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 #include <linux/android_kabi.h>
18
19 struct path;
20 struct file;
21 struct vfsmount;
22
23 /*
24 * linux/include/linux/dcache.h
25 *
26 * Dirent cache data structures
27 *
28 * (C) Copyright 1997 Thomas Schoebel-Theuer,
29 * with heavy changes by Linus Torvalds
30 */
31
32 #define IS_ROOT(x) ((x) == (x)->d_parent)
33
34 /* The hash is always the low bits of hash_len */
35 #ifdef __LITTLE_ENDIAN
36 #define HASH_LEN_DECLARE u32 hash; u32 len
37 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
38 #else
39 #define HASH_LEN_DECLARE u32 len; u32 hash
40 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
41 #endif
42
43 /*
44 * "quick string" -- eases parameter passing, but more importantly
45 * saves "metadata" about the string (ie length and the hash).
46 *
47 * hash comes first so it snuggles against d_parent in the
48 * dentry.
49 */
50 struct qstr {
51 union {
52 struct {
53 HASH_LEN_DECLARE;
54 };
55 u64 hash_len;
56 };
57 const unsigned char *name;
58 };
59
60 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
61
62 extern const struct qstr empty_name;
63 extern const struct qstr slash_name;
64 extern const struct qstr dotdot_name;
65
66 /*
67 * Try to keep struct dentry aligned on 64 byte cachelines (this will
68 * give reasonable cacheline footprint with larger lines without the
69 * large memory footprint increase).
70 */
71 #ifdef CONFIG_64BIT
72 # define DNAME_INLINE_LEN 32 /* 192 bytes */
73 #else
74 # ifdef CONFIG_SMP
75 # define DNAME_INLINE_LEN 36 /* 128 bytes */
76 # else
77 # define DNAME_INLINE_LEN 40 /* 128 bytes */
78 # endif
79 #endif
80
81 #define d_lock d_lockref.lock
82
83 struct dentry {
84 /* RCU lookup touched fields */
85 unsigned int d_flags; /* protected by d_lock */
86 seqcount_spinlock_t d_seq; /* per dentry seqlock */
87 struct hlist_bl_node d_hash; /* lookup hash list */
88 struct dentry *d_parent; /* parent directory */
89 struct qstr d_name;
90 struct inode *d_inode; /* Where the name belongs to - NULL is
91 * negative */
92 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
93
94 /* Ref lookup also touches following */
95 struct lockref d_lockref; /* per-dentry lock and refcount */
96 const struct dentry_operations *d_op;
97 struct super_block *d_sb; /* The root of the dentry tree */
98 unsigned long d_time; /* used by d_revalidate */
99 void *d_fsdata; /* fs-specific data */
100
101 union {
102 struct list_head d_lru; /* LRU list */
103 wait_queue_head_t *d_wait; /* in-lookup ones only */
104 };
105 struct list_head d_child; /* child of parent list */
106 struct list_head d_subdirs; /* our children */
107 /*
108 * d_alias and d_rcu can share memory
109 */
110 union {
111 struct hlist_node d_alias; /* inode alias list */
112 struct hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */
113 struct rcu_head d_rcu;
114 } d_u;
115
116 ANDROID_KABI_RESERVE(1);
117 ANDROID_KABI_RESERVE(2);
118 } __randomize_layout;
119
120 /*
121 * dentry->d_lock spinlock nesting subclasses:
122 *
123 * 0: normal
124 * 1: nested
125 */
126 enum dentry_d_lock_class
127 {
128 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
129 DENTRY_D_LOCK_NESTED
130 };
131
132 struct dentry_operations {
133 int (*d_revalidate)(struct dentry *, unsigned int);
134 int (*d_weak_revalidate)(struct dentry *, unsigned int);
135 int (*d_hash)(const struct dentry *, struct qstr *);
136 int (*d_compare)(const struct dentry *,
137 unsigned int, const char *, const struct qstr *);
138 int (*d_delete)(const struct dentry *);
139 int (*d_init)(struct dentry *);
140 void (*d_release)(struct dentry *);
141 void (*d_prune)(struct dentry *);
142 void (*d_iput)(struct dentry *, struct inode *);
143 char *(*d_dname)(struct dentry *, char *, int);
144 struct vfsmount *(*d_automount)(struct path *);
145 int (*d_manage)(const struct path *, bool);
146 struct dentry *(*d_real)(struct dentry *, const struct inode *);
147 int (*d_canonical_path)(const struct path *, struct path *);
148
149 ANDROID_KABI_RESERVE(1);
150 ANDROID_KABI_RESERVE(2);
151 ANDROID_KABI_RESERVE(3);
152 ANDROID_KABI_RESERVE(4);
153 } ____cacheline_aligned;
154
155 /*
156 * Locking rules for dentry_operations callbacks are to be found in
157 * Documentation/filesystems/locking.rst. Keep it updated!
