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/config.h>
18 #include <linux/syscalls.h>
19 #include <linux/string.h>
22 #include <linux/fsnotify.h>
23 #include <linux/slab.h>
24 #include <linux/init.h>
25 #include <linux/smp_lock.h>
26 #include <linux/hash.h>
27 #include <linux/cache.h>
28 #include <linux/module.h>
29 #include <linux/mount.h>
30 #include <linux/file.h>
31 #include <asm/uaccess.h>
32 #include <linux/security.h>
33 #include <linux/seqlock.h>
34 #include <linux/swap.h>
35 #include <linux/bootmem.h>
38 int sysctl_vfs_cache_pressure __read_mostly
= 100;
39 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure
);
41 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(dcache_lock
);
42 static seqlock_t rename_lock __cacheline_aligned_in_smp
= SEQLOCK_UNLOCKED
;
44 EXPORT_SYMBOL(dcache_lock
);
46 static kmem_cache_t
*dentry_cache __read_mostly
;
48 #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname))
51 * This is the single most critical data structure when it comes
52 * to the dcache: the hashtable for lookups. Somebody should try
53 * to make this good - I've just made it work.
55 * This hash-function tries to avoid losing too many bits of hash
56 * information, yet avoid using a prime hash-size or similar.
58 #define D_HASHBITS d_hash_shift
59 #define D_HASHMASK d_hash_mask
61 static unsigned int d_hash_mask __read_mostly
;
62 static unsigned int d_hash_shift __read_mostly
;
63 static struct hlist_head
*dentry_hashtable __read_mostly
;
64 static LIST_HEAD(dentry_unused
);
66 /* Statistics gathering. */
67 struct dentry_stat_t dentry_stat
= {
71 static void d_callback(struct rcu_head
*head
)
73 struct dentry
* dentry
= container_of(head
, struct dentry
, d_u
.d_rcu
);
75 if (dname_external(dentry
))
76 kfree(dentry
->d_name
.name
);
77 kmem_cache_free(dentry_cache
, dentry
);
81 * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry
84 static void d_free(struct dentry
*dentry
)
86 if (dentry
->d_op
&& dentry
->d_op
->d_release
)
87 dentry
->d_op
->d_release(dentry
);
88 call_rcu(&dentry
->d_u
.d_rcu
, d_callback
);
92 * Release the dentry's inode, using the filesystem
93 * d_iput() operation if defined.
94 * Called with dcache_lock and per dentry lock held, drops both.
96 static void dentry_iput(struct dentry
* dentry
)
98 struct inode
*inode
= dentry
->d_inode
;
100 dentry
->d_inode
= NULL
;
101 list_del_init(&dentry
->d_alias
);
102 spin_unlock(&dentry
->d_lock
);
103 spin_unlock(&dcache_lock
);
105 fsnotify_inoderemove(inode
);
106 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
107 dentry
->d_op
->d_iput(dentry
, inode
);
111 spin_unlock(&dentry
->d_lock
);
112 spin_unlock(&dcache_lock
);
119 * This is complicated by the fact that we do not want to put
120 * dentries that are no longer on any hash chain on the unused
121 * list: we'd much rather just get rid of them immediately.
123 * However, that implies that we have to traverse the dentry
124 * tree upwards to the parents which might _also_ now be
125 * scheduled for deletion (it may have been only waiting for
126 * its last child to go away).
128 * This tail recursion is done by hand as we don't want to depend
129 * on the compiler to always get this right (gcc generally doesn't).
130 * Real recursion would eat up our stack space.
134 * dput - release a dentry
135 * @dentry: dentry to release
137 * Release a dentry. This will drop the usage count and if appropriate
138 * call the dentry unlink method as well as removing it from the queues and
139 * releasing its resources. If the parent dentries were scheduled for release
140 * they too may now get deleted.
142 * no dcache lock, please.
145 void dput(struct dentry
*dentry
)
151 if (atomic_read(&dentry
->d_count
) == 1)
153 if (!atomic_dec_and_lock(&dentry
->d_count
, &dcache_lock
))
156 spin_lock(&dentry
->d_lock
);
157 if (atomic_read(&dentry
->d_count
)) {
158 spin_unlock(&dentry
->d_lock
);
159 spin_unlock(&dcache_lock
);
164 * AV: ->d_delete() is _NOT_ allowed to block now.
166 if (dentry
->d_op
&& dentry
->d_op
->d_delete
) {
167 if (dentry
->d_op
->d_delete(dentry
))
170 /* Unreachable? Get rid of it */
171 if (d_unhashed(dentry
))
173 if (list_empty(&dentry
->d_lru
)) {
174 dentry
->d_flags
|= DCACHE_REFERENCED
;
175 list_add(&dentry
->d_lru
, &dentry_unused
);
176 dentry_stat
.nr_unused
++;
178 spin_unlock(&dentry
->d_lock
);
179 spin_unlock(&dcache_lock
);
186 struct dentry
*parent
;
188 /* If dentry was on d_lru list
189 * delete it from there
191 if (!list_empty(&dentry
->d_lru
)) {
192 list_del(&dentry
->d_lru
);
193 dentry_stat
.nr_unused
--;
195 list_del(&dentry
->d_u
.d_child
);
196 dentry_stat
.nr_dentry
--; /* For d_free, below */
197 /*drops the locks, at that point nobody can reach this dentry */
199 parent
= dentry
->d_parent
;
201 if (dentry
== parent
)
209 * d_invalidate - invalidate a dentry
210 * @dentry: dentry to invalidate
212 * Try to invalidate the dentry if it turns out to be
213 * possible. If there are other dentries that can be
214 * reached through this one we can't delete it and we
215 * return -EBUSY. On success we return 0.
220 int d_invalidate(struct dentry
* dentry
)
223 * If it's already been dropped, return OK.
225 spin_lock(&dcache_lock
);
226 if (d_unhashed(dentry
)) {
227 spin_unlock(&dcache_lock
);
231 * Check whether to do a partial shrink_dcache
232 * to get rid of unused child entries.
234 if (!list_empty(&dentry
->d_subdirs
)) {
235 spin_unlock(&dcache_lock
);
236 shrink_dcache_parent(dentry
);
237 spin_lock(&dcache_lock
);
241 * Somebody else still using it?
243 * If it's a directory, we can't drop it
244 * for fear of somebody re-populating it
245 * with children (even though dropping it
246 * would make it unreachable from the root,
247 * we might still populate it if it was a
248 * working directory or similar).
