1 #ifndef __LINUX_DCACHE_H
2 #define __LINUX_DCACHE_H
4 #include <linux/atomic.h>
5 #include <linux/list.h>
6 #include <linux/rculist.h>
7 #include <linux/rculist_bl.h>
8 #include <linux/spinlock.h>
9 #include <linux/seqlock.h>
10 #include <linux/cache.h>
11 #include <linux/rcupdate.h>
12 #include <linux/lockref.h>
19 * linux/include/linux/dcache.h
21 * Dirent cache data structures
23 * (C) Copyright 1997 Thomas Schoebel-Theuer,
24 * with heavy changes by Linus Torvalds
27 #define IS_ROOT(x) ((x) == (x)->d_parent)
29 /* The hash is always the low bits of hash_len */
30 #ifdef __LITTLE_ENDIAN
31 #define HASH_LEN_DECLARE u32 hash; u32 len;
32 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8))
34 #define HASH_LEN_DECLARE u32 len; u32 hash;
35 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8))
39 * "quick string" -- eases parameter passing, but more importantly
40 * saves "metadata" about the string (ie length and the hash).
42 * hash comes first so it snuggles against d_parent in the
52 const unsigned char *name;
55 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n }
56 #define hashlen_hash(hashlen) ((u32) (hashlen))
57 #define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
58 #define hashlen_create(hash,len) (((u64)(len)<<32)|(u32)(hash))
60 struct dentry_stat_t {
63 long age_limit; /* age in seconds */
64 long want_pages; /* pages requested by system */
67 extern struct dentry_stat_t dentry_stat;
69 /* Name hashing routines. Initial hash value */
70 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
71 #define init_name_hash() 0
73 /* partial hash update function. Assume roughly 4 bits per character */
74 static inline unsigned long
75 partial_name_hash(unsigned long c, unsigned long prevhash)
77 return (prevhash + (c << 4) + (c >> 4)) * 11;
81 * Finally: cut down the number of bits to a int value (and try to avoid
84 static inline unsigned long end_name_hash(unsigned long hash)
86 return (unsigned int) hash;
89 /* Compute the hash for a name string. */
90 extern unsigned int full_name_hash(const unsigned char *, unsigned int);
93 * Try to keep struct dentry aligned on 64 byte cachelines (this will
94 * give reasonable cacheline footprint with larger lines without the
95 * large memory footprint increase).
98 # define DNAME_INLINE_LEN 32 /* 192 bytes */
101 # define DNAME_INLINE_LEN 36 /* 128 bytes */
103 # define DNAME_INLINE_LEN 40 /* 128 bytes */
107 #define d_lock d_lockref.lock
110 /* RCU lookup touched fields */
111 unsigned int d_flags; /* protected by d_lock */
112 seqcount_t d_seq; /* per dentry seqlock */
113 struct hlist_bl_node d_hash; /* lookup hash list */
114 struct dentry *d_parent; /* parent directory */
116 struct inode *d_inode; /* Where the name belongs to - NULL is
118 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */
120 /* Ref lookup also touches following */
121 struct lockref d_lockref; /* per-dentry lock and refcount */
122 const struct dentry_operations *d_op;
123 struct super_block *d_sb; /* The root of the dentry tree */
124 unsigned long d_time; /* used by d_revalidate */
125 void *d_fsdata; /* fs-specific data */
127 struct list_head d_lru; /* LRU list */
129 * d_child and d_rcu can share memory
132 struct list_head d_child; /* child of parent list */
133 struct rcu_head d_rcu;
135 struct list_head d_subdirs; /* our children */
136 struct hlist_node d_alias; /* inode alias list */
140 * dentry->d_lock spinlock nesting subclasses:
145 enum dentry_d_lock_class
147 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */
151 struct dentry_operations {
152 int (*d_revalidate)(struct dentry *, unsigned int);
153 int (*d_weak_revalidate)(struct dentry *, unsigned int);
154 int (*d_hash)(const struct dentry *, struct qstr *);
155 int (*d_compare)(const struct dentry *, const struct dentry *,
156 unsigned int, const char *, const struct qstr *);
157 int (*d_delete)(const struct dentry *);
158 void (*d_release)(struct dentry *);
159 void (*d_prune)(struct dentry *);
160 void (*d_iput)(struct dentry *, struct inode *);
161 char *(*d_dname)(struct dentry *, char *, int);
162 struct vfsmount *(*d_automount)(struct path *);
163 int (*d_manage)(struct dentry *, bool);
164 } ____cacheline_aligned;
167 * Locking rules for dentry_operations callbacks are to be found in
168 * Documentation/filesystems/Locking. Keep it updated!
170 * FUrther descriptions are found in Documentation/filesystems/vfs.txt.
171 * Keep it updated too!
174 /* d_flags entries */
175 #define DCACHE_OP_HASH 0x00000001
176 #define DCACHE_OP_COMPARE 0x00000002
177 #define DCACHE_OP_REVALIDATE 0x00000004
178 #define DCACHE_OP_DELETE 0x00000008
179 #define DCACHE_OP_PRUNE 0x00000010
181 #define DCACHE_DISCONNECTED 0x00000020
182 /* This dentry is possibly not currently connected to the dcache tree, in
183 * which case its parent will either be itself, or will have this flag as
184 * well. nfsd will not use a dentry with this bit set, but will first
185 * endeavour to clear the bit either by discovering that it is connected,
186 * or by performing lookup operations. Any filesystem which supports
187 * nfsd_operations MUST have a lookup function which, if it finds a
188 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that
189 * dentry into place and return that dentry rather than the passed one,
190 * typically using d_splice_alias. */
192 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */
193 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */
195 #define DCACHE_CANT_MOUNT 0x00000100
196 #define DCACHE_GENOCIDE 0x00000200
197 #define DCACHE_SHRINK_LIST 0x00000400
199 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800
201 #define DCACHE_NFSFS_RENAMED 0x00001000
202 /* this dentry has been "silly renamed" and has to be deleted on the last
204 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */
205 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000
206 /* Parent inode is watched by some fsnotify listener */
208 #define DCACHE_DENTRY_KILLED 0x00008000
210 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */
211 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */
212 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */
213 #define DCACHE_MANAGED_DENTRY \
214 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
216 #define DCACHE_LRU_LIST 0x00080000
218 #define DCACHE_ENTRY_TYPE 0x00700000
219 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry */
220 #define DCACHE_DIRECTORY_TYPE 0x00100000 /* Normal directory */
221 #define DCACHE_AUTODIR_TYPE 0x00200000 /* Lookupless directory (presumed automount) */
222 #define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */
223 #define DCACHE_FILE_TYPE 0x00400000 /* Other file type */
225 #define DCACHE_MAY_FREE 0x00800000
227 extern seqlock_t rename_lock;
229 static inline int dname_external(const struct dentry *dentry)
231 return dentry->d_name.name != dentry->d_iname;
235 * These are the low-level FS interfaces to the dcache..
237 extern void d_instantiate(struct dentry *, struct inode *);
238 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
239 extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
240 extern int d_instantiate_no_diralias(struct dentry *, struct inode *);
241 extern void __d_drop(struct dentry *dentry);
242 extern void d_drop(struct dentry *dentry);
243 extern void d_delete(struct dentry *);
244 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
246 /* allocate/de-allocate */
247 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
248 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
249 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
250 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
251 extern struct dentry *d_find_any_alias(struct inode *inode);
252 extern struct dentry * d_obtain_alias(struct inode *);
253 extern struct dentry * d_obtain_root(struct inode *);
254 extern void shrink_dcache_sb(struct super_block *);
255 extern void shrink_dcache_parent(struct dentry *);
256 extern void shrink_dcache_for_umount(struct super_block *);
257 extern int d_invalidate(struct dentry *);
259 /* only used at mount-time */
260 extern struct dentry * d_make_root(struct inode *);
262 /* <clickety>-<click> the ramfs-type tree */
263 extern void d_genocide(struct dentry *);
265 extern void d_tmpfile(struct dentry *, struct inode *);
267 extern struct dentry *d_find_alias(struct inode *);
268 extern void d_prune_aliases(struct inode *);
270 /* test whether we have any submounts in a subdir tree */
271 extern int have_submounts(struct dentry *);
272 extern int check_submounts_and_drop(struct dentry *);
275 * This adds the entry to the hash queues.
277 extern void d_rehash(struct dentry *);
280 * d_add - add dentry to hash queues
281 * @entry: dentry to add
282 * @inode: The inode to attach to this dentry
284 * This adds the entry to the hash queues and initializes @inode.
285 * The entry was actually filled in earlier during d_alloc().
288 static inline void d_add(struct dentry *entry, struct inode *inode)
290 d_instantiate(entry, inode);
295 * d_add_unique - add dentry to hash queues without aliasing
296 * @entry: dentry to add
297 * @inode: The inode to attach to this dentry
299 * This adds the entry to the hash queues and initializes @inode.
300 * The entry was actually filled in earlier during d_alloc().
302 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode)
306 res = d_instantiate_unique(entry, inode);
307 d_rehash(res != NULL ? res : entry);
311 extern void dentry_update_name_case(struct dentry *, struct qstr *);
313 /* used for rename() and baskets */
314 extern void d_move(struct dentry *, struct dentry *);
315 extern void d_exchange(struct dentry *, struct dentry *);
316 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
318 /* appendix may either be NULL or be used for transname suffixes */
319 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
320 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
321 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
322 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
323 const struct qstr *name, unsigned *seq);
325 static inline unsigned d_count(const struct dentry *dentry)
327 return dentry->d_lockref.count;
330 /* validate "insecure" dentry pointer */
331 extern int d_validate(struct dentry *, struct dentry *);
334 * helper function for dentry_operations.d_dname() members
336 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...);
337 extern char *simple_dname(struct dentry *, char *, int);
339 extern char *__d_path(const struct path *, const struct path *, char *, int);
340 extern char *d_absolute_path(const struct path *, char *, int);
341 extern char *d_path(const struct path *, char *, int);
342 extern char *dentry_path_raw(struct dentry *, char *, int);
343 extern char *dentry_path(struct dentry *, char *, int);
345 /* Allocation counts.. */
348 * dget, dget_dlock - get a reference to a dentry
349 * @dentry: dentry to get a reference to
351 * Given a dentry or %NULL pointer increment the reference count
352 * if appropriate and return the dentry. A dentry will not be
353 * destroyed when it has references.
355 static inline struct dentry *dget_dlock(struct dentry *dentry)
358 dentry->d_lockref.count++;
362 static inline struct dentry *dget(struct dentry *dentry)
365 lockref_get(&dentry->d_lockref);
369 extern struct dentry *dget_parent(struct dentry *dentry);
372 * d_unhashed - is dentry hashed
373 * @dentry: entry to check
375 * Returns true if the dentry passed is not currently hashed.
378 static inline int d_unhashed(const struct dentry *dentry)
380 return hlist_bl_unhashed(&dentry->d_hash);
383 static inline int d_unlinked(const struct dentry *dentry)
385 return d_unhashed(dentry) && !IS_ROOT(dentry);
388 static inline int cant_mount(const struct dentry *dentry)
390 return (dentry->d_flags & DCACHE_CANT_MOUNT);
393 static inline void dont_mount(struct dentry *dentry)
395 spin_lock(&dentry->d_lock);
396 dentry->d_flags |= DCACHE_CANT_MOUNT;
397 spin_unlock(&dentry->d_lock);
400 extern void dput(struct dentry *);
402 static inline bool d_managed(const struct dentry *dentry)
404 return dentry->d_flags & DCACHE_MANAGED_DENTRY;
407 static inline bool d_mountpoint(const struct dentry *dentry)
409 return dentry->d_flags & DCACHE_MOUNTED;
413 * Directory cache entry type accessor functions.
415 static inline void __d_set_type(struct dentry *dentry, unsigned type)
417 dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type;
420 static inline void __d_clear_type(struct dentry *dentry)
422 __d_set_type(dentry, DCACHE_MISS_TYPE);
425 static inline void d_set_type(struct dentry *dentry, unsigned type)
427 spin_lock(&dentry->d_lock);
428 __d_set_type(dentry, type);
429 spin_unlock(&dentry->d_lock);
432 static inline unsigned __d_entry_type(const struct dentry *dentry)
434 return dentry->d_flags & DCACHE_ENTRY_TYPE;
437 static inline bool d_can_lookup(const struct dentry *dentry)
439 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE;
442 static inline bool d_is_autodir(const struct dentry *dentry)
444 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE;
447 static inline bool d_is_dir(const struct dentry *dentry)
449 return d_can_lookup(dentry) || d_is_autodir(dentry);
452 static inline bool d_is_symlink(const struct dentry *dentry)
454 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE;
457 static inline bool d_is_file(const struct dentry *dentry)
459 return __d_entry_type(dentry) == DCACHE_FILE_TYPE;
462 static inline bool d_is_negative(const struct dentry *dentry)
464 return __d_entry_type(dentry) == DCACHE_MISS_TYPE;
467 static inline bool d_is_positive(const struct dentry *dentry)
469 return !d_is_negative(dentry);
472 extern int sysctl_vfs_cache_pressure;
474 static inline unsigned long vfs_pressure_ratio(unsigned long val)
476 return mult_frac(val, sysctl_vfs_cache_pressure, 100);
478 #endif /* __LINUX_DCACHE_H */