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1 | #ifndef __LINUX_DCACHE_H |
2 | #define __LINUX_DCACHE_H |
3 | |
4 | #include <linux/atomic.h> |
5 | #include <linux/list.h> |
6 | #include <linux/rculist.h> |
7 | #include <linux/rculist_bl.h> |
8 | #include <linux/spinlock.h> |
9 | #include <linux/seqlock.h> |
10 | #include <linux/cache.h> |
11 | #include <linux/rcupdate.h> |
12 | #include <linux/lockref.h> |
13 | |
14 | struct nameidata; |
15 | struct path; |
16 | struct vfsmount; |
17 | |
18 | /* |
19 | * linux/include/linux/dcache.h |
20 | * |
21 | * Dirent cache data structures |
22 | * |
23 | * (C) Copyright 1997 Thomas Schoebel-Theuer, |
24 | * with heavy changes by Linus Torvalds |
25 | */ |
26 | |
27 | #define IS_ROOT(x) ((x) == (x)->d_parent) |
28 | |
29 | /* The hash is always the low bits of hash_len */ |
30 | #ifdef __LITTLE_ENDIAN |
31 | #define HASH_LEN_DECLARE u32 hash; u32 len; |
32 | #else |
33 | #define HASH_LEN_DECLARE u32 len; u32 hash; |
34 | #endif |
35 | |
36 | /* |
37 | * "quick string" -- eases parameter passing, but more importantly |
38 | * saves "metadata" about the string (ie length and the hash). |
39 | * |
40 | * hash comes first so it snuggles against d_parent in the |
41 | * dentry. |
42 | */ |
43 | struct qstr { |
44 | union { |
45 | struct { |
46 | HASH_LEN_DECLARE; |
47 | }; |
48 | u64 hash_len; |
49 | }; |
50 | const unsigned char *name; |
51 | }; |
52 | |
53 | #define QSTR_INIT(n,l) { { { .len = l } }, .name = n } |
54 | #define hashlen_hash(hashlen) ((u32) (hashlen)) |
55 | #define hashlen_len(hashlen) ((u32)((hashlen) >> 32)) |
56 | |
57 | struct dentry_stat_t { |
58 | int nr_dentry; |
59 | int nr_unused; |
60 | int age_limit; /* age in seconds */ |
61 | int want_pages; /* pages requested by system */ |
62 | int dummy[2]; |
63 | }; |
64 | extern struct dentry_stat_t dentry_stat; |
65 | |
66 | /* Name hashing routines. Initial hash value */ |
67 | /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ |
68 | #define init_name_hash() 0 |
69 | |
70 | /* partial hash update function. Assume roughly 4 bits per character */ |
71 | static inline unsigned long |
72 | partial_name_hash(unsigned long c, unsigned long prevhash) |
73 | { |
74 | return (prevhash + (c << 4) + (c >> 4)) * 11; |
75 | } |
76 | |
77 | /* |
78 | * Finally: cut down the number of bits to a int value (and try to avoid |
79 | * losing bits) |
80 | */ |
81 | static inline unsigned long end_name_hash(unsigned long hash) |
82 | { |
83 | return (unsigned int) hash; |
84 | } |
85 | |
86 | /* Compute the hash for a name string. */ |
87 | extern unsigned int full_name_hash(const unsigned char *, unsigned int); |
88 | |
89 | /* |
90 | * Try to keep struct dentry aligned on 64 byte cachelines (this will |
91 | * give reasonable cacheline footprint with larger lines without the |
92 | * large memory footprint increase). |
93 | */ |
94 | #ifdef CONFIG_64BIT |
95 | # define DNAME_INLINE_LEN 32 /* 192 bytes */ |
96 | #else |
97 | # ifdef CONFIG_SMP |
98 | # define DNAME_INLINE_LEN 36 /* 128 bytes */ |
99 | # else |
100 | # define DNAME_INLINE_LEN 40 /* 128 bytes */ |
101 | # endif |
102 | #endif |
103 | |
104 | #define d_lock d_lockref.lock |
105 | |
106 | struct dentry { |
107 | /* RCU lookup touched fields */ |
108 | unsigned int d_flags; /* protected by d_lock */ |
109 | seqcount_t d_seq; /* per dentry seqlock */ |
110 | struct hlist_bl_node d_hash; /* lookup hash list */ |
111 | struct dentry *d_parent; /* parent directory */ |
112 | struct qstr d_name; |
113 | struct inode *d_inode; /* Where the name belongs to - NULL is |
114 | * negative */ |
