| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef __LINUX_DCACHE_H |
| 3 | #define __LINUX_DCACHE_H |
| 4 | |
| 5 | #include <linux/atomic.h> |
| 6 | #include <linux/list.h> |
| 7 | #include <linux/math.h> |
| 8 | #include <linux/rculist.h> |
| 9 | #include <linux/rculist_bl.h> |
| 10 | #include <linux/spinlock.h> |
| 11 | #include <linux/seqlock.h> |
| 12 | #include <linux/cache.h> |
| 13 | #include <linux/rcupdate.h> |
| 14 | #include <linux/lockref.h> |
| 15 | #include <linux/stringhash.h> |
| 16 | #include <linux/wait.h> |
| 17 | |
| 18 | struct path; |
| 19 | struct file; |
| 20 | struct vfsmount; |
| 21 | |
| 22 | /* |
| 23 | * linux/include/linux/dcache.h |
| 24 | * |
| 25 | * Dirent cache data structures |
| 26 | * |
| 27 | * (C) Copyright 1997 Thomas Schoebel-Theuer, |
| 28 | * with heavy changes by Linus Torvalds |
| 29 | */ |
| 30 | |
| 31 | #define IS_ROOT(x) ((x) == (x)->d_parent) |
| 32 | |
| 33 | /* The hash is always the low bits of hash_len */ |
| 34 | #ifdef __LITTLE_ENDIAN |
| 35 | #define HASH_LEN_DECLARE u32 hash; u32 len |
| 36 | #define bytemask_from_count(cnt) (~(~0ul << (cnt)*8)) |
| 37 | #else |
| 38 | #define HASH_LEN_DECLARE u32 len; u32 hash |
| 39 | #define bytemask_from_count(cnt) (~(~0ul >> (cnt)*8)) |
| 40 | #endif |
| 41 | |
| 42 | /* |
| 43 | * "quick string" -- eases parameter passing, but more importantly |
| 44 | * saves "metadata" about the string (ie length and the hash). |
| 45 | * |
| 46 | * hash comes first so it snuggles against d_parent in the |
| 47 | * dentry. |
| 48 | */ |
| 49 | struct qstr { |
| 50 | union { |
| 51 | struct { |
| 52 | HASH_LEN_DECLARE; |
| 53 | }; |
| 54 | u64 hash_len; |
| 55 | }; |
| 56 | const unsigned char *name; |
| 57 | }; |
| 58 | |
| 59 | #define QSTR_INIT(n,l) { { { .len = l } }, .name = n } |
| 60 | |
| 61 | extern const struct qstr empty_name; |
| 62 | extern const struct qstr slash_name; |
| 63 | extern const struct qstr dotdot_name; |
| 64 | |
| 65 | /* |
| 66 | * Try to keep struct dentry aligned on 64 byte cachelines (this will |
| 67 | * give reasonable cacheline footprint with larger lines without the |
| 68 | * large memory footprint increase). |
| 69 | */ |
| 70 | #ifdef CONFIG_64BIT |
| 71 | # define DNAME_INLINE_LEN 32 /* 192 bytes */ |
| 72 | #else |
| 73 | # ifdef CONFIG_SMP |
| 74 | # define DNAME_INLINE_LEN 36 /* 128 bytes */ |
| 75 | # else |
| 76 | # define DNAME_INLINE_LEN 40 /* 128 bytes */ |
| 77 | # endif |
| 78 | #endif |
| 79 | |
| 80 | #define d_lock d_lockref.lock |
| 81 | |
| 82 | struct dentry { |
| 83 | /* RCU lookup touched fields */ |
| 84 | unsigned int d_flags; /* protected by d_lock */ |
| 85 | seqcount_spinlock_t d_seq; /* per dentry seqlock */ |
| 86 | struct hlist_bl_node d_hash; /* lookup hash list */ |
| 87 | struct dentry *d_parent; /* parent directory */ |
| 88 | struct qstr d_name; |
| 89 | struct inode *d_inode; /* Where the name belongs to - NULL is |
| 90 | * negative */ |
| 91 | unsigned char d_iname[DNAME_INLINE_LEN]; /* small names */ |
| 92 | |
| 93 | /* Ref lookup also touches following */ |
| 94 | struct lockref d_lockref; /* per-dentry lock and refcount */ |
| 95 | const struct dentry_operations *d_op; |
| 96 | struct super_block *d_sb; /* The root of the dentry tree */ |
| 97 | unsigned long d_time; /* used by d_revalidate */ |
| 98 | void *d_fsdata; /* fs-specific data */ |
| 99 | |
| 100 | union { |
| 101 | struct list_head d_lru; /* LRU list */ |
