1 #ifndef __LINUX_DCACHE_H
2 #define __LINUX_DCACHE_H
4 #include <asm/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>
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)
29 * "quick string" -- eases parameter passing, but more importantly
30 * saves "metadata" about the string (ie length and the hash).
32 * hash comes first so it snuggles against d_parent in the
38 const unsigned char *name
;
41 struct dentry_stat_t
{
44 int age_limit
; /* age in seconds */
45 int want_pages
; /* pages requested by system */
48 extern struct dentry_stat_t dentry_stat
;
51 * Compare 2 name strings, return 0 if they match, otherwise non-zero.
52 * The strings are both count bytes long, and count is non-zero.
54 static inline int dentry_cmp(const unsigned char *cs
, size_t scount
,
55 const unsigned char *ct
, size_t tcount
)
71 /* Name hashing routines. Initial hash value */
72 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
73 #define init_name_hash() 0
75 /* partial hash update function. Assume roughly 4 bits per character */
76 static inline unsigned long
77 partial_name_hash(unsigned long c
, unsigned long prevhash
)
79 return (prevhash
+ (c
<< 4) + (c
>> 4)) * 11;
83 * Finally: cut down the number of bits to a int value (and try to avoid
86 static inline unsigned long end_name_hash(unsigned long hash
)
88 return (unsigned int) hash
;
91 /* Compute the hash for a name string. */
92 static inline unsigned int
93 full_name_hash(const unsigned char *name
, unsigned int len
)
95 unsigned long hash
= init_name_hash();
97 hash
= partial_name_hash(*name
++, hash
);
98 return end_name_hash(hash
);
102 * Try to keep struct dentry aligned on 64 byte cachelines (this will
103 * give reasonable cacheline footprint with larger lines without the
104 * large memory footprint increase).
107 # define DNAME_INLINE_LEN 32 /* 192 bytes */
110 # define DNAME_INLINE_LEN 36 /* 128 bytes */
112 # define DNAME_INLINE_LEN 40 /* 128 bytes */
117 /* RCU lookup touched fields */
118 unsigned int d_flags
; /* protected by d_lock */
119 seqcount_t d_seq
; /* per dentry seqlock */
120 struct hlist_bl_node d_hash
; /* lookup hash list */
121 struct dentry
*d_parent
; /* parent directory */
123 struct inode
*d_inode
; /* Where the name belongs to - NULL is
125 unsigned char d_iname
[DNAME_INLINE_LEN
]; /* small names */
127 /* Ref lookup also touches following */
128 unsigned int d_count
; /* protected by d_lock */
129 spinlock_t d_lock
; /* per dentry lock */
130 const struct dentry_operations
*d_op
;
131 struct super_block
*d_sb
; /* The root of the dentry tree */
132 unsigned long d_time
; /* used by d_revalidate */
133 void *d_fsdata
; /* fs-specific data */
135 struct list_head d_lru
; /* LRU list */
137 * d_child and d_rcu can share memory
140 struct list_head d_child
; /* child of parent list */
141 struct rcu_head d_rcu
;
143 struct list_head d_subdirs
; /* our children */
144 struct list_head d_alias
; /* inode alias list */
148 * dentry->d_lock spinlock nesting subclasses:
153 enum dentry_d_lock_class
155 DENTRY_D_LOCK_NORMAL
, /* implicitly used by plain spin_lock() APIs. */
159 struct dentry_operations
{
160 int (*d_revalidate
)(struct dentry
*, struct nameidata
*);
161 int (*d_hash
)(const struct dentry
*, const struct inode
*,
163 int (*d_compare
)(const struct dentry
*, const struct inode
*,
164 const struct dentry
*, const struct inode
*,
165 unsigned int, const char *, const struct qstr
*);
166 int (*d_delete
)(const struct dentry
*);
167 void (*d_release
)(struct dentry
*);
168 void (*d_iput
)(struct dentry
*, struct inode
*);
169 char *(*d_dname
)(struct dentry
*, char *, int);
170 } ____cacheline_aligned
;
173 * Locking rules for dentry_operations callbacks are to be found in
174 * Documentation/filesystems/Locking. Keep it updated!
176 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
177 * Keep it updated too!
180 /* d_flags entries */
181 #define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
182 #define DCACHE_NFSFS_RENAMED 0x0002
183 /* this dentry has been "silly renamed" and has to be deleted on the last
186 #define DCACHE_DISCONNECTED 0x0004
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 0x0008 /* Recently used, don't discard. */
198 #define DCACHE_UNHASHED 0x0010
199 #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020
200 /* Parent inode is watched by inotify */
202 #define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
203 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080
204 /* Parent inode is watched by some fsnotify listener */
206 #define DCACHE_CANT_MOUNT 0x0100
207 #define DCACHE_GENOCIDE 0x0200
208 #define DCACHE_MOUNTED 0x0400 /* is a mountpoint */
210 #define DCACHE_OP_HASH 0x1000
211 #define DCACHE_OP_COMPARE 0x2000
212 #define DCACHE_OP_REVALIDATE 0x4000
213 #define DCACHE_OP_DELETE 0x8000
215 extern seqlock_t rename_lock
;
217 static inline int dname_external(struct dentry
*dentry
)
219 return dentry
->d_name
.name
!= dentry
->d_iname
;
223 * These are the low-level FS interfaces to the dcache..
225 extern void d_instantiate(struct dentry
*, struct inode
*);
226 extern struct dentry
* d_instantiate_unique(struct dentry
*, struct inode
*);
227 extern struct dentry
* d_materialise_unique(struct dentry
*, struct inode
*);
228 extern void __d_drop(struct dentry
*dentry
);
229 extern void d_drop(struct dentry
*dentry
);
230 extern void d_delete(struct dentry
*);
231 extern void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
);
233 /* allocate/de-allocate */
234 extern struct dentry
* d_alloc(struct dentry
*, const struct qstr
*);
235 extern struct dentry
* d_alloc_pseudo(struct super_block
*, const struct qstr
*);
236 extern struct dentry
* d_splice_alias(struct inode
*, struct dentry
*);
237 extern struct dentry
* d_add_ci(struct dentry
*, struct inode
*, struct qstr
*);
238 extern struct dentry
* d_obtain_alias(struct inode
*);
239 extern void shrink_dcache_sb(struct super_block
*);
240 extern void shrink_dcache_parent(struct dentry
*);
241 extern void shrink_dcache_for_umount(struct super_block
*);
242 extern int d_invalidate(struct dentry
*);
244 /* only used at mount-time */
245 extern struct dentry
* d_alloc_root(struct inode
*);
247 /* <clickety>-<click> the ramfs-type tree */
248 extern void d_genocide(struct dentry
*);
250 extern struct dentry
*d_find_alias(struct inode
*);
251 extern void d_prune_aliases(struct inode
*);
253 /* test whether we have any submounts in a subdir tree */
254 extern int have_submounts(struct dentry
*);
257 * This adds the entry to the hash queues.
259 extern void d_rehash(struct dentry
*);
262 * d_add - add dentry to hash queues
263 * @entry: dentry to add
264 * @inode: The inode to attach to this dentry
266 * This adds the entry to the hash queues and initializes @inode.
267 * The entry was actually filled in earlier during d_alloc().
270 static inline void d_add(struct dentry
*entry
, struct inode
*inode
)
272 d_instantiate(entry
, inode
);
277 * d_add_unique - add dentry to hash queues without aliasing
278 * @entry: dentry to add
279 * @inode: The inode to attach to this dentry
281 * This adds the entry to the hash queues and initializes @inode.
282 * The entry was actually filled in earlier during d_alloc().
284 static inline struct dentry
*d_add_unique(struct dentry
*entry
, struct inode
*inode
)
288 res
= d_instantiate_unique(entry
, inode
);
289 d_rehash(res
!= NULL
? res
: entry
);
293 extern void dentry_update_name_case(struct dentry
*, struct qstr
*);
295 /* used for rename() and baskets */
296 extern void d_move(struct dentry
*, struct dentry
*);
297 extern struct dentry
*d_ancestor(struct dentry
*, struct dentry
*);
299 /* appendix may either be NULL or be used for transname suffixes */
300 extern struct dentry
*d_lookup(struct dentry
*, struct qstr
*);
301 extern struct dentry
*d_hash_and_lookup(struct dentry
*, struct qstr
*);
302 extern struct dentry
*__d_lookup(struct dentry
*, struct qstr
*);
303 extern struct dentry
*__d_lookup_rcu(struct dentry
*parent
, struct qstr
*name
,
304 unsigned *seq
, struct inode
**inode
);
307 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
308 * @dentry: dentry to take a ref on
309 * @seq: seqcount to verify against
310 * Returns: 0 on failure, else 1.
312 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
313 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
315 static inline int __d_rcu_to_refcount(struct dentry
*dentry
, unsigned seq
)
319 assert_spin_locked(&dentry
->d_lock
);
320 if (!read_seqcount_retry(&dentry
->d_seq
, seq
)) {
328 /* validate "insecure" dentry pointer */
329 extern int d_validate(struct dentry
*, struct dentry
*);
332 * helper function for dentry_operations.d_dname() members
334 extern char *dynamic_dname(struct dentry
*, char *, int, const char *, ...);
336 extern char *__d_path(const struct path
*path
, struct path
*root
, char *, int);
337 extern char *d_path(const struct path
*, char *, int);
338 extern char *d_path_with_unreachable(const struct path
*, char *, int);
339 extern char *dentry_path_raw(struct dentry
*, char *, int);
340 extern char *dentry_path(struct dentry
*, char *, int);
342 /* Allocation counts.. */
345 * dget, dget_dlock - get a reference to a dentry
346 * @dentry: dentry to get a reference to
348 * Given a dentry or %NULL pointer increment the reference count
349 * if appropriate and return the dentry. A dentry will not be
350 * destroyed when it has references.
352 static inline struct dentry
*dget_dlock(struct dentry
*dentry
)
359 static inline struct dentry
*dget(struct dentry
*dentry
)
362 spin_lock(&dentry
->d_lock
);
364 spin_unlock(&dentry
->d_lock
);
369 extern struct dentry
*dget_parent(struct dentry
*dentry
);
372 * d_unhashed - is dentry hashed
373 * @dentry: entry to check
375 * Returns true if the dentry passed is not currently hashed.
378 static inline int d_unhashed(struct dentry
*dentry
)
380 return (dentry
->d_flags
& DCACHE_UNHASHED
);
383 static inline int d_unlinked(struct dentry
*dentry
)
385 return d_unhashed(dentry
) && !IS_ROOT(dentry
);
388 static inline int cant_mount(struct dentry
*dentry
)
390 return (dentry
->d_flags
& DCACHE_CANT_MOUNT
);
393 static inline void dont_mount(struct dentry
*dentry
)
395 spin_lock(&dentry
->d_lock
);
396 dentry
->d_flags
|= DCACHE_CANT_MOUNT
;
397 spin_unlock(&dentry
->d_lock
);
400 extern void dput(struct dentry
*);
402 static inline int d_mountpoint(struct dentry
*dentry
)
404 return dentry
->d_flags
& DCACHE_MOUNTED
;
407 extern struct vfsmount
*lookup_mnt(struct path
*);
408 extern struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
);
410 extern int sysctl_vfs_cache_pressure
;
412 #endif /* __LINUX_DCACHE_H */