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 vfsmount;
20 :
21 : /*
22 : * linux/include/linux/dcache.h
23 : *
24 : * Dirent cache data structures
25 : *
26 : * (C) Copyright 1997 Thomas Schoebel-Theuer,
27 : * with heavy changes by Linus Torvalds
28 : */
29 :
30 : #define IS_ROOT(x) ((x) == (x)->d_parent)
31 :
32 : /* The hash is always the low bits of hash_len */
33 : #ifdef __LITTLE_ENDIAN
34 : #define HASH_LEN_DECLARE u32 hash; u32 len
35 : #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
36 : #else
37 : #define HASH_LEN_DECLARE u32 len; u32 hash
38 : #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
39 : #endif
40 :
41 : /*
42 : * "quick string" -- eases parameter passing, but more importantly
43 : * saves "metadata" about the string (ie length and the hash).
44 : *
45 : * hash comes first so it snuggles against d_parent in the
46 : * dentry.
47 : */
48 : struct qstr {
49 : union {
50 : struct {
51 : HASH_LEN_DECLARE;
52 : };
53 : u64 hash_len;
54 : };
55 : const unsigned char *name;
56 : };
57 :
58 : #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
59 :
60 : extern const struct qstr empty_name;
61 : extern const struct qstr slash_name;
62 :
63 : struct dentry_stat_t {
64 : long nr_dentry;
65 : long nr_unused;
66 : long age_limit; /* age in seconds */
67 : long want_pages; /* pages requested by system */
68 : long nr_negative; /* # of unused negative dentries */
69 : long dummy; /* Reserved for future use */
70 : };
71 : extern struct dentry_stat_t dentry_stat;
72 :
73 : /*
74 : * Try to keep struct dentry aligned on 64 byte cachelines (this will
75 : * give reasonable cacheline footprint with larger lines without the
76 : * large memory footprint increase).
77 : */
78 : #ifdef CONFIG_64BIT
79 : # define DNAME_INLINE_LEN 32 /* 192 bytes */
80 : #else
81 : # ifdef CONFIG_SMP
82 : # define DNAME_INLINE_LEN 36 /* 128 bytes */
83 : # else
84 : # define DNAME_INLINE_LEN 40 /* 128 bytes */
85 : # endif
86 : #endif
87 :
88 : #define d_lock d_lockref.lock
89 :
90 : struct dentry {
91 : /* RCU lookup touched fields */
92 : unsigned int d_flags; /* protected by d_lock */
93 : seqcount_spinlock_t d_seq; /* per dentry seqlock */
94 : struct hlist_bl_node d_hash; /* lookup hash list */
95 : struct dentry *d_parent; /* parent directory */
96 : struct qstr d_name;
97 : struct inode *d_inode; /* Where the name belongs to - NULL is
98 : * negative */
99 : unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
100 :
101 : /* Ref lookup also touches following */
102 : struct lockref d_lockref; /* per-dentry lock and refcount */
103 : const struct dentry_operations *d_op;
104 : struct super_block *d_sb; /* The root of the dentry tree */
105 : unsigned long d_time; /* used by d_revalidate */
106 : void *d_fsdata; /* fs-specific data */
107 :
108 : union {
109 : struct list_head d_lru; /* LRU list */
110 : wait_queue_head_t *d_wait; /* in-lookup ones only */
111 : };
112 : struct list_head d_child; /* child of parent list */
113 : struct list_head d_subdirs; /* our children */
114 : /*
115 : * d_alias and d_rcu can share memory
116 : */
117 : union {
118 : struct hlist_node d_alias; /* inode alias list */
119 : struct hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */
120 : struct rcu_head d_rcu;
121 : } d_u;
122 : } __randomize_layout;
123 :
124 : /*
125 : * dentry->d_lock spinlock nesting subclasses:
126 : *
127 : * 0: normal
128 : * 1: nested
129 : */
130 : enum dentry_d_lock_class
131 : {
132 : DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
133 : DENTRY_D_LOCK_NESTED
134 : };
135 :
136 : struct dentry_operations {
137 : int (*d_revalidate)(struct dentry *, unsigned int);
138 : int (*d_weak_revalidate)(struct dentry *, unsigned int);
139 : int (*d_hash)(const struct dentry *, struct qstr *);
140 : int (*d_compare)(const struct dentry *,
141 : unsigned int, const char *, const struct qstr *);
142 : int (*d_delete)(const struct dentry *);
143 : int (*d_init)(struct dentry *);
144 : void (*d_release)(struct dentry *);
145 : void (*d_prune)(struct dentry *);
146 : void (*d_iput)(struct dentry *, struct inode *);
147 : char *(*d_dname)(struct dentry *, char *, int);
148 : struct vfsmount *(*d_automount)(struct path *);
149 : int (*d_manage)(const struct path *, bool);
150 : struct dentry *(*d_real)(struct dentry *, const struct inode *);
151 : } ____cacheline_aligned;
152 :
153 : /*
154 : * Locking rules for dentry_operations callbacks are to be found in
155 : * Documentation/filesystems/locking.rst. Keep it updated!
156 : *
157 : * FUrther descriptions are found in Documentation/filesystems/vfs.rst.
158 : * Keep it updated too!
159 : */
160 :
161 : /* d_flags entries */
162 : #define DCACHE_OP_HASH 0x00000001
163 : #define DCACHE_OP_COMPARE 0x00000002
164 : #define DCACHE_OP_REVALIDATE 0x00000004
165 : #define DCACHE_OP_DELETE 0x00000008
166 : #define DCACHE_OP_PRUNE 0x00000010
167 :
168 : #define DCACHE_DISCONNECTED 0x00000020
169 : /* This dentry is possibly not currently connected to the dcache tree, in
170 : * which case its parent will either be itself, or will have this flag as
171 : * well. nfsd will not use a dentry with this bit set, but will first
172 : * endeavour to clear the bit either by discovering that it is connected,
173 : * or by performing lookup operations. Any filesystem which supports
174 : * nfsd_operations MUST have a lookup function which, if it finds a
175 : * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
176 : * dentry into place and return that dentry rather than the passed one,
177 : * typically using d_splice_alias. */
178 :
179 : #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
180 :
181 : #define DCACHE_DONTCACHE 0x00000080 /* Purge from memory on final dput() */
182 :
183 : #define DCACHE_CANT_MOUNT 0x00000100
184 : #define DCACHE_GENOCIDE 0x00000200
185 : #define DCACHE_SHRINK_LIST 0x00000400
186 :
187 : #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
188 :
189 : #define DCACHE_NFSFS_RENAMED 0x00001000
190 : /* this dentry has been "silly renamed" and has to be deleted on the last
191 : * dput() */
192 : #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
193 : #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
194 : /* Parent inode is watched by some fsnotify listener */
195 :
196 : #define DCACHE_DENTRY_KILLED 0x00008000
197 :
198 : #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
199 : #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
200 : #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
201 : #define DCACHE_MANAGED_DENTRY \
202 : (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
203 :
204 : #define DCACHE_LRU_LIST 0x00080000
205 :
206 : #define DCACHE_ENTRY_TYPE 0x00700000
207 : #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
208 : #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
209 : #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
210 : #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
211 : #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
212 : #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
213 : #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
214 :
215 : #define DCACHE_MAY_FREE 0x00800000
216 : #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
217 : #define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */
218 : #define DCACHE_OP_REAL 0x04000000
219 :
220 : #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
221 : #define DCACHE_DENTRY_CURSOR 0x20000000
222 : #define DCACHE_NORCU 0x40000000 /* No RCU delay for freeing */
223 :
224 : extern seqlock_t rename_lock;
225 :
226 : /*
227 : * These are the low-level FS interfaces to the dcache..
