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 #define IN_LOOKUP_SHIFT 10
115 static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT];
117 static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent,
120 hash += (unsigned long) parent / L1_CACHE_BYTES;
121 return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT);
125 /* Statistics gathering. */
126 struct dentry_stat_t dentry_stat = {
130 static DEFINE_PER_CPU(long, nr_dentry);
131 static DEFINE_PER_CPU(long, nr_dentry_unused);
133 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
136 * Here we resort to our own counters instead of using generic per-cpu counters
137 * for consistency with what the vfs inode code does. We are expected to harvest
138 * better code and performance by having our own specialized counters.
140 * Please note that the loop is done over all possible CPUs, not over all online
141 * CPUs. The reason for this is that we don't want to play games with CPUs going
142 * on and off. If one of them goes off, we will just keep their counters.
144 * glommer: See cffbc8a for details, and if you ever intend to change this,
145 * please update all vfs counters to match.
147 static long get_nr_dentry(void)
151 for_each_possible_cpu(i)
152 sum += per_cpu(nr_dentry, i);
153 return sum < 0 ? 0 : sum;
156 static long get_nr_dentry_unused(void)
160 for_each_possible_cpu(i)
161 sum += per_cpu(nr_dentry_unused, i);
162 return sum < 0 ? 0 : sum;
165 int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer,
166 size_t *lenp, loff_t *ppos)
168 dentry_stat.nr_dentry = get_nr_dentry();
169 dentry_stat.nr_unused = get_nr_dentry_unused();
170 return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
175 * Compare 2 name strings, return 0 if they match, otherwise non-zero.
176 * The strings are both count bytes long, and count is non-zero.
178 #ifdef CONFIG_DCACHE_WORD_ACCESS
180 #include <asm/word-at-a-time.h>
182 * NOTE! 'cs' and 'scount' come from a dentry, so it has a
183 * aligned allocation for this particular component. We don't
184 * strictly need the load_unaligned_zeropad() safety, but it
185 * doesn't hurt either.
187 * In contrast, 'ct' and 'tcount' can be from a pathname, and do
188 * need the careful unaligned handling.
190 static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
192 unsigned long a,b,mask;
195 a = *(unsigned long *)cs;
196 b = load_unaligned_zeropad(ct);
197 if (tcount < sizeof(unsigned long))
199 if (unlikely(a != b))
201 cs += sizeof(unsigned long);
202 ct += sizeof(unsigned long);
203 tcount -= sizeof(unsigned long);
207 mask = bytemask_from_count(tcount);
208 return unlikely(!!((a ^ b) & mask));
213 static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount)
227 static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount)
230 * Be careful about RCU walk racing with rename:
231 * use 'lockless_dereference' to fetch the name pointer.
233 * NOTE! Even if a rename will mean that the length
234 * was not loaded atomically, we don't care. The
235 * RCU walk will check the sequence count eventually,
236 * and catch it. And we won't overrun the buffer,
237 * because we're reading the name pointer atomically,
238 * and a dentry name is guaranteed to be properly
239 * terminated with a NUL byte.
241 * End result: even if 'len' is wrong, we'll exit
242 * early because the data cannot match (there can
243 * be no NUL in the ct/tcount data)
245 const unsigned char *cs = lockless_dereference(dentry->d_name.name);
247 return dentry_string_cmp(cs, ct, tcount);
250 struct external_name {
253 struct rcu_head head;
255 unsigned char name[];
258 static inline struct external_name *external_name(struct dentry *dentry)
260 return container_of(dentry->d_name.name, struct external_name, name[0]);
263 static void __d_free(struct rcu_head *head)
265 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
267 kmem_cache_free(dentry_cache, dentry);
270 static void __d_free_external(struct rcu_head *head)
272 struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
273 kfree(external_name(dentry));
274 kmem_cache_free(dentry_cache, dentry);
277 static inline int dname_external(const struct dentry *dentry)
279 return dentry->d_name.name != dentry->d_iname;
282 static inline void __d_set_inode_and_type(struct dentry *dentry,
288 dentry->d_inode = inode;
289 flags = READ_ONCE(dentry->d_flags);
290 flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
292 WRITE_ONCE(dentry->d_flags, flags);
295 static inline void __d_clear_type_and_inode(struct dentry *dentry)
297 unsigned flags = READ_ONCE(dentry->d_flags);
299 flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
300 WRITE_ONCE(dentry->d_flags, flags);
301 dentry->d_inode = NULL;
304 static void dentry_free(struct dentry *dentry)
306 WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
307 if (unlikely(dname_external(dentry))) {
308 struct external_name *p = external_name(dentry);
309 if (likely(atomic_dec_and_test(&p->u.count))) {
310 call_rcu(&dentry->d_u.d_rcu, __d_free_external);
314 /* if dentry was never visible to RCU, immediate free is OK */
315 if (!(dentry->d_flags & DCACHE_RCUACCESS))
316 __d_free(&dentry->d_u.d_rcu);
318 call_rcu(&dentry->d_u.d_rcu, __d_free);
322 * dentry_rcuwalk_invalidate - invalidate in-progress rcu-walk lookups
323 * @dentry: the target dentry
324 * After this call, in-progress rcu-walk path lookup will fail. This
325 * should be called after unhashing, and after changing d_inode (if
326 * the dentry has not already been unhashed).
328 static inline void dentry_rcuwalk_invalidate(struct dentry *dentry)
330 lockdep_assert_held(&dentry->d_lock);
331 /* Go through am invalidation barrier */
332 write_seqcount_invalidate(&dentry->d_seq);
336 * Release the dentry's inode, using the filesystem
337 * d_iput() operation if defined.
339 static void dentry_unlink_inode(struct dentry * dentry)
340 __releases(dentry->d_lock)
341 __releases(dentry->d_inode->i_lock)
343 struct inode *inode = dentry->d_inode;
344 bool hashed = !d_unhashed(dentry);
347 raw_write_seqcount_begin(&dentry->d_seq);
348 __d_clear_type_and_inode(dentry);
349 hlist_del_init(&dentry->d_u.d_alias);
351 raw_write_seqcount_end(&dentry->d_seq);
352 spin_unlock(&dentry->d_lock);
353 spin_unlock(&inode->i_lock);
355 fsnotify_inoderemove(inode);
356 if (dentry->d_op && dentry->d_op->d_iput)
357 dentry->d_op->d_iput(dentry, inode);
363 * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry
364 * is in use - which includes both the "real" per-superblock
365 * LRU list _and_ the DCACHE_SHRINK_LIST use.
367 * The DCACHE_SHRINK_LIST bit is set whenever the dentry is
368 * on the shrink list (ie not on the superblock LRU list).
370 * The per-cpu "nr_dentry_unused" counters are updated with
371 * the DCACHE_LRU_LIST bit.
373 * These helper functions make sure we always follow the
374 * rules. d_lock must be held by the caller.
376 #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x))
377 static void d_lru_add(struct dentry *dentry)
379 D_FLAG_VERIFY(dentry, 0);
380 dentry->d_flags |= DCACHE_LRU_LIST;
381 this_cpu_inc(nr_dentry_unused);
382 WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
385 static void d_lru_del(struct dentry *dentry)
387 D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
388 dentry->d_flags &= ~DCACHE_LRU_LIST;
389 this_cpu_dec(nr_dentry_unused);
390 WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru));
393 static void d_shrink_del(struct dentry *dentry)
395 D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
396 list_del_init(&dentry->d_lru);
397 dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST);
398 this_cpu_dec(nr_dentry_unused);
401 static void d_shrink_add(struct dentry *dentry, struct list_head *list)
403 D_FLAG_VERIFY(dentry, 0);
404 list_add(&dentry->d_lru, list);
405 dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST;
406 this_cpu_inc(nr_dentry_unused);
410 * These can only be called under the global LRU lock, ie during the
411 * callback for freeing the LRU list. "isolate" removes it from the
412 * LRU lists entirely, while shrink_move moves it to the indicated
415 static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry)
417 D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
418 dentry->d_flags &= ~DCACHE_LRU_LIST;
419 this_cpu_dec(nr_dentry_unused);
420 list_lru_isolate(lru, &dentry->d_lru);
423 static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry,
424 struct list_head *list)
426 D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST);
427 dentry->d_flags |= DCACHE_SHRINK_LIST;
428 list_lru_isolate_move(lru, &dentry->d_lru, list);
432 * dentry_lru_(add|del)_list) must be called with d_lock held.
434 static void dentry_lru_add(struct dentry *dentry)
436 if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST)))
441 * d_drop - drop a dentry
442 * @dentry: dentry to drop
444 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
445 * be found through a VFS lookup any more. Note that this is different from
446 * deleting the dentry - d_delete will try to mark the dentry negative if
447 * possible, giving a successful _negative_ lookup, while d_drop will
448 * just make the cache lookup fail.
450 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
451 * reason (NFS timeouts or autofs deletes).
453 * __d_drop requires dentry->d_lock.
455 void __d_drop(struct dentry *dentry)
457 if (!d_unhashed(dentry)) {
458 struct hlist_bl_head *b;
460 * Hashed dentries are normally on the dentry hashtable,
461 * with the exception of those newly allocated by
462 * d_obtain_alias, which are always IS_ROOT:
464 if (unlikely(IS_ROOT(dentry)))
465 b = &dentry->d_sb->s_anon;
467 b = d_hash(dentry->d_parent, dentry->d_name.hash);
470 __hlist_bl_del(&dentry->d_hash);
471 dentry->d_hash.pprev = NULL;
473 dentry_rcuwalk_invalidate(dentry);
476 EXPORT_SYMBOL(__d_drop);
478 void d_drop(struct dentry *dentry)
480 spin_lock(&dentry->d_lock);
482 spin_unlock(&dentry->d_lock);
484 EXPORT_SYMBOL(d_drop);
486 static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
490 * Inform d_walk() and shrink_dentry_list() that we are no longer
491 * attached to the dentry tree
493 dentry->d_flags |= DCACHE_DENTRY_KILLED;
494 if (unlikely(list_empty(&dentry->d_child)))
496 __list_del_entry(&dentry->d_child);
498 * Cursors can move around the list of children. While we'd been
499 * a normal list member, it didn't matter - ->d_child.next would've
500 * been updated. However, from now on it won't be and for the
501 * things like d_walk() it might end up with a nasty surprise.
502 * Normally d_walk() doesn't care about cursors moving around -
503 * ->d_lock on parent prevents that and since a cursor has no children
504 * of its own, we get through it without ever unlocking the parent.
505 * There is one exception, though - if we ascend from a child that
506 * gets killed as soon as we unlock it, the next sibling is found
507 * using the value left in its ->d_child.next. And if _that_
508 * pointed to a cursor, and cursor got moved (e.g. by lseek())
509 * before d_walk() regains parent->d_lock, we'll end up skipping
510 * everything the cursor had been moved past.
512 * Solution: make sure that the pointer left behind in ->d_child.next
513 * points to something that won't be moving around. I.e. skip the
516 while (dentry->d_child.next != &parent->d_subdirs) {
517 next = list_entry(dentry->d_child.next, struct dentry, d_child);
518 if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR)))
520 dentry->d_child.next = next->d_child.next;
524 static void __dentry_kill(struct dentry *dentry)
526 struct dentry *parent = NULL;
527 bool can_free = true;
528 if (!IS_ROOT(dentry))
529 parent = dentry->d_parent;
532 * The dentry is now unrecoverably dead to the world.