115 | unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ |
116 | |
117 | /* Ref lookup also touches following */ |
118 | struct lockref d_lockref; /* per-dentry lock and refcount */ |
119 | const struct dentry_operations *d_op; |
120 | struct super_block *d_sb; /* The root of the dentry tree */ |
121 | unsigned long d_time; /* used by d_revalidate */ |
122 | void *d_fsdata; /* fs-specific data */ |
123 | |
124 | struct list_head d_lru; /* LRU list */ |
125 | /* |
126 | * d_child and d_rcu can share memory |
127 | */ |
128 | union { |
129 | struct list_head d_child; /* child of parent list */ |
130 | struct rcu_head d_rcu; |
131 | } d_u; |
132 | struct list_head d_subdirs; /* our children */ |
133 | struct hlist_node d_alias; /* inode alias list */ |
134 | }; |
135 | |
136 | /* |
137 | * dentry->d_lock spinlock nesting subclasses: |
138 | * |
139 | * 0: normal |
140 | * 1: nested |
141 | */ |
142 | enum dentry_d_lock_class |
143 | { |
144 | DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ |
145 | DENTRY_D_LOCK_NESTED |
146 | }; |
147 | |
148 | struct dentry_operations { |
149 | int (*d_revalidate)(struct dentry *, unsigned int); |
150 | int (*d_weak_revalidate)(struct dentry *, unsigned int); |
151 | int (*d_hash)(const struct dentry *, struct qstr *); |
152 | int (*d_compare)(const struct dentry *, const struct dentry *, |
153 | unsigned int, const char *, const struct qstr *); |
154 | int (*d_delete)(const struct dentry *); |
155 | void (*d_release)(struct dentry *); |
156 | void (*d_prune)(struct dentry *); |
157 | void (*d_iput)(struct dentry *, struct inode *); |
158 | char *(*d_dname)(struct dentry *, char *, int); |
159 | struct vfsmount *(*d_automount)(struct path *); |
160 | int (*d_manage)(struct dentry *, bool); |
161 | } ____cacheline_aligned; |
162 | |
163 | /* |
164 | * Locking rules for dentry_operations callbacks are to be found in |
165 | * Documentation/filesystems/Locking. Keep it updated! |
166 | * |
167 | * FUrther descriptions are found in Documentation/filesystems/vfs.txt. |
168 | * Keep it updated too! |
169 | */ |
170 | |
171 | /* d_flags entries */ |
172 | #define DCACHE_OP_HASH 0x0001 |
173 | #define DCACHE_OP_COMPARE 0x0002 |
174 | #define DCACHE_OP_REVALIDATE 0x0004 |
175 | #define DCACHE_OP_DELETE 0x0008 |
176 | #define DCACHE_OP_PRUNE 0x0010 |
177 | |
178 | #define DCACHE_DISCONNECTED 0x0020 |
179 | /* This dentry is possibly not currently connected to the dcache tree, in |
180 | * which case its parent will either be itself, or will have this flag as |
181 | * well. nfsd will not use a dentry with this bit set, but will first |
182 | * endeavour to clear the bit either by discovering that it is connected, |
183 | * or by performing lookup operations. Any filesystem which supports |
184 | * nfsd_operations MUST have a lookup function which, if it finds a |
185 | * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that |
186 | * dentry into place and return that dentry rather than the passed one, |
187 | * typically using d_splice_alias. */ |
188 | |
189 | #define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */ |
190 | #define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */ |
191 | |
192 | #define DCACHE_CANT_MOUNT 0x0100 |
193 | #define DCACHE_GENOCIDE 0x0200 |
194 | #define DCACHE_SHRINK_LIST 0x0400 |
195 | |
196 | #define DCACHE_OP_WEAK_REVALIDATE 0x0800 |
197 | |
198 | #define DCACHE_NFSFS_RENAMED 0x1000 |
199 | /* this dentry has been "silly renamed" and has to be deleted on the last |
200 | * dput() */ |
201 | #define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */ |
202 | #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000 |
