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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/export.h> |
27 | #include <linux/mount.h> |
28 | #include <linux/file.h> |
29 | #include <asm/uaccess.h> |
30 | #include <linux/security.h> |
31 | #include <linux/seqlock.h> |
32 | #include <linux/swap.h> |
33 | #include <linux/bootmem.h> |
34 | #include <linux/fs_struct.h> |
35 | #include <linux/hardirq.h> |
36 | #include <linux/bit_spinlock.h> |
37 | #include <linux/rculist_bl.h> |
38 | #include <linux/prefetch.h> |
39 | #include <linux/ratelimit.h> |
40 | #include "internal.h" |
41 | #include "mount.h" |
42 | |
43 | /* |
44 | * Usage: |
45 | * dcache->d_inode->i_lock protects: |
46 | * - i_dentry, d_alias, d_inode of aliases |
47 | * dcache_hash_bucket lock protects: |
48 | * - the dcache hash table |
49 | * s_anon bl list spinlock protects: |
50 | * - the s_anon list (see __d_drop) |
51 | * dcache_lru_lock protects: |
52 | * - the dcache lru lists and counters |
53 | * d_lock protects: |
54 | * - d_flags |
55 | * - d_name |
56 | * - d_lru |
57 | * - d_count |
58 | * - d_unhashed() |
59 | * - d_parent and d_subdirs |
60 | * - childrens' d_child and d_parent |
61 | * - d_alias, d_inode |
62 | * |
63 | * Ordering: |
64 | * dentry->d_inode->i_lock |
65 | * dentry->d_lock |
66 | * dcache_lru_lock |
67 | * dcache_hash_bucket lock |
68 | * s_anon lock |
69 | * |
70 | * If there is an ancestor relationship: |
71 | * dentry->d_parent->...->d_parent->d_lock |
72 | * ... |
73 | * dentry->d_parent->d_lock |
74 | * dentry->d_lock |
75 | * |
76 | * If no ancestor relationship: |
77 | * if (dentry1 < dentry2) |
78 | * dentry1->d_lock |
79 | * dentry2->d_lock |
80 | */ |
81 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
82 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
83 | |
84 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); |
85 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
86 | |
87 | EXPORT_SYMBOL(rename_lock); |
88 | |
89 | static struct kmem_cache *dentry_cache __read_mostly; |
90 | |
91 | /* |
92 | * This is the single most critical data structure when it comes |
93 | * to the dcache: the hashtable for lookups. Somebody should try |
94 | * to make this good - I've just made it work. |
95 | * |
96 | * This hash-function tries to avoid losing too many bits of hash |
97 | * information, yet avoid using a prime hash-size or similar. |
98 | */ |
99 | #define D_HASHBITS d_hash_shift |
100 | #define D_HASHMASK d_hash_mask |
101 | |
102 | static unsigned int d_hash_mask __read_mostly; |
103 | static unsigned int d_hash_shift __read_mostly; |
104 | |
105 | static struct hlist_bl_head *dentry_hashtable __read_mostly; |
106 | |
107 | static inline struct hlist_bl_head *d_hash(const struct dentry *parent, |
108 | unsigned int hash) |
109 | { |
110 | hash += (unsigned long) parent / L1_CACHE_BYTES; |
111 | hash = hash + (hash >> D_HASHBITS); |
112 | return dentry_hashtable + (hash & D_HASHMASK); |
113 | } |
114 | |
115 | /* Statistics gathering. */ |
116 | struct dentry_stat_t dentry_stat = { |
117 | .age_limit = 45, |
118 | }; |
119 | |
120 | static DEFINE_PER_CPU(unsigned int, nr_dentry); |
121 | |
122 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
123 | static int get_nr_dentry(void) |
124 | { |
125 | int i; |
126 | int sum = 0; |
127 | for_each_possible_cpu(i) |
128 | sum += per_cpu(nr_dentry, i); |
129 | return sum < 0 ? 0 : sum; |
130 | } |
131 | |
132 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
133 | size_t *lenp, loff_t *ppos) |
134 | { |
135 | dentry_stat.nr_dentry = get_nr_dentry(); |
136 | return proc_dointvec(table, write, buffer, lenp, ppos); |
137 | } |
138 | #endif |
139 | |
140 | /* |
141 | * Compare 2 name strings, return 0 if they match, otherwise non-zero. |
142 | * The strings are both count bytes long, and count is non-zero. |
143 | */ |
144 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
145 | |
146 | #include <asm/word-at-a-time.h> |
147 | /* |
148 | * NOTE! 'cs' and 'scount' come from a dentry, so it has a |
149 | * aligned allocation for this particular component. We don't |
150 | * strictly need the load_unaligned_zeropad() safety, but it |
151 | * doesn't hurt either. |
152 | * |
153 | * In contrast, 'ct' and 'tcount' can be from a pathname, and do |
154 | * need the careful unaligned handling. |
155 | */ |
156 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
157 | { |
158 | unsigned long a,b,mask; |
159 | |
160 | for (;;) { |
161 | a = *(unsigned long *)cs; |
162 | b = load_unaligned_zeropad(ct); |
163 | if (tcount < sizeof(unsigned long)) |
164 | break; |
165 | if (unlikely(a != b)) |
166 | return 1; |
167 | cs += sizeof(unsigned long); |
168 | ct += sizeof(unsigned long); |
169 | tcount -= sizeof(unsigned long); |
170 | if (!tcount) |
171 | return 0; |
172 | } |
173 | mask = ~(~0ul << tcount*8); |
174 | return unlikely(!!((a ^ b) & mask)); |
175 | } |
176 | |
177 | #else |
178 | |
179 | static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
180 | { |
181 | do { |
182 | if (*cs != *ct) |
183 | return 1; |
184 | cs++; |
185 | ct++; |
186 | tcount--; |
187 | } while (tcount); |
188 | return 0; |
189 | } |
190 | |
191 | #endif |
192 | |
193 | static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) |
194 | { |
195 | const unsigned char *cs; |
196 | /* |
197 | * Be careful about RCU walk racing with rename: |
198 | * use ACCESS_ONCE to fetch the name pointer. |
199 | * |
200 | * NOTE! Even if a rename will mean that the length |
201 | * was not loaded atomically, we don't care. The |
202 | * RCU walk will check the sequence count eventually, |
203 | * and catch it. And we won't overrun the buffer, |
204 | * because we're reading the name pointer atomically, |
205 | * and a dentry name is guaranteed to be properly |
206 | * terminated with a NUL byte. |
207 | * |
208 | * End result: even if 'len' is wrong, we'll exit |
209 | * early because the data cannot match (there can |
210 | * be no NUL in the ct/tcount data) |
211 | */ |
212 | cs = ACCESS_ONCE(dentry->d_name.name); |
213 | smp_read_barrier_depends(); |
214 | return dentry_string_cmp(cs, ct, tcount); |
215 | } |
216 | |
217 | static void __d_free(struct rcu_head *head) |
218 | { |
219 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
220 | |
221 | WARN_ON(!hlist_unhashed(&dentry->d_alias)); |
222 | if (dname_external(dentry)) |
223 | kfree(dentry->d_name.name); |
224 | kmem_cache_free(dentry_cache, dentry); |
225 | } |
226 | |
227 | /* |
228 | * no locks, please. |
229 | */ |
230 | static void d_free(struct dentry *dentry) |
231 | { |
232 | BUG_ON(dentry->d_count); |
233 | this_cpu_dec(nr_dentry); |
234 | if (dentry->d_op && dentry->d_op->d_release) |
235 | dentry->d_op->d_release(dentry); |
236 | |
237 | /* if dentry was never visible to RCU, immediate free is OK */ |
238 | if (!(dentry->d_flags & DCACHE_RCUACCESS)) |
239 | __d_free(&dentry->d_u.d_rcu); |
240 | else |
241 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
242 | } |
243 | |
244 | /** |
245 | * dentry_rcuwalk_barrier - invalidate in-progress rcu-walk lookups |
246 | * @dentry: the target dentry |
247 | * After this call, in-progress rcu-walk path lookup will fail. This |
248 | * should be called after unhashing, and after changing d_inode (if |
249 | * the dentry has not already been unhashed). |
250 | */ |
251 | static inline void dentry_rcuwalk_barrier(struct dentry *dentry) |
252 | { |
253 | assert_spin_locked(&dentry->d_lock); |
254 | /* Go through a barrier */ |
255 | write_seqcount_barrier(&dentry->d_seq); |
256 | } |
257 | |
258 | /* |
259 | * Release the dentry's inode, using the filesystem |
260 | * d_iput() operation if defined. Dentry has no refcount |
261 | * and is unhashed. |
262 | */ |
263 | static void dentry_iput(struct dentry * dentry) |
264 | __releases(dentry->d_lock) |
265 | __releases(dentry->d_inode->i_lock) |
266 | { |
267 | struct inode *inode = dentry->d_inode; |
268 | if (inode) { |
269 | dentry->d_inode = NULL; |
270 | hlist_del_init(&dentry->d_alias); |
271 | spin_unlock(&dentry->d_lock); |
272 | spin_unlock(&inode->i_lock); |
273 | if (!inode->i_nlink) |
274 | fsnotify_inoderemove(inode); |
275 | if (dentry->d_op && dentry->d_op->d_iput) |
276 | dentry->d_op->d_iput(dentry, inode); |
277 | else |
278 | iput(inode); |
279 | } else { |
280 | spin_unlock(&dentry->d_lock); |
281 | } |
282 | } |
283 | |
284 | /* |
285 | * Release the dentry's inode, using the filesystem |
286 | * d_iput() operation if defined. dentry remains in-use. |
287 | */ |
288 | static void dentry_unlink_inode(struct dentry * dentry) |
289 | __releases(dentry->d_lock) |
290 | __releases(dentry->d_inode->i_lock) |
291 | { |
292 | struct inode *inode = dentry->d_inode; |
293 | dentry->d_inode = NULL; |
294 | hlist_del_init(&dentry->d_alias); |
295 | dentry_rcuwalk_barrier(dentry); |
296 | spin_unlock(&dentry->d_lock); |
297 | spin_unlock(&inode->i_lock); |
298 | if (!inode->i_nlink) |
299 | fsnotify_inoderemove(inode); |
300 | if (dentry->d_op && dentry->d_op->d_iput) |
301 | dentry->d_op->d_iput(dentry, inode); |
302 | else |
303 | iput(inode); |
304 | } |
305 | |
306 | /* |
307 | * dentry_lru_(add|del|prune|move_tail) must be called with d_lock held. |
308 | */ |
309 | static void dentry_lru_add(struct dentry *dentry) |
310 | { |
311 | if (list_empty(&dentry->d_lru)) { |
312 | spin_lock(&dcache_lru_lock); |
313 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
314 | dentry->d_sb->s_nr_dentry_unused++; |
315 | dentry_stat.nr_unused++; |
316 | spin_unlock(&dcache_lru_lock); |
317 | } |
318 | } |
319 | |
320 | static void __dentry_lru_del(struct dentry *dentry) |
321 | { |
322 | list_del_init(&dentry->d_lru); |
323 | dentry->d_flags &= ~DCACHE_SHRINK_LIST; |
324 | dentry->d_sb->s_nr_dentry_unused--; |
325 | dentry_stat.nr_unused--; |
326 | } |
327 | |
328 | /* |
329 | * Remove a dentry with references from the LRU. |
330 | */ |
331 | static void dentry_lru_del(struct dentry *dentry) |
332 | { |
333 | if (!list_empty(&dentry->d_lru)) { |
334 | spin_lock(&dcache_lru_lock); |
335 | __dentry_lru_del(dentry); |
336 | spin_unlock(&dcache_lru_lock); |
337 | } |
338 | } |
339 | |
340 | /* |
341 | * Remove a dentry that is unreferenced and about to be pruned |
342 | * (unhashed and destroyed) from the LRU, and inform the file system. |
343 | * This wrapper should be called _prior_ to unhashing a victim dentry. |
344 | */ |
345 | static void dentry_lru_prune(struct dentry *dentry) |
346 | { |
