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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: 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: /* 128: * d_child and d_rcu can share memory 129: */ 130: union { 131: struct list_head d_child; /* child of parent list */ 132: struct rcu_head d_rcu; 133: } d_u; 134: struct list_head d_subdirs; /* our children */ 135: struct hlist_node d_alias; /* inode alias list */ 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: extern seqlock_t rename_lock; 225: 226: static inline int dname_external(const struct dentry *dentry) 227: { 228: return dentry->d_name.name != dentry->d_iname; 229: } 230: 231: /* 232: * These are the low-level FS interfaces to the dcache.. 233: */ 234: extern void d_instantiate(struct dentry *, struct inode *); 235: extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); 236: extern struct dentry * d_materialise_unique(struct dentry *, struct inode *); 237: extern int d_instantiate_no_diralias(struct dentry *, struct inode *); 238: extern void __d_drop(struct dentry *dentry); 239: extern void d_drop(struct dentry *dentry); 240: extern void d_delete(struct dentry *); 241: extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); 242: 243: /* allocate/de-allocate */ 244: extern struct dentry * d_alloc(struct dentry *, const struct qstr *); 245: extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *); 246: extern struct dentry * d_splice_alias(struct inode *, struct dentry *); 247: extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); 248: extern struct dentry *d_find_any_alias(struct inode *inode); 249: extern struct dentry * d_obtain_alias(struct inode *); 250: extern void shrink_dcache_sb(struct super_block *); 251: extern void shrink_dcache_parent(struct dentry *); 252: extern void shrink_dcache_for_umount(struct super_block *); 253: extern int d_invalidate(struct dentry *); 254: 255: /* only used at mount-time */ 256: extern struct dentry * d_make_root(struct inode *); 257: 258: /* <clickety>-<click> the ramfs-type tree */ 259: extern void d_genocide(struct dentry *); 260: 261: extern void d_tmpfile(struct dentry *, struct inode *); 262: 263: extern struct dentry *d_find_alias(struct inode *); 264: extern void d_prune_aliases(struct inode *); 265: 266: /* test whether we have any submounts in a subdir tree */ 267: extern int have_submounts(struct dentry *); 268: extern int check_submounts_and_drop(struct dentry *); 269: 270: /* 271: * This adds the entry to the hash queues. 272: */ 273: extern void d_rehash(struct dentry *); 274: 275: /** 276: * d_add - add dentry to hash queues 277: * @entry: dentry to add 278: * @inode: The inode to attach to this dentry 279: * 280: * This adds the entry to the hash queues and initializes @inode. 281: * The entry was actually filled in earlier during d_alloc(). 282: */ 283: 284: static inline void d_add(struct dentry *entry, struct inode *inode) 285: { 286: d_instantiate(entry, inode); 287: d_rehash(entry); 288: } 289: 290: /** 291: * d_add_unique - add dentry to hash queues without aliasing 292: * @entry: dentry to add 293: * @inode: The inode to attach to this dentry 294: * 295: * This adds the entry to the hash queues and initializes @inode. 296: * The entry was actually filled in earlier during d_alloc(). 297: */ 298: static inline struct dentry *d_add_unique(struct dentry *entry, struct inode *inode) 299: { 300: struct dentry *res; 301: 302: res = d_instantiate_unique(entry, inode); 303: d_rehash(res != NULL ? res : entry); 304: return res; 305: } 306: 307: extern void dentry_update_name_case(struct dentry *, struct qstr *); 308: 309: /* used for rename() and baskets */ 310: extern void d_move(struct dentry *, struct dentry *); 311: extern struct dentry *d_ancestor(struct dentry *, struct dentry *); 312: 313: /* appendix may either be NULL or be used for transname suffixes */ 314: extern struct dentry *d_lookup(const struct dentry *, const struct qstr *); 315: extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); 316: extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *); 317: extern struct dentry *__d_lookup_rcu(const struct dentry *parent, 318: const struct qstr *name, unsigned *seq); 319: 