| 102 | wait_queue_head_t *d_wait; /* in-lookup ones only */ |
| 103 | }; |
| 104 | struct list_head d_child; /* child of parent list */ |
| 105 | struct list_head d_subdirs; /* our children */ |
| 106 | /* |
| 107 | * d_alias and d_rcu can share memory |
| 108 | */ |
| 109 | union { |
| 110 | struct hlist_node d_alias; /* inode alias list */ |
| 111 | struct hlist_bl_node d_in_lookup_hash; /* only for in-lookup ones */ |
| 112 | struct rcu_head d_rcu; |
| 113 | } d_u; |
| 114 | } __randomize_layout; |
| 115 | |
| 116 | /* |
| 117 | * dentry->d_lock spinlock nesting subclasses: |
| 118 | * |
| 119 | * 0: normal |
| 120 | * 1: nested |
| 121 | */ |
| 122 | enum dentry_d_lock_class |
| 123 | { |
| 124 | DENTRY_D_LOCK_NORMAL, /* implicitly used by plain spin_lock() APIs. */ |
| 125 | DENTRY_D_LOCK_NESTED |
| 126 | }; |
| 127 | |
| 128 | struct dentry_operations { |
| 129 | int (*d_revalidate)(struct dentry *, unsigned int); |
| 130 | int (*d_weak_revalidate)(struct dentry *, unsigned int); |
| 131 | int (*d_hash)(const struct dentry *, struct qstr *); |
| 132 | int (*d_compare)(const struct dentry *, |
| 133 | unsigned int, const char *, const struct qstr *); |
| 134 | int (*d_delete)(const struct dentry *); |
| 135 | int (*d_init)(struct dentry *); |
| 136 | void (*d_release)(struct dentry *); |
| 137 | void (*d_prune)(struct dentry *); |
| 138 | void (*d_iput)(struct dentry *, struct inode *); |
| 139 | char *(*d_dname)(struct dentry *, char *, int); |
| 140 | struct vfsmount *(*d_automount)(struct path *); |
| 141 | int (*d_manage)(const struct path *, bool); |
| 142 | struct dentry *(*d_real)(struct dentry *, const struct inode *); |
| 143 | } ____cacheline_aligned; |
| 144 | |
| 145 | /* |
| 146 | * Locking rules for dentry_operations callbacks are to be found in |
| 147 | * Documentation/filesystems/locking.rst. Keep it updated! |
| 148 | * |
| 149 | * FUrther descriptions are found in Documentation/filesystems/vfs.rst. |
| 150 | * Keep it updated too! |
| 151 | */ |
| 152 | |
| 153 | /* d_flags entries */ |
| 154 | #define DCACHE_OP_HASH 0x00000001 |
| 155 | #define DCACHE_OP_COMPARE 0x00000002 |
| 156 | #define DCACHE_OP_REVALIDATE 0x00000004 |
| 157 | #define DCACHE_OP_DELETE 0x00000008 |
| 158 | #define DCACHE_OP_PRUNE 0x00000010 |
| 159 | |
| 160 | #define DCACHE_DISCONNECTED 0x00000020 |
| 161 | /* This dentry is possibly not currently connected to the dcache tree, in |
| 162 | * which case its parent will either be itself, or will have this flag as |
| 163 | * well. nfsd will not use a dentry with this bit set, but will first |
| 164 | * endeavour to clear the bit either by discovering that it is connected, |
| 165 | * or by performing lookup operations. Any filesystem which supports |
| 166 | * nfsd_operations MUST have a lookup function which, if it finds a |
| 167 | * directory inode with a DCACHE_DISCONNECTED dentry, will d_move that |
| 168 | * dentry into place and return that dentry rather than the passed one, |
| 169 | * typically using d_splice_alias. */ |
| 170 | |
| 171 | #define DCACHE_REFERENCED 0x00000040 /* Recently used, don't discard. */ |
| 172 | |
| 173 | #define DCACHE_DONTCACHE 0x00000080 /* Purge from memory on final dput() */ |
| 174 | |
| 175 | #define DCACHE_CANT_MOUNT 0x00000100 |
| 176 | #define DCACHE_GENOCIDE 0x00000200 |
| 177 | #define DCACHE_SHRINK_LIST 0x00000400 |
| 178 | |
| 179 | #define DCACHE_OP_WEAK_REVALIDATE 0x00000800 |
| 180 | |
| 181 | #define DCACHE_NFSFS_RENAMED 0x00001000 |
| 182 | /* this dentry has been "silly renamed" and has to be deleted on the last |
| 183 | * dput() */ |
| 184 | #define DCACHE_COOKIE 0x00002000 /* For use by dcookie subsystem */ |
| 185 | #define DCACHE_FSNOTIFY_PARENT_WATCHED 0x00004000 |
| 186 | /* Parent inode is watched by some fsnotify listener */ |
| 187 | |
| 188 | #define DCACHE_DENTRY_KILLED 0x00008000 |
| 189 | |
| 190 | #define DCACHE_MOUNTED 0x00010000 /* is a mountpoint */ |
| 191 | #define DCACHE_NEED_AUTOMOUNT 0x00020000 /* handle automount on this dir */ |
| 192 | #define DCACHE_MANAGE_TRANSIT 0x00040000 /* manage transit from this dirent */ |
| 193 | #define DCACHE_MANAGED_DENTRY \ |
| 194 | (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT) |
| 195 | |
| 196 | #define DCACHE_LRU_LIST 0x00080000 |
| 197 | |
| 198 | #define DCACHE_ENTRY_TYPE 0x00700000 |
| 199 | #define DCACHE_MISS_TYPE 0x00000000 /* Negative dentry (maybe fallthru to nowhere) */ |
| 200 | #define DCACHE_WHITEOUT_TYPE 0x00100000 /* Whiteout dentry (stop pathwalk) */ |
| 201 | #define DCACHE_DIRECTORY_TYPE 0x00200000 /* Normal directory */ |
| 202 | #define DCACHE_AUTODIR_TYPE 0x00300000 /* Lookupless directory (presumed automount) */ |
| 203 | #define DCACHE_REGULAR_TYPE 0x00400000 /* Regular file type (or fallthru to such) */ |
| 204 | #define DCACHE_SPECIAL_TYPE 0x00500000 /* Other file type (or fallthru to such) */ |
| 205 | #define DCACHE_SYMLINK_TYPE 0x00600000 /* Symlink (or fallthru to such) */ |
| 206 | |
| 207 | #define DCACHE_MAY_FREE 0x00800000 |
| 208 | #define DCACHE_FALLTHRU 0x01000000 /* Fall through to lower layer */ |
| 209 | #define DCACHE_NOKEY_NAME 0x02000000 /* Encrypted name encoded without key */ |
| 210 | #define DCACHE_OP_REAL 0x04000000 |
| 211 | |
| 212 | #define DCACHE_PAR_LOOKUP 0x10000000 /* being looked up (with parent locked shared) */ |
| 213 | #define DCACHE_DENTRY_CURSOR 0x20000000 |
| 214 | #define DCACHE_NORCU 0x40000000 /* No RCU delay for freeing */ |
| 215 | |
| 216 | extern seqlock_t rename_lock; |
| 217 | |
| 218 | /* |
| 219 | * These are the low-level FS interfaces to the dcache.. |
| 220 | */ |
| 221 | extern void d_instantiate(struct dentry *, struct inode *); |
| 222 | extern void d_instantiate_new(struct dentry *, struct inode *); |
| 223 | extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); |
| 224 | extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *); |
| 225 | extern void __d_drop(struct dentry *dentry); |
| 226 | extern void d_drop(struct dentry *dentry); |
| 227 | extern void d_delete(struct dentry *); |
| 228 | extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op); |
| 229 | |
| 230 | /* allocate/de-allocate */ |
| 231 | extern struct dentry * d_alloc(struct dentry *, const struct qstr *); |
| 232 | extern struct dentry * d_alloc_anon(struct super_block *); |
| 233 | extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *, |
| 234 | wait_queue_head_t *); |
| 235 | extern struct dentry * d_splice_alias(struct inode *, struct dentry *); |
| 236 | extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *); |
| 237 | extern bool d_same_name(const struct dentry *dentry, const struct dentry *parent, |
| 238 | const struct qstr *name); |
| 239 | extern struct dentry * d_exact_alias(struct dentry *, struct inode *); |
| 240 | extern struct dentry *d_find_any_alias(struct inode *inode); |
| 241 | extern struct dentry * d_obtain_alias(struct inode *); |