250 spin_lock(&dentry
->d_lock
);
251 if (atomic_read(&dentry
->d_count
) > 1) {
252 if (dentry
->d_inode
&& S_ISDIR(dentry
->d_inode
->i_mode
)) {
253 spin_unlock(&dentry
->d_lock
);
254 spin_unlock(&dcache_lock
);
260 spin_unlock(&dentry
->d_lock
);
261 spin_unlock(&dcache_lock
);
265 /* This should be called _only_ with dcache_lock held */
267 static inline struct dentry
* __dget_locked(struct dentry
*dentry
)
269 atomic_inc(&dentry
->d_count
);
270 if (!list_empty(&dentry
->d_lru
)) {
271 dentry_stat
.nr_unused
--;
272 list_del_init(&dentry
->d_lru
);
277 struct dentry
* dget_locked(struct dentry
*dentry
)
279 return __dget_locked(dentry
);
283 * d_find_alias - grab a hashed alias of inode
284 * @inode: inode in question
285 * @want_discon: flag, used by d_splice_alias, to request
286 * that only a DISCONNECTED alias be returned.
288 * If inode has a hashed alias, or is a directory and has any alias,
289 * acquire the reference to alias and return it. Otherwise return NULL.
290 * Notice that if inode is a directory there can be only one alias and
291 * it can be unhashed only if it has no children, or if it is the root
294 * If the inode has a DCACHE_DISCONNECTED alias, then prefer
295 * any other hashed alias over that one unless @want_discon is set,
296 * in which case only return a DCACHE_DISCONNECTED alias.
299 static struct dentry
* __d_find_alias(struct inode
*inode
, int want_discon
)
301 struct list_head
*head
, *next
, *tmp
;
302 struct dentry
*alias
, *discon_alias
=NULL
;
304 head
= &inode
->i_dentry
;
305 next
= inode
->i_dentry
.next
;
306 while (next
!= head
) {
310 alias
= list_entry(tmp
, struct dentry
, d_alias
);
311 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
312 if (alias
->d_flags
& DCACHE_DISCONNECTED
)
313 discon_alias
= alias
;
314 else if (!want_discon
) {
315 __dget_locked(alias
);
321 __dget_locked(discon_alias
);
325 struct dentry
* d_find_alias(struct inode
*inode
)
327 struct dentry
*de
= NULL
;
329 if (!list_empty(&inode
->i_dentry
)) {
330 spin_lock(&dcache_lock
);
331 de
= __d_find_alias(inode
, 0);
332 spin_unlock(&dcache_lock
);
338 * Try to kill dentries associated with this inode.
339 * WARNING: you must own a reference to inode.
341 void d_prune_aliases(struct inode
*inode
)
343 struct dentry
*dentry
;
345 spin_lock(&dcache_lock
);
346 list_for_each_entry(dentry
, &inode
->i_dentry
, d_alias
) {
347 spin_lock(&dentry
->d_lock
);
348 if (!atomic_read(&dentry
->d_count
)) {
349 __dget_locked(dentry
);
351 spin_unlock(&dentry
->d_lock
);
352 spin_unlock(&dcache_lock
);
356 spin_unlock(&dentry
->d_lock
);
358 spin_unlock(&dcache_lock
);
362 * Throw away a dentry - free the inode, dput the parent. This requires that
363 * the LRU list has already been removed.
365 * Called with dcache_lock, drops it and then regains.
366 * Called with dentry->d_lock held, drops it.
368 static void prune_one_dentry(struct dentry
* dentry
)
370 struct dentry
* parent
;
373 list_del(&dentry
->d_u
.d_child
);
374 dentry_stat
.nr_dentry
--; /* For d_free, below */
376 parent
= dentry
->d_parent
;
378 if (parent
!= dentry
)
380 spin_lock(&dcache_lock
);
384 * prune_dcache - shrink the dcache
385 * @count: number of entries to try and free
386 * @sb: if given, ignore dentries for other superblocks
387 * which are being unmounted.
389 * Shrink the dcache. This is done when we need
390 * more memory, or simply when we need to unmount
391 * something (at which point we need to unuse
394 * This function may fail to free any resources if
395 * all the dentries are in use.
398 static void prune_dcache(int count
, struct super_block
*sb
)
400 spin_lock(&dcache_lock
);
401 for (; count
; count
--) {
402 struct dentry
*dentry
;
403 struct list_head
*tmp
;
404 struct rw_semaphore
*s_umount
;
406 cond_resched_lock(&dcache_lock
);
408 tmp
= dentry_unused
.prev
;
410 /* Try to find a dentry for this sb, but don't try
411 * too hard, if they aren't near the tail they will
412 * be moved down again soon
415 while (skip
&& tmp
!= &dentry_unused
&&
416 list_entry(tmp
, struct dentry
, d_lru
)->d_sb
!= sb
) {
421 if (tmp
== &dentry_unused
)
424 prefetch(dentry_unused
.prev
);
425 dentry_stat
.nr_unused
--;
426 dentry
= list_entry(tmp
, struct dentry
, d_lru
);
428 spin_lock(&dentry
->d_lock
);
430 * We found an inuse dentry which was not removed from
431 * dentry_unused because of laziness during lookup. Do not free
432 * it - just keep it off the dentry_unused list.
434 if (atomic_read(&dentry
->d_count
)) {
435 spin_unlock(&dentry
->d_lock
);
438 /* If the dentry was recently referenced, don't free it. */
439 if (dentry
->d_flags
& DCACHE_REFERENCED
) {
440 dentry
->d_flags
&= ~DCACHE_REFERENCED
;
441 list_add(&dentry
->d_lru
, &dentry_unused
);
442 dentry_stat
.nr_unused
++;
443 spin_unlock(&dentry
->d_lock
);
447 * If the dentry is not DCACHED_REFERENCED, it is time
448 * to remove it from the dcache, provided the super block is
449 * NULL (which means we are trying to reclaim memory)
450 * or this dentry belongs to the same super block that
454 * If this dentry is for "my" filesystem, then I can prune it
455 * without taking the s_umount lock (I already hold it).
457 if (sb
&& dentry
->d_sb
== sb
) {
458 prune_one_dentry(dentry
);
462 * ...otherwise we need to be sure this filesystem isn't being
463 * unmounted, otherwise we could race with
464 * generic_shutdown_super(), and end up holding a reference to
465 * an inode while the filesystem is unmounted.
466 * So we try to get s_umount, and make sure s_root isn't NULL.
