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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __LINUX_DCACHE_H
2#define __LINUX_DCACHE_H
3
Arun Sharma60063492011-07-26 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
50/* Name hashing routines. Initial hash value */
51/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
52#define init_name_hash() 0
53
54/* partial hash update function. Assume roughly 4 bits per character */
55static inline unsigned long
56partial_name_hash(unsigned long c, unsigned long prevhash)
57{
58 return (prevhash + (c << 4) + (c >> 4)) * 11;
59}
60
61/*
62 * Finally: cut down the number of bits to a int value (and try to avoid
63 * losing bits)
64 */
65static inline unsigned long end_name_hash(unsigned long hash)
66{
67 return (unsigned int) hash;
68}
69
70/* Compute the hash for a name string. */
Linus Torvalds0145acc2012-03-02 14:32:59 -080071extern unsigned int full_name_hash(const unsigned char *, unsigned int);
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Nick Pigginc2452f32008-12-01 09:33:43 +010073/*
74 * Try to keep struct dentry aligned on 64 byte cachelines (this will
75 * give reasonable cacheline footprint with larger lines without the
76 * large memory footprint increase).
77 */
78#ifdef CONFIG_64BIT
Nick Piggin44a7d7a2011-01-07 17:49:56 +110079# define DNAME_INLINE_LEN 32 /* 192 bytes */
Nick Pigginc2452f32008-12-01 09:33:43 +010080#else
Nick Piggin44a7d7a2011-01-07 17:49:56 +110081# ifdef CONFIG_SMP
82# define DNAME_INLINE_LEN 36 /* 128 bytes */
83# else
84# define DNAME_INLINE_LEN 40 /* 128 bytes */
85# endif
Nick Pigginc2452f32008-12-01 09:33:43 +010086#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
88struct dentry {
Nick Piggin44a7d7a2011-01-07 17:49:56 +110089 /* RCU lookup touched fields */
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 unsigned int d_flags; /* protected by d_lock */
Nick Piggin31e6b012011-01-07 17:49:52 +110091 seqcount_t d_seq; /* per dentry seqlock */
Nick Pigginceb5bdc2011-01-07 17:50:05 +110092 struct hlist_bl_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;
Nick Piggin44a7d7a2011-01-07 17:49:56 +110095 struct inode *d_inode; /* Where the name belongs to - NULL is
96 * negative */
97 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
98
99 /* Ref lookup also touches following */
100 unsigned int d_count; /* protected by d_lock */
101 spinlock_t d_lock; /* per dentry lock */
102 const struct dentry_operations *d_op;
103 struct super_block *d_sb; /* The root of the dentry tree */
104 unsigned long d_time; /* used by d_revalidate */
105 void *d_fsdata; /* fs-specific data */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106
107 struct list_head d_lru; /* LRU list */
Eric Dumazet5160ee62006-01-08 01:03:32 -0800108 /*
109 * d_child and d_rcu can share memory
110 */
111 union {
112 struct list_head d_child; /* child of parent list */
113 struct rcu_head d_rcu;
114 } d_u;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 struct list_head d_subdirs; /* our children */
116 struct list_head d_alias; /* inode alias list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117};
118
Ingo Molnara90b9c02006-07-03 00:25:04 -0700119/*
120 * dentry->d_lock spinlock nesting subclasses:
121 *
122 * 0: normal
123 * 1: nested
124 */
125enum dentry_d_lock_class
126{
127 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
128 DENTRY_D_LOCK_NESTED
129};
130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131struct dentry_operations {
132 int (*d_revalidate)(struct dentry *, struct nameidata *);
Nick Pigginb1e6a012011-01-07 17:49:28 +1100133 int (*d_hash)(const struct dentry *, const struct inode *,
134 struct qstr *);
Nick Piggin621e1552011-01-07 17:49:27 +1100135 int (*d_compare)(const struct dentry *, const struct inode *,
136 const struct dentry *, const struct inode *,
137 unsigned int, const char *, const struct qstr *);
Nick Pigginfe15ce42011-01-07 17:49:23 +1100138 int (*d_delete)(const struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 void (*d_release)(struct dentry *);
Sage Weilf0023bc2011-10-28 10:02:42 -0700140 void (*d_prune)(struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141 void (*d_iput)(struct dentry *, struct inode *);
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700142 char *(*d_dname)(struct dentry *, char *, int);
David Howells9875cf82011-01-14 18:45:21 +0000143 struct vfsmount *(*d_automount)(struct path *);
Al Viro1aed3e42011-03-18 09:09:02 -0400144 int (*d_manage)(struct dentry *, bool);
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100145} ____cacheline_aligned;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
Nick Piggin5eef7fa2011-01-07 17:49:22 +1100147/*
148 * Locking rules for dentry_operations callbacks are to be found in
149 * Documentation/filesystems/Locking. Keep it updated!
