1 #ifndef __LINUX_DCACHE_H
2 #define __LINUX_DCACHE_H
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>
18 * linux/include/linux/dcache.h
20 * Dirent cache data structures
22 * (C) Copyright 1997 Thomas Schoebel-Theuer,
23 * with heavy changes by Linus Torvalds
26 #define IS_ROOT(x) ((x) == (x)->d_parent)
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))
33 #define HASH_LEN_DECLARE u32 len; u32 hash
34 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
38 * "quick string" -- eases parameter passing, but more importantly
39 * saves "metadata" about the string (ie length and the hash).
41 * hash comes first so it snuggles against d_parent in the
51 const unsigned char *name
;
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))
59 struct dentry_stat_t
{
62 long age_limit
; /* age in seconds */
63 long want_pages
; /* pages requested by system */
66 extern struct dentry_stat_t dentry_stat
;
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
72 /* partial hash update function. Assume roughly 4 bits per character */
73 static inline unsigned long
74 partial_name_hash(unsigned long c
, unsigned long prevhash
)
76 return (prevhash
+ (c
<< 4) + (c
>> 4)) * 11;
80 * Finally: cut down the number of bits to a int value (and try to avoid
83 static inline unsigned long end_name_hash(unsigned long hash
)
85 return (unsigned int) hash
;
88 /* Compute the hash for a name string. */
89 extern unsigned int full_name_hash(const unsigned char *, unsigned int);
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).
97 # define DNAME_INLINE_LEN 32 /* 192 bytes */
100 # define DNAME_INLINE_LEN 36 /* 128 bytes */
102 # define DNAME_INLINE_LEN 40 /* 128 bytes */
106 #define d_lock d_lockref.lock
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 */
115 struct inode
*d_inode
; /* Where the name belongs to - NULL is
117 unsigned char d_iname
[DNAME_INLINE_LEN
]; /* small names */
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 */
127 struct list_head d_lru
; /* LRU list */
128 wait_queue_head_t
*d_wait
; /* in-lookup ones only */
130 struct list_head d_child
; /* child of parent list */
131 struct list_head d_subdirs
; /* our children */
133 * d_alias and d_rcu can share memory
136 struct hlist_node d_alias
; /* inode alias list */
137 struct hlist_bl_node d_in_lookup_hash
; /* only for in-lookup ones */
138 struct rcu_head d_rcu
;
143 * dentry->d_lock spinlock nesting subclasses:
148 enum dentry_d_lock_class
150 DENTRY_D_LOCK_NORMAL
, /* implicitly used by plain spin_lock() APIs. */
154 struct dentry_operations
{
155 int (*d_revalidate
)(struct dentry
*, unsigned int);
156 int (*d_weak_revalidate
)(struct dentry
*, unsigned int);
157 int (*d_hash
)(const struct dentry
*, struct qstr
*);
158 int (*d_compare
)(const struct dentry
*, const struct dentry
*,
159 unsigned int, const char *, const struct qstr
*);
160 int (*d_delete
)(const struct dentry
*);
161 void (*d_release
)(struct dentry
*);
162 void (*d_prune
)(struct dentry
*);
163 void (*d_iput
)(struct dentry
*, struct inode
*);
164 char *(*d_dname
)(struct dentry
*, char *, int);
165 struct vfsmount
*(*d_automount
)(struct path
*);
166 int (*d_manage
)(struct dentry
*, bool);
167 struct inode
*(*d_select_inode
)(struct dentry
*, unsigned);
168 struct dentry
*(*d_real
)(struct dentry
*, struct inode
*);
169 } ____cacheline_aligned
;
172 * Locking rules for dentry_operations callbacks are to be found in
173 * Documentation/filesystems/Locking. Keep it updated!
175 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
176 * Keep it updated too!
