1 #ifndef __LINUX_DCACHE_H
2 #define __LINUX_DCACHE_H
3
4 #include <linux/atomic.h>
5 #include <linux/list.h>
6 #include <linux/rculist.h>
7 #include <linux/rculist_bl.h>
8 #include <linux/spinlock.h>
9 #include <linux/seqlock.h>
10 #include <linux/cache.h>
11 #include <linux/rcupdate.h>
12 #include <linux/lockref.h>
13
14 struct path;
15 struct vfsmount;
16
17 /*
18 * linux/include/linux/dcache.h
19 *
20 * Dirent cache data structures
21 *
22 * (C) Copyright 1997 Thomas Schoebel-Theuer,
23 * with heavy changes by Linus Torvalds
24 */
25
26 #define IS_ROOT(x) ((x) == (x)->d_parent)
27
28 /* The hash is always the low bits of hash_len */
29 #ifdef __LITTLE_ENDIAN
30 #define HASH_LEN_DECLARE u32 hash; u32 len;
31 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
32 #else
33 #define HASH_LEN_DECLARE u32 len; u32 hash;
34 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
35 #endif
36
37 /*
38 * "quick string" -- eases parameter passing, but more importantly
39 * saves "metadata" about the string (ie length and the hash).
40 *
41 * hash comes first so it snuggles against d_parent in the
42 * dentry.
43 */
44 struct qstr {
45 union {
46 struct {
47 HASH_LEN_DECLARE;
48 };
49 u64 hash_len;
50 };
51 const unsigned char *name;
52 };
53
54 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
55 #define hashlen_hash(hashlen) ((u32) (hashlen))
56 #define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
57 #define hashlen_create(hash,len) (((u64)(len)<<32)|(u32)(hash))
58
59 struct dentry_stat_t {
60 long nr_dentry;
61 long nr_unused;
62 long age_limit; /* age in seconds */
63 long want_pages; /* pages requested by system */
64 long dummy[2];
65 };
66 extern struct dentry_stat_t dentry_stat;
67
68 /* Name hashing routines. Initial hash value */
69 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
70 #define init_name_hash() 0
71
72 /* partial hash update function. Assume roughly 4 bits per character */
73 static inline unsigned long
partial_name_hash(unsigned long c,unsigned long prevhash)74 partial_name_hash(unsigned long c, unsigned long prevhash)
75 {
76 return (prevhash + (c << 4) + (c >> 4)) * 11;
77 }
78
79 /*
80 * Finally: cut down the number of bits to a int value (and try to avoid
81 * losing bits)
82 */
end_name_hash(unsigned long hash)83 static inline unsigned long end_name_hash(unsigned long hash)
84 {
85 return (unsigned int) hash;
86 }
87
88 /* Compute the hash for a name string. */
89 extern unsigned int full_name_hash(const unsigned char *, unsigned int);
90
91 /*
92 * Try to keep struct dentry aligned on 64 byte cachelines (this will
93 * give reasonable cacheline footprint with larger lines without the
94 * large memory footprint increase).
95 */
96 #ifdef CONFIG_64BIT
97 # define DNAME_INLINE_LEN 32 /* 192 bytes */
98 #else
99 # ifdef CONFIG_SMP
100 # define DNAME_INLINE_LEN 36 /* 128 bytes */
101 # else
102 # define DNAME_INLINE_LEN 40 /* 128 bytes */
103 # endif
104 #endif
105
106 #define d_lock d_lockref.lock
107
108 struct dentry {
109 /* RCU lookup touched fields */
110 unsigned int d_flags; /* protected by d_lock */
111 seqcount_t d_seq; /* per dentry seqlock */
112 struct hlist_bl_node d_hash; /* lookup hash list */
113 struct dentry *d_parent; /* parent directory */
114 struct qstr d_name;
115 struct inode *d_inode; /* Where the name belongs to - NULL is
116 * negative */
117 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
118
119 /* Ref lookup also touches following */
120 struct lockref d_lockref; /* per-dentry lock and refcount */
121 const struct dentry_operations *d_op;
122 struct super_block *d_sb; /* The root of the dentry tree */
123 unsigned long d_time; /* used by d_revalidate */
124 void *d_fsdata; /* fs-specific data */
125
126 struct list_head d_lru; /* LRU list */
127 struct list_head d_child; /* child of parent list */
128 struct list_head d_subdirs; /* our children */
129 /*
130 * d_alias and d_rcu can share memory
131 */
132 union {
133 struct hlist_node d_alias; /* inode alias list */
134 struct rcu_head d_rcu;
135 } d_u;
136 };
137
138 /*
