~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/include/linux/dcache.h

Version: ~ [ linux-4.20-rc2 ] ~ [ linux-4.19.1 ] ~ [ linux-4.18.18 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.80 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.136 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.163 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.125 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.60 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.31.14 ] ~ [ linux-2.6.30.10 ] ~ [ linux-2.6.29.6 ] ~ [ linux-2.6.28.10 ] ~ [ linux-2.6.27.62 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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/rculist.h>
  8 #include <linux/rculist_bl.h>
  9 #include <linux/spinlock.h>
 10 #include <linux/seqlock.h>
 11 #include <linux/cache.h>
 12 #include <linux/rcupdate.h>
 13 #include <linux/lockref.h>
 14 #include <linux/stringhash.h>
 15 #include <linux/wait.h>
 16 
 17 struct path;
 18 struct vfsmount;
 19 
 20 /*
 21  * linux/include/linux/dcache.h
 22  *
 23  * Dirent cache data structures
 24  *
 25  * (C) Copyright 1997 Thomas Schoebel-Theuer,
 26  * with heavy changes by Linus Torvalds
 27  */
 28 
 29 #define IS_ROOT(x) ((x) == (x)->d_parent)
 30 
 31 /* The hash is always the low bits of hash_len */
 32 #ifdef __LITTLE_ENDIAN
 33  #define HASH_LEN_DECLARE u32 hash; u32 len
 34  #define bytemask_from_count(cnt)       (~(~0ul << (cnt)*8))
 35 #else
 36  #define HASH_LEN_DECLARE u32 len; u32 hash
 37  #define bytemask_from_count(cnt)       (~(~0ul >> (cnt)*8))
 38 #endif
 39 
 40 /*
 41  * "quick string" -- eases parameter passing, but more importantly
 42  * saves "metadata" about the string (ie length and the hash).
 43  *
 44  * hash comes first so it snuggles against d_parent in the
 45  * dentry.
 46  */
 47 struct qstr {
 48         union {
 49                 struct {
 50                         HASH_LEN_DECLARE;
 51                 };
 52                 u64 hash_len;
 53         };
 54         const unsigned char *name;
 55 };
 56 
 57 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
 58 
 59 extern const struct qstr empty_name;
 60 extern const struct qstr slash_name;
 61 
 62 struct dentry_stat_t {
 63         long nr_dentry;
 64         long nr_unused;
 65         long age_limit;          /* age in seconds */
 66         long want_pages;         /* pages requested by system */
 67         long dummy[2];
 68 };
 69 extern struct dentry_stat_t dentry_stat;
 70 
 71 /*
 72  * Try to keep struct dentry aligned on 64 byte cachelines (this will
 73  * give reasonable cacheline footprint with larger lines without the
 74  * large memory footprint increase).
 75  */
 76 #ifdef CONFIG_64BIT
 77 # define DNAME_INLINE_LEN 32 /* 192 bytes */
 78 #else
 79 # ifdef CONFIG_SMP
 80 #  define DNAME_INLINE_LEN 36 /* 128 bytes */
 81 # else
 82 #  define DNAME_INLINE_LEN 40 /* 128 bytes */
 83 # endif
 84 #endif
 85 
 86 #define d_lock  d_lockref.lock
 87 
 88 struct dentry {
 89         /* RCU lookup touched fields */
 90         unsigned int d_flags;           /* protected by d_lock */
 91         seqcount_t d_seq;               /* per dentry seqlock */
 92         struct hlist_bl_node d_hash;    /* lookup hash list */
 93         struct dentry *d_parent;        /* parent directory */
 94         struct qstr d_name;
 95         struct inode *d_inode;          /* Where the name belongs to - NULL is
 96                                          * negative */
 97         unsigned char d_iname[DNAME_INLINE_LEN];        /* small names */
 98 
 99         /* Ref lookup also touches following */
100         struct lockref d_lockref;       /* per-dentry lock and refcount */
101         const struct dentry_operations *d_op;
102         struct super_block *d_sb;       /* The root of the dentry tree */
103         unsigned long d_time;           /* used by d_revalidate */
104         void *d_fsdata;                 /* fs-specific data */
105 
106         union {
107                 struct list_head d_lru;         /* LRU list */
108                 wait_queue_head_t *d_wait;      /* in-lookup ones only */
109         };
110         struct list_head d_child;       /* child of parent list */
111         struct list_head d_subdirs;     /* our children */
112         /*
113          * d_alias and d_rcu can share memory
114          */
115         union {
116                 struct hlist_node d_alias;      /* inode alias list */
117                 struct hlist_bl_node d_in_lookup_hash;  /* only for in-lookup ones */
118                 struct rcu_head d_rcu;
119         } d_u;
120 } __randomize_layout;
121 
122 /*
123  * dentry->d_lock spinlock nesting subclasses:
124  *
125  * 0: normal
126  * 1: nested
127  */
128 enum dentry_d_lock_class
129 {
130         DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
