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 nameidata; 15 struct path; 16 struct vfsmount; 17 18 /* 19 * linux/include/linux/dcache.h 20 * 21 * Dirent cache data structures 22 * 23 * (C) Copyright 1997 Thomas Schoebel-Theuer, 24 * with heavy changes by Linus Torvalds 25 */ 26 27 #define IS_ROOT(x) ((x) == (x)->d_parent) 28 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 #else 33 #define HASH_LEN_DECLARE u32 len; u32 hash; 34 #endif 35 36 /* 37 * "quick string" -- eases parameter passing, but more importantly 38 * saves "metadata" about the string (ie length and the hash). 39 * 40 * hash comes first so it snuggles against d_parent in the 41 * dentry. 42 */ 43 struct qstr { 44 union { 45 struct { 46 HASH_LEN_DECLARE; 47 }; 48 u64 hash_len; 49 }; 50 const unsigned char *name; 51 }; 52 53 #define QSTR_INIT(n,l) { { { .len = l } }, .name = n } 54 #define hashlen_hash(hashlen) ((u32) (hashlen)) 55 #define hashlen_len(hashlen) ((u32)((hashlen) >> 32)) 56 57 struct dentry_stat_t { 58 long nr_dentry; 59 long nr_unused; 60 long age_limit; /* age in seconds */ 61 long want_pages; /* pages requested by system */ 62 long dummy[2]; 63 }; 64 extern struct dentry_stat_t dentry_stat; 65 66 /* Name hashing routines. Initial hash value */ 67 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */ 68 #define init_name_hash() 0 69 70 /* partial hash update function. Assume roughly 4 bits per character */ 71 static inline unsigned long 72 partial_name_hash(unsigned long c, unsigned long prevhash) 73 { 74 return (prevhash + (c << 4) + (c >> 4)) * 11; 75 } 76 77 /* 78 * Finally: cut down the number of bits to a int value (and try to avoid 79 * losing bits) 80 */ 81 static inline unsigned long end_name_hash(unsigned long hash) 82 { 83 return (unsigned int) hash; 84 } 85 86 /* Compute the hash for a name string. */ 87 extern unsigned int full_name_hash(const unsigned char *, unsigned int); 88 89 /* 90 * Try to keep struct dentry aligned on 64 byte cachelines (this will 91 * give reasonable cacheline footprint with larger lines without the 92 * large memory footprint increase). 93 */ 94 #ifdef CONFIG_64BIT 95 # define DNAME_INLINE_LEN 32 /* 192 bytes */ 96 #else 97 # ifdef CONFIG_SMP 98 # define DNAME_INLINE_LEN 36 /* 128 bytes */ 99 # else 100 # define DNAME_INLINE_LEN 40 /* 128 bytes */ 101 # endif 102 #endif 103 104 #define d_lock d_lockref.lock 105 106 struct dentry { 107 /* RCU lookup touched fields */ 108 unsigned int d_flags; /* protected by d_lock */ 109 seqcount_t d_seq; /* per dentry seqlock */ 110 struct hlist_bl_node d_hash; /* lookup hash list */ 111 struct dentry *d_parent; /* parent directory */ 112 struct qstr d_name; 113 struct inode *d_inode; /* Where the name belongs to - NULL is 114 * negative */ 115 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ 116 117 /* Ref lookup also touches following */ 118 struct lockref d_lockref; /* per-dentry lock and refcount */ 119 const struct dentry_operations *d_op; 120 struct super_block *d_sb; /* The root of the dentry tree */ 121 unsigned long d_time; /* used by d_revalidate */ 122 void *d_fsdata; /* fs-specific data */ 123 124 struct list_head d_lru; /* LRU list */ 125 /* 126 * d_child and d_rcu can share memory 127 */ 128 union { 129 struct list_head d_child; /* child of parent list */ 130 struct rcu_head d_rcu; 131 } d_u; 132 struct list_head d_subdirs; /* our children */ 133 struct hlist_node d_alias; /* inode alias list */ 134 }; 135 136 /* 137 * dentry->d_lock spinlock nesting subclasses: 138 * 139 * 0: normal 140 * 1: nested 141 */ 142 enum dentry_d_lock_class 143 { 144 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ 145 