139 * dentry->d_lock spinlock nesting subclasses:
140 *
141 * 0: normal
142 * 1: nested
143 */
144 enum dentry_d_lock_class
145 {
146 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
147 DENTRY_D_LOCK_NESTED
148 };
149
150 struct dentry_operations {
151 int (*d_revalidate)(struct dentry *, unsigned int);
152 int (*d_weak_revalidate)(struct dentry *, unsigned int);
153 int (*d_hash)(const struct dentry *, struct qstr *);
154 int (*d_compare)(const struct dentry *, const struct dentry *,
155 unsigned int, const char *, const struct qstr *);
156 int (*d_delete)(const struct dentry *);
157 void (*d_release)(struct dentry *);
158 void (*d_prune)(struct dentry *);
159 void (*d_iput)(struct dentry *, struct inode *);
160 char *(*d_dname)(struct dentry *, char *, int);
161 struct vfsmount *(*d_automount)(struct path *);
162 int (*d_manage)(struct dentry *, bool);
163 struct inode *(*d_select_inode)(struct dentry *, unsigned);
164 struct dentry *(*d_real)(struct dentry *, struct inode *);
165 void (*d_canonical_path)(const struct path *, struct path *);
166 } ____cacheline_aligned;
167
168 /*
169 * Locking rules for dentry_operations callbacks are to be found in
170 * Documentation/filesystems/Locking. Keep it updated!
171 *
172 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
173 * Keep it updated too!
174 */
175
176 /* d_flags entries */
177 #define DCACHE_OP_HASH 0x00000001
178 #define DCACHE_OP_COMPARE 0x00000002
179 #define DCACHE_OP_REVALIDATE 0x00000004
180 #define DCACHE_OP_DELETE 0x00000008
181 #define DCACHE_OP_PRUNE 0x00000010
182
183 #define DCACHE_DISCONNECTED 0x00000020
184 /* This dentry is possibly not currently connected to the dcache tree, in
185 * which case its parent will either be itself, or will have this flag as
186 * well. nfsd will not use a dentry with this bit set, but will first
187 * endeavour to clear the bit either by discovering that it is connected,
188 * or by performing lookup operations. Any filesystem which supports
189 * nfsd_operations MUST have a lookup function which, if it finds a
190 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
191 * dentry into place and return that dentry rather than the passed one,
192 * typically using d_splice_alias. */
193
194 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
195 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */
196
197 #define DCACHE_CANT_MOUNT 0x00000100
198 #define DCACHE_GENOCIDE 0x00000200
199 #define DCACHE_SHRINK_LIST 0x00000400
200
201 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
202
203 #define DCACHE_NFSFS_RENAMED 0x00001000
204 /* this dentry has been "silly renamed" and has to be deleted on the last
205 * dput() */
206 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
207 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
208 /* Parent inode is watched by some fsnotify listener */
209
210 #define DCACHE_DENTRY_KILLED 0x00008000
211
212 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
213 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
214 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
215 #define DCACHE_MANAGED_DENTRY \
216 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
217
218 #define DCACHE_LRU_LIST 0x00080000
219
220 #define DCACHE_ENTRY_TYPE 0x00700000
221 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
222 #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
223 #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
224 #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
225 #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
226 #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
227 #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
228
229 #define DCACHE_MAY_FREE 0x00800000
230 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
231 #define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op selects inode */
232 #define DCACHE_ENCRYPTED_WITH_KEY 0x04000000 /* dir is encrypted with a valid key */
233 #define DCACHE_OP_REAL 0x08000000
234
235 extern seqlock_t rename_lock;
236
237 /*
238 * These are the low-level FS interfaces to the dcache..
