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1da177e4 LT |
1 | #ifndef __LINUX_DCACHE_H |
2 | #define __LINUX_DCACHE_H | |
3 | ||
60063497 | 4 | #include <linux/atomic.h> |
1da177e4 | 5 | #include <linux/list.h> |
82524746 | 6 | #include <linux/rculist.h> |
ceb5bdc2 | 7 | #include <linux/rculist_bl.h> |
1da177e4 | 8 | #include <linux/spinlock.h> |
31e6b01f | 9 | #include <linux/seqlock.h> |
1da177e4 LT |
10 | #include <linux/cache.h> |
11 | #include <linux/rcupdate.h> | |
1da177e4 LT |
12 | |
13 | struct nameidata; | |
cf28b486 | 14 | struct path; |
1da177e4 LT |
15 | struct vfsmount; |
16 | ||
17 | /* | |
18 | * linux/include/linux/dcache.h | |
19 | * | |
20 | * Dirent cache data structures | |
21 | * | |
22 | * (C) Copyright 1997 Thomas Schoebel-Theuer, | |
23 | * with heavy changes by Linus Torvalds | |
24 | */ | |
25 | ||
26 | #define IS_ROOT(x) ((x) == (x)->d_parent) | |
27 | ||
28 | /* | |
29 | * "quick string" -- eases parameter passing, but more importantly | |
30 | * saves "metadata" about the string (ie length and the hash). | |
31 | * | |
32 | * hash comes first so it snuggles against d_parent in the | |
33 | * dentry. | |
34 | */ | |
35 | struct qstr { | |
36 | unsigned int hash; | |
37 | unsigned int len; | |
38 | const unsigned char *name; | |
39 | }; | |
40 | ||
41 | struct dentry_stat_t { | |
42 | int nr_dentry; | |
43 | int nr_unused; | |
44 | int age_limit; /* age in seconds */ | |
45 | int want_pages; /* pages requested by system */ | |
46 | int dummy[2]; | |
47 | }; | |
48 | extern struct dentry_stat_t dentry_stat; | |
49 | ||
9d55c369 NP |
50 | /* |
51 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. | |
52 | * The strings are both count bytes long, and count is non-zero. | |
53 | */ | |
54 | static inline int dentry_cmp(const unsigned char *cs, size_t scount, | |
55 | const unsigned char *ct, size_t tcount) | |
56 | { | |
57 | int ret; | |
58 | if (scount != tcount) | |
59 | return 1; | |
60 | do { | |
61 | ret = (*cs != *ct); | |
62 | if (ret) | |
63 | break; | |
64 | cs++; | |
65 | ct++; | |
66 | tcount--; | |
67 | } while (tcount); | |
68 | return ret; | |
69 | } | |
70 | ||
1da177e4 LT |
71 | /* Name hashing routines. Initial hash value */ |
72 | /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ | |
73 | #define init_name_hash() 0 | |
74 | ||
75 | /* partial hash update function. Assume roughly 4 bits per character */ | |
76 | static inline unsigned long | |
77 | partial_name_hash(unsigned long c, unsigned long prevhash) | |
78 | { | |
79 | return (prevhash + (c << 4) + (c >> 4)) * 11; | |
80 | } | |
81 | ||
82 | /* | |
83 | * Finally: cut down the number of bits to a int value (and try to avoid | |
84 | * losing bits) | |
85 | */ | |
86 | static inline unsigned long end_name_hash(unsigned long hash) | |
87 | { | |
88 | return (unsigned int) hash; | |
89 | } | |
90 | ||
91 | /* Compute the hash for a name string. */ | |
92 | static inline unsigned int | |
93 | full_name_hash(const unsigned char *name, unsigned int len) | |
94 | { | |
95 | unsigned long hash = init_name_hash(); | |
96 | while (len--) | |
97 | hash = partial_name_hash(*name++, hash); | |
98 | return end_name_hash(hash); | |
99 | } | |
100 | ||
c2452f32 NP |
101 | /* |
102 | * Try to keep struct dentry aligned on 64 byte cachelines (this will | |
103 | * give reasonable cacheline footprint with larger lines without the | |
104 | * large memory footprint increase). | |
