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>
41 #include <linux/kasan.h>
48 * dcache->d_inode->i_lock protects:
49 * - i_dentry, d_u.d_alias, d_inode of aliases
50 * dcache_hash_bucket lock protects:
51 * - the dcache hash table
52 * s_anon bl list spinlock protects:
53 * - the s_anon list (see __d_drop)
54 * dentry->d_sb->s_dentry_lru_lock protects:
55 * - the dcache lru lists and counters
62 * - d_parent and d_subdirs
63 * - childrens' d_child and d_parent
64 * - d_u.d_alias, d_inode
67 * dentry->d_inode->i_lock
69 * dentry->d_sb->s_dentry_lru_lock
70 * dcache_hash_bucket lock
73 * If there is an ancestor relationship:
74 * dentry->d_parent->...->d_parent->d_lock
76 * dentry->d_parent->d_lock
79 * If no ancestor relationship:
80 * if (dentry1 < dentry2)
84 int sysctl_vfs_cache_pressure __read_mostly
= 100;
85 EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure
);
87 __cacheline_aligned_in_smp
DEFINE_SEQLOCK(rename_lock
);
89 EXPORT_SYMBOL(rename_lock
);
91 static struct kmem_cache
*dentry_cache __read_mostly
;
94 * This is the single most critical data structure when it comes
95 * to the dcache: the hashtable for lookups. Somebody should try
96 * to make this good - I've just made it work.
98 * This hash-function tries to avoid losing too many bits of hash
99 * information, yet avoid using a prime hash-size or similar.
102 static unsigned int d_hash_mask __read_mostly
;
103 static unsigned int d_hash_shift __read_mostly
;
105 static struct hlist_bl_head
*dentry_hashtable __read_mostly
;
107 static inline struct hlist_bl_head
*d_hash(const struct dentry
*parent
,
110 hash
+= (unsigned long) parent
/ L1_CACHE_BYTES
;
111 return dentry_hashtable
+ hash_32(hash
, d_hash_shift
);
114 /* Statistics gathering. */
115 struct dentry_stat_t dentry_stat
= {
119 static DEFINE_PER_CPU(long, nr_dentry
);
120 static DEFINE_PER_CPU(long, nr_dentry_unused
);
122 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
125 * Here we resort to our own counters instead of using generic per-cpu counters
126 * for consistency with what the vfs inode code does. We are expected to harvest
127 * better code and performance by having our own specialized counters.
129 * Please note that the loop is done over all possible CPUs, not over all online
130 * CPUs. The reason for this is that we don't want to play games with CPUs going
131 * on and off. If one of them goes off, we will just keep their counters.
133 * glommer: See cffbc8a for details, and if you ever intend to change this,
134 * please update all vfs counters to match.
136 static long get_nr_dentry(void)
140 for_each_possible_cpu(i
)
141 sum
+= per_cpu(nr_dentry
, i
);
142 return sum
< 0 ? 0 : sum
;
145 static long get_nr_dentry_unused(void)
149 for_each_possible_cpu(i
)
150 sum
+= per_cpu(nr_dentry_unused
, i
);
151 return sum
< 0 ? 0 : sum
;
154 int proc_nr_dentry(struct ctl_table
*table
, int write
, void __user
*buffer
,
155 size_t *lenp
, loff_t
*ppos
)
157 dentry_stat
.nr_dentry
= get_nr_dentry();
158 dentry_stat
.nr_unused
= get_nr_dentry_unused();
159 return proc_doulongvec_minmax(table
, write
, buffer
, lenp
, ppos
);
164 * Compare 2 name strings, return 0 if they match, otherwise non-zero.
165 * The strings are both count bytes long, and count is non-zero.
167 #ifdef CONFIG_DCACHE_WORD_ACCESS
169 #include <asm/word-at-a-time.h>
171 * NOTE! 'cs' and 'scount' come from a dentry, so it has a
172 * aligned allocation for this particular component. We don't
173 * strictly need the load_unaligned_zeropad() safety, but it
174 * doesn't hurt either.
176 * In contrast, 'ct' and 'tcount' can be from a pathname, and do
177 * need the careful unaligned handling.
179 static inline int dentry_string_cmp(const unsigned char *cs
, const unsigned char *ct
, unsigned tcount
)
181 unsigned long a
,b
,mask
;
184 a
= *(unsigned long *)cs
;
185 b
= load_unaligned_zeropad(ct
);
186 if (tcount
< sizeof(unsigned long))
188 if (unlikely(a
!= b
))
190 cs
+= sizeof(unsigned long);
191 ct
+= sizeof(unsigned long);
192 tcount
-= sizeof(unsigned long);
196 mask
= bytemask_from_count(tcount
);
197 return unlikely(!!((a
^ b
) & mask
));
202 static inline int dentry_string_cmp(const unsigned char *cs
, const unsigned char *ct
, unsigned tcount
)
216 static inline int dentry_cmp(const struct dentry
*dentry
, const unsigned char *ct
, unsigned tcount
)
218 const unsigned char *cs
;
220 * Be careful about RCU walk racing with rename:
221 * use ACCESS_ONCE to fetch the name pointer.
223 * NOTE! Even if a rename will mean that the length
224 * was not loaded atomically, we don't care. The
225 * RCU walk will check the sequence count eventually,
226 * and catch it. And we won't overrun the buffer,
227 * because we're reading the name pointer atomically,
228 * and a dentry name is guaranteed to be properly
229 * terminated with a NUL byte.
231 * End result: even if 'len' is wrong, we'll exit
232 * early because the data cannot match (there can
233 * be no NUL in the ct/tcount data)
235 cs
= ACCESS_ONCE(dentry
->d_name
.name
);
236 smp_read_barrier_depends();
237 return dentry_string_cmp(cs
, ct
, tcount
);
240 struct external_name
{
243 struct rcu_head head
;
245 unsigned char name
[];
248 static inline struct external_name
*external_name(struct dentry
*dentry
)
250 return container_of(dentry
->d_name
.name
, struct external_name
, name
[0]);
253 static void __d_free(struct rcu_head
*head
)
255 struct dentry
*dentry
= container_of(head
, struct dentry
, d_u
.d_rcu
);
257 kmem_cache_free(dentry_cache
, dentry
);
260 static void __d_free_external(struct rcu_head
*head
)
262 struct dentry
*dentry
= container_of(head
, struct dentry
, d_u
.d_rcu
);
263 kfree(external_name(dentry
));
264 kmem_cache_free(dentry_cache
, dentry
);
267 static inline int dname_external(const struct dentry
*dentry
)
269 return dentry
->d_name
.name
!= dentry
->d_iname
;
273 * Make sure other CPUs see the inode attached before the type is set.
275 static inline void __d_set_inode_and_type(struct dentry
*dentry
,
281 dentry
->d_inode
= inode
;
283 flags
= READ_ONCE(dentry
->d_flags
);
284 flags
&= ~(DCACHE_ENTRY_TYPE
| DCACHE_FALLTHRU
);
286 WRITE_ONCE(dentry
->d_flags
, flags
);
290 * Ideally, we want to make sure that other CPUs see the flags cleared before
291 * the inode is detached, but this is really a violation of RCU principles
292 * since the ordering suggests we should always set inode before flags.
294 * We should instead replace or discard the entire dentry - but that sucks
295 * performancewise on mass deletion/rename.
297 static inline void __d_clear_type_and_inode(struct dentry
*dentry
)
299 unsigned flags
= READ_ONCE(dentry
->d_flags
);
301 flags
&= ~(DCACHE_ENTRY_TYPE
| DCACHE_FALLTHRU
);
302 WRITE_ONCE(dentry
->d_flags
, flags
);
304 dentry
->d_inode
= NULL
;
307 static void dentry_free(struct dentry
*dentry
)
309 WARN_ON(!hlist_unhashed(&dentry
->d_u
.d_alias
));
310 if (unlikely(dname_external(dentry
))) {
311 struct external_name
*p
= external_name(dentry
);
312 if (likely(atomic_dec_and_test(&p
->u
.count
))) {
313 call_rcu(&dentry
->d_u
.d_rcu
, __d_free_external
);
317 /* if dentry was never visible to RCU, immediate free is OK */
318 if (!(dentry
->d_flags
& DCACHE_RCUACCESS
))
319 __d_free(&dentry
->d_u
.d_rcu
);
321 call_rcu(&dentry
->d_u
.d_rcu
, __d_free
);
325 * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups
326 * @dentry: the target dentry
327 * After this call, in-progress rcu-walk path lookup will fail. This
328 * should be called after unhashing, and after changing d_inode (if
329 * the dentry has not already been unhashed).
331 static inline void dentry_rcuwalk_invalidate(struct dentry
*dentry
)
333 lockdep_assert_held(&dentry
->d_lock
);
334 /* Go through am invalidation barrier */
335 write_seqcount_invalidate(&dentry
->d_seq
);
339 * Release the dentry's inode, using the filesystem
340 * d_iput() operation if defined. Dentry has no refcount
343 static void dentry_iput(struct dentry
* dentry
)
344 __releases(dentry
->d_lock
)
345 __releases(dentry
->d_inode
->i_lock
)
347 struct inode
*inode
= dentry
->d_inode
;
349 __d_clear_type_and_inode(dentry
);
350 hlist_del_init(&dentry
->d_u
.d_alias
);
351 spin_unlock(&dentry
->d_lock
);
352 spin_unlock(&inode
->i_lock
);
354 fsnotify_inoderemove(inode
);
355 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
356 dentry
->d_op
->d_iput(dentry
, inode
);
360 spin_unlock(&dentry
->d_lock
);
365 * Release the dentry's inode, using the filesystem
366 * d_iput() operation if defined. dentry remains in-use.
368 static void dentry_unlink_inode(struct dentry
* dentry
)
369 __releases(dentry
->d_lock
)
370 __releases(dentry
->d_inode
->i_lock
)
372 struct inode
*inode
= dentry
->d_inode
;
373 __d_clear_type_and_inode(dentry
);
374 hlist_del_init(&dentry
->d_u
.d_alias
);
375 dentry_rcuwalk_invalidate(dentry
);
376 spin_unlock(&dentry
->d_lock
);
377 spin_unlock(&inode
->i_lock
);
379 fsnotify_inoderemove(inode
);
380 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
381 dentry
->d_op
->d_iput(dentry
, inode
);
387 * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
388 * is in use - which includes both the "real" per-superblock
389 * LRU list _and_ the DCACHE_SHRINK_LIST use.
391 * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
392 * on the shrink list (ie not on the superblock LRU list).
394 * The per-cpu "nr_dentry_unused" counters are updated with
395 * the DCACHE_LRU_LIST bit.
397 * These helper functions make sure we always follow the
398 * rules. d_lock must be held by the caller.
400 #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
401 static void d_lru_add(struct dentry
*dentry
)
403 D_FLAG_VERIFY(dentry
, 0);
404 dentry
->d_flags
|= DCACHE_LRU_LIST
;
405 this_cpu_inc(nr_dentry_unused
);
406 WARN_ON_ONCE(!list_lru_add(&dentry
->d_sb
->s_dentry_lru
, &dentry
->d_lru
));
409 static void d_lru_del(struct dentry
*dentry
)
411 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
412 dentry
->d_flags
&= ~DCACHE_LRU_LIST
;
413 this_cpu_dec(nr_dentry_unused
);
414 WARN_ON_ONCE(!list_lru_del(&dentry
->d_sb
->s_dentry_lru
, &dentry
->d_lru
));
417 static void d_shrink_del(struct dentry
*dentry
)
419 D_FLAG_VERIFY(dentry
, DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
);
420 list_del_init(&dentry
->d_lru
);
421 dentry
->d_flags
&= ~(DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
);
422 this_cpu_dec(nr_dentry_unused
);
425 static void d_shrink_add(struct dentry
*dentry
, struct list_head
*list
)
427 D_FLAG_VERIFY(dentry
, 0);
428 list_add(&dentry
->d_lru
, list
);
429 dentry
->d_flags
|= DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
;
430 this_cpu_inc(nr_dentry_unused
);
434 * These can only be called under the global LRU lock, ie during the
435 * callback for freeing the LRU list. "isolate" removes it from the
436 * LRU lists entirely, while shrink_move moves it to the indicated
439 static void d_lru_isolate(struct list_lru_one
*lru
, struct dentry
*dentry
)
441 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
442 dentry
->d_flags
&= ~DCACHE_LRU_LIST
;
443 this_cpu_dec(nr_dentry_unused
);
444 list_lru_isolate(lru
, &dentry
->d_lru
);
447 static void d_lru_shrink_move(struct list_lru_one
*lru
, struct dentry
*dentry
,
448 struct list_head
*list
)
450 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
451 dentry
->d_flags
|= DCACHE_SHRINK_LIST
;
452 list_lru_isolate_move(lru
, &dentry
->d_lru
, list
);
456 * dentry_lru_(add|del)_list) must be called with d_lock held.
