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 40 /* 192 bytes */ |
72 | #else |
73 | # ifdef CONFIG_SMP |
74 | # define DNAME_INLINE_LEN 40 /* 128 bytes */ |
75 | # else |
76 | # define DNAME_INLINE_LEN 44 /* 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 hlist_node d_sib; /* child of parent list */ |
105 | struct hlist_head d_children; /* 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 | }; |
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 | enum d_real_type { |
129 | D_REAL_DATA, |
130 | D_REAL_METADATA, |
131 | }; |
132 | |
133 | struct dentry_operations { |
134 | int (*d_revalidate)(struct dentry *, unsigned int); |
135 | int (*d_weak_revalidate)(struct dentry *, unsigned int); |
136 | int (*d_hash)(const struct dentry *, struct qstr *); |
137 | int (*d_compare)(const struct dentry *, |
138 | unsigned int, const char *, const struct qstr *); |
139 | int (*d_delete)(const struct dentry *); |
140 | int (*d_init)(struct dentry *); |
141 | void (*d_release)(struct dentry *); |
142 | void (*d_prune)(struct dentry *); |
143 | void (*d_iput)(struct dentry *, struct inode *); |
144 | char *(*d_dname)(struct dentry *, char *, int); |
145 | struct vfsmount *(*d_automount)(struct path *); |
146 | int (*d_manage)(const struct path *, bool); |
147 | struct dentry *(*d_real)(struct dentry *, enum d_real_type type); |
148 | } ____cacheline_aligned; |
149 | |
150 | /* |
151 | * Locking rules for dentry_operations callbacks are to be found in |
152 | * Documentation/filesystems/locking.rst. Keep it updated! |
153 | * |
154 | * FUrther descriptions are found in Documentation/filesystems/vfs.rst. |
155 | * Keep it updated too! |
156 | */ |
157 | |
158 | /* d_flags entries */ |
159 | #define DCACHE_OP_HASH BIT(0) |
160 | #define DCACHE_OP_COMPARE BIT(1) |
161 | #define DCACHE_OP_REVALIDATE BIT(2) |
162 | #define DCACHE_OP_DELETE BIT(3) |
163 | #define DCACHE_OP_PRUNE BIT(4) |
164 | |
165 | #define DCACHE_DISCONNECTED BIT(5) |
166 | /* This dentry is possibly not currently connected to the dcache tree, in |
167 | * which case its parent will either be itself, or will have this flag as |
168 | * well. nfsd will not use a dentry with this bit set, but will first |
169 | * endeavour to clear the bit either by discovering that it is connected, |
170 | * or by performing lookup operations. Any filesystem which supports |
171 | * nfsd_operations MUST have a lookup function which, if it finds a |
172 | * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that |
173 | * dentry into place and return that dentry rather than the passed one, |
174 | * typically using d_splice_alias. */ |
175 | |
176 | #define DCACHE_REFERENCED BIT(6) /* Recently used, don't discard. */ |
177 | |
178 | #define DCACHE_DONTCACHE BIT(7) /* Purge from memory on final dput() */ |
179 | |
180 | #define DCACHE_CANT_MOUNT BIT(8) |
181 | #define DCACHE_GENOCIDE BIT(9) |
182 | #define DCACHE_SHRINK_LIST BIT(10) |
183 | |
184 | #define DCACHE_OP_WEAK_REVALIDATE BIT(11) |
185 | |
186 | #define DCACHE_NFSFS_RENAMED BIT(12) |
187 | /* this dentry has been "silly renamed" and has to be deleted on the last |
188 | * dput() */ |
189 | #define DCACHE_FSNOTIFY_PARENT_WATCHED BIT(14) |
190 | /* Parent inode is watched by some fsnotify listener */ |
191 | |
192 | #define DCACHE_DENTRY_KILLED BIT(15) |
193 | |
194 | #define DCACHE_MOUNTED BIT(16) /* is a mountpoint */ |
195 | #define DCACHE_NEED_AUTOMOUNT BIT(17) /* handle automount on this dir */ |
196 | #define DCACHE_MANAGE_TRANSIT BIT(18) /* manage transit from this dirent */ |
