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
;
272 static inline void __d_set_inode_and_type(struct dentry
*dentry
,
278 dentry
->d_inode
= inode
;
279 flags
= READ_ONCE(dentry
->d_flags
);
280 flags
&= ~(DCACHE_ENTRY_TYPE
| DCACHE_FALLTHRU
);
282 WRITE_ONCE(dentry
->d_flags
, flags
);
285 static inline void __d_clear_type_and_inode(struct dentry
*dentry
)
287 unsigned flags
= READ_ONCE(dentry
->d_flags
);
289 flags
&= ~(DCACHE_ENTRY_TYPE
| DCACHE_FALLTHRU
);
290 WRITE_ONCE(dentry
->d_flags
, flags
);
291 dentry
->d_inode
= NULL
;
294 static void dentry_free(struct dentry
*dentry
)
296 WARN_ON(!hlist_unhashed(&dentry
->d_u
.d_alias
));
297 if (unlikely(dname_external(dentry
))) {
298 struct external_name
*p
= external_name(dentry
);
299 if (likely(atomic_dec_and_test(&p
->u
.count
))) {
300 call_rcu(&dentry
->d_u
.d_rcu
, __d_free_external
);
304 /* if dentry was never visible to RCU, immediate free is OK */
305 if (!(dentry
->d_flags
& DCACHE_RCUACCESS
))
306 __d_free(&dentry
->d_u
.d_rcu
);
308 call_rcu(&dentry
->d_u
.d_rcu
, __d_free
);
312 * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups
313 * @dentry: the target dentry
314 * After this call, in-progress rcu-walk path lookup will fail. This
315 * should be called after unhashing, and after changing d_inode (if
316 * the dentry has not already been unhashed).
318 static inline void dentry_rcuwalk_invalidate(struct dentry
*dentry
)
320 lockdep_assert_held(&dentry
->d_lock
);
321 /* Go through am invalidation barrier */
322 write_seqcount_invalidate(&dentry
->d_seq
);
326 * Release the dentry's inode, using the filesystem
327 * d_iput() operation if defined. Dentry has no refcount
330 static void dentry_iput(struct dentry
* dentry
)
331 __releases(dentry
->d_lock
)
332 __releases(dentry
->d_inode
->i_lock
)
334 struct inode
*inode
= dentry
->d_inode
;
336 __d_clear_type_and_inode(dentry
);
337 hlist_del_init(&dentry
->d_u
.d_alias
);
338 spin_unlock(&dentry
->d_lock
);
339 spin_unlock(&inode
->i_lock
);
341 fsnotify_inoderemove(inode
);
342 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
343 dentry
->d_op
->d_iput(dentry
, inode
);
347 spin_unlock(&dentry
->d_lock
);
352 * Release the dentry's inode, using the filesystem
353 * d_iput() operation if defined. dentry remains in-use.
355 static void dentry_unlink_inode(struct dentry
* dentry
)
356 __releases(dentry
->d_lock
)
357 __releases(dentry
->d_inode
->i_lock
)
359 struct inode
*inode
= dentry
->d_inode
;
361 raw_write_seqcount_begin(&dentry
->d_seq
);
362 __d_clear_type_and_inode(dentry
);
363 hlist_del_init(&dentry
->d_u
.d_alias
);
364 raw_write_seqcount_end(&dentry
->d_seq
);
365 spin_unlock(&dentry
->d_lock
);
366 spin_unlock(&inode
->i_lock
);
368 fsnotify_inoderemove(inode
);
369 if (dentry
->d_op
&& dentry
->d_op
->d_iput
)
370 dentry
->d_op
->d_iput(dentry
, inode
);
376 * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
377 * is in use - which includes both the "real" per-superblock
378 * LRU list _and_ the DCACHE_SHRINK_LIST use.
380 * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
381 * on the shrink list (ie not on the superblock LRU list).
383 * The per-cpu "nr_dentry_unused" counters are updated with
384 * the DCACHE_LRU_LIST bit.
386 * These helper functions make sure we always follow the
387 * rules. d_lock must be held by the caller.
389 #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
390 static void d_lru_add(struct dentry
*dentry
)
392 D_FLAG_VERIFY(dentry
, 0);
393 dentry
->d_flags
|= DCACHE_LRU_LIST
;
394 this_cpu_inc(nr_dentry_unused
);
395 WARN_ON_ONCE(!list_lru_add(&dentry
->d_sb
->s_dentry_lru
, &dentry
->d_lru
));
398 static void d_lru_del(struct dentry
*dentry
)
400 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
401 dentry
->d_flags
&= ~DCACHE_LRU_LIST
;
402 this_cpu_dec(nr_dentry_unused
);
403 WARN_ON_ONCE(!list_lru_del(&dentry
->d_sb
->s_dentry_lru
, &dentry
->d_lru
));
406 static void d_shrink_del(struct dentry
*dentry
)
408 D_FLAG_VERIFY(dentry
, DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
);
409 list_del_init(&dentry
->d_lru
);
410 dentry
->d_flags
&= ~(DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
);
411 this_cpu_dec(nr_dentry_unused
);
414 static void d_shrink_add(struct dentry
*dentry
, struct list_head
*list
)
416 D_FLAG_VERIFY(dentry
, 0);
417 list_add(&dentry
->d_lru
, list
);
418 dentry
->d_flags
|= DCACHE_SHRINK_LIST
| DCACHE_LRU_LIST
;
419 this_cpu_inc(nr_dentry_unused
);
423 * These can only be called under the global LRU lock, ie during the
424 * callback for freeing the LRU list. "isolate" removes it from the
425 * LRU lists entirely, while shrink_move moves it to the indicated
428 static void d_lru_isolate(struct list_lru_one
*lru
, struct dentry
*dentry
)
430 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
431 dentry
->d_flags
&= ~DCACHE_LRU_LIST
;
432 this_cpu_dec(nr_dentry_unused
);
433 list_lru_isolate(lru
, &dentry
->d_lru
);
436 static void d_lru_shrink_move(struct list_lru_one
*lru
, struct dentry
*dentry
,
437 struct list_head
*list
)
439 D_FLAG_VERIFY(dentry
, DCACHE_LRU_LIST
);
440 dentry
->d_flags
|= DCACHE_SHRINK_LIST
;
441 list_lru_isolate_move(lru
, &dentry
->d_lru
, list
);
445 * dentry_lru_(add|del)_list) must be called with d_lock held.
447 static void dentry_lru_add(struct dentry
*dentry
)
449 if (unlikely(!(dentry
->d_flags
& DCACHE_LRU_LIST
)))
454 * d_drop - drop a dentry
455 * @dentry: dentry to drop
457 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
458 * be found through a VFS lookup any more. Note that this is different from
459 * deleting the dentry - d_delete will try to mark the dentry negative if
460 * possible, giving a successful _negative_ lookup, while d_drop will
461 * just make the cache lookup fail.
463 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
464 * reason (NFS timeouts or autofs deletes).
466 * __d_drop requires dentry->d_lock.
468 void __d_drop(struct dentry
*dentry
)
470 if (!d_unhashed(dentry
)) {
471 struct hlist_bl_head
*b
;
473 * Hashed dentries are normally on the dentry hashtable,
474 * with the exception of those newly allocated by
475 * d_obtain_alias, which are always IS_ROOT:
477 if (unlikely(IS_ROOT(dentry
)))
478 b
= &dentry
->d_sb
->s_anon
;
480 b
= d_hash(dentry
->d_parent
, dentry
->d_name
.hash
);
483 __hlist_bl_del(&dentry
->d_hash
);
484 dentry
->d_hash
.pprev
= NULL
;
486 dentry_rcuwalk_invalidate(dentry
);
489 EXPORT_SYMBOL(__d_drop
);
491 void d_drop(struct dentry
*dentry
)
493 spin_lock(&dentry
->d_lock
);
495 spin_unlock(&dentry
->d_lock
);
497 EXPORT_SYMBOL(d_drop
);
499 static void __dentry_kill(struct dentry
*dentry
)
501 struct dentry
*parent
= NULL
;
502 bool can_free
= true;
503 if (!IS_ROOT(dentry
))
504 parent
= dentry
->d_parent
;
507 * The dentry is now unrecoverably dead to the world.
509 lockref_mark_dead(&dentry
->d_lockref
);
512 * inform the fs via d_prune that this dentry is about to be
513 * unhashed and destroyed.
515 if (dentry
->d_flags
& DCACHE_OP_PRUNE
)
516 dentry
->d_op
->d_prune(dentry
);
518 if (dentry
->d_flags
& DCACHE_LRU_LIST
) {
519 if (!(dentry
->d_flags
& DCACHE_SHRINK_LIST
))
522 /* if it was on the hash then remove it */
524 __list_del_entry(&dentry
->d_child
);
526 * Inform d_walk() that we are no longer attached to the
529 dentry
->d_flags
|= DCACHE_DENTRY_KILLED
;
531 spin_unlock(&parent
->d_lock
);
534 * dentry_iput drops the locks, at which point nobody (except
535 * transient RCU lookups) can reach this dentry.
537 BUG_ON(dentry
->d_lockref
.count
> 0);
538 this_cpu_dec(nr_dentry
);
539 if (dentry
->d_op
&& dentry
->d_op
->d_release
)
540 dentry
->d_op
->d_release(dentry
);
542 spin_lock(&dentry
->d_lock
);
543 if (dentry
->d_flags
& DCACHE_SHRINK_LIST
) {
544 dentry
->d_flags
|= DCACHE_MAY_FREE
;
547 spin_unlock(&dentry
->d_lock
);
548 if (likely(can_free
))
553 * Finish off a dentry we've decided to kill.
554 * dentry->d_lock must be held, returns with it unlocked.
555 * If ref is non-zero, then decrement the refcount too.
556 * Returns dentry requiring refcount drop, or NULL if we're done.
558 static struct dentry
*dentry_kill(struct dentry
*dentry
)
559 __releases(dentry
->d_lock
)
561 struct inode
*inode
= dentry
->d_inode
;
562 struct dentry
*parent
= NULL
;
564 if (inode
&& unlikely(!spin_trylock(&inode
->i_lock
)))
567 if (!IS_ROOT(dentry
)) {
568 parent
= dentry
->d_parent
;
569 if (unlikely(!spin_trylock(&parent
->d_lock
))) {
571 spin_unlock(&inode
->i_lock
);
576 __dentry_kill(dentry
);
580 spin_unlock(&dentry
->d_lock
);
581 return dentry
; /* try again with same dentry */
584 static inline struct dentry
*lock_parent(struct dentry
*dentry
)
586 struct dentry
*parent
= dentry
->d_parent
;
589 if (unlikely(dentry
->d_lockref
.count
< 0))
591 if (likely(spin_trylock(&parent
->d_lock
)))
594 spin_unlock(&dentry
->d_lock
);
596 parent
= ACCESS_ONCE(dentry
->d_parent
);
597 spin_lock(&parent
->d_lock
);
599 * We can't blindly lock dentry until we are sure
600 * that we won't violate the locking order.
601 * Any changes of dentry->d_parent must have
602 * been done with parent->d_lock held, so
603 * spin_lock() above is enough of a barrier
604 * for checking if it's still our child.
606 if (unlikely(parent
!= dentry
->d_parent
)) {
607 spin_unlock(&parent
->d_lock
);
611 if (parent
!= dentry
)
612 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
619 * Try to do a lockless dput(), and return whether that was successful.
621 * If unsuccessful, we return false, having already taken the dentry lock.
623 * The caller needs to hold the RCU read lock, so that the dentry is
624 * guaranteed to stay around even if the refcount goes down to zero!
626 static inline bool fast_dput(struct dentry
*dentry
)
629 unsigned int d_flags
;
632 * If we have a d_op->d_delete() operation, we sould not
633 * let the dentry count go to zero, so use "put_or_lock".
