1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_DCACHE_H
3 #define __LINUX_DCACHE_H
4
5 #include <linux/atomic.h>
6 #include <linux/list.h>
7 #include <linux/math.h>
8 #include <linux/rculist.h>
9 #include <linux/rculist_bl.h>
10 #include <linux/spinlock.h>
11 #include <linux/seqlock.h>
12 #include <linux/cache.h>
13 #include <linux/rcupdate.h>
14 #include <linux/lockref.h>
15 #include <linux/stringhash.h>
16 #include <linux/wait.h>
17
18 struct path;
19 struct file;
20 struct vfsmount;
21
22 /*
23 * linux/include/linux/dcache.h
24 *
25 * Dirent cache data structures
26 *
27 * (C) Copyright 1997 Thomas Schoebel-Theuer,
28 * with heavy changes by Linus Torvalds
29 */
30
31 #define IS_ROOT(x) ((x) == (x)->d_parent)
32
33 /* The hash is always the low bits of hash_len */
34 #ifdef __LITTLE_ENDIAN
35 #define HASH_LEN_DECLARE u32 hash; u32 len
36 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
37 #else
38 #define HASH_LEN_DECLARE u32 len; u32 hash
39 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
40 #endif
41
42 /*
43 * "quick string" -- eases parameter passing, but more importantly
44 * saves "metadata" about the string (ie length and the hash).
45 *
46 * hash comes first so it snuggles against d_parent in the
47 * dentry.
48 */
49 struct qstr {
50 union {
51 struct {
52 HASH_LEN_DECLARE;
53 };
54 u64 hash_len;
55 };
56 const unsigned char *name;
57 };
58
59 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
60 #define QSTR_LEN(n,l) (struct qstr)QSTR_INIT(n,l)
61 #define QSTR(n) QSTR_LEN(n, strlen(n))
62
63 extern const struct qstr empty_name;
64 extern const struct qstr slash_name;
65 extern const struct qstr dotdot_name;
66
67 /*
68 * Try to keep struct dentry aligned on 64 byte cachelines (this will
69 * give reasonable cacheline footprint with larger lines without the
70 * large memory footprint increase).
71 */
72 #ifdef CONFIG_64BIT
73 # define DNAME_INLINE_WORDS 5 /* 192 bytes */
74 #else
75 # ifdef CONFIG_SMP
76 # define DNAME_INLINE_WORDS 9 /* 128 bytes */
77 # else
78 # define DNAME_INLINE_WORDS 11 /* 128 bytes */
79 # endif
80 #endif
81
82 #define DNAME_INLINE_LEN (DNAME_INLINE_WORDS*sizeof(unsigned long))
83
84 union shortname_store {
85 unsigned char string[DNAME_INLINE_LEN];
86 unsigned long words[DNAME_INLINE_WORDS];
87 };
88
89 #define d_lock d_lockref.lock
90 #define d_iname d_shortname.string
91
92 struct dentry {
93 /* RCU lookup touched fields */
94 unsigned int d_flags; /* protected by d_lock */
95 seqcount_spinlock_t d_seq; /* per dentry seqlock */
96 struct hlist_bl_node d_hash; /* lookup hash list */
97 struct dentry *d_parent; /* parent directory */
98 union {
99 struct qstr __d_name; /* for use ONLY in fs/dcache.c */
100 const struct qstr d_name;
101 };
102 struct inode *d_inode; /* Where the name belongs to - NULL is
103 * negative */
104 union shortname_store d_shortname;
105 /* --- cacheline 1 boundary (64 bytes) was 32 bytes ago --- */
106
107 /* Ref lookup also touches following */
108 const struct dentry_operations *d_op;
109 struct super_block *d_sb; /* The root of the dentry tree */
110 unsigned long d_time; /* used by d_revalidate */
111 void *d_fsdata; /* fs-specific data */
112 /* --- cacheline 2 boundary (128 bytes) --- */
113 struct lockref d_lockref; /* per-dentry lock and refcount
114 * keep separate from RCU lookup area if
115 * possible!