458 static void dentry_lru_add(struct dentry
*dentry
)
460 if (unlikely(!(dentry
->d_flags
& DCACHE_LRU_LIST
)))
465 * d_drop - drop a dentry
466 * @dentry: dentry to drop
468 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
469 * be found through a VFS lookup any more. Note that this is different from
470 * deleting the dentry - d_delete will try to mark the dentry negative if
471 * possible, giving a successful _negative_ lookup, while d_drop will
472 * just make the cache lookup fail.
474 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
475 * reason (NFS timeouts or autofs deletes).
477 * __d_drop requires dentry->d_lock.
479 void __d_drop(struct dentry
*dentry
)
481 if (!d_unhashed(dentry
)) {
482 struct hlist_bl_head
*b
;
484 * Hashed dentries are normally on the dentry hashtable,
485 * with the exception of those newly allocated by
486 * d_obtain_alias, which are always IS_ROOT:
488 if (unlikely(IS_ROOT(dentry
)))
489 b
= &dentry
->d_sb
->s_anon
;
491 b
= d_hash(dentry
->d_parent
, dentry
->d_name
.hash
);
494 __hlist_bl_del(&dentry
->d_hash
);
495 dentry
->d_hash
.pprev
= NULL
;
497 dentry_rcuwalk_invalidate(dentry
);
500 EXPORT_SYMBOL(__d_drop
);
502 void d_drop(struct dentry
*dentry
)
504 spin_lock(&dentry
->d_lock
);
506 spin_unlock(&dentry
->d_lock
);
508 EXPORT_SYMBOL(d_drop
);
510 static void __dentry_kill(struct dentry
*dentry
)
512 struct dentry
*parent
= NULL
;
513 bool can_free
= true;
514 if (!IS_ROOT(dentry
))
515 parent
= dentry
->d_parent
;
518 * The dentry is now unrecoverably dead to the world.
520 lockref_mark_dead(&dentry
->d_lockref
);
523 * inform the fs via d_prune that this dentry is about to be
524 * unhashed and destroyed.
526 if (dentry
->d_flags
& DCACHE_OP_PRUNE
)
527 dentry
->d_op
->d_prune(dentry
);
529 if (dentry
->d_flags
& DCACHE_LRU_LIST
) {
530 if (!(dentry
->d_flags
& DCACHE_SHRINK_LIST
))
533 /* if it was on the hash then remove it */
535 __list_del_entry(&dentry
->d_child
);
537 * Inform d_walk() that we are no longer attached to the
540 dentry
->d_flags
|= DCACHE_DENTRY_KILLED
;
542 spin_unlock(&parent
->d_lock
);
545 * dentry_iput drops the locks, at which point nobody (except
546 * transient RCU lookups) can reach this dentry.
548 BUG_ON(dentry
->d_lockref
.count
> 0);
549 this_cpu_dec(nr_dentry
);
550 if (dentry
->d_op
&& dentry
->d_op
->d_release
)
551 dentry
->d_op
->d_release(dentry
);
553 spin_lock(&dentry
->d_lock
);
554 if (dentry
->d_flags
& DCACHE_SHRINK_LIST
) {
555 dentry
->d_flags
|= DCACHE_MAY_FREE
;
558 spin_unlock(&dentry
->d_lock
);
559 if (likely(can_free
))
564 * Finish off a dentry we've decided to kill.
565 * dentry->d_lock must be held, returns with it unlocked.
566 * If ref is non-zero, then decrement the refcount too.
567 * Returns dentry requiring refcount drop, or NULL if we're done.
569 static struct dentry
*dentry_kill(struct dentry
*dentry
)
570 __releases(dentry
->d_lock
)
572 struct inode
*inode
= dentry
->d_inode
;
573 struct dentry
*parent
= NULL
;
575 if (inode
&& unlikely(!spin_trylock(&inode
->i_lock
)))
578 if (!IS_ROOT(dentry
)) {
579 parent
= dentry
->d_parent
;
580 if (unlikely(!spin_trylock(&parent
->d_lock
))) {
582 spin_unlock(&inode
->i_lock
);
587 __dentry_kill(dentry
);
591 spin_unlock(&dentry
->d_lock
);
593 return dentry
; /* try again with same dentry */
596 static inline struct dentry
*lock_parent(struct dentry
*dentry
)
598 struct dentry
*parent
= dentry
->d_parent
;
601 if (unlikely(dentry
->d_lockref
.count
< 0))
603 if (likely(spin_trylock(&parent
->d_lock
)))
606 spin_unlock(&dentry
->d_lock
);
608 parent
= ACCESS_ONCE(dentry
->d_parent
);
609 spin_lock(&parent
->d_lock
);
611 * We can't blindly lock dentry until we are sure
612 * that we won't violate the locking order.
613 * Any changes of dentry->d_parent must have
614 * been done with parent->d_lock held, so
615 * spin_lock() above is enough of a barrier
616 * for checking if it's still our child.
618 if (unlikely(parent
!= dentry
->d_parent
)) {
619 spin_unlock(&parent
->d_lock
);
623 if (parent
!= dentry
)
624 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
631 * Try to do a lockless dput(), and return whether that was successful.
633 * If unsuccessful, we return false, having already taken the dentry lock.
635 * The caller needs to hold the RCU read lock, so that the dentry is
636 * guaranteed to stay around even if the refcount goes down to zero!
638 static inline bool fast_dput(struct dentry
*dentry
)
641 unsigned int d_flags
;
644 * If we have a d_op->d_delete() operation, we sould not
645 * let the dentry count go to zero, so use "put_or_lock".
647 if (unlikely(dentry
->d_flags
& DCACHE_OP_DELETE
))
648 return lockref_put_or_lock(&dentry
->d_lockref
);
651 * .. otherwise, we can try to just decrement the
652 * lockref optimistically.
654 ret
= lockref_put_return(&dentry
->d_lockref
);
657 * If the lockref_put_return() failed due to the lock being held
658 * by somebody else, the fast path has failed. We will need to
659 * get the lock, and then check the count again.
661 if (unlikely(ret
< 0)) {
662 spin_lock(&dentry
->d_lock
);
663 if (dentry
->d_lockref
.count
> 1) {
664 dentry
->d_lockref
.count
--;
665 spin_unlock(&dentry
->d_lock
);
672 * If we weren't the last ref, we're done.
678 * Careful, careful. The reference count went down
679 * to zero, but we don't hold the dentry lock, so
680 * somebody else could get it again, and do another
681 * dput(), and we need to not race with that.
683 * However, there is a very special and common case
684 * where we don't care, because there is nothing to
685 * do: the dentry is still hashed, it does not have
686 * a 'delete' op, and it's referenced and already on
689 * NOTE! Since we aren't locked, these values are
690 * not "stable". However, it is sufficient that at
691 * some point after we dropped the reference the
692 * dentry was hashed and the flags had the proper
693 * value. Other dentry users may have re-gotten
694 * a reference to the dentry and change that, but
695 * our work is done - we can leave the dentry
696 * around with a zero refcount.
699 d_flags
= ACCESS_ONCE(dentry
->d_flags
);
700 d_flags
&= DCACHE_REFERENCED
| DCACHE_LRU_LIST
| DCACHE_DISCONNECTED
;
702 /* Nothing to do? Dropping the reference was all we needed? */
703 if (d_flags
== (DCACHE_REFERENCED
| DCACHE_LRU_LIST
) && !d_unhashed(dentry
))
707 * Not the fast normal case? Get the lock. We've already decremented
708 * the refcount, but we'll need to re-check the situation after
711 spin_lock(&dentry
->d_lock
);
714 * Did somebody else grab a reference to it in the meantime, and
715 * we're no longer the last user after all? Alternatively, somebody
716 * else could have killed it and marked it dead. Either way, we
717 * don't need to do anything else.
719 if (dentry
->d_lockref
.count
) {
720 spin_unlock(&dentry
->d_lock
);
725 * Re-get the reference we optimistically dropped. We hold the
726 * lock, and we just tested that it was zero, so we can just
729 dentry
->d_lockref
.count
= 1;
737 * This is complicated by the fact that we do not want to put
738 * dentries that are no longer on any hash chain on the unused
739 * list: we'd much rather just get rid of them immediately.
741 * However, that implies that we have to traverse the dentry
742 * tree upwards to the parents which might _also_ now be
743 * scheduled for deletion (it may have been only waiting for
744 * its last child to go away).
746 * This tail recursion is done by hand as we don't want to depend
747 * on the compiler to always get this right (gcc generally doesn't).
748 * Real recursion would eat up our stack space.
752 * dput - release a dentry
753 * @dentry: dentry to release
755 * Release a dentry. This will drop the usage count and if appropriate
756 * call the dentry unlink method as well as removing it from the queues and
757 * releasing its resources. If the parent dentries were scheduled for release
758 * they too may now get deleted.
760 void dput(struct dentry
*dentry
)
762 if (unlikely(!dentry
))
767 if (likely(fast_dput(dentry
))) {
772 /* Slow case: now with the dentry lock held */
775 /* Unreachable? Get rid of it */
776 if (unlikely(d_unhashed(dentry
)))
779 if (unlikely(dentry
->d_flags
& DCACHE_DISCONNECTED
))
782 if (unlikely(dentry
->d_flags
& DCACHE_OP_DELETE
)) {
783 if (dentry
->d_op
->d_delete(dentry
))
787 if (!(dentry
->d_flags
& DCACHE_REFERENCED
))
788 dentry
->d_flags
|= DCACHE_REFERENCED
;
789 dentry_lru_add(dentry
);
791 dentry
->d_lockref
.count
--;
792 spin_unlock(&dentry
->d_lock
);
796 dentry
= dentry_kill(dentry
);
803 /* This must be called with d_lock held */
804 static inline void __dget_dlock(struct dentry
*dentry
)
806 dentry
->d_lockref
.count
++;
809 static inline void __dget(struct dentry
*dentry
)
811 lockref_get(&dentry
->d_lockref
);
814 struct dentry
*dget_parent(struct dentry
*dentry
)
820 * Do optimistic parent lookup without any
824 ret
= ACCESS_ONCE(dentry
->d_parent
);
825 gotref
= lockref_get_not_zero(&ret
->d_lockref
);
827 if (likely(gotref
)) {
828 if (likely(ret
== ACCESS_ONCE(dentry
->d_parent
)))
835 * Don't need rcu_dereference because we re-check it was correct under
839 ret
= dentry
->d_parent
;
840 spin_lock(&ret
->d_lock
);
841 if (unlikely(ret
!= dentry
->d_parent
)) {
842 spin_unlock(&ret
->d_lock
);
847 BUG_ON(!ret
->d_lockref
.count
);
848 ret
->d_lockref
.count
++;
849 spin_unlock(&ret
->d_lock
);
852 EXPORT_SYMBOL(dget_parent
);
855 * d_find_alias - grab a hashed alias of inode
856 * @inode: inode in question
858 * If inode has a hashed alias, or is a directory and has any alias,
859 * acquire the reference to alias and return it. Otherwise return NULL.
860 * Notice that if inode is a directory there can be only one alias and
861 * it can be unhashed only if it has no children, or if it is the root
862 * of a filesystem, or if the directory was renamed and d_revalidate
863 * was the first vfs operation to notice.
865 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
866 * any other hashed alias over that one.
868 static struct dentry
*__d_find_alias(struct inode
*inode
)
870 struct dentry
*alias
, *discon_alias
;
874 hlist_for_each_entry(alias
, &inode
->i_dentry
, d_u
.d_alias
) {
875 spin_lock(&alias
->d_lock
);
876 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
877 if (IS_ROOT(alias
) &&
878 (alias
->d_flags
& DCACHE_DISCONNECTED
)) {
879 discon_alias
= alias
;
882 spin_unlock(&alias
->d_lock
);
886 spin_unlock(&alias
->d_lock
);
889 alias
= discon_alias
;
890 spin_lock(&alias
->d_lock
);
891 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
893 spin_unlock(&alias
->d_lock
);
896 spin_unlock(&alias
->d_lock
);
902 struct dentry
*d_find_alias(struct inode
*inode
)
904 struct dentry
*de
= NULL
;
906 if (!hlist_empty(&inode
->i_dentry
)) {
907 spin_lock(&inode
->i_lock
);
908 de
= __d_find_alias(inode
);
909 spin_unlock(&inode
->i_lock
);
913 EXPORT_SYMBOL(d_find_alias
);
916 * Try to kill dentries associated with this inode.
