Line data Source code
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 :
61 : extern const struct qstr empty_name;
62 : extern const struct qstr slash_name;
63 : extern const struct qstr dotdot_name;
64 :
65 : /*
66 : * Try to keep struct dentry aligned on 64 byte cachelines (this will
67 : * give reasonable cacheline footprint with larger lines without the
68 : * large memory footprint increase).
69 : */
70 : #ifdef CONFIG_64BIT
71 : # define DNAME_INLINE_LEN 32 /* 192 bytes */
72 : #else
73 : # ifdef CONFIG_SMP
74 : # define DNAME_INLINE_LEN 36 /* 128 bytes */
75 : # else
76 : # define DNAME_INLINE_LEN 40 /* 128 bytes */
77 : # endif
78 : #endif
79 :
80 : #define d_lock d_lockref.lock
81 :
82 : struct dentry {
83 : /* RCU lookup touched fields */
84 : unsigned int d_flags; /* protected by d_lock */
85 : seqcount_spinlock_t d_seq; /* per dentry seqlock */
86 : struct hlist_bl_node d_hash; /* lookup hash list */
87 : struct dentry *d_parent; /* parent directory */
88 : struct qstr d_name;
89 : struct inode *d_inode; /* Where the name belongs to - NULL is
90 : * negative */
91 : unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
92 :
93 : /* Ref lookup also touches following */
94 : struct lockref d_lockref; /* per-dentry lock and refcount */
95 : const struct dentry_operations *d_op;
96 : struct super_block *d_sb; /* The root of the dentry tree */
97 : unsigned long d_time; /* used by d_revalidate */
98 : void *d_fsdata; /* fs-specific data */
99 :
100 : union {
101 : struct list_head d_lru; /* LRU list */
102 : wait_queue_head_t *d_wait; /* in-lookup ones only */
103 : };
104 : struct list_head d_child; /* child of parent list */
105 : struct list_head d_subdirs; /* our children */
106 : /*
107 : * d_alias and d_rcu can share memory
108 : */
109 : union {
110 : struct hlist_node d_alias; /* inode alias list */
111 : struct hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */
112 : struct rcu_head d_rcu;
113 : } d_u;
114 : } __randomize_layout;
115 :
116 : /*
117 : * dentry->d_lock spinlock nesting subclasses:
118 : *
119 : * 0: normal
120 : * 1: nested
121 : */
122 : enum dentry_d_lock_class
123 : {
124 : DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
125 : DENTRY_D_LOCK_NESTED
126 : };
127 :
128 : struct dentry_operations {
129 : int (*d_revalidate)(struct dentry *, unsigned int);
130 : int (*d_weak_revalidate)(struct dentry *, unsigned int);
131 : int (*d_hash)(const struct dentry *, struct qstr *);
132 : int (*d_compare)(const struct dentry *,
133 : unsigned int, const char *, const struct qstr *);
134 : int (*d_delete)(const struct dentry *);
135 : int (*d_init)(struct dentry *);
136 : void (*d_release)(struct dentry *);
137 : void (*d_prune)(struct dentry *);
138 : void (*d_iput)(struct dentry *, struct inode *);
139 : char *(*d_dname)(struct dentry *, char *, int);
140 : struct vfsmount *(*d_automount)(struct path *);
141 : int (*d_manage)(const struct path *, bool);
142 : struct dentry *(*d_real)(struct dentry *, const struct inode *);
143 : } ____cacheline_aligned;
144 :
145 : /*
146 : * Locking rules for dentry_operations callbacks are to be found in
147 : * Documentation/filesystems/locking.rst. Keep it updated!
148 : *
149 : * FUrther descriptions are found in Documentation/filesystems/vfs.rst.
150 : * Keep it updated too!