347 | if (!list_empty(&dentry->d_lru)) { |
348 | if (dentry->d_flags & DCACHE_OP_PRUNE) |
349 | dentry->d_op->d_prune(dentry); |
350 | |
351 | spin_lock(&dcache_lru_lock); |
352 | __dentry_lru_del(dentry); |
353 | spin_unlock(&dcache_lru_lock); |
354 | } |
355 | } |
356 | |
357 | static void dentry_lru_move_list(struct dentry *dentry, struct list_head *list) |
358 | { |
359 | spin_lock(&dcache_lru_lock); |
360 | if (list_empty(&dentry->d_lru)) { |
361 | list_add_tail(&dentry->d_lru, list); |
362 | dentry->d_sb->s_nr_dentry_unused++; |
363 | dentry_stat.nr_unused++; |
364 | } else { |
365 | list_move_tail(&dentry->d_lru, list); |
366 | } |
367 | spin_unlock(&dcache_lru_lock); |
368 | } |
369 | |
370 | /** |
371 | * d_kill - kill dentry and return parent |
372 | * @dentry: dentry to kill |
373 | * @parent: parent dentry |
374 | * |
375 | * The dentry must already be unhashed and removed from the LRU. |
376 | * |
377 | * If this is the root of the dentry tree, return NULL. |
378 | * |
379 | * dentry->d_lock and parent->d_lock must be held by caller, and are dropped by |
380 | * d_kill. |
381 | */ |
382 | static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
383 | __releases(dentry->d_lock) |
384 | __releases(parent->d_lock) |
385 | __releases(dentry->d_inode->i_lock) |
386 | { |
387 | list_del(&dentry->d_u.d_child); |
388 | /* |
389 | * Inform try_to_ascend() that we are no longer attached to the |
390 | * dentry tree |
391 | */ |
392 | dentry->d_flags |= DCACHE_DENTRY_KILLED; |
393 | if (parent) |
394 | spin_unlock(&parent->d_lock); |
395 | dentry_iput(dentry); |
396 | /* |
397 | * dentry_iput drops the locks, at which point nobody (except |
398 | * transient RCU lookups) can reach this dentry. |
399 | */ |
400 | d_free(dentry); |
401 | return parent; |
402 | } |
403 | |
404 | /* |
405 | * Unhash a dentry without inserting an RCU walk barrier or checking that |
406 | * dentry->d_lock is locked. The caller must take care of that, if |
407 | * appropriate. |
408 | */ |
409 | static void __d_shrink(struct dentry *dentry) |
410 | { |
411 | if (!d_unhashed(dentry)) { |
412 | struct hlist_bl_head *b; |
413 | if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) |
414 | b = &dentry->d_sb->s_anon; |
415 | else |
416 | b = d_hash(dentry->d_parent, dentry->d_name.hash); |
417 | |
418 | hlist_bl_lock(b); |
419 | __hlist_bl_del(&dentry->d_hash); |
420 | dentry->d_hash.pprev = NULL; |
421 | hlist_bl_unlock(b); |
422 | } |
423 | } |
424 | |
425 | /** |
426 | * d_drop - drop a dentry |
427 | * @dentry: dentry to drop |
428 | * |
429 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't |
430 | * be found through a VFS lookup any more. Note that this is different from |
431 | * deleting the dentry - d_delete will try to mark the dentry negative if |
432 | * possible, giving a successful _negative_ lookup, while d_drop will |
433 | * just make the cache lookup fail. |
434 | * |
435 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some |
436 | * reason (NFS timeouts or autofs deletes). |
437 | * |
438 | * __d_drop requires dentry->d_lock. |
439 | */ |
440 | void __d_drop(struct dentry *dentry) |
441 | { |
442 | if (!d_unhashed(dentry)) { |
443 | __d_shrink(dentry); |
444 | dentry_rcuwalk_barrier(dentry); |
445 | } |
446 | } |
447 | EXPORT_SYMBOL(__d_drop); |
448 | |
449 | void d_drop(struct dentry *dentry) |
450 | { |
451 | spin_lock(&dentry->d_lock); |
452 | __d_drop(dentry); |
453 | spin_unlock(&dentry->d_lock); |
454 | } |
455 | EXPORT_SYMBOL(d_drop); |
456 | |
457 | /* |
458 | * Finish off a dentry we've decided to kill. |
459 | * dentry->d_lock must be held, returns with it unlocked. |
460 | * If ref is non-zero, then decrement the refcount too. |
461 | * Returns dentry requiring refcount drop, or NULL if we're done. |
462 | */ |
463 | static inline struct dentry *dentry_kill(struct dentry *dentry, int ref) |
464 | __releases(dentry->d_lock) |
465 | { |
466 | struct inode *inode; |
467 | struct dentry *parent; |
468 | |
469 | inode = dentry->d_inode; |
470 | if (inode && !spin_trylock(&inode->i_lock)) { |
471 | relock: |
472 | spin_unlock(&dentry->d_lock); |
473 | cpu_relax(); |
474 | return dentry; /* try again with same dentry */ |
475 | } |
476 | if (IS_ROOT(dentry)) |
477 | parent = NULL; |
478 | else |
479 | parent = dentry->d_parent; |
480 | if (parent && !spin_trylock(&parent->d_lock)) { |
481 | if (inode) |
482 | spin_unlock(&inode->i_lock); |
483 | goto relock; |
484 | } |
485 | |
486 | if (ref) |
487 | dentry->d_count--; |
488 | /* |
489 | * if dentry was on the d_lru list delete it from there. |
490 | * inform the fs via d_prune that this dentry is about to be |
491 | * unhashed and destroyed. |
492 | */ |
493 | dentry_lru_prune(dentry); |
494 | /* if it was on the hash then remove it */ |
495 | __d_drop(dentry); |
496 | return d_kill(dentry, parent); |
497 | } |
498 | |
499 | /* |
500 | * This is dput |
501 | * |
502 | * This is complicated by the fact that we do not want to put |
503 | * dentries that are no longer on any hash chain on the unused |
504 | * list: we'd much rather just get rid of them immediately. |
505 | * |
506 | * However, that implies that we have to traverse the dentry |
507 | * tree upwards to the parents which might _also_ now be |
508 | * scheduled for deletion (it may have been only waiting for |
509 | * its last child to go away). |
510 | * |
511 | * This tail recursion is done by hand as we don't want to depend |
512 | * on the compiler to always get this right (gcc generally doesn't). |
513 | * Real recursion would eat up our stack space. |
514 | */ |
515 | |
516 | /* |
517 | * dput - release a dentry |
518 | * @dentry: dentry to release |
519 | * |
520 | * Release a dentry. This will drop the usage count and if appropriate |
521 | * call the dentry unlink method as well as removing it from the queues and |
522 | * releasing its resources. If the parent dentries were scheduled for release |
523 | * they too may now get deleted. |
524 | */ |
525 | void dput(struct dentry *dentry) |
526 | { |
527 | if (!dentry) |
528 | return; |
529 | |
530 | repeat: |
531 | if (dentry->d_count == 1) |
532 | might_sleep(); |
533 | spin_lock(&dentry->d_lock); |
534 | BUG_ON(!dentry->d_count); |
535 | if (dentry->d_count > 1) { |
536 | dentry->d_count--; |
537 | spin_unlock(&dentry->d_lock); |
538 | return; |
539 | } |
540 | |
541 | if (dentry->d_flags & DCACHE_OP_DELETE) { |
542 | if (dentry->d_op->d_delete(dentry)) |
543 | goto kill_it; |
544 | } |
545 | |
546 | /* Unreachable? Get rid of it */ |
547 | if (d_unhashed(dentry)) |
548 | goto kill_it; |
549 | |
550 | dentry->d_flags |= DCACHE_REFERENCED; |
551 | dentry_lru_add(dentry); |
552 | |
553 | dentry->d_count--; |
554 | spin_unlock(&dentry->d_lock); |
555 | return; |
556 | |
557 | kill_it: |
558 | dentry = dentry_kill(dentry, 1); |
559 | if (dentry) |
560 | goto repeat; |
561 | } |
562 | EXPORT_SYMBOL(dput); |
563 | |
564 | /** |
565 | * d_invalidate - invalidate a dentry |
566 | * @dentry: dentry to invalidate |
567 | * |
568 | * Try to invalidate the dentry if it turns out to be |
569 | * possible. If there are other dentries that can be |
570 | * reached through this one we can't delete it and we |
571 | * return -EBUSY. On success we return 0. |
572 | * |
573 | * no dcache lock. |
574 | */ |
575 | |
576 | int d_invalidate(struct dentry * dentry) |
577 | { |
578 | /* |
579 | * If it's already been dropped, return OK. |
580 | */ |
581 | spin_lock(&dentry->d_lock); |
582 | if (d_unhashed(dentry)) { |
583 | spin_unlock(&dentry->d_lock); |
584 | return 0; |
585 | } |
586 | /* |
587 | * Check whether to do a partial shrink_dcache |
588 | * to get rid of unused child entries. |
589 | */ |
590 | if (!list_empty(&dentry->d_subdirs)) { |
591 | spin_unlock(&dentry->d_lock); |
592 | shrink_dcache_parent(dentry); |
593 | spin_lock(&dentry->d_lock); |
594 | } |
595 | |
596 | /* |
597 | * Somebody else still using it? |
598 | * |
599 | * If it's a directory, we can't drop it |
600 | * for fear of somebody re-populating it |
601 | * with children (even though dropping it |
602 | * would make it unreachable from the root, |
603 | * we might still populate it if it was a |
604 | * working directory or similar). |
605 | * We also need to leave mountpoints alone, |
606 | * directory or not. |
607 | */ |
608 | if (dentry->d_count > 1 && dentry->d_inode) { |
609 | if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) { |
610 | spin_unlock(&dentry->d_lock); |
611 | return -EBUSY; |
612 | } |
613 | } |
614 | |
615 | __d_drop(dentry); |
616 | spin_unlock(&dentry->d_lock); |
617 | return 0; |
618 | } |
619 | EXPORT_SYMBOL(d_invalidate); |
620 | |
621 | /* This must be called with d_lock held */ |
622 | static inline void __dget_dlock(struct dentry *dentry) |
623 | { |
624 | dentry->d_count++; |
625 | } |
626 | |
627 | static inline void __dget(struct dentry *dentry) |
628 | { |
629 | spin_lock(&dentry->d_lock); |
630 | __dget_dlock(dentry); |
631 | spin_unlock(&dentry->d_lock); |
632 | } |
633 | |
634 | struct dentry *dget_parent(struct dentry *dentry) |
635 | { |
636 | struct dentry *ret; |
637 | |
638 | repeat: |
639 | /* |
640 | * Don't need rcu_dereference because we re-check it was correct under |
641 | * the lock. |
642 | */ |
643 | rcu_read_lock(); |
644 | ret = dentry->d_parent; |
645 | spin_lock(&ret->d_lock); |
646 | if (unlikely(ret != dentry->d_parent)) { |
647 | spin_unlock(&ret->d_lock); |
648 | rcu_read_unlock(); |
649 | goto repeat; |
650 | } |
651 | rcu_read_unlock(); |
652 | BUG_ON(!ret->d_count); |
653 | ret->d_count++; |
654 | spin_unlock(&ret->d_lock); |
655 | return ret; |
656 | } |
657 | EXPORT_SYMBOL(dget_parent); |
658 | |
659 | /** |
660 | * d_find_alias - grab a hashed alias of inode |
661 | * @inode: inode in question |
662 | * @want_discon: flag, used by d_splice_alias, to request |
663 | * that only a DISCONNECTED alias be returned. |
664 | * |
665 | * If inode has a hashed alias, or is a directory and has any alias, |
666 | * acquire the reference to alias and return it. Otherwise return NULL. |
667 | * Notice that if inode is a directory there can be only one alias and |
668 | * it can be unhashed only if it has no children, or if it is the root |
669 | * of a filesystem. |
670 | * |
671 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
672 | * any other hashed alias over that one unless @want_discon is set, |
673 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
674 | */ |
675 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
