1 #ifndef __LINUX_DCACHE_H 2 #define __LINUX_DCACHE_H 3 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> 13 14 struct path; 15 struct 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 /* The hash is always the low bits of hash_len */ 29 #ifdef __LITTLE_ENDIAN 30 #define HASH_LEN_DECLARE u32 hash; u32 len; 31 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8)) 32 #else 33 #define HASH_LEN_DECLARE u32 len; u32 hash; 34 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8)) 35 #endif 36 37 /* 38 * "quick string" -- eases parameter passing, but more importantly 39 * saves "metadata" about the string (ie length and the hash). 40 * 41 * hash comes first so it snuggles against d_parent in the 42 * dentry. 43 */ 44 struct qstr { 45 union { 46 struct { 47 HASH_LEN_DECLARE; 48 }; 49 u64 hash_len; 50 }; 51 const unsigned char *name; 52 }; 53 54 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n } 55 #define hashlen_hash(hashlen) ((u32) (hashlen)) 56 #define hashlen_len(hashlen) ((u32)((hashlen) >> 32)) 57 #define hashlen_create(hash,len) (((u64)(len)<<32)|(u32)(hash)) 58 59 struct dentry_stat_t { 60 long nr_dentry; 61 long nr_unused; 62 long age_limit; /* age in seconds */ 63 long want_pages; /* pages requested by system */ 64 long dummy[2]; 65 }; 66 extern struct dentry_stat_t dentry_stat; 67 68 /* Name hashing routines. Initial hash value */ 69 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ 70 #define init_name_hash() 0 71 72 /* partial hash update function. Assume roughly 4 bits per character */ 73 static inline unsigned long 74 partial_name_hash(unsigned long c, unsigned long prevhash) 75 { 76 return (prevhash + (c << 4) + (c >> 4)) * 11; 77 } 78 79 /* 80 * Finally: cut down the number of bits to a int value (and try to avoid 81 * losing bits) 82 */ 83 static inline unsigned long end_name_hash(unsigned long hash) 84 { 85 return (unsigned int) hash; 86 } 87 88 /* Compute the hash for a name string. */ 89 extern unsigned int full_name_hash(const unsigned char *, unsigned int); 90 91 /* 92 * Try to keep struct dentry aligned on 64 byte cachelines (this will 93 * give reasonable cacheline footprint with larger lines without the 94 * large memory footprint increase). 95 */ 96 #ifdef CONFIG_64BIT 97 # define DNAME_INLINE_LEN 32 /* 192 bytes */ 98 #else 99 # ifdef CONFIG_SMP 100 # define DNAME_INLINE_LEN 36 /* 128 bytes */ 101 # else 102 # define DNAME_INLINE_LEN 40 /* 128 bytes */ 103 # endif 104 #endif 105 106 #define d_lock d_lockref.lock 107 108 struct dentry { 109 /* RCU lookup touched fields */ 110 unsigned int d_flags; /* protected by d_lock */ 111 seqcount_t d_seq; /* per dentry seqlock */ 112 struct hlist_bl_node d_hash; /* lookup hash list */ 113 struct dentry *d_parent; /* parent directory */ 114 struct qstr d_name; 115 struct inode *d_inode; /* Where the name belongs to - NULL is 116 * negative */ 117 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ 118 119 /* Ref lookup also touches following */ 120 struct lockref d_lockref; /* per-dentry lock and refcount */ 121 const struct dentry_operations *d_op; 122 struct super_block *d_sb; /* The root of the dentry tree */ 123 unsigned long d_time; /* used by d_revalidate */ 124 void *d_fsdata; /* fs-specific data */ 125 126 struct list_head d_lru; /* LRU list */ 127 struct list_head d_child; /* child of parent list */ 128 struct list_head d_subdirs; /* our children */ 129 /* 130 * d_alias and d_rcu can share memory 131 */ 132 union { 133 struct hlist_node d_alias; /* inode alias list */ 134 struct rcu_head d_rcu; 135 } d_u; 136 }; 137 138 /* 139 * dentry->d_lock spinlock nesting subclasses: 140 * 141 * 0: normal 142 * 1: nested 143 */ 144 enum dentry_d_lock_class 145 { 146 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ 147 DENTRY_D_LOCK_NESTED 148 }; 149 150 struct dentry_operations { 151 int (*d_revalidate)(struct dentry *, unsigned int); 152 int (*d_weak_revalidate)(struct dentry *, unsigned int); 153 int (*d_hash)(const struct dentry *, struct qstr *); 154 int (*d_compare)(const struct dentry *, const struct dentry *, 155 unsigned int, const char *, const struct qstr *); 156 int (*d_delete)(const struct dentry *); 157 void (*d_release)(struct dentry *); 158 void (*d_prune)(struct dentry *); 159 void (*d_iput)(struct dentry *, struct inode *); 160 char *(*d_dname)(struct dentry *, char *, int); 161 struct vfsmount *(*d_automount)(struct path *); 162 int (*d_manage)(struct dentry *, bool); 163 } ____cacheline_aligned; 164 165 /* 166 * Locking rules for dentry_operations callbacks are to be found in 167 * Documentation/filesystems/Locking. Keep it updated! 168 * 169 * FUrther descriptions are found in Documentation/filesystems/vfs.txt. 170 * Keep it updated too! 171 */ 172 173 /* d_flags entries */ 174 #define DCACHE_OP_HASH 0x00000001 175 #define DCACHE_OP_COMPARE 0x00000002 176 #define DCACHE_OP_REVALIDATE 0x00000004 177 #define DCACHE_OP_DELETE 0x00000008 178 #define DCACHE_OP_PRUNE 0x00000010 179 180 #define DCACHE_DISCONNECTED 0x00000020 181 /* This dentry is possibly not currently connected to the dcache tree, in 182 * which case its parent will either be itself, or will have this flag as 183 * well. nfsd will not use a dentry with this bit set, but will first 184 * endeavour to clear the bit either by discovering that it is connected, 185 * or by performing lookup operations. Any filesystem which supports 186 * nfsd_operations MUST have a lookup function which, if it finds a 187 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that 188 * dentry into place and return that dentry rather than the passed one, 189 * typically using d_splice_alias. */ 190 191 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */ 192 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */ 193 194 #define DCACHE_CANT_MOUNT 0x00000100 195 #define DCACHE_GENOCIDE 0x00000200 196 #define DCACHE_SHRINK_LIST 0x00000400 197 198 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800 199 200 #define DCACHE_NFSFS_RENAMED 0x00001000 201 /* this dentry has been "silly renamed" and has to be deleted on the last 202 * dput() */ 203 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */ 204 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000 205 /* Parent inode is watched by some fsnotify listener */ 206 207 #define DCACHE_DENTRY_KILLED 0x00008000 208 209 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */ 210 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */ 211 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */ 212 #define DCACHE_MANAGED_DENTRY \ 213 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) 214 215 #define DCACHE_LRU_LIST 0x00080000 216 217 #define DCACHE_ENTRY_TYPE 0x00700000 218 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry */ 219 #define DCACHE_DIRECTORY_TYPE 0x00100000 /* Normal directory */ 220 #define DCACHE_AUTODIR_TYPE 0x00200000 /* Lookupless directory (presumed automount) */ 221 #define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */ 222 #define DCACHE_FILE_TYPE 0x00400000 /* Other file type */ 223 224 #define DCACHE_MAY_FREE 0x00800000 225 226 extern seqlock_t rename_lock; 227 228 /* 229 * These are the low-level FS interfaces to the dcache.. 230 */ 231 extern void d_instantiate(struct dentry *, struct inode *); 232 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); 233 extern int d_instantiate_no_diralias(struct dentry *, struct inode *); 234 extern void __d_drop(struct dentry *dentry); 235 extern void d_drop(struct dentry *dentry); 236 extern void d_delete(struct dentry *); 237 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); 238 239 /* allocate/de-allocate */ 240 extern struct dentry * d_alloc(struct dentry *, const struct qstr *); 241 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *); 242 extern struct dentry * d_splice_alias(struct inode *, struct dentry *); 243 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); 244 extern struct dentry *d_find_any_alias(struct inode *inode); 245 extern struct dentry * d_obtain_alias(struct inode *); 246 extern struct dentry * d_obtain_root(struct inode *); 247 extern void shrink_dcache_sb(struct super_block *); 248 extern void shrink_dcache_parent(struct dentry *); 249 extern void shrink_dcache_for_umount(struct super_block *); 250 extern void d_invalidate(struct dentry *); 251 252 /* only used at mount-time */ 253 extern struct dentry * d_make_root(struct inode *); 254 255 /* <clickety>-<click> the ramfs-type tree */ 256 extern void d_genocide(struct dentry *); 257 258 extern void d_tmpfile(struct dentry *, struct inode *); 259 260 extern struct dentry *d_find_alias(struct inode *); 261 extern void d_prune_aliases(struct inode *); 262 263 /* test whether we have any submounts in a subdir tree */ 264 extern int have_submounts(struct dentry *); 265 266 /* 267 * This adds the entry to the hash queues. 268 */ 269 extern void d_rehash(struct dentry *); 270 271 /** 272 * d_add - add dentry to hash queues 273 * @entry: dentry to add 274 * @inode: The inode to attach to this dentry 275 * 276 * This adds the entry to the hash queues and initializes @inode. 277 * The entry was actually filled in earlier during d_alloc(). 278 */ 279 280 static inline void d_add(struct dentry *entry, struct inode *inode) 281 { 282 d_instantiate(entry, inode); 283 d_rehash(entry); 284 } 285 286 /** 287 * d_add_unique - add dentry to hash queues without aliasing 288 * @entry: dentry to add 289 * @inode: The inode to attach to this dentry 290 * 291 * This adds the entry to the hash queues and initializes @inode. 292 * The entry was actually filled in earlier during d_alloc(). 293 */ 294 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) 295 { 296 struct dentry *res; 297 298 res = d_instantiate_unique(entry, inode); 299 d_rehash(res != NULL ? res : entry); 300 return res; 301 } 302 303 extern void dentry_update_name_case(struct dentry *, struct qstr *); 304 305 /* used for rename() and baskets */ 306 extern void d_move(struct dentry *, struct dentry *); 307 extern void d_exchange(struct dentry *, struct dentry *); 308 extern struct dentry *d_ancestor(struct dentry *, struct dentry *); 309 310 /* appendix may either be NULL or be used for transname suffixes */ 311 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *); 312 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); 313 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *); 314 extern struct dentry *__d_lookup_rcu(const struct dentry *parent, 315 const struct qstr *name, unsigned *seq); 316 317 static inline unsigned d_count(const struct dentry *dentry) 318 { 319 return dentry->d_lockref.count; 320 } 321 322 /* 323 * helper function for dentry_operations.d_dname() members 324 */ 325 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); 326 extern char *simple_dname(struct dentry *, char *, int); 327 328 extern char *__d_path(const struct path *, const struct path *, char *, int); 329 extern char *d_absolute_path(const struct path *, char *, int); 330 extern char *d_path(const struct path *, char *, int); 331 extern char *dentry_path_raw(struct dentry *, char *, int); 332 extern char *dentry_path(struct dentry *, char *, int); 333 334 /* Allocation counts.. */ 335 336 /** 337 * dget, dget_dlock - get a reference to a dentry 338 * @dentry: dentry to get a reference to 339 * 340 * Given a dentry or %NULL pointer increment the reference count 341 * if appropriate and return the dentry. A dentry will not be 342 * destroyed when it has references. 343 */ 344 static inline struct dentry *dget_dlock(struct dentry *dentry) 345 { 346 if (dentry) 347 dentry->d_lockref.count++; 348 return dentry; 349 } 350 351 static inline struct dentry *dget(struct dentry *dentry) 352 { 353 if (dentry) 354 lockref_get(&dentry->d_lockref); 355 return dentry; 356 } 357 358 extern struct dentry *dget_parent(struct dentry *dentry); 359 360 /** 361 * d_unhashed - is dentry hashed 362 * @dentry: entry to check 363 * 364 * Returns true if the dentry passed is not currently hashed. 365 */ 366 367 static inline int d_unhashed(const struct dentry *dentry) 368 { 369 return hlist_bl_unhashed(&dentry->d_hash); 370 } 371 372 static inline int d_unlinked(const struct dentry *dentry) 373 { 374 return d_unhashed(dentry) && !IS_ROOT(dentry); 375 } 376 377 static inline int cant_mount(const struct dentry *dentry) 378 { 379 return (dentry->d_flags & DCACHE_CANT_MOUNT); 380 } 381 382 static inline void dont_mount(struct dentry *dentry) 383 { 384 spin_lock(&dentry->d_lock); 385 dentry->d_flags |= DCACHE_CANT_MOUNT; 386 spin_unlock(&dentry->d_lock); 387 } 388 389 extern void dput(struct dentry *); 390 391 static inline bool d_managed(const struct dentry *dentry) 392 { 393 return dentry->d_flags & DCACHE_MANAGED_DENTRY; 394 } 395 396 static inline bool d_mountpoint(const struct dentry *dentry) 397 { 398 return dentry->d_flags & DCACHE_MOUNTED; 399 } 400 401 /* 402 * Directory cache entry type accessor functions. 403 */ 404 static inline void __d_set_type(struct dentry *dentry, unsigned type) 405 { 406 dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type; 407 } 408 409 static inline void __d_clear_type(struct dentry *dentry) 410 { 411 __d_set_type(dentry, DCACHE_MISS_TYPE); 412 } 413 414 static inline void d_set_type(struct dentry *dentry, unsigned type) 415 { 416 spin_lock(&dentry->d_lock); 417 __d_set_type(dentry, type); 418 spin_unlock(&dentry->d_lock); 419 } 420 421 static inline unsigned __d_entry_type(const struct dentry *dentry) 422 { 423 return dentry->d_flags & DCACHE_ENTRY_TYPE; 424 } 425 426 static inline bool d_can_lookup(const struct dentry *dentry) 427 { 428 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; 429 } 430 431 static inline bool d_is_autodir(const struct dentry *dentry) 432 { 433 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; 434 } 435 436 static inline bool d_is_dir(const struct dentry *dentry) 437 { 438 return d_can_lookup(dentry) || d_is_autodir(dentry); 439 } 440 441 static inline bool d_is_symlink(const struct dentry *dentry) 442 { 443 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; 444 } 445 446 static inline bool d_is_file(const struct dentry *dentry) 447 { 448 return __d_entry_type(dentry) == DCACHE_FILE_TYPE; 449 } 450 451 static inline bool d_is_negative(const struct dentry *dentry) 452 { 453 return __d_entry_type(dentry) == DCACHE_MISS_TYPE; 454 } 455 456 static inline bool d_is_positive(const struct dentry *dentry) 457 { 458 return !d_is_negative(dentry); 459 } 460 461 extern int sysctl_vfs_cache_pressure; 462 463 static inline unsigned long vfs_pressure_ratio(unsigned long val) 464 { 465 return mult_frac(val, sysctl_vfs_cache_pressure, 100); 466 } 467 #endif /* __LINUX_DCACHE_H */ 468