1 /* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
6 * dentry cache handling code
8 * Copyright (C) 2002, 2004 Oracle. All rights reserved.
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.
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.
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.
27 #include <linux/types.h>
28 #include <linux/slab.h>
29 #include <linux/namei.h>
31 #define MLOG_MASK_PREFIX ML_DCACHE
32 #include <cluster/masklog.h>
43 void ocfs2_dentry_attach_gen(struct dentry *dentry)
46 OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen;
47 BUG_ON(dentry->d_inode);
48 dentry->d_fsdata = (void *)gen;
52 static int ocfs2_dentry_revalidate(struct dentry *dentry,
56 int ret = 0; /* if all else fails, just return false */
57 struct ocfs2_super *osb;
59 if (nd && nd->flags & LOOKUP_RCU)
62 inode = dentry->d_inode;
63 osb = OCFS2_SB(dentry->d_sb);
65 mlog(0, "(0x%p, '%.*s')\n", dentry,
66 dentry->d_name.len, dentry->d_name.name);
68 /* For a negative dentry -
69 * check the generation number of the parent and compare with the
70 * one stored in the inode.
73 unsigned long gen = (unsigned long) dentry->d_fsdata;
75 OCFS2_I(dentry->d_parent->d_inode)->ip_dir_lock_gen;
76 mlog(0, "negative dentry: %.*s parent gen: %lu "
78 dentry->d_name.len, dentry->d_name.name, pgen, gen);
86 if (inode == osb->root_inode || is_bad_inode(inode))
89 spin_lock(&OCFS2_I(inode)->ip_lock);
90 /* did we or someone else delete this inode? */
91 if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED) {
92 spin_unlock(&OCFS2_I(inode)->ip_lock);
93 mlog(0, "inode (%llu) deleted, returning false\n",
94 (unsigned long long)OCFS2_I(inode)->ip_blkno);
97 spin_unlock(&OCFS2_I(inode)->ip_lock);
100 * We don't need a cluster lock to test this because once an
101 * inode nlink hits zero, it never goes back.
103 if (inode->i_nlink == 0) {
104 mlog(0, "Inode %llu orphaned, returning false "
106 (unsigned long long)OCFS2_I(inode)->ip_blkno,
107 S_ISDIR(inode->i_mode));
112 * If the last lookup failed to create dentry lock, let us
115 if (!dentry->d_fsdata) {
116 mlog(0, "Inode %llu doesn't have dentry lock, "
118 (unsigned long long)OCFS2_I(inode)->ip_blkno);
126 mlog(0, "ret = %d\n", ret);
130 static int ocfs2_match_dentry(struct dentry *dentry,
134 struct inode *parent;
137 * ocfs2_lookup() does a d_splice_alias() _before_ attaching
138 * to the lock data, so we skip those here, otherwise
139 * ocfs2_dentry_attach_lock() will get its original dentry
142 if (!dentry->d_fsdata)
145 if (!dentry->d_parent)
148 if (skip_unhashed && d_unhashed(dentry))
151 parent = dentry->d_parent->d_inode;
152 /* Negative parent dentry? */
156 /* Name is in a different directory. */
157 if (OCFS2_I(parent)->ip_blkno != parent_blkno)
164 * Walk the inode alias list, and find a dentry which has a given
165 * parent. ocfs2_dentry_attach_lock() wants to find _any_ alias as it
166 * is looking for a dentry_lock reference. The downconvert thread is
167 * looking to unhash aliases, so we allow it to skip any that already
168 * have that property.
170 struct dentry *ocfs2_find_local_alias(struct inode *inode,
175 struct dentry *dentry = NULL;
177 spin_lock(&inode->i_lock);
178 list_for_each(p, &inode->i_dentry) {
179 dentry = list_entry(p, struct dentry, d_alias);
181 spin_lock(&dentry->d_lock);
182 if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
183 mlog(0, "dentry found: %.*s\n",
184 dentry->d_name.len, dentry->d_name.name);
187 spin_unlock(&dentry->d_lock);
190 spin_unlock(&dentry->d_lock);
195 spin_unlock(&inode->i_lock);
200 DEFINE_SPINLOCK(dentry_attach_lock);
203 * Attach this dentry to a cluster lock.
205 * Dentry locks cover all links in a given directory to a particular
206 * inode. We do this so that ocfs2 can build a lock name which all
207 * nodes in the cluster can agree on at all times. Shoving full names
208 * in the cluster lock won't work due to size restrictions. Covering
209 * links inside of a directory is a good compromise because it still
210 * allows us to use the parent directory lock to synchronize
213 * Call this function with the parent dir semaphore and the parent dir
216 * The dir semaphore will protect us from having to worry about
217 * concurrent processes on our node trying to attach a lock at the
220 * The dir cluster lock (held at either PR or EX mode) protects us
221 * from unlink and rename on other nodes.