158 *
159 * FUrther descriptions are found in Documentation/filesystems/vfs.rst.
160 * Keep it updated too!
161 */
162
163 /* d_flags entries */
164 #define DCACHE_OP_HASH 0x00000001
165 #define DCACHE_OP_COMPARE 0x00000002
166 #define DCACHE_OP_REVALIDATE 0x00000004
167 #define DCACHE_OP_DELETE 0x00000008
168 #define DCACHE_OP_PRUNE 0x00000010
169
170 #define DCACHE_DISCONNECTED 0x00000020
171 /* This dentry is possibly not currently connected to the dcache tree, in
172 * which case its parent will either be itself, or will have this flag as
173 * well. nfsd will not use a dentry with this bit set, but will first
174 * endeavour to clear the bit either by discovering that it is connected,
175 * or by performing lookup operations. Any filesystem which supports
176 * nfsd_operations MUST have a lookup function which, if it finds a
177 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
178 * dentry into place and return that dentry rather than the passed one,
179 * typically using d_splice_alias. */
180
181 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
182
183 #define DCACHE_DONTCACHE 0x00000080 /* Purge from memory on final dput() */
184
185 #define DCACHE_CANT_MOUNT 0x00000100
186 #define DCACHE_GENOCIDE 0x00000200
187 #define DCACHE_SHRINK_LIST 0x00000400
188
189 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
190
191 #define DCACHE_NFSFS_RENAMED 0x00001000
192 /* this dentry has been "silly renamed" and has to be deleted on the last
193 * dput() */
194 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
195 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
196 /* Parent inode is watched by some fsnotify listener */
197
198 #define DCACHE_DENTRY_KILLED 0x00008000
199
200 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
201 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
202 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
203 #define DCACHE_MANAGED_DENTRY \
204 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
205
206 #define DCACHE_LRU_LIST 0x00080000
207
208 #define DCACHE_ENTRY_TYPE 0x00700000
209 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
210 #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
211 #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
212 #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
213 #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
214 #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
215 #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
216
217 #define DCACHE_MAY_FREE 0x00800000
218 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
219 #define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */
220 #define DCACHE_OP_REAL 0x04000000
221
222 #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
223 #define DCACHE_DENTRY_CURSOR 0x20000000
224 #define DCACHE_NORCU 0x40000000 /* No RCU delay for freeing */
225
226 extern seqlock_t rename_lock;
227
228 /*
229 * These are the low-level FS interfaces to the dcache..
