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(inode: d_inode(dentry: 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, len: dentry->d_name.len, |
48 | name: 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(lock: &dentry->d_lock); |
58 | pgen = OCFS2_I(inode: d_inode(dentry: dentry->d_parent))->ip_dir_lock_gen; |
59 | spin_unlock(lock: &dentry->d_lock); |
60 | trace_ocfs2_dentry_revalidate_negative(len: dentry->d_name.len, |
61 | name: 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(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(lock: &OCFS2_I(inode)->ip_lock); |
77 | trace_ocfs2_dentry_revalidate_delete( |
78 | num: (unsigned long long)OCFS2_I(inode)->ip_blkno); |
79 | goto bail; |
80 | } |
81 | spin_unlock(lock: &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 | val1: (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 | num: (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(num: 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 (!dentry->d_parent) |
128 | return 0; |
129 | |
130 | if (skip_unhashed && d_unhashed(dentry)) |
131 | return 0; |
132 | |
133 | parent = d_inode(dentry: dentry->d_parent); |
134 | /* Negative parent dentry? */ |
135 | if (!parent) |
136 | return 0; |
137 | |
138 | /* Name is in a different directory. */ |
139 | if (OCFS2_I(inode: parent)->ip_blkno != parent_blkno) |
140 | return 0; |
141 | |
142 | return 1; |
143 | } |
144 | |
145 | /* |
146 | * Walk the inode alias list, and find a dentry which has a given |
147 | * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it |
148 | * is looking for a dentry_lock reference. The downconvert thread is |
149 | * looking to unhash aliases, so we allow it to skip any that already |
150 | * have that property. |
151 | */ |
152 | struct dentry *ocfs2_find_local_alias(struct inode *inode, |
153 | u64 parent_blkno, |
154 | int skip_unhashed) |
155 | { |
156 | struct dentry *dentry; |
157 | |
158 | spin_lock(lock: &inode->i_lock); |
159 | hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
160 | spin_lock(lock: &dentry->d_lock); |
161 | if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) { |
162 | trace_ocfs2_find_local_alias(len: dentry->d_name.len, |
163 | name: dentry->d_name.name); |
164 | |
165 | dget_dlock(dentry); |
166 | spin_unlock(lock: &dentry->d_lock); |
167 | spin_unlock(lock: &inode->i_lock); |
168 | return dentry; |
169 | } |
170 | spin_unlock(lock: &dentry->d_lock); |
171 | } |
172 | spin_unlock(lock: &inode->i_lock); |
173 | return NULL; |
174 | } |
175 | |
176 | DEFINE_SPINLOCK(dentry_attach_lock); |
177 | |
178 | /* |
179 | * Attach this dentry to a cluster lock. |
180 | * |
181 | * Dentry locks cover all links in a given directory to a particular |
182 | * inode. We do this so that ocfs2 can build a lock name which all |
183 | * nodes in the cluster can agree on at all times. Shoving full names |
184 | * in the cluster lock won't work due to size restrictions. Covering |
185 | * links inside of a directory is a good compromise because it still |
186 | * allows us to use the parent directory lock to synchronize |
187 | * operations. |
188 | * |
189 | * Call this function with the parent dir semaphore and the parent dir |
190 | * cluster lock held. |
191 | * |
192 | * The dir semaphore will protect us from having to worry about |
193 | * concurrent processes on our node trying to attach a lock at the |
194 | * same time. |
195 | * |
196 | * The dir cluster lock (held at either PR or EX mode) protects us |
197 | * from unlink and rename on other nodes. |
198 | * |
199 | * A dput() can happen asynchronously due to pruning, so we cover |
200 | * attaching and detaching the dentry lock with a |
201 | * dentry_attach_lock. |
202 | * |
203 | * A node which has done lookup on a name retains a protected read |
204 | * lock until final dput. If the user requests and unlink or rename, |
205 | * the protected read is upgraded to an exclusive lock. Other nodes |
206 | * who have seen the dentry will then be informed that they need to |
207 | * downgrade their lock, which will involve d_delete on the |
208 | * dentry. This happens in ocfs2_dentry_convert_worker(). |
209 | */ |
210 | int ocfs2_dentry_attach_lock(struct dentry *dentry, |
211 | struct inode *inode, |
212 | u64 parent_blkno) |
213 | { |
214 | int ret; |
215 | struct dentry *alias; |
216 | struct ocfs2_dentry_lock *dl = dentry->d_fsdata; |
