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 (skip_unhashed && d_unhashed(dentry)) |
128 | return 0; |
129 | |
130 | parent = d_inode(dentry: dentry->d_parent); |
131 | /* Name is in a different directory. */ |
132 | if (OCFS2_I(inode: 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(lock: &inode->i_lock); |
152 | hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
153 | spin_lock(lock: &dentry->d_lock); |
154 | if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) { |
155 | trace_ocfs2_find_local_alias(len: dentry->d_name.len, |
156 | name: dentry->d_name.name); |
157 | |
158 | dget_dlock(dentry); |
159 | spin_unlock(lock: &dentry->d_lock); |
160 | spin_unlock(lock: &inode->i_lock); |
161 | return dentry; |
162 | } |
163 | spin_unlock(lock: &dentry->d_lock); |
164 | } |
165 | spin_unlock(lock: &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(len: dentry->d_name.len, name: dentry->d_name.name, |
212 | parent: (unsigned long long)parent_blkno, fsdata: 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, skip_unhashed: 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(name: dl->dl_lockres.l_name, |
263 | parent: (unsigned long long)parent_blkno, |
264 | ino: (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(size: 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: parent_blkno, inode); |
287 | |
288 | out_attach: |
289 | spin_lock(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(lock: &dentry_attach_lock); |
296 | iput(dl->dl_inode); |
297 | ocfs2_lock_res_free(res: &dl->dl_lockres); |
298 | kfree(objp: dl); |
299 | return 0; |
300 | } |
301 | |
302 | dentry->d_fsdata = dl; |
303 | dl->dl_count++; |
304 | spin_unlock(lock: &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, ex: 0); |
312 | if (!ret) |
313 | ocfs2_dentry_unlock(dentry, ex: 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(res: &dl->dl_lockres); |
324 | BUG_ON(dl->dl_count != 1); |
325 | spin_lock(lock: &dentry_attach_lock); |
326 | dentry->d_fsdata = NULL; |
327 | spin_unlock(lock: &dentry_attach_lock); |
328 | kfree(objp: 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, lockres: &dl->dl_lockres); |
363 | ocfs2_lock_res_free(res: &dl->dl_lockres); |
364 | kfree(objp: 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(lock: &dentry_attach_lock); |
375 | dl->dl_count--; |
376 | unlock = !dl->dl_count; |
377 | spin_unlock(lock: &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, dl: dentry->d_fsdata); |
450 | |
451 | dentry->d_fsdata = NULL; |
452 | ret = ocfs2_dentry_attach_lock(dentry, inode, parent_blkno: OCFS2_I(inode: 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 | |