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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __LINUX_DCACHE_H
2#define __LINUX_DCACHE_H
3
Arun Sharma600634972011-07-26 16:09:06 -07004#include <linux/atomic.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07005#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 */
Linus Torvalds830c0f02011-08-06 22:41:50 -0700183#define DCACHE_OP_HASH 0x0001
184#define DCACHE_OP_COMPARE 0x0002
185#define DCACHE_OP_REVALIDATE 0x0004
186#define DCACHE_OP_DELETE 0x0008
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100187
Linus Torvalds830c0f02011-08-06 22:41:50 -0700188#define DCACHE_DISCONNECTED 0x0010
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100189 /* 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
Linus Torvalds830c0f02011-08-06 22:41:50 -0700199#define DCACHE_REFERENCED 0x0020 /* Recently used, don't discard. */
200#define DCACHE_RCUACCESS 0x0040 /* Entry has ever been RCU-visible */
Eric Parisc28f7e52009-05-21 17:01:29 -0400201
Al Virod83c49f2010-04-30 17:17:09 -0400202#define DCACHE_CANT_MOUNT 0x0100
Nick Piggin949854d2011-01-07 17:49:37 +1100203#define DCACHE_GENOCIDE 0x0200
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100204
Linus Torvalds830c0f02011-08-06 22:41:50 -0700205#define DCACHE_NFSFS_RENAMED 0x1000
206 /* this dentry has been "silly renamed" and has to be deleted on the last
207 * dput() */
208#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
209#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
210 /* Parent inode is watched by some fsnotify listener */
Nick Pigginfb045ad2011-01-07 17:49:55 +1100211
David Howells9875cf82011-01-14 18:45:21 +0000212#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
213#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
David Howellscc53ce52011-01-14 18:45:26 +0000214#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
Josef Bacik44396f42011-05-31 11:58:49 -0400215#define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */
David Howells9875cf82011-01-14 18:45:21 +0000216#define DCACHE_MANAGED_DENTRY \
David Howellscc53ce52011-01-14 18:45:26 +0000217 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
David Howells9875cf82011-01-14 18:45:21 +0000218
Al Viro74c3cbe2007-07-22 08:04:18 -0400219extern seqlock_t rename_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221static inline int dname_external(struct dentry *dentry)
222{
223 return dentry->d_name.name != dentry->d_iname;
224}
225
226/*
227 * These are the low-level FS interfaces to the dcache..
228 */
229extern void d_instantiate(struct dentry *, struct inode *);
230extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
David Howells770bfad2006-08-22 20:06:07 -0400231extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
Nick Piggin789680d2011-01-07 17:49:30 +1100232extern void __d_drop(struct dentry *dentry);
233extern void d_drop(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234extern void d_delete(struct dentry *);
Nick Pigginfb045ad2011-01-07 17:49:55 +1100235extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
237/* allocate/de-allocate */
238extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
Nick Piggin4b936882011-01-07 17:50:07 +1100239extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
Christoph Hellwige45b5902008-08-07 23:49:07 +0200241extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200242extern struct dentry * d_obtain_alias(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243extern void shrink_dcache_sb(struct super_block *);
244extern void shrink_dcache_parent(struct dentry *);
David Howellsc636ebd2006-10-11 01:22:19 -0700245extern void shrink_dcache_for_umount(struct super_block *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246extern int d_invalidate(struct dentry *);
247
248/* only used at mount-time */
249extern struct dentry * d_alloc_root(struct inode *);
250
251/* <clickety>-<click> the ramfs-type tree */
252extern void d_genocide(struct dentry *);
253
254extern struct dentry *d_find_alias(struct inode *);
255extern void d_prune_aliases(struct inode *);
256
257/* test whether we have any submounts in a subdir tree */
258extern int have_submounts(struct dentry *);
259
260/*
261 * This adds the entry to the hash queues.
262 */
263extern void d_rehash(struct dentry *);
264
265/**
266 * d_add - add dentry to hash queues
267 * @entry: dentry to add
268 * @inode: The inode to attach to this dentry
269 *
270 * This adds the entry to the hash queues and initializes @inode.
271 * The entry was actually filled in earlier during d_alloc().
272 */
273
274static inline void d_add(struct dentry *entry, struct inode *inode)
275{
276 d_instantiate(entry, inode);
277 d_rehash(entry);
278}
279
280/**
281 * d_add_unique - add dentry to hash queues without aliasing
282 * @entry: dentry to add
283 * @inode: The inode to attach to this dentry
284 *
285 * This adds the entry to the hash queues and initializes @inode.