223 * A dput() can happen asynchronously due to pruning, so we cover
224 * attaching and detaching the dentry lock with a
225 * dentry_attach_lock.
227 * A node which has done lookup on a name retains a protected read
228 * lock until final dput. If the user requests and unlink or rename,
229 * the protected read is upgraded to an exclusive lock. Other nodes
230 * who have seen the dentry will then be informed that they need to
231 * downgrade their lock, which will involve d_delete on the
232 * dentry. This happens in ocfs2_dentry_convert_worker().
234 int ocfs2_dentry_attach_lock(struct dentry *dentry,
239 struct dentry *alias;
240 struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
242 mlog(0, "Attach \"%.*s\", parent %llu, fsdata: %p\n",
243 dentry->d_name.len, dentry->d_name.name,
244 (unsigned long long)parent_blkno, dl);
247 * Negative dentry. We ignore these for now.
249 * XXX: Could we can improve ocfs2_dentry_revalidate() by
255 if (!dentry->d_inode && dentry->d_fsdata) {
256 /* Converting a negative dentry to positive
257 Clear dentry->d_fsdata */
258 dentry->d_fsdata = dl = NULL;
262 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
263 " \"%.*s\": old parent: %llu, new: %llu\n",
264 dentry->d_name.len, dentry->d_name.name,
265 (unsigned long long)parent_blkno,
266 (unsigned long long)dl->dl_parent_blkno);
270 alias = ocfs2_find_local_alias(inode, parent_blkno, 0);
273 * Great, an alias exists, which means we must have a
274 * dentry lock already. We can just grab the lock off
275 * the alias and add it to the list.
277 * We're depending here on the fact that this dentry
278 * was found and exists in the dcache and so must have
279 * a reference to the dentry_lock because we can't
280 * race creates. Final dput() cannot happen on it
281 * since we have it pinned, so our reference is safe.
283 dl = alias->d_fsdata;
284 mlog_bug_on_msg(!dl, "parent %llu, ino %llu\n",
285 (unsigned long long)parent_blkno,
286 (unsigned long long)OCFS2_I(inode)->ip_blkno);
288 mlog_bug_on_msg(dl->dl_parent_blkno != parent_blkno,
289 " \"%.*s\": old parent: %llu, new: %llu\n",
290 dentry->d_name.len, dentry->d_name.name,
291 (unsigned long long)parent_blkno,
292 (unsigned long long)dl->dl_parent_blkno);
294 mlog(0, "Found: %s\n", dl->dl_lockres.l_name);
300 * There are no other aliases
302 dl = kmalloc(sizeof(*dl), GFP_NOFS);
311 * Does this have to happen below, for all attaches, in case
312 * the struct inode gets blown away by the downconvert thread?
314 dl->dl_inode = igrab(inode);
315 dl->dl_parent_blkno = parent_blkno;
316 ocfs2_dentry_lock_res_init(dl, parent_blkno, inode);
319 spin_lock(&dentry_attach_lock);
320 dentry->d_fsdata = dl;
322 spin_unlock(&dentry_attach_lock);
325 * This actually gets us our PRMODE level lock. From now on,
326 * we'll have a notification if one of these names is
327 * destroyed on another node.
329 ret = ocfs2_dentry_lock(dentry, 0);
331 ocfs2_dentry_unlock(dentry, 0);
336 * In case of error, manually free the allocation and do the iput().
337 * We need to do this because error here means no d_instantiate(),
338 * which means iput() will not be called during dput(dentry).
340 if (ret < 0 && !alias) {
341 ocfs2_lock_res_free(&dl->dl_lockres);
342 BUG_ON(dl->dl_count != 1);
343 spin_lock(&dentry_attach_lock);
344 dentry->d_fsdata = NULL;
345 spin_unlock(&dentry_attach_lock);
355 DEFINE_SPINLOCK(dentry_list_lock);
357 /* We limit the number of dentry locks to drop in one go. We have
358 * this limit so that we don't starve other users of ocfs2_wq. */
359 #define DL_INODE_DROP_COUNT 64
361 /* Drop inode references from dentry locks */
362 static void __ocfs2_drop_dl_inodes(struct ocfs2_super *osb, int drop_count)
364 struct ocfs2_dentry_lock *dl;
366 spin_lock(&dentry_list_lock);
367 while (osb->dentry_lock_list && (drop_count < 0 || drop_count--)) {
368 dl = osb->dentry_lock_list;
369 osb->dentry_lock_list = dl->dl_next;
370 spin_unlock(&dentry_list_lock);
373 spin_lock(&dentry_list_lock);
375 spin_unlock(&dentry_list_lock);
378 void ocfs2_drop_dl_inodes(struct work_struct *work)
380 struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
383 __ocfs2_drop_dl_inodes(osb, DL_INODE_DROP_COUNT);
385 * Don't queue dropping if umount is in progress. We flush the
386 * list in ocfs2_dismount_volume
388 spin_lock(&dentry_list_lock);
389 if (osb->dentry_lock_list &&
390 !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
391 queue_work(ocfs2_wq, &osb->dentry_lock_work);
392 spin_unlock(&dentry_list_lock);
395 /* Flush the whole work queue */
396 void ocfs2_drop_all_dl_inodes(struct ocfs2_super *osb)
398 __ocfs2_drop_dl_inodes(osb, -1);
402 * ocfs2_dentry_iput() and friends.
