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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>
Nick Pigginceb5bdc2011-01-07 17:50:05 +11007#include <linux/rculist_bl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#include <linux/spinlock.h>
Nick Piggin31e6b012011-01-07 17:49:52 +11009#include <linux/seqlock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/cache.h>
11#include <linux/rcupdate.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012
13struct nameidata;
Jan Blunckcf28b482008-02-14 19:38:44 -080014struct path;
Linus Torvalds1da177e2005-04-16 15:20:36 -070015struct 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 */
35struct qstr {
36 unsigned int hash;
37 unsigned int len;
38 const unsigned char *name;
39};
40
41struct 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};
48extern struct dentry_stat_t dentry_stat;
49
Nick Piggin9d55c362011-01-07 17:50:09 +110050/*
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 */
54static 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070071/* 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 */
76static inline unsigned long
77partial_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 */
86static 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. */
92static inline unsigned int
93full_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
Nick Pigginc2452f32008-12-01 09:33:43 +0100101/*
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
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100107# define DNAME_INLINE_LEN 32 /* 192 bytes */
Nick Pigginc2452f32008-12-01 09:33:43 +0100108#else
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100109# ifdef CONFIG_SMP
110# define DNAME_INLINE_LEN 36 /* 128 bytes */
111# else
112# define DNAME_INLINE_LEN 40 /* 128 bytes */
113# endif
Nick Pigginc2452f32008-12-01 09:33:43 +0100114#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116struct dentry {
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100117 /* RCU lookup touched fields */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 unsigned int d_flags; /* protected by d_lock */
Nick Piggin31e6b012011-01-07 17:49:52 +1100119 seqcount_t d_seq; /* per dentry seqlock */
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100120 struct hlist_bl_node d_hash; /* lookup hash list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 struct dentry *d_parent; /* parent directory */
122 struct qstr d_name;
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100123 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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
135 struct list_head d_lru; /* LRU list */
Eric Dumazet5160ee62006-01-08 01:03:32 -0800136 /*
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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 struct list_head d_subdirs; /* our children */
144 struct list_head d_alias; /* inode alias list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145};
146
Ingo Molnara90b9c02006-07-03 00:25:04 -0700147/*
148 * dentry->d_lock spinlock nesting subclasses:
149 *
150 * 0: normal
151 * 1: nested
152 */
153enum dentry_d_lock_class
154{
155 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
156 DENTRY_D_LOCK_NESTED
157};
158
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159struct dentry_operations {
160 int (*d_revalidate)(struct dentry *, struct nameidata *);
Nick Pigginb1e6a012011-01-07 17:49:28 +1100161 int (*d_hash)(const struct dentry *, const struct inode *,
162 struct qstr *);
Nick Piggin621e1552011-01-07 17:49:27 +1100163 int (*d_compare)(const struct dentry *, const struct inode *,
164 const struct dentry *, const struct inode *,
165 unsigned int, const char *, const struct qstr *);
Nick Pigginfe15ce42011-01-07 17:49:23 +1100166 int (*d_delete)(const struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 void (*d_release)(struct dentry *);
168 void (*d_iput)(struct dentry *, struct inode *);
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700169 char *(*d_dname)(struct dentry *, char *, int);
David Howells9875cf82011-01-14 18:45:21 +0000170 struct vfsmount *(*d_automount)(struct path *);
Al Viro1aed3e42011-03-18 09:09:02 -0400171 int (*d_manage)(struct dentry *, bool);
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100172} ____cacheline_aligned;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173
Nick Piggin5eef7fa2011-01-07 17:49:22 +1100174/*
175 * Locking rules for dentry_operations callbacks are to be found in
176 * Documentation/filesystems/Locking. Keep it updated!
