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ccd979bd MF |
1 | /* -*- mode: c; c-basic-offset: 8; -*- |
2 | * vim: noexpandtab sw=8 ts=8 sts=0: | |
3 | * | |
4 | * dcache.c | |
5 | * | |
6 | * dentry cache handling code | |
7 | * | |
8 | * Copyright (C) 2002, 2004 Oracle. All rights reserved. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public | |
12 | * License as published by the Free Software Foundation; either | |
13 | * version 2 of the License, or (at your option) any later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, | |
16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public | |
21 | * License along with this program; if not, write to the | |
22 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | * Boston, MA 021110-1307, USA. | |
24 | */ | |
25 | ||
26 | #include <linux/fs.h> | |
27 | #include <linux/types.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/namei.h> | |
30 | ||
31 | #define MLOG_MASK_PREFIX ML_DCACHE | |
32 | #include <cluster/masklog.h> | |
33 | ||
34 | #include "ocfs2.h" | |
35 | ||
36 | #include "alloc.h" | |
37 | #include "dcache.h" | |
80c05846 | 38 | #include "dlmglue.h" |
ccd979bd MF |
39 | #include "file.h" |
40 | #include "inode.h" | |
ea455f8a | 41 | #include "super.h" |
ccd979bd | 42 | |
80c05846 | 43 | |
ccd979bd MF |
44 | static int ocfs2_dentry_revalidate(struct dentry *dentry, |
45 | struct nameidata *nd) | |
46 | { | |
47 | struct inode *inode = dentry->d_inode; | |
48 | int ret = 0; /* if all else fails, just return false */ | |
80c05846 | 49 | struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb); |
ccd979bd MF |
50 | |
51 | mlog_entry("(0x%p, '%.*s')\n", dentry, | |
52 | dentry->d_name.len, dentry->d_name.name); | |
53 | ||
54 | /* Never trust a negative dentry - force a new lookup. */ | |
55 | if (inode == NULL) { | |
56 | mlog(0, "negative dentry: %.*s\n", dentry->d_name.len, | |
57 | dentry->d_name.name); | |
58 | goto bail; | |
59 | } | |
60 | ||
ccd979bd MF |
61 | BUG_ON(!osb); |
62 | ||
80c05846 MF |
63 | if (inode == osb->root_inode || is_bad_inode(inode)) |
64 | goto bail; | |
65 | ||
66 | spin_lock(&OCFS2_I(inode)->ip_lock); | |
67 | /* did we or someone else delete this inode? */ | |
68 | if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) { | |
ccd979bd | 69 | spin_unlock(&OCFS2_I(inode)->ip_lock); |
80c05846 MF |
70 | mlog(0, "inode (%llu) deleted, returning false\n", |
71 | (unsigned long long)OCFS2_I(inode)->ip_blkno); | |
72 | goto bail; | |
73 | } | |
74 | spin_unlock(&OCFS2_I(inode)->ip_lock); | |
ccd979bd | 75 | |
80c05846 MF |
76 | /* |
77 | * We don't need a cluster lock to test this because once an | |
78 | * inode nlink hits zero, it never goes back. | |
79 | */ | |
80 | if (inode->i_nlink == 0) { | |
81 | mlog(0, "Inode %llu orphaned, returning false " | |
82 | "dir = %d\n", | |
83 | (unsigned long long)OCFS2_I(inode)->ip_blkno, | |
84 | S_ISDIR(inode->i_mode)); | |
85 | goto bail; | |
ccd979bd MF |
86 | } |
87 | ||
88 | ret = 1; | |
89 | ||
90 | bail: | |
91 | mlog_exit(ret); | |
92 | ||
93 | return ret; | |
94 | } | |
95 | ||
80c05846 MF |
96 | static int ocfs2_match_dentry(struct dentry *dentry, |
97 | u64 parent_blkno, | |
98 | int skip_unhashed) | |
99 | { | |
100 | struct inode *parent; | |
101 | ||
102 | /* | |
103 | * ocfs2_lookup() does a d_splice_alias() _before_ attaching | |
