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TOMOYO Linux Cross Reference
Linux/fs/dcache.c

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Diff markup

Differences between /fs/dcache.c (Version linux-6.12-rc7) and /fs/dcache.c (Version linux-5.13.19)


  1 // SPDX-License-Identifier: GPL-2.0-only            1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*                                                  2 /*
  3  * fs/dcache.c                                      3  * fs/dcache.c
  4  *                                                  4  *
  5  * Complete reimplementation                        5  * Complete reimplementation
  6  * (C) 1997 Thomas Schoebel-Theuer,                 6  * (C) 1997 Thomas Schoebel-Theuer,
  7  * with heavy changes by Linus Torvalds             7  * with heavy changes by Linus Torvalds
  8  */                                                 8  */
  9                                                     9 
 10 /*                                                 10 /*
 11  * Notes on the allocation strategy:               11  * Notes on the allocation strategy:
 12  *                                                 12  *
 13  * The dcache is a master of the icache - when     13  * The dcache is a master of the icache - whenever a dcache entry
 14  * exists, the inode will always exist. "iput(     14  * exists, the inode will always exist. "iput()" is done either when
 15  * the dcache entry is deleted or garbage coll     15  * the dcache entry is deleted or garbage collected.
 16  */                                                16  */
 17                                                    17 
 18 #include <linux/ratelimit.h>                       18 #include <linux/ratelimit.h>
 19 #include <linux/string.h>                          19 #include <linux/string.h>
 20 #include <linux/mm.h>                              20 #include <linux/mm.h>
 21 #include <linux/fs.h>                              21 #include <linux/fs.h>
 22 #include <linux/fscrypt.h>                         22 #include <linux/fscrypt.h>
 23 #include <linux/fsnotify.h>                        23 #include <linux/fsnotify.h>
 24 #include <linux/slab.h>                            24 #include <linux/slab.h>
 25 #include <linux/init.h>                            25 #include <linux/init.h>
 26 #include <linux/hash.h>                            26 #include <linux/hash.h>
 27 #include <linux/cache.h>                           27 #include <linux/cache.h>
 28 #include <linux/export.h>                          28 #include <linux/export.h>
 29 #include <linux/security.h>                        29 #include <linux/security.h>
 30 #include <linux/seqlock.h>                         30 #include <linux/seqlock.h>
 31 #include <linux/memblock.h>                        31 #include <linux/memblock.h>
 32 #include <linux/bit_spinlock.h>                    32 #include <linux/bit_spinlock.h>
 33 #include <linux/rculist_bl.h>                      33 #include <linux/rculist_bl.h>
 34 #include <linux/list_lru.h>                        34 #include <linux/list_lru.h>
 35 #include "internal.h"                              35 #include "internal.h"
 36 #include "mount.h"                                 36 #include "mount.h"
 37                                                    37 
 38 #include <asm/runtime-const.h>                 << 
 39                                                << 
 40 /*                                                 38 /*
 41  * Usage:                                          39  * Usage:
 42  * dcache->d_inode->i_lock protects:               40  * dcache->d_inode->i_lock protects:
 43  *   - i_dentry, d_u.d_alias, d_inode of alias     41  *   - i_dentry, d_u.d_alias, d_inode of aliases
 44  * dcache_hash_bucket lock protects:               42  * dcache_hash_bucket lock protects:
 45  *   - the dcache hash table                       43  *   - the dcache hash table
 46  * s_roots bl list spinlock protects:              44  * s_roots bl list spinlock protects:
 47  *   - the s_roots list (see __d_drop)             45  *   - the s_roots list (see __d_drop)
 48  * dentry->d_sb->s_dentry_lru_lock protects:       46  * dentry->d_sb->s_dentry_lru_lock protects:
 49  *   - the dcache lru lists and counters           47  *   - the dcache lru lists and counters
 50  * d_lock protects:                                48  * d_lock protects:
 51  *   - d_flags                                     49  *   - d_flags
 52  *   - d_name                                      50  *   - d_name
 53  *   - d_lru                                       51  *   - d_lru
 54  *   - d_count                                     52  *   - d_count
 55  *   - d_unhashed()                                53  *   - d_unhashed()
 56  *   - d_parent and d_chilren                  !!  54  *   - d_parent and d_subdirs
 57  *   - childrens' d_sib and d_parent           !!  55  *   - childrens' d_child and d_parent
 58  *   - d_u.d_alias, d_inode                        56  *   - d_u.d_alias, d_inode
 59  *                                                 57  *
 60  * Ordering:                                       58  * Ordering:
 61  * dentry->d_inode->i_lock                         59  * dentry->d_inode->i_lock
 62  *   dentry->d_lock                                60  *   dentry->d_lock
 63  *     dentry->d_sb->s_dentry_lru_lock             61  *     dentry->d_sb->s_dentry_lru_lock
 64  *     dcache_hash_bucket lock                     62  *     dcache_hash_bucket lock
 65  *     s_roots lock                                63  *     s_roots lock
 66  *                                                 64  *
 67  * If there is an ancestor relationship:           65  * If there is an ancestor relationship:
 68  * dentry->d_parent->...->d_parent->d_lock         66  * dentry->d_parent->...->d_parent->d_lock
 69  *   ...                                           67  *   ...
 70  *     dentry->d_parent->d_lock                    68  *     dentry->d_parent->d_lock
 71  *       dentry->d_lock                            69  *       dentry->d_lock
 72  *                                                 70  *
 73  * If no ancestor relationship:                    71  * If no ancestor relationship:
 74  * arbitrary, since it's serialized on rename_     72  * arbitrary, since it's serialized on rename_lock
 75  */                                                73  */
 76 int sysctl_vfs_cache_pressure __read_mostly =      74 int sysctl_vfs_cache_pressure __read_mostly = 100;
 77 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);      75 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
 78                                                    76 
 79 __cacheline_aligned_in_smp DEFINE_SEQLOCK(rena     77 __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);
 80                                                    78 
 81 EXPORT_SYMBOL(rename_lock);                        79 EXPORT_SYMBOL(rename_lock);
 82                                                    80 
 83 static struct kmem_cache *dentry_cache __ro_af !!  81 static struct kmem_cache *dentry_cache __read_mostly;
 84                                                    82 
 85 const struct qstr empty_name = QSTR_INIT("", 0     83 const struct qstr empty_name = QSTR_INIT("", 0);
 86 EXPORT_SYMBOL(empty_name);                         84 EXPORT_SYMBOL(empty_name);
 87 const struct qstr slash_name = QSTR_INIT("/",      85 const struct qstr slash_name = QSTR_INIT("/", 1);
 88 EXPORT_SYMBOL(slash_name);                         86 EXPORT_SYMBOL(slash_name);
 89 const struct qstr dotdot_name = QSTR_INIT(".."     87 const struct qstr dotdot_name = QSTR_INIT("..", 2);
 90 EXPORT_SYMBOL(dotdot_name);                        88 EXPORT_SYMBOL(dotdot_name);
 91                                                    89 
 92 /*                                                 90 /*
 93  * This is the single most critical data struc     91  * This is the single most critical data structure when it comes
 94  * to the dcache: the hashtable for lookups. S     92  * to the dcache: the hashtable for lookups. Somebody should try
 95  * to make this good - I've just made it work.     93  * to make this good - I've just made it work.
 96  *                                                 94  *
 97  * This hash-function tries to avoid losing to     95  * This hash-function tries to avoid losing too many bits of hash
 98  * information, yet avoid using a prime hash-s     96  * information, yet avoid using a prime hash-size or similar.
 99  *                                             << 
100  * Marking the variables "used" ensures that t << 
101  * optimize them away completely on architectu << 
102  * constant infrastructure, this allows debugg << 
103  * values. But updating these values has no ef << 
104  */                                                97  */
105                                                    98 
106 static unsigned int d_hash_shift __ro_after_in !!  99 static unsigned int d_hash_shift __read_mostly;
107                                                   100 
108 static struct hlist_bl_head *dentry_hashtable  !! 101 static struct hlist_bl_head *dentry_hashtable __read_mostly;
109                                                   102 
110 static inline struct hlist_bl_head *d_hash(uns !! 103 static inline struct hlist_bl_head *d_hash(unsigned int hash)
111 {                                                 104 {
112         return runtime_const_ptr(dentry_hashta !! 105         return dentry_hashtable + (hash >> d_hash_shift);
113                 runtime_const_shift_right_32(h << 
114 }                                                 106 }
115                                                   107 
116 #define IN_LOOKUP_SHIFT 10                        108 #define IN_LOOKUP_SHIFT 10
117 static struct hlist_bl_head in_lookup_hashtabl    109 static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT];
118                                                   110 
119 static inline struct hlist_bl_head *in_lookup_    111 static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent,
120                                         unsign    112                                         unsigned int hash)
121 {                                                 113 {
122         hash += (unsigned long) parent / L1_CA    114         hash += (unsigned long) parent / L1_CACHE_BYTES;
123         return in_lookup_hashtable + hash_32(h    115         return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT);
124 }                                                 116 }
125                                                   117 
126 struct dentry_stat_t {                         !! 118 
127         long nr_dentry;                        !! 119 /* Statistics gathering. */
128         long nr_unused;                        !! 120 struct dentry_stat_t dentry_stat = {
129         long age_limit;         /* age in seco !! 121         .age_limit = 45,
130         long want_pages;        /* pages reque << 
131         long nr_negative;       /* # of unused << 
132         long dummy;             /* Reserved fo << 
133 };                                                122 };
134                                                   123 
135 static DEFINE_PER_CPU(long, nr_dentry);           124 static DEFINE_PER_CPU(long, nr_dentry);
136 static DEFINE_PER_CPU(long, nr_dentry_unused);    125 static DEFINE_PER_CPU(long, nr_dentry_unused);
137 static DEFINE_PER_CPU(long, nr_dentry_negative    126 static DEFINE_PER_CPU(long, nr_dentry_negative);
138                                                   127 
139 #if defined(CONFIG_SYSCTL) && defined(CONFIG_P    128 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
140 /* Statistics gathering. */                    << 
141 static struct dentry_stat_t dentry_stat = {    << 
142         .age_limit = 45,                       << 
143 };                                             << 
144                                                   129 
145 /*                                                130 /*
146  * Here we resort to our own counters instead     131  * Here we resort to our own counters instead of using generic per-cpu counters
147  * for consistency with what the vfs inode cod    132  * for consistency with what the vfs inode code does. We are expected to harvest
148  * better code and performance by having our o    133  * better code and performance by having our own specialized counters.
149  *                                                134  *
150  * Please note that the loop is done over all     135  * Please note that the loop is done over all possible CPUs, not over all online
151  * CPUs. The reason for this is that we don't     136  * CPUs. The reason for this is that we don't want to play games with CPUs going
152  * on and off. If one of them goes off, we wil    137  * on and off. If one of them goes off, we will just keep their counters.
153  *                                                138  *
154  * glommer: See cffbc8a for details, and if yo    139  * glommer: See cffbc8a for details, and if you ever intend to change this,
155  * please update all vfs counters to match.       140  * please update all vfs counters to match.
156  */                                               141  */
157 static long get_nr_dentry(void)                   142 static long get_nr_dentry(void)
158 {                                                 143 {
159         int i;                                    144         int i;
160         long sum = 0;                             145         long sum = 0;
161         for_each_possible_cpu(i)                  146         for_each_possible_cpu(i)
162                 sum += per_cpu(nr_dentry, i);     147                 sum += per_cpu(nr_dentry, i);
163         return sum < 0 ? 0 : sum;                 148         return sum < 0 ? 0 : sum;
164 }                                                 149 }
165                                                   150 
166 static long get_nr_dentry_unused(void)            151 static long get_nr_dentry_unused(void)
167 {                                                 152 {
168         int i;                                    153         int i;
169         long sum = 0;                             154         long sum = 0;
170         for_each_possible_cpu(i)                  155         for_each_possible_cpu(i)
171                 sum += per_cpu(nr_dentry_unuse    156                 sum += per_cpu(nr_dentry_unused, i);
172         return sum < 0 ? 0 : sum;                 157         return sum < 0 ? 0 : sum;
173 }                                                 158 }
174                                                   159 
175 static long get_nr_dentry_negative(void)          160 static long get_nr_dentry_negative(void)
176 {                                                 161 {
177         int i;                                    162         int i;
178         long sum = 0;                             163         long sum = 0;
179                                                   164 
180         for_each_possible_cpu(i)                  165         for_each_possible_cpu(i)
181                 sum += per_cpu(nr_dentry_negat    166                 sum += per_cpu(nr_dentry_negative, i);
182         return sum < 0 ? 0 : sum;                 167         return sum < 0 ? 0 : sum;
183 }                                                 168 }
184                                                   169 
185 static int proc_nr_dentry(const struct ctl_tab !! 170 int proc_nr_dentry(struct ctl_table *table, int write, void *buffer,
186                           size_t *lenp, loff_t !! 171                    size_t *lenp, loff_t *ppos)
187 {                                                 172 {
188         dentry_stat.nr_dentry = get_nr_dentry(    173         dentry_stat.nr_dentry = get_nr_dentry();
189         dentry_stat.nr_unused = get_nr_dentry_    174         dentry_stat.nr_unused = get_nr_dentry_unused();
190         dentry_stat.nr_negative = get_nr_dentr    175         dentry_stat.nr_negative = get_nr_dentry_negative();
191         return proc_doulongvec_minmax(table, w    176         return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
192 }                                                 177 }
193                                                << 
194 static struct ctl_table fs_dcache_sysctls[] =  << 
195         {                                      << 
196                 .procname       = "dentry-stat << 
197                 .data           = &dentry_stat << 
198                 .maxlen         = 6*sizeof(lon << 
199                 .mode           = 0444,        << 
200                 .proc_handler   = proc_nr_dent << 
201         },                                     << 
202 };                                             << 
203                                                << 
204 static int __init init_fs_dcache_sysctls(void) << 
205 {                                              << 
206         register_sysctl_init("fs", fs_dcache_s << 
207         return 0;                              << 
208 }                                              << 
209 fs_initcall(init_fs_dcache_sysctls);           << 
210 #endif                                            178 #endif
211                                                   179 
212 /*                                                180 /*
213  * Compare 2 name strings, return 0 if they ma    181  * Compare 2 name strings, return 0 if they match, otherwise non-zero.
214  * The strings are both count bytes long, and     182  * The strings are both count bytes long, and count is non-zero.
215  */                                               183  */
216 #ifdef CONFIG_DCACHE_WORD_ACCESS                  184 #ifdef CONFIG_DCACHE_WORD_ACCESS
217                                                   185 
218 #include <asm/word-at-a-time.h>                   186 #include <asm/word-at-a-time.h>
219 /*                                                187 /*
220  * NOTE! 'cs' and 'scount' come from a dentry,    188  * NOTE! 'cs' and 'scount' come from a dentry, so it has a
221  * aligned allocation for this particular comp    189  * aligned allocation for this particular component. We don't
222  * strictly need the load_unaligned_zeropad()     190  * strictly need the load_unaligned_zeropad() safety, but it
223  * doesn't hurt either.                           191  * doesn't hurt either.
224  *                                                192  *
225  * In contrast, 'ct' and 'tcount' can be from     193  * In contrast, 'ct' and 'tcount' can be from a pathname, and do
226  * need the careful unaligned handling.           194  * need the careful unaligned handling.
227  */                                               195  */
228 static inline int dentry_string_cmp(const unsi    196 static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
229 {                                                 197 {
230         unsigned long a,b,mask;                   198         unsigned long a,b,mask;
231                                                   199 
232         for (;;) {                                200         for (;;) {
233                 a = read_word_at_a_time(cs);      201                 a = read_word_at_a_time(cs);
234                 b = load_unaligned_zeropad(ct)    202                 b = load_unaligned_zeropad(ct);
235                 if (tcount < sizeof(unsigned l    203                 if (tcount < sizeof(unsigned long))
236                         break;                    204                         break;
237                 if (unlikely(a != b))             205                 if (unlikely(a != b))
238                         return 1;                 206                         return 1;
239                 cs += sizeof(unsigned long);      207                 cs += sizeof(unsigned long);
240                 ct += sizeof(unsigned long);      208                 ct += sizeof(unsigned long);
241                 tcount -= sizeof(unsigned long    209                 tcount -= sizeof(unsigned long);
242                 if (!tcount)                      210                 if (!tcount)
243                         return 0;                 211                         return 0;
244         }                                         212         }
245         mask = bytemask_from_count(tcount);       213         mask = bytemask_from_count(tcount);
246         return unlikely(!!((a ^ b) & mask));      214         return unlikely(!!((a ^ b) & mask));
247 }                                                 215 }
248                                                   216 
249 #else                                             217 #else
250                                                   218 
251 static inline int dentry_string_cmp(const unsi    219 static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
252 {                                                 220 {
253         do {                                      221         do {
254                 if (*cs != *ct)                   222                 if (*cs != *ct)
255                         return 1;                 223                         return 1;
256                 cs++;                             224                 cs++;
257                 ct++;                             225                 ct++;
258                 tcount--;                         226                 tcount--;
259         } while (tcount);                         227         } while (tcount);
260         return 0;                                 228         return 0;
261 }                                                 229 }
262                                                   230 
263 #endif                                            231 #endif
264                                                   232 
265 static inline int dentry_cmp(const struct dent    233 static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount)
266 {                                                 234 {
267         /*                                        235         /*
268          * Be careful about RCU walk racing wi    236          * Be careful about RCU walk racing with rename:
269          * use 'READ_ONCE' to fetch the name p    237          * use 'READ_ONCE' to fetch the name pointer.
270          *                                        238          *
271          * NOTE! Even if a rename will mean th    239          * NOTE! Even if a rename will mean that the length
272          * was not loaded atomically, we don't    240          * was not loaded atomically, we don't care. The
273          * RCU walk will check the sequence co    241          * RCU walk will check the sequence count eventually,
274          * and catch it. And we won't overrun     242          * and catch it. And we won't overrun the buffer,
275          * because we're reading the name poin    243          * because we're reading the name pointer atomically,
276          * and a dentry name is guaranteed to     244          * and a dentry name is guaranteed to be properly
277          * terminated with a NUL byte.            245          * terminated with a NUL byte.
278          *                                        246          *
279          * End result: even if 'len' is wrong,    247          * End result: even if 'len' is wrong, we'll exit
280          * early because the data cannot match    248          * early because the data cannot match (there can
281          * be no NUL in the ct/tcount data)       249          * be no NUL in the ct/tcount data)
282          */                                       250          */
283         const unsigned char *cs = READ_ONCE(de    251         const unsigned char *cs = READ_ONCE(dentry->d_name.name);
284                                                   252 
285         return dentry_string_cmp(cs, ct, tcoun    253         return dentry_string_cmp(cs, ct, tcount);
286 }                                                 254 }
287                                                   255 
288 struct external_name {                            256 struct external_name {
289         union {                                   257         union {
290                 atomic_t count;                   258                 atomic_t count;
291                 struct rcu_head head;             259                 struct rcu_head head;
292         } u;                                      260         } u;
293         unsigned char name[];                     261         unsigned char name[];
294 };                                                262 };
295                                                   263 
296 static inline struct external_name *external_n    264 static inline struct external_name *external_name(struct dentry *dentry)
297 {                                                 265 {
298         return container_of(dentry->d_name.nam    266         return container_of(dentry->d_name.name, struct external_name, name[0]);
299 }                                                 267 }
300                                                   268 
301 static void __d_free(struct rcu_head *head)       269 static void __d_free(struct rcu_head *head)
302 {                                                 270 {
303         struct dentry *dentry = container_of(h    271         struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
304                                                   272 
305         kmem_cache_free(dentry_cache, dentry);    273         kmem_cache_free(dentry_cache, dentry); 
306 }                                                 274 }
307                                                   275 
308 static void __d_free_external(struct rcu_head     276 static void __d_free_external(struct rcu_head *head)
309 {                                                 277 {
310         struct dentry *dentry = container_of(h    278         struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
311         kfree(external_name(dentry));             279         kfree(external_name(dentry));
312         kmem_cache_free(dentry_cache, dentry);    280         kmem_cache_free(dentry_cache, dentry);
313 }                                                 281 }
314                                                   282 
315 static inline int dname_external(const struct     283 static inline int dname_external(const struct dentry *dentry)
316 {                                                 284 {
317         return dentry->d_name.name != dentry->    285         return dentry->d_name.name != dentry->d_iname;
318 }                                                 286 }
319                                                   287 
320 void take_dentry_name_snapshot(struct name_sna    288 void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry)
321 {                                                 289 {
322         spin_lock(&dentry->d_lock);               290         spin_lock(&dentry->d_lock);
323         name->name = dentry->d_name;              291         name->name = dentry->d_name;
324         if (unlikely(dname_external(dentry)))     292         if (unlikely(dname_external(dentry))) {
325                 atomic_inc(&external_name(dent    293                 atomic_inc(&external_name(dentry)->u.count);
326         } else {                                  294         } else {
327                 memcpy(name->inline_name, dent    295                 memcpy(name->inline_name, dentry->d_iname,
328                        dentry->d_name.len + 1)    296                        dentry->d_name.len + 1);
329                 name->name.name = name->inline    297                 name->name.name = name->inline_name;
330         }                                         298         }
331         spin_unlock(&dentry->d_lock);             299         spin_unlock(&dentry->d_lock);
332 }                                                 300 }
333 EXPORT_SYMBOL(take_dentry_name_snapshot);         301 EXPORT_SYMBOL(take_dentry_name_snapshot);
334                                                   302 
335 void release_dentry_name_snapshot(struct name_    303 void release_dentry_name_snapshot(struct name_snapshot *name)
336 {                                                 304 {
337         if (unlikely(name->name.name != name->    305         if (unlikely(name->name.name != name->inline_name)) {
338                 struct external_name *p;          306                 struct external_name *p;
339                 p = container_of(name->name.na    307                 p = container_of(name->name.name, struct external_name, name[0]);
340                 if (unlikely(atomic_dec_and_te    308                 if (unlikely(atomic_dec_and_test(&p->u.count)))
341                         kfree_rcu(p, u.head);     309                         kfree_rcu(p, u.head);
342         }                                         310         }
343 }                                                 311 }
344 EXPORT_SYMBOL(release_dentry_name_snapshot);      312 EXPORT_SYMBOL(release_dentry_name_snapshot);
345                                                   313 
346 static inline void __d_set_inode_and_type(stru    314 static inline void __d_set_inode_and_type(struct dentry *dentry,
347                                           stru    315                                           struct inode *inode,
348                                           unsi    316                                           unsigned type_flags)
349 {                                                 317 {
350         unsigned flags;                           318         unsigned flags;
351                                                   319 
352         dentry->d_inode = inode;                  320         dentry->d_inode = inode;
353         flags = READ_ONCE(dentry->d_flags);       321         flags = READ_ONCE(dentry->d_flags);
354         flags &= ~DCACHE_ENTRY_TYPE;           !! 322         flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
355         flags |= type_flags;                      323         flags |= type_flags;
356         smp_store_release(&dentry->d_flags, fl    324         smp_store_release(&dentry->d_flags, flags);
357 }                                                 325 }
358                                                   326 
359 static inline void __d_clear_type_and_inode(st    327 static inline void __d_clear_type_and_inode(struct dentry *dentry)
360 {                                                 328 {
361         unsigned flags = READ_ONCE(dentry->d_f    329         unsigned flags = READ_ONCE(dentry->d_flags);
362                                                   330 
363         flags &= ~DCACHE_ENTRY_TYPE;           !! 331         flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
364         WRITE_ONCE(dentry->d_flags, flags);       332         WRITE_ONCE(dentry->d_flags, flags);
365         dentry->d_inode = NULL;                   333         dentry->d_inode = NULL;
366         /*                                     !! 334         if (dentry->d_flags & DCACHE_LRU_LIST)
367          * The negative counter only tracks de << 
368          * d_lru is on another list.           << 
369          */                                    << 
370         if ((flags & (DCACHE_LRU_LIST|DCACHE_S << 
371                 this_cpu_inc(nr_dentry_negativ    335                 this_cpu_inc(nr_dentry_negative);
372 }                                                 336 }
373                                                   337 
374 static void dentry_free(struct dentry *dentry)    338 static void dentry_free(struct dentry *dentry)
375 {                                                 339 {
376         WARN_ON(!hlist_unhashed(&dentry->d_u.d    340         WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
377         if (unlikely(dname_external(dentry)))     341         if (unlikely(dname_external(dentry))) {
378                 struct external_name *p = exte    342                 struct external_name *p = external_name(dentry);
379                 if (likely(atomic_dec_and_test    343                 if (likely(atomic_dec_and_test(&p->u.count))) {
380                         call_rcu(&dentry->d_u.    344                         call_rcu(&dentry->d_u.d_rcu, __d_free_external);
381                         return;                   345                         return;
382                 }                                 346                 }
383         }                                         347         }
384         /* if dentry was never visible to RCU,    348         /* if dentry was never visible to RCU, immediate free is OK */
385         if (dentry->d_flags & DCACHE_NORCU)       349         if (dentry->d_flags & DCACHE_NORCU)
386                 __d_free(&dentry->d_u.d_rcu);     350                 __d_free(&dentry->d_u.d_rcu);
387         else                                      351         else
388                 call_rcu(&dentry->d_u.d_rcu, _    352                 call_rcu(&dentry->d_u.d_rcu, __d_free);
389 }                                                 353 }
390                                                   354 
391 /*                                                355 /*
392  * Release the dentry's inode, using the files    356  * Release the dentry's inode, using the filesystem
393  * d_iput() operation if defined.                 357  * d_iput() operation if defined.
394  */                                               358  */
395 static void dentry_unlink_inode(struct dentry     359 static void dentry_unlink_inode(struct dentry * dentry)
396         __releases(dentry->d_lock)                360         __releases(dentry->d_lock)
397         __releases(dentry->d_inode->i_lock)       361         __releases(dentry->d_inode->i_lock)
398 {                                                 362 {
399         struct inode *inode = dentry->d_inode;    363         struct inode *inode = dentry->d_inode;
400                                                   364 
401         raw_write_seqcount_begin(&dentry->d_se    365         raw_write_seqcount_begin(&dentry->d_seq);
402         __d_clear_type_and_inode(dentry);         366         __d_clear_type_and_inode(dentry);
403         hlist_del_init(&dentry->d_u.d_alias);     367         hlist_del_init(&dentry->d_u.d_alias);
404         raw_write_seqcount_end(&dentry->d_seq)    368         raw_write_seqcount_end(&dentry->d_seq);
405         spin_unlock(&dentry->d_lock);             369         spin_unlock(&dentry->d_lock);
406         spin_unlock(&inode->i_lock);              370         spin_unlock(&inode->i_lock);
407         if (!inode->i_nlink)                      371         if (!inode->i_nlink)
408                 fsnotify_inoderemove(inode);      372                 fsnotify_inoderemove(inode);
409         if (dentry->d_op && dentry->d_op->d_ip    373         if (dentry->d_op && dentry->d_op->d_iput)
410                 dentry->d_op->d_iput(dentry, i    374                 dentry->d_op->d_iput(dentry, inode);
411         else                                      375         else
412                 iput(inode);                      376                 iput(inode);
413 }                                                 377 }
414                                                   378 
415 /*                                                379 /*
416  * The DCACHE_LRU_LIST bit is set whenever the    380  * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
417  * is in use - which includes both the "real"     381  * is in use - which includes both the "real" per-superblock
418  * LRU list _and_ the DCACHE_SHRINK_LIST use.     382  * LRU list _and_ the DCACHE_SHRINK_LIST use.
419  *                                                383  *
420  * The DCACHE_SHRINK_LIST bit is set whenever     384  * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
421  * on the shrink list (ie not on the superbloc    385  * on the shrink list (ie not on the superblock LRU list).
422  *                                                386  *
423  * The per-cpu "nr_dentry_unused" counters are    387  * The per-cpu "nr_dentry_unused" counters are updated with
424  * the DCACHE_LRU_LIST bit.                       388  * the DCACHE_LRU_LIST bit.
425  *                                                389  *
426  * The per-cpu "nr_dentry_negative" counters a    390  * The per-cpu "nr_dentry_negative" counters are only updated
427  * when deleted from or added to the per-super    391  * when deleted from or added to the per-superblock LRU list, not
428  * from/to the shrink list. That is to avoid a    392  * from/to the shrink list. That is to avoid an unneeded dec/inc
429  * pair when moving from LRU to shrink list in    393  * pair when moving from LRU to shrink list in select_collect().
430  *                                                394  *
431  * These helper functions make sure we always     395  * These helper functions make sure we always follow the
432  * rules. d_lock must be held by the caller.      396  * rules. d_lock must be held by the caller.
