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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __LINUX_DCACHE_H
2#define __LINUX_DCACHE_H
3
Linus Torvalds1da177e2005-04-16 15:20:36 -07004#include <asm/atomic.h>
5#include <linux/list.h>
Franck Bui-Huu82524742008-05-12 21:21:05 +02006#include <linux/rculist.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/spinlock.h>
8#include <linux/cache.h>
9#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010
11struct nameidata;
Jan Blunckcf28b482008-02-14 19:38:44 -080012struct path;
Linus Torvalds1da177e2005-04-16 15:20:36 -070013struct 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
Nick Pigginc2452f32008-12-01 09:33:43 +010078/*
79 * Try to keep struct dentry aligned on 64 byte cachelines (this will
80 * give reasonable cacheline footprint with larger lines without the
81 * large memory footprint increase).
82 */
83#ifdef CONFIG_64BIT
84#define DNAME_INLINE_LEN_MIN 32 /* 192 bytes */
85#else
86#define DNAME_INLINE_LEN_MIN 40 /* 128 bytes */
87#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89struct dentry {
90 atomic_t d_count;
91 unsigned int d_flags; /* protected by d_lock */
92 spinlock_t d_lock; /* per dentry lock */
Nick Pigginc2452f32008-12-01 09:33:43 +010093 int d_mounted;
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 struct inode *d_inode; /* Where the name belongs to - NULL is
95 * negative */
96 /*
97 * The next three fields are touched by __d_lookup. Place them here
Eric Dumazet3f4bb1f2005-09-06 15:18:16 -070098 * so they all fit in a cache line.
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 */
Eric Dumazet3f4bb1f2005-09-06 15:18:16 -0700100 struct hlist_node d_hash; /* lookup hash list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 struct dentry *d_parent; /* parent directory */
102 struct qstr d_name;
103
104 struct list_head d_lru; /* LRU list */
Eric Dumazet5160ee62006-01-08 01:03:32 -0800105 /*
106 * d_child and d_rcu can share memory
107 */
108 union {
109 struct list_head d_child; /* child of parent list */
110 struct rcu_head d_rcu;
111 } d_u;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112 struct list_head d_subdirs; /* our children */
113 struct list_head d_alias; /* inode alias list */
114 unsigned long d_time; /* used by d_revalidate */
115 struct dentry_operations *d_op;
116 struct super_block *d_sb; /* The root of the dentry tree */
117 void *d_fsdata; /* fs-specific data */
Nick Pigginc2452f32008-12-01 09:33:43 +0100118
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 unsigned char d_iname[DNAME_INLINE_LEN_MIN]; /* small names */
120};
121
Ingo Molnara90b9c02006-07-03 00:25:04 -0700122/*
123 * dentry->d_lock spinlock nesting subclasses:
124 *
125 * 0: normal
126 * 1: nested
127 */
128enum dentry_d_lock_class
129{
130 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
131 DENTRY_D_LOCK_NESTED
132};
133
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134struct dentry_operations {
135 int (*d_revalidate)(struct dentry *, struct nameidata *);
136 int (*d_hash) (struct dentry *, struct qstr *);
137 int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
138 int (*d_delete)(struct dentry *);
139 void (*d_release)(struct dentry *);
140 void (*d_iput)(struct dentry *, struct inode *);
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700141 char *(*d_dname)(struct dentry *, char *, int);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142};
143
144/* the dentry parameter passed to d_hash and d_compare is the parent
145 * directory of the entries to be compared. It is used in case these
146 * functions need any directory specific information for determining
147 * equivalency classes. Using the dentry itself might not work, as it
148 * might be a negative dentry which has no information associated with
149 * it */
150
151/*
152locking rules:
153 big lock dcache_lock d_lock may block
154d_revalidate: no no no yes
155d_hash no no no yes
156d_compare: no yes yes no
157d_delete: no yes no no
158d_release: no no no yes
159d_iput: no no no yes
160 */
161
162/* d_flags entries */
163#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
164#define DCACHE_NFSFS_RENAMED 0x0002 /* this dentry has been "silly
165 * renamed" and has to be
166 * deleted on the last dput()
167 */
168#define DCACHE_DISCONNECTED 0x0004
169 /* This dentry is possibly not currently connected to the dcache tree,
170 * in which case its parent will either be itself, or will have this
171 * flag as well. nfsd will not use a dentry with this bit set, but will
172 * first endeavour to clear the bit either by discovering that it is
173 * connected, or by performing lookup operations. Any filesystem which
174 * supports nfsd_operations MUST have a lookup function which, if it finds
175 * a directory inode with a DCACHE_DISCONNECTED dentry, will d_move
176 * that dentry into place and return that dentry rather than the passed one,
177 * typically using d_splice_alias.
178 */
179
180#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
181#define DCACHE_UNHASHED 0x0010
182
Nick Pigginc32ccd82006-03-25 03:07:09 -0800183#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */
184
Nick Pigginc2452f32008-12-01 09:33:43 +0100185#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187extern spinlock_t dcache_lock;
Al Viro74c3cbe2007-07-22 08:04:18 -0400188extern seqlock_t rename_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
190/**
191 * d_drop - drop a dentry
192 * @dentry: dentry to drop
193 *
194 * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
195 * be found through a VFS lookup any more. Note that this is different from
196 * deleting the dentry - d_delete will try to mark the dentry negative if
197 * possible, giving a successful _negative_ lookup, while d_drop will
198 * just make the cache lookup fail.
199 *
200 * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
201 * reason (NFS timeouts or autofs deletes).
202 *
203 * __d_drop requires dentry->d_lock.