116 */
117
118 union {
119 struct list_head d_lru; /* LRU list */
120 wait_queue_head_t *d_wait; /* in-lookup ones only */
121 };
122 struct hlist_node d_sib; /* child of parent list */
123 struct hlist_head d_children; /* our children */
124 /*
125 * d_alias and d_rcu can share memory
126 */
127 union {
128 struct hlist_node d_alias; /* inode alias list */
129 struct hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */
130 struct rcu_head d_rcu;
131 } d_u;
132 };
133
134 /*
135 * dentry->d_lock spinlock nesting subclasses:
136 *
137 * 0: normal
138 * 1: nested
139 */
140 enum dentry_d_lock_class
141 {
142 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
143 DENTRY_D_LOCK_NESTED
144 };
145
146 enum d_real_type {
147 D_REAL_DATA,
148 D_REAL_METADATA,
149 };
150
151 struct dentry_operations {
152 int (*d_revalidate)(struct inode *, const struct qstr *,
153 struct dentry *, unsigned int);
154 int (*d_weak_revalidate)(struct dentry *, unsigned int);
155 int (*d_hash)(const struct dentry *, struct qstr *);
156 int (*d_compare)(const struct dentry *,
157 unsigned int, const char *, const struct qstr *);
158 int (*d_delete)(const struct dentry *);
159 int (*d_init)(struct dentry *);
160 void (*d_release)(struct dentry *);
161 void (*d_prune)(struct dentry *);
162 void (*d_iput)(struct dentry *, struct inode *);
163 char *(*d_dname)(struct dentry *, char *, int);
164 struct vfsmount *(*d_automount)(struct path *);
165 int (*d_manage)(const struct path *, bool);
166 struct dentry *(*d_real)(struct dentry *, enum d_real_type type);
167 bool (*d_unalias_trylock)(const struct dentry *);
168 void (*d_unalias_unlock)(const struct dentry *);
169 } ____cacheline_aligned;
170
171 /*
172 * Locking rules for dentry_operations callbacks are to be found in
173 * Documentation/filesystems/locking.rst. Keep it updated!
174 *
175 * FUrther descriptions are found in Documentation/filesystems/vfs.rst.
176 * Keep it updated too!
177 */
178
179 /* d_flags entries */
180 enum dentry_flags {
181 DCACHE_OP_HASH = BIT(0),
182 DCACHE_OP_COMPARE = BIT(1),
183 DCACHE_OP_REVALIDATE = BIT(2),
184 DCACHE_OP_DELETE = BIT(3),
185 DCACHE_OP_PRUNE = BIT(4),
186 /*
187 * This dentry is possibly not currently connected to the dcache tree,
188 * in which case its parent will either be itself, or will have this
189 * flag as well. nfsd will not use a dentry with this bit set, but will
190 * first endeavour to clear the bit either by discovering that it is
191 * connected, or by performing lookup operations. Any filesystem which
192 * supports nfsd_operations MUST have a lookup function which, if it
193 * finds a directory inode with a DCACHE_DISCONNECTED dentry, will
194 * d_move that dentry into place and return that dentry rather than the
195 * passed one, typically using d_splice_alias.