534 lockref_mark_dead(&dentry->d_lockref);
537 * inform the fs via d_prune that this dentry is about to be
538 * unhashed and destroyed.
540 if (dentry->d_flags & DCACHE_OP_PRUNE)
541 dentry->d_op->d_prune(dentry);
543 if (dentry->d_flags & DCACHE_LRU_LIST) {
544 if (!(dentry->d_flags & DCACHE_SHRINK_LIST))
547 /* if it was on the hash then remove it */
549 dentry_unlist(dentry, parent);
551 spin_unlock(&parent->d_lock);
553 dentry_unlink_inode(dentry);
555 spin_unlock(&dentry->d_lock);
556 this_cpu_dec(nr_dentry);
557 if (dentry->d_op && dentry->d_op->d_release)
558 dentry->d_op->d_release(dentry);
560 spin_lock(&dentry->d_lock);
561 if (dentry->d_flags & DCACHE_SHRINK_LIST) {
562 dentry->d_flags |= DCACHE_MAY_FREE;
565 spin_unlock(&dentry->d_lock);
566 if (likely(can_free))
571 * Finish off a dentry we've decided to kill.
572 * dentry->d_lock must be held, returns with it unlocked.
573 * If ref is non-zero, then decrement the refcount too.
574 * Returns dentry requiring refcount drop, or NULL if we're done.
576 static struct dentry *dentry_kill(struct dentry *dentry)
577 __releases(dentry->d_lock)
579 struct inode *inode = dentry->d_inode;
580 struct dentry *parent = NULL;
582 if (inode && unlikely(!spin_trylock(&inode->i_lock)))
585 if (!IS_ROOT(dentry)) {
586 parent = dentry->d_parent;
587 if (unlikely(!spin_trylock(&parent->d_lock))) {
589 spin_unlock(&inode->i_lock);
594 __dentry_kill(dentry);
598 spin_unlock(&dentry->d_lock);
600 return dentry; /* try again with same dentry */
603 static inline struct dentry *lock_parent(struct dentry *dentry)
605 struct dentry *parent = dentry->d_parent;
608 if (unlikely(dentry->d_lockref.count < 0))
610 if (likely(spin_trylock(&parent->d_lock)))
613 spin_unlock(&dentry->d_lock);
615 parent = ACCESS_ONCE(dentry->d_parent);
616 spin_lock(&parent->d_lock);
618 * We can't blindly lock dentry until we are sure
619 * that we won't violate the locking order.
620 * Any changes of dentry->d_parent must have
621 * been done with parent->d_lock held, so
622 * spin_lock() above is enough of a barrier
623 * for checking if it's still our child.
625 if (unlikely(parent != dentry->d_parent)) {
626 spin_unlock(&parent->d_lock);
630 if (parent != dentry)
631 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
638 * Try to do a lockless dput(), and return whether that was successful.
640 * If unsuccessful, we return false, having already taken the dentry lock.
642 * The caller needs to hold the RCU read lock, so that the dentry is
643 * guaranteed to stay around even if the refcount goes down to zero!
645 static inline bool fast_dput(struct dentry *dentry)
648 unsigned int d_flags;
651 * If we have a d_op->d_delete() operation, we sould not
652 * let the dentry count go to zero, so use "put_or_lock".
654 if (unlikely(dentry->d_flags & DCACHE_OP_DELETE))
655 return lockref_put_or_lock(&dentry->d_lockref);
658 * .. otherwise, we can try to just decrement the
659 * lockref optimistically.
661 ret = lockref_put_return(&dentry->d_lockref);
664 * If the lockref_put_return() failed due to the lock being held
665 * by somebody else, the fast path has failed. We will need to
666 * get the lock, and then check the count again.
668 if (unlikely(ret < 0)) {
669 spin_lock(&dentry->d_lock);
670 if (dentry->d_lockref.count > 1) {
671 dentry->d_lockref.count--;
672 spin_unlock(&dentry->d_lock);
679 * If we weren't the last ref, we're done.
685 * Careful, careful. The reference count went down
686 * to zero, but we don't hold the dentry lock, so
687 * somebody else could get it again, and do another
688 * dput(), and we need to not race with that.
690 * However, there is a very special and common case
691 * where we don't care, because there is nothing to
692 * do: the dentry is still hashed, it does not have
693 * a 'delete' op, and it's referenced and already on
696 * NOTE! Since we aren't locked, these values are
697 * not "stable". However, it is sufficient that at
698 * some point after we dropped the reference the
699 * dentry was hashed and the flags had the proper
700 * value. Other dentry users may have re-gotten
701 * a reference to the dentry and change that, but
702 * our work is done - we can leave the dentry
703 * around with a zero refcount.
706 d_flags = ACCESS_ONCE(dentry->d_flags);
707 d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED;
709 /* Nothing to do? Dropping the reference was all we needed? */
710 if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
714 * Not the fast normal case? Get the lock. We've already decremented
715 * the refcount, but we'll need to re-check the situation after
718 spin_lock(&dentry->d_lock);
721 * Did somebody else grab a reference to it in the meantime, and
722 * we're no longer the last user after all? Alternatively, somebody
723 * else could have killed it and marked it dead. Either way, we
724 * don't need to do anything else.
726 if (dentry->d_lockref.count) {
727 spin_unlock(&dentry->d_lock);
732 * Re-get the reference we optimistically dropped. We hold the
733 * lock, and we just tested that it was zero, so we can just
736 dentry->d_lockref.count = 1;
744 * This is complicated by the fact that we do not want to put
745 * dentries that are no longer on any hash chain on the unused
746 * list: we'd much rather just get rid of them immediately.
748 * However, that implies that we have to traverse the dentry
749 * tree upwards to the parents which might _also_ now be
750 * scheduled for deletion (it may have been only waiting for
751 * its last child to go away).
753 * This tail recursion is done by hand as we don't want to depend
754 * on the compiler to always get this right (gcc generally doesn't).
755 * Real recursion would eat up our stack space.
759 * dput - release a dentry
760 * @dentry: dentry to release
762 * Release a dentry. This will drop the usage count and if appropriate
763 * call the dentry unlink method as well as removing it from the queues and
764 * releasing its resources. If the parent dentries were scheduled for release
765 * they too may now get deleted.
767 void dput(struct dentry *dentry)
769 if (unlikely(!dentry))
774 if (likely(fast_dput(dentry))) {
779 /* Slow case: now with the dentry lock held */
782 WARN_ON(d_in_lookup(dentry));
784 /* Unreachable? Get rid of it */
785 if (unlikely(d_unhashed(dentry)))
788 if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
791 if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) {
792 if (dentry->d_op->d_delete(dentry))
796 if (!(dentry->d_flags & DCACHE_REFERENCED))
797 dentry->d_flags |= DCACHE_REFERENCED;
798 dentry_lru_add(dentry);
800 dentry->d_lockref.count--;
801 spin_unlock(&dentry->d_lock);
805 dentry = dentry_kill(dentry);
812 /* This must be called with d_lock held */
813 static inline void __dget_dlock(struct dentry *dentry)
815 dentry->d_lockref.count++;
818 static inline void __dget(struct dentry *dentry)
820 lockref_get(&dentry->d_lockref);
823 struct dentry *dget_parent(struct dentry *dentry)
829 * Do optimistic parent lookup without any
833 ret = ACCESS_ONCE(dentry->d_parent);
834 gotref = lockref_get_not_zero(&ret->d_lockref);
836 if (likely(gotref)) {
837 if (likely(ret == ACCESS_ONCE(dentry->d_parent)))
844 * Don't need rcu_dereference because we re-check it was correct under
848 ret = dentry->d_parent;
849 spin_lock(&ret->d_lock);
850 if (unlikely(ret != dentry->d_parent)) {
851 spin_unlock(&ret->d_lock);
856 BUG_ON(!ret->d_lockref.count);
857 ret->d_lockref.count++;
858 spin_unlock(&ret->d_lock);
861 EXPORT_SYMBOL(dget_parent);
864 * d_find_alias - grab a hashed alias of inode
865 * @inode: inode in question
867 * If inode has a hashed alias, or is a directory and has any alias,
868 * acquire the reference to alias and return it. Otherwise return NULL.
869 * Notice that if inode is a directory there can be only one alias and
870 * it can be unhashed only if it has no children, or if it is the root
871 * of a filesystem, or if the directory was renamed and d_revalidate
872 * was the first vfs operation to notice.
874 * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer
875 * any other hashed alias over that one.
877 static struct dentry *__d_find_alias(struct inode *inode)
879 struct dentry *alias, *discon_alias;
883 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
884 spin_lock(&alias->d_lock);
885 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
886 if (IS_ROOT(alias) &&
887 (alias->d_flags & DCACHE_DISCONNECTED)) {
888 discon_alias = alias;
891 spin_unlock(&alias->d_lock);
895 spin_unlock(&alias->d_lock);
898 alias = discon_alias;
899 spin_lock(&alias->d_lock);
900 if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
902 spin_unlock(&alias->d_lock);
905 spin_unlock(&alias->d_lock);
911 struct dentry *d_find_alias(struct inode *inode)
913 struct dentry *de = NULL;
915 if (!hlist_empty(&inode->i_dentry)) {
916 spin_lock(&inode->i_lock);
917 de = __d_find_alias(inode);
918 spin_unlock(&inode->i_lock);
922 EXPORT_SYMBOL(d_find_alias);
925 * Try to kill dentries associated with this inode.
926 * WARNING: you must own a reference to inode.
928 void d_prune_aliases(struct inode *inode)
930 struct dentry *dentry;
932 spin_lock(&inode->i_lock);
933 hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
934 spin_lock(&dentry->d_lock);
935 if (!dentry->d_lockref.count) {
936 struct dentry *parent = lock_parent(dentry);
937 if (likely(!dentry->d_lockref.count)) {
938 __dentry_kill(dentry);
943 spin_unlock(&parent->d_lock);
945 spin_unlock(&dentry->d_lock);
947 spin_unlock(&inode->i_lock);
949 EXPORT_SYMBOL(d_prune_aliases);
951 static void shrink_dentry_list(struct list_head *list)
953 struct dentry *dentry, *parent;
955 while (!list_empty(list)) {
957 dentry = list_entry(list->prev, struct dentry, d_lru);
958 spin_lock(&dentry->d_lock);
959 parent = lock_parent(dentry);
962 * The dispose list is isolated and dentries are not accounted
963 * to the LRU here, so we can simply remove it from the list
964 * here regardless of whether it is referenced or not.
966 d_shrink_del(dentry);
969 * We found an inuse dentry which was not removed from
970 * the LRU because of laziness during lookup. Do not free it.