104 | * to the lock data, so we skip those here, otherwise | |
105 | * ocfs2_dentry_attach_lock() will get its original dentry | |
106 | * back. | |
107 | */ | |
108 | if (!dentry->d_fsdata) | |
109 | return 0; | |
110 | ||
111 | if (!dentry->d_parent) | |
112 | return 0; | |
113 | ||
114 | if (skip_unhashed && d_unhashed(dentry)) | |
115 | return 0; | |
116 | ||
117 | parent = dentry->d_parent->d_inode; | |
118 | /* Negative parent dentry? */ | |
119 | if (!parent) | |
120 | return 0; | |
121 | ||
122 | /* Name is in a different directory. */ | |
123 | if (OCFS2_I(parent)->ip_blkno != parent_blkno) | |
124 | return 0; | |
125 | ||
126 | return 1; | |
127 | } | |
128 | ||
129 | /* | |
130 | * Walk the inode alias list, and find a dentry which has a given | |
131 | * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it | |
34d024f8 MF |
132 | * is looking for a dentry_lock reference. The downconvert thread is |
133 | * looking to unhash aliases, so we allow it to skip any that already | |
134 | * have that property. | |
80c05846 MF |
135 | */ |
136 | struct dentry *ocfs2_find_local_alias(struct inode *inode, | |
137 | u64 parent_blkno, | |
138 | int skip_unhashed) | |
139 | { | |
140 | struct list_head *p; | |
141 | struct dentry *dentry = NULL; | |
142 | ||
143 | spin_lock(&dcache_lock); | |
144 | ||
145 | list_for_each(p, &inode->i_dentry) { | |
146 | dentry = list_entry(p, struct dentry, d_alias); | |
147 | ||
148 | if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) { | |
149 | mlog(0, "dentry found: %.*s\n", | |
150 | dentry->d_name.len, dentry->d_name.name); | |
151 | ||
152 | dget_locked(dentry); | |
153 | break; | |
154 | } | |
155 | ||
156 | dentry = NULL; | |
157 | } | |
158 | ||
159 | spin_unlock(&dcache_lock); | |
160 | ||
161 | return dentry; | |
162 | } | |
163 | ||
d680efe9 MF |
164 | DEFINE_SPINLOCK(dentry_attach_lock); |
165 | ||
80c05846 MF |
166 | /* |
167 | * Attach this dentry to a cluster lock. | |
168 | * | |
169 | * Dentry locks cover all links in a given directory to a particular | |
170 | * inode. We do this so that ocfs2 can build a lock name which all | |
171 | * nodes in the cluster can agree on at all times. Shoving full names | |
172 | * in the cluster lock won't work due to size restrictions. Covering | |
173 | * links inside of a directory is a good compromise because it still | |
174 | * allows us to use the parent directory lock to synchronize | |
175 | * operations. | |
176 | * | |
177 | * Call this function with the parent dir semaphore and the parent dir | |
178 | * cluster lock held. | |
179 | * | |
180 | * The dir semaphore will protect us from having to worry about | |
181 | * concurrent processes on our node trying to attach a lock at the | |
182 | * same time. | |
183 | * | |
184 | * The dir cluster lock (held at either PR or EX mode) protects us | |
185 | * from unlink and rename on other nodes. | |
186 | * | |
80c05846 MF |
187 | * A dput() can happen asynchronously due to pruning, so we cover |
188 | * attaching and detaching the dentry lock with a | |
189 | * dentry_attach_lock. | |
190 | * | |
191 | * A node which has done lookup on a name retains a protected read | |
192 | * lock until final dput. If the user requests and unlink or rename, | |
193 | * the protected read is upgraded to an exclusive lock. Other nodes | |
194 | * who have seen the dentry will then be informed that they need to | |
195 | * downgrade their lock, which will involve d_delete on the | |
196 | * dentry. This happens in ocfs2_dentry_convert_worker(). | |
197 | */ | |
198 | int ocfs2_dentry_attach_lock(struct dentry *dentry, | |
199 | struct inode *inode, | |
0027dd5b | 200 | u64 parent_blkno) |
80c05846 MF |
201 | { |
202 | int ret; | |
203 | struct dentry *alias; | |
204 | struct ocfs2_dentry_lock *dl = dentry->d_fsdata; | |
205 | ||
0027dd5b | 206 | mlog(0, "Attach \"%.*s\", parent %llu, fsdata: %p\n", |
80c05846 | 207 | dentry->d_name.len, dentry->d_name.name, |
0027dd5b | 208 | (unsigned long long)parent_blkno, dl); |
80c05846 MF |
209 | |
210 | /* | |
211 | * Negative dentry. We ignore these for now. | |
212 | * | |
213 | * XXX: Could we can improve ocfs2_dentry_revalidate() by | |
214 | * tracking these? | |
215 | */ | |
216 | if (!inode) | |
217 | return 0; | |
218 | ||
219 | if (dl) { | |
220 | mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, | |
221 | " \"%.*s\": old parent: %llu, new: %llu\n", | |
222 | dentry->d_name.len, dentry->d_name.name, | |
223 | (unsigned long long)parent_blkno, | |
224 | (unsigned long long)dl->dl_parent_blkno); | |
225 | return 0; | |
226 | } | |
227 | ||
228 | alias = ocfs2_find_local_alias(inode, parent_blkno, 0); | |
229 | if (alias) { | |
230 | /* | |
231 | * Great, an alias exists, which means we must have a | |
232 | * dentry lock already. We can just grab the lock off | |
233 | * the alias and add it to the list. | |
234 | * | |
235 | * We're depending here on the fact that this dentry | |
236 | * was found and exists in the dcache and so must have | |
237 | * a reference to the dentry_lock because we can't | |
238 | * race creates. Final dput() cannot happen on it | |
239 | * since we have it pinned, so our reference is safe. | |
240 | */ | |
241 | dl = alias->d_fsdata; | |
0027dd5b | 242 | mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n", |
80c05846 | 243 | (unsigned long long)parent_blkno, |
0027dd5b | 244 | (unsigned long long)OCFS2_I(inode)->ip_blkno); |
80c05846 MF |
245 | |
246 | mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno, | |
247 | " \"%.*s\": old parent: %llu, new: %llu\n", | |
248 | dentry->d_name.len, dentry->d_name.name, | |
249 | (unsigned long long)parent_blkno, | |
250 | (unsigned long long)dl->dl_parent_blkno); | |
251 | ||
252 | mlog(0, "Found: %s\n", dl->dl_lockres.l_name); | |
253 | ||
254 | goto out_attach; | |
255 | } | |
256 | ||
257 | /* | |
258 | * There are no other aliases | |
259 | */ | |
260 | dl = kmalloc(sizeof(*dl), GFP_NOFS); | |
261 | if (!dl) { | |
262 | ret = -ENOMEM; | |
263 | mlog_errno(ret); | |
264 | return ret; | |
265 | } | |
266 | ||
267 | dl->dl_count = 0; | |
268 | /* | |
269 | * Does this have to happen below, for all attaches, in case | |
34d024f8 | 270 | * the struct inode gets blown away by the downconvert thread? |
80c05846 MF |
271 | */ |
272 | dl->dl_inode = igrab(inode); | |
273 | dl->dl_parent_blkno = parent_blkno; | |
274 | ocfs2_dentry_lock_res_init(dl, parent_blkno, inode); | |
275 | ||
276 | out_attach: | |
277 | spin_lock(&dentry_attach_lock); | |
278 | dentry->d_fsdata = dl; | |
279 | dl->dl_count++; | |
280 | spin_unlock(&dentry_attach_lock); | |
281 | ||
80c05846 MF |
282 | /* |
283 | * This actually gets us our PRMODE level lock. From now on, | |
284 | * we'll have a notification if one of these names is | |
285 | * destroyed on another node. | |
286 | */ | |
287 | ret = ocfs2_dentry_lock(dentry, 0); | |
0027dd5b MF |
288 | if (!ret) |
289 | ocfs2_dentry_unlock(dentry, 0); | |
290 | else | |
80c05846 | 291 | mlog_errno(ret); |
80c05846 | 292 | |
80c05846 MF |
293 | dput(alias); |
294 | ||
295 | return ret; | |
296 | } | |
297 | ||
ea455f8a JK |
298 | static DEFINE_SPINLOCK(dentry_list_lock); |
299 | ||
300 | /* We limit the number of dentry locks to drop in one go. We have | |
301 | * this limit so that we don't starve other users of ocfs2_wq. */ | |
302 | #define DL_INODE_DROP_COUNT 64 | |
303 | ||
304 | /* Drop inode references from dentry locks */ | |
305 | void ocfs2_drop_dl_inodes(struct work_struct *work) | |
306 | { | |
307 | struct ocfs2_super *osb = container_of(work, struct ocfs2_super, | |
308 | dentry_lock_work); | |
309 | struct ocfs2_dentry_lock *dl; | |
310 | int drop_count = DL_INODE_DROP_COUNT; | |
311 | ||
312 | spin_lock(&dentry_list_lock); | |
313 | while (osb->dentry_lock_list && drop_count--) { | |
314 | dl = osb->dentry_lock_list; | |
315 | osb->dentry_lock_list = dl->dl_next; | |
316 | spin_unlock(&dentry_list_lock); | |
317 | iput(dl->dl_inode); | |
318 | kfree(dl); | |
319 | spin_lock(&dentry_list_lock); | |
320 | } | |
321 | if (osb->dentry_lock_list) | |
322 | queue_work(ocfs2_wq, &osb->dentry_lock_work); | |
323 | spin_unlock(&dentry_list_lock); | |
324 | } | |
325 | ||
80c05846 MF |
326 | /* |
327 | * ocfs2_dentry_iput() and friends. | |
328 | * | |
329 | * At this point, our particular dentry is detached from the inodes | |
330 | * alias list, so there's no way that the locking code can find it. | |
331 | * | |
332 | * The interesting stuff happens when we determine that our lock needs | |
333 | * to go away because this is the last subdir alias in the | |
334 | * system. This function needs to handle a couple things: | |
335 | * | |
336 | * 1) Synchronizing lock shutdown with the downconvert threads. This | |
337 | * is already handled for us via the lockres release drop function | |
338 | * called in ocfs2_release_dentry_lock() | |
339 | * | |
340 | * 2) A race may occur when we're doing our lock shutdown and | |
341 | * another process wants to create a new dentry lock. Right now we | |
342 | * let them race, which means that for a very short while, this | |
343 | * node might have two locks on a lock resource. This should be a | |
344 | * problem though because one of them is in the process of being | |
345 | * thrown out. | |
346 | */ | |
347 | static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb, | |
348 | struct ocfs2_dentry_lock *dl) | |
349 | { | |
350 | ocfs2_simple_drop_lockres(osb, &dl->dl_lockres); | |
351 | ocfs2_lock_res_free(&dl->dl_lockres); | |
ea455f8a JK |
352 | |
353 | /* We leave dropping of inode reference to ocfs2_wq as that can | |
354 | * possibly lead to inode deletion which gets tricky */ | |
355 | spin_lock(&dentry_list_lock); | |
356 | if (!osb->dentry_lock_list) | |
357 | queue_work(ocfs2_wq, &osb->dentry_lock_work); | |
358 | dl->dl_next = osb->dentry_lock_list; | |
359 | osb->dentry_lock_list = dl; | |
360 | spin_unlock(&dentry_list_lock); | |
80c05846 MF |
361 | } |
362 | ||
363 | void ocfs2_dentry_lock_put(struct ocfs2_super *osb, | |
364 | struct ocfs2_dentry_lock *dl) | |
365 | { | |
ea455f8a | 366 | int unlock; |
80c05846 MF |
367 | |
368 | BUG_ON(dl->dl_count == 0); | |