286 * The entry was actually filled in earlier during d_alloc().
287 */
288static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
289{
290 struct dentry *res;
291
292 res = d_instantiate_unique(entry, inode);
293 d_rehash(res != NULL ? res : entry);
294 return res;
295}
296
Nick Pigginfb2d5b82011-01-07 17:49:26 +1100297extern void dentry_update_name_case(struct dentry *, struct qstr *);
298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299/* used for rename() and baskets */
300extern void d_move(struct dentry *, struct dentry *);
OGAWA Hirofumie2761a12008-10-16 07:50:28 +0900301extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302
303/* appendix may either be NULL or be used for transname suffixes */
Nick Piggin31e6b012011-01-07 17:49:52 +1100304extern struct dentry *d_lookup(struct dentry *, struct qstr *);
305extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
306extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
307extern struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name,
308 unsigned *seq, struct inode **inode);
309
310/**
311 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
312 * @dentry: dentry to take a ref on
313 * @seq: seqcount to verify against
Randy Dunlap2a8c0c682011-01-08 19:37:20 -0800314 * Returns: 0 on failure, else 1.
Nick Piggin31e6b012011-01-07 17:49:52 +1100315 *
316 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
317 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
318 */
319static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
320{
321 int ret = 0;
322
323 assert_spin_locked(&dentry->d_lock);
324 if (!read_seqcount_retry(&dentry->d_seq, seq)) {
325 ret = 1;
326 dentry->d_count++;
327 }
328
329 return ret;
330}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
332/* validate "insecure" dentry pointer */
333extern int d_validate(struct dentry *, struct dentry *);
334
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700335/*
336 * helper function for dentry_operations.d_dname() members
337 */
338extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
339
Miklos Szeredi9d1bc6012008-03-27 13:06:21 +0100340extern char *__d_path(const struct path *path, struct path *root, char *, int);
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -0700341extern char *d_path(const struct path *, char *, int);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +0200342extern char *d_path_with_unreachable(const struct path *, char *, int);
Nick Pigginec2447c2011-01-07 17:49:29 +1100343extern char *dentry_path_raw(struct dentry *, char *, int);
Ram Pai6092d042008-03-27 13:06:20 +0100344extern char *dentry_path(struct dentry *, char *, int);
Jan Blunckcf28b482008-02-14 19:38:44 -0800345
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346/* Allocation counts.. */
347
348/**
Nick Piggindc0474b2011-01-07 17:49:43 +1100349 * dget, dget_dlock - get a reference to a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 * @dentry: dentry to get a reference to
351 *
352 * Given a dentry or %NULL pointer increment the reference count
353 * if appropriate and return the dentry. A dentry will not be
Nick Piggindc0474b2011-01-07 17:49:43 +1100354 * destroyed when it has references.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100356static inline struct dentry *dget_dlock(struct dentry *dentry)
357{
Nick Piggindc0474b2011-01-07 17:49:43 +1100358 if (dentry)
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100359 dentry->d_count++;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100360 return dentry;
361}
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100362
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363static inline struct dentry *dget(struct dentry *dentry)
364{
365 if (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100366 spin_lock(&dentry->d_lock);
367 dget_dlock(dentry);
368 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 }
370 return dentry;
371}
372
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100373extern struct dentry *dget_parent(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374
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
382static inline int d_unhashed(struct dentry *dentry)
383{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700384 return hlist_bl_unhashed(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385}
386
Alexey Dobriyanf3da3922009-05-04 03:32:03 +0400387static inline int d_unlinked(struct dentry *dentry)
388{
389 return d_unhashed(dentry) && !IS_ROOT(dentry);
390}
391
Al Virod83c49f2010-04-30 17:17:09 -0400392static inline int cant_mount(struct dentry *dentry)
393{
394 return (dentry->d_flags & DCACHE_CANT_MOUNT);
395}
396
397static 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404extern void dput(struct dentry *);
405
David Howellscc53ce52011-01-14 18:45:26 +0000406static inline bool d_managed(struct dentry *dentry)
407{
408 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
409}
410
411static inline bool d_mountpoint(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412{
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100413 return dentry->d_flags & DCACHE_MOUNTED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414}
415
Josef Bacik44396f42011-05-31 11:58:49 -0400416static inline bool d_need_lookup(struct dentry *dentry)
417{
418 return dentry->d_flags & DCACHE_NEED_LOOKUP;
419}
420
421extern void d_clear_need_lookup(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422
423extern int sysctl_vfs_cache_pressure;
424
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425#endif /* __LINUX_DCACHE_H */