4 * Complete reimplementation
5 * (C) 1997 Thomas Schoebel-Theuer,
6 * with heavy changes by Linus Torvalds
10 * Notes on the allocation strategy:
12 * The dcache is a master of the icache - whenever a dcache entry
13 * exists, the inode will always exist. "iput()" is done either when
14 * the dcache entry is deleted or garbage collected.
17 #include <linux/syscalls.h>
18 #include <linux/string.h>
21 #include <linux/fsnotify.h>
22 #include <linux/slab.h>
23 #include <linux/init.h>
24 #include <linux/hash.h>
25 #include <linux/cache.h>
26 #include <linux/module.h>
27 #include <linux/mount.h>
28 #include <linux/file.h>
29 #include <asm/uaccess.h>
30 #include <linux/security.h>
31 #include <linux/seqlock.h>
32 #include <linux/swap.h>
33 #include <linux/bootmem.h>
34 #include <linux/fs_struct.h>
35 #include <linux/hardirq.h>
40 * dcache_hash_lock protects:
41 * - the dcache hash table, s_anon lists
42 * dcache_lru_lock protects:
43 * - the dcache lru lists and counters
55 * if (dentry1 < dentry2)
59 int sysctl_vfs_cache_pressure __read_mostly
= 100;
60 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure
);
62 static __cacheline_aligned_in_smp
DEFINE_SPINLOCK(dcache_hash_lock
);
63 static __cacheline_aligned_in_smp
DEFINE_SPINLOCK(dcache_lru_lock
);
64 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(dcache_lock
);
65 __cacheline_aligned_in_smp
DEFINE_SEQLOCK(rename_lock
);
67 EXPORT_SYMBOL(dcache_lock
);
69 static struct kmem_cache
*dentry_cache __read_mostly
;
71 #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname))
74 * This is the single most critical data structure when it comes
75 * to the dcache: the hashtable for lookups. Somebody should try
76 * to make this good - I've just made it work.
78 * This hash-function tries to avoid losing too many bits of hash
79 * information, yet avoid using a prime hash-size or similar.
81 #define D_HASHBITS d_hash_shift
82 #define D_HASHMASK d_hash_mask
84 static unsigned int d_hash_mask __read_mostly
;
85 static unsigned int d_hash_shift __read_mostly
;
86 static struct hlist_head
*dentry_hashtable __read_mostly
;
88 /* Statistics gathering. */
89 struct dentry_stat_t dentry_stat
= {
93 static DEFINE_PER_CPU(unsigned int, nr_dentry
);
95 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
96 static int get_nr_dentry(void)
100 for_each_possible_cpu(i
)
101 sum
+= per_cpu(nr_dentry
, i
);
102 return sum
< 0 ? 0 : sum
;
105 int proc_nr_dentry(ctl_table
*table
, int write
, void __user
*buffer
,
106 size_t *lenp
, loff_t
*ppos
)
108 dentry_stat
.nr_dentry
= get_nr_dentry();
109 return proc_dointvec(table
, write
, buffer
, lenp
, ppos
);
113 static void __d_free(struct rcu_head
*head
)
115 struct dentry
*dentry
= container_of(head
, struct dentry
, d_u
.d_rcu
);
117 WARN_ON(!list_empty(&dentry
->d_alias
));
118 if (dname_external(dentry
))
119 kfree(dentry
->d_name
.name
);
120 kmem_cache_free(dentry_cache
, dentry
);
124 * no dcache_lock, please.
126 static void d_free(struct dentry
*dentry
)
128 this_cpu_dec(nr_dentry
);
129 if (dentry
->d_op
&& dentry
->d_op
->d_release
)
130 dentry
->d_op
->d_release(dentry
);
132 /* if dentry was never inserted into hash, immediate free is OK */
133 if (hlist_unhashed(&dentry
->d_hash
))
134 __d_free(&dentry
->d_u
.d_rcu
);
136 call_rcu(&dentry
->d_u
.d_rcu
, __d_free
);
140 * Release the dentry's inode, using the filesystem
141 * d_iput() operation if defined.
143 static void dentry_iput(struct dentry
* dentry
)
144 __releases(dentry
->d_lock
)
145 __releases(dcache_lock
)
147 struct inode
*inode
= dentry
->d_inode
;
149 dentry
->d_inode
= NULL
;
150 list_del_init(&dentry
->d_alias
);
151 spin_unlock(&dentry
->d_lock
);
152 spin_unlock(&dcache_lock
);
154 fsnotify_inoderemove(inode
);
155 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
156 dentry
->d_op
->d_iput(dentry
, inode
);
160 spin_unlock(&dentry
->d_lock
);
161 spin_unlock(&dcache_lock
);
166 * dentry_lru_(add|del|move_tail) must be called with d_lock held.
168 static void dentry_lru_add(struct dentry
*dentry
)
170 if (list_empty(&dentry
->d_lru
)) {
171 spin_lock(&dcache_lru_lock
);
172 list_add(&dentry
->d_lru
, &dentry
->d_sb
->s_dentry_lru
);
173 dentry
->d_sb
->s_nr_dentry_unused
++;
174 dentry_stat
.nr_unused
++;
175 spin_unlock(&dcache_lru_lock
);
179 static void __dentry_lru_del(struct dentry
*dentry
)
181 list_del_init(&dentry
->d_lru
);
182 dentry
->d_sb
->s_nr_dentry_unused
--;
183 dentry_stat
.nr_unused
--;
186 static void dentry_lru_del(struct dentry
*dentry
)
188 if (!list_empty(&dentry
->d_lru
)) {
189 spin_lock(&dcache_lru_lock
);
190 __dentry_lru_del(dentry
);
191 spin_unlock(&dcache_lru_lock
);
195 static void dentry_lru_move_tail(struct dentry
*dentry
)
197 spin_lock(&dcache_lru_lock
);
198 if (list_empty(&dentry
->d_lru
)) {
199 list_add_tail(&dentry
->d_lru
, &dentry
->d_sb
->s_dentry_lru
);
200 dentry
->d_sb
->s_nr_dentry_unused
++;
201 dentry_stat
.nr_unused
++;
203 list_move_tail(&dentry
->d_lru
, &dentry
->d_sb
->s_dentry_lru
);
205 spin_unlock(&dcache_lru_lock
);
209 * d_kill - kill dentry and return parent
210 * @dentry: dentry to kill
212 * The dentry must already be unhashed and removed from the LRU.
214 * If this is the root of the dentry tree, return NULL.
216 * dcache_lock and d_lock must be held by caller, are dropped by d_kill.
218 static struct dentry
*d_kill(struct dentry
*dentry
)
219 __releases(dentry
->d_lock
)
220 __releases(dcache_lock
)
222 struct dentry
*parent
;
224 list_del(&dentry
->d_u
.d_child
);
225 /*drops the locks, at that point nobody can reach this dentry */
230 parent
= dentry
->d_parent
;
236 * d_drop - drop a dentry
237 * @dentry: dentry to drop
239 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
240 * be found through a VFS lookup any more. Note that this is different from
241 * deleting the dentry - d_delete will try to mark the dentry negative if
242 * possible, giving a successful _negative_ lookup, while d_drop will
243 * just make the cache lookup fail.
245 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
246 * reason (NFS timeouts or autofs deletes).
248 * __d_drop requires dentry->d_lock.
250 void __d_drop(struct dentry
*dentry
)
252 if (!(dentry
->d_flags
& DCACHE_UNHASHED
)) {
253 dentry
->d_flags
|= DCACHE_UNHASHED
;
254 spin_lock(&dcache_hash_lock
);
255 hlist_del_rcu(&dentry
->d_hash
);
256 spin_unlock(&dcache_hash_lock
);
259 EXPORT_SYMBOL(__d_drop
);
261 void d_drop(struct dentry
*dentry
)
263 spin_lock(&dcache_lock
);
264 spin_lock(&dentry
->d_lock
);
266 spin_unlock(&dentry
->d_lock
);
267 spin_unlock(&dcache_lock
);
269 EXPORT_SYMBOL(d_drop
);
274 * This is complicated by the fact that we do not want to put
275 * dentries that are no longer on any hash chain on the unused
276 * list: we'd much rather just get rid of them immediately.
278 * However, that implies that we have to traverse the dentry
279 * tree upwards to the parents which might _also_ now be
280 * scheduled for deletion (it may have been only waiting for
281 * its last child to go away).
283 * This tail recursion is done by hand as we don't want to depend
284 * on the compiler to always get this right (gcc generally doesn't).
285 * Real recursion would eat up our stack space.
289 * dput - release a dentry
290 * @dentry: dentry to release
292 * Release a dentry. This will drop the usage count and if appropriate
293 * call the dentry unlink method as well as removing it from the queues and
294 * releasing its resources. If the parent dentries were scheduled for release
295 * they too may now get deleted.
297 * no dcache lock, please.
300 void dput(struct dentry
*dentry
)
306 if (atomic_read(&dentry
->d_count
) == 1)
308 if (!atomic_dec_and_lock(&dentry
->d_count
, &dcache_lock
))
311 spin_lock(&dentry
->d_lock
);
312 if (atomic_read(&dentry
->d_count
)) {
313 spin_unlock(&dentry
->d_lock
);
314 spin_unlock(&dcache_lock
);
319 * AV: ->d_delete() is _NOT_ allowed to block now.
