1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * dcache.c
4 *
5 * dentry cache handling code
6 *
7 * Copyright (C) 2002, 2004 Oracle. All rights reserved.
8 */
9
10 #include <linux/fs.h>
11 #include <linux/types.h>
12 #include <linux/slab.h>
13 #include <linux/namei.h>
14
15 #include <cluster/masklog.h>
16
17 #include "ocfs2.h"
18
19 #include "alloc.h"
20 #include "dcache.h"
21 #include "dlmglue.h"
22 #include "file.h"
23 #include "inode.h"
24 #include "ocfs2_trace.h"
25
26 void ocfs2_dentry_attach_gen(struct dentry *dentry)
27 {
28 unsigned long gen =
29 OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
30 BUG_ON(d_inode(dentry));
31 dentry->d_fsdata = (void *)gen;
32 }
33
34
35 static int ocfs2_dentry_revalidate(struct dentry *dentry, unsigned int flags)
36 {
37 struct inode *inode;
38 int ret = 0; /* if all else fails, just return false */
39 struct ocfs2_super *osb;
40
41 if (flags & LOOKUP_RCU)
42 return -ECHILD;
43
44 inode = d_inode(dentry);
45 osb = OCFS2_SB(dentry->d_sb);
46
47 trace_ocfs2_dentry_revalidate(dentry, dentry->d_name.len,
48 dentry->d_name.name);
49
50 /* For a negative dentry -
51 * check the generation number of the parent and compare with the
52 * one stored in the inode.
53 */
54 if (inode == NULL) {
55 unsigned long gen = (unsigned long) dentry->d_fsdata;
56 unsigned long pgen;
57 spin_lock(&dentry->d_lock);
58 pgen = OCFS2_I(d_inode(dentry->d_parent))->ip_dir_lock_gen;
59 spin_unlock(&dentry->d_lock);
60 trace_ocfs2_dentry_revalidate_negative(dentry->d_name.len,
61 dentry->d_name.name,
62 pgen, gen);
63 if (gen != pgen)
64 goto bail;
65 goto valid;
66 }
67
68 BUG_ON(!osb);
69
70 if (inode == osb->root_inode || is_bad_inode(inode))
71 goto bail;
72
73 spin_lock(&OCFS2_I(inode)->ip_lock);
74 /* did we or someone else delete this inode? */
75 if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
76 spin_unlock(&OCFS2_I(inode)->ip_lock);
77 trace_ocfs2_dentry_revalidate_delete(
78 (unsigned long long)OCFS2_I(inode)->ip_blkno);
79 goto bail;
80 }
81 spin_unlock(&OCFS2_I(inode)->ip_lock);
82
83 /*
84 * We don't need a cluster lock to test this because once an
85 * inode nlink hits zero, it never goes back.
86 */
87 if (inode->i_nlink == 0) {
88 trace_ocfs2_dentry_revalidate_orphaned(
89 (unsigned long long)OCFS2_I(inode)->ip_blkno,
90 S_ISDIR(inode->i_mode));
91 goto bail;
92 }
93
94 /*
95 * If the last lookup failed to create dentry lock, let us
96 * redo it.
97 */
98 if (!dentry->d_fsdata) {
99 trace_ocfs2_dentry_revalidate_nofsdata(
100 (unsigned long long)OCFS2_I(inode)->ip_blkno);
101 goto bail;
102 }
103
104 valid:
105 ret = 1;
106
107 bail:
108 trace_ocfs2_dentry_revalidate_ret(ret);
109 return ret;
110 }
111
112 static int ocfs2_match_dentry(struct dentry *dentry,
113 u64 parent_blkno,
114 int skip_unhashed)
115 {
116 struct inode *parent;
117
118 /*
119 * ocfs2_lookup() does a d_splice_alias() _before_ attaching
120 * to the lock data, so we skip those here, otherwise
121 * ocfs2_dentry_attach_lock() will get its original dentry
122 * back.
123 */
124 if (!dentry->d_fsdata)
125 return 0;
126
127 if (skip_unhashed && d_unhashed(dentry))
128 return 0;
129
130 parent = d_inode(dentry->d_parent);
131 /* Name is in a different directory. */
132 if (OCFS2_I(parent)->ip_blkno != parent_blkno)
133 return 0;
134
135 return 1;
136 }
137
138 /*
139 * Walk the inode alias list, and find a dentry which has a given
140 * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
141 * is looking for a dentry_lock reference. The downconvert thread is
142 * looking to unhash aliases, so we allow it to skip any that already
143 * have that property.
144 */
145 struct dentry *ocfs2_find_local_alias(struct inode *inode,
146 u64 parent_blkno,
147 int skip_unhashed)
148 {
149 struct dentry *dentry;
150
151 spin_lock(&inode->i_lock);
152 hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
153 spin_lock(&dentry->d_lock);
154 if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
155 trace_ocfs2_find_local_alias(dentry->d_name.len,
156 dentry->d_name.name);
157
158 dget_dlock(dentry);
159 spin_unlock(&dentry->d_lock);
160 spin_unlock(&inode->i_lock);
161 return dentry;
162 }
163 spin_unlock(&dentry->d_lock);
164 }
165 spin_unlock(&inode->i_lock);
166 return NULL;
167 }
168
169 DEFINE_SPINLOCK(dentry_attach_lock);
170
171 /*
172 * Attach this dentry to a cluster lock.
173 *
174 * Dentry locks cover all links in a given directory to a particular
175 * inode. We do this so that ocfs2 can build a lock name which all
176 * nodes in the cluster can agree on at all times. Shoving full names
177 * in the cluster lock won't work due to size restrictions. Covering
178 * links inside of a directory is a good compromise because it still
179 * allows us to use the parent directory lock to synchronize
180 * operations.
181 *
182 * Call this function with the parent dir semaphore and the parent dir
183 * cluster lock held.
184 *
185 * The dir semaphore will protect us from having to worry about
186 * concurrent processes on our node trying to attach a lock at the
187 * same time.
188 *
189 * The dir cluster lock (held at either PR or EX mode) protects us
190 * from unlink and rename on other nodes.
191 *
192 * A dput() can happen asynchronously due to pruning, so we cover
193 * attaching and detaching the dentry lock with a
194 * dentry_attach_lock.
195 *
196 * A node which has done lookup on a name retains a protected read
197 * lock until final dput. If the user requests and unlink or rename,
198 * the protected read is upgraded to an exclusive lock. Other nodes
199 * who have seen the dentry will then be informed that they need to
200 * downgrade their lock, which will involve d_delete on the
201 * dentry. This happens in ocfs2_dentry_convert_worker().
202 */
203 int ocfs2_dentry_attach_lock(struct dentry *dentry,
204 struct inode *inode,
205 u64 parent_blkno)
206 {
207 int ret;
208 struct dentry *alias;
209 struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
210
211 trace_ocfs2_dentry_attach_lock(dentry->d_name.len, dentry->d_name.name,
212 (unsigned long long)parent_blkno, dl);
213
214 /*
215 * Negative dentry. We ignore these for now.
216 *
217 * XXX: Could we can improve ocfs2_dentry_revalidate() by
218 * tracking these?
219 */
220 if (!inode)
221 return 0;
222
223 if (d_really_is_negative(dentry) && dentry->d_fsdata) {
224 /* Converting a negative dentry to positive
225 Clear dentry->d_fsdata */
226 dentry->d_fsdata = dl = NULL;
227 }
228
229 if (dl) {
230 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
231 " \"%pd\": old parent: %llu, new: %llu\n",
232 dentry,
233 (unsigned long long)parent_blkno,
234 (unsigned long long)dl->dl_parent_blkno);
235 return 0;
236 }
237
238 alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
239 if (alias) {
240 /*
241 * Great, an alias exists, which means we must have a
242 * dentry lock already. We can just grab the lock off
243 * the alias and add it to the list.
244 *
245 * We're depending here on the fact that this dentry
246 * was found and exists in the dcache and so must have
247 * a reference to the dentry_lock because we can't
248 * race creates. Final dput() cannot happen on it
249 * since we have it pinned, so our reference is safe.
250 */
251 dl = alias->d_fsdata;
252 mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
253 (unsigned long long)parent_blkno,
254 (unsigned long long)OCFS2_I(inode)->ip_blkno);
255
256 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
257 " \"%pd\": old parent: %llu, new: %llu\n",
258 dentry,
259 (unsigned long long)parent_blkno,
260 (unsigned long long)dl->dl_parent_blkno);
261
262 trace_ocfs2_dentry_attach_lock_found(dl->dl_lockres.l_name,
263 (unsigned long long)parent_blkno,
264 (unsigned long long)OCFS2_I(inode)->ip_blkno);
265
266 goto out_attach;
267 }
268
269 /*
270 * There are no other aliases
271 */
272 dl = kmalloc(sizeof(*dl), GFP_NOFS);
273 if (!dl) {
274 ret = -ENOMEM;
275 mlog_errno(ret);
276 return ret;
277 }
278
279 dl->dl_count = 0;
280 /*
281 * Does this have to happen below, for all attaches, in case
282 * the struct inode gets blown away by the downconvert thread?
283 */
284 dl->dl_inode = igrab(inode);
285 dl->dl_parent_blkno = parent_blkno;
286 ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);
287
288 out_attach:
289 spin_lock(&dentry_attach_lock);
290 if (unlikely(dentry->d_fsdata && !alias)) {
291 /* d_fsdata is set by a racing thread which is doing
292 * the same thing as this thread is doing. Leave the racing
293 * thread going ahead and we return here.
294 */
295 spin_unlock(&dentry_attach_lock);
296 iput(dl->dl_inode);
297 ocfs2_lock_res_free(&dl->dl_lockres);
298 kfree(dl);
299 return 0;
300 }
301
302 dentry->d_fsdata = dl;
303 dl->dl_count++;
304 spin_unlock(&dentry_attach_lock);
305
306 /*
307 * This actually gets us our PRMODE level lock. From now on,
308 * we'll have a notification if one of these names is
309 * destroyed on another node.