131         DENTRY_D_LOCK_NESTED
132 };
133 
134 struct dentry_operations {
135         int (*d_revalidate)(struct dentry *, unsigned int);
136         int (*d_weak_revalidate)(struct dentry *, unsigned int);
137         int (*d_hash)(const struct dentry *, struct qstr *);
138         int (*d_compare)(const struct dentry *,
139                         unsigned int, const char *, const struct qstr *);
140         int (*d_delete)(const struct dentry *);
141         int (*d_init)(struct dentry *);
142         void (*d_release)(struct dentry *);
143         void (*d_prune)(struct dentry *);
144         void (*d_iput)(struct dentry *, struct inode *);
145         char *(*d_dname)(struct dentry *, char *, int);
146         struct vfsmount *(*d_automount)(struct path *);
147         int (*d_manage)(const struct path *, bool);
148         struct dentry *(*d_real)(struct dentry *, const struct inode *);
149 } ____cacheline_aligned;
150 
151 /*
152  * Locking rules for dentry_operations callbacks are to be found in
153  * Documentation/filesystems/Locking. Keep it updated!
154  *
155  * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
156  * Keep it updated too!
157  */
158 
159 /* d_flags entries */
160 #define DCACHE_OP_HASH                  0x00000001
161 #define DCACHE_OP_COMPARE               0x00000002
162 #define DCACHE_OP_REVALIDATE            0x00000004
163 #define DCACHE_OP_DELETE                0x00000008
164 #define DCACHE_OP_PRUNE                 0x00000010
165 
166 #define DCACHE_DISCONNECTED             0x00000020
167      /* This dentry is possibly not currently connected to the dcache tree, in
168       * which case its parent will either be itself, or will have this flag as
169       * well.  nfsd will not use a dentry with this bit set, but will first
170       * endeavour to clear the bit either by discovering that it is connected,
171       * or by performing lookup operations.   Any filesystem which supports
172       * nfsd_operations MUST have a lookup function which, if it finds a
173       * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
174       * dentry into place and return that dentry rather than the passed one,
175       * typically using d_splice_alias. */
176 
177 #define DCACHE_REFERENCED               0x00000040 /* Recently used, don't discard. */
178 #define DCACHE_RCUACCESS                0x00000080 /* Entry has ever been RCU-visible */
179 
180 #define DCACHE_CANT_MOUNT               0x00000100
181 #define DCACHE_GENOCIDE                 0x00000200
182 #define DCACHE_SHRINK_LIST              0x00000400
183 
184 #define DCACHE_OP_WEAK_REVALIDATE       0x00000800
185 
186 #define DCACHE_NFSFS_RENAMED            0x00001000
187      /* this dentry has been "silly renamed" and has to be deleted on the last
188       * dput() */
189 #define DCACHE_COOKIE                   0x00002000 /* For use by dcookie subsystem */
190 #define DCACHE_FSNOTIFY_PARENT_WATCHED  0x00004000
191      /* Parent inode is watched by some fsnotify listener */
192 
193 #define DCACHE_DENTRY_KILLED            0x00008000
194 
195 #define DCACHE_MOUNTED                  0x00010000 /* is a mountpoint */
196 #define DCACHE_NEED_AUTOMOUNT           0x00020000 /* handle automount on this dir */
197 #define DCACHE_MANAGE_TRANSIT           0x00040000 /* manage transit from this dirent */
198 #define DCACHE_MANAGED_DENTRY \
199         (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
200 
201 #define DCACHE_LRU_LIST                 0x00080000
202 
203 #define DCACHE_ENTRY_TYPE               0x00700000
204 #define DCACHE_MISS_TYPE                0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
205 #define DCACHE_WHITEOUT_TYPE            0x00100000 /* Whiteout dentry (stop pathwalk) */
206 #define DCACHE_DIRECTORY_TYPE           0x00200000 /* Normal directory */
207 #define DCACHE_AUTODIR_TYPE             0x00300000 /* Lookupless directory (presumed automount) */
208 #define DCACHE_REGULAR_TYPE             0x00400000 /* Regular file type (or fallthru to such) */
209 #define DCACHE_SPECIAL_TYPE             0x00500000 /* Other file type (or fallthru to such) */
210 #define DCACHE_SYMLINK_TYPE             0x00600000 /* Symlink (or fallthru to such) */
211 
212 #define DCACHE_MAY_FREE                 0x00800000
213 #define DCACHE_FALLTHRU                 0x01000000 /* Fall through to lower layer */
214 #define DCACHE_ENCRYPTED_WITH_KEY       0x02000000 /* dir is encrypted with a valid key */
215 #define DCACHE_OP_REAL                  0x04000000
216 
217 #define DCACHE_PAR_LOOKUP               0x10000000 /* being looked up (with parent locked shared) */
218 #define DCACHE_DENTRY_CURSOR            0x20000000
219 
220 extern seqlock_t rename_lock;
221 
222 /*
223  * These are the low-level FS interfaces to the dcache..