467 * (Take a local copy of s_umount to avoid a use-after-free of
470 s_umount
= &dentry
->d_sb
->s_umount
;
471 if (down_read_trylock(s_umount
)) {
472 if (dentry
->d_sb
->s_root
!= NULL
) {
473 prune_one_dentry(dentry
);
479 spin_unlock(&dentry
->d_lock
);
480 /* Cannot remove the first dentry, and it isn't appropriate
481 * to move it to the head of the list, so give up, and try
486 spin_unlock(&dcache_lock
);
490 * Shrink the dcache for the specified super block.
491 * This allows us to unmount a device without disturbing
492 * the dcache for the other devices.
494 * This implementation makes just two traversals of the
495 * unused list. On the first pass we move the selected
496 * dentries to the most recent end, and on the second
497 * pass we free them. The second pass must restart after
498 * each dput(), but since the target dentries are all at
499 * the end, it's really just a single traversal.
503 * shrink_dcache_sb - shrink dcache for a superblock
506 * Shrink the dcache for the specified super block. This
507 * is used to free the dcache before unmounting a file
511 void shrink_dcache_sb(struct super_block
* sb
)
513 struct list_head
*tmp
, *next
;
514 struct dentry
*dentry
;
517 * Pass one ... move the dentries for the specified
518 * superblock to the most recent end of the unused list.
520 spin_lock(&dcache_lock
);
521 list_for_each_safe(tmp
, next
, &dentry_unused
) {
522 dentry
= list_entry(tmp
, struct dentry
, d_lru
);
523 if (dentry
->d_sb
!= sb
)
526 list_add(tmp
, &dentry_unused
);
530 * Pass two ... free the dentries for this superblock.
533 list_for_each_safe(tmp
, next
, &dentry_unused
) {
534 dentry
= list_entry(tmp
, struct dentry
, d_lru
);
535 if (dentry
->d_sb
!= sb
)
537 dentry_stat
.nr_unused
--;
539 spin_lock(&dentry
->d_lock
);
540 if (atomic_read(&dentry
->d_count
)) {
541 spin_unlock(&dentry
->d_lock
);
544 prune_one_dentry(dentry
);
545 cond_resched_lock(&dcache_lock
);
548 spin_unlock(&dcache_lock
);
552 * Search for at least 1 mount point in the dentry's subdirs.
553 * We descend to the next level whenever the d_subdirs
554 * list is non-empty and continue searching.
558 * have_submounts - check for mounts over a dentry
559 * @parent: dentry to check.
561 * Return true if the parent or its subdirectories contain
565 int have_submounts(struct dentry
*parent
)
567 struct dentry
*this_parent
= parent
;
568 struct list_head
*next
;
570 spin_lock(&dcache_lock
);
571 if (d_mountpoint(parent
))
574 next
= this_parent
->d_subdirs
.next
;
576 while (next
!= &this_parent
->d_subdirs
) {
577 struct list_head
*tmp
= next
;
578 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
580 /* Have we found a mount point ? */
581 if (d_mountpoint(dentry
))
583 if (!list_empty(&dentry
->d_subdirs
)) {
584 this_parent
= dentry
;
589 * All done at this level ... ascend and resume the search.
591 if (this_parent
!= parent
) {
592 next
= this_parent
->d_u
.d_child
.next
;
593 this_parent
= this_parent
->d_parent
;
596 spin_unlock(&dcache_lock
);
597 return 0; /* No mount points found in tree */
599 spin_unlock(&dcache_lock
);
604 * Search the dentry child list for the specified parent,
605 * and move any unused dentries to the end of the unused
606 * list for prune_dcache(). We descend to the next level
607 * whenever the d_subdirs list is non-empty and continue
610 * It returns zero iff there are no unused children,
611 * otherwise it returns the number of children moved to
612 * the end of the unused list. This may not be the total
613 * number of unused children, because select_parent can
614 * drop the lock and return early due to latency
617 static int select_parent(struct dentry
* parent
)
619 struct dentry
*this_parent
= parent
;
620 struct list_head
*next
;
623 spin_lock(&dcache_lock
);
625 next
= this_parent
->d_subdirs
.next
;
627 while (next
!= &this_parent
->d_subdirs
) {
628 struct list_head
*tmp
= next
;
629 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
632 if (!list_empty(&dentry
->d_lru
)) {
633 dentry_stat
.nr_unused
--;
634 list_del_init(&dentry
->d_lru
);
637 * move only zero ref count dentries to the end
638 * of the unused list for prune_dcache
640 if (!atomic_read(&dentry
->d_count
)) {
641 list_add(&dentry
->d_lru
, dentry_unused
.prev
);
642 dentry_stat
.nr_unused
++;
647 * We can return to the caller if we have found some (this
648 * ensures forward progress). We'll be coming back to find
651 if (found
&& need_resched())
655 * Descend a level if the d_subdirs list is non-empty.
657 if (!list_empty(&dentry
->d_subdirs
)) {
658 this_parent
= dentry
;
663 * All done at this level ... ascend and resume the search.
665 if (this_parent
!= parent
) {
666 next
= this_parent
->d_u
.d_child
.next
;
667 this_parent
= this_parent
->d_parent
;
671 spin_unlock(&dcache_lock
);
676 * shrink_dcache_parent - prune dcache
677 * @parent: parent of entries to prune
679 * Prune the dcache to remove unused children of the parent dentry.
682 void shrink_dcache_parent(struct dentry
* parent
)
686 while ((found
= select_parent(parent
)) != 0)
687 prune_dcache(found
, parent
->d_sb
);
691 * shrink_dcache_anon - further prune the cache
692 * @head: head of d_hash list of dentries to prune
694 * Prune the dentries that are anonymous
696 * parsing d_hash list does not hlist_for_each_entry_rcu() as it
697 * done under dcache_lock.
700 void shrink_dcache_anon(struct super_block
*sb
)
702 struct hlist_node
*lp
;
703 struct hlist_head
*head
= &sb
->s_anon
;
707 spin_lock(&dcache_lock
);
708 hlist_for_each(lp
, head
) {
709 struct dentry
*this = hlist_entry(lp
, struct dentry
, d_hash
);
710 if (!list_empty(&this->d_lru
)) {
711 dentry_stat
.nr_unused
--;
712 list_del_init(&this->d_lru
);
716 * move only zero ref count dentries to the end
717 * of the unused list for prune_dcache
719 if (!atomic_read(&this->d_count
)) {
720 list_add_tail(&this->d_lru
, &dentry_unused
);
721 dentry_stat
.nr_unused
++;
725 spin_unlock(&dcache_lock
);
726 prune_dcache(found
, sb
);
731 * Scan `nr' dentries and return the number which remain.
733 * We need to avoid reentering the filesystem if the caller is performing a
734 * GFP_NOFS allocation attempt. One example deadlock is:
736 * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache->
737 * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode->
738 * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK.
740 * In this case we return -1 to tell the caller that we baled.
742 static int shrink_dcache_memory(int nr
, gfp_t gfp_mask
)
745 if (!(gfp_mask
& __GFP_FS
))
747 prune_dcache(nr
, NULL
);
749 return (dentry_stat
.nr_unused
/ 100) * sysctl_vfs_cache_pressure
;
753 * d_alloc - allocate a dcache entry
754 * @parent: parent of entry to allocate
755 * @name: qstr of the name
757 * Allocates a dentry. It returns %NULL if there is insufficient memory
758 * available. On a success the dentry is returned. The name passed in is
759 * copied and the copy passed in may be reused after this call.
762 struct dentry
*d_alloc(struct dentry
* parent
, const struct qstr
*name
)
764 struct dentry
*dentry
;
767 dentry
= kmem_cache_alloc(dentry_cache
, GFP_KERNEL
);
771 if (name
->len
> DNAME_INLINE_LEN
-1) {
772 dname
= kmalloc(name
->len
+ 1, GFP_KERNEL
);
774 kmem_cache_free(dentry_cache
, dentry
);
778 dname
= dentry
->d_iname
;
780 dentry
->d_name
.name
= dname
;
782 dentry
->d_name
.len
= name
->len
;
783 dentry
->d_name
.hash
= name
->hash
;
784 memcpy(dname
, name
->name
, name
->len
);
785 dname
[name
->len
] = 0;
787 atomic_set(&dentry
->d_count
, 1);
788 dentry
->d_flags
= DCACHE_UNHASHED
;
789 spin_lock_init(&dentry
->d_lock
);
790 dentry
->d_inode
= NULL
;
791 dentry
->d_parent
= NULL
;
794 dentry
->d_fsdata
= NULL
;
795 dentry
->d_mounted
= 0;
796 #ifdef CONFIG_PROFILING
797 dentry
->d_cookie
= NULL
;
799 INIT_HLIST_NODE(&dentry
->d_hash
);
800 INIT_LIST_HEAD(&dentry
->d_lru
);
801 INIT_LIST_HEAD(&dentry
->d_subdirs
);
802 INIT_LIST_HEAD(&dentry
->d_alias
);
805 dentry
->d_parent
= dget(parent
);
806 dentry
->d_sb
= parent
->d_sb
;
808 INIT_LIST_HEAD(&dentry
->d_u
.d_child
);
811 spin_lock(&dcache_lock
);
813 list_add(&dentry
->d_u
.d_child
, &parent
->d_subdirs
);
814 dentry_stat
.nr_dentry
++;
815 spin_unlock(&dcache_lock
);
820 struct dentry
*d_alloc_name(struct dentry
*parent
, const char *name
)
825 q
.len
= strlen(name
);
826 q
.hash
= full_name_hash(q
.name
, q
.len
);
827 return d_alloc(parent
, &q
);
831 * d_instantiate - fill in inode information for a dentry
832 * @entry: dentry to complete
833 * @inode: inode to attach to this dentry
835 * Fill in inode information in the entry.
837 * This turns negative dentries into productive full members
840 * NOTE! This assumes that the inode count has been incremented
841 * (or otherwise set) by the caller to indicate that it is now
842 * in use by the dcache.
845 void d_instantiate(struct dentry
*entry
, struct inode
* inode
)
847 BUG_ON(!list_empty(&entry
->d_alias
));
848 spin_lock(&dcache_lock
);
850 list_add(&entry
->d_alias
, &inode
->i_dentry
);
851 entry
->d_inode
= inode
;
852 fsnotify_d_instantiate(entry
, inode
);
853 spin_unlock(&dcache_lock
);
854 security_d_instantiate(entry
, inode
);
858 * d_instantiate_unique - instantiate a non-aliased dentry
859 * @entry: dentry to instantiate
860 * @inode: inode to attach to this dentry
862 * Fill in inode information in the entry. On success, it returns NULL.
863 * If an unhashed alias of "entry" already exists, then we return the
864 * aliased dentry instead and drop one reference to inode.
866 * Note that in order to avoid conflicts with rename() etc, the caller
867 * had better be holding the parent directory semaphore.
869 * This also assumes that the inode count has been incremented
870 * (or otherwise set) by the caller to indicate that it is now
871 * in use by the dcache.
873 struct dentry
*d_instantiate_unique(struct dentry
*entry
, struct inode
*inode
)
875 struct dentry
*alias
;
876 int len
= entry
->d_name
.len
;
877 const char *name
= entry
->d_name
.name
;
878 unsigned int hash
= entry
->d_name
.hash
;
880 BUG_ON(!list_empty(&entry
->d_alias
));
881 spin_lock(&dcache_lock
);
884 list_for_each_entry(alias
, &inode
->i_dentry
, d_alias
) {
885 struct qstr
*qstr
= &alias
->d_name
;
887 if (qstr
->hash
!= hash
)
889 if (alias
->d_parent
!= entry
->d_parent
)
891 if (qstr
->len
!= len
)
893 if (memcmp(qstr
->name
, name
, len
))
896 spin_unlock(&dcache_lock
);
897 BUG_ON(!d_unhashed(alias
));
901 list_add(&entry
->d_alias
, &inode
->i_dentry
);
903 entry
->d_inode
= inode
;
904 fsnotify_d_instantiate(entry
, inode
);
905 spin_unlock(&dcache_lock
);
906 security_d_instantiate(entry
, inode
);
909 EXPORT_SYMBOL(d_instantiate_unique
);
912 * d_alloc_root - allocate root dentry
913 * @root_inode: inode to allocate the root for
915 * Allocate a root ("/") dentry for the inode given. The inode is
916 * instantiated and returned. %NULL is returned if there is insufficient
917 * memory or the inode passed is %NULL.
920 struct dentry
* d_alloc_root(struct inode
* root_inode
)
922 struct dentry
*res
= NULL
;
925 static const struct qstr name
= { .name
= "/", .len
= 1 };
927 res
= d_alloc(NULL
, &name
);
929 res
->d_sb
= root_inode
->i_sb
;
931 d_instantiate(res
, root_inode
);
937 static inline struct hlist_head
*d_hash(struct dentry
*parent
,
940 hash
+= ((unsigned long) parent
^ GOLDEN_RATIO_PRIME
) / L1_CACHE_BYTES
;
941 hash
= hash
^ ((hash
^ GOLDEN_RATIO_PRIME
) >> D_HASHBITS
);
942 return dentry_hashtable
+ (hash
& D_HASHMASK
);
946 * d_alloc_anon - allocate an anonymous dentry
947 * @inode: inode to allocate the dentry for
949 * This is similar to d_alloc_root. It is used by filesystems when
950 * creating a dentry for a given inode, often in the process of
951 * mapping a filehandle to a dentry. The returned dentry may be
952 * anonymous, or may have a full name (if the inode was already
953 * in the cache). The file system may need to make further
954 * efforts to connect this dentry into the dcache properly.