310 */
311 ret = ocfs2_dentry_lock(dentry, 0);
312 if (!ret)
313 ocfs2_dentry_unlock(dentry, 0);
314 else
315 mlog_errno(ret);
316
317 /*
318 * In case of error, manually free the allocation and do the iput().
319 * We need to do this because error here means no d_instantiate(),
320 * which means iput() will not be called during dput(dentry).
321 */
322 if (ret < 0 && !alias) {
323 ocfs2_lock_res_free(&dl->dl_lockres);
324 BUG_ON(dl->dl_count != 1);
325 spin_lock(&dentry_attach_lock);
326 dentry->d_fsdata = NULL;
327 spin_unlock(&dentry_attach_lock);
328 kfree(dl);
329 iput(inode);
330 }
331
332 dput(alias);
333
334 return ret;
335 }
336
337 /*
338 * ocfs2_dentry_iput() and friends.
339 *
340 * At this point, our particular dentry is detached from the inodes
341 * alias list, so there's no way that the locking code can find it.
342 *
343 * The interesting stuff happens when we determine that our lock needs
344 * to go away because this is the last subdir alias in the
345 * system. This function needs to handle a couple things:
346 *
347 * 1) Synchronizing lock shutdown with the downconvert threads. This
348 * is already handled for us via the lockres release drop function
349 * called in ocfs2_release_dentry_lock()
350 *
351 * 2) A race may occur when we're doing our lock shutdown and
352 * another process wants to create a new dentry lock. Right now we
353 * let them race, which means that for a very short while, this
354 * node might have two locks on a lock resource. This should be a
355 * problem though because one of them is in the process of being
356 * thrown out.
357 */
358 static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
359 struct ocfs2_dentry_lock *dl)
360 {
361 iput(dl->dl_inode);
362 ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
363 ocfs2_lock_res_free(&dl->dl_lockres);
364 kfree(dl);
365 }
366
367 void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
368 struct ocfs2_dentry_lock *dl)
369 {
370 int unlock = 0;
371
372 BUG_ON(dl->dl_count == 0);
373
374 spin_lock(&dentry_attach_lock);
375 dl->dl_count--;
376 unlock = !dl->dl_count;
377 spin_unlock(&dentry_attach_lock);
378
379 if (unlock)
380 ocfs2_drop_dentry_lock(osb, dl);
381 }
382
383 static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
384 {
385 struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
386
387 if (!dl) {
388 /*
389 * No dentry lock is ok if we're disconnected or
390 * unhashed.
391 */
392 if (!(dentry->d_flags & DCACHE_DISCONNECTED) &&
393 !d_unhashed(dentry)) {
394 unsigned long long ino = 0ULL;
395 if (inode)
396 ino = (unsigned long long)OCFS2_I(inode)->ip_blkno;
397 mlog(ML_ERROR, "Dentry is missing cluster lock. "
398 "inode: %llu, d_flags: 0x%x, d_name: %pd\n",
399 ino, dentry->d_flags, dentry);
400 }
401
402 goto out;
403 }
404
405 mlog_bug_on_msg(dl->dl_count == 0, "dentry: %pd, count: %u\n",
406 dentry, dl->dl_count);
407
408 ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);
409
410 out:
411 iput(inode);
412 }
413
414 /*
415 * d_move(), but keep the locks in sync.
416 *
417 * When we are done, "dentry" will have the parent dir and name of
418 * "target", which will be thrown away.
419 *
420 * We manually update the lock of "dentry" if need be.
421 *
422 * "target" doesn't have it's dentry lock touched - we allow the later
423 * dput() to handle this for us.
424 *
425 * This is called during ocfs2_rename(), while holding parent
426 * directory locks. The dentries have already been deleted on other
427 * nodes via ocfs2_remote_dentry_delete().
428 *
429 * Normally, the VFS handles the d_move() for the file system, after
430 * the ->rename() callback. OCFS2 wants to handle this internally, so
431 * the new lock can be created atomically with respect to the cluster.
432 */
433 void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
434 struct inode *old_dir, struct inode *new_dir)
435 {
436 int ret;
437 struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
438 struct inode *inode = d_inode(dentry);
439
440 /*
441 * Move within the same directory, so the actual lock info won't
442 * change.
443 *
444 * XXX: Is there any advantage to dropping the lock here?
445 */
446 if (old_dir == new_dir)
447 goto out_move;
448
449 ocfs2_dentry_lock_put(osb, dentry->d_fsdata);
450
451 dentry->d_fsdata = NULL;
452 ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
453 if (ret)
454 mlog_errno(ret);
455
456 out_move:
457 d_move(dentry, target);
458 }
459
460 const struct dentry_operations ocfs2_dentry_ops = {
461 .d_revalidate = ocfs2_dentry_revalidate,
462 .d_iput = ocfs2_dentry_iput,
463 };
464
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