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/export.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>
36 #include <linux/bit_spinlock.h>
37 #include <linux/rculist_bl.h>
38 #include <linux/prefetch.h>
39 #include <linux/ratelimit.h>
40 #include <linux/list_lru.h>
46 * dcache->d_inode->i_lock protects:
47 * - i_dentry, d_alias, d_inode of aliases
48 * dcache_hash_bucket lock protects:
49 * - the dcache hash table
50 * s_anon bl list spinlock protects:
51 * - the s_anon list (see __d_drop)
52 * dentry->d_sb->s_dentry_lru_lock protects:
53 * - the dcache lru lists and counters
60 * - d_parent and d_subdirs
61 * - childrens' d_child and d_parent
65 * dentry->d_inode->i_lock
67 * dentry->d_sb->s_dentry_lru_lock
68 * dcache_hash_bucket lock
71 * If there is an ancestor relationship:
72 * dentry->d_parent->...->d_parent->d_lock
74 * dentry->d_parent->d_lock
77 * If no ancestor relationship:
78 * if (dentry1 < dentry2)
82 int sysctl_vfs_cache_pressure __read_mostly
= 100;
83 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure
);
85 __cacheline_aligned_in_smp
DEFINE_SEQLOCK(rename_lock
);
87 EXPORT_SYMBOL(rename_lock
);
89 static struct kmem_cache
*dentry_cache __read_mostly
;
92 * This is the single most critical data structure when it comes
93 * to the dcache: the hashtable for lookups. Somebody should try
94 * to make this good - I've just made it work.
96 * This hash-function tries to avoid losing too many bits of hash
97 * information, yet avoid using a prime hash-size or similar.
100 static unsigned int d_hash_mask __read_mostly
;
101 static unsigned int d_hash_shift __read_mostly
;
103 static struct hlist_bl_head
*dentry_hashtable __read_mostly
;
105 static inline struct hlist_bl_head
*d_hash(const struct dentry
*parent
,
108 hash
+= (unsigned long) parent
/ L1_CACHE_BYTES
;
109 hash
= hash
+ (hash
>> d_hash_shift
);
110 return dentry_hashtable
+ (hash
& d_hash_mask
);
113 /* Statistics gathering. */
114 struct dentry_stat_t dentry_stat
= {
118 static DEFINE_PER_CPU(long, nr_dentry
);
119 static DEFINE_PER_CPU(long, nr_dentry_unused
);
121 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
124 * Here we resort to our own counters instead of using generic per-cpu counters
125 * for consistency with what the vfs inode code does. We are expected to harvest
126 * better code and performance by having our own specialized counters.
128 * Please note that the loop is done over all possible CPUs, not over all online
129 * CPUs. The reason for this is that we don't want to play games with CPUs going
130 * on and off. If one of them goes off, we will just keep their counters.
132 * glommer: See cffbc8a for details, and if you ever intend to change this,
133 * please update all vfs counters to match.
135 static long get_nr_dentry(void)
139 for_each_possible_cpu(i
)
140 sum
+= per_cpu(nr_dentry
, i
);
141 return sum
< 0 ? 0 : sum
;
144 static long get_nr_dentry_unused(void)
148 for_each_possible_cpu(i
)
149 sum
+= per_cpu(nr_dentry_unused
, i
);
150 return sum
< 0 ? 0 : sum
;
153 int proc_nr_dentry(struct ctl_table
*table
, int write
, void __user
*buffer
,
154 size_t *lenp
, loff_t
*ppos
)
156 dentry_stat
.nr_dentry
= get_nr_dentry();
157 dentry_stat
.nr_unused
= get_nr_dentry_unused();
158 return proc_doulongvec_minmax(table
, write
, buffer
, lenp
, ppos
);
163 * Compare 2 name strings, return 0 if they match, otherwise non-zero.
164 * The strings are both count bytes long, and count is non-zero.
166 #ifdef CONFIG_DCACHE_WORD_ACCESS
168 #include <asm/word-at-a-time.h>
170 * NOTE! 'cs' and 'scount' come from a dentry, so it has a
171 * aligned allocation for this particular component. We don't
172 * strictly need the load_unaligned_zeropad() safety, but it
173 * doesn't hurt either.
175 * In contrast, 'ct' and 'tcount' can be from a pathname, and do
176 * need the careful unaligned handling.
178 static inline int dentry_string_cmp(const unsigned char *cs
, const unsigned char *ct
, unsigned tcount
)
180 unsigned long a
,b
,mask
;
183 a
= *(unsigned long *)cs
;
184 b
= load_unaligned_zeropad(ct
);
185 if (tcount
< sizeof(unsigned long))
187 if (unlikely(a
!= b
))
189 cs
+= sizeof(unsigned long);
190 ct
+= sizeof(unsigned long);
191 tcount
-= sizeof(unsigned long);
195 mask
= bytemask_from_count(tcount
);
196 return unlikely(!!((a
^ b
) & mask
));
201 static inline int dentry_string_cmp(const unsigned char *cs
, const unsigned char *ct
, unsigned tcount
)
215 static inline int dentry_cmp(const struct dentry
*dentry
, const unsigned char *ct
, unsigned tcount
)
217 const unsigned char *cs
;
219 * Be careful about RCU walk racing with rename:
220 * use ACCESS_ONCE to fetch the name pointer.
222 * NOTE! Even if a rename will mean that the length
223 * was not loaded atomically, we don't care. The
224 * RCU walk will check the sequence count eventually,
225 * and catch it. And we won't overrun the buffer,
226 * because we're reading the name pointer atomically,
227 * and a dentry name is guaranteed to be properly
228 * terminated with a NUL byte.
230 * End result: even if 'len' is wrong, we'll exit
231 * early because the data cannot match (there can
232 * be no NUL in the ct/tcount data)
234 cs
= ACCESS_ONCE(dentry
->d_name
.name
);
235 smp_read_barrier_depends();
236 return dentry_string_cmp(cs
, ct
, tcount
);
239 static void __d_free(struct rcu_head
*head
)
241 struct dentry
*dentry
= container_of(head
, struct dentry
, d_u
.d_rcu
);
243 WARN_ON(!hlist_unhashed(&dentry
->d_alias
));
244 if (dname_external(dentry
))
245 kfree(dentry
->d_name
.name
);
246 kmem_cache_free(dentry_cache
, dentry
);
249 static void dentry_free(struct dentry
*dentry
)
251 /* if dentry was never visible to RCU, immediate free is OK */
252 if (!(dentry
->d_flags
& DCACHE_RCUACCESS
))
253 __d_free(&dentry
->d_u
.d_rcu
);
255 call_rcu(&dentry
->d_u
.d_rcu
, __d_free
);
259 * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups
260 * @dentry: the target dentry
261 * After this call, in-progress rcu-walk path lookup will fail. This
262 * should be called after unhashing, and after changing d_inode (if
263 * the dentry has not already been unhashed).
265 static inline void dentry_rcuwalk_barrier(struct dentry
*dentry
)
267 assert_spin_locked(&dentry
->d_lock
);
268 /* Go through a barrier */
269 write_seqcount_barrier(&dentry
->d_seq
);
273 * Release the dentry's inode, using the filesystem
274 * d_iput() operation if defined. Dentry has no refcount
277 static void dentry_iput(struct dentry
* dentry
)
278 __releases(dentry
->d_lock
)
279 __releases(dentry
->d_inode
->i_lock
)
281 struct inode
*inode
= dentry
->d_inode
;
283 dentry
->d_inode
= NULL
;
284 hlist_del_init(&dentry
->d_alias
);
285 spin_unlock(&dentry
->d_lock
);
286 spin_unlock(&inode
->i_lock
);
288 fsnotify_inoderemove(inode
);
289 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
290 dentry
->d_op
->d_iput(dentry
, inode
);
294 spin_unlock(&dentry
->d_lock
);
299 * Release the dentry's inode, using the filesystem
300 * d_iput() operation if defined. dentry remains in-use.
302 static void dentry_unlink_inode(struct dentry
* dentry
)
303 __releases(dentry
->d_lock
)
304 __releases(dentry
->d_inode
->i_lock
)
306 struct inode
*inode
= dentry
->d_inode
;
307 __d_clear_type(dentry
);
308 dentry
->d_inode
= NULL
;
309 hlist_del_init(&dentry
->d_alias
);
310 dentry_rcuwalk_barrier(dentry
);
311 spin_unlock(&dentry
->d_lock
);
312 spin_unlock(&inode
->i_lock
);
314 fsnotify_inoderemove(inode
);
315 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
316 dentry
->d_op
->d_iput(dentry
, inode
);
322 * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
323 * is in use - which includes both the "real" per-superblock
324 * LRU list _and_ the DCACHE_SHRINK_LIST use.
326 * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
327 * on the shrink list (ie not on the superblock LRU list).
329 * The per-cpu "nr_dentry_unused" counters are updated with
330 * the DCACHE_LRU_LIST bit.
332 * These helper functions make sure we always follow the
333 * rules. d_lock must be held by the caller.
335 #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
336 static void d_lru_add(struct dentry
*dentry
)
338 D_FLAG_VERIFY(dentry
, 0);
339 dentry
->d_flags
|= DCACHE_LRU_LIST
;
340 this_cpu_inc(nr_dentry_unused
);
341 WARN_ON_ONCE(!list_lru_add(&dentry
->d_sb
->s_dentry_lru
, &dentry
->d_lru
));
344 static void d_lru_del(struct dentry
*dentry
)
346 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
347 dentry
->d_flags
&= ~DCACHE_LRU_LIST
;
348 this_cpu_dec(nr_dentry_unused
);
349 WARN_ON_ONCE(!list_lru_del(&dentry
->d_sb
->s_dentry_lru
, &dentry
->d_lru
));
352 static void d_shrink_del(struct dentry
*dentry
)
354 D_FLAG_VERIFY(dentry
, DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
);
355 list_del_init(&dentry
->d_lru
);
356 dentry
->d_flags
&= ~(DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
);
357 this_cpu_dec(nr_dentry_unused
);
360 static void d_shrink_add(struct dentry
*dentry
, struct list_head
*list
)
362 D_FLAG_VERIFY(dentry
, 0);
363 list_add(&dentry
->d_lru
, list
);
364 dentry
->d_flags
|= DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
;
365 this_cpu_inc(nr_dentry_unused
);
369 * These can only be called under the global LRU lock, ie during the
370 * callback for freeing the LRU list. "isolate" removes it from the
371 * LRU lists entirely, while shrink_move moves it to the indicated
374 static void d_lru_isolate(struct dentry
*dentry
)
376 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
377 dentry
->d_flags
&= ~DCACHE_LRU_LIST
;
378 this_cpu_dec(nr_dentry_unused
);
379 list_del_init(&dentry
->d_lru
);
382 static void d_lru_shrink_move(struct dentry
*dentry
, struct list_head
*list
)
384 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
385 dentry
->d_flags
|= DCACHE_SHRINK_LIST
;
386 list_move_tail(&dentry
->d_lru
, list
);
390 * dentry_lru_(add|del)_list) must be called with d_lock held.
392 static void dentry_lru_add(struct dentry
*dentry
)
394 if (unlikely(!(dentry
->d_flags
& DCACHE_LRU_LIST
)))
399 * d_drop - drop a dentry
400 * @dentry: dentry to drop
402 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
403 * be found through a VFS lookup any more. Note that this is different from
404 * deleting the dentry - d_delete will try to mark the dentry negative if
405 * possible, giving a successful _negative_ lookup, while d_drop will
406 * just make the cache lookup fail.
408 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
409 * reason (NFS timeouts or autofs deletes).
411 * __d_drop requires dentry->d_lock.
