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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
Linus Torvalds26fe5752012-05-10 13:14:12 -070028/* The hash is always the low bits of hash_len */
29#ifdef __LITTLE_ENDIAN
30 #define HASH_LEN_DECLARE u32 hash; u32 len;
31#else
32 #define HASH_LEN_DECLARE u32 len; u32 hash;
33#endif
34
Linus Torvalds1da177e2005-04-16 15:20:36 -070035/*
36 * "quick string" -- eases parameter passing, but more importantly
37 * saves "metadata" about the string (ie length and the hash).
38 *
39 * hash comes first so it snuggles against d_parent in the
40 * dentry.
41 */
42struct qstr {
Linus Torvalds26fe5752012-05-10 13:14:12 -070043 union {
44 struct {
45 HASH_LEN_DECLARE;
46 };
47 u64 hash_len;
48 };
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 const unsigned char *name;
50};
51
Linus Torvalds26fe5752012-05-10 13:14:12 -070052#define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
53#define hashlen_hash(hashlen) ((u32) (hashlen))
54#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
55
Linus Torvalds1da177e2005-04-16 15:20:36 -070056struct dentry_stat_t {
57 int nr_dentry;
58 int nr_unused;
59 int age_limit; /* age in seconds */
60 int want_pages; /* pages requested by system */
61 int dummy[2];
62};
63extern struct dentry_stat_t dentry_stat;
64
65/* Name hashing routines. Initial hash value */
66/* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
67#define init_name_hash() 0
68
69/* partial hash update function. Assume roughly 4 bits per character */
70static inline unsigned long
71partial_name_hash(unsigned long c, unsigned long prevhash)
72{
73 return (prevhash + (c << 4) + (c >> 4)) * 11;
74}
75
76/*
77 * Finally: cut down the number of bits to a int value (and try to avoid
78 * losing bits)
79 */
80static inline unsigned long end_name_hash(unsigned long hash)
81{
82 return (unsigned int) hash;
83}
84
85/* Compute the hash for a name string. */
Linus Torvalds0145acc2012-03-02 14:32:59 -080086extern unsigned int full_name_hash(const unsigned char *, unsigned int);
Linus Torvalds1da177e2005-04-16 15:20:36 -070087
Nick Pigginc2452f32008-12-01 09:33:43 +010088/*
89 * Try to keep struct dentry aligned on 64 byte cachelines (this will
90 * give reasonable cacheline footprint with larger lines without the
91 * large memory footprint increase).
92 */
93#ifdef CONFIG_64BIT
Nick Piggin44a7d7a2011-01-07 17:49:56 +110094# define DNAME_INLINE_LEN 32 /* 192 bytes */
Nick Pigginc2452f32008-12-01 09:33:43 +010095#else
Nick Piggin44a7d7a2011-01-07 17:49:56 +110096# ifdef CONFIG_SMP
97# define DNAME_INLINE_LEN 36 /* 128 bytes */
98# else
99# define DNAME_INLINE_LEN 40 /* 128 bytes */
100# endif
Nick Pigginc2452f32008-12-01 09:33:43 +0100101#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
103struct dentry {
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100104 /* RCU lookup touched fields */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 unsigned int d_flags; /* protected by d_lock */
Nick Piggin31e6b012011-01-07 17:49:52 +1100106 seqcount_t d_seq; /* per dentry seqlock */
Nick Pigginceb5bdc2011-01-07 17:50:05 +1100107 struct hlist_bl_node d_hash; /* lookup hash list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 struct dentry *d_parent; /* parent directory */
109 struct qstr d_name;
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100110 struct inode *d_inode; /* Where the name belongs to - NULL is
111 * negative */
112 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
113
114 /* Ref lookup also touches following */
115 unsigned int d_count; /* protected by d_lock */
116 spinlock_t d_lock; /* per dentry lock */
117 const struct dentry_operations *d_op;
118 struct super_block *d_sb; /* The root of the dentry tree */
119 unsigned long d_time; /* used by d_revalidate */
120 void *d_fsdata; /* fs-specific data */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121
122 struct list_head d_lru; /* LRU list */
Eric Dumazet5160ee62006-01-08 01:03:32 -0800123 /*
124 * d_child and d_rcu can share memory
125 */
126 union {
127 struct list_head d_child; /* child of parent list */
128 struct rcu_head d_rcu;
129 } d_u;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 struct list_head d_subdirs; /* our children */
Al Virob3d9b7a2012-06-09 13:51:19 -0400131 struct hlist_node d_alias; /* inode alias list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132};
133
Ingo Molnara90b9c02006-07-03 00:25:04 -0700134/*
135 * dentry->d_lock spinlock nesting subclasses:
136 *
137 * 0: normal
138 * 1: nested
139 */
140enum dentry_d_lock_class
141{
142 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
143 DENTRY_D_LOCK_NESTED
144};
145
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146struct dentry_operations {
Al Viro0b728e12012-06-10 16:03:43 -0400147 int (*d_revalidate)(struct dentry *, unsigned int);
Nick Pigginb1e6a012011-01-07 17:49:28 +1100148 int (*d_hash)(const struct dentry *, const struct inode *,
149 struct qstr *);
Nick Piggin621e1552011-01-07 17:49:27 +1100150 int (*d_compare)(const struct dentry *, const struct inode *,
151 const struct dentry *, const struct inode *,
152 unsigned int, const char *, const struct qstr *);
Nick Pigginfe15ce42011-01-07 17:49:23 +1100153 int (*d_delete)(const struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 void (*d_release)(struct dentry *);
Sage Weilf0023bc2011-10-28 10:02:42 -0700155 void (*d_prune)(struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 void (*d_iput)(struct dentry *, struct inode *);
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700157 char *(*d_dname)(struct dentry *, char *, int);
David Howells9875cf82011-01-14 18:45:21 +0000158 struct vfsmount *(*d_automount)(struct path *);
Al Viro1aed3e42011-03-18 09:09:02 -0400159 int (*d_manage)(struct dentry *, bool);
Nick Piggin44a7d7a2011-01-07 17:49:56 +1100160} ____cacheline_aligned;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Nick Piggin5eef7fa2011-01-07 17:49:22 +1100162/*
163 * Locking rules for dentry_operations callbacks are to be found in
164 * Documentation/filesystems/Locking. Keep it updated!
165 *
Nick Piggin621e1552011-01-07 17:49:27 +1100166 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
167 * Keep it updated too!
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 */
169
170/* d_flags entries */
Linus Torvalds830c0f02011-08-06 22:41:50 -0700171#define DCACHE_OP_HASH 0x0001
172#define DCACHE_OP_COMPARE 0x0002
173#define DCACHE_OP_REVALIDATE 0x0004
174#define DCACHE_OP_DELETE 0x0008
Sage Weilf0023bc2011-10-28 10:02:42 -0700175#define DCACHE_OP_PRUNE 0x0010
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100176
Sage Weilf0023bc2011-10-28 10:02:42 -0700177#define DCACHE_DISCONNECTED 0x0020
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100178 /* This dentry is possibly not currently connected to the dcache tree, in
179 * which case its parent will either be itself, or will have this flag as
180 * well. nfsd will not use a dentry with this bit set, but will first
181 * endeavour to clear the bit either by discovering that it is connected,
182 * or by performing lookup operations. Any filesystem which supports
183 * nfsd_operations MUST have a lookup function which, if it finds a
184 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
185 * dentry into place and return that dentry rather than the passed one,
186 * typically using d_splice_alias. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
Sage Weilf0023bc2011-10-28 10:02:42 -0700188#define DCACHE_REFERENCED 0x0040 /* Recently used, don't discard. */
189#define DCACHE_RCUACCESS 0x0080 /* Entry has ever been RCU-visible */
Eric Parisc28f7e52009-05-21 17:01:29 -0400190
Al Virod83c49f2010-04-30 17:17:09 -0400191#define DCACHE_CANT_MOUNT 0x0100
Nick Piggin949854d2011-01-07 17:49:37 +1100192#define DCACHE_GENOCIDE 0x0200
Miklos Szeredieaf5f902012-01-10 18:22:25 +0100193#define DCACHE_SHRINK_LIST 0x0400
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100194
Linus Torvalds830c0f02011-08-06 22:41:50 -0700195#define DCACHE_NFSFS_RENAMED 0x1000
196 /* this dentry has been "silly renamed" and has to be deleted on the last
197 * dput() */
198#define DCACHE_COOKIE 0x2000 /* For use by dcookie subsystem */
199#define DCACHE_FSNOTIFY_PARENT_WATCHED 0x4000
200 /* Parent inode is watched by some fsnotify listener */
Nick Pigginfb045ad2011-01-07 17:49:55 +1100201
David Howells9875cf82011-01-14 18:45:21 +0000202#define DCACHE_MOUNTED 0x10000 /* is a mountpoint */
203#define DCACHE_NEED_AUTOMOUNT 0x20000 /* handle automount on this dir */
David Howellscc53ce52011-01-14 18:45:26 +0000204#define DCACHE_MANAGE_TRANSIT 0x40000 /* manage transit from this dirent */
David Howells9875cf82011-01-14 18:45:21 +0000205#define DCACHE_MANAGED_DENTRY \
David Howellscc53ce52011-01-14 18:45:26 +0000206 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
David Howells9875cf82011-01-14 18:45:21 +0000207
Miklos Szeredib161dfa62012-09-17 22:31:38 +0200208#define DCACHE_DENTRY_KILLED 0x100000
209
Al Viro74c3cbe2007-07-22 08:04:18 -0400210extern seqlock_t rename_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212static inline int dname_external(struct dentry *dentry)
213{
214 return dentry->d_name.name != dentry->d_iname;
215}
216
217/*
218 * These are the low-level FS interfaces to the dcache..
219 */
220extern void d_instantiate(struct dentry *, struct inode *);
221extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
David Howells770bfad2006-08-22 20:06:07 -0400222extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
Nick Piggin789680d2011-01-07 17:49:30 +1100223extern void __d_drop(struct dentry *dentry);
224extern void d_drop(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225extern void d_delete(struct dentry *);
Nick Pigginfb045ad2011-01-07 17:49:55 +1100226extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
228/* allocate/de-allocate */
229extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
Nick Piggin4b936882011-01-07 17:50:07 +1100230extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
Christoph Hellwige45b5902008-08-07 23:49:07 +0200232extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
Sage Weil46f72b32012-01-10 09:04:37 -0800233extern struct dentry *d_find_any_alias(struct inode *inode);
Christoph Hellwig4ea3ada2008-08-11 15:48:57 +0200234extern struct dentry * d_obtain_alias(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235extern void shrink_dcache_sb(struct super_block *);
236extern void shrink_dcache_parent(struct dentry *);
David Howellsc636ebd2006-10-11 01:22:19 -0700237extern void shrink_dcache_for_umount(struct super_block *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238extern int d_invalidate(struct dentry *);
239
240/* only used at mount-time */
Al Viroadc0e912012-01-08 16:49:21 -0500241extern struct dentry * d_make_root(struct inode *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242
243/* <clickety>-<click> the ramfs-type tree */
244extern void d_genocide(struct dentry *);
245
246extern struct dentry *d_find_alias(struct inode *);
247extern void d_prune_aliases(struct inode *);
248
249/* test whether we have any submounts in a subdir tree */
250extern int have_submounts(struct dentry *);
251
252/*
253 * This adds the entry to the hash queues.
254 */
255extern void d_rehash(struct dentry *);
256
257/**
258 * d_add - add dentry to hash queues
259 * @entry: dentry to add
260 * @inode: The inode to attach to this dentry
261 *
262 * This adds the entry to the hash queues and initializes @inode.
263 * The entry was actually filled in earlier during d_alloc().
264 */
265
266static inline void d_add(struct dentry *entry, struct inode *inode)
267{
268 d_instantiate(entry, inode);
269 d_rehash(entry);
270}
271
272/**
273 * d_add_unique - add dentry to hash queues without aliasing
274 * @entry: dentry to add
275 * @inode: The inode to attach to this dentry
276 *
277 * This adds the entry to the hash queues and initializes @inode.
278 * The entry was actually filled in earlier during d_alloc().
279 */
280static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
281{
282 struct dentry *res;
283
284 res = d_instantiate_unique(entry, inode);
285 d_rehash(res != NULL ? res : entry);
286 return res;
287}
288
Nick Pigginfb2d5b82011-01-07 17:49:26 +1100289extern void dentry_update_name_case(struct dentry *, struct qstr *);
290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291/* used for rename() and baskets */
292extern void d_move(struct dentry *, struct dentry *);
OGAWA Hirofumie2761a12008-10-16 07:50:28 +0900293extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294
295/* appendix may either be NULL or be used for transname suffixes */
Nick Piggin31e6b012011-01-07 17:49:52 +1100296extern struct dentry *d_lookup(struct dentry *, struct qstr *);
297extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
298extern struct dentry *__d_lookup(struct dentry *, struct qstr *);
Linus Torvalds8966be92012-03-02 14:23:30 -0800299extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
300 const struct qstr *name,
Linus Torvalds12f8ad42012-05-04 14:59:14 -0700301 unsigned *seq, struct inode *inode);
Nick Piggin31e6b012011-01-07 17:49:52 +1100302
303/**
304 * __d_rcu_to_refcount - take a refcount on dentry if sequence check is ok
305 * @dentry: dentry to take a ref on
306 * @seq: seqcount to verify against
Randy Dunlap2a8c0c682011-01-08 19:37:20 -0800307 * Returns: 0 on failure, else 1.
Nick Piggin31e6b012011-01-07 17:49:52 +1100308 *
309 * __d_rcu_to_refcount operates on a dentry,seq pair that was returned
310 * by __d_lookup_rcu, to get a reference on an rcu-walk dentry.
311 */
312static inline int __d_rcu_to_refcount(struct dentry *dentry, unsigned seq)
313{
314 int ret = 0;
315
316 assert_spin_locked(&dentry->d_lock);
317 if (!read_seqcount_retry(&dentry->d_seq, seq)) {
318 ret = 1;
319 dentry->d_count++;
320 }
321
322 return ret;
323}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
325/* validate "insecure" dentry pointer */
326extern int d_validate(struct dentry *, struct dentry *);
327
Eric Dumazetc23fbb62007-05-08 00:26:18 -0700328/*
329 * helper function for dentry_operations.d_dname() members
330 */
331extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
332
Al Viro02125a82011-12-05 08:43:34 -0500333extern char *__d_path(const struct path *, const struct path *, char *, int);
334extern char *d_absolute_path(const struct path *, char *, int);
Jan Engelhardt20d4fdc2008-06-09 16:40:36 -0700335extern char *d_path(const struct path *, char *, int);
Miklos Szeredi8df9d1a2010-08-10 11:41:41 +0200336extern char *d_path_with_unreachable(const struct path *, char *, int);
Nick Pigginec2447c2011-01-07 17:49:29 +1100337extern char *dentry_path_raw(struct dentry *, char *, int);
Ram Pai6092d042008-03-27 13:06:20 +0100338extern char *dentry_path(struct dentry *, char *, int);
Jan Blunckcf28b482008-02-14 19:38:44 -0800339
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340/* Allocation counts.. */
341
342/**
Nick Piggindc0474b2011-01-07 17:49:43 +1100343 * dget, dget_dlock - get a reference to a dentry
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 * @dentry: dentry to get a reference to
345 *
346 * Given a dentry or %NULL pointer increment the reference count
347 * if appropriate and return the dentry. A dentry will not be
Nick Piggindc0474b2011-01-07 17:49:43 +1100348 * destroyed when it has references.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 */
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100350static inline struct dentry *dget_dlock(struct dentry *dentry)
351{
Nick Piggindc0474b2011-01-07 17:49:43 +1100352 if (dentry)
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100353 dentry->d_count++;
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100354 return dentry;
355}
Nick Piggin2fd6b7f2011-01-07 17:49:34 +1100356
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357static inline struct dentry *dget(struct dentry *dentry)
358{
359 if (dentry) {
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100360 spin_lock(&dentry->d_lock);
361 dget_dlock(dentry);
362 spin_unlock(&dentry->d_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 }
364 return dentry;
365}
366
Nick Pigginb7ab39f2011-01-07 17:49:32 +1100367extern struct dentry *dget_parent(struct dentry *dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368
369/**
370 * d_unhashed - is dentry hashed
371 * @dentry: entry to check
372 *
373 * Returns true if the dentry passed is not currently hashed.
374 */
375
376static inline int d_unhashed(struct dentry *dentry)
377{
Linus Torvaldsdea36672011-04-24 07:58:46 -0700378 return hlist_bl_unhashed(&dentry->d_hash);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379}
380
Alexey Dobriyanf3da3922009-05-04 03:32:03 +0400381static inline int d_unlinked(struct dentry *dentry)
382{
383 return d_unhashed(dentry) && !IS_ROOT(dentry);
384}
385
Al Virod83c49f2010-04-30 17:17:09 -0400386static inline int cant_mount(struct dentry *dentry)
387{
388 return (dentry->d_flags & DCACHE_CANT_MOUNT);
389}
390
391static inline void dont_mount(struct dentry *dentry)
392{
393 spin_lock(&dentry->d_lock);
394 dentry->d_flags |= DCACHE_CANT_MOUNT;
395 spin_unlock(&dentry->d_lock);
396}
397
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398extern void dput(struct dentry *);
399
David Howellscc53ce52011-01-14 18:45:26 +0000400static inline bool d_managed(struct dentry *dentry)
401{
402 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
403}
404
405static inline bool d_mountpoint(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
Nick Piggin5f57cbc2011-01-07 17:49:54 +1100407 return dentry->d_flags & DCACHE_MOUNTED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408}
409
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410extern int sysctl_vfs_cache_pressure;
411
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412#endif /* __LINUX_DCACHE_H */