151 : */
152 :
153 : /* d_flags entries */
154 : #define DCACHE_OP_HASH 0x00000001
155 : #define DCACHE_OP_COMPARE 0x00000002
156 : #define DCACHE_OP_REVALIDATE 0x00000004
157 : #define DCACHE_OP_DELETE 0x00000008
158 : #define DCACHE_OP_PRUNE 0x00000010
159 :
160 : #define DCACHE_DISCONNECTED 0x00000020
161 : /* This dentry is possibly not currently connected to the dcache tree, in
162 : * which case its parent will either be itself, or will have this flag as
163 : * well. nfsd will not use a dentry with this bit set, but will first
164 : * endeavour to clear the bit either by discovering that it is connected,
165 : * or by performing lookup operations. Any filesystem which supports
166 : * nfsd_operations MUST have a lookup function which, if it finds a
167 : * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
168 : * dentry into place and return that dentry rather than the passed one,
169 : * typically using d_splice_alias. */
170 :
171 : #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
172 :
173 : #define DCACHE_DONTCACHE 0x00000080 /* Purge from memory on final dput() */
174 :
175 : #define DCACHE_CANT_MOUNT 0x00000100
176 : #define DCACHE_GENOCIDE 0x00000200
177 : #define DCACHE_SHRINK_LIST 0x00000400
178 :
179 : #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
180 :
181 : #define DCACHE_NFSFS_RENAMED 0x00001000
182 : /* this dentry has been "silly renamed" and has to be deleted on the last
183 : * dput() */
184 : #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
185 : #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
186 : /* Parent inode is watched by some fsnotify listener */
187 :
188 : #define DCACHE_DENTRY_KILLED 0x00008000
189 :
190 : #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
191 : #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
192 : #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
193 : #define DCACHE_MANAGED_DENTRY \
194 : (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
195 :
196 : #define DCACHE_LRU_LIST 0x00080000
197 :
198 : #define DCACHE_ENTRY_TYPE 0x00700000
199 : #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
200 : #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
201 : #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
202 : #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
203 : #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
204 : #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
205 : #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
206 :
207 : #define DCACHE_MAY_FREE 0x00800000
208 : #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
209 : #define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */
210 : #define DCACHE_OP_REAL 0x04000000
211 :
212 : #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
213 : #define DCACHE_DENTRY_CURSOR 0x20000000
214 : #define DCACHE_NORCU 0x40000000 /* No RCU delay for freeing */
215 :
216 : extern seqlock_t rename_lock;
217 :
218 : /*
219 : * These are the low-level FS interfaces to the dcache..
220 : */
221 : extern void d_instantiate(struct dentry *, struct inode *);
222 : extern void d_instantiate_new(struct dentry *, struct inode *);
223 : extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
224 : extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
225 : extern void __d_drop(struct dentry *dentry);
226 : extern void d_drop(struct dentry *dentry);
227 : extern void d_delete(struct dentry *);
228 : extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
229 :
230 : /* allocate/de-allocate */
231 : extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
232 : extern struct dentry * d_alloc_anon(struct super_block *);
233 : extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
234 : wait_queue_head_t *);
235 : extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
236 : extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
237 : extern bool d_same_name(const struct dentry *dentry, const struct dentry *parent,
238 : const struct qstr *name);
239 : extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
240 : extern struct dentry *d_find_any_alias(struct inode *inode);
241 : extern struct dentry * d_obtain_alias(struct inode *);
242 : extern struct dentry * d_obtain_root(struct inode *);
243 : extern void shrink_dcache_sb(struct super_block *);
244 : extern void shrink_dcache_parent(struct dentry *);
245 : extern void shrink_dcache_for_umount(struct super_block *);
246 : extern void d_invalidate(struct dentry *);
247 :
248 : /* only used at mount-time */
249 : extern struct dentry * d_make_root(struct inode *);
250 :
251 : /* <clickety>-<click> the ramfs-type tree */
252 : extern void d_genocide(struct dentry *);
253 :
254 : extern void d_tmpfile(struct file *, struct inode *);
255 :
256 : extern struct dentry *d_find_alias(struct inode *);
257 : extern void d_prune_aliases(struct inode *);
258 :
259 : extern struct dentry *d_find_alias_rcu(struct inode *);
260 :
261 : /* test whether we have any submounts in a subdir tree */
262 : extern int path_has_submounts(const struct path *);
263 :
264 : /*
265 : * This adds the entry to the hash queues.
