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