179 /* d_flags entries */
180 #define DCACHE_OP_HASH 0x00000001
181 #define DCACHE_OP_COMPARE 0x00000002
182 #define DCACHE_OP_REVALIDATE 0x00000004
183 #define DCACHE_OP_DELETE 0x00000008
184 #define DCACHE_OP_PRUNE 0x00000010
186 #define DCACHE_DISCONNECTED 0x00000020
187 /* This dentry is possibly not currently connected to the dcache tree, in
188 * which case its parent will either be itself, or will have this flag as
189 * well. nfsd will not use a dentry with this bit set, but will first
190 * endeavour to clear the bit either by discovering that it is connected,
191 * or by performing lookup operations. Any filesystem which supports
192 * nfsd_operations MUST have a lookup function which, if it finds a
193 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
194 * dentry into place and return that dentry rather than the passed one,
195 * typically using d_splice_alias. */
197 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
198 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */
200 #define DCACHE_CANT_MOUNT 0x00000100
201 #define DCACHE_GENOCIDE 0x00000200
202 #define DCACHE_SHRINK_LIST 0x00000400
204 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
206 #define DCACHE_NFSFS_RENAMED 0x00001000
207 /* this dentry has been "silly renamed" and has to be deleted on the last
209 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
210 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
211 /* Parent inode is watched by some fsnotify listener */
213 #define DCACHE_DENTRY_KILLED 0x00008000
215 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
216 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
217 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
218 #define DCACHE_MANAGED_DENTRY \
219 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
221 #define DCACHE_LRU_LIST 0x00080000
223 #define DCACHE_ENTRY_TYPE 0x00700000
224 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
225 #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
226 #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
227 #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
228 #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
229 #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
230 #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
232 #define DCACHE_MAY_FREE 0x00800000
233 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
234 #define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op selects inode */
236 #define DCACHE_ENCRYPTED_WITH_KEY 0x04000000 /* dir is encrypted with a valid key */
237 #define DCACHE_OP_REAL 0x08000000
239 #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */
241 extern seqlock_t rename_lock
;
244 * These are the low-level FS interfaces to the dcache..
246 extern void d_instantiate(struct dentry
*, struct inode
*);
247 extern struct dentry
* d_instantiate_unique(struct dentry
*, struct inode
*);
248 extern int d_instantiate_no_diralias(struct dentry
*, struct inode
*);
249 extern void __d_drop(struct dentry
*dentry
);
250 extern void d_drop(struct dentry
*dentry
);
251 extern void d_delete(struct dentry
*);
252 extern void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
);
254 /* allocate/de-allocate */
255 extern struct dentry
* d_alloc(struct dentry
*, const struct qstr
*);
256 extern struct dentry
* d_alloc_pseudo(struct super_block
*, const struct qstr
*);
257 extern struct dentry
* d_alloc_parallel(struct dentry
*, const struct qstr
*,
258 wait_queue_head_t
*);
259 extern struct dentry
* d_splice_alias(struct inode
*, struct dentry
*);
260 extern struct dentry
* d_add_ci(struct dentry
*, struct inode
*, struct qstr
*);
261 extern struct dentry
* d_exact_alias(struct dentry
*, struct inode
*);
262 extern struct dentry
*d_find_any_alias(struct inode
*inode
);
263 extern struct dentry
* d_obtain_alias(struct inode
*);
264 extern struct dentry
* d_obtain_root(struct inode
*);
265 extern void shrink_dcache_sb(struct super_block
*);
266 extern void shrink_dcache_parent(struct dentry
*);
267 extern void shrink_dcache_for_umount(struct super_block
*);
268 extern void d_invalidate(struct dentry
*);
270 /* only used at mount-time */
271 extern struct dentry
* d_make_root(struct inode
*);
273 /* <clickety>-<click> the ramfs-type tree */
274 extern void d_genocide(struct dentry
*);
276 extern void d_tmpfile(struct dentry
*, struct inode
*);
278 extern struct dentry
*d_find_alias(struct inode
*);
279 extern void d_prune_aliases(struct inode
*);
281 /* test whether we have any submounts in a subdir tree */
282 extern int have_submounts(struct dentry
*);
285 * This adds the entry to the hash queues.