224  */
225 extern void d_instantiate(struct dentry *, struct inode *);
226 extern void d_instantiate_new(struct dentry *, struct inode *);
227 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
228 extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
229 extern void __d_drop(struct dentry *dentry);
230 extern void d_drop(struct dentry *dentry);
231 extern void d_delete(struct dentry *);
232 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
233 
234 /* allocate/de-allocate */
235 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
236 extern struct dentry * d_alloc_anon(struct super_block *);
237 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
238 extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
239                                         wait_queue_head_t *);
240 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
241 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
242 extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
243 extern struct dentry *d_find_any_alias(struct inode *inode);
244 extern struct dentry * d_obtain_alias(struct inode *);
245 extern struct dentry * d_obtain_root(struct inode *);
246 extern void shrink_dcache_sb(struct super_block *);
247 extern void shrink_dcache_parent(struct dentry *);
248 extern void shrink_dcache_for_umount(struct super_block *);
249 extern void d_invalidate(struct dentry *);
250 
251 /* only used at mount-time */
252 extern struct dentry * d_make_root(struct inode *);
253 
254 /* <clickety>-<click> the ramfs-type tree */
255 extern void d_genocide(struct dentry *);
256 
257 extern void d_tmpfile(struct dentry *, struct inode *);
258 
259 extern struct dentry *d_find_alias(struct inode *);
260 extern void d_prune_aliases(struct inode *);
261 
262 /* test whether we have any submounts in a subdir tree */
263 extern int path_has_submounts(const struct path *);
264 
265 /*
266  * This adds the entry to the hash queues.
267  */
268 extern void d_rehash(struct dentry *);
269  
270 extern void d_add(struct dentry *, struct inode *);
271 
272 /* used for rename() and baskets */
273 extern void d_move(struct dentry *, struct dentry *);
274 extern void d_exchange(struct dentry *, struct dentry *);
275 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
276 
277 /* appendix may either be NULL or be used for transname suffixes */
278 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
279 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
280 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
281 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
282                                 const struct qstr *name, unsigned *seq);
283 
284 static inline unsigned d_count(const struct dentry *dentry)
285 {
286         return dentry->d_lockref.count;
287 }
288 
289 /*
290  * helper function for dentry_operations.d_dname() members
291  */
292 extern __printf(4, 5)
293 char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
294 extern char *simple_dname(struct dentry *, char *, int);
295 
296 extern char *__d_path(const struct path *, const struct path *, char *, int);
297 extern char *d_absolute_path(const struct path *, char *, int);
298 extern char *d_path(const struct path *, char *, int);
299 extern char *dentry_path_raw(struct dentry *, char *, int);
300 extern char *dentry_path(struct dentry *, char *, int);
301 
302 /* Allocation counts.. */
303 
304 /**
305  *      dget, dget_dlock -      get a reference to a dentry
306  *      @dentry: dentry to get a reference to
307  *
308  *      Given a dentry or %NULL pointer increment the reference count
309  *      if appropriate and return the dentry. A dentry will not be 
310  *      destroyed when it has references.