676 | { |
677 | struct dentry *alias, *discon_alias; |
678 | |
679 | again: |
680 | discon_alias = NULL; |
681 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
682 | spin_lock(&alias->d_lock); |
683 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
684 | if (IS_ROOT(alias) && |
685 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
686 | discon_alias = alias; |
687 | } else if (!want_discon) { |
688 | __dget_dlock(alias); |
689 | spin_unlock(&alias->d_lock); |
690 | return alias; |
691 | } |
692 | } |
693 | spin_unlock(&alias->d_lock); |
694 | } |
695 | if (discon_alias) { |
696 | alias = discon_alias; |
697 | spin_lock(&alias->d_lock); |
698 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
699 | if (IS_ROOT(alias) && |
700 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
701 | __dget_dlock(alias); |
702 | spin_unlock(&alias->d_lock); |
703 | return alias; |
704 | } |
705 | } |
706 | spin_unlock(&alias->d_lock); |
707 | goto again; |
708 | } |
709 | return NULL; |
710 | } |
711 | |
712 | struct dentry *d_find_alias(struct inode *inode) |
713 | { |
714 | struct dentry *de = NULL; |
715 | |
716 | if (!hlist_empty(&inode->i_dentry)) { |
717 | spin_lock(&inode->i_lock); |
718 | de = __d_find_alias(inode, 0); |
719 | spin_unlock(&inode->i_lock); |
720 | } |
721 | return de; |
722 | } |
723 | EXPORT_SYMBOL(d_find_alias); |
724 | |
725 | /* |
726 | * Try to kill dentries associated with this inode. |
727 | * WARNING: you must own a reference to inode. |
728 | */ |
729 | void d_prune_aliases(struct inode *inode) |
730 | { |
731 | struct dentry *dentry; |
732 | restart: |
733 | spin_lock(&inode->i_lock); |
734 | hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
735 | spin_lock(&dentry->d_lock); |
736 | if (!dentry->d_count) { |
737 | __dget_dlock(dentry); |
738 | __d_drop(dentry); |
739 | spin_unlock(&dentry->d_lock); |
740 | spin_unlock(&inode->i_lock); |
741 | dput(dentry); |
742 | goto restart; |
743 | } |
744 | spin_unlock(&dentry->d_lock); |
745 | } |
746 | spin_unlock(&inode->i_lock); |
747 | } |
748 | EXPORT_SYMBOL(d_prune_aliases); |
749 | |
750 | /* |
751 | * Try to throw away a dentry - free the inode, dput the parent. |
752 | * Requires dentry->d_lock is held, and dentry->d_count == 0. |
753 | * Releases dentry->d_lock. |
754 | * |
755 | * This may fail if locks cannot be acquired no problem, just try again. |
756 | */ |
757 | static void try_prune_one_dentry(struct dentry *dentry) |
758 | __releases(dentry->d_lock) |
759 | { |
760 | struct dentry *parent; |
761 | |
762 | parent = dentry_kill(dentry, 0); |
763 | /* |
764 | * If dentry_kill returns NULL, we have nothing more to do. |
765 | * if it returns the same dentry, trylocks failed. In either |
766 | * case, just loop again. |
767 | * |
768 | * Otherwise, we need to prune ancestors too. This is necessary |
769 | * to prevent quadratic behavior of shrink_dcache_parent(), but |
770 | * is also expected to be beneficial in reducing dentry cache |
771 | * fragmentation. |
772 | */ |
773 | if (!parent) |
774 | return; |
775 | if (parent == dentry) |
776 | return; |
777 | |
778 | /* Prune ancestors. */ |
779 | dentry = parent; |
780 | while (dentry) { |
781 | spin_lock(&dentry->d_lock); |
782 | if (dentry->d_count > 1) { |
783 | dentry->d_count--; |
784 | spin_unlock(&dentry->d_lock); |
785 | return; |
786 | } |
787 | dentry = dentry_kill(dentry, 1); |
788 | } |
789 | } |
790 | |
791 | static void shrink_dentry_list(struct list_head *list) |
792 | { |
793 | struct dentry *dentry; |
794 | |
795 | rcu_read_lock(); |
796 | for (;;) { |
797 | dentry = list_entry_rcu(list->prev, struct dentry, d_lru); |
798 | if (&dentry->d_lru == list) |
799 | break; /* empty */ |
800 | spin_lock(&dentry->d_lock); |
801 | if (dentry != list_entry(list->prev, struct dentry, d_lru)) { |
802 | spin_unlock(&dentry->d_lock); |
803 | continue; |
804 | } |
805 | |
806 | /* |
807 | * We found an inuse dentry which was not removed from |
808 | * the LRU because of laziness during lookup. Do not free |
809 | * it - just keep it off the LRU list. |
810 | */ |
811 | if (dentry->d_count) { |
812 | dentry_lru_del(dentry); |
813 | spin_unlock(&dentry->d_lock); |
814 | continue; |
815 | } |
816 | |
817 | rcu_read_unlock(); |
818 | |
819 | try_prune_one_dentry(dentry); |
820 | |
821 | rcu_read_lock(); |
822 | } |
823 | rcu_read_unlock(); |
824 | } |
825 | |
826 | /** |
827 | * prune_dcache_sb - shrink the dcache |
828 | * @sb: superblock |
829 | * @count: number of entries to try to free |
830 | * |
831 | * Attempt to shrink the superblock dcache LRU by @count entries. This is |
832 | * done when we need more memory an called from the superblock shrinker |
833 | * function. |
834 | * |
835 | * This function may fail to free any resources if all the dentries are in |
836 | * use. |
837 | */ |
838 | void prune_dcache_sb(struct super_block *sb, int count) |
839 | { |
840 | struct dentry *dentry; |
841 | LIST_HEAD(referenced); |
842 | LIST_HEAD(tmp); |
843 | |
844 | relock: |
845 | spin_lock(&dcache_lru_lock); |
846 | while (!list_empty(&sb->s_dentry_lru)) { |
847 | dentry = list_entry(sb->s_dentry_lru.prev, |
848 | struct dentry, d_lru); |
849 | BUG_ON(dentry->d_sb != sb); |
850 | |
851 | if (!spin_trylock(&dentry->d_lock)) { |
852 | spin_unlock(&dcache_lru_lock); |
853 | cpu_relax(); |
854 | goto relock; |
855 | } |
856 | |
857 | if (dentry->d_flags & DCACHE_REFERENCED) { |
858 | dentry->d_flags &= ~DCACHE_REFERENCED; |
859 | list_move(&dentry->d_lru, &referenced); |
860 | spin_unlock(&dentry->d_lock); |
861 | } else { |
862 | list_move_tail(&dentry->d_lru, &tmp); |
863 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
864 | spin_unlock(&dentry->d_lock); |
865 | if (!--count) |
866 | break; |
867 | } |
868 | cond_resched_lock(&dcache_lru_lock); |
869 | } |
870 | if (!list_empty(&referenced)) |
871 | list_splice(&referenced, &sb->s_dentry_lru); |
872 | spin_unlock(&dcache_lru_lock); |
873 | |
874 | shrink_dentry_list(&tmp); |
875 | } |
876 | |
877 | /** |
878 | * shrink_dcache_sb - shrink dcache for a superblock |
879 | * @sb: superblock |
880 | * |
881 | * Shrink the dcache for the specified super block. This is used to free |
882 | * the dcache before unmounting a file system. |
883 | */ |
884 | void shrink_dcache_sb(struct super_block *sb) |
885 | { |
886 | LIST_HEAD(tmp); |
887 | |
888 | spin_lock(&dcache_lru_lock); |
889 | while (!list_empty(&sb->s_dentry_lru)) { |
890 | list_splice_init(&sb->s_dentry_lru, &tmp); |
891 | spin_unlock(&dcache_lru_lock); |
892 | shrink_dentry_list(&tmp); |
893 | spin_lock(&dcache_lru_lock); |
894 | } |
895 | spin_unlock(&dcache_lru_lock); |
896 | } |
897 | EXPORT_SYMBOL(shrink_dcache_sb); |
898 | |
899 | /* |
900 | * destroy a single subtree of dentries for unmount |
901 | * - see the comments on shrink_dcache_for_umount() for a description of the |
902 | * locking |
903 | */ |
904 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) |
905 | { |
906 | struct dentry *parent; |
907 | |
908 | BUG_ON(!IS_ROOT(dentry)); |
909 | |
910 | for (;;) { |
911 | /* descend to the first leaf in the current subtree */ |
912 | while (!list_empty(&dentry->d_subdirs)) |
913 | dentry = list_entry(dentry->d_subdirs.next, |
914 | struct dentry, d_u.d_child); |
915 | |
916 | /* consume the dentries from this leaf up through its parents |
917 | * until we find one with children or run out altogether */ |
918 | do { |
919 | struct inode *inode; |
920 | |
921 | /* |
922 | * remove the dentry from the lru, and inform |
923 | * the fs that this dentry is about to be |
924 | * unhashed and destroyed. |
925 | */ |
926 | dentry_lru_prune(dentry); |
927 | __d_shrink(dentry); |
928 | |
929 | if (dentry->d_count != 0) { |
930 | printk(KERN_ERR |
931 | "BUG: Dentry %p{i=%lx,n=%s}" |
932 | " still in use (%d)" |
933 | " [unmount of %s %s]\n", |
934 | dentry, |
935 | dentry->d_inode ? |
936 | dentry->d_inode->i_ino : 0UL, |
937 | dentry->d_name.name, |
938 | dentry->d_count, |
939 | dentry->d_sb->s_type->name, |
940 | dentry->d_sb->s_id); |
941 | BUG(); |
942 | } |
943 | |
944 | if (IS_ROOT(dentry)) { |
945 | parent = NULL; |
946 | list_del(&dentry->d_u.d_child); |
947 | } else { |
948 | parent = dentry->d_parent; |
949 | parent->d_count--; |
950 | list_del(&dentry->d_u.d_child); |
951 | } |
952 | |
953 | inode = dentry->d_inode; |
954 | if (inode) { |
955 | dentry->d_inode = NULL; |
956 | hlist_del_init(&dentry->d_alias); |
957 | if (dentry->d_op && dentry->d_op->d_iput) |
958 | dentry->d_op->d_iput(dentry, inode); |
959 | else |
960 | iput(inode); |
961 | } |
962 | |
963 | d_free(dentry); |
964 | |
965 | /* finished when we fall off the top of the tree, |
966 | * otherwise we ascend to the parent and move to the |
967 | * next sibling if there is one */ |
968 | if (!parent) |
969 | return; |
970 | dentry = parent; |
971 | } while (list_empty(&dentry->d_subdirs)); |
972 | |
973 | dentry = list_entry(dentry->d_subdirs.next, |
974 | struct dentry, d_u.d_child); |
975 | } |
976 | } |
977 | |
978 | /* |
979 | * destroy the dentries attached to a superblock on unmounting |
980 | * - we don't need to use dentry->d_lock because: |
981 | * - the superblock is detached from all mountings and open files, so the |
982 | * dentry trees will not be rearranged by the VFS |
983 | * - s_umount is write-locked, so the memory pressure shrinker will ignore |
984 | * any dentries belonging to this superblock that it comes across |
985 | * - the filesystem itself is no longer permitted to rearrange the dentries |
986 | * in this superblock |
987 | */ |
988 | void shrink_dcache_for_umount(struct super_block *sb) |
989 | { |
990 | struct dentry *dentry; |
991 | |
992 | if (down_read_trylock(&sb->s_umount)) |
993 | BUG(); |
994 | |
995 | dentry = sb->s_root; |
996 | sb->s_root = NULL; |
997 | dentry->d_count--; |
998 | shrink_dcache_for_umount_subtree(dentry); |
999 | |
1000 | while (!hlist_bl_empty(&sb->s_anon)) { |
1001 | dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); |
1002 | shrink_dcache_for_umount_subtree(dentry); |
1003 | } |
1004 | } |
1005 | |
1006 | /* |
1007 | * This tries to ascend one level of parenthood, but |
1008 | * we can race with renaming, so we need to re-check |
1009 | * the parenthood after dropping the lock and check |
1010 | * that the sequence number still matches. |
1011 | */ |
1012 | static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq) |
1013 | { |
1014 | struct dentry *new = old->d_parent; |
1015 | |
1016 | rcu_read_lock(); |