| 242 | extern struct dentry * d_obtain_root(struct inode *); |
| 243 | extern void shrink_dcache_sb(struct super_block *); |
| 244 | extern void shrink_dcache_parent(struct dentry *); |
| 245 | extern void shrink_dcache_for_umount(struct super_block *); |
| 246 | extern void d_invalidate(struct dentry *); |
| 247 | |
| 248 | /* only used at mount-time */ |
| 249 | extern struct dentry * d_make_root(struct inode *); |
| 250 | |
| 251 | /* <clickety>-<click> the ramfs-type tree */ |
| 252 | extern void d_genocide(struct dentry *); |
| 253 | |
| 254 | extern void d_tmpfile(struct file *, struct inode *); |
| 255 | |
| 256 | extern struct dentry *d_find_alias(struct inode *); |
| 257 | extern void d_prune_aliases(struct inode *); |
| 258 | |
| 259 | extern struct dentry *d_find_alias_rcu(struct inode *); |
| 260 | |
| 261 | /* test whether we have any submounts in a subdir tree */ |
| 262 | extern int path_has_submounts(const struct path *); |
| 263 | |
| 264 | /* |
| 265 | * This adds the entry to the hash queues. |
| 266 | */ |
| 267 | extern void d_rehash(struct dentry *); |
| 268 | |
| 269 | extern void d_add(struct dentry *, struct inode *); |
| 270 | |
| 271 | /* used for rename() and baskets */ |
| 272 | extern void d_move(struct dentry *, struct dentry *); |
| 273 | extern void d_exchange(struct dentry *, struct dentry *); |
| 274 | extern struct dentry *d_ancestor(struct dentry *, struct dentry *); |
| 275 | |
| 276 | /* appendix may either be NULL or be used for transname suffixes */ |
| 277 | extern struct dentry *d_lookup(const struct dentry *, const struct qstr *); |
| 278 | extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *); |
| 279 | extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *); |
| 280 | extern struct dentry *__d_lookup_rcu(const struct dentry *parent, |
| 281 | const struct qstr *name, unsigned *seq); |
| 282 | |
| 283 | static inline unsigned d_count(const struct dentry *dentry) |
| 284 | { |
| 285 | return dentry->d_lockref.count; |
| 286 | } |
| 287 | |
| 288 | /* |
| 289 | * helper function for dentry_operations.d_dname() members |
| 290 | */ |
| 291 | extern __printf(3, 4) |
| 292 | char *dynamic_dname(char *, int, const char *, ...); |
| 293 | |
| 294 | extern char *__d_path(const struct path *, const struct path *, char *, int); |
| 295 | extern char *d_absolute_path(const struct path *, char *, int); |
| 296 | extern char *d_path(const struct path *, char *, int); |
| 297 | extern char *dentry_path_raw(const struct dentry *, char *, int); |
| 298 | extern char *dentry_path(const struct dentry *, char *, int); |
| 299 | |
| 300 | /* Allocation counts.. */ |
| 301 | |
| 302 | /** |
| 303 | * dget, dget_dlock - get a reference to a dentry |
| 304 | * @dentry: dentry to get a reference to |
| 305 | * |
| 306 | * Given a dentry or %NULL pointer increment the reference count |
| 307 | * if appropriate and return the dentry. A dentry will not be |
| 308 | * destroyed when it has references. |
| 309 | */ |
| 310 | static inline struct dentry *dget_dlock(struct dentry *dentry) |
| 311 | { |
| 312 | if (dentry) |
| 313 | dentry->d_lockref.count++; |
| 314 | return dentry; |
| 315 | } |
| 316 | |
| 317 | static inline struct dentry *dget(struct dentry *dentry) |
| 318 | { |
| 319 | if (dentry) |
| 320 | lockref_get(&dentry->d_lockref); |
| 321 | return dentry; |
| 322 | } |
| 323 | |
| 324 | extern struct dentry *dget_parent(struct dentry *dentry); |
| 325 | |
| 326 | /** |
| 327 | * d_unhashed - is dentry hashed |
| 328 | * @dentry: entry to check |
| 329 | * |
| 330 | * Returns true if the dentry passed is not currently hashed. |
| 331 | */ |
| 332 | |
| 333 | static inline int d_unhashed(const struct dentry *dentry) |
| 334 | { |
| 335 | return hlist_bl_unhashed(&dentry->d_hash); |
| 336 | } |
| 337 | |
| 338 | static inline int d_unlinked(const struct dentry *dentry) |
| 339 | { |
| 340 | return d_unhashed(dentry) && !IS_ROOT(dentry); |
| 341 | } |
| 342 | |
| 343 | static inline int cant_mount(const struct dentry *dentry) |
| 344 | { |
| 345 | return (dentry->d_flags & DCACHE_CANT_MOUNT); |
| 346 | } |
| 347 | |
| 348 | static inline void dont_mount(struct dentry *dentry) |
| 349 | { |
| 350 | spin_lock(&dentry->d_lock); |
| 351 | dentry->d_flags |= DCACHE_CANT_MOUNT; |
| 352 | spin_unlock(&dentry->d_lock); |
| 353 | } |
| 354 | |
| 355 | extern void __d_lookup_unhash_wake(struct dentry *dentry); |
| 356 | |
| 357 | static inline int d_in_lookup(const struct dentry *dentry) |
| 358 | { |
| 359 | return dentry->d_flags & DCACHE_PAR_LOOKUP; |
| 360 | } |
| 361 | |
| 362 | static inline void d_lookup_done(struct dentry *dentry) |
| 363 | { |
| 364 | if (unlikely(d_in_lookup(dentry))) |
| 365 | __d_lookup_unhash_wake(dentry); |
| 366 | } |
| 367 | |
| 368 | extern void dput(struct dentry *); |
| 369 | |
| 370 | static inline bool d_managed(const struct dentry *dentry) |
| 371 | { |
| 372 | return dentry->d_flags & DCACHE_MANAGED_DENTRY; |
| 373 | } |
| 374 | |
| 375 | static inline bool d_mountpoint(const struct dentry *dentry) |
| 376 | { |
| 377 | return dentry->d_flags & DCACHE_MOUNTED; |
| 378 | } |
| 379 | |
| 380 | /* |
| 381 | * Directory cache entry type accessor functions. |
| 382 | */ |
| 383 | static inline unsigned __d_entry_type(const struct dentry *dentry) |
| 384 | { |
| 385 | return dentry->d_flags & DCACHE_ENTRY_TYPE; |
| 386 | } |
| 387 | |
| 388 | static inline bool d_is_miss(const struct dentry *dentry) |
| 389 | { |
| 390 | return __d_entry_type(dentry) == DCACHE_MISS_TYPE; |
| 391 | } |
| 392 | |
| 393 | static inline bool d_is_whiteout(const struct dentry *dentry) |
| 394 | { |
| 395 | return __d_entry_type(dentry) == DCACHE_WHITEOUT_TYPE; |
| 396 | } |
| 397 | |
| 398 | static inline bool d_can_lookup(const struct dentry *dentry) |
| 399 | { |
| 400 | return __d_entry_type(dentry) == DCACHE_DIRECTORY_TYPE; |
| 401 | } |
| 402 | |
| 403 | static inline bool d_is_autodir(const struct dentry *dentry) |
| 404 | { |
| 405 | return __d_entry_type(dentry) == DCACHE_AUTODIR_TYPE; |
| 406 | } |
| 407 | |
| 408 | static inline bool d_is_dir(const struct dentry *dentry) |
| 409 | { |
| 410 | return d_can_lookup(dentry) || d_is_autodir(dentry); |
| 411 | } |
| 412 | |
| 413 | static inline bool d_is_symlink(const struct dentry *dentry) |
| 414 | { |
| 415 | return __d_entry_type(dentry) == DCACHE_SYMLINK_TYPE; |
| 416 | } |
| 417 | |
| 418 | static inline bool d_is_reg(const struct dentry *dentry) |
| 419 | { |
| 420 | return __d_entry_type(dentry) == DCACHE_REGULAR_TYPE; |
| 421 | } |
| 422 | |
| 423 | static inline bool d_is_special(const struct dentry *dentry) |
| 424 | { |
| 425 | return __d_entry_type(dentry) == DCACHE_SPECIAL_TYPE; |
| 426 | } |
| 427 | |
| 428 | static inline bool d_is_file(const struct dentry *dentry) |
| 429 | { |
| 430 | return d_is_reg(dentry) || d_is_special(dentry); |
| 431 | } |
| 432 | |
| 433 | static inline bool d_is_negative(const struct dentry *dentry) |
| 434 | { |
| 435 | // TODO: check d_is_whiteout(dentry) also. |
| 436 | return d_is_miss(dentry); |
| 437 | } |
| 438 | |
| 439 | static inline bool d_flags_negative(unsigned flags) |
| 440 | { |
| 441 | return (flags & DCACHE_ENTRY_TYPE) == DCACHE_MISS_TYPE; |
| 442 | } |
| 443 | |
| 444 | static inline bool d_is_positive(const struct dentry *dentry) |
| 445 | { |
| 446 | return !d_is_negative(dentry); |
| 447 | } |
| 448 | |
| 449 | /** |
| 450 | * d_really_is_negative - Determine if a dentry is really negative (ignoring fallthroughs) |
| 451 | * @dentry: The dentry in question |
| 452 | * |
| 453 | * Returns true if the dentry represents either an absent name or a name that |
| 454 | * doesn't map to an inode (ie. ->d_inode is NULL). The dentry could represent |
| 455 | * a true miss, a whiteout that isn't represented by a 0,0 chardev or a |
| 456 | * fallthrough marker in an opaque directory. |
| 457 | * |
| 458 | * Note! (1) This should be used *only* by a filesystem to examine its own |
| 459 | * dentries. It should not be used to look at some other filesystem's |
| 460 | * dentries. (2) It should also be used in combination with d_inode() to get |
| 461 | * the inode. (3) The dentry may have something attached to ->d_lower and the |
| 462 | * type field of the flags may be set to something other than miss or whiteout. |
| 463 | */ |
| 464 | static inline bool d_really_is_negative(const struct dentry *dentry) |
| 465 | { |
| 466 | return dentry->d_inode == NULL; |
| 467 | } |
| 468 | |
| 469 | /** |
| 470 | * d_really_is_positive - Determine if a dentry is really positive (ignoring fallthroughs) |
| 471 | * @dentry: The dentry in question |
| 472 | * |
| 473 | * Returns true if the dentry represents a name that maps to an inode |
| 474 | * (ie. ->d_inode is not NULL). The dentry might still represent a whiteout if |
| 475 | * that is represented on medium as a 0,0 chardev. |
| 476 | * |
| 477 | * Note! (1) This should be used *only* by a filesystem to examine its own |
| 478 | * dentries. It should not be used to look at some other filesystem's |
| 479 | * dentries. (2) It should also be used in combination with d_inode() to get |
| 480 | * the inode. |
| 481 | */ |
| 482 | static inline bool d_really_is_positive(const struct dentry *dentry) |
| 483 | { |
| 484 | return dentry->d_inode != NULL; |
| 485 | } |
| 486 | |
| 487 | static inline int simple_positive(const struct dentry *dentry) |
| 488 | { |
| 489 | return d_really_is_positive(dentry) && !d_unhashed(dentry); |
| 490 | } |
| 491 | |
| 492 | extern void d_set_fallthru(struct dentry *dentry); |
| 493 | |
| 494 | static inline bool d_is_fallthru(const struct dentry *dentry) |
| 495 | { |
| 496 | return dentry->d_flags & DCACHE_FALLTHRU; |
| 497 | } |
| 498 | |
| 499 | |
| 500 | extern int sysctl_vfs_cache_pressure; |
| 501 | |
| 502 | static inline unsigned long vfs_pressure_ratio(unsigned long val) |
| 503 | { |
| 504 | return mult_frac(val, sysctl_vfs_cache_pressure, 100); |
| 505 | } |
| 506 | |
| 507 | /** |
| 508 | * d_inode - Get the actual inode of this dentry |
| 509 | * @dentry: The dentry to query |
| 510 | * |
| 511 | * This is the helper normal filesystems should use to get at their own inodes |
| 512 | * in their own dentries and ignore the layering superimposed upon them. |
| 513 | */ |