239 */
240 extern void d_instantiate(struct dentry *, struct inode *);
241 extern void d_instantiate_new(struct dentry *, struct inode *);
242 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
243 extern int d_instantiate_no_diralias(struct dentry *, struct inode *);
244 extern void __d_drop(struct dentry *dentry);
245 extern void d_drop(struct dentry *dentry);
246 extern void d_delete(struct dentry *);
247 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
248
249 /* allocate/de-allocate */
250 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
251 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
252 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
253 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
254 extern struct dentry *d_find_any_alias(struct inode *inode);
255 extern struct dentry * d_obtain_alias(struct inode *);
256 extern struct dentry * d_obtain_root(struct inode *);
257 extern void shrink_dcache_sb(struct super_block *);
258 extern void shrink_dcache_parent(struct dentry *);
259 extern void shrink_dcache_for_umount(struct super_block *);
260 extern void d_invalidate(struct dentry *);
261
262 /* only used at mount-time */
263 extern struct dentry * d_make_root(struct inode *);
264
265 /* <clickety>-<click> the ramfs-type tree */
266 extern void d_genocide(struct dentry *);
267
268 extern void d_tmpfile(struct dentry *, struct inode *);
269
270 extern struct dentry *d_find_alias(struct inode *);
271 extern void d_prune_aliases(struct inode *);
272
273 /* test whether we have any submounts in a subdir tree */
274 extern int have_submounts(struct dentry *);
275
276 /*
277 * This adds the entry to the hash queues.
278 */
279 extern void d_rehash(struct dentry *);
280
281 /**
282 * d_add - add dentry to hash queues
283 * @entry: dentry to add
284 * @inode: The inode to attach to this dentry
285 *
286 * This adds the entry to the hash queues and initializes @inode.
287 * The entry was actually filled in earlier during d_alloc().
288 */
289
d_add(struct dentry * entry,struct inode * inode)290 static inline void d_add(struct dentry *entry, struct inode *inode)
291 {
292 d_instantiate(entry, inode);
293 d_rehash(entry);
294 }
295
296 /**
297 * d_add_unique - add dentry to hash queues without aliasing
298 * @entry: dentry to add
299 * @inode: The inode to attach to this dentry
300 *
301 * This adds the entry to the hash queues and initializes @inode.
302 * The entry was actually filled in earlier during d_alloc().
303 */
d_add_unique(struct dentry * entry,struct inode * inode)304 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
305 {
306 struct dentry *res;
307
308 res = d_instantiate_unique(entry, inode);
309 d_rehash(res != NULL ? res : entry);
310 return res;
311 }
312
313 extern void dentry_update_name_case(struct dentry *, struct qstr *);
314
315 /* used for rename() and baskets */
316 extern void d_move(struct dentry *, struct dentry *);
317 extern void d_exchange(struct dentry *, struct dentry *);
318 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
319
320 /* appendix may either be NULL or be used for transname suffixes */
321 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
322 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
323 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
324 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
325 const struct qstr *name, unsigned *seq);
326
d_count(const struct dentry * dentry)327 static inline unsigned d_count(const struct dentry *dentry)
328 {
329 return dentry->d_lockref.count;
330 }
331
332 /*
333 * helper function for dentry_operations.d_dname() members
334 */
335 extern __printf(4, 5)
336 char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
337 extern char *simple_dname(struct dentry *, char *, int);
338
339 extern char *__d_path(const struct path *, const struct path *, char *, int);
340 extern char *d_absolute_path(const struct path *, char *, int);
341 extern char *d_path(const struct path *, char *, int);
342 extern char *dentry_path_raw(struct dentry *, char *, int);
343 extern char *dentry_path(struct dentry *, char *, int);
344
345 /* Allocation counts.. */
346
347 /**
348 * dget, dget_dlock - get a reference to a dentry
349 * @dentry: dentry to get a reference to
350 *
351 * Given a dentry or %NULL pointer increment the reference count
352 * if appropriate and return the dentry. A dentry will not be
353 * destroyed when it has references.
354 */
dget_dlock(struct dentry * dentry)355 static inline struct dentry *dget_dlock(struct dentry *dentry)
356 {
357 if (dentry)
358 dentry->d_lockref.count++;
359 return dentry;
360 }
361
dget(struct dentry * dentry)362 static inline struct dentry *dget(struct dentry *dentry)
363 {
364 if (dentry)
365 lockref_get(&dentry->d_lockref);
366 return dentry;
367 }
368
369 extern struct dentry *dget_parent(struct dentry *dentry);
370
371 /**
372 * d_unhashed - is dentry hashed
373 * @dentry: entry to check
374 *
375 * Returns true if the dentry passed is not currently hashed.