197 | #define DCACHE_MANAGED_DENTRY \ |
198 | (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) |
199 | |
200 | #define DCACHE_LRU_LIST BIT(19) |
201 | |
202 | #define DCACHE_ENTRY_TYPE (7 << 20) /* bits 20..22 are for storing type: */ |
203 | #define DCACHE_MISS_TYPE (0 << 20) /* Negative dentry */ |
204 | #define DCACHE_WHITEOUT_TYPE (1 << 20) /* Whiteout dentry (stop pathwalk) */ |
205 | #define DCACHE_DIRECTORY_TYPE (2 << 20) /* Normal directory */ |
206 | #define DCACHE_AUTODIR_TYPE (3 << 20) /* Lookupless directory (presumed automount) */ |
207 | #define DCACHE_REGULAR_TYPE (4 << 20) /* Regular file type */ |
208 | #define DCACHE_SPECIAL_TYPE (5 << 20) /* Other file type */ |
209 | #define DCACHE_SYMLINK_TYPE (6 << 20) /* Symlink */ |
210 | |
211 | #define DCACHE_NOKEY_NAME BIT(25) /* Encrypted name encoded without key */ |
212 | #define DCACHE_OP_REAL BIT(26) |
213 | |
214 | #define DCACHE_PAR_LOOKUP BIT(28) /* being looked up (with parent locked shared) */ |
215 | #define DCACHE_DENTRY_CURSOR BIT(29) |
216 | #define DCACHE_NORCU BIT(30) /* No RCU delay for freeing */ |
217 | |
218 | extern seqlock_t rename_lock; |
219 | |
220 | /* |
221 | * These are the low-level FS interfaces to the dcache.. |
222 | */ |
223 | extern void d_instantiate(struct dentry *, struct inode *); |
224 | extern void d_instantiate_new(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 d_invalidate(struct dentry *); |
246 | |
247 | /* only used at mount-time */ |
248 | extern struct dentry * d_make_root(struct inode *); |
249 | |
250 | extern void d_mark_tmpfile(struct file *, struct inode *); |
251 | extern void d_tmpfile(struct file *, struct inode *); |
252 | |
253 | extern struct dentry *d_find_alias(struct inode *); |
254 | extern void d_prune_aliases(struct inode *); |
255 | |
256 | extern struct dentry *d_find_alias_rcu(struct inode *); |
257 | |
258 | /* test whether we have any submounts in a subdir tree */ |
259 | extern int path_has_submounts(const struct path *); |
260 | |
261 | /* |
262 | * This adds the entry to the hash queues. |
263 | */ |
264 | extern void d_rehash(struct dentry *); |
265 | |
266 | extern void d_add(struct dentry *, struct inode *); |
267 | |
268 | /* used for rename() and baskets */ |
269 | extern void d_move(struct dentry *, struct dentry *); |
270 | extern void d_exchange(struct dentry *, struct dentry *); |
271 | extern struct dentry *d_ancestor(struct dentry *, struct dentry *); |
272 | |
273 | extern struct dentry *d_lookup(const struct dentry *, const struct qstr *); |
274 | extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); |
275 | |
276 | static inline unsigned d_count(const struct dentry *dentry) |
277 | { |
278 | return dentry->d_lockref.count; |
279 | } |
280 | |
281 | /* |
282 | * helper function for dentry_operations.d_dname() members |
283 | */ |
284 | extern __printf(3, 4) |
285 | char *dynamic_dname(char *, int, const char *, ...); |
286 | |
287 | extern char *__d_path(const struct path *, const struct path *, char *, int); |
288 | extern char *d_absolute_path(const struct path *, char *, int); |
289 | extern char *d_path(const struct path *, char *, int); |
290 | extern char *dentry_path_raw(const struct dentry *, char *, int); |
291 | extern char *dentry_path(const struct dentry *, char *, int); |
292 | |
293 | /* Allocation counts.. */ |
294 | |
295 | /** |
296 | * dget_dlock - get a reference to a dentry |
297 | * @dentry: dentry to get a reference to |
298 | * |
299 | * Given a live dentry, increment the reference count and return the dentry. |
300 | * Caller must hold @dentry->d_lock. Making sure that dentry is alive is |
301 | * caller's resonsibility. There are many conditions sufficient to guarantee |
302 | * that; e.g. anything with non-negative refcount is alive, so's anything |
303 | * hashed, anything positive, anyone's parent, etc. |
304 | */ |
305 | static inline struct dentry *dget_dlock(struct dentry *dentry) |
306 | { |
307 | dentry->d_lockref.count++; |
308 | return dentry; |
309 | } |
310 | |
311 | |
312 | /** |
313 | * dget - 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. Conversely, a dentry with |
319 | * no references can disappear for any number of reasons, starting |
320 | * with memory pressure. In other words, that primitive is |
321 | * used to clone an existing reference; using it on something with |
322 | * zero refcount is a bug. |
323 | * |
324 | * NOTE: it will spin if @dentry->d_lock is held. From the deadlock |
325 | * avoidance point of view it is equivalent to spin_lock()/increment |
326 | * refcount/spin_unlock(), so calling it under @dentry->d_lock is |
327 | * always a bug; so's calling it under ->d_lock on any of its descendents. |
328 | * |
329 | */ |
330 | static inline struct dentry *dget(struct dentry *dentry) |
331 | { |
332 | if (dentry) |
333 | lockref_get(&dentry->d_lockref); |
334 | return dentry; |
335 | } |
336 | |
337 | extern struct dentry *dget_parent(struct dentry *dentry); |
338 | |
339 | /** |
340 | * d_unhashed - is dentry hashed |
341 | * @dentry: entry to check |
342 | * |
343 | * Returns true if the dentry passed is not currently hashed. |
344 | */ |
345 | static inline int d_unhashed(const struct dentry *dentry) |
346 | { |
347 | return hlist_bl_unhashed(h: &dentry->d_hash); |
348 | } |
349 | |
350 | static inline int d_unlinked(const struct dentry *dentry) |
351 | { |
352 | return d_unhashed(dentry) && !IS_ROOT(dentry); |
353 | } |
354 | |
355 | static inline int cant_mount(const struct dentry *dentry) |
356 | { |
357 | return (dentry->d_flags & DCACHE_CANT_MOUNT); |
358 | } |
359 | |
360 | static inline void dont_mount(struct dentry *dentry) |
361 | { |
362 | spin_lock(lock: &dentry->d_lock); |
363 | dentry->d_flags |= DCACHE_CANT_MOUNT; |
364 | spin_unlock(lock: &dentry->d_lock); |
365 | } |
366 | |
367 | extern void __d_lookup_unhash_wake(struct dentry *dentry); |
368 | |
369 | static inline int d_in_lookup(const struct dentry *dentry) |
370 | { |
371 | return dentry->d_flags & DCACHE_PAR_LOOKUP; |
372 | } |
373 | |
374 | static inline void d_lookup_done(struct dentry *dentry) |
375 | { |
376 | if (unlikely(d_in_lookup(dentry))) |
377 | __d_lookup_unhash_wake(dentry); |
378 | } |
379 | |
380 | extern void dput(struct dentry *); |
381 | |
382 | static inline bool d_managed(const struct dentry *dentry) |
383 | { |
384 | return dentry->d_flags & DCACHE_MANAGED_DENTRY; |
385 | } |
386 | |
387 | static inline bool d_mountpoint(const struct dentry *dentry) |
388 | { |
389 | return dentry->d_flags & DCACHE_MOUNTED; |
390 | } |
391 | |
392 | /* |
393 | * Directory cache entry type accessor functions. |
394 | */ |
395 | static inline unsigned __d_entry_type(const struct dentry *dentry) |
396 | { |
397 | return dentry->d_flags & DCACHE_ENTRY_TYPE; |
398 | } |
399 | |
400 | static inline bool d_is_miss(const struct dentry *dentry) |
401 | { |
402 | return __d_entry_type(dentry) == DCACHE_MISS_TYPE; |
403 | } |
404 | |
405 | static inline bool d_is_whiteout(const struct dentry *dentry) |
406 | { |
407 | return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE; |
408 | } |
409 | |
410 | static inline bool d_can_lookup(const struct dentry *dentry) |
411 | { |
412 | return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; |
413 | } |
414 | |
415 | static inline bool d_is_autodir(const struct dentry *dentry) |
416 | { |
417 | return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; |
418 | } |
419 | |
420 | static inline bool d_is_dir(const struct dentry *dentry) |
421 | { |
422 | return d_can_lookup(dentry) || d_is_autodir(dentry); |
423 | } |
424 | |
425 | static inline bool d_is_symlink(const struct dentry *dentry) |
426 | { |
427 | return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; |
428 | } |
429 | |
430 | static inline bool d_is_reg(const struct dentry *dentry) |
431 | { |
432 | return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE; |
433 | } |
434 | |
435 | static inline bool d_is_special(const struct dentry *dentry) |
436 | { |
437 | return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE; |
438 | } |
439 | |
440 | static inline bool d_is_file(const struct dentry *dentry) |
441 | { |
442 | return d_is_reg(dentry) || d_is_special(dentry); |
443 | } |
444 | |
445 | static inline bool d_is_negative(const struct dentry *dentry) |
446 | { |
447 | // TODO: check d_is_whiteout(dentry) also. |
448 | return d_is_miss(dentry); |
449 | } |
450 | |
451 | static inline bool d_flags_negative(unsigned flags) |
452 | { |
453 | return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE; |
454 | } |
455 | |
456 | static inline bool d_is_positive(const struct dentry *dentry) |
457 | { |
458 | return !d_is_negative(dentry); |
459 | } |
460 | |
461 | /** |
462 | * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs) |
463 | * @dentry: The dentry in question |
464 | * |
465 | * Returns true if the dentry represents either an absent name or a name that |
466 | * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent |
467 | * a true miss, a whiteout that isn't represented by a 0,0 chardev or a |
468 | * fallthrough marker in an opaque directory. |
469 | * |
470 | * Note! (1) This should be used *only* by a filesystem to examine its own |
471 | * dentries. It should not be used to look at some other filesystem's |
472 | * dentries. (2) It should also be used in combination with d_inode() to get |
473 | * the inode. (3) The dentry may have something attached to ->d_lower and the |
474 | * type field of the flags may be set to something other than miss or whiteout. |
475 | */ |
476 | static inline bool d_really_is_negative(const struct dentry *dentry) |
477 | { |
478 | return dentry->d_inode == NULL; |
479 | } |
480 | |
481 | /** |
482 | * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs) |
483 | * @dentry: The dentry in question |
484 | * |
485 | * Returns true if the dentry represents a name that maps to an inode |
486 | * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if |
487 | * that is represented on medium as a 0,0 chardev. |
488 | * |
489 | * Note! (1) This should be used *only* by a filesystem to examine its own |
490 | * dentries. It should not be used to look at some other filesystem's |
491 | * dentries. (2) It should also be used in combination with d_inode() to get |
492 | * the inode. |
493 | */ |
494 | static inline bool d_really_is_positive(const struct dentry *dentry) |
495 | { |
496 | return dentry->d_inode != NULL; |
497 | } |
498 | |
499 | static inline int simple_positive(const struct dentry *dentry) |
