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 #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8)) 33 #else 34 #define HASH_LEN_DECLARE u32 len; u32 hash; 35 #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8)) 36 #endif 37 38 /* 39 * "quick string" -- eases parameter passing, but more importantly 40 * saves "metadata" about the string (ie length and the hash). 41 * 42 * hash comes first so it snuggles against d_parent in the 43 * dentry. 44 */ 45 struct qstr { 46 union { 47 struct { 48 HASH_LEN_DECLARE; 49 }; 50 u64 hash_len; 51 }; 52 const unsigned char *name; 53 }; 54 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)) 59 60 struct dentry_stat_t { 61 long nr_dentry; 62 long nr_unused; 63 long age_limit; /* age in seconds */ 64 long want_pages; /* pages requested by system */ 65 long dummy[2]; 66 }; 67 extern struct dentry_stat_t dentry_stat; 68 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 72 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) 76 { 77 return (prevhash + (c << 4) + (c >> 4)) * 11; 78 } 79 80 /* 81 * Finally: cut down the number of bits to a int value (and try to avoid 82 * losing bits) 83 */ 84 static inline unsigned long end_name_hash(unsigned long hash) 85 { 86 return (unsigned int) hash; 87 } 88 89 /* Compute the hash for a name string. */ 90 extern unsigned int full_name_hash(const unsigned char *, unsigned int); 91 92 /* 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). 96 */ 97 #ifdef CONFIG_64BIT 98 # define DNAME_INLINE_LEN 32 /* 192 bytes */ 99 #else 100 # ifdef CONFIG_SMP 101 # define DNAME_INLINE_LEN 36 /* 128 bytes */ 102 # else 103 # define DNAME_INLINE_LEN 40 /* 128 bytes */ 104 # endif 105 #endif 106 107 #define d_lock d_lockref.lock 108 109 struct dentry { 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 */ 115 struct qstr d_name; 116 struct inode *d_inode; /* Where the name belongs to - NULL is 117 * negative */ 118 unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ 119 120 /* 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 */ 126 127 struct list_head d_lru; /* LRU list */ 128 /* 129 * d_child and d_rcu can share memory 130 */ 131 union { 132 struct list_head d_child; /* child of parent list */ 133 struct rcu_head d_rcu; 134 } d_u; 135 struct list_head d_subdirs; /* our children */ 136 struct hlist_node d_alias; /* inode alias list */ 137 }; 138 139 /* 140 * dentry->d_lock spinlock nesting subclasses: 141 * 142 * 0: normal 143 * 1: nested 144 */ 145 enum dentry_d_lock_class 146 { 147 DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ 148 DENTRY_D_LOCK_NESTED 149 }; 150 151 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; 165 166 /* 167 * Locking rules for dentry_operations callbacks are to be found in 168 * Documentation/filesystems/Locking. Keep it updated! 169 * 170 * FUrther descriptions are found in Documentation/filesystems/vfs.txt. 171 * Keep it updated too! 172 */ 173 174 /* 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 180 181 #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. */ 191 192 #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */ 193 #define DCACHE_RCUACCESS 0x00000080 /* Entry has ever been RCU-visible */ 194 195 #define DCACHE_CANT_MOUNT 0x00000100 196 #define DCACHE_GENOCIDE 0x00000200 197 #define DCACHE_SHRINK_LIST 0x00000400 198 199 #define DCACHE_OP_WEAK_REVALIDATE 0x00000800 200 201 #define DCACHE_NFSFS_RENAMED 0x00001000 202 /* this dentry has been "silly renamed" and has to be deleted on the last 203 * dput() */ 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 */ 207 208 #define DCACHE_DENTRY_KILLED 0x00008000 209 210 #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) 215 216 #define DCACHE_LRU_LIST 0x00080000 217 218 #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 */ 224 225 #define DCACHE_MAY_FREE 0x00800000 226 227 extern seqlock_t rename_lock; 228 229 static inline int dname_external(const struct dentry *dentry) 230 { 231 return dentry->d_name.name != dentry->d_iname; 232 } 233 234 /* 235 * These are the low-level FS interfaces to the dcache.. 236 */ 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); 245 246 /* 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 *); 258 259 /* only used at mount-time */ 260 extern struct dentry * d_make_root(struct inode *); 261 262 /* <clickety>-<click> the ramfs-type tree */ 263 extern void d_genocide(struct dentry *); 264 265 extern void d_tmpfile(struct dentry *, struct inode *); 266 267 extern struct dentry *d_find_alias(struct inode *); 268 extern void d_prune_aliases(struct inode *); 269 270 /* 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 *); 273 274 /* 275 * This adds the entry to the hash queues. 276 */ 277 extern void d_rehash(struct dentry *); 278 279 /** 280 * d_add - add dentry to hash queues 281 * @entry: dentry to add 282 * @inode: The inode to attach to this dentry 283 * 284 * This adds the entry to the hash queues and initializes @inode. 285 * The entry was actually filled in earlier during d_alloc(). 286 */ 287 288 static inline void d_add(struct dentry *entry, struct inode *inode) 289 { 290 d_instantiate(entry, inode); 291 d_rehash(entry); 292 } 293 294 /** 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 298 * 299 * This adds the entry to the hash queues and initializes @inode. 300 * The entry was actually filled in earlier during d_alloc(). 301 */ 302 static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) 303 { 304 struct dentry *res; 305 306 res = d_instantiate_unique(entry, inode); 307 d_rehash(res != NULL ? res : entry); 308 return res; 309 } 310 311 extern void dentry_update_name_case(struct dentry *, struct qstr *); 312 313 /* 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 *); 317 318 /* 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); 324 325 static inline unsigned d_count(const struct dentry *dentry) 326 { 327 return dentry->d_lockref.count; 328 } 329 330 /* validate "insecure" dentry pointer */ 331 extern int d_validate(struct dentry *, struct dentry *); 332 333 /* 334 * helper function for dentry_operations.d_dname() members 335 */ 336 extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); 337 extern char *simple_dname(struct dentry *, char *, int); 338 339 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); 344 345 /* Allocation counts.. */ 346 347 /** 348 * dget, dget_dlock - get a reference to a dentry 349 * @dentry: dentry to get a reference to 350 * 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. 354 */ 355 static inline struct dentry *dget_dlock(struct dentry *dentry) 356 { 357 if (dentry) 358 dentry->d_lockref.count++; 359 return dentry; 360 } 361 362 static inline struct dentry *dget(struct dentry *dentry) 363 { 364 if (dentry) 365 lockref_get(&dentry->d_lockref); 366 return dentry; 367 } 368 369 extern struct dentry *dget_parent(struct dentry *dentry); 370 371 /** 372 * d_unhashed - is dentry hashed 373 * @dentry: entry to check 374 * 375 * Returns true if the dentry passed is not currently hashed. 376 */ 377 378 static inline int d_unhashed(const struct dentry *dentry) 379 { 380 return hlist_bl_unhashed(&dentry->d_hash); 381 } 382 383 static inline int d_unlinked(const struct dentry *dentry) 384 { 385 return d_unhashed(dentry) && !IS_ROOT(dentry); 386 } 387 388 static inline int cant_mount(const struct dentry *dentry) 389 { 390 return (dentry->d_flags & DCACHE_CANT_MOUNT); 391 } 392 393 static inline void dont_mount(struct dentry *dentry) 394 { 395 spin_lock(&dentry->d_lock); 396 dentry->d_flags |= DCACHE_CANT_MOUNT; 397 spin_unlock(&dentry->d_lock); 398 } 399 400 extern void dput(struct dentry *); 401 402 static inline bool d_managed(const struct dentry *dentry) 403 { 404 return dentry->d_flags & DCACHE_MANAGED_DENTRY; 405 } 406 407 static inline bool d_mountpoint(const struct dentry *dentry) 408 { 409 return dentry->d_flags & DCACHE_MOUNTED; 410 } 411 412 /* 413 * Directory cache entry type accessor functions. 414 */ 415 static inline void __d_set_type(struct dentry *dentry, unsigned type) 416 { 417 dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type; 418 } 419 420 static inline void __d_clear_type(struct dentry *dentry) 421 { 422 __d_set_type(dentry, DCACHE_MISS_TYPE); 423 } 424 425 static inline void d_set_type(struct dentry *dentry, unsigned type) 426 { 427 spin_lock(&dentry->d_lock); 428 __d_set_type(dentry, type); 429 spin_unlock(&dentry->d_lock); 430 } 431 432 static inline unsigned __d_entry_type(const struct dentry *dentry) 433 { 434 return dentry->d_flags & DCACHE_ENTRY_TYPE; 435 } 436 437 static inline bool d_can_lookup(const struct dentry *dentry) 438 { 439 return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; 440 } 441 442 static inline bool d_is_autodir(const struct dentry *dentry) 443 { 444 return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; 445 } 446 447 static inline bool d_is_dir(const struct dentry *dentry) 448 { 449 return d_can_lookup(dentry) || d_is_autodir(dentry); 450 } 451 452 static inline bool d_is_symlink(const struct dentry *dentry) 453 { 454 return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; 455 } 456 457 static inline bool d_is_file(const struct dentry *dentry) 458 { 459 return __d_entry_type(dentry) == DCACHE_FILE_TYPE; 460 } 461 462 static inline bool d_is_negative(const struct dentry *dentry) 463 { 464 return __d_entry_type(dentry) == DCACHE_MISS_TYPE; 465 } 466 467 static inline bool d_is_positive(const struct dentry *dentry) 468 { 469 return !d_is_negative(dentry); 470 } 471 472 extern int sysctl_vfs_cache_pressure; 473 474 static inline unsigned long vfs_pressure_ratio(unsigned long val) 475 { 476 return mult_frac(val, sysctl_vfs_cache_pressure, 100); 477 } 478 #endif /* __LINUX_DCACHE_H */ 479