972 if (dentry->d_lockref.count > 0) {
973 spin_unlock(&dentry->d_lock);
975 spin_unlock(&parent->d_lock);
980 if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
981 bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
982 spin_unlock(&dentry->d_lock);
984 spin_unlock(&parent->d_lock);
990 inode = dentry->d_inode;
991 if (inode && unlikely(!spin_trylock(&inode->i_lock))) {
992 d_shrink_add(dentry, list);
993 spin_unlock(&dentry->d_lock);
995 spin_unlock(&parent->d_lock);
999 __dentry_kill(dentry);
1002 * We need to prune ancestors too. This is necessary to prevent
1003 * quadratic behavior of shrink_dcache_parent(), but is also
1004 * expected to be beneficial in reducing dentry cache
1008 while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) {
1009 parent = lock_parent(dentry);
1010 if (dentry->d_lockref.count != 1) {
1011 dentry->d_lockref.count--;
1012 spin_unlock(&dentry->d_lock);
1014 spin_unlock(&parent->d_lock);
1017 inode = dentry->d_inode; /* can't be NULL */
1018 if (unlikely(!spin_trylock(&inode->i_lock))) {
1019 spin_unlock(&dentry->d_lock);
1021 spin_unlock(&parent->d_lock);
1025 __dentry_kill(dentry);
1031 static enum lru_status dentry_lru_isolate(struct list_head *item,
1032 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
1034 struct list_head *freeable = arg;
1035 struct dentry *dentry = container_of(item, struct dentry, d_lru);
1039 * we are inverting the lru lock/dentry->d_lock here,
1040 * so use a trylock. If we fail to get the lock, just skip
1043 if (!spin_trylock(&dentry->d_lock))
1047 * Referenced dentries are still in use. If they have active
1048 * counts, just remove them from the LRU. Otherwise give them
1049 * another pass through the LRU.
1051 if (dentry->d_lockref.count) {
1052 d_lru_isolate(lru, dentry);
1053 spin_unlock(&dentry->d_lock);
1057 if (dentry->d_flags & DCACHE_REFERENCED) {
1058 dentry->d_flags &= ~DCACHE_REFERENCED;
1059 spin_unlock(&dentry->d_lock);
1062 * The list move itself will be made by the common LRU code. At
1063 * this point, we've dropped the dentry->d_lock but keep the
1064 * lru lock. This is safe to do, since every list movement is
1065 * protected by the lru lock even if both locks are held.
1067 * This is guaranteed by the fact that all LRU management
1068 * functions are intermediated by the LRU API calls like
1069 * list_lru_add and list_lru_del. List movement in this file
1070 * only ever occur through this functions or through callbacks
1071 * like this one, that are called from the LRU API.
1073 * The only exceptions to this are functions like
1074 * shrink_dentry_list, and code that first checks for the
1075 * DCACHE_SHRINK_LIST flag. Those are guaranteed to be
1076 * operating only with stack provided lists after they are
1077 * properly isolated from the main list. It is thus, always a
1083 d_lru_shrink_move(lru, dentry, freeable);
1084 spin_unlock(&dentry->d_lock);
1090 * prune_dcache_sb - shrink the dcache
1092 * @sc: shrink control, passed to list_lru_shrink_walk()
1094 * Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This
1095 * is done when we need more memory and called from the superblock shrinker
1098 * This function may fail to free any resources if all the dentries are in
1101 long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc)
1106 freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc,
1107 dentry_lru_isolate, &dispose);
1108 shrink_dentry_list(&dispose);
1112 static enum lru_status dentry_lru_isolate_shrink(struct list_head *item,
1113 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
1115 struct list_head *freeable = arg;
1116 struct dentry *dentry = container_of(item, struct dentry, d_lru);
1119 * we are inverting the lru lock/dentry->d_lock here,
1120 * so use a trylock. If we fail to get the lock, just skip
1123 if (!spin_trylock(&dentry->d_lock))
1126 d_lru_shrink_move(lru, dentry, freeable);
1127 spin_unlock(&dentry->d_lock);
1134 * shrink_dcache_sb - shrink dcache for a superblock
1137 * Shrink the dcache for the specified super block. This is used to free
1138 * the dcache before unmounting a file system.
1140 void shrink_dcache_sb(struct super_block *sb)
1147 freed = list_lru_walk(&sb->s_dentry_lru,
1148 dentry_lru_isolate_shrink, &dispose, UINT_MAX);
1150 this_cpu_sub(nr_dentry_unused, freed);
1151 shrink_dentry_list(&dispose);
1152 } while (freed > 0);
1154 EXPORT_SYMBOL(shrink_dcache_sb);
1157 * enum d_walk_ret - action to talke during tree walk
1158 * @D_WALK_CONTINUE: contrinue walk
1159 * @D_WALK_QUIT: quit walk
1160 * @D_WALK_NORETRY: quit when retry is needed
1161 * @D_WALK_SKIP: skip this dentry and its children
1171 * d_walk - walk the dentry tree
1172 * @parent: start of walk
1173 * @data: data passed to @enter() and @finish()
1174 * @enter: callback when first entering the dentry
1175 * @finish: callback when successfully finished the walk
1177 * The @enter() and @finish() callbacks are called with d_lock held.
1179 static void d_walk(struct dentry *parent, void *data,
1180 enum d_walk_ret (*enter)(void *, struct dentry *),
1181 void (*finish)(void *))
1183 struct dentry *this_parent;
1184 struct list_head *next;
1186 enum d_walk_ret ret;
1190 read_seqbegin_or_lock(&rename_lock, &seq);
1191 this_parent = parent;
1192 spin_lock(&this_parent->d_lock);
1194 ret = enter(data, this_parent);
1196 case D_WALK_CONTINUE:
1201 case D_WALK_NORETRY:
1206 next = this_parent->d_subdirs.next;
1208 while (next != &this_parent->d_subdirs) {
1209 struct list_head *tmp = next;
1210 struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
1213 if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR))
1216 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
1218 ret = enter(data, dentry);
1220 case D_WALK_CONTINUE:
1223 spin_unlock(&dentry->d_lock);
1225 case D_WALK_NORETRY:
1229 spin_unlock(&dentry->d_lock);
1233 if (!list_empty(&dentry->d_subdirs)) {
1234 spin_unlock(&this_parent->d_lock);
1235 spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_);
1236 this_parent = dentry;
1237 spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_);
1240 spin_unlock(&dentry->d_lock);
1243 * All done at this level ... ascend and resume the search.
1247 if (this_parent != parent) {
1248 struct dentry *child = this_parent;
1249 this_parent = child->d_parent;
1251 spin_unlock(&child->d_lock);
1252 spin_lock(&this_parent->d_lock);
1254 /* might go back up the wrong parent if we have had a rename. */
1255 if (need_seqretry(&rename_lock, seq))
1257 /* go into the first sibling still alive */
1259 next = child->d_child.next;
1260 if (next == &this_parent->d_subdirs)
1262 child = list_entry(next, struct dentry, d_child);
1263 } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
1267 if (need_seqretry(&rename_lock, seq))
1274 spin_unlock(&this_parent->d_lock);
1275 done_seqretry(&rename_lock, seq);
1279 spin_unlock(&this_parent->d_lock);
1289 * Search for at least 1 mount point in the dentry's subdirs.
1290 * We descend to the next level whenever the d_subdirs
1291 * list is non-empty and continue searching.
1294 static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
1297 if (d_mountpoint(dentry)) {
1301 return D_WALK_CONTINUE;
1305 * have_submounts - check for mounts over a dentry
1306 * @parent: dentry to check.
1308 * Return true if the parent or its subdirectories contain
1311 int have_submounts(struct dentry *parent)
1315 d_walk(parent, &ret, check_mount, NULL);
1319 EXPORT_SYMBOL(have_submounts);
1322 * Called by mount code to set a mountpoint and check if the mountpoint is
1323 * reachable (e.g. NFS can unhash a directory dentry and then the complete
1324 * subtree can become unreachable).
1326 * Only one of d_invalidate() and d_set_mounted() must succeed. For
1327 * this reason take rename_lock and d_lock on dentry and ancestors.
1329 int d_set_mounted(struct dentry *dentry)
1333 write_seqlock(&rename_lock);
1334 for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
1335 /* Need exclusion wrt. d_invalidate() */
1336 spin_lock(&p->d_lock);
1337 if (unlikely(d_unhashed(p))) {
1338 spin_unlock(&p->d_lock);
1341 spin_unlock(&p->d_lock);
1343 spin_lock(&dentry->d_lock);
1344 if (!d_unlinked(dentry)) {
1345 dentry->d_flags |= DCACHE_MOUNTED;
1348 spin_unlock(&dentry->d_lock);
1350 write_sequnlock(&rename_lock);
1355 * Search the dentry child list of the specified parent,
1356 * and move any unused dentries to the end of the unused
1357 * list for prune_dcache(). We descend to the next level
1358 * whenever the d_subdirs list is non-empty and continue
1361 * It returns zero iff there are no unused children,
1362 * otherwise it returns the number of children moved to
1363 * the end of the unused list. This may not be the total
1364 * number of unused children, because select_parent can
1365 * drop the lock and return early due to latency
1369 struct select_data {
1370 struct dentry *start;
1371 struct list_head dispose;
1375 static enum d_walk_ret select_collect(void *_data, struct dentry *dentry)
1377 struct select_data *data = _data;
1378 enum d_walk_ret ret = D_WALK_CONTINUE;
1380 if (data->start == dentry)
1383 if (dentry->d_flags & DCACHE_SHRINK_LIST) {
1386 if (dentry->d_flags & DCACHE_LRU_LIST)
1388 if (!dentry->d_lockref.count) {
1389 d_shrink_add(dentry, &data->dispose);
1394 * We can return to the caller if we have found some (this
1395 * ensures forward progress). We'll be coming back to find
1398 if (!list_empty(&data->dispose))
1399 ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
1405 * shrink_dcache_parent - prune dcache
1406 * @parent: parent of entries to prune
1408 * Prune the dcache to remove unused children of the parent dentry.
1410 void shrink_dcache_parent(struct dentry *parent)
1413 struct select_data data;
1415 INIT_LIST_HEAD(&data.dispose);
1416 data.start = parent;
1419 d_walk(parent, &data, select_collect, NULL);
1423 shrink_dentry_list(&data.dispose);
1427 EXPORT_SYMBOL(shrink_dcache_parent);
1429 static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
1431 /* it has busy descendents; complain about those instead */
1432 if (!list_empty(&dentry->d_subdirs))
1433 return D_WALK_CONTINUE;
1435 /* root with refcount 1 is fine */
1436 if (dentry == _data && dentry->d_lockref.count == 1)
1437 return D_WALK_CONTINUE;
1439 printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} "
1440 " still in use (%d) [unmount of %s %s]\n",
1443 dentry->d_inode->i_ino : 0UL,
1445 dentry->d_lockref.count,
1446 dentry->d_sb->s_type->name,
1447 dentry->d_sb->s_id);
1449 return D_WALK_CONTINUE;
1452 static void do_one_tree(struct dentry *dentry)
1454 shrink_dcache_parent(dentry);
1455 d_walk(dentry, dentry, umount_check, NULL);
1461 * destroy the dentries attached to a superblock on unmounting
1463 void shrink_dcache_for_umount(struct super_block *sb)
1465 struct dentry *dentry;
1467 WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
1469 dentry = sb->s_root;
1471 do_one_tree(dentry);
1473 while (!hlist_bl_empty(&sb->s_anon)) {
1474 dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash));
1475 do_one_tree(dentry);
1479 struct detach_data {
1480 struct select_data select;
1481 struct dentry *mountpoint;
1483 static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry)
1485 struct detach_data *data = _data;
1487 if (d_mountpoint(dentry)) {
1488 __dget_dlock(dentry);
1489 data->mountpoint = dentry;
1493 return select_collect(&data->select, dentry);
1496 static void check_and_drop(void *_data)
1498 struct detach_data *data = _data;
1500 if (!data->mountpoint && !data->select.found)
1501 __d_drop(data->select.start);
1505 * d_invalidate - detach submounts, prune dcache, and drop
1506 * @dentry: dentry to invalidate (aka detach, prune and drop)
1510 * The final d_drop is done as an atomic operation relative to
1511 * rename_lock ensuring there are no races with d_set_mounted. This
1512 * ensures there are no unhashed dentries on the path to a mountpoint.
1514 void d_invalidate(struct dentry *dentry)
1517 * If it's already been dropped, return OK.
1519 spin_lock(&dentry->d_lock);
1520 if (d_unhashed(dentry)) {
1521 spin_unlock(&dentry->d_lock);
1524 spin_unlock(&dentry->d_lock);
1526 /* Negative dentries can be dropped without further checks */
1527 if (!dentry->d_inode) {
1533 struct detach_data data;
1535 data.mountpoint = NULL;
1536 INIT_LIST_HEAD(&data.select.dispose);
1537 data.select.start = dentry;
1538 data.select.found = 0;
1540 d_walk(dentry, &data, detach_and_collect, check_and_drop);
1542 if (data.select.found)
1543 shrink_dentry_list(&data.select.dispose);
1545 if (data.mountpoint) {
1546 detach_mounts(data.mountpoint);
1547 dput(data.mountpoint);
1550 if (!data.mountpoint && !data.select.found)
1556 EXPORT_SYMBOL(d_invalidate);
1559 * __d_alloc - allocate a dcache entry
1560 * @sb: filesystem it will belong to
1561 * @name: qstr of the name
1563 * Allocates a dentry. It returns %NULL if there is insufficient memory
1564 * available. On a success the dentry is returned. The name passed in is
1565 * copied and the copy passed in may be reused after this call.
1568 struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
1570 struct dentry *dentry;
1573 dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL);
1578 * We guarantee that the inline name is always NUL-terminated.
1579 * This way the memcpy() done by the name switching in rename
1580 * will still always have a NUL at the end, even if we might
1581 * be overwriting an internal NUL character
1583 dentry->d_iname[DNAME_INLINE_LEN-1] = 0;
1584 if (unlikely(!name)) {
1585 static const struct qstr anon = QSTR_INIT("/", 1);
1587 dname = dentry->d_iname;
1588 } else if (name->len > DNAME_INLINE_LEN-1) {
1589 size_t size = offsetof(struct external_name, name[1]);
1590 struct external_name *p = kmalloc(size + name->len,
1591 GFP_KERNEL_ACCOUNT);
1593 kmem_cache_free(dentry_cache, dentry);
1596 atomic_set(&p->u.count, 1);
1598 if (IS_ENABLED(CONFIG_DCACHE_WORD_ACCESS))
1599 kasan_unpoison_shadow(dname,
1600 round_up(name->len + 1, sizeof(unsigned long)));
1602 dname = dentry->d_iname;
1605 dentry->d_name.len = name->len;
1606 dentry->d_name.hash = name->hash;
1607 memcpy(dname, name->name, name->len);
1608 dname[name->len] = 0;
1610 /* Make sure we always see the terminating NUL character */
1612 dentry->d_name.name = dname;
1614 dentry->d_lockref.count = 1;
1615 dentry->d_flags = 0;
1616 spin_lock_init(&dentry->d_lock);
1617 seqcount_init(&dentry->d_seq);
1618 dentry->d_inode = NULL;
1619 dentry->d_parent = dentry;
1621 dentry->d_op = NULL;
1622 dentry->d_fsdata = NULL;
1623 INIT_HLIST_BL_NODE(&dentry->d_hash);
1624 INIT_LIST_HEAD(&dentry->d_lru);
1625 INIT_LIST_HEAD(&dentry->d_subdirs);
1626 INIT_HLIST_NODE(&dentry->d_u.d_alias);
1627 INIT_LIST_HEAD(&dentry->d_child);
1628 d_set_d_op(dentry, dentry->d_sb->s_d_op);
1630 this_cpu_inc(nr_dentry);
1636 * d_alloc - allocate a dcache entry
1637 * @parent: parent of entry to allocate
1638 * @name: qstr of the name
1640 * Allocates a dentry. It returns %NULL if there is insufficient memory
1641 * available. On a success the dentry is returned. The name passed in is
1642 * copied and the copy passed in may be reused after this call.
1644 struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
1646 struct dentry *dentry = __d_alloc(parent->d_sb, name);
1649 dentry->d_flags |= DCACHE_RCUACCESS;
1650 spin_lock(&parent->d_lock);
1652 * don't need child lock because it is not subject
1653 * to concurrency here
1655 __dget_dlock(parent);
1656 dentry->d_parent = parent;
1657 list_add(&dentry->d_child, &parent->d_subdirs);
1658 spin_unlock(&parent->d_lock);
1662 EXPORT_SYMBOL(d_alloc);
1664 struct dentry *d_alloc_cursor(struct dentry * parent)
1666 struct dentry *dentry = __d_alloc(parent->d_sb, NULL);
1668 dentry->d_flags |= DCACHE_RCUACCESS | DCACHE_DENTRY_CURSOR;
1669 dentry->d_parent = dget(parent);
1675 * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems)
1676 * @sb: the superblock
1677 * @name: qstr of the name
1679 * For a filesystem that just pins its dentries in memory and never
1680 * performs lookups at all, return an unhashed IS_ROOT dentry.
1682 struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
1684 return __d_alloc(sb, name);
1686 EXPORT_SYMBOL(d_alloc_pseudo);
1688 struct dentry *d_alloc_name(struct dentry *parent, const char *name)
1693 q.hash_len = hashlen_string(name);
1694 return d_alloc(parent, &q);
1696 EXPORT_SYMBOL(d_alloc_name);
1698 void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
1700 WARN_ON_ONCE(dentry->d_op);
1701 WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH |
1703 DCACHE_OP_REVALIDATE |
1704 DCACHE_OP_WEAK_REVALIDATE |
1711 dentry->d_flags |= DCACHE_OP_HASH;
1713 dentry->d_flags |= DCACHE_OP_COMPARE;
1714 if (op->d_revalidate)
1715 dentry->d_flags |= DCACHE_OP_REVALIDATE;
1716 if (op->d_weak_revalidate)
1717 dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE;
1719 dentry->d_flags |= DCACHE_OP_DELETE;
1721 dentry->d_flags |= DCACHE_OP_PRUNE;
1723 dentry->d_flags |= DCACHE_OP_REAL;
1726 EXPORT_SYMBOL(d_set_d_op);
1730 * d_set_fallthru - Mark a dentry as falling through to a lower layer
1731 * @dentry - The dentry to mark
1733 * Mark a dentry as falling through to the lower layer (as set with
1734 * d_pin_lower()). This flag may be recorded on the medium.
1736 void d_set_fallthru(struct dentry *dentry)
1738 spin_lock(&dentry->d_lock);
1739 dentry->d_flags |= DCACHE_FALLTHRU;
1740 spin_unlock(&dentry->d_lock);
1742 EXPORT_SYMBOL(d_set_fallthru);
1744 static unsigned d_flags_for_inode(struct inode *inode)
1746 unsigned add_flags = DCACHE_REGULAR_TYPE;
1749 return DCACHE_MISS_TYPE;
1751 if (S_ISDIR(inode->i_mode)) {
1752 add_flags = DCACHE_DIRECTORY_TYPE;
1753 if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
1754 if (unlikely(!inode->i_op->lookup))
1755 add_flags = DCACHE_AUTODIR_TYPE;
1757 inode->i_opflags |= IOP_LOOKUP;
1759 goto type_determined;
1762 if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
1763 if (unlikely(inode->i_op->get_link)) {
1764 add_flags = DCACHE_SYMLINK_TYPE;
1765 goto type_determined;
1767 inode->i_opflags |= IOP_NOFOLLOW;
1770 if (unlikely(!S_ISREG(inode->i_mode)))
1771 add_flags = DCACHE_SPECIAL_TYPE;
1774 if (unlikely(IS_AUTOMOUNT(inode)))
1775 add_flags |= DCACHE_NEED_AUTOMOUNT;
1779 static void __d_instantiate(struct dentry *dentry, struct inode *inode)
1781 unsigned add_flags = d_flags_for_inode(inode);
1782 WARN_ON(d_in_lookup(dentry));
1784 spin_lock(&dentry->d_lock);
1785 hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
1786 raw_write_seqcount_begin(&dentry->d_seq);
1787 __d_set_inode_and_type(dentry, inode, add_flags);
1788 raw_write_seqcount_end(&dentry->d_seq);
1789 fsnotify_update_flags(dentry);
1790 spin_unlock(&dentry->d_lock);
1794 * d_instantiate - fill in inode information for a dentry
1795 * @entry: dentry to complete
1796 * @inode: inode to attach to this dentry
1798 * Fill in inode information in the entry.
1800 * This turns negative dentries into productive full members
1803 * NOTE! This assumes that the inode count has been incremented
1804 * (or otherwise set) by the caller to indicate that it is now
1805 * in use by the dcache.
1808 void d_instantiate(struct dentry *entry, struct inode * inode)
1810 BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
1812 security_d_instantiate(entry, inode);
1813 spin_lock(&inode->i_lock);
1814 __d_instantiate(entry, inode);
1815 spin_unlock(&inode->i_lock);
1818 EXPORT_SYMBOL(d_instantiate);
1821 * d_instantiate_no_diralias - instantiate a non-aliased dentry
1822 * @entry: dentry to complete
1823 * @inode: inode to attach to this dentry
1825 * Fill in inode information in the entry. If a directory alias is found, then
1826 * return an error (and drop inode). Together with d_materialise_unique() this
1827 * guarantees that a directory inode may never have more than one alias.
1829 int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode)
1831 BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
1833 security_d_instantiate(entry, inode);
1834 spin_lock(&inode->i_lock);
1835 if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) {
1836 spin_unlock(&inode->i_lock);
1840 __d_instantiate(entry, inode);
1841 spin_unlock(&inode->i_lock);
1845 EXPORT_SYMBOL(d_instantiate_no_diralias);
1847 struct dentry *d_make_root(struct inode *root_inode)
1849 struct dentry *res = NULL;
1852 res = __d_alloc(root_inode->i_sb, NULL);
1854 d_instantiate(res, root_inode);
1860 EXPORT_SYMBOL(d_make_root);
1862 static struct dentry * __d_find_any_alias(struct inode *inode)
1864 struct dentry *alias;
1866 if (hlist_empty(&inode->i_dentry))
1868 alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
1874 * d_find_any_alias - find any alias for a given inode
1875 * @inode: inode to find an alias for
1877 * If any aliases exist for the given inode, take and return a
1878 * reference for one of them. If no aliases exist, return %NULL.