311  */
312 static inline struct dentry *dget_dlock(struct dentry *dentry)
313 {
314         if (dentry)
315                 dentry->d_lockref.count++;
316         return dentry;
317 }
318 
319 static inline struct dentry *dget(struct dentry *dentry)
320 {
321         if (dentry)
322                 lockref_get(&dentry->d_lockref);
323         return dentry;
324 }
325 
326 extern struct dentry *dget_parent(struct dentry *dentry);
327 
328 /**
329  *      d_unhashed -    is dentry hashed
330  *      @dentry: entry to check
331  *
332  *      Returns true if the dentry passed is not currently hashed.
333  */
334  
335 static inline int d_unhashed(const struct dentry *dentry)
336 {
337         return hlist_bl_unhashed(&dentry->d_hash);
338 }
339 
340 static inline int d_unlinked(const struct dentry *dentry)
341 {
342         return d_unhashed(dentry) && !IS_ROOT(dentry);
343 }
344 
345 static inline int cant_mount(const struct dentry *dentry)
346 {
347         return (dentry->d_flags & DCACHE_CANT_MOUNT);
348 }
349 
350 static inline void dont_mount(struct dentry *dentry)
351 {
352         spin_lock(&dentry->d_lock);
353         dentry->d_flags |= DCACHE_CANT_MOUNT;
354         spin_unlock(&dentry->d_lock);
355 }
356 
357 extern void __d_lookup_done(struct dentry *);
358 
359 static inline int d_in_lookup(const struct dentry *dentry)
360 {
361         return dentry->d_flags & DCACHE_PAR_LOOKUP;
362 }
363 
364 static inline void d_lookup_done(struct dentry *dentry)
365 {
366         if (unlikely(d_in_lookup(dentry))) {
367                 spin_lock(&dentry->d_lock);
368                 __d_lookup_done(dentry);
369                 spin_unlock(&dentry->d_lock);
370         }
371 }
372 
373 extern void dput(struct dentry *);
374 
375 static inline bool d_managed(const struct dentry *dentry)
376 {
377         return dentry->d_flags & DCACHE_MANAGED_DENTRY;
378 }
379 
380 static inline bool d_mountpoint(const struct dentry *dentry)
381 {
382         return dentry->d_flags & DCACHE_MOUNTED;
383 }
384 
385 /*
386  * Directory cache entry type accessor functions.
387  */
388 static inline unsigned __d_entry_type(const struct dentry *dentry)
389 {
390         return dentry->d_flags & DCACHE_ENTRY_TYPE;
391 }
392 
393 static inline bool d_is_miss(const struct dentry *dentry)
394 {
395         return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
396 }
397 
398 static inline bool d_is_whiteout(const struct dentry *dentry)
399 {
400         return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE;
401 }
402 
403 static inline bool d_can_lookup(const struct dentry *dentry)
404 {
405         return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
406 }
407 
408 static inline bool d_is_autodir(const struct dentry *dentry)
409 {
410         return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
411 }
412 
413 static inline bool d_is_dir(const struct dentry *dentry)
414 {
415         return d_can_lookup(dentry) || d_is_autodir(dentry);
416 }
417 
418 static inline bool d_is_symlink(const struct dentry *dentry)
419 {
420         return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
421 }
422 
423 static inline bool d_is_reg(const struct dentry *dentry)
424 {
425         return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE;
426 }
427 
428 static inline bool d_is_special(const struct dentry *dentry)
429 {
430         return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE;
431 }
432 
433 static inline bool d_is_file(const struct dentry *dentry)
434 {
435         return d_is_reg(dentry) || d_is_special(dentry);
436 }
437 
438 static inline bool d_is_negative(const struct dentry *dentry)
439 {
440         // TODO: check d_is_whiteout(dentry) also.
441         return d_is_miss(dentry);
442 }
443 
444 static inline bool d_is_positive(const struct dentry *dentry)
445 {
446         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         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         return dentry->d_inode != NULL;
485 }
486 
487 static inline int simple_positive(const struct dentry *dentry)
488 {
489         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         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         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         struct inode *inode = upper->d_inode;
544 
545         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.txt
572  */
573 static inline struct dentry *d_real(struct dentry *dentry,
574                                     const struct inode *inode)
575 {
576         if (unlikely(dentry->d_flags & DCACHE_OP_REAL))
577                 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         const unsigned char *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 */
603 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp