| 1 | /* |
| 2 | * fs/dcache.c |
| 3 | * |
| 4 | * Complete reimplementation |
| 5 | * (C) 1997 Thomas Schoebel-Theuer, |
| 6 | * with heavy changes by Linus Torvalds |
| 7 | */ |
| 8 | |
| 9 | /* |
| 10 | * Notes on the allocation strategy: |
| 11 | * |
| 12 | * The dcache is a master of the icache - whenever a dcache entry |
| 13 | * exists, the inode will always exist. "iput()" is done either when |
| 14 | * the dcache entry is deleted or garbage collected. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/syscalls.h> |
| 18 | #include <linux/string.h> |
| 19 | #include <linux/mm.h> |
| 20 | #include <linux/fs.h> |
| 21 | #include <linux/fsnotify.h> |
| 22 | #include <linux/slab.h> |
| 23 | #include <linux/init.h> |
| 24 | #include <linux/hash.h> |
| 25 | #include <linux/cache.h> |
| 26 | #include <linux/export.h> |
| 27 | #include <linux/mount.h> |
| 28 | #include <linux/file.h> |
| 29 | #include <asm/uaccess.h> |
| 30 | #include <linux/security.h> |
| 31 | #include <linux/seqlock.h> |
| 32 | #include <linux/swap.h> |
| 33 | #include <linux/bootmem.h> |
| 34 | #include <linux/fs_struct.h> |
| 35 | #include <linux/hardirq.h> |
| 36 | #include <linux/bit_spinlock.h> |
| 37 | #include <linux/rculist_bl.h> |
| 38 | #include <linux/prefetch.h> |
| 39 | #include <linux/ratelimit.h> |
| 40 | #include <linux/list_lru.h> |
| 41 | #include "internal.h" |
| 42 | #include "mount.h" |
| 43 | |
| 44 | /* |
| 45 | * Usage: |
| 46 | * dcache->d_inode->i_lock protects: |
| 47 | * - i_dentry, d_u.d_alias, d_inode of aliases |
| 48 | * dcache_hash_bucket lock protects: |
| 49 | * - the dcache hash table |
| 50 | * s_anon bl list spinlock protects: |
| 51 | * - the s_anon list (see __d_drop) |
| 52 | * dentry->d_sb->s_dentry_lru_lock protects: |
| 53 | * - the dcache lru lists and counters |
| 54 | * d_lock protects: |
| 55 | * - d_flags |
| 56 | * - d_name |
| 57 | * - d_lru |
| 58 | * - d_count |
| 59 | * - d_unhashed() |
| 60 | * - d_parent and d_subdirs |
| 61 | * - childrens' d_child and d_parent |
| 62 | * - d_u.d_alias, d_inode |
| 63 | * |
| 64 | * Ordering: |
| 65 | * dentry->d_inode->i_lock |
| 66 | * dentry->d_lock |
| 67 | * dentry->d_sb->s_dentry_lru_lock |
| 68 | * dcache_hash_bucket lock |
| 69 | * s_anon lock |
| 70 | * |
| 71 | * If there is an ancestor relationship: |
| 72 | * dentry->d_parent->...->d_parent->d_lock |
| 73 | * ... |
| 74 | * dentry->d_parent->d_lock |
| 75 | * dentry->d_lock |
| 76 | * |
| 77 | * If no ancestor relationship: |
| 78 | * if (dentry1 < dentry2) |
| 79 | * dentry1->d_lock |
| 80 | * dentry2->d_lock |
| 81 | */ |
| 82 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
| 83 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
| 84 | |
| 85 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
| 86 | |
| 87 | EXPORT_SYMBOL(rename_lock); |
| 88 | |
| 89 | static struct kmem_cache *dentry_cache __read_mostly; |
| 90 | |
| 91 | /* |
| 92 | * This is the single most critical data structure when it comes |
| 93 | * to the dcache: the hashtable for lookups. Somebody should try |
| 94 | * to make this good - I've just made it work. |
| 95 | * |
| 96 | * This hash-function tries to avoid losing too many bits of hash |
| 97 | * information, yet avoid using a prime hash-size or similar. |
| 98 | */ |
| 99 | |
| 100 | static unsigned int d_hash_mask __read_mostly; |
| 101 | static unsigned int d_hash_shift __read_mostly; |
| 102 | |
| 103 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
| 104 | |
| 105 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
| 106 | unsigned int hash) |
| 107 | { |
| 108 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
| 109 | return dentry_hashtable + hash_32(hash, d_hash_shift); |
| 110 | } |
| 111 | |
| 112 | /* Statistics gathering. */ |
| 113 | struct dentry_stat_t dentry_stat = { |
| 114 | .age_limit = 45, |
| 115 | }; |
| 116 | |
| 117 | static DEFINE_PER_CPU(long, nr_dentry); |
| 118 | static DEFINE_PER_CPU(long, nr_dentry_unused); |
| 119 | |
| 120 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
| 121 | |
| 122 | /* |
| 123 | * Here we resort to our own counters instead of using generic per-cpu counters |
| 124 | * for consistency with what the vfs inode code does. We are expected to harvest |
| 125 | * better code and performance by having our own specialized counters. |
| 126 | * |
| 127 | * Please note that the loop is done over all possible CPUs, not over all online |
| 128 | * CPUs. The reason for this is that we don't want to play games with CPUs going |
| 129 | * on and off. If one of them goes off, we will just keep their counters. |
| 130 | * |
| 131 | * glommer: See cffbc8a for details, and if you ever intend to change this, |
| 132 | * please update all vfs counters to match. |
| 133 | */ |
| 134 | static long get_nr_dentry(void) |
| 135 | { |
| 136 | int i; |
| 137 | long sum = 0; |
| 138 | for_each_possible_cpu(i) |
| 139 | sum += per_cpu(nr_dentry, i); |
| 140 | return sum < 0 ? 0 : sum; |
| 141 | } |
| 142 | |
| 143 | static long get_nr_dentry_unused(void) |
| 144 | { |
| 145 | int i; |
| 146 | long sum = 0; |
| 147 | for_each_possible_cpu(i) |
| 148 | sum += per_cpu(nr_dentry_unused, i); |
| 149 | return sum < 0 ? 0 : sum; |
| 150 | } |
| 151 | |
| 152 | int proc_nr_dentry(struct ctl_table *table, int write, void __user *buffer, |
| 153 | size_t *lenp, loff_t *ppos) |
| 154 | { |
| 155 | dentry_stat.nr_dentry = get_nr_dentry(); |
| 156 | dentry_stat.nr_unused = get_nr_dentry_unused(); |
| 157 | return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
| 158 | } |
| 159 | #endif |
| 160 | |
| 161 | /* |
| 162 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. |
| 163 | * The strings are both count bytes long, and count is non-zero. |
| 164 | */ |
| 165 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
| 166 | |
| 167 | #include <asm/word-at-a-time.h> |
| 168 | /* |
| 169 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a |
| 170 | * aligned allocation for this particular component. We don't |
| 171 | * strictly need the load_unaligned_zeropad() safety, but it |
| 172 | * doesn't hurt either. |
| 173 | * |
| 174 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do |
| 175 | * need the careful unaligned handling. |
| 176 | */ |
| 177 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
| 178 | { |
| 179 | unsigned long a,b,mask; |
| 180 | |
| 181 | for (;;) { |
| 182 | a = *(unsigned long *)cs; |
| 183 | b = load_unaligned_zeropad(ct); |
| 184 | if (tcount < sizeof(unsigned long)) |
| 185 | break; |
| 186 | if (unlikely(a != b)) |
| 187 | return 1; |
| 188 | cs += sizeof(unsigned long); |
| 189 | ct += sizeof(unsigned long); |
| 190 | tcount -= sizeof(unsigned long); |
| 191 | if (!tcount) |
| 192 | return 0; |
| 193 | } |
| 194 | mask = bytemask_from_count(tcount); |
| 195 | return unlikely(!!((a ^ b) & mask)); |
| 196 | } |
| 197 | |
| 198 | #else |
| 199 | |
| 200 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
| 201 | { |
| 202 | do { |
| 203 | if (*cs != *ct) |
| 204 | return 1; |
| 205 | cs++; |
| 206 | ct++; |
| 207 | tcount--; |
| 208 | } while (tcount); |
| 209 | return 0; |
| 210 | } |
| 211 | |
| 212 | #endif |
| 213 | |
| 214 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
| 215 | { |
| 216 | const unsigned char *cs; |
| 217 | /* |
| 218 | * Be careful about RCU walk racing with rename: |
| 219 | * use ACCESS_ONCE to fetch the name pointer. |
| 220 | * |
| 221 | * NOTE! Even if a rename will mean that the length |
| 222 | * was not loaded atomically, we don't care. The |
| 223 | * RCU walk will check the sequence count eventually, |
| 224 | * and catch it. And we won't overrun the buffer, |
| 225 | * because we're reading the name pointer atomically, |
| 226 | * and a dentry name is guaranteed to be properly |
| 227 | * terminated with a NUL byte. |
| 228 | * |
| 229 | * End result: even if 'len' is wrong, we'll exit |
| 230 | * early because the data cannot match (there can |
| 231 | * be no NUL in the ct/tcount data) |
| 232 | */ |
| 233 | cs = ACCESS_ONCE(dentry->d_name.name); |
| 234 | smp_read_barrier_depends(); |
| 235 | return dentry_string_cmp(cs, ct, tcount); |
| 236 | } |
| 237 | |
| 238 | struct external_name { |
| 239 | union { |
| 240 | atomic_t count; |
| 241 | struct rcu_head head; |
| 242 | } u; |
| 243 | unsigned char name[]; |
| 244 | }; |
| 245 | |
| 246 | static inline struct external_name *external_name(struct dentry *dentry) |
| 247 | { |
| 248 | return container_of(dentry->d_name.name, struct external_name, name[0]); |
| 249 | } |
| 250 | |
| 251 | static void __d_free(struct rcu_head *head) |
| 252 | { |
| 253 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
| 254 | |
| 255 | kmem_cache_free(dentry_cache, dentry); |
| 256 | } |
| 257 | |
| 258 | static void __d_free_external(struct rcu_head *head) |
| 259 | { |
| 260 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
| 261 | kfree(external_name(dentry)); |
| 262 | kmem_cache_free(dentry_cache, dentry); |
| 263 | } |
| 264 | |
| 265 | static inline int dname_external(const struct dentry *dentry) |
| 266 | { |
| 267 | return dentry->d_name.name != dentry->d_iname; |
| 268 | } |
| 269 | |
| 270 | static void dentry_free(struct dentry *dentry) |
| 271 | { |
| 272 | WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias)); |
| 273 | if (unlikely(dname_external(dentry))) { |
| 274 | struct external_name *p = external_name(dentry); |
| 275 | if (likely(atomic_dec_and_test(&p->u.count))) { |
| 276 | call_rcu(&dentry->d_u.d_rcu, __d_free_external); |
| 277 | return; |
| 278 | } |
| 279 | } |
| 280 | /* if dentry was never visible to RCU, immediate free is OK */ |
| 281 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) |
| 282 | __d_free(&dentry->d_u.d_rcu); |
| 283 | else |
| 284 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
| 285 | } |
| 286 | |
| 287 | /** |
| 288 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups |
| 289 | * @dentry: the target dentry |
| 290 | * After this call, in-progress rcu-walk path lookup will fail. This |
| 291 | * should be called after unhashing, and after changing d_inode (if |
| 292 | * the dentry has not already been unhashed). |
| 293 | */ |
| 294 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) |
| 295 | { |
| 296 | assert_spin_locked(&dentry->d_lock); |
| 297 | /* Go through a barrier */ |
| 298 | write_seqcount_barrier(&dentry->d_seq); |
| 299 | } |
| 300 | |
| 301 | /* |
| 302 | * Release the dentry's inode, using the filesystem |
| 303 | * d_iput() operation if defined. Dentry has no refcount |
| 304 | * and is unhashed. |
| 305 | */ |
| 306 | static void dentry_iput(struct dentry * dentry) |
| 307 | __releases(dentry->d_lock) |
| 308 | __releases(dentry->d_inode->i_lock) |
| 309 | { |
| 310 | struct inode *inode = dentry->d_inode; |
| 311 | if (inode) { |
| 312 | dentry->d_inode = NULL; |
| 313 | hlist_del_init(&dentry->d_u.d_alias); |
| 314 | spin_unlock(&dentry->d_lock); |
| 315 | spin_unlock(&inode->i_lock); |
| 316 | if (!inode->i_nlink) |
| 317 | fsnotify_inoderemove(inode); |
| 318 | if (dentry->d_op && dentry->d_op->d_iput) |
| 319 | dentry->d_op->d_iput(dentry, inode); |
| 320 | else |
| 321 | iput(inode); |
| 322 | } else { |
| 323 | spin_unlock(&dentry->d_lock); |
| 324 | } |
| 325 | } |
| 326 | |
| 327 | /* |
| 328 | * Release the dentry's inode, using the filesystem |
| 329 | * d_iput() operation if defined. dentry remains in-use. |
| 330 | */ |
| 331 | static void dentry_unlink_inode(struct dentry * dentry) |
| 332 | __releases(dentry->d_lock) |
| 333 | __releases(dentry->d_inode->i_lock) |
| 334 | { |
| 335 | struct inode *inode = dentry->d_inode; |
| 336 | __d_clear_type(dentry); |
| 337 | dentry->d_inode = NULL; |
| 338 | hlist_del_init(&dentry->d_u.d_alias); |
| 339 | dentry_rcuwalk_barrier(dentry); |
| 340 | spin_unlock(&dentry->d_lock); |
| 341 | spin_unlock(&inode->i_lock); |
| 342 | if (!inode->i_nlink) |
| 343 | fsnotify_inoderemove(inode); |
| 344 | if (dentry->d_op && dentry->d_op->d_iput) |
| 345 | dentry->d_op->d_iput(dentry, inode); |
| 346 | else |
| 347 | iput(inode); |
| 348 | } |
| 349 | |
| 350 | /* |
| 351 | * The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry |
| 352 | * is in use - which includes both the "real" per-superblock |
| 353 | * LRU list _and_ the DCACHE_SHRINK_LIST use. |
| 354 | * |
| 355 | * The DCACHE_SHRINK_LIST bit is set whenever the dentry is |
| 356 | * on the shrink list (ie not on the superblock LRU list). |
| 357 | * |
| 358 | * The per-cpu "nr_dentry_unused" counters are updated with |
| 359 | * the DCACHE_LRU_LIST bit. |
| 360 | * |
| 361 | * These helper functions make sure we always follow the |
| 362 | * rules. d_lock must be held by the caller. |
| 363 | */ |
| 364 | #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) |
| 365 | static void d_lru_add(struct dentry *dentry) |
| 366 | { |
| 367 | D_FLAG_VERIFY(dentry, 0); |
| 368 | dentry->d_flags |= DCACHE_LRU_LIST; |
| 369 | this_cpu_inc(nr_dentry_unused); |
| 370 | WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); |
| 371 | } |
| 372 | |
| 373 | static void d_lru_del(struct dentry *dentry) |
| 374 | { |
| 375 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 376 | dentry->d_flags &= ~DCACHE_LRU_LIST; |
| 377 | this_cpu_dec(nr_dentry_unused); |
| 378 | WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); |
| 379 | } |
| 380 | |
| 381 | static void d_shrink_del(struct dentry *dentry) |
| 382 | { |
| 383 | D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); |
| 384 | list_del_init(&dentry->d_lru); |
| 385 | dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); |
| 386 | this_cpu_dec(nr_dentry_unused); |
| 387 | } |
| 388 | |
| 389 | static void d_shrink_add(struct dentry *dentry, struct list_head *list) |
| 390 | { |
| 391 | D_FLAG_VERIFY(dentry, 0); |
| 392 | list_add(&dentry->d_lru, list); |
| 393 | dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; |
| 394 | this_cpu_inc(nr_dentry_unused); |
| 395 | } |
| 396 | |
| 397 | /* |
| 398 | * These can only be called under the global LRU lock, ie during the |
| 399 | * callback for freeing the LRU list. "isolate" removes it from the |
| 400 | * LRU lists entirely, while shrink_move moves it to the indicated |
| 401 | * private list. |
| 402 | */ |
| 403 | static void d_lru_isolate(struct dentry *dentry) |
| 404 | { |
| 405 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 406 | dentry->d_flags &= ~DCACHE_LRU_LIST; |
| 407 | this_cpu_dec(nr_dentry_unused); |
| 408 | list_del_init(&dentry->d_lru); |
| 409 | } |
| 410 | |
| 411 | static void d_lru_shrink_move(struct dentry *dentry, struct list_head *list) |