DENTRY_D_LOCK_NESTED 146 }; 147 148 struct dentry_operations { 149 int (*d_revalidate)(struct dentry *, unsigned int); 150 int (*d_weak_revalidate)(struct dentry *, unsigned int); 151 int (*d_hash)(const struct dentry *, struct qstr *); 152 int (*d_compare)(const struct dentry *, const struct dentry *, 153 unsigned int, const char *, const struct qstr *); 154 int (*d_delete)(const struct dentry *); 155 void (*d_release)(struct dentry *); 156 void (*d_prune)(struct dentry *); 157 void (*d_iput)(struct dentry *, struct inode *); 158 char *(*d_dname)(struct dentry *, char *, int); 159 struct vfsmount *(*d_automount)(struct path *); 160 int (*d_manage)(struct dentry *, bool); 161 } ____cacheline_aligned; 162 163 /* 164 * Locking rules for dentry_operations callbacks are to be found in 165 * Documentation/filesystems/Locking. Keep it updated! 166 * 167 * FUrther descriptions are found in Documentation/filesystems/vfs.txt. 168 * Keep it updated too! 169 */ 170 171 /* d_flags entries */ 172 #define DCACHE_OP_HASH 0x00000001 173 #define DCACHE_OP_COMPARE 0x00000002 174 #define DCACHE_OP_REVALIDATE 0x00000004 175 #define DCACHE_OP_DELETE 0x00000008 176 #define DCACHE_OP_PRUNE 0x00000010 177 178 #define DCACHE_DISCONNECTED 0x00000020 179 /* This dentry is possibly not currently connected to the dcache tree, in 180 * which case its parent will either be itself, or will have this flag as 181 * well. nfsd will not use a dentry with this bit set, but will first 182 * endeavour to clear the bit either by discovering that it is connected, 183 * or by performing lookup operations. Any filesystem which supports 184 * nfsd_operations MUST have a lookup function which, if it finds a 185 * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that 186 * dentry into place and return that dentry rather than the passed one, 187 * typically using d_splice_alias. */ 188 189 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */ 190 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */ 191 192 #define DCACHE_CANT_MOUNT 0x00000100 193 #define DCACHE_GENOCIDE 0x00000200 194 #define DCACHE_SHRINK_LIST 0x00000400 195 196 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800 197 198 #define DCACHE_NFSFS_RENAMED 0x00001000 199 /* this dentry has been "silly renamed" and has to be deleted on the last 200 * dput() */ 201 #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */ 202 #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000 203 /* Parent inode is watched by some fsnotify listener */ 204 205 #define DCACHE_DENTRY_KILLED 0x00008000 206 207 #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */ 208 #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */ 209 #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */ 210 #define DCACHE_MANAGED_DENTRY \ 211 (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) 212 213 #define DCACHE_LRU_LIST 0x00080000 214 215 #define DCACHE_ENTRY_TYPE 0x00700000 216 #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry */ 217 #define DCACHE_DIRECTORY_TYPE 0x00100000 /* Normal directory */ 218 #define DCACHE_AUTODIR_TYPE 0x00200000 /* Lookupless directory (presumed automount) */ 219 #define DCACHE_SYMLINK_TYPE 0x00300000 /* Symlink */ 220 #define DCACHE_FILE_TYPE 0x00400000 /* Other file type */ 221 222 extern seqlock_t rename_lock; 223 224 static inline int dname_external(const struct dentry *dentry) 225 { 226 return dentry->d_name.name != dentry->d_iname; 227 } 228 229 /* 230 * These are the low-level FS interfaces to the dcache.. 