321 if (dentry
->d_op
&& dentry
->d_op
->d_delete
) {
322 if (dentry
->d_op
->d_delete(dentry
))
326 /* Unreachable? Get rid of it */
327 if (d_unhashed(dentry
))
330 /* Otherwise leave it cached and ensure it's on the LRU */
331 dentry
->d_flags
|= DCACHE_REFERENCED
;
332 dentry_lru_add(dentry
);
334 spin_unlock(&dentry
->d_lock
);
335 spin_unlock(&dcache_lock
);
341 /* if dentry was on the d_lru list delete it from there */
342 dentry_lru_del(dentry
);
343 dentry
= d_kill(dentry
);
350 * d_invalidate - invalidate a dentry
351 * @dentry: dentry to invalidate
353 * Try to invalidate the dentry if it turns out to be
354 * possible. If there are other dentries that can be
355 * reached through this one we can't delete it and we
356 * return -EBUSY. On success we return 0.
361 int d_invalidate(struct dentry
* dentry
)
364 * If it's already been dropped, return OK.
366 spin_lock(&dcache_lock
);
367 if (d_unhashed(dentry
)) {
368 spin_unlock(&dcache_lock
);
372 * Check whether to do a partial shrink_dcache
373 * to get rid of unused child entries.
375 if (!list_empty(&dentry
->d_subdirs
)) {
376 spin_unlock(&dcache_lock
);
377 shrink_dcache_parent(dentry
);
378 spin_lock(&dcache_lock
);
382 * Somebody else still using it?
384 * If it's a directory, we can't drop it
385 * for fear of somebody re-populating it
386 * with children (even though dropping it
387 * would make it unreachable from the root,
388 * we might still populate it if it was a
389 * working directory or similar).
391 spin_lock(&dentry
->d_lock
);
392 if (atomic_read(&dentry
->d_count
) > 1) {
393 if (dentry
->d_inode
&& S_ISDIR(dentry
->d_inode
->i_mode
)) {
394 spin_unlock(&dentry
->d_lock
);
395 spin_unlock(&dcache_lock
);
401 spin_unlock(&dentry
->d_lock
);
402 spin_unlock(&dcache_lock
);
405 EXPORT_SYMBOL(d_invalidate
);
407 /* This should be called _only_ with dcache_lock held */
408 static inline struct dentry
* __dget_locked_dlock(struct dentry
*dentry
)
410 atomic_inc(&dentry
->d_count
);
411 dentry_lru_del(dentry
);
415 static inline struct dentry
* __dget_locked(struct dentry
*dentry
)
417 atomic_inc(&dentry
->d_count
);
418 spin_lock(&dentry
->d_lock
);
419 dentry_lru_del(dentry
);
420 spin_unlock(&dentry
->d_lock
);
424 struct dentry
* dget_locked(struct dentry
*dentry
)
426 return __dget_locked(dentry
);
428 EXPORT_SYMBOL(dget_locked
);
431 * d_find_alias - grab a hashed alias of inode
432 * @inode: inode in question
433 * @want_discon: flag, used by d_splice_alias, to request
434 * that only a DISCONNECTED alias be returned.
436 * If inode has a hashed alias, or is a directory and has any alias,
437 * acquire the reference to alias and return it. Otherwise return NULL.
438 * Notice that if inode is a directory there can be only one alias and
439 * it can be unhashed only if it has no children, or if it is the root
442 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
443 * any other hashed alias over that one unless @want_discon is set,
444 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
447 static struct dentry
* __d_find_alias(struct inode
*inode
, int want_discon
)
449 struct list_head
*head
, *next
, *tmp
;
450 struct dentry
*alias
, *discon_alias
=NULL
;
452 head
= &inode
->i_dentry
;
453 next
= inode
->i_dentry
.next
;
454 while (next
!= head
) {
458 alias
= list_entry(tmp
, struct dentry
, d_alias
);
459 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
460 if (IS_ROOT(alias
) &&
461 (alias
->d_flags
& DCACHE_DISCONNECTED
))
462 discon_alias
= alias
;
463 else if (!want_discon
) {
464 __dget_locked(alias
);
470 __dget_locked(discon_alias
);
474 struct dentry
* d_find_alias(struct inode
*inode
)
476 struct dentry
*de
= NULL
;
478 if (!list_empty(&inode
->i_dentry
)) {
479 spin_lock(&dcache_lock
);
480 de
= __d_find_alias(inode
, 0);
481 spin_unlock(&dcache_lock
);
485 EXPORT_SYMBOL(d_find_alias
);
488 * Try to kill dentries associated with this inode.
489 * WARNING: you must own a reference to inode.
491 void d_prune_aliases(struct inode
*inode
)
493 struct dentry
*dentry
;
495 spin_lock(&dcache_lock
);
496 list_for_each_entry(dentry
, &inode
->i_dentry
, d_alias
) {
497 spin_lock(&dentry
->d_lock
);
498 if (!atomic_read(&dentry
->d_count
)) {
499 __dget_locked_dlock(dentry
);
501 spin_unlock(&dentry
->d_lock
);
502 spin_unlock(&dcache_lock
);
506 spin_unlock(&dentry
->d_lock
);
508 spin_unlock(&dcache_lock
);
510 EXPORT_SYMBOL(d_prune_aliases
);
513 * Throw away a dentry - free the inode, dput the parent. This requires that
514 * the LRU list has already been removed.
516 * Try to prune ancestors as well. This is necessary to prevent
517 * quadratic behavior of shrink_dcache_parent(), but is also expected
518 * to be beneficial in reducing dentry cache fragmentation.
520 static void prune_one_dentry(struct dentry
* dentry
)
521 __releases(dentry
->d_lock
)
522 __releases(dcache_lock
)
525 dentry
= d_kill(dentry
);
528 * Prune ancestors. Locking is simpler than in dput(),
529 * because dcache_lock needs to be taken anyway.
532 spin_lock(&dcache_lock
);
533 if (!atomic_dec_and_lock(&dentry
->d_count
, &dentry
->d_lock
)) {
534 spin_unlock(&dcache_lock
);
538 dentry_lru_del(dentry
);
540 dentry
= d_kill(dentry
);
544 static void shrink_dentry_list(struct list_head
*list
)
546 struct dentry
*dentry
;
548 while (!list_empty(list
)) {
549 dentry
= list_entry(list
->prev
, struct dentry
, d_lru
);
551 if (!spin_trylock(&dentry
->d_lock
)) {
552 spin_unlock(&dcache_lru_lock
);
554 spin_lock(&dcache_lru_lock
);
558 __dentry_lru_del(dentry
);
561 * We found an inuse dentry which was not removed from
562 * the LRU because of laziness during lookup. Do not free
563 * it - just keep it off the LRU list.
565 if (atomic_read(&dentry
->d_count
)) {
566 spin_unlock(&dentry
->d_lock
);
569 spin_unlock(&dcache_lru_lock
);
571 prune_one_dentry(dentry
);
572 /* dcache_lock and dentry->d_lock dropped */
573 spin_lock(&dcache_lock
);
574 spin_lock(&dcache_lru_lock
);
579 * __shrink_dcache_sb - shrink the dentry LRU on a given superblock
580 * @sb: superblock to shrink dentry LRU.
581 * @count: number of entries to prune
582 * @flags: flags to control the dentry processing
584 * If flags contains DCACHE_REFERENCED reference dentries will not be pruned.
586 static void __shrink_dcache_sb(struct super_block
*sb
, int *count
, int flags
)
588 /* called from prune_dcache() and shrink_dcache_parent() */
589 struct dentry
*dentry
;
590 LIST_HEAD(referenced
);
594 spin_lock(&dcache_lock
);
596 spin_lock(&dcache_lru_lock
);
597 while (!list_empty(&sb
->s_dentry_lru
)) {
598 dentry
= list_entry(sb
->s_dentry_lru
.prev
,
599 struct dentry
, d_lru
);
600 BUG_ON(dentry
->d_sb
!= sb
);
602 if (!spin_trylock(&dentry
->d_lock
)) {
603 spin_unlock(&dcache_lru_lock
);
609 * If we are honouring the DCACHE_REFERENCED flag and the
610 * dentry has this flag set, don't free it. Clear the flag
611 * and put it back on the LRU.
613 if (flags
& DCACHE_REFERENCED
&&
614 dentry
->d_flags
& DCACHE_REFERENCED
) {
615 dentry
->d_flags
&= ~DCACHE_REFERENCED
;
616 list_move(&dentry
->d_lru
, &referenced
);
617 spin_unlock(&dentry
->d_lock
);
619 list_move_tail(&dentry
->d_lru
, &tmp
);
620 spin_unlock(&dentry
->d_lock
);
624 /* XXX: re-add cond_resched_lock when dcache_lock goes away */
628 shrink_dentry_list(&tmp
);
630 if (!list_empty(&referenced
))
631 list_splice(&referenced
, &sb
->s_dentry_lru
);
632 spin_unlock(&dcache_lru_lock
);
633 spin_unlock(&dcache_lock
);
638 * prune_dcache - shrink the dcache
639 * @count: number of entries to try to free
641 * Shrink the dcache. This is done when we need more memory, or simply when we
642 * need to unmount something (at which point we need to unuse all dentries).
644 * This function may fail to free any resources if all the dentries are in use.