| 412 | { |
| 413 | D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); |
| 414 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
| 415 | list_move_tail(&dentry->d_lru, list); |
| 416 | } |
| 417 | |
| 418 | /* |
| 419 | * dentry_lru_(add|del)_list) must be called with d_lock held. |
| 420 | */ |
| 421 | static void dentry_lru_add(struct dentry *dentry) |
| 422 | { |
| 423 | if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) |
| 424 | d_lru_add(dentry); |
| 425 | } |
| 426 | |
| 427 | /** |
| 428 | * d_drop - drop a dentry |
| 429 | * @dentry: dentry to drop |
| 430 | * |
| 431 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't |
| 432 | * be found through a VFS lookup any more. Note that this is different from |
| 433 | * deleting the dentry - d_delete will try to mark the dentry negative if |
| 434 | * possible, giving a successful _negative_ lookup, while d_drop will |
| 435 | * just make the cache lookup fail. |
| 436 | * |
| 437 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some |
| 438 | * reason (NFS timeouts or autofs deletes). |
| 439 | * |
| 440 | * __d_drop requires dentry->d_lock. |
| 441 | */ |
| 442 | void __d_drop(struct dentry *dentry) |
| 443 | { |
| 444 | if (!d_unhashed(dentry)) { |
| 445 | struct hlist_bl_head *b; |
| 446 | /* |
| 447 | * Hashed dentries are normally on the dentry hashtable, |
| 448 | * with the exception of those newly allocated by |
| 449 | * d_obtain_alias, which are always IS_ROOT: |
| 450 | */ |
| 451 | if (unlikely(IS_ROOT(dentry))) |
| 452 | b = &dentry->d_sb->s_anon; |
| 453 | else |
| 454 | b = d_hash(dentry->d_parent, dentry->d_name.hash); |
| 455 | |
| 456 | hlist_bl_lock(b); |
| 457 | __hlist_bl_del(&dentry->d_hash); |
| 458 | dentry->d_hash.pprev = NULL; |
| 459 | hlist_bl_unlock(b); |
| 460 | dentry_rcuwalk_barrier(dentry); |
| 461 | } |
| 462 | } |
| 463 | EXPORT_SYMBOL(__d_drop); |
| 464 | |
| 465 | void d_drop(struct dentry *dentry) |
| 466 | { |
| 467 | spin_lock(&dentry->d_lock); |
| 468 | __d_drop(dentry); |
| 469 | spin_unlock(&dentry->d_lock); |
| 470 | } |
| 471 | EXPORT_SYMBOL(d_drop); |
| 472 | |
| 473 | static void __dentry_kill(struct dentry *dentry) |
| 474 | { |
| 475 | struct dentry *parent = NULL; |
| 476 | bool can_free = true; |
| 477 | if (!IS_ROOT(dentry)) |
| 478 | parent = dentry->d_parent; |
| 479 | |
| 480 | /* |
| 481 | * The dentry is now unrecoverably dead to the world. |
| 482 | */ |
| 483 | lockref_mark_dead(&dentry->d_lockref); |
| 484 | |
| 485 | /* |
| 486 | * inform the fs via d_prune that this dentry is about to be |
| 487 | * unhashed and destroyed. |
| 488 | */ |
| 489 | if (dentry->d_flags & DCACHE_OP_PRUNE) |
| 490 | dentry->d_op->d_prune(dentry); |
| 491 | |
| 492 | if (dentry->d_flags & DCACHE_LRU_LIST) { |
| 493 | if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) |
| 494 | d_lru_del(dentry); |
| 495 | } |
| 496 | /* if it was on the hash then remove it */ |
| 497 | __d_drop(dentry); |
| 498 | __list_del_entry(&dentry->d_child); |
| 499 | /* |
| 500 | * Inform d_walk() that we are no longer attached to the |
| 501 | * dentry tree |
| 502 | */ |
| 503 | dentry->d_flags |= DCACHE_DENTRY_KILLED; |
| 504 | if (parent) |
| 505 | spin_unlock(&parent->d_lock); |
| 506 | dentry_iput(dentry); |
| 507 | /* |
| 508 | * dentry_iput drops the locks, at which point nobody (except |
| 509 | * transient RCU lookups) can reach this dentry. |
| 510 | */ |
| 511 | BUG_ON((int)dentry->d_lockref.count > 0); |
| 512 | this_cpu_dec(nr_dentry); |
| 513 | if (dentry->d_op && dentry->d_op->d_release) |
| 514 | dentry->d_op->d_release(dentry); |
| 515 | |
| 516 | spin_lock(&dentry->d_lock); |
| 517 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
| 518 | dentry->d_flags |= DCACHE_MAY_FREE; |
| 519 | can_free = false; |
| 520 | } |
| 521 | spin_unlock(&dentry->d_lock); |
| 522 | if (likely(can_free)) |
| 523 | dentry_free(dentry); |
| 524 | } |
| 525 | |
| 526 | /* |
| 527 | * Finish off a dentry we've decided to kill. |
| 528 | * dentry->d_lock must be held, returns with it unlocked. |
| 529 | * If ref is non-zero, then decrement the refcount too. |
| 530 | * Returns dentry requiring refcount drop, or NULL if we're done. |
| 531 | */ |
| 532 | static struct dentry *dentry_kill(struct dentry *dentry) |
| 533 | __releases(dentry->d_lock) |
| 534 | { |
| 535 | struct inode *inode = dentry->d_inode; |
| 536 | struct dentry *parent = NULL; |
| 537 | |
| 538 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) |
| 539 | goto failed; |
| 540 | |
| 541 | if (!IS_ROOT(dentry)) { |
| 542 | parent = dentry->d_parent; |
| 543 | if (unlikely(!spin_trylock(&parent->d_lock))) { |
| 544 | if (inode) |
| 545 | spin_unlock(&inode->i_lock); |
| 546 | goto failed; |
| 547 | } |
| 548 | } |
| 549 | |
| 550 | __dentry_kill(dentry); |
| 551 | return parent; |
| 552 | |
| 553 | failed: |
| 554 | spin_unlock(&dentry->d_lock); |
| 555 | cpu_relax(); |
| 556 | return dentry; /* try again with same dentry */ |
| 557 | } |
| 558 | |
| 559 | static inline struct dentry *lock_parent(struct dentry *dentry) |
| 560 | { |
| 561 | struct dentry *parent = dentry->d_parent; |
| 562 | if (IS_ROOT(dentry)) |
| 563 | return NULL; |
| 564 | if (unlikely((int)dentry->d_lockref.count < 0)) |
| 565 | return NULL; |
| 566 | if (likely(spin_trylock(&parent->d_lock))) |
| 567 | return parent; |
| 568 | rcu_read_lock(); |
| 569 | spin_unlock(&dentry->d_lock); |
| 570 | again: |
| 571 | parent = ACCESS_ONCE(dentry->d_parent); |
| 572 | spin_lock(&parent->d_lock); |
| 573 | /* |
| 574 | * We can't blindly lock dentry until we are sure |
| 575 | * that we won't violate the locking order. |
| 576 | * Any changes of dentry->d_parent must have |
| 577 | * been done with parent->d_lock held, so |
| 578 | * spin_lock() above is enough of a barrier |
| 579 | * for checking if it's still our child. |
| 580 | */ |
| 581 | if (unlikely(parent != dentry->d_parent)) { |
| 582 | spin_unlock(&parent->d_lock); |
| 583 | goto again; |
| 584 | } |
| 585 | rcu_read_unlock(); |
| 586 | if (parent != dentry) |
| 587 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| 588 | else |
| 589 | parent = NULL; |
| 590 | return parent; |
| 591 | } |
| 592 | |
| 593 | /* |
| 594 | * This is dput |
| 595 | * |
| 596 | * This is complicated by the fact that we do not want to put |
| 597 | * dentries that are no longer on any hash chain on the unused |
| 598 | * list: we'd much rather just get rid of them immediately. |
| 599 | * |
| 600 | * However, that implies that we have to traverse the dentry |
| 601 | * tree upwards to the parents which might _also_ now be |
| 602 | * scheduled for deletion (it may have been only waiting for |
| 603 | * its last child to go away). |
| 604 | * |
| 605 | * This tail recursion is done by hand as we don't want to depend |
| 606 | * on the compiler to always get this right (gcc generally doesn't). |
| 607 | * Real recursion would eat up our stack space. |
| 608 | */ |
| 609 | |
| 610 | /* |
| 611 | * dput - release a dentry |
| 612 | * @dentry: dentry to release |
| 613 | * |
| 614 | * Release a dentry. This will drop the usage count and if appropriate |
| 615 | * call the dentry unlink method as well as removing it from the queues and |
| 616 | * releasing its resources. If the parent dentries were scheduled for release |
| 617 | * they too may now get deleted. |
| 618 | */ |
| 619 | void dput(struct dentry *dentry) |
| 620 | { |
| 621 | if (unlikely(!dentry)) |
| 622 | return; |
| 623 | |
| 624 | repeat: |
| 625 | if (lockref_put_or_lock(&dentry->d_lockref)) |
| 626 | return; |
| 627 | |
| 628 | /* Unreachable? Get rid of it */ |
| 629 | if (unlikely(d_unhashed(dentry))) |
| 630 | goto kill_it; |
| 631 | |
| 632 | if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { |
| 633 | if (dentry->d_op->d_delete(dentry)) |
| 634 | goto kill_it; |
| 635 | } |
| 636 | |
| 637 | if (!(dentry->d_flags & DCACHE_REFERENCED)) |
| 638 | dentry->d_flags |= DCACHE_REFERENCED; |
| 639 | dentry_lru_add(dentry); |
| 640 | |
| 641 | dentry->d_lockref.count--; |
| 642 | spin_unlock(&dentry->d_lock); |
| 643 | return; |
| 644 | |
| 645 | kill_it: |
| 646 | dentry = dentry_kill(dentry); |
| 647 | if (dentry) |
| 648 | goto repeat; |
| 649 | } |
| 650 | EXPORT_SYMBOL(dput); |
| 651 | |
| 652 | |
| 653 | /* This must be called with d_lock held */ |
| 654 | static inline void __dget_dlock(struct dentry *dentry) |
| 655 | { |
| 656 | dentry->d_lockref.count++; |
| 657 | } |
| 658 | |
| 659 | static inline void __dget(struct dentry *dentry) |
| 660 | { |
| 661 | lockref_get(&dentry->d_lockref); |
| 662 | } |
| 663 | |
| 664 | struct dentry *dget_parent(struct dentry *dentry) |
| 665 | { |
| 666 | int gotref; |
| 667 | struct dentry *ret; |
| 668 | |
| 669 | /* |
| 670 | * Do optimistic parent lookup without any |
| 671 | * locking. |
| 672 | */ |
| 673 | rcu_read_lock(); |
| 674 | ret = ACCESS_ONCE(dentry->d_parent); |
| 675 | gotref = lockref_get_not_zero(&ret->d_lockref); |
| 676 | rcu_read_unlock(); |
| 677 | if (likely(gotref)) { |
| 678 | if (likely(ret == ACCESS_ONCE(dentry->d_parent))) |
| 679 | return ret; |
| 680 | dput(ret); |
| 681 | } |
| 682 | |
| 683 | repeat: |
| 684 | /* |
| 685 | * Don't need rcu_dereference because we re-check it was correct under |
| 686 | * the lock. |
| 687 | */ |
| 688 | rcu_read_lock(); |
| 689 | ret = dentry->d_parent; |
| 690 | spin_lock(&ret->d_lock); |
| 691 | if (unlikely(ret != dentry->d_parent)) { |
| 692 | spin_unlock(&ret->d_lock); |
| 693 | rcu_read_unlock(); |
| 694 | goto repeat; |
| 695 | } |
| 696 | rcu_read_unlock(); |
| 697 | BUG_ON(!ret->d_lockref.count); |
| 698 | ret->d_lockref.count++; |
| 699 | spin_unlock(&ret->d_lock); |
| 700 | return ret; |
| 701 | } |
| 702 | EXPORT_SYMBOL(dget_parent); |
| 703 | |
| 704 | /** |
| 705 | * d_find_alias - grab a hashed alias of inode |
| 706 | * @inode: inode in question |
| 707 | * |
| 708 | * If inode has a hashed alias, or is a directory and has any alias, |
| 709 | * acquire the reference to alias and return it. Otherwise return NULL. |
| 710 | * Notice that if inode is a directory there can be only one alias and |
| 711 | * it can be unhashed only if it has no children, or if it is the root |
| 712 | * of a filesystem, or if the directory was renamed and d_revalidate |
| 713 | * was the first vfs operation to notice. |
| 714 | * |
| 715 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
| 716 | * any other hashed alias over that one. |
| 717 | */ |
| 718 | static struct dentry *__d_find_alias(struct inode *inode) |
| 719 | { |
| 720 | struct dentry *alias, *discon_alias; |
| 721 | |
| 722 | again: |
| 723 | discon_alias = NULL; |
| 724 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
| 725 | spin_lock(&alias->d_lock); |
| 726 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
| 727 | if (IS_ROOT(alias) && |
| 728 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
| 729 | discon_alias = alias; |
| 730 | } else { |
| 731 | __dget_dlock(alias); |
| 732 | spin_unlock(&alias->d_lock); |
| 733 | return alias; |
| 734 | } |
| 735 | } |
| 736 | spin_unlock(&alias->d_lock); |
| 737 | } |
| 738 | if (discon_alias) { |
| 739 | alias = discon_alias; |
| 740 | spin_lock(&alias->d_lock); |
| 741 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
| 742 | __dget_dlock(alias); |
| 743 | spin_unlock(&alias->d_lock); |
| 744 | return alias; |
| 745 | } |
| 746 | spin_unlock(&alias->d_lock); |
| 747 | goto again; |
| 748 | } |
| 749 | return NULL; |
| 750 | } |
| 751 | |
| 752 | struct dentry *d_find_alias(struct inode *inode) |
| 753 | { |
| 754 | struct dentry *de = NULL; |
| 755 | |
| 756 | if (!hlist_empty(&inode->i_dentry)) { |
| 757 | spin_lock(&inode->i_lock); |
| 758 | de = __d_find_alias(inode); |
| 759 | spin_unlock(&inode->i_lock); |
| 760 | } |
| 761 | return de; |
| 762 | } |
| 763 | EXPORT_SYMBOL(d_find_alias); |
| 764 | |
| 765 | /* |
| 766 | * Try to kill dentries associated with this inode. |
| 767 | * WARNING: you must own a reference to inode. |
| 768 | */ |
| 769 | void d_prune_aliases(struct inode *inode) |
| 770 | { |
| 771 | struct dentry *dentry; |
| 772 | restart: |
| 773 | spin_lock(&inode->i_lock); |
| 774 | hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
| 775 | spin_lock(&dentry->d_lock); |
| 776 | if (!dentry->d_lockref.count) { |
| 777 | struct dentry *parent = lock_parent(dentry); |
| 778 | if (likely(!dentry->d_lockref.count)) { |
| 779 | __dentry_kill(dentry); |
| 780 | dput(parent); |
| 781 | goto restart; |
| 782 | } |
| 783 | if (parent) |
| 784 | spin_unlock(&parent->d_lock); |
| 785 | } |
| 786 | spin_unlock(&dentry->d_lock); |
| 787 | } |
| 788 | spin_unlock(&inode->i_lock); |
| 789 | } |
| 790 | EXPORT_SYMBOL(d_prune_aliases); |
| 791 | |
| 792 | static void shrink_dentry_list(struct list_head *list) |
| 793 | { |
| 794 | struct dentry *dentry, *parent; |
| 795 | |
| 796 | while (!list_empty(list)) { |
| 797 | struct inode *inode; |
| 798 | dentry = list_entry(list->prev, struct dentry, d_lru); |
| 799 | spin_lock(&dentry->d_lock); |
| 800 | parent = lock_parent(dentry); |
| 801 | |
| 802 | /* |
| 803 | * The dispose list is isolated and dentries are not accounted |
| 804 | * to the LRU here, so we can simply remove it from the list |
| 805 | * here regardless of whether it is referenced or not. |
| 806 | */ |
| 807 | d_shrink_del(dentry); |
| 808 | |
| 809 | /* |
| 810 | * We found an inuse dentry which was not removed from |
| 811 | * the LRU because of laziness during lookup. Do not free it. |
| 812 | */ |
| 813 | if ((int)dentry->d_lockref.count > 0) { |
| 814 | spin_unlock(&dentry->d_lock); |
| 815 | if (parent) |
| 816 | spin_unlock(&parent->d_lock); |
| 817 | continue; |
| 818 | } |
| 819 | |
| 820 | |
| 821 | if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) { |
| 822 | bool can_free = dentry->d_flags & DCACHE_MAY_FREE; |
| 823 | spin_unlock(&dentry->d_lock); |
| 824 | if (parent) |
| 825 | spin_unlock(&parent->d_lock); |
| 826 | if (can_free) |
| 827 | dentry_free(dentry); |
| 828 | continue; |
| 829 | } |
| 830 | |
| 831 | inode = dentry->d_inode; |
| 832 | if (inode && unlikely(!spin_trylock(&inode->i_lock))) { |
| 833 | d_shrink_add(dentry, list); |
| 834 | spin_unlock(&dentry->d_lock); |
| 835 | if (parent) |
| 836 | spin_unlock(&parent->d_lock); |
| 837 | continue; |
| 838 | } |
| 839 | |
| 840 | __dentry_kill(dentry); |
| 841 | |
| 842 | /* |
| 843 | * We need to prune ancestors too. This is necessary to prevent |
| 844 | * quadratic behavior of shrink_dcache_parent(), but is also |
| 845 | * expected to be beneficial in reducing dentry cache |
| 846 | * fragmentation. |
| 847 | */ |
| 848 | dentry = parent; |
| 849 | while (dentry && !lockref_put_or_lock(&dentry->d_lockref)) { |
| 850 | parent = lock_parent(dentry); |
| 851 | if (dentry->d_lockref.count != 1) { |
| 852 | dentry->d_lockref.count--; |
| 853 | spin_unlock(&dentry->d_lock); |
| 854 | if (parent) |
| 855 | spin_unlock(&parent->d_lock); |
| 856 | break; |
| 857 | } |
| 858 | inode = dentry->d_inode; /* can't be NULL */ |
| 859 | if (unlikely(!spin_trylock(&inode->i_lock))) { |
| 860 | spin_unlock(&dentry->d_lock); |
| 861 | if (parent) |
| 862 | spin_unlock(&parent->d_lock); |
| 863 | cpu_relax(); |
| 864 | continue; |
| 865 | } |
| 866 | __dentry_kill(dentry); |
| 867 | dentry = parent; |
| 868 | } |
| 869 | } |
| 870 | } |
| 871 | |
| 872 | static enum lru_status |
| 873 | dentry_lru_isolate(struct list_head *item, spinlock_t *lru_lock, void *arg) |
| 874 | { |
| 875 | struct list_head *freeable = arg; |
| 876 | struct dentry *dentry = container_of(item, struct dentry, d_lru); |
| 877 | |
| 878 | |
| 879 | /* |
| 880 | * we are inverting the lru lock/dentry->d_lock here, |
| 881 | * so use a trylock. If we fail to get the lock, just skip |
| 882 | * it |
| 883 | */ |
| 884 | if (!spin_trylock(&dentry->d_lock)) |
| 885 | return LRU_SKIP; |
| 886 | |
| 887 | /* |
| 888 | * Referenced dentries are still in use. If they have active |
| 889 | * counts, just remove them from the LRU. Otherwise give them |
| 890 | * another pass through the LRU. |
| 891 | */ |
| 892 | if (dentry->d_lockref.count) { |
| 893 | d_lru_isolate(dentry); |
| 894 | spin_unlock(&dentry->d_lock); |
| 895 | return LRU_REMOVED; |
| 896 | } |
| 897 | |
| 898 | if (dentry->d_flags & DCACHE_REFERENCED) { |
| 899 | dentry->d_flags &= ~DCACHE_REFERENCED; |
| 900 | spin_unlock(&dentry->d_lock); |
| 901 | |
| 902 | /* |
| 903 | * The list move itself will be made by the common LRU code. At |
| 904 | * this point, we've dropped the dentry->d_lock but keep the |
| 905 | * lru lock. This is safe to do, since every list movement is |
| 906 | * protected by the lru lock even if both locks are held. |
| 907 | * |
| 908 | * This is guaranteed by the fact that all LRU management |
| 909 | * functions are intermediated by the LRU API calls like |
| 910 | * list_lru_add and list_lru_del. List movement in this file |
| 911 | * only ever occur through this functions or through callbacks |
| 912 | * like this one, that are called from the LRU API. |
| 913 | * |
| 914 | * The only exceptions to this are functions like |
| 915 | * shrink_dentry_list, and code that first checks for the |
| 916 | * DCACHE_SHRINK_LIST flag. Those are guaranteed to be |
| 917 | * operating only with stack provided lists after they are |
| 918 | * properly isolated from the main list. It is thus, always a |
| 919 | * local access. |
| 920 | */ |
| 921 | return LRU_ROTATE; |
| 922 | } |
| 923 | |
| 924 | d_lru_shrink_move(dentry, freeable); |
| 925 | spin_unlock(&dentry->d_lock); |
| 926 | |
| 927 | return LRU_REMOVED; |
| 928 | } |
| 929 | |
| 930 | /** |
| 931 | * prune_dcache_sb - shrink the dcache |
| 932 | * @sb: superblock |
| 933 | * @nr_to_scan : number of entries to try to free |
| 934 | * @nid: which node to scan for freeable entities |
| 935 | * |
| 936 | * Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is |
| 937 | * done when we need more memory an called from the superblock shrinker |
| 938 | * function. |
| 939 | * |
| 940 | * This function may fail to free any resources if all the dentries are in |
| 941 | * use. |
| 942 | */ |
| 943 | long prune_dcache_sb(struct super_block *sb, unsigned long nr_to_scan, |
| 944 | int nid) |
| 945 | { |
| 946 | LIST_HEAD(dispose); |
| 947 | long freed; |
| 948 | |
| 949 | freed = list_lru_walk_node(&sb->s_dentry_lru, nid, dentry_lru_isolate, |
| 950 | &dispose, &nr_to_scan); |
| 951 | shrink_dentry_list(&dispose); |
| 952 | return freed; |
| 953 | } |
| 954 | |
| 955 | static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
| 956 | spinlock_t *lru_lock, void *arg) |
| 957 | { |
| 958 | struct list_head *freeable = arg; |
| 959 | struct dentry *dentry = container_of(item, struct dentry, d_lru); |
| 960 | |
| 961 | /* |
| 962 | * we are inverting the lru lock/dentry->d_lock here, |
| 963 | * so use a trylock. If we fail to get the lock, just skip |
| 964 | * it |
| 965 | */ |
| 966 | if (!spin_trylock(&dentry->d_lock)) |
| 967 | return LRU_SKIP; |
| 968 | |
| 969 | d_lru_shrink_move(dentry, freeable); |
| 970 | spin_unlock(&dentry->d_lock); |
| 971 | |
| 972 | return LRU_REMOVED; |
| 973 | } |
| 974 | |
| 975 | |
| 976 | /** |
| 977 | * shrink_dcache_sb - shrink dcache for a superblock |
| 978 | * @sb: superblock |
| 979 | * |
| 980 | * Shrink the dcache for the specified super block. This is used to free |
| 981 | * the dcache before unmounting a file system. |
| 982 | */ |
| 983 | void shrink_dcache_sb(struct super_block *sb) |
| 984 | { |
| 985 | long freed; |
| 986 | |
| 987 | do { |
| 988 | LIST_HEAD(dispose); |
| 989 | |
| 990 | freed = list_lru_walk(&sb->s_dentry_lru, |
| 991 | dentry_lru_isolate_shrink, &dispose, UINT_MAX); |
| 992 | |
| 993 | this_cpu_sub(nr_dentry_unused, freed); |
| 994 | shrink_dentry_list(&dispose); |
| 995 | } while (freed > 0); |
| 996 | } |
| 997 | EXPORT_SYMBOL(shrink_dcache_sb); |
| 998 | |
| 999 | /** |
| 1000 | * enum d_walk_ret - action to talke during tree walk |
| 1001 | * @D_WALK_CONTINUE: contrinue walk |
| 1002 | * @D_WALK_QUIT: quit walk |
| 1003 | * @D_WALK_NORETRY: quit when retry is needed |
| 1004 | * @D_WALK_SKIP: skip this dentry and its children |
| 1005 | */ |
| 1006 | enum d_walk_ret { |
| 1007 | D_WALK_CONTINUE, |
| 1008 | D_WALK_QUIT, |
| 1009 | D_WALK_NORETRY, |
| 1010 | D_WALK_SKIP, |
| 1011 | }; |
| 1012 | |
| 1013 | /** |
| 1014 | * d_walk - walk the dentry tree |
| 1015 | * @parent: start of walk |
| 1016 | * @data: data passed to @enter() and @finish() |
| 1017 | * @enter: callback when first entering the dentry |
| 1018 | * @finish: callback when successfully finished the walk |
| 1019 | * |
| 1020 | * The @enter() and @finish() callbacks are called with d_lock held. |
| 1021 | */ |
| 1022 | static void d_walk(struct dentry *parent, void *data, |
| 1023 | enum d_walk_ret (*enter)(void *, struct dentry *), |
| 1024 | void (*finish)(void *)) |
| 1025 | { |
| 1026 | struct dentry *this_parent; |
| 1027 | struct list_head *next; |
| 1028 | unsigned seq = 0; |
| 1029 | enum d_walk_ret ret; |
| 1030 | bool retry = true; |
| 1031 | |
| 1032 | again: |
| 1033 | read_seqbegin_or_lock(&rename_lock, &seq); |
| 1034 | this_parent = parent; |
| 1035 | spin_lock(&this_parent->d_lock); |
| 1036 | |
| 1037 | ret = enter(data, this_parent); |
| 1038 | switch (ret) { |
| 1039 | case D_WALK_CONTINUE: |
| 1040 | break; |
| 1041 | case D_WALK_QUIT: |
| 1042 | case D_WALK_SKIP: |
| 1043 | goto out_unlock; |
| 1044 | case D_WALK_NORETRY: |
| 1045 | retry = false; |
| 1046 | break; |
| 1047 | } |
| 1048 | repeat: |
| 1049 | next = this_parent->d_subdirs.next; |
| 1050 | resume: |
| 1051 | while (next != &this_parent->d_subdirs) { |
| 1052 | struct list_head *tmp = next; |
| 1053 | struct dentry *dentry = list_entry(tmp, struct dentry, d_child); |
| 1054 | next = tmp->next; |
| 1055 | |
| 1056 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| 1057 | |
| 1058 | ret = enter(data, dentry); |
| 1059 | switch (ret) { |
| 1060 | case D_WALK_CONTINUE: |
| 1061 | break; |
| 1062 | case D_WALK_QUIT: |
| 1063 | spin_unlock(&dentry->d_lock); |
| 1064 | goto out_unlock; |
| 1065 | case D_WALK_NORETRY: |
| 1066 | retry = false; |
| 1067 | break; |
| 1068 | case D_WALK_SKIP: |
| 1069 | spin_unlock(&dentry->d_lock); |
| 1070 | continue; |
| 1071 | } |
| 1072 | |
| 1073 | if (!list_empty(&dentry->d_subdirs)) { |
| 1074 | spin_unlock(&this_parent->d_lock); |
| 1075 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
| 1076 | this_parent = dentry; |
| 1077 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
| 1078 | goto repeat; |
| 1079 | } |
| 1080 | spin_unlock(&dentry->d_lock); |
| 1081 | } |
| 1082 | /* |
| 1083 | * All done at this level ... ascend and resume the search. |
| 1084 | */ |
| 1085 | rcu_read_lock(); |
| 1086 | ascend: |
| 1087 | if (this_parent != parent) { |
| 1088 | struct dentry *child = this_parent; |
| 1089 | this_parent = child->d_parent; |
| 1090 | |
| 1091 | spin_unlock(&child->d_lock); |
| 1092 | spin_lock(&this_parent->d_lock); |
| 1093 | |
| 1094 | /* might go back up the wrong parent if we have had a rename. */ |
| 1095 | if (need_seqretry(&rename_lock, seq)) |
| 1096 | goto rename_retry; |
| 1097 | next = child->d_child.next; |
| 1098 | while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)) { |
| 1099 | if (next == &this_parent->d_subdirs) |
| 1100 | goto ascend; |
| 1101 | child = list_entry(next, struct dentry, d_child); |
| 1102 | next = next->next; |
| 1103 | } |
| 1104 | rcu_read_unlock(); |
| 1105 | goto resume; |
| 1106 | } |
| 1107 | if (need_seqretry(&rename_lock, seq)) |
| 1108 | goto rename_retry; |
| 1109 | rcu_read_unlock(); |
| 1110 | if (finish) |
| 1111 | finish(data); |
| 1112 | |
| 1113 | out_unlock: |
| 1114 | spin_unlock(&this_parent->d_lock); |
| 1115 | done_seqretry(&rename_lock, seq); |
| 1116 | return; |
| 1117 | |
| 1118 | rename_retry: |
| 1119 | spin_unlock(&this_parent->d_lock); |
| 1120 | rcu_read_unlock(); |
| 1121 | BUG_ON(seq & 1); |
| 1122 | if (!retry) |
| 1123 | return; |
| 1124 | seq = 1; |
| 1125 | goto again; |
| 1126 | } |
| 1127 | |
| 1128 | /* |
| 1129 | * Search for at least 1 mount point in the dentry's subdirs. |
| 1130 | * We descend to the next level whenever the d_subdirs |
| 1131 | * list is non-empty and continue searching. |
| 1132 | */ |
| 1133 | |
| 1134 | static enum d_walk_ret check_mount(void *data, struct dentry *dentry) |
| 1135 | { |
| 1136 | int *ret = data; |
| 1137 | if (d_mountpoint(dentry)) { |
| 1138 | *ret = 1; |
| 1139 | return D_WALK_QUIT; |
| 1140 | } |
| 1141 | return D_WALK_CONTINUE; |
| 1142 | } |
| 1143 | |
| 1144 | /** |
| 1145 | * have_submounts - check for mounts over a dentry |
| 1146 | * @parent: dentry to check. |
| 1147 | * |
| 1148 | * Return true if the parent or its subdirectories contain |
| 1149 | * a mount point |
| 1150 | */ |
| 1151 | int have_submounts(struct dentry *parent) |
| 1152 | { |
| 1153 | int ret = 0; |
| 1154 | |
| 1155 | d_walk(parent, &ret, check_mount, NULL); |
| 1156 | |
| 1157 | return ret; |
| 1158 | } |
| 1159 | EXPORT_SYMBOL(have_submounts); |
| 1160 | |
| 1161 | /* |
| 1162 | * Called by mount code to set a mountpoint and check if the mountpoint is |
| 1163 | * reachable (e.g. NFS can unhash a directory dentry and then the complete |
| 1164 | * subtree can become unreachable). |
| 1165 | * |
| 1166 | * Only one of d_invalidate() and d_set_mounted() must succeed. For |
| 1167 | * this reason take rename_lock and d_lock on dentry and ancestors. |
| 1168 | */ |
| 1169 | int d_set_mounted(struct dentry *dentry) |
| 1170 | { |
| 1171 | struct dentry *p; |
| 1172 | int ret = -ENOENT; |
| 1173 | write_seqlock(&rename_lock); |
| 1174 | for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { |
| 1175 | /* Need exclusion wrt. d_invalidate() */ |
| 1176 | spin_lock(&p->d_lock); |
| 1177 | if (unlikely(d_unhashed(p))) { |
| 1178 | spin_unlock(&p->d_lock); |
| 1179 | goto out; |
| 1180 | } |
| 1181 | spin_unlock(&p->d_lock); |
| 1182 | } |
| 1183 | spin_lock(&dentry->d_lock); |
| 1184 | if (!d_unlinked(dentry)) { |
| 1185 | dentry->d_flags |= DCACHE_MOUNTED; |
| 1186 | ret = 0; |
| 1187 | } |
| 1188 | spin_unlock(&dentry->d_lock); |
| 1189 | out: |
| 1190 | write_sequnlock(&rename_lock); |
| 1191 | return ret; |
| 1192 | } |
| 1193 | |
| 1194 | /* |
| 1195 | * Search the dentry child list of the specified parent, |
| 1196 | * and move any unused dentries to the end of the unused |
| 1197 | * list for prune_dcache(). We descend to the next level |
| 1198 | * whenever the d_subdirs list is non-empty and continue |
| 1199 | * searching. |
| 1200 | * |
| 1201 | * It returns zero iff there are no unused children, |
| 1202 | * otherwise it returns the number of children moved to |
| 1203 | * the end of the unused list. This may not be the total |
| 1204 | * number of unused children, because select_parent can |
| 1205 | * drop the lock and return early due to latency |
| 1206 | * constraints. |
| 1207 | */ |
| 1208 | |
| 1209 | struct select_data { |
| 1210 | struct dentry *start; |
| 1211 | struct list_head dispose; |
| 1212 | int found; |
| 1213 | }; |
| 1214 | |
| 1215 | static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) |
| 1216 | { |
| 1217 | struct select_data *data = _data; |
| 1218 | enum d_walk_ret ret = D_WALK_CONTINUE; |
| 1219 | |
| 1220 | if (data->start == dentry) |
| 1221 | goto out; |
| 1222 | |
| 1223 | if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
| 1224 | data->found++; |
| 1225 | } else { |
| 1226 | if (dentry->d_flags & DCACHE_LRU_LIST) |
| 1227 | d_lru_del(dentry); |
| 1228 | if (!dentry->d_lockref.count) { |
| 1229 | d_shrink_add(dentry, &data->dispose); |
| 1230 | data->found++; |
| 1231 | } |
| 1232 | } |
| 1233 | /* |
| 1234 | * We can return to the caller if we have found some (this |
| 1235 | * ensures forward progress). We'll be coming back to find |
| 1236 | * the rest. |
| 1237 | */ |
| 1238 | if (!list_empty(&data->dispose)) |
| 1239 | ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; |
| 1240 | out: |
| 1241 | return ret; |
| 1242 | } |
| 1243 | |
| 1244 | /** |
| 1245 | * shrink_dcache_parent - prune dcache |
| 1246 | * @parent: parent of entries to prune |
| 1247 | * |
| 1248 | * Prune the dcache to remove unused children of the parent dentry. |
| 1249 | */ |
| 1250 | void shrink_dcache_parent(struct dentry *parent) |
| 1251 | { |
| 1252 | for (;;) { |
| 1253 | struct select_data data; |
| 1254 | |
| 1255 | INIT_LIST_HEAD(&data.dispose); |
| 1256 | data.start = parent; |
| 1257 | data.found = 0; |
| 1258 | |
| 1259 | d_walk(parent, &data, select_collect, NULL); |
| 1260 | if (!data.found) |
| 1261 | break; |
| 1262 | |
| 1263 | shrink_dentry_list(&data.dispose); |
| 1264 | cond_resched(); |
| 1265 | } |
| 1266 | } |
| 1267 | EXPORT_SYMBOL(shrink_dcache_parent); |
| 1268 | |
| 1269 | static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) |
| 1270 | { |
| 1271 | /* it has busy descendents; complain about those instead */ |
| 1272 | if (!list_empty(&dentry->d_subdirs)) |
| 1273 | return D_WALK_CONTINUE; |
| 1274 | |
| 1275 | /* root with refcount 1 is fine */ |
| 1276 | if (dentry == _data && dentry->d_lockref.count == 1) |
| 1277 | return D_WALK_CONTINUE; |