1880 struct dentry *d_find_any_alias(struct inode *inode)
1884 spin_lock(&inode->i_lock);
1885 de = __d_find_any_alias(inode);
1886 spin_unlock(&inode->i_lock);
1889 EXPORT_SYMBOL(d_find_any_alias);
1891 static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
1898 return ERR_PTR(-ESTALE);
1900 return ERR_CAST(inode);
1902 res = d_find_any_alias(inode);
1906 tmp = __d_alloc(inode->i_sb, NULL);
1908 res = ERR_PTR(-ENOMEM);
1912 security_d_instantiate(tmp, inode);
1913 spin_lock(&inode->i_lock);
1914 res = __d_find_any_alias(inode);
1916 spin_unlock(&inode->i_lock);
1921 /* attach a disconnected dentry */
1922 add_flags = d_flags_for_inode(inode);
1925 add_flags |= DCACHE_DISCONNECTED;
1927 spin_lock(&tmp->d_lock);
1928 __d_set_inode_and_type(tmp, inode, add_flags);
1929 hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry);
1930 hlist_bl_lock(&tmp->d_sb->s_anon);
1931 hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
1932 hlist_bl_unlock(&tmp->d_sb->s_anon);
1933 spin_unlock(&tmp->d_lock);
1934 spin_unlock(&inode->i_lock);
1944 * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode
1945 * @inode: inode to allocate the dentry for
1947 * Obtain a dentry for an inode resulting from NFS filehandle conversion or
1948 * similar open by handle operations. The returned dentry may be anonymous,
1949 * or may have a full name (if the inode was already in the cache).
1951 * When called on a directory inode, we must ensure that the inode only ever
1952 * has one dentry. If a dentry is found, that is returned instead of
1953 * allocating a new one.
1955 * On successful return, the reference to the inode has been transferred
1956 * to the dentry. In case of an error the reference on the inode is released.
1957 * To make it easier to use in export operations a %NULL or IS_ERR inode may
1958 * be passed in and the error will be propagated to the return value,
1959 * with a %NULL @inode replaced by ERR_PTR(-ESTALE).
1961 struct dentry *d_obtain_alias(struct inode *inode)
1963 return __d_obtain_alias(inode, 1);
1965 EXPORT_SYMBOL(d_obtain_alias);
1968 * d_obtain_root - find or allocate a dentry for a given inode
1969 * @inode: inode to allocate the dentry for
1971 * Obtain an IS_ROOT dentry for the root of a filesystem.
1973 * We must ensure that directory inodes only ever have one dentry. If a
1974 * dentry is found, that is returned instead of allocating a new one.
1976 * On successful return, the reference to the inode has been transferred
1977 * to the dentry. In case of an error the reference on the inode is
1978 * released. A %NULL or IS_ERR inode may be passed in and will be the
1979 * error will be propagate to the return value, with a %NULL @inode
1980 * replaced by ERR_PTR(-ESTALE).
1982 struct dentry *d_obtain_root(struct inode *inode)
1984 return __d_obtain_alias(inode, 0);
1986 EXPORT_SYMBOL(d_obtain_root);
1989 * d_add_ci - lookup or allocate new dentry with case-exact name
1990 * @inode: the inode case-insensitive lookup has found
1991 * @dentry: the negative dentry that was passed to the parent's lookup func
1992 * @name: the case-exact name to be associated with the returned dentry
1994 * This is to avoid filling the dcache with case-insensitive names to the
1995 * same inode, only the actual correct case is stored in the dcache for
1996 * case-insensitive filesystems.
1998 * For a case-insensitive lookup match and if the the case-exact dentry
1999 * already exists in in the dcache, use it and return it.
2001 * If no entry exists with the exact case name, allocate new dentry with
2002 * the exact case, and return the spliced entry.
2004 struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
2007 struct dentry *found, *res;
2010 * First check if a dentry matching the name already exists,
2011 * if not go ahead and create it now.
2013 found = d_hash_and_lookup(dentry->d_parent, name);
2018 if (d_in_lookup(dentry)) {
2019 found = d_alloc_parallel(dentry->d_parent, name,
2021 if (IS_ERR(found) || !d_in_lookup(found)) {
2026 found = d_alloc(dentry->d_parent, name);
2029 return ERR_PTR(-ENOMEM);
2032 res = d_splice_alias(inode, found);
2039 EXPORT_SYMBOL(d_add_ci);
2042 static inline bool d_same_name(const struct dentry *dentry,
2043 const struct dentry *parent,
2044 const struct qstr *name)
2046 if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) {
2047 if (dentry->d_name.len != name->len)
2049 return dentry_cmp(dentry, name->name, name->len) == 0;
2051 return parent->d_op->d_compare(parent, dentry,
2052 dentry->d_name.len, dentry->d_name.name,
2057 * __d_lookup_rcu - search for a dentry (racy, store-free)
2058 * @parent: parent dentry
2059 * @name: qstr of name we wish to find
2060 * @seqp: returns d_seq value at the point where the dentry was found
2061 * Returns: dentry, or NULL
2063 * __d_lookup_rcu is the dcache lookup function for rcu-walk name
2064 * resolution (store-free path walking) design described in
2065 * Documentation/filesystems/path-lookup.txt.
2067 * This is not to be used outside core vfs.
2069 * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock
2070 * held, and rcu_read_lock held. The returned dentry must not be stored into
2071 * without taking d_lock and checking d_seq sequence count against @seq
2074 * A refcount may be taken on the found dentry with the d_rcu_to_refcount
2077 * Alternatively, __d_lookup_rcu may be called again to look up the child of
2078 * the returned dentry, so long as its parent's seqlock is checked after the
2079 * child is looked up. Thus, an interlocking stepping of sequence lock checks
2080 * is formed, giving integrity down the path walk.
2082 * NOTE! The caller *has* to check the resulting dentry against the sequence
2083 * number we've returned before using any of the resulting dentry state!
2085 struct dentry *__d_lookup_rcu(const struct dentry *parent,
2086 const struct qstr *name,
2089 u64 hashlen = name->hash_len;
2090 const unsigned char *str = name->name;
2091 struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen));
2092 struct hlist_bl_node *node;
2093 struct dentry *dentry;
2096 * Note: There is significant duplication with __d_lookup_rcu which is
2097 * required to prevent single threaded performance regressions
2098 * especially on architectures where smp_rmb (in seqcounts) are costly.
2099 * Keep the two functions in sync.
2103 * The hash list is protected using RCU.
2105 * Carefully use d_seq when comparing a candidate dentry, to avoid
2106 * races with d_move().
2108 * It is possible that concurrent renames can mess up our list
2109 * walk here and result in missing our dentry, resulting in the
2110 * false-negative result. d_lookup() protects against concurrent
2111 * renames using rename_lock seqlock.
2113 * See Documentation/filesystems/path-lookup.txt for more details.
2115 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
2120 * The dentry sequence count protects us from concurrent
2121 * renames, and thus protects parent and name fields.
2123 * The caller must perform a seqcount check in order
2124 * to do anything useful with the returned dentry.
2126 * NOTE! We do a "raw" seqcount_begin here. That means that
2127 * we don't wait for the sequence count to stabilize if it
2128 * is in the middle of a sequence change. If we do the slow
2129 * dentry compare, we will do seqretries until it is stable,
2130 * and if we end up with a successful lookup, we actually
2131 * want to exit RCU lookup anyway.
2133 * Note that raw_seqcount_begin still *does* smp_rmb(), so
2134 * we are still guaranteed NUL-termination of ->d_name.name.
2136 seq = raw_seqcount_begin(&dentry->d_seq);
2137 if (dentry->d_parent != parent)
2139 if (d_unhashed(dentry))
2142 if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
2145 if (dentry->d_name.hash != hashlen_hash(hashlen))
2147 tlen = dentry->d_name.len;
2148 tname = dentry->d_name.name;
2149 /* we want a consistent (name,len) pair */
2150 if (read_seqcount_retry(&dentry->d_seq, seq)) {
2154 if (parent->d_op->d_compare(parent, dentry,
2155 tlen, tname, name) != 0)
2158 if (dentry->d_name.hash_len != hashlen)
2160 if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0)
2170 * d_lookup - search for a dentry
2171 * @parent: parent dentry
2172 * @name: qstr of name we wish to find
2173 * Returns: dentry, or NULL
2175 * d_lookup searches the children of the parent dentry for the name in
2176 * question. If the dentry is found its reference count is incremented and the
2177 * dentry is returned. The caller must use dput to free the entry when it has
2178 * finished using it. %NULL is returned if the dentry does not exist.
2180 struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name)
2182 struct dentry *dentry;
2186 seq = read_seqbegin(&rename_lock);
2187 dentry = __d_lookup(parent, name);
2190 } while (read_seqretry(&rename_lock, seq));
2193 EXPORT_SYMBOL(d_lookup);
2196 * __d_lookup - search for a dentry (racy)
2197 * @parent: parent dentry
2198 * @name: qstr of name we wish to find
2199 * Returns: dentry, or NULL
2201 * __d_lookup is like d_lookup, however it may (rarely) return a
2202 * false-negative result due to unrelated rename activity.
2204 * __d_lookup is slightly faster by avoiding rename_lock read seqlock,
2205 * however it must be used carefully, eg. with a following d_lookup in
2206 * the case of failure.
2208 * __d_lookup callers must be commented.
2210 struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
2212 unsigned int hash = name->hash;
2213 struct hlist_bl_head *b = d_hash(parent, hash);
2214 struct hlist_bl_node *node;
2215 struct dentry *found = NULL;
2216 struct dentry *dentry;
2219 * Note: There is significant duplication with __d_lookup_rcu which is
2220 * required to prevent single threaded performance regressions
2221 * especially on architectures where smp_rmb (in seqcounts) are costly.
2222 * Keep the two functions in sync.
2226 * The hash list is protected using RCU.
2228 * Take d_lock when comparing a candidate dentry, to avoid races
2231 * It is possible that concurrent renames can mess up our list
2232 * walk here and result in missing our dentry, resulting in the
2233 * false-negative result. d_lookup() protects against concurrent
2234 * renames using rename_lock seqlock.
2236 * See Documentation/filesystems/path-lookup.txt for more details.
2240 hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) {
2242 if (dentry->d_name.hash != hash)
2245 spin_lock(&dentry->d_lock);
2246 if (dentry->d_parent != parent)
2248 if (d_unhashed(dentry))
2251 if (!d_same_name(dentry, parent, name))
2254 dentry->d_lockref.count++;
2256 spin_unlock(&dentry->d_lock);
2259 spin_unlock(&dentry->d_lock);
2267 * d_hash_and_lookup - hash the qstr then search for a dentry
2268 * @dir: Directory to search in
2269 * @name: qstr of name we wish to find
2271 * On lookup failure NULL is returned; on bad name - ERR_PTR(-error)
2273 struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
2276 * Check for a fs-specific hash function. Note that we must
2277 * calculate the standard hash first, as the d_op->d_hash()
2278 * routine may choose to leave the hash value unchanged.