217 | |
218 | trace_ocfs2_dentry_attach_lock(len: dentry->d_name.len, name: dentry->d_name.name, |
219 | parent: (unsigned long long)parent_blkno, fsdata: dl); |
220 | |
221 | /* |
222 | * Negative dentry. We ignore these for now. |
223 | * |
224 | * XXX: Could we can improve ocfs2_dentry_revalidate() by |
225 | * tracking these? |
226 | */ |
227 | if (!inode) |
228 | return 0; |
229 | |
230 | if (d_really_is_negative(dentry) && dentry->d_fsdata) { |
231 | /* Converting a negative dentry to positive |
232 | Clear dentry->d_fsdata */ |
233 | dentry->d_fsdata = dl = NULL; |
234 | } |
235 | |
236 | if (dl) { |
237 | mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, |
238 | " \"%pd\": old parent: %llu, new: %llu\n" , |
239 | dentry, |
240 | (unsigned long long)parent_blkno, |
241 | (unsigned long long)dl->dl_parent_blkno); |
242 | return 0; |
243 | } |
244 | |
245 | alias = ocfs2_find_local_alias(inode, parent_blkno, skip_unhashed: 0); |
246 | if (alias) { |
247 | /* |
248 | * Great, an alias exists, which means we must have a |
249 | * dentry lock already. We can just grab the lock off |
250 | * the alias and add it to the list. |
251 | * |
252 | * We're depending here on the fact that this dentry |
253 | * was found and exists in the dcache and so must have |
254 | * a reference to the dentry_lock because we can't |
255 | * race creates. Final dput() cannot happen on it |
256 | * since we have it pinned, so our reference is safe. |
257 | */ |
258 | dl = alias->d_fsdata; |
259 | mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n" , |
260 | (unsigned long long)parent_blkno, |
261 | (unsigned long long)OCFS2_I(inode)->ip_blkno); |
262 | |
263 | mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, |
264 | " \"%pd\": old parent: %llu, new: %llu\n" , |
265 | dentry, |
266 | (unsigned long long)parent_blkno, |
267 | (unsigned long long)dl->dl_parent_blkno); |
268 | |
269 | trace_ocfs2_dentry_attach_lock_found(name: dl->dl_lockres.l_name, |
270 | parent: (unsigned long long)parent_blkno, |
271 | ino: (unsigned long long)OCFS2_I(inode)->ip_blkno); |
272 | |
273 | goto out_attach; |
274 | } |
275 | |
276 | /* |
277 | * There are no other aliases |
278 | */ |
279 | dl = kmalloc(size: sizeof(*dl), GFP_NOFS); |
280 | if (!dl) { |
281 | ret = -ENOMEM; |
282 | mlog_errno(ret); |
283 | return ret; |
284 | } |
285 | |
286 | dl->dl_count = 0; |
287 | /* |
288 | * Does this have to happen below, for all attaches, in case |
289 | * the struct inode gets blown away by the downconvert thread? |
290 | */ |
291 | dl->dl_inode = igrab(inode); |
292 | dl->dl_parent_blkno = parent_blkno; |
293 | ocfs2_dentry_lock_res_init(dl, parent: parent_blkno, inode); |
294 | |
295 | out_attach: |
296 | spin_lock(lock: &dentry_attach_lock); |
297 | if (unlikely(dentry->d_fsdata && !alias)) { |
298 | /* d_fsdata is set by a racing thread which is doing |
299 | * the same thing as this thread is doing. Leave the racing |
300 | * thread going ahead and we return here. |
301 | */ |
302 | spin_unlock(lock: &dentry_attach_lock); |
303 | iput(dl->dl_inode); |
304 | ocfs2_lock_res_free(res: &dl->dl_lockres); |
305 | kfree(objp: dl); |
306 | return 0; |
307 | } |
308 | |
309 | dentry->d_fsdata = dl; |
310 | dl->dl_count++; |
311 | spin_unlock(lock: &dentry_attach_lock); |
312 | |
313 | /* |
314 | * This actually gets us our PRMODE level lock. From now on, |
315 | * we'll have a notification if one of these names is |
316 | * destroyed on another node. |
317 | */ |
318 | ret = ocfs2_dentry_lock(dentry, ex: 0); |
319 | if (!ret) |
320 | ocfs2_dentry_unlock(dentry, ex: 0); |
321 | else |
322 | mlog_errno(ret); |
323 | |
324 | /* |
325 | * In case of error, manually free the allocation and do the iput(). |
326 | * We need to do this because error here means no d_instantiate(), |
327 | * which means iput() will not be called during dput(dentry). |
328 | */ |
329 | if (ret < 0 && !alias) { |
330 | ocfs2_lock_res_free(res: &dl->dl_lockres); |
331 | BUG_ON(dl->dl_count != 1); |
332 | spin_lock(lock: &dentry_attach_lock); |
333 | dentry->d_fsdata = NULL; |
334 | spin_unlock(lock: &dentry_attach_lock); |
335 | kfree(objp: dl); |
336 | iput(inode); |
337 | } |
338 | |
339 | dput(alias); |
340 | |
341 | return ret; |
342 | } |
343 | |
344 | /* |
345 | * ocfs2_dentry_iput() and friends. |
346 | * |
347 | * At this point, our particular dentry is detached from the inodes |
