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