1017 | spin_unlock(&old->d_lock); |
1018 | spin_lock(&new->d_lock); |
1019 | |
1020 | /* |
1021 | * might go back up the wrong parent if we have had a rename |
1022 | * or deletion |
1023 | */ |
1024 | if (new != old->d_parent || |
1025 | (old->d_flags & DCACHE_DENTRY_KILLED) || |
1026 | (!locked && read_seqretry(&rename_lock, seq))) { |
1027 | spin_unlock(&new->d_lock); |
1028 | new = NULL; |
1029 | } |
1030 | rcu_read_unlock(); |
1031 | return new; |
1032 | } |
1033 | |
1034 | |
1035 | /* |
1036 | * Search for at least 1 mount point in the dentry's subdirs. |
1037 | * We descend to the next level whenever the d_subdirs |
1038 | * list is non-empty and continue searching. |
1039 | */ |
1040 | |
1041 | /** |
1042 | * have_submounts - check for mounts over a dentry |
1043 | * @parent: dentry to check. |
1044 | * |
1045 | * Return true if the parent or its subdirectories contain |
1046 | * a mount point |
1047 | */ |
1048 | int have_submounts(struct dentry *parent) |
1049 | { |
1050 | struct dentry *this_parent; |
1051 | struct list_head *next; |
1052 | unsigned seq; |
1053 | int locked = 0; |
1054 | |
1055 | seq = read_seqbegin(&rename_lock); |
1056 | again: |
1057 | this_parent = parent; |
1058 | |
1059 | if (d_mountpoint(parent)) |
1060 | goto positive; |
1061 | spin_lock(&this_parent->d_lock); |
1062 | repeat: |
1063 | next = this_parent->d_subdirs.next; |
1064 | resume: |
1065 | while (next != &this_parent->d_subdirs) { |
1066 | struct list_head *tmp = next; |
1067 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1068 | next = tmp->next; |
1069 | |
1070 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1071 | /* Have we found a mount point ? */ |
1072 | if (d_mountpoint(dentry)) { |
1073 | spin_unlock(&dentry->d_lock); |
1074 | spin_unlock(&this_parent->d_lock); |
1075 | goto positive; |
1076 | } |
1077 | if (!list_empty(&dentry->d_subdirs)) { |
1078 | spin_unlock(&this_parent->d_lock); |
1079 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
1080 | this_parent = dentry; |
1081 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1082 | goto repeat; |
1083 | } |
1084 | spin_unlock(&dentry->d_lock); |
1085 | } |
1086 | /* |
1087 | * All done at this level ... ascend and resume the search. |
1088 | */ |
1089 | if (this_parent != parent) { |
1090 | struct dentry *child = this_parent; |
1091 | this_parent = try_to_ascend(this_parent, locked, seq); |
1092 | if (!this_parent) |
1093 | goto rename_retry; |
1094 | next = child->d_u.d_child.next; |
1095 | goto resume; |
1096 | } |
1097 | spin_unlock(&this_parent->d_lock); |
1098 | if (!locked && read_seqretry(&rename_lock, seq)) |
1099 | goto rename_retry; |
1100 | if (locked) |
1101 | write_sequnlock(&rename_lock); |
1102 | return 0; /* No mount points found in tree */ |
1103 | positive: |
1104 | if (!locked && read_seqretry(&rename_lock, seq)) |
1105 | goto rename_retry; |
1106 | if (locked) |
1107 | write_sequnlock(&rename_lock); |
1108 | return 1; |
1109 | |
1110 | rename_retry: |
1111 | if (locked) |
1112 | goto again; |
1113 | locked = 1; |
1114 | write_seqlock(&rename_lock); |
1115 | goto again; |
1116 | } |
1117 | EXPORT_SYMBOL(have_submounts); |
1118 | |
1119 | /* |
1120 | * Search the dentry child list of the specified parent, |
1121 | * and move any unused dentries to the end of the unused |
1122 | * list for prune_dcache(). We descend to the next level |
1123 | * whenever the d_subdirs list is non-empty and continue |
1124 | * searching. |
1125 | * |
1126 | * It returns zero iff there are no unused children, |
1127 | * otherwise it returns the number of children moved to |
1128 | * the end of the unused list. This may not be the total |
1129 | * number of unused children, because select_parent can |
1130 | * drop the lock and return early due to latency |
1131 | * constraints. |
1132 | */ |
1133 | static int select_parent(struct dentry *parent, struct list_head *dispose) |
1134 | { |
1135 | struct dentry *this_parent; |
1136 | struct list_head *next; |
1137 | unsigned seq; |
1138 | int found = 0; |
1139 | int locked = 0; |
1140 | |
1141 | seq = read_seqbegin(&rename_lock); |
1142 | again: |
1143 | this_parent = parent; |
1144 | spin_lock(&this_parent->d_lock); |
1145 | repeat: |
1146 | next = this_parent->d_subdirs.next; |
1147 | resume: |
1148 | while (next != &this_parent->d_subdirs) { |
1149 | struct list_head *tmp = next; |
1150 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1151 | next = tmp->next; |
1152 | |
1153 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1154 | |
1155 | /* |
1156 | * move only zero ref count dentries to the dispose list. |
1157 | * |
1158 | * Those which are presently on the shrink list, being processed |
1159 | * by shrink_dentry_list(), shouldn't be moved. Otherwise the |
1160 | * loop in shrink_dcache_parent() might not make any progress |
1161 | * and loop forever. |
1162 | */ |
1163 | if (dentry->d_count) { |
1164 | dentry_lru_del(dentry); |
1165 | } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { |
1166 | dentry_lru_move_list(dentry, dispose); |
1167 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
1168 | found++; |
1169 | } |
1170 | /* |
1171 | * We can return to the caller if we have found some (this |
1172 | * ensures forward progress). We'll be coming back to find |
1173 | * the rest. |
1174 | */ |
1175 | if (found && need_resched()) { |
1176 | spin_unlock(&dentry->d_lock); |
1177 | goto out; |
1178 | } |
1179 | |
1180 | /* |
1181 | * Descend a level if the d_subdirs list is non-empty. |
1182 | */ |
1183 | if (!list_empty(&dentry->d_subdirs)) { |
1184 | spin_unlock(&this_parent->d_lock); |
1185 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
1186 | this_parent = dentry; |
1187 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1188 | goto repeat; |
1189 | } |
1190 | |
1191 | spin_unlock(&dentry->d_lock); |
1192 | } |
1193 | /* |
1194 | * All done at this level ... ascend and resume the search. |
1195 | */ |
1196 | if (this_parent != parent) { |
1197 | struct dentry *child = this_parent; |
1198 | this_parent = try_to_ascend(this_parent, locked, seq); |
1199 | if (!this_parent) |
1200 | goto rename_retry; |
1201 | next = child->d_u.d_child.next; |
1202 | goto resume; |
1203 | } |
1204 | out: |
1205 | spin_unlock(&this_parent->d_lock); |
1206 | if (!locked && read_seqretry(&rename_lock, seq)) |
1207 | goto rename_retry; |
1208 | if (locked) |
1209 | write_sequnlock(&rename_lock); |
1210 | return found; |
1211 | |
1212 | rename_retry: |
1213 | if (found) |
1214 | return found; |
1215 | if (locked) |
1216 | goto again; |
1217 | locked = 1; |
1218 | write_seqlock(&rename_lock); |
1219 | goto again; |
1220 | } |
1221 | |
1222 | /** |
1223 | * shrink_dcache_parent - prune dcache |
1224 | * @parent: parent of entries to prune |
1225 | * |
1226 | * Prune the dcache to remove unused children of the parent dentry. |
1227 | */ |
1228 | void shrink_dcache_parent(struct dentry * parent) |
1229 | { |
1230 | LIST_HEAD(dispose); |
1231 | int found; |
1232 | |
1233 | while ((found = select_parent(parent, &dispose)) != 0) |
1234 | shrink_dentry_list(&dispose); |
1235 | } |
1236 | EXPORT_SYMBOL(shrink_dcache_parent); |
1237 | |
1238 | /** |
1239 | * __d_alloc - allocate a dcache entry |
1240 | * @sb: filesystem it will belong to |
1241 | * @name: qstr of the name |
1242 | * |
1243 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
1244 | * available. On a success the dentry is returned. The name passed in is |
1245 | * copied and the copy passed in may be reused after this call. |
1246 | */ |
1247 | |
1248 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1249 | { |
1250 | struct dentry *dentry; |
1251 | char *dname; |
1252 | |
1253 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1254 | if (!dentry) |
1255 | return NULL; |
1256 | |
1257 | /* |
1258 | * We guarantee that the inline name is always NUL-terminated. |
1259 | * This way the memcpy() done by the name switching in rename |
1260 | * will still always have a NUL at the end, even if we might |
1261 | * be overwriting an internal NUL character |
1262 | */ |
1263 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; |
1264 | if (name->len > DNAME_INLINE_LEN-1) { |
1265 | dname = kmalloc(name->len + 1, GFP_KERNEL); |
1266 | if (!dname) { |
1267 | kmem_cache_free(dentry_cache, dentry); |
1268 | return NULL; |
1269 | } |
1270 | } else { |
1271 | dname = dentry->d_iname; |
1272 | } |
1273 | |
1274 | dentry->d_name.len = name->len; |
1275 | dentry->d_name.hash = name->hash; |
1276 | memcpy(dname, name->name, name->len); |
1277 | dname[name->len] = 0; |
1278 | |
1279 | /* Make sure we always see the terminating NUL character */ |
1280 | smp_wmb(); |
1281 | dentry->d_name.name = dname; |
1282 | |
1283 | dentry->d_count = 1; |
1284 | dentry->d_flags = 0; |
1285 | spin_lock_init(&dentry->d_lock); |
1286 | seqcount_init(&dentry->d_seq); |
1287 | dentry->d_inode = NULL; |
1288 | dentry->d_parent = dentry; |
1289 | dentry->d_sb = sb; |
1290 | dentry->d_op = NULL; |
1291 | dentry->d_fsdata = NULL; |
1292 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1293 | INIT_LIST_HEAD(&dentry->d_lru); |
1294 | INIT_LIST_HEAD(&dentry->d_subdirs); |
1295 | INIT_HLIST_NODE(&dentry->d_alias); |
1296 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1297 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1298 | |
1299 | this_cpu_inc(nr_dentry); |
1300 | |
1301 | return dentry; |
1302 | } |
1303 | |
1304 | /** |
1305 | * d_alloc - allocate a dcache entry |
1306 | * @parent: parent of entry to allocate |
1307 | * @name: qstr of the name |
1308 | * |
1309 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
1310 | * available. On a success the dentry is returned. The name passed in is |
1311 | * copied and the copy passed in may be reused after this call. |
1312 | */ |
1313 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
1314 | { |
1315 | struct dentry *dentry = __d_alloc(parent->d_sb, name); |
1316 | if (!dentry) |
1317 | return NULL; |
1318 | |
1319 | spin_lock(&parent->d_lock); |
1320 | /* |
1321 | * don't need child lock because it is not subject |
1322 | * to concurrency here |
1323 | */ |
1324 | __dget_dlock(parent); |
1325 | dentry->d_parent = parent; |
1326 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1327 | spin_unlock(&parent->d_lock); |
1328 | |
1329 | return dentry; |
1330 | } |
1331 | EXPORT_SYMBOL(d_alloc); |
1332 | |
1333 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1334 | { |
1335 | struct dentry *dentry = __d_alloc(sb, name); |
1336 | if (dentry) |
1337 | dentry->d_flags |= DCACHE_DISCONNECTED; |
1338 | return dentry; |
1339 | } |
1340 | EXPORT_SYMBOL(d_alloc_pseudo); |
1341 | |
1342 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1343 | { |
1344 | struct qstr q; |
1345 | |
1346 | q.name = name; |
1347 | q.len = strlen(name); |
1348 | q.hash = full_name_hash(q.name, q.len); |
1349 | return d_alloc(parent, &q); |
1350 | } |
1351 | EXPORT_SYMBOL(d_alloc_name); |
1352 | |
1353 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1354 | { |
1355 | WARN_ON_ONCE(dentry->d_op); |
1356 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
1357 | DCACHE_OP_COMPARE | |
1358 | DCACHE_OP_REVALIDATE | |
1359 | DCACHE_OP_WEAK_REVALIDATE | |
1360 | DCACHE_OP_DELETE )); |
1361 | dentry->d_op = op; |
1362 | if (!op) |
1363 | return; |
1364 | if (op->d_hash) |
1365 | dentry->d_flags |= DCACHE_OP_HASH; |
1366 | if (op->d_compare) |
1367 | dentry->d_flags |= DCACHE_OP_COMPARE; |
1368 | if (op->d_revalidate) |
1369 | dentry->d_flags |= DCACHE_OP_REVALIDATE; |
1370 | if (op->d_weak_revalidate) |
1371 | dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; |
1372 | if (op->d_delete) |
1373 | dentry->d_flags |= DCACHE_OP_DELETE; |
1374 | if (op->d_prune) |
1375 | dentry->d_flags |= DCACHE_OP_PRUNE; |
1376 | |
1377 | } |
1378 | EXPORT_SYMBOL(d_set_d_op); |
1379 | |
1380 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1381 | { |
1382 | spin_lock(&dentry->d_lock); |
1383 | if (inode) { |
1384 | if (unlikely(IS_AUTOMOUNT(inode))) |
1385 | dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; |
1386 | hlist_add_head(&dentry->d_alias, &inode->i_dentry); |
1387 | } |
1388 | dentry->d_inode = inode; |
1389 | dentry_rcuwalk_barrier(dentry); |
1390 | spin_unlock(&dentry->d_lock); |
1391 | fsnotify_d_instantiate(dentry, inode); |
1392 | } |
1393 | |
1394 | /** |
1395 | * d_instantiate - fill in inode information for a dentry |
1396 | * @entry: dentry to complete |
1397 | * @inode: inode to attach to this dentry |
1398 | * |
1399 | * Fill in inode information in the entry. |
1400 | * |
1401 | * This turns negative dentries into productive full members |
1402 | * of society. |
1403 | * |
1404 | * NOTE! This assumes that the inode count has been incremented |
1405 | * (or otherwise set) by the caller to indicate that it is now |
1406 | * in use by the dcache. |
1407 | */ |
1408 | |
1409 | void d_instantiate(struct dentry *entry, struct inode * inode) |
1410 | { |
1411 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
1412 | if (inode) |
1413 | spin_lock(&inode->i_lock); |
1414 | __d_instantiate(entry, inode); |
1415 | if (inode) |
1416 | spin_unlock(&inode->i_lock); |
1417 | security_d_instantiate(entry, inode); |
1418 | } |
1419 | EXPORT_SYMBOL(d_instantiate); |
1420 | |
1421 | /** |
1422 | * d_instantiate_unique - instantiate a non-aliased dentry |
1423 | * @entry: dentry to instantiate |
1424 | * @inode: inode to attach to this dentry |
1425 | * |
1426 | * Fill in inode information in the entry. On success, it returns NULL. |
1427 | * If an unhashed alias of "entry" already exists, then we return the |
1428 | * aliased dentry instead and drop one reference to inode. |
1429 | * |
1430 | * Note that in order to avoid conflicts with rename() etc, the caller |
1431 | * had better be holding the parent directory semaphore. |
1432 | * |
1433 | * This also assumes that the inode count has been incremented |
1434 | * (or otherwise set) by the caller to indicate that it is now |
1435 | * in use by the dcache. |
1436 | */ |
1437 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1438 | struct inode *inode) |
1439 | { |
1440 | struct dentry *alias; |
1441 | int len = entry->d_name.len; |
1442 | const char *name = entry->d_name.name; |
1443 | unsigned int hash = entry->d_name.hash; |
1444 | |
1445 | if (!inode) { |
1446 | __d_instantiate(entry, NULL); |
1447 | return NULL; |
1448 | } |
1449 | |
1450 | hlist_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1451 | /* |
1452 | * Don't need alias->d_lock here, because aliases with |
1453 | * d_parent == entry->d_parent are not subject to name or |
1454 | * parent changes, because the parent inode i_mutex is held. |
1455 | */ |
1456 | if (alias->d_name.hash != hash) |
1457 | continue; |
1458 | if (alias->d_parent != entry->d_parent) |
1459 | continue; |
1460 | if (alias->d_name.len != len) |
1461 | continue; |
1462 | if (dentry_cmp(alias, name, len)) |
1463 | continue; |
1464 | __dget(alias); |
1465 | return alias; |
1466 | } |
1467 | |
1468 | __d_instantiate(entry, inode); |
1469 | return NULL; |
1470 | } |
1471 | |
1472 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
1473 | { |
1474 | struct dentry *result; |
1475 | |
1476 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
1477 | |
1478 | if (inode) |
1479 | spin_lock(&inode->i_lock); |
1480 | result = __d_instantiate_unique(entry, inode); |
1481 | if (inode) |
1482 | spin_unlock(&inode->i_lock); |
1483 | |
1484 | if (!result) { |
1485 | security_d_instantiate(entry, inode); |
1486 | return NULL; |
1487 | } |
1488 | |
1489 | BUG_ON(!d_unhashed(result)); |
1490 | iput(inode); |
1491 | return result; |
1492 | } |
1493 | |
1494 | EXPORT_SYMBOL(d_instantiate_unique); |
1495 | |
1496 | struct dentry *d_make_root(struct inode *root_inode) |
1497 | { |
1498 | struct dentry *res = NULL; |
1499 | |
1500 | if (root_inode) { |
1501 | static const struct qstr name = QSTR_INIT("/", 1); |
1502 | |
1503 | res = __d_alloc(root_inode->i_sb, &name); |
1504 | if (res) |
1505 | d_instantiate(res, root_inode); |
1506 | else |
1507 | iput(root_inode); |
1508 | } |
1509 | return res; |
1510 | } |
1511 | EXPORT_SYMBOL(d_make_root); |
1512 | |
1513 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1514 | { |
1515 | struct dentry *alias; |
1516 | |
1517 | if (hlist_empty(&inode->i_dentry)) |
1518 | return NULL; |
1519 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias); |
1520 | __dget(alias); |
1521 | return alias; |
1522 | } |
1523 | |
1524 | /** |
1525 | * d_find_any_alias - find any alias for a given inode |
1526 | * @inode: inode to find an alias for |
1527 | * |
1528 | * If any aliases exist for the given inode, take and return a |
1529 | * reference for one of them. If no aliases exist, return %NULL. |
1530 | */ |
1531 | struct dentry *d_find_any_alias(struct inode *inode) |
1532 | { |
1533 | struct dentry *de; |
1534 | |
1535 | spin_lock(&inode->i_lock); |
1536 | de = __d_find_any_alias(inode); |
1537 | spin_unlock(&inode->i_lock); |
1538 | return de; |
1539 | } |
1540 | EXPORT_SYMBOL(d_find_any_alias); |
1541 | |
1542 | /** |
1543 | * d_obtain_alias - find or allocate a dentry for a given inode |
1544 | * @inode: inode to allocate the dentry for |
1545 | * |
1546 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
1547 | * similar open by handle operations. The returned dentry may be anonymous, |
1548 | * or may have a full name (if the inode was already in the cache). |
1549 | * |
1550 | * When called on a directory inode, we must ensure that the inode only ever |
1551 | * has one dentry. If a dentry is found, that is returned instead of |
1552 | * allocating a new one. |
1553 | * |
1554 | * On successful return, the reference to the inode has been transferred |
1555 | * to the dentry. In case of an error the reference on the inode is released. |
1556 | * To make it easier to use in export operations a %NULL or IS_ERR inode may |
1557 | * be passed in and will be the error will be propagate to the return value, |
1558 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
1559 | */ |
1560 | struct dentry *d_obtain_alias(struct inode *inode) |
1561 | { |
1562 | static const struct qstr anonstring = QSTR_INIT("/", 1); |
1563 | struct dentry *tmp; |
1564 | struct dentry *res; |
1565 | |
1566 | if (!inode) |
1567 | return ERR_PTR(-ESTALE); |
1568 | if (IS_ERR(inode)) |
1569 | return ERR_CAST(inode); |
1570 | |
1571 | res = d_find_any_alias(inode); |
1572 | if (res) |
1573 | goto out_iput; |
1574 | |
1575 | tmp = __d_alloc(inode->i_sb, &anonstring); |
1576 | if (!tmp) { |
1577 | res = ERR_PTR(-ENOMEM); |
1578 | goto out_iput; |
1579 | } |
1580 | |
1581 | spin_lock(&inode->i_lock); |
1582 | res = __d_find_any_alias(inode); |
1583 | if (res) { |
1584 | spin_unlock(&inode->i_lock); |
1585 | dput(tmp); |
1586 | goto out_iput; |
1587 | } |
1588 | |
1589 | /* attach a disconnected dentry */ |
1590 | spin_lock(&tmp->d_lock); |
1591 | tmp->d_inode = inode; |
1592 | tmp->d_flags |= DCACHE_DISCONNECTED; |
1593 | hlist_add_head(&tmp->d_alias, &inode->i_dentry); |
1594 | hlist_bl_lock(&tmp->d_sb->s_anon); |
1595 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1596 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
1597 | spin_unlock(&tmp->d_lock); |
1598 | spin_unlock(&inode->i_lock); |
1599 | security_d_instantiate(tmp, inode); |
1600 | |
1601 | return tmp; |
1602 | |
1603 | out_iput: |
1604 | if (res && !IS_ERR(res)) |
1605 | security_d_instantiate(res, inode); |
1606 | iput(inode); |
1607 | return res; |
1608 | } |
1609 | EXPORT_SYMBOL(d_obtain_alias); |
1610 | |
1611 | /** |
1612 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
1613 | * @inode: the inode which may have a disconnected dentry |
1614 | * @dentry: a negative dentry which we want to point to the inode. |
1615 | * |
1616 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and |
1617 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry |
1618 | * and return it, else simply d_add the inode to the dentry and return NULL. |
1619 | * |
1620 | * This is needed in the lookup routine of any filesystem that is exportable |
1621 | * (via knfsd) so that we can build dcache paths to directories effectively. |
1622 | * |
1623 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
1624 | * is returned. This matches the expected return value of ->lookup. |
1625 | * |
1626 | */ |
1627 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
1628 | { |
1629 | struct dentry *new = NULL; |
1630 | |
1631 | if (IS_ERR(inode)) |
1632 | return ERR_CAST(inode); |
1633 | |
1634 | if (inode && S_ISDIR(inode->i_mode)) { |
1635 | spin_lock(&inode->i_lock); |
1636 | new = __d_find_alias(inode, 1); |
1637 | if (new) { |
1638 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
1639 | spin_unlock(&inode->i_lock); |
1640 | security_d_instantiate(new, inode); |
1641 | d_move(new, dentry); |
1642 | iput(inode); |
1643 | } else { |
1644 | /* already taking inode->i_lock, so d_add() by hand */ |