376 */
377
d_unhashed(const struct dentry * dentry)378 static inline int d_unhashed(const struct dentry *dentry)
379 {
380 return hlist_bl_unhashed(&dentry->d_hash);
381 }
382
d_unlinked(const struct dentry * dentry)383 static inline int d_unlinked(const struct dentry *dentry)
384 {
385 return d_unhashed(dentry) && !IS_ROOT(dentry);
386 }
387
cant_mount(const struct dentry * dentry)388 static inline int cant_mount(const struct dentry *dentry)
389 {
390 return (dentry->d_flags & DCACHE_CANT_MOUNT);
391 }
392
dont_mount(struct dentry * dentry)393 static inline void dont_mount(struct dentry *dentry)
394 {
395 spin_lock(&dentry->d_lock);
396 dentry->d_flags |= DCACHE_CANT_MOUNT;
397 spin_unlock(&dentry->d_lock);
398 }
399
400 extern void dput(struct dentry *);
401
d_managed(const struct dentry * dentry)402 static inline bool d_managed(const struct dentry *dentry)
403 {
404 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
405 }
406
d_mountpoint(const struct dentry * dentry)407 static inline bool d_mountpoint(const struct dentry *dentry)
408 {
409 return dentry->d_flags & DCACHE_MOUNTED;
410 }
411
412 /*
413 * Directory cache entry type accessor functions.
414 */
__d_entry_type(const struct dentry * dentry)415 static inline unsigned __d_entry_type(const struct dentry *dentry)
416 {
417 return dentry->d_flags & DCACHE_ENTRY_TYPE;
418 }
419
d_is_miss(const struct dentry * dentry)420 static inline bool d_is_miss(const struct dentry *dentry)
421 {
422 return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
423 }
424
d_is_whiteout(const struct dentry * dentry)425 static inline bool d_is_whiteout(const struct dentry *dentry)
426 {
427 return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
428 }
429
d_can_lookup(const struct dentry * dentry)430 static inline bool d_can_lookup(const struct dentry *dentry)
431 {
432 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
433 }
434
d_is_autodir(const struct dentry * dentry)435 static inline bool d_is_autodir(const struct dentry *dentry)
436 {
437 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
438 }
439
d_is_dir(const struct dentry * dentry)440 static inline bool d_is_dir(const struct dentry *dentry)
441 {
442 return d_can_lookup(dentry) || d_is_autodir(dentry);
443 }
444
d_is_symlink(const struct dentry * dentry)445 static inline bool d_is_symlink(const struct dentry *dentry)
446 {
447 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
448 }
449
d_is_reg(const struct dentry * dentry)450 static inline bool d_is_reg(const struct dentry *dentry)
451 {
452 return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
453 }
454
d_is_special(const struct dentry * dentry)455 static inline bool d_is_special(const struct dentry *dentry)
456 {
457 return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
458 }
459
d_is_file(const struct dentry * dentry)460 static inline bool d_is_file(const struct dentry *dentry)
461 {
462 return d_is_reg(dentry) || d_is_special(dentry);
463 }
464
d_is_negative(const struct dentry * dentry)465 static inline bool d_is_negative(const struct dentry *dentry)
466 {
467 // TODO: check d_is_whiteout(dentry) also.
468 return d_is_miss(dentry);
469 }
470
d_is_positive(const struct dentry * dentry)471 static inline bool d_is_positive(const struct dentry *dentry)
472 {
473 return !d_is_negative(dentry);
474 }
475
476 /**
477 * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
478 * @dentry: The dentry in question
479 *
480 * Returns true if the dentry represents either an absent name or a name that
481 * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
482 * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
483 * fallthrough marker in an opaque directory.
484 *
485 * Note! (1) This should be used *only* by a filesystem to examine its own
486 * dentries. It should not be used to look at some other filesystem's
487 * dentries. (2) It should also be used in combination with d_inode() to get
488 * the inode. (3) The dentry may have something attached to ->d_lower and the
489 * type field of the flags may be set to something other than miss or whiteout.
490 */
d_really_is_negative(const struct dentry * dentry)491 static inline bool d_really_is_negative(const struct dentry *dentry)
492 {
493 return dentry->d_inode == NULL;
494 }
495
496 /**
497 * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
498 * @dentry: The dentry in question
499 *
500 * Returns true if the dentry represents a name that maps to an inode
501 * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
502 * that is represented on medium as a 0,0 chardev.
503 *
504 * Note! (1) This should be used *only* by a filesystem to examine its own
505 * dentries. It should not be used to look at some other filesystem's
506 * dentries. (2) It should also be used in combination with d_inode() to get
507 * the inode.