320: static inline unsigned d_count(const struct dentry *dentry) 321: { 322: return dentry->d_lockref.count; 323: } 324: 325: /* validate "insecure" dentry pointer */ 326: extern int d_validate(struct dentry *, struct dentry *); 327: 328: /* 329: * helper function for dentry_operations.d_dname() members 330: */ 331: extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); 332: extern char *simple_dname(struct dentry *, char *, int); 333: 334: extern char *__d_path(const struct path *, const struct path *, char *, int); 335: extern char *d_absolute_path(const struct path *, char *, int); 336: extern char *d_path(const struct path *, char *, int); 337: extern char *dentry_path_raw(struct dentry *, char *, int); 338: extern char *dentry_path(struct dentry *, char *, int); 339: 340: /* Allocation counts.. */ 341: 342: /** 343: * dget, dget_dlock - get a reference to a dentry 344: * @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 348: * destroyed when it has references. 349: */ 350: static inline struct dentry *dget_dlock(struct dentry *dentry) 351: { 352: if (dentry) 353: dentry->d_lockref.count++; 354: return dentry; 355: } 356: 357: static inline struct dentry *dget(struct dentry *dentry) 358: { 359: if (dentry) 360: lockref_get(&dentry->d_lockref); 361: return dentry; 362: } 363: 364: extern struct dentry *dget_parent(struct dentry *dentry); 365: 366: /** 367: * d_unhashed - is dentry hashed 368: * @dentry: entry to check 369: * 370: * Returns true if the dentry passed is not currently hashed. 371: */ 372: 373: static inline int d_unhashed(const struct dentry *dentry) 374: { 375: return hlist_bl_unhashed(&dentry->d_hash); 376: } 377: 378: static inline int d_unlinked(const struct dentry *dentry) 379: { 380: return d_unhashed(dentry) && !IS_ROOT(dentry); 381: } 382: 383: static inline int cant_mount(const struct dentry *dentry) 384: { 385: return (dentry->d_flags & DCACHE_CANT_MOUNT); 386: } 387: 388: static inline void dont_mount(struct dentry *dentry) 389: { 390: spin_lock(&dentry->d_lock); 391: dentry->d_flags |= DCACHE_CANT_MOUNT; 392: spin_unlock(&dentry->d_lock); 393: } 394: 395: extern void dput(struct dentry *); 396: 397: static inline bool d_managed(const struct dentry *dentry) 398: { 399: return dentry->d_flags & DCACHE_MANAGED_DENTRY; 400: } 401: 402: static inline bool d_mountpoint(const struct dentry *dentry) 403: { 404: return dentry->d_flags & DCACHE_MOUNTED; 405: } 406: 407: /* 408: * Directory cache entry type accessor functions. 409: */ 410: static inline void __d_set_type(struct dentry *dentry, unsigned type) 411: { 412: dentry->d_flags = (dentry->d_flags & ~DCACHE_ENTRY_TYPE) | type; 413: } 414: 415: static inline void __d_clear_type(struct dentry *dentry) 416: { 417: __d_set_type(dentry, DCACHE_MISS_TYPE); 418: } 419: 420: static inline void d_set_type(struct dentry *dentry, unsigned type) 421: { 422: spin_lock(&dentry->d_lock); 423: __d_set_type(dentry, type); 424: spin_unlock(&dentry->d_lock); 425: } 426: 427: static inline unsigned __d_entry_type(const struct dentry *dentry) 428: { 429: return dentry->d_flags & DCACHE_ENTRY_TYPE; 430: } 431: 432: static inline bool d_is_directory(const struct dentry *dentry) 433: { 434: return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; 435: } 436: 437: static inline bool d_is_autodir(const struct dentry *dentry) 438: { 439: return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; 440: } 441: 442: static inline bool d_is_symlink(const struct dentry *dentry) 443: { 444: return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; 445: } 446: 447: static inline bool d_is_file(const struct dentry *dentry) 448: { 449: return __d_entry_type(dentry) == DCACHE_FILE_TYPE; 450: } 451: 452: static inline bool d_is_negative(const struct dentry *dentry) 453: { 454: return __d_entry_type(dentry) == DCACHE_MISS_TYPE; 455: } 456: 457: static inline bool d_is_positive(const struct dentry *dentry) 458: { 459: return !d_is_negative(dentry); 460: } 461: 462: extern int sysctl_vfs_cache_pressure; 463: 464: static inline unsigned long vfs_pressure_ratio(unsigned long val) 465: { 466: return mult_frac(val, sysctl_vfs_cache_pressure, 100); 467: } 468: #endif /* __LINUX_DCACHE_H */ 469: