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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; | |
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 | ||
78 | struct dcookie_struct; | |
79 | ||
80 | #define DNAME_INLINE_LEN_MIN 36 | |
81 | ||
82 | struct dentry { | |
83 | atomic_t d_count; | |
84 | unsigned int d_flags; /* protected by d_lock */ | |
85 | spinlock_t d_lock; /* per dentry lock */ | |
86 | struct inode *d_inode; /* Where the name belongs to - NULL is | |
87 | * negative */ | |
88 | /* | |
89 | * The next three fields are touched by __d_lookup. Place them here | |
3f4bb1f4 | 90 | * so they all fit in a cache line. |
1da177e4 | 91 | */ |
3f4bb1f4 | 92 | struct hlist_node d_hash; /* lookup hash list */ |
1da177e4 LT |
93 | struct dentry *d_parent; /* parent directory */ |
94 | struct qstr d_name; | |
95 | ||
96 | struct list_head d_lru; /* LRU list */ | |
5160ee6f ED |
97 | /* |
98 | * d_child and d_rcu can share memory | |
99 | */ | |
100 | union { | |
101 | struct list_head d_child; /* child of parent list */ | |
102 | struct rcu_head d_rcu; | |
103 | } d_u; | |
1da177e4 LT |
104 | struct list_head d_subdirs; /* our children */ |
105 | struct list_head d_alias; /* inode alias list */ | |
106 | unsigned long d_time; /* used by d_revalidate */ | |
107 | struct dentry_operations *d_op; | |
108 | struct super_block *d_sb; /* The root of the dentry tree */ | |
109 | void *d_fsdata; /* fs-specific data */ | |
47ba87e0 | 110 | #ifdef CONFIG_PROFILING |
1da177e4 | 111 | struct dcookie_struct *d_cookie; /* cookie, if any */ |
47ba87e0 | 112 | #endif |
1da177e4 LT |
113 | int d_mounted; |
114 | unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */ | |
115 | }; | |
116 | ||
a90b9c05 IM |
117 | /* |
118 | * dentry->d_lock spinlock nesting subclasses: | |
119 | * | |
120 | * 0: normal | |
121 | * 1: nested | |
122 | */ | |
123 | enum dentry_d_lock_class | |
124 | { | |
125 | DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ | |
126 | DENTRY_D_LOCK_NESTED | |
127 | }; | |
128 | ||
1da177e4 LT |
129 | struct dentry_operations { |
130 | int (*d_revalidate)(struct dentry *, struct nameidata *); | |
131 | int (*d_hash) (struct dentry *, struct qstr *); | |
132 | int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); | |
133 | int (*d_delete)(struct dentry *); | |
134 | void (*d_release)(struct dentry *); | |
135 | void (*d_iput)(struct dentry *, struct inode *); | |
136 | }; | |
137 | ||
138 | /* the dentry parameter passed to d_hash and d_compare is the parent | |
139 | * directory of the entries to be compared. It is used in case these | |
140 | * functions need any directory specific information for determining | |
141 | * equivalency classes. Using the dentry itself might not work, as it | |
142 | * might be a negative dentry which has no information associated with | |
143 | * it */ | |
144 | ||
145 | /* | |
146 | locking rules: | |
147 | big lock dcache_lock d_lock may block | |
148 | d_revalidate: no no no yes | |
149 | d_hash no no no yes | |
150 | d_compare: no yes yes no | |
151 | d_delete: no yes no no | |
152 | d_release: no no no yes | |
153 | d_iput: no no no yes | |
154 | */ | |
155 | ||
156 | /* d_flags entries */ | |
157 | #define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */ | |
158 | #define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly | |
159 | * renamed" and has to be | |
160 | * deleted on the last dput() | |
161 | */ | |
162 | #define DCACHE_DISCONNECTED 0x0004 | |
163 | /* This dentry is possibly not currently connected to the dcache tree, | |
164 | * in which case its parent will either be itself, or will have this | |
165 | * flag as well. nfsd will not use a dentry with this bit set, but will | |