196 */
197 DCACHE_DISCONNECTED = BIT(5),
198 DCACHE_REFERENCED = BIT(6), /* Recently used, don't discard. */
199 DCACHE_DONTCACHE = BIT(7), /* Purge from memory on final dput() */
200 DCACHE_CANT_MOUNT = BIT(8),
201 DCACHE_GENOCIDE = BIT(9),
202 DCACHE_SHRINK_LIST = BIT(10),
203 DCACHE_OP_WEAK_REVALIDATE = BIT(11),
204 /*
205 * this dentry has been "silly renamed" and has to be deleted on the
206 * last dput()
207 */
208 DCACHE_NFSFS_RENAMED = BIT(12),
209 DCACHE_FSNOTIFY_PARENT_WATCHED = BIT(13), /* Parent inode is watched by some fsnotify listener */
210 DCACHE_DENTRY_KILLED = BIT(14),
211 DCACHE_MOUNTED = BIT(15), /* is a mountpoint */
212 DCACHE_NEED_AUTOMOUNT = BIT(16), /* handle automount on this dir */
213 DCACHE_MANAGE_TRANSIT = BIT(17), /* manage transit from this dirent */
214 DCACHE_LRU_LIST = BIT(18),
215 DCACHE_ENTRY_TYPE = (7 << 19), /* bits 19..21 are for storing type: */
216 DCACHE_MISS_TYPE = (0 << 19), /* Negative dentry */
217 DCACHE_WHITEOUT_TYPE = (1 << 19), /* Whiteout dentry (stop pathwalk) */
218 DCACHE_DIRECTORY_TYPE = (2 << 19), /* Normal directory */
219 DCACHE_AUTODIR_TYPE = (3 << 19), /* Lookupless directory (presumed automount) */
220 DCACHE_REGULAR_TYPE = (4 << 19), /* Regular file type */
221 DCACHE_SPECIAL_TYPE = (5 << 19), /* Other file type */
222 DCACHE_SYMLINK_TYPE = (6 << 19), /* Symlink */
223 DCACHE_NOKEY_NAME = BIT(22), /* Encrypted name encoded without key */
224 DCACHE_OP_REAL = BIT(23),
225 DCACHE_PAR_LOOKUP = BIT(24), /* being looked up (with parent locked shared) */
226 DCACHE_DENTRY_CURSOR = BIT(25),
227 DCACHE_NORCU = BIT(26), /* No RCU delay for freeing */
228 };
229
230 #define DCACHE_MANAGED_DENTRY \
231 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
232
233 extern seqlock_t rename_lock;
234
235 /*
236 * These are the low-level FS interfaces to the dcache..
237 */
238 extern void d_instantiate(struct dentry *, struct inode *);
239 extern void d_instantiate_new(struct dentry *, struct inode *);
240 extern void __d_drop(struct dentry *dentry);
241 extern void d_drop(struct dentry *dentry);
242 extern void d_delete(struct dentry *);
243
244 /* allocate/de-allocate */
245 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
246 extern struct dentry * d_alloc_anon(struct super_block *);
247 extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
248 wait_queue_head_t *);
249 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
250 /* weird procfs mess; *NOT* exported */
251 extern struct dentry * d_splice_alias_ops(struct inode *, struct dentry *,
252 const struct dentry_operations *);
253 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
254 extern bool d_same_name(const struct dentry *dentry, const struct dentry *parent,
255 const struct qstr *name);
256 extern struct dentry *d_find_any_alias(struct inode *inode);
257 extern struct dentry * d_obtain_alias(struct inode *);
258 extern struct dentry * d_obtain_root(struct inode *);
259 extern void shrink_dcache_sb(struct super_block *);
260 extern void shrink_dcache_parent(struct dentry *);
261 extern void d_invalidate(struct dentry *);
262
263 /* only used at mount-time */
264 extern struct dentry * d_make_root(struct inode *);
265
266 extern void d_mark_tmpfile(struct file *, struct inode *);
267 extern void d_tmpfile(struct file *, struct inode *);
268
269 extern struct dentry *d_find_alias(struct inode *);
270 extern void d_prune_aliases(struct inode *);
271
272 extern struct dentry *d_find_alias_rcu(struct inode *);
273
274 /* test whether we have any submounts in a subdir tree */
275 extern int path_has_submounts(const struct path *);
276
277 /*
278 * This adds the entry to the hash queues.
