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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 static inline unsigned d_count(const struct dentry *dentry)
308 {
309 return dentry->d_lockref.count;
310 }
311
312 /* validate "insecure" dentry pointer */
313 extern int d_validate(struct dentry *, struct dentry *);
314
315 /*
316 * helper function for dentry_operations.d_dname() members
317 */
318 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
319 extern char *simple_dname(struct dentry *, char *, int);
320
321 extern char *__d_path(const struct path *, const struct path *, char *, int);
322 extern char *d_absolute_path(const struct path *, char *, int);
323 extern char *d_path(const struct path *, char *, int);
324 extern char *dentry_path_raw(struct dentry *, char *, int);
325 extern char *dentry_path(struct dentry *, char *, int);
326
327 /* Allocation counts.. */
328
329 /**
330 * dget, dget_dlock - get a reference to a dentry
331 * @dentry: dentry to get a reference to
332 *
333 * Given a dentry or %NULL pointer increment the reference count
334 * if appropriate and return the dentry. A dentry will not be
335 * destroyed when it has references.
336 */
337 static inline struct dentry *dget_dlock(struct dentry *dentry)
338 {
339 if (dentry)
340 dentry->d_lockref.count++;
341 return dentry;
342 }
343
344 static inline struct dentry *dget(struct dentry *dentry)
345 {
346 if (dentry)
347 lockref_get(&dentry->d_lockref);
348 return dentry;
349 }
350
351 extern struct dentry *dget_parent(struct dentry *dentry);
352
353 /**
354 * d_unhashed - is dentry hashed
355 * @dentry: entry to check
356 *
357 * Returns true if the dentry passed is not currently hashed.
358 */
359
360 static inline int d_unhashed(struct dentry *dentry)
361 {
362 return hlist_bl_unhashed(&dentry->d_hash);
363 }
364
365 static inline int d_unlinked(struct dentry *dentry)
366 {
367 return d_unhashed(dentry) && !IS_ROOT(dentry);
368 }
369
370 static inline int cant_mount(struct dentry *dentry)
371 {
372 return (dentry->d_flags & DCACHE_CANT_MOUNT);
373 }
374
375 static inline void dont_mount(struct dentry *dentry)
376 {
377 spin_lock(&dentry->d_lock);
378 dentry->d_flags |= DCACHE_CANT_MOUNT;
379 spin_unlock(&dentry->d_lock);
380 }
381
382 extern void dput(struct dentry *);
383
384 static inline bool d_managed(struct dentry *dentry)
385 {
386 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
387 }
388
389 static inline bool d_mountpoint(struct dentry *dentry)
390 {
391 return dentry->d_flags & DCACHE_MOUNTED;
392 }
393
394 extern int sysctl_vfs_cache_pressure;
395
396 #endif /* __LINUX_DCACHE_H */