956 * When called on a directory inode, we must ensure that
957 * the inode only ever has one dentry. If a dentry is
958 * found, that is returned instead of allocating a new one.
960 * On successful return, the reference to the inode has been transferred
961 * to the dentry. If %NULL is returned (indicating kmalloc failure),
962 * the reference on the inode has not been released.
965 struct dentry
* d_alloc_anon(struct inode
*inode
)
967 static const struct qstr anonstring
= { .name
= "" };
971 if ((res
= d_find_alias(inode
))) {
976 tmp
= d_alloc(NULL
, &anonstring
);
980 tmp
->d_parent
= tmp
; /* make sure dput doesn't croak */
982 spin_lock(&dcache_lock
);
983 res
= __d_find_alias(inode
, 0);
985 /* attach a disconnected dentry */
988 spin_lock(&res
->d_lock
);
989 res
->d_sb
= inode
->i_sb
;
991 res
->d_inode
= inode
;
992 res
->d_flags
|= DCACHE_DISCONNECTED
;
993 res
->d_flags
&= ~DCACHE_UNHASHED
;
994 list_add(&res
->d_alias
, &inode
->i_dentry
);
995 hlist_add_head(&res
->d_hash
, &inode
->i_sb
->s_anon
);
996 spin_unlock(&res
->d_lock
);
998 inode
= NULL
; /* don't drop reference */
1000 spin_unlock(&dcache_lock
);
1011 * d_splice_alias - splice a disconnected dentry into the tree if one exists
1012 * @inode: the inode which may have a disconnected dentry
1013 * @dentry: a negative dentry which we want to point to the inode.
1015 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
1016 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
1017 * and return it, else simply d_add the inode to the dentry and return NULL.
1019 * This is needed in the lookup routine of any filesystem that is exportable
1020 * (via knfsd) so that we can build dcache paths to directories effectively.
1022 * If a dentry was found and moved, then it is returned. Otherwise NULL
1023 * is returned. This matches the expected return value of ->lookup.
1026 struct dentry
*d_splice_alias(struct inode
*inode
, struct dentry
*dentry
)
1028 struct dentry
*new = NULL
;
1031 spin_lock(&dcache_lock
);
1032 new = __d_find_alias(inode
, 1);
1034 BUG_ON(!(new->d_flags
& DCACHE_DISCONNECTED
));
1035 fsnotify_d_instantiate(new, inode
);
1036 spin_unlock(&dcache_lock
);
1037 security_d_instantiate(new, inode
);
1039 d_move(new, dentry
);
1042 /* d_instantiate takes dcache_lock, so we do it by hand */
1043 list_add(&dentry
->d_alias
, &inode
->i_dentry
);
1044 dentry
->d_inode
= inode
;
1045 fsnotify_d_instantiate(dentry
, inode
);
1046 spin_unlock(&dcache_lock
);
1047 security_d_instantiate(dentry
, inode
);
1051 d_add(dentry
, inode
);
1057 * d_lookup - search for a dentry
1058 * @parent: parent dentry
1059 * @name: qstr of name we wish to find
1061 * Searches the children of the parent dentry for the name in question. If
1062 * the dentry is found its reference count is incremented and the dentry
1063 * is returned. The caller must use d_put to free the entry when it has
1064 * finished using it. %NULL is returned on failure.
1066 * __d_lookup is dcache_lock free. The hash list is protected using RCU.
1067 * Memory barriers are used while updating and doing lockless traversal.
1068 * To avoid races with d_move while rename is happening, d_lock is used.
1070 * Overflows in memcmp(), while d_move, are avoided by keeping the length
1071 * and name pointer in one structure pointed by d_qstr.
1073 * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while
1074 * lookup is going on.
1076 * dentry_unused list is not updated even if lookup finds the required dentry
1077 * in there. It is updated in places such as prune_dcache, shrink_dcache_sb,
1078 * select_parent and __dget_locked. This laziness saves lookup from dcache_lock
1081 * d_lookup() is protected against the concurrent renames in some unrelated
1082 * directory using the seqlockt_t rename_lock.
1085 struct dentry
* d_lookup(struct dentry
* parent
, struct qstr
* name
)
1087 struct dentry
* dentry
= NULL
;
1091 seq
= read_seqbegin(&rename_lock
);
1092 dentry
= __d_lookup(parent
, name
);
1095 } while (read_seqretry(&rename_lock
, seq
));
1099 struct dentry
* __d_lookup(struct dentry
* parent
, struct qstr
* name
)
1101 unsigned int len
= name
->len
;
1102 unsigned int hash
= name
->hash
;
1103 const unsigned char *str
= name
->name
;
1104 struct hlist_head
*head
= d_hash(parent
,hash
);
1105 struct dentry
*found
= NULL
;
1106 struct hlist_node
*node
;
1107 struct dentry
*dentry
;
1111 hlist_for_each_entry_rcu(dentry
, node
, head
, d_hash
) {
1114 if (dentry
->d_name
.hash
!= hash
)
1116 if (dentry
->d_parent
!= parent
)
1119 spin_lock(&dentry
->d_lock
);
1122 * Recheck the dentry after taking the lock - d_move may have
1123 * changed things. Don't bother checking the hash because we're
1124 * about to compare the whole name anyway.
1126 if (dentry
->d_parent
!= parent
)
1130 * It is safe to compare names since d_move() cannot
1131 * change the qstr (protected by d_lock).
1133 qstr
= &dentry
->d_name
;
1134 if (parent
->d_op
&& parent
->d_op
->d_compare
) {
1135 if (parent
->d_op
->d_compare(parent
, qstr
, name
))
1138 if (qstr
->len
!= len
)
1140 if (memcmp(qstr
->name
, str
, len
))
1144 if (!d_unhashed(dentry
)) {
1145 atomic_inc(&dentry
->d_count
);
1148 spin_unlock(&dentry
->d_lock
);
1151 spin_unlock(&dentry
->d_lock
);
1159 * d_hash_and_lookup - hash the qstr then search for a dentry
1160 * @dir: Directory to search in
1161 * @name: qstr of name we wish to find
1163 * On hash failure or on lookup failure NULL is returned.
1165 struct dentry
*d_hash_and_lookup(struct dentry
*dir
, struct qstr
*name
)
1167 struct dentry
*dentry
= NULL
;
1170 * Check for a fs-specific hash function. Note that we must
1171 * calculate the standard hash first, as the d_op->d_hash()
1172 * routine may choose to leave the hash value unchanged.
1174 name
->hash
= full_name_hash(name
->name
, name
->len
);
1175 if (dir
->d_op
&& dir
->d_op
->d_hash
) {
1176 if (dir
->d_op
->d_hash(dir
, name
) < 0)
1179 dentry
= d_lookup(dir
, name
);
1185 * d_validate - verify dentry provided from insecure source
1186 * @dentry: The dentry alleged to be valid child of @dparent
1187 * @dparent: The parent dentry (known to be valid)
1188 * @hash: Hash of the dentry
1189 * @len: Length of the name
1191 * An insecure source has sent us a dentry, here we verify it and dget() it.
1192 * This is used by ncpfs in its readdir implementation.
1193 * Zero is returned in the dentry is invalid.
1196 int d_validate(struct dentry
*dentry
, struct dentry
*dparent
)
1198 struct hlist_head
*base
;
1199 struct hlist_node
*lhp
;
1201 /* Check whether the ptr might be valid at all.. */
1202 if (!kmem_ptr_validate(dentry_cache
, dentry
))
1205 if (dentry
->d_parent
!= dparent
)
1208 spin_lock(&dcache_lock
);
1209 base
= d_hash(dparent
, dentry
->d_name
.hash
);
1210 hlist_for_each(lhp
,base
) {
1211 /* hlist_for_each_entry_rcu() not required for d_hash list
1212 * as it is parsed under dcache_lock
1214 if (dentry
== hlist_entry(lhp
, struct dentry
, d_hash
)) {
1215 __dget_locked(dentry
);
1216 spin_unlock(&dcache_lock
);
1220 spin_unlock(&dcache_lock
);
1226 * When a file is deleted, we have two options:
1227 * - turn this dentry into a negative dentry
1228 * - unhash this dentry and free it.
1230 * Usually, we want to just turn this into
1231 * a negative dentry, but if anybody else is
1232 * currently using the dentry or the inode
1233 * we can't do that and we fall back on removing
1234 * it from the hash queues and waiting for
1235 * it to be deleted later when it has no users
1239 * d_delete - delete a dentry
1240 * @dentry: The dentry to delete
1242 * Turn the dentry into a negative dentry if possible, otherwise
1243 * remove it from the hash queues so it can be deleted later
1246 void d_delete(struct dentry
* dentry
)
1250 * Are we the only user?
1252 spin_lock(&dcache_lock
);
1253 spin_lock(&dentry
->d_lock
);
1254 isdir
= S_ISDIR(dentry
->d_inode
->i_mode
);
1255 if (atomic_read(&dentry
->d_count
) == 1) {
1256 dentry_iput(dentry
);
1257 fsnotify_nameremove(dentry
, isdir
);
1259 /* remove this and other inotify debug checks after 2.6.18 */
1260 dentry
->d_flags
&= ~DCACHE_INOTIFY_PARENT_WATCHED
;
1264 if (!d_unhashed(dentry
))
1267 spin_unlock(&dentry
->d_lock
);
1268 spin_unlock(&dcache_lock
);
1270 fsnotify_nameremove(dentry
, isdir
);
1273 static void __d_rehash(struct dentry
* entry
, struct hlist_head
*list
)
1276 entry
->d_flags
&= ~DCACHE_UNHASHED
;
1277 hlist_add_head_rcu(&entry
->d_hash
, list
);
1281 * d_rehash - add an entry back to the hash
1282 * @entry: dentry to add to the hash
1284 * Adds a dentry to the hash according to its name.
1287 void d_rehash(struct dentry
* entry
)
1289 struct hlist_head
*list
= d_hash(entry
->d_parent
, entry
->d_name
.hash
);
1291 spin_lock(&dcache_lock
);
1292 spin_lock(&entry
->d_lock
);
1293 __d_rehash(entry
, list
);
1294 spin_unlock(&entry
->d_lock
);
1295 spin_unlock(&dcache_lock
);
1298 #define do_switch(x,y) do { \
1299 __typeof__ (x) __tmp = x; \
1300 x = y; y = __tmp; } while (0)
1303 * When switching names, the actual string doesn't strictly have to
1304 * be preserved in the target - because we're dropping the target
1305 * anyway. As such, we can just do a simple memcpy() to copy over
1306 * the new name before we switch.
1308 * Note that we have to be a lot more careful about getting the hash
1309 * switched - we have to switch the hash value properly even if it
1310 * then no longer matches the actual (corrupted) string of the target.
1311 * The hash value has to match the hash queue that the dentry is on..
1313 static void switch_names(struct dentry
*dentry
, struct dentry
*target
)
1315 if (dname_external(target
)) {
1316 if (dname_external(dentry
)) {
1318 * Both external: swap the pointers
1320 do_switch(target
->d_name
.name
, dentry
->d_name
.name
);
1323 * dentry:internal, target:external. Steal target's
1324 * storage and make target internal.
1326 dentry
->d_name
.name
= target
->d_name
.name
;
1327 target
->d_name
.name
= target
->d_iname
;
1330 if (dname_external(dentry
)) {
1332 * dentry:external, target:internal. Give dentry's
1333 * storage to target and make dentry internal
1335 memcpy(dentry
->d_iname
, target
->d_name
.name
,
1336 target
->d_name
.len
+ 1);
1337 target
->d_name
.name
= dentry
->d_name
.name
;
1338 dentry
->d_name
.name
= dentry
->d_iname
;
1341 * Both are internal. Just copy target to dentry
1343 memcpy(dentry
->d_iname
, target
->d_name
.name
,
1344 target
->d_name
.len
+ 1);
1350 * We cannibalize "target" when moving dentry on top of it,
1351 * because it's going to be thrown away anyway. We could be more
1352 * polite about it, though.
1354 * This forceful removal will result in ugly /proc output if
1355 * somebody holds a file open that got deleted due to a rename.
1356 * We could be nicer about the deleted file, and let it show
1357 * up under the name it got deleted rather than the name that
1362 * d_move - move a dentry
1363 * @dentry: entry to move
1364 * @target: new dentry
1366 * Update the dcache to reflect the move of a file name. Negative
1367 * dcache entries should not be moved in this way.
1370 void d_move(struct dentry
* dentry
, struct dentry
* target
)
1372 struct hlist_head
*list
;
1374 if (!dentry
->d_inode
)
1375 printk(KERN_WARNING
"VFS: moving negative dcache entry\n");
1377 spin_lock(&dcache_lock
);
1378 write_seqlock(&rename_lock
);
1380 * XXXX: do we really need to take target->d_lock?
1382 if (target
< dentry
) {
1383 spin_lock(&target
->d_lock
);
1384 spin_lock(&dentry
->d_lock
);
1386 spin_lock(&dentry
->d_lock
);
1387 spin_lock(&target
->d_lock
);
1390 /* Move the dentry to the target hash queue, if on different bucket */
1391 if (dentry
->d_flags
& DCACHE_UNHASHED
)
1392 goto already_unhashed
;
1394 hlist_del_rcu(&dentry
->d_hash
);
1397 list
= d_hash(target
->d_parent
, target
->d_name
.hash
);
1398 __d_rehash(dentry
, list
);
1400 /* Unhash the target: dput() will then get rid of it */
1403 list_del(&dentry
->d_u
.d_child
);
1404 list_del(&target
->d_u
.d_child
);
1406 /* Switch the names.. */
1407 switch_names(dentry
, target
);
1408 do_switch(dentry
->d_name
.len
, target
->d_name
.len
);
1409 do_switch(dentry
->d_name
.hash
, target
->d_name
.hash
);
1411 /* ... and switch the parents */
1412 if (IS_ROOT(dentry
)) {
1413 dentry
->d_parent
= target
->d_parent
;
1414 target
->d_parent
= target
;
1415 INIT_LIST_HEAD(&target
->d_u
.d_child
);
1417 do_switch(dentry
->d_parent
, target
->d_parent
);
1419 /* And add them back to the (new) parent lists */
1420 list_add(&target
->d_u
.d_child
, &target
->d_parent
->d_subdirs
);
1423 list_add(&dentry
->d_u
.d_child
, &dentry
->d_parent
->d_subdirs
);
1424 spin_unlock(&target
->d_lock
);
1425 fsnotify_d_move(dentry
);
1426 spin_unlock(&dentry
->d_lock
);
1427 write_sequnlock(&rename_lock
);
1428 spin_unlock(&dcache_lock
);
1432 * d_path - return the path of a dentry
1433 * @dentry: dentry to report
1434 * @vfsmnt: vfsmnt to which the dentry belongs
1435 * @root: root dentry
1436 * @rootmnt: vfsmnt to which the root dentry belongs
1437 * @buffer: buffer to return value in
1438 * @buflen: buffer length
1440 * Convert a dentry into an ASCII path name. If the entry has been deleted
1441 * the string " (deleted)" is appended. Note that this is ambiguous.
1443 * Returns the buffer or an error code if the path was too long.
1445 * "buflen" should be positive. Caller holds the dcache_lock.
1447 static char * __d_path( struct dentry
*dentry
, struct vfsmount
*vfsmnt
,
1448 struct dentry
*root
, struct vfsmount
*rootmnt
,
1449 char *buffer
, int buflen
)
1451 char * end
= buffer
+buflen
;
1457 if (!IS_ROOT(dentry
) && d_unhashed(dentry
)) {
1462 memcpy(end
, " (deleted)", 10);
1472 struct dentry
* parent
;
1474 if (dentry
== root
&& vfsmnt
== rootmnt
)
1476 if (dentry
== vfsmnt
->mnt_root
|| IS_ROOT(dentry
)) {
1478 spin_lock(&vfsmount_lock
);
1479 if (vfsmnt
->mnt_parent
== vfsmnt
) {
1480 spin_unlock(&vfsmount_lock
);
1483 dentry
= vfsmnt
->mnt_mountpoint
;
1484 vfsmnt
= vfsmnt
->mnt_parent
;
1485 spin_unlock(&vfsmount_lock
);
1488 parent
= dentry
->d_parent
;
1490 namelen
= dentry
->d_name
.len
;
1491 buflen
-= namelen
+ 1;
1495 memcpy(end
, dentry
->d_name
.name
, namelen
);
1504 namelen
= dentry
->d_name
.len
;
1508 retval
-= namelen
-1; /* hit the slash */
1509 memcpy(retval
, dentry
->d_name
.name
, namelen
);
1512 return ERR_PTR(-ENAMETOOLONG
);
1515 /* write full pathname into buffer and return start of pathname */
1516 char * d_path(struct dentry
*dentry
, struct vfsmount
*vfsmnt
,
1517 char *buf
, int buflen
)
1520 struct vfsmount
*rootmnt
;
1521 struct dentry
*root
;
1523 read_lock(¤t
->fs
->lock
);
1524 rootmnt
= mntget(current
->fs
->rootmnt
);
1525 root
= dget(current
->fs
->root
);
1526 read_unlock(¤t
->fs
->lock
);
1527 spin_lock(&dcache_lock
);
1528 res
= __d_path(dentry
, vfsmnt
, root
, rootmnt
, buf
, buflen
);
1529 spin_unlock(&dcache_lock
);
1536 * NOTE! The user-level library version returns a
1537 * character pointer. The kernel system call just
1538 * returns the length of the buffer filled (which
1539 * includes the ending '\0' character), or a negative
1540 * error value. So libc would do something like
1542 * char *getcwd(char * buf, size_t size)
1546 * retval = sys_getcwd(buf, size);
1553 asmlinkage
long sys_getcwd(char __user
*buf
, unsigned long size
)
1556 struct vfsmount
*pwdmnt
, *rootmnt
;
1557 struct dentry
*pwd
, *root
;
1558 char *page
= (char *) __get_free_page(GFP_USER
);
1563 read_lock(¤t
->fs
->lock
);
1564 pwdmnt
= mntget(current
->fs
->pwdmnt
);
1565 pwd
= dget(current
->fs
->pwd
);
1566 rootmnt
= mntget(current
->fs
->rootmnt
);
1567 root
= dget(current
->fs
->root
);
1568 read_unlock(¤t
->fs
->lock
);
1571 /* Has the current directory has been unlinked? */
1572 spin_lock(&dcache_lock
);
1573 if (pwd
->d_parent
== pwd
|| !d_unhashed(pwd
)) {
1577 cwd
= __d_path(pwd
, pwdmnt
, root
, rootmnt
, page
, PAGE_SIZE
);
1578 spin_unlock(&dcache_lock
);
1580 error
= PTR_ERR(cwd
);
1585 len
= PAGE_SIZE
+ page
- cwd
;
1588 if (copy_to_user(buf
, cwd
, len
))
1592 spin_unlock(&dcache_lock
);
1599 free_page((unsigned long) page
);
1604 * Test whether new_dentry is a subdirectory of old_dentry.
1606 * Trivially implemented using the dcache structure
1610 * is_subdir - is new dentry a subdirectory of old_dentry
1611 * @new_dentry: new dentry
1612 * @old_dentry: old dentry
1614 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
1615 * Returns 0 otherwise.
1616 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
1619 int is_subdir(struct dentry
* new_dentry
, struct dentry
* old_dentry
)
1622 struct dentry
* saved
= new_dentry
;
1625 /* need rcu_readlock to protect against the d_parent trashing due to
1630 /* for restarting inner loop in case of seq retry */
1633 seq
= read_seqbegin(&rename_lock
);
1635 if (new_dentry
!= old_dentry
) {
1636 struct dentry
* parent
= new_dentry
->d_parent
;
1637 if (parent
== new_dentry
)
1639 new_dentry
= parent
;
1645 } while (read_seqretry(&rename_lock
, seq
));
1651 void d_genocide(struct dentry
*root
)
1653 struct dentry
*this_parent
= root
;
1654 struct list_head
*next
;
1656 spin_lock(&dcache_lock
);
1658 next
= this_parent
->d_subdirs
.next
;
1660 while (next
!= &this_parent
->d_subdirs
) {
1661 struct list_head
*tmp
= next
;
1662 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
1664 if (d_unhashed(dentry
)||!dentry
->d_inode
)
1666 if (!list_empty(&dentry
->d_subdirs
)) {
1667 this_parent
= dentry
;
1670 atomic_dec(&dentry
->d_count
);
1672 if (this_parent
!= root
) {
1673 next
= this_parent
->d_u
.d_child
.next
;
1674 atomic_dec(&this_parent
->d_count
);
1675 this_parent
= this_parent
->d_parent
;
1678 spin_unlock(&dcache_lock
);
1682 * find_inode_number - check for dentry with name
1683 * @dir: directory to check
1684 * @name: Name to find.
1686 * Check whether a dentry already exists for the given name,
1687 * and return the inode number if it has an inode. Otherwise
1690 * This routine is used to post-process directory listings for
1691 * filesystems using synthetic inode numbers, and is necessary
1692 * to keep getcwd() working.
1695 ino_t
find_inode_number(struct dentry
*dir
, struct qstr
*name
)
1697 struct dentry
* dentry
;
1700 dentry
= d_hash_and_lookup(dir
, name
);
1702 if (dentry
->d_inode
)
1703 ino
= dentry
->d_inode
->i_ino
;
1709 static __initdata
unsigned long dhash_entries
;
1710 static int __init
set_dhash_entries(char *str
)
1714 dhash_entries
= simple_strtoul(str
, &str
, 0);
1717 __setup("dhash_entries=", set_dhash_entries
);
1719 static void __init
dcache_init_early(void)
1723 /* If hashes are distributed across NUMA nodes, defer
1724 * hash allocation until vmalloc space is available.
1730 alloc_large_system_hash("Dentry cache",
1731 sizeof(struct hlist_head
),
1739 for (loop
= 0; loop
< (1 << d_hash_shift
); loop
++)
1740 INIT_HLIST_HEAD(&dentry_hashtable
[loop
]);
1743 static void __init
dcache_init(unsigned long mempages
)
1748 * A constructor could be added for stable state like the lists,
1749 * but it is probably not worth it because of the cache nature
1752 dentry_cache
= kmem_cache_create("dentry_cache",
1753 sizeof(struct dentry
),
1755 (SLAB_RECLAIM_ACCOUNT
|SLAB_PANIC
|
1759 set_shrinker(DEFAULT_SEEKS
, shrink_dcache_memory
);
1761 /* Hash may have been set up in dcache_init_early */
1766 alloc_large_system_hash("Dentry cache",
1767 sizeof(struct hlist_head
),
1775 for (loop
= 0; loop
< (1 << d_hash_shift
); loop
++)
1776 INIT_HLIST_HEAD(&dentry_hashtable
[loop
]);
1779 /* SLAB cache for __getname() consumers */
1780 kmem_cache_t
*names_cachep __read_mostly
;
1782 /* SLAB cache for file structures */
1783 kmem_cache_t
*filp_cachep __read_mostly
;
1785 EXPORT_SYMBOL(d_genocide
);
1787 extern void bdev_cache_init(void);
1788 extern void chrdev_init(void);
1790 void __init
vfs_caches_init_early(void)
1792 dcache_init_early();
1796 void __init
vfs_caches_init(unsigned long mempages
)
1798 unsigned long reserve
;
1800 /* Base hash sizes on available memory, with a reserve equal to
1801 150% of current kernel size */
1803 reserve
= min((mempages
- nr_free_pages()) * 3/2, mempages
- 1);
1804 mempages
-= reserve
;
1806 names_cachep
= kmem_cache_create("names_cache", PATH_MAX
, 0,
1807 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1809 filp_cachep
= kmem_cache_create("filp", sizeof(struct file
), 0,
1810 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1812 dcache_init(mempages
);
1813 inode_init(mempages
);
1814 files_init(mempages
);
1820 EXPORT_SYMBOL(d_alloc
);
1821 EXPORT_SYMBOL(d_alloc_anon
);
1822 EXPORT_SYMBOL(d_alloc_root
);
1823 EXPORT_SYMBOL(d_delete
);
1824 EXPORT_SYMBOL(d_find_alias
);
1825 EXPORT_SYMBOL(d_instantiate
);
1826 EXPORT_SYMBOL(d_invalidate
);
1827 EXPORT_SYMBOL(d_lookup
);
1828 EXPORT_SYMBOL(d_move
);
1829 EXPORT_SYMBOL(d_path
);
1830 EXPORT_SYMBOL(d_prune_aliases
);
1831 EXPORT_SYMBOL(d_rehash
);
1832 EXPORT_SYMBOL(d_splice_alias
);
1833 EXPORT_SYMBOL(d_validate
);
1834 EXPORT_SYMBOL(dget_locked
);
1835 EXPORT_SYMBOL(dput
);
1836 EXPORT_SYMBOL(find_inode_number
);
1837 EXPORT_SYMBOL(have_submounts
);
1838 EXPORT_SYMBOL(names_cachep
);
1839 EXPORT_SYMBOL(shrink_dcache_parent
);
1840 EXPORT_SYMBOL(shrink_dcache_sb
);