228 : */
229 : extern void d_instantiate(struct dentry *, struct inode *);
230 : extern void d_instantiate_new(struct dentry *, struct inode *);
231 : extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
232 : extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
233 : extern void __d_drop(struct dentry *dentry);
234 : extern void d_drop(struct dentry *dentry);
235 : extern void d_delete(struct dentry *);
236 : extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
237 :
238 : /* allocate/de-allocate */
239 : extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
240 : extern struct dentry * d_alloc_anon(struct super_block *);
241 : extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
242 : wait_queue_head_t *);
243 : extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
244 : extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
245 : extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
246 : extern struct dentry *d_find_any_alias(struct inode *inode);
247 : extern struct dentry * d_obtain_alias(struct inode *);
248 : extern struct dentry * d_obtain_root(struct inode *);
249 : extern void shrink_dcache_sb(struct super_block *);
250 : extern void shrink_dcache_parent(struct dentry *);
251 : extern void shrink_dcache_for_umount(struct super_block *);
252 : extern void d_invalidate(struct dentry *);
253 :
254 : /* only used at mount-time */
255 : extern struct dentry * d_make_root(struct inode *);
256 :
257 : /* <clickety>-<click> the ramfs-type tree */
258 : extern void d_genocide(struct dentry *);
259 :
260 : extern void d_tmpfile(struct dentry *, struct inode *);
261 :
262 : extern struct dentry *d_find_alias(struct inode *);
263 : extern void d_prune_aliases(struct inode *);
264 :
265 : extern struct dentry *d_find_alias_rcu(struct inode *);
266 :
267 : /* test whether we have any submounts in a subdir tree */
268 : extern int path_has_submounts(const struct path *);
269 :
270 : /*
271 : * This adds the entry to the hash queues.
272 : */
273 : extern void d_rehash(struct dentry *);
274 :
275 : extern void d_add(struct dentry *, struct inode *);
276 :
277 : /* used for rename() and baskets */
278 : extern void d_move(struct dentry *, struct dentry *);
279 : extern void d_exchange(struct dentry *, struct dentry *);
280 : extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
281 :
282 : /* appendix may either be NULL or be used for transname suffixes */
283 : extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
284 : extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
285 : extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
286 : extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
287 : const struct qstr *name, unsigned *seq);
288 :
289 : static inline unsigned d_count(const struct dentry *dentry)
290 : {
291 : return dentry->d_lockref.count;
292 : }
293 :
294 : /*
295 : * helper function for dentry_operations.d_dname() members
296 : */
297 : extern __printf(4, 5)
298 : char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
299 :
300 : extern char *__d_path(const struct path *, const struct path *, char *, int);
301 : extern char *d_absolute_path(const struct path *, char *, int);
302 : extern char *d_path(const struct path *, char *, int);
303 : extern char *dentry_path_raw(struct dentry *, char *, int);
304 : extern char *dentry_path(struct dentry *, char *, int);
305 :
306 : /* Allocation counts.. */
307 :
308 : /**
309 : * dget, dget_dlock - get a reference to a dentry
310 : * @dentry: dentry to get a reference to
311 : *
312 : * Given a dentry or %NULL pointer increment the reference count
313 : * if appropriate and return the dentry. A dentry will not be
314 : * destroyed when it has references.
315 : */
316 3054 : static inline struct dentry *dget_dlock(struct dentry *dentry)
317 : {
318 3054 : if (dentry)
319 3054 : dentry->d_lockref.count++;
320 : return dentry;
321 : }
322 :
323 60968 : static inline struct dentry *dget(struct dentry *dentry)
324 : {
325 60967 : if (dentry)
326 60968 : lockref_get(&dentry->d_lockref);
327 6678 : return dentry;
328 : }
329 :
330 : extern struct dentry *dget_parent(struct dentry *dentry);
331 :
332 : /**
333 : * d_unhashed - is dentry hashed
334 : * @dentry: entry to check
335 : *
336 : * Returns true if the dentry passed is not currently hashed.
337 : */
338 :
339 279639 : static inline int d_unhashed(const struct dentry *dentry)
340 : {
341 279343 : return hlist_bl_unhashed(&dentry->d_hash);
342 : }
343 :
344 6230 : static inline int d_unlinked(const struct dentry *dentry)
345 : {
346 6230 : return d_unhashed(dentry) && !IS_ROOT(dentry);
347 : }
348 :
349 161 : static inline int cant_mount(const struct dentry *dentry)
350 : {
351 161 : return (dentry->d_flags & DCACHE_CANT_MOUNT);
352 : }
353 :
354 1293 : static inline void dont_mount(struct dentry *dentry)
355 : {
356 1293 : spin_lock(&dentry->d_lock);
357 1293 : dentry->d_flags |= DCACHE_CANT_MOUNT;
358 1293 : spin_unlock(&dentry->d_lock);
359 1293 : }
360 :
361 : extern void __d_lookup_done(struct dentry *);
362 :
363 119976 : static inline int d_in_lookup(const struct dentry *dentry)
364 : {
365 95226 : return dentry->d_flags & DCACHE_PAR_LOOKUP;
366 : }
367 :
368 24750 : static inline void d_lookup_done(struct dentry *dentry)
369 : {
370 24750 : if (unlikely(d_in_lookup(dentry))) {
371 1535 : spin_lock(&dentry->d_lock);
372 1535 : __d_lookup_done(dentry);
373 1535 : spin_unlock(&dentry->d_lock);
374 : }
375 24750 : }
376 :
377 : extern void dput(struct dentry *);
378 :
379 : static inline bool d_managed(const struct dentry *dentry)
380 : {
381 : return dentry->d_flags & DCACHE_MANAGED_DENTRY;
382 : }
383 :
384 4639 : static inline bool d_mountpoint(const struct dentry *dentry)
385 : {
386 4639 : return dentry->d_flags & DCACHE_MOUNTED;
387 : }
388 :
389 : /*
390 : * Directory cache entry type accessor functions.