917 * WARNING: you must own a reference to inode.
919 void d_prune_aliases(struct inode
*inode
)
921 struct dentry
*dentry
;
923 spin_lock(&inode
->i_lock
);
924 hlist_for_each_entry(dentry
, &inode
->i_dentry
, d_u
.d_alias
) {
925 spin_lock(&dentry
->d_lock
);
926 if (!dentry
->d_lockref
.count
) {
927 struct dentry
*parent
= lock_parent(dentry
);
928 if (likely(!dentry
->d_lockref
.count
)) {
929 __dentry_kill(dentry
);
934 spin_unlock(&parent
->d_lock
);
936 spin_unlock(&dentry
->d_lock
);
938 spin_unlock(&inode
->i_lock
);
940 EXPORT_SYMBOL(d_prune_aliases
);
942 static void shrink_dentry_list(struct list_head
*list
)
944 struct dentry
*dentry
, *parent
;
946 while (!list_empty(list
)) {
948 dentry
= list_entry(list
->prev
, struct dentry
, d_lru
);
949 spin_lock(&dentry
->d_lock
);
950 parent
= lock_parent(dentry
);
953 * The dispose list is isolated and dentries are not accounted
954 * to the LRU here, so we can simply remove it from the list
955 * here regardless of whether it is referenced or not.
957 d_shrink_del(dentry
);
960 * We found an inuse dentry which was not removed from
961 * the LRU because of laziness during lookup. Do not free it.
963 if (dentry
->d_lockref
.count
> 0) {
964 spin_unlock(&dentry
->d_lock
);
966 spin_unlock(&parent
->d_lock
);
971 if (unlikely(dentry
->d_flags
& DCACHE_DENTRY_KILLED
)) {
972 bool can_free
= dentry
->d_flags
& DCACHE_MAY_FREE
;
973 spin_unlock(&dentry
->d_lock
);
975 spin_unlock(&parent
->d_lock
);
981 inode
= dentry
->d_inode
;
982 if (inode
&& unlikely(!spin_trylock(&inode
->i_lock
))) {
983 d_shrink_add(dentry
, list
);
984 spin_unlock(&dentry
->d_lock
);
986 spin_unlock(&parent
->d_lock
);
990 __dentry_kill(dentry
);
993 * We need to prune ancestors too. This is necessary to prevent
994 * quadratic behavior of shrink_dcache_parent(), but is also
995 * expected to be beneficial in reducing dentry cache
999 while (dentry
&& !lockref_put_or_lock(&dentry
->d_lockref
)) {
1000 parent
= lock_parent(dentry
);
1001 if (dentry
->d_lockref
.count
!= 1) {
1002 dentry
->d_lockref
.count
--;
1003 spin_unlock(&dentry
->d_lock
);
1005 spin_unlock(&parent
->d_lock
);
1008 inode
= dentry
->d_inode
; /* can't be NULL */
1009 if (unlikely(!spin_trylock(&inode
->i_lock
))) {
1010 spin_unlock(&dentry
->d_lock
);
1012 spin_unlock(&parent
->d_lock
);
1016 __dentry_kill(dentry
);
1022 static enum lru_status
dentry_lru_isolate(struct list_head
*item
,
1023 struct list_lru_one
*lru
, spinlock_t
*lru_lock
, void *arg
)
1025 struct list_head
*freeable
= arg
;
1026 struct dentry
*dentry
= container_of(item
, struct dentry
, d_lru
);
1030 * we are inverting the lru lock/dentry->d_lock here,
1031 * so use a trylock. If we fail to get the lock, just skip
1034 if (!spin_trylock(&dentry
->d_lock
))
1038 * Referenced dentries are still in use. If they have active
1039 * counts, just remove them from the LRU. Otherwise give them
1040 * another pass through the LRU.
1042 if (dentry
->d_lockref
.count
) {
1043 d_lru_isolate(lru
, dentry
);
1044 spin_unlock(&dentry
->d_lock
);
1048 if (dentry
->d_flags
& DCACHE_REFERENCED
) {
1049 dentry
->d_flags
&= ~DCACHE_REFERENCED
;
1050 spin_unlock(&dentry
->d_lock
);
1053 * The list move itself will be made by the common LRU code. At
1054 * this point, we've dropped the dentry->d_lock but keep the
1055 * lru lock. This is safe to do, since every list movement is
1056 * protected by the lru lock even if both locks are held.
1058 * This is guaranteed by the fact that all LRU management
1059 * functions are intermediated by the LRU API calls like
1060 * list_lru_add and list_lru_del. List movement in this file
1061 * only ever occur through this functions or through callbacks
1062 * like this one, that are called from the LRU API.
1064 * The only exceptions to this are functions like
1065 * shrink_dentry_list, and code that first checks for the
1066 * DCACHE_SHRINK_LIST flag. Those are guaranteed to be
1067 * operating only with stack provided lists after they are
1068 * properly isolated from the main list. It is thus, always a
1074 d_lru_shrink_move(lru
, dentry
, freeable
);
1075 spin_unlock(&dentry
->d_lock
);
1081 * prune_dcache_sb - shrink the dcache
1083 * @sc: shrink control, passed to list_lru_shrink_walk()
1085 * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This
1086 * is done when we need more memory and called from the superblock shrinker
1089 * This function may fail to free any resources if all the dentries are in
1092 long prune_dcache_sb(struct super_block
*sb
, struct shrink_control
*sc
)
1097 freed
= list_lru_shrink_walk(&sb
->s_dentry_lru
, sc
,
1098 dentry_lru_isolate
, &dispose
);
1099 shrink_dentry_list(&dispose
);
1103 static enum lru_status
dentry_lru_isolate_shrink(struct list_head
*item
,
1104 struct list_lru_one
*lru
, spinlock_t
*lru_lock
, void *arg
)
1106 struct list_head
*freeable
= arg
;
1107 struct dentry
*dentry
= container_of(item
, struct dentry
, d_lru
);
1110 * we are inverting the lru lock/dentry->d_lock here,
1111 * so use a trylock. If we fail to get the lock, just skip
1114 if (!spin_trylock(&dentry
->d_lock
))
1117 d_lru_shrink_move(lru
, dentry
, freeable
);
1118 spin_unlock(&dentry
->d_lock
);
1125 * shrink_dcache_sb - shrink dcache for a superblock
1128 * Shrink the dcache for the specified super block. This is used to free
1129 * the dcache before unmounting a file system.
1131 void shrink_dcache_sb(struct super_block
*sb
)
1138 freed
= list_lru_walk(&sb
->s_dentry_lru
,
1139 dentry_lru_isolate_shrink
, &dispose
, UINT_MAX
);
1141 this_cpu_sub(nr_dentry_unused
, freed
);
1142 shrink_dentry_list(&dispose
);
1143 } while (freed
> 0);
1145 EXPORT_SYMBOL(shrink_dcache_sb
);
1148 * enum d_walk_ret - action to talke during tree walk
1149 * @D_WALK_CONTINUE: contrinue walk
1150 * @D_WALK_QUIT: quit walk
1151 * @D_WALK_NORETRY: quit when retry is needed
1152 * @D_WALK_SKIP: skip this dentry and its children
1162 * d_walk - walk the dentry tree
1163 * @parent: start of walk
1164 * @data: data passed to @enter() and @finish()
1165 * @enter: callback when first entering the dentry
1166 * @finish: callback when successfully finished the walk
1168 * The @enter() and @finish() callbacks are called with d_lock held.
1170 static void d_walk(struct dentry
*parent
, void *data
,
1171 enum d_walk_ret (*enter
)(void *, struct dentry
*),
1172 void (*finish
)(void *))
1174 struct dentry
*this_parent
;
1175 struct list_head
*next
;
1177 enum d_walk_ret ret
;
1181 read_seqbegin_or_lock(&rename_lock
, &seq
);
1182 this_parent
= parent
;
1183 spin_lock(&this_parent
->d_lock
);
1185 ret
= enter(data
, this_parent
);
1187 case D_WALK_CONTINUE
:
1192 case D_WALK_NORETRY
:
1197 next
= this_parent
->d_subdirs
.next
;
1199 while (next
!= &this_parent
->d_subdirs
) {
1200 struct list_head
*tmp
= next
;
1201 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_child
);
1204 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
1206 ret
= enter(data
, dentry
);
1208 case D_WALK_CONTINUE
:
1211 spin_unlock(&dentry
->d_lock
);
1213 case D_WALK_NORETRY
:
1217 spin_unlock(&dentry
->d_lock
);
1221 if (!list_empty(&dentry
->d_subdirs
)) {
1222 spin_unlock(&this_parent
->d_lock
);
1223 spin_release(&dentry
->d_lock
.dep_map
, 1, _RET_IP_
);
1224 this_parent
= dentry
;
1225 spin_acquire(&this_parent
->d_lock
.dep_map
, 0, 1, _RET_IP_
);
1228 spin_unlock(&dentry
->d_lock
);
1231 * All done at this level ... ascend and resume the search.
1235 if (this_parent
!= parent
) {
1236 struct dentry
*child
= this_parent
;
1237 this_parent
= child
->d_parent
;
1239 spin_unlock(&child
->d_lock
);
1240 spin_lock(&this_parent
->d_lock
);
1242 /* might go back up the wrong parent if we have had a rename. */
1243 if (need_seqretry(&rename_lock
, seq
))
1245 /* go into the first sibling still alive */
1247 next
= child
->d_child
.next
;
1248 if (next
== &this_parent
->d_subdirs
)
1250 child
= list_entry(next
, struct dentry
, d_child
);
1251 } while (unlikely(child
->d_flags
& DCACHE_DENTRY_KILLED
));
1255 if (need_seqretry(&rename_lock
, seq
))
1262 spin_unlock(&this_parent
->d_lock
);
1263 done_seqretry(&rename_lock
, seq
);
1267 spin_unlock(&this_parent
->d_lock
);
1277 * Search for at least 1 mount point in the dentry's subdirs.
1278 * We descend to the next level whenever the d_subdirs
1279 * list is non-empty and continue searching.
1282 static enum d_walk_ret
check_mount(void *data
, struct dentry
*dentry
)
1285 if (d_mountpoint(dentry
)) {
1289 return D_WALK_CONTINUE
;
1293 * have_submounts - check for mounts over a dentry
1294 * @parent: dentry to check.
1296 * Return true if the parent or its subdirectories contain
1299 int have_submounts(struct dentry
*parent
)
1303 d_walk(parent
, &ret
, check_mount
, NULL
);
1307 EXPORT_SYMBOL(have_submounts
);
1310 * Called by mount code to set a mountpoint and check if the mountpoint is
1311 * reachable (e.g. NFS can unhash a directory dentry and then the complete
1312 * subtree can become unreachable).
1314 * Only one of d_invalidate() and d_set_mounted() must succeed. For
1315 * this reason take rename_lock and d_lock on dentry and ancestors.
1317 int d_set_mounted(struct dentry
*dentry
)
1321 write_seqlock(&rename_lock
);
1322 for (p
= dentry
->d_parent
; !IS_ROOT(p
); p
= p
->d_parent
) {
1323 /* Need exclusion wrt. d_invalidate() */
1324 spin_lock(&p
->d_lock
);
1325 if (unlikely(d_unhashed(p
))) {
1326 spin_unlock(&p
->d_lock
);
1329 spin_unlock(&p
->d_lock
);
1331 spin_lock(&dentry
->d_lock
);
1332 if (!d_unlinked(dentry
)) {
1333 dentry
->d_flags
|= DCACHE_MOUNTED
;
1336 spin_unlock(&dentry
->d_lock
);
1338 write_sequnlock(&rename_lock
);
1343 * Search the dentry child list of the specified parent,
1344 * and move any unused dentries to the end of the unused
1345 * list for prune_dcache(). We descend to the next level
1346 * whenever the d_subdirs list is non-empty and continue
1349 * It returns zero iff there are no unused children,
1350 * otherwise it returns the number of children moved to
1351 * the end of the unused list. This may not be the total
1352 * number of unused children, because select_parent can
1353 * drop the lock and return early due to latency
1357 struct select_data
{
1358 struct dentry
*start
;
1359 struct list_head dispose
;
1363 static enum d_walk_ret
select_collect(void *_data
, struct dentry
*dentry
)
1365 struct select_data
*data
= _data
;
1366 enum d_walk_ret ret
= D_WALK_CONTINUE
;
1368 if (data
->start
== dentry
)
1371 if (dentry
->d_flags
& DCACHE_SHRINK_LIST
) {
1374 if (dentry
->d_flags
& DCACHE_LRU_LIST
)
1376 if (!dentry
->d_lockref
.count
) {
1377 d_shrink_add(dentry
, &data
->dispose
);
1382 * We can return to the caller if we have found some (this
1383 * ensures forward progress). We'll be coming back to find
1386 if (!list_empty(&data
->dispose
))
1387 ret
= need_resched() ? D_WALK_QUIT
: D_WALK_NORETRY
;
1393 * shrink_dcache_parent - prune dcache
1394 * @parent: parent of entries to prune
1396 * Prune the dcache to remove unused children of the parent dentry.
