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1da177e4 LT |
1 | #ifndef __LINUX_DCACHE_H |
2 | #define __LINUX_DCACHE_H | |
3 | ||
1da177e4 LT |
4 | #include <asm/atomic.h> |
5 | #include <linux/list.h> | |
82524746 | 6 | #include <linux/rculist.h> |
1da177e4 LT |
7 | #include <linux/spinlock.h> |
8 | #include <linux/cache.h> | |
9 | #include <linux/rcupdate.h> | |
1da177e4 LT |
10 | |
11 | struct nameidata; | |
cf28b486 | 12 | struct path; |
1da177e4 LT |
13 | struct vfsmount; |
14 | ||
15 | /* | |
16 | * linux/include/linux/dcache.h | |
17 | * | |
18 | * Dirent cache data structures | |
19 | * | |
20 | * (C) Copyright 1997 Thomas Schoebel-Theuer, | |
21 | * with heavy changes by Linus Torvalds | |
22 | */ | |
23 | ||
24 | #define IS_ROOT(x) ((x) == (x)->d_parent) | |
25 | ||
26 | /* | |
27 | * "quick string" -- eases parameter passing, but more importantly | |
28 | * saves "metadata" about the string (ie length and the hash). | |
29 | * | |
30 | * hash comes first so it snuggles against d_parent in the | |
31 | * dentry. | |
32 | */ | |
33 | struct qstr { | |
34 | unsigned int hash; | |
35 | unsigned int len; | |
36 | const unsigned char *name; | |
37 | }; | |
38 | ||
39 | struct dentry_stat_t { | |
40 | int nr_dentry; | |
41 | int nr_unused; | |
42 | int age_limit; /* age in seconds */ | |
43 | int want_pages; /* pages requested by system */ | |
44 | int dummy[2]; | |
45 | }; | |
46 | extern struct dentry_stat_t dentry_stat; | |
47 | ||
48 | /* Name hashing routines. Initial hash value */ | |
49 | /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ | |
50 | #define init_name_hash() 0 | |
51 | ||
52 | /* partial hash update function. Assume roughly 4 bits per character */ | |
53 | static inline unsigned long | |
54 | partial_name_hash(unsigned long c, unsigned long prevhash) | |
55 | { | |
56 | return (prevhash + (c << 4) + (c >> 4)) * 11; | |
57 | } | |
58 | ||
59 | /* | |
60 | * Finally: cut down the number of bits to a int value (and try to avoid | |
61 | * losing bits) | |
62 | */ | |
63 | static inline unsigned long end_name_hash(unsigned long hash) | |
64 | { | |
65 | return (unsigned int) hash; | |
66 | } | |
67 | ||
68 | /* Compute the hash for a name string. */ | |
69 | static inline unsigned int | |
70 | full_name_hash(const unsigned char *name, unsigned int len) | |
71 | { | |
72 | unsigned long hash = init_name_hash(); | |
73 | while (len--) | |
74 | hash = partial_name_hash(*name++, hash); | |
75 | return end_name_hash(hash); | |
76 | } | |
77 | ||
c2452f32 NP |
78 | /* |
79 | * Try to keep struct dentry aligned on 64 byte cachelines (this will | |
80 | * give reasonable cacheline footprint with larger lines without the | |
81 | * large memory footprint increase). | |
82 | */ | |
83 | #ifdef CONFIG_64BIT | |
84 | #define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */ | |
85 | #else | |
86 | #define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */ | |
87 | #endif | |
1da177e4 LT |
88 | |
89 | struct dentry { | |
90 | atomic_t d_count; | |
91 | unsigned int d_flags; /* protected by d_lock */ | |
92 | spinlock_t d_lock; /* per dentry lock */ | |
c2452f32 | 93 | int d_mounted; |
1da177e4 LT |
94 | struct inode *d_inode; /* Where the name belongs to - NULL is |
95 | * negative */ | |
96 | /* | |
97 | * The next three fields are touched by __d_lookup. Place them here | |
3f4bb1f4 | 98 | * so they all fit in a cache line. |
1da177e4 | 99 | */ |
3f4bb1f4 | 100 | struct hlist_node d_hash; /* lookup hash list */ |
1da177e4 LT |
101 | struct dentry *d_parent; /* parent directory */ |
102 | struct qstr d_name; | |
103 | ||
104 | struct list_head d_lru; /* LRU list */ | |
5160ee6f ED |
105 | /* |
106 | * d_child and d_rcu can share memory | |
107 | */ | |