166 | * first endeavour to clear the bit either by discovering that it is | |
167 | * connected, or by performing lookup operations. Any filesystem which | |
168 | * supports nfsd_operations MUST have a lookup function which, if it finds | |
169 | * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move | |
170 | * that dentry into place and return that dentry rather than the passed one, | |
171 | * typically using d_splice_alias. | |
172 | */ | |
173 | ||
174 | #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ | |
175 | #define DCACHE_UNHASHED 0x0010 | |
176 | ||
c32ccd87 NP |
177 | #define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */ |
178 | ||
1da177e4 LT |
179 | extern spinlock_t dcache_lock; |
180 | ||
181 | /** | |
182 | * d_drop - drop a dentry | |
183 | * @dentry: dentry to drop | |
184 | * | |
185 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
186 | * be found through a VFS lookup any more. Note that this is different from | |
187 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
188 | * possible, giving a successful _negative_ lookup, while d_drop will | |
189 | * just make the cache lookup fail. | |
190 | * | |
191 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
192 | * reason (NFS timeouts or autofs deletes). | |
193 | * | |
194 | * __d_drop requires dentry->d_lock. | |
195 | */ | |
196 | ||
197 | static inline void __d_drop(struct dentry *dentry) | |
198 | { | |
199 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { | |
200 | dentry->d_flags |= DCACHE_UNHASHED; | |
201 | hlist_del_rcu(&dentry->d_hash); | |
202 | } | |
203 | } | |
204 | ||
205 | static inline void d_drop(struct dentry *dentry) | |
206 | { | |
207 | spin_lock(&dcache_lock); | |
208 | spin_lock(&dentry->d_lock); | |
209 | __d_drop(dentry); | |
210 | spin_unlock(&dentry->d_lock); | |
211 | spin_unlock(&dcache_lock); | |
212 | } | |
213 | ||
214 | static inline int dname_external(struct dentry *dentry) | |
215 | { | |
216 | return dentry->d_name.name != dentry->d_iname; | |
217 | } | |
218 | ||
219 | /* | |
220 | * These are the low-level FS interfaces to the dcache.. | |
221 | */ | |
222 | extern void d_instantiate(struct dentry *, struct inode *); | |
223 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); | |
770bfad8 | 224 | extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); |
1da177e4 LT |
225 | extern void d_delete(struct dentry *); |
226 | ||
227 | /* allocate/de-allocate */ | |
228 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); | |
229 | extern struct dentry * d_alloc_anon(struct inode *); | |
230 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); | |
231 | extern void shrink_dcache_sb(struct super_block *); | |
232 | extern void shrink_dcache_parent(struct dentry *); | |
c636ebdb | 233 | extern void shrink_dcache_for_umount(struct super_block *); |
1da177e4 LT |
234 | extern int d_invalidate(struct dentry *); |
235 | ||
236 | /* only used at mount-time */ | |
237 | extern struct dentry * d_alloc_root(struct inode *); | |
238 | ||
239 | /* <clickety>-<click> the ramfs-type tree */ | |
240 | extern void d_genocide(struct dentry *); | |
241 | ||
242 | extern struct dentry *d_find_alias(struct inode *); | |
243 | extern void d_prune_aliases(struct inode *); | |
244 | ||
245 | /* test whether we have any submounts in a subdir tree */ | |
246 | extern int have_submounts(struct dentry *); | |
247 | ||
248 | /* | |
249 | * This adds the entry to the hash queues. | |
250 | */ | |
251 | extern void d_rehash(struct dentry *); | |
252 | ||
253 | /** | |
254 | * d_add - add dentry to hash queues | |
255 | * @entry: dentry to add | |
256 | * @inode: The inode to attach to this dentry | |
257 | * | |
258 | * This adds the entry to the hash queues and initializes @inode. | |
