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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/module.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 "internal.h" |
39 | |
40 | /* |
41 | * Usage: |
42 | * dcache->d_inode->i_lock protects: |
43 | * - i_dentry, d_alias, d_inode of aliases |
44 | * dcache_hash_bucket lock protects: |
45 | * - the dcache hash table |
46 | * s_anon bl list spinlock protects: |
47 | * - the s_anon list (see __d_drop) |
48 | * dcache_lru_lock protects: |
49 | * - the dcache lru lists and counters |
50 | * d_lock protects: |
51 | * - d_flags |
52 | * - d_name |
53 | * - d_lru |
54 | * - d_count |
55 | * - d_unhashed() |
56 | * - d_parent and d_subdirs |
57 | * - childrens' d_child and d_parent |
58 | * - d_alias, d_inode |
59 | * |
60 | * Ordering: |
61 | * dentry->d_inode->i_lock |
62 | * dentry->d_lock |
63 | * dcache_lru_lock |
64 | * dcache_hash_bucket lock |
65 | * s_anon lock |
66 | * |
67 | * If there is an ancestor relationship: |
68 | * dentry->d_parent->...->d_parent->d_lock |
69 | * ... |
70 | * dentry->d_parent->d_lock |
71 | * dentry->d_lock |
72 | * |
73 | * If no ancestor relationship: |
74 | * if (dentry1 < dentry2) |
75 | * dentry1->d_lock |
76 | * dentry2->d_lock |
77 | */ |
78 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
79 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
80 | |
81 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); |
82 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
83 | |
84 | EXPORT_SYMBOL(rename_lock); |
85 | |
86 | static struct kmem_cache *dentry_cache __read_mostly; |
87 | |
88 | /* |
89 | * This is the single most critical data structure when it comes |
90 | * to the dcache: the hashtable for lookups. Somebody should try |
91 | * to make this good - I've just made it work. |
92 | * |
93 | * This hash-function tries to avoid losing too many bits of hash |
94 | * information, yet avoid using a prime hash-size or similar. |
95 | */ |
96 | #define D_HASHBITS d_hash_shift |
97 | #define D_HASHMASK d_hash_mask |
98 | |
99 | static unsigned int d_hash_mask __read_mostly; |
100 | static unsigned int d_hash_shift __read_mostly; |
101 | |
102 | struct dcache_hash_bucket { |
103 | struct hlist_bl_head head; |
104 | }; |
105 | static struct dcache_hash_bucket *dentry_hashtable __read_mostly; |
106 | |
107 | static inline struct dcache_hash_bucket *d_hash(struct dentry *parent, |
108 | unsigned long hash) |
109 | { |
110 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; |
111 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); |
112 | return dentry_hashtable + (hash & D_HASHMASK); |
113 | } |
114 | |
115 | static inline void spin_lock_bucket(struct dcache_hash_bucket *b) |
116 | { |
117 | bit_spin_lock(0, (unsigned long *)&b->head.first); |
118 | } |
119 | |
120 | static inline void spin_unlock_bucket(struct dcache_hash_bucket *b) |
121 | { |
122 | __bit_spin_unlock(0, (unsigned long *)&b->head.first); |
123 | } |
124 | |
125 | /* Statistics gathering. */ |
126 | struct dentry_stat_t dentry_stat = { |
127 | .age_limit = 45, |
128 | }; |
129 | |
130 | static DEFINE_PER_CPU(unsigned int, nr_dentry); |
131 | |
132 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
133 | static int get_nr_dentry(void) |
134 | { |
135 | int i; |
136 | int sum = 0; |
137 | for_each_possible_cpu(i) |
138 | sum += per_cpu(nr_dentry, i); |
139 | return sum < 0 ? 0 : sum; |
140 | } |
141 | |
142 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
143 | size_t *lenp, loff_t *ppos) |
144 | { |
145 | dentry_stat.nr_dentry = get_nr_dentry(); |
146 | return proc_dointvec(table, write, buffer, lenp, ppos); |
147 | } |
148 | #endif |
149 | |
150 | static void __d_free(struct rcu_head *head) |
151 | { |
152 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
153 | |
154 | WARN_ON(!list_empty(&dentry->d_alias)); |
155 | if (dname_external(dentry)) |
156 | kfree(dentry->d_name.name); |
157 | kmem_cache_free(dentry_cache, dentry); |
158 | } |
159 | |
160 | /* |
161 | * no locks, please. |
162 | */ |
163 | static void d_free(struct dentry *dentry) |
164 | { |
165 | BUG_ON(dentry->d_count); |
166 | this_cpu_dec(nr_dentry); |
167 | if (dentry->d_op && dentry->d_op->d_release) |
168 | dentry->d_op->d_release(dentry); |
169 | |
170 | /* if dentry was never inserted into hash, immediate free is OK */ |
171 | if (hlist_bl_unhashed(&dentry->d_hash)) |
172 | __d_free(&dentry->d_u.d_rcu); |
173 | else |
174 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
175 | } |
176 | |
177 | /** |
178 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups |
179 | * @dentry: the target dentry |
180 | * After this call, in-progress rcu-walk path lookup will fail. This |
181 | * should be called after unhashing, and after changing d_inode (if |
182 | * the dentry has not already been unhashed). |
183 | */ |
184 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) |
185 | { |
186 | assert_spin_locked(&dentry->d_lock); |
187 | /* Go through a barrier */ |
188 | write_seqcount_barrier(&dentry->d_seq); |
189 | } |
190 | |
191 | /* |
192 | * Release the dentry's inode, using the filesystem |
193 | * d_iput() operation if defined. Dentry has no refcount |
194 | * and is unhashed. |
195 | */ |
196 | static void dentry_iput(struct dentry * dentry) |
197 | __releases(dentry->d_lock) |
198 | __releases(dentry->d_inode->i_lock) |
199 | { |
200 | struct inode *inode = dentry->d_inode; |
201 | if (inode) { |
202 | dentry->d_inode = NULL; |
203 | list_del_init(&dentry->d_alias); |
204 | spin_unlock(&dentry->d_lock); |
205 | spin_unlock(&inode->i_lock); |
206 | if (!inode->i_nlink) |
207 | fsnotify_inoderemove(inode); |
208 | if (dentry->d_op && dentry->d_op->d_iput) |
209 | dentry->d_op->d_iput(dentry, inode); |
210 | else |
211 | iput(inode); |
212 | } else { |
213 | spin_unlock(&dentry->d_lock); |
214 | } |
215 | } |
216 | |
217 | /* |
218 | * Release the dentry's inode, using the filesystem |
219 | * d_iput() operation if defined. dentry remains in-use. |
220 | */ |
221 | static void dentry_unlink_inode(struct dentry * dentry) |
222 | __releases(dentry->d_lock) |
223 | __releases(dentry->d_inode->i_lock) |
224 | { |
225 | struct inode *inode = dentry->d_inode; |
226 | dentry->d_inode = NULL; |
227 | list_del_init(&dentry->d_alias); |
228 | dentry_rcuwalk_barrier(dentry); |
229 | spin_unlock(&dentry->d_lock); |
230 | spin_unlock(&inode->i_lock); |
231 | if (!inode->i_nlink) |
232 | fsnotify_inoderemove(inode); |
233 | if (dentry->d_op && dentry->d_op->d_iput) |
234 | dentry->d_op->d_iput(dentry, inode); |
235 | else |
236 | iput(inode); |
237 | } |
238 | |
239 | /* |
240 | * dentry_lru_(add|del|move_tail) must be called with d_lock held. |
241 | */ |
242 | static void dentry_lru_add(struct dentry *dentry) |
243 | { |
244 | if (list_empty(&dentry->d_lru)) { |
245 | spin_lock(&dcache_lru_lock); |
246 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
247 | dentry->d_sb->s_nr_dentry_unused++; |
248 | dentry_stat.nr_unused++; |
249 | spin_unlock(&dcache_lru_lock); |
250 | } |
251 | } |
252 | |
253 | static void __dentry_lru_del(struct dentry *dentry) |
254 | { |
255 | list_del_init(&dentry->d_lru); |
256 | dentry->d_sb->s_nr_dentry_unused--; |
257 | dentry_stat.nr_unused--; |
258 | } |
259 | |
260 | static void dentry_lru_del(struct dentry *dentry) |
261 | { |
262 | if (!list_empty(&dentry->d_lru)) { |
263 | spin_lock(&dcache_lru_lock); |
264 | __dentry_lru_del(dentry); |
265 | spin_unlock(&dcache_lru_lock); |
266 | } |
267 | } |
268 | |
269 | static void dentry_lru_move_tail(struct dentry *dentry) |
270 | { |
271 | spin_lock(&dcache_lru_lock); |
272 | if (list_empty(&dentry->d_lru)) { |
273 | list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
274 | dentry->d_sb->s_nr_dentry_unused++; |
275 | dentry_stat.nr_unused++; |
276 | } else { |
277 | list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
278 | } |
279 | spin_unlock(&dcache_lru_lock); |
280 | } |
281 | |
282 | /** |
283 | * d_kill - kill dentry and return parent |
284 | * @dentry: dentry to kill |
285 | * @parent: parent dentry |
286 | * |
287 | * The dentry must already be unhashed and removed from the LRU. |
288 | * |
289 | * If this is the root of the dentry tree, return NULL. |
290 | * |
291 | * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by |
292 | * d_kill. |
293 | */ |
294 | static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
295 | __releases(dentry->d_lock) |
296 | __releases(parent->d_lock) |
297 | __releases(dentry->d_inode->i_lock) |
298 | { |
299 | dentry->d_parent = NULL; |
300 | list_del(&dentry->d_u.d_child); |
301 | if (parent) |
302 | spin_unlock(&parent->d_lock); |
303 | dentry_iput(dentry); |
304 | /* |
305 | * dentry_iput drops the locks, at which point nobody (except |
306 | * transient RCU lookups) can reach this dentry. |
307 | */ |
308 | d_free(dentry); |
309 | return parent; |
310 | } |
311 | |
312 | /** |
313 | * d_drop - drop a dentry |
314 | * @dentry: dentry to drop |
315 | * |
316 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't |
317 | * be found through a VFS lookup any more. Note that this is different from |
318 | * deleting the dentry - d_delete will try to mark the dentry negative if |
319 | * possible, giving a successful _negative_ lookup, while d_drop will |
320 | * just make the cache lookup fail. |
321 | * |
322 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some |
323 | * reason (NFS timeouts or autofs deletes). |
324 | * |
325 | * __d_drop requires dentry->d_lock. |
326 | */ |
327 | void __d_drop(struct dentry *dentry) |
328 | { |
329 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { |
330 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) { |
331 | bit_spin_lock(0, |
332 | (unsigned long *)&dentry->d_sb->s_anon.first); |
333 | dentry->d_flags |= DCACHE_UNHASHED; |
334 | hlist_bl_del_init(&dentry->d_hash); |
335 | __bit_spin_unlock(0, |
336 | (unsigned long *)&dentry->d_sb->s_anon.first); |
337 | } else { |
338 | struct dcache_hash_bucket *b; |
339 | b = d_hash(dentry->d_parent, dentry->d_name.hash); |
340 | spin_lock_bucket(b); |
341 | /* |
342 | * We may not actually need to put DCACHE_UNHASHED |
343 | * manipulations under the hash lock, but follow |
344 | * the principle of least surprise. |
345 | */ |
346 | dentry->d_flags |= DCACHE_UNHASHED; |
347 | hlist_bl_del_rcu(&dentry->d_hash); |
348 | spin_unlock_bucket(b); |
349 | dentry_rcuwalk_barrier(dentry); |
350 | } |
351 | } |
352 | } |
353 | EXPORT_SYMBOL(__d_drop); |
354 | |
355 | void d_drop(struct dentry *dentry) |
356 | { |
357 | spin_lock(&dentry->d_lock); |
358 | __d_drop(dentry); |
359 | spin_unlock(&dentry->d_lock); |
360 | } |
361 | EXPORT_SYMBOL(d_drop); |
362 | |
363 | /* |
364 | * Finish off a dentry we've decided to kill. |
365 | * dentry->d_lock must be held, returns with it unlocked. |
366 | * If ref is non-zero, then decrement the refcount too. |
367 | * Returns dentry requiring refcount drop, or NULL if we're done. |
368 | */ |
369 | static inline struct dentry *dentry_kill(struct dentry *dentry, int ref) |
370 | __releases(dentry->d_lock) |
371 | { |
372 | struct inode *inode; |
373 | struct dentry *parent; |
374 | |
375 | inode = dentry->d_inode; |
376 | if (inode && !spin_trylock(&inode->i_lock)) { |
377 | relock: |
378 | spin_unlock(&dentry->d_lock); |
379 | cpu_relax(); |
380 | return dentry; /* try again with same dentry */ |
381 | } |
382 | if (IS_ROOT(dentry)) |
383 | parent = NULL; |
384 | else |
385 | parent = dentry->d_parent; |
386 | if (parent && !spin_trylock(&parent->d_lock)) { |
387 | if (inode) |
388 | spin_unlock(&inode->i_lock); |
389 | goto relock; |
390 | } |
391 | |
392 | if (ref) |
393 | dentry->d_count--; |
394 | /* if dentry was on the d_lru list delete it from there */ |
395 | dentry_lru_del(dentry); |
396 | /* if it was on the hash then remove it */ |
397 | __d_drop(dentry); |
398 | return d_kill(dentry, parent); |
399 | } |
400 | |
401 | /* |
402 | * This is dput |
403 | * |
404 | * This is complicated by the fact that we do not want to put |
405 | * dentries that are no longer on any hash chain on the unused |
406 | * list: we'd much rather just get rid of them immediately. |
407 | * |
408 | * However, that implies that we have to traverse the dentry |
409 | * tree upwards to the parents which might _also_ now be |
410 | * scheduled for deletion (it may have been only waiting for |
411 | * its last child to go away). |
412 | * |
413 | * This tail recursion is done by hand as we don't want to depend |
414 | * on the compiler to always get this right (gcc generally doesn't). |
415 | * Real recursion would eat up our stack space. |
416 | */ |
417 | |
418 | /* |
419 | * dput - release a dentry |
420 | * @dentry: dentry to release |
421 | * |
422 | * Release a dentry. This will drop the usage count and if appropriate |
423 | * call the dentry unlink method as well as removing it from the queues and |
424 | * releasing its resources. If the parent dentries were scheduled for release |
425 | * they too may now get deleted. |
426 | */ |
427 | void dput(struct dentry *dentry) |
428 | { |
429 | if (!dentry) |
430 | return; |
431 | |
432 | repeat: |
433 | if (dentry->d_count == 1) |
434 | might_sleep(); |
435 | spin_lock(&dentry->d_lock); |
436 | BUG_ON(!dentry->d_count); |
437 | if (dentry->d_count > 1) { |
438 | dentry->d_count--; |
439 | spin_unlock(&dentry->d_lock); |
440 | return; |
441 | } |
442 | |
443 | if (dentry->d_flags & DCACHE_OP_DELETE) { |
444 | if (dentry->d_op->d_delete(dentry)) |
445 | goto kill_it; |
446 | } |
447 | |
448 | /* Unreachable? Get rid of it */ |
449 | if (d_unhashed(dentry)) |
450 | goto kill_it; |
451 | |
452 | /* Otherwise leave it cached and ensure it's on the LRU */ |
453 | dentry->d_flags |= DCACHE_REFERENCED; |
454 | dentry_lru_add(dentry); |
455 | |
456 | dentry->d_count--; |
457 | spin_unlock(&dentry->d_lock); |
458 | return; |
459 | |
460 | kill_it: |
461 | dentry = dentry_kill(dentry, 1); |
462 | if (dentry) |
463 | goto repeat; |
464 | } |
465 | EXPORT_SYMBOL(dput); |
466 | |
467 | /** |
468 | * d_invalidate - invalidate a dentry |
469 | * @dentry: dentry to invalidate |
470 | * |
471 | * Try to invalidate the dentry if it turns out to be |
472 | * possible. If there are other dentries that can be |
473 | * reached through this one we can't delete it and we |
474 | * return -EBUSY. On success we return 0. |
475 | * |
476 | * no dcache lock. |
477 | */ |
478 | |
479 | int d_invalidate(struct dentry * dentry) |
480 | { |
481 | /* |
482 | * If it's already been dropped, return OK. |
483 | */ |
484 | spin_lock(&dentry->d_lock); |
485 | if (d_unhashed(dentry)) { |
486 | spin_unlock(&dentry->d_lock); |
487 | return 0; |
488 | } |
489 | /* |
490 | * Check whether to do a partial shrink_dcache |
491 | * to get rid of unused child entries. |
492 | */ |
493 | if (!list_empty(&dentry->d_subdirs)) { |
494 | spin_unlock(&dentry->d_lock); |
495 | shrink_dcache_parent(dentry); |
496 | spin_lock(&dentry->d_lock); |
497 | } |
498 | |
499 | /* |
500 | * Somebody else still using it? |
501 | * |
502 | * If it's a directory, we can't drop it |
503 | * for fear of somebody re-populating it |
504 | * with children (even though dropping it |
505 | * would make it unreachable from the root, |
506 | * we might still populate it if it was a |
507 | * working directory or similar). |
508 | */ |
509 | if (dentry->d_count > 1) { |
510 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
511 | spin_unlock(&dentry->d_lock); |
512 | return -EBUSY; |
513 | } |
514 | } |
515 | |
516 | __d_drop(dentry); |
517 | spin_unlock(&dentry->d_lock); |
518 | return 0; |
519 | } |
520 | EXPORT_SYMBOL(d_invalidate); |
521 | |
522 | /* This must be called with d_lock held */ |
523 | static inline void __dget_dlock(struct dentry *dentry) |
524 | { |
525 | dentry->d_count++; |
526 | } |
527 | |
528 | static inline void __dget(struct dentry *dentry) |
529 | { |
530 | spin_lock(&dentry->d_lock); |
531 | __dget_dlock(dentry); |
532 | spin_unlock(&dentry->d_lock); |
533 | } |
534 | |
535 | struct dentry *dget_parent(struct dentry *dentry) |
536 | { |
537 | struct dentry *ret; |
538 | |
539 | repeat: |
540 | /* |
541 | * Don't need rcu_dereference because we re-check it was correct under |
542 | * the lock. |
543 | */ |
544 | rcu_read_lock(); |
545 | ret = dentry->d_parent; |
546 | if (!ret) { |
547 | rcu_read_unlock(); |
548 | goto out; |
549 | } |
550 | spin_lock(&ret->d_lock); |
551 | if (unlikely(ret != dentry->d_parent)) { |
552 | spin_unlock(&ret->d_lock); |
553 | rcu_read_unlock(); |
554 | goto repeat; |
555 | } |
556 | rcu_read_unlock(); |
557 | BUG_ON(!ret->d_count); |
558 | ret->d_count++; |
559 | spin_unlock(&ret->d_lock); |
560 | out: |
561 | return ret; |
562 | } |
563 | EXPORT_SYMBOL(dget_parent); |
564 | |
565 | /** |
566 | * d_find_alias - grab a hashed alias of inode |
567 | * @inode: inode in question |
568 | * @want_discon: flag, used by d_splice_alias, to request |
569 | * that only a DISCONNECTED alias be returned. |
570 | * |
571 | * If inode has a hashed alias, or is a directory and has any alias, |
572 | * acquire the reference to alias and return it. Otherwise return NULL. |
573 | * Notice that if inode is a directory there can be only one alias and |
574 | * it can be unhashed only if it has no children, or if it is the root |
575 | * of a filesystem. |
576 | * |
577 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
578 | * any other hashed alias over that one unless @want_discon is set, |
579 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
580 | */ |
581 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
582 | { |
583 | struct dentry *alias, *discon_alias; |
584 | |
585 | again: |
586 | discon_alias = NULL; |
587 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
588 | spin_lock(&alias->d_lock); |
589 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
590 | if (IS_ROOT(alias) && |
591 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
592 | discon_alias = alias; |
593 | } else if (!want_discon) { |
594 | __dget_dlock(alias); |
595 | spin_unlock(&alias->d_lock); |
596 | return alias; |
597 | } |
598 | } |
599 | spin_unlock(&alias->d_lock); |
600 | } |
601 | if (discon_alias) { |
602 | alias = discon_alias; |
603 | spin_lock(&alias->d_lock); |
604 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
605 | if (IS_ROOT(alias) && |
606 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
607 | __dget_dlock(alias); |
608 | spin_unlock(&alias->d_lock); |
609 | return alias; |
610 | } |
611 | } |
612 | spin_unlock(&alias->d_lock); |
613 | goto again; |
614 | } |
615 | return NULL; |
616 | } |
617 | |
618 | struct dentry *d_find_alias(struct inode *inode) |
619 | { |
620 | struct dentry *de = NULL; |
621 | |
622 | if (!list_empty(&inode->i_dentry)) { |
623 | spin_lock(&inode->i_lock); |
624 | de = __d_find_alias(inode, 0); |
625 | spin_unlock(&inode->i_lock); |
626 | } |
627 | return de; |
628 | } |
629 | EXPORT_SYMBOL(d_find_alias); |
630 | |
631 | /* |
632 | * Try to kill dentries associated with this inode. |
633 | * WARNING: you must own a reference to inode. |
634 | */ |
635 | void d_prune_aliases(struct inode *inode) |
636 | { |
637 | struct dentry *dentry; |
638 | restart: |
639 | spin_lock(&inode->i_lock); |
640 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
641 | spin_lock(&dentry->d_lock); |
642 | if (!dentry->d_count) { |
643 | __dget_dlock(dentry); |
644 | __d_drop(dentry); |
645 | spin_unlock(&dentry->d_lock); |
646 | spin_unlock(&inode->i_lock); |
647 | dput(dentry); |
648 | goto restart; |
649 | } |
650 | spin_unlock(&dentry->d_lock); |
651 | } |
652 | spin_unlock(&inode->i_lock); |
653 | } |
654 | EXPORT_SYMBOL(d_prune_aliases); |
655 | |
656 | /* |
657 | * Try to throw away a dentry - free the inode, dput the parent. |
658 | * Requires dentry->d_lock is held, and dentry->d_count == 0. |
659 | * Releases dentry->d_lock. |
660 | * |
661 | * This may fail if locks cannot be acquired no problem, just try again. |
662 | */ |
663 | static void try_prune_one_dentry(struct dentry *dentry) |
664 | __releases(dentry->d_lock) |
665 | { |
666 | struct dentry *parent; |
667 | |
668 | parent = dentry_kill(dentry, 0); |
669 | /* |
670 | * If dentry_kill returns NULL, we have nothing more to do. |
671 | * if it returns the same dentry, trylocks failed. In either |
672 | * case, just loop again. |
673 | * |
674 | * Otherwise, we need to prune ancestors too. This is necessary |
675 | * to prevent quadratic behavior of shrink_dcache_parent(), but |
676 | * is also expected to be beneficial in reducing dentry cache |
677 | * fragmentation. |
678 | */ |
679 | if (!parent) |
680 | return; |
681 | if (parent == dentry) |
682 | return; |
683 | |
684 | /* Prune ancestors. */ |
685 | dentry = parent; |
686 | while (dentry) { |
687 | spin_lock(&dentry->d_lock); |
688 | if (dentry->d_count > 1) { |
689 | dentry->d_count--; |
690 | spin_unlock(&dentry->d_lock); |
691 | return; |
692 | } |
693 | dentry = dentry_kill(dentry, 1); |
694 | } |
695 | } |
696 | |
697 | static void shrink_dentry_list(struct list_head *list) |
698 | { |
699 | struct dentry *dentry; |
700 | |
701 | rcu_read_lock(); |
702 | for (;;) { |
703 | dentry = list_entry_rcu(list->prev, struct dentry, d_lru); |
704 | if (&dentry->d_lru == list) |
705 | break; /* empty */ |
706 | spin_lock(&dentry->d_lock); |
707 | if (dentry != list_entry(list->prev, struct dentry, d_lru)) { |
708 | spin_unlock(&dentry->d_lock); |
709 | continue; |
710 | } |
711 | |
712 | /* |
713 | * We found an inuse dentry which was not removed from |
714 | * the LRU because of laziness during lookup. Do not free |
715 | * it - just keep it off the LRU list. |
716 | */ |
717 | if (dentry->d_count) { |
718 | dentry_lru_del(dentry); |
719 | spin_unlock(&dentry->d_lock); |
720 | continue; |
721 | } |
722 | |
723 | rcu_read_unlock(); |
724 | |
725 | try_prune_one_dentry(dentry); |
726 | |
727 | rcu_read_lock(); |
728 | } |
729 | rcu_read_unlock(); |
730 | } |
731 | |
732 | /** |
733 | * __shrink_dcache_sb - shrink the dentry LRU on a given superblock |
734 | * @sb: superblock to shrink dentry LRU. |
735 | * @count: number of entries to prune |
736 | * @flags: flags to control the dentry processing |
737 | * |
738 | * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. |
739 | */ |
740 | static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) |
741 | { |
742 | /* called from prune_dcache() and shrink_dcache_parent() */ |
743 | struct dentry *dentry; |
744 | LIST_HEAD(referenced); |
745 | LIST_HEAD(tmp); |
746 | int cnt = *count; |
747 | |
748 | relock: |
749 | spin_lock(&dcache_lru_lock); |
750 | while (!list_empty(&sb->s_dentry_lru)) { |
751 | dentry = list_entry(sb->s_dentry_lru.prev, |
752 | struct dentry, d_lru); |
753 | BUG_ON(dentry->d_sb != sb); |
754 | |
755 | if (!spin_trylock(&dentry->d_lock)) { |
756 | spin_unlock(&dcache_lru_lock); |
757 | cpu_relax(); |
758 | goto relock; |
759 | } |
760 | |
761 | /* |
762 | * If we are honouring the DCACHE_REFERENCED flag and the |
763 | * dentry has this flag set, don't free it. Clear the flag |
764 | * and put it back on the LRU. |
765 | */ |
766 | if (flags & DCACHE_REFERENCED && |
767 | dentry->d_flags & DCACHE_REFERENCED) { |
768 | dentry->d_flags &= ~DCACHE_REFERENCED; |
769 | list_move(&dentry->d_lru, &referenced); |
770 | spin_unlock(&dentry->d_lock); |
771 | } else { |
772 | list_move_tail(&dentry->d_lru, &tmp); |
773 | spin_unlock(&dentry->d_lock); |
774 | if (!--cnt) |
775 | break; |
776 | } |
777 | cond_resched_lock(&dcache_lru_lock); |
778 | } |
779 | if (!list_empty(&referenced)) |
780 | list_splice(&referenced, &sb->s_dentry_lru); |
781 | spin_unlock(&dcache_lru_lock); |
782 | |
783 | shrink_dentry_list(&tmp); |
784 | |
785 | *count = cnt; |
786 | } |
787 | |
788 | /** |
789 | * prune_dcache - shrink the dcache |
790 | * @count: number of entries to try to free |
791 | * |
792 | * Shrink the dcache. This is done when we need more memory, or simply when we |
793 | * need to unmount something (at which point we need to unuse all dentries). |
794 | * |
795 | * This function may fail to free any resources if all the dentries are in use. |
796 | */ |
797 | static void prune_dcache(int count) |
798 | { |
799 | struct super_block *sb, *p = NULL; |
800 | int w_count; |
801 | int unused = dentry_stat.nr_unused; |
802 | int prune_ratio; |
803 | int pruned; |
804 | |
805 | if (unused == 0 || count == 0) |
806 | return; |
807 | if (count >= unused) |
808 | prune_ratio = 1; |
809 | else |
810 | prune_ratio = unused / count; |
811 | spin_lock(&sb_lock); |
812 | list_for_each_entry(sb, &super_blocks, s_list) { |
813 | if (list_empty(&sb->s_instances)) |
814 | continue; |
815 | if (sb->s_nr_dentry_unused == 0) |
816 | continue; |
817 | sb->s_count++; |
818 | /* Now, we reclaim unused dentrins with fairness. |
819 | * We reclaim them same percentage from each superblock. |
820 | * We calculate number of dentries to scan on this sb |
821 | * as follows, but the implementation is arranged to avoid |