391 : */
392 415666 : static inline unsigned __d_entry_type(const struct dentry *dentry)
393 : {
394 415666 : return dentry->d_flags & DCACHE_ENTRY_TYPE;
395 : }
396 :
397 26899 : static inline bool d_is_miss(const struct dentry *dentry)
398 : {
399 26899 : return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
400 : }
401 :
402 : static inline bool d_is_whiteout(const struct dentry *dentry)
403 : {
404 : return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
405 : }
406 :
407 173080 : static inline bool d_can_lookup(const struct dentry *dentry)
408 : {
409 169081 : return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
410 : }
411 :
412 2860 : static inline bool d_is_autodir(const struct dentry *dentry)
413 : {
414 2860 : return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
415 : }
416 :
417 4375 : static inline bool d_is_dir(const struct dentry *dentry)
418 : {
419 4372 : return d_can_lookup(dentry) || d_is_autodir(dentry);
420 : }
421 :
422 197855 : static inline bool d_is_symlink(const struct dentry *dentry)
423 : {
424 197855 : return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
425 : }
426 :
427 14972 : static inline bool d_is_reg(const struct dentry *dentry)
428 : {
429 14972 : return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
430 : }
431 :
432 : static inline bool d_is_special(const struct dentry *dentry)
433 : {
434 : return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
435 : }
436 :
437 : static inline bool d_is_file(const struct dentry *dentry)
438 : {
439 : return d_is_reg(dentry) || d_is_special(dentry);
440 : }
441 :
442 26899 : static inline bool d_is_negative(const struct dentry *dentry)
443 : {
444 : // TODO: check d_is_whiteout(dentry) also.
445 22124 : return d_is_miss(dentry);
446 : }
447 :
448 45241 : static inline bool d_flags_negative(unsigned flags)
449 : {
450 45241 : return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE;
451 : }
452 :
453 5578 : static inline bool d_is_positive(const struct dentry *dentry)
454 : {
455 5578 : return !d_is_negative(dentry);
456 : }
457 :
458 : /**
459 : * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
460 : * @dentry: The dentry in question
461 : *
462 : * Returns true if the dentry represents either an absent name or a name that
463 : * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
464 : * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
465 : * fallthrough marker in an opaque directory.
466 : *
467 : * Note! (1) This should be used *only* by a filesystem to examine its own
468 : * dentries. It should not be used to look at some other filesystem's
469 : * dentries. (2) It should also be used in combination with d_inode() to get
470 : * the inode. (3) The dentry may have something attached to ->d_lower and the
471 : * type field of the flags may be set to something other than miss or whiteout.
472 : */
473 63746 : static inline bool d_really_is_negative(const struct dentry *dentry)
474 : {
475 43202 : return dentry->d_inode == NULL;
476 : }
477 :
478 : /**
479 : * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
480 : * @dentry: The dentry in question
481 : *
482 : * Returns true if the dentry represents a name that maps to an inode
483 : * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
484 : * that is represented on medium as a 0,0 chardev.
485 : *
486 : * Note! (1) This should be used *only* by a filesystem to examine its own
487 : * dentries. It should not be used to look at some other filesystem's
488 : * dentries. (2) It should also be used in combination with d_inode() to get
489 : * the inode.