266 : */
267 : extern void d_rehash(struct dentry *);
268 :
269 : extern void d_add(struct dentry *, struct inode *);
270 :
271 : /* used for rename() and baskets */
272 : extern void d_move(struct dentry *, struct dentry *);
273 : extern void d_exchange(struct dentry *, struct dentry *);
274 : extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
275 :
276 : /* appendix may either be NULL or be used for transname suffixes */
277 : extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
278 : extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
279 : extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
280 : extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
281 : const struct qstr *name, unsigned *seq);
282 :
283 : static inline unsigned d_count(const struct dentry *dentry)
284 : {
285 : return dentry->d_lockref.count;
286 : }
287 :
288 : /*
289 : * helper function for dentry_operations.d_dname() members
290 : */
291 : extern __printf(3, 4)
292 : char *dynamic_dname(char *, int, const char *, ...);
293 :
294 : extern char *__d_path(const struct path *, const struct path *, char *, int);
295 : extern char *d_absolute_path(const struct path *, char *, int);
296 : extern char *d_path(const struct path *, char *, int);
297 : extern char *dentry_path_raw(const struct dentry *, char *, int);
298 : extern char *dentry_path(const struct dentry *, char *, int);
299 :
300 : /* Allocation counts.. */
301 :
302 : /**
303 : * dget, dget_dlock - get a reference to a dentry
304 : * @dentry: dentry to get a reference to
305 : *
306 : * Given a dentry or %NULL pointer increment the reference count
307 : * if appropriate and return the dentry. A dentry will not be
308 : * destroyed when it has references.
309 : */
310 : static inline struct dentry *dget_dlock(struct dentry *dentry)
311 : {
312 258098772 : if (dentry)
313 258098772 : dentry->d_lockref.count++;
314 : return dentry;
315 : }
316 :
317 : static inline struct dentry *dget(struct dentry *dentry)
318 : {
319 2520387386 : if (dentry)
320 2520387386 : lockref_get(&dentry->d_lockref);
321 118459405 : return dentry;
322 : }
323 :
324 : extern struct dentry *dget_parent(struct dentry *dentry);
325 :
326 : /**
327 : * d_unhashed - is dentry hashed
328 : * @dentry: entry to check
329 : *
330 : * Returns true if the dentry passed is not currently hashed.
331 : */
332 :
333 : static inline int d_unhashed(const struct dentry *dentry)
334 : {
335 43087590530 : return hlist_bl_unhashed(&dentry->d_hash);
336 : }
337 :
338 : static inline int d_unlinked(const struct dentry *dentry)
339 : {
340 889397855 : return d_unhashed(dentry) && !IS_ROOT(dentry);
341 : }
342 :
343 : static inline int cant_mount(const struct dentry *dentry)
344 : {
345 229795 : return (dentry->d_flags & DCACHE_CANT_MOUNT);
346 : }
347 :
348 62288259 : static inline void dont_mount(struct dentry *dentry)
349 : {
350 62288259 : spin_lock(&dentry->d_lock);
351 62307679 : dentry->d_flags |= DCACHE_CANT_MOUNT;
352 62307679 : spin_unlock(&dentry->d_lock);
353 62318557 : }
354 :
355 : extern void __d_lookup_unhash_wake(struct dentry *dentry);
356 :
357 : static inline int d_in_lookup(const struct dentry *dentry)
358 : {
359 4694571662 : return dentry->d_flags & DCACHE_PAR_LOOKUP;
360 : }
361 :
362 831332288 : static inline void d_lookup_done(struct dentry *dentry)
363 : {
364 831332288 : if (unlikely(d_in_lookup(dentry)))
365 1221084 : __d_lookup_unhash_wake(dentry);
366 831332260 : }
367 :
368 : extern void dput(struct dentry *);
369 :
370 : static inline bool d_managed(const struct dentry *dentry)
371 : {
372 : return dentry->d_flags & DCACHE_MANAGED_DENTRY;
373 : }
374 :
375 : static inline bool d_mountpoint(const struct dentry *dentry)
376 : {
377 234261640 : return dentry->d_flags & DCACHE_MOUNTED;
378 : }
379 :
380 : /*
381 : * Directory cache entry type accessor functions.