105 | */ | |
106 | #ifdef CONFIG_64BIT | |
44a7d7a8 | 107 | # define DNAME_INLINE_LEN 32 /* 192 bytes */ |
c2452f32 | 108 | #else |
44a7d7a8 NP |
109 | # ifdef CONFIG_SMP |
110 | # define DNAME_INLINE_LEN 36 /* 128 bytes */ | |
111 | # else | |
112 | # define DNAME_INLINE_LEN 40 /* 128 bytes */ | |
113 | # endif | |
c2452f32 | 114 | #endif |
1da177e4 LT |
115 | |
116 | struct dentry { | |
44a7d7a8 | 117 | /* RCU lookup touched fields */ |
1da177e4 | 118 | unsigned int d_flags; /* protected by d_lock */ |
31e6b01f | 119 | seqcount_t d_seq; /* per dentry seqlock */ |
ceb5bdc2 | 120 | struct hlist_bl_node d_hash; /* lookup hash list */ |
1da177e4 LT |
121 | struct dentry *d_parent; /* parent directory */ |
122 | struct qstr d_name; | |
44a7d7a8 NP |
123 | struct inode *d_inode; /* Where the name belongs to - NULL is |
124 | * negative */ | |
125 | unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ | |
126 | ||
127 | /* Ref lookup also touches following */ | |
128 | unsigned int d_count; /* protected by d_lock */ | |
129 | spinlock_t d_lock; /* per dentry lock */ | |
130 | const struct dentry_operations *d_op; | |
131 | struct super_block *d_sb; /* The root of the dentry tree */ | |
132 | unsigned long d_time; /* used by d_revalidate */ | |
133 | void *d_fsdata; /* fs-specific data */ | |
1da177e4 LT |
134 | |
135 | struct list_head d_lru; /* LRU list */ | |
5160ee6f ED |
136 | /* |
137 | * d_child and d_rcu can share memory | |
138 | */ | |
139 | union { | |
140 | struct list_head d_child; /* child of parent list */ | |
141 | struct rcu_head d_rcu; | |
142 | } d_u; | |
1da177e4 LT |
143 | struct list_head d_subdirs; /* our children */ |
144 | struct list_head d_alias; /* inode alias list */ | |
1da177e4 LT |
145 | }; |
146 | ||
a90b9c05 IM |
147 | /* |
148 | * dentry->d_lock spinlock nesting subclasses: | |
149 | * | |
150 | * 0: normal | |
151 | * 1: nested | |
152 | */ | |
153 | enum dentry_d_lock_class | |
154 | { | |
155 | DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ | |
156 | DENTRY_D_LOCK_NESTED | |
157 | }; | |
158 | ||
1da177e4 LT |
159 | struct dentry_operations { |
160 | int (*d_revalidate)(struct dentry *, struct nameidata *); | |
b1e6a015 NP |
161 | int (*d_hash)(const struct dentry *, const struct inode *, |
162 | struct qstr *); | |
621e155a NP |
163 | int (*d_compare)(const struct dentry *, const struct inode *, |
164 | const struct dentry *, const struct inode *, | |
165 | unsigned int, const char *, const struct qstr *); | |
fe15ce44 | 166 | int (*d_delete)(const struct dentry *); |
1da177e4 LT |
167 | void (*d_release)(struct dentry *); |
168 | void (*d_iput)(struct dentry *, struct inode *); | |
c23fbb6b | 169 | char *(*d_dname)(struct dentry *, char *, int); |
9875cf80 | 170 | struct vfsmount *(*d_automount)(struct path *); |
1aed3e42 | 171 | int (*d_manage)(struct dentry *, bool); |
44a7d7a8 | 172 | } ____cacheline_aligned; |
1da177e4 | 173 | |
5eef7fa9 NP |
174 | /* |
175 | * Locking rules for dentry_operations callbacks are to be found in | |
176 | * Documentation/filesystems/Locking. Keep it updated! | |
177 | * | |
621e155a NP |
178 | * FUrther descriptions are found in Documentation/filesystems/vfs.txt. |
179 | * Keep it updated too! | |
1da177e4 LT |
180 | */ |
181 | ||
182 | /* d_flags entries */ | |
830c0f0e LT |
183 | #define DCACHE_OP_HASH 0x0001 |
184 | #define DCACHE_OP_COMPARE 0x0002 | |
185 | #define DCACHE_OP_REVALIDATE 0x0004 | |
186 | #define DCACHE_OP_DELETE 0x0008 | |
5f57cbcc | 187 | |
830c0f0e | 188 | #define DCACHE_DISCONNECTED 0x0010 |
5f57cbcc NP |
189 | /* This dentry is possibly not currently connected to the dcache tree, in |
190 | * which case its parent will either be itself, or will have this flag as | |
191 | * well. nfsd will not use a dentry with this bit set, but will first | |
192 | * endeavour to clear the bit either by discovering that it is connected, | |
193 | * or by performing lookup operations. Any filesystem which supports | |
194 | * nfsd_operations MUST have a lookup function which, if it finds a | |
195 | * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that | |
196 | * dentry into place and return that dentry rather than the passed one, | |
197 | * typically using d_splice_alias. */ | |
1da177e4 | 198 | |
830c0f0e LT |
199 | #define DCACHE_REFERENCED 0x0020 /* Recently used, don't discard. */ |
200 | #define DCACHE_RCUACCESS 0x0040 /* Entry has ever been RCU-visible */ | |
c28f7e56 | 201 | |
d83c49f3 | 202 | #define DCACHE_CANT_MOUNT 0x0100 |
949854d0 | 203 | #define DCACHE_GENOCIDE 0x0200 |
5f57cbcc | 204 | |
830c0f0e LT |
205 | #define DCACHE_NFSFS_RENAMED 0x1000 |
206 | /* this dentry has been "silly renamed" and has to be deleted on the last | |
207 | * dput() */ | |
208 | #define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */ | |
209 | #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000 | |
210 | /* Parent inode is watched by some fsnotify listener */ | |
fb045adb | 211 | |
9875cf80 DH |
212 | #define DCACHE_MOUNTED 0x10000 /* is a mountpoint */ |
213 | #define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */ | |
cc53ce53 | 214 | #define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */ |
44396f4b | 215 | #define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */ |
9875cf80 | 216 | #define DCACHE_MANAGED_DENTRY \ |
cc53ce53 | 217 | (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) |
9875cf80 | 218 | |
74c3cbe3 | 219 | extern seqlock_t rename_lock; |
1da177e4 | 220 | |
1da177e4 LT |
221 | static inline int dname_external(struct dentry *dentry) |
222 | { | |
223 | return dentry->d_name.name != dentry->d_iname; | |
224 | } | |
225 | ||
226 | /* | |
227 | * These are the low-level FS interfaces to the dcache.. | |
228 | */ | |
229 | extern void d_instantiate(struct dentry *, struct inode *); | |
230 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); | |
770bfad8 | 231 | extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); |
789680d1 NP |
232 | extern void __d_drop(struct dentry *dentry); |
233 | extern void d_drop(struct dentry *dentry); | |
1da177e4 | 234 | extern void d_delete(struct dentry *); |
fb045adb | 235 | extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); |
1da177e4 LT |
236 | |
237 | /* allocate/de-allocate */ | |
238 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); | |
4b936885 | 239 | extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *); |
1da177e4 | 240 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); |
e45b590b | 241 | extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); |
4ea3ada2 | 242 | extern struct dentry * d_obtain_alias(struct inode *); |
1da177e4 LT |
243 | extern void shrink_dcache_sb(struct super_block *); |
244 | extern void shrink_dcache_parent(struct dentry *); | |
c636ebdb | 245 | extern void shrink_dcache_for_umount(struct super_block *); |
1da177e4 LT |
246 | extern int d_invalidate(struct dentry *); |
247 | ||
248 | /* only used at mount-time */ | |
249 | extern struct dentry * d_alloc_root(struct inode *); | |
250 | ||
251 | /* <clickety>-<click> the ramfs-type tree */ | |
252 | extern void d_genocide(struct dentry *); | |
253 | ||
254 | extern struct dentry *d_find_alias(struct inode *); | |
255 | extern void d_prune_aliases(struct inode *); | |
256 | ||
257 | /* test whether we have any submounts in a subdir tree */ | |
258 | extern int have_submounts(struct dentry *); | |
259 | ||
260 | /* | |
261 | * This adds the entry to the hash queues. | |
262 | */ | |
263 | extern void d_rehash(struct dentry *); | |
264 | ||
265 | /** | |
266 | * d_add - add dentry to hash queues | |
267 | * @entry: dentry to add | |
268 | * @inode: The inode to attach to this dentry | |
269 | * | |
270 | * This adds the entry to the hash queues and initializes @inode. | |
271 | * The entry was actually filled in earlier during d_alloc(). | |
272 | */ | |
273 | ||
274 | static inline void d_add(struct dentry *entry, struct inode *inode) | |
275 | { | |
276 | d_instantiate(entry, inode); | |
277 | d_rehash(entry); | |
278 | } | |
279 | ||
280 | /** | |
281 | * d_add_unique - add dentry to hash queues without aliasing | |
282 | * @entry: dentry to add | |
283 | * @inode: The inode to attach to this dentry | |
284 | * | |
285 | * This adds the entry to the hash queues and initializes @inode. | |
286 | * The entry was actually filled in earlier during d_alloc(). | |
287 | */ | |
288 | static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) | |
289 | { | |
290 | struct dentry *res; | |
291 | ||
292 | res = d_instantiate_unique(entry, inode); | |
293 | d_rehash(res != NULL ? res : entry); | |
294 | return res; | |
295 | } | |
296 | ||
fb2d5b86 NP |
297 | extern void dentry_update_name_case(struct dentry *, struct qstr *); |
298 | ||
1da177e4 LT |
299 | /* used for rename() and baskets */ |
300 | extern void d_move(struct dentry *, struct dentry *); | |
e2761a11 | 301 | extern struct dentry *d_ancestor(struct dentry *, struct dentry *); |
1da177e4 LT |
302 | |
303 | /* appendix may either be NULL or be used for transname suffixes */ | |
31e6b01f NP |
304 | extern struct dentry *d_lookup(struct dentry *, struct qstr *); |
305 | extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); | |
306 | extern struct dentry *__d_lookup(struct dentry *, struct qstr *); | |
307 | extern struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, | |
308 | unsigned *seq, struct inode **inode); | |
309 | ||
310 | /** | |
311 | * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok | |
312 | * @dentry: dentry to take a ref on | |
313 | * @seq: seqcount to verify against | |
2a8c0c68 | 314 | * Returns: 0 on failure, else 1. |
31e6b01f NP |
315 | * |
316 | * __d_rcu_to_refcount operates on a dentry,seq pair that was returned | |
317 | * by __d_lookup_rcu, to get a reference on an rcu-walk dentry. | |
318 | */ | |
319 | static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq) | |
320 | { | |
321 | int ret = 0; | |
322 | ||
323 | assert_spin_locked(&dentry->d_lock); | |
324 | if (!read_seqcount_retry(&dentry->d_seq, seq)) { | |
325 | ret = 1; | |
326 | dentry->d_count++; | |
327 | } | |
328 | ||
329 | return ret; | |
330 | } | |
1da177e4 LT |
331 | |
332 | /* validate "insecure" dentry pointer */ | |