413 void __d_drop(struct dentry
*dentry
)
415 if (!d_unhashed(dentry
)) {
416 struct hlist_bl_head
*b
;
418 * Hashed dentries are normally on the dentry hashtable,
419 * with the exception of those newly allocated by
420 * d_obtain_alias, which are always IS_ROOT:
422 if (unlikely(IS_ROOT(dentry
)))
423 b
= &dentry
->d_sb
->s_anon
;
425 b
= d_hash(dentry
->d_parent
, dentry
->d_name
.hash
);
428 __hlist_bl_del(&dentry
->d_hash
);
429 dentry
->d_hash
.pprev
= NULL
;
431 dentry_rcuwalk_barrier(dentry
);
434 EXPORT_SYMBOL(__d_drop
);
436 void d_drop(struct dentry
*dentry
)
438 spin_lock(&dentry
->d_lock
);
440 spin_unlock(&dentry
->d_lock
);
442 EXPORT_SYMBOL(d_drop
);
444 static void __dentry_kill(struct dentry
*dentry
)
446 struct dentry
*parent
= NULL
;
447 bool can_free
= true;
448 if (!IS_ROOT(dentry
))
449 parent
= dentry
->d_parent
;
452 * The dentry is now unrecoverably dead to the world.
454 lockref_mark_dead(&dentry
->d_lockref
);
457 * inform the fs via d_prune that this dentry is about to be
458 * unhashed and destroyed.
460 if ((dentry
->d_flags
& DCACHE_OP_PRUNE
) && !d_unhashed(dentry
))
461 dentry
->d_op
->d_prune(dentry
);
463 if (dentry
->d_flags
& DCACHE_LRU_LIST
) {
464 if (!(dentry
->d_flags
& DCACHE_SHRINK_LIST
))
467 /* if it was on the hash then remove it */
469 list_del(&dentry
->d_u
.d_child
);
471 * Inform d_walk() that we are no longer attached to the
474 dentry
->d_flags
|= DCACHE_DENTRY_KILLED
;
476 spin_unlock(&parent
->d_lock
);
479 * dentry_iput drops the locks, at which point nobody (except
480 * transient RCU lookups) can reach this dentry.
482 BUG_ON((int)dentry
->d_lockref
.count
> 0);
483 this_cpu_dec(nr_dentry
);
484 if (dentry
->d_op
&& dentry
->d_op
->d_release
)
485 dentry
->d_op
->d_release(dentry
);
487 spin_lock(&dentry
->d_lock
);
488 if (dentry
->d_flags
& DCACHE_SHRINK_LIST
) {
489 dentry
->d_flags
|= DCACHE_MAY_FREE
;
492 spin_unlock(&dentry
->d_lock
);
493 if (likely(can_free
))
498 * Finish off a dentry we've decided to kill.
499 * dentry->d_lock must be held, returns with it unlocked.
500 * If ref is non-zero, then decrement the refcount too.
501 * Returns dentry requiring refcount drop, or NULL if we're done.
503 static struct dentry
*dentry_kill(struct dentry
*dentry
)
504 __releases(dentry
->d_lock
)
506 struct inode
*inode
= dentry
->d_inode
;
507 struct dentry
*parent
= NULL
;
509 if (inode
&& unlikely(!spin_trylock(&inode
->i_lock
)))
512 if (!IS_ROOT(dentry
)) {
513 parent
= dentry
->d_parent
;
514 if (unlikely(!spin_trylock(&parent
->d_lock
))) {
516 spin_unlock(&inode
->i_lock
);
521 __dentry_kill(dentry
);
525 spin_unlock(&dentry
->d_lock
);
527 return dentry
; /* try again with same dentry */
530 static inline struct dentry
*lock_parent(struct dentry
*dentry
)
532 struct dentry
*parent
= dentry
->d_parent
;
535 if (unlikely((int)dentry
->d_lockref
.count
< 0))
537 if (likely(spin_trylock(&parent
->d_lock
)))
540 spin_unlock(&dentry
->d_lock
);
542 parent
= ACCESS_ONCE(dentry
->d_parent
);
543 spin_lock(&parent
->d_lock
);
545 * We can't blindly lock dentry until we are sure
546 * that we won't violate the locking order.
547 * Any changes of dentry->d_parent must have
548 * been done with parent->d_lock held, so
549 * spin_lock() above is enough of a barrier
550 * for checking if it's still our child.
552 if (unlikely(parent
!= dentry
->d_parent
)) {
553 spin_unlock(&parent
->d_lock
);
557 if (parent
!= dentry
)
558 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
567 * This is complicated by the fact that we do not want to put
568 * dentries that are no longer on any hash chain on the unused
569 * list: we'd much rather just get rid of them immediately.
571 * However, that implies that we have to traverse the dentry
572 * tree upwards to the parents which might _also_ now be
573 * scheduled for deletion (it may have been only waiting for
574 * its last child to go away).
576 * This tail recursion is done by hand as we don't want to depend
577 * on the compiler to always get this right (gcc generally doesn't).
578 * Real recursion would eat up our stack space.
582 * dput - release a dentry
583 * @dentry: dentry to release
585 * Release a dentry. This will drop the usage count and if appropriate
586 * call the dentry unlink method as well as removing it from the queues and
587 * releasing its resources. If the parent dentries were scheduled for release
588 * they too may now get deleted.
590 void dput(struct dentry
*dentry
)
592 if (unlikely(!dentry
))
596 if (lockref_put_or_lock(&dentry
->d_lockref
))
599 /* Unreachable? Get rid of it */
600 if (unlikely(d_unhashed(dentry
)))
603 if (unlikely(dentry
->d_flags
& DCACHE_OP_DELETE
)) {
604 if (dentry
->d_op
->d_delete(dentry
))
608 if (!(dentry
->d_flags
& DCACHE_REFERENCED
))
609 dentry
->d_flags
|= DCACHE_REFERENCED
;
610 dentry_lru_add(dentry
);
612 dentry
->d_lockref
.count
--;
613 spin_unlock(&dentry
->d_lock
);
617 dentry
= dentry_kill(dentry
);
624 * d_invalidate - invalidate a dentry
625 * @dentry: dentry to invalidate
627 * Try to invalidate the dentry if it turns out to be
628 * possible. If there are other dentries that can be
629 * reached through this one we can't delete it and we
630 * return -EBUSY. On success we return 0.
635 int d_invalidate(struct dentry
* dentry
)
638 * If it's already been dropped, return OK.
640 spin_lock(&dentry
->d_lock
);
641 if (d_unhashed(dentry
)) {
642 spin_unlock(&dentry
->d_lock
);
646 * Check whether to do a partial shrink_dcache
647 * to get rid of unused child entries.
649 if (!list_empty(&dentry
->d_subdirs
)) {
650 spin_unlock(&dentry
->d_lock
);
651 shrink_dcache_parent(dentry
);
652 spin_lock(&dentry
->d_lock
);
656 * Somebody else still using it?
658 * If it's a directory, we can't drop it
659 * for fear of somebody re-populating it
660 * with children (even though dropping it
661 * would make it unreachable from the root,
662 * we might still populate it if it was a
663 * working directory or similar).
664 * We also need to leave mountpoints alone,
667 if (dentry
->d_lockref
.count
> 1 && dentry
->d_inode
) {
668 if (S_ISDIR(dentry
->d_inode
->i_mode
) || d_mountpoint(dentry
)) {
669 spin_unlock(&dentry
->d_lock
);
675 spin_unlock(&dentry
->d_lock
);
678 EXPORT_SYMBOL(d_invalidate
);
680 /* This must be called with d_lock held */
681 static inline void __dget_dlock(struct dentry
*dentry
)
683 dentry
->d_lockref
.count
++;
686 static inline void __dget(struct dentry
*dentry
)
688 lockref_get(&dentry
->d_lockref
);
691 struct dentry
*dget_parent(struct dentry
*dentry
)
697 * Do optimistic parent lookup without any
701 ret
= ACCESS_ONCE(dentry
->d_parent
);
702 gotref
= lockref_get_not_zero(&ret
->d_lockref
);
704 if (likely(gotref
)) {
705 if (likely(ret
== ACCESS_ONCE(dentry
->d_parent
)))
712 * Don't need rcu_dereference because we re-check it was correct under
716 ret
= dentry
->d_parent
;
717 spin_lock(&ret
->d_lock
);
718 if (unlikely(ret
!= dentry
->d_parent
)) {
719 spin_unlock(&ret
->d_lock
);
724 BUG_ON(!ret
->d_lockref
.count
);
725 ret
->d_lockref
.count
++;
726 spin_unlock(&ret
->d_lock
);
729 EXPORT_SYMBOL(dget_parent
);
732 * d_find_alias - grab a hashed alias of inode
733 * @inode: inode in question
734 * @want_discon: flag, used by d_splice_alias, to request
735 * that only a DISCONNECTED alias be returned.
737 * If inode has a hashed alias, or is a directory and has any alias,
738 * acquire the reference to alias and return it. Otherwise return NULL.
739 * Notice that if inode is a directory there can be only one alias and
740 * it can be unhashed only if it has no children, or if it is the root
743 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
744 * any other hashed alias over that one unless @want_discon is set,
745 * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias.
747 static struct dentry
*__d_find_alias(struct inode
*inode
, int want_discon
)
749 struct dentry
*alias
, *discon_alias
;
753 hlist_for_each_entry(alias
, &inode
->i_dentry
, d_alias
) {
754 spin_lock(&alias
->d_lock
);
755 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
756 if (IS_ROOT(alias
) &&
757 (alias
->d_flags
& DCACHE_DISCONNECTED
)) {
758 discon_alias
= alias
;
759 } else if (!want_discon
) {
761 spin_unlock(&alias
->d_lock
);
765 spin_unlock(&alias
->d_lock
);
768 alias
= discon_alias
;
769 spin_lock(&alias
->d_lock
);
770 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
771 if (IS_ROOT(alias
) &&
772 (alias
->d_flags
& DCACHE_DISCONNECTED
)) {
774 spin_unlock(&alias
->d_lock
);
778 spin_unlock(&alias
->d_lock
);
784 struct dentry
*d_find_alias(struct inode
*inode
)
786 struct dentry
*de
= NULL
;
788 if (!hlist_empty(&inode
->i_dentry
)) {
789 spin_lock(&inode
->i_lock
);
790 de
= __d_find_alias(inode
, 0);
791 spin_unlock(&inode
->i_lock
);
795 EXPORT_SYMBOL(d_find_alias
);
798 * Try to kill dentries associated with this inode.
799 * WARNING: you must own a reference to inode.
801 void d_prune_aliases(struct inode
*inode
)
803 struct dentry
*dentry
;
805 spin_lock(&inode
->i_lock
);
806 hlist_for_each_entry(dentry
, &inode
->i_dentry
, d_alias
) {
807 spin_lock(&dentry
->d_lock
);
808 if (!dentry
->d_lockref
.count
) {
810 * inform the fs via d_prune that this dentry
811 * is about to be unhashed and destroyed.
813 if ((dentry
->d_flags
& DCACHE_OP_PRUNE
) &&
815 dentry
->d_op
->d_prune(dentry
);
817 __dget_dlock(dentry
);
819 spin_unlock(&dentry
->d_lock
);
820 spin_unlock(&inode
->i_lock
);
824 spin_unlock(&dentry
->d_lock
);
826 spin_unlock(&inode
->i_lock
);
828 EXPORT_SYMBOL(d_prune_aliases
);
830 static void shrink_dentry_list(struct list_head
*list
)
832 struct dentry
*dentry
, *parent
;
834 while (!list_empty(list
)) {
836 dentry
= list_entry(list
->prev
, struct dentry
, d_lru
);
837 spin_lock(&dentry
->d_lock
);
838 parent
= lock_parent(dentry
);
841 * The dispose list is isolated and dentries are not accounted
842 * to the LRU here, so we can simply remove it from the list
843 * here regardless of whether it is referenced or not.
845 d_shrink_del(dentry
);
848 * We found an inuse dentry which was not removed from
849 * the LRU because of laziness during lookup. Do not free it.