382 : */
383 : static inline unsigned __d_entry_type(const struct dentry *dentry)
384 : {
385 74963292135 : return dentry->d_flags & DCACHE_ENTRY_TYPE;
386 : }
387 :
388 : static inline bool d_is_miss(const struct dentry *dentry)
389 : {
390 884041067 : return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
391 : }
392 :
393 : static inline bool d_is_whiteout(const struct dentry *dentry)
394 : {
395 : return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
396 : }
397 :
398 : static inline bool d_can_lookup(const struct dentry *dentry)
399 : {
400 33655790859 : return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
401 : }
402 :
403 : static inline bool d_is_autodir(const struct dentry *dentry)
404 : {
405 : return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
406 : }
407 :
408 : static inline bool d_is_dir(const struct dentry *dentry)
409 : {
410 309762007 : return d_can_lookup(dentry) || d_is_autodir(dentry);
411 : }
412 :
413 : static inline bool d_is_symlink(const struct dentry *dentry)
414 : {
415 39408416371 : return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
416 : }
417 :
418 : static inline bool d_is_reg(const struct dentry *dentry)
419 : {
420 710144562 : return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
421 : }
422 :
423 : static inline bool d_is_special(const struct dentry *dentry)
424 : {
425 3923501 : return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
426 : }
427 :
428 : static inline bool d_is_file(const struct dentry *dentry)
429 : {
430 : return d_is_reg(dentry) || d_is_special(dentry);
431 : }
432 :
433 : static inline bool d_is_negative(const struct dentry *dentry)
434 : {
435 : // TODO: check d_is_whiteout(dentry) also.
436 548688941 : return d_is_miss(dentry);
437 : }
438 :
439 : static inline bool d_flags_negative(unsigned flags)
440 : {
441 1349516809 : return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE;
442 : }
443 :
444 : static inline bool d_is_positive(const struct dentry *dentry)
445 : {
446 335352126 : return !d_is_negative(dentry);
447 : }
448 :
449 : /**
450 : * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
451 : * @dentry: The dentry in question
452 : *
453 : * Returns true if the dentry represents either an absent name or a name that
454 : * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
455 : * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
456 : * fallthrough marker in an opaque directory.
457 : *
458 : * Note! (1) This should be used *only* by a filesystem to examine its own
459 : * dentries. It should not be used to look at some other filesystem's
460 : * dentries. (2) It should also be used in combination with d_inode() to get
461 : * the inode. (3) The dentry may have something attached to ->d_lower and the
462 : * type field of the flags may be set to something other than miss or whiteout.
463 : */
464 : static inline bool d_really_is_negative(const struct dentry *dentry)
465 : {
466 60783 : return dentry->d_inode == NULL;
467 : }
468 :
469 : /**
470 : * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
471 : * @dentry: The dentry in question
472 : *
473 : * Returns true if the dentry represents a name that maps to an inode
474 : * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
475 : * that is represented on medium as a 0,0 chardev.
476 : *
477 : * Note! (1) This should be used *only* by a filesystem to examine its own
478 : * dentries. It should not be used to look at some other filesystem's
479 : * dentries. (2) It should also be used in combination with d_inode() to get
480 : * the inode.