1645 | __d_instantiate(dentry, inode); |
1646 | spin_unlock(&inode->i_lock); |
1647 | security_d_instantiate(dentry, inode); |
1648 | d_rehash(dentry); |
1649 | } |
1650 | } else |
1651 | d_add(dentry, inode); |
1652 | return new; |
1653 | } |
1654 | EXPORT_SYMBOL(d_splice_alias); |
1655 | |
1656 | /** |
1657 | * d_add_ci - lookup or allocate new dentry with case-exact name |
1658 | * @inode: the inode case-insensitive lookup has found |
1659 | * @dentry: the negative dentry that was passed to the parent's lookup func |
1660 | * @name: the case-exact name to be associated with the returned dentry |
1661 | * |
1662 | * This is to avoid filling the dcache with case-insensitive names to the |
1663 | * same inode, only the actual correct case is stored in the dcache for |
1664 | * case-insensitive filesystems. |
1665 | * |
1666 | * For a case-insensitive lookup match and if the the case-exact dentry |
1667 | * already exists in in the dcache, use it and return it. |
1668 | * |
1669 | * If no entry exists with the exact case name, allocate new dentry with |
1670 | * the exact case, and return the spliced entry. |
1671 | */ |
1672 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
1673 | struct qstr *name) |
1674 | { |
1675 | struct dentry *found; |
1676 | struct dentry *new; |
1677 | |
1678 | /* |
1679 | * First check if a dentry matching the name already exists, |
1680 | * if not go ahead and create it now. |
1681 | */ |
1682 | found = d_hash_and_lookup(dentry->d_parent, name); |
1683 | if (unlikely(IS_ERR(found))) |
1684 | goto err_out; |
1685 | if (!found) { |
1686 | new = d_alloc(dentry->d_parent, name); |
1687 | if (!new) { |
1688 | found = ERR_PTR(-ENOMEM); |
1689 | goto err_out; |
1690 | } |
1691 | |
1692 | found = d_splice_alias(inode, new); |
1693 | if (found) { |
1694 | dput(new); |
1695 | return found; |
1696 | } |
1697 | return new; |
1698 | } |
1699 | |
1700 | /* |
1701 | * If a matching dentry exists, and it's not negative use it. |
1702 | * |
1703 | * Decrement the reference count to balance the iget() done |
1704 | * earlier on. |
1705 | */ |
1706 | if (found->d_inode) { |
1707 | if (unlikely(found->d_inode != inode)) { |
1708 | /* This can't happen because bad inodes are unhashed. */ |
1709 | BUG_ON(!is_bad_inode(inode)); |
1710 | BUG_ON(!is_bad_inode(found->d_inode)); |
1711 | } |
1712 | iput(inode); |
1713 | return found; |
1714 | } |
1715 | |
1716 | /* |
1717 | * Negative dentry: instantiate it unless the inode is a directory and |
1718 | * already has a dentry. |
1719 | */ |
1720 | new = d_splice_alias(inode, found); |
1721 | if (new) { |
1722 | dput(found); |
1723 | found = new; |
1724 | } |
1725 | return found; |
1726 | |
1727 | err_out: |
1728 | iput(inode); |
1729 | return found; |
1730 | } |
1731 | EXPORT_SYMBOL(d_add_ci); |
1732 | |
1733 | /* |
1734 | * Do the slow-case of the dentry name compare. |
1735 | * |
1736 | * Unlike the dentry_cmp() function, we need to atomically |
1737 | * load the name, length and inode information, so that the |
1738 | * filesystem can rely on them, and can use the 'name' and |
1739 | * 'len' information without worrying about walking off the |
1740 | * end of memory etc. |
1741 | * |
1742 | * Thus the read_seqcount_retry() and the "duplicate" info |
1743 | * in arguments (the low-level filesystem should not look |
1744 | * at the dentry inode or name contents directly, since |
1745 | * rename can change them while we're in RCU mode). |
1746 | */ |
1747 | enum slow_d_compare { |
1748 | D_COMP_OK, |
1749 | D_COMP_NOMATCH, |
1750 | D_COMP_SEQRETRY, |
1751 | }; |
1752 | |
1753 | static noinline enum slow_d_compare slow_dentry_cmp( |
1754 | const struct dentry *parent, |
1755 | struct inode *inode, |
1756 | struct dentry *dentry, |
1757 | unsigned int seq, |
1758 | const struct qstr *name) |
1759 | { |
1760 | int tlen = dentry->d_name.len; |
1761 | const char *tname = dentry->d_name.name; |
1762 | struct inode *i = dentry->d_inode; |
1763 | |
1764 | if (read_seqcount_retry(&dentry->d_seq, seq)) { |
1765 | cpu_relax(); |
1766 | return D_COMP_SEQRETRY; |
1767 | } |
1768 | if (parent->d_op->d_compare(parent, inode, |
1769 | dentry, i, |
1770 | tlen, tname, name)) |
1771 | return D_COMP_NOMATCH; |
1772 | return D_COMP_OK; |
1773 | } |
1774 | |
1775 | /** |
1776 | * __d_lookup_rcu - search for a dentry (racy, store-free) |
1777 | * @parent: parent dentry |
1778 | * @name: qstr of name we wish to find |
1779 | * @seqp: returns d_seq value at the point where the dentry was found |
1780 | * @inode: returns dentry->d_inode when the inode was found valid. |
1781 | * Returns: dentry, or NULL |
1782 | * |
1783 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name |
1784 | * resolution (store-free path walking) design described in |
1785 | * Documentation/filesystems/path-lookup.txt. |
1786 | * |
1787 | * This is not to be used outside core vfs. |
1788 | * |
1789 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock |
1790 | * held, and rcu_read_lock held. The returned dentry must not be stored into |
1791 | * without taking d_lock and checking d_seq sequence count against @seq |
1792 | * returned here. |
1793 | * |
1794 | * A refcount may be taken on the found dentry with the __d_rcu_to_refcount |
1795 | * function. |
1796 | * |
1797 | * Alternatively, __d_lookup_rcu may be called again to look up the child of |
1798 | * the returned dentry, so long as its parent's seqlock is checked after the |
1799 | * child is looked up. Thus, an interlocking stepping of sequence lock checks |
1800 | * is formed, giving integrity down the path walk. |
1801 | * |
1802 | * NOTE! The caller *has* to check the resulting dentry against the sequence |
1803 | * number we've returned before using any of the resulting dentry state! |
1804 | */ |
1805 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
1806 | const struct qstr *name, |
1807 | unsigned *seqp, struct inode *inode) |
1808 | { |
1809 | u64 hashlen = name->hash_len; |
1810 | const unsigned char *str = name->name; |
1811 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
1812 | struct hlist_bl_node *node; |
1813 | struct dentry *dentry; |
1814 | |
1815 | /* |
1816 | * Note: There is significant duplication with __d_lookup_rcu which is |
1817 | * required to prevent single threaded performance regressions |
1818 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
1819 | * Keep the two functions in sync. |
1820 | */ |
1821 | |
1822 | /* |
1823 | * The hash list is protected using RCU. |
1824 | * |
1825 | * Carefully use d_seq when comparing a candidate dentry, to avoid |
1826 | * races with d_move(). |
1827 | * |
1828 | * It is possible that concurrent renames can mess up our list |
1829 | * walk here and result in missing our dentry, resulting in the |
1830 | * false-negative result. d_lookup() protects against concurrent |
1831 | * renames using rename_lock seqlock. |
1832 | * |
1833 | * See Documentation/filesystems/path-lookup.txt for more details. |
1834 | */ |
1835 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1836 | unsigned seq; |
1837 | |
1838 | seqretry: |
1839 | /* |
1840 | * The dentry sequence count protects us from concurrent |
1841 | * renames, and thus protects inode, parent and name fields. |
1842 | * |
1843 | * The caller must perform a seqcount check in order |
1844 | * to do anything useful with the returned dentry, |
1845 | * including using the 'd_inode' pointer. |
1846 | * |
1847 | * NOTE! We do a "raw" seqcount_begin here. That means that |
1848 | * we don't wait for the sequence count to stabilize if it |
1849 | * is in the middle of a sequence change. If we do the slow |
1850 | * dentry compare, we will do seqretries until it is stable, |
1851 | * and if we end up with a successful lookup, we actually |
1852 | * want to exit RCU lookup anyway. |
1853 | */ |
1854 | seq = raw_seqcount_begin(&dentry->d_seq); |
1855 | if (dentry->d_parent != parent) |
1856 | continue; |
1857 | if (d_unhashed(dentry)) |
1858 | continue; |
1859 | *seqp = seq; |
1860 | |
1861 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
1862 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
1863 | continue; |
1864 | switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) { |
1865 | case D_COMP_OK: |
1866 | return dentry; |
1867 | case D_COMP_NOMATCH: |
1868 | continue; |
1869 | default: |
1870 | goto seqretry; |
1871 | } |
1872 | } |
1873 | |
1874 | if (dentry->d_name.hash_len != hashlen) |
1875 | continue; |
1876 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
1877 | return dentry; |
1878 | } |
1879 | return NULL; |
1880 | } |
1881 | |
1882 | /** |
1883 | * d_lookup - search for a dentry |
1884 | * @parent: parent dentry |
1885 | * @name: qstr of name we wish to find |
1886 | * Returns: dentry, or NULL |
1887 | * |
1888 | * d_lookup searches the children of the parent dentry for the name in |
1889 | * question. If the dentry is found its reference count is incremented and the |
1890 | * dentry is returned. The caller must use dput to free the entry when it has |
1891 | * finished using it. %NULL is returned if the dentry does not exist. |
1892 | */ |
1893 | struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1894 | { |
1895 | struct dentry *dentry; |
1896 | unsigned seq; |
1897 | |
1898 | do { |
1899 | seq = read_seqbegin(&rename_lock); |
1900 | dentry = __d_lookup(parent, name); |
1901 | if (dentry) |
1902 | break; |
1903 | } while (read_seqretry(&rename_lock, seq)); |
1904 | return dentry; |
1905 | } |
1906 | EXPORT_SYMBOL(d_lookup); |
1907 | |
1908 | /** |
1909 | * __d_lookup - search for a dentry (racy) |
1910 | * @parent: parent dentry |
1911 | * @name: qstr of name we wish to find |
1912 | * Returns: dentry, or NULL |
1913 | * |
1914 | * __d_lookup is like d_lookup, however it may (rarely) return a |
1915 | * false-negative result due to unrelated rename activity. |
1916 | * |
1917 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
1918 | * however it must be used carefully, eg. with a following d_lookup in |
1919 | * the case of failure. |
1920 | * |
1921 | * __d_lookup callers must be commented. |
1922 | */ |
1923 | struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1924 | { |
1925 | unsigned int len = name->len; |
1926 | unsigned int hash = name->hash; |
1927 | const unsigned char *str = name->name; |
1928 | struct hlist_bl_head *b = d_hash(parent, hash); |
1929 | struct hlist_bl_node *node; |
1930 | struct dentry *found = NULL; |
1931 | struct dentry *dentry; |
1932 | |
