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>
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;
32 #define HASH_LEN_DECLARE u32 len; u32 hash;
36 * "quick string" -- eases parameter passing, but more importantly
37 * saves "metadata" about the string (ie length and the hash).
39 * hash comes first so it snuggles against d_parent in the
49 const unsigned char *name
;
52 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
53 #define hashlen_hash(hashlen) ((u32) (hashlen))
54 #define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
56 struct dentry_stat_t
{
59 int age_limit
; /* age in seconds */
60 int want_pages
; /* pages requested by system */
63 extern struct dentry_stat_t dentry_stat
;
65 /* Name hashing routines. Initial hash value */
66 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
67 #define init_name_hash() 0
69 /* partial hash update function. Assume roughly 4 bits per character */
70 static inline unsigned long
71 partial_name_hash(unsigned long c
, unsigned long prevhash
)
73 return (prevhash
+ (c
<< 4) + (c
>> 4)) * 11;
77 * Finally: cut down the number of bits to a int value (and try to avoid
80 static inline unsigned long end_name_hash(unsigned long hash
)
82 return (unsigned int) hash
;
85 /* Compute the hash for a name string. */
86 extern unsigned int full_name_hash(const unsigned char *, unsigned int);
89 * Try to keep struct dentry aligned on 64 byte cachelines (this will
90 * give reasonable cacheline footprint with larger lines without the
91 * large memory footprint increase).
94 # define DNAME_INLINE_LEN 32 /* 192 bytes */
97 # define DNAME_INLINE_LEN 36 /* 128 bytes */
99 # define DNAME_INLINE_LEN 40 /* 128 bytes */
104 /* RCU lookup touched fields */
105 unsigned int d_flags
; /* protected by d_lock */
106 seqcount_t d_seq
; /* per dentry seqlock */
107 struct hlist_bl_node d_hash
; /* lookup hash list */
108 struct dentry
*d_parent
; /* parent directory */
110 struct inode
*d_inode
; /* Where the name belongs to - NULL is
112 unsigned char d_iname
[DNAME_INLINE_LEN
]; /* small names */
114 /* Ref lookup also touches following */
115 unsigned int d_count
; /* protected by d_lock */
116 spinlock_t d_lock
; /* per dentry lock */
117 const struct dentry_operations
*d_op
;
118 struct super_block
*d_sb
; /* The root of the dentry tree */
119 unsigned long d_time
; /* used by d_revalidate */
120 void *d_fsdata
; /* fs-specific data */
122 struct list_head d_lru
; /* LRU list */
124 * d_child and d_rcu can share memory
127 struct list_head d_child
; /* child of parent list */
128 struct rcu_head d_rcu
;
130 struct list_head d_subdirs
; /* our children */
131 struct hlist_node d_alias
; /* inode alias list */
135 * dentry->d_lock spinlock nesting subclasses:
140 enum dentry_d_lock_class
142 DENTRY_D_LOCK_NORMAL
, /* implicitly used by plain spin_lock() APIs. */
146 struct dentry_operations
{
147 int (*d_revalidate
)(struct dentry
*, unsigned int);
148 int (*d_weak_revalidate
)(struct dentry
*, unsigned int);
149 int (*d_hash
)(const struct dentry
*, struct qstr
*);
150 int (*d_compare
)(const struct dentry
*, const struct dentry
*,
151 unsigned int, const char *, const struct qstr
*);
152 int (*d_delete
)(const struct dentry
*);
153 void (*d_release
)(struct dentry
*);
154 void (*d_prune
)(struct dentry
*);
155 void (*d_iput
)(struct dentry
*, struct inode
*);
156 char *(*d_dname
)(struct dentry
*, char *, int);
157 struct vfsmount
*(*d_automount
)(struct path
*);
158 int (*d_manage
)(struct dentry
*, bool);
159 } ____cacheline_aligned
;
162 * Locking rules for dentry_operations callbacks are to be found in
163 * Documentation/filesystems/Locking. Keep it updated!
165 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
166 * Keep it updated too!
169 /* d_flags entries */
170 #define DCACHE_OP_HASH 0x0001
171 #define DCACHE_OP_COMPARE 0x0002
172 #define DCACHE_OP_REVALIDATE 0x0004
173 #define DCACHE_OP_DELETE 0x0008
174 #define DCACHE_OP_PRUNE 0x0010
176 #define DCACHE_DISCONNECTED 0x0020
177 /* This dentry is possibly not currently connected to the dcache tree, in
178 * which case its parent will either be itself, or will have this flag as
179 * well. nfsd will not use a dentry with this bit set, but will first
180 * endeavour to clear the bit either by discovering that it is connected,
181 * or by performing lookup operations. Any filesystem which supports
182 * nfsd_operations MUST have a lookup function which, if it finds a
183 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
184 * dentry into place and return that dentry rather than the passed one,
185 * typically using d_splice_alias. */
187 #define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */
188 #define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */
190 #define DCACHE_CANT_MOUNT 0x0100
191 #define DCACHE_GENOCIDE 0x0200
192 #define DCACHE_SHRINK_LIST 0x0400
194 #define DCACHE_OP_WEAK_REVALIDATE 0x0800
196 #define DCACHE_NFSFS_RENAMED 0x1000
197 /* this dentry has been "silly renamed" and has to be deleted on the last
199 #define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
200 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
201 /* Parent inode is watched by some fsnotify listener */
203 #define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
204 #define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
205 #define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
206 #define DCACHE_MANAGED_DENTRY \
207 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
209 #define DCACHE_DENTRY_KILLED 0x100000
211 extern seqlock_t rename_lock
;
213 static inline int dname_external(struct dentry
*dentry
)
215 return dentry
->d_name
.name
!= dentry
->d_iname
;
219 * These are the low-level FS interfaces to the dcache..