230 */
231 extern void d_instantiate(struct dentry *, struct inode *);
232 extern void d_instantiate_new(struct dentry *, struct inode *);
233 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
234 extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
235 extern void __d_drop(struct dentry *dentry);
236 extern void d_drop(struct dentry *dentry);
237 extern void d_delete(struct dentry *);
238 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
239
240 /* allocate/de-allocate */
241 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
242 extern struct dentry * d_alloc_anon(struct super_block *);
243 extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
244 wait_queue_head_t *);
245 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
246 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
247 extern bool d_same_name(const struct dentry *dentry, const struct dentry *parent,
248 const struct qstr *name);
249 extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
250 extern struct dentry *d_find_any_alias(struct inode *inode);
251 extern struct dentry * d_obtain_alias(struct inode *);
252 extern struct dentry * d_obtain_root(struct inode *);
253 extern void shrink_dcache_sb(struct super_block *);
254 extern void shrink_dcache_parent(struct dentry *);
255 extern void shrink_dcache_for_umount(struct super_block *);
256 extern void d_invalidate(struct dentry *);
257
258 /* only used at mount-time */
259 extern struct dentry * d_make_root(struct inode *);
260
261 /* <clickety>-<click> the ramfs-type tree */
262 extern void d_genocide(struct dentry *);
263
264 extern void d_tmpfile(struct file *, struct inode *);
265
266 extern struct dentry *d_find_alias(struct inode *);
267 extern void d_prune_aliases(struct inode *);
268
269 extern struct dentry *d_find_alias_rcu(struct inode *);
270
271 /* test whether we have any submounts in a subdir tree */
272 extern int path_has_submounts(const struct path *);
273
274 /*
275 * This adds the entry to the hash queues.
276 */
277 extern void d_rehash(struct dentry *);
278
279 extern void d_add(struct dentry *, struct inode *);
280
281 /* used for rename() and baskets */
282 extern void d_move(struct dentry *, struct dentry *);
283 extern void d_exchange(struct dentry *, struct dentry *);
284 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
285
286 /* appendix may either be NULL or be used for transname suffixes */
287 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
288 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
289 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
290 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
291 const struct qstr *name, unsigned *seq);
292
d_count(const struct dentry * dentry)293 static inline unsigned d_count(const struct dentry *dentry)
294 {
295 return dentry->d_lockref.count;
296 }
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, dget_dlock - get a reference to a dentry
314 * @dentry: dentry to get a reference to
315 *
316 * Given a dentry or %NULL pointer increment the reference count
317 * if appropriate and return the dentry. A dentry will not be
318 * destroyed when it has references.
319 */
dget_dlock(struct dentry * dentry)320 static inline struct dentry *dget_dlock(struct dentry *dentry)
321 {
322 if (dentry)
323 dentry->d_lockref.count++;
324 return dentry;
325 }
326
dget(struct dentry * dentry)327 static inline struct dentry *dget(struct dentry *dentry)
328 {
329 if (dentry)
330 lockref_get(&dentry->d_lockref);
331 return dentry;
332 }
333
334 extern struct dentry *dget_parent(struct dentry *dentry);
335
336 /**
337 * d_unhashed - is dentry hashed
338 * @dentry: entry to check
339 *
340 * Returns true if the dentry passed is not currently hashed.
341 */
342
d_unhashed(const struct dentry * dentry)343 static inline int d_unhashed(const struct dentry *dentry)
344 {
345 return hlist_bl_unhashed(&dentry->d_hash);
346 }
347
d_unlinked(const struct dentry * dentry)348 static inline int d_unlinked(const struct dentry *dentry)
349 {
350 return d_unhashed(dentry) && !IS_ROOT(dentry);
351 }
352
cant_mount(const struct dentry * dentry)353 static inline int cant_mount(const struct dentry *dentry)
354 {
355 return (dentry->d_flags & DCACHE_CANT_MOUNT);
356 }
357
dont_mount(struct dentry * dentry)358 static inline void dont_mount(struct dentry *dentry)
359 {
360 spin_lock(&dentry->d_lock);
361 dentry->d_flags |= DCACHE_CANT_MOUNT;
362 spin_unlock(&dentry->d_lock);
363 }
364
365 extern void __d_lookup_unhash_wake(struct dentry *dentry);
366
d_in_lookup(const struct dentry * dentry)367 static inline int d_in_lookup(const struct dentry *dentry)
368 {
369 return dentry->d_flags & DCACHE_PAR_LOOKUP;
370 }
371
d_lookup_done(struct dentry * dentry)372 static inline void d_lookup_done(struct dentry *dentry)
373 {
374 if (unlikely(d_in_lookup(dentry)))
375 __d_lookup_unhash_wake(dentry);
376 }
377
378 extern void dput(struct dentry *);
379
d_managed(const struct dentry * dentry)380 static inline bool d_managed(const struct dentry *dentry)
381 {
382 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
383 }
384
d_mountpoint(const struct dentry * dentry)385 static inline bool d_mountpoint(const struct dentry *dentry)
386 {
387 return dentry->d_flags & DCACHE_MOUNTED;
388 }
389
390 /*
391 * Directory cache entry type accessor functions.