203 | /* Parent inode is watched by some fsnotify listener */ |
204 | |
205 | #define DCACHE_MOUNTED 0x10000 /* is a mountpoint */ |
206 | #define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */ |
207 | #define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */ |
208 | #define DCACHE_MANAGED_DENTRY \ |
209 | (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) |
210 | |
211 | #define DCACHE_DENTRY_KILLED 0x100000 |
212 | |
213 | extern seqlock_t rename_lock; |
214 | |
215 | static inline int dname_external(struct dentry *dentry) |
216 | { |
217 | return dentry->d_name.name != dentry->d_iname; |
218 | } |
219 | |
220 | /* |
221 | * These are the low-level FS interfaces to the dcache.. |
222 | */ |
223 | extern void d_instantiate(struct dentry *, struct inode *); |
224 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); |
225 | extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); |
226 | extern void __d_drop(struct dentry *dentry); |
227 | extern void d_drop(struct dentry *dentry); |
228 | extern void d_delete(struct dentry *); |
229 | extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); |
230 | |
231 | /* allocate/de-allocate */ |
232 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); |
233 | extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *); |
234 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); |
235 | extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); |
236 | extern struct dentry *d_find_any_alias(struct inode *inode); |
237 | extern struct dentry * d_obtain_alias(struct inode *); |
238 | extern void shrink_dcache_sb(struct super_block *); |
239 | extern void shrink_dcache_parent(struct dentry *); |
240 | extern void shrink_dcache_for_umount(struct super_block *); |
241 | extern int d_invalidate(struct dentry *); |
242 | |
243 | /* only used at mount-time */ |
244 | extern struct dentry * d_make_root(struct inode *); |
245 | |
246 | /* <clickety>-<click> the ramfs-type tree */ |
247 | extern void d_genocide(struct dentry *); |
248 | |
249 | extern void d_tmpfile(struct dentry *, struct inode *); |
250 | |
251 | extern struct dentry *d_find_alias(struct inode *); |
252 | extern void d_prune_aliases(struct inode *); |
253 | |
254 | /* test whether we have any submounts in a subdir tree */ |
255 | extern int have_submounts(struct dentry *); |
256 | |
257 | /* |
258 | * This adds the entry to the hash queues. |
259 | */ |
260 | extern void d_rehash(struct dentry *); |
261 | |
262 | /** |
263 | * d_add - add dentry to hash queues |
264 | * @entry: dentry to add |
265 | * @inode: The inode to attach to this dentry |
266 | * |
267 | * This adds the entry to the hash queues and initializes @inode. |
268 | * The entry was actually filled in earlier during d_alloc(). |
269 | */ |
270 | |
271 | static inline void d_add(struct dentry *entry, struct inode *inode) |
272 | { |
273 | d_instantiate(entry, inode); |
274 | d_rehash(entry); |
275 | } |
276 | |
277 | /** |
278 | * d_add_unique - add dentry to hash queues without aliasing |
279 | * @entry: dentry to add |
280 | * @inode: The inode to attach to this dentry |
281 | * |
282 | * This adds the entry to the hash queues and initializes @inode. |
283 | * The entry was actually filled in earlier during d_alloc(). |
284 | */ |
285 | static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) |
286 | { |
287 | struct dentry *res; |
288 | |
289 | res = d_instantiate_unique(entry, inode); |
290 | d_rehash(res != NULL ? res : entry); |
291 | return res; |
292 | } |
293 | |
294 | extern void dentry_update_name_case(struct dentry *, struct qstr *); |
295 | |
296 | /* used for rename() and baskets */ |
297 | extern void d_move(struct dentry *, struct dentry *); |
298 | extern struct dentry *d_ancestor(struct dentry *, struct dentry *); |
299 | |
300 | /* appendix may either be NULL or be used for transname suffixes */ |
301 | extern struct dentry *d_lookup(const struct dentry *, const struct qstr *); |
302 | extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); |
303 | extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *); |
304 | extern struct dentry *__d_lookup_rcu(const struct dentry *parent, |
305 | const struct qstr *name, unsigned *seq); |
306 | |
307 | /** |
308 | * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok |
309 | * @dentry: dentry to take a ref on |
310 | * @seq: seqcount to verify against |
311 | * Returns: 0 on failure, else 1. |
312 | * |
313 | * __d_rcu_to_refcount operates on a dentry,seq pair that was returned |
314 | * by __d_lookup_rcu, to get a reference on an rcu-walk dentry. |
315 | */ |
316 | static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq) |
317 | { |
318 | int ret = 0; |
319 | |
320 | assert_spin_locked(&dentry->d_lock); |
321 | if (!read_seqcount_retry(&dentry->d_seq, seq)) { |
322 | ret = 1; |
323 | dentry->d_lockref.count++; |
324 | } |
325 | |
326 | return ret; |
327 | } |
328 | |
329 | static inline unsigned d_count(const struct dentry *dentry) |
330 | { |
331 | return dentry->d_lockref.count; |
332 | } |
333 | |
334 | /* validate "insecure" dentry pointer */ |
335 | extern int d_validate(struct dentry *, struct dentry *); |
336 | |
337 | /* |
338 | * helper function for dentry_operations.d_dname() members |
339 | */ |
340 | extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); |
341 | extern char *simple_dname(struct dentry *, char *, int); |
342 | |
343 | extern char *__d_path(const struct path *, const struct path *, char *, int); |
344 | extern char *d_absolute_path(const struct path *, char *, int); |
345 | extern char *d_path(const struct path *, char *, int); |
346 | extern char *dentry_path_raw(struct dentry *, char *, int); |
347 | extern char *dentry_path(struct dentry *, char *, int); |
348 | |
349 | /* Allocation counts.. */ |
350 | |
351 | /** |
352 | * dget, dget_dlock - get a reference to a dentry |
353 | * @dentry: dentry to get a reference to |
354 | * |
355 | * Given a dentry or %NULL pointer increment the reference count |
356 | * if appropriate and return the dentry. A dentry will not be |
357 | * destroyed when it has references. |
358 | */ |
359 | static inline struct dentry *dget_dlock(struct dentry *dentry) |
360 | { |
361 | if (dentry) |
362 | dentry->d_lockref.count++; |
363 | return dentry; |
364 | } |
365 | |
366 | static inline struct dentry *dget(struct dentry *dentry) |
367 | { |
368 | if (dentry) |
369 | lockref_get(&dentry->d_lockref); |
370 | return dentry; |
371 | } |
372 | |
373 | extern struct dentry *dget_parent(struct dentry *dentry); |
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 | { |
384 | return hlist_bl_unhashed(&dentry->d_hash); |
385 | } |
386 | |
387 | static inline int d_unlinked(struct dentry *dentry) |
388 | { |
389 | return d_unhashed(dentry) && !IS_ROOT(dentry); |
390 | } |
391 | |
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 | |
404 | extern void dput(struct dentry *); |
405 | |
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) |
412 | { |
413 | return dentry->d_flags & DCACHE_MOUNTED; |
414 | } |
415 | |
416 | extern int sysctl_vfs_cache_pressure; |
417 | |
418 | #endif /* __LINUX_DCACHE_H */ |
419 |
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