259 | * The entry was actually filled in earlier during d_alloc(). | |
260 | */ | |
261 | ||
262 | static inline void d_add(struct dentry *entry, struct inode *inode) | |
263 | { | |
264 | d_instantiate(entry, inode); | |
265 | d_rehash(entry); | |
266 | } | |
267 | ||
268 | /** | |
269 | * d_add_unique - add dentry to hash queues without aliasing | |
270 | * @entry: dentry to add | |
271 | * @inode: The inode to attach to this dentry | |
272 | * | |
273 | * This adds the entry to the hash queues and initializes @inode. | |
274 | * The entry was actually filled in earlier during d_alloc(). | |
275 | */ | |
276 | static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) | |
277 | { | |
278 | struct dentry *res; | |
279 | ||
280 | res = d_instantiate_unique(entry, inode); | |
281 | d_rehash(res != NULL ? res : entry); | |
282 | return res; | |
283 | } | |
284 | ||
285 | /* used for rename() and baskets */ | |
286 | extern void d_move(struct dentry *, struct dentry *); | |
287 | ||
288 | /* appendix may either be NULL or be used for transname suffixes */ | |
289 | extern struct dentry * d_lookup(struct dentry *, struct qstr *); | |
290 | extern struct dentry * __d_lookup(struct dentry *, struct qstr *); | |
3e7e241f | 291 | extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *); |
1da177e4 LT |
292 | |
293 | /* validate "insecure" dentry pointer */ | |
294 | extern int d_validate(struct dentry *, struct dentry *); | |
295 | ||
296 | extern char * d_path(struct dentry *, struct vfsmount *, char *, int); | |
297 | ||
298 | /* Allocation counts.. */ | |
299 | ||
300 | /** | |
301 | * dget, dget_locked - get a reference to a dentry | |
302 | * @dentry: dentry to get a reference to | |
303 | * | |
304 | * Given a dentry or %NULL pointer increment the reference count | |
305 | * if appropriate and return the dentry. A dentry will not be | |
306 | * destroyed when it has references. dget() should never be | |
307 | * called for dentries with zero reference counter. For these cases | |
308 | * (preferably none, functions in dcache.c are sufficient for normal | |
309 | * needs and they take necessary precautions) you should hold dcache_lock | |
310 | * and call dget_locked() instead of dget(). | |
311 | */ | |
312 | ||
313 | static inline struct dentry *dget(struct dentry *dentry) | |
314 | { | |
315 | if (dentry) { | |
316 | BUG_ON(!atomic_read(&dentry->d_count)); | |
317 | atomic_inc(&dentry->d_count); | |
318 | } | |
319 | return dentry; | |
320 | } | |
321 | ||
322 | extern struct dentry * dget_locked(struct dentry *); | |
323 | ||
324 | /** | |
325 | * d_unhashed - is dentry hashed | |
326 | * @dentry: entry to check | |
327 | * | |
328 | * Returns true if the dentry passed is not currently hashed. | |
329 | */ | |
330 | ||
331 | static inline int d_unhashed(struct dentry *dentry) | |
332 | { | |
333 | return (dentry->d_flags & DCACHE_UNHASHED); | |
334 | } | |
335 | ||
336 | static inline struct dentry *dget_parent(struct dentry *dentry) | |
337 | { | |
338 | struct dentry *ret; | |
339 | ||
340 | spin_lock(&dentry->d_lock); | |
341 | ret = dget(dentry->d_parent); | |
342 | spin_unlock(&dentry->d_lock); | |
343 | return ret; | |
344 | } | |
345 | ||
346 | extern void dput(struct dentry *); | |
347 | ||
348 | static inline int d_mountpoint(struct dentry *dentry) | |
349 | { | |
350 | return dentry->d_mounted; | |
351 | } | |
352 | ||
353 | extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *); | |
a05964f3 | 354 | extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int); |
1da177e4 LT |
355 | extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); |
356 | ||
357 | extern int sysctl_vfs_cache_pressure; | |
358 | ||
359 | #endif /* __KERNEL__ */ | |
360 | ||
361 | #endif /* __LINUX_DCACHE_H */ |