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>
13 #include <linux/stringhash.h>
19 * linux/include/linux/dcache.h
21 * Dirent cache data structures
23 * (C) Copyright 1997 Thomas Schoebel-Theuer,
24 * with heavy changes by Linus Torvalds
27 #define IS_ROOT(x) ((x) == (x)->d_parent)
29 /* The hash is always the low bits of hash_len */
30 #ifdef __LITTLE_ENDIAN
31 #define HASH_LEN_DECLARE u32 hash; u32 len
32 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
34 #define HASH_LEN_DECLARE u32 len; u32 hash
35 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
39 * "quick string" -- eases parameter passing, but more importantly
40 * saves "metadata" about the string (ie length and the hash).
42 * hash comes first so it snuggles against d_parent in the
52 const unsigned char *name
;
55 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
57 struct dentry_stat_t
{
60 long age_limit
; /* age in seconds */
61 long want_pages
; /* pages requested by system */
64 extern struct dentry_stat_t dentry_stat
;
67 * Try to keep struct dentry aligned on 64 byte cachelines (this will
68 * give reasonable cacheline footprint with larger lines without the
69 * large memory footprint increase).
72 # define DNAME_INLINE_LEN 32 /* 192 bytes */
75 # define DNAME_INLINE_LEN 36 /* 128 bytes */
77 # define DNAME_INLINE_LEN 40 /* 128 bytes */
81 #define d_lock d_lockref.lock
84 /* RCU lookup touched fields */
85 unsigned int d_flags
; /* protected by d_lock */
86 seqcount_t d_seq
; /* per dentry seqlock */
87 struct hlist_bl_node d_hash
; /* lookup hash list */
88 struct dentry
*d_parent
; /* parent directory */
90 struct inode
*d_inode
; /* Where the name belongs to - NULL is
92 unsigned char d_iname
[DNAME_INLINE_LEN
]; /* small names */
94 /* Ref lookup also touches following */
95 struct lockref d_lockref
; /* per-dentry lock and refcount */
96 const struct dentry_operations
*d_op
;
97 struct super_block
*d_sb
; /* The root of the dentry tree */
98 unsigned long d_time
; /* used by d_revalidate */
99 void *d_fsdata
; /* fs-specific data */
101 struct list_head d_lru
; /* LRU list */
102 struct list_head d_child
; /* child of parent list */
103 struct list_head d_subdirs
; /* our children */
105 * d_alias and d_rcu can share memory
108 struct hlist_node d_alias
; /* inode alias list */
109 struct rcu_head d_rcu
;
114 * dentry->d_lock spinlock nesting subclasses:
119 enum dentry_d_lock_class
121 DENTRY_D_LOCK_NORMAL
, /* implicitly used by plain spin_lock() APIs. */
125 struct dentry_operations
{
126 int (*d_revalidate
)(struct dentry
*, unsigned int);
127 int (*d_weak_revalidate
)(struct dentry
*, unsigned int);
128 int (*d_hash
)(const struct dentry
*, struct qstr
*);
129 int (*d_compare
)(const struct dentry
*, const struct dentry
*,
130 unsigned int, const char *, const struct qstr
*);
131 int (*d_delete
)(const struct dentry
*);
132 void (*d_release
)(struct dentry
*);
133 void (*d_prune
)(struct dentry
*);
134 void (*d_iput
)(struct dentry
*, struct inode
*);
135 char *(*d_dname
)(struct dentry
*, char *, int);
136 struct vfsmount
*(*d_automount
)(struct path
*);
137 int (*d_manage
)(struct dentry
*, bool);
138 struct inode
*(*d_select_inode
)(struct dentry
*, unsigned);
139 struct dentry
*(*d_real
)(struct dentry
*, struct inode
*);
140 } ____cacheline_aligned
;
143 * Locking rules for dentry_operations callbacks are to be found in
144 * Documentation/filesystems/Locking. Keep it updated!
146 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
147 * Keep it updated too!