635 if (unlikely(dentry
->d_flags
& DCACHE_OP_DELETE
))
636 return lockref_put_or_lock(&dentry
->d_lockref
);
639 * .. otherwise, we can try to just decrement the
640 * lockref optimistically.
642 ret
= lockref_put_return(&dentry
->d_lockref
);
645 * If the lockref_put_return() failed due to the lock being held
646 * by somebody else, the fast path has failed. We will need to
647 * get the lock, and then check the count again.
649 if (unlikely(ret
< 0)) {
650 spin_lock(&dentry
->d_lock
);
651 if (dentry
->d_lockref
.count
> 1) {
652 dentry
->d_lockref
.count
--;
653 spin_unlock(&dentry
->d_lock
);
660 * If we weren't the last ref, we're done.
666 * Careful, careful. The reference count went down
667 * to zero, but we don't hold the dentry lock, so
668 * somebody else could get it again, and do another
669 * dput(), and we need to not race with that.
671 * However, there is a very special and common case
672 * where we don't care, because there is nothing to
673 * do: the dentry is still hashed, it does not have
674 * a 'delete' op, and it's referenced and already on
677 * NOTE! Since we aren't locked, these values are
678 * not "stable". However, it is sufficient that at
679 * some point after we dropped the reference the
680 * dentry was hashed and the flags had the proper
681 * value. Other dentry users may have re-gotten
682 * a reference to the dentry and change that, but
683 * our work is done - we can leave the dentry
684 * around with a zero refcount.
687 d_flags
= ACCESS_ONCE(dentry
->d_flags
);
688 d_flags
&= DCACHE_REFERENCED
| DCACHE_LRU_LIST
| DCACHE_DISCONNECTED
;
690 /* Nothing to do? Dropping the reference was all we needed? */
691 if (d_flags
== (DCACHE_REFERENCED
| DCACHE_LRU_LIST
) && !d_unhashed(dentry
))
695 * Not the fast normal case? Get the lock. We've already decremented
696 * the refcount, but we'll need to re-check the situation after
699 spin_lock(&dentry
->d_lock
);
702 * Did somebody else grab a reference to it in the meantime, and
703 * we're no longer the last user after all? Alternatively, somebody
704 * else could have killed it and marked it dead. Either way, we
705 * don't need to do anything else.
707 if (dentry
->d_lockref
.count
) {
708 spin_unlock(&dentry
->d_lock
);
713 * Re-get the reference we optimistically dropped. We hold the
714 * lock, and we just tested that it was zero, so we can just
717 dentry
->d_lockref
.count
= 1;
725 * This is complicated by the fact that we do not want to put
726 * dentries that are no longer on any hash chain on the unused
727 * list: we'd much rather just get rid of them immediately.
729 * However, that implies that we have to traverse the dentry
730 * tree upwards to the parents which might _also_ now be
731 * scheduled for deletion (it may have been only waiting for
732 * its last child to go away).
734 * This tail recursion is done by hand as we don't want to depend
735 * on the compiler to always get this right (gcc generally doesn't).
736 * Real recursion would eat up our stack space.
740 * dput - release a dentry
741 * @dentry: dentry to release
743 * Release a dentry. This will drop the usage count and if appropriate
744 * call the dentry unlink method as well as removing it from the queues and
745 * releasing its resources. If the parent dentries were scheduled for release
746 * they too may now get deleted.
748 void dput(struct dentry
*dentry
)
750 if (unlikely(!dentry
))
757 if (likely(fast_dput(dentry
))) {
762 /* Slow case: now with the dentry lock held */
765 /* Unreachable? Get rid of it */
766 if (unlikely(d_unhashed(dentry
)))
769 if (unlikely(dentry
->d_flags
& DCACHE_DISCONNECTED
))
772 if (unlikely(dentry
->d_flags
& DCACHE_OP_DELETE
)) {
773 if (dentry
->d_op
->d_delete(dentry
))
777 if (!(dentry
->d_flags
& DCACHE_REFERENCED
))
778 dentry
->d_flags
|= DCACHE_REFERENCED
;
779 dentry_lru_add(dentry
);
781 dentry
->d_lockref
.count
--;
782 spin_unlock(&dentry
->d_lock
);
786 dentry
= dentry_kill(dentry
);
795 /* This must be called with d_lock held */
796 static inline void __dget_dlock(struct dentry
*dentry
)
798 dentry
->d_lockref
.count
++;
801 static inline void __dget(struct dentry
*dentry
)
803 lockref_get(&dentry
->d_lockref
);
806 struct dentry
*dget_parent(struct dentry
*dentry
)
812 * Do optimistic parent lookup without any
816 ret
= ACCESS_ONCE(dentry
->d_parent
);
817 gotref
= lockref_get_not_zero(&ret
->d_lockref
);
819 if (likely(gotref
)) {
820 if (likely(ret
== ACCESS_ONCE(dentry
->d_parent
)))
827 * Don't need rcu_dereference because we re-check it was correct under
831 ret
= dentry
->d_parent
;
832 spin_lock(&ret
->d_lock
);
833 if (unlikely(ret
!= dentry
->d_parent
)) {
834 spin_unlock(&ret
->d_lock
);
839 BUG_ON(!ret
->d_lockref
.count
);
840 ret
->d_lockref
.count
++;
841 spin_unlock(&ret
->d_lock
);
844 EXPORT_SYMBOL(dget_parent
);
847 * d_find_alias - grab a hashed alias of inode
848 * @inode: inode in question
850 * If inode has a hashed alias, or is a directory and has any alias,
851 * acquire the reference to alias and return it. Otherwise return NULL.
852 * Notice that if inode is a directory there can be only one alias and
853 * it can be unhashed only if it has no children, or if it is the root
854 * of a filesystem, or if the directory was renamed and d_revalidate
855 * was the first vfs operation to notice.
857 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
858 * any other hashed alias over that one.
860 static struct dentry
*__d_find_alias(struct inode
*inode
)
862 struct dentry
*alias
, *discon_alias
;
866 hlist_for_each_entry(alias
, &inode
->i_dentry
, d_u
.d_alias
) {
867 spin_lock(&alias
->d_lock
);
868 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
869 if (IS_ROOT(alias
) &&
870 (alias
->d_flags
& DCACHE_DISCONNECTED
)) {
871 discon_alias
= alias
;
874 spin_unlock(&alias
->d_lock
);
878 spin_unlock(&alias
->d_lock
);
881 alias
= discon_alias
;
882 spin_lock(&alias
->d_lock
);
883 if (S_ISDIR(inode
->i_mode
) || !d_unhashed(alias
)) {
885 spin_unlock(&alias
->d_lock
);
888 spin_unlock(&alias
->d_lock
);
894 struct dentry
*d_find_alias(struct inode
*inode
)
896 struct dentry
*de
= NULL
;
898 if (!hlist_empty(&inode
->i_dentry
)) {
899 spin_lock(&inode
->i_lock
);
900 de
= __d_find_alias(inode
);
901 spin_unlock(&inode
->i_lock
);
905 EXPORT_SYMBOL(d_find_alias
);
908 * Try to kill dentries associated with this inode.
909 * WARNING: you must own a reference to inode.
911 void d_prune_aliases(struct inode
*inode
)
913 struct dentry
*dentry
;
915 spin_lock(&inode
->i_lock
);
916 hlist_for_each_entry(dentry
, &inode
->i_dentry
, d_u
.d_alias
) {
917 spin_lock(&dentry
->d_lock
);
918 if (!dentry
->d_lockref
.count
) {
919 struct dentry
*parent
= lock_parent(dentry
);
920 if (likely(!dentry
->d_lockref
.count
)) {
921 __dentry_kill(dentry
);
926 spin_unlock(&parent
->d_lock
);
928 spin_unlock(&dentry
->d_lock
);
930 spin_unlock(&inode
->i_lock
);
932 EXPORT_SYMBOL(d_prune_aliases
);
934 static void shrink_dentry_list(struct list_head
*list
)
936 struct dentry
*dentry
, *parent
;
938 while (!list_empty(list
)) {
940 dentry
= list_entry(list
->prev
, struct dentry
, d_lru
);
941 spin_lock(&dentry
->d_lock
);
942 parent
= lock_parent(dentry
);
945 * The dispose list is isolated and dentries are not accounted
946 * to the LRU here, so we can simply remove it from the list
947 * here regardless of whether it is referenced or not.
949 d_shrink_del(dentry
);
952 * We found an inuse dentry which was not removed from
953 * the LRU because of laziness during lookup. Do not free it.
955 if (dentry
->d_lockref
.count
> 0) {
956 spin_unlock(&dentry
->d_lock
);
958 spin_unlock(&parent
->d_lock
);
963 if (unlikely(dentry
->d_flags
& DCACHE_DENTRY_KILLED
)) {
964 bool can_free
= dentry
->d_flags
& DCACHE_MAY_FREE
;
965 spin_unlock(&dentry
->d_lock
);
967 spin_unlock(&parent
->d_lock
);
973 inode
= dentry
->d_inode
;
974 if (inode
&& unlikely(!spin_trylock(&inode
->i_lock
))) {
975 d_shrink_add(dentry
, list
);
976 spin_unlock(&dentry
->d_lock
);
978 spin_unlock(&parent
->d_lock
);
982 __dentry_kill(dentry
);
985 * We need to prune ancestors too. This is necessary to prevent
986 * quadratic behavior of shrink_dcache_parent(), but is also
987 * expected to be beneficial in reducing dentry cache
991 while (dentry
&& !lockref_put_or_lock(&dentry
->d_lockref
)) {
992 parent
= lock_parent(dentry
);
993 if (dentry
->d_lockref
.count
!= 1) {
994 dentry
->d_lockref
.count
--;
995 spin_unlock(&dentry
->d_lock
);
997 spin_unlock(&parent
->d_lock
);
1000 inode
= dentry
->d_inode
; /* can't be NULL */
1001 if (unlikely(!spin_trylock(&inode
->i_lock
))) {
1002 spin_unlock(&dentry
->d_lock
);
1004 spin_unlock(&parent
->d_lock
);
1008 __dentry_kill(dentry
);
1014 static enum lru_status
dentry_lru_isolate(struct list_head
*item
,
1015 struct list_lru_one
*lru
, spinlock_t
*lru_lock
, void *arg
)
1017 struct list_head
*freeable
= arg
;
1018 struct dentry
*dentry
= container_of(item
, struct dentry
, d_lru
);
1022 * we are inverting the lru lock/dentry->d_lock here,
1023 * so use a trylock. If we fail to get the lock, just skip
1026 if (!spin_trylock(&dentry
->d_lock
))
1030 * Referenced dentries are still in use. If they have active
1031 * counts, just remove them from the LRU. Otherwise give them
1032 * another pass through the LRU.
1034 if (dentry
->d_lockref
.count
) {
1035 d_lru_isolate(lru
, dentry
);
1036 spin_unlock(&dentry
->d_lock
);
1040 if (dentry
->d_flags
& DCACHE_REFERENCED
) {
1041 dentry
->d_flags
&= ~DCACHE_REFERENCED
;
1042 spin_unlock(&dentry
->d_lock
);
1045 * The list move itself will be made by the common LRU code. At
1046 * this point, we've dropped the dentry->d_lock but keep the
1047 * lru lock. This is safe to do, since every list movement is
1048 * protected by the lru lock even if both locks are held.
1050 * This is guaranteed by the fact that all LRU management
1051 * functions are intermediated by the LRU API calls like
1052 * list_lru_add and list_lru_del. List movement in this file
1053 * only ever occur through this functions or through callbacks
1054 * like this one, that are called from the LRU API.
1056 * The only exceptions to this are functions like
1057 * shrink_dentry_list, and code that first checks for the
1058 * DCACHE_SHRINK_LIST flag. Those are guaranteed to be
1059 * operating only with stack provided lists after they are
1060 * properly isolated from the main list. It is thus, always a
1066 d_lru_shrink_move(lru
, dentry
, freeable
);
1067 spin_unlock(&dentry
->d_lock
);
1073 * prune_dcache_sb - shrink the dcache
1075 * @sc: shrink control, passed to list_lru_shrink_walk()
1077 * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This
1078 * is done when we need more memory and called from the superblock shrinker
1081 * This function may fail to free any resources if all the dentries are in
1084 long prune_dcache_sb(struct super_block
*sb
, struct shrink_control
*sc
)
1089 freed
= list_lru_shrink_walk(&sb
->s_dentry_lru
, sc
,
1090 dentry_lru_isolate
, &dispose
);
1091 shrink_dentry_list(&dispose
);
1095 static enum lru_status
dentry_lru_isolate_shrink(struct list_head
*item
,
1096 struct list_lru_one
*lru
, spinlock_t
*lru_lock
, void *arg
)
1098 struct list_head
*freeable
= arg
;
1099 struct dentry
*dentry
= container_of(item
, struct dentry
, d_lru
);
1102 * we are inverting the lru lock/dentry->d_lock here,
1103 * so use a trylock. If we fail to get the lock, just skip
1106 if (!spin_trylock(&dentry
->d_lock
))
1109 d_lru_shrink_move(lru
, dentry
, freeable
);
1110 spin_unlock(&dentry
->d_lock
);
1117 * shrink_dcache_sb - shrink dcache for a superblock
1120 * Shrink the dcache for the specified super block. This is used to free
1121 * the dcache before unmounting a file system.
1123 void shrink_dcache_sb(struct super_block
*sb
)
1130 freed
= list_lru_walk(&sb
->s_dentry_lru
,
1131 dentry_lru_isolate_shrink
, &dispose
, UINT_MAX
);
1133 this_cpu_sub(nr_dentry_unused
, freed
);
1134 shrink_dentry_list(&dispose
);
1135 } while (freed
> 0);
1137 EXPORT_SYMBOL(shrink_dcache_sb
);
1140 * enum d_walk_ret - action to talke during tree walk
1141 * @D_WALK_CONTINUE: contrinue walk
1142 * @D_WALK_QUIT: quit walk
1143 * @D_WALK_NORETRY: quit when retry is needed
1144 * @D_WALK_SKIP: skip this dentry and its children
1154 * d_walk - walk the dentry tree
1155 * @parent: start of walk
1156 * @data: data passed to @enter() and @finish()
1157 * @enter: callback when first entering the dentry
1158 * @finish: callback when successfully finished the walk
1160 * The @enter() and @finish() callbacks are called with d_lock held.
1162 static void d_walk(struct dentry
*parent
, void *data
,
1163 enum d_walk_ret (*enter
)(void *, struct dentry
*),
1164 void (*finish
)(void *))
1166 struct dentry
*this_parent
;
1167 struct list_head
*next
;
1169 enum d_walk_ret ret
;
1173 read_seqbegin_or_lock(&rename_lock
, &seq
);
1174 this_parent
= parent
;
1175 spin_lock(&this_parent
->d_lock
);
1177 ret
= enter(data
, this_parent
);
1179 case D_WALK_CONTINUE
:
1184 case D_WALK_NORETRY
:
1189 next
= this_parent
->d_subdirs
.next
;
1191 while (next
!= &this_parent
->d_subdirs
) {
1192 struct list_head
*tmp
= next
;
1193 struct dentry
*dentry
= list_entry(tmp
, struct dentry
, d_child
);
1196 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
1198 ret
= enter(data
, dentry
);
1200 case D_WALK_CONTINUE
:
1203 spin_unlock(&dentry
->d_lock
);
1205 case D_WALK_NORETRY
:
1209 spin_unlock(&dentry
->d_lock
);
1213 if (!list_empty(&dentry
->d_subdirs
)) {
1214 spin_unlock(&this_parent
->d_lock
);
1215 spin_release(&dentry
->d_lock
.dep_map
, 1, _RET_IP_
);
1216 this_parent
= dentry
;
1217 spin_acquire(&this_parent
->d_lock
.dep_map
, 0, 1, _RET_IP_
);
1220 spin_unlock(&dentry
->d_lock
);
1223 * All done at this level ... ascend and resume the search.
1227 if (this_parent
!= parent
) {
1228 struct dentry
*child
= this_parent
;
1229 this_parent
= child
->d_parent
;
1231 spin_unlock(&child
->d_lock
);
1232 spin_lock(&this_parent
->d_lock
);
1234 /* might go back up the wrong parent if we have had a rename. */
1235 if (need_seqretry(&rename_lock
, seq
))
1237 /* go into the first sibling still alive */
1239 next
= child
->d_child
.next
;
1240 if (next
== &this_parent
->d_subdirs
)
1242 child
= list_entry(next
, struct dentry
, d_child
);
1243 } while (unlikely(child
->d_flags
& DCACHE_DENTRY_KILLED
));
1247 if (need_seqretry(&rename_lock
, seq
))
1254 spin_unlock(&this_parent
->d_lock
);
1255 done_seqretry(&rename_lock
, seq
);
1259 spin_unlock(&this_parent
->d_lock
);
1269 * Search for at least 1 mount point in the dentry's subdirs.
1270 * We descend to the next level whenever the d_subdirs
1271 * list is non-empty and continue searching.
1274 static enum d_walk_ret
check_mount(void *data
, struct dentry
*dentry
)
1277 if (d_mountpoint(dentry
)) {
1281 return D_WALK_CONTINUE
;
1285 * have_submounts - check for mounts over a dentry
1286 * @parent: dentry to check.
1288 * Return true if the parent or its subdirectories contain
1291 int have_submounts(struct dentry
*parent
)
1295 d_walk(parent
, &ret
, check_mount
, NULL
);
1299 EXPORT_SYMBOL(have_submounts
);
1302 * Called by mount code to set a mountpoint and check if the mountpoint is
1303 * reachable (e.g. NFS can unhash a directory dentry and then the complete
1304 * subtree can become unreachable).
1306 * Only one of d_invalidate() and d_set_mounted() must succeed. For
1307 * this reason take rename_lock and d_lock on dentry and ancestors.
1309 int d_set_mounted(struct dentry
*dentry
)
1313 write_seqlock(&rename_lock
);
1314 for (p
= dentry
->d_parent
; !IS_ROOT(p
); p
= p
->d_parent
) {
1315 /* Need exclusion wrt. d_invalidate() */
1316 spin_lock(&p
->d_lock
);
1317 if (unlikely(d_unhashed(p
))) {
1318 spin_unlock(&p
->d_lock
);
1321 spin_unlock(&p
->d_lock
);
1323 spin_lock(&dentry
->d_lock
);
1324 if (!d_unlinked(dentry
)) {
1326 if (!d_mountpoint(dentry
)) {
1327 dentry
->d_flags
|= DCACHE_MOUNTED
;
1331 spin_unlock(&dentry
->d_lock
);
1333 write_sequnlock(&rename_lock
);
1338 * Search the dentry child list of the specified parent,
1339 * and move any unused dentries to the end of the unused
1340 * list for prune_dcache(). We descend to the next level
1341 * whenever the d_subdirs list is non-empty and continue
1344 * It returns zero iff there are no unused children,
1345 * otherwise it returns the number of children moved to
1346 * the end of the unused list. This may not be the total
1347 * number of unused children, because select_parent can
1348 * drop the lock and return early due to latency
1352 struct select_data
{
1353 struct dentry
*start
;
1354 struct list_head dispose
;
1358 static enum d_walk_ret
select_collect(void *_data
, struct dentry
*dentry
)
1360 struct select_data
*data
= _data
;
1361 enum d_walk_ret ret
= D_WALK_CONTINUE
;
1363 if (data
->start
== dentry
)
1366 if (dentry
->d_flags
& DCACHE_SHRINK_LIST
) {
1369 if (dentry
->d_flags
& DCACHE_LRU_LIST
)
1371 if (!dentry
->d_lockref
.count
) {
1372 d_shrink_add(dentry
, &data
->dispose
);
1377 * We can return to the caller if we have found some (this
1378 * ensures forward progress). We'll be coming back to find
1381 if (!list_empty(&data
->dispose
))
1382 ret
= need_resched() ? D_WALK_QUIT
: D_WALK_NORETRY
;
1388 * shrink_dcache_parent - prune dcache
1389 * @parent: parent of entries to prune
1391 * Prune the dcache to remove unused children of the parent dentry.
1393 void shrink_dcache_parent(struct dentry
*parent
)
1396 struct select_data data
;
1398 INIT_LIST_HEAD(&data
.dispose
);
1399 data
.start
= parent
;
1402 d_walk(parent
, &data
, select_collect
, NULL
);
1406 shrink_dentry_list(&data
.dispose
);
1410 EXPORT_SYMBOL(shrink_dcache_parent
);
1412 static enum d_walk_ret
umount_check(void *_data
, struct dentry
*dentry
)
1414 /* it has busy descendents; complain about those instead */
1415 if (!list_empty(&dentry
->d_subdirs
))
1416 return D_WALK_CONTINUE
;
1418 /* root with refcount 1 is fine */
1419 if (dentry
== _data
&& dentry
->d_lockref
.count
== 1)
1420 return D_WALK_CONTINUE
;
1422 printk(KERN_ERR
"BUG: Dentry %p{i=%lx,n=%pd} "
1423 " still in use (%d) [unmount of %s %s]\n",
1426 dentry
->d_inode
->i_ino
: 0UL,
1428 dentry
->d_lockref
.count
,
1429 dentry
->d_sb
->s_type
->name
,
1430 dentry
->d_sb
->s_id
);
1432 return D_WALK_CONTINUE
;
1435 static void do_one_tree(struct dentry
*dentry
)
1437 shrink_dcache_parent(dentry
);
1438 d_walk(dentry
, dentry
, umount_check
, NULL
);
1444 * destroy the dentries attached to a superblock on unmounting
1446 void shrink_dcache_for_umount(struct super_block
*sb
)
1448 struct dentry
*dentry
;
1450 WARN(down_read_trylock(&sb
->s_umount
), "s_umount should've been locked");
1452 dentry
= sb
->s_root
;
1454 do_one_tree(dentry
);
1456 while (!hlist_bl_empty(&sb
->s_anon
)) {
1457 dentry
= dget(hlist_bl_entry(hlist_bl_first(&sb
->s_anon
), struct dentry
, d_hash
));
1458 do_one_tree(dentry
);
1462 struct detach_data
{
1463 struct select_data select
;
1464 struct dentry
*mountpoint
;
1466 static enum d_walk_ret
detach_and_collect(void *_data
, struct dentry
*dentry
)
1468 struct detach_data
*data
= _data
;
1470 if (d_mountpoint(dentry
)) {
1471 __dget_dlock(dentry
);
1472 data
->mountpoint
= dentry
;
1476 return select_collect(&data
->select
, dentry
);
1479 static void check_and_drop(void *_data
)
1481 struct detach_data
*data
= _data
;
1483 if (!data
->mountpoint
&& !data
->select
.found
)
1484 __d_drop(data
->select
.start
);
1488 * d_invalidate - detach submounts, prune dcache, and drop
1489 * @dentry: dentry to invalidate (aka detach, prune and drop)
1493 * The final d_drop is done as an atomic operation relative to
1494 * rename_lock ensuring there are no races with d_set_mounted. This
1495 * ensures there are no unhashed dentries on the path to a mountpoint.
1497 void d_invalidate(struct dentry
*dentry
)
1500 * If it's already been dropped, return OK.
1502 spin_lock(&dentry
->d_lock
);
1503 if (d_unhashed(dentry
)) {
1504 spin_unlock(&dentry
->d_lock
);
1507 spin_unlock(&dentry
->d_lock
);
1509 /* Negative dentries can be dropped without further checks */
1510 if (!dentry
->d_inode
) {
1516 struct detach_data data
;
1518 data
.mountpoint
= NULL
;
1519 INIT_LIST_HEAD(&data
.select
.dispose
);
1520 data
.select
.start
= dentry
;
1521 data
.select
.found
= 0;
1523 d_walk(dentry
, &data
, detach_and_collect
, check_and_drop
);
1525 if (data
.select
.found
)
1526 shrink_dentry_list(&data
.select
.dispose
);
1528 if (data
.mountpoint
) {
1529 detach_mounts(data
.mountpoint
);
1530 dput(data
.mountpoint
);
1533 if (!data
.mountpoint
&& !data
.select
.found
)
1539 EXPORT_SYMBOL(d_invalidate
);
1542 * __d_alloc - allocate a dcache entry
1543 * @sb: filesystem it will belong to
1544 * @name: qstr of the name
1546 * Allocates a dentry. It returns %NULL if there is insufficient memory
1547 * available. On a success the dentry is returned. The name passed in is
1548 * copied and the copy passed in may be reused after this call.
1551 struct dentry
*__d_alloc(struct super_block
*sb
, const struct qstr
*name
)
1553 struct dentry
*dentry
;
1556 dentry
= kmem_cache_alloc(dentry_cache
, GFP_KERNEL
);
1561 * We guarantee that the inline name is always NUL-terminated.
1562 * This way the memcpy() done by the name switching in rename
1563 * will still always have a NUL at the end, even if we might
1564 * be overwriting an internal NUL character
1566 dentry
->d_iname
[DNAME_INLINE_LEN
-1] = 0;
1567 if (name
->len
> DNAME_INLINE_LEN
-1) {
1568 size_t size
= offsetof(struct external_name
, name
[1]);
1569 struct external_name
*p
= kmalloc(size
+ name
->len
, GFP_KERNEL
);
1571 kmem_cache_free(dentry_cache
, dentry
);
1574 atomic_set(&p
->u
.count
, 1);
1576 if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS
))
1577 kasan_unpoison_shadow(dname
,
1578 round_up(name
->len
+ 1, sizeof(unsigned long)));
1580 dname
= dentry
->d_iname
;
1583 dentry
->d_name
.len
= name
->len
;
1584 dentry
->d_name
.hash
= name
->hash
;
1585 memcpy(dname
, name
->name
, name
->len
);
1586 dname
[name
->len
] = 0;
1588 /* Make sure we always see the terminating NUL character */
1590 dentry
->d_name
.name
= dname
;
1592 dentry
->d_lockref
.count
= 1;
1593 dentry
->d_flags
= 0;
1594 spin_lock_init(&dentry
->d_lock
);
1595 seqcount_init(&dentry
->d_seq
);
1596 dentry
->d_inode
= NULL
;
1597 dentry
->d_parent
= dentry
;
1599 dentry
->d_op
= NULL
;
1600 dentry
->d_fsdata
= NULL
;
1601 INIT_HLIST_BL_NODE(&dentry
->d_hash
);
1602 INIT_LIST_HEAD(&dentry
->d_lru
);
1603 INIT_LIST_HEAD(&dentry
->d_subdirs
);
1604 INIT_HLIST_NODE(&dentry
->d_u
.d_alias
);
1605 INIT_LIST_HEAD(&dentry
->d_child
);
1606 d_set_d_op(dentry
, dentry
->d_sb
->s_d_op
);
1608 this_cpu_inc(nr_dentry
);
1614 * d_alloc - allocate a dcache entry
1615 * @parent: parent of entry to allocate
1616 * @name: qstr of the name
1618 * Allocates a dentry. It returns %NULL if there is insufficient memory
1619 * available. On a success the dentry is returned. The name passed in is
1620 * copied and the copy passed in may be reused after this call.
1622 struct dentry
*d_alloc(struct dentry
* parent
, const struct qstr
*name
)
1624 struct dentry
*dentry
= __d_alloc(parent
->d_sb
, name
);
1627 dentry
->d_flags
|= DCACHE_RCUACCESS
;
1628 spin_lock(&parent
->d_lock
);
1630 * don't need child lock because it is not subject
1631 * to concurrency here
1633 __dget_dlock(parent
);
1634 dentry
->d_parent
= parent
;
1635 list_add(&dentry
->d_child
, &parent
->d_subdirs
);
1636 spin_unlock(&parent
->d_lock
);
1640 EXPORT_SYMBOL(d_alloc
);
1643 * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
1644 * @sb: the superblock
1645 * @name: qstr of the name
1647 * For a filesystem that just pins its dentries in memory and never
1648 * performs lookups at all, return an unhashed IS_ROOT dentry.
1650 struct dentry
*d_alloc_pseudo(struct super_block
*sb
, const struct qstr
*name
)
1652 return __d_alloc(sb
, name
);
1654 EXPORT_SYMBOL(d_alloc_pseudo
);
1656 struct dentry
*d_alloc_name(struct dentry
*parent
, const char *name
)
1661 q
.len
= strlen(name
);
1662 q
.hash
= full_name_hash(q
.name
, q
.len
);
1663 return d_alloc(parent
, &q
);
1665 EXPORT_SYMBOL(d_alloc_name
);
1667 void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
)
1669 WARN_ON_ONCE(dentry
->d_op
);
1670 WARN_ON_ONCE(dentry
->d_flags
& (DCACHE_OP_HASH
|
1672 DCACHE_OP_REVALIDATE
|
1673 DCACHE_OP_WEAK_REVALIDATE
|
1675 DCACHE_OP_SELECT_INODE
));
1680 dentry
->d_flags
|= DCACHE_OP_HASH
;
1682 dentry
->d_flags
|= DCACHE_OP_COMPARE
;
1683 if (op
->d_revalidate
)
1684 dentry
->d_flags
|= DCACHE_OP_REVALIDATE
;
1685 if (op
->d_weak_revalidate
)
1686 dentry
->d_flags
|= DCACHE_OP_WEAK_REVALIDATE
;
1688 dentry
->d_flags
|= DCACHE_OP_DELETE
;
1690 dentry
->d_flags
|= DCACHE_OP_PRUNE
;
1691 if (op
->d_select_inode
)
1692 dentry
->d_flags
|= DCACHE_OP_SELECT_INODE
;
1695 EXPORT_SYMBOL(d_set_d_op
);
1699 * d_set_fallthru - Mark a dentry as falling through to a lower layer
1700 * @dentry - The dentry to mark
1702 * Mark a dentry as falling through to the lower layer (as set with
1703 * d_pin_lower()). This flag may be recorded on the medium.
1705 void d_set_fallthru(struct dentry
*dentry
)
1707 spin_lock(&dentry
->d_lock
);
1708 dentry
->d_flags
|= DCACHE_FALLTHRU
;
1709 spin_unlock(&dentry
->d_lock
);
1711 EXPORT_SYMBOL(d_set_fallthru
);
1713 static unsigned d_flags_for_inode(struct inode
*inode
)
1715 unsigned add_flags
= DCACHE_REGULAR_TYPE
;
1718 return DCACHE_MISS_TYPE
;
1720 if (S_ISDIR(inode
->i_mode
)) {
1721 add_flags
= DCACHE_DIRECTORY_TYPE
;
1722 if (unlikely(!(inode
->i_opflags
& IOP_LOOKUP
))) {
1723 if (unlikely(!inode
->i_op
->lookup
))
1724 add_flags
= DCACHE_AUTODIR_TYPE
;
1726 inode
->i_opflags
|= IOP_LOOKUP
;
1728 goto type_determined
;
1731 if (unlikely(!(inode
->i_opflags
& IOP_NOFOLLOW
))) {
1732 if (unlikely(inode
->i_op
->follow_link
)) {
1733 add_flags
= DCACHE_SYMLINK_TYPE
;
1734 goto type_determined
;
1736 inode
->i_opflags
|= IOP_NOFOLLOW
;
1739 if (unlikely(!S_ISREG(inode
->i_mode
)))
1740 add_flags
= DCACHE_SPECIAL_TYPE
;
1743 if (unlikely(IS_AUTOMOUNT(inode
)))
1744 add_flags
|= DCACHE_NEED_AUTOMOUNT
;
1748 static void __d_instantiate(struct dentry
*dentry
, struct inode
*inode
)
1750 unsigned add_flags
= d_flags_for_inode(inode
);
1752 spin_lock(&dentry
->d_lock
);
1754 hlist_add_head(&dentry
->d_u
.d_alias
, &inode
->i_dentry
);
1755 raw_write_seqcount_begin(&dentry
->d_seq
);
1756 __d_set_inode_and_type(dentry
, inode
, add_flags
);
1757 raw_write_seqcount_end(&dentry
->d_seq
);
1758 spin_unlock(&dentry
->d_lock
);
1759 fsnotify_d_instantiate(dentry
, inode
);
1763 * d_instantiate - fill in inode information for a dentry
1764 * @entry: dentry to complete
1765 * @inode: inode to attach to this dentry
1767 * Fill in inode information in the entry.
1769 * This turns negative dentries into productive full members
1772 * NOTE! This assumes that the inode count has been incremented
1773 * (or otherwise set) by the caller to indicate that it is now
1774 * in use by the dcache.
1777 void d_instantiate(struct dentry
*entry
, struct inode
* inode
)
1779 BUG_ON(!hlist_unhashed(&entry
->d_u
.d_alias
));
1781 spin_lock(&inode
->i_lock
);
1782 __d_instantiate(entry
, inode
);
1784 spin_unlock(&inode
->i_lock
);
1785 security_d_instantiate(entry
, inode
);
1787 EXPORT_SYMBOL(d_instantiate
);
1790 * d_instantiate_unique - instantiate a non-aliased dentry
1791 * @entry: dentry to instantiate
1792 * @inode: inode to attach to this dentry
1794 * Fill in inode information in the entry. On success, it returns NULL.
1795 * If an unhashed alias of "entry" already exists, then we return the
1796 * aliased dentry instead and drop one reference to inode.
1798 * Note that in order to avoid conflicts with rename() etc, the caller
1799 * had better be holding the parent directory semaphore.
1801 * This also assumes that the inode count has been incremented
1802 * (or otherwise set) by the caller to indicate that it is now
1803 * in use by the dcache.
1805 static struct dentry
*__d_instantiate_unique(struct dentry
*entry
,
1806 struct inode
*inode
)
1808 struct dentry
*alias
;
1809 int len
= entry
->d_name
.len
;
1810 const char *name
= entry
->d_name
.name
;
1811 unsigned int hash
= entry
->d_name
.hash
;
1814 __d_instantiate(entry
, NULL
);
1818 hlist_for_each_entry(alias
, &inode
->i_dentry
, d_u
.d_alias
) {
1820 * Don't need alias->d_lock here, because aliases with
1821 * d_parent == entry->d_parent are not subject to name or
1822 * parent changes, because the parent inode i_mutex is held.
1824 if (alias
->d_name
.hash
!= hash
)
1826 if (alias
->d_parent
!= entry
->d_parent
)
1828 if (alias
->d_name
.len
!= len
)
1830 if (dentry_cmp(alias
, name
, len
))
1836 __d_instantiate(entry
, inode
);
1840 struct dentry
*d_instantiate_unique(struct dentry
*entry
, struct inode
*inode
)
1842 struct dentry
*result
;
1844 BUG_ON(!hlist_unhashed(&entry
->d_u
.d_alias
));
1847 spin_lock(&inode
->i_lock
);
1848 result
= __d_instantiate_unique(entry
, inode
);
1850 spin_unlock(&inode
->i_lock
);
1853 security_d_instantiate(entry
, inode
);
1857 BUG_ON(!d_unhashed(result
));
1862 EXPORT_SYMBOL(d_instantiate_unique
);
1865 * d_instantiate_no_diralias - instantiate a non-aliased dentry
1866 * @entry: dentry to complete
1867 * @inode: inode to attach to this dentry
1869 * Fill in inode information in the entry. If a directory alias is found, then
1870 * return an error (and drop inode). Together with d_materialise_unique() this
1871 * guarantees that a directory inode may never have more than one alias.
1873 int d_instantiate_no_diralias(struct dentry
*entry
, struct inode
*inode
)
1875 BUG_ON(!hlist_unhashed(&entry
->d_u
.d_alias
));
1877 spin_lock(&inode
->i_lock
);
1878 if (S_ISDIR(inode
->i_mode
) && !hlist_empty(&inode
->i_dentry
)) {
1879 spin_unlock(&inode
->i_lock
);
1883 __d_instantiate(entry
, inode
);
1884 spin_unlock(&inode
->i_lock
);
1885 security_d_instantiate(entry
, inode
);
1889 EXPORT_SYMBOL(d_instantiate_no_diralias
);
1891 struct dentry
*d_make_root(struct inode
*root_inode
)
1893 struct dentry
*res
= NULL
;
1896 static const struct qstr name
= QSTR_INIT("/", 1);
1898 res
= __d_alloc(root_inode
->i_sb
, &name
);
1900 d_instantiate(res
, root_inode
);
1906 EXPORT_SYMBOL(d_make_root
);
1908 static struct dentry
* __d_find_any_alias(struct inode
*inode
)
1910 struct dentry
*alias
;
1912 if (hlist_empty(&inode
->i_dentry
))
1914 alias
= hlist_entry(inode
->i_dentry
.first
, struct dentry
, d_u
.d_alias
);
1920 * d_find_any_alias - find any alias for a given inode
1921 * @inode: inode to find an alias for
1923 * If any aliases exist for the given inode, take and return a
1924 * reference for one of them. If no aliases exist, return %NULL.
1926 struct dentry
*d_find_any_alias(struct inode
*inode
)
1930 spin_lock(&inode
->i_lock
);
1931 de
= __d_find_any_alias(inode
);
1932 spin_unlock(&inode
->i_lock
);
1935 EXPORT_SYMBOL(d_find_any_alias
);
1937 static struct dentry
*__d_obtain_alias(struct inode
*inode
, int disconnected
)
1939 static const struct qstr anonstring
= QSTR_INIT("/", 1);
1945 return ERR_PTR(-ESTALE
);
1947 return ERR_CAST(inode
);
1949 res
= d_find_any_alias(inode
);
1953 tmp
= __d_alloc(inode
->i_sb
, &anonstring
);
1955 res
= ERR_PTR(-ENOMEM
);
1959 spin_lock(&inode
->i_lock
);
1960 res
= __d_find_any_alias(inode
);
1962 spin_unlock(&inode
->i_lock
);
1967 /* attach a disconnected dentry */
1968 add_flags
= d_flags_for_inode(inode
);
1971 add_flags
|= DCACHE_DISCONNECTED
;
1973 spin_lock(&tmp
->d_lock
);
1974 __d_set_inode_and_type(tmp
, inode
, add_flags
);
1975 hlist_add_head(&tmp
->d_u
.d_alias
, &inode
->i_dentry
);
1976 hlist_bl_lock(&tmp
->d_sb
->s_anon
);
1977 hlist_bl_add_head(&tmp
->d_hash
, &tmp
->d_sb
->s_anon
);
1978 hlist_bl_unlock(&tmp
->d_sb
->s_anon
);
1979 spin_unlock(&tmp
->d_lock
);
1980 spin_unlock(&inode
->i_lock
);
1981 security_d_instantiate(tmp
, inode
);
1986 if (res
&& !IS_ERR(res
))
1987 security_d_instantiate(res
, inode
);
1993 * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
1994 * @inode: inode to allocate the dentry for
1996 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1997 * similar open by handle operations. The returned dentry may be anonymous,
1998 * or may have a full name (if the inode was already in the cache).
2000 * When called on a directory inode, we must ensure that the inode only ever
2001 * has one dentry. If a dentry is found, that is returned instead of
2002 * allocating a new one.
2004 * On successful return, the reference to the inode has been transferred
2005 * to the dentry. In case of an error the reference on the inode is released.
2006 * To make it easier to use in export operations a %NULL or IS_ERR inode may
2007 * be passed in and the error will be propagated to the return value,
2008 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
2010 struct dentry
*d_obtain_alias(struct inode
*inode
)
2012 return __d_obtain_alias(inode
, 1);
2014 EXPORT_SYMBOL(d_obtain_alias
);
2017 * d_obtain_root - find or allocate a dentry for a given inode
2018 * @inode: inode to allocate the dentry for
2020 * Obtain an IS_ROOT dentry for the root of a filesystem.
2022 * We must ensure that directory inodes only ever have one dentry. If a
2023 * dentry is found, that is returned instead of allocating a new one.
2025 * On successful return, the reference to the inode has been transferred
2026 * to the dentry. In case of an error the reference on the inode is
2027 * released. A %NULL or IS_ERR inode may be passed in and will be the
2028 * error will be propagate to the return value, with a %NULL @inode
2029 * replaced by ERR_PTR(-ESTALE).
2031 struct dentry
*d_obtain_root(struct inode
*inode
)
2033 return __d_obtain_alias(inode
, 0);
2035 EXPORT_SYMBOL(d_obtain_root
);
2038 * d_add_ci - lookup or allocate new dentry with case-exact name
2039 * @inode: the inode case-insensitive lookup has found
2040 * @dentry: the negative dentry that was passed to the parent's lookup func
2041 * @name: the case-exact name to be associated with the returned dentry
2043 * This is to avoid filling the dcache with case-insensitive names to the
2044 * same inode, only the actual correct case is stored in the dcache for
2045 * case-insensitive filesystems.
2047 * For a case-insensitive lookup match and if the the case-exact dentry
2048 * already exists in in the dcache, use it and return it.
2050 * If no entry exists with the exact case name, allocate new dentry with
2051 * the exact case, and return the spliced entry.
2053 struct dentry
*d_add_ci(struct dentry
*dentry
, struct inode
*inode
,
2056 struct dentry
*found
;
2060 * First check if a dentry matching the name already exists,
2061 * if not go ahead and create it now.
2063 found
= d_hash_and_lookup(dentry
->d_parent
, name
);
2065 new = d_alloc(dentry
->d_parent
, name
);
2067 found
= ERR_PTR(-ENOMEM
);
2069 found
= d_splice_alias(inode
, new);
2080 EXPORT_SYMBOL(d_add_ci
);
2083 * Do the slow-case of the dentry name compare.
2085 * Unlike the dentry_cmp() function, we need to atomically
2086 * load the name and length information, so that the
2087 * filesystem can rely on them, and can use the 'name' and
2088 * 'len' information without worrying about walking off the
2089 * end of memory etc.
2091 * Thus the read_seqcount_retry() and the "duplicate" info
2092 * in arguments (the low-level filesystem should not look
2093 * at the dentry inode or name contents directly, since
2094 * rename can change them while we're in RCU mode).
2096 enum slow_d_compare
{
2102 static noinline
enum slow_d_compare
slow_dentry_cmp(
2103 const struct dentry
*parent
,
2104 struct dentry
*dentry
,
2106 const struct qstr
*name
)
2108 int tlen
= dentry
->d_name
.len
;
2109 const char *tname
= dentry
->d_name
.name
;
2111 if (read_seqcount_retry(&dentry
->d_seq
, seq
)) {
2113 return D_COMP_SEQRETRY
;
2115 if (parent
->d_op
->d_compare(parent
, dentry
, tlen
, tname
, name
))
2116 return D_COMP_NOMATCH
;
2121 * __d_lookup_rcu - search for a dentry (racy, store-free)
2122 * @parent: parent dentry
2123 * @name: qstr of name we wish to find
2124 * @seqp: returns d_seq value at the point where the dentry was found
2125 * Returns: dentry, or NULL
2127 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
2128 * resolution (store-free path walking) design described in
2129 * Documentation/filesystems/path-lookup.txt.
2131 * This is not to be used outside core vfs.
2133 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
2134 * held, and rcu_read_lock held. The returned dentry must not be stored into
2135 * without taking d_lock and checking d_seq sequence count against @seq
2138 * A refcount may be taken on the found dentry with the d_rcu_to_refcount
2141 * Alternatively, __d_lookup_rcu may be called again to look up the child of
2142 * the returned dentry, so long as its parent's seqlock is checked after the
2143 * child is looked up. Thus, an interlocking stepping of sequence lock checks
2144 * is formed, giving integrity down the path walk.
2146 * NOTE! The caller *has* to check the resulting dentry against the sequence
2147 * number we've returned before using any of the resulting dentry state!
2149 struct dentry
*__d_lookup_rcu(const struct dentry
*parent
,
2150 const struct qstr
*name
,
2153 u64 hashlen
= name
->hash_len
;
2154 const unsigned char *str
= name
->name
;
2155 struct hlist_bl_head
*b
= d_hash(parent
, hashlen_hash(hashlen
));
2156 struct hlist_bl_node
*node
;
2157 struct dentry
*dentry
;
2160 * Note: There is significant duplication with __d_lookup_rcu which is
2161 * required to prevent single threaded performance regressions
2162 * especially on architectures where smp_rmb (in seqcounts) are costly.
2163 * Keep the two functions in sync.
2167 * The hash list is protected using RCU.
2169 * Carefully use d_seq when comparing a candidate dentry, to avoid
2170 * races with d_move().
2172 * It is possible that concurrent renames can mess up our list
2173 * walk here and result in missing our dentry, resulting in the
2174 * false-negative result. d_lookup() protects against concurrent
2175 * renames using rename_lock seqlock.
2177 * See Documentation/filesystems/path-lookup.txt for more details.
2179 hlist_bl_for_each_entry_rcu(dentry
, node
, b
, d_hash
) {
2184 * The dentry sequence count protects us from concurrent
2185 * renames, and thus protects parent and name fields.
2187 * The caller must perform a seqcount check in order
2188 * to do anything useful with the returned dentry.
2190 * NOTE! We do a "raw" seqcount_begin here. That means that
2191 * we don't wait for the sequence count to stabilize if it
2192 * is in the middle of a sequence change. If we do the slow
2193 * dentry compare, we will do seqretries until it is stable,
2194 * and if we end up with a successful lookup, we actually
2195 * want to exit RCU lookup anyway.
2197 seq
= raw_seqcount_begin(&dentry
->d_seq
);
2198 if (dentry
->d_parent
!= parent
)
2200 if (d_unhashed(dentry
))
2203 if (unlikely(parent
->d_flags
& DCACHE_OP_COMPARE
)) {
2204 if (dentry
->d_name
.hash
!= hashlen_hash(hashlen
))
2207 switch (slow_dentry_cmp(parent
, dentry
, seq
, name
)) {
2210 case D_COMP_NOMATCH
:
2217 if (dentry
->d_name
.hash_len
!= hashlen
)
2220 if (!dentry_cmp(dentry
, str
, hashlen_len(hashlen
)))
2227 * d_lookup - search for a dentry
2228 * @parent: parent dentry
2229 * @name: qstr of name we wish to find
2230 * Returns: dentry, or NULL
2232 * d_lookup searches the children of the parent dentry for the name in
2233 * question. If the dentry is found its reference count is incremented and the
2234 * dentry is returned. The caller must use dput to free the entry when it has
2235 * finished using it. %NULL is returned if the dentry does not exist.
