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1da177e4 LT |
1 | #ifndef __LINUX_DCACHE_H |
2 | #define __LINUX_DCACHE_H | |
3 | ||
4 | #ifdef __KERNEL__ | |
5 | ||
6 | #include <asm/atomic.h> | |
7 | #include <linux/list.h> | |
8 | #include <linux/spinlock.h> | |
9 | #include <linux/cache.h> | |
10 | #include <linux/rcupdate.h> | |
1da177e4 LT |
11 | |
12 | struct nameidata; | |
cf28b486 | 13 | struct path; |
1da177e4 LT |
14 | struct vfsmount; |
15 | ||
16 | /* | |
17 | * linux/include/linux/dcache.h | |
18 | * | |
19 | * Dirent cache data structures | |
20 | * | |
21 | * (C) Copyright 1997 Thomas Schoebel-Theuer, | |
22 | * with heavy changes by Linus Torvalds | |
23 | */ | |
24 | ||
25 | #define IS_ROOT(x) ((x) == (x)->d_parent) | |
26 | ||
27 | /* | |
28 | * "quick string" -- eases parameter passing, but more importantly | |
29 | * saves "metadata" about the string (ie length and the hash). | |
30 | * | |
31 | * hash comes first so it snuggles against d_parent in the | |
32 | * dentry. | |
33 | */ | |
34 | struct qstr { | |
35 | unsigned int hash; | |
36 | unsigned int len; | |
37 | const unsigned char *name; | |
38 | }; | |
39 | ||
40 | struct dentry_stat_t { | |
41 | int nr_dentry; | |
42 | int nr_unused; | |
43 | int age_limit; /* age in seconds */ | |
44 | int want_pages; /* pages requested by system */ | |
45 | int dummy[2]; | |
46 | }; | |
47 | extern struct dentry_stat_t dentry_stat; | |
48 | ||
49 | /* Name hashing routines. Initial hash value */ | |
50 | /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ | |
51 | #define init_name_hash() 0 | |
52 | ||
53 | /* partial hash update function. Assume roughly 4 bits per character */ | |
54 | static inline unsigned long | |
55 | partial_name_hash(unsigned long c, unsigned long prevhash) | |
56 | { | |
57 | return (prevhash + (c << 4) + (c >> 4)) * 11; | |
58 | } | |
59 | ||
60 | /* | |
61 | * Finally: cut down the number of bits to a int value (and try to avoid | |
62 | * losing bits) | |
63 | */ | |
64 | static inline unsigned long end_name_hash(unsigned long hash) | |
65 | { | |
66 | return (unsigned int) hash; | |
67 | } | |
68 | ||
69 | /* Compute the hash for a name string. */ | |
70 | static inline unsigned int | |
71 | full_name_hash(const unsigned char *name, unsigned int len) | |
72 | { | |
73 | unsigned long hash = init_name_hash(); | |
74 | while (len--) | |
75 | hash = partial_name_hash(*name++, hash); | |
76 | return end_name_hash(hash); | |
77 | } | |
78 | ||
79 | struct dcookie_struct; | |
80 | ||
81 | #define DNAME_INLINE_LEN_MIN 36 | |
82 | ||
83 | struct dentry { | |
84 | atomic_t d_count; | |
85 | unsigned int d_flags; /* protected by d_lock */ | |
86 | spinlock_t d_lock; /* per dentry lock */ | |
87 | struct inode *d_inode; /* Where the name belongs to - NULL is | |
88 | * negative */ | |
89 | /* | |
90 | * The next three fields are touched by __d_lookup. Place them here | |
3f4bb1f4 | 91 | * so they all fit in a cache line. |
1da177e4 | 92 | */ |
3f4bb1f4 | 93 | struct hlist_node d_hash; /* lookup hash list */ |
1da177e4 LT |
94 | struct dentry *d_parent; /* parent directory */ |
95 | struct qstr d_name; | |
96 | ||
97 | struct list_head d_lru; /* LRU list */ | |
5160ee6f ED |
98 | /* |
99 | * d_child and d_rcu can share memory | |
100 | */ | |
101 | union { | |
102 | struct list_head d_child; /* child of parent list */ | |
103 | struct rcu_head d_rcu; | |
104 | } d_u; | |
1da177e4 LT |
105 | struct list_head d_subdirs; /* our children */ |
106 | struct list_head d_alias; /* inode alias list */ | |
107 | unsigned long d_time; /* used by d_revalidate */ | |
108 | struct dentry_operations *d_op; | |
109 | struct super_block *d_sb; /* The root of the dentry tree */ | |
110 | void *d_fsdata; /* fs-specific data */ | |
47ba87e0 | 111 | #ifdef CONFIG_PROFILING |
1da177e4 | 112 | struct dcookie_struct *d_cookie; /* cookie, if any */ |
47ba87e0 | 113 | #endif |
1da177e4 LT |
114 | int d_mounted; |
115 | unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */ | |
116 | }; | |
117 | ||
a90b9c05 IM |
118 | /* |
119 | * dentry->d_lock spinlock nesting subclasses: | |
120 | * | |
121 | * 0: normal | |
122 | * 1: nested | |
123 | */ | |
124 | enum dentry_d_lock_class | |
125 | { | |
126 | DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ | |
127 | DENTRY_D_LOCK_NESTED | |
128 | }; | |
129 | ||
1da177e4 LT |
130 | struct dentry_operations { |
131 | int (*d_revalidate)(struct dentry *, struct nameidata *); | |
132 | int (*d_hash) (struct dentry *, struct qstr *); | |
133 | int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); | |
134 | int (*d_delete)(struct dentry *); | |
135 | void (*d_release)(struct dentry *); | |
136 | void (*d_iput)(struct dentry *, struct inode *); | |
c23fbb6b | 137 | char *(*d_dname)(struct dentry *, char *, int); |
1da177e4 LT |
138 | }; |
139 | ||
140 | /* the dentry parameter passed to d_hash and d_compare is the parent | |
141 | * directory of the entries to be compared. It is used in case these | |
142 | * functions need any directory specific information for determining | |
143 | * equivalency classes. Using the dentry itself might not work, as it | |
144 | * might be a negative dentry which has no information associated with | |
145 | * it */ | |
146 | ||
147 | /* | |
148 | locking rules: | |
149 | big lock dcache_lock d_lock may block | |
150 | d_revalidate: no no no yes | |
151 | d_hash no no no yes | |
152 | d_compare: no yes yes no | |
153 | d_delete: no yes no no | |
154 | d_release: no no no yes | |
155 | d_iput: no no no yes | |
156 | */ | |
157 | ||
158 | /* d_flags entries */ | |
159 | #define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */ | |
160 | #define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly | |
161 | * renamed" and has to be | |
162 | * deleted on the last dput() | |
163 | */ | |
164 | #define DCACHE_DISCONNECTED 0x0004 | |
165 | /* This dentry is possibly not currently connected to the dcache tree, | |
166 | * in which case its parent will either be itself, or will have this | |
167 | * flag as well. nfsd will not use a dentry with this bit set, but will | |
168 | * first endeavour to clear the bit either by discovering that it is | |
169 | * connected, or by performing lookup operations. Any filesystem which | |
170 | * supports nfsd_operations MUST have a lookup function which, if it finds | |
171 | * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move | |
172 | * that dentry into place and return that dentry rather than the passed one, | |
173 | * typically using d_splice_alias. | |
174 | */ | |
175 | ||
176 | #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ | |
177 | #define DCACHE_UNHASHED 0x0010 | |
178 | ||
c32ccd87 NP |
179 | #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */ |
180 | ||
1da177e4 | 181 | extern spinlock_t dcache_lock; |
74c3cbe3 | 182 | extern seqlock_t rename_lock; |
1da177e4 LT |
183 | |
184 | /** | |
185 | * d_drop - drop a dentry | |
186 | * @dentry: dentry to drop | |
187 | * | |
188 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
189 | * be found through a VFS lookup any more. Note that this is different from | |
190 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
191 | * possible, giving a successful _negative_ lookup, while d_drop will | |
192 | * just make the cache lookup fail. | |
193 | * | |
194 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
195 | * reason (NFS timeouts or autofs deletes). | |
196 | * | |
197 | * __d_drop requires dentry->d_lock. | |
198 | */ | |
199 | ||
200 | static inline void __d_drop(struct dentry *dentry) | |
201 | { | |
202 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { | |
203 | dentry->d_flags |= DCACHE_UNHASHED; | |
204 | hlist_del_rcu(&dentry->d_hash); | |
205 | } | |
206 | } | |
207 | ||
208 | static inline void d_drop(struct dentry *dentry) | |
209 | { | |
210 | spin_lock(&dcache_lock); | |
211 | spin_lock(&dentry->d_lock); | |
212 | __d_drop(dentry); | |
213 | spin_unlock(&dentry->d_lock); | |
214 | spin_unlock(&dcache_lock); | |
215 | } | |
216 | ||
217 | static inline int dname_external(struct dentry *dentry) | |
218 | { | |
219 | return dentry->d_name.name != dentry->d_iname; | |
220 | } | |
221 | ||
222 | /* | |
223 | * These are the low-level FS interfaces to the dcache.. | |
224 | */ | |
225 | extern void d_instantiate(struct dentry *, struct inode *); | |
226 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); | |
770bfad8 | 227 | extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); |
1da177e4 LT |
228 | extern void d_delete(struct dentry *); |
229 | ||
230 | /* allocate/de-allocate */ | |
231 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); | |
232 | extern struct dentry * d_alloc_anon(struct inode *); | |
233 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); | |
234 | extern void shrink_dcache_sb(struct super_block *); | |
235 | extern void shrink_dcache_parent(struct dentry *); | |
c636ebdb | 236 | extern void shrink_dcache_for_umount(struct super_block *); |
1da177e4 LT |
237 | extern int d_invalidate(struct dentry *); |
238 | ||
239 | /* only used at mount-time */ | |
240 | extern struct dentry * d_alloc_root(struct inode *); | |
241 | ||
242 | /* <clickety>-<click> the ramfs-type tree */ | |