2280 name->hash = full_name_hash(name->name, name->len);
2281 if (dir->d_flags & DCACHE_OP_HASH) {
2282 int err = dir->d_op->d_hash(dir, name);
2283 if (unlikely(err < 0))
2284 return ERR_PTR(err);
2286 return d_lookup(dir, name);
2288 EXPORT_SYMBOL(d_hash_and_lookup);
2291 * When a file is deleted, we have two options:
2292 * - turn this dentry into a negative dentry
2293 * - unhash this dentry and free it.
2295 * Usually, we want to just turn this into
2296 * a negative dentry, but if anybody else is
2297 * currently using the dentry or the inode
2298 * we can't do that and we fall back on removing
2299 * it from the hash queues and waiting for
2300 * it to be deleted later when it has no users
2304 * d_delete - delete a dentry
2305 * @dentry: The dentry to delete
2307 * Turn the dentry into a negative dentry if possible, otherwise
2308 * remove it from the hash queues so it can be deleted later
2311 void d_delete(struct dentry * dentry)
2313 struct inode *inode;
2316 * Are we the only user?
2319 spin_lock(&dentry->d_lock);
2320 inode = dentry->d_inode;
2321 isdir = S_ISDIR(inode->i_mode);
2322 if (dentry->d_lockref.count == 1) {
2323 if (!spin_trylock(&inode->i_lock)) {
2324 spin_unlock(&dentry->d_lock);
2328 dentry->d_flags &= ~DCACHE_CANT_MOUNT;
2329 dentry_unlink_inode(dentry);
2330 fsnotify_nameremove(dentry, isdir);
2334 if (!d_unhashed(dentry))
2337 spin_unlock(&dentry->d_lock);
2339 fsnotify_nameremove(dentry, isdir);
2341 EXPORT_SYMBOL(d_delete);
2343 static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
2345 BUG_ON(!d_unhashed(entry));
2347 hlist_bl_add_head_rcu(&entry->d_hash, b);
2351 static void _d_rehash(struct dentry * entry)
2353 __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
2357 * d_rehash - add an entry back to the hash
2358 * @entry: dentry to add to the hash
2360 * Adds a dentry to the hash according to its name.
2363 void d_rehash(struct dentry * entry)
2365 spin_lock(&entry->d_lock);
2367 spin_unlock(&entry->d_lock);
2369 EXPORT_SYMBOL(d_rehash);
2371 static inline unsigned start_dir_add(struct inode *dir)
2375 unsigned n = dir->i_dir_seq;
2376 if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
2382 static inline void end_dir_add(struct inode *dir, unsigned n)
2384 smp_store_release(&dir->i_dir_seq, n + 2);
2387 static void d_wait_lookup(struct dentry *dentry)
2389 if (d_in_lookup(dentry)) {
2390 DECLARE_WAITQUEUE(wait, current);
2391 add_wait_queue(dentry->d_wait, &wait);
2393 set_current_state(TASK_UNINTERRUPTIBLE);
2394 spin_unlock(&dentry->d_lock);
2396 spin_lock(&dentry->d_lock);
2397 } while (d_in_lookup(dentry));
2401 struct dentry *d_alloc_parallel(struct dentry *parent,
2402 const struct qstr *name,
2403 wait_queue_head_t *wq)
2405 unsigned int hash = name->hash;
2406 struct hlist_bl_head *b = in_lookup_hash(parent, hash);
2407 struct hlist_bl_node *node;
2408 struct dentry *new = d_alloc(parent, name);
2409 struct dentry *dentry;
2410 unsigned seq, r_seq, d_seq;
2413 return ERR_PTR(-ENOMEM);
2417 seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1;
2418 r_seq = read_seqbegin(&rename_lock);
2419 dentry = __d_lookup_rcu(parent, name, &d_seq);
2420 if (unlikely(dentry)) {
2421 if (!lockref_get_not_dead(&dentry->d_lockref)) {
2425 if (read_seqcount_retry(&dentry->d_seq, d_seq)) {
2434 if (unlikely(read_seqretry(&rename_lock, r_seq))) {
2439 if (unlikely(parent->d_inode->i_dir_seq != seq)) {
2445 * No changes for the parent since the beginning of d_lookup().
2446 * Since all removals from the chain happen with hlist_bl_lock(),
2447 * any potential in-lookup matches are going to stay here until
2448 * we unlock the chain. All fields are stable in everything
2451 hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) {
2452 if (dentry->d_name.hash != hash)
2454 if (dentry->d_parent != parent)
2456 if (!d_same_name(dentry, parent, name))
2459 /* now we can try to grab a reference */
2460 if (!lockref_get_not_dead(&dentry->d_lockref)) {
2467 * somebody is likely to be still doing lookup for it;
2468 * wait for them to finish
2470 spin_lock(&dentry->d_lock);
2471 d_wait_lookup(dentry);
2473 * it's not in-lookup anymore; in principle we should repeat
2474 * everything from dcache lookup, but it's likely to be what
2475 * d_lookup() would've found anyway. If it is, just return it;
2476 * otherwise we really have to repeat the whole thing.
2478 if (unlikely(dentry->d_name.hash != hash))
2480 if (unlikely(dentry->d_parent != parent))
2482 if (unlikely(d_unhashed(dentry)))
2484 if (unlikely(!d_same_name(dentry, parent, name)))
2486 /* OK, it *is* a hashed match; return it */
2487 spin_unlock(&dentry->d_lock);
2492 /* we can't take ->d_lock here; it's OK, though. */
2493 new->d_flags |= DCACHE_PAR_LOOKUP;
2495 hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b);
2499 spin_unlock(&dentry->d_lock);
2503 EXPORT_SYMBOL(d_alloc_parallel);
2505 void __d_lookup_done(struct dentry *dentry)
2507 struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent,
2508 dentry->d_name.hash);
2510 dentry->d_flags &= ~DCACHE_PAR_LOOKUP;
2511 __hlist_bl_del(&dentry->d_u.d_in_lookup_hash);
2512 wake_up_all(dentry->d_wait);
2513 dentry->d_wait = NULL;
2515 INIT_HLIST_NODE(&dentry->d_u.d_alias);
2516 INIT_LIST_HEAD(&dentry->d_lru);
2518 EXPORT_SYMBOL(__d_lookup_done);
2520 /* inode->i_lock held if inode is non-NULL */
2522 static inline void __d_add(struct dentry *dentry, struct inode *inode)
2524 struct inode *dir = NULL;
2526 spin_lock(&dentry->d_lock);
2527 if (unlikely(d_in_lookup(dentry))) {
2528 dir = dentry->d_parent->d_inode;
2529 n = start_dir_add(dir);
2530 __d_lookup_done(dentry);
2533 unsigned add_flags = d_flags_for_inode(inode);
2534 hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
2535 raw_write_seqcount_begin(&dentry->d_seq);
2536 __d_set_inode_and_type(dentry, inode, add_flags);
2537 raw_write_seqcount_end(&dentry->d_seq);
2538 fsnotify_update_flags(dentry);
2542 end_dir_add(dir, n);
2543 spin_unlock(&dentry->d_lock);
2545 spin_unlock(&inode->i_lock);
2549 * d_add - add dentry to hash queues
2550 * @entry: dentry to add
2551 * @inode: The inode to attach to this dentry
2553 * This adds the entry to the hash queues and initializes @inode.
2554 * The entry was actually filled in earlier during d_alloc().
2557 void d_add(struct dentry *entry, struct inode *inode)
2560 security_d_instantiate(entry, inode);
2561 spin_lock(&inode->i_lock);
2563 __d_add(entry, inode);
2565 EXPORT_SYMBOL(d_add);
2568 * d_exact_alias - find and hash an exact unhashed alias
2569 * @entry: dentry to add
2570 * @inode: The inode to go with this dentry
2572 * If an unhashed dentry with the same name/parent and desired
2573 * inode already exists, hash and return it. Otherwise, return
2576 * Parent directory should be locked.
2578 struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode)
2580 struct dentry *alias;
2581 unsigned int hash = entry->d_name.hash;
2583 spin_lock(&inode->i_lock);
2584 hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
2586 * Don't need alias->d_lock here, because aliases with
2587 * d_parent == entry->d_parent are not subject to name or
2588 * parent changes, because the parent inode i_mutex is held.
2590 if (alias->d_name.hash != hash)
2592 if (alias->d_parent != entry->d_parent)
2594 if (!d_same_name(alias, entry->d_parent, &entry->d_name))
2596 spin_lock(&alias->d_lock);
2597 if (!d_unhashed(alias)) {
2598 spin_unlock(&alias->d_lock);
2601 __dget_dlock(alias);
2603 spin_unlock(&alias->d_lock);
2605 spin_unlock(&inode->i_lock);
2608 spin_unlock(&inode->i_lock);
2611 EXPORT_SYMBOL(d_exact_alias);
2614 * dentry_update_name_case - update case insensitive dentry with a new name
2615 * @dentry: dentry to be updated
2618 * Update a case insensitive dentry with new case of name.
2620 * dentry must have been returned by d_lookup with name @name. Old and new
2621 * name lengths must match (ie. no d_compare which allows mismatched name
2624 * Parent inode i_mutex must be held over d_lookup and into this call (to
2625 * keep renames and concurrent inserts, and readdir(2) away).
2627 void dentry_update_name_case(struct dentry *dentry, struct qstr *name)
2629 BUG_ON(!inode_is_locked(dentry->d_parent->d_inode));
2630 BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */
2632 spin_lock(&dentry->d_lock);
2633 write_seqcount_begin(&dentry->d_seq);
2634 memcpy((unsigned char *)dentry->d_name.name, name->name, name->len);
2635 write_seqcount_end(&dentry->d_seq);
2636 spin_unlock(&dentry->d_lock);
2638 EXPORT_SYMBOL(dentry_update_name_case);
2640 static void swap_names(struct dentry *dentry, struct dentry *target)
2642 if (unlikely(dname_external(target))) {
2643 if (unlikely(dname_external(dentry))) {
2645 * Both external: swap the pointers
2647 swap(target->d_name.name, dentry->d_name.name);
2650 * dentry:internal, target:external. Steal target's
2651 * storage and make target internal.
2653 memcpy(target->d_iname, dentry->d_name.name,
2654 dentry->d_name.len + 1);
2655 dentry->d_name.name = target->d_name.name;
2656 target->d_name.name = target->d_iname;
2659 if (unlikely(dname_external(dentry))) {
2661 * dentry:external, target:internal. Give dentry's
2662 * storage to target and make dentry internal
2664 memcpy(dentry->d_iname, target->d_name.name,
2665 target->d_name.len + 1);
2666 target->d_name.name = dentry->d_name.name;
2667 dentry->d_name.name = dentry->d_iname;
2670 * Both are internal.
2673 BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
2674 kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN);
2675 kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN);
2676 for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) {
2677 swap(((long *) &dentry->d_iname)[i],
2678 ((long *) &target->d_iname)[i]);
2682 swap(dentry->d_name.hash_len, target->d_name.hash_len);
2685 static void copy_name(struct dentry *dentry, struct dentry *target)
2687 struct external_name *old_name = NULL;
2688 if (unlikely(dname_external(dentry)))
2689 old_name = external_name(dentry);
2690 if (unlikely(dname_external(target))) {
2691 atomic_inc(&external_name(target)->u.count);
2692 dentry->d_name = target->d_name;
2694 memcpy(dentry->d_iname, target->d_name.name,
2695 target->d_name.len + 1);
2696 dentry->d_name.name = dentry->d_iname;
2697 dentry->d_name.hash_len = target->d_name.hash_len;
2699 if (old_name && likely(atomic_dec_and_test(&old_name->u.count)))
2700 kfree_rcu(old_name, u.head);
2703 static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target)
2706 * XXXX: do we really need to take target->d_lock?