| 1278 | |
| 1279 | printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} " |
| 1280 | " still in use (%d) [unmount of %s %s]\n", |
| 1281 | dentry, |
| 1282 | dentry->d_inode ? |
| 1283 | dentry->d_inode->i_ino : 0UL, |
| 1284 | dentry, |
| 1285 | dentry->d_lockref.count, |
| 1286 | dentry->d_sb->s_type->name, |
| 1287 | dentry->d_sb->s_id); |
| 1288 | WARN_ON(1); |
| 1289 | return D_WALK_CONTINUE; |
| 1290 | } |
| 1291 | |
| 1292 | static void do_one_tree(struct dentry *dentry) |
| 1293 | { |
| 1294 | shrink_dcache_parent(dentry); |
| 1295 | d_walk(dentry, dentry, umount_check, NULL); |
| 1296 | d_drop(dentry); |
| 1297 | dput(dentry); |
| 1298 | } |
| 1299 | |
| 1300 | /* |
| 1301 | * destroy the dentries attached to a superblock on unmounting |
| 1302 | */ |
| 1303 | void shrink_dcache_for_umount(struct super_block *sb) |
| 1304 | { |
| 1305 | struct dentry *dentry; |
| 1306 | |
| 1307 | WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked"); |
| 1308 | |
| 1309 | dentry = sb->s_root; |
| 1310 | sb->s_root = NULL; |
| 1311 | do_one_tree(dentry); |
| 1312 | |
| 1313 | while (!hlist_bl_empty(&sb->s_anon)) { |
| 1314 | dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash)); |
| 1315 | do_one_tree(dentry); |
| 1316 | } |
| 1317 | } |
| 1318 | |
| 1319 | struct detach_data { |
| 1320 | struct select_data select; |
| 1321 | struct dentry *mountpoint; |
| 1322 | }; |
| 1323 | static enum d_walk_ret detach_and_collect(void *_data, struct dentry *dentry) |
| 1324 | { |
| 1325 | struct detach_data *data = _data; |
| 1326 | |
| 1327 | if (d_mountpoint(dentry)) { |
| 1328 | __dget_dlock(dentry); |
| 1329 | data->mountpoint = dentry; |
| 1330 | return D_WALK_QUIT; |
| 1331 | } |
| 1332 | |
| 1333 | return select_collect(&data->select, dentry); |
| 1334 | } |
| 1335 | |
| 1336 | static void check_and_drop(void *_data) |
| 1337 | { |
| 1338 | struct detach_data *data = _data; |
| 1339 | |
| 1340 | if (!data->mountpoint && !data->select.found) |
| 1341 | __d_drop(data->select.start); |
| 1342 | } |
| 1343 | |
| 1344 | /** |
| 1345 | * d_invalidate - detach submounts, prune dcache, and drop |
| 1346 | * @dentry: dentry to invalidate (aka detach, prune and drop) |
| 1347 | * |
| 1348 | * no dcache lock. |
| 1349 | * |
| 1350 | * The final d_drop is done as an atomic operation relative to |
| 1351 | * rename_lock ensuring there are no races with d_set_mounted. This |
| 1352 | * ensures there are no unhashed dentries on the path to a mountpoint. |
| 1353 | */ |
| 1354 | void d_invalidate(struct dentry *dentry) |
| 1355 | { |
| 1356 | /* |
| 1357 | * If it's already been dropped, return OK. |
| 1358 | */ |
| 1359 | spin_lock(&dentry->d_lock); |
| 1360 | if (d_unhashed(dentry)) { |
| 1361 | spin_unlock(&dentry->d_lock); |
| 1362 | return; |
| 1363 | } |
| 1364 | spin_unlock(&dentry->d_lock); |
| 1365 | |
| 1366 | /* Negative dentries can be dropped without further checks */ |
| 1367 | if (!dentry->d_inode) { |
| 1368 | d_drop(dentry); |
| 1369 | return; |
| 1370 | } |
| 1371 | |
| 1372 | for (;;) { |
| 1373 | struct detach_data data; |
| 1374 | |
| 1375 | data.mountpoint = NULL; |
| 1376 | INIT_LIST_HEAD(&data.select.dispose); |
| 1377 | data.select.start = dentry; |
| 1378 | data.select.found = 0; |
| 1379 | |
| 1380 | d_walk(dentry, &data, detach_and_collect, check_and_drop); |
| 1381 | |
| 1382 | if (data.select.found) |
| 1383 | shrink_dentry_list(&data.select.dispose); |
| 1384 | |
| 1385 | if (data.mountpoint) { |
| 1386 | detach_mounts(data.mountpoint); |
| 1387 | dput(data.mountpoint); |
| 1388 | } |
| 1389 | |
| 1390 | if (!data.mountpoint && !data.select.found) |
| 1391 | break; |
| 1392 | |
| 1393 | cond_resched(); |
| 1394 | } |
| 1395 | } |
| 1396 | EXPORT_SYMBOL(d_invalidate); |
| 1397 | |
| 1398 | /** |
| 1399 | * __d_alloc - allocate a dcache entry |
| 1400 | * @sb: filesystem it will belong to |
| 1401 | * @name: qstr of the name |
| 1402 | * |
| 1403 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 1404 | * available. On a success the dentry is returned. The name passed in is |
| 1405 | * copied and the copy passed in may be reused after this call. |
| 1406 | */ |
| 1407 | |
| 1408 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
| 1409 | { |
| 1410 | struct dentry *dentry; |
| 1411 | char *dname; |
| 1412 | |
| 1413 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
| 1414 | if (!dentry) |
| 1415 | return NULL; |
| 1416 | |
| 1417 | /* |
| 1418 | * We guarantee that the inline name is always NUL-terminated. |
| 1419 | * This way the memcpy() done by the name switching in rename |
| 1420 | * will still always have a NUL at the end, even if we might |
| 1421 | * be overwriting an internal NUL character |
| 1422 | */ |
| 1423 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; |
| 1424 | if (name->len > DNAME_INLINE_LEN-1) { |
| 1425 | size_t size = offsetof(struct external_name, name[1]); |
| 1426 | struct external_name *p = kmalloc(size + name->len, GFP_KERNEL); |
| 1427 | if (!p) { |
| 1428 | kmem_cache_free(dentry_cache, dentry); |
| 1429 | return NULL; |
| 1430 | } |
| 1431 | atomic_set(&p->u.count, 1); |
| 1432 | dname = p->name; |
| 1433 | } else { |
| 1434 | dname = dentry->d_iname; |
| 1435 | } |
| 1436 | |
| 1437 | dentry->d_name.len = name->len; |
| 1438 | dentry->d_name.hash = name->hash; |
| 1439 | memcpy(dname, name->name, name->len); |
| 1440 | dname[name->len] = 0; |
| 1441 | |
| 1442 | /* Make sure we always see the terminating NUL character */ |
| 1443 | smp_wmb(); |
| 1444 | dentry->d_name.name = dname; |
| 1445 | |
| 1446 | dentry->d_lockref.count = 1; |
| 1447 | dentry->d_flags = 0; |
| 1448 | spin_lock_init(&dentry->d_lock); |
| 1449 | seqcount_init(&dentry->d_seq); |
| 1450 | dentry->d_inode = NULL; |
| 1451 | dentry->d_parent = dentry; |
| 1452 | dentry->d_sb = sb; |
| 1453 | dentry->d_op = NULL; |
| 1454 | dentry->d_fsdata = NULL; |
| 1455 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
| 1456 | INIT_LIST_HEAD(&dentry->d_lru); |
| 1457 | INIT_LIST_HEAD(&dentry->d_subdirs); |
| 1458 | INIT_HLIST_NODE(&dentry->d_u.d_alias); |
| 1459 | INIT_LIST_HEAD(&dentry->d_child); |
| 1460 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
| 1461 | |
| 1462 | this_cpu_inc(nr_dentry); |
| 1463 | |
| 1464 | return dentry; |
| 1465 | } |
| 1466 | |
| 1467 | /** |
| 1468 | * d_alloc - allocate a dcache entry |
| 1469 | * @parent: parent of entry to allocate |
| 1470 | * @name: qstr of the name |
| 1471 | * |
| 1472 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
| 1473 | * available. On a success the dentry is returned. The name passed in is |
| 1474 | * copied and the copy passed in may be reused after this call. |
| 1475 | */ |
| 1476 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
| 1477 | { |
| 1478 | struct dentry *dentry = __d_alloc(parent->d_sb, name); |
| 1479 | if (!dentry) |
| 1480 | return NULL; |
| 1481 | |
| 1482 | spin_lock(&parent->d_lock); |
| 1483 | /* |
| 1484 | * don't need child lock because it is not subject |
| 1485 | * to concurrency here |
| 1486 | */ |
| 1487 | __dget_dlock(parent); |
| 1488 | dentry->d_parent = parent; |
| 1489 | list_add(&dentry->d_child, &parent->d_subdirs); |
| 1490 | spin_unlock(&parent->d_lock); |
| 1491 | |
| 1492 | return dentry; |
| 1493 | } |
| 1494 | EXPORT_SYMBOL(d_alloc); |
| 1495 | |
| 1496 | /** |
| 1497 | * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) |
| 1498 | * @sb: the superblock |
| 1499 | * @name: qstr of the name |
| 1500 | * |
| 1501 | * For a filesystem that just pins its dentries in memory and never |
| 1502 | * performs lookups at all, return an unhashed IS_ROOT dentry. |
| 1503 | */ |
| 1504 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
| 1505 | { |
| 1506 | return __d_alloc(sb, name); |
| 1507 | } |
| 1508 | EXPORT_SYMBOL(d_alloc_pseudo); |
| 1509 | |
| 1510 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
| 1511 | { |
| 1512 | struct qstr q; |
| 1513 | |
| 1514 | q.name = name; |
| 1515 | q.len = strlen(name); |
| 1516 | q.hash = full_name_hash(q.name, q.len); |
| 1517 | return d_alloc(parent, &q); |
| 1518 | } |
| 1519 | EXPORT_SYMBOL(d_alloc_name); |
| 1520 | |
| 1521 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
| 1522 | { |
| 1523 | WARN_ON_ONCE(dentry->d_op); |
| 1524 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
| 1525 | DCACHE_OP_COMPARE | |
| 1526 | DCACHE_OP_REVALIDATE | |
| 1527 | DCACHE_OP_WEAK_REVALIDATE | |
| 1528 | DCACHE_OP_DELETE )); |
| 1529 | dentry->d_op = op; |
| 1530 | if (!op) |
| 1531 | return; |
| 1532 | if (op->d_hash) |
| 1533 | dentry->d_flags |= DCACHE_OP_HASH; |
| 1534 | if (op->d_compare) |
| 1535 | dentry->d_flags |= DCACHE_OP_COMPARE; |
| 1536 | if (op->d_revalidate) |
| 1537 | dentry->d_flags |= DCACHE_OP_REVALIDATE; |
| 1538 | if (op->d_weak_revalidate) |
| 1539 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; |
| 1540 | if (op->d_delete) |
| 1541 | dentry->d_flags |= DCACHE_OP_DELETE; |
| 1542 | if (op->d_prune) |
| 1543 | dentry->d_flags |= DCACHE_OP_PRUNE; |
| 1544 | |
| 1545 | } |
| 1546 | EXPORT_SYMBOL(d_set_d_op); |
| 1547 | |
| 1548 | static unsigned d_flags_for_inode(struct inode *inode) |
| 1549 | { |
| 1550 | unsigned add_flags = DCACHE_FILE_TYPE; |
| 1551 | |
| 1552 | if (!inode) |
| 1553 | return DCACHE_MISS_TYPE; |
| 1554 | |
| 1555 | if (S_ISDIR(inode->i_mode)) { |
| 1556 | add_flags = DCACHE_DIRECTORY_TYPE; |
| 1557 | if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { |
| 1558 | if (unlikely(!inode->i_op->lookup)) |
| 1559 | add_flags = DCACHE_AUTODIR_TYPE; |
| 1560 | else |
| 1561 | inode->i_opflags |= IOP_LOOKUP; |
| 1562 | } |
| 1563 | } else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { |
| 1564 | if (unlikely(inode->i_op->follow_link)) |
| 1565 | add_flags = DCACHE_SYMLINK_TYPE; |
| 1566 | else |
| 1567 | inode->i_opflags |= IOP_NOFOLLOW; |
| 1568 | } |
| 1569 | |
| 1570 | if (unlikely(IS_AUTOMOUNT(inode))) |
| 1571 | add_flags |= DCACHE_NEED_AUTOMOUNT; |
| 1572 | return add_flags; |
| 1573 | } |
| 1574 | |
| 1575 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
| 1576 | { |
| 1577 | unsigned add_flags = d_flags_for_inode(inode); |
| 1578 | |
| 1579 | spin_lock(&dentry->d_lock); |
| 1580 | __d_set_type(dentry, add_flags); |
| 1581 | if (inode) |
| 1582 | hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); |
| 1583 | dentry->d_inode = inode; |
| 1584 | dentry_rcuwalk_barrier(dentry); |
| 1585 | spin_unlock(&dentry->d_lock); |
| 1586 | fsnotify_d_instantiate(dentry, inode); |
| 1587 | } |
| 1588 | |
| 1589 | /** |
| 1590 | * d_instantiate - fill in inode information for a dentry |
| 1591 | * @entry: dentry to complete |
| 1592 | * @inode: inode to attach to this dentry |
| 1593 | * |
| 1594 | * Fill in inode information in the entry. |
| 1595 | * |
| 1596 | * This turns negative dentries into productive full members |
| 1597 | * of society. |
| 1598 | * |
| 1599 | * NOTE! This assumes that the inode count has been incremented |
| 1600 | * (or otherwise set) by the caller to indicate that it is now |
| 1601 | * in use by the dcache. |
| 1602 | */ |
| 1603 | |
| 1604 | void d_instantiate(struct dentry *entry, struct inode * inode) |
| 1605 | { |
| 1606 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
| 1607 | if (inode) |
| 1608 | spin_lock(&inode->i_lock); |
| 1609 | __d_instantiate(entry, inode); |
| 1610 | if (inode) |
| 1611 | spin_unlock(&inode->i_lock); |
| 1612 | security_d_instantiate(entry, inode); |
| 1613 | } |
| 1614 | EXPORT_SYMBOL(d_instantiate); |
| 1615 | |
| 1616 | /** |
| 1617 | * d_instantiate_unique - instantiate a non-aliased dentry |
| 1618 | * @entry: dentry to instantiate |
| 1619 | * @inode: inode to attach to this dentry |
| 1620 | * |
| 1621 | * Fill in inode information in the entry. On success, it returns NULL. |
| 1622 | * If an unhashed alias of "entry" already exists, then we return the |
| 1623 | * aliased dentry instead and drop one reference to inode. |
| 1624 | * |
| 1625 | * Note that in order to avoid conflicts with rename() etc, the caller |
| 1626 | * had better be holding the parent directory semaphore. |
| 1627 | * |
| 1628 | * This also assumes that the inode count has been incremented |
| 1629 | * (or otherwise set) by the caller to indicate that it is now |
| 1630 | * in use by the dcache. |
| 1631 | */ |
| 1632 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
| 1633 | struct inode *inode) |
| 1634 | { |
| 1635 | struct dentry *alias; |
| 1636 | int len = entry->d_name.len; |
| 1637 | const char *name = entry->d_name.name; |
| 1638 | unsigned int hash = entry->d_name.hash; |
| 1639 | |
| 1640 | if (!inode) { |
| 1641 | __d_instantiate(entry, NULL); |
| 1642 | return NULL; |
| 1643 | } |
| 1644 | |
| 1645 | hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
| 1646 | /* |
| 1647 | * Don't need alias->d_lock here, because aliases with |
| 1648 | * d_parent == entry->d_parent are not subject to name or |
| 1649 | * parent changes, because the parent inode i_mutex is held. |
| 1650 | */ |
| 1651 | if (alias->d_name.hash != hash) |
| 1652 | continue; |
| 1653 | if (alias->d_parent != entry->d_parent) |
| 1654 | continue; |
| 1655 | if (alias->d_name.len != len) |
| 1656 | continue; |
| 1657 | if (dentry_cmp(alias, name, len)) |
| 1658 | continue; |
| 1659 | __dget(alias); |
| 1660 | return alias; |
| 1661 | } |
| 1662 | |
| 1663 | __d_instantiate(entry, inode); |
| 1664 | return NULL; |
| 1665 | } |
| 1666 | |
| 1667 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
| 1668 | { |
| 1669 | struct dentry *result; |
| 1670 | |
| 1671 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
| 1672 | |
| 1673 | if (inode) |
| 1674 | spin_lock(&inode->i_lock); |
| 1675 | result = __d_instantiate_unique(entry, inode); |
| 1676 | if (inode) |
| 1677 | spin_unlock(&inode->i_lock); |
| 1678 | |
| 1679 | if (!result) { |
| 1680 | security_d_instantiate(entry, inode); |
| 1681 | return NULL; |
| 1682 | } |
| 1683 | |
| 1684 | BUG_ON(!d_unhashed(result)); |
| 1685 | iput(inode); |
| 1686 | return result; |
| 1687 | } |
| 1688 | |
| 1689 | EXPORT_SYMBOL(d_instantiate_unique); |
| 1690 | |
| 1691 | /** |
| 1692 | * d_instantiate_no_diralias - instantiate a non-aliased dentry |
| 1693 | * @entry: dentry to complete |
| 1694 | * @inode: inode to attach to this dentry |
| 1695 | * |
| 1696 | * Fill in inode information in the entry. If a directory alias is found, then |
| 1697 | * return an error (and drop inode). Together with d_materialise_unique() this |
| 1698 | * guarantees that a directory inode may never have more than one alias. |
| 1699 | */ |
| 1700 | int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) |