348 | * alias list, so there's no way that the locking code can find it. |
349 | * |
350 | * The interesting stuff happens when we determine that our lock needs |
351 | * to go away because this is the last subdir alias in the |
352 | * system. This function needs to handle a couple things: |
353 | * |
354 | * 1) Synchronizing lock shutdown with the downconvert threads. This |
355 | * is already handled for us via the lockres release drop function |
356 | * called in ocfs2_release_dentry_lock() |
357 | * |
358 | * 2) A race may occur when we're doing our lock shutdown and |
359 | * another process wants to create a new dentry lock. Right now we |
360 | * let them race, which means that for a very short while, this |
361 | * node might have two locks on a lock resource. This should be a |
362 | * problem though because one of them is in the process of being |
363 | * thrown out. |
364 | */ |
365 | static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb, |
366 | struct ocfs2_dentry_lock *dl) |
367 | { |
368 | iput(dl->dl_inode); |
369 | ocfs2_simple_drop_lockres(osb, lockres: &dl->dl_lockres); |
370 | ocfs2_lock_res_free(res: &dl->dl_lockres); |
371 | kfree(objp: dl); |
372 | } |
373 | |
374 | void ocfs2_dentry_lock_put(struct ocfs2_super *osb, |
375 | struct ocfs2_dentry_lock *dl) |
376 | { |
377 | int unlock = 0; |
378 | |
379 | BUG_ON(dl->dl_count == 0); |
380 | |
381 | spin_lock(lock: &dentry_attach_lock); |
382 | dl->dl_count--; |
383 | unlock = !dl->dl_count; |
384 | spin_unlock(lock: &dentry_attach_lock); |
385 | |
386 | if (unlock) |
387 | ocfs2_drop_dentry_lock(osb, dl); |
388 | } |
389 | |
390 | static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode) |
391 | { |
392 | struct ocfs2_dentry_lock *dl = dentry->d_fsdata; |
393 | |
394 | if (!dl) { |
395 | /* |
396 | * No dentry lock is ok if we're disconnected or |
397 | * unhashed. |
398 | */ |
399 | if (!(dentry->d_flags & DCACHE_DISCONNECTED) && |
400 | !d_unhashed(dentry)) { |
401 | unsigned long long ino = 0ULL; |
402 | if (inode) |
403 | ino = (unsigned long long)OCFS2_I(inode)->ip_blkno; |
404 | mlog(ML_ERROR, "Dentry is missing cluster lock. " |
405 | "inode: %llu, d_flags: 0x%x, d_name: %pd\n" , |
406 | ino, dentry->d_flags, dentry); |
407 | } |
408 | |
409 | goto out; |
410 | } |
411 | |
412 | mlog_bug_on_msg(dl->dl_count == 0, "dentry: %pd, count: %u\n" , |
413 | dentry, dl->dl_count); |
414 | |
415 | ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl); |
416 | |
417 | out: |
418 | iput(inode); |
419 | } |
420 | |
421 | /* |
422 | * d_move(), but keep the locks in sync. |
423 | * |
424 | * When we are done, "dentry" will have the parent dir and name of |
425 | * "target", which will be thrown away. |
426 | * |
427 | * We manually update the lock of "dentry" if need be. |
428 | * |
429 | * "target" doesn't have it's dentry lock touched - we allow the later |
430 | * dput() to handle this for us. |
431 | * |
432 | * This is called during ocfs2_rename(), while holding parent |
433 | * directory locks. The dentries have already been deleted on other |
434 | * nodes via ocfs2_remote_dentry_delete(). |
435 | * |
436 | * Normally, the VFS handles the d_move() for the file system, after |
437 | * the ->rename() callback. OCFS2 wants to handle this internally, so |
438 | * the new lock can be created atomically with respect to the cluster. |
439 | */ |
440 | void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target, |
441 | struct inode *old_dir, struct inode *new_dir) |
442 | { |
443 | int ret; |
444 | struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb); |
445 | struct inode *inode = d_inode(dentry); |
446 | |
447 | /* |
448 | * Move within the same directory, so the actual lock info won't |
449 | * change. |
450 | * |
451 | * XXX: Is there any advantage to dropping the lock here? |
452 | */ |
453 | if (old_dir == new_dir) |
454 | goto out_move; |
455 | |
456 | ocfs2_dentry_lock_put(osb, dl: dentry->d_fsdata); |
457 | |
458 | dentry->d_fsdata = NULL; |
459 | ret = ocfs2_dentry_attach_lock(dentry, inode, parent_blkno: OCFS2_I(inode: new_dir)->ip_blkno); |
460 | if (ret) |
461 | mlog_errno(ret); |
462 | |
463 | out_move: |
464 | d_move(dentry, target); |
465 | } |
466 | |
467 | const struct dentry_operations ocfs2_dentry_ops = { |
468 | .d_revalidate = ocfs2_dentry_revalidate, |
469 | .d_iput = ocfs2_dentry_iput, |
470 | }; |
471 | |