851 if ((int)dentry
->d_lockref
.count
> 0) {
852 spin_unlock(&dentry
->d_lock
);
854 spin_unlock(&parent
->d_lock
);
859 if (unlikely(dentry
->d_flags
& DCACHE_DENTRY_KILLED
)) {
860 bool can_free
= dentry
->d_flags
& DCACHE_MAY_FREE
;
861 spin_unlock(&dentry
->d_lock
);
863 spin_unlock(&parent
->d_lock
);
869 inode
= dentry
->d_inode
;
870 if (inode
&& unlikely(!spin_trylock(&inode
->i_lock
))) {
871 d_shrink_add(dentry
, list
);
872 spin_unlock(&dentry
->d_lock
);
874 spin_unlock(&parent
->d_lock
);
878 __dentry_kill(dentry
);
881 * We need to prune ancestors too. This is necessary to prevent
882 * quadratic behavior of shrink_dcache_parent(), but is also
883 * expected to be beneficial in reducing dentry cache
887 while (dentry
&& !lockref_put_or_lock(&dentry
->d_lockref
)) {
888 parent
= lock_parent(dentry
);
889 if (dentry
->d_lockref
.count
!= 1) {
890 dentry
->d_lockref
.count
--;
891 spin_unlock(&dentry
->d_lock
);
893 spin_unlock(&parent
->d_lock
);
896 inode
= dentry
->d_inode
; /* can't be NULL */
897 if (unlikely(!spin_trylock(&inode
->i_lock
))) {
898 spin_unlock(&dentry
->d_lock
);
900 spin_unlock(&parent
->d_lock
);
904 __dentry_kill(dentry
);
910 static enum lru_status
911 dentry_lru_isolate(struct list_head
*item
, spinlock_t
*lru_lock
, void *arg
)
913 struct list_head
*freeable
= arg
;
914 struct dentry
*dentry
= container_of(item
, struct dentry
, d_lru
);
918 * we are inverting the lru lock/dentry->d_lock here,
919 * so use a trylock. If we fail to get the lock, just skip
922 if (!spin_trylock(&dentry
->d_lock
))
926 * Referenced dentries are still in use. If they have active
927 * counts, just remove them from the LRU. Otherwise give them
928 * another pass through the LRU.
930 if (dentry
->d_lockref
.count
) {
931 d_lru_isolate(dentry
);
932 spin_unlock(&dentry
->d_lock
);
936 if (dentry
->d_flags
& DCACHE_REFERENCED
) {
937 dentry
->d_flags
&= ~DCACHE_REFERENCED
;
938 spin_unlock(&dentry
->d_lock
);
941 * The list move itself will be made by the common LRU code. At
942 * this point, we've dropped the dentry->d_lock but keep the
943 * lru lock. This is safe to do, since every list movement is
944 * protected by the lru lock even if both locks are held.
946 * This is guaranteed by the fact that all LRU management
947 * functions are intermediated by the LRU API calls like
948 * list_lru_add and list_lru_del. List movement in this file
949 * only ever occur through this functions or through callbacks
950 * like this one, that are called from the LRU API.
952 * The only exceptions to this are functions like
953 * shrink_dentry_list, and code that first checks for the
954 * DCACHE_SHRINK_LIST flag. Those are guaranteed to be
955 * operating only with stack provided lists after they are
956 * properly isolated from the main list. It is thus, always a
962 d_lru_shrink_move(dentry
, freeable
);
963 spin_unlock(&dentry
->d_lock
);
969 * prune_dcache_sb - shrink the dcache
971 * @nr_to_scan : number of entries to try to free
972 * @nid: which node to scan for freeable entities
974 * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
975 * done when we need more memory an called from the superblock shrinker
978 * This function may fail to free any resources if all the dentries are in
981 long prune_dcache_sb(struct super_block
*sb
, unsigned long nr_to_scan
,
987 freed
= list_lru_walk_node(&sb
->s_dentry_lru
, nid
, dentry_lru_isolate
,
988 &dispose
, &nr_to_scan
);
989 shrink_dentry_list(&dispose
);
993 static enum lru_status
dentry_lru_isolate_shrink(struct list_head
*item
,
994 spinlock_t
*lru_lock
, void *arg
)
996 struct list_head
*freeable
= arg
;
997 struct dentry
*dentry
= container_of(item
, struct dentry
, d_lru
);
1000 * we are inverting the lru lock/dentry->d_lock here,
1001 * so use a trylock. If we fail to get the lock, just skip
1004 if (!spin_trylock(&dentry
->d_lock
))
1007 d_lru_shrink_move(dentry
, freeable
);
1008 spin_unlock(&dentry
->d_lock
);
1015 * shrink_dcache_sb - shrink dcache for a superblock
1018 * Shrink the dcache for the specified super block. This is used to free
1019 * the dcache before unmounting a file system.
1021 void shrink_dcache_sb(struct super_block
*sb
)
1028 freed
= list_lru_walk(&sb
->s_dentry_lru
,
1029 dentry_lru_isolate_shrink
, &dispose
, UINT_MAX
);
1031 this_cpu_sub(nr_dentry_unused
, freed
);
1032 shrink_dentry_list(&dispose
);
1033 } while (freed
> 0);
1035 EXPORT_SYMBOL(shrink_dcache_sb
);
1038 * enum d_walk_ret - action to talke during tree walk
1039 * @D_WALK_CONTINUE: contrinue walk
1040 * @D_WALK_QUIT: quit walk
1041 * @D_WALK_NORETRY: quit when retry is needed
1042 * @D_WALK_SKIP: skip this dentry and its children
1052 * d_walk - walk the dentry tree
1053 * @parent: start of walk
1054 * @data: data passed to @enter() and @finish()
1055 * @enter: callback when first entering the dentry
1056 * @finish: callback when successfully finished the walk
1058 * The @enter() and @finish() callbacks are called with d_lock held.
1060 static void d_walk(struct dentry
*parent
, void *data
,
1061 enum d_walk_ret (*enter
)(void *, struct dentry
*),
1062 void (*finish
)(void *))
1064 struct dentry
*this_parent
;
1065 struct list_head
*next
;
1067 enum d_walk_ret ret
;
1071 read_seqbegin_or_lock(&rename_lock
, &seq
);
1072 this_parent
= parent
;
1073 spin_lock(&this_parent
->d_lock
);
1075 ret
= enter(data
, this_parent
);
1077 case D_WALK_CONTINUE
:
1082 case D_WALK_NORETRY
:
1087 next
= this_parent
->d_subdirs
.next
;
1089 while (next
!= &this_parent
->d_subdirs
) {
1090 struct list_head
*tmp
= next
;
1091 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_u
.d_child
);
1094 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
1096 ret
= enter(data
, dentry
);
1098 case D_WALK_CONTINUE
:
1101 spin_unlock(&dentry
->d_lock
);
1103 case D_WALK_NORETRY
:
1107 spin_unlock(&dentry
->d_lock
);
1111 if (!list_empty(&dentry
->d_subdirs
)) {
1112 spin_unlock(&this_parent
->d_lock
);
1113 spin_release(&dentry
->d_lock
.dep_map
, 1, _RET_IP_
);
1114 this_parent
= dentry
;
1115 spin_acquire(&this_parent
->d_lock
.dep_map
, 0, 1, _RET_IP_
);
1118 spin_unlock(&dentry
->d_lock
);
1121 * All done at this level ... ascend and resume the search.
1123 if (this_parent
!= parent
) {
1124 struct dentry
*child
= this_parent
;
1125 this_parent
= child
->d_parent
;
1128 spin_unlock(&child
->d_lock
);
1129 spin_lock(&this_parent
->d_lock
);
1132 * might go back up the wrong parent if we have had a rename
1135 if (this_parent
!= child
->d_parent
||
1136 (child
->d_flags
& DCACHE_DENTRY_KILLED
) ||
1137 need_seqretry(&rename_lock
, seq
)) {
1138 spin_unlock(&this_parent
->d_lock
);
1143 next
= child
->d_u
.d_child
.next
;
1146 if (need_seqretry(&rename_lock
, seq
)) {
1147 spin_unlock(&this_parent
->d_lock
);
1154 spin_unlock(&this_parent
->d_lock
);
1155 done_seqretry(&rename_lock
, seq
);
1166 * Search for at least 1 mount point in the dentry's subdirs.
1167 * We descend to the next level whenever the d_subdirs
1168 * list is non-empty and continue searching.
1171 static enum d_walk_ret
check_mount(void *data
, struct dentry
*dentry
)
1174 if (d_mountpoint(dentry
)) {
1178 return D_WALK_CONTINUE
;
1182 * have_submounts - check for mounts over a dentry
1183 * @parent: dentry to check.
1185 * Return true if the parent or its subdirectories contain
1188 int have_submounts(struct dentry
*parent
)
1192 d_walk(parent
, &ret
, check_mount
, NULL
);
1196 EXPORT_SYMBOL(have_submounts
);
1199 * Called by mount code to set a mountpoint and check if the mountpoint is
1200 * reachable (e.g. NFS can unhash a directory dentry and then the complete
1201 * subtree can become unreachable).
1203 * Only one of check_submounts_and_drop() and d_set_mounted() must succeed. For
1204 * this reason take rename_lock and d_lock on dentry and ancestors.
1206 int d_set_mounted(struct dentry
*dentry
)
1210 write_seqlock(&rename_lock
);
1211 for (p
= dentry
->d_parent
; !IS_ROOT(p
); p
= p
->d_parent
) {
1212 /* Need exclusion wrt. check_submounts_and_drop() */
1213 spin_lock(&p
->d_lock
);
1214 if (unlikely(d_unhashed(p
))) {
1215 spin_unlock(&p
->d_lock
);
1218 spin_unlock(&p
->d_lock
);
1220 spin_lock(&dentry
->d_lock
);
1221 if (!d_unlinked(dentry
)) {
1222 dentry
->d_flags
|= DCACHE_MOUNTED
;
1225 spin_unlock(&dentry
->d_lock
);
1227 write_sequnlock(&rename_lock
);
1232 * Search the dentry child list of the specified parent,
1233 * and move any unused dentries to the end of the unused
1234 * list for prune_dcache(). We descend to the next level
1235 * whenever the d_subdirs list is non-empty and continue
1238 * It returns zero iff there are no unused children,
1239 * otherwise it returns the number of children moved to
1240 * the end of the unused list. This may not be the total
1241 * number of unused children, because select_parent can
1242 * drop the lock and return early due to latency
1246 struct select_data
{
1247 struct dentry
*start
;
1248 struct list_head dispose
;
1252 static enum d_walk_ret
select_collect(void *_data
, struct dentry
*dentry
)
1254 struct select_data
*data
= _data
;
1255 enum d_walk_ret ret
= D_WALK_CONTINUE
;
1257 if (data
->start
== dentry
)
1260 if (dentry
->d_flags
& DCACHE_SHRINK_LIST
) {
1263 if (dentry
->d_flags
& DCACHE_LRU_LIST
)
1265 if (!dentry
->d_lockref
.count
) {
1266 d_shrink_add(dentry
, &data
->dispose
);
1271 * We can return to the caller if we have found some (this
1272 * ensures forward progress). We'll be coming back to find
1275 if (!list_empty(&data
->dispose
))
1276 ret
= need_resched() ? D_WALK_QUIT
: D_WALK_NORETRY
;
1282 * shrink_dcache_parent - prune dcache
1283 * @parent: parent of entries to prune
1285 * Prune the dcache to remove unused children of the parent dentry.
1287 void shrink_dcache_parent(struct dentry
*parent
)
1290 struct select_data data
;
1292 INIT_LIST_HEAD(&data
.dispose
);
1293 data
.start
= parent
;
1296 d_walk(parent
, &data
, select_collect
, NULL
);
1300 shrink_dentry_list(&data
.dispose
);
1304 EXPORT_SYMBOL(shrink_dcache_parent
);
1306 static enum d_walk_ret
umount_check(void *_data
, struct dentry
*dentry
)
1308 /* it has busy descendents; complain about those instead */
1309 if (!list_empty(&dentry
->d_subdirs
))
1310 return D_WALK_CONTINUE
;
1312 /* root with refcount 1 is fine */
1313 if (dentry
== _data
&& dentry
->d_lockref
.count
== 1)
1314 return D_WALK_CONTINUE
;
1316 printk(KERN_ERR
"BUG: Dentry %p{i=%lx,n=%pd} "
1317 " still in use (%d) [unmount of %s %s]\n",
1320 dentry
->d_inode
->i_ino
: 0UL,
1322 dentry
->d_lockref
.count
,
1323 dentry
->d_sb
->s_type
->name
,
1324 dentry
->d_sb
->s_id
);
1326 return D_WALK_CONTINUE
;
1329 static void do_one_tree(struct dentry
*dentry
)
1331 shrink_dcache_parent(dentry
);
1332 d_walk(dentry
, dentry
, umount_check
, NULL
);
1338 * destroy the dentries attached to a superblock on unmounting
1340 void shrink_dcache_for_umount(struct super_block
*sb
)
1342 struct dentry
*dentry
;
1344 WARN(down_read_trylock(&sb
->s_umount
), "s_umount should've been locked");
1346 dentry
= sb
->s_root
;
1348 do_one_tree(dentry
);
1350 while (!hlist_bl_empty(&sb
->s_anon
)) {
1351 dentry
= dget(hlist_bl_entry(hlist_bl_first(&sb
->s_anon
), struct dentry
, d_hash
));
1352 do_one_tree(dentry
);
1356 static enum d_walk_ret
check_and_collect(void *_data
, struct dentry
*dentry
)
1358 struct select_data
*data
= _data
;
1360 if (d_mountpoint(dentry
)) {
1361 data
->found
= -EBUSY
;
1365 return select_collect(_data
, dentry
);
1368 static void check_and_drop(void *_data
)
1370 struct select_data
*data
= _data
;
1372 if (d_mountpoint(data
->start
))
1373 data
->found
= -EBUSY
;
1375 __d_drop(data
->start
);
1379 * check_submounts_and_drop - prune dcache, check for submounts and drop
1381 * All done as a single atomic operation relative to has_unlinked_ancestor().
1382 * Returns 0 if successfully unhashed @parent. If there were submounts then
1385 * @dentry: dentry to prune and drop
1387 int check_submounts_and_drop(struct dentry
*dentry
)
1391 /* Negative dentries can be dropped without further checks */
1392 if (!dentry
->d_inode
) {
1398 struct select_data data
;
1400 INIT_LIST_HEAD(&data
.dispose
);
1401 data
.start
= dentry
;
1404 d_walk(dentry
, &data
, check_and_collect
, check_and_drop
);
1407 if (!list_empty(&data
.dispose
))
1408 shrink_dentry_list(&data
.dispose
);
1419 EXPORT_SYMBOL(check_submounts_and_drop
);
1422 * __d_alloc - allocate a dcache entry
1423 * @sb: filesystem it will belong to
1424 * @name: qstr of the name
1426 * Allocates a dentry. It returns %NULL if there is insufficient memory
1427 * available. On a success the dentry is returned. The name passed in is
1428 * copied and the copy passed in may be reused after this call.
1431 struct dentry
*__d_alloc(struct super_block
*sb
, const struct qstr
*name
)
1433 struct dentry
*dentry
;
1436 dentry
= kmem_cache_alloc(dentry_cache
, GFP_KERNEL
);
1441 * We guarantee that the inline name is always NUL-terminated.
1442 * This way the memcpy() done by the name switching in rename
1443 * will still always have a NUL at the end, even if we might
1444 * be overwriting an internal NUL character
1446 dentry
->d_iname
[DNAME_INLINE_LEN
-1] = 0;
1447 if (name
->len
> DNAME_INLINE_LEN
-1) {
1448 dname
= kmalloc(name
->len
+ 1, GFP_KERNEL
);
1450 kmem_cache_free(dentry_cache
, dentry
);
1454 dname
= dentry
->d_iname
;
1457 dentry
->d_name
.len
= name
->len
;
1458 dentry
->d_name
.hash
= name
->hash
;
1459 memcpy(dname
, name
->name
, name
->len
);
1460 dname
[name
->len
] = 0;
1462 /* Make sure we always see the terminating NUL character */
1464 dentry
->d_name
.name
= dname
;
1466 dentry
->d_lockref
.count
= 1;
1467 dentry
->d_flags
= 0;
1468 spin_lock_init(&dentry
->d_lock
);
1469 seqcount_init(&dentry
->d_seq
);
1470 dentry
->d_inode
= NULL
;
1471 dentry
->d_parent
= dentry
;
1473 dentry
->d_op
= NULL
;
1474 dentry
->d_fsdata
= NULL
;
1475 INIT_HLIST_BL_NODE(&dentry
->d_hash
);
1476 INIT_LIST_HEAD(&dentry
->d_lru
);
1477 INIT_LIST_HEAD(&dentry
->d_subdirs
);
1478 INIT_HLIST_NODE(&dentry
->d_alias
);
1479 INIT_LIST_HEAD(&dentry
->d_u
.d_child
);
1480 d_set_d_op(dentry
, dentry
->d_sb
->s_d_op
);
1482 this_cpu_inc(nr_dentry
);
1488 * d_alloc - allocate a dcache entry
1489 * @parent: parent of entry to allocate
1490 * @name: qstr of the name
1492 * Allocates a dentry. It returns %NULL if there is insufficient memory
1493 * available. On a success the dentry is returned. The name passed in is
1494 * copied and the copy passed in may be reused after this call.
1496 struct dentry
*d_alloc(struct dentry
* parent
, const struct qstr
*name
)
1498 struct dentry
*dentry
= __d_alloc(parent
->d_sb
, name
);
1502 spin_lock(&parent
->d_lock
);
1504 * don't need child lock because it is not subject
1505 * to concurrency here
1507 __dget_dlock(parent
);
1508 dentry
->d_parent
= parent
;
1509 list_add(&dentry
->d_u
.d_child
, &parent
->d_subdirs
);
1510 spin_unlock(&parent
->d_lock
);
1514 EXPORT_SYMBOL(d_alloc
);
1517 * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
1518 * @sb: the superblock
1519 * @name: qstr of the name
1521 * For a filesystem that just pins its dentries in memory and never
1522 * performs lookups at all, return an unhashed IS_ROOT dentry.
1524 struct dentry
*d_alloc_pseudo(struct super_block
*sb
, const struct qstr
*name
)
1526 return __d_alloc(sb
, name
);
1528 EXPORT_SYMBOL(d_alloc_pseudo
);
1530 struct dentry
*d_alloc_name(struct dentry
*parent
, const char *name
)
1535 q
.len
= strlen(name
);
1536 q
.hash
= full_name_hash(q
.name
, q
.len
);
1537 return d_alloc(parent
, &q
);
1539 EXPORT_SYMBOL(d_alloc_name
);
1541 void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
)
1543 WARN_ON_ONCE(dentry
->d_op
);
1544 WARN_ON_ONCE(dentry
->d_flags
& (DCACHE_OP_HASH
|
1546 DCACHE_OP_REVALIDATE
|
1547 DCACHE_OP_WEAK_REVALIDATE
|
1548 DCACHE_OP_DELETE
));
1553 dentry
->d_flags
|= DCACHE_OP_HASH
;
1555 dentry
->d_flags
|= DCACHE_OP_COMPARE
;
1556 if (op
->d_revalidate
)
1557 dentry
->d_flags
|= DCACHE_OP_REVALIDATE
;
1558 if (op
->d_weak_revalidate
)
1559 dentry
->d_flags
|= DCACHE_OP_WEAK_REVALIDATE
;
1561 dentry
->d_flags
|= DCACHE_OP_DELETE
;
1563 dentry
->d_flags
|= DCACHE_OP_PRUNE
;
1566 EXPORT_SYMBOL(d_set_d_op
);
1568 static unsigned d_flags_for_inode(struct inode
*inode
)
1570 unsigned add_flags
= DCACHE_FILE_TYPE
;
1573 return DCACHE_MISS_TYPE
;
1575 if (S_ISDIR(inode
->i_mode
)) {
1576 add_flags
= DCACHE_DIRECTORY_TYPE
;
1577 if (unlikely(!(inode
->i_opflags
& IOP_LOOKUP
))) {
1578 if (unlikely(!inode
->i_op
->lookup
))
1579 add_flags
= DCACHE_AUTODIR_TYPE
;
1581 inode
->i_opflags
|= IOP_LOOKUP
;
1583 } else if (unlikely(!(inode
->i_opflags
& IOP_NOFOLLOW
))) {
1584 if (unlikely(inode
->i_op
->follow_link
))
1585 add_flags
= DCACHE_SYMLINK_TYPE
;
1587 inode
->i_opflags
|= IOP_NOFOLLOW
;
1590 if (unlikely(IS_AUTOMOUNT(inode
)))
1591 add_flags
|= DCACHE_NEED_AUTOMOUNT
;
1595 static void __d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
1597 unsigned add_flags
= d_flags_for_inode(inode
);
1599 spin_lock(&dentry
->d_lock
);
1600 __d_set_type(dentry
, add_flags
);
1602 hlist_add_head(&dentry
->d_alias
, &inode
->i_dentry
);
1603 dentry
->d_inode
= inode
;
1604 dentry_rcuwalk_barrier(dentry
);
1605 spin_unlock(&dentry
->d_lock
);
1606 fsnotify_d_instantiate(dentry
, inode
);
1610 * d_instantiate - fill in inode information for a dentry
1611 * @entry: dentry to complete
1612 * @inode: inode to attach to this dentry
1614 * Fill in inode information in the entry.
1616 * This turns negative dentries into productive full members
1619 * NOTE! This assumes that the inode count has been incremented
1620 * (or otherwise set) by the caller to indicate that it is now
1621 * in use by the dcache.
1624 void d_instantiate(struct dentry
*entry
, struct inode
* inode
)
1626 BUG_ON(!hlist_unhashed(&entry
->d_alias
));
1628 spin_lock(&inode
->i_lock
);
1629 __d_instantiate(entry
, inode
);
1631 spin_unlock(&inode
->i_lock
);
1632 security_d_instantiate(entry
, inode
);
1634 EXPORT_SYMBOL(d_instantiate
);
1637 * d_instantiate_unique - instantiate a non-aliased dentry
1638 * @entry: dentry to instantiate
1639 * @inode: inode to attach to this dentry
1641 * Fill in inode information in the entry. On success, it returns NULL.
1642 * If an unhashed alias of "entry" already exists, then we return the
1643 * aliased dentry instead and drop one reference to inode.
1645 * Note that in order to avoid conflicts with rename() etc, the caller
1646 * had better be holding the parent directory semaphore.
1648 * This also assumes that the inode count has been incremented
1649 * (or otherwise set) by the caller to indicate that it is now
1650 * in use by the dcache.
1652 static struct dentry
*__d_instantiate_unique(struct dentry
*entry
,
1653 struct inode
*inode
)
1655 struct dentry
*alias
;
1656 int len
= entry
->d_name
.len
;
1657 const char *name
= entry
->d_name
.name
;
1658 unsigned int hash
= entry
->d_name
.hash
;
1661 __d_instantiate(entry
, NULL
);
1665 hlist_for_each_entry(alias
, &inode
->i_dentry
, d_alias
) {
1667 * Don't need alias->d_lock here, because aliases with
1668 * d_parent == entry->d_parent are not subject to name or
1669 * parent changes, because the parent inode i_mutex is held.
1671 if (alias
->d_name
.hash
!= hash
)
1673 if (alias
->d_parent
!= entry
->d_parent
)
1675 if (alias
->d_name
.len
!= len
)
1677 if (dentry_cmp(alias
, name
, len
))
1683 __d_instantiate(entry
, inode
);
1687 struct dentry
*d_instantiate_unique(struct dentry
*entry
, struct inode
*inode
)
1689 struct dentry
*result
;
1691 BUG_ON(!hlist_unhashed(&entry
->d_alias
));
1694 spin_lock(&inode
->i_lock
);
1695 result
= __d_instantiate_unique(entry
, inode
);
1697 spin_unlock(&inode
->i_lock
);
1700 security_d_instantiate(entry
, inode
);
1704 BUG_ON(!d_unhashed(result
));
1709 EXPORT_SYMBOL(d_instantiate_unique
);
1712 * d_instantiate_no_diralias - instantiate a non-aliased dentry
1713 * @entry: dentry to complete
1714 * @inode: inode to attach to this dentry
1716 * Fill in inode information in the entry. If a directory alias is found, then
1717 * return an error (and drop inode). Together with d_materialise_unique() this
1718 * guarantees that a directory inode may never have more than one alias.
1720 int d_instantiate_no_diralias(struct dentry
*entry
, struct inode
*inode
)
1722 BUG_ON(!hlist_unhashed(&entry
->d_alias
));
1724 spin_lock(&inode
->i_lock
);
1725 if (S_ISDIR(inode
->i_mode
) && !hlist_empty(&inode
->i_dentry
)) {
1726 spin_unlock(&inode
->i_lock
);
1730 __d_instantiate(entry
, inode
);
1731 spin_unlock(&inode
->i_lock
);
1732 security_d_instantiate(entry
, inode
);
1736 EXPORT_SYMBOL(d_instantiate_no_diralias
);
1738 struct dentry
*d_make_root(struct inode
*root_inode
)
1740 struct dentry
*res
= NULL
;
1743 static const struct qstr name
= QSTR_INIT("/", 1);
1745 res
= __d_alloc(root_inode
->i_sb
, &name
);
1747 d_instantiate(res
, root_inode
);
1753 EXPORT_SYMBOL(d_make_root
);
1755 static struct dentry
* __d_find_any_alias(struct inode
*inode
)
1757 struct dentry
*alias
;
1759 if (hlist_empty(&inode
->i_dentry
))
1761 alias
= hlist_entry(inode
->i_dentry
.first
, struct dentry
, d_alias
);
1767 * d_find_any_alias - find any alias for a given inode
1768 * @inode: inode to find an alias for
1770 * If any aliases exist for the given inode, take and return a
1771 * reference for one of them. If no aliases exist, return %NULL.
1773 struct dentry
*d_find_any_alias(struct inode
*inode
)
1777 spin_lock(&inode
->i_lock
);
1778 de
= __d_find_any_alias(inode
);
1779 spin_unlock(&inode
->i_lock
);
1782 EXPORT_SYMBOL(d_find_any_alias
);
1785 * d_obtain_alias - find or allocate a dentry for a given inode
1786 * @inode: inode to allocate the dentry for
1788 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1789 * similar open by handle operations. The returned dentry may be anonymous,
1790 * or may have a full name (if the inode was already in the cache).
1792 * When called on a directory inode, we must ensure that the inode only ever
1793 * has one dentry. If a dentry is found, that is returned instead of
1794 * allocating a new one.
1796 * On successful return, the reference to the inode has been transferred
1797 * to the dentry. In case of an error the reference on the inode is released.
1798 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1799 * be passed in and will be the error will be propagate to the return value,
1800 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
1802 struct dentry
*d_obtain_alias(struct inode
*inode
)
1804 static const struct qstr anonstring
= QSTR_INIT("/", 1);
1810 return ERR_PTR(-ESTALE
);
1812 return ERR_CAST(inode
);
1814 res
= d_find_any_alias(inode
);
1818 tmp
= __d_alloc(inode
->i_sb
, &anonstring
);
1820 res
= ERR_PTR(-ENOMEM
);
1824 spin_lock(&inode
->i_lock
);
1825 res
= __d_find_any_alias(inode
);
1827 spin_unlock(&inode
->i_lock
);
1832 /* attach a disconnected dentry */
1833 add_flags
= d_flags_for_inode(inode
) | DCACHE_DISCONNECTED
;
1835 spin_lock(&tmp
->d_lock
);
1836 tmp
->d_inode
= inode
;
1837 tmp
->d_flags
|= add_flags
;
1838 hlist_add_head(&tmp
->d_alias
, &inode
->i_dentry
);
1839 hlist_bl_lock(&tmp
->d_sb
->s_anon
);
1840 hlist_bl_add_head(&tmp
->d_hash
, &tmp
->d_sb
->s_anon
);
1841 hlist_bl_unlock(&tmp
->d_sb
->s_anon
);
1842 spin_unlock(&tmp
->d_lock
);
1843 spin_unlock(&inode
->i_lock
);
1844 security_d_instantiate(tmp
, inode
);
1849 if (res
&& !IS_ERR(res
))
1850 security_d_instantiate(res
, inode
);
1854 EXPORT_SYMBOL(d_obtain_alias
);
1857 * d_add_ci - lookup or allocate new dentry with case-exact name
1858 * @inode: the inode case-insensitive lookup has found
1859 * @dentry: the negative dentry that was passed to the parent's lookup func
1860 * @name: the case-exact name to be associated with the returned dentry
1862 * This is to avoid filling the dcache with case-insensitive names to the
1863 * same inode, only the actual correct case is stored in the dcache for
1864 * case-insensitive filesystems.
1866 * For a case-insensitive lookup match and if the the case-exact dentry
1867 * already exists in in the dcache, use it and return it.
1869 * If no entry exists with the exact case name, allocate new dentry with
1870 * the exact case, and return the spliced entry.
1872 struct dentry
*d_add_ci(struct dentry
*dentry
, struct inode
*inode
,
1875 struct dentry
*found
;
1879 * First check if a dentry matching the name already exists,
1880 * if not go ahead and create it now.
1882 found
= d_hash_and_lookup(dentry
->d_parent
, name
);
1883 if (unlikely(IS_ERR(found
)))
1886 new = d_alloc(dentry
->d_parent
, name
);
1888 found
= ERR_PTR(-ENOMEM
);
1892 found
= d_splice_alias(inode
, new);
1901 * If a matching dentry exists, and it's not negative use it.
1903 * Decrement the reference count to balance the iget() done
1906 if (found
->d_inode
) {
1907 if (unlikely(found
->d_inode
!= inode
)) {
1908 /* This can't happen because bad inodes are unhashed. */
1909 BUG_ON(!is_bad_inode(inode
));
1910 BUG_ON(!is_bad_inode(found
->d_inode
));
1917 * Negative dentry: instantiate it unless the inode is a directory and
1918 * already has a dentry.
1920 new = d_splice_alias(inode
, found
);
1931 EXPORT_SYMBOL(d_add_ci
);
1934 * Do the slow-case of the dentry name compare.
1936 * Unlike the dentry_cmp() function, we need to atomically
1937 * load the name and length information, so that the
1938 * filesystem can rely on them, and can use the 'name' and
1939 * 'len' information without worrying about walking off the
1940 * end of memory etc.
1942 * Thus the read_seqcount_retry() and the "duplicate" info
1943 * in arguments (the low-level filesystem should not look
1944 * at the dentry inode or name contents directly, since
1945 * rename can change them while we're in RCU mode).
1947 enum slow_d_compare
{
1953 static noinline
enum slow_d_compare
slow_dentry_cmp(
1954 const struct dentry
*parent
,
1955 struct dentry
*dentry
,
1957 const struct qstr
*name
)
1959 int tlen
= dentry
->d_name
.len
;
1960 const char *tname
= dentry
->d_name
.name
;
1962 if (read_seqcount_retry(&dentry
->d_seq
, seq
)) {
1964 return D_COMP_SEQRETRY
;
1966 if (parent
->d_op
->d_compare(parent
, dentry
, tlen
, tname
, name
))
1967 return D_COMP_NOMATCH
;
1972 * __d_lookup_rcu - search for a dentry (racy, store-free)
1973 * @parent: parent dentry
1974 * @name: qstr of name we wish to find
1975 * @seqp: returns d_seq value at the point where the dentry was found
1976 * Returns: dentry, or NULL
1978 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
1979 * resolution (store-free path walking) design described in
1980 * Documentation/filesystems/path-lookup.txt.
1982 * This is not to be used outside core vfs.
1984 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
1985 * held, and rcu_read_lock held. The returned dentry must not be stored into
1986 * without taking d_lock and checking d_seq sequence count against @seq
1989 * A refcount may be taken on the found dentry with the d_rcu_to_refcount
1992 * Alternatively, __d_lookup_rcu may be called again to look up the child of
1993 * the returned dentry, so long as its parent's seqlock is checked after the
1994 * child is looked up. Thus, an interlocking stepping of sequence lock checks
1995 * is formed, giving integrity down the path walk.
1997 * NOTE! The caller *has* to check the resulting dentry against the sequence
1998 * number we've returned before using any of the resulting dentry state!
2000 struct dentry
*__d_lookup_rcu(const struct dentry
*parent
,
2001 const struct qstr
*name
,
2004 u64 hashlen
= name
->hash_len
;
2005 const unsigned char *str
= name
->name
;
2006 struct hlist_bl_head
*b
= d_hash(parent
, hashlen_hash(hashlen
));
2007 struct hlist_bl_node
*node
;
2008 struct dentry
*dentry
;
2011 * Note: There is significant duplication with __d_lookup_rcu which is
2012 * required to prevent single threaded performance regressions
2013 * especially on architectures where smp_rmb (in seqcounts) are costly.
2014 * Keep the two functions in sync.
2018 * The hash list is protected using RCU.
2020 * Carefully use d_seq when comparing a candidate dentry, to avoid
2021 * races with d_move().
2023 * It is possible that concurrent renames can mess up our list
2024 * walk here and result in missing our dentry, resulting in the
2025 * false-negative result. d_lookup() protects against concurrent
2026 * renames using rename_lock seqlock.
2028 * See Documentation/filesystems/path-lookup.txt for more details.
2030 hlist_bl_for_each_entry_rcu(dentry
, node
, b
, d_hash
) {
2035 * The dentry sequence count protects us from concurrent
2036 * renames, and thus protects parent and name fields.
2038 * The caller must perform a seqcount check in order
2039 * to do anything useful with the returned dentry.
2041 * NOTE! We do a "raw" seqcount_begin here. That means that
2042 * we don't wait for the sequence count to stabilize if it
2043 * is in the middle of a sequence change. If we do the slow
2044 * dentry compare, we will do seqretries until it is stable,
2045 * and if we end up with a successful lookup, we actually
2046 * want to exit RCU lookup anyway.
2048 seq
= raw_seqcount_begin(&dentry
->d_seq
);
2049 if (dentry
->d_parent
!= parent
)
2051 if (d_unhashed(dentry
))
2054 if (unlikely(parent
->d_flags
& DCACHE_OP_COMPARE
)) {
2055 if (dentry
->d_name
.hash
!= hashlen_hash(hashlen
))
2058 switch (slow_dentry_cmp(parent
, dentry
, seq
, name
)) {
2061 case D_COMP_NOMATCH
:
2068 if (dentry
->d_name
.hash_len
!= hashlen
)
2071 if (!dentry_cmp(dentry
, str
, hashlen_len(hashlen
)))
2078 * d_lookup - search for a dentry
2079 * @parent: parent dentry
2080 * @name: qstr of name we wish to find
2081 * Returns: dentry, or NULL
2083 * d_lookup searches the children of the parent dentry for the name in
2084 * question. If the dentry is found its reference count is incremented and the
2085 * dentry is returned. The caller must use dput to free the entry when it has
2086 * finished using it. %NULL is returned if the dentry does not exist.
2088 struct dentry
*d_lookup(const struct dentry
*parent
, const struct qstr
*name
)
2090 struct dentry
*dentry
;
2094 seq
= read_seqbegin(&rename_lock
);
2095 dentry
= __d_lookup(parent
, name
);
2098 } while (read_seqretry(&rename_lock
, seq
));
2101 EXPORT_SYMBOL(d_lookup
);
2104 * __d_lookup - search for a dentry (racy)
2105 * @parent: parent dentry
2106 * @name: qstr of name we wish to find
2107 * Returns: dentry, or NULL
2109 * __d_lookup is like d_lookup, however it may (rarely) return a
2110 * false-negative result due to unrelated rename activity.
2112 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
2113 * however it must be used carefully, eg. with a following d_lookup in
2114 * the case of failure.
2116 * __d_lookup callers must be commented.
2118 struct dentry
*__d_lookup(const struct dentry
*parent
, const struct qstr
*name
)
2120 unsigned int len
= name
->len
;
2121 unsigned int hash
= name
->hash
;
2122 const unsigned char *str
= name
->name
;
2123 struct hlist_bl_head
*b
= d_hash(parent
, hash
);
2124 struct hlist_bl_node
*node
;
2125 struct dentry
*found
= NULL
;
2126 struct dentry
*dentry
;
2129 * Note: There is significant duplication with __d_lookup_rcu which is
2130 * required to prevent single threaded performance regressions
2131 * especially on architectures where smp_rmb (in seqcounts) are costly.
2132 * Keep the two functions in sync.
2136 * The hash list is protected using RCU.
2138 * Take d_lock when comparing a candidate dentry, to avoid races
2141 * It is possible that concurrent renames can mess up our list
2142 * walk here and result in missing our dentry, resulting in the
2143 * false-negative result. d_lookup() protects against concurrent
2144 * renames using rename_lock seqlock.
2146 * See Documentation/filesystems/path-lookup.txt for more details.