481 : */
482 : static inline bool d_really_is_positive(const struct dentry *dentry)
483 : {
484 1284 : return dentry->d_inode != NULL;
485 : }
486 :
487 : static inline int simple_positive(const struct dentry *dentry)
488 : {
489 516738076 : return d_really_is_positive(dentry) && !d_unhashed(dentry);
490 : }
491 :
492 : extern void d_set_fallthru(struct dentry *dentry);
493 :
494 : static inline bool d_is_fallthru(const struct dentry *dentry)
495 : {
496 : return dentry->d_flags & DCACHE_FALLTHRU;
497 : }
498 :
499 :
500 : extern int sysctl_vfs_cache_pressure;
501 :
502 : static inline unsigned long vfs_pressure_ratio(unsigned long val)
503 : {
504 190414 : return mult_frac(val, sysctl_vfs_cache_pressure, 100);
505 : }
506 :
507 : /**
508 : * d_inode - Get the actual inode of this dentry
509 : * @dentry: The dentry to query
510 : *
511 : * This is the helper normal filesystems should use to get at their own inodes
512 : * in their own dentries and ignore the layering superimposed upon them.
513 : */
514 : static inline struct inode *d_inode(const struct dentry *dentry)
515 : {
516 11878636794 : return dentry->d_inode;
517 : }
518 :
519 : /**
520 : * d_inode_rcu - Get the actual inode of this dentry with READ_ONCE()
521 : * @dentry: The dentry to query
522 : *
523 : * This is the helper normal filesystems should use to get at their own inodes
524 : * in their own dentries and ignore the layering superimposed upon them.
525 : */
526 : static inline struct inode *d_inode_rcu(const struct dentry *dentry)
527 : {
528 : return READ_ONCE(dentry->d_inode);
529 : }
530 :
531 : /**
532 : * d_backing_inode - Get upper or lower inode we should be using
533 : * @upper: The upper layer
534 : *
535 : * This is the helper that should be used to get at the inode that will be used
536 : * if this dentry were to be opened as a file. The inode may be on the upper
537 : * dentry or it may be on a lower dentry pinned by the upper.
538 : *
539 : * Normal filesystems should not use this to access their own inodes.
540 : */
541 : static inline struct inode *d_backing_inode(const struct dentry *upper)
542 : {
543 5375572544 : struct inode *inode = upper->d_inode;
544 :
545 5375572544 : return inode;
546 : }
547 :
548 : /**
549 : * d_backing_dentry - Get upper or lower dentry we should be using
550 : * @upper: The upper layer
551 : *
552 : * This is the helper that should be used to get the dentry of the inode that
553 : * will be used if this dentry were opened as a file. It may be the upper
554 : * dentry or it may be a lower dentry pinned by the upper.
555 : *
556 : * Normal filesystems should not use this to access their own dentries.
557 : */
558 : static inline struct dentry *d_backing_dentry(struct dentry *upper)
559 : {
560 : return upper;
561 : }
562 :
563 : /**
564 : * d_real - Return the real dentry
565 : * @dentry: the dentry to query
566 : * @inode: inode to select the dentry from multiple layers (can be NULL)
567 : *
568 : * If dentry is on a union/overlay, then return the underlying, real dentry.
569 : * Otherwise return the dentry itself.
570 : *
571 : * See also: Documentation/filesystems/vfs.rst
572 : */
573 706648470 : static inline struct dentry *d_real(struct dentry *dentry,
574 : const struct inode *inode)
575 : {
576 706648470 : if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
577 125066 : return dentry->d_op->d_real(dentry, inode);
578 : else
579 : return dentry;
580 : }
581 :
582 : /**
583 : * d_real_inode - Return the real inode
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 : */
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_backing_inode(d_real((struct dentry *) dentry, NULL));
593 : }
594 :
595 : struct name_snapshot {
596 : struct qstr name;
597 : unsigned char inline_name[DNAME_INLINE_LEN];
598 : };
599 : void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
600 : void release_dentry_name_snapshot(struct name_snapshot *);
601 :
602 : #endif /* __LINUX_DCACHE_H */
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