| 514 | static inline struct inode *d_inode(const struct dentry *dentry) |
| 515 | { |
| 516 | return dentry->d_inode; |
| 517 | } |
| 518 | |
| 519 | /** |
| 520 | * d_inode_rcu - Get the actual inode of this dentry with READ_ONCE() |
| 521 | * @dentry: The dentry to query |
| 522 | * |
| 523 | * This is the helper normal filesystems should use to get at their own inodes |
| 524 | * in their own dentries and ignore the layering superimposed upon them. |
| 525 | */ |
| 526 | static inline struct inode *d_inode_rcu(const struct dentry *dentry) |
| 527 | { |
| 528 | return READ_ONCE(dentry->d_inode); |
| 529 | } |
| 530 | |
| 531 | /** |
| 532 | * d_backing_inode - Get upper or lower inode we should be using |
| 533 | * @upper: The upper layer |
| 534 | * |
| 535 | * This is the helper that should be used to get at the inode that will be used |
| 536 | * if this dentry were to be opened as a file. The inode may be on the upper |
| 537 | * dentry or it may be on a lower dentry pinned by the upper. |
| 538 | * |
| 539 | * Normal filesystems should not use this to access their own inodes. |
| 540 | */ |
| 541 | static inline struct inode *d_backing_inode(const struct dentry *upper) |
| 542 | { |
| 543 | struct inode *inode = upper->d_inode; |
| 544 | |
| 545 | return inode; |
| 546 | } |
| 547 | |
| 548 | /** |
| 549 | * d_backing_dentry - Get upper or lower dentry we should be using |
| 550 | * @upper: The upper layer |
| 551 | * |
| 552 | * This is the helper that should be used to get the dentry of the inode that |
| 553 | * will be used if this dentry were opened as a file. It may be the upper |
| 554 | * dentry or it may be a lower dentry pinned by the upper. |
| 555 | * |
| 556 | * Normal filesystems should not use this to access their own dentries. |
| 557 | */ |
| 558 | static inline struct dentry *d_backing_dentry(struct dentry *upper) |
| 559 | { |
| 560 | return upper; |
| 561 | } |
| 562 | |
| 563 | /** |
| 564 | * d_real - Return the real dentry |
| 565 | * @dentry: the dentry to query |
| 566 | * @inode: inode to select the dentry from multiple layers (can be NULL) |
| 567 | * |
| 568 | * If dentry is on a union/overlay, then return the underlying, real dentry. |
| 569 | * Otherwise return the dentry itself. |
| 570 | * |
| 571 | * See also: Documentation/filesystems/vfs.rst |
| 572 | */ |
| 573 | static inline struct dentry *d_real(struct dentry *dentry, |
| 574 | const struct inode *inode) |
| 575 | { |
| 576 | if (unlikely(dentry->d_flags & DCACHE_OP_REAL)) |
| 577 | return dentry->d_op->d_real(dentry, inode); |
| 578 | else |
| 579 | return dentry; |
| 580 | } |
| 581 | |
| 582 | /** |
| 583 | * d_real_inode - Return the real inode |
| 584 | * @dentry: The dentry to query |
| 585 | * |
| 586 | * If dentry is on a union/overlay, then return the underlying, real inode. |
| 587 | * Otherwise return d_inode(). |
| 588 | */ |
| 589 | static inline struct inode *d_real_inode(const struct dentry *dentry) |
| 590 | { |
| 591 | /* This usage of d_real() results in const dentry */ |
| 592 | return d_backing_inode(d_real((struct dentry *) dentry, NULL)); |
| 593 | } |
| 594 | |
| 595 | struct name_snapshot { |
| 596 | struct qstr name; |
| 597 | unsigned char inline_name[DNAME_INLINE_LEN]; |
| 598 | }; |
| 599 | void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *); |
| 600 | void release_dentry_name_snapshot(struct name_snapshot *); |
| 601 | |
| 602 | #endif /* __LINUX_DCACHE_H */ |