433  */                                               397  */
434 #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE((    398 #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
435 static void d_lru_add(struct dentry *dentry)      399 static void d_lru_add(struct dentry *dentry)
436 {                                                 400 {
437         D_FLAG_VERIFY(dentry, 0);                 401         D_FLAG_VERIFY(dentry, 0);
438         dentry->d_flags |= DCACHE_LRU_LIST;       402         dentry->d_flags |= DCACHE_LRU_LIST;
439         this_cpu_inc(nr_dentry_unused);           403         this_cpu_inc(nr_dentry_unused);
440         if (d_is_negative(dentry))                404         if (d_is_negative(dentry))
441                 this_cpu_inc(nr_dentry_negativ    405                 this_cpu_inc(nr_dentry_negative);
442         WARN_ON_ONCE(!list_lru_add_obj(        !! 406         WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
443                         &dentry->d_sb->s_dentr << 
444 }                                                 407 }
445                                                   408 
446 static void d_lru_del(struct dentry *dentry)      409 static void d_lru_del(struct dentry *dentry)
447 {                                                 410 {
448         D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST)    411         D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
449         dentry->d_flags &= ~DCACHE_LRU_LIST;      412         dentry->d_flags &= ~DCACHE_LRU_LIST;
450         this_cpu_dec(nr_dentry_unused);           413         this_cpu_dec(nr_dentry_unused);
451         if (d_is_negative(dentry))                414         if (d_is_negative(dentry))
452                 this_cpu_dec(nr_dentry_negativ    415                 this_cpu_dec(nr_dentry_negative);
453         WARN_ON_ONCE(!list_lru_del_obj(        !! 416         WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
454                         &dentry->d_sb->s_dentr << 
455 }                                                 417 }
456                                                   418 
457 static void d_shrink_del(struct dentry *dentry    419 static void d_shrink_del(struct dentry *dentry)
458 {                                                 420 {
459         D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LI    421         D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
460         list_del_init(&dentry->d_lru);            422         list_del_init(&dentry->d_lru);
461         dentry->d_flags &= ~(DCACHE_SHRINK_LIS    423         dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
462         this_cpu_dec(nr_dentry_unused);           424         this_cpu_dec(nr_dentry_unused);
463 }                                                 425 }
464                                                   426 
465 static void d_shrink_add(struct dentry *dentry    427 static void d_shrink_add(struct dentry *dentry, struct list_head *list)
466 {                                                 428 {
467         D_FLAG_VERIFY(dentry, 0);                 429         D_FLAG_VERIFY(dentry, 0);
468         list_add(&dentry->d_lru, list);           430         list_add(&dentry->d_lru, list);
469         dentry->d_flags |= DCACHE_SHRINK_LIST     431         dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST;
470         this_cpu_inc(nr_dentry_unused);           432         this_cpu_inc(nr_dentry_unused);
471 }                                                 433 }
472                                                   434 
473 /*                                                435 /*
474  * These can only be called under the global L    436  * These can only be called under the global LRU lock, ie during the
475  * callback for freeing the LRU list. "isolate    437  * callback for freeing the LRU list. "isolate" removes it from the
476  * LRU lists entirely, while shrink_move moves    438  * LRU lists entirely, while shrink_move moves it to the indicated
477  * private list.                                  439  * private list.
478  */                                               440  */
479 static void d_lru_isolate(struct list_lru_one     441 static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry)
480 {                                                 442 {
481         D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST)    443         D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
482         dentry->d_flags &= ~DCACHE_LRU_LIST;      444         dentry->d_flags &= ~DCACHE_LRU_LIST;
483         this_cpu_dec(nr_dentry_unused);           445         this_cpu_dec(nr_dentry_unused);
484         if (d_is_negative(dentry))                446         if (d_is_negative(dentry))
485                 this_cpu_dec(nr_dentry_negativ    447                 this_cpu_dec(nr_dentry_negative);
486         list_lru_isolate(lru, &dentry->d_lru);    448         list_lru_isolate(lru, &dentry->d_lru);
487 }                                                 449 }
488                                                   450 
489 static void d_lru_shrink_move(struct list_lru_    451 static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry,
490                               struct list_head    452                               struct list_head *list)
491 {                                                 453 {
492         D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST)    454         D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
493         dentry->d_flags |= DCACHE_SHRINK_LIST;    455         dentry->d_flags |= DCACHE_SHRINK_LIST;
494         if (d_is_negative(dentry))                456         if (d_is_negative(dentry))
495                 this_cpu_dec(nr_dentry_negativ    457                 this_cpu_dec(nr_dentry_negative);
496         list_lru_isolate_move(lru, &dentry->d_    458         list_lru_isolate_move(lru, &dentry->d_lru, list);
497 }                                                 459 }
498                                                   460 
499 static void ___d_drop(struct dentry *dentry)      461 static void ___d_drop(struct dentry *dentry)
500 {                                                 462 {
501         struct hlist_bl_head *b;                  463         struct hlist_bl_head *b;
502         /*                                        464         /*
503          * Hashed dentries are normally on the    465          * Hashed dentries are normally on the dentry hashtable,
504          * with the exception of those newly a    466          * with the exception of those newly allocated by
505          * d_obtain_root, which are always IS_    467          * d_obtain_root, which are always IS_ROOT:
506          */                                       468          */
507         if (unlikely(IS_ROOT(dentry)))            469         if (unlikely(IS_ROOT(dentry)))
508                 b = &dentry->d_sb->s_roots;       470                 b = &dentry->d_sb->s_roots;
509         else                                      471         else
510                 b = d_hash(dentry->d_name.hash    472                 b = d_hash(dentry->d_name.hash);
511                                                   473 
512         hlist_bl_lock(b);                         474         hlist_bl_lock(b);
513         __hlist_bl_del(&dentry->d_hash);          475         __hlist_bl_del(&dentry->d_hash);
514         hlist_bl_unlock(b);                       476         hlist_bl_unlock(b);
515 }                                                 477 }
516                                                   478 
517 void __d_drop(struct dentry *dentry)              479 void __d_drop(struct dentry *dentry)
518 {                                                 480 {
519         if (!d_unhashed(dentry)) {                481         if (!d_unhashed(dentry)) {
520                 ___d_drop(dentry);                482                 ___d_drop(dentry);
521                 dentry->d_hash.pprev = NULL;      483                 dentry->d_hash.pprev = NULL;
522                 write_seqcount_invalidate(&den    484                 write_seqcount_invalidate(&dentry->d_seq);
523         }                                         485         }
524 }                                                 486 }
525 EXPORT_SYMBOL(__d_drop);                          487 EXPORT_SYMBOL(__d_drop);
526                                                   488 
527 /**                                               489 /**
528  * d_drop - drop a dentry                         490  * d_drop - drop a dentry
529  * @dentry: dentry to drop                        491  * @dentry: dentry to drop
530  *                                                492  *
531  * d_drop() unhashes the entry from the parent    493  * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
532  * be found through a VFS lookup any more. Not    494  * be found through a VFS lookup any more. Note that this is different from
533  * deleting the dentry - d_delete will try to     495  * deleting the dentry - d_delete will try to mark the dentry negative if
534  * possible, giving a successful _negative_ lo    496  * possible, giving a successful _negative_ lookup, while d_drop will
535  * just make the cache lookup fail.               497  * just make the cache lookup fail.
536  *                                                498  *
537  * d_drop() is used mainly for stuff that want    499  * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
538  * reason (NFS timeouts or autofs deletes).       500  * reason (NFS timeouts or autofs deletes).
539  *                                                501  *
540  * __d_drop requires dentry->d_lock               502  * __d_drop requires dentry->d_lock
541  *                                                503  *
542  * ___d_drop doesn't mark dentry as "unhashed"    504  * ___d_drop doesn't mark dentry as "unhashed"
543  * (dentry->d_hash.pprev will be LIST_POISON2,    505  * (dentry->d_hash.pprev will be LIST_POISON2, not NULL).
544  */                                               506  */
545 void d_drop(struct dentry *dentry)                507 void d_drop(struct dentry *dentry)
546 {                                                 508 {
547         spin_lock(&dentry->d_lock);               509         spin_lock(&dentry->d_lock);
548         __d_drop(dentry);                         510         __d_drop(dentry);
549         spin_unlock(&dentry->d_lock);             511         spin_unlock(&dentry->d_lock);
550 }                                                 512 }
551 EXPORT_SYMBOL(d_drop);                            513 EXPORT_SYMBOL(d_drop);
552                                                   514 
553 static inline void dentry_unlist(struct dentry !! 515 static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
554 {                                                 516 {
555         struct dentry *next;                      517         struct dentry *next;
556         /*                                        518         /*
557          * Inform d_walk() and shrink_dentry_l    519          * Inform d_walk() and shrink_dentry_list() that we are no longer
558          * attached to the dentry tree            520          * attached to the dentry tree
559          */                                       521          */
560         dentry->d_flags |= DCACHE_DENTRY_KILLE    522         dentry->d_flags |= DCACHE_DENTRY_KILLED;
561         if (unlikely(hlist_unhashed(&dentry->d !! 523         if (unlikely(list_empty(&dentry->d_child)))
562                 return;                           524                 return;
563         __hlist_del(&dentry->d_sib);           !! 525         __list_del_entry(&dentry->d_child);
564         /*                                        526         /*
565          * Cursors can move around the list of    527          * Cursors can move around the list of children.  While we'd been
566          * a normal list member, it didn't mat !! 528          * a normal list member, it didn't matter - ->d_child.next would've
567          * been updated.  However, from now on    529          * been updated.  However, from now on it won't be and for the
568          * things like d_walk() it might end u    530          * things like d_walk() it might end up with a nasty surprise.
569          * Normally d_walk() doesn't care abou    531          * Normally d_walk() doesn't care about cursors moving around -
570          * ->d_lock on parent prevents that an    532          * ->d_lock on parent prevents that and since a cursor has no children
571          * of its own, we get through it witho    533          * of its own, we get through it without ever unlocking the parent.
572          * There is one exception, though - if    534          * There is one exception, though - if we ascend from a child that
573          * gets killed as soon as we unlock it    535          * gets killed as soon as we unlock it, the next sibling is found
574          * using the value left in its ->d_sib !! 536          * using the value left in its ->d_child.next.  And if _that_
575          * pointed to a cursor, and cursor got    537          * pointed to a cursor, and cursor got moved (e.g. by lseek())
576          * before d_walk() regains parent->d_l    538          * before d_walk() regains parent->d_lock, we'll end up skipping
577          * everything the cursor had been move    539          * everything the cursor had been moved past.
578          *                                        540          *
579          * Solution: make sure that the pointe !! 541          * Solution: make sure that the pointer left behind in ->d_child.next
580          * points to something that won't be m    542          * points to something that won't be moving around.  I.e. skip the
581          * cursors.                               543          * cursors.
582          */                                       544          */
583         while (dentry->d_sib.next) {           !! 545         while (dentry->d_child.next != &parent->d_subdirs) {
584                 next = hlist_entry(dentry->d_s !! 546                 next = list_entry(dentry->d_child.next, struct dentry, d_child);
585                 if (likely(!(next->d_flags & D    547                 if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR)))
586                         break;                    548                         break;
587                 dentry->d_sib.next = next->d_s !! 549                 dentry->d_child.next = next->d_child.next;
588         }                                         550         }
589 }                                                 551 }
590                                                   552 
591 static struct dentry *__dentry_kill(struct den !! 553 static void __dentry_kill(struct dentry *dentry)
592 {                                                 554 {
593         struct dentry *parent = NULL;             555         struct dentry *parent = NULL;
594         bool can_free = true;                     556         bool can_free = true;
                                                   >> 557         if (!IS_ROOT(dentry))
                                                   >> 558                 parent = dentry->d_parent;
595                                                   559 
596         /*                                        560         /*
597          * The dentry is now unrecoverably dea    561          * The dentry is now unrecoverably dead to the world.
598          */                                       562          */
599         lockref_mark_dead(&dentry->d_lockref);    563         lockref_mark_dead(&dentry->d_lockref);
600                                                   564 
601         /*                                        565         /*
602          * inform the fs via d_prune that this    566          * inform the fs via d_prune that this dentry is about to be
603          * unhashed and destroyed.                567          * unhashed and destroyed.
604          */                                       568          */
605         if (dentry->d_flags & DCACHE_OP_PRUNE)    569         if (dentry->d_flags & DCACHE_OP_PRUNE)
606                 dentry->d_op->d_prune(dentry);    570                 dentry->d_op->d_prune(dentry);
607                                                   571 
608         if (dentry->d_flags & DCACHE_LRU_LIST)    572         if (dentry->d_flags & DCACHE_LRU_LIST) {
609                 if (!(dentry->d_flags & DCACHE    573                 if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
610                         d_lru_del(dentry);        574                         d_lru_del(dentry);
611         }                                         575         }
612         /* if it was on the hash then remove i    576         /* if it was on the hash then remove it */
613         __d_drop(dentry);                         577         __d_drop(dentry);
                                                   >> 578         dentry_unlist(dentry, parent);
                                                   >> 579         if (parent)
                                                   >> 580                 spin_unlock(&parent->d_lock);
614         if (dentry->d_inode)                      581         if (dentry->d_inode)
615                 dentry_unlink_inode(dentry);      582                 dentry_unlink_inode(dentry);
616         else                                      583         else
617                 spin_unlock(&dentry->d_lock);     584                 spin_unlock(&dentry->d_lock);
618         this_cpu_dec(nr_dentry);                  585         this_cpu_dec(nr_dentry);
619         if (dentry->d_op && dentry->d_op->d_re    586         if (dentry->d_op && dentry->d_op->d_release)
620                 dentry->d_op->d_release(dentry    587                 dentry->d_op->d_release(dentry);
621                                                   588 
622         cond_resched();                        !! 589         spin_lock(&dentry->d_lock);
623         /* now that it's negative, ->d_parent  !! 590         if (dentry->d_flags & DCACHE_SHRINK_LIST) {
624         if (!IS_ROOT(dentry)) {                !! 591                 dentry->d_flags |= DCACHE_MAY_FREE;
625                 parent = dentry->d_parent;     << 
626                 spin_lock(&parent->d_lock);    << 
627         }                                      << 
628         spin_lock_nested(&dentry->d_lock, DENT << 
629         dentry_unlist(dentry);                 << 
630         if (dentry->d_flags & DCACHE_SHRINK_LI << 
631                 can_free = false;                 592                 can_free = false;
                                                   >> 593         }
632         spin_unlock(&dentry->d_lock);             594         spin_unlock(&dentry->d_lock);
633         if (likely(can_free))                     595         if (likely(can_free))
634                 dentry_free(dentry);              596                 dentry_free(dentry);
635         if (parent && --parent->d_lockref.coun !! 597         cond_resched();
                                                   >> 598 }
                                                   >> 599 
                                                   >> 600 static struct dentry *__lock_parent(struct dentry *dentry)
                                                   >> 601 {
                                                   >> 602         struct dentry *parent;
                                                   >> 603         rcu_read_lock();
                                                   >> 604         spin_unlock(&dentry->d_lock);
                                                   >> 605 again:
                                                   >> 606         parent = READ_ONCE(dentry->d_parent);
                                                   >> 607         spin_lock(&parent->d_lock);
                                                   >> 608         /*
                                                   >> 609          * We can't blindly lock dentry until we are sure
                                                   >> 610          * that we won't violate the locking order.
                                                   >> 611          * Any changes of dentry->d_parent must have
                                                   >> 612          * been done with parent->d_lock held, so
                                                   >> 613          * spin_lock() above is enough of a barrier
                                                   >> 614          * for checking if it's still our child.
                                                   >> 615          */
                                                   >> 616         if (unlikely(parent != dentry->d_parent)) {
636                 spin_unlock(&parent->d_lock);     617                 spin_unlock(&parent->d_lock);
637                 return NULL;                   !! 618                 goto again;
638         }                                         619         }
                                                   >> 620         rcu_read_unlock();
                                                   >> 621         if (parent != dentry)
                                                   >> 622                 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
                                                   >> 623         else
                                                   >> 624                 parent = NULL;
639         return parent;                            625         return parent;
640 }                                                 626 }
641                                                   627 
642 /*                                             !! 628 static inline struct dentry *lock_parent(struct dentry *dentry)
643  * Lock a dentry for feeding it to __dentry_ki << 
644  * Called under rcu_read_lock() and dentry->d_ << 
645  * guarantees that nothing we access will be f << 
646  * Note that dentry is *not* protected from co << 
647  * d_delete(), etc.                            << 
648  *                                             << 
649  * Return false if dentry is busy.  Otherwise, << 
650  * that dentry's inode locked.                 << 
651  */                                            << 
652                                                << 
653 static bool lock_for_kill(struct dentry *dentr << 
654 {                                                 629 {
655         struct inode *inode = dentry->d_inode; !! 630         struct dentry *parent = dentry->d_parent;
656                                                !! 631         if (IS_ROOT(dentry))
657         if (unlikely(dentry->d_lockref.count)) !! 632                 return NULL;
658                 return false;                  !! 633         if (likely(spin_trylock(&parent->d_lock)))
659                                                !! 634                 return parent;
660         if (!inode || likely(spin_trylock(&ino !! 635         return __lock_parent(dentry);
661                 return true;                   << 
662                                                << 
663         do {                                   << 
664                 spin_unlock(&dentry->d_lock);  << 
665                 spin_lock(&inode->i_lock);     << 
666                 spin_lock(&dentry->d_lock);    << 
667                 if (likely(inode == dentry->d_ << 
668                         break;                 << 
669                 spin_unlock(&inode->i_lock);   << 
670                 inode = dentry->d_inode;       << 
671         } while (inode);                       << 
672         if (likely(!dentry->d_lockref.count))  << 
673                 return true;                   << 
674         if (inode)                             << 
675                 spin_unlock(&inode->i_lock);   << 
676         return false;                          << 
677 }                                                 636 }
678                                                   637 
679 /*                                             !! 638 static inline bool retain_dentry(struct dentry *dentry)
680  * Decide if dentry is worth retaining.  Usual << 
681  * locked; if not locked, we are more limited  << 
682  * without a lock.  False in this case means " << 
683  *                                             << 
684  * In case we aren't locked, these predicates  << 
685  * sufficient that at some point after we drop << 
686  * hashed and the flags had the proper value.  << 
687  * re-gotten a reference to the dentry and cha << 
688  * we can leave the dentry around with a zero  << 
689  */                                            << 
690 static inline bool retain_dentry(struct dentry << 
691 {                                                 639 {
692         unsigned int d_flags;                  !! 640         WARN_ON(d_in_lookup(dentry));
693                                                << 
694         smp_rmb();                             << 
695         d_flags = READ_ONCE(dentry->d_flags);  << 
696                                                   641 
697         // Unreachable? Nobody would be able t !! 642         /* Unreachable? Get rid of it */
698         if (unlikely(d_unhashed(dentry)))         643         if (unlikely(d_unhashed(dentry)))
699                 return false;                     644                 return false;
700                                                   645 
701         // Same if it's disconnected           !! 646         if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
702         if (unlikely(d_flags & DCACHE_DISCONNE << 
703                 return false;                     647                 return false;
704                                                   648 
705         // ->d_delete() might tell us not to b !! 649         if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
706         // ->d_lock; can't decide without it   !! 650                 if (dentry->d_op->d_delete(dentry))
707         if (unlikely(d_flags & DCACHE_OP_DELET << 
708                 if (!locked || dentry->d_op->d << 
709                         return false;             651                         return false;
710         }                                         652         }
711                                                   653 
712         // Explicitly told not to bother       !! 654         if (unlikely(dentry->d_flags & DCACHE_DONTCACHE))
713         if (unlikely(d_flags & DCACHE_DONTCACH << 
714                 return false;                     655                 return false;
715                                                   656 
716         // At this point it looks like we ough !! 657         /* retain; LRU fodder */
717         // need to do something - put it on LR !! 658         dentry->d_lockref.count--;
718         // and mark it referenced if it was on !! 659         if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
719         // Unfortunately, both actions require << 
720         // case we'd have to punt rather than  << 
721         if (unlikely(!(d_flags & DCACHE_LRU_LI << 
722                 if (!locked)                   << 
723                         return false;          << 
724                 d_lru_add(dentry);                660                 d_lru_add(dentry);
725         } else if (unlikely(!(d_flags & DCACHE !! 661         else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED)))
726                 if (!locked)                   << 
727                         return false;          << 
728                 dentry->d_flags |= DCACHE_REFE    662                 dentry->d_flags |= DCACHE_REFERENCED;
729         }                                      << 
730         return true;                              663         return true;
731 }                                                 664 }
732                                                   665 
733 void d_mark_dontcache(struct inode *inode)        666 void d_mark_dontcache(struct inode *inode)
734 {                                                 667 {
735         struct dentry *de;                        668         struct dentry *de;
736                                                   669 
737         spin_lock(&inode->i_lock);                670         spin_lock(&inode->i_lock);
738         hlist_for_each_entry(de, &inode->i_den    671         hlist_for_each_entry(de, &inode->i_dentry, d_u.d_alias) {
739                 spin_lock(&de->d_lock);           672                 spin_lock(&de->d_lock);
740                 de->d_flags |= DCACHE_DONTCACH    673                 de->d_flags |= DCACHE_DONTCACHE;
741                 spin_unlock(&de->d_lock);         674                 spin_unlock(&de->d_lock);
742         }                                         675         }
743         inode->i_state |= I_DONTCACHE;            676         inode->i_state |= I_DONTCACHE;
744         spin_unlock(&inode->i_lock);              677         spin_unlock(&inode->i_lock);
745 }                                                 678 }
746 EXPORT_SYMBOL(d_mark_dontcache);                  679 EXPORT_SYMBOL(d_mark_dontcache);
747                                                   680 
748 /*                                                681 /*
                                                   >> 682  * Finish off a dentry we've decided to kill.
                                                   >> 683  * dentry->d_lock must be held, returns with it unlocked.
                                                   >> 684  * Returns dentry requiring refcount drop, or NULL if we're done.
                                                   >> 685  */
                                                   >> 686 static struct dentry *dentry_kill(struct dentry *dentry)
                                                   >> 687         __releases(dentry->d_lock)
                                                   >> 688 {
                                                   >> 689         struct inode *inode = dentry->d_inode;
                                                   >> 690         struct dentry *parent = NULL;
                                                   >> 691 
                                                   >> 692         if (inode && unlikely(!spin_trylock(&inode->i_lock)))
                                                   >> 693                 goto slow_positive;
                                                   >> 694 
                                                   >> 695         if (!IS_ROOT(dentry)) {
                                                   >> 696                 parent = dentry->d_parent;
                                                   >> 697                 if (unlikely(!spin_trylock(&parent->d_lock))) {
                                                   >> 698                         parent = __lock_parent(dentry);
                                                   >> 699                         if (likely(inode || !dentry->d_inode))
                                                   >> 700                                 goto got_locks;
                                                   >> 701                         /* negative that became positive */
                                                   >> 702                         if (parent)
                                                   >> 703                                 spin_unlock(&parent->d_lock);
                                                   >> 704                         inode = dentry->d_inode;
                                                   >> 705                         goto slow_positive;
                                                   >> 706                 }
                                                   >> 707         }
                                                   >> 708         __dentry_kill(dentry);
                                                   >> 709         return parent;
                                                   >> 710 
                                                   >> 711 slow_positive:
                                                   >> 712         spin_unlock(&dentry->d_lock);
                                                   >> 713         spin_lock(&inode->i_lock);
                                                   >> 714         spin_lock(&dentry->d_lock);
                                                   >> 715         parent = lock_parent(dentry);
                                                   >> 716 got_locks:
                                                   >> 717         if (unlikely(dentry->d_lockref.count != 1)) {
                                                   >> 718                 dentry->d_lockref.count--;
                                                   >> 719         } else if (likely(!retain_dentry(dentry))) {
                                                   >> 720                 __dentry_kill(dentry);
                                                   >> 721                 return parent;
                                                   >> 722         }
                                                   >> 723         /* we are keeping it, after all */
                                                   >> 724         if (inode)
                                                   >> 725                 spin_unlock(&inode->i_lock);
                                                   >> 726         if (parent)
                                                   >> 727                 spin_unlock(&parent->d_lock);
                                                   >> 728         spin_unlock(&dentry->d_lock);
                                                   >> 729         return NULL;
                                                   >> 730 }
                                                   >> 731 
                                                   >> 732 /*
749  * Try to do a lockless dput(), and return whe    733  * Try to do a lockless dput(), and return whether that was successful.
750  *                                                734  *
751  * If unsuccessful, we return false, having al    735  * If unsuccessful, we return false, having already taken the dentry lock.
752  * In that case refcount is guaranteed to be z << 
753  * decided that it's not worth keeping around. << 
754  *                                                736  *
755  * The caller needs to hold the RCU read lock,    737  * The caller needs to hold the RCU read lock, so that the dentry is
756  * guaranteed to stay around even if the refco    738  * guaranteed to stay around even if the refcount goes down to zero!
757  */                                               739  */
758 static inline bool fast_dput(struct dentry *de    740 static inline bool fast_dput(struct dentry *dentry)
759 {                                                 741 {
760         int ret;                                  742         int ret;
                                                   >> 743         unsigned int d_flags;
                                                   >> 744 
                                                   >> 745         /*
                                                   >> 746          * If we have a d_op->d_delete() operation, we sould not
                                                   >> 747          * let the dentry count go to zero, so use "put_or_lock".
                                                   >> 748          */
                                                   >> 749         if (unlikely(dentry->d_flags & DCACHE_OP_DELETE))
                                                   >> 750                 return lockref_put_or_lock(&dentry->d_lockref);
761                                                   751 
762         /*                                        752         /*
763          * try to decrement the lockref optimi !! 753          * .. otherwise, we can try to just decrement the
                                                   >> 754          * lockref optimistically.
764          */                                       755          */
765         ret = lockref_put_return(&dentry->d_lo    756         ret = lockref_put_return(&dentry->d_lockref);
766                                                   757 
767         /*                                        758         /*
768          * If the lockref_put_return() failed     759          * If the lockref_put_return() failed due to the lock being held
769          * by somebody else, the fast path has    760          * by somebody else, the fast path has failed. We will need to
770          * get the lock, and then check the co    761          * get the lock, and then check the count again.
771          */                                       762          */
772         if (unlikely(ret < 0)) {                  763         if (unlikely(ret < 0)) {
773                 spin_lock(&dentry->d_lock);       764                 spin_lock(&dentry->d_lock);
774                 if (WARN_ON_ONCE(dentry->d_loc !! 765                 if (dentry->d_lockref.count > 1) {
                                                   >> 766                         dentry->d_lockref.count--;
775                         spin_unlock(&dentry->d    767                         spin_unlock(&dentry->d_lock);
776                         return true;              768                         return true;
777                 }                                 769                 }
778                 dentry->d_lockref.count--;     !! 770                 return false;
779                 goto locked;                   << 
780         }                                         771         }
781                                                   772 
782         /*                                        773         /*
783          * If we weren't the last ref, we're d    774          * If we weren't the last ref, we're done.
784          */                                       775          */
785         if (ret)                                  776         if (ret)
786                 return true;                      777                 return true;
787                                                   778 
788         /*                                        779         /*
789          * Can we decide that decrement of ref !! 780          * Careful, careful. The reference count went down
790          * taking the lock?  There's a very co !! 781          * to zero, but we don't hold the dentry lock, so
791          * dentry looks like it ought to be re !! 782          * somebody else could get it again, and do another
792          * to do.                              !! 783          * dput(), and we need to not race with that.
                                                   >> 784          *
                                                   >> 785          * However, there is a very special and common case
                                                   >> 786          * where we don't care, because there is nothing to
                                                   >> 787          * do: the dentry is still hashed, it does not have
                                                   >> 788          * a 'delete' op, and it's referenced and already on
                                                   >> 789          * the LRU list.
                                                   >> 790          *
                                                   >> 791          * NOTE! Since we aren't locked, these values are
                                                   >> 792          * not "stable". However, it is sufficient that at
                                                   >> 793          * some point after we dropped the reference the
                                                   >> 794          * dentry was hashed and the flags had the proper
                                                   >> 795          * value. Other dentry users may have re-gotten
                                                   >> 796          * a reference to the dentry and change that, but
                                                   >> 797          * our work is done - we can leave the dentry
                                                   >> 798          * around with a zero refcount.
                                                   >> 799          *
                                                   >> 800          * Nevertheless, there are two cases that we should kill
                                                   >> 801          * the dentry anyway.
                                                   >> 802          * 1. free disconnected dentries as soon as their refcount
                                                   >> 803          *    reached zero.
                                                   >> 804          * 2. free dentries if they should not be cached.
793          */                                       805          */
794         if (retain_dentry(dentry, false))      !! 806         smp_rmb();
                                                   >> 807         d_flags = READ_ONCE(dentry->d_flags);
                                                   >> 808         d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST |
                                                   >> 809                         DCACHE_DISCONNECTED | DCACHE_DONTCACHE;
                                                   >> 810 
                                                   >> 811         /* Nothing to do? Dropping the reference was all we needed? */
                                                   >> 812         if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
795                 return true;                      813                 return true;
796                                                   814 
797         /*                                        815         /*
798          * Either not worth retaining or we ca !! 816          * Not the fast normal case? Get the lock. We've already decremented
799          * Get the lock, then.  We've already  !! 817          * the refcount, but we'll need to re-check the situation after
800          * but we'll need to re-check the situ !! 818          * getting the lock.