287 extern void d_rehash(struct dentry
*);
289 extern void d_add(struct dentry
*, struct inode
*);
291 extern void dentry_update_name_case(struct dentry
*, struct qstr
*);
293 /* used for rename() and baskets */
294 extern void d_move(struct dentry
*, struct dentry
*);
295 extern void d_exchange(struct dentry
*, struct dentry
*);
296 extern struct dentry
*d_ancestor(struct dentry
*, struct dentry
*);
298 /* appendix may either be NULL or be used for transname suffixes */
299 extern struct dentry
*d_lookup(const struct dentry
*, const struct qstr
*);
300 extern struct dentry
*d_hash_and_lookup(struct dentry
*, struct qstr
*);
301 extern struct dentry
*__d_lookup(const struct dentry
*, const struct qstr
*);
302 extern struct dentry
*__d_lookup_rcu(const struct dentry
*parent
,
303 const struct qstr
*name
, unsigned *seq
);
305 static inline unsigned d_count(const struct dentry
*dentry
)
307 return dentry
->d_lockref
.count
;
311 * helper function for dentry_operations.d_dname() members
313 extern __printf(4, 5)
314 char *dynamic_dname(struct dentry
*, char *, int, const char *, ...);
315 extern char *simple_dname(struct dentry
*, char *, int);
317 extern char *__d_path(const struct path
*, const struct path
*, char *, int);
318 extern char *d_absolute_path(const struct path
*, char *, int);
319 extern char *d_path(const struct path
*, char *, int);
320 extern char *dentry_path_raw(struct dentry
*, char *, int);
321 extern char *dentry_path(struct dentry
*, char *, int);
323 /* Allocation counts.. */
326 * dget, dget_dlock - get a reference to a dentry
327 * @dentry: dentry to get a reference to
329 * Given a dentry or %NULL pointer increment the reference count
330 * if appropriate and return the dentry. A dentry will not be
331 * destroyed when it has references.
333 static inline struct dentry
*dget_dlock(struct dentry
*dentry
)
336 dentry
->d_lockref
.count
++;
340 static inline struct dentry
*dget(struct dentry
*dentry
)
343 lockref_get(&dentry
->d_lockref
);
347 extern struct dentry
*dget_parent(struct dentry
*dentry
);
350 * d_unhashed - is dentry hashed
351 * @dentry: entry to check
353 * Returns true if the dentry passed is not currently hashed.
356 static inline int d_unhashed(const struct dentry
*dentry
)
358 return hlist_bl_unhashed(&dentry
->d_hash
);
361 static inline int d_unlinked(const struct dentry
*dentry
)
363 return d_unhashed(dentry
) && !IS_ROOT(dentry
);
366 static inline int cant_mount(const struct dentry
*dentry
)
368 return (dentry
->d_flags
& DCACHE_CANT_MOUNT
);
371 static inline void dont_mount(struct dentry
*dentry
)
373 spin_lock(&dentry
->d_lock
);
374 dentry
->d_flags
|= DCACHE_CANT_MOUNT
;
375 spin_unlock(&dentry
->d_lock
);
378 extern void __d_lookup_done(struct dentry
*);
380 static inline int d_in_lookup(struct dentry
*dentry
)
382 return dentry
->d_flags
& DCACHE_PAR_LOOKUP
;
385 static inline void d_lookup_done(struct dentry
*dentry
)
387 if (unlikely(d_in_lookup(dentry
))) {
388 spin_lock(&dentry
->d_lock
);
389 __d_lookup_done(dentry
);
390 spin_unlock(&dentry
->d_lock
);
394 extern void dput(struct dentry
*);
396 static inline bool d_managed(const struct dentry
*dentry
)
398 return dentry
->d_flags
& DCACHE_MANAGED_DENTRY
;
401 static inline bool d_mountpoint(const struct dentry
*dentry
)
403 return dentry
->d_flags
& DCACHE_MOUNTED
;
407 * Directory cache entry type accessor functions.
409 static inline unsigned __d_entry_type(const struct dentry
*dentry
)
411 return dentry
->d_flags
& DCACHE_ENTRY_TYPE
;
414 static inline bool d_is_miss(const struct dentry
*dentry
)
416 return __d_entry_type(dentry
) == DCACHE_MISS_TYPE
;
419 static inline bool d_is_whiteout(const struct dentry
*dentry
)
421 return __d_entry_type(dentry
) == DCACHE_WHITEOUT_TYPE
;
424 static inline bool d_can_lookup(const struct dentry
*dentry
)
426 return __d_entry_type(dentry
) == DCACHE_DIRECTORY_TYPE
;
429 static inline bool d_is_autodir(const struct dentry
*dentry
)
431 return __d_entry_type(dentry
) == DCACHE_AUTODIR_TYPE
;
434 static inline bool d_is_dir(const struct dentry
*dentry
)
436 return d_can_lookup(dentry
) || d_is_autodir(dentry
);
439 static inline bool d_is_symlink(const struct dentry
*dentry
)
441 return __d_entry_type(dentry
) == DCACHE_SYMLINK_TYPE
;
444 static inline bool d_is_reg(const struct dentry
*dentry
)
446 return __d_entry_type(dentry
) == DCACHE_REGULAR_TYPE
;
449 static inline bool d_is_special(const struct dentry
*dentry
)
451 return __d_entry_type(dentry
) == DCACHE_SPECIAL_TYPE
;
454 static inline bool d_is_file(const struct dentry
*dentry
)
456 return d_is_reg(dentry
) || d_is_special(dentry
);
459 static inline bool d_is_negative(const struct dentry
*dentry
)
461 // TODO: check d_is_whiteout(dentry) also.