1398 void shrink_dcache_parent(struct dentry
*parent
)
1401 struct select_data data
;
1403 INIT_LIST_HEAD(&data
.dispose
);
1404 data
.start
= parent
;
1407 d_walk(parent
, &data
, select_collect
, NULL
);
1411 shrink_dentry_list(&data
.dispose
);
1415 EXPORT_SYMBOL(shrink_dcache_parent
);
1417 static enum d_walk_ret
umount_check(void *_data
, struct dentry
*dentry
)
1419 /* it has busy descendents; complain about those instead */
1420 if (!list_empty(&dentry
->d_subdirs
))
1421 return D_WALK_CONTINUE
;
1423 /* root with refcount 1 is fine */
1424 if (dentry
== _data
&& dentry
->d_lockref
.count
== 1)
1425 return D_WALK_CONTINUE
;
1427 printk(KERN_ERR
"BUG: Dentry %p{i=%lx,n=%pd} "
1428 " still in use (%d) [unmount of %s %s]\n",
1431 dentry
->d_inode
->i_ino
: 0UL,
1433 dentry
->d_lockref
.count
,
1434 dentry
->d_sb
->s_type
->name
,
1435 dentry
->d_sb
->s_id
);
1437 return D_WALK_CONTINUE
;
1440 static void do_one_tree(struct dentry
*dentry
)
1442 shrink_dcache_parent(dentry
);
1443 d_walk(dentry
, dentry
, umount_check
, NULL
);
1449 * destroy the dentries attached to a superblock on unmounting
1451 void shrink_dcache_for_umount(struct super_block
*sb
)
1453 struct dentry
*dentry
;
1455 WARN(down_read_trylock(&sb
->s_umount
), "s_umount should've been locked");
1457 dentry
= sb
->s_root
;
1459 do_one_tree(dentry
);
1461 while (!hlist_bl_empty(&sb
->s_anon
)) {
1462 dentry
= dget(hlist_bl_entry(hlist_bl_first(&sb
->s_anon
), struct dentry
, d_hash
));
1463 do_one_tree(dentry
);
1467 struct detach_data
{
1468 struct select_data select
;
1469 struct dentry
*mountpoint
;
1471 static enum d_walk_ret
detach_and_collect(void *_data
, struct dentry
*dentry
)
1473 struct detach_data
*data
= _data
;
1475 if (d_mountpoint(dentry
)) {
1476 __dget_dlock(dentry
);
1477 data
->mountpoint
= dentry
;
1481 return select_collect(&data
->select
, dentry
);
1484 static void check_and_drop(void *_data
)
1486 struct detach_data
*data
= _data
;
1488 if (!data
->mountpoint
&& !data
->select
.found
)
1489 __d_drop(data
->select
.start
);
1493 * d_invalidate - detach submounts, prune dcache, and drop
1494 * @dentry: dentry to invalidate (aka detach, prune and drop)
1498 * The final d_drop is done as an atomic operation relative to
1499 * rename_lock ensuring there are no races with d_set_mounted. This
1500 * ensures there are no unhashed dentries on the path to a mountpoint.
1502 void d_invalidate(struct dentry
*dentry
)
1505 * If it's already been dropped, return OK.
1507 spin_lock(&dentry
->d_lock
);
1508 if (d_unhashed(dentry
)) {
1509 spin_unlock(&dentry
->d_lock
);
1512 spin_unlock(&dentry
->d_lock
);
1514 /* Negative dentries can be dropped without further checks */
1515 if (!dentry
->d_inode
) {
1521 struct detach_data data
;
1523 data
.mountpoint
= NULL
;
1524 INIT_LIST_HEAD(&data
.select
.dispose
);
1525 data
.select
.start
= dentry
;
1526 data
.select
.found
= 0;
1528 d_walk(dentry
, &data
, detach_and_collect
, check_and_drop
);
1530 if (data
.select
.found
)
1531 shrink_dentry_list(&data
.select
.dispose
);
1533 if (data
.mountpoint
) {
1534 detach_mounts(data
.mountpoint
);
1535 dput(data
.mountpoint
);
1538 if (!data
.mountpoint
&& !data
.select
.found
)
1544 EXPORT_SYMBOL(d_invalidate
);
1547 * __d_alloc - allocate a dcache entry
1548 * @sb: filesystem it will belong to
1549 * @name: qstr of the name
1551 * Allocates a dentry. It returns %NULL if there is insufficient memory
1552 * available. On a success the dentry is returned. The name passed in is
1553 * copied and the copy passed in may be reused after this call.
1556 struct dentry
*__d_alloc(struct super_block
*sb
, const struct qstr
*name
)
1558 struct dentry
*dentry
;
1561 dentry
= kmem_cache_alloc(dentry_cache
, GFP_KERNEL
);
1566 * We guarantee that the inline name is always NUL-terminated.
1567 * This way the memcpy() done by the name switching in rename
1568 * will still always have a NUL at the end, even if we might
1569 * be overwriting an internal NUL character
1571 dentry
->d_iname
[DNAME_INLINE_LEN
-1] = 0;
1572 if (name
->len
> DNAME_INLINE_LEN
-1) {
1573 size_t size
= offsetof(struct external_name
, name
[1]);
1574 struct external_name
*p
= kmalloc(size
+ name
->len
, GFP_KERNEL
);
1576 kmem_cache_free(dentry_cache
, dentry
);
1579 atomic_set(&p
->u
.count
, 1);
1581 if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS
))
1582 kasan_unpoison_shadow(dname
,
1583 round_up(name
->len
+ 1, sizeof(unsigned long)));
1585 dname
= dentry
->d_iname
;
1588 dentry
->d_name
.len
= name
->len
;
1589 dentry
->d_name
.hash
= name
->hash
;
1590 memcpy(dname
, name
->name
, name
->len
);
1591 dname
[name
->len
] = 0;
1593 /* Make sure we always see the terminating NUL character */
1595 dentry
->d_name
.name
= dname
;
1597 dentry
->d_lockref
.count
= 1;
1598 dentry
->d_flags
= 0;
1599 spin_lock_init(&dentry
->d_lock
);
1600 seqcount_init(&dentry
->d_seq
);
1601 dentry
->d_inode
= NULL
;
1602 dentry
->d_parent
= dentry
;
1604 dentry
->d_op
= NULL
;
1605 dentry
->d_fsdata
= NULL
;
1606 INIT_HLIST_BL_NODE(&dentry
->d_hash
);
1607 INIT_LIST_HEAD(&dentry
->d_lru
);
1608 INIT_LIST_HEAD(&dentry
->d_subdirs
);
1609 INIT_HLIST_NODE(&dentry
->d_u
.d_alias
);
1610 INIT_LIST_HEAD(&dentry
->d_child
);
1611 d_set_d_op(dentry
, dentry
->d_sb
->s_d_op
);
1613 this_cpu_inc(nr_dentry
);
1619 * d_alloc - allocate a dcache entry
1620 * @parent: parent of entry to allocate
1621 * @name: qstr of the name
1623 * Allocates a dentry. It returns %NULL if there is insufficient memory
1624 * available. On a success the dentry is returned. The name passed in is
1625 * copied and the copy passed in may be reused after this call.
1627 struct dentry
*d_alloc(struct dentry
* parent
, const struct qstr
*name
)
1629 struct dentry
*dentry
= __d_alloc(parent
->d_sb
, name
);
1633 spin_lock(&parent
->d_lock
);
1635 * don't need child lock because it is not subject
1636 * to concurrency here
1638 __dget_dlock(parent
);
1639 dentry
->d_parent
= parent
;
1640 list_add(&dentry
->d_child
, &parent
->d_subdirs
);
1641 spin_unlock(&parent
->d_lock
);
1645 EXPORT_SYMBOL(d_alloc
);
1648 * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
1649 * @sb: the superblock
1650 * @name: qstr of the name
1652 * For a filesystem that just pins its dentries in memory and never
1653 * performs lookups at all, return an unhashed IS_ROOT dentry.
1655 struct dentry
*d_alloc_pseudo(struct super_block
*sb
, const struct qstr
*name
)
1657 return __d_alloc(sb
, name
);
1659 EXPORT_SYMBOL(d_alloc_pseudo
);
1661 struct dentry
*d_alloc_name(struct dentry
*parent
, const char *name
)
1666 q
.len
= strlen(name
);
1667 q
.hash
= full_name_hash(q
.name
, q
.len
);
1668 return d_alloc(parent
, &q
);
1670 EXPORT_SYMBOL(d_alloc_name
);
1672 void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
)
1674 WARN_ON_ONCE(dentry
->d_op
);
1675 WARN_ON_ONCE(dentry
->d_flags
& (DCACHE_OP_HASH
|
1677 DCACHE_OP_REVALIDATE
|
1678 DCACHE_OP_WEAK_REVALIDATE
|
1680 DCACHE_OP_SELECT_INODE
));
1685 dentry
->d_flags
|= DCACHE_OP_HASH
;
1687 dentry
->d_flags
|= DCACHE_OP_COMPARE
;
1688 if (op
->d_revalidate
)
1689 dentry
->d_flags
|= DCACHE_OP_REVALIDATE
;
1690 if (op
->d_weak_revalidate
)
1691 dentry
->d_flags
|= DCACHE_OP_WEAK_REVALIDATE
;
1693 dentry
->d_flags
|= DCACHE_OP_DELETE
;
1695 dentry
->d_flags
|= DCACHE_OP_PRUNE
;
1696 if (op
->d_select_inode
)
1697 dentry
->d_flags
|= DCACHE_OP_SELECT_INODE
;
1700 EXPORT_SYMBOL(d_set_d_op
);
1704 * d_set_fallthru - Mark a dentry as falling through to a lower layer
1705 * @dentry - The dentry to mark
1707 * Mark a dentry as falling through to the lower layer (as set with
1708 * d_pin_lower()). This flag may be recorded on the medium.
1710 void d_set_fallthru(struct dentry
*dentry
)
1712 spin_lock(&dentry
->d_lock
);
1713 dentry
->d_flags
|= DCACHE_FALLTHRU
;
1714 spin_unlock(&dentry
->d_lock
);
1716 EXPORT_SYMBOL(d_set_fallthru
);
1718 static unsigned d_flags_for_inode(struct inode
*inode
)
1720 unsigned add_flags
= DCACHE_REGULAR_TYPE
;
1723 return DCACHE_MISS_TYPE
;
1725 if (S_ISDIR(inode
->i_mode
)) {
1726 add_flags
= DCACHE_DIRECTORY_TYPE
;
1727 if (unlikely(!(inode
->i_opflags
& IOP_LOOKUP
))) {
1728 if (unlikely(!inode
->i_op
->lookup
))
1729 add_flags
= DCACHE_AUTODIR_TYPE
;
1731 inode
->i_opflags
|= IOP_LOOKUP
;
1733 goto type_determined
;
1736 if (unlikely(!(inode
->i_opflags
& IOP_NOFOLLOW
))) {
1737 if (unlikely(inode
->i_op
->get_link
)) {
1738 add_flags
= DCACHE_SYMLINK_TYPE
;
1739 goto type_determined
;
1741 inode
->i_opflags
|= IOP_NOFOLLOW
;
1744 if (unlikely(!S_ISREG(inode
->i_mode
)))
1745 add_flags
= DCACHE_SPECIAL_TYPE
;
1748 if (unlikely(IS_AUTOMOUNT(inode
)))
1749 add_flags
|= DCACHE_NEED_AUTOMOUNT
;
1753 static void __d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
1755 unsigned add_flags
= d_flags_for_inode(inode
);
1757 spin_lock(&dentry
->d_lock
);
1759 hlist_add_head(&dentry
->d_u
.d_alias
, &inode
->i_dentry
);
1760 __d_set_inode_and_type(dentry
, inode
, add_flags
);
1761 dentry_rcuwalk_invalidate(dentry
);
1762 spin_unlock(&dentry
->d_lock
);
1763 fsnotify_d_instantiate(dentry
, inode
);
1767 * d_instantiate - fill in inode information for a dentry
1768 * @entry: dentry to complete
1769 * @inode: inode to attach to this dentry
1771 * Fill in inode information in the entry.