392 */
__d_entry_type(const struct dentry * dentry)393 static inline unsigned __d_entry_type(const struct dentry *dentry)
394 {
395 return dentry->d_flags & DCACHE_ENTRY_TYPE;
396 }
397
d_is_miss(const struct dentry * dentry)398 static inline bool d_is_miss(const struct dentry *dentry)
399 {
400 return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
401 }
402
d_is_whiteout(const struct dentry * dentry)403 static inline bool d_is_whiteout(const struct dentry *dentry)
404 {
405 return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
406 }
407
d_can_lookup(const struct dentry * dentry)408 static inline bool d_can_lookup(const struct dentry *dentry)
409 {
410 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
411 }
412
d_is_autodir(const struct dentry * dentry)413 static inline bool d_is_autodir(const struct dentry *dentry)
414 {
415 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
416 }
417
d_is_dir(const struct dentry * dentry)418 static inline bool d_is_dir(const struct dentry *dentry)
419 {
420 return d_can_lookup(dentry) || d_is_autodir(dentry);
421 }
422
d_is_symlink(const struct dentry * dentry)423 static inline bool d_is_symlink(const struct dentry *dentry)
424 {
425 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
426 }
427
d_is_reg(const struct dentry * dentry)428 static inline bool d_is_reg(const struct dentry *dentry)
429 {
430 return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
431 }
432
d_is_special(const struct dentry * dentry)433 static inline bool d_is_special(const struct dentry *dentry)
434 {
435 return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
436 }
437
d_is_file(const struct dentry * dentry)438 static inline bool d_is_file(const struct dentry *dentry)
439 {
440 return d_is_reg(dentry) || d_is_special(dentry);
441 }
442
d_is_negative(const struct dentry * dentry)443 static inline bool d_is_negative(const struct dentry *dentry)
444 {
445 // TODO: check d_is_whiteout(dentry) also.
446 return d_is_miss(dentry);
447 }
448
d_flags_negative(unsigned flags)449 static inline bool d_flags_negative(unsigned flags)
450 {
451 return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE;
452 }
453
d_is_positive(const struct dentry * dentry)454 static inline bool d_is_positive(const struct dentry *dentry)
455 {
456 return !d_is_negative(dentry);
457 }
458
459 /**
460 * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
461 * @dentry: The dentry in question
462 *
463 * Returns true if the dentry represents either an absent name or a name that
464 * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
465 * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
466 * fallthrough marker in an opaque directory.
467 *
468 * Note! (1) This should be used *only* by a filesystem to examine its own
469 * dentries. It should not be used to look at some other filesystem's
470 * dentries. (2) It should also be used in combination with d_inode() to get
471 * the inode. (3) The dentry may have something attached to ->d_lower and the
472 * type field of the flags may be set to something other than miss or whiteout.
473 */
d_really_is_negative(const struct dentry * dentry)474 static inline bool d_really_is_negative(const struct dentry *dentry)
475 {
476 return dentry->d_inode == NULL;
477 }
478
479 /**
480 * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
481 * @dentry: The dentry in question
482 *
483 * Returns true if the dentry represents a name that maps to an inode
484 * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
485 * that is represented on medium as a 0,0 chardev.
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.