822 | * overflows: |
823 | * number of dentries to scan on this sb = |
824 | * count * (number of dentries on this sb / |
825 | * number of dentries in the machine) |
826 | */ |
827 | spin_unlock(&sb_lock); |
828 | if (prune_ratio != 1) |
829 | w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1; |
830 | else |
831 | w_count = sb->s_nr_dentry_unused; |
832 | pruned = w_count; |
833 | /* |
834 | * We need to be sure this filesystem isn't being unmounted, |
835 | * otherwise we could race with generic_shutdown_super(), and |
836 | * end up holding a reference to an inode while the filesystem |
837 | * is unmounted. So we try to get s_umount, and make sure |
838 | * s_root isn't NULL. |
839 | */ |
840 | if (down_read_trylock(&sb->s_umount)) { |
841 | if ((sb->s_root != NULL) && |
842 | (!list_empty(&sb->s_dentry_lru))) { |
843 | __shrink_dcache_sb(sb, &w_count, |
844 | DCACHE_REFERENCED); |
845 | pruned -= w_count; |
846 | } |
847 | up_read(&sb->s_umount); |
848 | } |
849 | spin_lock(&sb_lock); |
850 | if (p) |
851 | __put_super(p); |
852 | count -= pruned; |
853 | p = sb; |
854 | /* more work left to do? */ |
855 | if (count <= 0) |
856 | break; |
857 | } |
858 | if (p) |
859 | __put_super(p); |
860 | spin_unlock(&sb_lock); |
861 | } |
862 | |
863 | /** |
864 | * shrink_dcache_sb - shrink dcache for a superblock |
865 | * @sb: superblock |
866 | * |
867 | * Shrink the dcache for the specified super block. This is used to free |
868 | * the dcache before unmounting a file system. |
869 | */ |
870 | void shrink_dcache_sb(struct super_block *sb) |
871 | { |
872 | LIST_HEAD(tmp); |
873 | |
874 | spin_lock(&dcache_lru_lock); |
875 | while (!list_empty(&sb->s_dentry_lru)) { |
876 | list_splice_init(&sb->s_dentry_lru, &tmp); |
877 | spin_unlock(&dcache_lru_lock); |
878 | shrink_dentry_list(&tmp); |
879 | spin_lock(&dcache_lru_lock); |
880 | } |
881 | spin_unlock(&dcache_lru_lock); |
882 | } |
883 | EXPORT_SYMBOL(shrink_dcache_sb); |
884 | |
885 | /* |
886 | * destroy a single subtree of dentries for unmount |
887 | * - see the comments on shrink_dcache_for_umount() for a description of the |
888 | * locking |
889 | */ |
890 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) |
891 | { |
892 | struct dentry *parent; |
893 | unsigned detached = 0; |
894 | |
895 | BUG_ON(!IS_ROOT(dentry)); |
896 | |
897 | /* detach this root from the system */ |
898 | spin_lock(&dentry->d_lock); |
899 | dentry_lru_del(dentry); |
900 | __d_drop(dentry); |
901 | spin_unlock(&dentry->d_lock); |
902 | |
903 | for (;;) { |
904 | /* descend to the first leaf in the current subtree */ |
905 | while (!list_empty(&dentry->d_subdirs)) { |
906 | struct dentry *loop; |
907 | |
908 | /* this is a branch with children - detach all of them |
909 | * from the system in one go */ |
910 | spin_lock(&dentry->d_lock); |
911 | list_for_each_entry(loop, &dentry->d_subdirs, |
912 | d_u.d_child) { |
913 | spin_lock_nested(&loop->d_lock, |
914 | DENTRY_D_LOCK_NESTED); |
915 | dentry_lru_del(loop); |
916 | __d_drop(loop); |
917 | spin_unlock(&loop->d_lock); |
918 | } |
919 | spin_unlock(&dentry->d_lock); |
920 | |
921 | /* move to the first child */ |
922 | dentry = list_entry(dentry->d_subdirs.next, |
923 | struct dentry, d_u.d_child); |
924 | } |
925 | |
926 | /* consume the dentries from this leaf up through its parents |
927 | * until we find one with children or run out altogether */ |
928 | do { |
929 | struct inode *inode; |
930 | |
931 | if (dentry->d_count != 0) { |
932 | printk(KERN_ERR |
933 | "BUG: Dentry %p{i=%lx,n=%s}" |
934 | " still in use (%d)" |
935 | " [unmount of %s %s]\n", |
936 | dentry, |
937 | dentry->d_inode ? |
938 | dentry->d_inode->i_ino : 0UL, |
939 | dentry->d_name.name, |
940 | dentry->d_count, |
941 | dentry->d_sb->s_type->name, |
942 | dentry->d_sb->s_id); |
943 | BUG(); |
944 | } |
945 | |
946 | if (IS_ROOT(dentry)) { |
947 | parent = NULL; |
948 | list_del(&dentry->d_u.d_child); |
949 | } else { |
950 | parent = dentry->d_parent; |
951 | spin_lock(&parent->d_lock); |
952 | parent->d_count--; |
953 | list_del(&dentry->d_u.d_child); |
954 | spin_unlock(&parent->d_lock); |
955 | } |
956 | |
957 | detached++; |
958 | |
959 | inode = dentry->d_inode; |
960 | if (inode) { |
961 | dentry->d_inode = NULL; |
962 | list_del_init(&dentry->d_alias); |
963 | if (dentry->d_op && dentry->d_op->d_iput) |
964 | dentry->d_op->d_iput(dentry, inode); |
965 | else |
966 | iput(inode); |
967 | } |
968 | |
969 | d_free(dentry); |
970 | |
971 | /* finished when we fall off the top of the tree, |
972 | * otherwise we ascend to the parent and move to the |
973 | * next sibling if there is one */ |
974 | if (!parent) |
975 | return; |
976 | dentry = parent; |
977 | } while (list_empty(&dentry->d_subdirs)); |
978 | |
979 | dentry = list_entry(dentry->d_subdirs.next, |
980 | struct dentry, d_u.d_child); |
981 | } |
982 | } |
983 | |
984 | /* |
985 | * destroy the dentries attached to a superblock on unmounting |
986 | * - we don't need to use dentry->d_lock because: |
987 | * - the superblock is detached from all mountings and open files, so the |
988 | * dentry trees will not be rearranged by the VFS |
989 | * - s_umount is write-locked, so the memory pressure shrinker will ignore |
990 | * any dentries belonging to this superblock that it comes across |
991 | * - the filesystem itself is no longer permitted to rearrange the dentries |
992 | * in this superblock |
993 | */ |
994 | void shrink_dcache_for_umount(struct super_block *sb) |
995 | { |
996 | struct dentry *dentry; |
997 | |
998 | if (down_read_trylock(&sb->s_umount)) |
999 | BUG(); |
1000 | |
1001 | dentry = sb->s_root; |
1002 | sb->s_root = NULL; |
1003 | spin_lock(&dentry->d_lock); |
1004 | dentry->d_count--; |
1005 | spin_unlock(&dentry->d_lock); |
1006 | shrink_dcache_for_umount_subtree(dentry); |
1007 | |
1008 | while (!hlist_bl_empty(&sb->s_anon)) { |
1009 | dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); |
1010 | shrink_dcache_for_umount_subtree(dentry); |
1011 | } |
1012 | } |
1013 | |
1014 | /* |
1015 | * Search for at least 1 mount point in the dentry's subdirs. |
1016 | * We descend to the next level whenever the d_subdirs |
1017 | * list is non-empty and continue searching. |
1018 | */ |
1019 | |
1020 | /** |
1021 | * have_submounts - check for mounts over a dentry |
1022 | * @parent: dentry to check. |
1023 | * |
1024 | * Return true if the parent or its subdirectories contain |
1025 | * a mount point |
1026 | */ |
1027 | int have_submounts(struct dentry *parent) |
1028 | { |
1029 | struct dentry *this_parent; |
1030 | struct list_head *next; |
1031 | unsigned seq; |
1032 | int locked = 0; |
1033 | |
1034 | seq = read_seqbegin(&rename_lock); |
1035 | again: |
1036 | this_parent = parent; |
1037 | |
1038 | if (d_mountpoint(parent)) |
1039 | goto positive; |
1040 | spin_lock(&this_parent->d_lock); |
1041 | repeat: |
1042 | next = this_parent->d_subdirs.next; |
1043 | resume: |
1044 | while (next != &this_parent->d_subdirs) { |
1045 | struct list_head *tmp = next; |
1046 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1047 | next = tmp->next; |
1048 | |
1049 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1050 | /* Have we found a mount point ? */ |
1051 | if (d_mountpoint(dentry)) { |
1052 | spin_unlock(&dentry->d_lock); |
1053 | spin_unlock(&this_parent->d_lock); |
1054 | goto positive; |
1055 | } |
1056 | if (!list_empty(&dentry->d_subdirs)) { |
1057 | spin_unlock(&this_parent->d_lock); |
1058 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
1059 | this_parent = dentry; |
1060 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1061 | goto repeat; |
1062 | } |
1063 | spin_unlock(&dentry->d_lock); |
1064 | } |
1065 | /* |
1066 | * All done at this level ... ascend and resume the search. |
1067 | */ |
1068 | if (this_parent != parent) { |
1069 | struct dentry *tmp; |
1070 | struct dentry *child; |
1071 | |
1072 | tmp = this_parent->d_parent; |
1073 | rcu_read_lock(); |
1074 | spin_unlock(&this_parent->d_lock); |
1075 | child = this_parent; |
1076 | this_parent = tmp; |
1077 | spin_lock(&this_parent->d_lock); |
1078 | /* might go back up the wrong parent if we have had a rename |
1079 | * or deletion */ |
1080 | if (this_parent != child->d_parent || |
1081 | (!locked && read_seqretry(&rename_lock, seq))) { |
1082 | spin_unlock(&this_parent->d_lock); |
1083 | rcu_read_unlock(); |
1084 | goto rename_retry; |
1085 | } |
1086 | rcu_read_unlock(); |
1087 | next = child->d_u.d_child.next; |
1088 | goto resume; |
1089 | } |
1090 | spin_unlock(&this_parent->d_lock); |
1091 | if (!locked && read_seqretry(&rename_lock, seq)) |
1092 | goto rename_retry; |
1093 | if (locked) |
1094 | write_sequnlock(&rename_lock); |
1095 | return 0; /* No mount points found in tree */ |
1096 | positive: |
1097 | if (!locked && read_seqretry(&rename_lock, seq)) |
1098 | goto rename_retry; |
1099 | if (locked) |
1100 | write_sequnlock(&rename_lock); |
1101 | return 1; |
1102 | |
1103 | rename_retry: |
1104 | locked = 1; |
1105 | write_seqlock(&rename_lock); |
1106 | goto again; |
1107 | } |
1108 | EXPORT_SYMBOL(have_submounts); |
1109 | |
1110 | /* |
1111 | * Search the dentry child list for the specified parent, |
1112 | * and move any unused dentries to the end of the unused |
1113 | * list for prune_dcache(). We descend to the next level |
1114 | * whenever the d_subdirs list is non-empty and continue |
1115 | * searching. |
1116 | * |
1117 | * It returns zero iff there are no unused children, |
1118 | * otherwise it returns the number of children moved to |
1119 | * the end of the unused list. This may not be the total |
1120 | * number of unused children, because select_parent can |
1121 | * drop the lock and return early due to latency |
1122 | * constraints. |
1123 | */ |
1124 | static int select_parent(struct dentry * parent) |
1125 | { |
1126 | struct dentry *this_parent; |
1127 | struct list_head *next; |
1128 | unsigned seq; |
1129 | int found = 0; |
1130 | int locked = 0; |
1131 | |
1132 | seq = read_seqbegin(&rename_lock); |
1133 | again: |
1134 | this_parent = parent; |
1135 | spin_lock(&this_parent->d_lock); |
1136 | repeat: |
1137 | next = this_parent->d_subdirs.next; |
1138 | resume: |
1139 | while (next != &this_parent->d_subdirs) { |
1140 | struct list_head *tmp = next; |
1141 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1142 | next = tmp->next; |
1143 | |
1144 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1145 | |
1146 | /* |
1147 | * move only zero ref count dentries to the end |
1148 | * of the unused list for prune_dcache |
1149 | */ |
1150 | if (!dentry->d_count) { |
1151 | dentry_lru_move_tail(dentry); |
1152 | found++; |
1153 | } else { |
1154 | dentry_lru_del(dentry); |
1155 | } |
1156 | |
1157 | /* |
1158 | * We can return to the caller if we have found some (this |
1159 | * ensures forward progress). We'll be coming back to find |
1160 | * the rest. |
1161 | */ |
1162 | if (found && need_resched()) { |
1163 | spin_unlock(&dentry->d_lock); |
1164 | goto out; |
1165 | } |
1166 | |
1167 | /* |
1168 | * Descend a level if the d_subdirs list is non-empty. |
1169 | */ |
1170 | if (!list_empty(&dentry->d_subdirs)) { |
1171 | spin_unlock(&this_parent->d_lock); |
1172 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
1173 | this_parent = dentry; |
1174 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1175 | goto repeat; |
1176 | } |
1177 | |
1178 | spin_unlock(&dentry->d_lock); |
1179 | } |
1180 | /* |
1181 | * All done at this level ... ascend and resume the search. |
1182 | */ |
1183 | if (this_parent != parent) { |
1184 | struct dentry *tmp; |
1185 | struct dentry *child; |
1186 | |
1187 | tmp = this_parent->d_parent; |
1188 | rcu_read_lock(); |
1189 | spin_unlock(&this_parent->d_lock); |
1190 | child = this_parent; |
1191 | this_parent = tmp; |
1192 | spin_lock(&this_parent->d_lock); |
1193 | /* might go back up the wrong parent if we have had a rename |
1194 | * or deletion */ |
1195 | if (this_parent != child->d_parent || |
1196 | (!locked && read_seqretry(&rename_lock, seq))) { |
1197 | spin_unlock(&this_parent->d_lock); |
1198 | rcu_read_unlock(); |
1199 | goto rename_retry; |
1200 | } |
1201 | rcu_read_unlock(); |
1202 | next = child->d_u.d_child.next; |
1203 | goto resume; |
1204 | } |
1205 | out: |
1206 | spin_unlock(&this_parent->d_lock); |
1207 | if (!locked && read_seqretry(&rename_lock, seq)) |
1208 | goto rename_retry; |
1209 | if (locked) |
1210 | write_sequnlock(&rename_lock); |
1211 | return found; |
1212 | |
1213 | rename_retry: |
1214 | if (found) |
1215 | return found; |
1216 | locked = 1; |
1217 | write_seqlock(&rename_lock); |
1218 | goto again; |
1219 | } |
1220 | |
1221 | /** |
1222 | * shrink_dcache_parent - prune dcache |
1223 | * @parent: parent of entries to prune |
1224 | * |
1225 | * Prune the dcache to remove unused children of the parent dentry. |
1226 | */ |
1227 | |
1228 | void shrink_dcache_parent(struct dentry * parent) |
1229 | { |
1230 | struct super_block *sb = parent->d_sb; |
1231 | int found; |
1232 | |
1233 | while ((found = select_parent(parent)) != 0) |
1234 | __shrink_dcache_sb(sb, &found, 0); |
1235 | } |
1236 | EXPORT_SYMBOL(shrink_dcache_parent); |
1237 | |
1238 | /* |
1239 | * Scan `nr' dentries and return the number which remain. |
1240 | * |
1241 | * We need to avoid reentering the filesystem if the caller is performing a |
1242 | * GFP_NOFS allocation attempt. One example deadlock is: |
1243 | * |
1244 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> |
1245 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> |
1246 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. |
1247 | * |
1248 | * In this case we return -1 to tell the caller that we baled. |
1249 | */ |
1250 | static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask) |
1251 | { |
1252 | if (nr) { |
1253 | if (!(gfp_mask & __GFP_FS)) |
1254 | return -1; |
1255 | prune_dcache(nr); |
1256 | } |
1257 | |
1258 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; |
1259 | } |
1260 | |
1261 | static struct shrinker dcache_shrinker = { |
1262 | .shrink = shrink_dcache_memory, |
1263 | .seeks = DEFAULT_SEEKS, |
1264 | }; |
1265 | |
1266 | /** |
1267 | * d_alloc - allocate a dcache entry |
1268 | * @parent: parent of entry to allocate |
1269 | * @name: qstr of the name |
1270 | * |
1271 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
1272 | * available. On a success the dentry is returned. The name passed in is |
1273 | * copied and the copy passed in may be reused after this call. |
1274 | */ |
1275 | |
1276 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
1277 | { |
1278 | struct dentry *dentry; |
1279 | char *dname; |
1280 | |
1281 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1282 | if (!dentry) |
1283 | return NULL; |
1284 | |
1285 | if (name->len > DNAME_INLINE_LEN-1) { |
1286 | dname = kmalloc(name->len + 1, GFP_KERNEL); |
1287 | if (!dname) { |
1288 | kmem_cache_free(dentry_cache, dentry); |
1289 | return NULL; |
1290 | } |
1291 | } else { |
1292 | dname = dentry->d_iname; |
1293 | } |
1294 | dentry->d_name.name = dname; |
1295 | |
1296 | dentry->d_name.len = name->len; |
1297 | dentry->d_name.hash = name->hash; |
1298 | memcpy(dname, name->name, name->len); |
1299 | dname[name->len] = 0; |
1300 | |
1301 | dentry->d_count = 1; |
1302 | dentry->d_flags = DCACHE_UNHASHED; |
1303 | spin_lock_init(&dentry->d_lock); |
1304 | seqcount_init(&dentry->d_seq); |
1305 | dentry->d_inode = NULL; |
1306 | dentry->d_parent = NULL; |
1307 | dentry->d_sb = NULL; |
1308 | dentry->d_op = NULL; |
1309 | dentry->d_fsdata = NULL; |
1310 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1311 | INIT_LIST_HEAD(&dentry->d_lru); |
1312 | INIT_LIST_HEAD(&dentry->d_subdirs); |
1313 | INIT_LIST_HEAD(&dentry->d_alias); |
1314 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1315 | |
1316 | if (parent) { |
1317 | spin_lock(&parent->d_lock); |
1318 | /* |
1319 | * don't need child lock because it is not subject |
1320 | * to concurrency here |
1321 | */ |
1322 | __dget_dlock(parent); |
1323 | dentry->d_parent = parent; |
1324 | dentry->d_sb = parent->d_sb; |
1325 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1326 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1327 | spin_unlock(&parent->d_lock); |
1328 | } |
1329 | |
1330 | this_cpu_inc(nr_dentry); |
1331 | |
1332 | return dentry; |
1333 | } |
1334 | EXPORT_SYMBOL(d_alloc); |
1335 | |
1336 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1337 | { |
1338 | struct dentry *dentry = d_alloc(NULL, name); |
1339 | if (dentry) { |
1340 | dentry->d_sb = sb; |
1341 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1342 | dentry->d_parent = dentry; |
1343 | dentry->d_flags |= DCACHE_DISCONNECTED; |
1344 | } |
1345 | return dentry; |
1346 | } |
1347 | EXPORT_SYMBOL(d_alloc_pseudo); |
1348 | |
1349 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1350 | { |
1351 | struct qstr q; |
1352 | |
1353 | q.name = name; |
1354 | q.len = strlen(name); |
1355 | q.hash = full_name_hash(q.name, q.len); |
1356 | return d_alloc(parent, &q); |
1357 | } |
1358 | EXPORT_SYMBOL(d_alloc_name); |
1359 | |
1360 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1361 | { |
1362 | WARN_ON_ONCE(dentry->d_op); |
1363 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
1364 | DCACHE_OP_COMPARE | |
1365 | DCACHE_OP_REVALIDATE | |
1366 | DCACHE_OP_DELETE )); |
1367 | dentry->d_op = op; |
1368 | if (!op) |
1369 | return; |
1370 | if (op->d_hash) |
1371 | dentry->d_flags |= DCACHE_OP_HASH; |
1372 | if (op->d_compare) |
1373 | dentry->d_flags |= DCACHE_OP_COMPARE; |
1374 | if (op->d_revalidate) |
1375 | dentry->d_flags |= DCACHE_OP_REVALIDATE; |
1376 | if (op->d_delete) |
1377 | dentry->d_flags |= DCACHE_OP_DELETE; |
1378 | |
1379 | } |
1380 | EXPORT_SYMBOL(d_set_d_op); |
1381 | |
1382 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1383 | { |
1384 | spin_lock(&dentry->d_lock); |
1385 | if (inode) { |
1386 | if (unlikely(IS_AUTOMOUNT(inode))) |
1387 | dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; |
1388 | list_add(&dentry->d_alias, &inode->i_dentry); |
1389 | } |
1390 | dentry->d_inode = inode; |
1391 | dentry_rcuwalk_barrier(dentry); |
1392 | spin_unlock(&dentry->d_lock); |
1393 | fsnotify_d_instantiate(dentry, inode); |
1394 | } |
1395 | |
1396 | /** |
1397 | * d_instantiate - fill in inode information for a dentry |
1398 | * @entry: dentry to complete |
1399 | * @inode: inode to attach to this dentry |
1400 | * |
1401 | * Fill in inode information in the entry. |
1402 | * |
1403 | * This turns negative dentries into productive full members |
1404 | * of society. |
1405 | * |
1406 | * NOTE! This assumes that the inode count has been incremented |
1407 | * (or otherwise set) by the caller to indicate that it is now |
1408 | * in use by the dcache. |
1409 | */ |
1410 | |
1411 | void d_instantiate(struct dentry *entry, struct inode * inode) |
1412 | { |
1413 | BUG_ON(!list_empty(&entry->d_alias)); |
1414 | if (inode) |
1415 | spin_lock(&inode->i_lock); |
1416 | __d_instantiate(entry, inode); |
1417 | if (inode) |
1418 | spin_unlock(&inode->i_lock); |
1419 | security_d_instantiate(entry, inode); |
1420 | } |
1421 | EXPORT_SYMBOL(d_instantiate); |
1422 | |
1423 | /** |
1424 | * d_instantiate_unique - instantiate a non-aliased dentry |
1425 | * @entry: dentry to instantiate |
1426 | * @inode: inode to attach to this dentry |
1427 | * |
1428 | * Fill in inode information in the entry. On success, it returns NULL. |
1429 | * If an unhashed alias of "entry" already exists, then we return the |
1430 | * aliased dentry instead and drop one reference to inode. |
1431 | * |
1432 | * Note that in order to avoid conflicts with rename() etc, the caller |
1433 | * had better be holding the parent directory semaphore. |
1434 | * |
1435 | * This also assumes that the inode count has been incremented |
1436 | * (or otherwise set) by the caller to indicate that it is now |
1437 | * in use by the dcache. |
1438 | */ |
1439 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1440 | struct inode *inode) |
1441 | { |
1442 | struct dentry *alias; |
1443 | int len = entry->d_name.len; |
1444 | const char *name = entry->d_name.name; |
1445 | unsigned int hash = entry->d_name.hash; |
1446 | |
1447 | if (!inode) { |
1448 | __d_instantiate(entry, NULL); |
1449 | return NULL; |
1450 | } |
1451 | |
1452 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1453 | struct qstr *qstr = &alias->d_name; |
1454 | |
1455 | /* |
1456 | * Don't need alias->d_lock here, because aliases with |
1457 | * d_parent == entry->d_parent are not subject to name or |
1458 | * parent changes, because the parent inode i_mutex is held. |
1459 | */ |
1460 | if (qstr->hash != hash) |
1461 | continue; |
1462 | if (alias->d_parent != entry->d_parent) |
1463 | continue; |
1464 | if (dentry_cmp(qstr->name, qstr->len, name, len)) |
1465 | continue; |
1466 | __dget(alias); |
1467 | return alias; |
1468 | } |
1469 | |
1470 | __d_instantiate(entry, inode); |
1471 | return NULL; |
1472 | } |
1473 | |
1474 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
1475 | { |
1476 | struct dentry *result; |
1477 | |
1478 | BUG_ON(!list_empty(&entry->d_alias)); |
1479 | |
1480 | if (inode) |
1481 | spin_lock(&inode->i_lock); |
1482 | result = __d_instantiate_unique(entry, inode); |
1483 | if (inode) |
1484 | spin_unlock(&inode->i_lock); |
1485 | |
1486 | if (!result) { |
1487 | security_d_instantiate(entry, inode); |
1488 | return NULL; |
1489 | } |
1490 | |
1491 | BUG_ON(!d_unhashed(result)); |
1492 | iput(inode); |
1493 | return result; |
1494 | } |
1495 | |
1496 | EXPORT_SYMBOL(d_instantiate_unique); |
1497 | |
1498 | /** |
1499 | * d_alloc_root - allocate root dentry |
1500 | * @root_inode: inode to allocate the root for |
1501 | * |
1502 | * Allocate a root ("/") dentry for the inode given. The inode is |
1503 | * instantiated and returned. %NULL is returned if there is insufficient |
1504 | * memory or the inode passed is %NULL. |
1505 | */ |
1506 | |
1507 | struct dentry * d_alloc_root(struct inode * root_inode) |
1508 | { |
1509 | struct dentry *res = NULL; |
1510 | |
1511 | if (root_inode) { |
1512 | static const struct qstr name = { .name = "/", .len = 1 }; |
1513 | |
1514 | res = d_alloc(NULL, &name); |
1515 | if (res) { |
1516 | res->d_sb = root_inode->i_sb; |
1517 | d_set_d_op(res, res->d_sb->s_d_op); |
1518 | res->d_parent = res; |
1519 | d_instantiate(res, root_inode); |
1520 | } |
1521 | } |
1522 | return res; |
1523 | } |
1524 | EXPORT_SYMBOL(d_alloc_root); |
1525 | |
1526 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1527 | { |
1528 | struct dentry *alias; |
1529 | |
1530 | if (list_empty(&inode->i_dentry)) |
1531 | return NULL; |
1532 | alias = list_first_entry(&inode->i_dentry, struct dentry, d_alias); |
1533 | __dget(alias); |
1534 | return alias; |
1535 | } |
1536 | |
1537 | static struct dentry * d_find_any_alias(struct inode *inode) |
1538 | { |
1539 | struct dentry *de; |
1540 | |
1541 | spin_lock(&inode->i_lock); |
1542 | de = __d_find_any_alias(inode); |
1543 | spin_unlock(&inode->i_lock); |
1544 | return de; |
1545 | } |
1546 | |
1547 | |
1548 | /** |
1549 | * d_obtain_alias - find or allocate a dentry for a given inode |
1550 | * @inode: inode to allocate the dentry for |
1551 | * |
1552 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
1553 | * similar open by handle operations. The returned dentry may be anonymous, |
1554 | * or may have a full name (if the inode was already in the cache). |
1555 | * |
1556 | * When called on a directory inode, we must ensure that the inode only ever |
1557 | * has one dentry. If a dentry is found, that is returned instead of |
1558 | * allocating a new one. |
1559 | * |
1560 | * On successful return, the reference to the inode has been transferred |
1561 | * to the dentry. In case of an error the reference on the inode is released. |
1562 | * To make it easier to use in export operations a %NULL or IS_ERR inode may |
1563 | * be passed in and will be the error will be propagate to the return value, |
1564 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
1565 | */ |
1566 | struct dentry *d_obtain_alias(struct inode *inode) |
1567 | { |
1568 | static const struct qstr anonstring = { .name = "" }; |
1569 | struct dentry *tmp; |
1570 | struct dentry *res; |
1571 | |
1572 | if (!inode) |
1573 | return ERR_PTR(-ESTALE); |
1574 | if (IS_ERR(inode)) |
1575 | return ERR_CAST(inode); |
1576 | |
1577 | res = d_find_any_alias(inode); |
1578 | if (res) |
1579 | goto out_iput; |
1580 | |
1581 | tmp = d_alloc(NULL, &anonstring); |
1582 | if (!tmp) { |
1583 | res = ERR_PTR(-ENOMEM); |
1584 | goto out_iput; |
1585 | } |
1586 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
1587 | |
1588 | |
1589 | spin_lock(&inode->i_lock); |
1590 | res = __d_find_any_alias(inode); |
1591 | if (res) { |
1592 | spin_unlock(&inode->i_lock); |
1593 | dput(tmp); |
1594 | goto out_iput; |
1595 | } |
1596 | |