108 | union { | |
109 | struct list_head d_child; /* child of parent list */ | |
110 | struct rcu_head d_rcu; | |
111 | } d_u; | |
1da177e4 LT |
112 | struct list_head d_subdirs; /* our children */ |
113 | struct list_head d_alias; /* inode alias list */ | |
114 | unsigned long d_time; /* used by d_revalidate */ | |
e56980d4 | 115 | const struct dentry_operations *d_op; |
1da177e4 LT |
116 | struct super_block *d_sb; /* The root of the dentry tree */ |
117 | void *d_fsdata; /* fs-specific data */ | |
c2452f32 | 118 | |
1da177e4 LT |
119 | unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */ |
120 | }; | |
121 | ||
a90b9c05 IM |
122 | /* |
123 | * dentry->d_lock spinlock nesting subclasses: | |
124 | * | |
125 | * 0: normal | |
126 | * 1: nested | |
127 | */ | |
128 | enum dentry_d_lock_class | |
129 | { | |
130 | DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ | |
131 | DENTRY_D_LOCK_NESTED | |
132 | }; | |
133 | ||
1da177e4 LT |
134 | struct dentry_operations { |
135 | int (*d_revalidate)(struct dentry *, struct nameidata *); | |
136 | int (*d_hash) (struct dentry *, struct qstr *); | |
137 | int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); | |
138 | int (*d_delete)(struct dentry *); | |
139 | void (*d_release)(struct dentry *); | |
140 | void (*d_iput)(struct dentry *, struct inode *); | |
c23fbb6b | 141 | char *(*d_dname)(struct dentry *, char *, int); |
1da177e4 LT |
142 | }; |
143 | ||
144 | /* the dentry parameter passed to d_hash and d_compare is the parent | |
145 | * directory of the entries to be compared. It is used in case these | |
146 | * functions need any directory specific information for determining | |
147 | * equivalency classes. Using the dentry itself might not work, as it | |
148 | * might be a negative dentry which has no information associated with | |
149 | * it */ | |
150 | ||
151 | /* | |
152 | locking rules: | |
153 | big lock dcache_lock d_lock may block | |
154 | d_revalidate: no no no yes | |
155 | d_hash no no no yes | |
156 | d_compare: no yes yes no | |
157 | d_delete: no yes no no | |
158 | d_release: no no no yes | |
159 | d_iput: no no no yes | |
160 | */ | |
161 | ||
162 | /* d_flags entries */ | |
163 | #define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */ | |
164 | #define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly | |
165 | * renamed" and has to be | |
166 | * deleted on the last dput() | |
167 | */ | |
168 | #define DCACHE_DISCONNECTED 0x0004 | |
169 | /* This dentry is possibly not currently connected to the dcache tree, | |
170 | * in which case its parent will either be itself, or will have this | |
171 | * flag as well. nfsd will not use a dentry with this bit set, but will | |
172 | * first endeavour to clear the bit either by discovering that it is | |
173 | * connected, or by performing lookup operations. Any filesystem which | |
174 | * supports nfsd_operations MUST have a lookup function which, if it finds | |
175 | * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move | |
176 | * that dentry into place and return that dentry rather than the passed one, | |
177 | * typically using d_splice_alias. | |
178 | */ | |
179 | ||
180 | #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ | |
181 | #define DCACHE_UNHASHED 0x0010 | |
182 | ||
c28f7e56 | 183 | #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched by inotify */ |
c32ccd87 | 184 | |
c2452f32 NP |
185 | #define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */ |
186 | ||
c28f7e56 EP |
187 | #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080 /* Parent inode is watched by some fsnotify listener */ |
188 | ||
1da177e4 | 189 | extern spinlock_t dcache_lock; |
74c3cbe3 | 190 | extern seqlock_t rename_lock; |
1da177e4 LT |
191 | |
192 | /** | |
193 | * d_drop - drop a dentry | |
194 | * @dentry: dentry to drop | |
195 | * | |
196 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
197 | * be found through a VFS lookup any more. Note that this is different from | |
198 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
199 | * possible, giving a successful _negative_ lookup, while d_drop will | |
200 | * just make the cache lookup fail. | |
201 | * | |
202 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
203 | * reason (NFS timeouts or autofs deletes). | |
204 | * | |
205 | * __d_drop requires dentry->d_lock. | |
206 | */ | |
207 | ||
208 | static inline void __d_drop(struct dentry *dentry) | |
209 | { | |
210 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { | |
211 | dentry->d_flags |= DCACHE_UNHASHED; | |
212 | hlist_del_rcu(&dentry->d_hash); | |
213 | } | |
214 | } | |
215 | ||
216 | static inline void d_drop(struct dentry *dentry) | |
217 | { | |
218 | spin_lock(&dcache_lock); | |
219 | spin_lock(&dentry->d_lock); | |
220 | __d_drop(dentry); | |
221 | spin_unlock(&dentry->d_lock); | |
222 | spin_unlock(&dcache_lock); | |
223 | } | |
224 | ||
225 | static inline int dname_external(struct dentry *dentry) | |
226 | { | |
227 | return dentry->d_name.name != dentry->d_iname; | |
228 | } | |
229 | ||
230 | /* | |
231 | * These are the low-level FS interfaces to the dcache.. | |
232 | */ | |
233 | extern void d_instantiate(struct dentry *, struct inode *); | |
234 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); | |
770bfad8 | 235 | extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); |
1da177e4 LT |
236 | extern void d_delete(struct dentry *); |
237 | ||
238 | /* allocate/de-allocate */ | |
239 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); | |
1da177e4 | 240 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); |
e45b590b | 241 | extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); |
4ea3ada2 | 242 | extern struct dentry * d_obtain_alias(struct inode *); |
1da177e4 LT |
243 | extern void shrink_dcache_sb(struct super_block *); |
244 | extern void shrink_dcache_parent(struct dentry *); | |
c636ebdb | 245 | extern void shrink_dcache_for_umount(struct super_block *); |
1da177e4 LT |
246 | extern int d_invalidate(struct dentry *); |
247 | ||
248 | /* only used at mount-time */ | |
249 | extern struct dentry * d_alloc_root(struct inode *); | |
250 | ||
251 | /* <clickety>-<click> the ramfs-type tree */ | |
252 | extern void d_genocide(struct dentry *); | |
253 | ||
254 | extern struct dentry *d_find_alias(struct inode *); | |
255 | extern void d_prune_aliases(struct inode *); | |
256 | ||
257 | /* test whether we have any submounts in a subdir tree */ | |
258 | extern int have_submounts(struct dentry *); | |
259 | ||
260 | /* | |
261 | * This adds the entry to the hash queues. | |
262 | */ | |
263 | extern void d_rehash(struct dentry *); | |
264 | ||
265 | /** | |
266 | * d_add - add dentry to hash queues | |
267 | * @entry: dentry to add | |
268 | * @inode: The inode to attach to this dentry | |
269 | * | |
270 | * This adds the entry to the hash queues and initializes @inode. | |
271 | * The entry was actually filled in earlier during d_alloc(). | |
272 | */ | |
273 | ||
274 | static inline void d_add(struct dentry *entry, struct inode *inode) | |
275 | { | |
276 | d_instantiate(entry, inode); | |
277 | d_rehash(entry); | |
278 | } | |
279 | ||
280 | /** | |
281 | * d_add_unique - add dentry to hash queues without aliasing | |
282 | * @entry: dentry to add | |
283 | * @inode: The inode to attach to this dentry | |
284 | * | |
285 | * This adds the entry to the hash queues and initializes @inode. | |
286 | * The entry was actually filled in earlier during d_alloc(). | |