491 */
d_really_is_positive(const struct dentry * dentry)492 static inline bool d_really_is_positive(const struct dentry *dentry)
493 {
494 return dentry->d_inode != NULL;
495 }
496
simple_positive(const struct dentry * dentry)497 static inline int simple_positive(const struct dentry *dentry)
498 {
499 return d_really_is_positive(dentry) && !d_unhashed(dentry);
500 }
501
502 extern void d_set_fallthru(struct dentry *dentry);
503
d_is_fallthru(const struct dentry * dentry)504 static inline bool d_is_fallthru(const struct dentry *dentry)
505 {
506 return dentry->d_flags & DCACHE_FALLTHRU;
507 }
508
509
510 extern int sysctl_vfs_cache_pressure;
511
vfs_pressure_ratio(unsigned long val)512 static inline unsigned long vfs_pressure_ratio(unsigned long val)
513 {
514 return mult_frac(val, sysctl_vfs_cache_pressure, 100);
515 }
516
517 /**
518 * d_inode - Get the actual inode of this dentry
519 * @dentry: The dentry to query
520 *
521 * This is the helper normal filesystems should use to get at their own inodes
522 * in their own dentries and ignore the layering superimposed upon them.
523 */
d_inode(const struct dentry * dentry)524 static inline struct inode *d_inode(const struct dentry *dentry)
525 {
526 return dentry->d_inode;
527 }
528
529 /**
530 * d_inode_rcu - Get the actual inode of this dentry with READ_ONCE()
531 * @dentry: The dentry to query
532 *
533 * This is the helper normal filesystems should use to get at their own inodes
534 * in their own dentries and ignore the layering superimposed upon them.
535 */
d_inode_rcu(const struct dentry * dentry)536 static inline struct inode *d_inode_rcu(const struct dentry *dentry)
537 {
538 return READ_ONCE(dentry->d_inode);
539 }
540
541 /**
542 * d_backing_inode - Get upper or lower inode we should be using
543 * @upper: The upper layer
544 *
545 * This is the helper that should be used to get at the inode that will be used
546 * if this dentry were to be opened as a file. The inode may be on the upper
547 * dentry or it may be on a lower dentry pinned by the upper.
548 *
549 * Normal filesystems should not use this to access their own inodes.
550 */
d_backing_inode(const struct dentry * upper)551 static inline struct inode *d_backing_inode(const struct dentry *upper)
552 {
553 struct inode *inode = upper->d_inode;
554
555 return inode;
556 }
557
558 /**
559 * d_backing_dentry - Get upper or lower dentry we should be using
560 * @upper: The upper layer
561 *
562 * This is the helper that should be used to get the dentry of the inode that
563 * will be used if this dentry were opened as a file. It may be the upper
564 * dentry or it may be a lower dentry pinned by the upper.
565 *
566 * Normal filesystems should not use this to access their own dentries.
567 */
d_backing_dentry(struct dentry * upper)568 static inline struct dentry *d_backing_dentry(struct dentry *upper)
569 {
570 return upper;
571 }
572
573 /**
574 * d_real - Return the real dentry
575 * @dentry: the dentry to query
576 * @inode: inode to select the dentry from multiple layers (can be NULL)
577 *
578 * If dentry is on a union/overlay, then return the underlying, real dentry.
579 * Otherwise return the dentry itself.
580 *
581 * See also: Documentation/filesystems/vfs.rst
582 */
d_real(struct dentry * dentry,const struct inode * inode)583 static inline struct dentry *d_real(struct dentry *dentry,
584 const struct inode *inode)
585 {
586 if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
587 return dentry->d_op->d_real(dentry, inode);
588 else
589 return dentry;
590 }
591
592 /**
593 * d_real_inode - Return the real inode
594 * @dentry: The dentry to query
595 *
596 * If dentry is on a union/overlay, then return the underlying, real inode.
597 * Otherwise return d_inode().
598 */
d_real_inode(const struct dentry * dentry)599 static inline struct inode *d_real_inode(const struct dentry *dentry)
600 {
601 /* This usage of d_real() results in const dentry */
602 return d_backing_inode(d_real((struct dentry *) dentry, NULL));
603 }
604
605 struct name_snapshot {
606 struct qstr name;
607 unsigned char inline_name[DNAME_INLINE_LEN];
608 };
609 void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
610 void release_dentry_name_snapshot(struct name_snapshot *);
611
612 #endif /* __LINUX_DCACHE_H */
613