150 /* d_flags entries */
151 #define DCACHE_OP_HASH 0x00000001
152 #define DCACHE_OP_COMPARE 0x00000002
153 #define DCACHE_OP_REVALIDATE 0x00000004
154 #define DCACHE_OP_DELETE 0x00000008
155 #define DCACHE_OP_PRUNE 0x00000010
157 #define DCACHE_DISCONNECTED 0x00000020
158 /* This dentry is possibly not currently connected to the dcache tree, in
159 * which case its parent will either be itself, or will have this flag as
160 * well. nfsd will not use a dentry with this bit set, but will first
161 * endeavour to clear the bit either by discovering that it is connected,
162 * or by performing lookup operations. Any filesystem which supports
163 * nfsd_operations MUST have a lookup function which, if it finds a
164 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
165 * dentry into place and return that dentry rather than the passed one,
166 * typically using d_splice_alias. */
168 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
169 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */
171 #define DCACHE_CANT_MOUNT 0x00000100
172 #define DCACHE_GENOCIDE 0x00000200
173 #define DCACHE_SHRINK_LIST 0x00000400
175 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
177 #define DCACHE_NFSFS_RENAMED 0x00001000
178 /* this dentry has been "silly renamed" and has to be deleted on the last
180 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
181 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
182 /* Parent inode is watched by some fsnotify listener */
184 #define DCACHE_DENTRY_KILLED 0x00008000
186 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
187 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
188 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
189 #define DCACHE_MANAGED_DENTRY \
190 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
192 #define DCACHE_LRU_LIST 0x00080000
194 #define DCACHE_ENTRY_TYPE 0x00700000
195 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
196 #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */
197 #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */
198 #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */
199 #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */
200 #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */
201 #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */
203 #define DCACHE_MAY_FREE 0x00800000
204 #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */
205 #define DCACHE_OP_SELECT_INODE 0x02000000 /* Unioned entry: dcache op selects inode */
207 #define DCACHE_ENCRYPTED_WITH_KEY 0x04000000 /* dir is encrypted with a valid key */
208 #define DCACHE_OP_REAL 0x08000000
210 extern seqlock_t rename_lock
;
213 * These are the low-level FS interfaces to the dcache..
215 extern void d_instantiate(struct dentry
*, struct inode
*);
216 extern struct dentry
* d_instantiate_unique(struct dentry
*, struct inode
*);
217 extern int d_instantiate_no_diralias(struct dentry
*, struct inode
*);
218 extern void __d_drop(struct dentry
*dentry
);
219 extern void d_drop(struct dentry
*dentry
);
220 extern void d_delete(struct dentry
*);
221 extern void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
);
223 /* allocate/de-allocate */
224 extern struct dentry
* d_alloc(struct dentry
*, const struct qstr
*);
225 extern struct dentry
* d_alloc_pseudo(struct super_block
*, const struct qstr
*);
226 extern struct dentry
* d_splice_alias(struct inode
*, struct dentry
*);
227 extern struct dentry
* d_add_ci(struct dentry
*, struct inode
*, struct qstr
*);
228 extern struct dentry
* d_exact_alias(struct dentry
*, struct inode
*);
229 extern struct dentry
*d_find_any_alias(struct inode
*inode
);
230 extern struct dentry
* d_obtain_alias(struct inode
*);
231 extern struct dentry
* d_obtain_root(struct inode
*);
232 extern void shrink_dcache_sb(struct super_block
*);
233 extern void shrink_dcache_parent(struct dentry
*);
234 extern void shrink_dcache_for_umount(struct super_block
*);
235 extern void d_invalidate(struct dentry
*);
237 /* only used at mount-time */
238 extern struct dentry
* d_make_root(struct inode
*);
240 /* <clickety>-<click> the ramfs-type tree */
241 extern void d_genocide(struct dentry
*);
243 extern void d_tmpfile(struct dentry
*, struct inode
*);
245 extern struct dentry
*d_find_alias(struct inode
*);
246 extern void d_prune_aliases(struct inode
*);
248 /* test whether we have any submounts in a subdir tree */
249 extern int have_submounts(struct dentry
*);
252 * This adds the entry to the hash queues.