333 | extern int d_validate(struct dentry *, struct dentry *); | |
334 | ||
c23fbb6b ED |
335 | /* |
336 | * helper function for dentry_operations.d_dname() members | |
337 | */ | |
338 | extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); | |
339 | ||
9d1bc601 | 340 | extern char *__d_path(const struct path *path, struct path *root, char *, int); |
20d4fdc1 | 341 | extern char *d_path(const struct path *, char *, int); |
8df9d1a4 | 342 | extern char *d_path_with_unreachable(const struct path *, char *, int); |
ec2447c2 | 343 | extern char *dentry_path_raw(struct dentry *, char *, int); |
6092d048 | 344 | extern char *dentry_path(struct dentry *, char *, int); |
cf28b486 | 345 | |
1da177e4 LT |
346 | /* Allocation counts.. */ |
347 | ||
348 | /** | |
dc0474be | 349 | * dget, dget_dlock - get a reference to a dentry |
1da177e4 LT |
350 | * @dentry: dentry to get a reference to |
351 | * | |
352 | * Given a dentry or %NULL pointer increment the reference count | |
353 | * if appropriate and return the dentry. A dentry will not be | |
dc0474be | 354 | * destroyed when it has references. |
1da177e4 | 355 | */ |
b7ab39f6 NP |
356 | static inline struct dentry *dget_dlock(struct dentry *dentry) |
357 | { | |
dc0474be | 358 | if (dentry) |
b7ab39f6 | 359 | dentry->d_count++; |
b7ab39f6 NP |
360 | return dentry; |
361 | } | |
2fd6b7f5 | 362 | |
1da177e4 LT |
363 | static inline struct dentry *dget(struct dentry *dentry) |
364 | { | |
365 | if (dentry) { | |
b7ab39f6 NP |
366 | spin_lock(&dentry->d_lock); |
367 | dget_dlock(dentry); | |
368 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
369 | } |
370 | return dentry; | |
371 | } | |
372 | ||
b7ab39f6 | 373 | extern struct dentry *dget_parent(struct dentry *dentry); |
1da177e4 LT |
374 | |
375 | /** | |
376 | * d_unhashed - is dentry hashed | |
377 | * @dentry: entry to check | |
378 | * | |
379 | * Returns true if the dentry passed is not currently hashed. | |
380 | */ | |
381 | ||
382 | static inline int d_unhashed(struct dentry *dentry) | |
383 | { | |
dea3667b | 384 | return hlist_bl_unhashed(&dentry->d_hash); |
1da177e4 LT |
385 | } |
386 | ||
f3da392e AD |
387 | static inline int d_unlinked(struct dentry *dentry) |
388 | { | |
389 | return d_unhashed(dentry) && !IS_ROOT(dentry); | |
390 | } | |
391 | ||
d83c49f3 AV |
392 | static inline int cant_mount(struct dentry *dentry) |
393 | { | |
394 | return (dentry->d_flags & DCACHE_CANT_MOUNT); | |
395 | } | |
396 | ||
397 | static inline void dont_mount(struct dentry *dentry) | |
398 | { | |
399 | spin_lock(&dentry->d_lock); | |
400 | dentry->d_flags |= DCACHE_CANT_MOUNT; | |
401 | spin_unlock(&dentry->d_lock); | |
402 | } | |
403 | ||
1da177e4 LT |
404 | extern void dput(struct dentry *); |
405 | ||
cc53ce53 DH |
406 | static inline bool d_managed(struct dentry *dentry) |
407 | { | |
408 | return dentry->d_flags & DCACHE_MANAGED_DENTRY; | |
409 | } | |
410 | ||
411 | static inline bool d_mountpoint(struct dentry *dentry) | |
1da177e4 | 412 | { |
5f57cbcc | 413 | return dentry->d_flags & DCACHE_MOUNTED; |
1da177e4 LT |
414 | } |
415 | ||
44396f4b JB |
416 | static inline bool d_need_lookup(struct dentry *dentry) |
417 | { | |
418 | return dentry->d_flags & DCACHE_NEED_LOOKUP; | |
419 | } | |
420 | ||
421 | extern void d_clear_need_lookup(struct dentry *dentry); | |
1da177e4 LT |
422 | |
423 | extern int sysctl_vfs_cache_pressure; | |
424 | ||
1da177e4 | 425 | #endif /* __LINUX_DCACHE_H */ |