243 | extern void d_genocide(struct dentry *); | |
244 | ||
245 | extern struct dentry *d_find_alias(struct inode *); | |
246 | extern void d_prune_aliases(struct inode *); | |
247 | ||
248 | /* test whether we have any submounts in a subdir tree */ | |
249 | extern int have_submounts(struct dentry *); | |
250 | ||
251 | /* | |
252 | * This adds the entry to the hash queues. | |
253 | */ | |
254 | extern void d_rehash(struct dentry *); | |
255 | ||
256 | /** | |
257 | * d_add - add dentry to hash queues | |
258 | * @entry: dentry to add | |
259 | * @inode: The inode to attach to this dentry | |
260 | * | |
261 | * This adds the entry to the hash queues and initializes @inode. | |
262 | * The entry was actually filled in earlier during d_alloc(). | |
263 | */ | |
264 | ||
265 | static inline void d_add(struct dentry *entry, struct inode *inode) | |
266 | { | |
267 | d_instantiate(entry, inode); | |
268 | d_rehash(entry); | |
269 | } | |
270 | ||
271 | /** | |
272 | * d_add_unique - add dentry to hash queues without aliasing | |
273 | * @entry: dentry to add | |
274 | * @inode: The inode to attach to this dentry | |
275 | * | |
276 | * This adds the entry to the hash queues and initializes @inode. | |
277 | * The entry was actually filled in earlier during d_alloc(). | |
278 | */ | |
279 | static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) | |
280 | { | |
281 | struct dentry *res; | |
282 | ||
283 | res = d_instantiate_unique(entry, inode); | |
284 | d_rehash(res != NULL ? res : entry); | |
285 | return res; | |
286 | } | |
287 | ||
288 | /* used for rename() and baskets */ | |
289 | extern void d_move(struct dentry *, struct dentry *); | |
290 | ||
291 | /* appendix may either be NULL or be used for transname suffixes */ | |
292 | extern struct dentry * d_lookup(struct dentry *, struct qstr *); | |
293 | extern struct dentry * __d_lookup(struct dentry *, struct qstr *); | |
3e7e241f | 294 | extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *); |
1da177e4 LT |
295 | |
296 | /* validate "insecure" dentry pointer */ | |
297 | extern int d_validate(struct dentry *, struct dentry *); | |
298 | ||
c23fbb6b ED |
299 | /* |
300 | * helper function for dentry_operations.d_dname() members | |
301 | */ | |
302 | extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); | |
303 | ||
cf28b486 | 304 | extern char *d_path(struct path *, char *, int); |
6092d048 | 305 | extern char *dentry_path(struct dentry *, char *, int); |
cf28b486 | 306 | |
1da177e4 LT |
307 | /* Allocation counts.. */ |
308 | ||
309 | /** | |
310 | * dget, dget_locked - get a reference to a dentry | |
311 | * @dentry: dentry to get a reference to | |
312 | * | |
313 | * Given a dentry or %NULL pointer increment the reference count | |
314 | * if appropriate and return the dentry. A dentry will not be | |
315 | * destroyed when it has references. dget() should never be | |
316 | * called for dentries with zero reference counter. For these cases | |
317 | * (preferably none, functions in dcache.c are sufficient for normal | |
318 | * needs and they take necessary precautions) you should hold dcache_lock | |
319 | * and call dget_locked() instead of dget(). | |
320 | */ | |
321 | ||
322 | static inline struct dentry *dget(struct dentry *dentry) | |
323 | { | |
324 | if (dentry) { | |
325 | BUG_ON(!atomic_read(&dentry->d_count)); | |
326 | atomic_inc(&dentry->d_count); | |
327 | } | |
328 | return dentry; | |
329 | } | |
330 | ||
331 | extern struct dentry * dget_locked(struct dentry *); | |
332 | ||
333 | /** | |
334 | * d_unhashed - is dentry hashed | |
335 | * @dentry: entry to check | |
336 | * | |
337 | * Returns true if the dentry passed is not currently hashed. | |
338 | */ | |
339 | ||
340 | static inline int d_unhashed(struct dentry *dentry) | |
341 | { | |
342 | return (dentry->d_flags & DCACHE_UNHASHED); | |
343 | } | |
344 | ||
345 | static inline struct dentry *dget_parent(struct dentry *dentry) | |
346 | { | |
347 | struct dentry *ret; | |
348 | ||
349 | spin_lock(&dentry->d_lock); | |
350 | ret = dget(dentry->d_parent); | |
351 | spin_unlock(&dentry->d_lock); | |
352 | return ret; | |
353 | } | |
354 | ||
355 | extern void dput(struct dentry *); | |
356 | ||
357 | static inline int d_mountpoint(struct dentry *dentry) | |
358 | { | |
359 | return dentry->d_mounted; | |
360 | } | |
361 | ||
362 | extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *); | |
363 | extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); | |
364 | ||
365 | extern int sysctl_vfs_cache_pressure; | |
366 | ||
367 | #endif /* __KERNEL__ */ | |
368 | ||
369 | #endif /* __LINUX_DCACHE_H */ |