| 1701 | { |
| 1702 | BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
| 1703 | |
| 1704 | spin_lock(&inode->i_lock); |
| 1705 | if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { |
| 1706 | spin_unlock(&inode->i_lock); |
| 1707 | iput(inode); |
| 1708 | return -EBUSY; |
| 1709 | } |
| 1710 | __d_instantiate(entry, inode); |
| 1711 | spin_unlock(&inode->i_lock); |
| 1712 | security_d_instantiate(entry, inode); |
| 1713 | |
| 1714 | return 0; |
| 1715 | } |
| 1716 | EXPORT_SYMBOL(d_instantiate_no_diralias); |
| 1717 | |
| 1718 | struct dentry *d_make_root(struct inode *root_inode) |
| 1719 | { |
| 1720 | struct dentry *res = NULL; |
| 1721 | |
| 1722 | if (root_inode) { |
| 1723 | static const struct qstr name = QSTR_INIT("/", 1); |
| 1724 | |
| 1725 | res = __d_alloc(root_inode->i_sb, &name); |
| 1726 | if (res) |
| 1727 | d_instantiate(res, root_inode); |
| 1728 | else |
| 1729 | iput(root_inode); |
| 1730 | } |
| 1731 | return res; |
| 1732 | } |
| 1733 | EXPORT_SYMBOL(d_make_root); |
| 1734 | |
| 1735 | static struct dentry * __d_find_any_alias(struct inode *inode) |
| 1736 | { |
| 1737 | struct dentry *alias; |
| 1738 | |
| 1739 | if (hlist_empty(&inode->i_dentry)) |
| 1740 | return NULL; |
| 1741 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); |
| 1742 | __dget(alias); |
| 1743 | return alias; |
| 1744 | } |
| 1745 | |
| 1746 | /** |
| 1747 | * d_find_any_alias - find any alias for a given inode |
| 1748 | * @inode: inode to find an alias for |
| 1749 | * |
| 1750 | * If any aliases exist for the given inode, take and return a |
| 1751 | * reference for one of them. If no aliases exist, return %NULL. |
| 1752 | */ |
| 1753 | struct dentry *d_find_any_alias(struct inode *inode) |
| 1754 | { |
| 1755 | struct dentry *de; |
| 1756 | |
| 1757 | spin_lock(&inode->i_lock); |
| 1758 | de = __d_find_any_alias(inode); |
| 1759 | spin_unlock(&inode->i_lock); |
| 1760 | return de; |
| 1761 | } |
| 1762 | EXPORT_SYMBOL(d_find_any_alias); |
| 1763 | |
| 1764 | static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected) |
| 1765 | { |
| 1766 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
| 1767 | struct dentry *tmp; |
| 1768 | struct dentry *res; |
| 1769 | unsigned add_flags; |
| 1770 | |
| 1771 | if (!inode) |
| 1772 | return ERR_PTR(-ESTALE); |
| 1773 | if (IS_ERR(inode)) |
| 1774 | return ERR_CAST(inode); |
| 1775 | |
| 1776 | res = d_find_any_alias(inode); |
| 1777 | if (res) |
| 1778 | goto out_iput; |
| 1779 | |
| 1780 | tmp = __d_alloc(inode->i_sb, &anonstring); |
| 1781 | if (!tmp) { |
| 1782 | res = ERR_PTR(-ENOMEM); |
| 1783 | goto out_iput; |
| 1784 | } |
| 1785 | |
| 1786 | spin_lock(&inode->i_lock); |
| 1787 | res = __d_find_any_alias(inode); |
| 1788 | if (res) { |
| 1789 | spin_unlock(&inode->i_lock); |
| 1790 | dput(tmp); |
| 1791 | goto out_iput; |
| 1792 | } |
| 1793 | |
| 1794 | /* attach a disconnected dentry */ |
| 1795 | add_flags = d_flags_for_inode(inode); |
| 1796 | |
| 1797 | if (disconnected) |
| 1798 | add_flags |= DCACHE_DISCONNECTED; |
| 1799 | |
| 1800 | spin_lock(&tmp->d_lock); |
| 1801 | tmp->d_inode = inode; |
| 1802 | tmp->d_flags |= add_flags; |
| 1803 | hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry); |
| 1804 | hlist_bl_lock(&tmp->d_sb->s_anon); |
| 1805 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
| 1806 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
| 1807 | spin_unlock(&tmp->d_lock); |
| 1808 | spin_unlock(&inode->i_lock); |
| 1809 | security_d_instantiate(tmp, inode); |
| 1810 | |
| 1811 | return tmp; |
| 1812 | |
| 1813 | out_iput: |
| 1814 | if (res && !IS_ERR(res)) |
| 1815 | security_d_instantiate(res, inode); |
| 1816 | iput(inode); |
| 1817 | return res; |
| 1818 | } |
| 1819 | |
| 1820 | /** |
| 1821 | * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode |
| 1822 | * @inode: inode to allocate the dentry for |
| 1823 | * |
| 1824 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
| 1825 | * similar open by handle operations. The returned dentry may be anonymous, |
| 1826 | * or may have a full name (if the inode was already in the cache). |
| 1827 | * |
| 1828 | * When called on a directory inode, we must ensure that the inode only ever |
| 1829 | * has one dentry. If a dentry is found, that is returned instead of |
| 1830 | * allocating a new one. |
| 1831 | * |
| 1832 | * On successful return, the reference to the inode has been transferred |
| 1833 | * to the dentry. In case of an error the reference on the inode is released. |
| 1834 | * To make it easier to use in export operations a %NULL or IS_ERR inode may |
| 1835 | * be passed in and the error will be propagated to the return value, |
| 1836 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
| 1837 | */ |
| 1838 | struct dentry *d_obtain_alias(struct inode *inode) |
| 1839 | { |
| 1840 | return __d_obtain_alias(inode, 1); |
| 1841 | } |
| 1842 | EXPORT_SYMBOL(d_obtain_alias); |
| 1843 | |
| 1844 | /** |
| 1845 | * d_obtain_root - find or allocate a dentry for a given inode |
| 1846 | * @inode: inode to allocate the dentry for |
| 1847 | * |
| 1848 | * Obtain an IS_ROOT dentry for the root of a filesystem. |
| 1849 | * |
| 1850 | * We must ensure that directory inodes only ever have one dentry. If a |
| 1851 | * dentry is found, that is returned instead of allocating a new one. |
| 1852 | * |
| 1853 | * On successful return, the reference to the inode has been transferred |
| 1854 | * to the dentry. In case of an error the reference on the inode is |
| 1855 | * released. A %NULL or IS_ERR inode may be passed in and will be the |
| 1856 | * error will be propagate to the return value, with a %NULL @inode |
| 1857 | * replaced by ERR_PTR(-ESTALE). |
| 1858 | */ |
| 1859 | struct dentry *d_obtain_root(struct inode *inode) |
| 1860 | { |
| 1861 | return __d_obtain_alias(inode, 0); |
| 1862 | } |
| 1863 | EXPORT_SYMBOL(d_obtain_root); |
| 1864 | |
| 1865 | /** |
| 1866 | * d_add_ci - lookup or allocate new dentry with case-exact name |
| 1867 | * @inode: the inode case-insensitive lookup has found |
| 1868 | * @dentry: the negative dentry that was passed to the parent's lookup func |
| 1869 | * @name: the case-exact name to be associated with the returned dentry |
| 1870 | * |
| 1871 | * This is to avoid filling the dcache with case-insensitive names to the |
| 1872 | * same inode, only the actual correct case is stored in the dcache for |
| 1873 | * case-insensitive filesystems. |
| 1874 | * |
| 1875 | * For a case-insensitive lookup match and if the the case-exact dentry |
| 1876 | * already exists in in the dcache, use it and return it. |
| 1877 | * |
| 1878 | * If no entry exists with the exact case name, allocate new dentry with |
| 1879 | * the exact case, and return the spliced entry. |
| 1880 | */ |
| 1881 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
| 1882 | struct qstr *name) |
| 1883 | { |
| 1884 | struct dentry *found; |
| 1885 | struct dentry *new; |
| 1886 | |
| 1887 | /* |
| 1888 | * First check if a dentry matching the name already exists, |
| 1889 | * if not go ahead and create it now. |
| 1890 | */ |
| 1891 | found = d_hash_and_lookup(dentry->d_parent, name); |
| 1892 | if (!found) { |
| 1893 | new = d_alloc(dentry->d_parent, name); |
| 1894 | if (!new) { |
| 1895 | found = ERR_PTR(-ENOMEM); |
| 1896 | } else { |
| 1897 | found = d_splice_alias(inode, new); |
| 1898 | if (found) { |
| 1899 | dput(new); |
| 1900 | return found; |
| 1901 | } |
| 1902 | return new; |
| 1903 | } |
| 1904 | } |
| 1905 | iput(inode); |
| 1906 | return found; |
| 1907 | } |
| 1908 | EXPORT_SYMBOL(d_add_ci); |
| 1909 | |
| 1910 | /* |
| 1911 | * Do the slow-case of the dentry name compare. |
| 1912 | * |
| 1913 | * Unlike the dentry_cmp() function, we need to atomically |
| 1914 | * load the name and length information, so that the |
| 1915 | * filesystem can rely on them, and can use the 'name' and |
| 1916 | * 'len' information without worrying about walking off the |
| 1917 | * end of memory etc. |
| 1918 | * |
| 1919 | * Thus the read_seqcount_retry() and the "duplicate" info |
| 1920 | * in arguments (the low-level filesystem should not look |
| 1921 | * at the dentry inode or name contents directly, since |
| 1922 | * rename can change them while we're in RCU mode). |
| 1923 | */ |
| 1924 | enum slow_d_compare { |
| 1925 | D_COMP_OK, |
| 1926 | D_COMP_NOMATCH, |
| 1927 | D_COMP_SEQRETRY, |
| 1928 | }; |
| 1929 | |
| 1930 | static noinline enum slow_d_compare slow_dentry_cmp( |
| 1931 | const struct dentry *parent, |
| 1932 | struct dentry *dentry, |
| 1933 | unsigned int seq, |
| 1934 | const struct qstr *name) |
| 1935 | { |
| 1936 | int tlen = dentry->d_name.len; |
| 1937 | const char *tname = dentry->d_name.name; |
| 1938 | |
| 1939 | if (read_seqcount_retry(&dentry->d_seq, seq)) { |
| 1940 | cpu_relax(); |
| 1941 | return D_COMP_SEQRETRY; |
| 1942 | } |
| 1943 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
| 1944 | return D_COMP_NOMATCH; |
| 1945 | return D_COMP_OK; |
| 1946 | } |
| 1947 | |
| 1948 | /** |
| 1949 | * __d_lookup_rcu - search for a dentry (racy, store-free) |
| 1950 | * @parent: parent dentry |
| 1951 | * @name: qstr of name we wish to find |
| 1952 | * @seqp: returns d_seq value at the point where the dentry was found |
| 1953 | * Returns: dentry, or NULL |
| 1954 | * |
| 1955 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name |
| 1956 | * resolution (store-free path walking) design described in |
| 1957 | * Documentation/filesystems/path-lookup.txt. |
| 1958 | * |
| 1959 | * This is not to be used outside core vfs. |
| 1960 | * |
| 1961 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock |
| 1962 | * held, and rcu_read_lock held. The returned dentry must not be stored into |
| 1963 | * without taking d_lock and checking d_seq sequence count against @seq |
| 1964 | * returned here. |
| 1965 | * |
| 1966 | * A refcount may be taken on the found dentry with the d_rcu_to_refcount |
| 1967 | * function. |
| 1968 | * |
| 1969 | * Alternatively, __d_lookup_rcu may be called again to look up the child of |
| 1970 | * the returned dentry, so long as its parent's seqlock is checked after the |
| 1971 | * child is looked up. Thus, an interlocking stepping of sequence lock checks |
| 1972 | * is formed, giving integrity down the path walk. |
| 1973 | * |
| 1974 | * NOTE! The caller *has* to check the resulting dentry against the sequence |
| 1975 | * number we've returned before using any of the resulting dentry state! |
| 1976 | */ |
| 1977 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
| 1978 | const struct qstr *name, |
| 1979 | unsigned *seqp) |
| 1980 | { |
| 1981 | u64 hashlen = name->hash_len; |
| 1982 | const unsigned char *str = name->name; |
| 1983 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
| 1984 | struct hlist_bl_node *node; |
| 1985 | struct dentry *dentry; |
| 1986 | |
| 1987 | /* |
| 1988 | * Note: There is significant duplication with __d_lookup_rcu which is |
| 1989 | * required to prevent single threaded performance regressions |
| 1990 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
| 1991 | * Keep the two functions in sync. |
| 1992 | */ |
| 1993 | |
| 1994 | /* |
| 1995 | * The hash list is protected using RCU. |
| 1996 | * |
| 1997 | * Carefully use d_seq when comparing a candidate dentry, to avoid |
| 1998 | * races with d_move(). |
| 1999 | * |
| 2000 | * It is possible that concurrent renames can mess up our list |
| 2001 | * walk here and result in missing our dentry, resulting in the |
| 2002 | * false-negative result. d_lookup() protects against concurrent |
| 2003 | * renames using rename_lock seqlock. |
| 2004 | * |
| 2005 | * See Documentation/filesystems/path-lookup.txt for more details. |
| 2006 | */ |
| 2007 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
| 2008 | unsigned seq; |
| 2009 | |
| 2010 | seqretry: |
| 2011 | /* |
| 2012 | * The dentry sequence count protects us from concurrent |
| 2013 | * renames, and thus protects parent and name fields. |
| 2014 | * |
| 2015 | * The caller must perform a seqcount check in order |
| 2016 | * to do anything useful with the returned dentry. |
| 2017 | * |
| 2018 | * NOTE! We do a "raw" seqcount_begin here. That means that |
| 2019 | * we don't wait for the sequence count to stabilize if it |
| 2020 | * is in the middle of a sequence change. If we do the slow |
| 2021 | * dentry compare, we will do seqretries until it is stable, |
| 2022 | * and if we end up with a successful lookup, we actually |
| 2023 | * want to exit RCU lookup anyway. |
| 2024 | */ |
| 2025 | seq = raw_seqcount_begin(&dentry->d_seq); |
| 2026 | if (dentry->d_parent != parent) |
| 2027 | continue; |
| 2028 | if (d_unhashed(dentry)) |
| 2029 | continue; |
| 2030 | |
| 2031 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
| 2032 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
| 2033 | continue; |
| 2034 | *seqp = seq; |
| 2035 | switch (slow_dentry_cmp(parent, dentry, seq, name)) { |
| 2036 | case D_COMP_OK: |
| 2037 | return dentry; |
| 2038 | case D_COMP_NOMATCH: |
| 2039 | continue; |
| 2040 | default: |
| 2041 | goto seqretry; |
| 2042 | } |
| 2043 | } |
| 2044 | |
| 2045 | if (dentry->d_name.hash_len != hashlen) |
| 2046 | continue; |
| 2047 | *seqp = seq; |
| 2048 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
| 2049 | return dentry; |
| 2050 | } |
| 2051 | return NULL; |
| 2052 | } |
| 2053 | |
| 2054 | /** |
| 2055 | * d_lookup - search for a dentry |
| 2056 | * @parent: parent dentry |
| 2057 | * @name: qstr of name we wish to find |
| 2058 | * Returns: dentry, or NULL |
| 2059 | * |
| 2060 | * d_lookup searches the children of the parent dentry for the name in |
| 2061 | * question. If the dentry is found its reference count is incremented and the |
| 2062 | * dentry is returned. The caller must use dput to free the entry when it has |
| 2063 | * finished using it. %NULL is returned if the dentry does not exist. |
| 2064 | */ |
| 2065 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
| 2066 | { |
| 2067 | struct dentry *dentry; |
| 2068 | unsigned seq; |
| 2069 | |
| 2070 | do { |
| 2071 | seq = read_seqbegin(&rename_lock); |
| 2072 | dentry = __d_lookup(parent, name); |
| 2073 | if (dentry) |
| 2074 | break; |
| 2075 | } while (read_seqretry(&rename_lock, seq)); |
| 2076 | return dentry; |
| 2077 | } |
| 2078 | EXPORT_SYMBOL(d_lookup); |
| 2079 | |
| 2080 | /** |
| 2081 | * __d_lookup - search for a dentry (racy) |
| 2082 | * @parent: parent dentry |
| 2083 | * @name: qstr of name we wish to find |
| 2084 | * Returns: dentry, or NULL |