204 */
205
206static inline void __d_drop(struct dentry *dentry)
207{
208 if (!(dentry->d_flags & DCACHE_UNHASHED)) {
209 dentry->d_flags |= DCACHE_UNHASHED;
210 hlist_del_rcu(&dentry->d_hash);
211 }
212}
213
214static inline void d_drop(struct dentry *dentry)
215{
216 spin_lock(&dcache_lock);
217 spin_lock(&dentry->d_lock);
218 __d_drop(dentry);
219 spin_unlock(&dentry->d_lock);
220 spin_unlock(&dcache_lock);
221}
222
223static inline int dname_external(struct dentry *dentry)
224{
225 return dentry->d_name.name != dentry->d_iname;
226}
227
228/*
229 * These are the low-level FS interfaces to the dcache..
230 */
231extern void d_instantiate(struct dentry *, struct inode *);
232extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
David Howells770bfad2006-08-22 20:06:07 -0400233extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234extern void d_delete(struct dentry *);
235
236/* allocate/de-allocate */
237extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
Christoph Hellwige45b5902008-08-07 23:49:07 +0200239extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200240extern struct dentry * d_obtain_alias(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241extern void shrink_dcache_sb(struct super_block *);
242extern void shrink_dcache_parent(struct dentry *);
David Howellsc636ebd2006-10-11 01:22:19 -0700243extern void shrink_dcache_for_umount(struct super_block *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244extern int d_invalidate(struct dentry *);
245
246/* only used at mount-time */
247extern struct dentry * d_alloc_root(struct inode *);
248
249/* <clickety>-<click> the ramfs-type tree */
250extern void d_genocide(struct dentry *);
251
252extern struct dentry *d_find_alias(struct inode *);
253extern void d_prune_aliases(struct inode *);
254
255/* test whether we have any submounts in a subdir tree */
256extern int have_submounts(struct dentry *);
257
258/*
259 * This adds the entry to the hash queues.
260 */
261extern void d_rehash(struct dentry *);
262
263/**
264 * d_add - add dentry to hash queues
265 * @entry: dentry to add
266 * @inode: The inode to attach to this dentry
267 *
268 * This adds the entry to the hash queues and initializes @inode.
269 * The entry was actually filled in earlier during d_alloc().
270 */
271
272static inline void d_add(struct dentry *entry, struct inode *inode)
273{
274 d_instantiate(entry, inode);
275 d_rehash(entry);
276}
277
278/**
279 * d_add_unique - add dentry to hash queues without aliasing
280 * @entry: dentry to add
281 * @inode: The inode to attach to this dentry
282 *
283 * This adds the entry to the hash queues and initializes @inode.
284 * The entry was actually filled in earlier during d_alloc().
285 */
286static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
287{
288 struct dentry *res;
289
290 res = d_instantiate_unique(entry, inode);
291 d_rehash(res != NULL ? res : entry);
292 return res;
293}
294
295/* used for rename() and baskets */
296extern void d_move(struct dentry *, struct dentry *);
OGAWA Hirofumie2761a12008-10-16 07:50:28 +0900297extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298
299/* appendix may either be NULL or be used for transname suffixes */
300extern struct dentry * d_lookup(struct dentry *, struct qstr *);
301extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
Eric W. Biederman3e7e2412006-03-31 02:31:43 -0800302extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
304/* validate "insecure" dentry pointer */
305extern int d_validate(struct dentry *, struct dentry *);
306
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700307/*
308 * helper function for dentry_operations.d_dname() members
309 */
310extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
311
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +0100312extern char *__d_path(const struct path *path, struct path *root, char *, int);
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -0700313extern char *d_path(const struct path *, char *, int);
Ram Pai6092d042008-03-27 13:06:20 +0100314extern char *dentry_path(struct dentry *, char *, int);
Jan Blunckcf28b482008-02-14 19:38:44 -0800315
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316/* Allocation counts.. */
317
318/**
319 * dget, dget_locked - get a reference to a dentry
320 * @dentry: dentry to get a reference to
321 *
322 * Given a dentry or %NULL pointer increment the reference count
323 * if appropriate and return the dentry. A dentry will not be
324 * destroyed when it has references. dget() should never be
325 * called for dentries with zero reference counter. For these cases
326 * (preferably none, functions in dcache.c are sufficient for normal
327 * needs and they take necessary precautions) you should hold dcache_lock
328 * and call dget_locked() instead of dget().
329 */
330
331static inline struct dentry *dget(struct dentry *dentry)
332{
333 if (dentry) {
334 BUG_ON(!atomic_read(&dentry->d_count));
335 atomic_inc(&dentry->d_count);
336 }
337 return dentry;
338}
339
340extern struct dentry * dget_locked(struct dentry *);
341
342/**
343 * d_unhashed - is dentry hashed
344 * @dentry: entry to check
345 *
346 * Returns true if the dentry passed is not currently hashed.
347 */
348
349static inline int d_unhashed(struct dentry *dentry)
350{
351 return (dentry->d_flags & DCACHE_UNHASHED);
352}
353
354static inline struct dentry *dget_parent(struct dentry *dentry)
355{
356 struct dentry *ret;
357
358 spin_lock(&dentry->d_lock);
359 ret = dget(dentry->d_parent);
360 spin_unlock(&dentry->d_lock);
361 return ret;
362}
363
364extern void dput(struct dentry *);
365
366static inline int d_mountpoint(struct dentry *dentry)
367{
368 return dentry->d_mounted;
369}
370
371extern struct vfsmount *lookup_mnt(struct vfsmount *, struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
373
374extern int sysctl_vfs_cache_pressure;
375
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376#endif /* __LINUX_DCACHE_H */