1773 * This turns negative dentries into productive full members
1776 * NOTE! This assumes that the inode count has been incremented
1777 * (or otherwise set) by the caller to indicate that it is now
1778 * in use by the dcache.
1781 void d_instantiate(struct dentry
*entry
, struct inode
* inode
)
1783 BUG_ON(!hlist_unhashed(&entry
->d_u
.d_alias
));
1785 spin_lock(&inode
->i_lock
);
1786 __d_instantiate(entry
, inode
);
1788 spin_unlock(&inode
->i_lock
);
1789 security_d_instantiate(entry
, inode
);
1791 EXPORT_SYMBOL(d_instantiate
);
1794 * d_instantiate_unique - instantiate a non-aliased dentry
1795 * @entry: dentry to instantiate
1796 * @inode: inode to attach to this dentry
1798 * Fill in inode information in the entry. On success, it returns NULL.
1799 * If an unhashed alias of "entry" already exists, then we return the
1800 * aliased dentry instead and drop one reference to inode.
1802 * Note that in order to avoid conflicts with rename() etc, the caller
1803 * had better be holding the parent directory semaphore.
1805 * This also assumes that the inode count has been incremented
1806 * (or otherwise set) by the caller to indicate that it is now
1807 * in use by the dcache.
1809 static struct dentry
*__d_instantiate_unique(struct dentry
*entry
,
1810 struct inode
*inode
)
1812 struct dentry
*alias
;
1813 int len
= entry
->d_name
.len
;
1814 const char *name
= entry
->d_name
.name
;
1815 unsigned int hash
= entry
->d_name
.hash
;
1818 __d_instantiate(entry
, NULL
);
1822 hlist_for_each_entry(alias
, &inode
->i_dentry
, d_u
.d_alias
) {
1824 * Don't need alias->d_lock here, because aliases with
1825 * d_parent == entry->d_parent are not subject to name or
1826 * parent changes, because the parent inode i_mutex is held.
1828 if (alias
->d_name
.hash
!= hash
)
1830 if (alias
->d_parent
!= entry
->d_parent
)
1832 if (alias
->d_name
.len
!= len
)
1834 if (dentry_cmp(alias
, name
, len
))
1840 __d_instantiate(entry
, inode
);
1844 struct dentry
*d_instantiate_unique(struct dentry
*entry
, struct inode
*inode
)
1846 struct dentry
*result
;
1848 BUG_ON(!hlist_unhashed(&entry
->d_u
.d_alias
));
1851 spin_lock(&inode
->i_lock
);
1852 result
= __d_instantiate_unique(entry
, inode
);
1854 spin_unlock(&inode
->i_lock
);
1857 security_d_instantiate(entry
, inode
);
1861 BUG_ON(!d_unhashed(result
));
1866 EXPORT_SYMBOL(d_instantiate_unique
);
1869 * d_instantiate_no_diralias - instantiate a non-aliased dentry
1870 * @entry: dentry to complete
1871 * @inode: inode to attach to this dentry
1873 * Fill in inode information in the entry. If a directory alias is found, then
1874 * return an error (and drop inode). Together with d_materialise_unique() this
1875 * guarantees that a directory inode may never have more than one alias.
1877 int d_instantiate_no_diralias(struct dentry
*entry
, struct inode
*inode
)
1879 BUG_ON(!hlist_unhashed(&entry
->d_u
.d_alias
));
1881 spin_lock(&inode
->i_lock
);
1882 if (S_ISDIR(inode
->i_mode
) && !hlist_empty(&inode
->i_dentry
)) {
1883 spin_unlock(&inode
->i_lock
);
1887 __d_instantiate(entry
, inode
);
1888 spin_unlock(&inode
->i_lock
);
1889 security_d_instantiate(entry
, inode
);
1893 EXPORT_SYMBOL(d_instantiate_no_diralias
);
1895 struct dentry
*d_make_root(struct inode
*root_inode
)
1897 struct dentry
*res
= NULL
;
1900 static const struct qstr name
= QSTR_INIT("/", 1);
1902 res
= __d_alloc(root_inode
->i_sb
, &name
);
1904 d_instantiate(res
, root_inode
);
1910 EXPORT_SYMBOL(d_make_root
);
1912 static struct dentry
* __d_find_any_alias(struct inode
*inode
)
1914 struct dentry
*alias
;
1916 if (hlist_empty(&inode
->i_dentry
))
1918 alias
= hlist_entry(inode
->i_dentry
.first
, struct dentry
, d_u
.d_alias
);
1924 * d_find_any_alias - find any alias for a given inode
1925 * @inode: inode to find an alias for
1927 * If any aliases exist for the given inode, take and return a
1928 * reference for one of them. If no aliases exist, return %NULL.
1930 struct dentry
*d_find_any_alias(struct inode
*inode
)
1934 spin_lock(&inode
->i_lock
);
1935 de
= __d_find_any_alias(inode
);
1936 spin_unlock(&inode
->i_lock
);
1939 EXPORT_SYMBOL(d_find_any_alias
);
1941 static struct dentry
*__d_obtain_alias(struct inode
*inode
, int disconnected
)
1943 static const struct qstr anonstring
= QSTR_INIT("/", 1);
1949 return ERR_PTR(-ESTALE
);
1951 return ERR_CAST(inode
);
1953 res
= d_find_any_alias(inode
);
1957 tmp
= __d_alloc(inode
->i_sb
, &anonstring
);
1959 res
= ERR_PTR(-ENOMEM
);
1963 spin_lock(&inode
->i_lock
);
1964 res
= __d_find_any_alias(inode
);
1966 spin_unlock(&inode
->i_lock
);
1971 /* attach a disconnected dentry */
1972 add_flags
= d_flags_for_inode(inode
);
1975 add_flags
|= DCACHE_DISCONNECTED
;
1977 spin_lock(&tmp
->d_lock
);
1978 __d_set_inode_and_type(tmp
, inode
, add_flags
);
1979 hlist_add_head(&tmp
->d_u
.d_alias
, &inode
->i_dentry
);
1980 hlist_bl_lock(&tmp
->d_sb
->s_anon
);
1981 hlist_bl_add_head(&tmp
->d_hash
, &tmp
->d_sb
->s_anon
);
1982 hlist_bl_unlock(&tmp
->d_sb
->s_anon
);
1983 spin_unlock(&tmp
->d_lock
);
1984 spin_unlock(&inode
->i_lock
);
1985 security_d_instantiate(tmp
, inode
);
1990 if (res
&& !IS_ERR(res
))
1991 security_d_instantiate(res
, inode
);
1997 * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
1998 * @inode: inode to allocate the dentry for
2000 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
2001 * similar open by handle operations. The returned dentry may be anonymous,
2002 * or may have a full name (if the inode was already in the cache).
2004 * When called on a directory inode, we must ensure that the inode only ever
2005 * has one dentry. If a dentry is found, that is returned instead of
2006 * allocating a new one.
2008 * On successful return, the reference to the inode has been transferred
2009 * to the dentry. In case of an error the reference on the inode is released.
2010 * To make it easier to use in export operations a %NULL or IS_ERR inode may
2011 * be passed in and the error will be propagated to the return value,
2012 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
2014 struct dentry
*d_obtain_alias(struct inode
*inode
)
2016 return __d_obtain_alias(inode
, 1);
2018 EXPORT_SYMBOL(d_obtain_alias
);
2021 * d_obtain_root - find or allocate a dentry for a given inode
2022 * @inode: inode to allocate the dentry for
2024 * Obtain an IS_ROOT dentry for the root of a filesystem.
2026 * We must ensure that directory inodes only ever have one dentry. If a
2027 * dentry is found, that is returned instead of allocating a new one.
2029 * On successful return, the reference to the inode has been transferred
2030 * to the dentry. In case of an error the reference on the inode is
2031 * released. A %NULL or IS_ERR inode may be passed in and will be the
2032 * error will be propagate to the return value, with a %NULL @inode
2033 * replaced by ERR_PTR(-ESTALE).
2035 struct dentry
*d_obtain_root(struct inode
*inode
)
2037 return __d_obtain_alias(inode
, 0);
2039 EXPORT_SYMBOL(d_obtain_root
);
2042 * d_add_ci - lookup or allocate new dentry with case-exact name
2043 * @inode: the inode case-insensitive lookup has found
2044 * @dentry: the negative dentry that was passed to the parent's lookup func
2045 * @name: the case-exact name to be associated with the returned dentry
2047 * This is to avoid filling the dcache with case-insensitive names to the
2048 * same inode, only the actual correct case is stored in the dcache for
2049 * case-insensitive filesystems.
2051 * For a case-insensitive lookup match and if the the case-exact dentry
2052 * already exists in in the dcache, use it and return it.
2054 * If no entry exists with the exact case name, allocate new dentry with
2055 * the exact case, and return the spliced entry.
2057 struct dentry
*d_add_ci(struct dentry
*dentry
, struct inode
*inode
,
2060 struct dentry
*found
;
2064 * First check if a dentry matching the name already exists,
2065 * if not go ahead and create it now.
2067 found
= d_hash_and_lookup(dentry
->d_parent
, name
);
2069 new = d_alloc(dentry
->d_parent
, name
);
2071 found
= ERR_PTR(-ENOMEM
);
2073 found
= d_splice_alias(inode
, new);
2084 EXPORT_SYMBOL(d_add_ci
);
2087 * Do the slow-case of the dentry name compare.
2089 * Unlike the dentry_cmp() function, we need to atomically
2090 * load the name and length information, so that the
2091 * filesystem can rely on them, and can use the 'name' and
2092 * 'len' information without worrying about walking off the
2093 * end of memory etc.
2095 * Thus the read_seqcount_retry() and the "duplicate" info
2096 * in arguments (the low-level filesystem should not look
2097 * at the dentry inode or name contents directly, since
2098 * rename can change them while we're in RCU mode).
2100 enum slow_d_compare
{
2106 static noinline
enum slow_d_compare
slow_dentry_cmp(
2107 const struct dentry
*parent
,
2108 struct dentry
*dentry
,
2110 const struct qstr
*name
)
2112 int tlen
= dentry
->d_name
.len
;
2113 const char *tname
= dentry
->d_name
.name
;
2115 if (read_seqcount_retry(&dentry
->d_seq
, seq
)) {
2117 return D_COMP_SEQRETRY
;
2119 if (parent
->d_op
->d_compare(parent
, dentry
, tlen
, tname
, name
))
2120 return D_COMP_NOMATCH
;
2125 * __d_lookup_rcu - search for a dentry (racy, store-free)
2126 * @parent: parent dentry
2127 * @name: qstr of name we wish to find
2128 * @seqp: returns d_seq value at the point where the dentry was found
2129 * Returns: dentry, or NULL
2131 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
2132 * resolution (store-free path walking) design described in
2133 * Documentation/filesystems/path-lookup.txt.
2135 * This is not to be used outside core vfs.
2137 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
2138 * held, and rcu_read_lock held. The returned dentry must not be stored into
2139 * without taking d_lock and checking d_seq sequence count against @seq
2142 * A refcount may be taken on the found dentry with the d_rcu_to_refcount
2145 * Alternatively, __d_lookup_rcu may be called again to look up the child of
2146 * the returned dentry, so long as its parent's seqlock is checked after the
2147 * child is looked up. Thus, an interlocking stepping of sequence lock checks
2148 * is formed, giving integrity down the path walk.
2150 * NOTE! The caller *has* to check the resulting dentry against the sequence
2151 * number we've returned before using any of the resulting dentry state!
2153 struct dentry
*__d_lookup_rcu(const struct dentry
*parent
,
2154 const struct qstr
*name
,
2157 u64 hashlen
= name
->hash_len
;
2158 const unsigned char *str
= name
->name
;
2159 struct hlist_bl_head
*b
= d_hash(parent
, hashlen_hash(hashlen
));
2160 struct hlist_bl_node
*node
;
2161 struct dentry
*dentry
;
2164 * Note: There is significant duplication with __d_lookup_rcu which is
2165 * required to prevent single threaded performance regressions
2166 * especially on architectures where smp_rmb (in seqcounts) are costly.