646 static void prune_dcache(int count
)
648 struct super_block
*sb
, *p
= NULL
;
650 int unused
= dentry_stat
.nr_unused
;
654 if (unused
== 0 || count
== 0)
656 spin_lock(&dcache_lock
);
660 prune_ratio
= unused
/ count
;
662 list_for_each_entry(sb
, &super_blocks
, s_list
) {
663 if (list_empty(&sb
->s_instances
))
665 if (sb
->s_nr_dentry_unused
== 0)
668 /* Now, we reclaim unused dentrins with fairness.
669 * We reclaim them same percentage from each superblock.
670 * We calculate number of dentries to scan on this sb
671 * as follows, but the implementation is arranged to avoid
673 * number of dentries to scan on this sb =
674 * count * (number of dentries on this sb /
675 * number of dentries in the machine)
677 spin_unlock(&sb_lock
);
678 if (prune_ratio
!= 1)
679 w_count
= (sb
->s_nr_dentry_unused
/ prune_ratio
) + 1;
681 w_count
= sb
->s_nr_dentry_unused
;
684 * We need to be sure this filesystem isn't being unmounted,
685 * otherwise we could race with generic_shutdown_super(), and
686 * end up holding a reference to an inode while the filesystem
687 * is unmounted. So we try to get s_umount, and make sure
690 if (down_read_trylock(&sb
->s_umount
)) {
691 if ((sb
->s_root
!= NULL
) &&
692 (!list_empty(&sb
->s_dentry_lru
))) {
693 spin_unlock(&dcache_lock
);
694 __shrink_dcache_sb(sb
, &w_count
,
697 spin_lock(&dcache_lock
);
699 up_read(&sb
->s_umount
);
706 /* more work left to do? */
712 spin_unlock(&sb_lock
);
713 spin_unlock(&dcache_lock
);
717 * shrink_dcache_sb - shrink dcache for a superblock
720 * Shrink the dcache for the specified super block. This is used to free
721 * the dcache before unmounting a file system.
723 void shrink_dcache_sb(struct super_block
*sb
)
727 spin_lock(&dcache_lock
);
728 spin_lock(&dcache_lru_lock
);
729 while (!list_empty(&sb
->s_dentry_lru
)) {
730 list_splice_init(&sb
->s_dentry_lru
, &tmp
);
731 shrink_dentry_list(&tmp
);
733 spin_unlock(&dcache_lru_lock
);
734 spin_unlock(&dcache_lock
);
736 EXPORT_SYMBOL(shrink_dcache_sb
);
739 * destroy a single subtree of dentries for unmount
740 * - see the comments on shrink_dcache_for_umount() for a description of the
743 static void shrink_dcache_for_umount_subtree(struct dentry
*dentry
)
745 struct dentry
*parent
;
746 unsigned detached
= 0;
748 BUG_ON(!IS_ROOT(dentry
));
750 /* detach this root from the system */
751 spin_lock(&dcache_lock
);
752 spin_lock(&dentry
->d_lock
);
753 dentry_lru_del(dentry
);
754 spin_unlock(&dentry
->d_lock
);
756 spin_unlock(&dcache_lock
);
759 /* descend to the first leaf in the current subtree */
760 while (!list_empty(&dentry
->d_subdirs
)) {
763 /* this is a branch with children - detach all of them
764 * from the system in one go */
765 spin_lock(&dcache_lock
);
766 list_for_each_entry(loop
, &dentry
->d_subdirs
,
768 spin_lock(&loop
->d_lock
);
769 dentry_lru_del(loop
);
770 spin_unlock(&loop
->d_lock
);
772 cond_resched_lock(&dcache_lock
);
774 spin_unlock(&dcache_lock
);
776 /* move to the first child */
777 dentry
= list_entry(dentry
->d_subdirs
.next
,
778 struct dentry
, d_u
.d_child
);
781 /* consume the dentries from this leaf up through its parents
782 * until we find one with children or run out altogether */
786 if (atomic_read(&dentry
->d_count
) != 0) {
788 "BUG: Dentry %p{i=%lx,n=%s}"
790 " [unmount of %s %s]\n",
793 dentry
->d_inode
->i_ino
: 0UL,
795 atomic_read(&dentry
->d_count
),
796 dentry
->d_sb
->s_type
->name
,
804 parent
= dentry
->d_parent
;
805 atomic_dec(&parent
->d_count
);
808 list_del(&dentry
->d_u
.d_child
);
811 inode
= dentry
->d_inode
;
813 dentry
->d_inode
= NULL
;
814 list_del_init(&dentry
->d_alias
);
815 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
816 dentry
->d_op
->d_iput(dentry
, inode
);
823 /* finished when we fall off the top of the tree,
824 * otherwise we ascend to the parent and move to the
825 * next sibling if there is one */
829 } while (list_empty(&dentry
->d_subdirs
));
831 dentry
= list_entry(dentry
->d_subdirs
.next
,
832 struct dentry
, d_u
.d_child
);
837 * destroy the dentries attached to a superblock on unmounting
838 * - we don't need to use dentry->d_lock, and only need dcache_lock when
839 * removing the dentry from the system lists and hashes because:
840 * - the superblock is detached from all mountings and open files, so the
841 * dentry trees will not be rearranged by the VFS
842 * - s_umount is write-locked, so the memory pressure shrinker will ignore
843 * any dentries belonging to this superblock that it comes across
844 * - the filesystem itself is no longer permitted to rearrange the dentries
847 void shrink_dcache_for_umount(struct super_block
*sb
)
849 struct dentry
*dentry
;
851 if (down_read_trylock(&sb
->s_umount
))
856 atomic_dec(&dentry
->d_count
);
857 shrink_dcache_for_umount_subtree(dentry
);
859 while (!hlist_empty(&sb
->s_anon
)) {
860 dentry
= hlist_entry(sb
->s_anon
.first
, struct dentry
, d_hash
);
861 shrink_dcache_for_umount_subtree(dentry
);
866 * Search for at least 1 mount point in the dentry's subdirs.
867 * We descend to the next level whenever the d_subdirs
868 * list is non-empty and continue searching.
872 * have_submounts - check for mounts over a dentry
873 * @parent: dentry to check.
875 * Return true if the parent or its subdirectories contain
879 int have_submounts(struct dentry
*parent
)
881 struct dentry
*this_parent
= parent
;
882 struct list_head
*next
;
884 spin_lock(&dcache_lock
);
885 if (d_mountpoint(parent
))
888 next
= this_parent
->d_subdirs
.next
;
890 while (next
!= &this_parent
->d_subdirs
) {
891 struct list_head
*tmp
= next
;
892 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
894 /* Have we found a mount point ? */
895 if (d_mountpoint(dentry
))
897 if (!list_empty(&dentry
->d_subdirs
)) {
898 this_parent
= dentry
;
903 * All done at this level ... ascend and resume the search.
905 if (this_parent
!= parent
) {
906 next
= this_parent
->d_u
.d_child
.next
;
907 this_parent
= this_parent
->d_parent
;
910 spin_unlock(&dcache_lock
);
911 return 0; /* No mount points found in tree */
913 spin_unlock(&dcache_lock
);
916 EXPORT_SYMBOL(have_submounts
);
919 * Search the dentry child list for the specified parent,
920 * and move any unused dentries to the end of the unused
921 * list for prune_dcache(). We descend to the next level
922 * whenever the d_subdirs list is non-empty and continue
925 * It returns zero iff there are no unused children,
926 * otherwise it returns the number of children moved to
927 * the end of the unused list. This may not be the total
928 * number of unused children, because select_parent can
929 * drop the lock and return early due to latency
932 static int select_parent(struct dentry
* parent
)
934 struct dentry
*this_parent
= parent
;
935 struct list_head
*next
;
938 spin_lock(&dcache_lock
);
940 next
= this_parent
->d_subdirs
.next
;
942 while (next
!= &this_parent
->d_subdirs
) {
943 struct list_head
*tmp
= next
;
944 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
947 spin_lock(&dentry
->d_lock
);
950 * move only zero ref count dentries to the end
951 * of the unused list for prune_dcache
953 if (!atomic_read(&dentry
->d_count
)) {
954 dentry_lru_move_tail(dentry
);
957 dentry_lru_del(dentry
);
960 spin_unlock(&dentry
->d_lock
);
963 * We can return to the caller if we have found some (this
964 * ensures forward progress). We'll be coming back to find
967 if (found
&& need_resched())
971 * Descend a level if the d_subdirs list is non-empty.
973 if (!list_empty(&dentry
->d_subdirs
)) {
974 this_parent
= dentry
;
979 * All done at this level ... ascend and resume the search.
981 if (this_parent
!= parent
) {
982 next
= this_parent
->d_u
.d_child
.next
;
983 this_parent
= this_parent
->d_parent
;
987 spin_unlock(&dcache_lock
);
992 * shrink_dcache_parent - prune dcache
993 * @parent: parent of entries to prune
995 * Prune the dcache to remove unused children of the parent dentry.
998 void shrink_dcache_parent(struct dentry
* parent
)
1000 struct super_block
*sb
= parent
->d_sb
;
1003 while ((found
= select_parent(parent
)) != 0)
1004 __shrink_dcache_sb(sb
, &found
, 0);
1006 EXPORT_SYMBOL(shrink_dcache_parent
);
1009 * Scan `nr' dentries and return the number which remain.
1011 * We need to avoid reentering the filesystem if the caller is performing a
1012 * GFP_NOFS allocation attempt. One example deadlock is:
1014 * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache->
1015 * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode->
1016 * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK.
1018 * In this case we return -1 to tell the caller that we baled.
1020 static int shrink_dcache_memory(struct shrinker
*shrink
, int nr
, gfp_t gfp_mask
)
1023 if (!(gfp_mask
& __GFP_FS
))
1028 return (dentry_stat
.nr_unused
/ 100) * sysctl_vfs_cache_pressure
;
1031 static struct shrinker dcache_shrinker
= {
1032 .shrink
= shrink_dcache_memory
,
1033 .seeks
= DEFAULT_SEEKS
,
1037 * d_alloc - allocate a dcache entry
1038 * @parent: parent of entry to allocate
1039 * @name: qstr of the name
1041 * Allocates a dentry. It returns %NULL if there is insufficient memory
1042 * available. On a success the dentry is returned. The name passed in is
1043 * copied and the copy passed in may be reused after this call.
1046 struct dentry
*d_alloc(struct dentry
* parent
, const struct qstr
*name
)
1048 struct dentry
*dentry
;
1051 dentry
= kmem_cache_alloc(dentry_cache
, GFP_KERNEL
);
1055 if (name
->len
> DNAME_INLINE_LEN
-1) {
1056 dname
= kmalloc(name
->len
+ 1, GFP_KERNEL
);
1058 kmem_cache_free(dentry_cache
, dentry
);
1062 dname
= dentry
->d_iname
;
1064 dentry
->d_name
.name
= dname
;
1066 dentry
->d_name
.len
= name
->len
;
1067 dentry
->d_name
.hash
= name
->hash
;
1068 memcpy(dname
, name
->name
, name
->len
);
1069 dname
[name
->len
] = 0;
1071 atomic_set(&dentry
->d_count
, 1);
1072 dentry
->d_flags
= DCACHE_UNHASHED
;
1073 spin_lock_init(&dentry
->d_lock
);
1074 dentry
->d_inode
= NULL
;
1075 dentry
->d_parent
= NULL
;
1076 dentry
->d_sb
= NULL
;
1077 dentry
->d_op
= NULL
;
1078 dentry
->d_fsdata
= NULL
;
1079 dentry
->d_mounted
= 0;
1080 INIT_HLIST_NODE(&dentry
->d_hash
);
1081 INIT_LIST_HEAD(&dentry
->d_lru
);
1082 INIT_LIST_HEAD(&dentry
->d_subdirs
);
1083 INIT_LIST_HEAD(&dentry
->d_alias
);
1086 dentry
->d_parent
= dget(parent
);
1087 dentry
->d_sb
= parent
->d_sb
;
1089 INIT_LIST_HEAD(&dentry
->d_u
.d_child
);
1092 spin_lock(&dcache_lock
);
1094 list_add(&dentry
->d_u
.d_child
, &parent
->d_subdirs
);
1095 spin_unlock(&dcache_lock
);
1097 this_cpu_inc(nr_dentry
);
1101 EXPORT_SYMBOL(d_alloc
);
1103 struct dentry
*d_alloc_name(struct dentry
*parent
, const char *name
)
1108 q
.len
= strlen(name
);
1109 q
.hash
= full_name_hash(q
.name
, q
.len
);
1110 return d_alloc(parent
, &q
);
1112 EXPORT_SYMBOL(d_alloc_name
);
1114 /* the caller must hold dcache_lock */
1115 static void __d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
1118 list_add(&dentry
->d_alias
, &inode
->i_dentry
);
1119 dentry
->d_inode
= inode
;
1120 fsnotify_d_instantiate(dentry
, inode
);
1124 * d_instantiate - fill in inode information for a dentry
1125 * @entry: dentry to complete
1126 * @inode: inode to attach to this dentry
1128 * Fill in inode information in the entry.
1130 * This turns negative dentries into productive full members
1133 * NOTE! This assumes that the inode count has been incremented
1134 * (or otherwise set) by the caller to indicate that it is now
1135 * in use by the dcache.
1138 void d_instantiate(struct dentry
*entry
, struct inode
* inode
)
1140 BUG_ON(!list_empty(&entry
->d_alias
));
1141 spin_lock(&dcache_lock
);
1142 __d_instantiate(entry
, inode
);
1143 spin_unlock(&dcache_lock
);
1144 security_d_instantiate(entry
, inode
);
1146 EXPORT_SYMBOL(d_instantiate
);
1149 * d_instantiate_unique - instantiate a non-aliased dentry
1150 * @entry: dentry to instantiate
1151 * @inode: inode to attach to this dentry
1153 * Fill in inode information in the entry. On success, it returns NULL.
1154 * If an unhashed alias of "entry" already exists, then we return the
1155 * aliased dentry instead and drop one reference to inode.
1157 * Note that in order to avoid conflicts with rename() etc, the caller
1158 * had better be holding the parent directory semaphore.
1160 * This also assumes that the inode count has been incremented
1161 * (or otherwise set) by the caller to indicate that it is now
1162 * in use by the dcache.
1164 static struct dentry
*__d_instantiate_unique(struct dentry
*entry
,
1165 struct inode
*inode
)
1167 struct dentry
*alias
;
1168 int len
= entry
->d_name
.len
;
1169 const char *name
= entry
->d_name
.name
;
1170 unsigned int hash
= entry
->d_name
.hash
;
1173 __d_instantiate(entry
, NULL
);
1177 list_for_each_entry(alias
, &inode
->i_dentry
, d_alias
) {
1178 struct qstr
*qstr
= &alias
->d_name
;
1180 if (qstr
->hash
!= hash
)
1182 if (alias
->d_parent
!= entry
->d_parent
)
1184 if (qstr
->len
!= len
)
1186 if (memcmp(qstr
->name
, name
, len
))
1192 __d_instantiate(entry
, inode
);
1196 struct dentry
*d_instantiate_unique(struct dentry
*entry
, struct inode
*inode
)
1198 struct dentry
*result
;
1200 BUG_ON(!list_empty(&entry
->d_alias
));
1202 spin_lock(&dcache_lock
);
1203 result
= __d_instantiate_unique(entry
, inode
);
1204 spin_unlock(&dcache_lock
);
1207 security_d_instantiate(entry
, inode
);
1211 BUG_ON(!d_unhashed(result
));
1216 EXPORT_SYMBOL(d_instantiate_unique
);
1219 * d_alloc_root - allocate root dentry
1220 * @root_inode: inode to allocate the root for
1222 * Allocate a root ("/") dentry for the inode given. The inode is
1223 * instantiated and returned. %NULL is returned if there is insufficient
1224 * memory or the inode passed is %NULL.
1227 struct dentry
* d_alloc_root(struct inode
* root_inode
)
1229 struct dentry
*res
= NULL
;
1232 static const struct qstr name
= { .name
= "/", .len
= 1 };
1234 res
= d_alloc(NULL
, &name
);
1236 res
->d_sb
= root_inode
->i_sb
;
1237 res
->d_parent
= res
;
1238 d_instantiate(res
, root_inode
);
1243 EXPORT_SYMBOL(d_alloc_root
);
1245 static inline struct hlist_head
*d_hash(struct dentry
*parent
,
1248 hash
+= ((unsigned long) parent
^ GOLDEN_RATIO_PRIME
) / L1_CACHE_BYTES
;
1249 hash
= hash
^ ((hash
^ GOLDEN_RATIO_PRIME
) >> D_HASHBITS
);
1250 return dentry_hashtable
+ (hash
& D_HASHMASK
);
1254 * d_obtain_alias - find or allocate a dentry for a given inode
1255 * @inode: inode to allocate the dentry for
1257 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1258 * similar open by handle operations. The returned dentry may be anonymous,
1259 * or may have a full name (if the inode was already in the cache).
1261 * When called on a directory inode, we must ensure that the inode only ever
1262 * has one dentry. If a dentry is found, that is returned instead of
1263 * allocating a new one.
1265 * On successful return, the reference to the inode has been transferred
1266 * to the dentry. In case of an error the reference on the inode is released.
1267 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1268 * be passed in and will be the error will be propagate to the return value,
1269 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
1271 struct dentry
*d_obtain_alias(struct inode
*inode
)
1273 static const struct qstr anonstring
= { .name
= "" };
1278 return ERR_PTR(-ESTALE
);
1280 return ERR_CAST(inode
);
1282 res
= d_find_alias(inode
);
1286 tmp
= d_alloc(NULL
, &anonstring
);
1288 res
= ERR_PTR(-ENOMEM
);
1291 tmp
->d_parent
= tmp
; /* make sure dput doesn't croak */
1293 spin_lock(&dcache_lock
);
1294 res
= __d_find_alias(inode
, 0);
1296 spin_unlock(&dcache_lock
);
1301 /* attach a disconnected dentry */
1302 spin_lock(&tmp
->d_lock
);
1303 tmp
->d_sb
= inode
->i_sb
;
1304 tmp
->d_inode
= inode
;
1305 tmp
->d_flags
|= DCACHE_DISCONNECTED
;
1306 tmp
->d_flags
&= ~DCACHE_UNHASHED
;
1307 list_add(&tmp
->d_alias
, &inode
->i_dentry
);
1308 spin_lock(&dcache_hash_lock
);
1309 hlist_add_head(&tmp
->d_hash
, &inode
->i_sb
->s_anon
);
1310 spin_unlock(&dcache_hash_lock
);
1311 spin_unlock(&tmp
->d_lock
);
1313 spin_unlock(&dcache_lock
);
1320 EXPORT_SYMBOL(d_obtain_alias
);
1323 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1324 * @inode: the inode which may have a disconnected dentry
1325 * @dentry: a negative dentry which we want to point to the inode.
1327 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1328 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1329 * and return it, else simply d_add the inode to the dentry and return NULL.
1331 * This is needed in the lookup routine of any filesystem that is exportable
1332 * (via knfsd) so that we can build dcache paths to directories effectively.
1334 * If a dentry was found and moved, then it is returned. Otherwise NULL
1335 * is returned. This matches the expected return value of ->lookup.
1338 struct dentry
*d_splice_alias(struct inode
*inode
, struct dentry
*dentry
)
1340 struct dentry
*new = NULL
;
1342 if (inode
&& S_ISDIR(inode
->i_mode
)) {
1343 spin_lock(&dcache_lock
);
1344 new = __d_find_alias(inode
, 1);
1346 BUG_ON(!(new->d_flags
& DCACHE_DISCONNECTED
));
1347 spin_unlock(&dcache_lock
);
1348 security_d_instantiate(new, inode
);
1349 d_move(new, dentry
);
1352 /* already taking dcache_lock, so d_add() by hand */
1353 __d_instantiate(dentry
, inode
);
1354 spin_unlock(&dcache_lock
);
1355 security_d_instantiate(dentry
, inode
);
1359 d_add(dentry
, inode
);
1362 EXPORT_SYMBOL(d_splice_alias
);
1365 * d_add_ci - lookup or allocate new dentry with case-exact name
1366 * @inode: the inode case-insensitive lookup has found
1367 * @dentry: the negative dentry that was passed to the parent's lookup func
1368 * @name: the case-exact name to be associated with the returned dentry
1370 * This is to avoid filling the dcache with case-insensitive names to the
1371 * same inode, only the actual correct case is stored in the dcache for
1372 * case-insensitive filesystems.
1374 * For a case-insensitive lookup match and if the the case-exact dentry
1375 * already exists in in the dcache, use it and return it.
1377 * If no entry exists with the exact case name, allocate new dentry with
1378 * the exact case, and return the spliced entry.
1380 struct dentry
*d_add_ci(struct dentry
*dentry
, struct inode
*inode
,
1384 struct dentry
*found
;
1388 * First check if a dentry matching the name already exists,
1389 * if not go ahead and create it now.
1391 found
= d_hash_and_lookup(dentry
->d_parent
, name
);
1393 new = d_alloc(dentry
->d_parent
, name
);
1399 found
= d_splice_alias(inode
, new);
1408 * If a matching dentry exists, and it's not negative use it.
1410 * Decrement the reference count to balance the iget() done
1413 if (found
->d_inode
) {
1414 if (unlikely(found
->d_inode
!= inode
)) {
1415 /* This can't happen because bad inodes are unhashed. */
1416 BUG_ON(!is_bad_inode(inode
));
1417 BUG_ON(!is_bad_inode(found
->d_inode
));
1424 * Negative dentry: instantiate it unless the inode is a directory and
1425 * already has a dentry.
1427 spin_lock(&dcache_lock
);
1428 if (!S_ISDIR(inode
->i_mode
) || list_empty(&inode
->i_dentry
)) {
1429 __d_instantiate(found
, inode
);
1430 spin_unlock(&dcache_lock
);
1431 security_d_instantiate(found
, inode
);
1436 * In case a directory already has a (disconnected) entry grab a
1437 * reference to it, move it in place and use it.
1439 new = list_entry(inode
->i_dentry
.next
, struct dentry
, d_alias
);
1441 spin_unlock(&dcache_lock
);
1442 security_d_instantiate(found
, inode
);
1450 return ERR_PTR(error
);
1452 EXPORT_SYMBOL(d_add_ci
);
1455 * d_lookup - search for a dentry
1456 * @parent: parent dentry
1457 * @name: qstr of name we wish to find
1458 * Returns: dentry, or NULL
1460 * d_lookup searches the children of the parent dentry for the name in
1461 * question. If the dentry is found its reference count is incremented and the
1462 * dentry is returned. The caller must use dput to free the entry when it has
1463 * finished using it. %NULL is returned if the dentry does not exist.
1465 struct dentry
* d_lookup(struct dentry
* parent
, struct qstr
* name
)
1467 struct dentry
* dentry
= NULL
;
1471 seq
= read_seqbegin(&rename_lock
);
1472 dentry
= __d_lookup(parent
, name
);
1475 } while (read_seqretry(&rename_lock
, seq
));
1478 EXPORT_SYMBOL(d_lookup
);
1481 * __d_lookup - search for a dentry (racy)
1482 * @parent: parent dentry
1483 * @name: qstr of name we wish to find
1484 * Returns: dentry, or NULL
1486 * __d_lookup is like d_lookup, however it may (rarely) return a
1487 * false-negative result due to unrelated rename activity.
1489 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
1490 * however it must be used carefully, eg. with a following d_lookup in
1491 * the case of failure.
1493 * __d_lookup callers must be commented.
1495 struct dentry
* __d_lookup(struct dentry
* parent
, struct qstr
* name
)
1497 unsigned int len
= name
->len
;
1498 unsigned int hash
= name
->hash
;
1499 const unsigned char *str
= name
->name
;
1500 struct hlist_head
*head
= d_hash(parent
,hash
);
1501 struct dentry
*found
= NULL
;
1502 struct hlist_node
*node
;
1503 struct dentry
*dentry
;
1506 * The hash list is protected using RCU.
1508 * Take d_lock when comparing a candidate dentry, to avoid races
1511 * It is possible that concurrent renames can mess up our list
1512 * walk here and result in missing our dentry, resulting in the
1513 * false-negative result. d_lookup() protects against concurrent
1514 * renames using rename_lock seqlock.
1516 * See Documentation/vfs/dcache-locking.txt for more details.
1520 hlist_for_each_entry_rcu(dentry
, node
, head
, d_hash
) {
1523 if (dentry
->d_name
.hash
!= hash
)
1525 if (dentry
->d_parent
!= parent
)
1528 spin_lock(&dentry
->d_lock
);
1531 * Recheck the dentry after taking the lock - d_move may have
1532 * changed things. Don't bother checking the hash because
1533 * we're about to compare the whole name anyway.
1535 if (dentry
->d_parent
!= parent
)
1538 /* non-existing due to RCU? */
1539 if (d_unhashed(dentry
))
1543 * It is safe to compare names since d_move() cannot
1544 * change the qstr (protected by d_lock).
1546 qstr
= &dentry
->d_name
;
1547 if (parent
->d_op
&& parent
->d_op
->d_compare
) {
1548 if (parent
->d_op
->d_compare(parent
, parent
->d_inode
,
1549 dentry
, dentry
->d_inode
,
1550 qstr
->len
, qstr
->name
, name
))
1553 if (qstr
->len
!= len
)
1555 if (memcmp(qstr
->name
, str
, len
))
1559 atomic_inc(&dentry
->d_count
);
1561 spin_unlock(&dentry
->d_lock
);
1564 spin_unlock(&dentry
->d_lock
);
1572 * d_hash_and_lookup - hash the qstr then search for a dentry
1573 * @dir: Directory to search in
1574 * @name: qstr of name we wish to find
1576 * On hash failure or on lookup failure NULL is returned.
1578 struct dentry
*d_hash_and_lookup(struct dentry
*dir
, struct qstr
*name
)
1580 struct dentry
*dentry
= NULL
;
1583 * Check for a fs-specific hash function. Note that we must
1584 * calculate the standard hash first, as the d_op->d_hash()
1585 * routine may choose to leave the hash value unchanged.
1587 name
->hash
= full_name_hash(name
->name
, name
->len
);
1588 if (dir
->d_op
&& dir
->d_op
->d_hash
) {
1589 if (dir
->d_op
->d_hash(dir
, dir
->d_inode
, name
) < 0)
1592 dentry
= d_lookup(dir
, name
);
1598 * d_validate - verify dentry provided from insecure source (deprecated)
1599 * @dentry: The dentry alleged to be valid child of @dparent
1600 * @dparent: The parent dentry (known to be valid)
1602 * An insecure source has sent us a dentry, here we verify it and dget() it.
1603 * This is used by ncpfs in its readdir implementation.
1604 * Zero is returned in the dentry is invalid.
1606 * This function is slow for big directories, and deprecated, do not use it.
1608 int d_validate(struct dentry
*dentry
, struct dentry
*dparent
)
1610 struct dentry
*child
;
1612 spin_lock(&dcache_lock
);
1613 list_for_each_entry(child
, &dparent
->d_subdirs
, d_u
.d_child
) {
1614 if (dentry
== child
) {
1615 __dget_locked(dentry
);
1616 spin_unlock(&dcache_lock
);
1620 spin_unlock(&dcache_lock
);
1624 EXPORT_SYMBOL(d_validate
);
1627 * When a file is deleted, we have two options:
1628 * - turn this dentry into a negative dentry
1629 * - unhash this dentry and free it.
1631 * Usually, we want to just turn this into
1632 * a negative dentry, but if anybody else is
1633 * currently using the dentry or the inode
1634 * we can't do that and we fall back on removing
1635 * it from the hash queues and waiting for
1636 * it to be deleted later when it has no users
1640 * d_delete - delete a dentry
1641 * @dentry: The dentry to delete
1643 * Turn the dentry into a negative dentry if possible, otherwise
1644 * remove it from the hash queues so it can be deleted later
1647 void d_delete(struct dentry
* dentry
)
1651 * Are we the only user?
1653 spin_lock(&dcache_lock
);
1654 spin_lock(&dentry
->d_lock
);
1655 isdir
= S_ISDIR(dentry
->d_inode
->i_mode
);
1656 if (atomic_read(&dentry
->d_count
) == 1) {
1657 dentry
->d_flags
&= ~DCACHE_CANT_MOUNT
;
1658 dentry_iput(dentry
);
1659 fsnotify_nameremove(dentry
, isdir
);
1663 if (!d_unhashed(dentry
))
1666 spin_unlock(&dentry
->d_lock
);
1667 spin_unlock(&dcache_lock
);
1669 fsnotify_nameremove(dentry
, isdir
);
1671 EXPORT_SYMBOL(d_delete
);
1673 static void __d_rehash(struct dentry
* entry
, struct hlist_head
*list
)
1676 entry
->d_flags
&= ~DCACHE_UNHASHED
;
1677 hlist_add_head_rcu(&entry
->d_hash
, list
);
1680 static void _d_rehash(struct dentry
* entry
)
1682 __d_rehash(entry
, d_hash(entry
->d_parent
, entry
->d_name
.hash
));
1686 * d_rehash - add an entry back to the hash
1687 * @entry: dentry to add to the hash
1689 * Adds a dentry to the hash according to its name.
1692 void d_rehash(struct dentry
* entry
)
1694 spin_lock(&dcache_lock
);
1695 spin_lock(&entry
->d_lock
);
1696 spin_lock(&dcache_hash_lock
);
1698 spin_unlock(&dcache_hash_lock
);
1699 spin_unlock(&entry
->d_lock
);
1700 spin_unlock(&dcache_lock
);
1702 EXPORT_SYMBOL(d_rehash
);
1705 * dentry_update_name_case - update case insensitive dentry with a new name
1706 * @dentry: dentry to be updated
1709 * Update a case insensitive dentry with new case of name.
1711 * dentry must have been returned by d_lookup with name @name. Old and new
1712 * name lengths must match (ie. no d_compare which allows mismatched name
1715 * Parent inode i_mutex must be held over d_lookup and into this call (to
1716 * keep renames and concurrent inserts, and readdir(2) away).
1718 void dentry_update_name_case(struct dentry
*dentry
, struct qstr
*name
)
1720 BUG_ON(!mutex_is_locked(&dentry
->d_inode
->i_mutex
));
1721 BUG_ON(dentry
->d_name
.len
!= name
->len
); /* d_lookup gives this */
1723 spin_lock(&dcache_lock
);
1724 spin_lock(&dentry
->d_lock
);
1725 memcpy((unsigned char *)dentry
->d_name
.name
, name
->name
, name
->len
);
1726 spin_unlock(&dentry
->d_lock
);
1727 spin_unlock(&dcache_lock
);
1729 EXPORT_SYMBOL(dentry_update_name_case
);
1732 * When switching names, the actual string doesn't strictly have to
1733 * be preserved in the target - because we're dropping the target
1734 * anyway. As such, we can just do a simple memcpy() to copy over
1735 * the new name before we switch.
1737 * Note that we have to be a lot more careful about getting the hash
1738 * switched - we have to switch the hash value properly even if it
1739 * then no longer matches the actual (corrupted) string of the target.
1740 * The hash value has to match the hash queue that the dentry is on..
1742 static void switch_names(struct dentry
*dentry
, struct dentry
*target
)
1744 if (dname_external(target
)) {
1745 if (dname_external(dentry
)) {
1747 * Both external: swap the pointers
1749 swap(target
->d_name
.name
, dentry
->d_name
.name
);
1752 * dentry:internal, target:external. Steal target's
1753 * storage and make target internal.
1755 memcpy(target
->d_iname
, dentry
->d_name
.name
,
1756 dentry
->d_name
.len
+ 1);
1757 dentry
->d_name
.name
= target
->d_name
.name
;
1758 target
->d_name
.name
= target
->d_iname
;
1761 if (dname_external(dentry
)) {
1763 * dentry:external, target:internal. Give dentry's
1764 * storage to target and make dentry internal
1766 memcpy(dentry
->d_iname
, target
->d_name
.name
,
1767 target
->d_name
.len
+ 1);
1768 target
->d_name
.name
= dentry
->d_name
.name
;
1769 dentry
->d_name
.name
= dentry
->d_iname
;
1772 * Both are internal. Just copy target to dentry
1774 memcpy(dentry
->d_iname
, target
->d_name
.name
,
1775 target
->d_name
.len
+ 1);
1776 dentry
->d_name
.len
= target
->d_name
.len
;
1780 swap(dentry
->d_name
.len
, target
->d_name
.len
);
1784 * We cannibalize "target" when moving dentry on top of it,
1785 * because it's going to be thrown away anyway. We could be more
1786 * polite about it, though.
1788 * This forceful removal will result in ugly /proc output if
1789 * somebody holds a file open that got deleted due to a rename.
1790 * We could be nicer about the deleted file, and let it show
1791 * up under the name it had before it was deleted rather than
1792 * under the original name of the file that was moved on top of it.
1796 * d_move_locked - move a dentry
1797 * @dentry: entry to move
1798 * @target: new dentry
1800 * Update the dcache to reflect the move of a file name. Negative
1801 * dcache entries should not be moved in this way.
1803 static void d_move_locked(struct dentry
* dentry
, struct dentry
* target
)
1805 if (!dentry
->d_inode
)
1806 printk(KERN_WARNING
"VFS: moving negative dcache entry\n");
1808 write_seqlock(&rename_lock
);
1810 * XXXX: do we really need to take target->d_lock?
1812 if (target
< dentry
) {
1813 spin_lock(&target
->d_lock
);
1814 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
1816 spin_lock(&dentry
->d_lock
);
1817 spin_lock_nested(&target
->d_lock
, DENTRY_D_LOCK_NESTED
);
1820 /* Move the dentry to the target hash queue, if on different bucket */
1821 spin_lock(&dcache_hash_lock
);
1822 if (!d_unhashed(dentry
))
1823 hlist_del_rcu(&dentry
->d_hash
);
1824 __d_rehash(dentry
, d_hash(target
->d_parent
, target
->d_name
.hash
));
1825 spin_unlock(&dcache_hash_lock
);
1827 /* Unhash the target: dput() will then get rid of it */
1830 list_del(&dentry
->d_u
.d_child
);
1831 list_del(&target
->d_u
.d_child
);
1833 /* Switch the names.. */
1834 switch_names(dentry
, target
);
1835 swap(dentry
->d_name
.hash
, target
->d_name
.hash
);
1837 /* ... and switch the parents */
1838 if (IS_ROOT(dentry
)) {
1839 dentry
->d_parent
= target
->d_parent
;
1840 target
->d_parent
= target
;
1841 INIT_LIST_HEAD(&target
->d_u
.d_child
);
1843 swap(dentry
->d_parent
, target
->d_parent
);
1845 /* And add them back to the (new) parent lists */
1846 list_add(&target
->d_u
.d_child
, &target
->d_parent
->d_subdirs
);
1849 list_add(&dentry
->d_u
.d_child
, &dentry
->d_parent
->d_subdirs
);
1850 spin_unlock(&target
->d_lock
);
1851 fsnotify_d_move(dentry
);
1852 spin_unlock(&dentry
->d_lock
);
1853 write_sequnlock(&rename_lock
);
1857 * d_move - move a dentry
1858 * @dentry: entry to move
1859 * @target: new dentry
1861 * Update the dcache to reflect the move of a file name. Negative
1862 * dcache entries should not be moved in this way.
1865 void d_move(struct dentry
* dentry
, struct dentry
* target
)
1867 spin_lock(&dcache_lock
);
1868 d_move_locked(dentry
, target
);
1869 spin_unlock(&dcache_lock
);
1871 EXPORT_SYMBOL(d_move
);
1874 * d_ancestor - search for an ancestor
1875 * @p1: ancestor dentry
1878 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
1879 * an ancestor of p2, else NULL.
1881 struct dentry
*d_ancestor(struct dentry
*p1
, struct dentry
*p2
)
1885 for (p
= p2
; !IS_ROOT(p
); p
= p
->d_parent
) {
1886 if (p
->d_parent
== p1
)
1893 * This helper attempts to cope with remotely renamed directories
1895 * It assumes that the caller is already holding
1896 * dentry->d_parent->d_inode->i_mutex and the dcache_lock
1898 * Note: If ever the locking in lock_rename() changes, then please
1899 * remember to update this too...
1901 static struct dentry
*__d_unalias(struct dentry
*dentry
, struct dentry
*alias
)
1902 __releases(dcache_lock
)
1904 struct mutex
*m1
= NULL
, *m2
= NULL
;
1907 /* If alias and dentry share a parent, then no extra locks required */
1908 if (alias
->d_parent
== dentry
->d_parent
)
1911 /* Check for loops */
1912 ret
= ERR_PTR(-ELOOP
);
1913 if (d_ancestor(alias
, dentry
))
1916 /* See lock_rename() */
1917 ret
= ERR_PTR(-EBUSY
);
1918 if (!mutex_trylock(&dentry
->d_sb
->s_vfs_rename_mutex
))
1920 m1
= &dentry
->d_sb
->s_vfs_rename_mutex
;
1921 if (!mutex_trylock(&alias
->d_parent
->d_inode
->i_mutex
))
1923 m2
= &alias
->d_parent
->d_inode
->i_mutex
;
1925 d_move_locked(alias
, dentry
);
1928 spin_unlock(&dcache_lock
);
1937 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
1938 * named dentry in place of the dentry to be replaced.