500 | { |
501 | return d_really_is_positive(dentry) && !d_unhashed(dentry); |
502 | } |
503 | |
504 | extern int sysctl_vfs_cache_pressure; |
505 | |
506 | static inline unsigned long vfs_pressure_ratio(unsigned long val) |
507 | { |
508 | return mult_frac(val, sysctl_vfs_cache_pressure, 100); |
509 | } |
510 | |
511 | /** |
512 | * d_inode - Get the actual inode of this dentry |
513 | * @dentry: The dentry to query |
514 | * |
515 | * This is the helper normal filesystems should use to get at their own inodes |
516 | * in their own dentries and ignore the layering superimposed upon them. |
517 | */ |
518 | static inline struct inode *d_inode(const struct dentry *dentry) |
519 | { |
520 | return dentry->d_inode; |
521 | } |
522 | |
523 | /** |
524 | * d_inode_rcu - Get the actual inode of this dentry with READ_ONCE() |
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 | */ |
530 | static inline struct inode *d_inode_rcu(const struct dentry *dentry) |
531 | { |
532 | return READ_ONCE(dentry->d_inode); |
533 | } |
534 | |
535 | /** |
536 | * d_backing_inode - Get upper or lower inode we should be using |
537 | * @upper: The upper layer |
538 | * |
539 | * This is the helper that should be used to get at the inode that will be used |
540 | * if this dentry were to be opened as a file. The inode may be on the upper |
541 | * dentry or it may be on a lower dentry pinned by the upper. |
542 | * |
543 | * Normal filesystems should not use this to access their own inodes. |
544 | */ |
545 | static inline struct inode *d_backing_inode(const struct dentry *upper) |
546 | { |
547 | struct inode *inode = upper->d_inode; |
548 | |
549 | return inode; |
550 | } |
551 | |
552 | /** |
553 | * d_real - Return the real dentry |
554 | * @dentry: the dentry to query |
555 | * @type: the type of real dentry (data or metadata) |
556 | * |
557 | * If dentry is on a union/overlay, then return the underlying, real dentry. |
558 | * Otherwise return the dentry itself. |
559 | * |
560 | * See also: Documentation/filesystems/vfs.rst |
561 | */ |
562 | static inline struct dentry *d_real(struct dentry *dentry, enum d_real_type type) |
563 | { |
564 | if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) |
565 | return dentry->d_op->d_real(dentry, type); |
566 | else |
567 | return dentry; |
568 | } |
569 | |
570 | /** |
571 | * d_real_inode - Return the real inode hosting the data |
572 | * @dentry: The dentry to query |
573 | * |
574 | * If dentry is on a union/overlay, then return the underlying, real inode. |
575 | * Otherwise return d_inode(). |
576 | */ |
577 | static inline struct inode *d_real_inode(const struct dentry *dentry) |
578 | { |
579 | /* This usage of d_real() results in const dentry */ |
580 | return d_inode(dentry: d_real(dentry: (struct dentry *) dentry, type: D_REAL_DATA)); |
581 | } |
582 | |
583 | struct name_snapshot { |
584 | struct qstr name; |
585 | unsigned char inline_name[DNAME_INLINE_LEN]; |
586 | }; |
587 | void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *); |
588 | void release_dentry_name_snapshot(struct name_snapshot *); |
589 | |
590 | static inline struct dentry *d_first_child(const struct dentry *dentry) |
591 | { |
592 | return hlist_entry_safe(dentry->d_children.first, struct dentry, d_sib); |
593 | } |
594 | |
595 | static inline struct dentry *d_next_sibling(const struct dentry *dentry) |
596 | { |
597 | return hlist_entry_safe(dentry->d_sib.next, struct dentry, d_sib); |
598 | } |
599 | |
600 | #endif /* __LINUX_DCACHE_H */ |
601 | |