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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011
12struct nameidata;
13struct vfsmount;
14
15/*
16 * linux/include/linux/dcache.h
17 *
18 * Dirent cache data structures
19 *
20 * (C) Copyright 1997 Thomas Schoebel-Theuer,
21 * with heavy changes by Linus Torvalds
22 */
23
24#define IS_ROOT(x) ((x) == (x)->d_parent)
25
26/*
27 * "quick string" -- eases parameter passing, but more importantly
28 * saves "metadata" about the string (ie length and the hash).
29 *
30 * hash comes first so it snuggles against d_parent in the
31 * dentry.
32 */
33struct qstr {
34 unsigned int hash;
35 unsigned int len;
36 const unsigned char *name;
37};
38
39struct dentry_stat_t {
40 int nr_dentry;
41 int nr_unused;
42 int age_limit; /* age in seconds */
43 int want_pages; /* pages requested by system */
44 int dummy[2];
45};
46extern struct dentry_stat_t dentry_stat;
47
48/* Name hashing routines. Initial hash value */
49/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
50#define init_name_hash() 0
51
52/* partial hash update function. Assume roughly 4 bits per character */
53static inline unsigned long
54partial_name_hash(unsigned long c, unsigned long prevhash)
55{
56 return (prevhash + (c << 4) + (c >> 4)) * 11;
57}
58
59/*
60 * Finally: cut down the number of bits to a int value (and try to avoid
61 * losing bits)
62 */
63static inline unsigned long end_name_hash(unsigned long hash)
64{
65 return (unsigned int) hash;
66}
67
68/* Compute the hash for a name string. */
69static inline unsigned int
70full_name_hash(const unsigned char *name, unsigned int len)
71{
72 unsigned long hash = init_name_hash();
73 while (len--)
74 hash = partial_name_hash(*name++, hash);
75 return end_name_hash(hash);
76}
77
78struct dcookie_struct;
79
80#define DNAME_INLINE_LEN_MIN 36
81
82struct dentry {
83 atomic_t d_count;
84 unsigned int d_flags; /* protected by d_lock */
85 spinlock_t d_lock; /* per dentry lock */
86 struct inode *d_inode; /* Where the name belongs to - NULL is
87 * negative */
88 /*
89 * The next three fields are touched by __d_lookup. Place them here
Eric Dumazet3f4bb1f2005-09-06 15:18:16 -070090 * so they all fit in a cache line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 */
Eric Dumazet3f4bb1f2005-09-06 15:18:16 -070092 struct hlist_node d_hash; /* lookup hash list */
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 struct dentry *d_parent; /* parent directory */
94 struct qstr d_name;
95
96 struct list_head d_lru; /* LRU list */
Eric Dumazet5160ee62006-01-08 01:03:32 -080097 /*
98 * d_child and d_rcu can share memory
99 */
100 union {
101 struct list_head d_child; /* child of parent list */
102 struct rcu_head d_rcu;
103 } d_u;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 struct list_head d_subdirs; /* our children */
105 struct list_head d_alias; /* inode alias list */
106 unsigned long d_time; /* used by d_revalidate */
107 struct dentry_operations *d_op;
108 struct super_block *d_sb; /* The root of the dentry tree */
109 void *d_fsdata; /* fs-specific data */
Marcelo Tosatti47ba87e2006-02-03 03:04:06 -0800110#ifdef CONFIG_PROFILING
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 struct dcookie_struct *d_cookie; /* cookie, if any */
Marcelo Tosatti47ba87e2006-02-03 03:04:06 -0800112#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 int d_mounted;
114 unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
115};
116
Ingo Molnara90b9c02006-07-03 00:25:04 -0700117/*
118 * dentry->d_lock spinlock nesting subclasses:
119 *
120 * 0: normal
121 * 1: nested
122 */
123enum dentry_d_lock_class
124{
125 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
126 DENTRY_D_LOCK_NESTED
127};
128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129struct dentry_operations {
130 int (*d_revalidate)(struct dentry *, struct nameidata *);
131 int (*d_hash) (struct dentry *, struct qstr *);
132 int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
133 int (*d_delete)(struct dentry *);
134 void (*d_release)(struct dentry *);
135 void (*d_iput)(struct dentry *, struct inode *);
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700136 char *(*d_dname)(struct dentry *, char *, int);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137};
138