1597 | /* attach a disconnected dentry */ |
1598 | spin_lock(&tmp->d_lock); |
1599 | tmp->d_sb = inode->i_sb; |
1600 | d_set_d_op(tmp, tmp->d_sb->s_d_op); |
1601 | tmp->d_inode = inode; |
1602 | tmp->d_flags |= DCACHE_DISCONNECTED; |
1603 | list_add(&tmp->d_alias, &inode->i_dentry); |
1604 | bit_spin_lock(0, (unsigned long *)&tmp->d_sb->s_anon.first); |
1605 | tmp->d_flags &= ~DCACHE_UNHASHED; |
1606 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1607 | __bit_spin_unlock(0, (unsigned long *)&tmp->d_sb->s_anon.first); |
1608 | spin_unlock(&tmp->d_lock); |
1609 | spin_unlock(&inode->i_lock); |
1610 | |
1611 | return tmp; |
1612 | |
1613 | out_iput: |
1614 | iput(inode); |
1615 | return res; |
1616 | } |
1617 | EXPORT_SYMBOL(d_obtain_alias); |
1618 | |
1619 | /** |
1620 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
1621 | * @inode: the inode which may have a disconnected dentry |
1622 | * @dentry: a negative dentry which we want to point to the inode. |
1623 | * |
1624 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and |
1625 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry |
1626 | * and return it, else simply d_add the inode to the dentry and return NULL. |
1627 | * |
1628 | * This is needed in the lookup routine of any filesystem that is exportable |
1629 | * (via knfsd) so that we can build dcache paths to directories effectively. |
1630 | * |
1631 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
1632 | * is returned. This matches the expected return value of ->lookup. |
1633 | * |
1634 | */ |
1635 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
1636 | { |
1637 | struct dentry *new = NULL; |
1638 | |
1639 | if (inode && S_ISDIR(inode->i_mode)) { |
1640 | spin_lock(&inode->i_lock); |
1641 | new = __d_find_alias(inode, 1); |
1642 | if (new) { |
1643 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
1644 | spin_unlock(&inode->i_lock); |
1645 | security_d_instantiate(new, inode); |
1646 | d_move(new, dentry); |
1647 | iput(inode); |
1648 | } else { |
1649 | /* already taking inode->i_lock, so d_add() by hand */ |
1650 | __d_instantiate(dentry, inode); |
1651 | spin_unlock(&inode->i_lock); |
1652 | security_d_instantiate(dentry, inode); |
1653 | d_rehash(dentry); |
1654 | } |
1655 | } else |
1656 | d_add(dentry, inode); |
1657 | return new; |
1658 | } |
1659 | EXPORT_SYMBOL(d_splice_alias); |
1660 | |
1661 | /** |
1662 | * d_add_ci - lookup or allocate new dentry with case-exact name |
1663 | * @inode: the inode case-insensitive lookup has found |
1664 | * @dentry: the negative dentry that was passed to the parent's lookup func |
1665 | * @name: the case-exact name to be associated with the returned dentry |
1666 | * |
1667 | * This is to avoid filling the dcache with case-insensitive names to the |
1668 | * same inode, only the actual correct case is stored in the dcache for |
1669 | * case-insensitive filesystems. |
1670 | * |
1671 | * For a case-insensitive lookup match and if the the case-exact dentry |
1672 | * already exists in in the dcache, use it and return it. |
1673 | * |
1674 | * If no entry exists with the exact case name, allocate new dentry with |
1675 | * the exact case, and return the spliced entry. |
1676 | */ |
1677 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
1678 | struct qstr *name) |
1679 | { |
1680 | int error; |
1681 | struct dentry *found; |
1682 | struct dentry *new; |
1683 | |
1684 | /* |
1685 | * First check if a dentry matching the name already exists, |
1686 | * if not go ahead and create it now. |
1687 | */ |
1688 | found = d_hash_and_lookup(dentry->d_parent, name); |
1689 | if (!found) { |
1690 | new = d_alloc(dentry->d_parent, name); |
1691 | if (!new) { |
1692 | error = -ENOMEM; |
1693 | goto err_out; |
1694 | } |
1695 | |
1696 | found = d_splice_alias(inode, new); |
1697 | if (found) { |
1698 | dput(new); |
1699 | return found; |
1700 | } |
1701 | return new; |
1702 | } |
1703 | |
1704 | /* |
1705 | * If a matching dentry exists, and it's not negative use it. |
1706 | * |
1707 | * Decrement the reference count to balance the iget() done |
1708 | * earlier on. |
1709 | */ |
1710 | if (found->d_inode) { |
1711 | if (unlikely(found->d_inode != inode)) { |
1712 | /* This can't happen because bad inodes are unhashed. */ |
1713 | BUG_ON(!is_bad_inode(inode)); |
1714 | BUG_ON(!is_bad_inode(found->d_inode)); |
1715 | } |
1716 | iput(inode); |
1717 | return found; |
1718 | } |
1719 | |
1720 | /* |
1721 | * Negative dentry: instantiate it unless the inode is a directory and |
1722 | * already has a dentry. |
1723 | */ |
1724 | spin_lock(&inode->i_lock); |
1725 | if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) { |
1726 | __d_instantiate(found, inode); |
1727 | spin_unlock(&inode->i_lock); |
1728 | security_d_instantiate(found, inode); |
1729 | return found; |
1730 | } |
1731 | |
1732 | /* |
1733 | * In case a directory already has a (disconnected) entry grab a |
1734 | * reference to it, move it in place and use it. |
1735 | */ |
1736 | new = list_entry(inode->i_dentry.next, struct dentry, d_alias); |
1737 | __dget(new); |
1738 | spin_unlock(&inode->i_lock); |
1739 | security_d_instantiate(found, inode); |
1740 | d_move(new, found); |
1741 | iput(inode); |
1742 | dput(found); |
1743 | return new; |
1744 | |
1745 | err_out: |
1746 | iput(inode); |
1747 | return ERR_PTR(error); |
1748 | } |
1749 | EXPORT_SYMBOL(d_add_ci); |
1750 | |
1751 | /** |
1752 | * __d_lookup_rcu - search for a dentry (racy, store-free) |
1753 | * @parent: parent dentry |
1754 | * @name: qstr of name we wish to find |
1755 | * @seq: returns d_seq value at the point where the dentry was found |
1756 | * @inode: returns dentry->d_inode when the inode was found valid. |
1757 | * Returns: dentry, or NULL |
1758 | * |
1759 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name |
1760 | * resolution (store-free path walking) design described in |
1761 | * Documentation/filesystems/path-lookup.txt. |
1762 | * |
1763 | * This is not to be used outside core vfs. |
1764 | * |
1765 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock |
1766 | * held, and rcu_read_lock held. The returned dentry must not be stored into |
1767 | * without taking d_lock and checking d_seq sequence count against @seq |
1768 | * returned here. |
1769 | * |
1770 | * A refcount may be taken on the found dentry with the __d_rcu_to_refcount |
1771 | * function. |
1772 | * |
1773 | * Alternatively, __d_lookup_rcu may be called again to look up the child of |
1774 | * the returned dentry, so long as its parent's seqlock is checked after the |
1775 | * child is looked up. Thus, an interlocking stepping of sequence lock checks |
1776 | * is formed, giving integrity down the path walk. |
1777 | */ |
1778 | struct dentry *__d_lookup_rcu(struct dentry *parent, struct qstr *name, |
1779 | unsigned *seq, struct inode **inode) |
1780 | { |
1781 | unsigned int len = name->len; |
1782 | unsigned int hash = name->hash; |
1783 | const unsigned char *str = name->name; |
1784 | struct dcache_hash_bucket *b = d_hash(parent, hash); |
1785 | struct hlist_bl_node *node; |
1786 | struct dentry *dentry; |
1787 | |
1788 | /* |
1789 | * Note: There is significant duplication with __d_lookup_rcu which is |
1790 | * required to prevent single threaded performance regressions |
1791 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
1792 | * Keep the two functions in sync. |
1793 | */ |
1794 | |
1795 | /* |
1796 | * The hash list is protected using RCU. |
1797 | * |
1798 | * Carefully use d_seq when comparing a candidate dentry, to avoid |
1799 | * races with d_move(). |
1800 | * |
1801 | * It is possible that concurrent renames can mess up our list |
1802 | * walk here and result in missing our dentry, resulting in the |
1803 | * false-negative result. d_lookup() protects against concurrent |
1804 | * renames using rename_lock seqlock. |
1805 | * |
1806 | * See Documentation/vfs/dcache-locking.txt for more details. |
1807 | */ |
1808 | hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) { |
1809 | struct inode *i; |
1810 | const char *tname; |
1811 | int tlen; |
1812 | |
1813 | if (dentry->d_name.hash != hash) |
1814 | continue; |
1815 | |
1816 | seqretry: |
1817 | *seq = read_seqcount_begin(&dentry->d_seq); |
1818 | if (dentry->d_parent != parent) |
1819 | continue; |
1820 | if (d_unhashed(dentry)) |
1821 | continue; |
1822 | tlen = dentry->d_name.len; |
1823 | tname = dentry->d_name.name; |
1824 | i = dentry->d_inode; |
1825 | prefetch(tname); |
1826 | if (i) |
1827 | prefetch(i); |
1828 | /* |
1829 | * This seqcount check is required to ensure name and |
1830 | * len are loaded atomically, so as not to walk off the |
1831 | * edge of memory when walking. If we could load this |
1832 | * atomically some other way, we could drop this check. |
1833 | */ |
1834 | if (read_seqcount_retry(&dentry->d_seq, *seq)) |
1835 | goto seqretry; |
1836 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
1837 | if (parent->d_op->d_compare(parent, *inode, |
1838 | dentry, i, |
1839 | tlen, tname, name)) |
1840 | continue; |
1841 | } else { |
1842 | if (dentry_cmp(tname, tlen, str, len)) |
1843 | continue; |
1844 | } |
1845 | /* |
1846 | * No extra seqcount check is required after the name |
1847 | * compare. The caller must perform a seqcount check in |
1848 | * order to do anything useful with the returned dentry |
1849 | * anyway. |
1850 | */ |
1851 | *inode = i; |
1852 | return dentry; |
1853 | } |
1854 | return NULL; |
1855 | } |
1856 | |
1857 | /** |
1858 | * d_lookup - search for a dentry |
1859 | * @parent: parent dentry |
1860 | * @name: qstr of name we wish to find |
1861 | * Returns: dentry, or NULL |
1862 | * |
1863 | * d_lookup searches the children of the parent dentry for the name in |
1864 | * question. If the dentry is found its reference count is incremented and the |
1865 | * dentry is returned. The caller must use dput to free the entry when it has |
1866 | * finished using it. %NULL is returned if the dentry does not exist. |
1867 | */ |
1868 | struct dentry *d_lookup(struct dentry *parent, struct qstr *name) |
1869 | { |
1870 | struct dentry *dentry; |
1871 | unsigned seq; |
1872 | |
1873 | do { |
1874 | seq = read_seqbegin(&rename_lock); |
1875 | dentry = __d_lookup(parent, name); |
1876 | if (dentry) |
1877 | break; |
1878 | } while (read_seqretry(&rename_lock, seq)); |
1879 | return dentry; |
1880 | } |
1881 | EXPORT_SYMBOL(d_lookup); |
1882 | |
1883 | /** |
1884 | * __d_lookup - search for a dentry (racy) |
1885 | * @parent: parent dentry |
1886 | * @name: qstr of name we wish to find |
1887 | * Returns: dentry, or NULL |
1888 | * |
1889 | * __d_lookup is like d_lookup, however it may (rarely) return a |
1890 | * false-negative result due to unrelated rename activity. |
1891 | * |
1892 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
1893 | * however it must be used carefully, eg. with a following d_lookup in |
1894 | * the case of failure. |
1895 | * |
1896 | * __d_lookup callers must be commented. |
1897 | */ |
1898 | struct dentry *__d_lookup(struct dentry *parent, struct qstr *name) |
1899 | { |
1900 | unsigned int len = name->len; |
1901 | unsigned int hash = name->hash; |
1902 | const unsigned char *str = name->name; |
1903 | struct dcache_hash_bucket *b = d_hash(parent, hash); |
1904 | struct hlist_bl_node *node; |
1905 | struct dentry *found = NULL; |
1906 | struct dentry *dentry; |
1907 | |
1908 | /* |
1909 | * Note: There is significant duplication with __d_lookup_rcu which is |
1910 | * required to prevent single threaded performance regressions |
1911 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
1912 | * Keep the two functions in sync. |
1913 | */ |
1914 | |
1915 | /* |
1916 | * The hash list is protected using RCU. |
1917 | * |
1918 | * Take d_lock when comparing a candidate dentry, to avoid races |
1919 | * with d_move(). |
1920 | * |
1921 | * It is possible that concurrent renames can mess up our list |
1922 | * walk here and result in missing our dentry, resulting in the |
1923 | * false-negative result. d_lookup() protects against concurrent |
1924 | * renames using rename_lock seqlock. |
1925 | * |
1926 | * See Documentation/vfs/dcache-locking.txt for more details. |
1927 | */ |
1928 | rcu_read_lock(); |
1929 | |
1930 | hlist_bl_for_each_entry_rcu(dentry, node, &b->head, d_hash) { |
1931 | const char *tname; |
1932 | int tlen; |
1933 | |
1934 | if (dentry->d_name.hash != hash) |
1935 | continue; |
1936 | |
1937 | spin_lock(&dentry->d_lock); |