150 *
Nick Piggin621e1552011-01-07 17:49:27 +1100151 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
152 * Keep it updated too!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153 */
154
155/* d_flags entries */
Linus Torvalds830c0f02011-08-06 22:41:50 -0700156#define DCACHE_OP_HASH 0x0001
157#define DCACHE_OP_COMPARE 0x0002
158#define DCACHE_OP_REVALIDATE 0x0004
159#define DCACHE_OP_DELETE 0x0008
Sage Weilf0023bc2011-10-28 10:02:42 -0700160#define DCACHE_OP_PRUNE 0x0010
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100161
Sage Weilf0023bc2011-10-28 10:02:42 -0700162#define DCACHE_DISCONNECTED 0x0020
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100163 /* This dentry is possibly not currently connected to the dcache tree, in
164 * which case its parent will either be itself, or will have this flag as
165 * well. nfsd will not use a dentry with this bit set, but will first
166 * endeavour to clear the bit either by discovering that it is connected,
167 * or by performing lookup operations. Any filesystem which supports
168 * nfsd_operations MUST have a lookup function which, if it finds a
169 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
170 * dentry into place and return that dentry rather than the passed one,
171 * typically using d_splice_alias. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
Sage Weilf0023bc2011-10-28 10:02:42 -0700173#define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */
174#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */
Eric Parisc28f7e52009-05-21 17:01:29 -0400175
Al Virod83c49f2010-04-30 17:17:09 -0400176#define DCACHE_CANT_MOUNT 0x0100
Nick Piggin949854d2011-01-07 17:49:37 +1100177#define DCACHE_GENOCIDE 0x0200
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100178#define DCACHE_SHRINK_LIST 0x0400
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100179
Linus Torvalds830c0f02011-08-06 22:41:50 -0700180#define DCACHE_NFSFS_RENAMED 0x1000
181 /* this dentry has been "silly renamed" and has to be deleted on the last
182 * dput() */
183#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
184#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
185 /* Parent inode is watched by some fsnotify listener */
Nick Pigginfb045ad2011-01-07 17:49:55 +1100186
David Howells9875cf82011-01-14 18:45:21 +0000187#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
188#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
David Howellscc53ce52011-01-14 18:45:26 +0000189#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
Josef Bacik44396f42011-05-31 11:58:49 -0400190#define DCACHE_NEED_LOOKUP 0x80000 /* dentry requires i_op->lookup */
David Howells9875cf82011-01-14 18:45:21 +0000191#define DCACHE_MANAGED_DENTRY \
David Howellscc53ce52011-01-14 18:45:26 +0000192 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
David Howells9875cf82011-01-14 18:45:21 +0000193
Al Viro74c3cbe2007-07-22 08:04:18 -0400194extern seqlock_t rename_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196static inline int dname_external(struct dentry *dentry)
197{
198 return dentry->d_name.name != dentry->d_iname;
199}
200
201/*
202 * These are the low-level FS interfaces to the dcache..
203 */
204extern void d_instantiate(struct dentry *, struct inode *);
205extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
David Howells770bfad2006-08-22 20:06:07 -0400206extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
Nick Piggin789680d2011-01-07 17:49:30 +1100207extern void __d_drop(struct dentry *dentry);
208extern void d_drop(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209extern void d_delete(struct dentry *);
Nick Pigginfb045ad2011-01-07 17:49:55 +1100210extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211
212/* allocate/de-allocate */
213extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
Nick Piggin4b936882011-01-07 17:50:07 +1100214extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
Christoph Hellwige45b5902008-08-07 23:49:07 +0200216extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
Sage Weil46f72b32012-01-10 09:04:37 -0800217extern struct dentry *d_find_any_alias(struct inode *inode);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200218extern struct dentry * d_obtain_alias(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219extern void shrink_dcache_sb(struct super_block *);
220extern void shrink_dcache_parent(struct dentry *);
David Howellsc636ebd2006-10-11 01:22:19 -0700221extern void shrink_dcache_for_umount(struct super_block *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222extern int d_invalidate(struct dentry *);
223
224/* only used at mount-time */
Al Viroadc0e912012-01-08 16:49:21 -0500225extern struct dentry * d_make_root(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226
227/* <clickety>-<click> the ramfs-type tree */
228extern void d_genocide(struct dentry *);
229
230extern struct dentry *d_find_alias(struct inode *);
231extern void d_prune_aliases(struct inode *);
232
233/* test whether we have any submounts in a subdir tree */
234extern int have_submounts(struct dentry *);
235
236/*
237 * This adds the entry to the hash queues.
238 */
239extern void d_rehash(struct dentry *);
240
241/**
242 * d_add - add dentry to hash queues
243 * @entry: dentry to add
244 * @inode: The inode to attach to this dentry
245 *
246 * This adds the entry to the hash queues and initializes @inode.
247 * The entry was actually filled in earlier during d_alloc().
248 */
249
250static inline void d_add(struct dentry *entry, struct inode *inode)
251{
252 d_instantiate(entry, inode);
253 d_rehash(entry);
254}
255
256/**
257 * d_add_unique - add dentry to hash queues without aliasing
258 * @entry: dentry to add
259 * @inode: The inode to attach to this dentry
260 *
261 * This adds the entry to the hash queues and initializes @inode.
262 * The entry was actually filled in earlier during d_alloc().
263 */
264static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
265{
266 struct dentry *res;
267
268 res = d_instantiate_unique(entry, inode);
269 d_rehash(res != NULL ? res : entry);
270 return res;
271}
272
Nick Pigginfb2d5b82011-01-07 17:49:26 +1100273extern void dentry_update_name_case(struct dentry *, struct qstr *);
274
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275/* used for rename() and baskets */
276extern void d_move(struct dentry *, struct dentry *);
OGAWA Hirofumie2761a12008-10-16 07:50:28 +0900277extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278
279/* appendix may either be NULL or be used for transname suffixes */
Nick Piggin31e6b012011-01-07 17:49:52 +1100280extern struct dentry *d_lookup(struct dentry *, struct qstr *);
281extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
282extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
Linus Torvalds8966be92012-03-02 14:23:30 -0800283extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
284 const struct qstr *name,
Nick Piggin31e6b012011-01-07 17:49:52 +1100285 unsigned *seq, struct inode **inode);
286
287/**
288 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
289 * @dentry: dentry to take a ref on
290 * @seq: seqcount to verify against
Randy Dunlap2a8c0c62011-01-08 19:37:20 -0800291 * Returns: 0 on failure, else 1.
Nick Piggin31e6b012011-01-07 17:49:52 +1100292 *
293 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
294 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
295 */
296static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
297{
298 int ret = 0;
299
300 assert_spin_locked(&dentry->d_lock);
301 if (!read_seqcount_retry(&dentry->d_seq, seq)) {
302 ret = 1;
303 dentry->d_count++;
304 }
305
306 return ret;
307}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
309/* validate "insecure" dentry pointer */
310extern int d_validate(struct dentry *, struct dentry *);
311
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700312/*
313 * helper function for dentry_operations.d_dname() members
314 */
315extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
316
Al Viro02125a82011-12-05 08:43:34 -0500317extern char *__d_path(const struct path *, const struct path *, char *, int);
318extern char *d_absolute_path(const struct path *, char *, int);
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -0700319extern char *d_path(const struct path *, char *, int);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +0200320extern char *d_path_with_unreachable(const struct path *, char *, int);
Nick Pigginec2447c2011-01-07 17:49:29 +1100321extern char *dentry_path_raw(struct dentry *, char *, int);
Ram Pai6092d042008-03-27 13:06:20 +0100322extern char *dentry_path(struct dentry *, char *, int);
Jan Blunckcf28b482008-02-14 19:38:44 -0800323
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324/* Allocation counts.. */
325
326/**
Nick Piggindc0474b2011-01-07 17:49:43 +1100327 * dget, dget_dlock - get a reference to a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 * @dentry: dentry to get a reference to
329 *
330 * Given a dentry or %NULL pointer increment the reference count
331 * if appropriate and return the dentry. A dentry will not be
Nick Piggindc0474b2011-01-07 17:49:43 +1100332 * destroyed when it has references.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100334static inline struct dentry *dget_dlock(struct dentry *dentry)
335{
Nick Piggindc0474b2011-01-07 17:49:43 +1100336 if (dentry)
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100337 dentry->d_count++;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100338 return dentry;
339}
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100340
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341static inline struct dentry *dget(struct dentry *dentry)
342{
343 if (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100344 spin_lock(&dentry->d_lock);
345 dget_dlock(dentry);
346 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 }
348 return dentry;
349}
350
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100351extern struct dentry *dget_parent(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352
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
360static inline int d_unhashed(struct dentry *dentry)
361{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700362 return hlist_bl_unhashed(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363}
364
Alexey Dobriyanf3da3922009-05-04 03:32:03 +0400365static inline int d_unlinked(struct dentry *dentry)
366{
367 return d_unhashed(dentry) && !IS_ROOT(dentry);
368}
369
Al Virod83c49f2010-04-30 17:17:09 -0400370static inline int cant_mount(struct dentry *dentry)
371{
372 return (dentry->d_flags & DCACHE_CANT_MOUNT);
373}
374
375static 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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382extern void dput(struct dentry *);
383
David Howellscc53ce52011-01-14 18:45:26 +0000384static inline bool d_managed(struct dentry *dentry)
385{
386 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
387}
388
389static inline bool d_mountpoint(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390{
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100391 return dentry->d_flags & DCACHE_MOUNTED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392}
393
Josef Bacik44396f42011-05-31 11:58:49 -0400394static inline bool d_need_lookup(struct dentry *dentry)
395{
396 return dentry->d_flags & DCACHE_NEED_LOOKUP;
397}
398
399extern void d_clear_need_lookup(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400
401extern int sysctl_vfs_cache_pressure;
402
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403#endif /* __LINUX_DCACHE_H */