| 2085 | * |
| 2086 | * __d_lookup is like d_lookup, however it may (rarely) return a |
| 2087 | * false-negative result due to unrelated rename activity. |
| 2088 | * |
| 2089 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
| 2090 | * however it must be used carefully, eg. with a following d_lookup in |
| 2091 | * the case of failure. |
| 2092 | * |
| 2093 | * __d_lookup callers must be commented. |
| 2094 | */ |
| 2095 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
| 2096 | { |
| 2097 | unsigned int len = name->len; |
| 2098 | unsigned int hash = name->hash; |
| 2099 | const unsigned char *str = name->name; |
| 2100 | struct hlist_bl_head *b = d_hash(parent, hash); |
| 2101 | struct hlist_bl_node *node; |
| 2102 | struct dentry *found = NULL; |
| 2103 | struct dentry *dentry; |
| 2104 | |
| 2105 | /* |
| 2106 | * Note: There is significant duplication with __d_lookup_rcu which is |
| 2107 | * required to prevent single threaded performance regressions |
| 2108 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
| 2109 | * Keep the two functions in sync. |
| 2110 | */ |
| 2111 | |
| 2112 | /* |
| 2113 | * The hash list is protected using RCU. |
| 2114 | * |
| 2115 | * Take d_lock when comparing a candidate dentry, to avoid races |
| 2116 | * with d_move(). |
| 2117 | * |
| 2118 | * It is possible that concurrent renames can mess up our list |
| 2119 | * walk here and result in missing our dentry, resulting in the |
| 2120 | * false-negative result. d_lookup() protects against concurrent |
| 2121 | * renames using rename_lock seqlock. |
| 2122 | * |
| 2123 | * See Documentation/filesystems/path-lookup.txt for more details. |
| 2124 | */ |
| 2125 | rcu_read_lock(); |
| 2126 | |
| 2127 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
| 2128 | |
| 2129 | if (dentry->d_name.hash != hash) |
| 2130 | continue; |
| 2131 | |
| 2132 | spin_lock(&dentry->d_lock); |
| 2133 | if (dentry->d_parent != parent) |
| 2134 | goto next; |
| 2135 | if (d_unhashed(dentry)) |
| 2136 | goto next; |
| 2137 | |
| 2138 | /* |
| 2139 | * It is safe to compare names since d_move() cannot |
| 2140 | * change the qstr (protected by d_lock). |
| 2141 | */ |
| 2142 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
| 2143 | int tlen = dentry->d_name.len; |
| 2144 | const char *tname = dentry->d_name.name; |
| 2145 | if (parent->d_op->d_compare(parent, dentry, tlen, tname, name)) |
| 2146 | goto next; |
| 2147 | } else { |
| 2148 | if (dentry->d_name.len != len) |
| 2149 | goto next; |
| 2150 | if (dentry_cmp(dentry, str, len)) |
| 2151 | goto next; |
| 2152 | } |
| 2153 | |
| 2154 | dentry->d_lockref.count++; |
| 2155 | found = dentry; |
| 2156 | spin_unlock(&dentry->d_lock); |
| 2157 | break; |
| 2158 | next: |
| 2159 | spin_unlock(&dentry->d_lock); |
| 2160 | } |
| 2161 | rcu_read_unlock(); |
| 2162 | |
| 2163 | return found; |
| 2164 | } |
| 2165 | |
| 2166 | /** |
| 2167 | * d_hash_and_lookup - hash the qstr then search for a dentry |
| 2168 | * @dir: Directory to search in |
| 2169 | * @name: qstr of name we wish to find |
| 2170 | * |
| 2171 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
| 2172 | */ |
| 2173 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
| 2174 | { |
| 2175 | /* |
| 2176 | * Check for a fs-specific hash function. Note that we must |
| 2177 | * calculate the standard hash first, as the d_op->d_hash() |
| 2178 | * routine may choose to leave the hash value unchanged. |
| 2179 | */ |
| 2180 | name->hash = full_name_hash(name->name, name->len); |
| 2181 | if (dir->d_flags & DCACHE_OP_HASH) { |
| 2182 | int err = dir->d_op->d_hash(dir, name); |
| 2183 | if (unlikely(err < 0)) |
| 2184 | return ERR_PTR(err); |
| 2185 | } |
| 2186 | return d_lookup(dir, name); |
| 2187 | } |
| 2188 | EXPORT_SYMBOL(d_hash_and_lookup); |
| 2189 | |
| 2190 | /** |
| 2191 | * d_validate - verify dentry provided from insecure source (deprecated) |
| 2192 | * @dentry: The dentry alleged to be valid child of @dparent |
| 2193 | * @dparent: The parent dentry (known to be valid) |
| 2194 | * |
| 2195 | * An insecure source has sent us a dentry, here we verify it and dget() it. |
| 2196 | * This is used by ncpfs in its readdir implementation. |
| 2197 | * Zero is returned in the dentry is invalid. |
| 2198 | * |
| 2199 | * This function is slow for big directories, and deprecated, do not use it. |
| 2200 | */ |
| 2201 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
| 2202 | { |
| 2203 | struct dentry *child; |
| 2204 | |
| 2205 | spin_lock(&dparent->d_lock); |
| 2206 | list_for_each_entry(child, &dparent->d_subdirs, d_child) { |
| 2207 | if (dentry == child) { |
| 2208 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| 2209 | __dget_dlock(dentry); |
| 2210 | spin_unlock(&dentry->d_lock); |
| 2211 | spin_unlock(&dparent->d_lock); |
| 2212 | return 1; |
| 2213 | } |
| 2214 | } |
| 2215 | spin_unlock(&dparent->d_lock); |
| 2216 | |
| 2217 | return 0; |
| 2218 | } |
| 2219 | EXPORT_SYMBOL(d_validate); |
| 2220 | |
| 2221 | /* |
| 2222 | * When a file is deleted, we have two options: |
| 2223 | * - turn this dentry into a negative dentry |
| 2224 | * - unhash this dentry and free it. |
| 2225 | * |
| 2226 | * Usually, we want to just turn this into |
| 2227 | * a negative dentry, but if anybody else is |
| 2228 | * currently using the dentry or the inode |
| 2229 | * we can't do that and we fall back on removing |
| 2230 | * it from the hash queues and waiting for |
| 2231 | * it to be deleted later when it has no users |
| 2232 | */ |
| 2233 | |
| 2234 | /** |
| 2235 | * d_delete - delete a dentry |
| 2236 | * @dentry: The dentry to delete |
| 2237 | * |
| 2238 | * Turn the dentry into a negative dentry if possible, otherwise |
| 2239 | * remove it from the hash queues so it can be deleted later |
| 2240 | */ |
| 2241 | |
| 2242 | void d_delete(struct dentry * dentry) |
| 2243 | { |
| 2244 | struct inode *inode; |
| 2245 | int isdir = 0; |
| 2246 | /* |
| 2247 | * Are we the only user? |
| 2248 | */ |
| 2249 | again: |
| 2250 | spin_lock(&dentry->d_lock); |
| 2251 | inode = dentry->d_inode; |
| 2252 | isdir = S_ISDIR(inode->i_mode); |
| 2253 | if (dentry->d_lockref.count == 1) { |
| 2254 | if (!spin_trylock(&inode->i_lock)) { |
| 2255 | spin_unlock(&dentry->d_lock); |
| 2256 | cpu_relax(); |
| 2257 | goto again; |
| 2258 | } |
| 2259 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
| 2260 | dentry_unlink_inode(dentry); |
| 2261 | fsnotify_nameremove(dentry, isdir); |
| 2262 | return; |
| 2263 | } |
| 2264 | |
| 2265 | if (!d_unhashed(dentry)) |
| 2266 | __d_drop(dentry); |
| 2267 | |
| 2268 | spin_unlock(&dentry->d_lock); |
| 2269 | |
| 2270 | fsnotify_nameremove(dentry, isdir); |
| 2271 | } |
| 2272 | EXPORT_SYMBOL(d_delete); |
| 2273 | |
| 2274 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
| 2275 | { |
| 2276 | BUG_ON(!d_unhashed(entry)); |
| 2277 | hlist_bl_lock(b); |
| 2278 | entry->d_flags |= DCACHE_RCUACCESS; |
| 2279 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
| 2280 | hlist_bl_unlock(b); |
| 2281 | } |
| 2282 | |
| 2283 | static void _d_rehash(struct dentry * entry) |
| 2284 | { |
| 2285 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
| 2286 | } |
| 2287 | |
| 2288 | /** |
| 2289 | * d_rehash - add an entry back to the hash |
| 2290 | * @entry: dentry to add to the hash |
| 2291 | * |
| 2292 | * Adds a dentry to the hash according to its name. |
| 2293 | */ |
| 2294 | |
| 2295 | void d_rehash(struct dentry * entry) |
| 2296 | { |
| 2297 | spin_lock(&entry->d_lock); |
| 2298 | _d_rehash(entry); |
| 2299 | spin_unlock(&entry->d_lock); |
| 2300 | } |
| 2301 | EXPORT_SYMBOL(d_rehash); |
| 2302 | |
| 2303 | /** |
| 2304 | * dentry_update_name_case - update case insensitive dentry with a new name |
| 2305 | * @dentry: dentry to be updated |
| 2306 | * @name: new name |
| 2307 | * |
| 2308 | * Update a case insensitive dentry with new case of name. |
| 2309 | * |
| 2310 | * dentry must have been returned by d_lookup with name @name. Old and new |
| 2311 | * name lengths must match (ie. no d_compare which allows mismatched name |
| 2312 | * lengths). |
| 2313 | * |
| 2314 | * Parent inode i_mutex must be held over d_lookup and into this call (to |
| 2315 | * keep renames and concurrent inserts, and readdir(2) away). |
| 2316 | */ |
| 2317 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
| 2318 | { |
| 2319 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
| 2320 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
| 2321 | |
| 2322 | spin_lock(&dentry->d_lock); |
| 2323 | write_seqcount_begin(&dentry->d_seq); |
| 2324 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
| 2325 | write_seqcount_end(&dentry->d_seq); |
| 2326 | spin_unlock(&dentry->d_lock); |
| 2327 | } |
| 2328 | EXPORT_SYMBOL(dentry_update_name_case); |
| 2329 | |
| 2330 | static void swap_names(struct dentry *dentry, struct dentry *target) |
| 2331 | { |
| 2332 | if (unlikely(dname_external(target))) { |
| 2333 | if (unlikely(dname_external(dentry))) { |
| 2334 | /* |
| 2335 | * Both external: swap the pointers |
| 2336 | */ |
| 2337 | swap(target->d_name.name, dentry->d_name.name); |
| 2338 | } else { |
| 2339 | /* |
| 2340 | * dentry:internal, target:external. Steal target's |
| 2341 | * storage and make target internal. |
| 2342 | */ |
| 2343 | memcpy(target->d_iname, dentry->d_name.name, |
| 2344 | dentry->d_name.len + 1); |
| 2345 | dentry->d_name.name = target->d_name.name; |
| 2346 | target->d_name.name = target->d_iname; |
| 2347 | } |
| 2348 | } else { |
| 2349 | if (unlikely(dname_external(dentry))) { |
| 2350 | /* |
| 2351 | * dentry:external, target:internal. Give dentry's |
| 2352 | * storage to target and make dentry internal |
| 2353 | */ |
| 2354 | memcpy(dentry->d_iname, target->d_name.name, |
| 2355 | target->d_name.len + 1); |
| 2356 | target->d_name.name = dentry->d_name.name; |
| 2357 | dentry->d_name.name = dentry->d_iname; |
| 2358 | } else { |
| 2359 | /* |
| 2360 | * Both are internal. |
| 2361 | */ |
| 2362 | unsigned int i; |
| 2363 | BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); |
| 2364 | kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN); |
| 2365 | kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN); |
| 2366 | for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { |
| 2367 | swap(((long *) &dentry->d_iname)[i], |
| 2368 | ((long *) &target->d_iname)[i]); |
| 2369 | } |
| 2370 | } |
| 2371 | } |
| 2372 | swap(dentry->d_name.hash_len, target->d_name.hash_len); |
| 2373 | } |
| 2374 | |
| 2375 | static void copy_name(struct dentry *dentry, struct dentry *target) |
| 2376 | { |
| 2377 | struct external_name *old_name = NULL; |
| 2378 | if (unlikely(dname_external(dentry))) |
| 2379 | old_name = external_name(dentry); |
| 2380 | if (unlikely(dname_external(target))) { |
| 2381 | atomic_inc(&external_name(target)->u.count); |
| 2382 | dentry->d_name = target->d_name; |
| 2383 | } else { |
| 2384 | memcpy(dentry->d_iname, target->d_name.name, |
| 2385 | target->d_name.len + 1); |
| 2386 | dentry->d_name.name = dentry->d_iname; |
| 2387 | dentry->d_name.hash_len = target->d_name.hash_len; |
| 2388 | } |
| 2389 | if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) |
| 2390 | kfree_rcu(old_name, u.head); |
| 2391 | } |
| 2392 | |
| 2393 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
| 2394 | { |
| 2395 | /* |
| 2396 | * XXXX: do we really need to take target->d_lock? |
| 2397 | */ |
| 2398 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) |
| 2399 | spin_lock(&target->d_parent->d_lock); |
| 2400 | else { |
| 2401 | if (d_ancestor(dentry->d_parent, target->d_parent)) { |
| 2402 | spin_lock(&dentry->d_parent->d_lock); |
| 2403 | spin_lock_nested(&target->d_parent->d_lock, |
| 2404 | DENTRY_D_LOCK_NESTED); |
| 2405 | } else { |
| 2406 | spin_lock(&target->d_parent->d_lock); |
| 2407 | spin_lock_nested(&dentry->d_parent->d_lock, |
| 2408 | DENTRY_D_LOCK_NESTED); |
| 2409 | } |
| 2410 | } |
| 2411 | if (target < dentry) { |
| 2412 | spin_lock_nested(&target->d_lock, 2); |
| 2413 | spin_lock_nested(&dentry->d_lock, 3); |
| 2414 | } else { |
| 2415 | spin_lock_nested(&dentry->d_lock, 2); |
| 2416 | spin_lock_nested(&target->d_lock, 3); |
| 2417 | } |
| 2418 | } |
| 2419 | |
| 2420 | static void dentry_unlock_for_move(struct dentry *dentry, struct dentry *target) |
| 2421 | { |
| 2422 | if (target->d_parent != dentry->d_parent) |
| 2423 | spin_unlock(&dentry->d_parent->d_lock); |
| 2424 | if (target->d_parent != target) |
| 2425 | spin_unlock(&target->d_parent->d_lock); |
| 2426 | spin_unlock(&target->d_lock); |
| 2427 | spin_unlock(&dentry->d_lock); |
| 2428 | } |
| 2429 | |
| 2430 | /* |
| 2431 | * When switching names, the actual string doesn't strictly have to |
| 2432 | * be preserved in the target - because we're dropping the target |
| 2433 | * anyway. As such, we can just do a simple memcpy() to copy over |
| 2434 | * the new name before we switch, unless we are going to rehash |
| 2435 | * it. Note that if we *do* unhash the target, we are not allowed |
| 2436 | * to rehash it without giving it a new name/hash key - whether |
| 2437 | * we swap or overwrite the names here, resulting name won't match |
| 2438 | * the reality in filesystem; it's only there for d_path() purposes. |
| 2439 | * Note that all of this is happening under rename_lock, so the |
| 2440 | * any hash lookup seeing it in the middle of manipulations will |
| 2441 | * be discarded anyway. So we do not care what happens to the hash |
| 2442 | * key in that case. |
| 2443 | */ |
| 2444 | /* |
| 2445 | * __d_move - move a dentry |
| 2446 | * @dentry: entry to move |
| 2447 | * @target: new dentry |
| 2448 | * @exchange: exchange the two dentries |
| 2449 | * |
| 2450 | * Update the dcache to reflect the move of a file name. Negative |
| 2451 | * dcache entries should not be moved in this way. Caller must hold |
| 2452 | * rename_lock, the i_mutex of the source and target directories, |
| 2453 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). |
| 2454 | */ |
| 2455 | static void __d_move(struct dentry *dentry, struct dentry *target, |
| 2456 | bool exchange) |
| 2457 | { |
| 2458 | if (!dentry->d_inode) |
| 2459 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
| 2460 | |
| 2461 | BUG_ON(d_ancestor(dentry, target)); |
| 2462 | BUG_ON(d_ancestor(target, dentry)); |
| 2463 | |
| 2464 | dentry_lock_for_move(dentry, target); |
| 2465 | |
| 2466 | write_seqcount_begin(&dentry->d_seq); |
| 2467 | write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); |
| 2468 | |
| 2469 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