1938 | if (dentry->d_parent != parent) |
1939 | goto next; |
1940 | if (d_unhashed(dentry)) |
1941 | goto next; |
1942 | |
1943 | /* |
1944 | * It is safe to compare names since d_move() cannot |
1945 | * change the qstr (protected by d_lock). |
1946 | */ |
1947 | tlen = dentry->d_name.len; |
1948 | tname = dentry->d_name.name; |
1949 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
1950 | if (parent->d_op->d_compare(parent, parent->d_inode, |
1951 | dentry, dentry->d_inode, |
1952 | tlen, tname, name)) |
1953 | goto next; |
1954 | } else { |
1955 | if (dentry_cmp(tname, tlen, str, len)) |
1956 | goto next; |
1957 | } |
1958 | |
1959 | dentry->d_count++; |
1960 | found = dentry; |
1961 | spin_unlock(&dentry->d_lock); |
1962 | break; |
1963 | next: |
1964 | spin_unlock(&dentry->d_lock); |
1965 | } |
1966 | rcu_read_unlock(); |
1967 | |
1968 | return found; |
1969 | } |
1970 | |
1971 | /** |
1972 | * d_hash_and_lookup - hash the qstr then search for a dentry |
1973 | * @dir: Directory to search in |
1974 | * @name: qstr of name we wish to find |
1975 | * |
1976 | * On hash failure or on lookup failure NULL is returned. |
1977 | */ |
1978 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
1979 | { |
1980 | struct dentry *dentry = NULL; |
1981 | |
1982 | /* |
1983 | * Check for a fs-specific hash function. Note that we must |
1984 | * calculate the standard hash first, as the d_op->d_hash() |
1985 | * routine may choose to leave the hash value unchanged. |
1986 | */ |
1987 | name->hash = full_name_hash(name->name, name->len); |
1988 | if (dir->d_flags & DCACHE_OP_HASH) { |
1989 | if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) |
1990 | goto out; |
1991 | } |
1992 | dentry = d_lookup(dir, name); |
1993 | out: |
1994 | return dentry; |
1995 | } |
1996 | |
1997 | /** |
1998 | * d_validate - verify dentry provided from insecure source (deprecated) |
1999 | * @dentry: The dentry alleged to be valid child of @dparent |
2000 | * @dparent: The parent dentry (known to be valid) |
2001 | * |
2002 | * An insecure source has sent us a dentry, here we verify it and dget() it. |
2003 | * This is used by ncpfs in its readdir implementation. |
2004 | * Zero is returned in the dentry is invalid. |
2005 | * |
2006 | * This function is slow for big directories, and deprecated, do not use it. |
2007 | */ |
2008 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
2009 | { |
2010 | struct dentry *child; |
2011 | |
2012 | spin_lock(&dparent->d_lock); |
2013 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
2014 | if (dentry == child) { |
2015 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
2016 | __dget_dlock(dentry); |
2017 | spin_unlock(&dentry->d_lock); |
2018 | spin_unlock(&dparent->d_lock); |
2019 | return 1; |
2020 | } |
2021 | } |
2022 | spin_unlock(&dparent->d_lock); |
2023 | |
2024 | return 0; |
2025 | } |
2026 | EXPORT_SYMBOL(d_validate); |
2027 | |
2028 | /* |
2029 | * When a file is deleted, we have two options: |
2030 | * - turn this dentry into a negative dentry |
2031 | * - unhash this dentry and free it. |
2032 | * |
2033 | * Usually, we want to just turn this into |
2034 | * a negative dentry, but if anybody else is |
2035 | * currently using the dentry or the inode |
2036 | * we can't do that and we fall back on removing |
2037 | * it from the hash queues and waiting for |
2038 | * it to be deleted later when it has no users |
2039 | */ |
2040 | |
2041 | /** |
2042 | * d_delete - delete a dentry |
2043 | * @dentry: The dentry to delete |
2044 | * |
2045 | * Turn the dentry into a negative dentry if possible, otherwise |
2046 | * remove it from the hash queues so it can be deleted later |
2047 | */ |
2048 | |
2049 | void d_delete(struct dentry * dentry) |
2050 | { |
2051 | struct inode *inode; |
2052 | int isdir = 0; |
2053 | /* |
2054 | * Are we the only user? |
2055 | */ |
2056 | again: |
2057 | spin_lock(&dentry->d_lock); |
2058 | inode = dentry->d_inode; |
2059 | isdir = S_ISDIR(inode->i_mode); |
2060 | if (dentry->d_count == 1) { |
2061 | if (inode && !spin_trylock(&inode->i_lock)) { |
2062 | spin_unlock(&dentry->d_lock); |
2063 | cpu_relax(); |
2064 | goto again; |
2065 | } |
2066 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
2067 | dentry_unlink_inode(dentry); |
2068 | fsnotify_nameremove(dentry, isdir); |
2069 | return; |
2070 | } |
2071 | |
2072 | if (!d_unhashed(dentry)) |
2073 | __d_drop(dentry); |
2074 | |
2075 | spin_unlock(&dentry->d_lock); |
2076 | |
2077 | fsnotify_nameremove(dentry, isdir); |
2078 | } |
2079 | EXPORT_SYMBOL(d_delete); |
2080 | |
2081 | static void __d_rehash(struct dentry * entry, struct dcache_hash_bucket *b) |
2082 | { |
2083 | BUG_ON(!d_unhashed(entry)); |
2084 | spin_lock_bucket(b); |
2085 | entry->d_flags &= ~DCACHE_UNHASHED; |
2086 | hlist_bl_add_head_rcu(&entry->d_hash, &b->head); |
2087 | spin_unlock_bucket(b); |
2088 | } |
2089 | |
2090 | static void _d_rehash(struct dentry * entry) |
2091 | { |
2092 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
2093 | } |
2094 | |
2095 | /** |
2096 | * d_rehash - add an entry back to the hash |
2097 | * @entry: dentry to add to the hash |
2098 | * |
2099 | * Adds a dentry to the hash according to its name. |
2100 | */ |
2101 | |
2102 | void d_rehash(struct dentry * entry) |
2103 | { |
2104 | spin_lock(&entry->d_lock); |
2105 | _d_rehash(entry); |
2106 | spin_unlock(&entry->d_lock); |
2107 | } |
2108 | EXPORT_SYMBOL(d_rehash); |
2109 | |
2110 | /** |
2111 | * dentry_update_name_case - update case insensitive dentry with a new name |
2112 | * @dentry: dentry to be updated |
2113 | * @name: new name |
2114 | * |
2115 | * Update a case insensitive dentry with new case of name. |
2116 | * |
2117 | * dentry must have been returned by d_lookup with name @name. Old and new |
2118 | * name lengths must match (ie. no d_compare which allows mismatched name |
2119 | * lengths). |
2120 | * |
2121 | * Parent inode i_mutex must be held over d_lookup and into this call (to |
2122 | * keep renames and concurrent inserts, and readdir(2) away). |
2123 | */ |
2124 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
2125 | { |
2126 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); |
2127 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2128 | |
2129 | spin_lock(&dentry->d_lock); |
2130 | write_seqcount_begin(&dentry->d_seq); |
2131 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
2132 | write_seqcount_end(&dentry->d_seq); |
2133 | spin_unlock(&dentry->d_lock); |
2134 | } |
2135 | EXPORT_SYMBOL(dentry_update_name_case); |
2136 | |
2137 | static void switch_names(struct dentry *dentry, struct dentry *target) |
2138 | { |
2139 | if (dname_external(target)) { |
2140 | if (dname_external(dentry)) { |
2141 | /* |
2142 | * Both external: swap the pointers |
2143 | */ |
2144 | swap(target->d_name.name, dentry->d_name.name); |
2145 | } else { |
2146 | /* |
2147 | * dentry:internal, target:external. Steal target's |
2148 | * storage and make target internal. |
2149 | */ |
2150 | memcpy(target->d_iname, dentry->d_name.name, |
2151 | dentry->d_name.len + 1); |
2152 | dentry->d_name.name = target->d_name.name; |
2153 | target->d_name.name = target->d_iname; |
2154 | } |
2155 | } else { |
2156 | if (dname_external(dentry)) { |
2157 | /* |
2158 | * dentry:external, target:internal. Give dentry's |
2159 | * storage to target and make dentry internal |
2160 | */ |
2161 | memcpy(dentry->d_iname, target->d_name.name, |
2162 | target->d_name.len + 1); |
2163 | target->d_name.name = dentry->d_name.name; |
2164 | dentry->d_name.name = dentry->d_iname; |
2165 | } else { |
2166 | /* |
2167 | * Both are internal. Just copy target to dentry |
2168 | */ |
2169 | memcpy(dentry->d_iname, target->d_name.name, |
2170 | target->d_name.len + 1); |
2171 | dentry->d_name.len = target->d_name.len; |
2172 | return; |
2173 | } |
2174 | } |
2175 | swap(dentry->d_name.len, target->d_name.len); |
2176 | } |
2177 | |
2178 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2179 | { |
2180 | /* |
2181 | * XXXX: do we really need to take target->d_lock? |
2182 | */ |
2183 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) |
2184 | spin_lock(&target->d_parent->d_lock); |
2185 | else { |
2186 | if (d_ancestor(dentry->d_parent, target->d_parent)) { |
2187 | spin_lock(&dentry->d_parent->d_lock); |
2188 | spin_lock_nested(&target->d_parent->d_lock, |
2189 | DENTRY_D_LOCK_NESTED); |
2190 | } else { |
2191 | spin_lock(&target->d_parent->d_lock); |
2192 | spin_lock_nested(&dentry->d_parent->d_lock, |
2193 | DENTRY_D_LOCK_NESTED); |
2194 | } |
2195 | } |
2196 | if (target < dentry) { |
2197 | spin_lock_nested(&target->d_lock, 2); |
2198 | spin_lock_nested(&dentry->d_lock, 3); |
2199 | } else { |
2200 | spin_lock_nested(&dentry->d_lock, 2); |
2201 | spin_lock_nested(&target->d_lock, 3); |
2202 | } |
2203 | } |
2204 | |
2205 | static void dentry_unlock_parents_for_move(struct dentry *dentry, |
2206 | struct dentry *target) |
2207 | { |
2208 | if (target->d_parent != dentry->d_parent) |
2209 | spin_unlock(&dentry->d_parent->d_lock); |
2210 | if (target->d_parent != target) |
2211 | spin_unlock(&target->d_parent->d_lock); |
2212 | } |
2213 | |
2214 | /* |
2215 | * When switching names, the actual string doesn't strictly have to |
2216 | * be preserved in the target - because we're dropping the target |
2217 | * anyway. As such, we can just do a simple memcpy() to copy over |
2218 | * the new name before we switch. |
2219 | * |
2220 | * Note that we have to be a lot more careful about getting the hash |
2221 | * switched - we have to switch the hash value properly even if it |
2222 | * then no longer matches the actual (corrupted) string of the target. |
2223 | * The hash value has to match the hash queue that the dentry is on.. |
2224 | */ |
2225 | /* |
2226 | * d_move - move a dentry |
2227 | * @dentry: entry to move |
2228 | * @target: new dentry |
2229 | * |
2230 | * Update the dcache to reflect the move of a file name. Negative |
2231 | * dcache entries should not be moved in this way. |
2232 | */ |
2233 | void d_move(struct dentry * dentry, struct dentry * target) |
2234 | { |
2235 | if (!dentry->d_inode) |
2236 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
2237 | |
2238 | BUG_ON(d_ancestor(dentry, target)); |
2239 | BUG_ON(d_ancestor(target, dentry)); |
2240 | |
2241 | write_seqlock(&rename_lock); |
2242 | |
2243 | dentry_lock_for_move(dentry, target); |
2244 | |
2245 | write_seqcount_begin(&dentry->d_seq); |
2246 | write_seqcount_begin(&target->d_seq); |
2247 | |
2248 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2249 | |
2250 | /* |
2251 | * Move the dentry to the target hash queue. Don't bother checking |
2252 | * for the same hash queue because of how unlikely it is. |
2253 | */ |
2254 | __d_drop(dentry); |
2255 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
2256 | |
2257 | /* Unhash the target: dput() will then get rid of it */ |
2258 | __d_drop(target); |
2259 | |
2260 | list_del(&dentry->d_u.d_child); |
2261 | list_del(&target->d_u.d_child); |
2262 | |
2263 | /* Switch the names.. */ |
2264 | switch_names(dentry, target); |
2265 | swap(dentry->d_name.hash, target->d_name.hash); |
2266 | |
2267 | /* ... and switch the parents */ |
2268 | if (IS_ROOT(dentry)) { |
2269 | dentry->d_parent = target->d_parent; |
2270 | target->d_parent = target; |
2271 | INIT_LIST_HEAD(&target->d_u.d_child); |
2272 | } else { |
2273 | swap(dentry->d_parent, target->d_parent); |
2274 | |
2275 | /* And add them back to the (new) parent lists */ |
2276 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
2277 | } |
2278 | |
2279 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2280 | |
2281 | write_seqcount_end(&target->d_seq); |
2282 | write_seqcount_end(&dentry->d_seq); |
2283 | |
2284 | dentry_unlock_parents_for_move(dentry, target); |
2285 | spin_unlock(&target->d_lock); |
2286 | fsnotify_d_move(dentry); |
2287 | spin_unlock(&dentry->d_lock); |
2288 | write_sequnlock(&rename_lock); |
2289 | } |
2290 | EXPORT_SYMBOL(d_move); |
2291 | |
2292 | /** |
2293 | * d_ancestor - search for an ancestor |
2294 | * @p1: ancestor dentry |
2295 | * @p2: child dentry |
2296 | * |
2297 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
2298 | * an ancestor of p2, else NULL. |
2299 | */ |
2300 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
2301 | { |
2302 | struct dentry *p; |
2303 | |
2304 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
2305 | if (p->d_parent == p1) |
2306 | return p; |
2307 | } |
2308 | return NULL; |