2167 * Keep the two functions in sync.
2171 * The hash list is protected using RCU.
2173 * Carefully use d_seq when comparing a candidate dentry, to avoid
2174 * races with d_move().
2176 * It is possible that concurrent renames can mess up our list
2177 * walk here and result in missing our dentry, resulting in the
2178 * false-negative result. d_lookup() protects against concurrent
2179 * renames using rename_lock seqlock.
2181 * See Documentation/filesystems/path-lookup.txt for more details.
2183 hlist_bl_for_each_entry_rcu(dentry
, node
, b
, d_hash
) {
2188 * The dentry sequence count protects us from concurrent
2189 * renames, and thus protects parent and name fields.
2191 * The caller must perform a seqcount check in order
2192 * to do anything useful with the returned dentry.
2194 * NOTE! We do a "raw" seqcount_begin here. That means that
2195 * we don't wait for the sequence count to stabilize if it
2196 * is in the middle of a sequence change. If we do the slow
2197 * dentry compare, we will do seqretries until it is stable,
2198 * and if we end up with a successful lookup, we actually
2199 * want to exit RCU lookup anyway.
2201 seq
= raw_seqcount_begin(&dentry
->d_seq
);
2202 if (dentry
->d_parent
!= parent
)
2204 if (d_unhashed(dentry
))
2207 if (unlikely(parent
->d_flags
& DCACHE_OP_COMPARE
)) {
2208 if (dentry
->d_name
.hash
!= hashlen_hash(hashlen
))
2211 switch (slow_dentry_cmp(parent
, dentry
, seq
, name
)) {
2214 case D_COMP_NOMATCH
:
2221 if (dentry
->d_name
.hash_len
!= hashlen
)
2224 if (!dentry_cmp(dentry
, str
, hashlen_len(hashlen
)))
2231 * d_lookup - search for a dentry
2232 * @parent: parent dentry
2233 * @name: qstr of name we wish to find
2234 * Returns: dentry, or NULL
2236 * d_lookup searches the children of the parent dentry for the name in
2237 * question. If the dentry is found its reference count is incremented and the
2238 * dentry is returned. The caller must use dput to free the entry when it has
2239 * finished using it. %NULL is returned if the dentry does not exist.
2241 struct dentry
*d_lookup(const struct dentry
*parent
, const struct qstr
*name
)
2243 struct dentry
*dentry
;
2247 seq
= read_seqbegin(&rename_lock
);
2248 dentry
= __d_lookup(parent
, name
);
2251 } while (read_seqretry(&rename_lock
, seq
));
2254 EXPORT_SYMBOL(d_lookup
);
2257 * __d_lookup - search for a dentry (racy)
2258 * @parent: parent dentry
2259 * @name: qstr of name we wish to find
2260 * Returns: dentry, or NULL
2262 * __d_lookup is like d_lookup, however it may (rarely) return a
2263 * false-negative result due to unrelated rename activity.
2265 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
2266 * however it must be used carefully, eg. with a following d_lookup in
2267 * the case of failure.
2269 * __d_lookup callers must be commented.
2271 struct dentry
*__d_lookup(const struct dentry
*parent
, const struct qstr
*name
)
2273 unsigned int len
= name
->len
;
2274 unsigned int hash
= name
->hash
;
2275 const unsigned char *str
= name
->name
;
2276 struct hlist_bl_head
*b
= d_hash(parent
, hash
);
2277 struct hlist_bl_node
*node
;
2278 struct dentry
*found
= NULL
;
2279 struct dentry
*dentry
;
2282 * Note: There is significant duplication with __d_lookup_rcu which is
2283 * required to prevent single threaded performance regressions
2284 * especially on architectures where smp_rmb (in seqcounts) are costly.
2285 * Keep the two functions in sync.
2289 * The hash list is protected using RCU.
2291 * Take d_lock when comparing a candidate dentry, to avoid races
2294 * It is possible that concurrent renames can mess up our list
2295 * walk here and result in missing our dentry, resulting in the
2296 * false-negative result. d_lookup() protects against concurrent
2297 * renames using rename_lock seqlock.
2299 * See Documentation/filesystems/path-lookup.txt for more details.
2303 hlist_bl_for_each_entry_rcu(dentry
, node
, b
, d_hash
) {
2305 if (dentry
->d_name
.hash
!= hash
)
2308 spin_lock(&dentry
->d_lock
);
2309 if (dentry
->d_parent
!= parent
)
2311 if (d_unhashed(dentry
))
2315 * It is safe to compare names since d_move() cannot
2316 * change the qstr (protected by d_lock).
2318 if (parent
->d_flags
& DCACHE_OP_COMPARE
) {
2319 int tlen
= dentry
->d_name
.len
;
2320 const char *tname
= dentry
->d_name
.name
;
2321 if (parent
->d_op
->d_compare(parent
, dentry
, tlen
, tname
, name
))
2324 if (dentry
->d_name
.len
!= len
)
2326 if (dentry_cmp(dentry
, str
, len
))
2330 dentry
->d_lockref
.count
++;
2332 spin_unlock(&dentry
->d_lock
);
2335 spin_unlock(&dentry
->d_lock
);
2343 * d_hash_and_lookup - hash the qstr then search for a dentry
2344 * @dir: Directory to search in
2345 * @name: qstr of name we wish to find
2347 * On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
2349 struct dentry
*d_hash_and_lookup(struct dentry
*dir
, struct qstr
*name
)
2352 * Check for a fs-specific hash function. Note that we must
2353 * calculate the standard hash first, as the d_op->d_hash()
2354 * routine may choose to leave the hash value unchanged.
2356 name
->hash
= full_name_hash(name
->name
, name
->len
);
2357 if (dir
->d_flags
& DCACHE_OP_HASH
) {
2358 int err
= dir
->d_op
->d_hash(dir
, name
);
2359 if (unlikely(err
< 0))
2360 return ERR_PTR(err
);
2362 return d_lookup(dir
, name
);
2364 EXPORT_SYMBOL(d_hash_and_lookup
);
2367 * When a file is deleted, we have two options:
2368 * - turn this dentry into a negative dentry
2369 * - unhash this dentry and free it.
2371 * Usually, we want to just turn this into
2372 * a negative dentry, but if anybody else is
2373 * currently using the dentry or the inode
2374 * we can't do that and we fall back on removing
2375 * it from the hash queues and waiting for
2376 * it to be deleted later when it has no users
2380 * d_delete - delete a dentry
2381 * @dentry: The dentry to delete
2383 * Turn the dentry into a negative dentry if possible, otherwise
2384 * remove it from the hash queues so it can be deleted later
2387 void d_delete(struct dentry
* dentry
)
2389 struct inode
*inode
;
2392 * Are we the only user?
2395 spin_lock(&dentry
->d_lock
);
2396 inode
= dentry
->d_inode
;
2397 isdir
= S_ISDIR(inode
->i_mode
);
2398 if (dentry
->d_lockref
.count
== 1) {
2399 if (!spin_trylock(&inode
->i_lock
)) {
2400 spin_unlock(&dentry
->d_lock
);
2404 dentry
->d_flags
&= ~DCACHE_CANT_MOUNT
;
2405 dentry_unlink_inode(dentry
);
2406 fsnotify_nameremove(dentry
, isdir
);
2410 if (!d_unhashed(dentry
))
2413 spin_unlock(&dentry
->d_lock
);
2415 fsnotify_nameremove(dentry
, isdir
);
2417 EXPORT_SYMBOL(d_delete
);
2419 static void __d_rehash(struct dentry
* entry
, struct hlist_bl_head
*b
)
2421 BUG_ON(!d_unhashed(entry
));
2423 entry
->d_flags
|= DCACHE_RCUACCESS
;
2424 hlist_bl_add_head_rcu(&entry
->d_hash
, b
);
2428 static void _d_rehash(struct dentry
* entry
)
2430 __d_rehash(entry
, d_hash(entry
->d_parent
, entry
->d_name
.hash
));
2434 * d_rehash - add an entry back to the hash
2435 * @entry: dentry to add to the hash
2437 * Adds a dentry to the hash according to its name.
2440 void d_rehash(struct dentry
* entry
)
2442 spin_lock(&entry
->d_lock
);
2444 spin_unlock(&entry
->d_lock
);
2446 EXPORT_SYMBOL(d_rehash
);
2449 * dentry_update_name_case - update case insensitive dentry with a new name
2450 * @dentry: dentry to be updated
2453 * Update a case insensitive dentry with new case of name.
2455 * dentry must have been returned by d_lookup with name @name. Old and new
2456 * name lengths must match (ie. no d_compare which allows mismatched name
2459 * Parent inode i_mutex must be held over d_lookup and into this call (to
2460 * keep renames and concurrent inserts, and readdir(2) away).
2462 void dentry_update_name_case(struct dentry
*dentry
, struct qstr
*name
)
2464 BUG_ON(!mutex_is_locked(&dentry
->d_parent
->d_inode
->i_mutex
));
2465 BUG_ON(dentry
->d_name
.len
!= name
->len
); /* d_lookup gives this */
2467 spin_lock(&dentry
->d_lock
);
2468 write_seqcount_begin(&dentry
->d_seq
);
2469 memcpy((unsigned char *)dentry
->d_name
.name
, name
->name
, name
->len
);
2470 write_seqcount_end(&dentry
->d_seq
);
2471 spin_unlock(&dentry
->d_lock
);
2473 EXPORT_SYMBOL(dentry_update_name_case
);
2475 static void swap_names(struct dentry
*dentry
, struct dentry
*target
)
2477 if (unlikely(dname_external(target
))) {
2478 if (unlikely(dname_external(dentry
))) {
2480 * Both external: swap the pointers
2482 swap(target
->d_name
.name
, dentry
->d_name
.name
);
2485 * dentry:internal, target:external. Steal target's
2486 * storage and make target internal.
2488 memcpy(target
->d_iname
, dentry
->d_name
.name
,
2489 dentry
->d_name
.len
+ 1);
2490 dentry
->d_name
.name
= target
->d_name
.name
;
2491 target
->d_name
.name
= target
->d_iname
;
2494 if (unlikely(dname_external(dentry
))) {
2496 * dentry:external, target:internal. Give dentry's
2497 * storage to target and make dentry internal
2499 memcpy(dentry
->d_iname
, target
->d_name
.name
,
2500 target
->d_name
.len
+ 1);
2501 target
->d_name
.name
= dentry
->d_name
.name
;
2502 dentry
->d_name
.name
= dentry
->d_iname
;
2505 * Both are internal.
2508 BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN
, sizeof(long)));
2509 kmemcheck_mark_initialized(dentry
->d_iname
, DNAME_INLINE_LEN
);
2510 kmemcheck_mark_initialized(target
->d_iname
, DNAME_INLINE_LEN
);
2511 for (i
= 0; i
< DNAME_INLINE_LEN
/ sizeof(long); i
++) {
2512 swap(((long *) &dentry
->d_iname
)[i
],
2513 ((long *) &target
->d_iname
)[i
]);
2517 swap(dentry
->d_name
.hash_len
, target
->d_name
.hash_len
);
2520 static void copy_name(struct dentry
*dentry
, struct dentry
*target
)
2522 struct external_name
*old_name
= NULL
;
2523 if (unlikely(dname_external(dentry
)))
2524 old_name
= external_name(dentry
);
2525 if (unlikely(dname_external(target
))) {
2526 atomic_inc(&external_name(target
)->u
.count
);
2527 dentry
->d_name
= target
->d_name
;
2529 memcpy(dentry
->d_iname
, target
->d_name
.name
,
2530 target
->d_name
.len
+ 1);
2531 dentry
->d_name
.name
= dentry
->d_iname
;
2532 dentry
->d_name
.hash_len
= target
->d_name
.hash_len
;
2534 if (old_name
&& likely(atomic_dec_and_test(&old_name
->u
.count
)))
2535 kfree_rcu(old_name
, u
.head
);
2538 static void dentry_lock_for_move(struct dentry
*dentry
, struct dentry
*target
)
2541 * XXXX: do we really need to take target->d_lock?
