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>
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 }
56 #define hashlen_hash(hashlen) ((u32) (hashlen))
57 #define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
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 */
126 struct list_head d_lru
; /* LRU list */
128 * d_child and d_rcu can share memory
131 struct list_head d_child
; /* child of parent list */
132 struct rcu_head d_rcu
;
134 struct list_head d_subdirs
; /* our children */
135 struct hlist_node d_alias
; /* inode alias list */
139 * dentry->d_lock spinlock nesting subclasses:
144 enum dentry_d_lock_class
146 DENTRY_D_LOCK_NORMAL
, /* implicitly used by plain spin_lock() APIs. */
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 } ____cacheline_aligned
;
166 * Locking rules for dentry_operations callbacks are to be found in
167 * Documentation/filesystems/Locking. Keep it updated!
169 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
170 * Keep it updated too!
173 /* d_flags entries */
174 #define DCACHE_OP_HASH 0x00000001
175 #define DCACHE_OP_COMPARE 0x00000002
176 #define DCACHE_OP_REVALIDATE 0x00000004
177 #define DCACHE_OP_DELETE 0x00000008
178 #define DCACHE_OP_PRUNE 0x00000010
180 #define DCACHE_DISCONNECTED 0x00000020
181 /* This dentry is possibly not currently connected to the dcache tree, in
182 * which case its parent will either be itself, or will have this flag as
183 * well. nfsd will not use a dentry with this bit set, but will first
184 * endeavour to clear the bit either by discovering that it is connected,
185 * or by performing lookup operations. Any filesystem which supports
186 * nfsd_operations MUST have a lookup function which, if it finds a
187 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
188 * dentry into place and return that dentry rather than the passed one,
189 * typically using d_splice_alias. */
191 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
192 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */
194 #define DCACHE_CANT_MOUNT 0x00000100
195 #define DCACHE_GENOCIDE 0x00000200
196 #define DCACHE_SHRINK_LIST 0x00000400
198 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
200 #define DCACHE_NFSFS_RENAMED 0x00001000
201 /* this dentry has been "silly renamed" and has to be deleted on the last
203 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
204 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
205 /* Parent inode is watched by some fsnotify listener */
207 #define DCACHE_DENTRY_KILLED 0x00008000
209 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
210 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
211 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
212 #define DCACHE_MANAGED_DENTRY \
213 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
215 #define DCACHE_LRU_LIST 0x00080000
217 #define DCACHE_ENTRY_TYPE 0x00700000
218 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry */
219 #define DCACHE_DIRECTORY_TYPE 0x00100000 /* Normal directory */
220 #define DCACHE_AUTODIR_TYPE 0x00200000 /* Lookupless directory (presumed automount) */
221 #define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */
222 #define DCACHE_FILE_TYPE 0x00400000 /* Other file type */
224 extern seqlock_t rename_lock
;
226 static inline int dname_external(const struct dentry
*dentry
)
228 return dentry
->d_name
.name
!= dentry
->d_iname
;
232 * These are the low-level FS interfaces to the dcache..
234 extern void d_instantiate(struct dentry
*, struct inode
*);
235 extern struct dentry
* d_instantiate_unique(struct dentry
*, struct inode
*);
236 extern struct dentry
* d_materialise_unique(struct dentry
*, struct inode
*);
237 extern int d_instantiate_no_diralias(struct dentry
*, struct inode
*);
238 extern void __d_drop(struct dentry
*dentry
);
239 extern void d_drop(struct dentry
*dentry
);
240 extern void d_delete(struct dentry
*);
241 extern void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
);
243 /* allocate/de-allocate */
244 extern struct dentry
* d_alloc(struct dentry
*, const struct qstr
*);
245 extern struct dentry
* d_alloc_pseudo(struct super_block
*, const struct qstr
*);
246 extern struct dentry
* d_splice_alias(struct inode
*, struct dentry
*);
247 extern struct dentry
* d_add_ci(struct dentry
*, struct inode
*, struct qstr
*);
248 extern struct dentry
*d_find_any_alias(struct inode
*inode
);
249 extern struct dentry
* d_obtain_alias(struct inode
*);
250 extern void shrink_dcache_sb(struct super_block
*);
251 extern void shrink_dcache_parent(struct dentry
*);
252 extern void shrink_dcache_for_umount(struct super_block
*);
253 extern int d_invalidate(struct dentry
*);
255 /* only used at mount-time */
256 extern struct dentry
* d_make_root(struct inode
*);
258 /* <clickety>-<click> the ramfs-type tree */
259 extern void d_genocide(struct dentry
*);
261 extern void d_tmpfile(struct dentry
*, struct inode
*);
263 extern struct dentry
*d_find_alias(struct inode
*);
264 extern void d_prune_aliases(struct inode
*);
266 /* test whether we have any submounts in a subdir tree */
267 extern int have_submounts(struct dentry
*);
268 extern int check_submounts_and_drop(struct dentry
*);
271 * This adds the entry to the hash queues.
273 extern void d_rehash(struct dentry
*);
276 * d_add - add dentry to hash queues
277 * @entry: dentry to add
278 * @inode: The inode to attach to this dentry
280 * This adds the entry to the hash queues and initializes @inode.
281 * The entry was actually filled in earlier during d_alloc().
284 static inline void d_add(struct dentry
*entry
, struct inode
*inode
)
286 d_instantiate(entry
, inode
);
291 * d_add_unique - add dentry to hash queues without aliasing
292 * @entry: dentry to add
293 * @inode: The inode to attach to this dentry
295 * This adds the entry to the hash queues and initializes @inode.
296 * The entry was actually filled in earlier during d_alloc().