279 */
280 extern void d_rehash(struct dentry *);
281
282 extern void d_add(struct dentry *, struct inode *);
283
284 /* used for rename() and baskets */
285 extern void d_move(struct dentry *, struct dentry *);
286 extern void d_exchange(struct dentry *, struct dentry *);
287 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
288
289 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
290
d_count(const struct dentry * dentry)291 static inline unsigned d_count(const struct dentry *dentry)
292 {
293 return dentry->d_lockref.count;
294 }
295
296 ino_t d_parent_ino(struct dentry *dentry);
297
298 /*
299 * helper function for dentry_operations.d_dname() members
300 */
301 extern __printf(3, 4)
302 char *dynamic_dname(char *, int, const char *, ...);
303
304 extern char *__d_path(const struct path *, const struct path *, char *, int);
305 extern char *d_absolute_path(const struct path *, char *, int);
306 extern char *d_path(const struct path *, char *, int);
307 extern char *dentry_path_raw(const struct dentry *, char *, int);
308 extern char *dentry_path(const struct dentry *, char *, int);
309
310 /* Allocation counts.. */
311
312 /**
313 * dget_dlock - get a reference to a dentry
314 * @dentry: dentry to get a reference to
315 *
316 * Given a live dentry, increment the reference count and return the dentry.
317 * Caller must hold @dentry->d_lock. Making sure that dentry is alive is
318 * caller's resonsibility. There are many conditions sufficient to guarantee
319 * that; e.g. anything with non-negative refcount is alive, so's anything
320 * hashed, anything positive, anyone's parent, etc.
321 */
dget_dlock(struct dentry * dentry)322 static inline struct dentry *dget_dlock(struct dentry *dentry)
323 {
324 dentry->d_lockref.count++;
325 return dentry;
326 }
327
328
329 /**
330 * dget - get a reference to a dentry
331 * @dentry: dentry to get a reference to
332 *
333 * Given a dentry or %NULL pointer increment the reference count
334 * if appropriate and return the dentry. A dentry will not be
335 * destroyed when it has references. Conversely, a dentry with
336 * no references can disappear for any number of reasons, starting
337 * with memory pressure. In other words, that primitive is
338 * used to clone an existing reference; using it on something with
339 * zero refcount is a bug.
340 *
341 * NOTE: it will spin if @dentry->d_lock is held. From the deadlock
342 * avoidance point of view it is equivalent to spin_lock()/increment
343 * refcount/spin_unlock(), so calling it under @dentry->d_lock is
344 * always a bug; so's calling it under ->d_lock on any of its descendents.
345 *
346 */
dget(struct dentry * dentry)347 static inline struct dentry *dget(struct dentry *dentry)
348 {
349 if (dentry)
350 lockref_get(&dentry->d_lockref);
351 return dentry;
352 }
353
354 extern struct dentry *dget_parent(struct dentry *dentry);
355
356 /**
357 * d_unhashed - is dentry hashed
358 * @dentry: entry to check
359 *
360 * Returns true if the dentry passed is not currently hashed.
361 */
d_unhashed(const struct dentry * dentry)362 static inline int d_unhashed(const struct dentry *dentry)
363 {
364 return hlist_bl_unhashed(&dentry->d_hash);
365 }
366
d_unlinked(const struct dentry * dentry)367 static inline int d_unlinked(const struct dentry *dentry)
368 {
369 return d_unhashed(dentry) && !IS_ROOT(dentry);
370 }
371
cant_mount(const struct dentry * dentry)372 static inline int cant_mount(const struct dentry *dentry)
373 {
374 return (dentry->d_flags & DCACHE_CANT_MOUNT);
375 }
376
dont_mount(struct dentry * dentry)377 static inline void dont_mount(struct dentry *dentry)
378 {
379 spin_lock(&dentry->d_lock);
380 dentry->d_flags |= DCACHE_CANT_MOUNT;
381 spin_unlock(&dentry->d_lock);
382 }
383
384 extern void __d_lookup_unhash_wake(struct dentry *dentry);
385
d_in_lookup(const struct dentry * dentry)386 static inline int d_in_lookup(const struct dentry *dentry)
387 {
388 return dentry->d_flags & DCACHE_PAR_LOOKUP;
389 }
390
d_lookup_done(struct dentry * dentry)391 static inline void d_lookup_done(struct dentry *dentry)
392 {
393 if (unlikely(d_in_lookup(dentry)))
394 __d_lookup_unhash_wake(dentry);
395 }
396
397 extern void dput(struct dentry *);
398
d_managed(const struct dentry * dentry)399 static inline bool d_managed(const struct dentry *dentry)
400 {
401 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
402 }
403
d_mountpoint(const struct dentry * dentry)404 static inline bool d_mountpoint(const struct dentry *dentry)
405 {
406 return dentry->d_flags & DCACHE_MOUNTED;
407 }
408
409 /*
410 * Directory cache entry type accessor functions.