462 return d_is_miss(dentry
);
465 static inline bool d_is_positive(const struct dentry
*dentry
)
467 return !d_is_negative(dentry
);
471 * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
472 * @dentry: The dentry in question
474 * Returns true if the dentry represents either an absent name or a name that
475 * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
476 * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
477 * fallthrough marker in an opaque directory.
479 * Note! (1) This should be used *only* by a filesystem to examine its own
480 * dentries. It should not be used to look at some other filesystem's
481 * dentries. (2) It should also be used in combination with d_inode() to get
482 * the inode. (3) The dentry may have something attached to ->d_lower and the
483 * type field of the flags may be set to something other than miss or whiteout.
485 static inline bool d_really_is_negative(const struct dentry
*dentry
)
487 return dentry
->d_inode
== NULL
;
491 * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
492 * @dentry: The dentry in question
494 * Returns true if the dentry represents a name that maps to an inode
495 * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
496 * that is represented on medium as a 0,0 chardev.
498 * Note! (1) This should be used *only* by a filesystem to examine its own
499 * dentries. It should not be used to look at some other filesystem's
500 * dentries. (2) It should also be used in combination with d_inode() to get
503 static inline bool d_really_is_positive(const struct dentry
*dentry
)
505 return dentry
->d_inode
!= NULL
;
508 static inline int simple_positive(struct dentry
*dentry
)
510 return d_really_is_positive(dentry
) && !d_unhashed(dentry
);
513 extern void d_set_fallthru(struct dentry
*dentry
);
515 static inline bool d_is_fallthru(const struct dentry
*dentry
)
517 return dentry
->d_flags
& DCACHE_FALLTHRU
;
521 extern int sysctl_vfs_cache_pressure
;
523 static inline unsigned long vfs_pressure_ratio(unsigned long val
)
525 return mult_frac(val
, sysctl_vfs_cache_pressure
, 100);
529 * d_inode - Get the actual inode of this dentry
530 * @dentry: The dentry to query
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.
535 static inline struct inode
*d_inode(const struct dentry
*dentry
)
537 return dentry
->d_inode
;
541 * d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE()
542 * @dentry: The dentry to query
544 * This is the helper normal filesystems should use to get at their own inodes
545 * in their own dentries and ignore the layering superimposed upon them.
547 static inline struct inode
*d_inode_rcu(const struct dentry
*dentry
)
549 return ACCESS_ONCE(dentry
->d_inode
);
553 * d_backing_inode - Get upper or lower inode we should be using
554 * @upper: The upper layer
556 * This is the helper that should be used to get at the inode that will be used
557 * if this dentry were to be opened as a file. The inode may be on the upper
558 * dentry or it may be on a lower dentry pinned by the upper.
560 * Normal filesystems should not use this to access their own inodes.
562 static inline struct inode
*d_backing_inode(const struct dentry
*upper
)
564 struct inode
*inode
= upper
->d_inode
;
570 * d_backing_dentry - Get upper or lower dentry we should be using
571 * @upper: The upper layer
573 * This is the helper that should be used to get the dentry of the inode that
574 * will be used if this dentry were opened as a file. It may be the upper
575 * dentry or it may be a lower dentry pinned by the upper.
577 * Normal filesystems should not use this to access their own dentries.
579 static inline struct dentry
*d_backing_dentry(struct dentry
*upper
)
584 static inline struct dentry
*d_real(struct dentry
*dentry
)
586 if (unlikely(dentry
->d_flags
& DCACHE_OP_REAL
))
587 return dentry
->d_op
->d_real(dentry
, NULL
);
592 static inline struct inode
*vfs_select_inode(struct dentry
*dentry
,
595 struct inode
*inode
= d_inode(dentry
);
597 if (inode
&& unlikely(dentry
->d_flags
& DCACHE_OP_SELECT_INODE
))
598 inode
= dentry
->d_op
->d_select_inode(dentry
, open_flags
);
604 #endif /* __LINUX_DCACHE_H */