298 static inline struct dentry
*d_add_unique(struct dentry
*entry
, struct inode
*inode
)
302 res
= d_instantiate_unique(entry
, inode
);
303 d_rehash(res
!= NULL
? res
: entry
);
307 extern void dentry_update_name_case(struct dentry
*, struct qstr
*);
309 /* used for rename() and baskets */
310 extern void d_move(struct dentry
*, struct dentry
*);
311 extern void d_exchange(struct dentry
*, struct dentry
*);
312 extern struct dentry
*d_ancestor(struct dentry
*, struct dentry
*);
314 /* appendix may either be NULL or be used for transname suffixes */
315 extern struct dentry
*d_lookup(const struct dentry
*, const struct qstr
*);
316 extern struct dentry
*d_hash_and_lookup(struct dentry
*, struct qstr
*);
317 extern struct dentry
*__d_lookup(const struct dentry
*, const struct qstr
*);
318 extern struct dentry
*__d_lookup_rcu(const struct dentry
*parent
,
319 const struct qstr
*name
, unsigned *seq
);
321 static inline unsigned d_count(const struct dentry
*dentry
)
323 return dentry
->d_lockref
.count
;
326 /* validate "insecure" dentry pointer */
327 extern int d_validate(struct dentry
*, struct dentry
*);
330 * helper function for dentry_operations.d_dname() members
332 extern char *dynamic_dname(struct dentry
*, char *, int, const char *, ...);
333 extern char *simple_dname(struct dentry
*, char *, int);
335 extern char *__d_path(const struct path
*, const struct path
*, char *, int);
336 extern char *d_absolute_path(const struct path
*, char *, int);
337 extern char *d_path(const struct path
*, char *, int);
338 extern char *dentry_path_raw(struct dentry
*, char *, int);
339 extern char *dentry_path(struct dentry
*, char *, int);
341 /* Allocation counts.. */
344 * dget, dget_dlock - get a reference to a dentry
345 * @dentry: dentry to get a reference to
347 * Given a dentry or %NULL pointer increment the reference count
348 * if appropriate and return the dentry. A dentry will not be
349 * destroyed when it has references.
351 static inline struct dentry
*dget_dlock(struct dentry
*dentry
)
354 dentry
->d_lockref
.count
++;
358 static inline struct dentry
*dget(struct dentry
*dentry
)
361 lockref_get(&dentry
->d_lockref
);
365 extern struct dentry
*dget_parent(struct dentry
*dentry
);
368 * d_unhashed - is dentry hashed
369 * @dentry: entry to check
371 * Returns true if the dentry passed is not currently hashed.
374 static inline int d_unhashed(const struct dentry
*dentry
)
376 return hlist_bl_unhashed(&dentry
->d_hash
);
379 static inline int d_unlinked(const struct dentry
*dentry
)
381 return d_unhashed(dentry
) && !IS_ROOT(dentry
);
384 static inline int cant_mount(const struct dentry
*dentry
)
386 return (dentry
->d_flags
& DCACHE_CANT_MOUNT
);
389 static inline void dont_mount(struct dentry
*dentry
)
391 spin_lock(&dentry
->d_lock
);
392 dentry
->d_flags
|= DCACHE_CANT_MOUNT
;
393 spin_unlock(&dentry
->d_lock
);
396 extern void dput(struct dentry
*);
398 static inline bool d_managed(const struct dentry
*dentry
)
400 return dentry
->d_flags
& DCACHE_MANAGED_DENTRY
;
403 static inline bool d_mountpoint(const struct dentry
*dentry
)
405 return dentry
->d_flags
& DCACHE_MOUNTED
;
409 * Directory cache entry type accessor functions.
411 static inline void __d_set_type(struct dentry
*dentry
, unsigned type
)
413 dentry
->d_flags
= (dentry
->d_flags
& ~DCACHE_ENTRY_TYPE
) | type
;
416 static inline void __d_clear_type(struct dentry
*dentry
)
418 __d_set_type(dentry
, DCACHE_MISS_TYPE
);
421 static inline void d_set_type(struct dentry
*dentry
, unsigned type
)
423 spin_lock(&dentry
->d_lock
);
424 __d_set_type(dentry
, type
);
425 spin_unlock(&dentry
->d_lock
);
428 static inline unsigned __d_entry_type(const struct dentry
*dentry
)
430 return dentry
->d_flags
& DCACHE_ENTRY_TYPE
;
433 static inline bool d_can_lookup(const struct dentry
*dentry
)
435 return __d_entry_type(dentry
) == DCACHE_DIRECTORY_TYPE
;
438 static inline bool d_is_autodir(const struct dentry
*dentry
)
440 return __d_entry_type(dentry
) == DCACHE_AUTODIR_TYPE
;
443 static inline bool d_is_dir(const struct dentry
*dentry
)
445 return d_can_lookup(dentry
) || d_is_autodir(dentry
);
448 static inline bool d_is_symlink(const struct dentry
*dentry
)
450 return __d_entry_type(dentry
) == DCACHE_SYMLINK_TYPE
;
453 static inline bool d_is_file(const struct dentry
*dentry
)
455 return __d_entry_type(dentry
) == DCACHE_FILE_TYPE
;
458 static inline bool d_is_negative(const struct dentry
*dentry
)
460 return __d_entry_type(dentry
) == DCACHE_MISS_TYPE
;
463 static inline bool d_is_positive(const struct dentry
*dentry
)
465 return !d_is_negative(dentry
);
468 extern int sysctl_vfs_cache_pressure
;
470 static inline unsigned long vfs_pressure_ratio(unsigned long val
)
472 return mult_frac(val
, sysctl_vfs_cache_pressure
, 100);
474 #endif /* __LINUX_DCACHE_H */