177 *
Nick Piggin621e1552011-01-07 17:49:27 +1100178 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
179 * Keep it updated too!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 */
181
182/* d_flags entries */
183#define DCACHE_AUTOFS_PENDING 0x0001 /* autofs: "under construction" */
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100184#define DCACHE_NFSFS_RENAMED 0x0002
185 /* this dentry has been "silly renamed" and has to be deleted on the last
186 * dput() */
187
188#define DCACHE_DISCONNECTED 0x0004
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. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
199#define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */
Linus Torvaldsdea36672011-04-24 07:58:46 -0700200#define DCACHE_RCUACCESS 0x0010 /* Entry has ever been RCU-visible */
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100201#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020
202 /* Parent inode is watched by inotify */
Nick Pigginc32ccd82006-03-25 03:07:09 -0800203
Nick Pigginc2452f32008-12-01 09:33:43 +0100204#define DCACHE_COOKIE 0x0040 /* For use by dcookie subsystem */
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100205#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x0080
206 /* Parent inode is watched by some fsnotify listener */
Eric Parisc28f7e52009-05-21 17:01:29 -0400207
Al Virod83c49f2010-04-30 17:17:09 -0400208#define DCACHE_CANT_MOUNT 0x0100
Nick Piggin949854d2011-01-07 17:49:37 +1100209#define DCACHE_GENOCIDE 0x0200
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100210
Nick Pigginfb045ad2011-01-07 17:49:55 +1100211#define DCACHE_OP_HASH 0x1000
212#define DCACHE_OP_COMPARE 0x2000
213#define DCACHE_OP_REVALIDATE 0x4000
214#define DCACHE_OP_DELETE 0x8000
215
David Howells9875cf82011-01-14 18:45:21 +0000216#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
217#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
David Howellscc53ce52011-01-14 18:45:26 +0000218#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
David Howells9875cf82011-01-14 18:45:21 +0000219#define DCACHE_MANAGED_DENTRY \
David Howellscc53ce52011-01-14 18:45:26 +0000220 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
David Howells9875cf82011-01-14 18:45:21 +0000221
Al Viro74c3cbe2007-07-22 08:04:18 -0400222extern seqlock_t rename_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224static inline int dname_external(struct dentry *dentry)
225{
226 return dentry->d_name.name != dentry->d_iname;
227}
228
229/*
230 * These are the low-level FS interfaces to the dcache..
231 */
232extern void d_instantiate(struct dentry *, struct inode *);
233extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
David Howells770bfad2006-08-22 20:06:07 -0400234extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
Nick Piggin789680d2011-01-07 17:49:30 +1100235extern void __d_drop(struct dentry *dentry);
236extern void d_drop(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237extern void d_delete(struct dentry *);
Nick Pigginfb045ad2011-01-07 17:49:55 +1100238extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
240/* allocate/de-allocate */
241extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
Nick Piggin4b936882011-01-07 17:50:07 +1100242extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
Christoph Hellwige45b5902008-08-07 23:49:07 +0200244extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200245extern struct dentry * d_obtain_alias(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246extern void shrink_dcache_sb(struct super_block *);
247extern void shrink_dcache_parent(struct dentry *);
David Howellsc636ebd2006-10-11 01:22:19 -0700248extern void shrink_dcache_for_umount(struct super_block *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249extern int d_invalidate(struct dentry *);
250
251/* only used at mount-time */
252extern struct dentry * d_alloc_root(struct inode *);
253
254/* <clickety>-<click> the ramfs-type tree */
255extern void d_genocide(struct dentry *);
256
257extern struct dentry *d_find_alias(struct inode *);
258extern void d_prune_aliases(struct inode *);
259
260/* test whether we have any submounts in a subdir tree */
261extern int have_submounts(struct dentry *);
262
263/*
264 * This adds the entry to the hash queues.
265 */
266extern void d_rehash(struct dentry *);
267
268/**
269 * d_add - add dentry to hash queues
270 * @entry: dentry to add
271 * @inode: The inode to attach to this dentry
272 *
273 * This adds the entry to the hash queues and initializes @inode.
274 * The entry was actually filled in earlier during d_alloc().
275 */
276
277static inline void d_add(struct dentry *entry, struct inode *inode)
278{
279 d_instantiate(entry, inode);
280 d_rehash(entry);
281}
282
283/**
284 * d_add_unique - add dentry to hash queues without aliasing
285 * @entry: dentry to add
286 * @inode: The inode to attach to this dentry
287 *
288 * This adds the entry to the hash queues and initializes @inode.
289 * The entry was actually filled in earlier during d_alloc().