139/* the dentry parameter passed to d_hash and d_compare is the parent
140 * directory of the entries to be compared. It is used in case these
141 * functions need any directory specific information for determining
142 * equivalency classes. Using the dentry itself might not work, as it
143 * might be a negative dentry which has no information associated with
144 * it */
145
146/*
147locking rules:
148 big lock dcache_lock d_lock may block
149d_revalidate: no no no yes
150d_hash no no no yes
151d_compare: no yes yes no
152d_delete: no yes no no
153d_release: no no no yes
154d_iput: no no no yes
155 */
156
157/* d_flags entries */
158#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
159#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
160 * renamed" and has to be
161 * deleted on the last dput()
162 */
163#define DCACHE_DISCONNECTED 0x0004
164 /* This dentry is possibly not currently connected to the dcache tree,
165 * in which case its parent will either be itself, or will have this
166 * flag as well. nfsd will not use a dentry with this bit set, but will
167 * first endeavour to clear the bit either by discovering that it is
168 * connected, or by performing lookup operations. Any filesystem which
169 * supports nfsd_operations MUST have a lookup function which, if it finds
170 * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
171 * that dentry into place and return that dentry rather than the passed one,
172 * typically using d_splice_alias.
173 */
174
175#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
176#define DCACHE_UNHASHED 0x0010
177
Nick Pigginc32ccd82006-03-25 03:07:09 -0800178#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */
179
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180extern spinlock_t dcache_lock;
Al Viro74c3cbe2007-07-22 08:04:18 -0400181extern seqlock_t rename_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182
183/**
184 * d_drop - drop a dentry
185 * @dentry: dentry to drop
186 *
187 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
188 * be found through a VFS lookup any more. Note that this is different from
189 * deleting the dentry - d_delete will try to mark the dentry negative if
190 * possible, giving a successful _negative_ lookup, while d_drop will
191 * just make the cache lookup fail.
192 *
193 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
194 * reason (NFS timeouts or autofs deletes).
195 *
196 * __d_drop requires dentry->d_lock.
197 */
198
199static inline void __d_drop(struct dentry *dentry)
200{
201 if (!(dentry->d_flags & DCACHE_UNHASHED)) {
202 dentry->d_flags |= DCACHE_UNHASHED;
203 hlist_del_rcu(&dentry->d_hash);
204 }
205}
206
207static inline void d_drop(struct dentry *dentry)
208{
209 spin_lock(&dcache_lock);
210 spin_lock(&dentry->d_lock);
211 __d_drop(dentry);
212 spin_unlock(&dentry->d_lock);
213 spin_unlock(&dcache_lock);
214}
215
216static inline int dname_external(struct dentry *dentry)
217{
218 return dentry->d_name.name != dentry->d_iname;
219}
220
221/*
222 * These are the low-level FS interfaces to the dcache..
223 */
224extern void d_instantiate(struct dentry *, struct inode *);
225extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
David Howells770bfad2006-08-22 20:06:07 -0400226extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227extern void d_delete(struct dentry *);
228
229/* allocate/de-allocate */
230extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
231extern struct dentry * d_alloc_anon(struct inode *);
232extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
233extern void shrink_dcache_sb(struct super_block *);
234extern void shrink_dcache_parent(struct dentry *);
David Howellsc636ebd2006-10-11 01:22:19 -0700235extern void shrink_dcache_for_umount(struct super_block *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236extern int d_invalidate(struct dentry *);
237
238/* only used at mount-time */
239extern struct dentry * d_alloc_root(struct inode *);
240
241/* <clickety>-<click> the ramfs-type tree */
242extern void d_genocide(struct dentry *);
243
244extern struct dentry *d_find_alias(struct inode *);
245extern void d_prune_aliases(struct inode *);
246
247/* test whether we have any submounts in a subdir tree */
248extern int have_submounts(struct dentry *);
249
250/*
251 * This adds the entry to the hash queues.