| 2470 | |
| 2471 | /* |
| 2472 | * Move the dentry to the target hash queue. Don't bother checking |
| 2473 | * for the same hash queue because of how unlikely it is. |
| 2474 | */ |
| 2475 | __d_drop(dentry); |
| 2476 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
| 2477 | |
| 2478 | /* |
| 2479 | * Unhash the target (d_delete() is not usable here). If exchanging |
| 2480 | * the two dentries, then rehash onto the other's hash queue. |
| 2481 | */ |
| 2482 | __d_drop(target); |
| 2483 | if (exchange) { |
| 2484 | __d_rehash(target, |
| 2485 | d_hash(dentry->d_parent, dentry->d_name.hash)); |
| 2486 | } |
| 2487 | |
| 2488 | /* Switch the names.. */ |
| 2489 | if (exchange) |
| 2490 | swap_names(dentry, target); |
| 2491 | else |
| 2492 | copy_name(dentry, target); |
| 2493 | |
| 2494 | /* ... and switch them in the tree */ |
| 2495 | if (IS_ROOT(dentry)) { |
| 2496 | /* splicing a tree */ |
| 2497 | dentry->d_parent = target->d_parent; |
| 2498 | target->d_parent = target; |
| 2499 | list_del_init(&target->d_child); |
| 2500 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); |
| 2501 | } else { |
| 2502 | /* swapping two dentries */ |
| 2503 | swap(dentry->d_parent, target->d_parent); |
| 2504 | list_move(&target->d_child, &target->d_parent->d_subdirs); |
| 2505 | list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); |
| 2506 | if (exchange) |
| 2507 | fsnotify_d_move(target); |
| 2508 | fsnotify_d_move(dentry); |
| 2509 | } |
| 2510 | |
| 2511 | write_seqcount_end(&target->d_seq); |
| 2512 | write_seqcount_end(&dentry->d_seq); |
| 2513 | |
| 2514 | dentry_unlock_for_move(dentry, target); |
| 2515 | } |
| 2516 | |
| 2517 | /* |
| 2518 | * d_move - move a dentry |
| 2519 | * @dentry: entry to move |
| 2520 | * @target: new dentry |
| 2521 | * |
| 2522 | * Update the dcache to reflect the move of a file name. Negative |
| 2523 | * dcache entries should not be moved in this way. See the locking |
| 2524 | * requirements for __d_move. |
| 2525 | */ |
| 2526 | void d_move(struct dentry *dentry, struct dentry *target) |
| 2527 | { |
| 2528 | write_seqlock(&rename_lock); |
| 2529 | __d_move(dentry, target, false); |
| 2530 | write_sequnlock(&rename_lock); |
| 2531 | } |
| 2532 | EXPORT_SYMBOL(d_move); |
| 2533 | |
| 2534 | /* |
| 2535 | * d_exchange - exchange two dentries |
| 2536 | * @dentry1: first dentry |
| 2537 | * @dentry2: second dentry |
| 2538 | */ |
| 2539 | void d_exchange(struct dentry *dentry1, struct dentry *dentry2) |
| 2540 | { |
| 2541 | write_seqlock(&rename_lock); |
| 2542 | |
| 2543 | WARN_ON(!dentry1->d_inode); |
| 2544 | WARN_ON(!dentry2->d_inode); |
| 2545 | WARN_ON(IS_ROOT(dentry1)); |
| 2546 | WARN_ON(IS_ROOT(dentry2)); |
| 2547 | |
| 2548 | __d_move(dentry1, dentry2, true); |
| 2549 | |
| 2550 | write_sequnlock(&rename_lock); |
| 2551 | } |
| 2552 | |
| 2553 | /** |
| 2554 | * d_ancestor - search for an ancestor |
| 2555 | * @p1: ancestor dentry |
| 2556 | * @p2: child dentry |
| 2557 | * |
| 2558 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
| 2559 | * an ancestor of p2, else NULL. |
| 2560 | */ |
| 2561 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
| 2562 | { |
| 2563 | struct dentry *p; |
| 2564 | |
| 2565 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
| 2566 | if (p->d_parent == p1) |
| 2567 | return p; |
| 2568 | } |
| 2569 | return NULL; |
| 2570 | } |
| 2571 | |
| 2572 | /* |
| 2573 | * This helper attempts to cope with remotely renamed directories |
| 2574 | * |
| 2575 | * It assumes that the caller is already holding |
| 2576 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
| 2577 | * |
| 2578 | * Note: If ever the locking in lock_rename() changes, then please |
| 2579 | * remember to update this too... |
| 2580 | */ |
| 2581 | static int __d_unalias(struct inode *inode, |
| 2582 | struct dentry *dentry, struct dentry *alias) |
| 2583 | { |
| 2584 | struct mutex *m1 = NULL, *m2 = NULL; |
| 2585 | int ret = -EBUSY; |
| 2586 | |
| 2587 | /* If alias and dentry share a parent, then no extra locks required */ |
| 2588 | if (alias->d_parent == dentry->d_parent) |
| 2589 | goto out_unalias; |
| 2590 | |
| 2591 | /* See lock_rename() */ |
| 2592 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
| 2593 | goto out_err; |
| 2594 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
| 2595 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
| 2596 | goto out_err; |
| 2597 | m2 = &alias->d_parent->d_inode->i_mutex; |
| 2598 | out_unalias: |
| 2599 | __d_move(alias, dentry, false); |
| 2600 | ret = 0; |
| 2601 | out_err: |
| 2602 | spin_unlock(&inode->i_lock); |
| 2603 | if (m2) |
| 2604 | mutex_unlock(m2); |
| 2605 | if (m1) |
| 2606 | mutex_unlock(m1); |
| 2607 | return ret; |
| 2608 | } |
| 2609 | |
| 2610 | /** |
| 2611 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
| 2612 | * @inode: the inode which may have a disconnected dentry |
| 2613 | * @dentry: a negative dentry which we want to point to the inode. |
| 2614 | * |
| 2615 | * If inode is a directory and has an IS_ROOT alias, then d_move that in |
| 2616 | * place of the given dentry and return it, else simply d_add the inode |
| 2617 | * to the dentry and return NULL. |
| 2618 | * |
| 2619 | * If a non-IS_ROOT directory is found, the filesystem is corrupt, and |
| 2620 | * we should error out: directories can't have multiple aliases. |
| 2621 | * |
| 2622 | * This is needed in the lookup routine of any filesystem that is exportable |
| 2623 | * (via knfsd) so that we can build dcache paths to directories effectively. |
| 2624 | * |
| 2625 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
| 2626 | * is returned. This matches the expected return value of ->lookup. |
| 2627 | * |
| 2628 | * Cluster filesystems may call this function with a negative, hashed dentry. |
| 2629 | * In that case, we know that the inode will be a regular file, and also this |
| 2630 | * will only occur during atomic_open. So we need to check for the dentry |
| 2631 | * being already hashed only in the final case. |
| 2632 | */ |
| 2633 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
| 2634 | { |
| 2635 | if (IS_ERR(inode)) |
| 2636 | return ERR_CAST(inode); |
| 2637 | |
| 2638 | BUG_ON(!d_unhashed(dentry)); |
| 2639 | |
| 2640 | if (!inode) { |
| 2641 | __d_instantiate(dentry, NULL); |
| 2642 | goto out; |
| 2643 | } |
| 2644 | spin_lock(&inode->i_lock); |
| 2645 | if (S_ISDIR(inode->i_mode)) { |
| 2646 | struct dentry *new = __d_find_any_alias(inode); |
| 2647 | if (unlikely(new)) { |
| 2648 | write_seqlock(&rename_lock); |
| 2649 | if (unlikely(d_ancestor(new, dentry))) { |
| 2650 | write_sequnlock(&rename_lock); |
| 2651 | spin_unlock(&inode->i_lock); |
| 2652 | dput(new); |
| 2653 | new = ERR_PTR(-ELOOP); |
| 2654 | pr_warn_ratelimited( |
| 2655 | "VFS: Lookup of '%s' in %s %s" |
| 2656 | " would have caused loop\n", |
| 2657 | dentry->d_name.name, |
| 2658 | inode->i_sb->s_type->name, |
| 2659 | inode->i_sb->s_id); |
| 2660 | } else if (!IS_ROOT(new)) { |
| 2661 | int err = __d_unalias(inode, dentry, new); |
| 2662 | write_sequnlock(&rename_lock); |
| 2663 | if (err) { |
| 2664 | dput(new); |
| 2665 | new = ERR_PTR(err); |
| 2666 | } |
| 2667 | } else { |
| 2668 | __d_move(new, dentry, false); |
| 2669 | write_sequnlock(&rename_lock); |
| 2670 | spin_unlock(&inode->i_lock); |
| 2671 | security_d_instantiate(new, inode); |
| 2672 | } |
| 2673 | iput(inode); |
| 2674 | return new; |
| 2675 | } |
| 2676 | } |
| 2677 | /* already taking inode->i_lock, so d_add() by hand */ |
| 2678 | __d_instantiate(dentry, inode); |
| 2679 | spin_unlock(&inode->i_lock); |
| 2680 | out: |
| 2681 | security_d_instantiate(dentry, inode); |
| 2682 | d_rehash(dentry); |
| 2683 | return NULL; |
| 2684 | } |
| 2685 | EXPORT_SYMBOL(d_splice_alias); |
| 2686 | |
| 2687 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
| 2688 | { |
| 2689 | *buflen -= namelen; |
| 2690 | if (*buflen < 0) |
| 2691 | return -ENAMETOOLONG; |
| 2692 | *buffer -= namelen; |
| 2693 | memcpy(*buffer, str, namelen); |
| 2694 | return 0; |
| 2695 | } |
| 2696 | |
| 2697 | /** |
| 2698 | * prepend_name - prepend a pathname in front of current buffer pointer |
| 2699 | * @buffer: buffer pointer |
| 2700 | * @buflen: allocated length of the buffer |
| 2701 | * @name: name string and length qstr structure |
| 2702 | * |
| 2703 | * With RCU path tracing, it may race with d_move(). Use ACCESS_ONCE() to |
| 2704 | * make sure that either the old or the new name pointer and length are |
| 2705 | * fetched. However, there may be mismatch between length and pointer. |
| 2706 | * The length cannot be trusted, we need to copy it byte-by-byte until |
| 2707 | * the length is reached or a null byte is found. It also prepends "/" at |
| 2708 | * the beginning of the name. The sequence number check at the caller will |
| 2709 | * retry it again when a d_move() does happen. So any garbage in the buffer |
| 2710 | * due to mismatched pointer and length will be discarded. |
| 2711 | * |
| 2712 | * Data dependency barrier is needed to make sure that we see that terminating |
| 2713 | * NUL. Alpha strikes again, film at 11... |
| 2714 | */ |
| 2715 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
| 2716 | { |
| 2717 | const char *dname = ACCESS_ONCE(name->name); |
| 2718 | u32 dlen = ACCESS_ONCE(name->len); |
| 2719 | char *p; |
| 2720 | |
| 2721 | smp_read_barrier_depends(); |
| 2722 | |
| 2723 | *buflen -= dlen + 1; |
| 2724 | if (*buflen < 0) |
| 2725 | return -ENAMETOOLONG; |
| 2726 | p = *buffer -= dlen + 1; |
| 2727 | *p++ = '/'; |
| 2728 | while (dlen--) { |
| 2729 | char c = *dname++; |
| 2730 | if (!c) |
| 2731 | break; |
| 2732 | *p++ = c; |
| 2733 | } |
| 2734 | return 0; |
| 2735 | } |
| 2736 | |
| 2737 | /** |
| 2738 | * prepend_path - Prepend path string to a buffer |
| 2739 | * @path: the dentry/vfsmount to report |
| 2740 | * @root: root vfsmnt/dentry |
| 2741 | * @buffer: pointer to the end of the buffer |
| 2742 | * @buflen: pointer to buffer length |
| 2743 | * |
| 2744 | * The function will first try to write out the pathname without taking any |
| 2745 | * lock other than the RCU read lock to make sure that dentries won't go away. |
| 2746 | * It only checks the sequence number of the global rename_lock as any change |
| 2747 | * in the dentry's d_seq will be preceded by changes in the rename_lock |
| 2748 | * sequence number. If the sequence number had been changed, it will restart |
| 2749 | * the whole pathname back-tracing sequence again by taking the rename_lock. |
| 2750 | * In this case, there is no need to take the RCU read lock as the recursive |
| 2751 | * parent pointer references will keep the dentry chain alive as long as no |
| 2752 | * rename operation is performed. |
| 2753 | */ |
| 2754 | static int prepend_path(const struct path *path, |
| 2755 | const struct path *root, |
| 2756 | char **buffer, int *buflen) |
| 2757 | { |
| 2758 | struct dentry *dentry; |
| 2759 | struct vfsmount *vfsmnt; |
| 2760 | struct mount *mnt; |
| 2761 | int error = 0; |
| 2762 | unsigned seq, m_seq = 0; |
| 2763 | char *bptr; |
| 2764 | int blen; |
| 2765 | |
| 2766 | rcu_read_lock(); |
| 2767 | restart_mnt: |
| 2768 | read_seqbegin_or_lock(&mount_lock, &m_seq); |
| 2769 | seq = 0; |
| 2770 | rcu_read_lock(); |
| 2771 | restart: |
| 2772 | bptr = *buffer; |
| 2773 | blen = *buflen; |
| 2774 | error = 0; |
| 2775 | dentry = path->dentry; |
| 2776 | vfsmnt = path->mnt; |
| 2777 | mnt = real_mount(vfsmnt); |
| 2778 | read_seqbegin_or_lock(&rename_lock, &seq); |
| 2779 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
| 2780 | struct dentry * parent; |
| 2781 | |
| 2782 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
| 2783 | struct mount *parent = ACCESS_ONCE(mnt->mnt_parent); |
| 2784 | /* Global root? */ |
| 2785 | if (mnt != parent) { |
| 2786 | dentry = ACCESS_ONCE(mnt->mnt_mountpoint); |
| 2787 | mnt = parent; |
| 2788 | vfsmnt = &mnt->mnt; |
| 2789 | continue; |
| 2790 | } |
| 2791 | /* |
| 2792 | * Filesystems needing to implement special "root names" |
| 2793 | * should do so with ->d_dname() |
| 2794 | */ |
| 2795 | if (IS_ROOT(dentry) && |
| 2796 | (dentry->d_name.len != 1 || |
| 2797 | dentry->d_name.name[0] != '/')) { |
| 2798 | WARN(1, "Root dentry has weird name <%.*s>\n", |
| 2799 | (int) dentry->d_name.len, |
| 2800 | dentry->d_name.name); |
| 2801 | } |
| 2802 | if (!error) |
| 2803 | error = is_mounted(vfsmnt) ? 1 : 2; |
| 2804 | break; |
| 2805 | } |
| 2806 | parent = dentry->d_parent; |
| 2807 | prefetch(parent); |
| 2808 | error = prepend_name(&bptr, &blen, &dentry->d_name); |
| 2809 | if (error) |
| 2810 | break; |
| 2811 | |
| 2812 | dentry = parent; |
| 2813 | } |
| 2814 | if (!(seq & 1)) |
| 2815 | rcu_read_unlock(); |
| 2816 | if (need_seqretry(&rename_lock, seq)) { |
| 2817 | seq = 1; |
| 2818 | goto restart; |
| 2819 | } |
| 2820 | done_seqretry(&rename_lock, seq); |
| 2821 | |
| 2822 | if (!(m_seq & 1)) |
| 2823 | rcu_read_unlock(); |
| 2824 | if (need_seqretry(&mount_lock, m_seq)) { |
| 2825 | m_seq = 1; |
| 2826 | goto restart_mnt; |
| 2827 | } |
| 2828 | done_seqretry(&mount_lock, m_seq); |
| 2829 | |
| 2830 | if (error >= 0 && bptr == *buffer) { |
| 2831 | if (--blen < 0) |
| 2832 | error = -ENAMETOOLONG; |
| 2833 | else |
| 2834 | *--bptr = '/'; |
| 2835 | } |
| 2836 | *buffer = bptr; |
| 2837 | *buflen = blen; |
| 2838 | return error; |
| 2839 | } |
| 2840 | |
| 2841 | /** |
| 2842 | * __d_path - return the path of a dentry |
| 2843 | * @path: the dentry/vfsmount to report |
| 2844 | * @root: root vfsmnt/dentry |
| 2845 | * @buf: buffer to return value in |
| 2846 | * @buflen: buffer length |
| 2847 | * |
| 2848 | * Convert a dentry into an ASCII path name. |
| 2849 | * |
| 2850 | * Returns a pointer into the buffer or an error code if the |
| 2851 | * path was too long. |
| 2852 | * |
| 2853 | * "buflen" should be positive. |
| 2854 | * |
| 2855 | * If the path is not reachable from the supplied root, return %NULL. |
| 2856 | */ |
| 2857 | char *__d_path(const struct path *path, |
| 2858 | const struct path *root, |
| 2859 | char *buf, int buflen) |
| 2860 | { |
| 2861 | char *res = buf + buflen; |
| 2862 | int error; |
| 2863 | |
| 2864 | prepend(&res, &buflen, "\0", 1); |
| 2865 | error = prepend_path(path, root, &res, &buflen); |
| 2866 | |
| 2867 | if (error < 0) |
| 2868 | return ERR_PTR(error); |
| 2869 | if (error > 0) |
| 2870 | return NULL; |
| 2871 | return res; |
| 2872 | } |
| 2873 | |
| 2874 | char *d_absolute_path(const struct path *path, |
| 2875 | char *buf, int buflen) |
| 2876 | { |
| 2877 | struct path root = {}; |