801          */                                       819          */
802         spin_lock(&dentry->d_lock);               820         spin_lock(&dentry->d_lock);
803                                                   821 
804         /*                                        822         /*
805          * Did somebody else grab a reference     823          * Did somebody else grab a reference to it in the meantime, and
806          * we're no longer the last user after    824          * we're no longer the last user after all? Alternatively, somebody
807          * else could have killed it and marke    825          * else could have killed it and marked it dead. Either way, we
808          * don't need to do anything else.        826          * don't need to do anything else.
809          */                                       827          */
810 locked:                                        !! 828         if (dentry->d_lockref.count) {
811         if (dentry->d_lockref.count || retain_ << 
812                 spin_unlock(&dentry->d_lock);     829                 spin_unlock(&dentry->d_lock);
813                 return true;                      830                 return true;
814         }                                         831         }
                                                   >> 832 
                                                   >> 833         /*
                                                   >> 834          * Re-get the reference we optimistically dropped. We hold the
                                                   >> 835          * lock, and we just tested that it was zero, so we can just
                                                   >> 836          * set it to 1.
                                                   >> 837          */
                                                   >> 838         dentry->d_lockref.count = 1;
815         return false;                             839         return false;
816 }                                                 840 }
817                                                   841 
818                                                   842 
819 /*                                                843 /* 
820  * This is dput                                   844  * This is dput
821  *                                                845  *
822  * This is complicated by the fact that we do     846  * This is complicated by the fact that we do not want to put
823  * dentries that are no longer on any hash cha    847  * dentries that are no longer on any hash chain on the unused
824  * list: we'd much rather just get rid of them    848  * list: we'd much rather just get rid of them immediately.
825  *                                                849  *
826  * However, that implies that we have to trave    850  * However, that implies that we have to traverse the dentry
827  * tree upwards to the parents which might _al    851  * tree upwards to the parents which might _also_ now be
828  * scheduled for deletion (it may have been on    852  * scheduled for deletion (it may have been only waiting for
829  * its last child to go away).                    853  * its last child to go away).
830  *                                                854  *
831  * This tail recursion is done by hand as we d    855  * This tail recursion is done by hand as we don't want to depend
832  * on the compiler to always get this right (g    856  * on the compiler to always get this right (gcc generally doesn't).
833  * Real recursion would eat up our stack space    857  * Real recursion would eat up our stack space.
834  */                                               858  */
835                                                   859 
836 /*                                                860 /*
837  * dput - release a dentry                        861  * dput - release a dentry
838  * @dentry: dentry to release                     862  * @dentry: dentry to release 
839  *                                                863  *
840  * Release a dentry. This will drop the usage     864  * Release a dentry. This will drop the usage count and if appropriate
841  * call the dentry unlink method as well as re    865  * call the dentry unlink method as well as removing it from the queues and
842  * releasing its resources. If the parent dent    866  * releasing its resources. If the parent dentries were scheduled for release
843  * they too may now get deleted.                  867  * they too may now get deleted.
844  */                                               868  */
845 void dput(struct dentry *dentry)                  869 void dput(struct dentry *dentry)
846 {                                                 870 {
847         if (!dentry)                           !! 871         while (dentry) {
848                 return;                        !! 872                 might_sleep();
849         might_sleep();                         !! 873 
850         rcu_read_lock();                       !! 874                 rcu_read_lock();
851         if (likely(fast_dput(dentry))) {       !! 875                 if (likely(fast_dput(dentry))) {
852                 rcu_read_unlock();             !! 876                         rcu_read_unlock();
853                 return;                        << 
854         }                                      << 
855         while (lock_for_kill(dentry)) {        << 
856                 rcu_read_unlock();             << 
857                 dentry = __dentry_kill(dentry) << 
858                 if (!dentry)                   << 
859                         return;                   877                         return;
860                 if (retain_dentry(dentry, true !! 878                 }
                                                   >> 879 
                                                   >> 880                 /* Slow case: now with the dentry lock held */
                                                   >> 881                 rcu_read_unlock();
                                                   >> 882 
                                                   >> 883                 if (likely(retain_dentry(dentry))) {
861                         spin_unlock(&dentry->d    884                         spin_unlock(&dentry->d_lock);
862                         return;                   885                         return;
863                 }                                 886                 }
864                 rcu_read_lock();               !! 887 
                                                   >> 888                 dentry = dentry_kill(dentry);
865         }                                         889         }
866         rcu_read_unlock();                     << 
867         spin_unlock(&dentry->d_lock);          << 
868 }                                                 890 }
869 EXPORT_SYMBOL(dput);                              891 EXPORT_SYMBOL(dput);
870                                                   892 
871 static void to_shrink_list(struct dentry *dent !! 893 static void __dput_to_list(struct dentry *dentry, struct list_head *list)
872 __must_hold(&dentry->d_lock)                      894 __must_hold(&dentry->d_lock)
873 {                                                 895 {
874         if (!(dentry->d_flags & DCACHE_SHRINK_ !! 896         if (dentry->d_flags & DCACHE_SHRINK_LIST) {
                                                   >> 897                 /* let the owner of the list it's on deal with it */
                                                   >> 898                 --dentry->d_lockref.count;
                                                   >> 899         } else {
875                 if (dentry->d_flags & DCACHE_L    900                 if (dentry->d_flags & DCACHE_LRU_LIST)
876                         d_lru_del(dentry);        901                         d_lru_del(dentry);
877                 d_shrink_add(dentry, list);    !! 902                 if (!--dentry->d_lockref.count)
                                                   >> 903                         d_shrink_add(dentry, list);
878         }                                         904         }
879 }                                                 905 }
880                                                   906 
881 void dput_to_list(struct dentry *dentry, struc    907 void dput_to_list(struct dentry *dentry, struct list_head *list)
882 {                                                 908 {
883         rcu_read_lock();                          909         rcu_read_lock();
884         if (likely(fast_dput(dentry))) {          910         if (likely(fast_dput(dentry))) {
885                 rcu_read_unlock();                911                 rcu_read_unlock();
886                 return;                           912                 return;
887         }                                         913         }
888         rcu_read_unlock();                        914         rcu_read_unlock();
889         to_shrink_list(dentry, list);          !! 915         if (!retain_dentry(dentry))
                                                   >> 916                 __dput_to_list(dentry, list);
890         spin_unlock(&dentry->d_lock);             917         spin_unlock(&dentry->d_lock);
891 }                                                 918 }
892                                                   919 
                                                   >> 920 /* This must be called with d_lock held */
                                                   >> 921 static inline void __dget_dlock(struct dentry *dentry)
                                                   >> 922 {
                                                   >> 923         dentry->d_lockref.count++;
                                                   >> 924 }
                                                   >> 925 
                                                   >> 926 static inline void __dget(struct dentry *dentry)
                                                   >> 927 {
                                                   >> 928         lockref_get(&dentry->d_lockref);
                                                   >> 929 }
                                                   >> 930 
893 struct dentry *dget_parent(struct dentry *dent    931 struct dentry *dget_parent(struct dentry *dentry)
894 {                                                 932 {
895         int gotref;                               933         int gotref;
896         struct dentry *ret;                       934         struct dentry *ret;
897         unsigned seq;                             935         unsigned seq;
898                                                   936 
899         /*                                        937         /*
900          * Do optimistic parent lookup without    938          * Do optimistic parent lookup without any
901          * locking.                               939          * locking.
902          */                                       940          */
903         rcu_read_lock();                          941         rcu_read_lock();
904         seq = raw_seqcount_begin(&dentry->d_se    942         seq = raw_seqcount_begin(&dentry->d_seq);
905         ret = READ_ONCE(dentry->d_parent);        943         ret = READ_ONCE(dentry->d_parent);
906         gotref = lockref_get_not_zero(&ret->d_    944         gotref = lockref_get_not_zero(&ret->d_lockref);
907         rcu_read_unlock();                        945         rcu_read_unlock();
908         if (likely(gotref)) {                     946         if (likely(gotref)) {
909                 if (!read_seqcount_retry(&dent    947                 if (!read_seqcount_retry(&dentry->d_seq, seq))
910                         return ret;               948                         return ret;
911                 dput(ret);                        949                 dput(ret);
912         }                                         950         }
913                                                   951 
914 repeat:                                           952 repeat:
915         /*                                        953         /*
916          * Don't need rcu_dereference because     954          * Don't need rcu_dereference because we re-check it was correct under
917          * the lock.                              955          * the lock.
918          */                                       956          */
919         rcu_read_lock();                          957         rcu_read_lock();
920         ret = dentry->d_parent;                   958         ret = dentry->d_parent;
921         spin_lock(&ret->d_lock);                  959         spin_lock(&ret->d_lock);
922         if (unlikely(ret != dentry->d_parent))    960         if (unlikely(ret != dentry->d_parent)) {
923                 spin_unlock(&ret->d_lock);        961                 spin_unlock(&ret->d_lock);
924                 rcu_read_unlock();                962                 rcu_read_unlock();
925                 goto repeat;                      963                 goto repeat;
926         }                                         964         }
927         rcu_read_unlock();                        965         rcu_read_unlock();
928         BUG_ON(!ret->d_lockref.count);            966         BUG_ON(!ret->d_lockref.count);
929         ret->d_lockref.count++;                   967         ret->d_lockref.count++;
930         spin_unlock(&ret->d_lock);                968         spin_unlock(&ret->d_lock);
931         return ret;                               969         return ret;
932 }                                                 970 }
933 EXPORT_SYMBOL(dget_parent);                       971 EXPORT_SYMBOL(dget_parent);
934                                                   972 
935 static struct dentry * __d_find_any_alias(stru    973 static struct dentry * __d_find_any_alias(struct inode *inode)
936 {                                                 974 {
937         struct dentry *alias;                     975         struct dentry *alias;
938                                                   976 
939         if (hlist_empty(&inode->i_dentry))        977         if (hlist_empty(&inode->i_dentry))
940                 return NULL;                      978                 return NULL;
941         alias = hlist_entry(inode->i_dentry.fi    979         alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
942         lockref_get(&alias->d_lockref);        !! 980         __dget(alias);
943         return alias;                             981         return alias;
944 }                                                 982 }
945                                                   983 
946 /**                                               984 /**
947  * d_find_any_alias - find any alias for a giv    985  * d_find_any_alias - find any alias for a given inode
948  * @inode: inode to find an alias for             986  * @inode: inode to find an alias for
949  *                                                987  *
950  * If any aliases exist for the given inode, t    988  * If any aliases exist for the given inode, take and return a
951  * reference for one of them.  If no aliases e    989  * reference for one of them.  If no aliases exist, return %NULL.
952  */                                               990  */
953 struct dentry *d_find_any_alias(struct inode *    991 struct dentry *d_find_any_alias(struct inode *inode)
954 {                                                 992 {
955         struct dentry *de;                        993         struct dentry *de;
956                                                   994 
957         spin_lock(&inode->i_lock);                995         spin_lock(&inode->i_lock);
958         de = __d_find_any_alias(inode);           996         de = __d_find_any_alias(inode);
959         spin_unlock(&inode->i_lock);              997         spin_unlock(&inode->i_lock);
960         return de;                                998         return de;
961 }                                                 999 }
962 EXPORT_SYMBOL(d_find_any_alias);                  1000 EXPORT_SYMBOL(d_find_any_alias);
963                                                   1001 
964 static struct dentry *__d_find_alias(struct in    1002 static struct dentry *__d_find_alias(struct inode *inode)
965 {                                                 1003 {
966         struct dentry *alias;                     1004         struct dentry *alias;
967                                                   1005 
968         if (S_ISDIR(inode->i_mode))               1006         if (S_ISDIR(inode->i_mode))
969                 return __d_find_any_alias(inod    1007                 return __d_find_any_alias(inode);
970                                                   1008 
971         hlist_for_each_entry(alias, &inode->i_    1009         hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
972                 spin_lock(&alias->d_lock);        1010                 spin_lock(&alias->d_lock);
973                 if (!d_unhashed(alias)) {         1011                 if (!d_unhashed(alias)) {
974                         dget_dlock(alias);     !! 1012                         __dget_dlock(alias);
975                         spin_unlock(&alias->d_    1013                         spin_unlock(&alias->d_lock);
976                         return alias;             1014                         return alias;
977                 }                                 1015                 }
978                 spin_unlock(&alias->d_lock);      1016                 spin_unlock(&alias->d_lock);
979         }                                         1017         }
980         return NULL;                              1018         return NULL;
981 }                                                 1019 }
982                                                   1020 
983 /**                                               1021 /**
984  * d_find_alias - grab a hashed alias of inode    1022  * d_find_alias - grab a hashed alias of inode
985  * @inode: inode in question                      1023  * @inode: inode in question
986  *                                                1024  *
987  * If inode has a hashed alias, or is a direct    1025  * If inode has a hashed alias, or is a directory and has any alias,
988  * acquire the reference to alias and return i    1026  * acquire the reference to alias and return it. Otherwise return NULL.
989  * Notice that if inode is a directory there c    1027  * Notice that if inode is a directory there can be only one alias and
990  * it can be unhashed only if it has no childr    1028  * it can be unhashed only if it has no children, or if it is the root
991  * of a filesystem, or if the directory was re    1029  * of a filesystem, or if the directory was renamed and d_revalidate
992  * was the first vfs operation to notice.         1030  * was the first vfs operation to notice.
993  *                                                1031  *
994  * If the inode has an IS_ROOT, DCACHE_DISCONN    1032  * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
995  * any other hashed alias over that one.          1033  * any other hashed alias over that one.
996  */                                               1034  */
997 struct dentry *d_find_alias(struct inode *inod    1035 struct dentry *d_find_alias(struct inode *inode)
998 {                                                 1036 {
999         struct dentry *de = NULL;                 1037         struct dentry *de = NULL;
1000                                                  1038 
1001         if (!hlist_empty(&inode->i_dentry)) {    1039         if (!hlist_empty(&inode->i_dentry)) {
1002                 spin_lock(&inode->i_lock);       1040                 spin_lock(&inode->i_lock);
1003                 de = __d_find_alias(inode);      1041                 de = __d_find_alias(inode);
1004                 spin_unlock(&inode->i_lock);     1042                 spin_unlock(&inode->i_lock);
1005         }                                        1043         }
1006         return de;                               1044         return de;
1007 }                                                1045 }
1008 EXPORT_SYMBOL(d_find_alias);                     1046 EXPORT_SYMBOL(d_find_alias);
1009                                                  1047 
1010 /*                                               1048 /*
1011  *  Caller MUST be holding rcu_read_lock() an    1049  *  Caller MUST be holding rcu_read_lock() and be guaranteed
1012  *  that inode won't get freed until rcu_read    1050  *  that inode won't get freed until rcu_read_unlock().
1013  */                                              1051  */
1014 struct dentry *d_find_alias_rcu(struct inode     1052 struct dentry *d_find_alias_rcu(struct inode *inode)
1015 {                                                1053 {
1016         struct hlist_head *l = &inode->i_dent    1054         struct hlist_head *l = &inode->i_dentry;
1017         struct dentry *de = NULL;                1055         struct dentry *de = NULL;
1018                                                  1056 
1019         spin_lock(&inode->i_lock);               1057         spin_lock(&inode->i_lock);
1020         // ->i_dentry and ->i_rcu are colocat    1058         // ->i_dentry and ->i_rcu are colocated, but the latter won't be
1021         // used without having I_FREEING set,    1059         // used without having I_FREEING set, which means no aliases left
1022         if (likely(!(inode->i_state & I_FREEI    1060         if (likely(!(inode->i_state & I_FREEING) && !hlist_empty(l))) {
1023                 if (S_ISDIR(inode->i_mode)) {    1061                 if (S_ISDIR(inode->i_mode)) {
1024                         de = hlist_entry(l->f    1062                         de = hlist_entry(l->first, struct dentry, d_u.d_alias);
1025                 } else {                         1063                 } else {
1026                         hlist_for_each_entry(    1064                         hlist_for_each_entry(de, l, d_u.d_alias)
1027                                 if (!d_unhash    1065                                 if (!d_unhashed(de))
1028                                         break    1066                                         break;
1029                 }                                1067                 }
1030         }                                        1068         }
1031         spin_unlock(&inode->i_lock);             1069         spin_unlock(&inode->i_lock);
1032         return de;                               1070         return de;
1033 }                                                1071 }
1034                                                  1072 
1035 /*                                               1073 /*
1036  *      Try to kill dentries associated with     1074  *      Try to kill dentries associated with this inode.
1037  * WARNING: you must own a reference to inode    1075  * WARNING: you must own a reference to inode.
1038  */                                              1076  */
1039 void d_prune_aliases(struct inode *inode)        1077 void d_prune_aliases(struct inode *inode)
1040 {                                                1078 {
1041         LIST_HEAD(dispose);                   << 
1042         struct dentry *dentry;                   1079         struct dentry *dentry;
1043                                               !! 1080 restart:
1044         spin_lock(&inode->i_lock);               1081         spin_lock(&inode->i_lock);
1045         hlist_for_each_entry(dentry, &inode->    1082         hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
1046                 spin_lock(&dentry->d_lock);      1083                 spin_lock(&dentry->d_lock);
1047                 if (!dentry->d_lockref.count) !! 1084                 if (!dentry->d_lockref.count) {
1048                         to_shrink_list(dentry !! 1085                         struct dentry *parent = lock_parent(dentry);
                                                   >> 1086                         if (likely(!dentry->d_lockref.count)) {
                                                   >> 1087                                 __dentry_kill(dentry);
                                                   >> 1088                                 dput(parent);
                                                   >> 1089                                 goto restart;
                                                   >> 1090                         }
                                                   >> 1091                         if (parent)
                                                   >> 1092                                 spin_unlock(&parent->d_lock);
                                                   >> 1093                 }
1049                 spin_unlock(&dentry->d_lock);    1094                 spin_unlock(&dentry->d_lock);
1050         }                                        1095         }
1051         spin_unlock(&inode->i_lock);             1096         spin_unlock(&inode->i_lock);
1052         shrink_dentry_list(&dispose);         << 
1053 }                                                1097 }
1054 EXPORT_SYMBOL(d_prune_aliases);                  1098 EXPORT_SYMBOL(d_prune_aliases);
1055                                                  1099 
1056 static inline void shrink_kill(struct dentry  !! 1100 /*
                                                   >> 1101  * Lock a dentry from shrink list.
                                                   >> 1102  * Called under rcu_read_lock() and dentry->d_lock; the former
                                                   >> 1103  * guarantees that nothing we access will be freed under us.
                                                   >> 1104  * Note that dentry is *not* protected from concurrent dentry_kill(),
                                                   >> 1105  * d_delete(), etc.
                                                   >> 1106  *
                                                   >> 1107  * Return false if dentry has been disrupted or grabbed, leaving
                                                   >> 1108  * the caller to kick it off-list.  Otherwise, return true and have
                                                   >> 1109  * that dentry's inode and parent both locked.
                                                   >> 1110  */
                                                   >> 1111 static bool shrink_lock_dentry(struct dentry *dentry)
1057 {                                                1112 {
1058         do {                                  !! 1113         struct inode *inode;
1059                 rcu_read_unlock();            !! 1114         struct dentry *parent;
1060                 victim = __dentry_kill(victim !! 1115 
1061                 rcu_read_lock();              !! 1116         if (dentry->d_lockref.count)
1062         } while (victim && lock_for_kill(vict !! 1117                 return false;
1063         rcu_read_unlock();                    !! 1118 
1064         if (victim)                           !! 1119         inode = dentry->d_inode;
1065                 spin_unlock(&victim->d_lock); !! 1120         if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
                                                   >> 1121                 spin_unlock(&dentry->d_lock);
                                                   >> 1122                 spin_lock(&inode->i_lock);
                                                   >> 1123                 spin_lock(&dentry->d_lock);
                                                   >> 1124                 if (unlikely(dentry->d_lockref.count))
                                                   >> 1125                         goto out;
                                                   >> 1126                 /* changed inode means that somebody had grabbed it */
                                                   >> 1127                 if (unlikely(inode != dentry->d_inode))
                                                   >> 1128                         goto out;
                                                   >> 1129         }
                                                   >> 1130 
                                                   >> 1131         parent = dentry->d_parent;
                                                   >> 1132         if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock)))
                                                   >> 1133                 return true;
                                                   >> 1134 
                                                   >> 1135         spin_unlock(&dentry->d_lock);
                                                   >> 1136         spin_lock(&parent->d_lock);
                                                   >> 1137         if (unlikely(parent != dentry->d_parent)) {
                                                   >> 1138                 spin_unlock(&parent->d_lock);
                                                   >> 1139                 spin_lock(&dentry->d_lock);
                                                   >> 1140                 goto out;
                                                   >> 1141         }
                                                   >> 1142         spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
                                                   >> 1143         if (likely(!dentry->d_lockref.count))
                                                   >> 1144                 return true;
                                                   >> 1145         spin_unlock(&parent->d_lock);
                                                   >> 1146 out:
                                                   >> 1147         if (inode)
                                                   >> 1148                 spin_unlock(&inode->i_lock);
                                                   >> 1149         return false;
1066 }                                                1150 }
1067                                                  1151 
1068 void shrink_dentry_list(struct list_head *lis    1152 void shrink_dentry_list(struct list_head *list)
1069 {                                                1153 {
1070         while (!list_empty(list)) {              1154         while (!list_empty(list)) {
1071                 struct dentry *dentry;        !! 1155                 struct dentry *dentry, *parent;
1072                                                  1156 
1073                 dentry = list_entry(list->pre    1157                 dentry = list_entry(list->prev, struct dentry, d_lru);
1074                 spin_lock(&dentry->d_lock);      1158                 spin_lock(&dentry->d_lock);
1075                 rcu_read_lock();                 1159                 rcu_read_lock();
1076                 if (!lock_for_kill(dentry)) { !! 1160                 if (!shrink_lock_dentry(dentry)) {
1077                         bool can_free;        !! 1161                         bool can_free = false;
1078                         rcu_read_unlock();       1162                         rcu_read_unlock();
1079                         d_shrink_del(dentry);    1163                         d_shrink_del(dentry);
1080                         can_free = dentry->d_ !! 1164                         if (dentry->d_lockref.count < 0)
                                                   >> 1165                                 can_free = dentry->d_flags & DCACHE_MAY_FREE;
1081                         spin_unlock(&dentry->    1166                         spin_unlock(&dentry->d_lock);
1082                         if (can_free)            1167                         if (can_free)
1083                                 dentry_free(d    1168                                 dentry_free(dentry);
1084                         continue;                1169                         continue;
1085                 }                                1170                 }
                                                   >> 1171                 rcu_read_unlock();
1086                 d_shrink_del(dentry);            1172                 d_shrink_del(dentry);
1087                 shrink_kill(dentry);          !! 1173                 parent = dentry->d_parent;
                                                   >> 1174                 if (parent != dentry)
                                                   >> 1175                         __dput_to_list(parent, list);
                                                   >> 1176                 __dentry_kill(dentry);
1088         }                                        1177         }
1089 }                                                1178 }
1090                                                  1179 
1091 static enum lru_status dentry_lru_isolate(str    1180 static enum lru_status dentry_lru_isolate(struct list_head *item,
1092                 struct list_lru_one *lru, spi    1181                 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
1093 {                                                1182 {
1094         struct list_head *freeable = arg;        1183         struct list_head *freeable = arg;
1095         struct dentry   *dentry = container_o    1184         struct dentry   *dentry = container_of(item, struct dentry, d_lru);
1096                                                  1185 
1097                                                  1186 
1098         /*                                       1187         /*
1099          * we are inverting the lru lock/dent    1188          * we are inverting the lru lock/dentry->d_lock here,
1100          * so use a trylock. If we fail to ge    1189          * so use a trylock. If we fail to get the lock, just skip
1101          * it                                    1190          * it
1102          */                                      1191          */
1103         if (!spin_trylock(&dentry->d_lock))      1192         if (!spin_trylock(&dentry->d_lock))
1104                 return LRU_SKIP;                 1193                 return LRU_SKIP;
1105                                                  1194 
1106         /*                                       1195         /*
1107          * Referenced dentries are still in u    1196          * Referenced dentries are still in use. If they have active
1108          * counts, just remove them from the     1197          * counts, just remove them from the LRU. Otherwise give them
1109          * another pass through the LRU.         1198          * another pass through the LRU.
1110          */                                      1199          */
1111         if (dentry->d_lockref.count) {           1200         if (dentry->d_lockref.count) {
1112                 d_lru_isolate(lru, dentry);      1201                 d_lru_isolate(lru, dentry);
1113                 spin_unlock(&dentry->d_lock);    1202                 spin_unlock(&dentry->d_lock);
1114                 return LRU_REMOVED;              1203                 return LRU_REMOVED;
1115         }                                        1204         }
1116                                                  1205 
1117         if (dentry->d_flags & DCACHE_REFERENC    1206         if (dentry->d_flags & DCACHE_REFERENCED) {
1118                 dentry->d_flags &= ~DCACHE_RE    1207                 dentry->d_flags &= ~DCACHE_REFERENCED;
1119                 spin_unlock(&dentry->d_lock);    1208                 spin_unlock(&dentry->d_lock);
1120                                                  1209 
1121                 /*                               1210                 /*
1122                  * The list move itself will     1211                  * The list move itself will be made by the common LRU code. At
1123                  * this point, we've dropped     1212                  * this point, we've dropped the dentry->d_lock but keep the
1124                  * lru lock. This is safe to     1213                  * lru lock. This is safe to do, since every list movement is
1125                  * protected by the lru lock     1214                  * protected by the lru lock even if both locks are held.
1126                  *                               1215                  *
1127                  * This is guaranteed by the     1216                  * This is guaranteed by the fact that all LRU management
1128                  * functions are intermediate    1217                  * functions are intermediated by the LRU API calls like
1129                  * list_lru_add_obj and list_ !! 1218                  * list_lru_add and list_lru_del. List movement in this file
1130                  * only ever occur through th    1219                  * only ever occur through this functions or through callbacks
1131                  * like this one, that are ca    1220                  * like this one, that are called from the LRU API.
1132                  *                               1221                  *
1133                  * The only exceptions to thi    1222                  * The only exceptions to this are functions like
1134                  * shrink_dentry_list, and co    1223                  * shrink_dentry_list, and code that first checks for the
1135                  * DCACHE_SHRINK_LIST flag.      1224                  * DCACHE_SHRINK_LIST flag.  Those are guaranteed to be
1136                  * operating only with stack     1225                  * operating only with stack provided lists after they are
1137                  * properly isolated from the    1226                  * properly isolated from the main list.  It is thus, always a
1138                  * local access.                 1227                  * local access.
1139                  */                              1228                  */
1140                 return LRU_ROTATE;               1229                 return LRU_ROTATE;
1141         }                                        1230         }
1142                                                  1231 
1143         d_lru_shrink_move(lru, dentry, freeab    1232         d_lru_shrink_move(lru, dentry, freeable);
1144         spin_unlock(&dentry->d_lock);            1233         spin_unlock(&dentry->d_lock);
1145                                                  1234 
1146         return LRU_REMOVED;                      1235         return LRU_REMOVED;
1147 }                                                1236 }
1148                                                  1237 
1149 /**                                              1238 /**
1150  * prune_dcache_sb - shrink the dcache           1239  * prune_dcache_sb - shrink the dcache
1151  * @sb: superblock                               1240  * @sb: superblock
1152  * @sc: shrink control, passed to list_lru_sh    1241  * @sc: shrink control, passed to list_lru_shrink_walk()
1153  *                                               1242  *
1154  * Attempt to shrink the superblock dcache LR    1243  * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This
1155  * is done when we need more memory and calle    1244  * is done when we need more memory and called from the superblock shrinker
1156  * function.                                     1245  * function.
1157  *                                               1246  *
1158  * This function may fail to free any resourc    1247  * This function may fail to free any resources if all the dentries are in
1159  * use.                                          1248  * use.