411 */
__d_entry_type(const struct dentry * dentry)412 static inline unsigned __d_entry_type(const struct dentry *dentry)
413 {
414 return dentry->d_flags & DCACHE_ENTRY_TYPE;
415 }
416
d_is_miss(const struct dentry * dentry)417 static inline bool d_is_miss(const struct dentry *dentry)
418 {
419 return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
420 }
421
d_is_whiteout(const struct dentry * dentry)422 static inline bool d_is_whiteout(const struct dentry *dentry)
423 {
424 return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
425 }
426
d_can_lookup(const struct dentry * dentry)427 static inline bool d_can_lookup(const struct dentry *dentry)
428 {
429 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
430 }
431
d_is_autodir(const struct dentry * dentry)432 static inline bool d_is_autodir(const struct dentry *dentry)
433 {
434 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
435 }
436
d_is_dir(const struct dentry * dentry)437 static inline bool d_is_dir(const struct dentry *dentry)
438 {
439 return d_can_lookup(dentry) || d_is_autodir(dentry);
440 }
441
d_is_symlink(const struct dentry * dentry)442 static inline bool d_is_symlink(const struct dentry *dentry)
443 {
444 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
445 }
446
d_is_reg(const struct dentry * dentry)447 static inline bool d_is_reg(const struct dentry *dentry)
448 {
449 return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
450 }
451
d_is_special(const struct dentry * dentry)452 static inline bool d_is_special(const struct dentry *dentry)
453 {
454 return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
455 }
456
d_is_file(const struct dentry * dentry)457 static inline bool d_is_file(const struct dentry *dentry)
458 {
459 return d_is_reg(dentry) || d_is_special(dentry);
460 }
461
d_is_negative(const struct dentry * dentry)462 static inline bool d_is_negative(const struct dentry *dentry)
463 {
464 // TODO: check d_is_whiteout(dentry) also.
465 return d_is_miss(dentry);
466 }
467
d_flags_negative(unsigned flags)468 static inline bool d_flags_negative(unsigned flags)
469 {
470 return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE;
471 }
472
d_is_positive(const struct dentry * dentry)473 static inline bool d_is_positive(const struct dentry *dentry)
474 {
475 return !d_is_negative(dentry);
476 }
477
478 /**
479 * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
480 * @dentry: The dentry in question
481 *
482 * Returns true if the dentry represents either an absent name or a name that
483 * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
484 * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
485 * fallthrough marker in an opaque directory.
486 *
487 * Note! (1) This should be used *only* by a filesystem to examine its own
488 * dentries. It should not be used to look at some other filesystem's
489 * dentries. (2) It should also be used in combination with d_inode() to get
490 * the inode. (3) The dentry may have something attached to ->d_lower and the
491 * type field of the flags may be set to something other than miss or whiteout.
492 */
d_really_is_negative(const struct dentry * dentry)493 static inline bool d_really_is_negative(const struct dentry *dentry)
494 {
495 return dentry->d_inode == NULL;
496 }
497
498 /**
499 * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
500 * @dentry: The dentry in question
501 *
502 * Returns true if the dentry represents a name that maps to an inode
503 * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
504 * that is represented on medium as a 0,0 chardev.
505 *
506 * Note! (1) This should be used *only* by a filesystem to examine its own
507 * dentries. It should not be used to look at some other filesystem's
508 * dentries. (2) It should also be used in combination with d_inode() to get
509 * the inode.
