]>
Commit | Line | Data |
---|---|---|
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> | |
11 | #include <asm/bug.h> | |
12 | ||
13 | struct nameidata; | |
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 */ | |
98 | struct list_head d_child; /* child of parent list */ | |
99 | struct list_head d_subdirs; /* our children */ | |
100 | struct list_head d_alias; /* inode alias list */ | |
101 | unsigned long d_time; /* used by d_revalidate */ | |
102 | struct dentry_operations *d_op; | |
103 | struct super_block *d_sb; /* The root of the dentry tree */ | |
104 | void *d_fsdata; /* fs-specific data */ | |
105 | struct rcu_head d_rcu; | |
106 | struct dcookie_struct *d_cookie; /* cookie, if any */ | |
1da177e4 LT |
107 | int d_mounted; |
108 | unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */ | |
109 | }; | |
110 | ||
111 | struct dentry_operations { | |
112 | int (*d_revalidate)(struct dentry *, struct nameidata *); | |
113 | int (*d_hash) (struct dentry *, struct qstr *); | |
114 | int (*d_compare) (struct dentry *, struct qstr *, struct qstr *); | |
115 | int (*d_delete)(struct dentry *); | |
116 | void (*d_release)(struct dentry *); | |
117 | void (*d_iput)(struct dentry *, struct inode *); | |
118 | }; | |
119 | ||
120 | /* the dentry parameter passed to d_hash and d_compare is the parent | |
121 | * directory of the entries to be compared. It is used in case these | |
122 | * functions need any directory specific information for determining | |
123 | * equivalency classes. Using the dentry itself might not work, as it | |
124 | * might be a negative dentry which has no information associated with | |
125 | * it */ | |
126 | ||
127 | /* | |
128 | locking rules: | |
129 | big lock dcache_lock d_lock may block | |
130 | d_revalidate: no no no yes | |
131 | d_hash no no no yes | |
132 | d_compare: no yes yes no | |
133 | d_delete: no yes no no | |
134 | d_release: no no no yes | |
135 | d_iput: no no no yes | |
136 | */ | |
137 | ||
138 | /* d_flags entries */ | |
139 | #define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */ | |
140 | #define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly | |
141 | * renamed" and has to be | |
142 | * deleted on the last dput() | |
143 | */ | |
144 | #define DCACHE_DISCONNECTED 0x0004 | |
145 | /* This dentry is possibly not currently connected to the dcache tree, | |
146 | * in which case its parent will either be itself, or will have this | |
147 | * flag as well. nfsd will not use a dentry with this bit set, but will | |
148 | * first endeavour to clear the bit either by discovering that it is | |
149 | * connected, or by performing lookup operations. Any filesystem which | |
150 | * supports nfsd_operations MUST have a lookup function which, if it finds | |
151 | * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move | |
152 | * that dentry into place and return that dentry rather than the passed one, | |
153 | * typically using d_splice_alias. | |
154 | */ | |
155 | ||
156 | #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ | |
157 | #define DCACHE_UNHASHED 0x0010 | |
158 | ||
159 | extern spinlock_t dcache_lock; | |
160 | ||
161 | /** | |
162 | * d_drop - drop a dentry | |
163 | * @dentry: dentry to drop | |
164 | * | |
165 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
166 | * be found through a VFS lookup any more. Note that this is different from | |
167 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
168 | * possible, giving a successful _negative_ lookup, while d_drop will | |
169 | * just make the cache lookup fail. | |
170 | * | |
171 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
172 | * reason (NFS timeouts or autofs deletes). | |
173 | * | |
174 | * __d_drop requires dentry->d_lock. | |
175 | */ | |
176 | ||
177 | static inline void __d_drop(struct dentry *dentry) | |
178 | { | |
179 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { | |
180 | dentry->d_flags |= DCACHE_UNHASHED; | |
181 | hlist_del_rcu(&dentry->d_hash); | |
182 | } | |
183 | } | |
184 | ||
185 | static inline void d_drop(struct dentry *dentry) | |
186 | { | |
187 | spin_lock(&dcache_lock); | |
188 | spin_lock(&dentry->d_lock); | |
189 | __d_drop(dentry); | |
190 | spin_unlock(&dentry->d_lock); | |
191 | spin_unlock(&dcache_lock); | |
192 | } | |
193 | ||
194 | static inline int dname_external(struct dentry *dentry) | |
195 | { | |
196 | return dentry->d_name.name != dentry->d_iname; | |
197 | } | |
198 | ||
199 | /* | |
200 | * These are the low-level FS interfaces to the dcache.. | |
201 | */ | |
202 | extern void d_instantiate(struct dentry *, struct inode *); | |
203 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); | |
204 | extern void d_delete(struct dentry *); | |
205 | ||
206 | /* allocate/de-allocate */ | |
207 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); | |
208 | extern struct dentry * d_alloc_anon(struct inode *); | |
209 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); | |
210 | extern void shrink_dcache_sb(struct super_block *); | |
211 | extern void shrink_dcache_parent(struct dentry *); | |
212 | extern void shrink_dcache_anon(struct hlist_head *); | |
213 | extern int d_invalidate(struct dentry *); | |
214 | ||
215 | /* only used at mount-time */ | |
216 | extern struct dentry * d_alloc_root(struct inode *); | |
217 | ||
218 | /* <clickety>-<click> the ramfs-type tree */ | |
219 | extern void d_genocide(struct dentry *); | |
220 | ||
221 | extern struct dentry *d_find_alias(struct inode *); | |
222 | extern void d_prune_aliases(struct inode *); | |
223 | ||
224 | /* test whether we have any submounts in a subdir tree */ | |
225 | extern int have_submounts(struct dentry *); | |
226 | ||
227 | /* | |
228 | * This adds the entry to the hash queues. | |
229 | */ | |
230 | extern void d_rehash(struct dentry *); | |
231 | ||
232 | /** | |
233 | * d_add - add dentry to hash queues | |
234 | * @entry: dentry to add | |
235 | * @inode: The inode to attach to this dentry | |
236 | * | |
237 | * This adds the entry to the hash queues and initializes @inode. | |
238 | * The entry was actually filled in earlier during d_alloc(). | |
239 | */ | |
240 | ||
241 | static inline void d_add(struct dentry *entry, struct inode *inode) | |
242 | { | |
243 | d_instantiate(entry, inode); | |
244 | d_rehash(entry); | |
245 | } | |
246 | ||
247 | /** | |
248 | * d_add_unique - add dentry to hash queues without aliasing | |
249 | * @entry: dentry to add | |
250 | * @inode: The inode to attach to this dentry | |
251 | * | |
252 | * This adds the entry to the hash queues and initializes @inode. | |
253 | * The entry was actually filled in earlier during d_alloc(). | |
254 | */ | |
255 | static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) | |
256 | { | |
257 | struct dentry *res; | |
258 | ||
259 | res = d_instantiate_unique(entry, inode); | |
260 | d_rehash(res != NULL ? res : entry); | |
261 | return res; | |
262 | } | |
263 | ||
264 | /* used for rename() and baskets */ | |
265 | extern void d_move(struct dentry *, struct dentry *); | |
266 | ||
267 | /* appendix may either be NULL or be used for transname suffixes */ | |
268 | extern struct dentry * d_lookup(struct dentry *, struct qstr *); | |
269 | extern struct dentry * __d_lookup(struct dentry *, struct qstr *); | |
270 | ||
271 | /* validate "insecure" dentry pointer */ | |
272 | extern int d_validate(struct dentry *, struct dentry *); | |
273 | ||
274 | extern char * d_path(struct dentry *, struct vfsmount *, char *, int); | |
275 | ||
276 | /* Allocation counts.. */ | |
277 | ||
278 | /** | |
279 | * dget, dget_locked - get a reference to a dentry | |
280 | * @dentry: dentry to get a reference to | |
281 | * | |
282 | * Given a dentry or %NULL pointer increment the reference count | |
283 | * if appropriate and return the dentry. A dentry will not be | |
284 | * destroyed when it has references. dget() should never be | |
285 | * called for dentries with zero reference counter. For these cases | |
286 | * (preferably none, functions in dcache.c are sufficient for normal | |
287 | * needs and they take necessary precautions) you should hold dcache_lock | |
288 | * and call dget_locked() instead of dget(). | |
289 | */ | |
290 | ||
291 | static inline struct dentry *dget(struct dentry *dentry) | |
292 | { | |
293 | if (dentry) { | |
294 | BUG_ON(!atomic_read(&dentry->d_count)); | |
295 | atomic_inc(&dentry->d_count); | |
296 | } | |
297 | return dentry; | |
298 | } | |
299 | ||
300 | extern struct dentry * dget_locked(struct dentry *); | |
301 | ||
302 | /** | |
303 | * d_unhashed - is dentry hashed | |
304 | * @dentry: entry to check | |
305 | * | |
306 | * Returns true if the dentry passed is not currently hashed. | |
307 | */ | |
308 | ||
309 | static inline int d_unhashed(struct dentry *dentry) | |
310 | { | |
311 | return (dentry->d_flags & DCACHE_UNHASHED); | |
312 | } | |
313 | ||
314 | static inline struct dentry *dget_parent(struct dentry *dentry) | |
315 | { | |
316 | struct dentry *ret; | |
317 | ||
318 | spin_lock(&dentry->d_lock); | |
319 | ret = dget(dentry->d_parent); | |
320 | spin_unlock(&dentry->d_lock); | |
321 | return ret; | |
322 | } | |
323 | ||
324 | extern void dput(struct dentry *); | |
325 | ||
326 | static inline int d_mountpoint(struct dentry *dentry) | |
327 | { | |
328 | return dentry->d_mounted; | |
329 | } | |
330 | ||
331 | extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *); | |
332 | extern struct dentry *lookup_create(struct nameidata *nd, int is_dir); | |
333 | ||
334 | extern int sysctl_vfs_cache_pressure; | |
335 | ||
336 | #endif /* __KERNEL__ */ | |
337 | ||
338 | #endif /* __LINUX_DCACHE_H */ |