252 */
253extern void d_rehash(struct dentry *);
254
255/**
256 * d_add - add dentry to hash queues
257 * @entry: dentry to add
258 * @inode: The inode to attach to this dentry
259 *
260 * This adds the entry to the hash queues and initializes @inode.
261 * The entry was actually filled in earlier during d_alloc().
262 */
263
264static inline void d_add(struct dentry *entry, struct inode *inode)
265{
266 d_instantiate(entry, inode);
267 d_rehash(entry);
268}
269
270/**
271 * d_add_unique - add dentry to hash queues without aliasing
272 * @entry: dentry to add
273 * @inode: The inode to attach to this dentry
274 *
275 * This adds the entry to the hash queues and initializes @inode.
276 * The entry was actually filled in earlier during d_alloc().
277 */
278static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
279{
280 struct dentry *res;
281
282 res = d_instantiate_unique(entry, inode);
283 d_rehash(res != NULL ? res : entry);
284 return res;
285}
286
287/* used for rename() and baskets */
288extern void d_move(struct dentry *, struct dentry *);
289
290/* appendix may either be NULL or be used for transname suffixes */
291extern struct dentry * d_lookup(struct dentry *, struct qstr *);
292extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
Eric W. Biederman3e7e2412006-03-31 02:31:43 -0800293extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
295/* validate "insecure" dentry pointer */
296extern int d_validate(struct dentry *, struct dentry *);
297
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700298/*
299 * helper function for dentry_operations.d_dname() members
300 */
301extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
302
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303extern char * d_path(struct dentry *, struct vfsmount *, char *, int);
304
305/* Allocation counts.. */
306
307/**
308 * dget, dget_locked - get a reference to a dentry
309 * @dentry: dentry to get a reference to
310 *
311 * Given a dentry or %NULL pointer increment the reference count
312 * if appropriate and return the dentry. A dentry will not be
313 * destroyed when it has references. dget() should never be
314 * called for dentries with zero reference counter. For these cases
315 * (preferably none, functions in dcache.c are sufficient for normal
316 * needs and they take necessary precautions) you should hold dcache_lock
317 * and call dget_locked() instead of dget().
318 */
319
320static inline struct dentry *dget(struct dentry *dentry)
321{
322 if (dentry) {
323 BUG_ON(!atomic_read(&dentry->d_count));
324 atomic_inc(&dentry->d_count);
325 }
326 return dentry;
327}
328
329extern struct dentry * dget_locked(struct dentry *);
330
331/**
332 * d_unhashed - is dentry hashed
333 * @dentry: entry to check
334 *
335 * Returns true if the dentry passed is not currently hashed.
336 */
337
338static inline int d_unhashed(struct dentry *dentry)
339{
340 return (dentry->d_flags & DCACHE_UNHASHED);
341}
342
343static inline struct dentry *dget_parent(struct dentry *dentry)
344{
345 struct dentry *ret;
346
347 spin_lock(&dentry->d_lock);
348 ret = dget(dentry->d_parent);
349 spin_unlock(&dentry->d_lock);
350 return ret;
351}
352
353extern void dput(struct dentry *);
354
355static inline int d_mountpoint(struct dentry *dentry)
356{
357 return dentry->d_mounted;
358}
359
360extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
Ram Paia05964f2005-11-07 17:20:17 -0500361extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
363
364extern int sysctl_vfs_cache_pressure;
365
366#endif /* __KERNEL__ */
367
368#endif /* __LINUX_DCACHE_H */