2309 | } |
2310 | |
2311 | /* |
2312 | * This helper attempts to cope with remotely renamed directories |
2313 | * |
2314 | * It assumes that the caller is already holding |
2315 | * dentry->d_parent->d_inode->i_mutex and the inode->i_lock |
2316 | * |
2317 | * Note: If ever the locking in lock_rename() changes, then please |
2318 | * remember to update this too... |
2319 | */ |
2320 | static struct dentry *__d_unalias(struct inode *inode, |
2321 | struct dentry *dentry, struct dentry *alias) |
2322 | { |
2323 | struct mutex *m1 = NULL, *m2 = NULL; |
2324 | struct dentry *ret; |
2325 | |
2326 | /* If alias and dentry share a parent, then no extra locks required */ |
2327 | if (alias->d_parent == dentry->d_parent) |
2328 | goto out_unalias; |
2329 | |
2330 | /* Check for loops */ |
2331 | ret = ERR_PTR(-ELOOP); |
2332 | if (d_ancestor(alias, dentry)) |
2333 | goto out_err; |
2334 | |
2335 | /* See lock_rename() */ |
2336 | ret = ERR_PTR(-EBUSY); |
2337 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2338 | goto out_err; |
2339 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
2340 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
2341 | goto out_err; |
2342 | m2 = &alias->d_parent->d_inode->i_mutex; |
2343 | out_unalias: |
2344 | d_move(alias, dentry); |
2345 | ret = alias; |
2346 | out_err: |
2347 | spin_unlock(&inode->i_lock); |
2348 | if (m2) |
2349 | mutex_unlock(m2); |
2350 | if (m1) |
2351 | mutex_unlock(m1); |
2352 | return ret; |
2353 | } |
2354 | |
2355 | /* |
2356 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a |
2357 | * named dentry in place of the dentry to be replaced. |
2358 | * returns with anon->d_lock held! |
2359 | */ |
2360 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) |
2361 | { |
2362 | struct dentry *dparent, *aparent; |
2363 | |
2364 | dentry_lock_for_move(anon, dentry); |
2365 | |
2366 | write_seqcount_begin(&dentry->d_seq); |
2367 | write_seqcount_begin(&anon->d_seq); |
2368 | |
2369 | dparent = dentry->d_parent; |
2370 | aparent = anon->d_parent; |
2371 | |
2372 | switch_names(dentry, anon); |
2373 | swap(dentry->d_name.hash, anon->d_name.hash); |
2374 | |
2375 | dentry->d_parent = (aparent == anon) ? dentry : aparent; |
2376 | list_del(&dentry->d_u.d_child); |
2377 | if (!IS_ROOT(dentry)) |
2378 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2379 | else |
2380 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
2381 | |
2382 | anon->d_parent = (dparent == dentry) ? anon : dparent; |
2383 | list_del(&anon->d_u.d_child); |
2384 | if (!IS_ROOT(anon)) |
2385 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); |
2386 | else |
2387 | INIT_LIST_HEAD(&anon->d_u.d_child); |
2388 | |
2389 | write_seqcount_end(&dentry->d_seq); |
2390 | write_seqcount_end(&anon->d_seq); |
2391 | |
2392 | dentry_unlock_parents_for_move(anon, dentry); |
2393 | spin_unlock(&dentry->d_lock); |
2394 | |
2395 | /* anon->d_lock still locked, returns locked */ |
2396 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
2397 | } |
2398 | |
2399 | /** |
2400 | * d_materialise_unique - introduce an inode into the tree |
2401 | * @dentry: candidate dentry |
2402 | * @inode: inode to bind to the dentry, to which aliases may be attached |
2403 | * |
2404 | * Introduces an dentry into the tree, substituting an extant disconnected |
2405 | * root directory alias in its place if there is one |
2406 | */ |
2407 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) |
2408 | { |
2409 | struct dentry *actual; |
2410 | |
2411 | BUG_ON(!d_unhashed(dentry)); |
2412 | |
2413 | if (!inode) { |
2414 | actual = dentry; |
2415 | __d_instantiate(dentry, NULL); |
2416 | d_rehash(actual); |
2417 | goto out_nolock; |
2418 | } |
2419 | |
2420 | spin_lock(&inode->i_lock); |
2421 | |
2422 | if (S_ISDIR(inode->i_mode)) { |
2423 | struct dentry *alias; |
2424 | |
2425 | /* Does an aliased dentry already exist? */ |
2426 | alias = __d_find_alias(inode, 0); |
2427 | if (alias) { |
2428 | actual = alias; |
2429 | /* Is this an anonymous mountpoint that we could splice |
2430 | * into our tree? */ |
2431 | if (IS_ROOT(alias)) { |
2432 | __d_materialise_dentry(dentry, alias); |
2433 | __d_drop(alias); |
2434 | goto found; |
2435 | } |
2436 | /* Nope, but we must(!) avoid directory aliasing */ |
2437 | actual = __d_unalias(inode, dentry, alias); |
2438 | if (IS_ERR(actual)) |
2439 | dput(alias); |
2440 | goto out_nolock; |
2441 | } |
2442 | } |
2443 | |
2444 | /* Add a unique reference */ |
2445 | actual = __d_instantiate_unique(dentry, inode); |
2446 | if (!actual) |
2447 | actual = dentry; |
2448 | else |
2449 | BUG_ON(!d_unhashed(actual)); |
2450 | |
2451 | spin_lock(&actual->d_lock); |
2452 | found: |
2453 | _d_rehash(actual); |
2454 | spin_unlock(&actual->d_lock); |
2455 | spin_unlock(&inode->i_lock); |
2456 | out_nolock: |
2457 | if (actual == dentry) { |
2458 | security_d_instantiate(dentry, inode); |
2459 | return NULL; |
2460 | } |
2461 | |
2462 | iput(inode); |
2463 | return actual; |
2464 | } |
2465 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
2466 | |
2467 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
2468 | { |
2469 | *buflen -= namelen; |
2470 | if (*buflen < 0) |
2471 | return -ENAMETOOLONG; |
2472 | *buffer -= namelen; |
2473 | memcpy(*buffer, str, namelen); |
2474 | return 0; |
2475 | } |
2476 | |
2477 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2478 | { |
2479 | return prepend(buffer, buflen, name->name, name->len); |
2480 | } |
2481 | |
2482 | /** |
2483 | * prepend_path - Prepend path string to a buffer |
2484 | * @path: the dentry/vfsmount to report |
2485 | * @root: root vfsmnt/dentry (may be modified by this function) |
2486 | * @buffer: pointer to the end of the buffer |
2487 | * @buflen: pointer to buffer length |
2488 | * |
2489 | * Caller holds the rename_lock. |
2490 | * |
2491 | * If path is not reachable from the supplied root, then the value of |
2492 | * root is changed (without modifying refcounts). |
2493 | */ |
2494 | static int prepend_path(const struct path *path, struct path *root, |
2495 | char **buffer, int *buflen) |
2496 | { |
2497 | struct dentry *dentry = path->dentry; |
2498 | struct vfsmount *vfsmnt = path->mnt; |
2499 | bool slash = false; |
2500 | int error = 0; |
2501 | |
2502 | br_read_lock(vfsmount_lock); |
2503 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
2504 | struct dentry * parent; |
2505 | |
2506 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
2507 | /* Global root? */ |
2508 | if (vfsmnt->mnt_parent == vfsmnt) { |
2509 | goto global_root; |
2510 | } |
2511 | dentry = vfsmnt->mnt_mountpoint; |
2512 | vfsmnt = vfsmnt->mnt_parent; |
2513 | continue; |
2514 | } |
2515 | parent = dentry->d_parent; |
2516 | prefetch(parent); |
2517 | spin_lock(&dentry->d_lock); |
2518 | error = prepend_name(buffer, buflen, &dentry->d_name); |
2519 | spin_unlock(&dentry->d_lock); |
2520 | if (!error) |
2521 | error = prepend(buffer, buflen, "/", 1); |
2522 | if (error) |
2523 | break; |
2524 | |
2525 | slash = true; |
2526 | dentry = parent; |
2527 | } |
2528 | |
2529 | out: |
2530 | if (!error && !slash) |
2531 | error = prepend(buffer, buflen, "/", 1); |
2532 | |
2533 | br_read_unlock(vfsmount_lock); |
2534 | return error; |
2535 | |
2536 | global_root: |
2537 | /* |
2538 | * Filesystems needing to implement special "root names" |
2539 | * should do so with ->d_dname() |
2540 | */ |
2541 | if (IS_ROOT(dentry) && |
2542 | (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { |
2543 | WARN(1, "Root dentry has weird name <%.*s>\n", |
2544 | (int) dentry->d_name.len, dentry->d_name.name); |
2545 | } |
2546 | root->mnt = vfsmnt; |
2547 | root->dentry = dentry; |
2548 | goto out; |
2549 | } |
2550 | |
2551 | /** |
2552 | * __d_path - return the path of a dentry |
2553 | * @path: the dentry/vfsmount to report |
2554 | * @root: root vfsmnt/dentry (may be modified by this function) |
2555 | * @buf: buffer to return value in |
2556 | * @buflen: buffer length |
2557 | * |
2558 | * Convert a dentry into an ASCII path name. |
2559 | * |
2560 | * Returns a pointer into the buffer or an error code if the |
2561 | * path was too long. |
2562 | * |
2563 | * "buflen" should be positive. |
2564 | * |
2565 | * If path is not reachable from the supplied root, then the value of |
2566 | * root is changed (without modifying refcounts). |
2567 | */ |
2568 | char *__d_path(const struct path *path, struct path *root, |
2569 | char *buf, int buflen) |
2570 | { |
2571 | char *res = buf + buflen; |
2572 | int error; |
2573 | |
2574 | prepend(&res, &buflen, "\0", 1); |
2575 | write_seqlock(&rename_lock); |
2576 | error = prepend_path(path, root, &res, &buflen); |
2577 | write_sequnlock(&rename_lock); |
2578 | |
2579 | if (error) |
2580 | return ERR_PTR(error); |
2581 | return res; |
2582 | } |
2583 | |
2584 | /* |
2585 | * same as __d_path but appends "(deleted)" for unlinked files. |
2586 | */ |
2587 | static int path_with_deleted(const struct path *path, struct path *root, |
2588 | char **buf, int *buflen) |
2589 | { |
2590 | prepend(buf, buflen, "\0", 1); |
2591 | if (d_unlinked(path->dentry)) { |
2592 | int error = prepend(buf, buflen, " (deleted)", 10); |
2593 | if (error) |
2594 | return error; |
2595 | } |
2596 | |
2597 | return prepend_path(path, root, buf, buflen); |
2598 | } |
2599 | |
2600 | static int prepend_unreachable(char **buffer, int *buflen) |
2601 | { |
2602 | return prepend(buffer, buflen, "(unreachable)", 13); |
2603 | } |
2604 | |
2605 | /** |
2606 | * d_path - return the path of a dentry |
2607 | * @path: path to report |
2608 | * @buf: buffer to return value in |
2609 | * @buflen: buffer length |
2610 | * |
2611 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
2612 | * the string " (deleted)" is appended. Note that this is ambiguous. |
2613 | * |
2614 | * Returns a pointer into the buffer or an error code if the path was |
2615 | * too long. Note: Callers should use the returned pointer, not the passed |
2616 | * in buffer, to use the name! The implementation often starts at an offset |
2617 | * into the buffer, and may leave 0 bytes at the start. |
2618 | * |
2619 | * "buflen" should be positive. |
2620 | */ |
2621 | char *d_path(const struct path *path, char *buf, int buflen) |
2622 | { |
2623 | char *res = buf + buflen; |
2624 | struct path root; |
2625 | struct path tmp; |
2626 | int error; |
2627 | |
2628 | /* |
2629 | * We have various synthetic filesystems that never get mounted. On |
2630 | * these filesystems dentries are never used for lookup purposes, and |
2631 | * thus don't need to be hashed. They also don't need a name until a |
2632 | * user wants to identify the object in /proc/pid/fd/. The little hack |
2633 | * below allows us to generate a name for these objects on demand: |
2634 | */ |
2635 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2636 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
2637 | |
2638 | get_fs_root(current->fs, &root); |
2639 | write_seqlock(&rename_lock); |
2640 | tmp = root; |
2641 | error = path_with_deleted(path, &tmp, &res, &buflen); |
2642 | if (error) |
2643 | res = ERR_PTR(error); |
2644 | write_sequnlock(&rename_lock); |
2645 | path_put(&root); |
2646 | return res; |
2647 | } |
2648 | EXPORT_SYMBOL(d_path); |
2649 | |
2650 | /** |
2651 | * d_path_with_unreachable - return the path of a dentry |
2652 | * @path: path to report |
2653 | * @buf: buffer to return value in |
2654 | * @buflen: buffer length |
2655 | * |
2656 | * The difference from d_path() is that this prepends "(unreachable)" |
2657 | * to paths which are unreachable from the current process' root. |
2658 | */ |
2659 | char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) |
2660 | { |
2661 | char *res = buf + buflen; |
2662 | struct path root; |
2663 | struct path tmp; |
2664 | int error; |
2665 | |
2666 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2667 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
2668 | |
2669 | get_fs_root(current->fs, &root); |
2670 | write_seqlock(&rename_lock); |
2671 | tmp = root; |
2672 | error = path_with_deleted(path, &tmp, &res, &buflen); |
2673 | if (!error && !path_equal(&tmp, &root)) |
2674 | error = prepend_unreachable(&res, &buflen); |
2675 | write_sequnlock(&rename_lock); |
2676 | path_put(&root); |
2677 | if (error) |
2678 | res = ERR_PTR(error); |
2679 | |
2680 | return res; |
2681 | } |
2682 | |
2683 | /* |
2684 | * Helper function for dentry_operations.d_dname() members |
2685 | */ |
2686 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