254 extern void d_rehash(struct dentry
*);
256 extern void d_add(struct dentry
*, struct inode
*);
258 extern void dentry_update_name_case(struct dentry
*, struct qstr
*);
260 /* used for rename() and baskets */
261 extern void d_move(struct dentry
*, struct dentry
*);
262 extern void d_exchange(struct dentry
*, struct dentry
*);
263 extern struct dentry
*d_ancestor(struct dentry
*, struct dentry
*);
265 /* appendix may either be NULL or be used for transname suffixes */
266 extern struct dentry
*d_lookup(const struct dentry
*, const struct qstr
*);
267 extern struct dentry
*d_hash_and_lookup(struct dentry
*, struct qstr
*);
268 extern struct dentry
*__d_lookup(const struct dentry
*, const struct qstr
*);
269 extern struct dentry
*__d_lookup_rcu(const struct dentry
*parent
,
270 const struct qstr
*name
, unsigned *seq
);
272 static inline unsigned d_count(const struct dentry
*dentry
)
274 return dentry
->d_lockref
.count
;
278 * helper function for dentry_operations.d_dname() members
280 extern __printf(4, 5)
281 char *dynamic_dname(struct dentry
*, char *, int, const char *, ...);
282 extern char *simple_dname(struct dentry
*, char *, int);
284 extern char *__d_path(const struct path
*, const struct path
*, char *, int);
285 extern char *d_absolute_path(const struct path
*, char *, int);
286 extern char *d_path(const struct path
*, char *, int);
287 extern char *dentry_path_raw(struct dentry
*, char *, int);
288 extern char *dentry_path(struct dentry
*, char *, int);
290 /* Allocation counts.. */
293 * dget, dget_dlock - get a reference to a dentry
294 * @dentry: dentry to get a reference to
296 * Given a dentry or %NULL pointer increment the reference count
297 * if appropriate and return the dentry. A dentry will not be
298 * destroyed when it has references.
300 static inline struct dentry
*dget_dlock(struct dentry
*dentry
)
303 dentry
->d_lockref
.count
++;
307 static inline struct dentry
*dget(struct dentry
*dentry
)
310 lockref_get(&dentry
->d_lockref
);
314 extern struct dentry
*dget_parent(struct dentry
*dentry
);
317 * d_unhashed - is dentry hashed
318 * @dentry: entry to check
320 * Returns true if the dentry passed is not currently hashed.
323 static inline int d_unhashed(const struct dentry
*dentry
)
325 return hlist_bl_unhashed(&dentry
->d_hash
);
328 static inline int d_unlinked(const struct dentry
*dentry
)
330 return d_unhashed(dentry
) && !IS_ROOT(dentry
);
333 static inline int cant_mount(const struct dentry
*dentry
)
335 return (dentry
->d_flags
& DCACHE_CANT_MOUNT
);
338 static inline void dont_mount(struct dentry
*dentry
)
340 spin_lock(&dentry
->d_lock
);
341 dentry
->d_flags
|= DCACHE_CANT_MOUNT
;
342 spin_unlock(&dentry
->d_lock
);
345 extern void dput(struct dentry
*);
347 static inline bool d_managed(const struct dentry
*dentry
)
349 return dentry
->d_flags
& DCACHE_MANAGED_DENTRY
;
352 static inline bool d_mountpoint(const struct dentry
*dentry
)
354 return dentry
->d_flags
& DCACHE_MOUNTED
;
358 * Directory cache entry type accessor functions.
360 static inline unsigned __d_entry_type(const struct dentry
*dentry
)
362 return dentry
->d_flags
& DCACHE_ENTRY_TYPE
;
365 static inline bool d_is_miss(const struct dentry
*dentry
)
367 return __d_entry_type(dentry
) == DCACHE_MISS_TYPE
;
370 static inline bool d_is_whiteout(const struct dentry
*dentry
)
372 return __d_entry_type(dentry
) == DCACHE_WHITEOUT_TYPE
;
375 static inline bool d_can_lookup(const struct dentry
*dentry
)
377 return __d_entry_type(dentry
) == DCACHE_DIRECTORY_TYPE
;
380 static inline bool d_is_autodir(const struct dentry
*dentry
)
382 return __d_entry_type(dentry
) == DCACHE_AUTODIR_TYPE
;
385 static inline bool d_is_dir(const struct dentry
*dentry
)
387 return d_can_lookup(dentry
) || d_is_autodir(dentry
);
390 static inline bool d_is_symlink(const struct dentry
*dentry
)
392 return __d_entry_type(dentry
) == DCACHE_SYMLINK_TYPE
;
395 static inline bool d_is_reg(const struct dentry
*dentry
)
397 return __d_entry_type(dentry
) == DCACHE_REGULAR_TYPE
;
400 static inline bool d_is_special(const struct dentry
*dentry
)
402 return __d_entry_type(dentry
) == DCACHE_SPECIAL_TYPE
;
405 static inline bool d_is_file(const struct dentry
*dentry
)
407 return d_is_reg(dentry
) || d_is_special(dentry
);
410 static inline bool d_is_negative(const struct dentry
*dentry
)
412 // TODO: check d_is_whiteout(dentry) also.