1160  */                                              1249  */
1161 long prune_dcache_sb(struct super_block *sb,     1250 long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc)
1162 {                                                1251 {
1163         LIST_HEAD(dispose);                      1252         LIST_HEAD(dispose);
1164         long freed;                              1253         long freed;
1165                                                  1254 
1166         freed = list_lru_shrink_walk(&sb->s_d    1255         freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc,
1167                                      dentry_l    1256                                      dentry_lru_isolate, &dispose);
1168         shrink_dentry_list(&dispose);            1257         shrink_dentry_list(&dispose);
1169         return freed;                            1258         return freed;
1170 }                                                1259 }
1171                                                  1260 
1172 static enum lru_status dentry_lru_isolate_shr    1261 static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
1173                 struct list_lru_one *lru, spi    1262                 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
1174 {                                                1263 {
1175         struct list_head *freeable = arg;        1264         struct list_head *freeable = arg;
1176         struct dentry   *dentry = container_o    1265         struct dentry   *dentry = container_of(item, struct dentry, d_lru);
1177                                                  1266 
1178         /*                                       1267         /*
1179          * we are inverting the lru lock/dent    1268          * we are inverting the lru lock/dentry->d_lock here,
1180          * so use a trylock. If we fail to ge    1269          * so use a trylock. If we fail to get the lock, just skip
1181          * it                                    1270          * it
1182          */                                      1271          */
1183         if (!spin_trylock(&dentry->d_lock))      1272         if (!spin_trylock(&dentry->d_lock))
1184                 return LRU_SKIP;                 1273                 return LRU_SKIP;
1185                                                  1274 
1186         d_lru_shrink_move(lru, dentry, freeab    1275         d_lru_shrink_move(lru, dentry, freeable);
1187         spin_unlock(&dentry->d_lock);            1276         spin_unlock(&dentry->d_lock);
1188                                                  1277 
1189         return LRU_REMOVED;                      1278         return LRU_REMOVED;
1190 }                                                1279 }
1191                                                  1280 
1192                                                  1281 
1193 /**                                              1282 /**
1194  * shrink_dcache_sb - shrink dcache for a sup    1283  * shrink_dcache_sb - shrink dcache for a superblock
1195  * @sb: superblock                               1284  * @sb: superblock
1196  *                                               1285  *
1197  * Shrink the dcache for the specified super     1286  * Shrink the dcache for the specified super block. This is used to free
1198  * the dcache before unmounting a file system    1287  * the dcache before unmounting a file system.
1199  */                                              1288  */
1200 void shrink_dcache_sb(struct super_block *sb)    1289 void shrink_dcache_sb(struct super_block *sb)
1201 {                                                1290 {
1202         do {                                     1291         do {
1203                 LIST_HEAD(dispose);              1292                 LIST_HEAD(dispose);
1204                                                  1293 
1205                 list_lru_walk(&sb->s_dentry_l    1294                 list_lru_walk(&sb->s_dentry_lru,
1206                         dentry_lru_isolate_sh    1295                         dentry_lru_isolate_shrink, &dispose, 1024);
1207                 shrink_dentry_list(&dispose);    1296                 shrink_dentry_list(&dispose);
1208         } while (list_lru_count(&sb->s_dentry    1297         } while (list_lru_count(&sb->s_dentry_lru) > 0);
1209 }                                                1298 }
1210 EXPORT_SYMBOL(shrink_dcache_sb);                 1299 EXPORT_SYMBOL(shrink_dcache_sb);
1211                                                  1300 
1212 /**                                              1301 /**
1213  * enum d_walk_ret - action to talke during t    1302  * enum d_walk_ret - action to talke during tree walk
1214  * @D_WALK_CONTINUE:    contrinue walk           1303  * @D_WALK_CONTINUE:    contrinue walk
1215  * @D_WALK_QUIT:        quit walk                1304  * @D_WALK_QUIT:        quit walk
1216  * @D_WALK_NORETRY:     quit when retry is ne    1305  * @D_WALK_NORETRY:     quit when retry is needed
1217  * @D_WALK_SKIP:        skip this dentry and     1306  * @D_WALK_SKIP:        skip this dentry and its children
1218  */                                              1307  */
1219 enum d_walk_ret {                                1308 enum d_walk_ret {
1220         D_WALK_CONTINUE,                         1309         D_WALK_CONTINUE,
1221         D_WALK_QUIT,                             1310         D_WALK_QUIT,
1222         D_WALK_NORETRY,                          1311         D_WALK_NORETRY,
1223         D_WALK_SKIP,                             1312         D_WALK_SKIP,
1224 };                                               1313 };
1225                                                  1314 
1226 /**                                              1315 /**
1227  * d_walk - walk the dentry tree                 1316  * d_walk - walk the dentry tree
1228  * @parent:     start of walk                    1317  * @parent:     start of walk
1229  * @data:       data passed to @enter() and @    1318  * @data:       data passed to @enter() and @finish()
1230  * @enter:      callback when first entering     1319  * @enter:      callback when first entering the dentry
1231  *                                               1320  *
1232  * The @enter() callbacks are called with d_l    1321  * The @enter() callbacks are called with d_lock held.
1233  */                                              1322  */
1234 static void d_walk(struct dentry *parent, voi    1323 static void d_walk(struct dentry *parent, void *data,
1235                    enum d_walk_ret (*enter)(v    1324                    enum d_walk_ret (*enter)(void *, struct dentry *))
1236 {                                                1325 {
1237         struct dentry *this_parent, *dentry;  !! 1326         struct dentry *this_parent;
                                                   >> 1327         struct list_head *next;
1238         unsigned seq = 0;                        1328         unsigned seq = 0;
1239         enum d_walk_ret ret;                     1329         enum d_walk_ret ret;
1240         bool retry = true;                       1330         bool retry = true;
1241                                                  1331 
1242 again:                                           1332 again:
1243         read_seqbegin_or_lock(&rename_lock, &    1333         read_seqbegin_or_lock(&rename_lock, &seq);
1244         this_parent = parent;                    1334         this_parent = parent;
1245         spin_lock(&this_parent->d_lock);         1335         spin_lock(&this_parent->d_lock);
1246                                                  1336 
1247         ret = enter(data, this_parent);          1337         ret = enter(data, this_parent);
1248         switch (ret) {                           1338         switch (ret) {
1249         case D_WALK_CONTINUE:                    1339         case D_WALK_CONTINUE:
1250                 break;                           1340                 break;
1251         case D_WALK_QUIT:                        1341         case D_WALK_QUIT:
1252         case D_WALK_SKIP:                        1342         case D_WALK_SKIP:
1253                 goto out_unlock;                 1343                 goto out_unlock;
1254         case D_WALK_NORETRY:                     1344         case D_WALK_NORETRY:
1255                 retry = false;                   1345                 retry = false;
1256                 break;                           1346                 break;
1257         }                                        1347         }
1258 repeat:                                          1348 repeat:
1259         dentry = d_first_child(this_parent);  !! 1349         next = this_parent->d_subdirs.next;
1260 resume:                                          1350 resume:
1261         hlist_for_each_entry_from(dentry, d_s !! 1351         while (next != &this_parent->d_subdirs) {
                                                   >> 1352                 struct list_head *tmp = next;
                                                   >> 1353                 struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
                                                   >> 1354                 next = tmp->next;
                                                   >> 1355 
1262                 if (unlikely(dentry->d_flags     1356                 if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR))
1263                         continue;                1357                         continue;
1264                                                  1358 
1265                 spin_lock_nested(&dentry->d_l    1359                 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
1266                                                  1360 
1267                 ret = enter(data, dentry);       1361                 ret = enter(data, dentry);
1268                 switch (ret) {                   1362                 switch (ret) {
1269                 case D_WALK_CONTINUE:            1363                 case D_WALK_CONTINUE:
1270                         break;                   1364                         break;
1271                 case D_WALK_QUIT:                1365                 case D_WALK_QUIT:
1272                         spin_unlock(&dentry->    1366                         spin_unlock(&dentry->d_lock);
1273                         goto out_unlock;         1367                         goto out_unlock;
1274                 case D_WALK_NORETRY:             1368                 case D_WALK_NORETRY:
1275                         retry = false;           1369                         retry = false;
1276                         break;                   1370                         break;
1277                 case D_WALK_SKIP:                1371                 case D_WALK_SKIP:
1278                         spin_unlock(&dentry->    1372                         spin_unlock(&dentry->d_lock);
1279                         continue;                1373                         continue;
1280                 }                                1374                 }
1281                                                  1375 
1282                 if (!hlist_empty(&dentry->d_c !! 1376                 if (!list_empty(&dentry->d_subdirs)) {
1283                         spin_unlock(&this_par    1377                         spin_unlock(&this_parent->d_lock);
1284                         spin_release(&dentry-    1378                         spin_release(&dentry->d_lock.dep_map, _RET_IP_);
1285                         this_parent = dentry;    1379                         this_parent = dentry;
1286                         spin_acquire(&this_pa    1380                         spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
1287                         goto repeat;             1381                         goto repeat;
1288                 }                                1382                 }
1289                 spin_unlock(&dentry->d_lock);    1383                 spin_unlock(&dentry->d_lock);
1290         }                                        1384         }
1291         /*                                       1385         /*
1292          * All done at this level ... ascend     1386          * All done at this level ... ascend and resume the search.
1293          */                                      1387          */
1294         rcu_read_lock();                         1388         rcu_read_lock();
1295 ascend:                                          1389 ascend:
1296         if (this_parent != parent) {             1390         if (this_parent != parent) {
1297                 dentry = this_parent;         !! 1391                 struct dentry *child = this_parent;
1298                 this_parent = dentry->d_paren !! 1392                 this_parent = child->d_parent;
1299                                                  1393 
1300                 spin_unlock(&dentry->d_lock); !! 1394                 spin_unlock(&child->d_lock);
1301                 spin_lock(&this_parent->d_loc    1395                 spin_lock(&this_parent->d_lock);
1302                                                  1396 
1303                 /* might go back up the wrong    1397                 /* might go back up the wrong parent if we have had a rename. */
1304                 if (need_seqretry(&rename_loc    1398                 if (need_seqretry(&rename_lock, seq))
1305                         goto rename_retry;       1399                         goto rename_retry;
1306                 /* go into the first sibling     1400                 /* go into the first sibling still alive */
1307                 hlist_for_each_entry_continue !! 1401                 do {
1308                         if (likely(!(dentry-> !! 1402                         next = child->d_child.next;
1309                                 rcu_read_unlo !! 1403                         if (next == &this_parent->d_subdirs)
1310                                 goto resume;  !! 1404                                 goto ascend;
1311                         }                     !! 1405                         child = list_entry(next, struct dentry, d_child);
1312                 }                             !! 1406                 } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
1313                 goto ascend;                  !! 1407                 rcu_read_unlock();
                                                   >> 1408                 goto resume;
1314         }                                        1409         }
1315         if (need_seqretry(&rename_lock, seq))    1410         if (need_seqretry(&rename_lock, seq))
1316                 goto rename_retry;               1411                 goto rename_retry;
1317         rcu_read_unlock();                       1412         rcu_read_unlock();
1318                                                  1413 
1319 out_unlock:                                      1414 out_unlock:
1320         spin_unlock(&this_parent->d_lock);       1415         spin_unlock(&this_parent->d_lock);
1321         done_seqretry(&rename_lock, seq);        1416         done_seqretry(&rename_lock, seq);
1322         return;                                  1417         return;
1323                                                  1418 
1324 rename_retry:                                    1419 rename_retry:
1325         spin_unlock(&this_parent->d_lock);       1420         spin_unlock(&this_parent->d_lock);
1326         rcu_read_unlock();                       1421         rcu_read_unlock();
1327         BUG_ON(seq & 1);                         1422         BUG_ON(seq & 1);
1328         if (!retry)                              1423         if (!retry)
1329                 return;                          1424                 return;
1330         seq = 1;                                 1425         seq = 1;
1331         goto again;                              1426         goto again;
1332 }                                                1427 }
1333                                                  1428 
1334 struct check_mount {                             1429 struct check_mount {
1335         struct vfsmount *mnt;                    1430         struct vfsmount *mnt;
1336         unsigned int mounted;                    1431         unsigned int mounted;
1337 };                                               1432 };
1338                                                  1433 
1339 static enum d_walk_ret path_check_mount(void     1434 static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry)
1340 {                                                1435 {
1341         struct check_mount *info = data;         1436         struct check_mount *info = data;
1342         struct path path = { .mnt = info->mnt    1437         struct path path = { .mnt = info->mnt, .dentry = dentry };
1343                                                  1438 
1344         if (likely(!d_mountpoint(dentry)))       1439         if (likely(!d_mountpoint(dentry)))
1345                 return D_WALK_CONTINUE;          1440                 return D_WALK_CONTINUE;
1346         if (__path_is_mountpoint(&path)) {       1441         if (__path_is_mountpoint(&path)) {
1347                 info->mounted = 1;               1442                 info->mounted = 1;
1348                 return D_WALK_QUIT;              1443                 return D_WALK_QUIT;
1349         }                                        1444         }
1350         return D_WALK_CONTINUE;                  1445         return D_WALK_CONTINUE;
1351 }                                                1446 }
1352                                                  1447 
1353 /**                                              1448 /**
1354  * path_has_submounts - check for mounts over    1449  * path_has_submounts - check for mounts over a dentry in the
1355  *                      current namespace.       1450  *                      current namespace.
1356  * @parent: path to check.                       1451  * @parent: path to check.
1357  *                                               1452  *
1358  * Return true if the parent or its subdirect    1453  * Return true if the parent or its subdirectories contain
1359  * a mount point in the current namespace.       1454  * a mount point in the current namespace.
1360  */                                              1455  */
1361 int path_has_submounts(const struct path *par    1456 int path_has_submounts(const struct path *parent)
1362 {                                                1457 {
1363         struct check_mount data = { .mnt = pa    1458         struct check_mount data = { .mnt = parent->mnt, .mounted = 0 };
1364                                                  1459 
1365         read_seqlock_excl(&mount_lock);          1460         read_seqlock_excl(&mount_lock);
1366         d_walk(parent->dentry, &data, path_ch    1461         d_walk(parent->dentry, &data, path_check_mount);
1367         read_sequnlock_excl(&mount_lock);        1462         read_sequnlock_excl(&mount_lock);
1368                                                  1463 
1369         return data.mounted;                     1464         return data.mounted;
1370 }                                                1465 }
1371 EXPORT_SYMBOL(path_has_submounts);               1466 EXPORT_SYMBOL(path_has_submounts);
1372                                                  1467 
1373 /*                                               1468 /*
1374  * Called by mount code to set a mountpoint a    1469  * Called by mount code to set a mountpoint and check if the mountpoint is
1375  * reachable (e.g. NFS can unhash a directory    1470  * reachable (e.g. NFS can unhash a directory dentry and then the complete
1376  * subtree can become unreachable).              1471  * subtree can become unreachable).
1377  *                                               1472  *
1378  * Only one of d_invalidate() and d_set_mount    1473  * Only one of d_invalidate() and d_set_mounted() must succeed.  For
1379  * this reason take rename_lock and d_lock on    1474  * this reason take rename_lock and d_lock on dentry and ancestors.
1380  */                                              1475  */
1381 int d_set_mounted(struct dentry *dentry)         1476 int d_set_mounted(struct dentry *dentry)
1382 {                                                1477 {
1383         struct dentry *p;                        1478         struct dentry *p;
1384         int ret = -ENOENT;                       1479         int ret = -ENOENT;
1385         write_seqlock(&rename_lock);             1480         write_seqlock(&rename_lock);
1386         for (p = dentry->d_parent; !IS_ROOT(p    1481         for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
1387                 /* Need exclusion wrt. d_inva    1482                 /* Need exclusion wrt. d_invalidate() */
1388                 spin_lock(&p->d_lock);           1483                 spin_lock(&p->d_lock);
1389                 if (unlikely(d_unhashed(p)))     1484                 if (unlikely(d_unhashed(p))) {
1390                         spin_unlock(&p->d_loc    1485                         spin_unlock(&p->d_lock);
1391                         goto out;                1486                         goto out;
1392                 }                                1487                 }
1393                 spin_unlock(&p->d_lock);         1488                 spin_unlock(&p->d_lock);
1394         }                                        1489         }
1395         spin_lock(&dentry->d_lock);              1490         spin_lock(&dentry->d_lock);
1396         if (!d_unlinked(dentry)) {               1491         if (!d_unlinked(dentry)) {
1397                 ret = -EBUSY;                    1492                 ret = -EBUSY;
1398                 if (!d_mountpoint(dentry)) {     1493                 if (!d_mountpoint(dentry)) {
1399                         dentry->d_flags |= DC    1494                         dentry->d_flags |= DCACHE_MOUNTED;
1400                         ret = 0;                 1495                         ret = 0;
1401                 }                                1496                 }
1402         }                                        1497         }
1403         spin_unlock(&dentry->d_lock);            1498         spin_unlock(&dentry->d_lock);
1404 out:                                             1499 out:
1405         write_sequnlock(&rename_lock);           1500         write_sequnlock(&rename_lock);
1406         return ret;                              1501         return ret;
1407 }                                                1502 }
1408                                                  1503 
1409 /*                                               1504 /*
1410  * Search the dentry child list of the specif    1505  * Search the dentry child list of the specified parent,
1411  * and move any unused dentries to the end of    1506  * and move any unused dentries to the end of the unused
1412  * list for prune_dcache(). We descend to the    1507  * list for prune_dcache(). We descend to the next level
1413  * whenever the d_children list is non-empty  !! 1508  * whenever the d_subdirs list is non-empty and continue
1414  * searching.                                    1509  * searching.
1415  *                                               1510  *
1416  * It returns zero iff there are no unused ch    1511  * It returns zero iff there are no unused children,
1417  * otherwise  it returns the number of childr    1512  * otherwise  it returns the number of children moved to
1418  * the end of the unused list. This may not b    1513  * the end of the unused list. This may not be the total
1419  * number of unused children, because select_    1514  * number of unused children, because select_parent can
1420  * drop the lock and return early due to late    1515  * drop the lock and return early due to latency
1421  * constraints.                                  1516  * constraints.
1422  */                                              1517  */
1423                                                  1518 
1424 struct select_data {                             1519 struct select_data {
1425         struct dentry *start;                    1520         struct dentry *start;
1426         union {                                  1521         union {
1427                 long found;                      1522                 long found;
1428                 struct dentry *victim;           1523                 struct dentry *victim;
1429         };                                       1524         };
1430         struct list_head dispose;                1525         struct list_head dispose;
1431 };                                               1526 };
1432                                                  1527 
1433 static enum d_walk_ret select_collect(void *_    1528 static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
1434 {                                                1529 {
1435         struct select_data *data = _data;        1530         struct select_data *data = _data;
1436         enum d_walk_ret ret = D_WALK_CONTINUE    1531         enum d_walk_ret ret = D_WALK_CONTINUE;
1437                                                  1532 
1438         if (data->start == dentry)               1533         if (data->start == dentry)
1439                 goto out;                        1534                 goto out;
1440                                                  1535 
1441         if (dentry->d_flags & DCACHE_SHRINK_L    1536         if (dentry->d_flags & DCACHE_SHRINK_LIST) {
1442                 data->found++;                   1537                 data->found++;
1443         } else if (!dentry->d_lockref.count)  !! 1538         } else {
1444                 to_shrink_list(dentry, &data- !! 1539                 if (dentry->d_flags & DCACHE_LRU_LIST)
1445                 data->found++;                !! 1540                         d_lru_del(dentry);
1446         } else if (dentry->d_lockref.count <  !! 1541                 if (!dentry->d_lockref.count) {
1447                 data->found++;                !! 1542                         d_shrink_add(dentry, &data->dispose);
                                                   >> 1543                         data->found++;
                                                   >> 1544                 }
1448         }                                        1545         }
1449         /*                                       1546         /*
1450          * We can return to the caller if we     1547          * We can return to the caller if we have found some (this
1451          * ensures forward progress). We'll b    1548          * ensures forward progress). We'll be coming back to find
1452          * the rest.                             1549          * the rest.
1453          */                                      1550          */
1454         if (!list_empty(&data->dispose))         1551         if (!list_empty(&data->dispose))
1455                 ret = need_resched() ? D_WALK    1552                 ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
1456 out:                                             1553 out:
1457         return ret;                              1554         return ret;
1458 }                                                1555 }
1459                                                  1556 
1460 static enum d_walk_ret select_collect2(void *    1557 static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry)
1461 {                                                1558 {
1462         struct select_data *data = _data;        1559         struct select_data *data = _data;
1463         enum d_walk_ret ret = D_WALK_CONTINUE    1560         enum d_walk_ret ret = D_WALK_CONTINUE;
1464                                                  1561 
1465         if (data->start == dentry)               1562         if (data->start == dentry)
1466                 goto out;                        1563                 goto out;
1467                                                  1564 
1468         if (!dentry->d_lockref.count) {       !! 1565         if (dentry->d_flags & DCACHE_SHRINK_LIST) {
1469                 if (dentry->d_flags & DCACHE_ !! 1566                 if (!dentry->d_lockref.count) {
1470                         rcu_read_lock();         1567                         rcu_read_lock();
1471                         data->victim = dentry    1568                         data->victim = dentry;
1472                         return D_WALK_QUIT;      1569                         return D_WALK_QUIT;
1473                 }                                1570                 }
1474                 to_shrink_list(dentry, &data- !! 1571         } else {
                                                   >> 1572                 if (dentry->d_flags & DCACHE_LRU_LIST)
                                                   >> 1573                         d_lru_del(dentry);
                                                   >> 1574                 if (!dentry->d_lockref.count)
                                                   >> 1575                         d_shrink_add(dentry, &data->dispose);
1475         }                                        1576         }
1476         /*                                       1577         /*
1477          * We can return to the caller if we     1578          * We can return to the caller if we have found some (this
1478          * ensures forward progress). We'll b    1579          * ensures forward progress). We'll be coming back to find
1479          * the rest.                             1580          * the rest.
1480          */                                      1581          */
1481         if (!list_empty(&data->dispose))         1582         if (!list_empty(&data->dispose))
1482                 ret = need_resched() ? D_WALK    1583                 ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
1483 out:                                             1584 out:
1484         return ret;                              1585         return ret;
1485 }                                                1586 }
1486                                                  1587 
1487 /**                                              1588 /**
1488  * shrink_dcache_parent - prune dcache           1589  * shrink_dcache_parent - prune dcache
1489  * @parent: parent of entries to prune           1590  * @parent: parent of entries to prune
1490  *                                               1591  *
1491  * Prune the dcache to remove unused children    1592  * Prune the dcache to remove unused children of the parent dentry.
1492  */                                              1593  */
1493 void shrink_dcache_parent(struct dentry *pare    1594 void shrink_dcache_parent(struct dentry *parent)
1494 {                                                1595 {
1495         for (;;) {                               1596         for (;;) {
1496                 struct select_data data = {.s    1597                 struct select_data data = {.start = parent};
1497                                                  1598 
1498                 INIT_LIST_HEAD(&data.dispose)    1599                 INIT_LIST_HEAD(&data.dispose);
1499                 d_walk(parent, &data, select_    1600                 d_walk(parent, &data, select_collect);
1500                                                  1601 
1501                 if (!list_empty(&data.dispose    1602                 if (!list_empty(&data.dispose)) {
1502                         shrink_dentry_list(&d    1603                         shrink_dentry_list(&data.dispose);
1503                         continue;                1604                         continue;
1504                 }                                1605                 }
1505                                                  1606 
1506                 cond_resched();                  1607                 cond_resched();
1507                 if (!data.found)                 1608                 if (!data.found)
1508                         break;                   1609                         break;
1509                 data.victim = NULL;              1610                 data.victim = NULL;
1510                 d_walk(parent, &data, select_    1611                 d_walk(parent, &data, select_collect2);
1511                 if (data.victim) {               1612                 if (data.victim) {
                                                   >> 1613                         struct dentry *parent;
1512                         spin_lock(&data.victi    1614                         spin_lock(&data.victim->d_lock);
1513                         if (!lock_for_kill(da !! 1615                         if (!shrink_lock_dentry(data.victim)) {
1514                                 spin_unlock(&    1616                                 spin_unlock(&data.victim->d_lock);
1515                                 rcu_read_unlo    1617                                 rcu_read_unlock();
1516                         } else {                 1618                         } else {
1517                                 shrink_kill(d !! 1619                                 rcu_read_unlock();
                                                   >> 1620                                 parent = data.victim->d_parent;
                                                   >> 1621                                 if (parent != data.victim)
                                                   >> 1622                                         __dput_to_list(parent, &data.dispose);
                                                   >> 1623                                 __dentry_kill(data.victim);
1518                         }                        1624                         }
1519                 }                                1625                 }
1520                 if (!list_empty(&data.dispose    1626                 if (!list_empty(&data.dispose))
1521                         shrink_dentry_list(&d    1627                         shrink_dentry_list(&data.dispose);
1522         }                                        1628         }
1523 }                                                1629 }
1524 EXPORT_SYMBOL(shrink_dcache_parent);             1630 EXPORT_SYMBOL(shrink_dcache_parent);
1525                                                  1631 
1526 static enum d_walk_ret umount_check(void *_da    1632 static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
1527 {                                                1633 {
1528         /* it has busy descendents; complain     1634         /* it has busy descendents; complain about those instead */
1529         if (!hlist_empty(&dentry->d_children) !! 1635         if (!list_empty(&dentry->d_subdirs))
1530                 return D_WALK_CONTINUE;          1636                 return D_WALK_CONTINUE;
1531                                                  1637 
1532         /* root with refcount 1 is fine */       1638         /* root with refcount 1 is fine */
1533         if (dentry == _data && dentry->d_lock    1639         if (dentry == _data && dentry->d_lockref.count == 1)
1534                 return D_WALK_CONTINUE;          1640                 return D_WALK_CONTINUE;
1535                                                  1641 
1536         WARN(1, "BUG: Dentry %p{i=%lx,n=%pd}  !! 1642         printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} "
1537                         " still in use (%d) [    1643                         " still in use (%d) [unmount of %s %s]\n",
1538                        dentry,                   1644                        dentry,
1539                        dentry->d_inode ?         1645                        dentry->d_inode ?
1540                        dentry->d_inode->i_ino    1646                        dentry->d_inode->i_ino : 0UL,
1541                        dentry,                   1647                        dentry,
1542                        dentry->d_lockref.coun    1648                        dentry->d_lockref.count,
1543                        dentry->d_sb->s_type->    1649                        dentry->d_sb->s_type->name,
1544                        dentry->d_sb->s_id);      1650                        dentry->d_sb->s_id);
                                                   >> 1651         WARN_ON(1);
1545         return D_WALK_CONTINUE;                  1652         return D_WALK_CONTINUE;
1546 }                                                1653 }
1547                                                  1654 
1548 static void do_one_tree(struct dentry *dentry    1655 static void do_one_tree(struct dentry *dentry)
1549 {                                                1656 {
1550         shrink_dcache_parent(dentry);            1657         shrink_dcache_parent(dentry);
1551         d_walk(dentry, dentry, umount_check);    1658         d_walk(dentry, dentry, umount_check);
1552         d_drop(dentry);                          1659         d_drop(dentry);
1553         dput(dentry);                            1660         dput(dentry);
1554 }                                                1661 }
1555                                                  1662 
1556 /*                                               1663 /*
1557  * destroy the dentries attached to a superbl    1664  * destroy the dentries attached to a superblock on unmounting
1558  */                                              1665  */
1559 void shrink_dcache_for_umount(struct super_bl    1666 void shrink_dcache_for_umount(struct super_block *sb)
1560 {                                                1667 {
1561         struct dentry *dentry;                   1668         struct dentry *dentry;
1562                                                  1669 
1563         rwsem_assert_held_write(&sb->s_umount !! 1670         WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
1564                                                  1671 
1565         dentry = sb->s_root;                     1672         dentry = sb->s_root;
1566         sb->s_root = NULL;                       1673         sb->s_root = NULL;
1567         do_one_tree(dentry);                     1674         do_one_tree(dentry);
1568                                                  1675 
1569         while (!hlist_bl_empty(&sb->s_roots))    1676         while (!hlist_bl_empty(&sb->s_roots)) {
1570                 dentry = dget(hlist_bl_entry(    1677                 dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_roots), struct dentry, d_hash));
1571                 do_one_tree(dentry);             1678                 do_one_tree(dentry);
1572         }                                        1679         }
1573 }                                                1680 }
1574                                                  1681 
1575 static enum d_walk_ret find_submount(void *_d    1682 static enum d_walk_ret find_submount(void *_data, struct dentry *dentry)
1576 {                                                1683 {
1577         struct dentry **victim = _data;          1684         struct dentry **victim = _data;
1578         if (d_mountpoint(dentry)) {              1685         if (d_mountpoint(dentry)) {
1579                 *victim = dget_dlock(dentry); !! 1686                 __dget_dlock(dentry);
                                                   >> 1687                 *victim = dentry;
1580                 return D_WALK_QUIT;              1688                 return D_WALK_QUIT;
1581         }                                        1689         }
1582         return D_WALK_CONTINUE;                  1690         return D_WALK_CONTINUE;
1583 }                                                1691 }
1584                                                  1692 
1585 /**                                              1693 /**
1586  * d_invalidate - detach submounts, prune dca    1694  * d_invalidate - detach submounts, prune dcache, and drop
1587  * @dentry: dentry to invalidate (aka detach,    1695  * @dentry: dentry to invalidate (aka detach, prune and drop)
1588  */                                              1696  */
1589 void d_invalidate(struct dentry *dentry)         1697 void d_invalidate(struct dentry *dentry)
1590 {                                                1698 {
1591         bool had_submounts = false;              1699         bool had_submounts = false;
1592         spin_lock(&dentry->d_lock);              1700         spin_lock(&dentry->d_lock);
1593         if (d_unhashed(dentry)) {                1701         if (d_unhashed(dentry)) {
1594                 spin_unlock(&dentry->d_lock);    1702                 spin_unlock(&dentry->d_lock);
1595                 return;                          1703                 return;
1596         }                                        1704         }
1597         __d_drop(dentry);                        1705         __d_drop(dentry);
1598         spin_unlock(&dentry->d_lock);            1706         spin_unlock(&dentry->d_lock);
1599                                                  1707 
1600         /* Negative dentries can be dropped w    1708         /* Negative dentries can be dropped without further checks */
1601         if (!dentry->d_inode)                    1709         if (!dentry->d_inode)
1602                 return;                          1710                 return;
1603                                                  1711 
1604         shrink_dcache_parent(dentry);            1712         shrink_dcache_parent(dentry);
1605         for (;;) {                               1713         for (;;) {
1606                 struct dentry *victim = NULL;    1714                 struct dentry *victim = NULL;
1607                 d_walk(dentry, &victim, find_    1715                 d_walk(dentry, &victim, find_submount);
1608                 if (!victim) {                   1716                 if (!victim) {
1609                         if (had_submounts)       1717                         if (had_submounts)
1610                                 shrink_dcache    1718                                 shrink_dcache_parent(dentry);
1611                         return;                  1719                         return;
1612                 }                                1720                 }
1613                 had_submounts = true;            1721                 had_submounts = true;
1614                 detach_mounts(victim);           1722                 detach_mounts(victim);
1615                 dput(victim);                    1723                 dput(victim);
1616         }                                        1724         }
1617 }                                                1725 }
1618 EXPORT_SYMBOL(d_invalidate);                     1726 EXPORT_SYMBOL(d_invalidate);
1619                                                  1727 
1620 /**                                              1728 /**
1621  * __d_alloc    -       allocate a dcache ent    1729  * __d_alloc    -       allocate a dcache entry
1622  * @sb: filesystem it will belong to             1730  * @sb: filesystem it will belong to
1623  * @name: qstr of the name                       1731  * @name: qstr of the name
1624  *                                               1732  *
1625  * Allocates a dentry. It returns %NULL if th    1733  * Allocates a dentry. It returns %NULL if there is insufficient memory
1626  * available. On a success the dentry is retu    1734  * available. On a success the dentry is returned. The name passed in is
1627  * copied and the copy passed in may be reuse    1735  * copied and the copy passed in may be reused after this call.
1628  */                                              1736  */
1629                                                  1737  
1630 static struct dentry *__d_alloc(struct super_    1738 static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
1631 {                                                1739 {
1632         struct dentry *dentry;                   1740         struct dentry *dentry;
1633         char *dname;                             1741         char *dname;
1634         int err;                                 1742         int err;
1635                                                  1743 
1636         dentry = kmem_cache_alloc_lru(dentry_ !! 1744         dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
1637                                       GFP_KER << 
1638         if (!dentry)                             1745         if (!dentry)
1639                 return NULL;                     1746                 return NULL;
1640                                                  1747 
1641         /*                                       1748         /*
1642          * We guarantee that the inline name     1749          * We guarantee that the inline name is always NUL-terminated.
1643          * This way the memcpy() done by the     1750          * This way the memcpy() done by the name switching in rename
1644          * will still always have a NUL at th    1751          * will still always have a NUL at the end, even if we might
1645          * be overwriting an internal NUL cha    1752          * be overwriting an internal NUL character
1646          */                                      1753          */
1647         dentry->d_iname[DNAME_INLINE_LEN-1] =    1754         dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
1648         if (unlikely(!name)) {                   1755         if (unlikely(!name)) {
1649                 name = &slash_name;              1756                 name = &slash_name;
1650                 dname = dentry->d_iname;         1757                 dname = dentry->d_iname;
1651         } else if (name->len > DNAME_INLINE_L    1758         } else if (name->len > DNAME_INLINE_LEN-1) {
1652                 size_t size = offsetof(struct    1759                 size_t size = offsetof(struct external_name, name[1]);
1653                 struct external_name *p = kma    1760                 struct external_name *p = kmalloc(size + name->len,
1654                                                  1761                                                   GFP_KERNEL_ACCOUNT |
1655                                                  1762                                                   __GFP_RECLAIMABLE);
1656                 if (!p) {                        1763                 if (!p) {
1657                         kmem_cache_free(dentr    1764                         kmem_cache_free(dentry_cache, dentry); 
1658                         return NULL;             1765                         return NULL;
1659                 }                                1766                 }
1660                 atomic_set(&p->u.count, 1);      1767                 atomic_set(&p->u.count, 1);
1661                 dname = p->name;                 1768                 dname = p->name;
1662         } else  {                                1769         } else  {
1663                 dname = dentry->d_iname;         1770                 dname = dentry->d_iname;
1664         }                                        1771         }       
1665                                                  1772 
1666         dentry->d_name.len = name->len;          1773         dentry->d_name.len = name->len;
1667         dentry->d_name.hash = name->hash;        1774         dentry->d_name.hash = name->hash;
1668         memcpy(dname, name->name, name->len);    1775         memcpy(dname, name->name, name->len);
1669         dname[name->len] = 0;                    1776         dname[name->len] = 0;
1670                                                  1777 
1671         /* Make sure we always see the termin    1778         /* Make sure we always see the terminating NUL character */
1672         smp_store_release(&dentry->d_name.nam    1779         smp_store_release(&dentry->d_name.name, dname); /* ^^^ */
1673                                                  1780 
1674         dentry->d_lockref.count = 1;             1781         dentry->d_lockref.count = 1;
1675         dentry->d_flags = 0;                     1782         dentry->d_flags = 0;
1676         spin_lock_init(&dentry->d_lock);         1783         spin_lock_init(&dentry->d_lock);
1677         seqcount_spinlock_init(&dentry->d_seq    1784         seqcount_spinlock_init(&dentry->d_seq, &dentry->d_lock);
1678         dentry->d_inode = NULL;                  1785         dentry->d_inode = NULL;
1679         dentry->d_parent = dentry;               1786         dentry->d_parent = dentry;
1680         dentry->d_sb = sb;                       1787         dentry->d_sb = sb;
1681         dentry->d_op = NULL;                     1788         dentry->d_op = NULL;
1682         dentry->d_fsdata = NULL;                 1789         dentry->d_fsdata = NULL;
1683         INIT_HLIST_BL_NODE(&dentry->d_hash);     1790         INIT_HLIST_BL_NODE(&dentry->d_hash);
1684         INIT_LIST_HEAD(&dentry->d_lru);          1791         INIT_LIST_HEAD(&dentry->d_lru);
1685         INIT_HLIST_HEAD(&dentry->d_children); !! 1792         INIT_LIST_HEAD(&dentry->d_subdirs);
1686         INIT_HLIST_NODE(&dentry->d_u.d_alias)    1793         INIT_HLIST_NODE(&dentry->d_u.d_alias);
1687         INIT_HLIST_NODE(&dentry->d_sib);      !! 1794         INIT_LIST_HEAD(&dentry->d_child);
1688         d_set_d_op(dentry, dentry->d_sb->s_d_    1795         d_set_d_op(dentry, dentry->d_sb->s_d_op);
1689                                                  1796 
1690         if (dentry->d_op && dentry->d_op->d_i    1797         if (dentry->d_op && dentry->d_op->d_init) {
1691                 err = dentry->d_op->d_init(de    1798                 err = dentry->d_op->d_init(dentry);
1692                 if (err) {                       1799                 if (err) {
1693                         if (dname_external(de    1800                         if (dname_external(dentry))
1694                                 kfree(externa    1801                                 kfree(external_name(dentry));
1695                         kmem_cache_free(dentr    1802                         kmem_cache_free(dentry_cache, dentry);
1696                         return NULL;             1803                         return NULL;
1697                 }                                1804                 }
1698         }                                        1805         }
1699                                                  1806 
1700         this_cpu_inc(nr_dentry);                 1807         this_cpu_inc(nr_dentry);
1701                                                  1808 
1702         return dentry;                           1809         return dentry;
1703 }                                                1810 }
1704                                                  1811 
1705 /**                                              1812 /**
1706  * d_alloc      -       allocate a dcache ent    1813  * d_alloc      -       allocate a dcache entry
1707  * @parent: parent of entry to allocate          1814  * @parent: parent of entry to allocate
1708  * @name: qstr of the name                       1815  * @name: qstr of the name
1709  *                                               1816  *
1710  * Allocates a dentry. It returns %NULL if th    1817  * Allocates a dentry. It returns %NULL if there is insufficient memory
1711  * available. On a success the dentry is retu    1818  * available. On a success the dentry is returned. The name passed in is
1712  * copied and the copy passed in may be reuse    1819  * copied and the copy passed in may be reused after this call.
1713  */                                              1820  */
1714 struct dentry *d_alloc(struct dentry * parent    1821 struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1715 {                                                1822 {
1716         struct dentry *dentry = __d_alloc(par    1823         struct dentry *dentry = __d_alloc(parent->d_sb, name);
1717         if (!dentry)                             1824         if (!dentry)
1718                 return NULL;                     1825                 return NULL;
1719         spin_lock(&parent->d_lock);              1826         spin_lock(&parent->d_lock);
1720         /*                                       1827         /*
1721          * don't need child lock because it i    1828          * don't need child lock because it is not subject
1722          * to concurrency here                   1829          * to concurrency here
1723          */                                      1830          */
1724         dentry->d_parent = dget_dlock(parent) !! 1831         __dget_dlock(parent);
1725         hlist_add_head(&dentry->d_sib, &paren !! 1832         dentry->d_parent = parent;
                                                   >> 1833         list_add(&dentry->d_child, &parent->d_subdirs);
1726         spin_unlock(&parent->d_lock);            1834         spin_unlock(&parent->d_lock);
1727                                                  1835 
1728         return dentry;                           1836         return dentry;
1729 }                                                1837 }
1730 EXPORT_SYMBOL(d_alloc);                          1838 EXPORT_SYMBOL(d_alloc);
1731                                                  1839 
1732 struct dentry *d_alloc_anon(struct super_bloc    1840 struct dentry *d_alloc_anon(struct super_block *sb)
1733 {                                                1841 {
1734         return __d_alloc(sb, NULL);              1842         return __d_alloc(sb, NULL);
1735 }                                                1843 }
1736 EXPORT_SYMBOL(d_alloc_anon);                     1844 EXPORT_SYMBOL(d_alloc_anon);
1737                                                  1845 
1738 struct dentry *d_alloc_cursor(struct dentry *    1846 struct dentry *d_alloc_cursor(struct dentry * parent)
1739 {                                                1847 {
1740         struct dentry *dentry = d_alloc_anon(    1848         struct dentry *dentry = d_alloc_anon(parent->d_sb);
1741         if (dentry) {                            1849         if (dentry) {
1742                 dentry->d_flags |= DCACHE_DEN    1850                 dentry->d_flags |= DCACHE_DENTRY_CURSOR;
1743                 dentry->d_parent = dget(paren    1851                 dentry->d_parent = dget(parent);
1744         }                                        1852         }
1745         return dentry;                           1853         return dentry;
1746 }                                                1854 }
1747                                                  1855 
1748 /**                                              1856 /**
1749  * d_alloc_pseudo - allocate a dentry (for lo    1857  * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
1750  * @sb: the superblock                           1858  * @sb: the superblock
1751  * @name: qstr of the name                       1859  * @name: qstr of the name
1752  *                                               1860  *
1753  * For a filesystem that just pins its dentri    1861  * For a filesystem that just pins its dentries in memory and never
1754  * performs lookups at all, return an unhashe    1862  * performs lookups at all, return an unhashed IS_ROOT dentry.
1755  * This is used for pipes, sockets et.al. - t    1863  * This is used for pipes, sockets et.al. - the stuff that should
1756  * never be anyone's children or parents.  Un    1864  * never be anyone's children or parents.  Unlike all other
1757  * dentries, these will not have RCU delay be    1865  * dentries, these will not have RCU delay between dropping the
1758  * last reference and freeing them.              1866  * last reference and freeing them.
1759  *                                               1867  *
1760  * The only user is alloc_file_pseudo() and t    1868  * The only user is alloc_file_pseudo() and that's what should
1761  * be considered a public interface.  Don't u    1869  * be considered a public interface.  Don't use directly.
1762  */                                              1870  */
1763 struct dentry *d_alloc_pseudo(struct super_bl    1871 struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1764 {                                                1872 {
1765         static const struct dentry_operations << 
1766                 .d_dname = simple_dname       << 
1767         };                                    << 
1768         struct dentry *dentry = __d_alloc(sb,    1873         struct dentry *dentry = __d_alloc(sb, name);
1769         if (likely(dentry)) {                 !! 1874         if (likely(dentry))
1770                 dentry->d_flags |= DCACHE_NOR    1875                 dentry->d_flags |= DCACHE_NORCU;
1771                 if (!sb->s_d_op)              << 
1772                         d_set_d_op(dentry, &a << 
1773         }                                     << 
1774         return dentry;                           1876         return dentry;
1775 }                                                1877 }
1776                                                  1878 
1777 struct dentry *d_alloc_name(struct dentry *pa    1879 struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1778 {                                                1880 {
1779         struct qstr q;                           1881         struct qstr q;
1780                                                  1882 
1781         q.name = name;                           1883         q.name = name;
1782         q.hash_len = hashlen_string(parent, n    1884         q.hash_len = hashlen_string(parent, name);
1783         return d_alloc(parent, &q);              1885         return d_alloc(parent, &q);
1784 }                                                1886 }
1785 EXPORT_SYMBOL(d_alloc_name);                     1887 EXPORT_SYMBOL(d_alloc_name);
1786                                                  1888 
1787 void d_set_d_op(struct dentry *dentry, const     1889 void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1788 {                                                1890 {
1789         WARN_ON_ONCE(dentry->d_op);              1891         WARN_ON_ONCE(dentry->d_op);
1790         WARN_ON_ONCE(dentry->d_flags & (DCACH    1892         WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH  |
1791                                 DCACHE_OP_COM    1893                                 DCACHE_OP_COMPARE       |
1792                                 DCACHE_OP_REV    1894                                 DCACHE_OP_REVALIDATE    |
1793                                 DCACHE_OP_WEA    1895                                 DCACHE_OP_WEAK_REVALIDATE       |
1794                                 DCACHE_OP_DEL    1896                                 DCACHE_OP_DELETE        |
1795                                 DCACHE_OP_REA    1897                                 DCACHE_OP_REAL));
1796         dentry->d_op = op;                       1898         dentry->d_op = op;
1797         if (!op)                                 1899         if (!op)
1798                 return;                          1900                 return;
1799         if (op->d_hash)                          1901         if (op->d_hash)
1800                 dentry->d_flags |= DCACHE_OP_    1902                 dentry->d_flags |= DCACHE_OP_HASH;
1801         if (op->d_compare)                       1903         if (op->d_compare)
1802                 dentry->d_flags |= DCACHE_OP_    1904                 dentry->d_flags |= DCACHE_OP_COMPARE;
1803         if (op->d_revalidate)                    1905         if (op->d_revalidate)
1804                 dentry->d_flags |= DCACHE_OP_    1906                 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1805         if (op->d_weak_revalidate)               1907         if (op->d_weak_revalidate)
1806                 dentry->d_flags |= DCACHE_OP_    1908                 dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE;
1807         if (op->d_delete)                        1909         if (op->d_delete)
1808                 dentry->d_flags |= DCACHE_OP_    1910                 dentry->d_flags |= DCACHE_OP_DELETE;
1809         if (op->d_prune)                         1911         if (op->d_prune)
1810                 dentry->d_flags |= DCACHE_OP_    1912                 dentry->d_flags |= DCACHE_OP_PRUNE;
1811         if (op->d_real)                          1913         if (op->d_real)
1812                 dentry->d_flags |= DCACHE_OP_    1914                 dentry->d_flags |= DCACHE_OP_REAL;
1813                                                  1915 
1814 }                                                1916 }
1815 EXPORT_SYMBOL(d_set_d_op);                       1917 EXPORT_SYMBOL(d_set_d_op);
1816                                                  1918 
                                                   >> 1919 
                                                   >> 1920 /*
                                                   >> 1921  * d_set_fallthru - Mark a dentry as falling through to a lower layer
                                                   >> 1922  * @dentry - The dentry to mark
                                                   >> 1923  *
                                                   >> 1924  * Mark a dentry as falling through to the lower layer (as set with
                                                   >> 1925  * d_pin_lower()).  This flag may be recorded on the medium.
                                                   >> 1926  */
                                                   >> 1927 void d_set_fallthru(struct dentry *dentry)
                                                   >> 1928 {
                                                   >> 1929         spin_lock(&dentry->d_lock);
                                                   >> 1930         dentry->d_flags |= DCACHE_FALLTHRU;
                                                   >> 1931         spin_unlock(&dentry->d_lock);
                                                   >> 1932 }
                                                   >> 1933 EXPORT_SYMBOL(d_set_fallthru);
                                                   >> 1934 
1817 static unsigned d_flags_for_inode(struct inod    1935 static unsigned d_flags_for_inode(struct inode *inode)
1818 {                                                1936 {
1819         unsigned add_flags = DCACHE_REGULAR_T    1937         unsigned add_flags = DCACHE_REGULAR_TYPE;
1820                                                  1938 
1821         if (!inode)                              1939         if (!inode)
1822                 return DCACHE_MISS_TYPE;         1940                 return DCACHE_MISS_TYPE;
1823                                                  1941 
1824         if (S_ISDIR(inode->i_mode)) {            1942         if (S_ISDIR(inode->i_mode)) {
1825                 add_flags = DCACHE_DIRECTORY_    1943                 add_flags = DCACHE_DIRECTORY_TYPE;
1826                 if (unlikely(!(inode->i_opfla    1944                 if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
1827                         if (unlikely(!inode->    1945                         if (unlikely(!inode->i_op->lookup))
1828                                 add_flags = D    1946                                 add_flags = DCACHE_AUTODIR_TYPE;
1829                         else                     1947                         else
1830                                 inode->i_opfl    1948                                 inode->i_opflags |= IOP_LOOKUP;
1831                 }                                1949                 }
1832                 goto type_determined;            1950                 goto type_determined;
1833         }                                        1951         }
1834                                                  1952 
1835         if (unlikely(!(inode->i_opflags & IOP    1953         if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
1836                 if (unlikely(inode->i_op->get    1954                 if (unlikely(inode->i_op->get_link)) {
1837                         add_flags = DCACHE_SY    1955                         add_flags = DCACHE_SYMLINK_TYPE;
1838                         goto type_determined;    1956                         goto type_determined;
1839                 }                                1957                 }
1840                 inode->i_opflags |= IOP_NOFOL    1958                 inode->i_opflags |= IOP_NOFOLLOW;
1841         }                                        1959         }
1842                                                  1960 
1843         if (unlikely(!S_ISREG(inode->i_mode))    1961         if (unlikely(!S_ISREG(inode->i_mode)))
1844                 add_flags = DCACHE_SPECIAL_TY    1962                 add_flags = DCACHE_SPECIAL_TYPE;
1845                                                  1963 
1846 type_determined:                                 1964 type_determined:
1847         if (unlikely(IS_AUTOMOUNT(inode)))       1965         if (unlikely(IS_AUTOMOUNT(inode)))
1848                 add_flags |= DCACHE_NEED_AUTO    1966                 add_flags |= DCACHE_NEED_AUTOMOUNT;
1849         return add_flags;                        1967         return add_flags;
1850 }                                                1968 }
1851                                                  1969 
1852 static void __d_instantiate(struct dentry *de    1970 static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1853 {                                                1971 {
1854         unsigned add_flags = d_flags_for_inod    1972         unsigned add_flags = d_flags_for_inode(inode);
1855         WARN_ON(d_in_lookup(dentry));            1973         WARN_ON(d_in_lookup(dentry));
1856                                                  1974 
1857         spin_lock(&dentry->d_lock);              1975         spin_lock(&dentry->d_lock);
1858         /*                                       1976         /*
1859          * The negative counter only tracks d !! 1977          * Decrement negative dentry count if it was in the LRU list.
1860          * d_lru is on another list.          << 
1861          */                                      1978          */
1862         if ((dentry->d_flags &                !! 1979         if (dentry->d_flags & DCACHE_LRU_LIST)
1863              (DCACHE_LRU_LIST|DCACHE_SHRINK_L << 
1864                 this_cpu_dec(nr_dentry_negati    1980                 this_cpu_dec(nr_dentry_negative);
1865         hlist_add_head(&dentry->d_u.d_alias,     1981         hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
1866         raw_write_seqcount_begin(&dentry->d_s    1982         raw_write_seqcount_begin(&dentry->d_seq);
1867         __d_set_inode_and_type(dentry, inode,    1983         __d_set_inode_and_type(dentry, inode, add_flags);
1868         raw_write_seqcount_end(&dentry->d_seq    1984         raw_write_seqcount_end(&dentry->d_seq);
1869         fsnotify_update_flags(dentry);           1985         fsnotify_update_flags(dentry);
1870         spin_unlock(&dentry->d_lock);            1986         spin_unlock(&dentry->d_lock);
1871 }                                                1987 }
1872                                                  1988 
1873 /**                                              1989 /**
1874  * d_instantiate - fill in inode information     1990  * d_instantiate - fill in inode information for a dentry
1875  * @entry: dentry to complete                    1991  * @entry: dentry to complete
1876  * @inode: inode to attach to this dentry        1992  * @inode: inode to attach to this dentry
1877  *                                               1993  *
1878  * Fill in inode information in the entry.       1994  * Fill in inode information in the entry.
1879  *                                               1995  *
1880  * This turns negative dentries into producti    1996  * This turns negative dentries into productive full members
1881  * of society.                                   1997  * of society.
1882  *                                               1998  *
1883  * NOTE! This assumes that the inode count ha    1999  * NOTE! This assumes that the inode count has been incremented
1884  * (or otherwise set) by the caller to indica    2000  * (or otherwise set) by the caller to indicate that it is now
1885  * in use by the dcache.                         2001  * in use by the dcache.
1886  */                                              2002  */
1887                                                  2003  
1888 void d_instantiate(struct dentry *entry, stru    2004 void d_instantiate(struct dentry *entry, struct inode * inode)
1889 {                                                2005 {
1890         BUG_ON(!hlist_unhashed(&entry->d_u.d_    2006         BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
1891         if (inode) {                             2007         if (inode) {
1892                 security_d_instantiate(entry,    2008                 security_d_instantiate(entry, inode);
1893                 spin_lock(&inode->i_lock);       2009                 spin_lock(&inode->i_lock);
1894                 __d_instantiate(entry, inode)    2010                 __d_instantiate(entry, inode);
1895                 spin_unlock(&inode->i_lock);     2011                 spin_unlock(&inode->i_lock);
1896         }                                        2012         }
1897 }                                                2013 }
1898 EXPORT_SYMBOL(d_instantiate);                    2014 EXPORT_SYMBOL(d_instantiate);
1899                                                  2015 
1900 /*                                               2016 /*
1901  * This should be equivalent to d_instantiate    2017  * This should be equivalent to d_instantiate() + unlock_new_inode(),
1902  * with lockdep-related part of unlock_new_in    2018  * with lockdep-related part of unlock_new_inode() done before
1903  * anything else.  Use that instead of open-c    2019  * anything else.  Use that instead of open-coding d_instantiate()/
1904  * unlock_new_inode() combinations.              2020  * unlock_new_inode() combinations.
1905  */                                              2021  */
1906 void d_instantiate_new(struct dentry *entry,     2022 void d_instantiate_new(struct dentry *entry, struct inode *inode)
1907 {                                                2023 {
1908         BUG_ON(!hlist_unhashed(&entry->d_u.d_    2024         BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
1909         BUG_ON(!inode);                          2025         BUG_ON(!inode);
1910         lockdep_annotate_inode_mutex_key(inod    2026         lockdep_annotate_inode_mutex_key(inode);
1911         security_d_instantiate(entry, inode);    2027         security_d_instantiate(entry, inode);
1912         spin_lock(&inode->i_lock);               2028         spin_lock(&inode->i_lock);
1913         __d_instantiate(entry, inode);           2029         __d_instantiate(entry, inode);
1914         WARN_ON(!(inode->i_state & I_NEW));      2030         WARN_ON(!(inode->i_state & I_NEW));
1915         inode->i_state &= ~I_NEW & ~I_CREATIN    2031         inode->i_state &= ~I_NEW & ~I_CREATING;
1916         /*                                    << 
1917          * Pairs with the barrier in prepare_ << 
1918          * ___wait_var_event() either sees th << 
1919          * waitqueue_active() check in wake_u << 
1920          */                                   << 
1921         smp_mb();                                2032         smp_mb();
1922         inode_wake_up_bit(inode, __I_NEW);    !! 2033         wake_up_bit(&inode->i_state, __I_NEW);
1923         spin_unlock(&inode->i_lock);             2034         spin_unlock(&inode->i_lock);
1924 }                                                2035 }
1925 EXPORT_SYMBOL(d_instantiate_new);                2036 EXPORT_SYMBOL(d_instantiate_new);
1926                                                  2037 
1927 struct dentry *d_make_root(struct inode *root    2038 struct dentry *d_make_root(struct inode *root_inode)
1928 {                                                2039 {
1929         struct dentry *res = NULL;               2040         struct dentry *res = NULL;
1930                                                  2041 
1931         if (root_inode) {                        2042         if (root_inode) {
1932                 res = d_alloc_anon(root_inode    2043                 res = d_alloc_anon(root_inode->i_sb);
1933                 if (res)                         2044                 if (res)
1934                         d_instantiate(res, ro    2045                         d_instantiate(res, root_inode);
1935                 else                             2046                 else
1936                         iput(root_inode);        2047                         iput(root_inode);
1937         }                                        2048         }
1938         return res;                              2049         return res;
1939 }                                                2050 }
1940 EXPORT_SYMBOL(d_make_root);                      2051 EXPORT_SYMBOL(d_make_root);
1941                                                  2052 
                                                   >> 2053 static struct dentry *__d_instantiate_anon(struct dentry *dentry,
                                                   >> 2054                                            struct inode *inode,
                                                   >> 2055                                            bool disconnected)
                                                   >> 2056 {
                                                   >> 2057         struct dentry *res;
                                                   >> 2058         unsigned add_flags;
                                                   >> 2059 
                                                   >> 2060         security_d_instantiate(dentry, inode);
                                                   >> 2061         spin_lock(&inode->i_lock);
                                                   >> 2062         res = __d_find_any_alias(inode);
                                                   >> 2063         if (res) {
                                                   >> 2064                 spin_unlock(&inode->i_lock);
                                                   >> 2065                 dput(dentry);
                                                   >> 2066                 goto out_iput;
                                                   >> 2067         }
                                                   >> 2068 
                                                   >> 2069         /* attach a disconnected dentry */
                                                   >> 2070         add_flags = d_flags_for_inode(inode);
                                                   >> 2071 
                                                   >> 2072         if (disconnected)
                                                   >> 2073                 add_flags |= DCACHE_DISCONNECTED;
                                                   >> 2074 
                                                   >> 2075         spin_lock(&dentry->d_lock);
                                                   >> 2076         __d_set_inode_and_type(dentry, inode, add_flags);
                                                   >> 2077         hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
                                                   >> 2078         if (!disconnected) {
                                                   >> 2079                 hlist_bl_lock(&dentry->d_sb->s_roots);
                                                   >> 2080                 hlist_bl_add_head(&dentry->d_hash, &dentry->d_sb->s_roots);
                                                   >> 2081                 hlist_bl_unlock(&dentry->d_sb->s_roots);
                                                   >> 2082         }
                                                   >> 2083         spin_unlock(&dentry->d_lock);
                                                   >> 2084         spin_unlock(&inode->i_lock);
                                                   >> 2085 
                                                   >> 2086         return dentry;
                                                   >> 2087 
                                                   >> 2088  out_iput:
                                                   >> 2089         iput(inode);
                                                   >> 2090         return res;
                                                   >> 2091 }
                                                   >> 2092 
                                                   >> 2093 struct dentry *d_instantiate_anon(struct dentry *dentry, struct inode *inode)
                                                   >> 2094 {
                                                   >> 2095         return __d_instantiate_anon(dentry, inode, true);
                                                   >> 2096 }
                                                   >> 2097 EXPORT_SYMBOL(d_instantiate_anon);
                                                   >> 2098 
1942 static struct dentry *__d_obtain_alias(struct    2099 static struct dentry *__d_obtain_alias(struct inode *inode, bool disconnected)
1943 {                                                2100 {
1944         struct super_block *sb;               !! 2101         struct dentry *tmp;
1945         struct dentry *new, *res;             !! 2102         struct dentry *res;
1946                                                  2103 
1947         if (!inode)                              2104         if (!inode)
1948                 return ERR_PTR(-ESTALE);         2105                 return ERR_PTR(-ESTALE);
1949         if (IS_ERR(inode))                       2106         if (IS_ERR(inode))
1950                 return ERR_CAST(inode);          2107                 return ERR_CAST(inode);
1951                                                  2108 
1952         sb = inode->i_sb;                     !! 2109         res = d_find_any_alias(inode);
1953                                               << 
1954         res = d_find_any_alias(inode); /* exi << 
1955         if (res)                                 2110         if (res)
1956                 goto out;                     !! 2111                 goto out_iput;
1957                                                  2112 
1958         new = d_alloc_anon(sb);               !! 2113         tmp = d_alloc_anon(inode->i_sb);
1959         if (!new) {                           !! 2114         if (!tmp) {
1960                 res = ERR_PTR(-ENOMEM);          2115                 res = ERR_PTR(-ENOMEM);
1961                 goto out;                     !! 2116                 goto out_iput;
1962         }                                        2117         }
1963                                                  2118 
1964         security_d_instantiate(new, inode);   !! 2119         return __d_instantiate_anon(tmp, inode, disconnected);
1965         spin_lock(&inode->i_lock);            << 
1966         res = __d_find_any_alias(inode); /* r << 
1967         if (likely(!res)) { /* still no alias << 
1968                 unsigned add_flags = d_flags_ << 
1969                                               << 
1970                 if (disconnected)             << 
1971                         add_flags |= DCACHE_D << 
1972                                                  2120 
1973                 spin_lock(&new->d_lock);      !! 2121 out_iput:
1974                 __d_set_inode_and_type(new, i << 
1975                 hlist_add_head(&new->d_u.d_al << 
1976                 if (!disconnected) {          << 
1977                         hlist_bl_lock(&sb->s_ << 
1978                         hlist_bl_add_head(&ne << 
1979                         hlist_bl_unlock(&sb-> << 
1980                 }                             << 
1981                 spin_unlock(&new->d_lock);    << 
1982                 spin_unlock(&inode->i_lock);  << 
1983                 inode = NULL; /* consumed by  << 
1984                 res = new;                    << 
1985         } else {                              << 
1986                 spin_unlock(&inode->i_lock);  << 
1987                 dput(new);                    << 
1988         }                                     << 
1989                                               << 
1990  out:                                         << 
1991         iput(inode);                             2122         iput(inode);
1992         return res;                              2123         return res;
1993 }                                                2124 }
1994                                                  2125 
1995 /**                                              2126 /**
1996  * d_obtain_alias - find or allocate a DISCON    2127  * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
1997  * @inode: inode to allocate the dentry for      2128  * @inode: inode to allocate the dentry for
1998  *                                               2129  *
1999  * Obtain a dentry for an inode resulting fro    2130  * Obtain a dentry for an inode resulting from NFS filehandle conversion or
2000  * similar open by handle operations.  The re    2131  * similar open by handle operations.  The returned dentry may be anonymous,
2001  * or may have a full name (if the inode was     2132  * or may have a full name (if the inode was already in the cache).
2002  *                                               2133  *
2003  * When called on a directory inode, we must     2134  * When called on a directory inode, we must ensure that the inode only ever
2004  * has one dentry.  If a dentry is found, tha    2135  * has one dentry.  If a dentry is found, that is returned instead of
2005  * allocating a new one.                         2136  * allocating a new one.
2006  *                                               2137  *
2007  * On successful return, the reference to the    2138  * On successful return, the reference to the inode has been transferred
2008  * to the dentry.  In case of an error the re    2139  * to the dentry.  In case of an error the reference on the inode is released.
2009  * To make it easier to use in export operati    2140  * To make it easier to use in export operations a %NULL or IS_ERR inode may
2010  * be passed in and the error will be propaga    2141  * be passed in and the error will be propagated to the return value,
2011  * with a %NULL @inode replaced by ERR_PTR(-E    2142  * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
2012  */                                              2143  */
2013 struct dentry *d_obtain_alias(struct inode *i    2144 struct dentry *d_obtain_alias(struct inode *inode)
2014 {                                                2145 {
2015         return __d_obtain_alias(inode, true);    2146         return __d_obtain_alias(inode, true);
2016 }                                                2147 }
2017 EXPORT_SYMBOL(d_obtain_alias);                   2148 EXPORT_SYMBOL(d_obtain_alias);
2018                                                  2149 
2019 /**                                              2150 /**
2020  * d_obtain_root - find or allocate a dentry     2151  * d_obtain_root - find or allocate a dentry for a given inode
2021  * @inode: inode to allocate the dentry for      2152  * @inode: inode to allocate the dentry for
2022  *                                               2153  *
2023  * Obtain an IS_ROOT dentry for the root of a    2154  * Obtain an IS_ROOT dentry for the root of a filesystem.
2024  *                                               2155  *
2025  * We must ensure that directory inodes only     2156  * We must ensure that directory inodes only ever have one dentry.  If a
2026  * dentry is found, that is returned instead     2157  * dentry is found, that is returned instead of allocating a new one.
2027  *                                               2158  *
2028  * On successful return, the reference to the    2159  * On successful return, the reference to the inode has been transferred
2029  * to the dentry.  In case of an error the re    2160  * to the dentry.  In case of an error the reference on the inode is
2030  * released.  A %NULL or IS_ERR inode may be     2161  * released.  A %NULL or IS_ERR inode may be passed in and will be the
2031  * error will be propagate to the return valu    2162  * error will be propagate to the return value, with a %NULL @inode
2032  * replaced by ERR_PTR(-ESTALE).                 2163  * replaced by ERR_PTR(-ESTALE).
2033  */                                              2164  */
2034 struct dentry *d_obtain_root(struct inode *in    2165 struct dentry *d_obtain_root(struct inode *inode)
2035 {                                                2166 {
2036         return __d_obtain_alias(inode, false)    2167         return __d_obtain_alias(inode, false);
2037 }                                                2168 }
2038 EXPORT_SYMBOL(d_obtain_root);                    2169 EXPORT_SYMBOL(d_obtain_root);
2039                                                  2170 
2040 /**                                              2171 /**
2041  * d_add_ci - lookup or allocate new dentry w    2172  * d_add_ci - lookup or allocate new dentry with case-exact name
2042  * @inode:  the inode case-insensitive lookup    2173  * @inode:  the inode case-insensitive lookup has found
2043  * @dentry: the negative dentry that was pass    2174  * @dentry: the negative dentry that was passed to the parent's lookup func
2044  * @name:   the case-exact name to be associa    2175  * @name:   the case-exact name to be associated with the returned dentry
2045  *                                               2176  *
2046  * This is to avoid filling the dcache with c    2177  * This is to avoid filling the dcache with case-insensitive names to the
2047  * same inode, only the actual correct case i    2178  * same inode, only the actual correct case is stored in the dcache for
2048  * case-insensitive filesystems.                 2179  * case-insensitive filesystems.
2049  *                                               2180  *
2050  * For a case-insensitive lookup match and if    2181  * For a case-insensitive lookup match and if the case-exact dentry
2051  * already exists in the dcache, use it and r    2182  * already exists in the dcache, use it and return it.
2052  *                                               2183  *
2053  * If no entry exists with the exact case nam    2184  * If no entry exists with the exact case name, allocate new dentry with
2054  * the exact case, and return the spliced ent    2185  * the exact case, and return the spliced entry.
2055  */                                              2186  */
2056 struct dentry *d_add_ci(struct dentry *dentry    2187 struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
2057                         struct qstr *name)       2188                         struct qstr *name)
2058 {                                                2189 {
2059         struct dentry *found, *res;              2190         struct dentry *found, *res;
2060                                                  2191 
2061         /*                                       2192         /*
2062          * First check if a dentry matching t    2193          * First check if a dentry matching the name already exists,
2063          * if not go ahead and create it now.    2194          * if not go ahead and create it now.
2064          */                                      2195          */
2065         found = d_hash_and_lookup(dentry->d_p    2196         found = d_hash_and_lookup(dentry->d_parent, name);
2066         if (found) {                             2197         if (found) {
2067                 iput(inode);                     2198                 iput(inode);
2068                 return found;                    2199                 return found;
2069         }                                        2200         }
2070         if (d_in_lookup(dentry)) {               2201         if (d_in_lookup(dentry)) {
2071                 found = d_alloc_parallel(dent    2202                 found = d_alloc_parallel(dentry->d_parent, name,
2072                                         dentr    2203                                         dentry->d_wait);
2073                 if (IS_ERR(found) || !d_in_lo    2204                 if (IS_ERR(found) || !d_in_lookup(found)) {
2074                         iput(inode);             2205                         iput(inode);
2075                         return found;            2206                         return found;
2076                 }                                2207                 }
2077         } else {                                 2208         } else {
2078                 found = d_alloc(dentry->d_par    2209                 found = d_alloc(dentry->d_parent, name);
2079                 if (!found) {                    2210                 if (!found) {
2080                         iput(inode);             2211                         iput(inode);
2081                         return ERR_PTR(-ENOME    2212                         return ERR_PTR(-ENOMEM);
2082                 }                                2213                 } 
2083         }                                        2214         }
2084         res = d_splice_alias(inode, found);      2215         res = d_splice_alias(inode, found);
2085         if (res) {                               2216         if (res) {
2086                 d_lookup_done(found);         << 
2087                 dput(found);                     2217                 dput(found);
2088                 return res;                      2218                 return res;
2089         }                                        2219         }
2090         return found;                            2220         return found;
2091 }                                                2221 }
2092 EXPORT_SYMBOL(d_add_ci);                         2222 EXPORT_SYMBOL(d_add_ci);
2093                                                  2223 
2094 /**                                           !! 2224 
2095  * d_same_name - compare dentry name with cas !! 2225 static inline bool d_same_name(const struct dentry *dentry,
2096  * @parent: parent dentry                     !! 2226                                 const struct dentry *parent,
2097  * @dentry: the negative dentry that was pass !! 2227                                 const struct qstr *name)
2098  * @name:   the case-exact name to be associa << 
2099  *                                            << 
2100  * Return: true if names are same, or false   << 
2101  */                                           << 
2102 bool d_same_name(const struct dentry *dentry, << 
2103                  const struct qstr *name)     << 
2104 {                                                2228 {
2105         if (likely(!(parent->d_flags & DCACHE    2229         if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) {
2106                 if (dentry->d_name.len != nam    2230                 if (dentry->d_name.len != name->len)
2107                         return false;            2231                         return false;
2108                 return dentry_cmp(dentry, nam    2232                 return dentry_cmp(dentry, name->name, name->len) == 0;
2109         }                                        2233         }
2110         return parent->d_op->d_compare(dentry    2234         return parent->d_op->d_compare(dentry,
2111                                        dentry    2235                                        dentry->d_name.len, dentry->d_name.name,
2112                                        name)     2236                                        name) == 0;
2113 }                                                2237 }
2114 EXPORT_SYMBOL_GPL(d_same_name);               << 
2115                                               << 
2116 /*                                            << 
2117  * This is __d_lookup_rcu() when the parent d << 
2118  * DCACHE_OP_COMPARE, which makes things much << 
2119  */                                           << 
2120 static noinline struct dentry *__d_lookup_rcu << 
2121         const struct dentry *parent,          << 
2122         const struct qstr *name,              << 
2123         unsigned *seqp)                       << 
2124 {                                             << 
2125         u64 hashlen = name->hash_len;         << 
2126         struct hlist_bl_head *b = d_hash(hash << 
2127         struct hlist_bl_node *node;           << 
2128         struct dentry *dentry;                << 
2129                                               << 
2130         hlist_bl_for_each_entry_rcu(dentry, n << 
2131                 int tlen;                     << 
2132                 const char *tname;            << 
2133                 unsigned seq;                 << 
2134                                               << 
2135 seqretry:                                     << 
2136                 seq = raw_seqcount_begin(&den << 
2137                 if (dentry->d_parent != paren << 
2138                         continue;             << 
2139                 if (d_unhashed(dentry))       << 
2140                         continue;             << 
2141                 if (dentry->d_name.hash != ha << 
2142                         continue;             << 
2143                 tlen = dentry->d_name.len;    << 
2144                 tname = dentry->d_name.name;  << 
2145                 /* we want a consistent (name << 
2146                 if (read_seqcount_retry(&dent << 
2147                         cpu_relax();          << 
2148                         goto seqretry;        << 
2149                 }                             << 
2150                 if (parent->d_op->d_compare(d << 
2151                         continue;             << 
2152                 *seqp = seq;                  << 
2153                 return dentry;                << 
2154         }                                     << 
2155         return NULL;                          << 
2156 }                                             << 
2157                                                  2238 
2158 /**                                              2239 /**
2159  * __d_lookup_rcu - search for a dentry (racy    2240  * __d_lookup_rcu - search for a dentry (racy, store-free)
2160  * @parent: parent dentry                        2241  * @parent: parent dentry
2161  * @name: qstr of name we wish to find           2242  * @name: qstr of name we wish to find
2162  * @seqp: returns d_seq value at the point wh    2243  * @seqp: returns d_seq value at the point where the dentry was found
2163  * Returns: dentry, or NULL                      2244  * Returns: dentry, or NULL
2164  *                                               2245  *
2165  * __d_lookup_rcu is the dcache lookup functi    2246  * __d_lookup_rcu is the dcache lookup function for rcu-walk name
2166  * resolution (store-free path walking) desig    2247  * resolution (store-free path walking) design described in
2167  * Documentation/filesystems/path-lookup.txt.    2248  * Documentation/filesystems/path-lookup.txt.
2168  *                                               2249  *
2169  * This is not to be used outside core vfs.      2250  * This is not to be used outside core vfs.
2170  *                                               2251  *
2171  * __d_lookup_rcu must only be used in rcu-wa    2252  * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
2172  * held, and rcu_read_lock held. The returned    2253  * held, and rcu_read_lock held. The returned dentry must not be stored into
2173  * without taking d_lock and checking d_seq s    2254  * without taking d_lock and checking d_seq sequence count against @seq
2174  * returned here.                                2255  * returned here.
2175  *                                               2256  *
                                                   >> 2257  * A refcount may be taken on the found dentry with the d_rcu_to_refcount
                                                   >> 2258  * function.
                                                   >> 2259  *
2176  * Alternatively, __d_lookup_rcu may be calle    2260  * Alternatively, __d_lookup_rcu may be called again to look up the child of
2177  * the returned dentry, so long as its parent    2261  * the returned dentry, so long as its parent's seqlock is checked after the
2178  * child is looked up. Thus, an interlocking     2262  * child is looked up. Thus, an interlocking stepping of sequence lock checks
2179  * is formed, giving integrity down the path     2263  * is formed, giving integrity down the path walk.
2180  *                                               2264  *
2181  * NOTE! The caller *has* to check the result    2265  * NOTE! The caller *has* to check the resulting dentry against the sequence
2182  * number we've returned before using any of     2266  * number we've returned before using any of the resulting dentry state!
2183  */                                              2267  */
2184 struct dentry *__d_lookup_rcu(const struct de    2268 struct dentry *__d_lookup_rcu(const struct dentry *parent,
2185                                 const struct     2269                                 const struct qstr *name,
2186                                 unsigned *seq    2270                                 unsigned *seqp)
2187 {                                                2271 {
2188         u64 hashlen = name->hash_len;            2272         u64 hashlen = name->hash_len;
2189         const unsigned char *str = name->name    2273         const unsigned char *str = name->name;
2190         struct hlist_bl_head *b = d_hash(hash !! 2274         struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen));
2191         struct hlist_bl_node *node;              2275         struct hlist_bl_node *node;
2192         struct dentry *dentry;                   2276         struct dentry *dentry;
2193                                                  2277 
2194         /*                                       2278         /*
2195          * Note: There is significant duplica    2279          * Note: There is significant duplication with __d_lookup_rcu which is
2196          * required to prevent single threade    2280          * required to prevent single threaded performance regressions
2197          * especially on architectures where     2281          * especially on architectures where smp_rmb (in seqcounts) are costly.
2198          * Keep the two functions in sync.       2282          * Keep the two functions in sync.
2199          */                                      2283          */
2200                                                  2284 
2201         if (unlikely(parent->d_flags & DCACHE << 
2202                 return __d_lookup_rcu_op_comp << 
2203                                               << 
2204         /*                                       2285         /*
2205          * The hash list is protected using R    2286          * The hash list is protected using RCU.
2206          *                                       2287          *
2207          * Carefully use d_seq when comparing    2288          * Carefully use d_seq when comparing a candidate dentry, to avoid
2208          * races with d_move().                  2289          * races with d_move().
2209          *                                       2290          *
2210          * It is possible that concurrent ren    2291          * It is possible that concurrent renames can mess up our list
2211          * walk here and result in missing ou    2292          * walk here and result in missing our dentry, resulting in the
2212          * false-negative result. d_lookup()     2293          * false-negative result. d_lookup() protects against concurrent
2213          * renames using rename_lock seqlock.    2294          * renames using rename_lock seqlock.
2214          *                                       2295          *
2215          * See Documentation/filesystems/path    2296          * See Documentation/filesystems/path-lookup.txt for more details.
2216          */                                      2297          */
2217         hlist_bl_for_each_entry_rcu(dentry, n    2298         hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
2218                 unsigned seq;                    2299                 unsigned seq;
2219                                                  2300 
                                                   >> 2301 seqretry:
2220                 /*                               2302                 /*
2221                  * The dentry sequence count     2303                  * The dentry sequence count protects us from concurrent
2222                  * renames, and thus protects    2304                  * renames, and thus protects parent and name fields.
2223                  *                               2305                  *
2224                  * The caller must perform a     2306                  * The caller must perform a seqcount check in order
2225                  * to do anything useful with    2307                  * to do anything useful with the returned dentry.
2226                  *                               2308                  *
2227                  * NOTE! We do a "raw" seqcou    2309                  * NOTE! We do a "raw" seqcount_begin here. That means that
2228                  * we don't wait for the sequ    2310                  * we don't wait for the sequence count to stabilize if it
2229                  * is in the middle of a sequ    2311                  * is in the middle of a sequence change. If we do the slow
2230                  * dentry compare, we will do    2312                  * dentry compare, we will do seqretries until it is stable,
2231                  * and if we end up with a su    2313                  * and if we end up with a successful lookup, we actually
2232                  * want to exit RCU lookup an    2314                  * want to exit RCU lookup anyway.
2233                  *                               2315                  *
2234                  * Note that raw_seqcount_beg    2316                  * Note that raw_seqcount_begin still *does* smp_rmb(), so
2235                  * we are still guaranteed NU    2317                  * we are still guaranteed NUL-termination of ->d_name.name.
2236                  */                              2318                  */
2237                 seq = raw_seqcount_begin(&den    2319                 seq = raw_seqcount_begin(&dentry->d_seq);
2238                 if (dentry->d_parent != paren    2320                 if (dentry->d_parent != parent)
2239                         continue;                2321                         continue;
2240                 if (d_unhashed(dentry))          2322                 if (d_unhashed(dentry))
2241                         continue;                2323                         continue;
2242                 if (dentry->d_name.hash_len ! !! 2324 
2243                         continue;             !! 2325                 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
2244                 if (dentry_cmp(dentry, str, h !! 2326                         int tlen;
2245                         continue;             !! 2327                         const char *tname;
                                                   >> 2328                         if (dentry->d_name.hash != hashlen_hash(hashlen))
                                                   >> 2329                                 continue;
                                                   >> 2330                         tlen = dentry->d_name.len;
                                                   >> 2331                         tname = dentry->d_name.name;
                                                   >> 2332                         /* we want a consistent (name,len) pair */
                                                   >> 2333                         if (read_seqcount_retry(&dentry->d_seq, seq)) {
                                                   >> 2334                                 cpu_relax();
                                                   >> 2335                                 goto seqretry;
                                                   >> 2336                         }
                                                   >> 2337                         if (parent->d_op->d_compare(dentry,
                                                   >> 2338                                                     tlen, tname, name) != 0)
                                                   >> 2339                                 continue;
                                                   >> 2340                 } else {
                                                   >> 2341                         if (dentry->d_name.hash_len != hashlen)
                                                   >> 2342                                 continue;
                                                   >> 2343                         if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0)
                                                   >> 2344                                 continue;
                                                   >> 2345                 }
2246                 *seqp = seq;                     2346                 *seqp = seq;
2247                 return dentry;                   2347                 return dentry;
2248         }                                        2348         }
2249         return NULL;                             2349         return NULL;
2250 }                                                2350 }
2251                                                  2351 
2252 /**                                              2352 /**
2253  * d_lookup - search for a dentry                2353  * d_lookup - search for a dentry
2254  * @parent: parent dentry                        2354  * @parent: parent dentry
2255  * @name: qstr of name we wish to find           2355  * @name: qstr of name we wish to find
2256  * Returns: dentry, or NULL                      2356  * Returns: dentry, or NULL
2257  *                                               2357  *
2258  * d_lookup searches the children of the pare    2358  * d_lookup searches the children of the parent dentry for the name in
2259  * question. If the dentry is found its refer    2359  * question. If the dentry is found its reference count is incremented and the
2260  * dentry is returned. The caller must use dp    2360  * dentry is returned. The caller must use dput to free the entry when it has
2261  * finished using it. %NULL is returned if th    2361  * finished using it. %NULL is returned if the dentry does not exist.
2262  */                                              2362  */
2263 struct dentry *d_lookup(const struct dentry *    2363 struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name)
2264 {                                                2364 {
2265         struct dentry *dentry;                   2365         struct dentry *dentry;
2266         unsigned seq;                            2366         unsigned seq;
2267                                                  2367 
2268         do {                                     2368         do {
2269                 seq = read_seqbegin(&rename_l    2369                 seq = read_seqbegin(&rename_lock);
2270                 dentry = __d_lookup(parent, n    2370                 dentry = __d_lookup(parent, name);
2271                 if (dentry)                      2371                 if (dentry)
2272                         break;                   2372                         break;
2273         } while (read_seqretry(&rename_lock,     2373         } while (read_seqretry(&rename_lock, seq));
2274         return dentry;                           2374         return dentry;
2275 }                                                2375 }
2276 EXPORT_SYMBOL(d_lookup);                         2376 EXPORT_SYMBOL(d_lookup);
2277                                                  2377 
2278 /**                                              2378 /**
2279  * __d_lookup - search for a dentry (racy)       2379  * __d_lookup - search for a dentry (racy)
2280  * @parent: parent dentry                        2380  * @parent: parent dentry
2281  * @name: qstr of name we wish to find           2381  * @name: qstr of name we wish to find
2282  * Returns: dentry, or NULL                      2382  * Returns: dentry, or NULL
2283  *                                               2383  *
2284  * __d_lookup is like d_lookup, however it ma    2384  * __d_lookup is like d_lookup, however it may (rarely) return a
2285  * false-negative result due to unrelated ren    2385  * false-negative result due to unrelated rename activity.
2286  *                                               2386  *
2287  * __d_lookup is slightly faster by avoiding     2387  * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
2288  * however it must be used carefully, eg. wit    2388  * however it must be used carefully, eg. with a following d_lookup in
2289  * the case of failure.                          2389  * the case of failure.
2290  *                                               2390  *
2291  * __d_lookup callers must be commented.         2391  * __d_lookup callers must be commented.
2292  */                                              2392  */
2293 struct dentry *__d_lookup(const struct dentry    2393 struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
2294 {                                                2394 {
2295         unsigned int hash = name->hash;          2395         unsigned int hash = name->hash;
2296         struct hlist_bl_head *b = d_hash(hash    2396         struct hlist_bl_head *b = d_hash(hash);
2297         struct hlist_bl_node *node;              2397         struct hlist_bl_node *node;
2298         struct dentry *found = NULL;             2398         struct dentry *found = NULL;
2299         struct dentry *dentry;                   2399         struct dentry *dentry;
2300                                                  2400 
2301         /*                                       2401         /*
2302          * Note: There is significant duplica    2402          * Note: There is significant duplication with __d_lookup_rcu which is
2303          * required to prevent single threade    2403          * required to prevent single threaded performance regressions
2304          * especially on architectures where     2404          * especially on architectures where smp_rmb (in seqcounts) are costly.
2305          * Keep the two functions in sync.       2405          * Keep the two functions in sync.
2306          */                                      2406          */
2307                                                  2407 
2308         /*                                       2408         /*
2309          * The hash list is protected using R    2409          * The hash list is protected using RCU.
2310          *                                       2410          *
2311          * Take d_lock when comparing a candi    2411          * Take d_lock when comparing a candidate dentry, to avoid races
2312          * with d_move().                        2412          * with d_move().
2313          *                                       2413          *
2314          * It is possible that concurrent ren    2414          * It is possible that concurrent renames can mess up our list
2315          * walk here and result in missing ou    2415          * walk here and result in missing our dentry, resulting in the
2316          * false-negative result. d_lookup()     2416          * false-negative result. d_lookup() protects against concurrent
2317          * renames using rename_lock seqlock.    2417          * renames using rename_lock seqlock.
2318          *                                       2418          *
2319          * See Documentation/filesystems/path    2419          * See Documentation/filesystems/path-lookup.txt for more details.
2320          */                                      2420          */
2321         rcu_read_lock();                         2421         rcu_read_lock();
2322                                                  2422         
2323         hlist_bl_for_each_entry_rcu(dentry, n    2423         hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
2324                                                  2424 
2325                 if (dentry->d_name.hash != ha    2425                 if (dentry->d_name.hash != hash)
2326                         continue;                2426                         continue;
2327                                                  2427 
2328                 spin_lock(&dentry->d_lock);      2428                 spin_lock(&dentry->d_lock);
2329                 if (dentry->d_parent != paren    2429                 if (dentry->d_parent != parent)
2330                         goto next;               2430                         goto next;
2331                 if (d_unhashed(dentry))          2431                 if (d_unhashed(dentry))
2332                         goto next;               2432                         goto next;
2333                                                  2433 
2334                 if (!d_same_name(dentry, pare    2434                 if (!d_same_name(dentry, parent, name))
2335                         goto next;               2435                         goto next;
2336                                                  2436 
2337                 dentry->d_lockref.count++;       2437                 dentry->d_lockref.count++;
2338                 found = dentry;                  2438                 found = dentry;
2339                 spin_unlock(&dentry->d_lock);    2439                 spin_unlock(&dentry->d_lock);
2340                 break;                           2440                 break;
2341 next:                                            2441 next:
2342                 spin_unlock(&dentry->d_lock);    2442                 spin_unlock(&dentry->d_lock);
2343         }                                        2443         }
2344         rcu_read_unlock();                       2444         rcu_read_unlock();
2345                                                  2445 
2346         return found;                            2446         return found;
2347 }                                                2447 }
2348                                                  2448 
2349 /**                                              2449 /**
2350  * d_hash_and_lookup - hash the qstr then sea    2450  * d_hash_and_lookup - hash the qstr then search for a dentry
2351  * @dir: Directory to search in                  2451  * @dir: Directory to search in
2352  * @name: qstr of name we wish to find           2452  * @name: qstr of name we wish to find
2353  *                                               2453  *
2354  * On lookup failure NULL is returned; on bad    2454  * On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
2355  */                                              2455  */
2356 struct dentry *d_hash_and_lookup(struct dentr    2456 struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
2357 {                                                2457 {
2358         /*                                       2458         /*
2359          * Check for a fs-specific hash funct    2459          * Check for a fs-specific hash function. Note that we must
2360          * calculate the standard hash first,    2460          * calculate the standard hash first, as the d_op->d_hash()
2361          * routine may choose to leave the ha    2461          * routine may choose to leave the hash value unchanged.
2362          */                                      2462          */
2363         name->hash = full_name_hash(dir, name    2463         name->hash = full_name_hash(dir, name->name, name->len);
2364         if (dir->d_flags & DCACHE_OP_HASH) {     2464         if (dir->d_flags & DCACHE_OP_HASH) {
2365                 int err = dir->d_op->d_hash(d    2465                 int err = dir->d_op->d_hash(dir, name);
2366                 if (unlikely(err < 0))           2466                 if (unlikely(err < 0))
2367                         return ERR_PTR(err);     2467                         return ERR_PTR(err);
2368         }                                        2468         }
2369         return d_lookup(dir, name);              2469         return d_lookup(dir, name);
2370 }                                                2470 }
2371 EXPORT_SYMBOL(d_hash_and_lookup);                2471 EXPORT_SYMBOL(d_hash_and_lookup);
2372                                                  2472 
2373 /*                                               2473 /*
2374  * When a file is deleted, we have two option    2474  * When a file is deleted, we have two options:
2375  * - turn this dentry into a negative dentry     2475  * - turn this dentry into a negative dentry
2376  * - unhash this dentry and free it.             2476  * - unhash this dentry and free it.
2377  *                                               2477  *
2378  * Usually, we want to just turn this into       2478  * Usually, we want to just turn this into
2379  * a negative dentry, but if anybody else is     2479  * a negative dentry, but if anybody else is
2380  * currently using the dentry or the inode       2480  * currently using the dentry or the inode
2381  * we can't do that and we fall back on remov    2481  * we can't do that and we fall back on removing
2382  * it from the hash queues and waiting for       2482  * it from the hash queues and waiting for
2383  * it to be deleted later when it has no user    2483  * it to be deleted later when it has no users
2384  */                                              2484  */
2385                                                  2485  
2386 /**                                              2486 /**
2387  * d_delete - delete a dentry                    2487  * d_delete - delete a dentry
2388  * @dentry: The dentry to delete                 2488  * @dentry: The dentry to delete
2389  *                                               2489  *
2390  * Turn the dentry into a negative dentry if     2490  * Turn the dentry into a negative dentry if possible, otherwise
2391  * remove it from the hash queues so it can b    2491  * remove it from the hash queues so it can be deleted later
2392  */                                              2492  */
2393                                                  2493  
2394 void d_delete(struct dentry * dentry)            2494 void d_delete(struct dentry * dentry)
2395 {                                                2495 {
2396         struct inode *inode = dentry->d_inode    2496         struct inode *inode = dentry->d_inode;
2397                                                  2497 
2398         spin_lock(&inode->i_lock);               2498         spin_lock(&inode->i_lock);
2399         spin_lock(&dentry->d_lock);              2499         spin_lock(&dentry->d_lock);
2400         /*                                       2500         /*
2401          * Are we the only user?                 2501          * Are we the only user?
2402          */                                      2502          */
2403         if (dentry->d_lockref.count == 1) {      2503         if (dentry->d_lockref.count == 1) {
2404                 dentry->d_flags &= ~DCACHE_CA    2504                 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
2405                 dentry_unlink_inode(dentry);     2505                 dentry_unlink_inode(dentry);
2406         } else {                                 2506         } else {
2407                 __d_drop(dentry);                2507                 __d_drop(dentry);
2408                 spin_unlock(&dentry->d_lock);    2508                 spin_unlock(&dentry->d_lock);
2409                 spin_unlock(&inode->i_lock);     2509                 spin_unlock(&inode->i_lock);
2410         }                                        2510         }
2411 }                                                2511 }
2412 EXPORT_SYMBOL(d_delete);                         2512 EXPORT_SYMBOL(d_delete);
2413                                                  2513 
2414 static void __d_rehash(struct dentry *entry)     2514 static void __d_rehash(struct dentry *entry)
2415 {                                                2515 {
2416         struct hlist_bl_head *b = d_hash(entr    2516         struct hlist_bl_head *b = d_hash(entry->d_name.hash);
2417                                                  2517 
2418         hlist_bl_lock(b);                        2518         hlist_bl_lock(b);
2419         hlist_bl_add_head_rcu(&entry->d_hash,    2519         hlist_bl_add_head_rcu(&entry->d_hash, b);
2420         hlist_bl_unlock(b);                      2520         hlist_bl_unlock(b);
2421 }                                                2521 }
2422                                                  2522 
2423 /**                                              2523 /**
2424  * d_rehash     - add an entry back to the ha    2524  * d_rehash     - add an entry back to the hash
2425  * @entry: dentry to add to the hash             2525  * @entry: dentry to add to the hash
2426  *                                               2526  *
2427  * Adds a dentry to the hash according to its    2527  * Adds a dentry to the hash according to its name.
2428  */                                              2528  */
2429                                                  2529  
2430 void d_rehash(struct dentry * entry)             2530 void d_rehash(struct dentry * entry)
2431 {                                                2531 {
2432         spin_lock(&entry->d_lock);               2532         spin_lock(&entry->d_lock);
2433         __d_rehash(entry);                       2533         __d_rehash(entry);
2434         spin_unlock(&entry->d_lock);             2534         spin_unlock(&entry->d_lock);
2435 }                                                2535 }
2436 EXPORT_SYMBOL(d_rehash);                         2536 EXPORT_SYMBOL(d_rehash);
2437                                                  2537 
2438 static inline unsigned start_dir_add(struct i    2538 static inline unsigned start_dir_add(struct inode *dir)
2439 {                                                2539 {
2440         preempt_disable_nested();             !! 2540 
2441         for (;;) {                               2541         for (;;) {
2442                 unsigned n = dir->i_dir_seq;     2542                 unsigned n = dir->i_dir_seq;
2443                 if (!(n & 1) && cmpxchg(&dir-    2543                 if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
2444                         return n;                2544                         return n;
2445                 cpu_relax();                     2545                 cpu_relax();
2446         }                                        2546         }
2447 }                                                2547 }
2448                                                  2548 
2449 static inline void end_dir_add(struct inode * !! 2549 static inline void end_dir_add(struct inode *dir, unsigned n)
2450                                wait_queue_hea << 
2451 {                                                2550 {
2452         smp_store_release(&dir->i_dir_seq, n     2551         smp_store_release(&dir->i_dir_seq, n + 2);
2453         preempt_enable_nested();              << 
2454         wake_up_all(d_wait);                  << 
2455 }                                                2552 }
2456                                                  2553 
2457 static void d_wait_lookup(struct dentry *dent    2554 static void d_wait_lookup(struct dentry *dentry)
2458 {                                                2555 {
2459         if (d_in_lookup(dentry)) {               2556         if (d_in_lookup(dentry)) {
2460                 DECLARE_WAITQUEUE(wait, curre    2557                 DECLARE_WAITQUEUE(wait, current);
2461                 add_wait_queue(dentry->d_wait    2558                 add_wait_queue(dentry->d_wait, &wait);
2462                 do {                             2559                 do {
2463                         set_current_state(TAS    2560                         set_current_state(TASK_UNINTERRUPTIBLE);
2464                         spin_unlock(&dentry->    2561                         spin_unlock(&dentry->d_lock);
2465                         schedule();              2562                         schedule();
2466                         spin_lock(&dentry->d_    2563                         spin_lock(&dentry->d_lock);
2467                 } while (d_in_lookup(dentry))    2564                 } while (d_in_lookup(dentry));
2468         }                                        2565         }
2469 }                                                2566 }
2470                                                  2567 
2471 struct dentry *d_alloc_parallel(struct dentry    2568 struct dentry *d_alloc_parallel(struct dentry *parent,
2472                                 const struct     2569                                 const struct qstr *name,
2473                                 wait_queue_he    2570                                 wait_queue_head_t *wq)
2474 {                                                2571 {
2475         unsigned int hash = name->hash;          2572         unsigned int hash = name->hash;
2476         struct hlist_bl_head *b = in_lookup_h    2573         struct hlist_bl_head *b = in_lookup_hash(parent, hash);
2477         struct hlist_bl_node *node;              2574         struct hlist_bl_node *node;
2478         struct dentry *new = d_alloc(parent,     2575         struct dentry *new = d_alloc(parent, name);
2479         struct dentry *dentry;                   2576         struct dentry *dentry;
2480         unsigned seq, r_seq, d_seq;              2577         unsigned seq, r_seq, d_seq;
2481                                                  2578 
2482         if (unlikely(!new))                      2579         if (unlikely(!new))
2483                 return ERR_PTR(-ENOMEM);         2580                 return ERR_PTR(-ENOMEM);
2484                                                  2581 
2485 retry:                                           2582 retry:
2486         rcu_read_lock();                         2583         rcu_read_lock();
2487         seq = smp_load_acquire(&parent->d_ino    2584         seq = smp_load_acquire(&parent->d_inode->i_dir_seq);
2488         r_seq = read_seqbegin(&rename_lock);     2585         r_seq = read_seqbegin(&rename_lock);
2489         dentry = __d_lookup_rcu(parent, name,    2586         dentry = __d_lookup_rcu(parent, name, &d_seq);
2490         if (unlikely(dentry)) {                  2587         if (unlikely(dentry)) {
2491                 if (!lockref_get_not_dead(&de    2588                 if (!lockref_get_not_dead(&dentry->d_lockref)) {
2492                         rcu_read_unlock();       2589                         rcu_read_unlock();
2493                         goto retry;              2590                         goto retry;
2494                 }                                2591                 }
2495                 if (read_seqcount_retry(&dent    2592                 if (read_seqcount_retry(&dentry->d_seq, d_seq)) {
2496                         rcu_read_unlock();       2593                         rcu_read_unlock();
2497                         dput(dentry);            2594                         dput(dentry);
2498                         goto retry;              2595                         goto retry;
2499                 }                                2596                 }
2500                 rcu_read_unlock();               2597                 rcu_read_unlock();
2501                 dput(new);                       2598                 dput(new);
2502                 return dentry;                   2599                 return dentry;
2503         }                                        2600         }
2504         if (unlikely(read_seqretry(&rename_lo    2601         if (unlikely(read_seqretry(&rename_lock, r_seq))) {
2505                 rcu_read_unlock();               2602                 rcu_read_unlock();
2506                 goto retry;                      2603                 goto retry;
2507         }                                        2604         }
2508                                                  2605 
2509         if (unlikely(seq & 1)) {                 2606         if (unlikely(seq & 1)) {
2510                 rcu_read_unlock();               2607                 rcu_read_unlock();
2511                 goto retry;                      2608                 goto retry;
2512         }                                        2609         }
2513                                                  2610 
2514         hlist_bl_lock(b);                        2611         hlist_bl_lock(b);
2515         if (unlikely(READ_ONCE(parent->d_inod    2612         if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) {
2516                 hlist_bl_unlock(b);              2613                 hlist_bl_unlock(b);
2517                 rcu_read_unlock();               2614                 rcu_read_unlock();
2518                 goto retry;                      2615                 goto retry;
2519         }                                        2616         }
2520         /*                                       2617         /*
2521          * No changes for the parent since th    2618          * No changes for the parent since the beginning of d_lookup().
2522          * Since all removals from the chain     2619          * Since all removals from the chain happen with hlist_bl_lock(),
2523          * any potential in-lookup matches ar    2620          * any potential in-lookup matches are going to stay here until
2524          * we unlock the chain.  All fields a    2621          * we unlock the chain.  All fields are stable in everything
2525          * we encounter.                         2622          * we encounter.
2526          */                                      2623          */
2527         hlist_bl_for_each_entry(dentry, node,    2624         hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) {
2528                 if (dentry->d_name.hash != ha    2625                 if (dentry->d_name.hash != hash)
2529                         continue;                2626                         continue;
2530                 if (dentry->d_parent != paren    2627                 if (dentry->d_parent != parent)
2531                         continue;                2628                         continue;
2532                 if (!d_same_name(dentry, pare    2629                 if (!d_same_name(dentry, parent, name))
2533                         continue;                2630                         continue;
2534                 hlist_bl_unlock(b);              2631                 hlist_bl_unlock(b);
2535                 /* now we can try to grab a r    2632                 /* now we can try to grab a reference */
2536                 if (!lockref_get_not_dead(&de    2633                 if (!lockref_get_not_dead(&dentry->d_lockref)) {
2537                         rcu_read_unlock();       2634                         rcu_read_unlock();
2538                         goto retry;              2635                         goto retry;
2539                 }                                2636                 }
2540                                                  2637 
2541                 rcu_read_unlock();               2638                 rcu_read_unlock();
2542                 /*                               2639                 /*
2543                  * somebody is likely to be s    2640                  * somebody is likely to be still doing lookup for it;
2544                  * wait for them to finish       2641                  * wait for them to finish
2545                  */                              2642                  */
2546                 spin_lock(&dentry->d_lock);      2643                 spin_lock(&dentry->d_lock);
2547                 d_wait_lookup(dentry);           2644                 d_wait_lookup(dentry);
2548                 /*                               2645                 /*
2549                  * it's not in-lookup anymore    2646                  * it's not in-lookup anymore; in principle we should repeat
2550                  * everything from dcache loo    2647                  * everything from dcache lookup, but it's likely to be what
2551                  * d_lookup() would've found     2648                  * d_lookup() would've found anyway.  If it is, just return it;
2552                  * otherwise we really have t    2649                  * otherwise we really have to repeat the whole thing.
2553                  */                              2650                  */
2554                 if (unlikely(dentry->d_name.h    2651                 if (unlikely(dentry->d_name.hash != hash))
2555                         goto mismatch;           2652                         goto mismatch;
2556                 if (unlikely(dentry->d_parent    2653                 if (unlikely(dentry->d_parent != parent))
2557                         goto mismatch;           2654                         goto mismatch;
2558                 if (unlikely(d_unhashed(dentr    2655                 if (unlikely(d_unhashed(dentry)))
2559                         goto mismatch;           2656                         goto mismatch;
2560                 if (unlikely(!d_same_name(den    2657                 if (unlikely(!d_same_name(dentry, parent, name)))
2561                         goto mismatch;           2658                         goto mismatch;
2562                 /* OK, it *is* a hashed match    2659                 /* OK, it *is* a hashed match; return it */
2563                 spin_unlock(&dentry->d_lock);    2660                 spin_unlock(&dentry->d_lock);
2564                 dput(new);                       2661                 dput(new);
2565                 return dentry;                   2662                 return dentry;
2566         }                                        2663         }
2567         rcu_read_unlock();                       2664         rcu_read_unlock();
2568         /* we can't take ->d_lock here; it's     2665         /* we can't take ->d_lock here; it's OK, though. */
2569         new->d_flags |= DCACHE_PAR_LOOKUP;       2666         new->d_flags |= DCACHE_PAR_LOOKUP;
2570         new->d_wait = wq;                        2667         new->d_wait = wq;
2571         hlist_bl_add_head(&new->d_u.d_in_look !! 2668         hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b);
2572         hlist_bl_unlock(b);                      2669         hlist_bl_unlock(b);
2573         return new;                              2670         return new;
2574 mismatch:                                        2671 mismatch:
2575         spin_unlock(&dentry->d_lock);            2672         spin_unlock(&dentry->d_lock);
2576         dput(dentry);                            2673         dput(dentry);
2577         goto retry;                              2674         goto retry;
2578 }                                                2675 }
2579 EXPORT_SYMBOL(d_alloc_parallel);                 2676 EXPORT_SYMBOL(d_alloc_parallel);
2580                                                  2677 
2581 /*                                            !! 2678 void __d_lookup_done(struct dentry *dentry)
2582  * - Unhash the dentry                        << 
2583  * - Retrieve and clear the waitqueue head in << 
2584  * - Return the waitqueue head                << 
2585  */                                           << 
2586 static wait_queue_head_t *__d_lookup_unhash(s << 
2587 {                                                2679 {
2588         wait_queue_head_t *d_wait;            !! 2680         struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent,
2589         struct hlist_bl_head *b;              !! 2681                                                  dentry->d_name.hash);
2590                                               << 
2591         lockdep_assert_held(&dentry->d_lock); << 
2592                                               << 
2593         b = in_lookup_hash(dentry->d_parent,  << 
2594         hlist_bl_lock(b);                        2682         hlist_bl_lock(b);
2595         dentry->d_flags &= ~DCACHE_PAR_LOOKUP    2683         dentry->d_flags &= ~DCACHE_PAR_LOOKUP;
2596         __hlist_bl_del(&dentry->d_u.d_in_look    2684         __hlist_bl_del(&dentry->d_u.d_in_lookup_hash);
2597         d_wait = dentry->d_wait;              !! 2685         wake_up_all(dentry->d_wait);
2598         dentry->d_wait = NULL;                   2686         dentry->d_wait = NULL;
2599         hlist_bl_unlock(b);                      2687         hlist_bl_unlock(b);
2600         INIT_HLIST_NODE(&dentry->d_u.d_alias)    2688         INIT_HLIST_NODE(&dentry->d_u.d_alias);
2601         INIT_LIST_HEAD(&dentry->d_lru);          2689         INIT_LIST_HEAD(&dentry->d_lru);
2602         return d_wait;                        << 
2603 }                                                2690 }
2604                                               !! 2691 EXPORT_SYMBOL(__d_lookup_done);
2605 void __d_lookup_unhash_wake(struct dentry *de << 
2606 {                                             << 
2607         spin_lock(&dentry->d_lock);           << 
2608         wake_up_all(__d_lookup_unhash(dentry) << 
2609         spin_unlock(&dentry->d_lock);         << 
2610 }                                             << 
2611 EXPORT_SYMBOL(__d_lookup_unhash_wake);        << 
2612                                                  2692 
2613 /* inode->i_lock held if inode is non-NULL */    2693 /* inode->i_lock held if inode is non-NULL */
2614                                                  2694 
2615 static inline void __d_add(struct dentry *den    2695 static inline void __d_add(struct dentry *dentry, struct inode *inode)
2616 {                                                2696 {
2617         wait_queue_head_t *d_wait;            << 
2618         struct inode *dir = NULL;                2697         struct inode *dir = NULL;
2619         unsigned n;                              2698         unsigned n;
2620         spin_lock(&dentry->d_lock);              2699         spin_lock(&dentry->d_lock);
2621         if (unlikely(d_in_lookup(dentry))) {     2700         if (unlikely(d_in_lookup(dentry))) {
2622                 dir = dentry->d_parent->d_ino    2701                 dir = dentry->d_parent->d_inode;
2623                 n = start_dir_add(dir);          2702                 n = start_dir_add(dir);
2624                 d_wait = __d_lookup_unhash(de !! 2703                 __d_lookup_done(dentry);
2625         }                                        2704         }
2626         if (inode) {                             2705         if (inode) {
2627                 unsigned add_flags = d_flags_    2706                 unsigned add_flags = d_flags_for_inode(inode);
2628                 hlist_add_head(&dentry->d_u.d    2707                 hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
2629                 raw_write_seqcount_begin(&den    2708                 raw_write_seqcount_begin(&dentry->d_seq);
2630                 __d_set_inode_and_type(dentry    2709                 __d_set_inode_and_type(dentry, inode, add_flags);
2631                 raw_write_seqcount_end(&dentr    2710                 raw_write_seqcount_end(&dentry->d_seq);
2632                 fsnotify_update_flags(dentry)    2711                 fsnotify_update_flags(dentry);
2633         }                                        2712         }
2634         __d_rehash(dentry);                      2713         __d_rehash(dentry);
2635         if (dir)                                 2714         if (dir)
2636                 end_dir_add(dir, n, d_wait);  !! 2715                 end_dir_add(dir, n);
2637         spin_unlock(&dentry->d_lock);            2716         spin_unlock(&dentry->d_lock);
2638         if (inode)                               2717         if (inode)
2639                 spin_unlock(&inode->i_lock);     2718                 spin_unlock(&inode->i_lock);
2640 }                                                2719 }
2641                                                  2720 
2642 /**                                              2721 /**
2643  * d_add - add dentry to hash queues             2722  * d_add - add dentry to hash queues
2644  * @entry: dentry to add                         2723  * @entry: dentry to add
2645  * @inode: The inode to attach to this dentry    2724  * @inode: The inode to attach to this dentry
2646  *                                               2725  *
2647  * This adds the entry to the hash queues and    2726  * This adds the entry to the hash queues and initializes @inode.
2648  * The entry was actually filled in earlier d    2727  * The entry was actually filled in earlier during d_alloc().
2649  */                                              2728  */
2650                                                  2729 
2651 void d_add(struct dentry *entry, struct inode    2730 void d_add(struct dentry *entry, struct inode *inode)
2652 {                                                2731 {
2653         if (inode) {                             2732         if (inode) {
2654                 security_d_instantiate(entry,    2733                 security_d_instantiate(entry, inode);
2655                 spin_lock(&inode->i_lock);       2734                 spin_lock(&inode->i_lock);
2656         }                                        2735         }
2657         __d_add(entry, inode);                   2736         __d_add(entry, inode);
2658 }                                                2737 }
2659 EXPORT_SYMBOL(d_add);                            2738 EXPORT_SYMBOL(d_add);
2660                                                  2739 
2661 /**                                              2740 /**
2662  * d_exact_alias - find and hash an exact unh    2741  * d_exact_alias - find and hash an exact unhashed alias
2663  * @entry: dentry to add                         2742  * @entry: dentry to add
2664  * @inode: The inode to go with this dentry      2743  * @inode: The inode to go with this dentry
2665  *                                               2744  *
2666  * If an unhashed dentry with the same name/p    2745  * If an unhashed dentry with the same name/parent and desired
2667  * inode already exists, hash and return it.     2746  * inode already exists, hash and return it.  Otherwise, return
2668  * NULL.                                         2747  * NULL.
2669  *                                               2748  *
2670  * Parent directory should be locked.            2749  * Parent directory should be locked.
2671  */                                              2750  */
2672 struct dentry *d_exact_alias(struct dentry *e    2751 struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode)
2673 {                                                2752 {
2674         struct dentry *alias;                    2753         struct dentry *alias;
2675         unsigned int hash = entry->d_name.has    2754         unsigned int hash = entry->d_name.hash;
2676                                                  2755 
2677         spin_lock(&inode->i_lock);               2756         spin_lock(&inode->i_lock);
2678         hlist_for_each_entry(alias, &inode->i    2757         hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
2679                 /*                               2758                 /*
2680                  * Don't need alias->d_lock h    2759                  * Don't need alias->d_lock here, because aliases with
2681                  * d_parent == entry->d_paren    2760                  * d_parent == entry->d_parent are not subject to name or
2682                  * parent changes, because th    2761                  * parent changes, because the parent inode i_mutex is held.
2683                  */                              2762                  */
2684                 if (alias->d_name.hash != has    2763                 if (alias->d_name.hash != hash)
2685                         continue;                2764                         continue;
2686                 if (alias->d_parent != entry-    2765                 if (alias->d_parent != entry->d_parent)
2687                         continue;                2766                         continue;
2688                 if (!d_same_name(alias, entry    2767                 if (!d_same_name(alias, entry->d_parent, &entry->d_name))
2689                         continue;                2768                         continue;
2690                 spin_lock(&alias->d_lock);       2769                 spin_lock(&alias->d_lock);
2691                 if (!d_unhashed(alias)) {        2770                 if (!d_unhashed(alias)) {
2692                         spin_unlock(&alias->d    2771                         spin_unlock(&alias->d_lock);
2693                         alias = NULL;            2772                         alias = NULL;
2694                 } else {                         2773                 } else {
2695                         dget_dlock(alias);    !! 2774                         __dget_dlock(alias);
2696                         __d_rehash(alias);       2775                         __d_rehash(alias);
2697                         spin_unlock(&alias->d    2776                         spin_unlock(&alias->d_lock);
2698                 }                                2777                 }
2699                 spin_unlock(&inode->i_lock);     2778                 spin_unlock(&inode->i_lock);
2700                 return alias;                    2779                 return alias;
2701         }                                        2780         }
2702         spin_unlock(&inode->i_lock);             2781         spin_unlock(&inode->i_lock);
2703         return NULL;                             2782         return NULL;
2704 }                                                2783 }
2705 EXPORT_SYMBOL(d_exact_alias);                    2784 EXPORT_SYMBOL(d_exact_alias);
2706                                                  2785 
2707 static void swap_names(struct dentry *dentry,    2786 static void swap_names(struct dentry *dentry, struct dentry *target)
2708 {                                                2787 {
2709         if (unlikely(dname_external(target)))    2788         if (unlikely(dname_external(target))) {
2710                 if (unlikely(dname_external(d    2789                 if (unlikely(dname_external(dentry))) {
2711                         /*                       2790                         /*
2712                          * Both external: swa    2791                          * Both external: swap the pointers
2713                          */                      2792                          */
2714                         swap(target->d_name.n    2793                         swap(target->d_name.name, dentry->d_name.name);
2715                 } else {                         2794                 } else {
2716                         /*                       2795                         /*
2717                          * dentry:internal, t    2796                          * dentry:internal, target:external.  Steal target's
2718                          * storage and make t    2797                          * storage and make target internal.
2719                          */                      2798                          */
2720                         memcpy(target->d_inam    2799                         memcpy(target->d_iname, dentry->d_name.name,
2721                                         dentr    2800                                         dentry->d_name.len + 1);
2722                         dentry->d_name.name =    2801                         dentry->d_name.name = target->d_name.name;
2723                         target->d_name.name =    2802                         target->d_name.name = target->d_iname;
2724                 }                                2803                 }
2725         } else {                                 2804         } else {
2726                 if (unlikely(dname_external(d    2805                 if (unlikely(dname_external(dentry))) {
2727                         /*                       2806                         /*
2728                          * dentry:external, t    2807                          * dentry:external, target:internal.  Give dentry's
2729                          * storage to target     2808                          * storage to target and make dentry internal
2730                          */                      2809                          */
2731                         memcpy(dentry->d_inam    2810                         memcpy(dentry->d_iname, target->d_name.name,
2732                                         targe    2811                                         target->d_name.len + 1);
2733                         target->d_name.name =    2812                         target->d_name.name = dentry->d_name.name;
2734                         dentry->d_name.name =    2813                         dentry->d_name.name = dentry->d_iname;
2735                 } else {                         2814                 } else {
2736                         /*                       2815                         /*
2737                          * Both are internal.    2816                          * Both are internal.