2708 if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent)
2709 spin_lock(&target->d_parent->d_lock);
2711 if (d_ancestor(dentry->d_parent, target->d_parent)) {
2712 spin_lock(&dentry->d_parent->d_lock);
2713 spin_lock_nested(&target->d_parent->d_lock,
2714 DENTRY_D_LOCK_NESTED);
2716 spin_lock(&target->d_parent->d_lock);
2717 spin_lock_nested(&dentry->d_parent->d_lock,
2718 DENTRY_D_LOCK_NESTED);
2721 if (target < dentry) {
2722 spin_lock_nested(&target->d_lock, 2);
2723 spin_lock_nested(&dentry->d_lock, 3);
2725 spin_lock_nested(&dentry->d_lock, 2);
2726 spin_lock_nested(&target->d_lock, 3);
2730 static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target)
2732 if (target->d_parent != dentry->d_parent)
2733 spin_unlock(&dentry->d_parent->d_lock);
2734 if (target->d_parent != target)
2735 spin_unlock(&target->d_parent->d_lock);
2736 spin_unlock(&target->d_lock);
2737 spin_unlock(&dentry->d_lock);
2741 * When switching names, the actual string doesn't strictly have to
2742 * be preserved in the target - because we're dropping the target
2743 * anyway. As such, we can just do a simple memcpy() to copy over
2744 * the new name before we switch, unless we are going to rehash
2745 * it. Note that if we *do* unhash the target, we are not allowed
2746 * to rehash it without giving it a new name/hash key - whether
2747 * we swap or overwrite the names here, resulting name won't match
2748 * the reality in filesystem; it's only there for d_path() purposes.
2749 * Note that all of this is happening under rename_lock, so the
2750 * any hash lookup seeing it in the middle of manipulations will
2751 * be discarded anyway. So we do not care what happens to the hash
2755 * __d_move - move a dentry
2756 * @dentry: entry to move
2757 * @target: new dentry
2758 * @exchange: exchange the two dentries
2760 * Update the dcache to reflect the move of a file name. Negative
2761 * dcache entries should not be moved in this way. Caller must hold
2762 * rename_lock, the i_mutex of the source and target directories,
2763 * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
2765 static void __d_move(struct dentry *dentry, struct dentry *target,
2768 struct inode *dir = NULL;
2770 if (!dentry->d_inode)
2771 printk(KERN_WARNING "VFS: moving negative dcache entry\n");
2773 BUG_ON(d_ancestor(dentry, target));
2774 BUG_ON(d_ancestor(target, dentry));
2776 dentry_lock_for_move(dentry, target);
2777 if (unlikely(d_in_lookup(target))) {
2778 dir = target->d_parent->d_inode;
2779 n = start_dir_add(dir);
2780 __d_lookup_done(target);
2783 write_seqcount_begin(&dentry->d_seq);
2784 write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED);
2786 /* __d_drop does write_seqcount_barrier, but they're OK to nest. */
2789 * Move the dentry to the target hash queue. Don't bother checking
2790 * for the same hash queue because of how unlikely it is.
2793 __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
2796 * Unhash the target (d_delete() is not usable here). If exchanging
2797 * the two dentries, then rehash onto the other's hash queue.
2802 d_hash(dentry->d_parent, dentry->d_name.hash));
2805 /* Switch the names.. */
2807 swap_names(dentry, target);
2809 copy_name(dentry, target);
2811 /* ... and switch them in the tree */
2812 if (IS_ROOT(dentry)) {
2813 /* splicing a tree */
2814 dentry->d_flags |= DCACHE_RCUACCESS;
2815 dentry->d_parent = target->d_parent;
2816 target->d_parent = target;
2817 list_del_init(&target->d_child);
2818 list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
2820 /* swapping two dentries */
2821 swap(dentry->d_parent, target->d_parent);
2822 list_move(&target->d_child, &target->d_parent->d_subdirs);
2823 list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
2825 fsnotify_update_flags(target);
2826 fsnotify_update_flags(dentry);
2829 write_seqcount_end(&target->d_seq);
2830 write_seqcount_end(&dentry->d_seq);
2833 end_dir_add(dir, n);
2834 dentry_unlock_for_move(dentry, target);
2838 * d_move - move a dentry
2839 * @dentry: entry to move
2840 * @target: new dentry
2842 * Update the dcache to reflect the move of a file name. Negative
2843 * dcache entries should not be moved in this way. See the locking
2844 * requirements for __d_move.
2846 void d_move(struct dentry *dentry, struct dentry *target)
2848 write_seqlock(&rename_lock);
2849 __d_move(dentry, target, false);
2850 write_sequnlock(&rename_lock);
2852 EXPORT_SYMBOL(d_move);
2855 * d_exchange - exchange two dentries
2856 * @dentry1: first dentry
2857 * @dentry2: second dentry
2859 void d_exchange(struct dentry *dentry1, struct dentry *dentry2)
2861 write_seqlock(&rename_lock);
2863 WARN_ON(!dentry1->d_inode);
2864 WARN_ON(!dentry2->d_inode);
2865 WARN_ON(IS_ROOT(dentry1));
2866 WARN_ON(IS_ROOT(dentry2));
2868 __d_move(dentry1, dentry2, true);
2870 write_sequnlock(&rename_lock);
2874 * d_ancestor - search for an ancestor
2875 * @p1: ancestor dentry
2878 * Returns the ancestor dentry of p2 which is a child of p1, if p1 is
2879 * an ancestor of p2, else NULL.
2881 struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
2885 for (p = p2; !IS_ROOT(p); p = p->d_parent) {
2886 if (p->d_parent == p1)
2893 * This helper attempts to cope with remotely renamed directories
2895 * It assumes that the caller is already holding
2896 * dentry->d_parent->d_inode->i_mutex, and rename_lock
2898 * Note: If ever the locking in lock_rename() changes, then please
2899 * remember to update this too...
2901 static int __d_unalias(struct inode *inode,
2902 struct dentry *dentry, struct dentry *alias)
2904 struct mutex *m1 = NULL;
2905 struct rw_semaphore *m2 = NULL;
2908 /* If alias and dentry share a parent, then no extra locks required */
2909 if (alias->d_parent == dentry->d_parent)
2912 /* See lock_rename() */
2913 if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
2915 m1 = &dentry->d_sb->s_vfs_rename_mutex;
2916 if (!inode_trylock_shared(alias->d_parent->d_inode))
2918 m2 = &alias->d_parent->d_inode->i_rwsem;
2920 __d_move(alias, dentry, false);
2931 * d_splice_alias - splice a disconnected dentry into the tree if one exists
2932 * @inode: the inode which may have a disconnected dentry
2933 * @dentry: a negative dentry which we want to point to the inode.
2935 * If inode is a directory and has an IS_ROOT alias, then d_move that in
2936 * place of the given dentry and return it, else simply d_add the inode
2937 * to the dentry and return NULL.
2939 * If a non-IS_ROOT directory is found, the filesystem is corrupt, and
2940 * we should error out: directories can't have multiple aliases.
2942 * This is needed in the lookup routine of any filesystem that is exportable
2943 * (via knfsd) so that we can build dcache paths to directories effectively.
2945 * If a dentry was found and moved, then it is returned. Otherwise NULL
2946 * is returned. This matches the expected return value of ->lookup.
2948 * Cluster filesystems may call this function with a negative, hashed dentry.
2949 * In that case, we know that the inode will be a regular file, and also this
2950 * will only occur during atomic_open. So we need to check for the dentry
2951 * being already hashed only in the final case.
2953 struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
2956 return ERR_CAST(inode);
2958 BUG_ON(!d_unhashed(dentry));
2963 security_d_instantiate(dentry, inode);
2964 spin_lock(&inode->i_lock);
2965 if (S_ISDIR(inode->i_mode)) {
2966 struct dentry *new = __d_find_any_alias(inode);
2967 if (unlikely(new)) {
2968 /* The reference to new ensures it remains an alias */
2969 spin_unlock(&inode->i_lock);
2970 write_seqlock(&rename_lock);
2971 if (unlikely(d_ancestor(new, dentry))) {
2972 write_sequnlock(&rename_lock);
2974 new = ERR_PTR(-ELOOP);
2975 pr_warn_ratelimited(
2976 "VFS: Lookup of '%s' in %s %s"
2977 " would have caused loop\n",
2978 dentry->d_name.name,
2979 inode->i_sb->s_type->name,
2981 } else if (!IS_ROOT(new)) {
2982 int err = __d_unalias(inode, dentry, new);
2983 write_sequnlock(&rename_lock);
2989 __d_move(new, dentry, false);
2990 write_sequnlock(&rename_lock);
2997 __d_add(dentry, inode);
3000 EXPORT_SYMBOL(d_splice_alias);
3002 static int prepend(char **buffer, int *buflen, const char *str, int namelen)
3006 return -ENAMETOOLONG;
3008 memcpy(*buffer, str, namelen);
3013 * prepend_name - prepend a pathname in front of current buffer pointer
3014 * @buffer: buffer pointer
3015 * @buflen: allocated length of the buffer
3016 * @name: name string and length qstr structure
3018 * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to
3019 * make sure that either the old or the new name pointer and length are
3020 * fetched. However, there may be mismatch between length and pointer.
3021 * The length cannot be trusted, we need to copy it byte-by-byte until
3022 * the length is reached or a null byte is found. It also prepends "/" at
3023 * the beginning of the name. The sequence number check at the caller will
3024 * retry it again when a d_move() does happen. So any garbage in the buffer
3025 * due to mismatched pointer and length will be discarded.
3027 * Data dependency barrier is needed to make sure that we see that terminating
3028 * NUL. Alpha strikes again, film at 11...
3030 static int prepend_name(char **buffer, int *buflen, struct qstr *name)
3032 const char *dname = ACCESS_ONCE(name->name);
3033 u32 dlen = ACCESS_ONCE(name->len);
3036 smp_read_barrier_depends();
3038 *buflen -= dlen + 1;
3040 return -ENAMETOOLONG;
3041 p = *buffer -= dlen + 1;
3053 * prepend_path - Prepend path string to a buffer
3054 * @path: the dentry/vfsmount to report
3055 * @root: root vfsmnt/dentry
3056 * @buffer: pointer to the end of the buffer
3057 * @buflen: pointer to buffer length
3059 * The function will first try to write out the pathname without taking any
3060 * lock other than the RCU read lock to make sure that dentries won't go away.
3061 * It only checks the sequence number of the global rename_lock as any change
3062 * in the dentry's d_seq will be preceded by changes in the rename_lock
3063 * sequence number. If the sequence number had been changed, it will restart
3064 * the whole pathname back-tracing sequence again by taking the rename_lock.
3065 * In this case, there is no need to take the RCU read lock as the recursive
3066 * parent pointer references will keep the dentry chain alive as long as no
3067 * rename operation is performed.
3069 static int prepend_path(const struct path *path,
3070 const struct path *root,
3071 char **buffer, int *buflen)
3073 struct dentry *dentry;
3074 struct vfsmount *vfsmnt;
3077 unsigned seq, m_seq = 0;
3083 read_seqbegin_or_lock(&mount_lock, &m_seq);
3090 dentry = path->dentry;
3092 mnt = real_mount(vfsmnt);
3093 read_seqbegin_or_lock(&rename_lock, &seq);
3094 while (dentry != root->dentry || vfsmnt != root->mnt) {
3095 struct dentry * parent;
3097 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
3098 struct mount *parent = ACCESS_ONCE(mnt->mnt_parent);
3100 if (dentry != vfsmnt->mnt_root) {
3107 if (mnt != parent) {
3108 dentry = ACCESS_ONCE(mnt->mnt_mountpoint);
3114 error = is_mounted(vfsmnt) ? 1 : 2;
3117 parent = dentry->d_parent;
3119 error = prepend_name(&bptr, &blen, &dentry->d_name);
3127 if (need_seqretry(&rename_lock, seq)) {
3131 done_seqretry(&rename_lock, seq);
3135 if (need_seqretry(&mount_lock, m_seq)) {
3139 done_seqretry(&mount_lock, m_seq);
3141 if (error >= 0 && bptr == *buffer) {
3143 error = -ENAMETOOLONG;
3153 * __d_path - return the path of a dentry
3154 * @path: the dentry/vfsmount to report
3155 * @root: root vfsmnt/dentry
3156 * @buf: buffer to return value in
3157 * @buflen: buffer length
3159 * Convert a dentry into an ASCII path name.
3161 * Returns a pointer into the buffer or an error code if the
3162 * path was too long.
3164 * "buflen" should be positive.
3166 * If the path is not reachable from the supplied root, return %NULL.
3168 char *__d_path(const struct path *path,
3169 const struct path *root,
3170 char *buf, int buflen)
3172 char *res = buf + buflen;
3175 prepend(&res, &buflen, "\0", 1);
3176 error = prepend_path(path, root, &res, &buflen);
3179 return ERR_PTR(error);
3185 char *d_absolute_path(const struct path *path,
3186 char *buf, int buflen)
3188 struct path root = {};
3189 char *res = buf + buflen;
3192 prepend(&res, &buflen, "\0", 1);
3193 error = prepend_path(path, &root, &res, &buflen);
3198 return ERR_PTR(error);
3203 * same as __d_path but appends "(deleted)" for unlinked files.
3205 static int path_with_deleted(const struct path *path,
3206 const struct path *root,
3207 char **buf, int *buflen)
3209 prepend(buf, buflen, "\0", 1);
3210 if (d_unlinked(path->dentry)) {
3211 int error = prepend(buf, buflen, " (deleted)", 10);
3216 return prepend_path(path, root, buf, buflen);
3219 static int prepend_unreachable(char **buffer, int *buflen)
3221 return prepend(buffer, buflen, "(unreachable)", 13);
3224 static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
3229 seq = read_seqcount_begin(&fs->seq);
3231 } while (read_seqcount_retry(&fs->seq, seq));
3235 * d_path - return the path of a dentry
3236 * @path: path to report
3237 * @buf: buffer to return value in
3238 * @buflen: buffer length
3240 * Convert a dentry into an ASCII path name. If the entry has been deleted
3241 * the string " (deleted)" is appended. Note that this is ambiguous.
3243 * Returns a pointer into the buffer or an error code if the path was
3244 * too long. Note: Callers should use the returned pointer, not the passed
3245 * in buffer, to use the name! The implementation often starts at an offset
3246 * into the buffer, and may leave 0 bytes at the start.
3248 * "buflen" should be positive.
3250 char *d_path(const struct path *path, char *buf, int buflen)
3252 char *res = buf + buflen;
3257 * We have various synthetic filesystems that never get mounted. On
3258 * these filesystems dentries are never used for lookup purposes, and
3259 * thus don't need to be hashed. They also don't need a name until a
3260 * user wants to identify the object in /proc/pid/fd/. The little hack
3261 * below allows us to generate a name for these objects on demand:
3263 * Some pseudo inodes are mountable. When they are mounted
3264 * path->dentry == path->mnt->mnt_root. In that case don't call d_dname
3265 * and instead have d_path return the mounted path.
3267 if (path->dentry->d_op && path->dentry->d_op->d_dname &&
3268 (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root))
3269 return path->dentry->d_op->d_dname(path->dentry, buf, buflen);
3272 get_fs_root_rcu(current->fs, &root);
3273 error = path_with_deleted(path, &root, &res, &buflen);
3277 res = ERR_PTR(error);
3280 EXPORT_SYMBOL(d_path);
3283 * Helper function for dentry_operations.d_dname() members
3285 char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen,
3286 const char *fmt, ...)
3292 va_start(args, fmt);
3293 sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1;
3296 if (sz > sizeof(temp) || sz > buflen)
3297 return ERR_PTR(-ENAMETOOLONG);
3299 buffer += buflen - sz;
3300 return memcpy(buffer, temp, sz);
3303 char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
3305 char *end = buffer + buflen;
3306 /* these dentries are never renamed, so d_lock is not needed */
3307 if (prepend(&end, &buflen, " (deleted)", 11) ||
3308 prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) ||
3309 prepend(&end, &buflen, "/", 1))
3310 end = ERR_PTR(-ENAMETOOLONG);
3313 EXPORT_SYMBOL(simple_dname);
3316 * Write full pathname from the root of the filesystem into the buffer.
3318 static char *__dentry_path(struct dentry *d, char *buf, int buflen)
3320 struct dentry *dentry;
3333 prepend(&end, &len, "\0", 1);
3337 read_seqbegin_or_lock(&rename_lock, &seq);
3338 while (!IS_ROOT(dentry)) {
3339 struct dentry *parent = dentry->d_parent;
3342 error = prepend_name(&end, &len, &dentry->d_name);
3351 if (need_seqretry(&rename_lock, seq)) {
3355 done_seqretry(&rename_lock, seq);
3360 return ERR_PTR(-ENAMETOOLONG);
3363 char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen)
3365 return __dentry_path(dentry, buf, buflen);
3367 EXPORT_SYMBOL(dentry_path_raw);
3369 char *dentry_path(struct dentry *dentry, char *buf, int buflen)
3374 if (d_unlinked(dentry)) {
3376 if (prepend(&p, &buflen, "//deleted", 10) != 0)
3380 retval = __dentry_path(dentry, buf, buflen);
3381 if (!IS_ERR(retval) && p)
3382 *p = '/'; /* restore '/' overriden with '\0' */
3385 return ERR_PTR(-ENAMETOOLONG);
3388 static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root,
3394 seq = read_seqcount_begin(&fs->seq);
3397 } while (read_seqcount_retry(&fs->seq, seq));
3401 * NOTE! The user-level library version returns a
3402 * character pointer. The kernel system call just
3403 * returns the length of the buffer filled (which
3404 * includes the ending '\0' character), or a negative
3405 * error value. So libc would do something like
3407 * char *getcwd(char * buf, size_t size)
3411 * retval = sys_getcwd(buf, size);
3418 SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size)
3421 struct path pwd, root;
3422 char *page = __getname();
3428 get_fs_root_and_pwd_rcu(current->fs, &root, &pwd);
3431 if (!d_unlinked(pwd.dentry)) {
3433 char *cwd = page + PATH_MAX;
3434 int buflen = PATH_MAX;
3436 prepend(&cwd, &buflen, "\0", 1);
3437 error = prepend_path(&pwd, &root, &cwd, &buflen);
3443 /* Unreachable from current root */
3445 error = prepend_unreachable(&cwd, &buflen);
3451 len = PATH_MAX + page - cwd;
3454 if (copy_to_user(buf, cwd, len))
3467 * Test whether new_dentry is a subdirectory of old_dentry.
3469 * Trivially implemented using the dcache structure
3473 * is_subdir - is new dentry a subdirectory of old_dentry
3474 * @new_dentry: new dentry
3475 * @old_dentry: old dentry
3477 * Returns true if new_dentry is a subdirectory of the parent (at any depth).
3478 * Returns false otherwise.
3479 * Caller must ensure that "new_dentry" is pinned before calling is_subdir()
3482 bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
3487 if (new_dentry == old_dentry)
3491 /* for restarting inner loop in case of seq retry */
3492 seq = read_seqbegin(&rename_lock);
3494 * Need rcu_readlock to protect against the d_parent trashing
3498 if (d_ancestor(old_dentry, new_dentry))
3503 } while (read_seqretry(&rename_lock, seq));
3508 static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
3510 struct dentry *root = data;
3511 if (dentry != root) {
3512 if (d_unhashed(dentry) || !dentry->d_inode)
3515 if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
3516 dentry->d_flags |= DCACHE_GENOCIDE;
3517 dentry->d_lockref.count--;
3520 return D_WALK_CONTINUE;
3523 void d_genocide(struct dentry *parent)
3525 d_walk(parent, parent, d_genocide_kill, NULL);
3528 void d_tmpfile(struct dentry *dentry, struct inode *inode)
3530 inode_dec_link_count(inode);
3531 BUG_ON(dentry->d_name.name != dentry->d_iname ||
3532 !hlist_unhashed(&dentry->d_u.d_alias) ||
3533 !d_unlinked(dentry));
3534 spin_lock(&dentry->d_parent->d_lock);
3535 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
3536 dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
3537 (unsigned long long)inode->i_ino);
3538 spin_unlock(&dentry->d_lock);
3539 spin_unlock(&dentry->d_parent->d_lock);
3540 d_instantiate(dentry, inode);
3542 EXPORT_SYMBOL(d_tmpfile);
3544 static __initdata unsigned long dhash_entries;
3545 static int __init set_dhash_entries(char *str)
3549 dhash_entries = simple_strtoul(str, &str, 0);
3552 __setup("dhash_entries=", set_dhash_entries);
3554 static void __init dcache_init_early(void)
3558 /* If hashes are distributed across NUMA nodes, defer
3559 * hash allocation until vmalloc space is available.
3565 alloc_large_system_hash("Dentry cache",
3566 sizeof(struct hlist_bl_head),
3575 for (loop = 0; loop < (1U << d_hash_shift); loop++)
3576 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
3579 static void __init dcache_init(void)
3584 * A constructor could be added for stable state like the lists,
3585 * but it is probably not worth it because of the cache nature
3588 dentry_cache = KMEM_CACHE(dentry,
3589 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT);
3591 /* Hash may have been set up in dcache_init_early */
3596 alloc_large_system_hash("Dentry cache",
3597 sizeof(struct hlist_bl_head),
3606 for (loop = 0; loop < (1U << d_hash_shift); loop++)
3607 INIT_HLIST_BL_HEAD(dentry_hashtable + loop);
3610 /* SLAB cache for __getname() consumers */
3611 struct kmem_cache *names_cachep __read_mostly;
3612 EXPORT_SYMBOL(names_cachep);
3614 EXPORT_SYMBOL(d_genocide);
3616 void __init vfs_caches_init_early(void)
3618 dcache_init_early();
3622 void __init vfs_caches_init(void)
3624 names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0,
3625 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
3630 files_maxfiles_init();