413 return d_is_miss(dentry
);
416 static inline bool d_is_positive(const struct dentry
*dentry
)
418 return !d_is_negative(dentry
);
422 * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs)
423 * @dentry: The dentry in question
425 * Returns true if the dentry represents either an absent name or a name that
426 * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent
427 * a true miss, a whiteout that isn't represented by a 0,0 chardev or a
428 * fallthrough marker in an opaque directory.
430 * Note! (1) This should be used *only* by a filesystem to examine its own
431 * dentries. It should not be used to look at some other filesystem's
432 * dentries. (2) It should also be used in combination with d_inode() to get
433 * the inode. (3) The dentry may have something attached to ->d_lower and the
434 * type field of the flags may be set to something other than miss or whiteout.
436 static inline bool d_really_is_negative(const struct dentry
*dentry
)
438 return dentry
->d_inode
== NULL
;
442 * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs)
443 * @dentry: The dentry in question
445 * Returns true if the dentry represents a name that maps to an inode
446 * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if
447 * that is represented on medium as a 0,0 chardev.
449 * Note! (1) This should be used *only* by a filesystem to examine its own
450 * dentries. It should not be used to look at some other filesystem's
451 * dentries. (2) It should also be used in combination with d_inode() to get
454 static inline bool d_really_is_positive(const struct dentry
*dentry
)
456 return dentry
->d_inode
!= NULL
;
459 static inline int simple_positive(struct dentry
*dentry
)
461 return d_really_is_positive(dentry
) && !d_unhashed(dentry
);
464 extern void d_set_fallthru(struct dentry
*dentry
);
466 static inline bool d_is_fallthru(const struct dentry
*dentry
)
468 return dentry
->d_flags
& DCACHE_FALLTHRU
;
472 extern int sysctl_vfs_cache_pressure
;
474 static inline unsigned long vfs_pressure_ratio(unsigned long val
)
476 return mult_frac(val
, sysctl_vfs_cache_pressure
, 100);
480 * d_inode - Get the actual inode of this dentry
481 * @dentry: The dentry to query
483 * This is the helper normal filesystems should use to get at their own inodes
484 * in their own dentries and ignore the layering superimposed upon them.
486 static inline struct inode
*d_inode(const struct dentry
*dentry
)
488 return dentry
->d_inode
;
492 * d_inode_rcu - Get the actual inode of this dentry with ACCESS_ONCE()
493 * @dentry: The dentry to query
495 * This is the helper normal filesystems should use to get at their own inodes
496 * in their own dentries and ignore the layering superimposed upon them.
498 static inline struct inode
*d_inode_rcu(const struct dentry
*dentry
)
500 return ACCESS_ONCE(dentry
->d_inode
);
504 * d_backing_inode - Get upper or lower inode we should be using
505 * @upper: The upper layer
507 * This is the helper that should be used to get at the inode that will be used
508 * if this dentry were to be opened as a file. The inode may be on the upper
509 * dentry or it may be on a lower dentry pinned by the upper.
511 * Normal filesystems should not use this to access their own inodes.
513 static inline struct inode
*d_backing_inode(const struct dentry
*upper
)
515 struct inode
*inode
= upper
->d_inode
;
521 * d_backing_dentry - Get upper or lower dentry we should be using
522 * @upper: The upper layer
524 * This is the helper that should be used to get the dentry of the inode that
525 * will be used if this dentry were opened as a file. It may be the upper
526 * dentry or it may be a lower dentry pinned by the upper.
528 * Normal filesystems should not use this to access their own dentries.
530 static inline struct dentry
*d_backing_dentry(struct dentry
*upper
)
535 static inline struct dentry
*d_real(struct dentry
*dentry
)
537 if (unlikely(dentry
->d_flags
& DCACHE_OP_REAL
))
538 return dentry
->d_op
->d_real(dentry
, NULL
);
543 static inline struct inode
*vfs_select_inode(struct dentry
*dentry
,
546 struct inode
*inode
= d_inode(dentry
);
548 if (inode
&& unlikely(dentry
->d_flags
& DCACHE_OP_SELECT_INODE
))
549 inode
= dentry
->d_op
->d_select_inode(dentry
, open_flags
);
555 #endif /* __LINUX_DCACHE_H */