290 */
291static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
292{
293 struct dentry *res;
294
295 res = d_instantiate_unique(entry, inode);
296 d_rehash(res != NULL ? res : entry);
297 return res;
298}
299
Nick Pigginfb2d5b82011-01-07 17:49:26 +1100300extern void dentry_update_name_case(struct dentry *, struct qstr *);
301
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302/* used for rename() and baskets */
303extern void d_move(struct dentry *, struct dentry *);
OGAWA Hirofumie2761a12008-10-16 07:50:28 +0900304extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306/* appendix may either be NULL or be used for transname suffixes */
Nick Piggin31e6b012011-01-07 17:49:52 +1100307extern struct dentry *d_lookup(struct dentry *, struct qstr *);
308extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
309extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
310extern struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
311 unsigned *seq, struct inode **inode);
312
313/**
314 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
315 * @dentry: dentry to take a ref on
316 * @seq: seqcount to verify against
Randy Dunlap2a8c0c62011-01-08 19:37:20 -0800317 * Returns: 0 on failure, else 1.
Nick Piggin31e6b012011-01-07 17:49:52 +1100318 *
319 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
320 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
321 */
322static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
323{
324 int ret = 0;
325
326 assert_spin_locked(&dentry->d_lock);
327 if (!read_seqcount_retry(&dentry->d_seq, seq)) {
328 ret = 1;
329 dentry->d_count++;
330 }
331
332 return ret;
333}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334
335/* validate "insecure" dentry pointer */
336extern int d_validate(struct dentry *, struct dentry *);
337
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700338/*
339 * helper function for dentry_operations.d_dname() members
340 */
341extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
342
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +0100343extern char *__d_path(const struct path *path, struct path *root, char *, int);
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -0700344extern char *d_path(const struct path *, char *, int);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +0200345extern char *d_path_with_unreachable(const struct path *, char *, int);
Nick Pigginec2447c2011-01-07 17:49:29 +1100346extern char *dentry_path_raw(struct dentry *, char *, int);
Ram Pai6092d042008-03-27 13:06:20 +0100347extern char *dentry_path(struct dentry *, char *, int);
Jan Blunckcf28b482008-02-14 19:38:44 -0800348
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349/* Allocation counts.. */
350
351/**
Nick Piggindc0474b2011-01-07 17:49:43 +1100352 * dget, dget_dlock - get a reference to a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 * @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
Nick Piggindc0474b2011-01-07 17:49:43 +1100357 * destroyed when it has references.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100359static inline struct dentry *dget_dlock(struct dentry *dentry)
360{
Nick Piggindc0474b2011-01-07 17:49:43 +1100361 if (dentry)
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100362 dentry->d_count++;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100363 return dentry;
364}
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100365
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366static inline struct dentry *dget(struct dentry *dentry)
367{
368 if (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100369 spin_lock(&dentry->d_lock);
370 dget_dlock(dentry);
371 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 }
373 return dentry;
374}
375
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100376extern struct dentry *dget_parent(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377
378/**
379 * d_unhashed - is dentry hashed
380 * @dentry: entry to check
381 *
382 * Returns true if the dentry passed is not currently hashed.
383 */
384
385static inline int d_unhashed(struct dentry *dentry)
386{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700387 return hlist_bl_unhashed(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388}
389
Alexey Dobriyanf3da3922009-05-04 03:32:03 +0400390static inline int d_unlinked(struct dentry *dentry)
391{
392 return d_unhashed(dentry) && !IS_ROOT(dentry);
393}
394
Al Virod83c49f2010-04-30 17:17:09 -0400395static inline int cant_mount(struct dentry *dentry)
396{
397 return (dentry->d_flags & DCACHE_CANT_MOUNT);
398}
399
400static inline void dont_mount(struct dentry *dentry)
401{
402 spin_lock(&dentry->d_lock);
403 dentry->d_flags |= DCACHE_CANT_MOUNT;
404 spin_unlock(&dentry->d_lock);
405}
406
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407extern void dput(struct dentry *);
408
David Howellscc53ce52011-01-14 18:45:26 +0000409static inline bool d_managed(struct dentry *dentry)
410{
411 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
412}
413
414static inline bool d_mountpoint(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415{
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100416 return dentry->d_flags & DCACHE_MOUNTED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417}
418
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419extern struct dentry *lookup_create(struct nameidata *nd, int is_dir);
420
421extern int sysctl_vfs_cache_pressure;
422
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423#endif /* __LINUX_DCACHE_H */