510 */
d_really_is_positive(const struct dentry * dentry)511 static inline bool d_really_is_positive(const struct dentry *dentry)
512 {
513 return dentry->d_inode != NULL;
514 }
515
simple_positive(const struct dentry * dentry)516 static inline int simple_positive(const struct dentry *dentry)
517 {
518 return d_really_is_positive(dentry) && !d_unhashed(dentry);
519 }
520
521 unsigned long vfs_pressure_ratio(unsigned long val);
522
523 /**
524 * d_inode - Get the actual inode of this dentry
525 * @dentry: The dentry to query
526 *
527 * This is the helper normal filesystems should use to get at their own inodes
528 * in their own dentries and ignore the layering superimposed upon them.
529 */
d_inode(const struct dentry * dentry)530 static inline struct inode *d_inode(const struct dentry *dentry)
531 {
532 return dentry->d_inode;
533 }
534
535 /**
536 * d_inode_rcu - Get the actual inode of this dentry with READ_ONCE()
537 * @dentry: The dentry to query
538 *
539 * This is the helper normal filesystems should use to get at their own inodes
540 * in their own dentries and ignore the layering superimposed upon them.
541 */
d_inode_rcu(const struct dentry * dentry)542 static inline struct inode *d_inode_rcu(const struct dentry *dentry)
543 {
544 return READ_ONCE(dentry->d_inode);
545 }
546
547 /**
548 * d_backing_inode - Get upper or lower inode we should be using
549 * @upper: The upper layer
550 *
551 * This is the helper that should be used to get at the inode that will be used
552 * if this dentry were to be opened as a file. The inode may be on the upper
553 * dentry or it may be on a lower dentry pinned by the upper.
554 *
555 * Normal filesystems should not use this to access their own inodes.
556 */
d_backing_inode(const struct dentry * upper)557 static inline struct inode *d_backing_inode(const struct dentry *upper)
558 {
559 struct inode *inode = upper->d_inode;
560
561 return inode;
562 }
563
564 /**
565 * d_real - Return the real dentry
566 * @dentry: the dentry to query
567 * @type: the type of real dentry (data or metadata)
568 *
569 * If dentry is on a union/overlay, then return the underlying, real dentry.
570 * Otherwise return the dentry itself.
571 *
572 * See also: Documentation/filesystems/vfs.rst
573 */
d_real(struct dentry * dentry,enum d_real_type type)574 static inline struct dentry *d_real(struct dentry *dentry, enum d_real_type type)
575 {
576 if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
577 return dentry->d_op->d_real(dentry, type);
578 else
579 return dentry;
580 }
581
582 /**
583 * d_real_inode - Return the real inode hosting the data
584 * @dentry: The dentry to query
585 *
586 * If dentry is on a union/overlay, then return the underlying, real inode.
587 * Otherwise return d_inode().
588 */
d_real_inode(const struct dentry * dentry)589 static inline struct inode *d_real_inode(const struct dentry *dentry)
590 {
591 /* This usage of d_real() results in const dentry */
592 return d_inode(d_real((struct dentry *) dentry, D_REAL_DATA));
593 }
594
595 struct name_snapshot {
596 struct qstr name;
597 union shortname_store inline_name;
598 };
599 void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
600 void release_dentry_name_snapshot(struct name_snapshot *);
601
d_first_child(const struct dentry * dentry)602 static inline struct dentry *d_first_child(const struct dentry *dentry)
603 {
604 return hlist_entry_safe(dentry->d_children.first, struct dentry, d_sib);
605 }
606
d_next_sibling(const struct dentry * dentry)607 static inline struct dentry *d_next_sibling(const struct dentry *dentry)
608 {
609 return hlist_entry_safe(dentry->d_sib.next, struct dentry, d_sib);
610 }
611
612 void set_default_d_op(struct super_block *, const struct dentry_operations *);
613
614 #endif /* __LINUX_DCACHE_H */
615