1940 static void __d_materialise_dentry(struct dentry
*dentry
, struct dentry
*anon
)
1942 struct dentry
*dparent
, *aparent
;
1944 switch_names(dentry
, anon
);
1945 swap(dentry
->d_name
.hash
, anon
->d_name
.hash
);
1947 dparent
= dentry
->d_parent
;
1948 aparent
= anon
->d_parent
;
1950 dentry
->d_parent
= (aparent
== anon
) ? dentry
: aparent
;
1951 list_del(&dentry
->d_u
.d_child
);
1952 if (!IS_ROOT(dentry
))
1953 list_add(&dentry
->d_u
.d_child
, &dentry
->d_parent
->d_subdirs
);
1955 INIT_LIST_HEAD(&dentry
->d_u
.d_child
);
1957 anon
->d_parent
= (dparent
== dentry
) ? anon
: dparent
;
1958 list_del(&anon
->d_u
.d_child
);
1960 list_add(&anon
->d_u
.d_child
, &anon
->d_parent
->d_subdirs
);
1962 INIT_LIST_HEAD(&anon
->d_u
.d_child
);
1964 anon
->d_flags
&= ~DCACHE_DISCONNECTED
;
1968 * d_materialise_unique - introduce an inode into the tree
1969 * @dentry: candidate dentry
1970 * @inode: inode to bind to the dentry, to which aliases may be attached
1972 * Introduces an dentry into the tree, substituting an extant disconnected
1973 * root directory alias in its place if there is one
1975 struct dentry
*d_materialise_unique(struct dentry
*dentry
, struct inode
*inode
)
1977 struct dentry
*actual
;
1979 BUG_ON(!d_unhashed(dentry
));
1981 spin_lock(&dcache_lock
);
1985 __d_instantiate(dentry
, NULL
);
1989 if (S_ISDIR(inode
->i_mode
)) {
1990 struct dentry
*alias
;
1992 /* Does an aliased dentry already exist? */
1993 alias
= __d_find_alias(inode
, 0);
1996 /* Is this an anonymous mountpoint that we could splice
1998 if (IS_ROOT(alias
)) {
1999 spin_lock(&alias
->d_lock
);
2000 __d_materialise_dentry(dentry
, alias
);
2004 /* Nope, but we must(!) avoid directory aliasing */
2005 actual
= __d_unalias(dentry
, alias
);
2012 /* Add a unique reference */
2013 actual
= __d_instantiate_unique(dentry
, inode
);
2016 else if (unlikely(!d_unhashed(actual
)))
2017 goto shouldnt_be_hashed
;
2020 spin_lock(&actual
->d_lock
);
2022 spin_lock(&dcache_hash_lock
);
2024 spin_unlock(&dcache_hash_lock
);
2025 spin_unlock(&actual
->d_lock
);
2026 spin_unlock(&dcache_lock
);
2028 if (actual
== dentry
) {
2029 security_d_instantiate(dentry
, inode
);
2037 spin_unlock(&dcache_lock
);
2040 EXPORT_SYMBOL_GPL(d_materialise_unique
);
2042 static int prepend(char **buffer
, int *buflen
, const char *str
, int namelen
)
2046 return -ENAMETOOLONG
;
2048 memcpy(*buffer
, str
, namelen
);
2052 static int prepend_name(char **buffer
, int *buflen
, struct qstr
*name
)
2054 return prepend(buffer
, buflen
, name
->name
, name
->len
);
2058 * Prepend path string to a buffer
2060 * @path: the dentry/vfsmount to report
2061 * @root: root vfsmnt/dentry (may be modified by this function)
2062 * @buffer: pointer to the end of the buffer
2063 * @buflen: pointer to buffer length
2065 * Caller holds the dcache_lock.
2067 * If path is not reachable from the supplied root, then the value of
2068 * root is changed (without modifying refcounts).
2070 static int prepend_path(const struct path
*path
, struct path
*root
,
2071 char **buffer
, int *buflen
)
2073 struct dentry
*dentry
= path
->dentry
;
2074 struct vfsmount
*vfsmnt
= path
->mnt
;
2078 br_read_lock(vfsmount_lock
);
2079 while (dentry
!= root
->dentry
|| vfsmnt
!= root
->mnt
) {
2080 struct dentry
* parent
;
2082 if (dentry
== vfsmnt
->mnt_root
|| IS_ROOT(dentry
)) {
2084 if (vfsmnt
->mnt_parent
== vfsmnt
) {
2087 dentry
= vfsmnt
->mnt_mountpoint
;
2088 vfsmnt
= vfsmnt
->mnt_parent
;
2091 parent
= dentry
->d_parent
;
2093 error
= prepend_name(buffer
, buflen
, &dentry
->d_name
);
2095 error
= prepend(buffer
, buflen
, "/", 1);
2104 if (!error
&& !slash
)
2105 error
= prepend(buffer
, buflen
, "/", 1);
2107 br_read_unlock(vfsmount_lock
);
2112 * Filesystems needing to implement special "root names"
2113 * should do so with ->d_dname()
2115 if (IS_ROOT(dentry
) &&
2116 (dentry
->d_name
.len
!= 1 || dentry
->d_name
.name
[0] != '/')) {
2117 WARN(1, "Root dentry has weird name <%.*s>\n",
2118 (int) dentry
->d_name
.len
, dentry
->d_name
.name
);
2121 root
->dentry
= dentry
;
2126 * __d_path - return the path of a dentry
2127 * @path: the dentry/vfsmount to report
2128 * @root: root vfsmnt/dentry (may be modified by this function)
2129 * @buf: buffer to return value in
2130 * @buflen: buffer length
2132 * Convert a dentry into an ASCII path name.
2134 * Returns a pointer into the buffer or an error code if the
2135 * path was too long.
2137 * "buflen" should be positive.
2139 * If path is not reachable from the supplied root, then the value of
2140 * root is changed (without modifying refcounts).
2142 char *__d_path(const struct path
*path
, struct path
*root
,
2143 char *buf
, int buflen
)
2145 char *res
= buf
+ buflen
;
2148 prepend(&res
, &buflen
, "\0", 1);
2149 spin_lock(&dcache_lock
);
2150 error
= prepend_path(path
, root
, &res
, &buflen
);
2151 spin_unlock(&dcache_lock
);
2154 return ERR_PTR(error
);
2159 * same as __d_path but appends "(deleted)" for unlinked files.
2161 static int path_with_deleted(const struct path
*path
, struct path
*root
,
2162 char **buf
, int *buflen
)
2164 prepend(buf
, buflen
, "\0", 1);
2165 if (d_unlinked(path
->dentry
)) {
2166 int error
= prepend(buf
, buflen
, " (deleted)", 10);
2171 return prepend_path(path
, root
, buf
, buflen
);
2174 static int prepend_unreachable(char **buffer
, int *buflen
)
2176 return prepend(buffer
, buflen
, "(unreachable)", 13);
2180 * d_path - return the path of a dentry
2181 * @path: path to report
2182 * @buf: buffer to return value in
2183 * @buflen: buffer length
2185 * Convert a dentry into an ASCII path name. If the entry has been deleted
2186 * the string " (deleted)" is appended. Note that this is ambiguous.
2188 * Returns a pointer into the buffer or an error code if the path was
2189 * too long. Note: Callers should use the returned pointer, not the passed
2190 * in buffer, to use the name! The implementation often starts at an offset
2191 * into the buffer, and may leave 0 bytes at the start.
2193 * "buflen" should be positive.
2195 char *d_path(const struct path
*path
, char *buf
, int buflen
)
2197 char *res
= buf
+ buflen
;
2203 * We have various synthetic filesystems that never get mounted. On
2204 * these filesystems dentries are never used for lookup purposes, and
2205 * thus don't need to be hashed. They also don't need a name until a
2206 * user wants to identify the object in /proc/pid/fd/. The little hack
2207 * below allows us to generate a name for these objects on demand:
2209 if (path
->dentry
->d_op
&& path
->dentry
->d_op
->d_dname
)
2210 return path
->dentry
->d_op
->d_dname(path
->dentry
, buf
, buflen
);
2212 get_fs_root(current
->fs
, &root
);
2213 spin_lock(&dcache_lock
);
2215 error
= path_with_deleted(path
, &tmp
, &res
, &buflen
);
2217 res
= ERR_PTR(error
);
2218 spin_unlock(&dcache_lock
);
2222 EXPORT_SYMBOL(d_path
);
2225 * d_path_with_unreachable - return the path of a dentry
2226 * @path: path to report
2227 * @buf: buffer to return value in
2228 * @buflen: buffer length
2230 * The difference from d_path() is that this prepends "(unreachable)"
2231 * to paths which are unreachable from the current process' root.