369 | ||
370 | spin_lock(&dentry_attach_lock); | |
371 | dl->dl_count--; | |
372 | unlock = !dl->dl_count; | |
373 | spin_unlock(&dentry_attach_lock); | |
374 | ||
375 | if (unlock) | |
376 | ocfs2_drop_dentry_lock(osb, dl); | |
377 | } | |
378 | ||
379 | static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode) | |
380 | { | |
381 | struct ocfs2_dentry_lock *dl = dentry->d_fsdata; | |
382 | ||
bccb9dad MF |
383 | if (!dl) { |
384 | /* | |
385 | * No dentry lock is ok if we're disconnected or | |
386 | * unhashed. | |
387 | */ | |
388 | if (!(dentry->d_flags & DCACHE_DISCONNECTED) && | |
389 | !d_unhashed(dentry)) { | |
390 | unsigned long long ino = 0ULL; | |
391 | if (inode) | |
392 | ino = (unsigned long long)OCFS2_I(inode)->ip_blkno; | |
393 | mlog(ML_ERROR, "Dentry is missing cluster lock. " | |
394 | "inode: %llu, d_flags: 0x%x, d_name: %.*s\n", | |
395 | ino, dentry->d_flags, dentry->d_name.len, | |
396 | dentry->d_name.name); | |
397 | } | |
80c05846 | 398 | |
80c05846 | 399 | goto out; |
bccb9dad | 400 | } |
80c05846 MF |
401 | |
402 | mlog_bug_on_msg(dl->dl_count == 0, "dentry: %.*s, count: %u\n", | |
403 | dentry->d_name.len, dentry->d_name.name, | |
404 | dl->dl_count); | |
405 | ||
406 | ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl); | |
407 | ||
408 | out: | |
409 | iput(inode); | |
410 | } | |
411 | ||
412 | /* | |
413 | * d_move(), but keep the locks in sync. | |
414 | * | |
415 | * When we are done, "dentry" will have the parent dir and name of | |
416 | * "target", which will be thrown away. | |
417 | * | |
418 | * We manually update the lock of "dentry" if need be. | |
419 | * | |
420 | * "target" doesn't have it's dentry lock touched - we allow the later | |
421 | * dput() to handle this for us. | |
422 | * | |
423 | * This is called during ocfs2_rename(), while holding parent | |
424 | * directory locks. The dentries have already been deleted on other | |
425 | * nodes via ocfs2_remote_dentry_delete(). | |
426 | * | |
3a4fa0a2 | 427 | * Normally, the VFS handles the d_move() for the file system, after |
80c05846 MF |
428 | * the ->rename() callback. OCFS2 wants to handle this internally, so |
429 | * the new lock can be created atomically with respect to the cluster. | |
430 | */ | |
431 | void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target, | |
432 | struct inode *old_dir, struct inode *new_dir) | |
433 | { | |
434 | int ret; | |
435 | struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb); | |
436 | struct inode *inode = dentry->d_inode; | |
437 | ||
438 | /* | |
439 | * Move within the same directory, so the actual lock info won't | |
440 | * change. | |
441 | * | |
442 | * XXX: Is there any advantage to dropping the lock here? | |
443 | */ | |
444 | if (old_dir == new_dir) | |
1ba9da2f | 445 | goto out_move; |
80c05846 MF |
446 | |
447 | ocfs2_dentry_lock_put(osb, dentry->d_fsdata); | |
448 | ||
449 | dentry->d_fsdata = NULL; | |
0027dd5b | 450 | ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno); |
80c05846 MF |
451 | if (ret) |
452 | mlog_errno(ret); | |
1ba9da2f MF |
453 | |
454 | out_move: | |
455 | d_move(dentry, target); | |
80c05846 MF |
456 | } |
457 | ||
d8fba0ff | 458 | const struct dentry_operations ocfs2_dentry_ops = { |
ccd979bd | 459 | .d_revalidate = ocfs2_dentry_revalidate, |
80c05846 | 460 | .d_iput = ocfs2_dentry_iput, |
ccd979bd | 461 | }; |