508 */
d_really_is_positive(const struct dentry * dentry)509 static inline bool d_really_is_positive(const struct dentry *dentry)
510 {
511 return dentry->d_inode != NULL;
512 }
513
simple_positive(struct dentry * dentry)514 static inline int simple_positive(struct dentry *dentry)
515 {
516 return d_really_is_positive(dentry) && !d_unhashed(dentry);
517 }
518
519 extern void d_set_fallthru(struct dentry *dentry);
520
d_is_fallthru(const struct dentry * dentry)521 static inline bool d_is_fallthru(const struct dentry *dentry)
522 {
523 return dentry->d_flags & DCACHE_FALLTHRU;
524 }
525
526
527 extern int sysctl_vfs_cache_pressure;
528
vfs_pressure_ratio(unsigned long val)529 static inline unsigned long vfs_pressure_ratio(unsigned long val)
530 {
531 return mult_frac(val, sysctl_vfs_cache_pressure, 100);
532 }
533
534 /**
535 * d_inode - Get the actual inode of this dentry
536 * @dentry: The dentry to query
537 *
538 * This is the helper normal filesystems should use to get at their own inodes
539 * in their own dentries and ignore the layering superimposed upon them.
540 */
d_inode(const struct dentry * dentry)541 static inline struct inode *d_inode(const struct dentry *dentry)
542 {
543 return dentry->d_inode;
544 }
545
546 /**
547 * d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE()
548 * @dentry: The dentry to query
549 *
550 * This is the helper normal filesystems should use to get at their own inodes
551 * in their own dentries and ignore the layering superimposed upon them.
552 */
d_inode_rcu(const struct dentry * dentry)553 static inline struct inode *d_inode_rcu(const struct dentry *dentry)
554 {
555 return ACCESS_ONCE(dentry->d_inode);
556 }
557
558 /**
559 * d_backing_inode - Get upper or lower inode we should be using
560 * @upper: The upper layer
561 *
562 * This is the helper that should be used to get at the inode that will be used
563 * if this dentry were to be opened as a file. The inode may be on the upper
564 * dentry or it may be on a lower dentry pinned by the upper.
565 *
566 * Normal filesystems should not use this to access their own inodes.
567 */
d_backing_inode(const struct dentry * upper)568 static inline struct inode *d_backing_inode(const struct dentry *upper)
569 {
570 struct inode *inode = upper->d_inode;
571
572 return inode;
573 }
574
575 /**
576 * d_backing_dentry - Get upper or lower dentry we should be using
577 * @upper: The upper layer
578 *
579 * This is the helper that should be used to get the dentry of the inode that
580 * will be used if this dentry were opened as a file. It may be the upper
581 * dentry or it may be a lower dentry pinned by the upper.
582 *
583 * Normal filesystems should not use this to access their own dentries.
584 */
d_backing_dentry(struct dentry * upper)585 static inline struct dentry *d_backing_dentry(struct dentry *upper)
586 {
587 return upper;
588 }
589
d_real(struct dentry * dentry)590 static inline struct dentry *d_real(struct dentry *dentry)
591 {
592 if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
593 return dentry->d_op->d_real(dentry, NULL);
594 else
595 return dentry;
596 }
597
vfs_select_inode(struct dentry * dentry,unsigned open_flags)598 static inline struct inode *vfs_select_inode(struct dentry *dentry,
599 unsigned open_flags)
600 {
601 struct inode *inode = d_inode(dentry);
602
603 if (inode && unlikely(dentry->d_flags & DCACHE_OP_SELECT_INODE))
604 inode = dentry->d_op->d_select_inode(dentry, open_flags);
605
606 return inode;
607 }
608
609 /**
610 * d_real_inode - Return the real inode
611 * @dentry: The dentry to query
612 *
613 * If dentry is on an union/overlay, then return the underlying, real inode.
614 * Otherwise return d_inode().
615 */
d_real_inode(struct dentry * dentry)616 static inline struct inode *d_real_inode(struct dentry *dentry)
617 {
618 return d_backing_inode(d_real(dentry));
619 }
620
621 struct name_snapshot {
622 const char *name;
623 char inline_name[DNAME_INLINE_LEN];
624 };
625 void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
626 void release_dentry_name_snapshot(struct name_snapshot *);
627
628 #endif /* __LINUX_DCACHE_H */
629