2738                          */                      2817                          */
2739                         unsigned int i;          2818                         unsigned int i;
2740                         BUILD_BUG_ON(!IS_ALIG    2819                         BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
2741                         for (i = 0; i < DNAME    2820                         for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
2742                                 swap(((long *    2821                                 swap(((long *) &dentry->d_iname)[i],
2743                                      ((long *    2822                                      ((long *) &target->d_iname)[i]);
2744                         }                        2823                         }
2745                 }                                2824                 }
2746         }                                        2825         }
2747         swap(dentry->d_name.hash_len, target-    2826         swap(dentry->d_name.hash_len, target->d_name.hash_len);
2748 }                                                2827 }
2749                                                  2828 
2750 static void copy_name(struct dentry *dentry,     2829 static void copy_name(struct dentry *dentry, struct dentry *target)
2751 {                                                2830 {
2752         struct external_name *old_name = NULL    2831         struct external_name *old_name = NULL;
2753         if (unlikely(dname_external(dentry)))    2832         if (unlikely(dname_external(dentry)))
2754                 old_name = external_name(dent    2833                 old_name = external_name(dentry);
2755         if (unlikely(dname_external(target)))    2834         if (unlikely(dname_external(target))) {
2756                 atomic_inc(&external_name(tar    2835                 atomic_inc(&external_name(target)->u.count);
2757                 dentry->d_name = target->d_na    2836                 dentry->d_name = target->d_name;
2758         } else {                                 2837         } else {
2759                 memcpy(dentry->d_iname, targe    2838                 memcpy(dentry->d_iname, target->d_name.name,
2760                                 target->d_nam    2839                                 target->d_name.len + 1);
2761                 dentry->d_name.name = dentry-    2840                 dentry->d_name.name = dentry->d_iname;
2762                 dentry->d_name.hash_len = tar    2841                 dentry->d_name.hash_len = target->d_name.hash_len;
2763         }                                        2842         }
2764         if (old_name && likely(atomic_dec_and    2843         if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
2765                 kfree_rcu(old_name, u.head);     2844                 kfree_rcu(old_name, u.head);
2766 }                                                2845 }
2767                                                  2846 
2768 /*                                               2847 /*
2769  * __d_move - move a dentry                      2848  * __d_move - move a dentry
2770  * @dentry: entry to move                        2849  * @dentry: entry to move
2771  * @target: new dentry                           2850  * @target: new dentry
2772  * @exchange: exchange the two dentries          2851  * @exchange: exchange the two dentries
2773  *                                               2852  *
2774  * Update the dcache to reflect the move of a    2853  * Update the dcache to reflect the move of a file name. Negative
2775  * dcache entries should not be moved in this    2854  * dcache entries should not be moved in this way. Caller must hold
2776  * rename_lock, the i_mutex of the source and    2855  * rename_lock, the i_mutex of the source and target directories,
2777  * and the sb->s_vfs_rename_mutex if they dif    2856  * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
2778  */                                              2857  */
2779 static void __d_move(struct dentry *dentry, s    2858 static void __d_move(struct dentry *dentry, struct dentry *target,
2780                      bool exchange)              2859                      bool exchange)
2781 {                                                2860 {
2782         struct dentry *old_parent, *p;           2861         struct dentry *old_parent, *p;
2783         wait_queue_head_t *d_wait;            << 
2784         struct inode *dir = NULL;                2862         struct inode *dir = NULL;
2785         unsigned n;                              2863         unsigned n;
2786                                                  2864 
2787         WARN_ON(!dentry->d_inode);               2865         WARN_ON(!dentry->d_inode);
2788         if (WARN_ON(dentry == target))           2866         if (WARN_ON(dentry == target))
2789                 return;                          2867                 return;
2790                                                  2868 
2791         BUG_ON(d_ancestor(target, dentry));      2869         BUG_ON(d_ancestor(target, dentry));
2792         old_parent = dentry->d_parent;           2870         old_parent = dentry->d_parent;
2793         p = d_ancestor(old_parent, target);      2871         p = d_ancestor(old_parent, target);
2794         if (IS_ROOT(dentry)) {                   2872         if (IS_ROOT(dentry)) {
2795                 BUG_ON(p);                       2873                 BUG_ON(p);
2796                 spin_lock(&target->d_parent->    2874                 spin_lock(&target->d_parent->d_lock);
2797         } else if (!p) {                         2875         } else if (!p) {
2798                 /* target is not a descendent    2876                 /* target is not a descendent of dentry->d_parent */
2799                 spin_lock(&target->d_parent->    2877                 spin_lock(&target->d_parent->d_lock);
2800                 spin_lock_nested(&old_parent-    2878                 spin_lock_nested(&old_parent->d_lock, DENTRY_D_LOCK_NESTED);
2801         } else {                                 2879         } else {
2802                 BUG_ON(p == dentry);             2880                 BUG_ON(p == dentry);
2803                 spin_lock(&old_parent->d_lock    2881                 spin_lock(&old_parent->d_lock);
2804                 if (p != target)                 2882                 if (p != target)
2805                         spin_lock_nested(&tar    2883                         spin_lock_nested(&target->d_parent->d_lock,
2806                                         DENTR    2884                                         DENTRY_D_LOCK_NESTED);
2807         }                                        2885         }
2808         spin_lock_nested(&dentry->d_lock, 2);    2886         spin_lock_nested(&dentry->d_lock, 2);
2809         spin_lock_nested(&target->d_lock, 3);    2887         spin_lock_nested(&target->d_lock, 3);
2810                                                  2888 
2811         if (unlikely(d_in_lookup(target))) {     2889         if (unlikely(d_in_lookup(target))) {
2812                 dir = target->d_parent->d_ino    2890                 dir = target->d_parent->d_inode;
2813                 n = start_dir_add(dir);          2891                 n = start_dir_add(dir);
2814                 d_wait = __d_lookup_unhash(ta !! 2892                 __d_lookup_done(target);
2815         }                                        2893         }
2816                                                  2894 
2817         write_seqcount_begin(&dentry->d_seq);    2895         write_seqcount_begin(&dentry->d_seq);
2818         write_seqcount_begin_nested(&target->    2896         write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
2819                                                  2897 
2820         /* unhash both */                        2898         /* unhash both */
2821         if (!d_unhashed(dentry))                 2899         if (!d_unhashed(dentry))
2822                 ___d_drop(dentry);               2900                 ___d_drop(dentry);
2823         if (!d_unhashed(target))                 2901         if (!d_unhashed(target))
2824                 ___d_drop(target);               2902                 ___d_drop(target);
2825                                                  2903 
2826         /* ... and switch them in the tree */    2904         /* ... and switch them in the tree */
2827         dentry->d_parent = target->d_parent;     2905         dentry->d_parent = target->d_parent;
2828         if (!exchange) {                         2906         if (!exchange) {
2829                 copy_name(dentry, target);       2907                 copy_name(dentry, target);
2830                 target->d_hash.pprev = NULL;     2908                 target->d_hash.pprev = NULL;
2831                 dentry->d_parent->d_lockref.c    2909                 dentry->d_parent->d_lockref.count++;
2832                 if (dentry != old_parent) /*     2910                 if (dentry != old_parent) /* wasn't IS_ROOT */
2833                         WARN_ON(!--old_parent    2911                         WARN_ON(!--old_parent->d_lockref.count);
2834         } else {                                 2912         } else {
2835                 target->d_parent = old_parent    2913                 target->d_parent = old_parent;
2836                 swap_names(dentry, target);      2914                 swap_names(dentry, target);
2837                 if (!hlist_unhashed(&target-> !! 2915                 list_move(&target->d_child, &target->d_parent->d_subdirs);
2838                         __hlist_del(&target-> << 
2839                 hlist_add_head(&target->d_sib << 
2840                 __d_rehash(target);              2916                 __d_rehash(target);
2841                 fsnotify_update_flags(target)    2917                 fsnotify_update_flags(target);
2842         }                                        2918         }
2843         if (!hlist_unhashed(&dentry->d_sib))  !! 2919         list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
2844                 __hlist_del(&dentry->d_sib);  << 
2845         hlist_add_head(&dentry->d_sib, &dentr << 
2846         __d_rehash(dentry);                      2920         __d_rehash(dentry);
2847         fsnotify_update_flags(dentry);           2921         fsnotify_update_flags(dentry);
2848         fscrypt_handle_d_move(dentry);           2922         fscrypt_handle_d_move(dentry);
2849                                                  2923 
2850         write_seqcount_end(&target->d_seq);      2924         write_seqcount_end(&target->d_seq);
2851         write_seqcount_end(&dentry->d_seq);      2925         write_seqcount_end(&dentry->d_seq);
2852                                                  2926 
2853         if (dir)                                 2927         if (dir)
2854                 end_dir_add(dir, n, d_wait);  !! 2928                 end_dir_add(dir, n);
2855                                                  2929 
2856         if (dentry->d_parent != old_parent)      2930         if (dentry->d_parent != old_parent)
2857                 spin_unlock(&dentry->d_parent    2931                 spin_unlock(&dentry->d_parent->d_lock);
2858         if (dentry != old_parent)                2932         if (dentry != old_parent)
2859                 spin_unlock(&old_parent->d_lo    2933                 spin_unlock(&old_parent->d_lock);
2860         spin_unlock(&target->d_lock);            2934         spin_unlock(&target->d_lock);
2861         spin_unlock(&dentry->d_lock);            2935         spin_unlock(&dentry->d_lock);
2862 }                                                2936 }
2863                                                  2937 
2864 /*                                               2938 /*
2865  * d_move - move a dentry                        2939  * d_move - move a dentry
2866  * @dentry: entry to move                        2940  * @dentry: entry to move
2867  * @target: new dentry                           2941  * @target: new dentry
2868  *                                               2942  *
2869  * Update the dcache to reflect the move of a    2943  * Update the dcache to reflect the move of a file name. Negative
2870  * dcache entries should not be moved in this    2944  * dcache entries should not be moved in this way. See the locking
2871  * requirements for __d_move.                    2945  * requirements for __d_move.
2872  */                                              2946  */
2873 void d_move(struct dentry *dentry, struct den    2947 void d_move(struct dentry *dentry, struct dentry *target)
2874 {                                                2948 {
2875         write_seqlock(&rename_lock);             2949         write_seqlock(&rename_lock);
2876         __d_move(dentry, target, false);         2950         __d_move(dentry, target, false);
2877         write_sequnlock(&rename_lock);           2951         write_sequnlock(&rename_lock);
2878 }                                                2952 }
2879 EXPORT_SYMBOL(d_move);                           2953 EXPORT_SYMBOL(d_move);
2880                                                  2954 
2881 /*                                               2955 /*
2882  * d_exchange - exchange two dentries            2956  * d_exchange - exchange two dentries
2883  * @dentry1: first dentry                        2957  * @dentry1: first dentry
2884  * @dentry2: second dentry                       2958  * @dentry2: second dentry
2885  */                                              2959  */
2886 void d_exchange(struct dentry *dentry1, struc    2960 void d_exchange(struct dentry *dentry1, struct dentry *dentry2)
2887 {                                                2961 {
2888         write_seqlock(&rename_lock);             2962         write_seqlock(&rename_lock);
2889                                                  2963 
2890         WARN_ON(!dentry1->d_inode);              2964         WARN_ON(!dentry1->d_inode);
2891         WARN_ON(!dentry2->d_inode);              2965         WARN_ON(!dentry2->d_inode);
2892         WARN_ON(IS_ROOT(dentry1));               2966         WARN_ON(IS_ROOT(dentry1));
2893         WARN_ON(IS_ROOT(dentry2));               2967         WARN_ON(IS_ROOT(dentry2));
2894                                                  2968 
2895         __d_move(dentry1, dentry2, true);        2969         __d_move(dentry1, dentry2, true);
2896                                                  2970 
2897         write_sequnlock(&rename_lock);           2971         write_sequnlock(&rename_lock);
2898 }                                                2972 }
2899                                                  2973 
2900 /**                                              2974 /**
2901  * d_ancestor - search for an ancestor           2975  * d_ancestor - search for an ancestor
2902  * @p1: ancestor dentry                          2976  * @p1: ancestor dentry
2903  * @p2: child dentry                             2977  * @p2: child dentry
2904  *                                               2978  *
2905  * Returns the ancestor dentry of p2 which is    2979  * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2906  * an ancestor of p2, else NULL.                 2980  * an ancestor of p2, else NULL.
2907  */                                              2981  */
2908 struct dentry *d_ancestor(struct dentry *p1,     2982 struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
2909 {                                                2983 {
2910         struct dentry *p;                        2984         struct dentry *p;
2911                                                  2985 
2912         for (p = p2; !IS_ROOT(p); p = p->d_pa    2986         for (p = p2; !IS_ROOT(p); p = p->d_parent) {
2913                 if (p->d_parent == p1)           2987                 if (p->d_parent == p1)
2914                         return p;                2988                         return p;
2915         }                                        2989         }
2916         return NULL;                             2990         return NULL;
2917 }                                                2991 }
2918                                                  2992 
2919 /*                                               2993 /*
2920  * This helper attempts to cope with remotely    2994  * This helper attempts to cope with remotely renamed directories
2921  *                                               2995  *
2922  * It assumes that the caller is already hold    2996  * It assumes that the caller is already holding
2923  * dentry->d_parent->d_inode->i_mutex, and re    2997  * dentry->d_parent->d_inode->i_mutex, and rename_lock
2924  *                                               2998  *
2925  * Note: If ever the locking in lock_rename()    2999  * Note: If ever the locking in lock_rename() changes, then please
2926  * remember to update this too...                3000  * remember to update this too...
2927  */                                              3001  */
2928 static int __d_unalias(struct dentry *dentry, !! 3002 static int __d_unalias(struct inode *inode,
                                                   >> 3003                 struct dentry *dentry, struct dentry *alias)
2929 {                                                3004 {
2930         struct mutex *m1 = NULL;                 3005         struct mutex *m1 = NULL;
2931         struct rw_semaphore *m2 = NULL;          3006         struct rw_semaphore *m2 = NULL;
2932         int ret = -ESTALE;                       3007         int ret = -ESTALE;
2933                                                  3008 
2934         /* If alias and dentry share a parent    3009         /* If alias and dentry share a parent, then no extra locks required */
2935         if (alias->d_parent == dentry->d_pare    3010         if (alias->d_parent == dentry->d_parent)
2936                 goto out_unalias;                3011                 goto out_unalias;
2937                                                  3012 
2938         /* See lock_rename() */                  3013         /* See lock_rename() */
2939         if (!mutex_trylock(&dentry->d_sb->s_v    3014         if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2940                 goto out_err;                    3015                 goto out_err;
2941         m1 = &dentry->d_sb->s_vfs_rename_mute    3016         m1 = &dentry->d_sb->s_vfs_rename_mutex;
2942         if (!inode_trylock_shared(alias->d_pa    3017         if (!inode_trylock_shared(alias->d_parent->d_inode))
2943                 goto out_err;                    3018                 goto out_err;
2944         m2 = &alias->d_parent->d_inode->i_rws    3019         m2 = &alias->d_parent->d_inode->i_rwsem;
2945 out_unalias:                                     3020 out_unalias:
2946         __d_move(alias, dentry, false);          3021         __d_move(alias, dentry, false);
2947         ret = 0;                                 3022         ret = 0;
2948 out_err:                                         3023 out_err:
2949         if (m2)                                  3024         if (m2)
2950                 up_read(m2);                     3025                 up_read(m2);
2951         if (m1)                                  3026         if (m1)
2952                 mutex_unlock(m1);                3027                 mutex_unlock(m1);
2953         return ret;                              3028         return ret;
2954 }                                                3029 }
2955                                                  3030 
2956 /**                                              3031 /**
2957  * d_splice_alias - splice a disconnected den    3032  * d_splice_alias - splice a disconnected dentry into the tree if one exists
2958  * @inode:  the inode which may have a discon    3033  * @inode:  the inode which may have a disconnected dentry
2959  * @dentry: a negative dentry which we want t    3034  * @dentry: a negative dentry which we want to point to the inode.
2960  *                                               3035  *
2961  * If inode is a directory and has an IS_ROOT    3036  * If inode is a directory and has an IS_ROOT alias, then d_move that in
2962  * place of the given dentry and return it, e    3037  * place of the given dentry and return it, else simply d_add the inode
2963  * to the dentry and return NULL.                3038  * to the dentry and return NULL.
2964  *                                               3039  *
2965  * If a non-IS_ROOT directory is found, the f    3040  * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
2966  * we should error out: directories can't hav    3041  * we should error out: directories can't have multiple aliases.
2967  *                                               3042  *
2968  * This is needed in the lookup routine of an    3043  * This is needed in the lookup routine of any filesystem that is exportable
2969  * (via knfsd) so that we can build dcache pa    3044  * (via knfsd) so that we can build dcache paths to directories effectively.
2970  *                                               3045  *
2971  * If a dentry was found and moved, then it i    3046  * If a dentry was found and moved, then it is returned.  Otherwise NULL
2972  * is returned.  This matches the expected re    3047  * is returned.  This matches the expected return value of ->lookup.
2973  *                                               3048  *
2974  * Cluster filesystems may call this function    3049  * Cluster filesystems may call this function with a negative, hashed dentry.
2975  * In that case, we know that the inode will     3050  * In that case, we know that the inode will be a regular file, and also this
2976  * will only occur during atomic_open. So we     3051  * will only occur during atomic_open. So we need to check for the dentry
2977  * being already hashed only in the final cas    3052  * being already hashed only in the final case.
2978  */                                              3053  */
2979 struct dentry *d_splice_alias(struct inode *i    3054 struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
2980 {                                                3055 {
2981         if (IS_ERR(inode))                       3056         if (IS_ERR(inode))
2982                 return ERR_CAST(inode);          3057                 return ERR_CAST(inode);
2983                                                  3058 
2984         BUG_ON(!d_unhashed(dentry));             3059         BUG_ON(!d_unhashed(dentry));
2985                                                  3060 
2986         if (!inode)                              3061         if (!inode)
2987                 goto out;                        3062                 goto out;
2988                                                  3063 
2989         security_d_instantiate(dentry, inode)    3064         security_d_instantiate(dentry, inode);
2990         spin_lock(&inode->i_lock);               3065         spin_lock(&inode->i_lock);
2991         if (S_ISDIR(inode->i_mode)) {            3066         if (S_ISDIR(inode->i_mode)) {
2992                 struct dentry *new = __d_find    3067                 struct dentry *new = __d_find_any_alias(inode);
2993                 if (unlikely(new)) {             3068                 if (unlikely(new)) {
2994                         /* The reference to n    3069                         /* The reference to new ensures it remains an alias */
2995                         spin_unlock(&inode->i    3070                         spin_unlock(&inode->i_lock);
2996                         write_seqlock(&rename    3071                         write_seqlock(&rename_lock);
2997                         if (unlikely(d_ancest    3072                         if (unlikely(d_ancestor(new, dentry))) {
2998                                 write_sequnlo    3073                                 write_sequnlock(&rename_lock);
2999                                 dput(new);       3074                                 dput(new);
3000                                 new = ERR_PTR    3075                                 new = ERR_PTR(-ELOOP);
3001                                 pr_warn_ratel    3076                                 pr_warn_ratelimited(
3002                                         "VFS:    3077                                         "VFS: Lookup of '%s' in %s %s"
3003                                         " wou    3078                                         " would have caused loop\n",
3004                                         dentr    3079                                         dentry->d_name.name,
3005                                         inode    3080                                         inode->i_sb->s_type->name,
3006                                         inode    3081                                         inode->i_sb->s_id);
3007                         } else if (!IS_ROOT(n    3082                         } else if (!IS_ROOT(new)) {
3008                                 struct dentry    3083                                 struct dentry *old_parent = dget(new->d_parent);
3009                                 int err = __d !! 3084                                 int err = __d_unalias(inode, dentry, new);
3010                                 write_sequnlo    3085                                 write_sequnlock(&rename_lock);
3011                                 if (err) {       3086                                 if (err) {
3012                                         dput(    3087                                         dput(new);
3013                                         new =    3088                                         new = ERR_PTR(err);
3014                                 }                3089                                 }
3015                                 dput(old_pare    3090                                 dput(old_parent);
3016                         } else {                 3091                         } else {
3017                                 __d_move(new,    3092                                 __d_move(new, dentry, false);
3018                                 write_sequnlo    3093                                 write_sequnlock(&rename_lock);
3019                         }                        3094                         }
3020                         iput(inode);             3095                         iput(inode);
3021                         return new;              3096                         return new;
3022                 }                                3097                 }
3023         }                                        3098         }
3024 out:                                             3099 out:
3025         __d_add(dentry, inode);                  3100         __d_add(dentry, inode);
3026         return NULL;                             3101         return NULL;
3027 }                                                3102 }
3028 EXPORT_SYMBOL(d_splice_alias);                   3103 EXPORT_SYMBOL(d_splice_alias);
3029                                                  3104 
3030 /*                                               3105 /*
3031  * Test whether new_dentry is a subdirectory     3106  * Test whether new_dentry is a subdirectory of old_dentry.
3032  *                                               3107  *
3033  * Trivially implemented using the dcache str    3108  * Trivially implemented using the dcache structure
3034  */                                              3109  */
3035                                                  3110 
3036 /**                                              3111 /**
3037  * is_subdir - is new dentry a subdirectory o    3112  * is_subdir - is new dentry a subdirectory of old_dentry
3038  * @new_dentry: new dentry                       3113  * @new_dentry: new dentry
3039  * @old_dentry: old dentry                       3114  * @old_dentry: old dentry
3040  *                                               3115  *
3041  * Returns true if new_dentry is a subdirecto    3116  * Returns true if new_dentry is a subdirectory of the parent (at any depth).
3042  * Returns false otherwise.                      3117  * Returns false otherwise.
3043  * Caller must ensure that "new_dentry" is pi    3118  * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
3044  */                                              3119  */
3045                                                  3120   
3046 bool is_subdir(struct dentry *new_dentry, str    3121 bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
3047 {                                                3122 {
3048         bool subdir;                          !! 3123         bool result;
3049         unsigned seq;                            3124         unsigned seq;
3050                                                  3125 
3051         if (new_dentry == old_dentry)            3126         if (new_dentry == old_dentry)
3052                 return true;                     3127                 return true;
3053                                                  3128 
3054         /* Access d_parent under rcu as d_mov !! 3129         do {
3055         rcu_read_lock();                      !! 3130                 /* for restarting inner loop in case of seq retry */
3056         seq = read_seqbegin(&rename_lock);    !! 3131                 seq = read_seqbegin(&rename_lock);
3057         subdir = d_ancestor(old_dentry, new_d !! 3132                 /*
3058          /* Try lockless once... */           !! 3133                  * Need rcu_readlock to protect against the d_parent trashing
3059         if (read_seqretry(&rename_lock, seq)) !! 3134                  * due to d_move
3060                 /* ...else acquire lock for p !! 3135                  */
3061                 read_seqlock_excl(&rename_loc !! 3136                 rcu_read_lock();
3062                 subdir = d_ancestor(old_dentr !! 3137                 if (d_ancestor(old_dentry, new_dentry))
3063                 read_sequnlock_excl(&rename_l !! 3138                         result = true;
3064         }                                     !! 3139                 else
3065         rcu_read_unlock();                    !! 3140                         result = false;
3066         return subdir;                        !! 3141                 rcu_read_unlock();
                                                   >> 3142         } while (read_seqretry(&rename_lock, seq));
                                                   >> 3143 
                                                   >> 3144         return result;
3067 }                                                3145 }
3068 EXPORT_SYMBOL(is_subdir);                        3146 EXPORT_SYMBOL(is_subdir);
3069                                                  3147 
3070 static enum d_walk_ret d_genocide_kill(void *    3148 static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
3071 {                                                3149 {
3072         struct dentry *root = data;              3150         struct dentry *root = data;
3073         if (dentry != root) {                    3151         if (dentry != root) {
3074                 if (d_unhashed(dentry) || !de    3152                 if (d_unhashed(dentry) || !dentry->d_inode)
3075                         return D_WALK_SKIP;      3153                         return D_WALK_SKIP;
3076                                                  3154 
3077                 if (!(dentry->d_flags & DCACH    3155                 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
3078                         dentry->d_flags |= DC    3156                         dentry->d_flags |= DCACHE_GENOCIDE;
3079                         dentry->d_lockref.cou    3157                         dentry->d_lockref.count--;
3080                 }                                3158                 }
3081         }                                        3159         }
3082         return D_WALK_CONTINUE;                  3160         return D_WALK_CONTINUE;
3083 }                                                3161 }
3084                                                  3162 
3085 void d_genocide(struct dentry *parent)           3163 void d_genocide(struct dentry *parent)
3086 {                                                3164 {
3087         d_walk(parent, parent, d_genocide_kil    3165         d_walk(parent, parent, d_genocide_kill);
3088 }                                                3166 }
3089                                                  3167 
3090 void d_mark_tmpfile(struct file *file, struct !! 3168 EXPORT_SYMBOL(d_genocide);
3091 {                                             << 
3092         struct dentry *dentry = file->f_path. << 
3093                                                  3169 
                                                   >> 3170 void d_tmpfile(struct dentry *dentry, struct inode *inode)
                                                   >> 3171 {
                                                   >> 3172         inode_dec_link_count(inode);
3094         BUG_ON(dentry->d_name.name != dentry-    3173         BUG_ON(dentry->d_name.name != dentry->d_iname ||
3095                 !hlist_unhashed(&dentry->d_u.    3174                 !hlist_unhashed(&dentry->d_u.d_alias) ||
3096                 !d_unlinked(dentry));            3175                 !d_unlinked(dentry));
3097         spin_lock(&dentry->d_parent->d_lock);    3176         spin_lock(&dentry->d_parent->d_lock);
3098         spin_lock_nested(&dentry->d_lock, DEN    3177         spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
3099         dentry->d_name.len = sprintf(dentry->    3178         dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
3100                                 (unsigned lon    3179                                 (unsigned long long)inode->i_ino);
3101         spin_unlock(&dentry->d_lock);            3180         spin_unlock(&dentry->d_lock);
3102         spin_unlock(&dentry->d_parent->d_lock    3181         spin_unlock(&dentry->d_parent->d_lock);
3103 }                                             << 
3104 EXPORT_SYMBOL(d_mark_tmpfile);                << 
3105                                               << 
3106 void d_tmpfile(struct file *file, struct inod << 
3107 {                                             << 
3108         struct dentry *dentry = file->f_path. << 
3109                                               << 
3110         inode_dec_link_count(inode);          << 
3111         d_mark_tmpfile(file, inode);          << 
3112         d_instantiate(dentry, inode);            3182         d_instantiate(dentry, inode);
3113 }                                                3183 }
3114 EXPORT_SYMBOL(d_tmpfile);                        3184 EXPORT_SYMBOL(d_tmpfile);
3115                                                  3185 
3116 /*                                            << 
3117  * Obtain inode number of the parent dentry.  << 
3118  */                                           << 
3119 ino_t d_parent_ino(struct dentry *dentry)     << 
3120 {                                             << 
3121         struct dentry *parent;                << 
3122         struct inode *iparent;                << 
3123         unsigned seq;                         << 
3124         ino_t ret;                            << 
3125                                               << 
3126         scoped_guard(rcu) {                   << 
3127                 seq = raw_seqcount_begin(&den << 
3128                 parent = READ_ONCE(dentry->d_ << 
3129                 iparent = d_inode_rcu(parent) << 
3130                 if (likely(iparent)) {        << 
3131                         ret = iparent->i_ino; << 
3132                         if (!read_seqcount_re << 
3133                                 return ret;   << 
3134                 }                             << 
3135         }                                     << 
3136                                               << 
3137         spin_lock(&dentry->d_lock);           << 
3138         ret = dentry->d_parent->d_inode->i_in << 
3139         spin_unlock(&dentry->d_lock);         << 
3140         return ret;                           << 
3141 }                                             << 
3142 EXPORT_SYMBOL(d_parent_ino);                  << 
3143                                               << 
3144 static __initdata unsigned long dhash_entries    3186 static __initdata unsigned long dhash_entries;
3145 static int __init set_dhash_entries(char *str    3187 static int __init set_dhash_entries(char *str)
3146 {                                                3188 {
3147         if (!str)                                3189         if (!str)
3148                 return 0;                        3190                 return 0;
3149         dhash_entries = simple_strtoul(str, &    3191         dhash_entries = simple_strtoul(str, &str, 0);
3150         return 1;                                3192         return 1;
3151 }                                                3193 }
3152 __setup("dhash_entries=", set_dhash_entries);    3194 __setup("dhash_entries=", set_dhash_entries);
3153                                                  3195 
3154 static void __init dcache_init_early(void)       3196 static void __init dcache_init_early(void)
3155 {                                                3197 {
3156         /* If hashes are distributed across N    3198         /* If hashes are distributed across NUMA nodes, defer
3157          * hash allocation until vmalloc spac    3199          * hash allocation until vmalloc space is available.
3158          */                                      3200          */
3159         if (hashdist)                            3201         if (hashdist)
3160                 return;                          3202                 return;
3161                                                  3203 
3162         dentry_hashtable =                       3204         dentry_hashtable =
3163                 alloc_large_system_hash("Dent    3205                 alloc_large_system_hash("Dentry cache",
3164                                         sizeo    3206                                         sizeof(struct hlist_bl_head),
3165                                         dhash    3207                                         dhash_entries,
3166                                         13,      3208                                         13,
3167                                         HASH_    3209                                         HASH_EARLY | HASH_ZERO,
3168                                         &d_ha    3210                                         &d_hash_shift,
3169                                         NULL,    3211                                         NULL,
3170                                         0,       3212                                         0,
3171                                         0);      3213                                         0);
3172         d_hash_shift = 32 - d_hash_shift;        3214         d_hash_shift = 32 - d_hash_shift;
3173                                               << 
3174         runtime_const_init(shift, d_hash_shif << 
3175         runtime_const_init(ptr, dentry_hashta << 
3176 }                                                3215 }
3177                                                  3216 
3178 static void __init dcache_init(void)             3217 static void __init dcache_init(void)
3179 {                                                3218 {
3180         /*                                       3219         /*
3181          * A constructor could be added for s    3220          * A constructor could be added for stable state like the lists,
3182          * but it is probably not worth it be    3221          * but it is probably not worth it because of the cache nature
3183          * of the dcache.                        3222          * of the dcache.
3184          */                                      3223          */
3185         dentry_cache = KMEM_CACHE_USERCOPY(de    3224         dentry_cache = KMEM_CACHE_USERCOPY(dentry,
3186                 SLAB_RECLAIM_ACCOUNT|SLAB_PAN !! 3225                 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT,
3187                 d_iname);                        3226                 d_iname);
3188                                                  3227 
3189         /* Hash may have been set up in dcach    3228         /* Hash may have been set up in dcache_init_early */
3190         if (!hashdist)                           3229         if (!hashdist)
3191                 return;                          3230                 return;
3192                                                  3231 
3193         dentry_hashtable =                       3232         dentry_hashtable =
3194                 alloc_large_system_hash("Dent    3233                 alloc_large_system_hash("Dentry cache",
3195                                         sizeo    3234                                         sizeof(struct hlist_bl_head),
3196                                         dhash    3235                                         dhash_entries,
3197                                         13,      3236                                         13,
3198                                         HASH_    3237                                         HASH_ZERO,
3199                                         &d_ha    3238                                         &d_hash_shift,
3200                                         NULL,    3239                                         NULL,
3201                                         0,       3240                                         0,
3202                                         0);      3241                                         0);
3203         d_hash_shift = 32 - d_hash_shift;        3242         d_hash_shift = 32 - d_hash_shift;
3204                                               << 
3205         runtime_const_init(shift, d_hash_shif << 
3206         runtime_const_init(ptr, dentry_hashta << 
3207 }                                                3243 }
3208                                                  3244 
3209 /* SLAB cache for __getname() consumers */       3245 /* SLAB cache for __getname() consumers */
3210 struct kmem_cache *names_cachep __ro_after_in !! 3246 struct kmem_cache *names_cachep __read_mostly;
3211 EXPORT_SYMBOL(names_cachep);                     3247 EXPORT_SYMBOL(names_cachep);
3212                                                  3248 
3213 void __init vfs_caches_init_early(void)          3249 void __init vfs_caches_init_early(void)
3214 {                                                3250 {
3215         int i;                                   3251         int i;
3216                                                  3252 
3217         for (i = 0; i < ARRAY_SIZE(in_lookup_    3253         for (i = 0; i < ARRAY_SIZE(in_lookup_hashtable); i++)
3218                 INIT_HLIST_BL_HEAD(&in_lookup    3254                 INIT_HLIST_BL_HEAD(&in_lookup_hashtable[i]);
3219                                                  3255 
3220         dcache_init_early();                     3256         dcache_init_early();
3221         inode_init_early();                      3257         inode_init_early();
3222 }                                                3258 }
3223                                                  3259 
3224 void __init vfs_caches_init(void)                3260 void __init vfs_caches_init(void)
3225 {                                                3261 {
3226         names_cachep = kmem_cache_create_user    3262         names_cachep = kmem_cache_create_usercopy("names_cache", PATH_MAX, 0,
3227                         SLAB_HWCACHE_ALIGN|SL    3263                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, 0, PATH_MAX, NULL);
3228                                                  3264 
3229         dcache_init();                           3265         dcache_init();
3230         inode_init();                            3266         inode_init();
3231         files_init();                            3267         files_init();
3232         files_maxfiles_init();                   3268         files_maxfiles_init();
3233         mnt_init();                              3269         mnt_init();
3234         bdev_cache_init();                       3270         bdev_cache_init();
3235         chrdev_init();                           3271         chrdev_init();
3236 }                                                3272 }
3237                                                  3273 

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