| 2878 | char *res = buf + buflen; |
| 2879 | int error; |
| 2880 | |
| 2881 | prepend(&res, &buflen, "\0", 1); |
| 2882 | error = prepend_path(path, &root, &res, &buflen); |
| 2883 | |
| 2884 | if (error > 1) |
| 2885 | error = -EINVAL; |
| 2886 | if (error < 0) |
| 2887 | return ERR_PTR(error); |
| 2888 | return res; |
| 2889 | } |
| 2890 | |
| 2891 | /* |
| 2892 | * same as __d_path but appends "(deleted)" for unlinked files. |
| 2893 | */ |
| 2894 | static int path_with_deleted(const struct path *path, |
| 2895 | const struct path *root, |
| 2896 | char **buf, int *buflen) |
| 2897 | { |
| 2898 | prepend(buf, buflen, "\0", 1); |
| 2899 | if (d_unlinked(path->dentry)) { |
| 2900 | int error = prepend(buf, buflen, " (deleted)", 10); |
| 2901 | if (error) |
| 2902 | return error; |
| 2903 | } |
| 2904 | |
| 2905 | return prepend_path(path, root, buf, buflen); |
| 2906 | } |
| 2907 | |
| 2908 | static int prepend_unreachable(char **buffer, int *buflen) |
| 2909 | { |
| 2910 | return prepend(buffer, buflen, "(unreachable)", 13); |
| 2911 | } |
| 2912 | |
| 2913 | static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) |
| 2914 | { |
| 2915 | unsigned seq; |
| 2916 | |
| 2917 | do { |
| 2918 | seq = read_seqcount_begin(&fs->seq); |
| 2919 | *root = fs->root; |
| 2920 | } while (read_seqcount_retry(&fs->seq, seq)); |
| 2921 | } |
| 2922 | |
| 2923 | /** |
| 2924 | * d_path - return the path of a dentry |
| 2925 | * @path: path to report |
| 2926 | * @buf: buffer to return value in |
| 2927 | * @buflen: buffer length |
| 2928 | * |
| 2929 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
| 2930 | * the string " (deleted)" is appended. Note that this is ambiguous. |
| 2931 | * |
| 2932 | * Returns a pointer into the buffer or an error code if the path was |
| 2933 | * too long. Note: Callers should use the returned pointer, not the passed |
| 2934 | * in buffer, to use the name! The implementation often starts at an offset |
| 2935 | * into the buffer, and may leave 0 bytes at the start. |
| 2936 | * |
| 2937 | * "buflen" should be positive. |
| 2938 | */ |
| 2939 | char *d_path(const struct path *path, char *buf, int buflen) |
| 2940 | { |
| 2941 | char *res = buf + buflen; |
| 2942 | struct path root; |
| 2943 | int error; |
| 2944 | |
| 2945 | /* |
| 2946 | * We have various synthetic filesystems that never get mounted. On |
| 2947 | * these filesystems dentries are never used for lookup purposes, and |
| 2948 | * thus don't need to be hashed. They also don't need a name until a |
| 2949 | * user wants to identify the object in /proc/pid/fd/. The little hack |
| 2950 | * below allows us to generate a name for these objects on demand: |
| 2951 | * |
| 2952 | * Some pseudo inodes are mountable. When they are mounted |
| 2953 | * path->dentry == path->mnt->mnt_root. In that case don't call d_dname |
| 2954 | * and instead have d_path return the mounted path. |
| 2955 | */ |
| 2956 | if (path->dentry->d_op && path->dentry->d_op->d_dname && |
| 2957 | (!IS_ROOT(path->dentry) || path->dentry != path->mnt->mnt_root)) |
| 2958 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
| 2959 | |
| 2960 | rcu_read_lock(); |
| 2961 | get_fs_root_rcu(current->fs, &root); |
| 2962 | error = path_with_deleted(path, &root, &res, &buflen); |
| 2963 | rcu_read_unlock(); |
| 2964 | |
| 2965 | if (error < 0) |
| 2966 | res = ERR_PTR(error); |
| 2967 | return res; |
| 2968 | } |
| 2969 | EXPORT_SYMBOL(d_path); |
| 2970 | |
| 2971 | /* |
| 2972 | * Helper function for dentry_operations.d_dname() members |
| 2973 | */ |
| 2974 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
| 2975 | const char *fmt, ...) |
| 2976 | { |
| 2977 | va_list args; |
| 2978 | char temp[64]; |
| 2979 | int sz; |
| 2980 | |
| 2981 | va_start(args, fmt); |
| 2982 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
| 2983 | va_end(args); |
| 2984 | |
| 2985 | if (sz > sizeof(temp) || sz > buflen) |
| 2986 | return ERR_PTR(-ENAMETOOLONG); |
| 2987 | |
| 2988 | buffer += buflen - sz; |
| 2989 | return memcpy(buffer, temp, sz); |
| 2990 | } |
| 2991 | |
| 2992 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen) |
| 2993 | { |
| 2994 | char *end = buffer + buflen; |
| 2995 | /* these dentries are never renamed, so d_lock is not needed */ |
| 2996 | if (prepend(&end, &buflen, " (deleted)", 11) || |
| 2997 | prepend(&end, &buflen, dentry->d_name.name, dentry->d_name.len) || |
| 2998 | prepend(&end, &buflen, "/", 1)) |
| 2999 | end = ERR_PTR(-ENAMETOOLONG); |
| 3000 | return end; |
| 3001 | } |
| 3002 | EXPORT_SYMBOL(simple_dname); |
| 3003 | |
| 3004 | /* |
| 3005 | * Write full pathname from the root of the filesystem into the buffer. |
| 3006 | */ |
| 3007 | static char *__dentry_path(struct dentry *d, char *buf, int buflen) |
| 3008 | { |
| 3009 | struct dentry *dentry; |
| 3010 | char *end, *retval; |
| 3011 | int len, seq = 0; |
| 3012 | int error = 0; |
| 3013 | |
| 3014 | if (buflen < 2) |
| 3015 | goto Elong; |
| 3016 | |
| 3017 | rcu_read_lock(); |
| 3018 | restart: |
| 3019 | dentry = d; |
| 3020 | end = buf + buflen; |
| 3021 | len = buflen; |
| 3022 | prepend(&end, &len, "\0", 1); |
| 3023 | /* Get '/' right */ |
| 3024 | retval = end-1; |
| 3025 | *retval = '/'; |
| 3026 | read_seqbegin_or_lock(&rename_lock, &seq); |
| 3027 | while (!IS_ROOT(dentry)) { |
| 3028 | struct dentry *parent = dentry->d_parent; |
| 3029 | |
| 3030 | prefetch(parent); |
| 3031 | error = prepend_name(&end, &len, &dentry->d_name); |
| 3032 | if (error) |
| 3033 | break; |
| 3034 | |
| 3035 | retval = end; |
| 3036 | dentry = parent; |
| 3037 | } |
| 3038 | if (!(seq & 1)) |
| 3039 | rcu_read_unlock(); |
| 3040 | if (need_seqretry(&rename_lock, seq)) { |
| 3041 | seq = 1; |
| 3042 | goto restart; |
| 3043 | } |
| 3044 | done_seqretry(&rename_lock, seq); |
| 3045 | if (error) |
| 3046 | goto Elong; |
| 3047 | return retval; |
| 3048 | Elong: |
| 3049 | return ERR_PTR(-ENAMETOOLONG); |
| 3050 | } |
| 3051 | |
| 3052 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
| 3053 | { |
| 3054 | return __dentry_path(dentry, buf, buflen); |
| 3055 | } |
| 3056 | EXPORT_SYMBOL(dentry_path_raw); |
| 3057 | |
| 3058 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
| 3059 | { |
| 3060 | char *p = NULL; |
| 3061 | char *retval; |
| 3062 | |
| 3063 | if (d_unlinked(dentry)) { |
| 3064 | p = buf + buflen; |
| 3065 | if (prepend(&p, &buflen, "//deleted", 10) != 0) |
| 3066 | goto Elong; |
| 3067 | buflen++; |
| 3068 | } |
| 3069 | retval = __dentry_path(dentry, buf, buflen); |
| 3070 | if (!IS_ERR(retval) && p) |
| 3071 | *p = '/'; /* restore '/' overriden with '\0' */ |
| 3072 | return retval; |
| 3073 | Elong: |
| 3074 | return ERR_PTR(-ENAMETOOLONG); |
| 3075 | } |
| 3076 | |
| 3077 | static void get_fs_root_and_pwd_rcu(struct fs_struct *fs, struct path *root, |
| 3078 | struct path *pwd) |
| 3079 | { |
| 3080 | unsigned seq; |
| 3081 | |
| 3082 | do { |
| 3083 | seq = read_seqcount_begin(&fs->seq); |
| 3084 | *root = fs->root; |
| 3085 | *pwd = fs->pwd; |
| 3086 | } while (read_seqcount_retry(&fs->seq, seq)); |
| 3087 | } |
| 3088 | |
| 3089 | /* |
| 3090 | * NOTE! The user-level library version returns a |
| 3091 | * character pointer. The kernel system call just |
| 3092 | * returns the length of the buffer filled (which |
| 3093 | * includes the ending '\0' character), or a negative |
| 3094 | * error value. So libc would do something like |
| 3095 | * |
| 3096 | * char *getcwd(char * buf, size_t size) |
| 3097 | * { |
| 3098 | * int retval; |
| 3099 | * |
| 3100 | * retval = sys_getcwd(buf, size); |
| 3101 | * if (retval >= 0) |
| 3102 | * return buf; |
| 3103 | * errno = -retval; |
| 3104 | * return NULL; |
| 3105 | * } |
| 3106 | */ |
| 3107 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
| 3108 | { |
| 3109 | int error; |
| 3110 | struct path pwd, root; |
| 3111 | char *page = __getname(); |
| 3112 | |
| 3113 | if (!page) |
| 3114 | return -ENOMEM; |
| 3115 | |
| 3116 | rcu_read_lock(); |
| 3117 | get_fs_root_and_pwd_rcu(current->fs, &root, &pwd); |
| 3118 | |
| 3119 | error = -ENOENT; |
| 3120 | if (!d_unlinked(pwd.dentry)) { |
| 3121 | unsigned long len; |
| 3122 | char *cwd = page + PATH_MAX; |
| 3123 | int buflen = PATH_MAX; |
| 3124 | |
| 3125 | prepend(&cwd, &buflen, "\0", 1); |
| 3126 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
| 3127 | rcu_read_unlock(); |
| 3128 | |
| 3129 | if (error < 0) |
| 3130 | goto out; |
| 3131 | |
| 3132 | /* Unreachable from current root */ |
| 3133 | if (error > 0) { |
| 3134 | error = prepend_unreachable(&cwd, &buflen); |
| 3135 | if (error) |
| 3136 | goto out; |
| 3137 | } |
| 3138 | |
| 3139 | error = -ERANGE; |
| 3140 | len = PATH_MAX + page - cwd; |
| 3141 | if (len <= size) { |
| 3142 | error = len; |
| 3143 | if (copy_to_user(buf, cwd, len)) |
| 3144 | error = -EFAULT; |
| 3145 | } |
| 3146 | } else { |
| 3147 | rcu_read_unlock(); |
| 3148 | } |
| 3149 | |
| 3150 | out: |
| 3151 | __putname(page); |
| 3152 | return error; |
| 3153 | } |
| 3154 | |
| 3155 | /* |
| 3156 | * Test whether new_dentry is a subdirectory of old_dentry. |
| 3157 | * |
| 3158 | * Trivially implemented using the dcache structure |
| 3159 | */ |
| 3160 | |
| 3161 | /** |
| 3162 | * is_subdir - is new dentry a subdirectory of old_dentry |
| 3163 | * @new_dentry: new dentry |
| 3164 | * @old_dentry: old dentry |
| 3165 | * |
| 3166 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
| 3167 | * Returns 0 otherwise. |
| 3168 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
| 3169 | */ |
| 3170 | |
| 3171 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
| 3172 | { |
| 3173 | int result; |
| 3174 | unsigned seq; |
| 3175 | |
| 3176 | if (new_dentry == old_dentry) |
| 3177 | return 1; |
| 3178 | |
| 3179 | do { |
| 3180 | /* for restarting inner loop in case of seq retry */ |
| 3181 | seq = read_seqbegin(&rename_lock); |
| 3182 | /* |
| 3183 | * Need rcu_readlock to protect against the d_parent trashing |
| 3184 | * due to d_move |
| 3185 | */ |
| 3186 | rcu_read_lock(); |
| 3187 | if (d_ancestor(old_dentry, new_dentry)) |
| 3188 | result = 1; |
| 3189 | else |
| 3190 | result = 0; |
| 3191 | rcu_read_unlock(); |
| 3192 | } while (read_seqretry(&rename_lock, seq)); |
| 3193 | |
| 3194 | return result; |
| 3195 | } |
| 3196 | |
| 3197 | static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
| 3198 | { |
| 3199 | struct dentry *root = data; |
| 3200 | if (dentry != root) { |
| 3201 | if (d_unhashed(dentry) || !dentry->d_inode) |
| 3202 | return D_WALK_SKIP; |
| 3203 | |
| 3204 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
| 3205 | dentry->d_flags |= DCACHE_GENOCIDE; |
| 3206 | dentry->d_lockref.count--; |
| 3207 | } |
| 3208 | } |
| 3209 | return D_WALK_CONTINUE; |
| 3210 | } |
| 3211 | |
| 3212 | void d_genocide(struct dentry *parent) |
| 3213 | { |
| 3214 | d_walk(parent, parent, d_genocide_kill, NULL); |
| 3215 | } |
| 3216 | |
| 3217 | void d_tmpfile(struct dentry *dentry, struct inode *inode) |
| 3218 | { |
| 3219 | inode_dec_link_count(inode); |
| 3220 | BUG_ON(dentry->d_name.name != dentry->d_iname || |
| 3221 | !hlist_unhashed(&dentry->d_u.d_alias) || |
| 3222 | !d_unlinked(dentry)); |
| 3223 | spin_lock(&dentry->d_parent->d_lock); |
| 3224 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
| 3225 | dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", |
| 3226 | (unsigned long long)inode->i_ino); |
| 3227 | spin_unlock(&dentry->d_lock); |
| 3228 | spin_unlock(&dentry->d_parent->d_lock); |
| 3229 | d_instantiate(dentry, inode); |
| 3230 | } |
| 3231 | EXPORT_SYMBOL(d_tmpfile); |
| 3232 | |
| 3233 | static __initdata unsigned long dhash_entries; |
| 3234 | static int __init set_dhash_entries(char *str) |
| 3235 | { |
| 3236 | if (!str) |
| 3237 | return 0; |
| 3238 | dhash_entries = simple_strtoul(str, &str, 0); |
| 3239 | return 1; |
| 3240 | } |
| 3241 | __setup("dhash_entries=", set_dhash_entries); |
| 3242 | |
| 3243 | static void __init dcache_init_early(void) |
| 3244 | { |
| 3245 | unsigned int loop; |
| 3246 | |
| 3247 | /* If hashes are distributed across NUMA nodes, defer |
| 3248 | * hash allocation until vmalloc space is available. |
| 3249 | */ |
| 3250 | if (hashdist) |
| 3251 | return; |
| 3252 | |
| 3253 | dentry_hashtable = |
| 3254 | alloc_large_system_hash("Dentry cache", |
| 3255 | sizeof(struct hlist_bl_head), |
| 3256 | dhash_entries, |
| 3257 | 13, |
| 3258 | HASH_EARLY, |
| 3259 | &d_hash_shift, |
| 3260 | &d_hash_mask, |
| 3261 | 0, |
| 3262 | 0); |
| 3263 | |
| 3264 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
| 3265 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
| 3266 | } |
| 3267 | |
| 3268 | static void __init dcache_init(void) |
| 3269 | { |
| 3270 | unsigned int loop; |
| 3271 | |
| 3272 | /* |
| 3273 | * A constructor could be added for stable state like the lists, |
| 3274 | * but it is probably not worth it because of the cache nature |
| 3275 | * of the dcache. |
| 3276 | */ |
| 3277 | dentry_cache = KMEM_CACHE(dentry, |
| 3278 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
| 3279 | |
| 3280 | /* Hash may have been set up in dcache_init_early */ |
| 3281 | if (!hashdist) |
| 3282 | return; |
| 3283 | |
| 3284 | dentry_hashtable = |
| 3285 | alloc_large_system_hash("Dentry cache", |
| 3286 | sizeof(struct hlist_bl_head), |
| 3287 | dhash_entries, |
| 3288 | 13, |
| 3289 | 0, |
| 3290 | &d_hash_shift, |
| 3291 | &d_hash_mask, |
| 3292 | 0, |
| 3293 | 0); |
| 3294 | |
| 3295 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
| 3296 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
| 3297 | } |
| 3298 | |
| 3299 | /* SLAB cache for __getname() consumers */ |
| 3300 | struct kmem_cache *names_cachep __read_mostly; |
| 3301 | EXPORT_SYMBOL(names_cachep); |
| 3302 | |
| 3303 | EXPORT_SYMBOL(d_genocide); |
| 3304 | |
| 3305 | void __init vfs_caches_init_early(void) |
| 3306 | { |
| 3307 | dcache_init_early(); |
| 3308 | inode_init_early(); |
| 3309 | } |
| 3310 | |
| 3311 | void __init vfs_caches_init(unsigned long mempages) |
| 3312 | { |
| 3313 | unsigned long reserve; |
| 3314 | |
| 3315 | /* Base hash sizes on available memory, with a reserve equal to |
| 3316 | 150% of current kernel size */ |
| 3317 | |
| 3318 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); |
| 3319 | mempages -= reserve; |
| 3320 | |
| 3321 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
| 3322 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
| 3323 | |
| 3324 | dcache_init(); |
| 3325 | inode_init(); |
| 3326 | files_init(mempages); |
| 3327 | mnt_init(); |
| 3328 | bdev_cache_init(); |
| 3329 | chrdev_init(); |
| 3330 | } |