2543 if (IS_ROOT(dentry
) || dentry
->d_parent
== target
->d_parent
)
2544 spin_lock(&target
->d_parent
->d_lock
);
2546 if (d_ancestor(dentry
->d_parent
, target
->d_parent
)) {
2547 spin_lock(&dentry
->d_parent
->d_lock
);
2548 spin_lock_nested(&target
->d_parent
->d_lock
,
2549 DENTRY_D_LOCK_NESTED
);
2551 spin_lock(&target
->d_parent
->d_lock
);
2552 spin_lock_nested(&dentry
->d_parent
->d_lock
,
2553 DENTRY_D_LOCK_NESTED
);
2556 if (target
< dentry
) {
2557 spin_lock_nested(&target
->d_lock
, 2);
2558 spin_lock_nested(&dentry
->d_lock
, 3);
2560 spin_lock_nested(&dentry
->d_lock
, 2);
2561 spin_lock_nested(&target
->d_lock
, 3);
2565 static void dentry_unlock_for_move(struct dentry
*dentry
, struct dentry
*target
)
2567 if (target
->d_parent
!= dentry
->d_parent
)
2568 spin_unlock(&dentry
->d_parent
->d_lock
);
2569 if (target
->d_parent
!= target
)
2570 spin_unlock(&target
->d_parent
->d_lock
);
2571 spin_unlock(&target
->d_lock
);
2572 spin_unlock(&dentry
->d_lock
);
2576 * When switching names, the actual string doesn't strictly have to
2577 * be preserved in the target - because we're dropping the target
2578 * anyway. As such, we can just do a simple memcpy() to copy over
2579 * the new name before we switch, unless we are going to rehash
2580 * it. Note that if we *do* unhash the target, we are not allowed
2581 * to rehash it without giving it a new name/hash key - whether
2582 * we swap or overwrite the names here, resulting name won't match
2583 * the reality in filesystem; it's only there for d_path() purposes.
2584 * Note that all of this is happening under rename_lock, so the
2585 * any hash lookup seeing it in the middle of manipulations will
2586 * be discarded anyway. So we do not care what happens to the hash
2590 * __d_move - move a dentry
2591 * @dentry: entry to move
2592 * @target: new dentry
2593 * @exchange: exchange the two dentries
2595 * Update the dcache to reflect the move of a file name. Negative
2596 * dcache entries should not be moved in this way. Caller must hold
2597 * rename_lock, the i_mutex of the source and target directories,
2598 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
2600 static void __d_move(struct dentry
*dentry
, struct dentry
*target
,
2603 if (!dentry
->d_inode
)
2604 printk(KERN_WARNING
"VFS: moving negative dcache entry\n");
2606 BUG_ON(d_ancestor(dentry
, target
));
2607 BUG_ON(d_ancestor(target
, dentry
));
2609 dentry_lock_for_move(dentry
, target
);
2611 write_seqcount_begin(&dentry
->d_seq
);
2612 write_seqcount_begin_nested(&target
->d_seq
, DENTRY_D_LOCK_NESTED
);
2614 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2617 * Move the dentry to the target hash queue. Don't bother checking
2618 * for the same hash queue because of how unlikely it is.
2621 __d_rehash(dentry
, d_hash(target
->d_parent
, target
->d_name
.hash
));
2624 * Unhash the target (d_delete() is not usable here). If exchanging
2625 * the two dentries, then rehash onto the other's hash queue.
2630 d_hash(dentry
->d_parent
, dentry
->d_name
.hash
));
2633 /* Switch the names.. */
2635 swap_names(dentry
, target
);
2637 copy_name(dentry
, target
);
2639 /* ... and switch them in the tree */
2640 if (IS_ROOT(dentry
)) {
2641 /* splicing a tree */
2642 dentry
->d_parent
= target
->d_parent
;
2643 target
->d_parent
= target
;
2644 list_del_init(&target
->d_child
);
2645 list_move(&dentry
->d_child
, &dentry
->d_parent
->d_subdirs
);
2647 /* swapping two dentries */
2648 swap(dentry
->d_parent
, target
->d_parent
);
2649 list_move(&target
->d_child
, &target
->d_parent
->d_subdirs
);
2650 list_move(&dentry
->d_child
, &dentry
->d_parent
->d_subdirs
);
2652 fsnotify_d_move(target
);
2653 fsnotify_d_move(dentry
);
2656 write_seqcount_end(&target
->d_seq
);
2657 write_seqcount_end(&dentry
->d_seq
);
2659 dentry_unlock_for_move(dentry
, target
);
2663 * d_move - move a dentry
2664 * @dentry: entry to move
2665 * @target: new dentry
2667 * Update the dcache to reflect the move of a file name. Negative
2668 * dcache entries should not be moved in this way. See the locking
2669 * requirements for __d_move.
2671 void d_move(struct dentry
*dentry
, struct dentry
*target
)
2673 write_seqlock(&rename_lock
);
2674 __d_move(dentry
, target
, false);
2675 write_sequnlock(&rename_lock
);
2677 EXPORT_SYMBOL(d_move
);
2680 * d_exchange - exchange two dentries
2681 * @dentry1: first dentry
2682 * @dentry2: second dentry
2684 void d_exchange(struct dentry
*dentry1
, struct dentry
*dentry2
)
2686 write_seqlock(&rename_lock
);
2688 WARN_ON(!dentry1
->d_inode
);
2689 WARN_ON(!dentry2
->d_inode
);
2690 WARN_ON(IS_ROOT(dentry1
));
2691 WARN_ON(IS_ROOT(dentry2
));
2693 __d_move(dentry1
, dentry2
, true);
2695 write_sequnlock(&rename_lock
);
2699 * d_ancestor - search for an ancestor
2700 * @p1: ancestor dentry
2703 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2704 * an ancestor of p2, else NULL.
2706 struct dentry
*d_ancestor(struct dentry
*p1
, struct dentry
*p2
)
2710 for (p
= p2
; !IS_ROOT(p
); p
= p
->d_parent
) {
2711 if (p
->d_parent
== p1
)
2718 * This helper attempts to cope with remotely renamed directories
2720 * It assumes that the caller is already holding
2721 * dentry->d_parent->d_inode->i_mutex, and rename_lock
2723 * Note: If ever the locking in lock_rename() changes, then please
2724 * remember to update this too...
2726 static int __d_unalias(struct inode
*inode
,
2727 struct dentry
*dentry
, struct dentry
*alias
)
2729 struct mutex
*m1
= NULL
, *m2
= NULL
;
2732 /* If alias and dentry share a parent, then no extra locks required */
2733 if (alias
->d_parent
== dentry
->d_parent
)
2736 /* See lock_rename() */
2737 if (!mutex_trylock(&dentry
->d_sb
->s_vfs_rename_mutex
))
2739 m1
= &dentry
->d_sb
->s_vfs_rename_mutex
;
2740 if (!mutex_trylock(&alias
->d_parent
->d_inode
->i_mutex
))
2742 m2
= &alias
->d_parent
->d_inode
->i_mutex
;
2744 __d_move(alias
, dentry
, false);
2755 * d_splice_alias - splice a disconnected dentry into the tree if one exists
2756 * @inode: the inode which may have a disconnected dentry
2757 * @dentry: a negative dentry which we want to point to the inode.
2759 * If inode is a directory and has an IS_ROOT alias, then d_move that in
2760 * place of the given dentry and return it, else simply d_add the inode
2761 * to the dentry and return NULL.
2763 * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
2764 * we should error out: directories can't have multiple aliases.
2766 * This is needed in the lookup routine of any filesystem that is exportable
2767 * (via knfsd) so that we can build dcache paths to directories effectively.
2769 * If a dentry was found and moved, then it is returned. Otherwise NULL
2770 * is returned. This matches the expected return value of ->lookup.
2772 * Cluster filesystems may call this function with a negative, hashed dentry.
2773 * In that case, we know that the inode will be a regular file, and also this
2774 * will only occur during atomic_open. So we need to check for the dentry
2775 * being already hashed only in the final case.
2777 struct dentry
*d_splice_alias(struct inode
*inode
, struct dentry
*dentry
)
2780 return ERR_CAST(inode
);
2782 BUG_ON(!d_unhashed(dentry
));
2785 __d_instantiate(dentry
, NULL
);
2788 spin_lock(&inode
->i_lock
);
2789 if (S_ISDIR(inode
->i_mode
)) {
2790 struct dentry
*new = __d_find_any_alias(inode
);
2791 if (unlikely(new)) {
2792 /* The reference to new ensures it remains an alias */
2793 spin_unlock(&inode
->i_lock
);
2794 write_seqlock(&rename_lock
);
2795 if (unlikely(d_ancestor(new, dentry
))) {
2796 write_sequnlock(&rename_lock
);
2798 new = ERR_PTR(-ELOOP
);
2799 pr_warn_ratelimited(
2800 "VFS: Lookup of '%s' in %s %s"
2801 " would have caused loop\n",
2802 dentry
->d_name
.name
,
2803 inode
->i_sb
->s_type
->name
,
2805 } else if (!IS_ROOT(new)) {
2806 int err
= __d_unalias(inode
, dentry
, new);
2807 write_sequnlock(&rename_lock
);
2813 __d_move(new, dentry
, false);
2814 write_sequnlock(&rename_lock
);
2815 security_d_instantiate(new, inode
);
2821 /* already taking inode->i_lock, so d_add() by hand */
2822 __d_instantiate(dentry
, inode
);
2823 spin_unlock(&inode
->i_lock
);
2825 security_d_instantiate(dentry
, inode
);
2829 EXPORT_SYMBOL(d_splice_alias
);
2831 static int prepend(char **buffer
, int *buflen
, const char *str
, int namelen
)
2835 return -ENAMETOOLONG
;
2837 memcpy(*buffer
, str
, namelen
);
2842 * prepend_name - prepend a pathname in front of current buffer pointer
2843 * @buffer: buffer pointer
2844 * @buflen: allocated length of the buffer
2845 * @name: name string and length qstr structure
2847 * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to
2848 * make sure that either the old or the new name pointer and length are
2849 * fetched. However, there may be mismatch between length and pointer.
2850 * The length cannot be trusted, we need to copy it byte-by-byte until
2851 * the length is reached or a null byte is found. It also prepends "/" at
2852 * the beginning of the name. The sequence number check at the caller will
2853 * retry it again when a d_move() does happen. So any garbage in the buffer
2854 * due to mismatched pointer and length will be discarded.
2856 * Data dependency barrier is needed to make sure that we see that terminating
2857 * NUL. Alpha strikes again, film at 11...
2859 static int prepend_name(char **buffer
, int *buflen
, struct qstr
*name
)
2861 const char *dname
= ACCESS_ONCE(name
->name
);
2862 u32 dlen
= ACCESS_ONCE(name
->len
);
2865 smp_read_barrier_depends();
2867 *buflen
-= dlen
+ 1;
2869 return -ENAMETOOLONG
;
2870 p
= *buffer
-= dlen
+ 1;
2882 * prepend_path - Prepend path string to a buffer
2883 * @path: the dentry/vfsmount to report
2884 * @root: root vfsmnt/dentry
2885 * @buffer: pointer to the end of the buffer
2886 * @buflen: pointer to buffer length
2888 * The function will first try to write out the pathname without taking any
2889 * lock other than the RCU read lock to make sure that dentries won't go away.
2890 * It only checks the sequence number of the global rename_lock as any change
2891 * in the dentry's d_seq will be preceded by changes in the rename_lock
2892 * sequence number. If the sequence number had been changed, it will restart
2893 * the whole pathname back-tracing sequence again by taking the rename_lock.
2894 * In this case, there is no need to take the RCU read lock as the recursive
2895 * parent pointer references will keep the dentry chain alive as long as no
2896 * rename operation is performed.
2898 static int prepend_path(const struct path
*path
,
2899 const struct path
*root
,
2900 char **buffer
, int *buflen
)
2902 struct dentry
*dentry
;
2903 struct vfsmount
*vfsmnt
;
2906 unsigned seq
, m_seq
= 0;
2912 read_seqbegin_or_lock(&mount_lock
, &m_seq
);
2919 dentry
= path
->dentry
;
2921 mnt
= real_mount(vfsmnt
);
2922 read_seqbegin_or_lock(&rename_lock
, &seq
);
2923 while (dentry
!= root
->dentry
|| vfsmnt
!= root
->mnt
) {
2924 struct dentry
* parent
;
2926 if (dentry
== vfsmnt
->mnt_root
|| IS_ROOT(dentry
)) {
2927 struct mount
*parent
= ACCESS_ONCE(mnt
->mnt_parent
);
2929 if (dentry
!= vfsmnt
->mnt_root
) {
2936 if (mnt
!= parent
) {
2937 dentry
= ACCESS_ONCE(mnt
->mnt_mountpoint
);
2943 error
= is_mounted(vfsmnt
) ? 1 : 2;
2946 parent
= dentry
->d_parent
;
2948 error
= prepend_name(&bptr
, &blen
, &dentry
->d_name
);
2956 if (need_seqretry(&rename_lock
, seq
)) {
2960 done_seqretry(&rename_lock
, seq
);
2964 if (need_seqretry(&mount_lock
, m_seq
)) {
2968 done_seqretry(&mount_lock
, m_seq
);
2970 if (error
>= 0 && bptr
== *buffer
) {
2972 error
= -ENAMETOOLONG
;
2982 * __d_path - return the path of a dentry
2983 * @path: the dentry/vfsmount to report
2984 * @root: root vfsmnt/dentry
2985 * @buf: buffer to return value in
2986 * @buflen: buffer length
2988 * Convert a dentry into an ASCII path name.