2150 hlist_bl_for_each_entry_rcu(dentry
, node
, b
, d_hash
) {
2152 if (dentry
->d_name
.hash
!= hash
)
2155 spin_lock(&dentry
->d_lock
);
2156 if (dentry
->d_parent
!= parent
)
2158 if (d_unhashed(dentry
))
2162 * It is safe to compare names since d_move() cannot
2163 * change the qstr (protected by d_lock).
2165 if (parent
->d_flags
& DCACHE_OP_COMPARE
) {
2166 int tlen
= dentry
->d_name
.len
;
2167 const char *tname
= dentry
->d_name
.name
;
2168 if (parent
->d_op
->d_compare(parent
, dentry
, tlen
, tname
, name
))
2171 if (dentry
->d_name
.len
!= len
)
2173 if (dentry_cmp(dentry
, str
, len
))
2177 dentry
->d_lockref
.count
++;
2179 spin_unlock(&dentry
->d_lock
);
2182 spin_unlock(&dentry
->d_lock
);
2190 * d_hash_and_lookup - hash the qstr then search for a dentry
2191 * @dir: Directory to search in
2192 * @name: qstr of name we wish to find
2194 * On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
2196 struct dentry
*d_hash_and_lookup(struct dentry
*dir
, struct qstr
*name
)
2199 * Check for a fs-specific hash function. Note that we must
2200 * calculate the standard hash first, as the d_op->d_hash()
2201 * routine may choose to leave the hash value unchanged.
2203 name
->hash
= full_name_hash(name
->name
, name
->len
);
2204 if (dir
->d_flags
& DCACHE_OP_HASH
) {
2205 int err
= dir
->d_op
->d_hash(dir
, name
);
2206 if (unlikely(err
< 0))
2207 return ERR_PTR(err
);
2209 return d_lookup(dir
, name
);
2211 EXPORT_SYMBOL(d_hash_and_lookup
);
2214 * d_validate - verify dentry provided from insecure source (deprecated)
2215 * @dentry: The dentry alleged to be valid child of @dparent
2216 * @dparent: The parent dentry (known to be valid)
2218 * An insecure source has sent us a dentry, here we verify it and dget() it.
2219 * This is used by ncpfs in its readdir implementation.
2220 * Zero is returned in the dentry is invalid.
2222 * This function is slow for big directories, and deprecated, do not use it.
2224 int d_validate(struct dentry
*dentry
, struct dentry
*dparent
)
2226 struct dentry
*child
;
2228 spin_lock(&dparent
->d_lock
);
2229 list_for_each_entry(child
, &dparent
->d_subdirs
, d_u
.d_child
) {
2230 if (dentry
== child
) {
2231 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
2232 __dget_dlock(dentry
);
2233 spin_unlock(&dentry
->d_lock
);
2234 spin_unlock(&dparent
->d_lock
);
2238 spin_unlock(&dparent
->d_lock
);
2242 EXPORT_SYMBOL(d_validate
);
2245 * When a file is deleted, we have two options:
2246 * - turn this dentry into a negative dentry
2247 * - unhash this dentry and free it.
2249 * Usually, we want to just turn this into
2250 * a negative dentry, but if anybody else is
2251 * currently using the dentry or the inode
2252 * we can't do that and we fall back on removing
2253 * it from the hash queues and waiting for
2254 * it to be deleted later when it has no users
2258 * d_delete - delete a dentry
2259 * @dentry: The dentry to delete
2261 * Turn the dentry into a negative dentry if possible, otherwise
2262 * remove it from the hash queues so it can be deleted later
2265 void d_delete(struct dentry
* dentry
)
2267 struct inode
*inode
;
2270 * Are we the only user?
2273 spin_lock(&dentry
->d_lock
);
2274 inode
= dentry
->d_inode
;
2275 isdir
= S_ISDIR(inode
->i_mode
);
2276 if (dentry
->d_lockref
.count
== 1) {
2277 if (!spin_trylock(&inode
->i_lock
)) {
2278 spin_unlock(&dentry
->d_lock
);
2282 dentry
->d_flags
&= ~DCACHE_CANT_MOUNT
;
2283 dentry_unlink_inode(dentry
);
2284 fsnotify_nameremove(dentry
, isdir
);
2288 if (!d_unhashed(dentry
))
2291 spin_unlock(&dentry
->d_lock
);
2293 fsnotify_nameremove(dentry
, isdir
);
2295 EXPORT_SYMBOL(d_delete
);
2297 static void __d_rehash(struct dentry
* entry
, struct hlist_bl_head
*b
)
2299 BUG_ON(!d_unhashed(entry
));
2301 entry
->d_flags
|= DCACHE_RCUACCESS
;
2302 hlist_bl_add_head_rcu(&entry
->d_hash
, b
);
2306 static void _d_rehash(struct dentry
* entry
)
2308 __d_rehash(entry
, d_hash(entry
->d_parent
, entry
->d_name
.hash
));
2312 * d_rehash - add an entry back to the hash
2313 * @entry: dentry to add to the hash
2315 * Adds a dentry to the hash according to its name.
2318 void d_rehash(struct dentry
* entry
)
2320 spin_lock(&entry
->d_lock
);
2322 spin_unlock(&entry
->d_lock
);
2324 EXPORT_SYMBOL(d_rehash
);
2327 * dentry_update_name_case - update case insensitive dentry with a new name
2328 * @dentry: dentry to be updated
2331 * Update a case insensitive dentry with new case of name.
2333 * dentry must have been returned by d_lookup with name @name. Old and new
2334 * name lengths must match (ie. no d_compare which allows mismatched name
2337 * Parent inode i_mutex must be held over d_lookup and into this call (to
2338 * keep renames and concurrent inserts, and readdir(2) away).
2340 void dentry_update_name_case(struct dentry
*dentry
, struct qstr
*name
)
2342 BUG_ON(!mutex_is_locked(&dentry
->d_parent
->d_inode
->i_mutex
));
2343 BUG_ON(dentry
->d_name
.len
!= name
->len
); /* d_lookup gives this */
2345 spin_lock(&dentry
->d_lock
);
2346 write_seqcount_begin(&dentry
->d_seq
);
2347 memcpy((unsigned char *)dentry
->d_name
.name
, name
->name
, name
->len
);
2348 write_seqcount_end(&dentry
->d_seq
);
2349 spin_unlock(&dentry
->d_lock
);
2351 EXPORT_SYMBOL(dentry_update_name_case
);
2353 static void switch_names(struct dentry
*dentry
, struct dentry
*target
)
2355 if (dname_external(target
)) {
2356 if (dname_external(dentry
)) {
2358 * Both external: swap the pointers
2360 swap(target
->d_name
.name
, dentry
->d_name
.name
);
2363 * dentry:internal, target:external. Steal target's
2364 * storage and make target internal.
2366 memcpy(target
->d_iname
, dentry
->d_name
.name
,
2367 dentry
->d_name
.len
+ 1);
2368 dentry
->d_name
.name
= target
->d_name
.name
;
2369 target
->d_name
.name
= target
->d_iname
;
2372 if (dname_external(dentry
)) {
2374 * dentry:external, target:internal. Give dentry's
2375 * storage to target and make dentry internal
2377 memcpy(dentry
->d_iname
, target
->d_name
.name
,
2378 target
->d_name
.len
+ 1);
2379 target
->d_name
.name
= dentry
->d_name
.name
;
2380 dentry
->d_name
.name
= dentry
->d_iname
;
2383 * Both are internal.
2386 BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN
, sizeof(long)));
2387 for (i
= 0; i
< DNAME_INLINE_LEN
/ sizeof(long); i
++) {
2388 swap(((long *) &dentry
->d_iname
)[i
],
2389 ((long *) &target
->d_iname
)[i
]);
2393 swap(dentry
->d_name
.len
, target
->d_name
.len
);
2396 static void dentry_lock_for_move(struct dentry
*dentry
, struct dentry
*target
)
2399 * XXXX: do we really need to take target->d_lock?
2401 if (IS_ROOT(dentry
) || dentry
->d_parent
== target
->d_parent
)
2402 spin_lock(&target
->d_parent
->d_lock
);
2404 if (d_ancestor(dentry
->d_parent
, target
->d_parent
)) {
2405 spin_lock(&dentry
->d_parent
->d_lock
);
2406 spin_lock_nested(&target
->d_parent
->d_lock
,
2407 DENTRY_D_LOCK_NESTED
);
2409 spin_lock(&target
->d_parent
->d_lock
);
2410 spin_lock_nested(&dentry
->d_parent
->d_lock
,
2411 DENTRY_D_LOCK_NESTED
);
2414 if (target
< dentry
) {
2415 spin_lock_nested(&target
->d_lock
, 2);
2416 spin_lock_nested(&dentry
->d_lock
, 3);
2418 spin_lock_nested(&dentry
->d_lock
, 2);
2419 spin_lock_nested(&target
->d_lock
, 3);
2423 static void dentry_unlock_parents_for_move(struct dentry
*dentry
,
2424 struct dentry
*target
)
2426 if (target
->d_parent
!= dentry
->d_parent
)
2427 spin_unlock(&dentry
->d_parent
->d_lock
);
2428 if (target
->d_parent
!= target
)
2429 spin_unlock(&target
->d_parent
->d_lock
);
2433 * When switching names, the actual string doesn't strictly have to
2434 * be preserved in the target - because we're dropping the target
2435 * anyway. As such, we can just do a simple memcpy() to copy over
2436 * the new name before we switch.
2438 * Note that we have to be a lot more careful about getting the hash
2439 * switched - we have to switch the hash value properly even if it
2440 * then no longer matches the actual (corrupted) string of the target.
2441 * The hash value has to match the hash queue that the dentry is on..
2444 * __d_move - move a dentry
2445 * @dentry: entry to move
2446 * @target: new dentry
2447 * @exchange: exchange the two dentries
2449 * Update the dcache to reflect the move of a file name. Negative
2450 * dcache entries should not be moved in this way. Caller must hold
2451 * rename_lock, the i_mutex of the source and target directories,
2452 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
2454 static void __d_move(struct dentry
*dentry
, struct dentry
*target
,
2457 if (!dentry
->d_inode
)
2458 printk(KERN_WARNING
"VFS: moving negative dcache entry\n");
2460 BUG_ON(d_ancestor(dentry
, target
));
2461 BUG_ON(d_ancestor(target
, dentry
));
2463 dentry_lock_for_move(dentry
, target
);
2465 write_seqcount_begin(&dentry
->d_seq
);
2466 write_seqcount_begin_nested(&target
->d_seq
, DENTRY_D_LOCK_NESTED
);
2468 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2471 * Move the dentry to the target hash queue. Don't bother checking
2472 * for the same hash queue because of how unlikely it is.
2475 __d_rehash(dentry
, d_hash(target
->d_parent
, target
->d_name
.hash
));
2478 * Unhash the target (d_delete() is not usable here). If exchanging
2479 * the two dentries, then rehash onto the other's hash queue.
2484 d_hash(dentry
->d_parent
, dentry
->d_name
.hash
));
2487 list_del(&dentry
->d_u
.d_child
);
2488 list_del(&target
->d_u
.d_child
);
2490 /* Switch the names.. */
2491 switch_names(dentry
, target
);
2492 swap(dentry
->d_name
.hash
, target
->d_name
.hash
);
2494 /* ... and switch the parents */
2495 if (IS_ROOT(dentry
)) {
2496 dentry
->d_parent
= target
->d_parent
;
2497 target
->d_parent
= target
;
2498 INIT_LIST_HEAD(&target
->d_u
.d_child
);
2500 swap(dentry
->d_parent
, target
->d_parent
);
2502 /* And add them back to the (new) parent lists */
2503 list_add(&target
->d_u
.d_child
, &target
->d_parent
->d_subdirs
);
2506 list_add(&dentry
->d_u
.d_child
, &dentry
->d_parent
->d_subdirs
);
2508 write_seqcount_end(&target
->d_seq
);
2509 write_seqcount_end(&dentry
->d_seq
);
2511 dentry_unlock_parents_for_move(dentry
, target
);
2513 fsnotify_d_move(target
);
2514 spin_unlock(&target
->d_lock
);
2515 fsnotify_d_move(dentry
);
2516 spin_unlock(&dentry
->d_lock
);
2520 * d_move - move a dentry
2521 * @dentry: entry to move
2522 * @target: new dentry
2524 * Update the dcache to reflect the move of a file name. Negative
2525 * dcache entries should not be moved in this way. See the locking
2526 * requirements for __d_move.