2233 char *d_path_with_unreachable(const struct path
*path
, char *buf
, int buflen
)
2235 char *res
= buf
+ buflen
;
2240 if (path
->dentry
->d_op
&& path
->dentry
->d_op
->d_dname
)
2241 return path
->dentry
->d_op
->d_dname(path
->dentry
, buf
, buflen
);
2243 get_fs_root(current
->fs
, &root
);
2244 spin_lock(&dcache_lock
);
2246 error
= path_with_deleted(path
, &tmp
, &res
, &buflen
);
2247 if (!error
&& !path_equal(&tmp
, &root
))
2248 error
= prepend_unreachable(&res
, &buflen
);
2249 spin_unlock(&dcache_lock
);
2252 res
= ERR_PTR(error
);
2258 * Helper function for dentry_operations.d_dname() members
2260 char *dynamic_dname(struct dentry
*dentry
, char *buffer
, int buflen
,
2261 const char *fmt
, ...)
2267 va_start(args
, fmt
);
2268 sz
= vsnprintf(temp
, sizeof(temp
), fmt
, args
) + 1;
2271 if (sz
> sizeof(temp
) || sz
> buflen
)
2272 return ERR_PTR(-ENAMETOOLONG
);
2274 buffer
+= buflen
- sz
;
2275 return memcpy(buffer
, temp
, sz
);
2279 * Write full pathname from the root of the filesystem into the buffer.
2281 static char *__dentry_path(struct dentry
*dentry
, char *buf
, int buflen
)
2283 char *end
= buf
+ buflen
;
2286 prepend(&end
, &buflen
, "\0", 1);
2293 while (!IS_ROOT(dentry
)) {
2294 struct dentry
*parent
= dentry
->d_parent
;
2297 if ((prepend_name(&end
, &buflen
, &dentry
->d_name
) != 0) ||
2298 (prepend(&end
, &buflen
, "/", 1) != 0))
2306 return ERR_PTR(-ENAMETOOLONG
);
2309 char *dentry_path_raw(struct dentry
*dentry
, char *buf
, int buflen
)
2313 spin_lock(&dcache_lock
);
2314 retval
= __dentry_path(dentry
, buf
, buflen
);
2315 spin_unlock(&dcache_lock
);
2319 EXPORT_SYMBOL(dentry_path_raw
);
2321 char *dentry_path(struct dentry
*dentry
, char *buf
, int buflen
)
2326 spin_lock(&dcache_lock
);
2327 if (d_unlinked(dentry
)) {
2329 if (prepend(&p
, &buflen
, "//deleted", 10) != 0)
2333 retval
= __dentry_path(dentry
, buf
, buflen
);
2334 spin_unlock(&dcache_lock
);
2335 if (!IS_ERR(retval
) && p
)
2336 *p
= '/'; /* restore '/' overriden with '\0' */
2339 spin_unlock(&dcache_lock
);
2340 return ERR_PTR(-ENAMETOOLONG
);
2344 * NOTE! The user-level library version returns a
2345 * character pointer. The kernel system call just
2346 * returns the length of the buffer filled (which
2347 * includes the ending '\0' character), or a negative
2348 * error value. So libc would do something like
2350 * char *getcwd(char * buf, size_t size)
2354 * retval = sys_getcwd(buf, size);
2361 SYSCALL_DEFINE2(getcwd
, char __user
*, buf
, unsigned long, size
)
2364 struct path pwd
, root
;
2365 char *page
= (char *) __get_free_page(GFP_USER
);
2370 get_fs_root_and_pwd(current
->fs
, &root
, &pwd
);
2373 spin_lock(&dcache_lock
);
2374 if (!d_unlinked(pwd
.dentry
)) {
2376 struct path tmp
= root
;
2377 char *cwd
= page
+ PAGE_SIZE
;
2378 int buflen
= PAGE_SIZE
;
2380 prepend(&cwd
, &buflen
, "\0", 1);
2381 error
= prepend_path(&pwd
, &tmp
, &cwd
, &buflen
);
2382 spin_unlock(&dcache_lock
);
2387 /* Unreachable from current root */
2388 if (!path_equal(&tmp
, &root
)) {
2389 error
= prepend_unreachable(&cwd
, &buflen
);
2395 len
= PAGE_SIZE
+ page
- cwd
;
2398 if (copy_to_user(buf
, cwd
, len
))
2402 spin_unlock(&dcache_lock
);
2407 free_page((unsigned long) page
);
2412 * Test whether new_dentry is a subdirectory of old_dentry.
2414 * Trivially implemented using the dcache structure
2418 * is_subdir - is new dentry a subdirectory of old_dentry
2419 * @new_dentry: new dentry
2420 * @old_dentry: old dentry
2422 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
2423 * Returns 0 otherwise.
2424 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
2427 int is_subdir(struct dentry
*new_dentry
, struct dentry
*old_dentry
)
2432 if (new_dentry
== old_dentry
)
2436 * Need rcu_readlock to protect against the d_parent trashing
2441 /* for restarting inner loop in case of seq retry */
2442 seq
= read_seqbegin(&rename_lock
);
2443 if (d_ancestor(old_dentry
, new_dentry
))
2447 } while (read_seqretry(&rename_lock
, seq
));
2453 int path_is_under(struct path
*path1
, struct path
*path2
)
2455 struct vfsmount
*mnt
= path1
->mnt
;
2456 struct dentry
*dentry
= path1
->dentry
;
2459 br_read_lock(vfsmount_lock
);
2460 if (mnt
!= path2
->mnt
) {
2462 if (mnt
->mnt_parent
== mnt
) {
2463 br_read_unlock(vfsmount_lock
);
2466 if (mnt
->mnt_parent
== path2
->mnt
)
2468 mnt
= mnt
->mnt_parent
;
2470 dentry
= mnt
->mnt_mountpoint
;
2472 res
= is_subdir(dentry
, path2
->dentry
);
2473 br_read_unlock(vfsmount_lock
);
2476 EXPORT_SYMBOL(path_is_under
);
2478 void d_genocide(struct dentry
*root
)
2480 struct dentry
*this_parent
= root
;
2481 struct list_head
*next
;
2483 spin_lock(&dcache_lock
);
2485 next
= this_parent
->d_subdirs
.next
;
2487 while (next
!= &this_parent
->d_subdirs
) {
2488 struct list_head
*tmp
= next
;
2489 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
2491 if (d_unhashed(dentry
)||!dentry
->d_inode
)
2493 if (!list_empty(&dentry
->d_subdirs
)) {
2494 this_parent
= dentry
;
2497 atomic_dec(&dentry
->d_count
);
2499 if (this_parent
!= root
) {
2500 next
= this_parent
->d_u
.d_child
.next
;
2501 atomic_dec(&this_parent
->d_count
);
2502 this_parent
= this_parent
->d_parent
;
2505 spin_unlock(&dcache_lock
);
2509 * find_inode_number - check for dentry with name
2510 * @dir: directory to check
2511 * @name: Name to find.
2513 * Check whether a dentry already exists for the given name,
2514 * and return the inode number if it has an inode. Otherwise
2517 * This routine is used to post-process directory listings for
2518 * filesystems using synthetic inode numbers, and is necessary
2519 * to keep getcwd() working.
2522 ino_t
find_inode_number(struct dentry
*dir
, struct qstr
*name
)
2524 struct dentry
* dentry
;
2527 dentry
= d_hash_and_lookup(dir
, name
);
2529 if (dentry
->d_inode
)
2530 ino
= dentry
->d_inode
->i_ino
;
2535 EXPORT_SYMBOL(find_inode_number
);
2537 static __initdata
unsigned long dhash_entries
;
2538 static int __init
set_dhash_entries(char *str
)
2542 dhash_entries
= simple_strtoul(str
, &str
, 0);
2545 __setup("dhash_entries=", set_dhash_entries
);
2547 static void __init
dcache_init_early(void)
2551 /* If hashes are distributed across NUMA nodes, defer
2552 * hash allocation until vmalloc space is available.
2558 alloc_large_system_hash("Dentry cache",
2559 sizeof(struct hlist_head
),
2567 for (loop
= 0; loop
< (1 << d_hash_shift
); loop
++)
2568 INIT_HLIST_HEAD(&dentry_hashtable
[loop
]);
2571 static void __init
dcache_init(void)
2576 * A constructor could be added for stable state like the lists,
2577 * but it is probably not worth it because of the cache nature
2580 dentry_cache
= KMEM_CACHE(dentry
,
2581 SLAB_RECLAIM_ACCOUNT
|SLAB_PANIC
|SLAB_MEM_SPREAD
);
2583 register_shrinker(&dcache_shrinker
);
2585 /* Hash may have been set up in dcache_init_early */
2590 alloc_large_system_hash("Dentry cache",
2591 sizeof(struct hlist_head
),
2599 for (loop
= 0; loop
< (1 << d_hash_shift
); loop
++)
2600 INIT_HLIST_HEAD(&dentry_hashtable
[loop
]);
2603 /* SLAB cache for __getname() consumers */
2604 struct kmem_cache
*names_cachep __read_mostly
;
2605 EXPORT_SYMBOL(names_cachep
);
2607 EXPORT_SYMBOL(d_genocide
);
2609 void __init
vfs_caches_init_early(void)
2611 dcache_init_early();
2615 void __init
vfs_caches_init(unsigned long mempages
)
2617 unsigned long reserve
;
2619 /* Base hash sizes on available memory, with a reserve equal to
2620 150% of current kernel size */
2622 reserve
= min((mempages
- nr_free_pages()) * 3/2, mempages
- 1);
2623 mempages
-= reserve
;
2625 names_cachep
= kmem_cache_create("names_cache", PATH_MAX
, 0,
2626 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
2630 files_init(mempages
);