2237 struct dentry
*d_lookup(const struct dentry
*parent
, const struct qstr
*name
)
2239 struct dentry
*dentry
;
2243 seq
= read_seqbegin(&rename_lock
);
2244 dentry
= __d_lookup(parent
, name
);
2247 } while (read_seqretry(&rename_lock
, seq
));
2250 EXPORT_SYMBOL(d_lookup
);
2253 * __d_lookup - search for a dentry (racy)
2254 * @parent: parent dentry
2255 * @name: qstr of name we wish to find
2256 * Returns: dentry, or NULL
2258 * __d_lookup is like d_lookup, however it may (rarely) return a
2259 * false-negative result due to unrelated rename activity.
2261 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
2262 * however it must be used carefully, eg. with a following d_lookup in
2263 * the case of failure.
2265 * __d_lookup callers must be commented.
2267 struct dentry
*__d_lookup(const struct dentry
*parent
, const struct qstr
*name
)
2269 unsigned int len
= name
->len
;
2270 unsigned int hash
= name
->hash
;
2271 const unsigned char *str
= name
->name
;
2272 struct hlist_bl_head
*b
= d_hash(parent
, hash
);
2273 struct hlist_bl_node
*node
;
2274 struct dentry
*found
= NULL
;
2275 struct dentry
*dentry
;
2278 * Note: There is significant duplication with __d_lookup_rcu which is
2279 * required to prevent single threaded performance regressions
2280 * especially on architectures where smp_rmb (in seqcounts) are costly.
2281 * Keep the two functions in sync.
2285 * The hash list is protected using RCU.
2287 * Take d_lock when comparing a candidate dentry, to avoid races
2290 * It is possible that concurrent renames can mess up our list
2291 * walk here and result in missing our dentry, resulting in the
2292 * false-negative result. d_lookup() protects against concurrent
2293 * renames using rename_lock seqlock.
2295 * See Documentation/filesystems/path-lookup.txt for more details.
2299 hlist_bl_for_each_entry_rcu(dentry
, node
, b
, d_hash
) {
2301 if (dentry
->d_name
.hash
!= hash
)
2304 spin_lock(&dentry
->d_lock
);
2305 if (dentry
->d_parent
!= parent
)
2307 if (d_unhashed(dentry
))
2311 * It is safe to compare names since d_move() cannot
2312 * change the qstr (protected by d_lock).
2314 if (parent
->d_flags
& DCACHE_OP_COMPARE
) {
2315 int tlen
= dentry
->d_name
.len
;
2316 const char *tname
= dentry
->d_name
.name
;
2317 if (parent
->d_op
->d_compare(parent
, dentry
, tlen
, tname
, name
))
2320 if (dentry
->d_name
.len
!= len
)
2322 if (dentry_cmp(dentry
, str
, len
))
2326 dentry
->d_lockref
.count
++;
2328 spin_unlock(&dentry
->d_lock
);
2331 spin_unlock(&dentry
->d_lock
);
2339 * d_hash_and_lookup - hash the qstr then search for a dentry
2340 * @dir: Directory to search in
2341 * @name: qstr of name we wish to find
2343 * On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
2345 struct dentry
*d_hash_and_lookup(struct dentry
*dir
, struct qstr
*name
)
2348 * Check for a fs-specific hash function. Note that we must
2349 * calculate the standard hash first, as the d_op->d_hash()
2350 * routine may choose to leave the hash value unchanged.
2352 name
->hash
= full_name_hash(name
->name
, name
->len
);
2353 if (dir
->d_flags
& DCACHE_OP_HASH
) {
2354 int err
= dir
->d_op
->d_hash(dir
, name
);
2355 if (unlikely(err
< 0))
2356 return ERR_PTR(err
);
2358 return d_lookup(dir
, name
);
2360 EXPORT_SYMBOL(d_hash_and_lookup
);
2363 * When a file is deleted, we have two options:
2364 * - turn this dentry into a negative dentry
2365 * - unhash this dentry and free it.
2367 * Usually, we want to just turn this into
2368 * a negative dentry, but if anybody else is
2369 * currently using the dentry or the inode
2370 * we can't do that and we fall back on removing
2371 * it from the hash queues and waiting for
2372 * it to be deleted later when it has no users
2376 * d_delete - delete a dentry
2377 * @dentry: The dentry to delete
2379 * Turn the dentry into a negative dentry if possible, otherwise
2380 * remove it from the hash queues so it can be deleted later
2383 void d_delete(struct dentry
* dentry
)
2385 struct inode
*inode
;
2388 * Are we the only user?
2391 spin_lock(&dentry
->d_lock
);
2392 inode
= dentry
->d_inode
;
2393 isdir
= S_ISDIR(inode
->i_mode
);
2394 if (dentry
->d_lockref
.count
== 1) {
2395 if (!spin_trylock(&inode
->i_lock
)) {
2396 spin_unlock(&dentry
->d_lock
);
2400 dentry
->d_flags
&= ~DCACHE_CANT_MOUNT
;
2401 dentry_unlink_inode(dentry
);
2402 fsnotify_nameremove(dentry
, isdir
);
2406 if (!d_unhashed(dentry
))
2409 spin_unlock(&dentry
->d_lock
);
2411 fsnotify_nameremove(dentry
, isdir
);
2413 EXPORT_SYMBOL(d_delete
);
2415 static void __d_rehash(struct dentry
* entry
, struct hlist_bl_head
*b
)
2417 BUG_ON(!d_unhashed(entry
));
2419 hlist_bl_add_head_rcu(&entry
->d_hash
, b
);
2423 static void _d_rehash(struct dentry
* entry
)
2425 __d_rehash(entry
, d_hash(entry
->d_parent
, entry
->d_name
.hash
));
2429 * d_rehash - add an entry back to the hash
2430 * @entry: dentry to add to the hash
2432 * Adds a dentry to the hash according to its name.
2435 void d_rehash(struct dentry
* entry
)
2437 spin_lock(&entry
->d_lock
);
2439 spin_unlock(&entry
->d_lock
);
2441 EXPORT_SYMBOL(d_rehash
);
2444 * dentry_update_name_case - update case insensitive dentry with a new name
2445 * @dentry: dentry to be updated
2448 * Update a case insensitive dentry with new case of name.
2450 * dentry must have been returned by d_lookup with name @name. Old and new
2451 * name lengths must match (ie. no d_compare which allows mismatched name
2454 * Parent inode i_mutex must be held over d_lookup and into this call (to
2455 * keep renames and concurrent inserts, and readdir(2) away).
2457 void dentry_update_name_case(struct dentry
*dentry
, struct qstr
*name
)
2459 BUG_ON(!mutex_is_locked(&dentry
->d_parent
->d_inode
->i_mutex
));
2460 BUG_ON(dentry
->d_name
.len
!= name
->len
); /* d_lookup gives this */
2462 spin_lock(&dentry
->d_lock
);
2463 write_seqcount_begin(&dentry
->d_seq
);
2464 memcpy((unsigned char *)dentry
->d_name
.name
, name
->name
, name
->len
);
2465 write_seqcount_end(&dentry
->d_seq
);
2466 spin_unlock(&dentry
->d_lock
);
2468 EXPORT_SYMBOL(dentry_update_name_case
);
2470 static void swap_names(struct dentry
*dentry
, struct dentry
*target
)
2472 if (unlikely(dname_external(target
))) {
2473 if (unlikely(dname_external(dentry
))) {
2475 * Both external: swap the pointers
2477 swap(target
->d_name
.name
, dentry
->d_name
.name
);
2480 * dentry:internal, target:external. Steal target's
2481 * storage and make target internal.
2483 memcpy(target
->d_iname
, dentry
->d_name
.name
,
2484 dentry
->d_name
.len
+ 1);
2485 dentry
->d_name
.name
= target
->d_name
.name
;
2486 target
->d_name
.name
= target
->d_iname
;
2489 if (unlikely(dname_external(dentry
))) {
2491 * dentry:external, target:internal. Give dentry's
2492 * storage to target and make dentry internal
2494 memcpy(dentry
->d_iname
, target
->d_name
.name
,
2495 target
->d_name
.len
+ 1);
2496 target
->d_name
.name
= dentry
->d_name
.name
;
2497 dentry
->d_name
.name
= dentry
->d_iname
;
2500 * Both are internal.
2503 BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN
, sizeof(long)));
2504 kmemcheck_mark_initialized(dentry
->d_iname
, DNAME_INLINE_LEN
);
2505 kmemcheck_mark_initialized(target
->d_iname
, DNAME_INLINE_LEN
);
2506 for (i
= 0; i
< DNAME_INLINE_LEN
/ sizeof(long); i
++) {
2507 swap(((long *) &dentry
->d_iname
)[i
],
2508 ((long *) &target
->d_iname
)[i
]);
2512 swap(dentry
->d_name
.hash_len
, target
->d_name
.hash_len
);
2515 static void copy_name(struct dentry
*dentry
, struct dentry
*target
)
2517 struct external_name
*old_name
= NULL
;
2518 if (unlikely(dname_external(dentry
)))
2519 old_name
= external_name(dentry
);
2520 if (unlikely(dname_external(target
))) {
2521 atomic_inc(&external_name(target
)->u
.count
);
2522 dentry
->d_name
= target
->d_name
;
2524 memcpy(dentry
->d_iname
, target
->d_name
.name
,
2525 target
->d_name
.len
+ 1);
2526 dentry
->d_name
.name
= dentry
->d_iname
;
2527 dentry
->d_name
.hash_len
= target
->d_name
.hash_len
;
2529 if (old_name
&& likely(atomic_dec_and_test(&old_name
->u
.count
)))
2530 kfree_rcu(old_name
, u
.head
);
2533 static void dentry_lock_for_move(struct dentry
*dentry
, struct dentry
*target
)
2536 * XXXX: do we really need to take target->d_lock?
2538 if (IS_ROOT(dentry
) || dentry
->d_parent
== target
->d_parent
)
2539 spin_lock(&target
->d_parent
->d_lock
);
2541 if (d_ancestor(dentry
->d_parent
, target
->d_parent
)) {
2542 spin_lock(&dentry
->d_parent
->d_lock
);
2543 spin_lock_nested(&target
->d_parent
->d_lock
,
2544 DENTRY_D_LOCK_NESTED
);
2546 spin_lock(&target
->d_parent
->d_lock
);
2547 spin_lock_nested(&dentry
->d_parent
->d_lock
,
2548 DENTRY_D_LOCK_NESTED
);
2551 if (target
< dentry
) {
2552 spin_lock_nested(&target
->d_lock
, 2);
2553 spin_lock_nested(&dentry
->d_lock
, 3);
2555 spin_lock_nested(&dentry
->d_lock
, 2);
2556 spin_lock_nested(&target
->d_lock
, 3);
2560 static void dentry_unlock_for_move(struct dentry
*dentry
, struct dentry
*target
)
2562 if (target
->d_parent
!= dentry
->d_parent
)
2563 spin_unlock(&dentry
->d_parent
->d_lock
);
2564 if (target
->d_parent
!= target
)
2565 spin_unlock(&target
->d_parent
->d_lock
);
2566 spin_unlock(&target
->d_lock
);
2567 spin_unlock(&dentry
->d_lock
);
2571 * When switching names, the actual string doesn't strictly have to
2572 * be preserved in the target - because we're dropping the target
2573 * anyway. As such, we can just do a simple memcpy() to copy over
2574 * the new name before we switch, unless we are going to rehash
2575 * it. Note that if we *do* unhash the target, we are not allowed
2576 * to rehash it without giving it a new name/hash key - whether
2577 * we swap or overwrite the names here, resulting name won't match
2578 * the reality in filesystem; it's only there for d_path() purposes.