2990 * Returns a pointer into the buffer or an error code if the
2991 * path was too long.
2993 * "buflen" should be positive.
2995 * If the path is not reachable from the supplied root, return %NULL.
2997 char *__d_path(const struct path
*path
,
2998 const struct path
*root
,
2999 char *buf
, int buflen
)
3001 char *res
= buf
+ buflen
;
3004 prepend(&res
, &buflen
, "\0", 1);
3005 error
= prepend_path(path
, root
, &res
, &buflen
);
3008 return ERR_PTR(error
);
3014 char *d_absolute_path(const struct path
*path
,
3015 char *buf
, int buflen
)
3017 struct path root
= {};
3018 char *res
= buf
+ buflen
;
3021 prepend(&res
, &buflen
, "\0", 1);
3022 error
= prepend_path(path
, &root
, &res
, &buflen
);
3027 return ERR_PTR(error
);
3032 * same as __d_path but appends "(deleted)" for unlinked files.
3034 static int path_with_deleted(const struct path
*path
,
3035 const struct path
*root
,
3036 char **buf
, int *buflen
)
3038 prepend(buf
, buflen
, "\0", 1);
3039 if (d_unlinked(path
->dentry
)) {
3040 int error
= prepend(buf
, buflen
, " (deleted)", 10);
3045 return prepend_path(path
, root
, buf
, buflen
);
3048 static int prepend_unreachable(char **buffer
, int *buflen
)
3050 return prepend(buffer
, buflen
, "(unreachable)", 13);
3053 static void get_fs_root_rcu(struct fs_struct
*fs
, struct path
*root
)
3058 seq
= read_seqcount_begin(&fs
->seq
);
3060 } while (read_seqcount_retry(&fs
->seq
, seq
));
3064 * d_path - return the path of a dentry
3065 * @path: path to report
3066 * @buf: buffer to return value in
3067 * @buflen: buffer length
3069 * Convert a dentry into an ASCII path name. If the entry has been deleted
3070 * the string " (deleted)" is appended. Note that this is ambiguous.
3072 * Returns a pointer into the buffer or an error code if the path was
3073 * too long. Note: Callers should use the returned pointer, not the passed
3074 * in buffer, to use the name! The implementation often starts at an offset
3075 * into the buffer, and may leave 0 bytes at the start.
3077 * "buflen" should be positive.
3079 char *d_path(const struct path
*path
, char *buf
, int buflen
)
3081 char *res
= buf
+ buflen
;
3086 * We have various synthetic filesystems that never get mounted. On
3087 * these filesystems dentries are never used for lookup purposes, and
3088 * thus don't need to be hashed. They also don't need a name until a
3089 * user wants to identify the object in /proc/pid/fd/. The little hack
3090 * below allows us to generate a name for these objects on demand:
3092 * Some pseudo inodes are mountable. When they are mounted
3093 * path->dentry == path->mnt->mnt_root. In that case don't call d_dname
3094 * and instead have d_path return the mounted path.
3096 if (path
->dentry
->d_op
&& path
->dentry
->d_op
->d_dname
&&
3097 (!IS_ROOT(path
->dentry
) || path
->dentry
!= path
->mnt
->mnt_root
))
3098 return path
->dentry
->d_op
->d_dname(path
->dentry
, buf
, buflen
);
3101 get_fs_root_rcu(current
->fs
, &root
);
3102 error
= path_with_deleted(path
, &root
, &res
, &buflen
);
3106 res
= ERR_PTR(error
);
3109 EXPORT_SYMBOL(d_path
);
3112 * Helper function for dentry_operations.d_dname() members
3114 char *dynamic_dname(struct dentry
*dentry
, char *buffer
, int buflen
,
3115 const char *fmt
, ...)
3121 va_start(args
, fmt
);
3122 sz
= vsnprintf(temp
, sizeof(temp
), fmt
, args
) + 1;
3125 if (sz
> sizeof(temp
) || sz
> buflen
)
3126 return ERR_PTR(-ENAMETOOLONG
);
3128 buffer
+= buflen
- sz
;
3129 return memcpy(buffer
, temp
, sz
);
3132 char *simple_dname(struct dentry
*dentry
, char *buffer
, int buflen
)
3134 char *end
= buffer
+ buflen
;
3135 /* these dentries are never renamed, so d_lock is not needed */
3136 if (prepend(&end
, &buflen
, " (deleted)", 11) ||
3137 prepend(&end
, &buflen
, dentry
->d_name
.name
, dentry
->d_name
.len
) ||
3138 prepend(&end
, &buflen
, "/", 1))
3139 end
= ERR_PTR(-ENAMETOOLONG
);
3142 EXPORT_SYMBOL(simple_dname
);
3145 * Write full pathname from the root of the filesystem into the buffer.
3147 static char *__dentry_path(struct dentry
*d
, char *buf
, int buflen
)
3149 struct dentry
*dentry
;
3162 prepend(&end
, &len
, "\0", 1);
3166 read_seqbegin_or_lock(&rename_lock
, &seq
);
3167 while (!IS_ROOT(dentry
)) {
3168 struct dentry
*parent
= dentry
->d_parent
;
3171 error
= prepend_name(&end
, &len
, &dentry
->d_name
);
3180 if (need_seqretry(&rename_lock
, seq
)) {
3184 done_seqretry(&rename_lock
, seq
);
3189 return ERR_PTR(-ENAMETOOLONG
);
3192 char *dentry_path_raw(struct dentry
*dentry
, char *buf
, int buflen
)
3194 return __dentry_path(dentry
, buf
, buflen
);
3196 EXPORT_SYMBOL(dentry_path_raw
);
3198 char *dentry_path(struct dentry
*dentry
, char *buf
, int buflen
)
3203 if (d_unlinked(dentry
)) {
3205 if (prepend(&p
, &buflen
, "//deleted", 10) != 0)
3209 retval
= __dentry_path(dentry
, buf
, buflen
);
3210 if (!IS_ERR(retval
) && p
)
3211 *p
= '/'; /* restore '/' overriden with '\0' */
3214 return ERR_PTR(-ENAMETOOLONG
);
3217 static void get_fs_root_and_pwd_rcu(struct fs_struct
*fs
, struct path
*root
,
3223 seq
= read_seqcount_begin(&fs
->seq
);
3226 } while (read_seqcount_retry(&fs
->seq
, seq
));
3230 * NOTE! The user-level library version returns a
3231 * character pointer. The kernel system call just
3232 * returns the length of the buffer filled (which
3233 * includes the ending '\0' character), or a negative
3234 * error value. So libc would do something like
3236 * char *getcwd(char * buf, size_t size)
3240 * retval = sys_getcwd(buf, size);
3247 SYSCALL_DEFINE2(getcwd
, char __user
*, buf
, unsigned long, size
)
3250 struct path pwd
, root
;
3251 char *page
= __getname();
3257 get_fs_root_and_pwd_rcu(current
->fs
, &root
, &pwd
);
3260 if (!d_unlinked(pwd
.dentry
)) {
3262 char *cwd
= page
+ PATH_MAX
;
3263 int buflen
= PATH_MAX
;
3265 prepend(&cwd
, &buflen
, "\0", 1);
3266 error
= prepend_path(&pwd
, &root
, &cwd
, &buflen
);
3272 /* Unreachable from current root */
3274 error
= prepend_unreachable(&cwd
, &buflen
);
3280 len
= PATH_MAX
+ page
- cwd
;
3283 if (copy_to_user(buf
, cwd
, len
))
3296 * Test whether new_dentry is a subdirectory of old_dentry.
3298 * Trivially implemented using the dcache structure
3302 * is_subdir - is new dentry a subdirectory of old_dentry
3303 * @new_dentry: new dentry
3304 * @old_dentry: old dentry
3306 * Returns true if new_dentry is a subdirectory of the parent (at any depth).
3307 * Returns false otherwise.
3308 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
3311 bool is_subdir(struct dentry
*new_dentry
, struct dentry
*old_dentry
)
3316 if (new_dentry
== old_dentry
)
3320 /* for restarting inner loop in case of seq retry */
3321 seq
= read_seqbegin(&rename_lock
);
3323 * Need rcu_readlock to protect against the d_parent trashing
3327 if (d_ancestor(old_dentry
, new_dentry
))
3332 } while (read_seqretry(&rename_lock
, seq
));
3337 static enum d_walk_ret
d_genocide_kill(void *data
, struct dentry
*dentry
)
3339 struct dentry
*root
= data
;
3340 if (dentry
!= root
) {
3341 if (d_unhashed(dentry
) || !dentry
->d_inode
)
3344 if (!(dentry
->d_flags
& DCACHE_GENOCIDE
)) {
3345 dentry
->d_flags
|= DCACHE_GENOCIDE
;
3346 dentry
->d_lockref
.count
--;
3349 return D_WALK_CONTINUE
;
3352 void d_genocide(struct dentry
*parent
)
3354 d_walk(parent
, parent
, d_genocide_kill
, NULL
);
3357 void d_tmpfile(struct dentry
*dentry
, struct inode
*inode
)
3359 inode_dec_link_count(inode
);
3360 BUG_ON(dentry
->d_name
.name
!= dentry
->d_iname
||
3361 !hlist_unhashed(&dentry
->d_u
.d_alias
) ||
3362 !d_unlinked(dentry
));
3363 spin_lock(&dentry
->d_parent
->d_lock
);
3364 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
3365 dentry
->d_name
.len
= sprintf(dentry
->d_iname
, "#%llu",
3366 (unsigned long long)inode
->i_ino
);
3367 spin_unlock(&dentry
->d_lock
);
3368 spin_unlock(&dentry
->d_parent
->d_lock
);
3369 d_instantiate(dentry
, inode
);
3371 EXPORT_SYMBOL(d_tmpfile
);
3373 static __initdata
unsigned long dhash_entries
;
3374 static int __init
set_dhash_entries(char *str
)
3378 dhash_entries
= simple_strtoul(str
, &str
, 0);
3381 __setup("dhash_entries=", set_dhash_entries
);
3383 static void __init
dcache_init_early(void)
3387 /* If hashes are distributed across NUMA nodes, defer
3388 * hash allocation until vmalloc space is available.
3394 alloc_large_system_hash("Dentry cache",
3395 sizeof(struct hlist_bl_head
),
3404 for (loop
= 0; loop
< (1U << d_hash_shift
); loop
++)
3405 INIT_HLIST_BL_HEAD(dentry_hashtable
+ loop
);
3408 static void __init
dcache_init(void)
3413 * A constructor could be added for stable state like the lists,
3414 * but it is probably not worth it because of the cache nature
3417 dentry_cache
= KMEM_CACHE(dentry
,
3418 SLAB_RECLAIM_ACCOUNT
|SLAB_PANIC
|SLAB_MEM_SPREAD
);
3420 /* Hash may have been set up in dcache_init_early */
3425 alloc_large_system_hash("Dentry cache",
3426 sizeof(struct hlist_bl_head
),
3435 for (loop
= 0; loop
< (1U << d_hash_shift
); loop
++)
3436 INIT_HLIST_BL_HEAD(dentry_hashtable
+ loop
);
3439 /* SLAB cache for __getname() consumers */
3440 struct kmem_cache
*names_cachep __read_mostly
;
3441 EXPORT_SYMBOL(names_cachep
);
3443 EXPORT_SYMBOL(d_genocide
);
3445 void __init
vfs_caches_init_early(void)
3447 dcache_init_early();
3451 void __init
vfs_caches_init(void)
3453 names_cachep
= kmem_cache_create("names_cache", PATH_MAX
, 0,
3454 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
3459 files_maxfiles_init();