287 | */ | |
288 | static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) | |
289 | { | |
290 | struct dentry *res; | |
291 | ||
292 | res = d_instantiate_unique(entry, inode); | |
293 | d_rehash(res != NULL ? res : entry); | |
294 | return res; | |
295 | } | |
296 | ||
297 | /* used for rename() and baskets */ | |
298 | extern void d_move(struct dentry *, struct dentry *); | |
e2761a11 | 299 | extern struct dentry *d_ancestor(struct dentry *, struct dentry *); |
1da177e4 LT |
300 | |
301 | /* appendix may either be NULL or be used for transname suffixes */ | |
302 | extern struct dentry * d_lookup(struct dentry *, struct qstr *); | |
303 | extern struct dentry * __d_lookup(struct dentry *, struct qstr *); | |
3e7e241f | 304 | extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *); |
1da177e4 LT |
305 | |
306 | /* validate "insecure" dentry pointer */ | |
307 | extern int d_validate(struct dentry *, struct dentry *); | |
308 | ||
c23fbb6b ED |
309 | /* |
310 | * helper function for dentry_operations.d_dname() members | |
311 | */ | |
312 | extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); | |
313 | ||
9d1bc601 | 314 | extern char *__d_path(const struct path *path, struct path *root, char *, int); |
20d4fdc1 | 315 | extern char *d_path(const struct path *, char *, int); |
6092d048 | 316 | extern char *dentry_path(struct dentry *, char *, int); |
cf28b486 | 317 | |
1da177e4 LT |
318 | /* Allocation counts.. */ |
319 | ||
320 | /** | |
321 | * dget, dget_locked - get a reference to a dentry | |
322 | * @dentry: dentry to get a reference to | |
323 | * | |
324 | * Given a dentry or %NULL pointer increment the reference count | |
325 | * if appropriate and return the dentry. A dentry will not be | |
326 | * destroyed when it has references. dget() should never be | |
327 | * called for dentries with zero reference counter. For these cases | |
328 | * (preferably none, functions in dcache.c are sufficient for normal | |
329 | * needs and they take necessary precautions) you should hold dcache_lock | |
330 | * and call dget_locked() instead of dget(). | |
331 | */ | |
332 | ||
333 | static inline struct dentry *dget(struct dentry *dentry) | |
334 | { | |
335 | if (dentry) { | |
336 | BUG_ON(!atomic_read(&dentry->d_count)); | |
337 | atomic_inc(&dentry->d_count); | |
338 | } | |
339 | return dentry; | |
340 | } | |
341 | ||
342 | extern struct dentry * dget_locked(struct dentry *); | |
343 | ||
344 | /** | |
345 | * d_unhashed - is dentry hashed | |
346 | * @dentry: entry to check | |
347 | * | |
348 | * Returns true if the dentry passed is not currently hashed. | |
349 | */ | |
350 | ||
351 | static inline int d_unhashed(struct dentry *dentry) | |
352 | { | |
353 | return (dentry->d_flags & DCACHE_UNHASHED); | |
354 | } | |
355 | ||
f3da392e AD |
356 | static inline int d_unlinked(struct dentry *dentry) |
357 | { | |
358 | return d_unhashed(dentry) && !IS_ROOT(dentry); | |
359 | } | |
360 | ||
1da177e4 LT |
361 | static inline struct dentry *dget_parent(struct dentry *dentry) |
362 | { | |
363 | struct dentry *ret; | |
364 | ||
365 | spin_lock(&dentry->d_lock); | |
366 | ret = dget(dentry->d_parent); | |
367 | spin_unlock(&dentry->d_lock); | |
368 | return ret; | |
369 | } | |
370 | ||
371 | extern void dput(struct dentry *); | |
372 | ||
373 | static inline int d_mountpoint(struct dentry *dentry) | |
374 | { | |
375 | return dentry->d_mounted; | |
376 | } | |
377 | ||
1c755af4 | 378 | extern struct vfsmount *lookup_mnt(struct path *); |
1da177e4 LT |
379 | extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); |
380 | ||
381 | extern int sysctl_vfs_cache_pressure; | |
382 | ||
1da177e4 | 383 | #endif /* __LINUX_DCACHE_H */ |