2528 void d_move(struct dentry
*dentry
, struct dentry
*target
)
2530 write_seqlock(&rename_lock
);
2531 __d_move(dentry
, target
, false);
2532 write_sequnlock(&rename_lock
);
2534 EXPORT_SYMBOL(d_move
);
2537 * d_exchange - exchange two dentries
2538 * @dentry1: first dentry
2539 * @dentry2: second dentry
2541 void d_exchange(struct dentry
*dentry1
, struct dentry
*dentry2
)
2543 write_seqlock(&rename_lock
);
2545 WARN_ON(!dentry1
->d_inode
);
2546 WARN_ON(!dentry2
->d_inode
);
2547 WARN_ON(IS_ROOT(dentry1
));
2548 WARN_ON(IS_ROOT(dentry2
));
2550 __d_move(dentry1
, dentry2
, true);
2552 write_sequnlock(&rename_lock
);
2556 * d_ancestor - search for an ancestor
2557 * @p1: ancestor dentry
2560 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2561 * an ancestor of p2, else NULL.
2563 struct dentry
*d_ancestor(struct dentry
*p1
, struct dentry
*p2
)
2567 for (p
= p2
; !IS_ROOT(p
); p
= p
->d_parent
) {
2568 if (p
->d_parent
== p1
)
2575 * This helper attempts to cope with remotely renamed directories
2577 * It assumes that the caller is already holding
2578 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
2580 * Note: If ever the locking in lock_rename() changes, then please
2581 * remember to update this too...
2583 static struct dentry
*__d_unalias(struct inode
*inode
,
2584 struct dentry
*dentry
, struct dentry
*alias
)
2586 struct mutex
*m1
= NULL
, *m2
= NULL
;
2587 struct dentry
*ret
= ERR_PTR(-EBUSY
);
2589 /* If alias and dentry share a parent, then no extra locks required */
2590 if (alias
->d_parent
== dentry
->d_parent
)
2593 /* See lock_rename() */
2594 if (!mutex_trylock(&dentry
->d_sb
->s_vfs_rename_mutex
))
2596 m1
= &dentry
->d_sb
->s_vfs_rename_mutex
;
2597 if (!mutex_trylock(&alias
->d_parent
->d_inode
->i_mutex
))
2599 m2
= &alias
->d_parent
->d_inode
->i_mutex
;
2601 if (likely(!d_mountpoint(alias
))) {
2602 __d_move(alias
, dentry
, false);
2606 spin_unlock(&inode
->i_lock
);
2615 * Prepare an anonymous dentry for life in the superblock's dentry tree as a
2616 * named dentry in place of the dentry to be replaced.
2617 * returns with anon->d_lock held!
2619 static void __d_materialise_dentry(struct dentry
*dentry
, struct dentry
*anon
)
2621 struct dentry
*dparent
;
2623 dentry_lock_for_move(anon
, dentry
);
2625 write_seqcount_begin(&dentry
->d_seq
);
2626 write_seqcount_begin_nested(&anon
->d_seq
, DENTRY_D_LOCK_NESTED
);
2628 dparent
= dentry
->d_parent
;
2630 switch_names(dentry
, anon
);
2631 swap(dentry
->d_name
.hash
, anon
->d_name
.hash
);
2633 dentry
->d_parent
= dentry
;
2634 list_del_init(&dentry
->d_u
.d_child
);
2635 anon
->d_parent
= dparent
;
2636 list_move(&anon
->d_u
.d_child
, &dparent
->d_subdirs
);
2638 write_seqcount_end(&dentry
->d_seq
);
2639 write_seqcount_end(&anon
->d_seq
);
2641 dentry_unlock_parents_for_move(anon
, dentry
);
2642 spin_unlock(&dentry
->d_lock
);
2644 /* anon->d_lock still locked, returns locked */
2648 * d_splice_alias - splice a disconnected dentry into the tree if one exists
2649 * @inode: the inode which may have a disconnected dentry
2650 * @dentry: a negative dentry which we want to point to the inode.
2652 * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and
2653 * DCACHE_DISCONNECTED), then d_move that in place of the given dentry
2654 * and return it, else simply d_add the inode to the dentry and return NULL.
2656 * This is needed in the lookup routine of any filesystem that is exportable
2657 * (via knfsd) so that we can build dcache paths to directories effectively.
2659 * If a dentry was found and moved, then it is returned. Otherwise NULL
2660 * is returned. This matches the expected return value of ->lookup.
2662 * Cluster filesystems may call this function with a negative, hashed dentry.
2663 * In that case, we know that the inode will be a regular file, and also this
2664 * will only occur during atomic_open. So we need to check for the dentry
2665 * being already hashed only in the final case.
2667 struct dentry
*d_splice_alias(struct inode
*inode
, struct dentry
*dentry
)
2669 struct dentry
*new = NULL
;
2672 return ERR_CAST(inode
);
2674 if (inode
&& S_ISDIR(inode
->i_mode
)) {
2675 spin_lock(&inode
->i_lock
);
2676 new = __d_find_alias(inode
, 1);
2678 BUG_ON(!(new->d_flags
& DCACHE_DISCONNECTED
));
2679 write_seqlock(&rename_lock
);
2680 __d_materialise_dentry(dentry
, new);
2681 write_sequnlock(&rename_lock
);
2684 spin_unlock(&new->d_lock
);
2685 spin_unlock(&inode
->i_lock
);
2686 security_d_instantiate(new, inode
);
2689 /* already taking inode->i_lock, so d_add() by hand */
2690 __d_instantiate(dentry
, inode
);
2691 spin_unlock(&inode
->i_lock
);
2692 security_d_instantiate(dentry
, inode
);
2696 d_instantiate(dentry
, inode
);
2697 if (d_unhashed(dentry
))
2702 EXPORT_SYMBOL(d_splice_alias
);
2705 * d_materialise_unique - introduce an inode into the tree
2706 * @dentry: candidate dentry
2707 * @inode: inode to bind to the dentry, to which aliases may be attached
2709 * Introduces an dentry into the tree, substituting an extant disconnected
2710 * root directory alias in its place if there is one. Caller must hold the
2711 * i_mutex of the parent directory.
2713 struct dentry
*d_materialise_unique(struct dentry
*dentry
, struct inode
*inode
)
2715 struct dentry
*actual
;
2717 BUG_ON(!d_unhashed(dentry
));
2721 __d_instantiate(dentry
, NULL
);
2726 spin_lock(&inode
->i_lock
);
2728 if (S_ISDIR(inode
->i_mode
)) {
2729 struct dentry
*alias
;
2731 /* Does an aliased dentry already exist? */
2732 alias
= __d_find_alias(inode
, 0);
2735 write_seqlock(&rename_lock
);
2737 if (d_ancestor(alias
, dentry
)) {
2738 /* Check for loops */
2739 actual
= ERR_PTR(-ELOOP
);
2740 spin_unlock(&inode
->i_lock
);
2741 } else if (IS_ROOT(alias
)) {
2742 /* Is this an anonymous mountpoint that we
2743 * could splice into our tree? */
2744 __d_materialise_dentry(dentry
, alias
);
2745 write_sequnlock(&rename_lock
);
2749 /* Nope, but we must(!) avoid directory
2750 * aliasing. This drops inode->i_lock */
2751 actual
= __d_unalias(inode
, dentry
, alias
);
2753 write_sequnlock(&rename_lock
);
2754 if (IS_ERR(actual
)) {
2755 if (PTR_ERR(actual
) == -ELOOP
)
2756 pr_warn_ratelimited(
2757 "VFS: Lookup of '%s' in %s %s"
2758 " would have caused loop\n",
2759 dentry
->d_name
.name
,
2760 inode
->i_sb
->s_type
->name
,
2768 /* Add a unique reference */
2769 actual
= __d_instantiate_unique(dentry
, inode
);
2773 BUG_ON(!d_unhashed(actual
));
2775 spin_lock(&actual
->d_lock
);
2778 spin_unlock(&actual
->d_lock
);
2779 spin_unlock(&inode
->i_lock
);
2781 if (actual
== dentry
) {
2782 security_d_instantiate(dentry
, inode
);
2789 EXPORT_SYMBOL_GPL(d_materialise_unique
);
2791 static int prepend(char **buffer
, int *buflen
, const char *str
, int namelen
)
2795 return -ENAMETOOLONG
;
2797 memcpy(*buffer
, str
, namelen
);
2802 * prepend_name - prepend a pathname in front of current buffer pointer
2803 * @buffer: buffer pointer
2804 * @buflen: allocated length of the buffer
2805 * @name: name string and length qstr structure
2807 * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to
2808 * make sure that either the old or the new name pointer and length are
2809 * fetched. However, there may be mismatch between length and pointer.
2810 * The length cannot be trusted, we need to copy it byte-by-byte until
2811 * the length is reached or a null byte is found. It also prepends "/" at
2812 * the beginning of the name. The sequence number check at the caller will
2813 * retry it again when a d_move() does happen. So any garbage in the buffer
2814 * due to mismatched pointer and length will be discarded.
2816 static int prepend_name(char **buffer
, int *buflen
, struct qstr
*name
)
2818 const char *dname
= ACCESS_ONCE(name
->name
);
2819 u32 dlen
= ACCESS_ONCE(name
->len
);
2822 *buflen
-= dlen
+ 1;
2824 return -ENAMETOOLONG
;
2825 p
= *buffer
-= dlen
+ 1;
2837 * prepend_path - Prepend path string to a buffer
2838 * @path: the dentry/vfsmount to report
2839 * @root: root vfsmnt/dentry
2840 * @buffer: pointer to the end of the buffer
2841 * @buflen: pointer to buffer length
2843 * The function will first try to write out the pathname without taking any
2844 * lock other than the RCU read lock to make sure that dentries won't go away.
2845 * It only checks the sequence number of the global rename_lock as any change
2846 * in the dentry's d_seq will be preceded by changes in the rename_lock
2847 * sequence number. If the sequence number had been changed, it will restart
2848 * the whole pathname back-tracing sequence again by taking the rename_lock.
2849 * In this case, there is no need to take the RCU read lock as the recursive
2850 * parent pointer references will keep the dentry chain alive as long as no
2851 * rename operation is performed.
2853 static int prepend_path(const struct path
*path
,
2854 const struct path
*root
,
2855 char **buffer
, int *buflen
)
2857 struct dentry
*dentry
;
2858 struct vfsmount
*vfsmnt
;
2861 unsigned seq
, m_seq
= 0;
2867 read_seqbegin_or_lock(&mount_lock
, &m_seq
);
2874 dentry
= path
->dentry
;
2876 mnt
= real_mount(vfsmnt
);
2877 read_seqbegin_or_lock(&rename_lock
, &seq
);
2878 while (dentry
!= root
->dentry
|| vfsmnt
!= root
->mnt
) {
2879 struct dentry
* parent
;
2881 if (dentry
== vfsmnt
->mnt_root
|| IS_ROOT(dentry
)) {
2882 struct mount
*parent
= ACCESS_ONCE(mnt
->mnt_parent
);
2884 if (mnt
!= parent
) {
2885 dentry
= ACCESS_ONCE(mnt
->mnt_mountpoint
);
2891 * Filesystems needing to implement special "root names"
2892 * should do so with ->d_dname()
2894 if (IS_ROOT(dentry
) &&
2895 (dentry
->d_name
.len
!= 1 ||
2896 dentry
->d_name
.name
[0] != '/')) {
2897 WARN(1, "Root dentry has weird name <%.*s>\n",
2898 (int) dentry
->d_name
.len
,
2899 dentry
->d_name
.name
);
2902 error
= is_mounted(vfsmnt
) ? 1 : 2;
2905 parent
= dentry
->d_parent
;
2907 error
= prepend_name(&bptr
, &blen
, &dentry
->d_name
);
2915 if (need_seqretry(&rename_lock
, seq
)) {
2919 done_seqretry(&rename_lock
, seq
);
2923 if (need_seqretry(&mount_lock
, m_seq
)) {
2927 done_seqretry(&mount_lock
, m_seq
);
2929 if (error
>= 0 && bptr
== *buffer
) {
2931 error
= -ENAMETOOLONG
;
2941 * __d_path - return the path of a dentry
2942 * @path: the dentry/vfsmount to report
2943 * @root: root vfsmnt/dentry
2944 * @buf: buffer to return value in
2945 * @buflen: buffer length
2947 * Convert a dentry into an ASCII path name.