404 * At this point, our particular dentry is detached from the inodes
405 * alias list, so there's no way that the locking code can find it.
407 * The interesting stuff happens when we determine that our lock needs
408 * to go away because this is the last subdir alias in the
409 * system. This function needs to handle a couple things:
411 * 1) Synchronizing lock shutdown with the downconvert threads. This
412 * is already handled for us via the lockres release drop function
413 * called in ocfs2_release_dentry_lock()
415 * 2) A race may occur when we're doing our lock shutdown and
416 * another process wants to create a new dentry lock. Right now we
417 * let them race, which means that for a very short while, this
418 * node might have two locks on a lock resource. This should be a
419 * problem though because one of them is in the process of being
422 static void ocfs2_drop_dentry_lock(struct ocfs2_super *osb,
423 struct ocfs2_dentry_lock *dl)
425 ocfs2_simple_drop_lockres(osb, &dl->dl_lockres);
426 ocfs2_lock_res_free(&dl->dl_lockres);
428 /* We leave dropping of inode reference to ocfs2_wq as that can
429 * possibly lead to inode deletion which gets tricky */
430 spin_lock(&dentry_list_lock);
431 if (!osb->dentry_lock_list &&
432 !ocfs2_test_osb_flag(osb, OCFS2_OSB_DROP_DENTRY_LOCK_IMMED))
433 queue_work(ocfs2_wq, &osb->dentry_lock_work);
434 dl->dl_next = osb->dentry_lock_list;
435 osb->dentry_lock_list = dl;
436 spin_unlock(&dentry_list_lock);
439 void ocfs2_dentry_lock_put(struct ocfs2_super *osb,
440 struct ocfs2_dentry_lock *dl)
444 BUG_ON(dl->dl_count == 0);
446 spin_lock(&dentry_attach_lock);
448 unlock = !dl->dl_count;
449 spin_unlock(&dentry_attach_lock);
452 ocfs2_drop_dentry_lock(osb, dl);
455 static void ocfs2_dentry_iput(struct dentry *dentry, struct inode *inode)
457 struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
461 * No dentry lock is ok if we're disconnected or
464 if (!(dentry->d_flags & DCACHE_DISCONNECTED) &&
465 !d_unhashed(dentry)) {
466 unsigned long long ino = 0ULL;
468 ino = (unsigned long long)OCFS2_I(inode)->ip_blkno;
469 mlog(ML_ERROR, "Dentry is missing cluster lock. "
470 "inode: %llu, d_flags: 0x%x, d_name: %.*s\n",
471 ino, dentry->d_flags, dentry->d_name.len,
472 dentry->d_name.name);
478 mlog_bug_on_msg(dl->dl_count == 0, "dentry: %.*s, count: %u\n",
479 dentry->d_name.len, dentry->d_name.name,
482 ocfs2_dentry_lock_put(OCFS2_SB(dentry->d_sb), dl);
489 * d_move(), but keep the locks in sync.
491 * When we are done, "dentry" will have the parent dir and name of
492 * "target", which will be thrown away.
494 * We manually update the lock of "dentry" if need be.
496 * "target" doesn't have it's dentry lock touched - we allow the later
497 * dput() to handle this for us.
499 * This is called during ocfs2_rename(), while holding parent
500 * directory locks. The dentries have already been deleted on other
501 * nodes via ocfs2_remote_dentry_delete().
503 * Normally, the VFS handles the d_move() for the file system, after
504 * the ->rename() callback. OCFS2 wants to handle this internally, so
505 * the new lock can be created atomically with respect to the cluster.
507 void ocfs2_dentry_move(struct dentry *dentry, struct dentry *target,
508 struct inode *old_dir, struct inode *new_dir)
511 struct ocfs2_super *osb = OCFS2_SB(old_dir->i_sb);
512 struct inode *inode = dentry->d_inode;
515 * Move within the same directory, so the actual lock info won't
518 * XXX: Is there any advantage to dropping the lock here?
520 if (old_dir == new_dir)
523 ocfs2_dentry_lock_put(osb, dentry->d_fsdata);
525 dentry->d_fsdata = NULL;
526 ret = ocfs2_dentry_attach_lock(dentry, inode, OCFS2_I(new_dir)->ip_blkno);
531 d_move(dentry, target);
534 const struct dentry_operations ocfs2_dentry_ops = {
535 .d_revalidate = ocfs2_dentry_revalidate,
536 .d_iput = ocfs2_dentry_iput,