diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/linux/dcache.h |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/linux/dcache.h')
-rw-r--r-- | include/linux/dcache.h | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h new file mode 100644 index 000000000000..50be290d24d2 --- /dev/null +++ b/include/linux/dcache.h | |||
@@ -0,0 +1,338 @@ | |||
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 | ||
91 | * so they all fit in a 16-byte range, with 16-byte alignment. | ||
92 | */ | ||
93 | struct dentry *d_parent; /* parent directory */ | ||
94 | struct qstr d_name; | ||
95 | |||
96 | struct list_head d_lru; /* LRU list */ | ||
97 | struct list_head d_child; /* child of parent list */ | ||
98 | struct list_head d_subdirs; /* our children */ | ||
99 | struct list_head d_alias; /* inode alias list */ | ||
100 | unsigned long d_time; /* used by d_revalidate */ | ||
101 | struct dentry_operations *d_op; | ||
102 | struct super_block *d_sb; /* The root of the dentry tree */ | ||
103 | void *d_fsdata; /* fs-specific data */ | ||
104 | struct rcu_head d_rcu; | ||
105 | struct dcookie_struct *d_cookie; /* cookie, if any */ | ||
106 | struct hlist_node d_hash; /* lookup hash list */ | ||
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 */ | ||