490 : */
491 8822 : static inline bool d_really_is_positive(const struct dentry *dentry)
492 : {
493 2353 : return dentry->d_inode != NULL;
494 : }
495 :
496 6469 : static inline int simple_positive(const struct dentry *dentry)
497 : {
498 6469 : return d_really_is_positive(dentry) && !d_unhashed(dentry);
499 : }
500 :
501 : extern void d_set_fallthru(struct dentry *dentry);
502 :
503 : static inline bool d_is_fallthru(const struct dentry *dentry)
504 : {
505 : return dentry->d_flags & DCACHE_FALLTHRU;
506 : }
507 :
508 :
509 : extern int sysctl_vfs_cache_pressure;
510 :
511 0 : static inline unsigned long vfs_pressure_ratio(unsigned long val)
512 : {
513 0 : return mult_frac(val, sysctl_vfs_cache_pressure, 100);
514 : }
515 :
516 : /**
517 : * d_inode - Get the actual inode of this dentry
518 : * @dentry: The dentry to query
519 : *
520 : * This is the helper normal filesystems should use to get at their own inodes
521 : * in their own dentries and ignore the layering superimposed upon them.
522 : */
523 460066 : static inline struct inode *d_inode(const struct dentry *dentry)
524 : {
525 452293 : return dentry->d_inode;
526 : }
527 :
528 : /**
529 : * d_inode_rcu - Get the actual inode of this dentry with READ_ONCE()
530 : * @dentry: The dentry to query
531 : *
532 : * This is the helper normal filesystems should use to get at their own inodes
533 : * in their own dentries and ignore the layering superimposed upon them.
534 : */
535 38 : static inline struct inode *d_inode_rcu(const struct dentry *dentry)
536 : {
537 38 : return READ_ONCE(dentry->d_inode);
538 : }
539 :
540 : /**
541 : * d_backing_inode - Get upper or lower inode we should be using
542 : * @upper: The upper layer
543 : *
544 : * This is the helper that should be used to get at the inode that will be used
545 : * if this dentry were to be opened as a file. The inode may be on the upper
546 : * dentry or it may be on a lower dentry pinned by the upper.
547 : *
548 : * Normal filesystems should not use this to access their own inodes.
549 : */
550 373399 : static inline struct inode *d_backing_inode(const struct dentry *upper)
551 : {
552 373399 : struct inode *inode = upper->d_inode;
553 :
554 373399 : return inode;
555 : }
556 :
557 : /**
558 : * d_backing_dentry - Get upper or lower dentry we should be using
559 : * @upper: The upper layer
560 : *
561 : * This is the helper that should be used to get the dentry of the inode that
562 : * will be used if this dentry were opened as a file. It may be the upper
563 : * dentry or it may be a lower dentry pinned by the upper.
564 : *
565 : * Normal filesystems should not use this to access their own dentries.
566 : */
567 : static inline struct dentry *d_backing_dentry(struct dentry *upper)
568 : {
569 : return upper;
570 : }
571 :
572 : /**
573 : * d_real - Return the real dentry
574 : * @dentry: the dentry to query
575 : * @inode: inode to select the dentry from multiple layers (can be NULL)
576 : *
577 : * If dentry is on a union/overlay, then return the underlying, real dentry.
578 : * Otherwise return the dentry itself.
579 : *
580 : * See also: Documentation/filesystems/vfs.rst
581 : */
582 1629 : static inline struct dentry *d_real(struct dentry *dentry,
583 : const struct inode *inode)
584 : {
585 1629 : if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
586 39 : return dentry->d_op->d_real(dentry, inode);
587 : else
588 : return dentry;
589 : }
590 :
591 : /**
592 : * d_real_inode - Return the real inode
593 : * @dentry: The dentry to query
594 : *
595 : * If dentry is on a union/overlay, then return the underlying, real inode.
596 : * Otherwise return d_inode().
597 : */
598 : static inline struct inode *d_real_inode(const struct dentry *dentry)
599 : {
600 : /* This usage of d_real() results in const dentry */
601 : return d_backing_inode(d_real((struct dentry *) dentry, NULL));
602 : }
603 :
604 : struct name_snapshot {
605 : struct qstr name;
606 : unsigned char inline_name[DNAME_INLINE_LEN];
607 : };
608 : void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
609 : void release_dentry_name_snapshot(struct name_snapshot *);
610 :
611 : #endif /* __LINUX_DCACHE_H */
|