2579 * Note that all of this is happening under rename_lock, so the
2580 * any hash lookup seeing it in the middle of manipulations will
2581 * be discarded anyway. So we do not care what happens to the hash
2585 * __d_move - move a dentry
2586 * @dentry: entry to move
2587 * @target: new dentry
2588 * @exchange: exchange the two dentries
2590 * Update the dcache to reflect the move of a file name. Negative
2591 * dcache entries should not be moved in this way. Caller must hold
2592 * rename_lock, the i_mutex of the source and target directories,
2593 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
2595 static void __d_move(struct dentry
*dentry
, struct dentry
*target
,
2598 if (!dentry
->d_inode
)
2599 printk(KERN_WARNING
"VFS: moving negative dcache entry\n");
2601 BUG_ON(d_ancestor(dentry
, target
));
2602 BUG_ON(d_ancestor(target
, dentry
));
2604 dentry_lock_for_move(dentry
, target
);
2606 write_seqcount_begin(&dentry
->d_seq
);
2607 write_seqcount_begin_nested(&target
->d_seq
, DENTRY_D_LOCK_NESTED
);
2609 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2612 * Move the dentry to the target hash queue. Don't bother checking
2613 * for the same hash queue because of how unlikely it is.
2616 __d_rehash(dentry
, d_hash(target
->d_parent
, target
->d_name
.hash
));
2619 * Unhash the target (d_delete() is not usable here). If exchanging
2620 * the two dentries, then rehash onto the other's hash queue.
2625 d_hash(dentry
->d_parent
, dentry
->d_name
.hash
));
2628 /* Switch the names.. */
2630 swap_names(dentry
, target
);
2632 copy_name(dentry
, target
);
2634 /* ... and switch them in the tree */
2635 if (IS_ROOT(dentry
)) {
2636 /* splicing a tree */
2637 dentry
->d_flags
|= DCACHE_RCUACCESS
;
2638 dentry
->d_parent
= target
->d_parent
;
2639 target
->d_parent
= target
;
2640 list_del_init(&target
->d_child
);
2641 list_move(&dentry
->d_child
, &dentry
->d_parent
->d_subdirs
);
2643 /* swapping two dentries */
2644 swap(dentry
->d_parent
, target
->d_parent
);
2645 list_move(&target
->d_child
, &target
->d_parent
->d_subdirs
);
2646 list_move(&dentry
->d_child
, &dentry
->d_parent
->d_subdirs
);
2648 fsnotify_d_move(target
);
2649 fsnotify_d_move(dentry
);
2652 write_seqcount_end(&target
->d_seq
);
2653 write_seqcount_end(&dentry
->d_seq
);
2655 dentry_unlock_for_move(dentry
, target
);
2659 * d_move - move a dentry
2660 * @dentry: entry to move
2661 * @target: new dentry
2663 * Update the dcache to reflect the move of a file name. Negative
2664 * dcache entries should not be moved in this way. See the locking
2665 * requirements for __d_move.
2667 void d_move(struct dentry
*dentry
, struct dentry
*target
)
2669 write_seqlock(&rename_lock
);
2670 __d_move(dentry
, target
, false);
2671 write_sequnlock(&rename_lock
);
2673 EXPORT_SYMBOL(d_move
);
2676 * d_exchange - exchange two dentries
2677 * @dentry1: first dentry
2678 * @dentry2: second dentry
2680 void d_exchange(struct dentry
*dentry1
, struct dentry
*dentry2
)
2682 write_seqlock(&rename_lock
);
2684 WARN_ON(!dentry1
->d_inode
);
2685 WARN_ON(!dentry2
->d_inode
);
2686 WARN_ON(IS_ROOT(dentry1
));
2687 WARN_ON(IS_ROOT(dentry2
));
2689 __d_move(dentry1
, dentry2
, true);
2691 write_sequnlock(&rename_lock
);
2695 * d_ancestor - search for an ancestor
2696 * @p1: ancestor dentry
2699 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2700 * an ancestor of p2, else NULL.
2702 struct dentry
*d_ancestor(struct dentry
*p1
, struct dentry
*p2
)
2706 for (p
= p2
; !IS_ROOT(p
); p
= p
->d_parent
) {
2707 if (p
->d_parent
== p1
)
2714 * This helper attempts to cope with remotely renamed directories
2716 * It assumes that the caller is already holding
2717 * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock
2719 * Note: If ever the locking in lock_rename() changes, then please
2720 * remember to update this too...
2722 static int __d_unalias(struct inode
*inode
,
2723 struct dentry
*dentry
, struct dentry
*alias
)
2725 struct mutex
*m1
= NULL
, *m2
= NULL
;
2728 /* If alias and dentry share a parent, then no extra locks required */
2729 if (alias
->d_parent
== dentry
->d_parent
)
2732 /* See lock_rename() */
2733 if (!mutex_trylock(&dentry
->d_sb
->s_vfs_rename_mutex
))
2735 m1
= &dentry
->d_sb
->s_vfs_rename_mutex
;
2736 if (!mutex_trylock(&alias
->d_parent
->d_inode
->i_mutex
))
2738 m2
= &alias
->d_parent
->d_inode
->i_mutex
;
2740 __d_move(alias
, dentry
, false);
2743 spin_unlock(&inode
->i_lock
);
2752 * d_splice_alias - splice a disconnected dentry into the tree if one exists
2753 * @inode: the inode which may have a disconnected dentry
2754 * @dentry: a negative dentry which we want to point to the inode.
2756 * If inode is a directory and has an IS_ROOT alias, then d_move that in
2757 * place of the given dentry and return it, else simply d_add the inode
2758 * to the dentry and return NULL.
2760 * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
2761 * we should error out: directories can't have multiple aliases.
2763 * This is needed in the lookup routine of any filesystem that is exportable
2764 * (via knfsd) so that we can build dcache paths to directories effectively.
2766 * If a dentry was found and moved, then it is returned. Otherwise NULL
2767 * is returned. This matches the expected return value of ->lookup.
2769 * Cluster filesystems may call this function with a negative, hashed dentry.
2770 * In that case, we know that the inode will be a regular file, and also this
2771 * will only occur during atomic_open. So we need to check for the dentry
2772 * being already hashed only in the final case.
2774 struct dentry
*d_splice_alias(struct inode
*inode
, struct dentry
*dentry
)
2777 return ERR_CAST(inode
);
2779 BUG_ON(!d_unhashed(dentry
));
2782 __d_instantiate(dentry
, NULL
);
2785 spin_lock(&inode
->i_lock
);
2786 if (S_ISDIR(inode
->i_mode
)) {
2787 struct dentry
*new = __d_find_any_alias(inode
);
2788 if (unlikely(new)) {
2789 write_seqlock(&rename_lock
);
2790 if (unlikely(d_ancestor(new, dentry
))) {
2791 write_sequnlock(&rename_lock
);
2792 spin_unlock(&inode
->i_lock
);
2794 new = ERR_PTR(-ELOOP
);
2795 pr_warn_ratelimited(
2796 "VFS: Lookup of '%s' in %s %s"
2797 " would have caused loop\n",
2798 dentry
->d_name
.name
,
2799 inode
->i_sb
->s_type
->name
,
2801 } else if (!IS_ROOT(new)) {
2802 int err
= __d_unalias(inode
, dentry
, new);
2803 write_sequnlock(&rename_lock
);
2809 __d_move(new, dentry
, false);
2810 write_sequnlock(&rename_lock
);
2811 spin_unlock(&inode
->i_lock
);
2812 security_d_instantiate(new, inode
);
2818 /* already taking inode->i_lock, so d_add() by hand */
2819 __d_instantiate(dentry
, inode
);
2820 spin_unlock(&inode
->i_lock
);
2822 security_d_instantiate(dentry
, inode
);
2826 EXPORT_SYMBOL(d_splice_alias
);
2828 static int prepend(char **buffer
, int *buflen
, const char *str
, int namelen
)
2832 return -ENAMETOOLONG
;
2834 memcpy(*buffer
, str
, namelen
);
2839 * prepend_name - prepend a pathname in front of current buffer pointer
2840 * @buffer: buffer pointer
2841 * @buflen: allocated length of the buffer
2842 * @name: name string and length qstr structure
2844 * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to
2845 * make sure that either the old or the new name pointer and length are
2846 * fetched. However, there may be mismatch between length and pointer.
2847 * The length cannot be trusted, we need to copy it byte-by-byte until
2848 * the length is reached or a null byte is found. It also prepends "/" at
2849 * the beginning of the name. The sequence number check at the caller will
2850 * retry it again when a d_move() does happen. So any garbage in the buffer
2851 * due to mismatched pointer and length will be discarded.
2853 * Data dependency barrier is needed to make sure that we see that terminating
2854 * NUL. Alpha strikes again, film at 11...
2856 static int prepend_name(char **buffer
, int *buflen
, struct qstr
*name
)
2858 const char *dname
= ACCESS_ONCE(name
->name
);
2859 u32 dlen
= ACCESS_ONCE(name
->len
);
2862 smp_read_barrier_depends();
2864 *buflen
-= dlen
+ 1;
2866 return -ENAMETOOLONG
;
2867 p
= *buffer
-= dlen
+ 1;
2879 * prepend_path - Prepend path string to a buffer
2880 * @path: the dentry/vfsmount to report
2881 * @root: root vfsmnt/dentry
2882 * @buffer: pointer to the end of the buffer
2883 * @buflen: pointer to buffer length
2885 * The function will first try to write out the pathname without taking any
2886 * lock other than the RCU read lock to make sure that dentries won't go away.
2887 * It only checks the sequence number of the global rename_lock as any change
2888 * in the dentry's d_seq will be preceded by changes in the rename_lock
2889 * sequence number. If the sequence number had been changed, it will restart
2890 * the whole pathname back-tracing sequence again by taking the rename_lock.
2891 * In this case, there is no need to take the RCU read lock as the recursive
2892 * parent pointer references will keep the dentry chain alive as long as no
2893 * rename operation is performed.
2895 static int prepend_path(const struct path
*path
,
2896 const struct path
*root
,
2897 char **buffer
, int *buflen
)
2899 struct dentry
*dentry
;
2900 struct vfsmount
*vfsmnt
;
2903 unsigned seq
, m_seq
= 0;
2909 read_seqbegin_or_lock(&mount_lock
, &m_seq
);
2916 dentry
= path
->dentry
;
2918 mnt
= real_mount(vfsmnt
);
2919 read_seqbegin_or_lock(&rename_lock
, &seq
);
2920 while (dentry
!= root
->dentry
|| vfsmnt
!= root
->mnt
) {
2921 struct dentry
* parent
;
2923 if (dentry
== vfsmnt
->mnt_root
|| IS_ROOT(dentry
)) {
2924 struct mount
*parent
= ACCESS_ONCE(mnt
->mnt_parent
);
2926 if (dentry
!= vfsmnt
->mnt_root
) {
2933 if (mnt
!= parent
) {
2934 dentry
= ACCESS_ONCE(mnt
->mnt_mountpoint
);
2940 error
= is_mounted(vfsmnt
) ? 1 : 2;
2943 parent
= dentry
->d_parent
;
2945 error
= prepend_name(&bptr
, &blen
, &dentry
->d_name
);
2953 if (need_seqretry(&rename_lock
, seq
)) {
2957 done_seqretry(&rename_lock
, seq
);
2961 if (need_seqretry(&mount_lock
, m_seq
)) {
2965 done_seqretry(&mount_lock
, m_seq
);
2967 if (error
>= 0 && bptr
== *buffer
) {
2969 error
= -ENAMETOOLONG
;
2979 * __d_path - return the path of a dentry
2980 * @path: the dentry/vfsmount to report
2981 * @root: root vfsmnt/dentry
2982 * @buf: buffer to return value in
2983 * @buflen: buffer length
2985 * Convert a dentry into an ASCII path name.
2987 * Returns a pointer into the buffer or an error code if the
2988 * path was too long.
2990 * "buflen" should be positive.
2992 * If the path is not reachable from the supplied root, return %NULL.
2994 char *__d_path(const struct path
*path
,
2995 const struct path
*root
,
2996 char *buf
, int buflen
)
2998 char *res
= buf
+ buflen
;
3001 prepend(&res
, &buflen
, "\0", 1);
3002 error
= prepend_path(path
, root
, &res
, &buflen
);
3005 return ERR_PTR(error
);
3011 char *d_absolute_path(const struct path
*path
,
3012 char *buf
, int buflen
)
3014 struct path root
= {};
3015 char *res
= buf
+ buflen
;
3018 prepend(&res
, &buflen
, "\0", 1);
3019 error
= prepend_path(path
, &root
, &res
, &buflen
);
3024 return ERR_PTR(error
);
3029 * same as __d_path but appends "(deleted)" for unlinked files.
3031 static int path_with_deleted(const struct path
*path
,
3032 const struct path
*root
,
3033 char **buf
, int *buflen
)
3035 prepend(buf
, buflen
, "\0", 1);
3036 if (d_unlinked(path
->dentry
)) {
3037 int error
= prepend(buf
, buflen
, " (deleted)", 10);
3042 return prepend_path(path
, root
, buf
, buflen
);
3045 static int prepend_unreachable(char **buffer
, int *buflen
)
3047 return prepend(buffer
, buflen
, "(unreachable)", 13);
3050 static void get_fs_root_rcu(struct fs_struct
*fs
, struct path
*root
)
3055 seq
= read_seqcount_begin(&fs
->seq
);
3057 } while (read_seqcount_retry(&fs
->seq
, seq
));
3061 * d_path - return the path of a dentry
3062 * @path: path to report
3063 * @buf: buffer to return value in
3064 * @buflen: buffer length
3066 * Convert a dentry into an ASCII path name. If the entry has been deleted
3067 * the string " (deleted)" is appended. Note that this is ambiguous.
3069 * Returns a pointer into the buffer or an error code if the path was
3070 * too long. Note: Callers should use the returned pointer, not the passed
3071 * in buffer, to use the name! The implementation often starts at an offset
3072 * into the buffer, and may leave 0 bytes at the start.
3074 * "buflen" should be positive.
3076 char *d_path(const struct path
*path
, char *buf
, int buflen
)
3078 char *res
= buf
+ buflen
;
3083 * We have various synthetic filesystems that never get mounted. On
3084 * these filesystems dentries are never used for lookup purposes, and
3085 * thus don't need to be hashed. They also don't need a name until a
3086 * user wants to identify the object in /proc/pid/fd/. The little hack
3087 * below allows us to generate a name for these objects on demand:
3089 * Some pseudo inodes are mountable. When they are mounted
3090 * path->dentry == path->mnt->mnt_root. In that case don't call d_dname
3091 * and instead have d_path return the mounted path.
3093 if (path
->dentry
->d_op
&& path
->dentry
->d_op
->d_dname
&&
3094 (!IS_ROOT(path
->dentry
) || path
->dentry
!= path
->mnt
->mnt_root
))
3095 return path
->dentry
->d_op
->d_dname(path
->dentry
, buf
, buflen
);
3098 get_fs_root_rcu(current
->fs
, &root
);
3099 error
= path_with_deleted(path
, &root
, &res
, &buflen
);
3103 res
= ERR_PTR(error
);
3106 EXPORT_SYMBOL(d_path
);
3109 * Helper function for dentry_operations.d_dname() members
3111 char *dynamic_dname(struct dentry
*dentry
, char *buffer
, int buflen
,
3112 const char *fmt
, ...)
3118 va_start(args
, fmt
);
3119 sz
= vsnprintf(temp
, sizeof(temp
), fmt
, args
) + 1;
3122 if (sz
> sizeof(temp
) || sz
> buflen
)
3123 return ERR_PTR(-ENAMETOOLONG
);
3125 buffer
+= buflen
- sz
;
3126 return memcpy(buffer
, temp
, sz
);
3129 char *simple_dname(struct dentry
*dentry
, char *buffer
, int buflen
)
3131 char *end
= buffer
+ buflen
;
3132 /* these dentries are never renamed, so d_lock is not needed */
3133 if (prepend(&end
, &buflen
, " (deleted)", 11) ||
3134 prepend(&end
, &buflen
, dentry
->d_name
.name
, dentry
->d_name
.len
) ||
3135 prepend(&end
, &buflen
, "/", 1))
3136 end
= ERR_PTR(-ENAMETOOLONG
);
3139 EXPORT_SYMBOL(simple_dname
);
3142 * Write full pathname from the root of the filesystem into the buffer.
3144 static char *__dentry_path(struct dentry
*d
, char *buf
, int buflen
)
3146 struct dentry
*dentry
;
3159 prepend(&end
, &len
, "\0", 1);
3163 read_seqbegin_or_lock(&rename_lock
, &seq
);
3164 while (!IS_ROOT(dentry
)) {
3165 struct dentry
*parent
= dentry
->d_parent
;
3168 error
= prepend_name(&end
, &len
, &dentry
->d_name
);
3177 if (need_seqretry(&rename_lock
, seq
)) {
3181 done_seqretry(&rename_lock
, seq
);
3186 return ERR_PTR(-ENAMETOOLONG
);
3189 char *dentry_path_raw(struct dentry
*dentry
, char *buf
, int buflen
)
3191 return __dentry_path(dentry
, buf
, buflen
);
3193 EXPORT_SYMBOL(dentry_path_raw
);
3195 char *dentry_path(struct dentry
*dentry
, char *buf
, int buflen
)
3200 if (d_unlinked(dentry
)) {
3202 if (prepend(&p
, &buflen
, "//deleted", 10) != 0)
3206 retval
= __dentry_path(dentry
, buf
, buflen
);
3207 if (!IS_ERR(retval
) && p
)
3208 *p
= '/'; /* restore '/' overriden with '\0' */
3211 return ERR_PTR(-ENAMETOOLONG
);
3214 static void get_fs_root_and_pwd_rcu(struct fs_struct
*fs
, struct path
*root
,
3220 seq
= read_seqcount_begin(&fs
->seq
);
3223 } while (read_seqcount_retry(&fs
->seq
, seq
));
3227 * NOTE! The user-level library version returns a
3228 * character pointer. The kernel system call just
3229 * returns the length of the buffer filled (which
3230 * includes the ending '\0' character), or a negative
3231 * error value. So libc would do something like
3233 * char *getcwd(char * buf, size_t size)
3237 * retval = sys_getcwd(buf, size);
3244 SYSCALL_DEFINE2(getcwd
, char __user
*, buf
, unsigned long, size
)
3247 struct path pwd
, root
;
3248 char *page
= __getname();
3254 get_fs_root_and_pwd_rcu(current
->fs
, &root
, &pwd
);
3257 if (!d_unlinked(pwd
.dentry
)) {
3259 char *cwd
= page
+ PATH_MAX
;
3260 int buflen
= PATH_MAX
;
3262 prepend(&cwd
, &buflen
, "\0", 1);
3263 error
= prepend_path(&pwd
, &root
, &cwd
, &buflen
);
3269 /* Unreachable from current root */
3271 error
= prepend_unreachable(&cwd
, &buflen
);
3277 len
= PATH_MAX
+ page
- cwd
;
3280 if (copy_to_user(buf
, cwd
, len
))
3293 * Test whether new_dentry is a subdirectory of old_dentry.
3295 * Trivially implemented using the dcache structure
3299 * is_subdir - is new dentry a subdirectory of old_dentry
3300 * @new_dentry: new dentry
3301 * @old_dentry: old dentry
3303 * Returns 1 if new_dentry is a subdirectory of the parent (at any depth).
3304 * Returns 0 otherwise.
3305 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
3308 int is_subdir(struct dentry
*new_dentry
, struct dentry
*old_dentry
)
3313 if (new_dentry
== old_dentry
)
3317 /* for restarting inner loop in case of seq retry */
3318 seq
= read_seqbegin(&rename_lock
);
3320 * Need rcu_readlock to protect against the d_parent trashing
3324 if (d_ancestor(old_dentry
, new_dentry
))
3329 } while (read_seqretry(&rename_lock
, seq
));
3334 static enum d_walk_ret
d_genocide_kill(void *data
, struct dentry
*dentry
)
3336 struct dentry
*root
= data
;
3337 if (dentry
!= root
) {
3338 if (d_unhashed(dentry
) || !dentry
->d_inode
)
3341 if (!(dentry
->d_flags
& DCACHE_GENOCIDE
)) {
3342 dentry
->d_flags
|= DCACHE_GENOCIDE
;
3343 dentry
->d_lockref
.count
--;
3346 return D_WALK_CONTINUE
;
3349 void d_genocide(struct dentry
*parent
)
3351 d_walk(parent
, parent
, d_genocide_kill
, NULL
);
3354 void d_tmpfile(struct dentry
*dentry
, struct inode
*inode
)
3356 inode_dec_link_count(inode
);
3357 BUG_ON(dentry
->d_name
.name
!= dentry
->d_iname
||
3358 !hlist_unhashed(&dentry
->d_u
.d_alias
) ||
3359 !d_unlinked(dentry
));
3360 spin_lock(&dentry
->d_parent
->d_lock
);
3361 spin_lock_nested(&dentry
->d_lock
, DENTRY_D_LOCK_NESTED
);
3362 dentry
->d_name
.len
= sprintf(dentry
->d_iname
, "#%llu",
3363 (unsigned long long)inode
->i_ino
);
3364 spin_unlock(&dentry
->d_lock
);
3365 spin_unlock(&dentry
->d_parent
->d_lock
);
3366 d_instantiate(dentry
, inode
);
3368 EXPORT_SYMBOL(d_tmpfile
);
3370 static __initdata
unsigned long dhash_entries
;
3371 static int __init
set_dhash_entries(char *str
)
3375 dhash_entries
= simple_strtoul(str
, &str
, 0);
3378 __setup("dhash_entries=", set_dhash_entries
);
3380 static void __init
dcache_init_early(void)
3384 /* If hashes are distributed across NUMA nodes, defer
3385 * hash allocation until vmalloc space is available.
3391 alloc_large_system_hash("Dentry cache",
3392 sizeof(struct hlist_bl_head
),
3401 for (loop
= 0; loop
< (1U << d_hash_shift
); loop
++)
3402 INIT_HLIST_BL_HEAD(dentry_hashtable
+ loop
);
3405 static void __init
dcache_init(void)
3410 * A constructor could be added for stable state like the lists,
3411 * but it is probably not worth it because of the cache nature
3414 dentry_cache
= KMEM_CACHE(dentry
,
3415 SLAB_RECLAIM_ACCOUNT
|SLAB_PANIC
|SLAB_MEM_SPREAD
);
3417 /* Hash may have been set up in dcache_init_early */
3422 alloc_large_system_hash("Dentry cache",
3423 sizeof(struct hlist_bl_head
),
3432 for (loop
= 0; loop
< (1U << d_hash_shift
); loop
++)
3433 INIT_HLIST_BL_HEAD(dentry_hashtable
+ loop
);
3436 /* SLAB cache for __getname() consumers */
3437 struct kmem_cache
*names_cachep __read_mostly
;
3438 EXPORT_SYMBOL(names_cachep
);
3440 EXPORT_SYMBOL(d_genocide
);
3442 void __init
vfs_caches_init_early(void)
3444 dcache_init_early();
3448 void __init
vfs_caches_init(unsigned long mempages
)
3450 unsigned long reserve
;
3452 /* Base hash sizes on available memory, with a reserve equal to
3453 150% of current kernel size */
3455 reserve
= min((mempages
- nr_free_pages()) * 3/2, mempages
- 1);
3456 mempages
-= reserve
;
3458 names_cachep
= kmem_cache_create("names_cache", PATH_MAX
, 0,
3459 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
3463 files_init(mempages
);