2949 * Returns a pointer into the buffer or an error code if the
2950 * path was too long.
2952 * "buflen" should be positive.
2954 * If the path is not reachable from the supplied root, return %NULL.
2956 char *__d_path(const struct path
*path
,
2957 const struct path
*root
,
2958 char *buf
, int buflen
)
2960 char *res
= buf
+ buflen
;
2963 prepend(&res
, &buflen
, "\0", 1);
2964 error
= prepend_path(path
, root
, &res
, &buflen
);
2967 return ERR_PTR(error
);
2973 char *d_absolute_path(const struct path
*path
,
2974 char *buf
, int buflen
)
2976 struct path root
= {};
2977 char *res
= buf
+ buflen
;
2980 prepend(&res
, &buflen
, "\0", 1);
2981 error
= prepend_path(path
, &root
, &res
, &buflen
);
2986 return ERR_PTR(error
);
2991 * same as __d_path but appends "(deleted)" for unlinked files.
2993 static int path_with_deleted(const struct path
*path
,
2994 const struct path
*root
,
2995 char **buf
, int *buflen
)
2997 prepend(buf
, buflen
, "\0", 1);
2998 if (d_unlinked(path
->dentry
)) {
2999 int error
= prepend(buf
, buflen
, " (deleted)", 10);
3004 return prepend_path(path
, root
, buf
, buflen
);
3007 static int prepend_unreachable(char **buffer
, int *buflen
)
3009 return prepend(buffer
, buflen
, "(unreachable)", 13);
3012 static void get_fs_root_rcu(struct fs_struct
*fs
, struct path
*root
)
3017 seq
= read_seqcount_begin(&fs
->seq
);
3019 } while (read_seqcount_retry(&fs
->seq
, seq
));
3023 * d_path - return the path of a dentry
3024 * @path: path to report
3025 * @buf: buffer to return value in
3026 * @buflen: buffer length
3028 * Convert a dentry into an ASCII path name. If the entry has been deleted
3029 * the string " (deleted)" is appended. Note that this is ambiguous.
3031 * Returns a pointer into the buffer or an error code if the path was
3032 * too long. Note: Callers should use the returned pointer, not the passed
3033 * in buffer, to use the name! The implementation often starts at an offset
3034 * into the buffer, and may leave 0 bytes at the start.
3036 * "buflen" should be positive.
3038 char *d_path(const struct path
*path
, char *buf
, int buflen
)
3040 char *res
= buf
+ buflen
;
3045 * We have various synthetic filesystems that never get mounted. On
3046 * these filesystems dentries are never used for lookup purposes, and
3047 * thus don't need to be hashed. They also don't need a name until a
3048 * user wants to identify the object in /proc/pid/fd/. The little hack
3049 * below allows us to generate a name for these objects on demand:
3051 * Some pseudo inodes are mountable. When they are mounted
3052 * path->dentry == path->mnt->mnt_root. In that case don't call d_dname
3053 * and instead have d_path return the mounted path.
3055 if (path
->dentry
->d_op
&& path
->dentry
->d_op
->d_dname
&&
3056 (!IS_ROOT(path
->dentry
) || path
->dentry
!= path
->mnt
->mnt_root
))
3057 return path
->dentry
->d_op
->d_dname(path
->dentry
, buf
, buflen
);
3060 get_fs_root_rcu(current
->fs
, &root
);
3061 error
= path_with_deleted(path
, &root
, &res
, &buflen
);
3065 res
= ERR_PTR(error
);
3068 EXPORT_SYMBOL(d_path
);
3071 * Helper function for dentry_operations.d_dname() members
3073 char *dynamic_dname(struct dentry
*dentry
, char *buffer
, int buflen
,
3074 const char *fmt
, ...)
3080 va_start(args
, fmt
);
3081 sz
= vsnprintf(temp
, sizeof(temp
), fmt
, args
) + 1;
3084 if (sz
> sizeof(temp
) || sz
> buflen
)
3085 return ERR_PTR(-ENAMETOOLONG
);
3087 buffer
+= buflen
- sz
;
3088 return memcpy(buffer
, temp
, sz
);
3091 char *simple_dname(struct dentry
*dentry
, char *buffer
, int buflen
)
3093 char *end
= buffer
+ buflen
;
3094 /* these dentries are never renamed, so d_lock is not needed */
3095 if (prepend(&end
, &buflen
, " (deleted)", 11) ||
3096 prepend(&end
, &buflen
, dentry
->d_name
.name
, dentry
->d_name
.len
) ||
3097 prepend(&end
, &buflen
, "/", 1))
3098 end
= ERR_PTR(-ENAMETOOLONG
);
3101 EXPORT_SYMBOL(simple_dname
);
3104 * Write full pathname from the root of the filesystem into the buffer.
3106 static char *__dentry_path(struct dentry
*d
, char *buf
, int buflen
)
3108 struct dentry
*dentry
;
3121 prepend(&end
, &len
, "\0", 1);
3125 read_seqbegin_or_lock(&rename_lock
, &seq
);
3126 while (!IS_ROOT(dentry
)) {
3127 struct dentry
*parent
= dentry
->d_parent
;
3130 error
= prepend_name(&end
, &len
, &dentry
->d_name
);
3139 if (need_seqretry(&rename_lock
, seq
)) {
3143 done_seqretry(&rename_lock
, seq
);
3148 return ERR_PTR(-ENAMETOOLONG
);
3151 char *dentry_path_raw(struct dentry
*dentry
, char *buf
, int buflen
)
3153 return __dentry_path(dentry
, buf
, buflen
);
3155 EXPORT_SYMBOL(dentry_path_raw
);
3157 char *dentry_path(struct dentry
*dentry
, char *buf
, int buflen
)
3162 if (d_unlinked(dentry
)) {
3164 if (prepend(&p
, &buflen
, "//deleted", 10) != 0)
3168 retval
= __dentry_path(dentry
, buf
, buflen
);
3169 if (!IS_ERR(retval
) && p
)
3170 *p
= '/'; /* restore '/' overriden with '\0' */
3173 return ERR_PTR(-ENAMETOOLONG
);
3176 static void get_fs_root_and_pwd_rcu(struct fs_struct
*fs
, struct path
*root
,
3182 seq
= read_seqcount_begin(&fs
->seq
);
3185 } while (read_seqcount_retry(&fs
->seq
, seq
));
3189 * NOTE! The user-level library version returns a
3190 * character pointer. The kernel system call just
3191 * returns the length of the buffer filled (which
3192 * includes the ending '\0' character), or a negative
3193 * error value. So libc would do something like
3195 * char *getcwd(char * buf, size_t size)
3199 * retval = sys_getcwd(buf, size);
3206 SYSCALL_DEFINE2(getcwd
, char __user
*, buf
, unsigned long, size
)
3209 struct path pwd
, root
;
3210 char *page
= __getname();
3216 get_fs_root_and_pwd_rcu(current
->fs
, &root
, &pwd
);
3219 if (!d_unlinked(pwd
.dentry
)) {
3221 char *cwd
= page
+ PATH_MAX
;
3222 int buflen
= PATH_MAX
;
3224 prepend(&cwd
, &buflen
, "\0", 1);
3225 error
= prepend_path(&pwd
, &root
, &cwd
, &buflen
);
3231 /* Unreachable from current root */
3233 error
= prepend_unreachable(&cwd
, &buflen
);
3239 len
= PATH_MAX
+ page
- cwd
;
3242 if (copy_to_user(buf
, cwd
, len
))
3255 * Test whether new_dentry is a subdirectory of old_dentry.
3257 * Trivially implemented using the dcache structure
3261 * is_subdir - is new dentry a subdirectory of old_dentry
3262 * @new_dentry: new dentry
3263 * @old_dentry: old dentry
3265 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
3266 * Returns 0 otherwise.
3267 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
3270 int is_subdir(struct dentry
*new_dentry
, struct dentry
*old_dentry
)
3275 if (new_dentry
== old_dentry
)
3279 /* for restarting inner loop in case of seq retry */
3280 seq
= read_seqbegin(&rename_lock
);
3282 * Need rcu_readlock to protect against the d_parent trashing
3286 if (d_ancestor(old_dentry
, new_dentry
))
3291 } while (read_seqretry(&rename_lock
, seq
));
3296 static enum d_walk_ret
d_genocide_kill(void *data
, struct dentry
*dentry
)
3298 struct dentry
*root
= data
;
3299 if (dentry
!= root
) {
3300 if (d_unhashed(dentry
) || !dentry
->d_inode
)
3303 if (!(dentry
->d_flags
& DCACHE_GENOCIDE
)) {
3304 dentry
->d_flags
|= DCACHE_GENOCIDE
;
3305 dentry
->d_lockref
.count
--;
3308 return D_WALK_CONTINUE
;
3311 void d_genocide(struct dentry
*parent
)
3313 d_walk(parent
, parent
, d_genocide_kill
, NULL
);
3316 void d_tmpfile(struct dentry
*dentry
, struct inode
*inode
)
3318 inode_dec_link_count(inode
);
3319 BUG_ON(dentry
->d_name
.name
!= dentry
->d_iname
||
3320 !hlist_unhashed(&dentry
->d_alias
) ||
3321 !d_unlinked(dentry
));
3322 spin_lock(&dentry
->d_parent
->d_lock
);
3323 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
3324 dentry
->d_name
.len
= sprintf(dentry
->d_iname
, "#%llu",
3325 (unsigned long long)inode
->i_ino
);
3326 spin_unlock(&dentry
->d_lock
);
3327 spin_unlock(&dentry
->d_parent
->d_lock
);
3328 d_instantiate(dentry
, inode
);
3330 EXPORT_SYMBOL(d_tmpfile
);
3332 static __initdata
unsigned long dhash_entries
;
3333 static int __init
set_dhash_entries(char *str
)
3337 dhash_entries
= simple_strtoul(str
, &str
, 0);
3340 __setup("dhash_entries=", set_dhash_entries
);
3342 static void __init
dcache_init_early(void)
3346 /* If hashes are distributed across NUMA nodes, defer
3347 * hash allocation until vmalloc space is available.
3353 alloc_large_system_hash("Dentry cache",
3354 sizeof(struct hlist_bl_head
),
3363 for (loop
= 0; loop
< (1U << d_hash_shift
); loop
++)
3364 INIT_HLIST_BL_HEAD(dentry_hashtable
+ loop
);
3367 static void __init
dcache_init(void)
3372 * A constructor could be added for stable state like the lists,
3373 * but it is probably not worth it because of the cache nature
3376 dentry_cache
= KMEM_CACHE(dentry
,
3377 SLAB_RECLAIM_ACCOUNT
|SLAB_PANIC
|SLAB_MEM_SPREAD
);
3379 /* Hash may have been set up in dcache_init_early */
3384 alloc_large_system_hash("Dentry cache",
3385 sizeof(struct hlist_bl_head
),
3394 for (loop
= 0; loop
< (1U << d_hash_shift
); loop
++)
3395 INIT_HLIST_BL_HEAD(dentry_hashtable
+ loop
);
3398 /* SLAB cache for __getname() consumers */
3399 struct kmem_cache
*names_cachep __read_mostly
;
3400 EXPORT_SYMBOL(names_cachep
);
3402 EXPORT_SYMBOL(d_genocide
);
3404 void __init
vfs_caches_init_early(void)
3406 dcache_init_early();
3410 void __init
vfs_caches_init(unsigned long mempages
)
3412 unsigned long reserve
;
3414 /* Base hash sizes on available memory, with a reserve equal to
3415 150% of current kernel size */
3417 reserve
= min((mempages
- nr_free_pages()) * 3/2, mempages
- 1);
3418 mempages
-= reserve
;
3420 names_cachep
= kmem_cache_create("names_cache", PATH_MAX
, 0,
3421 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
3425 files_init(mempages
);