231 */ 232 extern void d_instantiate(struct dentry *, struct inode *); 233 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); 234 extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); 235 extern int d_instantiate_no_diralias(struct dentry *, struct inode *); 236 extern void __d_drop(struct dentry *dentry); 237 extern void d_drop(struct dentry *dentry); 238 extern void d_delete(struct dentry *); 239 extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); 240 241 /* allocate/de-allocate */ 242 extern struct dentry * d_alloc(struct dentry *, const struct qstr *); 243 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *); 244 extern struct dentry * d_splice_alias(struct inode *, struct dentry *); 245 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); 246 extern struct dentry *d_find_any_alias(struct inode *inode); 247 extern struct dentry * d_obtain_alias(struct inode *); 248 extern void shrink_dcache_sb(struct super_block *); 249 extern void shrink_dcache_parent(struct dentry *); 250 extern void shrink_dcache_for_umount(struct super_block *); 251 extern int d_invalidate(struct dentry *); 252 253 /* only used at mount-time */ 254 extern struct dentry * d_make_root(struct inode *); 255 256 /* <clickety>-<click> the ramfs-type tree */ 257 extern void d_genocide(struct dentry *); 258 259 extern void d_tmpfile(struct dentry *, struct inode *); 260 261 extern struct dentry *d_find_alias(struct inode *); 262 extern void d_prune_aliases(struct inode *); 263 264 /* test whether we have any submounts in a subdir tree */ 265 extern int have_submounts(struct dentry *); 266 extern int check_submounts_and_drop(struct dentry *); 267 268 /* 269 * This adds the entry to the hash queues. 270 */ 271 extern void d_rehash(struct dentry *); 272 273 /** 274 * d_add - add dentry to hash queues 275 * @entry: dentry to add 276 * @inode: The inode to attach to this dentry 277 * 278 * This adds the entry to the hash queues and initializes @inode. 279 * The entry was actually filled in earlier during d_alloc(). 280 */ 281 282 static inline void d_add(struct dentry *entry, struct inode *inode) 283 { 284 d_instantiate(entry, inode); 285 d_rehash(entry); 286 } 287 288 /** 289 * d_add_unique - add dentry to hash queues without aliasing 290 * @entry: dentry to add 291 * @inode: The inode to attach to this dentry 292 * 293 * This adds the entry to the hash queues and initializes @inode. 294 * The entry was actually filled in earlier during d_alloc(). 295 */ 296 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) 297 { 298 struct dentry *res; 299 300 res = d_instantiate_unique(entry, inode); 301 d_rehash(res != NULL ? res : entry); 302 return res; 303 } 304 305 extern void dentry_update_name_case(struct dentry *, struct qstr *); 306 307 /* used for rename() and baskets */ 308 extern void d_move(struct dentry *, struct dentry *); 309 extern struct dentry *d_ancestor(struct dentry *, struct dentry *); 310 311 /* appendix may either be NULL or be used for transname suffixes */ 312 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *); 313 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); 314 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *); 315 extern struct dentry *__d_lookup_rcu(const struct dentry *parent, 316 const struct qstr *name, unsigned *seq); 317 318 static inline unsigned d_count(const struct dentry *dentry) 319 { 320 return dentry->d_lockref.count; 321 } 322 323 /* validate "insecure" dentry pointer */ 324 extern int d_validate(struct dentry *, struct dentry *); 325 326 /* 327 * helper function for dentry_operations.d_dname() members 328 */ 329 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); 330 extern char *simple_dname(struct dentry *, char *, int); 331 332 extern char *__d_path(const struct path *, const struct path *, char *, int); 333 extern char *d_absolute_path(const struct path *, char *, int); 334 extern char *d_path(const struct path *, char *, int); 335 extern char *dentry_path_raw(struct dentry *, char *, int); 336 extern char *dentry_path(struct dentry *, char *, int); 337 338 /* Allocation counts.. */ 339 340 /** 341 * dget, dget_dlock - get a reference to a dentry 342 * @dentry: dentry to get a reference to 343 * 344 * Given a dentry or %NULL pointer increment the reference count 345 * if appropriate and return the dentry. A dentry will not be 346 * destroyed when it has references. 347 */ 348 static inline struct dentry *dget_dlock(struct dentry *dentry) 349 { 350 if (dentry) 351 dentry->d_lockref.count++; 352 return dentry; 353 } 354 355 static inline struct dentry *dget(struct dentry *dentry) 356 { 357 if (dentry) 358 lockref_get(&dentry->d_lockref); 359 return dentry; 360 } 361 362 extern struct dentry *dget_parent(struct dentry *dentry); 363 364 /** 365 * d_unhashed - is dentry hashed 366 * @dentry: entry to check 367 * 368 * Returns true if the dentry passed is not currently hashed. 369 */ 370 371 static inline int d_unhashed(const struct dentry *dentry) 372 { 373 return hlist_bl_unhashed(&dentry->d_hash); 374 } 375 376 static inline int d_unlinked(const struct dentry *dentry) 377 { 378 return d_unhashed(dentry) && !IS_ROOT(dentry); 379 } 380 381 static inline int cant_mount(const struct dentry *dentry) 382 { 383 return (dentry->d_flags & DCACHE_CANT_MOUNT); 384 } 385 386 static inline void dont_mount(struct dentry *dentry) 387 { 388 spin_lock(&dentry->d_lock); 389 dentry->d_flags |= DCACHE_CANT_MOUNT; 390 spin_unlock(&dentry->d_lock); 391 } 392 393 extern void dput(struct dentry *); 394 395 static inline bool d_managed(const struct dentry *dentry) 396 { 397 return dentry->d_flags & DCACHE_MANAGED_DENTRY; 398 } 399 400 static inline bool d_mountpoint(const struct dentry *dentry) 401 { 402 return dentry->d_flags & DCACHE_MOUNTED; 403 } 404 405 /* 406 * Directory cache entry type accessor functions. 407 */ 408 static inline void __d_set_type(struct dentry *dentry, unsigned type) 409 { 410 dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type; 411 } 412 413 static inline void __d_clear_type(struct dentry *dentry) 414 { 415 __d_set_type(dentry, DCACHE_MISS_TYPE); 416 } 417 418 static inline void d_set_type(struct dentry *dentry, unsigned type) 419 { 420 spin_lock(&dentry->d_lock); 421 __d_set_type(dentry, type); 422 spin_unlock(&dentry->d_lock); 423 } 424 425 static inline unsigned __d_entry_type(const struct dentry *dentry) 426 { 427 return dentry->d_flags & DCACHE_ENTRY_TYPE; 428 } 429 430 static inline bool d_is_directory(const struct dentry *dentry) 431 { 432 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; 433 } 434 435 static inline bool d_is_autodir(const struct dentry *dentry) 436 { 437 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; 438 } 439 440 static inline bool d_is_symlink(const struct dentry *dentry) 441 { 442 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; 443 } 444 445 static inline bool d_is_file(const struct dentry *dentry) 446 { 447 return __d_entry_type(dentry) == DCACHE_FILE_TYPE; 448 } 449 450 static inline bool d_is_negative(const struct dentry *dentry) 451 { 452 return __d_entry_type(dentry) == DCACHE_MISS_TYPE; 453 } 454 455 static inline bool d_is_positive(const struct dentry *dentry) 456 { 457 return !d_is_negative(dentry); 458 } 459 460 extern int sysctl_vfs_cache_pressure; 461 462 static inline unsigned long vfs_pressure_ratio(unsigned long val) 463 { 464 return mult_frac(val, sysctl_vfs_cache_pressure, 100); 465 } 466 #endif /* __LINUX_DCACHE_H */ 467