221 extern void d_instantiate(struct dentry
*, struct inode
*);
222 extern struct dentry
* d_instantiate_unique(struct dentry
*, struct inode
*);
223 extern struct dentry
* d_materialise_unique(struct dentry
*, struct inode
*);
224 extern void __d_drop(struct dentry
*dentry
);
225 extern void d_drop(struct dentry
*dentry
);
226 extern void d_delete(struct dentry
*);
227 extern void d_set_d_op(struct dentry
*dentry
, const struct dentry_operations
*op
);
229 /* allocate/de-allocate */
230 extern struct dentry
* d_alloc(struct dentry
*, const struct qstr
*);
231 extern struct dentry
* d_alloc_pseudo(struct super_block
*, const struct qstr
*);
232 extern struct dentry
* d_splice_alias(struct inode
*, struct dentry
*);
233 extern struct dentry
* d_add_ci(struct dentry
*, struct inode
*, struct qstr
*);
234 extern struct dentry
*d_find_any_alias(struct inode
*inode
);
235 extern struct dentry
* d_obtain_alias(struct inode
*);
236 extern void shrink_dcache_sb(struct super_block
*);
237 extern void shrink_dcache_parent(struct dentry
*);
238 extern void shrink_dcache_for_umount(struct super_block
*);
239 extern int d_invalidate(struct dentry
*);
241 /* only used at mount-time */
242 extern struct dentry
* d_make_root(struct inode
*);
244 /* <clickety>-<click> the ramfs-type tree */
245 extern void d_genocide(struct dentry
*);
247 extern void d_tmpfile(struct dentry
*, struct inode
*);
249 extern struct dentry
*d_find_alias(struct inode
*);
250 extern void d_prune_aliases(struct inode
*);
252 /* test whether we have any submounts in a subdir tree */
253 extern int have_submounts(struct dentry
*);
256 * This adds the entry to the hash queues.
258 extern void d_rehash(struct dentry
*);
261 * d_add - add dentry to hash queues
262 * @entry: dentry to add
263 * @inode: The inode to attach to this dentry
265 * This adds the entry to the hash queues and initializes @inode.
266 * The entry was actually filled in earlier during d_alloc().
269 static inline void d_add(struct dentry
*entry
, struct inode
*inode
)
271 d_instantiate(entry
, inode
);
276 * d_add_unique - add dentry to hash queues without aliasing
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().
283 static inline struct dentry
*d_add_unique(struct dentry
*entry
, struct inode
*inode
)
287 res
= d_instantiate_unique(entry
, inode
);
288 d_rehash(res
!= NULL
? res
: entry
);
292 extern void dentry_update_name_case(struct dentry
*, struct qstr
*);
294 /* used for rename() and baskets */
295 extern void d_move(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
);
306 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
307 * @dentry: dentry to take a ref on
308 * @seq: seqcount to verify against
309 * Returns: 0 on failure, else 1.
311 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
312 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
314 static inline int __d_rcu_to_refcount(struct dentry
*dentry
, unsigned seq
)
318 assert_spin_locked(&dentry
->d_lock
);
319 if (!read_seqcount_retry(&dentry
->d_seq
, seq
)) {
327 static inline unsigned d_count(struct dentry
*dentry
)
329 return dentry
->d_count
;
332 /* validate "insecure" dentry pointer */
333 extern int d_validate(struct dentry
*, struct dentry
*);
336 * helper function for dentry_operations.d_dname() members
338 extern char *dynamic_dname(struct dentry
*, char *, int, const char *, ...);
340 extern char *__d_path(const struct path
*, const struct path
*, char *, int);
341 extern char *d_absolute_path(const struct path
*, char *, int);
342 extern char *d_path(const struct path
*, char *, int);
343 extern char *dentry_path_raw(struct dentry
*, char *, int);
344 extern char *dentry_path(struct dentry
*, char *, int);
346 /* Allocation counts.. */
349 * dget, dget_dlock - get a reference to a dentry
350 * @dentry: dentry to get a reference to
352 * Given a dentry or %NULL pointer increment the reference count
353 * if appropriate and return the dentry. A dentry will not be
354 * destroyed when it has references.
356 static inline struct dentry
*dget_dlock(struct dentry
*dentry
)
363 static inline struct dentry
*dget(struct dentry
*dentry
)
366 spin_lock(&dentry
->d_lock
);
368 spin_unlock(&dentry
->d_lock
);
373 extern struct dentry
*dget_parent(struct dentry
*dentry
);
376 * d_unhashed - is dentry hashed
377 * @dentry: entry to check
379 * Returns true if the dentry passed is not currently hashed.
382 static inline int d_unhashed(struct dentry
*dentry
)
384 return hlist_bl_unhashed(&dentry
->d_hash
);
387 static inline int d_unlinked(struct dentry
*dentry
)
389 return d_unhashed(dentry
) && !IS_ROOT(dentry
);
392 static inline int cant_mount(struct dentry
*dentry
)
394 return (dentry
->d_flags
& DCACHE_CANT_MOUNT
);
397 static inline void dont_mount(struct dentry
*dentry
)
399 spin_lock(&dentry
->d_lock
);
400 dentry
->d_flags
|= DCACHE_CANT_MOUNT
;
401 spin_unlock(&dentry
->d_lock
);
404 extern void dput(struct dentry
*);
406 static inline bool d_managed(struct dentry
*dentry
)
408 return dentry
->d_flags
& DCACHE_MANAGED_DENTRY
;
411 static inline bool d_mountpoint(struct dentry
*dentry
)
413 return dentry
->d_flags
& DCACHE_MOUNTED
;
416 extern int sysctl_vfs_cache_pressure
;
418 #endif /* __LINUX_DCACHE_H */