2687 | const char *fmt, ...) |
2688 | { |
2689 | va_list args; |
2690 | char temp[64]; |
2691 | int sz; |
2692 | |
2693 | va_start(args, fmt); |
2694 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
2695 | va_end(args); |
2696 | |
2697 | if (sz > sizeof(temp) || sz > buflen) |
2698 | return ERR_PTR(-ENAMETOOLONG); |
2699 | |
2700 | buffer += buflen - sz; |
2701 | return memcpy(buffer, temp, sz); |
2702 | } |
2703 | |
2704 | /* |
2705 | * Write full pathname from the root of the filesystem into the buffer. |
2706 | */ |
2707 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
2708 | { |
2709 | char *end = buf + buflen; |
2710 | char *retval; |
2711 | |
2712 | prepend(&end, &buflen, "\0", 1); |
2713 | if (buflen < 1) |
2714 | goto Elong; |
2715 | /* Get '/' right */ |
2716 | retval = end-1; |
2717 | *retval = '/'; |
2718 | |
2719 | while (!IS_ROOT(dentry)) { |
2720 | struct dentry *parent = dentry->d_parent; |
2721 | int error; |
2722 | |
2723 | prefetch(parent); |
2724 | spin_lock(&dentry->d_lock); |
2725 | error = prepend_name(&end, &buflen, &dentry->d_name); |
2726 | spin_unlock(&dentry->d_lock); |
2727 | if (error != 0 || prepend(&end, &buflen, "/", 1) != 0) |
2728 | goto Elong; |
2729 | |
2730 | retval = end; |
2731 | dentry = parent; |
2732 | } |
2733 | return retval; |
2734 | Elong: |
2735 | return ERR_PTR(-ENAMETOOLONG); |
2736 | } |
2737 | |
2738 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
2739 | { |
2740 | char *retval; |
2741 | |
2742 | write_seqlock(&rename_lock); |
2743 | retval = __dentry_path(dentry, buf, buflen); |
2744 | write_sequnlock(&rename_lock); |
2745 | |
2746 | return retval; |
2747 | } |
2748 | EXPORT_SYMBOL(dentry_path_raw); |
2749 | |
2750 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
2751 | { |
2752 | char *p = NULL; |
2753 | char *retval; |
2754 | |
2755 | write_seqlock(&rename_lock); |
2756 | if (d_unlinked(dentry)) { |
2757 | p = buf + buflen; |
2758 | if (prepend(&p, &buflen, "//deleted", 10) != 0) |
2759 | goto Elong; |
2760 | buflen++; |
2761 | } |
2762 | retval = __dentry_path(dentry, buf, buflen); |
2763 | write_sequnlock(&rename_lock); |
2764 | if (!IS_ERR(retval) && p) |
2765 | *p = '/'; /* restore '/' overriden with '\0' */ |
2766 | return retval; |
2767 | Elong: |
2768 | return ERR_PTR(-ENAMETOOLONG); |
2769 | } |
2770 | |
2771 | /* |
2772 | * NOTE! The user-level library version returns a |
2773 | * character pointer. The kernel system call just |
2774 | * returns the length of the buffer filled (which |
2775 | * includes the ending '\0' character), or a negative |
2776 | * error value. So libc would do something like |
2777 | * |
2778 | * char *getcwd(char * buf, size_t size) |
2779 | * { |
2780 | * int retval; |
2781 | * |
2782 | * retval = sys_getcwd(buf, size); |
2783 | * if (retval >= 0) |
2784 | * return buf; |
2785 | * errno = -retval; |
2786 | * return NULL; |
2787 | * } |
2788 | */ |
2789 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
2790 | { |
2791 | int error; |
2792 | struct path pwd, root; |
2793 | char *page = (char *) __get_free_page(GFP_USER); |
2794 | |
2795 | if (!page) |
2796 | return -ENOMEM; |
2797 | |
2798 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
2799 | |
2800 | error = -ENOENT; |
2801 | write_seqlock(&rename_lock); |
2802 | if (!d_unlinked(pwd.dentry)) { |
2803 | unsigned long len; |
2804 | struct path tmp = root; |
2805 | char *cwd = page + PAGE_SIZE; |
2806 | int buflen = PAGE_SIZE; |
2807 | |
2808 | prepend(&cwd, &buflen, "\0", 1); |
2809 | error = prepend_path(&pwd, &tmp, &cwd, &buflen); |
2810 | write_sequnlock(&rename_lock); |
2811 | |
2812 | if (error) |
2813 | goto out; |
2814 | |
2815 | /* Unreachable from current root */ |
2816 | if (!path_equal(&tmp, &root)) { |
2817 | error = prepend_unreachable(&cwd, &buflen); |
2818 | if (error) |
2819 | goto out; |
2820 | } |
2821 | |
2822 | error = -ERANGE; |
2823 | len = PAGE_SIZE + page - cwd; |
2824 | if (len <= size) { |
2825 | error = len; |
2826 | if (copy_to_user(buf, cwd, len)) |
2827 | error = -EFAULT; |
2828 | } |
2829 | } else { |
2830 | write_sequnlock(&rename_lock); |
2831 | } |
2832 | |
2833 | out: |
2834 | path_put(&pwd); |
2835 | path_put(&root); |
2836 | free_page((unsigned long) page); |
2837 | return error; |
2838 | } |
2839 | |
2840 | /* |
2841 | * Test whether new_dentry is a subdirectory of old_dentry. |
2842 | * |
2843 | * Trivially implemented using the dcache structure |
2844 | */ |
2845 | |
2846 | /** |
2847 | * is_subdir - is new dentry a subdirectory of old_dentry |
2848 | * @new_dentry: new dentry |
2849 | * @old_dentry: old dentry |
2850 | * |
2851 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
2852 | * Returns 0 otherwise. |
2853 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
2854 | */ |
2855 | |
2856 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
2857 | { |
2858 | int result; |
2859 | unsigned seq; |
2860 | |
2861 | if (new_dentry == old_dentry) |
2862 | return 1; |
2863 | |
2864 | do { |
2865 | /* for restarting inner loop in case of seq retry */ |
2866 | seq = read_seqbegin(&rename_lock); |
2867 | /* |
2868 | * Need rcu_readlock to protect against the d_parent trashing |
2869 | * due to d_move |
2870 | */ |
2871 | rcu_read_lock(); |
2872 | if (d_ancestor(old_dentry, new_dentry)) |
2873 | result = 1; |
2874 | else |
2875 | result = 0; |
2876 | rcu_read_unlock(); |
2877 | } while (read_seqretry(&rename_lock, seq)); |
2878 | |
2879 | return result; |
2880 | } |
2881 | |
2882 | int path_is_under(struct path *path1, struct path *path2) |
2883 | { |
2884 | struct vfsmount *mnt = path1->mnt; |
2885 | struct dentry *dentry = path1->dentry; |
2886 | int res; |
2887 | |
2888 | br_read_lock(vfsmount_lock); |
2889 | if (mnt != path2->mnt) { |
2890 | for (;;) { |
2891 | if (mnt->mnt_parent == mnt) { |
2892 | br_read_unlock(vfsmount_lock); |
2893 | return 0; |
2894 | } |
2895 | if (mnt->mnt_parent == path2->mnt) |
2896 | break; |
2897 | mnt = mnt->mnt_parent; |
2898 | } |
2899 | dentry = mnt->mnt_mountpoint; |
2900 | } |
2901 | res = is_subdir(dentry, path2->dentry); |
2902 | br_read_unlock(vfsmount_lock); |
2903 | return res; |
2904 | } |
2905 | EXPORT_SYMBOL(path_is_under); |
2906 | |
2907 | void d_genocide(struct dentry *root) |
2908 | { |
2909 | struct dentry *this_parent; |
2910 | struct list_head *next; |
2911 | unsigned seq; |
2912 | int locked = 0; |
2913 | |
2914 | seq = read_seqbegin(&rename_lock); |
2915 | again: |
2916 | this_parent = root; |
2917 | spin_lock(&this_parent->d_lock); |
2918 | repeat: |
2919 | next = this_parent->d_subdirs.next; |
2920 | resume: |
2921 | while (next != &this_parent->d_subdirs) { |
2922 | struct list_head *tmp = next; |
2923 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
2924 | next = tmp->next; |
2925 | |
2926 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
2927 | if (d_unhashed(dentry) || !dentry->d_inode) { |
2928 | spin_unlock(&dentry->d_lock); |
2929 | continue; |
2930 | } |
2931 | if (!list_empty(&dentry->d_subdirs)) { |
2932 | spin_unlock(&this_parent->d_lock); |
2933 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
2934 | this_parent = dentry; |
2935 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
2936 | goto repeat; |
2937 | } |
2938 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
2939 | dentry->d_flags |= DCACHE_GENOCIDE; |
2940 | dentry->d_count--; |
2941 | } |
2942 | spin_unlock(&dentry->d_lock); |
2943 | } |
2944 | if (this_parent != root) { |
2945 | struct dentry *tmp; |
2946 | struct dentry *child; |
2947 | |
2948 | tmp = this_parent->d_parent; |
2949 | if (!(this_parent->d_flags & DCACHE_GENOCIDE)) { |
2950 | this_parent->d_flags |= DCACHE_GENOCIDE; |
2951 | this_parent->d_count--; |
2952 | } |
2953 | rcu_read_lock(); |
2954 | spin_unlock(&this_parent->d_lock); |
2955 | child = this_parent; |
2956 | this_parent = tmp; |
2957 | spin_lock(&this_parent->d_lock); |
2958 | /* might go back up the wrong parent if we have had a rename |
2959 | * or deletion */ |
2960 | if (this_parent != child->d_parent || |
2961 | (!locked && read_seqretry(&rename_lock, seq))) { |
2962 | spin_unlock(&this_parent->d_lock); |
2963 | rcu_read_unlock(); |
2964 | goto rename_retry; |
2965 | } |
2966 | rcu_read_unlock(); |
2967 | next = child->d_u.d_child.next; |
2968 | goto resume; |
2969 | } |
2970 | spin_unlock(&this_parent->d_lock); |
2971 | if (!locked && read_seqretry(&rename_lock, seq)) |
2972 | goto rename_retry; |
2973 | if (locked) |
2974 | write_sequnlock(&rename_lock); |
2975 | return; |
2976 | |
2977 | rename_retry: |
2978 | locked = 1; |
2979 | write_seqlock(&rename_lock); |
2980 | goto again; |
2981 | } |
2982 | |
2983 | /** |
2984 | * find_inode_number - check for dentry with name |
2985 | * @dir: directory to check |
2986 | * @name: Name to find. |
2987 | * |
2988 | * Check whether a dentry already exists for the given name, |
2989 | * and return the inode number if it has an inode. Otherwise |
2990 | * 0 is returned. |
2991 | * |
2992 | * This routine is used to post-process directory listings for |
2993 | * filesystems using synthetic inode numbers, and is necessary |
2994 | * to keep getcwd() working. |
2995 | */ |
2996 | |
2997 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) |
2998 | { |
2999 | struct dentry * dentry; |
3000 | ino_t ino = 0; |
3001 | |
3002 | dentry = d_hash_and_lookup(dir, name); |
3003 | if (dentry) { |
3004 | if (dentry->d_inode) |
3005 | ino = dentry->d_inode->i_ino; |
3006 | dput(dentry); |
3007 | } |
3008 | return ino; |
3009 | } |
3010 | EXPORT_SYMBOL(find_inode_number); |
3011 | |
3012 | static __initdata unsigned long dhash_entries; |
3013 | static int __init set_dhash_entries(char *str) |
3014 | { |
3015 | if (!str) |
3016 | return 0; |
3017 | dhash_entries = simple_strtoul(str, &str, 0); |
3018 | return 1; |
3019 | } |
3020 | __setup("dhash_entries=", set_dhash_entries); |
3021 | |
3022 | static void __init dcache_init_early(void) |
3023 | { |
3024 | int loop; |
3025 | |
3026 | /* If hashes are distributed across NUMA nodes, defer |
3027 | * hash allocation until vmalloc space is available. |
3028 | */ |
3029 | if (hashdist) |
3030 | return; |
3031 | |
3032 | dentry_hashtable = |
3033 | alloc_large_system_hash("Dentry cache", |
3034 | sizeof(struct dcache_hash_bucket), |
3035 | dhash_entries, |
3036 | 13, |
3037 | HASH_EARLY, |
3038 | &d_hash_shift, |
3039 | &d_hash_mask, |
3040 | 0); |
3041 | |
3042 | for (loop = 0; loop < (1 << d_hash_shift); loop++) |
3043 | INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head); |
3044 | } |
3045 | |
3046 | static void __init dcache_init(void) |
3047 | { |
3048 | int loop; |
3049 | |
3050 | /* |
3051 | * A constructor could be added for stable state like the lists, |
3052 | * but it is probably not worth it because of the cache nature |
3053 | * of the dcache. |
3054 | */ |
3055 | dentry_cache = KMEM_CACHE(dentry, |
3056 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
3057 | |
3058 | register_shrinker(&dcache_shrinker); |
3059 | |
3060 | /* Hash may have been set up in dcache_init_early */ |
3061 | if (!hashdist) |
3062 | return; |
3063 | |
3064 | dentry_hashtable = |
3065 | alloc_large_system_hash("Dentry cache", |
3066 | sizeof(struct dcache_hash_bucket), |
3067 | dhash_entries, |
3068 | 13, |
3069 | 0, |
3070 | &d_hash_shift, |
3071 | &d_hash_mask, |
3072 | 0); |
3073 | |
3074 | for (loop = 0; loop < (1 << d_hash_shift); loop++) |
3075 | INIT_HLIST_BL_HEAD(&dentry_hashtable[loop].head); |
3076 | } |
3077 | |
3078 | /* SLAB cache for __getname() consumers */ |
3079 | struct kmem_cache *names_cachep __read_mostly; |
3080 | EXPORT_SYMBOL(names_cachep); |
3081 | |
3082 | EXPORT_SYMBOL(d_genocide); |
3083 | |
3084 | void __init vfs_caches_init_early(void) |
3085 | { |
3086 | dcache_init_early(); |
3087 | inode_init_early(); |
3088 | } |
3089 | |
3090 | void __init vfs_caches_init(unsigned long mempages) |
3091 | { |
3092 | unsigned long reserve; |
3093 | |
3094 | /* Base hash sizes on available memory, with a reserve equal to |
3095 | 150% of current kernel size */ |
3096 | |
3097 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); |
3098 | mempages -= reserve; |
3099 | |
3100 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
3101 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
3102 | |
3103 | dcache_init(); |
3104 | inode_init(); |
3105 | files_init(mempages); |
3106 | mnt_init(); |
3107 | bdev_cache_init(); |
3108 | chrdev_init(); |
3109 | } |
3110 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9