1933 | /* |
1934 | * Note: There is significant duplication with __d_lookup_rcu which is |
1935 | * required to prevent single threaded performance regressions |
1936 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
1937 | * Keep the two functions in sync. |
1938 | */ |
1939 | |
1940 | /* |
1941 | * The hash list is protected using RCU. |
1942 | * |
1943 | * Take d_lock when comparing a candidate dentry, to avoid races |
1944 | * with d_move(). |
1945 | * |
1946 | * It is possible that concurrent renames can mess up our list |
1947 | * walk here and result in missing our dentry, resulting in the |
1948 | * false-negative result. d_lookup() protects against concurrent |
1949 | * renames using rename_lock seqlock. |
1950 | * |
1951 | * See Documentation/filesystems/path-lookup.txt for more details. |
1952 | */ |
1953 | rcu_read_lock(); |
1954 | |
1955 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1956 | |
1957 | if (dentry->d_name.hash != hash) |
1958 | continue; |
1959 | |
1960 | spin_lock(&dentry->d_lock); |
1961 | if (dentry->d_parent != parent) |
1962 | goto next; |
1963 | if (d_unhashed(dentry)) |
1964 | goto next; |
1965 | |
1966 | /* |
1967 | * It is safe to compare names since d_move() cannot |
1968 | * change the qstr (protected by d_lock). |
1969 | */ |
1970 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
1971 | int tlen = dentry->d_name.len; |
1972 | const char *tname = dentry->d_name.name; |
1973 | if (parent->d_op->d_compare(parent, parent->d_inode, |
1974 | dentry, dentry->d_inode, |
1975 | tlen, tname, name)) |
1976 | goto next; |
1977 | } else { |
1978 | if (dentry->d_name.len != len) |
1979 | goto next; |
1980 | if (dentry_cmp(dentry, str, len)) |
1981 | goto next; |
1982 | } |
1983 | |
1984 | dentry->d_count++; |
1985 | found = dentry; |
1986 | spin_unlock(&dentry->d_lock); |
1987 | break; |
1988 | next: |
1989 | spin_unlock(&dentry->d_lock); |
1990 | } |
1991 | rcu_read_unlock(); |
1992 | |
1993 | return found; |
1994 | } |
1995 | |
1996 | /** |
1997 | * d_hash_and_lookup - hash the qstr then search for a dentry |
1998 | * @dir: Directory to search in |
1999 | * @name: qstr of name we wish to find |
2000 | * |
2001 | * On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
2002 | */ |
2003 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
2004 | { |
2005 | /* |
2006 | * Check for a fs-specific hash function. Note that we must |
2007 | * calculate the standard hash first, as the d_op->d_hash() |
2008 | * routine may choose to leave the hash value unchanged. |
2009 | */ |
2010 | name->hash = full_name_hash(name->name, name->len); |
2011 | if (dir->d_flags & DCACHE_OP_HASH) { |
2012 | int err = dir->d_op->d_hash(dir, dir->d_inode, name); |
2013 | if (unlikely(err < 0)) |
2014 | return ERR_PTR(err); |
2015 | } |
2016 | return d_lookup(dir, name); |
2017 | } |
2018 | EXPORT_SYMBOL(d_hash_and_lookup); |
2019 | |
2020 | /** |
2021 | * d_validate - verify dentry provided from insecure source (deprecated) |
2022 | * @dentry: The dentry alleged to be valid child of @dparent |
2023 | * @dparent: The parent dentry (known to be valid) |
2024 | * |
2025 | * An insecure source has sent us a dentry, here we verify it and dget() it. |
2026 | * This is used by ncpfs in its readdir implementation. |
2027 | * Zero is returned in the dentry is invalid. |
2028 | * |
2029 | * This function is slow for big directories, and deprecated, do not use it. |
2030 | */ |
2031 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
2032 | { |
2033 | struct dentry *child; |
2034 | |
2035 | spin_lock(&dparent->d_lock); |
2036 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
2037 | if (dentry == child) { |
2038 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
2039 | __dget_dlock(dentry); |
2040 | spin_unlock(&dentry->d_lock); |
2041 | spin_unlock(&dparent->d_lock); |
2042 | return 1; |
2043 | } |
2044 | } |
2045 | spin_unlock(&dparent->d_lock); |
2046 | |
2047 | return 0; |
2048 | } |
2049 | EXPORT_SYMBOL(d_validate); |
2050 | |
2051 | /* |
2052 | * When a file is deleted, we have two options: |
2053 | * - turn this dentry into a negative dentry |
2054 | * - unhash this dentry and free it. |
2055 | * |
2056 | * Usually, we want to just turn this into |
2057 | * a negative dentry, but if anybody else is |
2058 | * currently using the dentry or the inode |
2059 | * we can't do that and we fall back on removing |
2060 | * it from the hash queues and waiting for |
2061 | * it to be deleted later when it has no users |
2062 | */ |
2063 | |
2064 | /** |
2065 | * d_delete - delete a dentry |
2066 | * @dentry: The dentry to delete |
2067 | * |
2068 | * Turn the dentry into a negative dentry if possible, otherwise |
2069 | * remove it from the hash queues so it can be deleted later |
2070 | */ |
2071 | |
2072 | void d_delete(struct dentry * dentry) |
2073 | { |
2074 | struct inode *inode; |
2075 | int isdir = 0; |
2076 | /* |
2077 | * Are we the only user? |
2078 | */ |
2079 | again: |
2080 | spin_lock(&dentry->d_lock); |
2081 | inode = dentry->d_inode; |
2082 | isdir = S_ISDIR(inode->i_mode); |
2083 | if (dentry->d_count == 1) { |
2084 | if (!spin_trylock(&inode->i_lock)) { |
2085 | spin_unlock(&dentry->d_lock); |
2086 | cpu_relax(); |
2087 | goto again; |
2088 | } |
2089 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
2090 | dentry_unlink_inode(dentry); |
2091 | fsnotify_nameremove(dentry, isdir); |
2092 | return; |
2093 | } |
2094 | |
2095 | if (!d_unhashed(dentry)) |
2096 | __d_drop(dentry); |
2097 | |
2098 | spin_unlock(&dentry->d_lock); |
2099 | |
2100 | fsnotify_nameremove(dentry, isdir); |
2101 | } |
2102 | EXPORT_SYMBOL(d_delete); |
2103 | |
2104 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
2105 | { |
2106 | BUG_ON(!d_unhashed(entry)); |
2107 | hlist_bl_lock(b); |
2108 | entry->d_flags |= DCACHE_RCUACCESS; |
2109 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
2110 | hlist_bl_unlock(b); |
2111 | } |
2112 | |
2113 | static void _d_rehash(struct dentry * entry) |
2114 | { |
2115 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
2116 | } |
2117 | |
2118 | /** |
2119 | * d_rehash - add an entry back to the hash |
2120 | * @entry: dentry to add to the hash |
2121 | * |
2122 | * Adds a dentry to the hash according to its name. |
2123 | */ |
2124 | |
2125 | void d_rehash(struct dentry * entry) |
2126 | { |
2127 | spin_lock(&entry->d_lock); |
2128 | _d_rehash(entry); |
2129 | spin_unlock(&entry->d_lock); |
2130 | } |
2131 | EXPORT_SYMBOL(d_rehash); |
2132 | |
2133 | /** |
2134 | * dentry_update_name_case - update case insensitive dentry with a new name |
2135 | * @dentry: dentry to be updated |
2136 | * @name: new name |
2137 | * |
2138 | * Update a case insensitive dentry with new case of name. |
2139 | * |
2140 | * dentry must have been returned by d_lookup with name @name. Old and new |
2141 | * name lengths must match (ie. no d_compare which allows mismatched name |
2142 | * lengths). |
2143 | * |
2144 | * Parent inode i_mutex must be held over d_lookup and into this call (to |
2145 | * keep renames and concurrent inserts, and readdir(2) away). |
2146 | */ |
2147 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
2148 | { |
2149 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
2150 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2151 | |
2152 | spin_lock(&dentry->d_lock); |
2153 | write_seqcount_begin(&dentry->d_seq); |
2154 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
2155 | write_seqcount_end(&dentry->d_seq); |
2156 | spin_unlock(&dentry->d_lock); |
2157 | } |
2158 | EXPORT_SYMBOL(dentry_update_name_case); |
2159 | |
2160 | static void switch_names(struct dentry *dentry, struct dentry *target) |
2161 | { |
2162 | if (dname_external(target)) { |
2163 | if (dname_external(dentry)) { |
2164 | /* |
2165 | * Both external: swap the pointers |
2166 | */ |
2167 | swap(target->d_name.name, dentry->d_name.name); |
2168 | } else { |
2169 | /* |
2170 | * dentry:internal, target:external. Steal target's |
2171 | * storage and make target internal. |
2172 | */ |
2173 | memcpy(target->d_iname, dentry->d_name.name, |
2174 | dentry->d_name.len + 1); |
2175 | dentry->d_name.name = target->d_name.name; |
2176 | target->d_name.name = target->d_iname; |
2177 | } |
2178 | } else { |
2179 | if (dname_external(dentry)) { |
2180 | /* |
2181 | * dentry:external, target:internal. Give dentry's |
2182 | * storage to target and make dentry internal |
2183 | */ |
2184 | memcpy(dentry->d_iname, target->d_name.name, |
2185 | target->d_name.len + 1); |
2186 | target->d_name.name = dentry->d_name.name; |
2187 | dentry->d_name.name = dentry->d_iname; |
2188 | } else { |
2189 | /* |
2190 | * Both are internal. Just copy target to dentry |
2191 | */ |
2192 | memcpy(dentry->d_iname, target->d_name.name, |
2193 | target->d_name.len + 1); |
2194 | dentry->d_name.len = target->d_name.len; |
2195 | return; |
2196 | } |
2197 | } |
2198 | swap(dentry->d_name.len, target->d_name.len); |
2199 | } |
2200 | |
2201 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2202 | { |
2203 | /* |
2204 | * XXXX: do we really need to take target->d_lock? |
2205 | */ |
2206 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) |
2207 | spin_lock(&target->d_parent->d_lock); |
2208 | else { |
2209 | if (d_ancestor(dentry->d_parent, target->d_parent)) { |
2210 | spin_lock(&dentry->d_parent->d_lock); |
2211 | spin_lock_nested(&target->d_parent->d_lock, |
2212 | DENTRY_D_LOCK_NESTED); |
2213 | } else { |
2214 | spin_lock(&target->d_parent->d_lock); |
2215 | spin_lock_nested(&dentry->d_parent->d_lock, |
2216 | DENTRY_D_LOCK_NESTED); |
2217 | } |
2218 | } |
2219 | if (target < dentry) { |
2220 | spin_lock_nested(&target->d_lock, 2); |
2221 | spin_lock_nested(&dentry->d_lock, 3); |
2222 | } else { |
2223 | spin_lock_nested(&dentry->d_lock, 2); |
2224 | spin_lock_nested(&target->d_lock, 3); |
2225 | } |
2226 | } |
2227 | |
2228 | static void dentry_unlock_parents_for_move(struct dentry *dentry, |
2229 | struct dentry *target) |
2230 | { |
2231 | if (target->d_parent != dentry->d_parent) |
2232 | spin_unlock(&dentry->d_parent->d_lock); |
2233 | if (target->d_parent != target) |
2234 | spin_unlock(&target->d_parent->d_lock); |
2235 | } |
2236 | |
2237 | /* |
2238 | * When switching names, the actual string doesn't strictly have to |
2239 | * be preserved in the target - because we're dropping the target |
2240 | * anyway. As such, we can just do a simple memcpy() to copy over |
2241 | * the new name before we switch. |
2242 | * |
2243 | * Note that we have to be a lot more careful about getting the hash |
2244 | * switched - we have to switch the hash value properly even if it |
2245 | * then no longer matches the actual (corrupted) string of the target. |
2246 | * The hash value has to match the hash queue that the dentry is on.. |
2247 | */ |
2248 | /* |
2249 | * __d_move - move a dentry |
2250 | * @dentry: entry to move |
2251 | * @target: new dentry |
2252 | * |
2253 | * Update the dcache to reflect the move of a file name. Negative |
2254 | * dcache entries should not be moved in this way. Caller must hold |
2255 | * rename_lock, the i_mutex of the source and target directories, |
2256 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). |
2257 | */ |
2258 | static void __d_move(struct dentry * dentry, struct dentry * target) |
2259 | { |
2260 | if (!dentry->d_inode) |
2261 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
2262 | |
2263 | BUG_ON(d_ancestor(dentry, target)); |
2264 | BUG_ON(d_ancestor(target, dentry)); |
2265 | |
2266 | dentry_lock_for_move(dentry, target); |
2267 | |
2268 | write_seqcount_begin(&dentry->d_seq); |
2269 | write_seqcount_begin(&target->d_seq); |
2270 | |
2271 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2272 | |
2273 | /* |
2274 | * Move the dentry to the target hash queue. Don't bother checking |
2275 | * for the same hash queue because of how unlikely it is. |
2276 | */ |
2277 | __d_drop(dentry); |
2278 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
2279 | |
2280 | /* Unhash the target: dput() will then get rid of it */ |
2281 | __d_drop(target); |
2282 | |
2283 | list_del(&dentry->d_u.d_child); |
2284 | list_del(&target->d_u.d_child); |
2285 | |
2286 | /* Switch the names.. */ |
2287 | switch_names(dentry, target); |
2288 | swap(dentry->d_name.hash, target->d_name.hash); |
2289 | |
2290 | /* ... and switch the parents */ |
2291 | if (IS_ROOT(dentry)) { |
2292 | dentry->d_parent = target->d_parent; |
2293 | target->d_parent = target; |
2294 | INIT_LIST_HEAD(&target->d_u.d_child); |
2295 | } else { |
2296 | swap(dentry->d_parent, target->d_parent); |
2297 | |
2298 | /* And add them back to the (new) parent lists */ |
2299 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
2300 | } |
2301 | |
2302 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2303 | |
2304 | write_seqcount_end(&target->d_seq); |
2305 | write_seqcount_end(&dentry->d_seq); |
2306 | |
2307 | dentry_unlock_parents_for_move(dentry, target); |
2308 | spin_unlock(&target->d_lock); |
2309 | fsnotify_d_move(dentry); |
2310 | spin_unlock(&dentry->d_lock); |
2311 | } |
2312 | |
2313 | /* |
2314 | * d_move - move a dentry |
2315 | * @dentry: entry to move |
2316 | * @target: new dentry |
2317 | * |
2318 | * Update the dcache to reflect the move of a file name. Negative |
2319 | * dcache entries should not be moved in this way. See the locking |
2320 | * requirements for __d_move. |
2321 | */ |
2322 | void d_move(struct dentry *dentry, struct dentry *target) |
2323 | { |
2324 | write_seqlock(&rename_lock); |
2325 | __d_move(dentry, target); |
2326 | write_sequnlock(&rename_lock); |
2327 | } |
2328 | EXPORT_SYMBOL(d_move); |
2329 | |
2330 | /** |
2331 | * d_ancestor - search for an ancestor |
2332 | * @p1: ancestor dentry |
2333 | * @p2: child dentry |
2334 | * |
2335 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
2336 | * an ancestor of p2, else NULL. |
2337 | */ |
2338 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
2339 | { |
2340 | struct dentry *p; |
2341 | |
2342 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
2343 | if (p->d_parent == p1) |
2344 | return p; |
2345 | } |
2346 | return NULL; |
2347 | } |
2348 | |
2349 | /* |
2350 | * This helper attempts to cope with remotely renamed directories |
2351 | * |
2352 | * It assumes that the caller is already holding |
2353 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
2354 | * |
2355 | * Note: If ever the locking in lock_rename() changes, then please |
2356 | * remember to update this too... |
2357 | */ |
2358 | static struct dentry *__d_unalias(struct inode *inode, |
2359 | struct dentry *dentry, struct dentry *alias) |
2360 | { |
2361 | struct mutex *m1 = NULL, *m2 = NULL; |
2362 | struct dentry *ret = ERR_PTR(-EBUSY); |
2363 | |
2364 | /* If alias and dentry share a parent, then no extra locks required */ |
2365 | if (alias->d_parent == dentry->d_parent) |
2366 | goto out_unalias; |
2367 | |
2368 | /* See lock_rename() */ |
2369 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2370 | goto out_err; |
2371 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
2372 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
2373 | goto out_err; |
2374 | m2 = &alias->d_parent->d_inode->i_mutex; |
2375 | out_unalias: |
2376 | if (likely(!d_mountpoint(alias))) { |
2377 | __d_move(alias, dentry); |
2378 | ret = alias; |
2379 | } |
2380 | out_err: |
2381 | spin_unlock(&inode->i_lock); |
2382 | if (m2) |
2383 | mutex_unlock(m2); |
2384 | if (m1) |
2385 | mutex_unlock(m1); |
2386 | return ret; |
2387 | } |
2388 | |
2389 | /* |
2390 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a |
2391 | * named dentry in place of the dentry to be replaced. |
2392 | * returns with anon->d_lock held! |
2393 | */ |
2394 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) |
2395 | { |
2396 | struct dentry *dparent; |
2397 | |
2398 | dentry_lock_for_move(anon, dentry); |
2399 | |
2400 | write_seqcount_begin(&dentry->d_seq); |
2401 | write_seqcount_begin(&anon->d_seq); |
2402 | |
2403 | dparent = dentry->d_parent; |
2404 | |
2405 | switch_names(dentry, anon); |
2406 | swap(dentry->d_name.hash, anon->d_name.hash); |
2407 | |
2408 | dentry->d_parent = dentry; |
2409 | list_del_init(&dentry->d_u.d_child); |
2410 | anon->d_parent = dparent; |
2411 | list_del(&anon->d_u.d_child); |
2412 | list_add(&anon->d_u.d_child, &dparent->d_subdirs); |
2413 | |
2414 | write_seqcount_end(&dentry->d_seq); |
2415 | write_seqcount_end(&anon->d_seq); |
2416 | |
2417 | dentry_unlock_parents_for_move(anon, dentry); |
2418 | spin_unlock(&dentry->d_lock); |
2419 | |
2420 | /* anon->d_lock still locked, returns locked */ |
2421 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
2422 | } |
2423 | |
2424 | /** |
2425 | * d_materialise_unique - introduce an inode into the tree |
2426 | * @dentry: candidate dentry |
2427 | * @inode: inode to bind to the dentry, to which aliases may be attached |
2428 | * |
2429 | * Introduces an dentry into the tree, substituting an extant disconnected |
2430 | * root directory alias in its place if there is one. Caller must hold the |
2431 | * i_mutex of the parent directory. |
2432 | */ |
2433 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) |
2434 | { |
2435 | struct dentry *actual; |
2436 | |
2437 | BUG_ON(!d_unhashed(dentry)); |
2438 | |
2439 | if (!inode) { |
2440 | actual = dentry; |
2441 | __d_instantiate(dentry, NULL); |
2442 | d_rehash(actual); |
2443 | goto out_nolock; |
2444 | } |
2445 | |
2446 | spin_lock(&inode->i_lock); |
2447 | |
2448 | if (S_ISDIR(inode->i_mode)) { |
2449 | struct dentry *alias; |
2450 | |
2451 | /* Does an aliased dentry already exist? */ |
2452 | alias = __d_find_alias(inode, 0); |
2453 | if (alias) { |
2454 | actual = alias; |
2455 | write_seqlock(&rename_lock); |
2456 | |
2457 | if (d_ancestor(alias, dentry)) { |
2458 | /* Check for loops */ |
2459 | actual = ERR_PTR(-ELOOP); |
2460 | spin_unlock(&inode->i_lock); |
2461 | } else if (IS_ROOT(alias)) { |
2462 | /* Is this an anonymous mountpoint that we |
2463 | * could splice into our tree? */ |
2464 | __d_materialise_dentry(dentry, alias); |
2465 | write_sequnlock(&rename_lock); |
2466 | __d_drop(alias); |
2467 | goto found; |
2468 | } else { |
2469 | /* Nope, but we must(!) avoid directory |
2470 | * aliasing. This drops inode->i_lock */ |
2471 | actual = __d_unalias(inode, dentry, alias); |
2472 | } |
2473 | write_sequnlock(&rename_lock); |
2474 | if (IS_ERR(actual)) { |
2475 | if (PTR_ERR(actual) == -ELOOP) |
2476 | pr_warn_ratelimited( |
2477 | "VFS: Lookup of '%s' in %s %s" |
2478 | " would have caused loop\n", |
2479 | dentry->d_name.name, |
2480 | inode->i_sb->s_type->name, |
2481 | inode->i_sb->s_id); |
2482 | dput(alias); |
2483 | } |
2484 | goto out_nolock; |
2485 | } |
2486 | } |
2487 | |
2488 | /* Add a unique reference */ |
2489 | actual = __d_instantiate_unique(dentry, inode); |
2490 | if (!actual) |
2491 | actual = dentry; |
2492 | else |
2493 | BUG_ON(!d_unhashed(actual)); |
2494 | |
2495 | spin_lock(&actual->d_lock); |
2496 | found: |
2497 | _d_rehash(actual); |
2498 | spin_unlock(&actual->d_lock); |
2499 | spin_unlock(&inode->i_lock); |
2500 | out_nolock: |
2501 | if (actual == dentry) { |
2502 | security_d_instantiate(dentry, inode); |
2503 | return NULL; |
2504 | } |
2505 | |
2506 | iput(inode); |
2507 | return actual; |
2508 | } |
2509 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
2510 | |
2511 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
2512 | { |
2513 | *buflen -= namelen; |
2514 | if (*buflen < 0) |
2515 | return -ENAMETOOLONG; |
2516 | *buffer -= namelen; |
2517 | memcpy(*buffer, str, namelen); |
2518 | return 0; |
2519 | } |
2520 | |
2521 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2522 | { |
2523 | return prepend(buffer, buflen, name->name, name->len); |
2524 | } |
2525 | |
2526 | /** |
2527 | * prepend_path - Prepend path string to a buffer |
2528 | * @path: the dentry/vfsmount to report |
2529 | * @root: root vfsmnt/dentry |
2530 | * @buffer: pointer to the end of the buffer |
2531 | * @buflen: pointer to buffer length |
2532 | * |
2533 | * Caller holds the rename_lock. |
2534 | */ |
2535 | static int prepend_path(const struct path *path, |
2536 | const struct path *root, |
2537 | char **buffer, int *buflen) |
2538 | { |
2539 | struct dentry *dentry = path->dentry; |
2540 | struct vfsmount *vfsmnt = path->mnt; |
2541 | struct mount *mnt = real_mount(vfsmnt); |
2542 | bool slash = false; |
2543 | int error = 0; |
2544 | |
2545 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
2546 | struct dentry * parent; |
2547 | |
2548 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
2549 | /* Global root? */ |
2550 | if (!mnt_has_parent(mnt)) |
2551 | goto global_root; |
2552 | dentry = mnt->mnt_mountpoint; |
2553 | mnt = mnt->mnt_parent; |
2554 | vfsmnt = &mnt->mnt; |
2555 | continue; |
2556 | } |
2557 | parent = dentry->d_parent; |
2558 | prefetch(parent); |
2559 | spin_lock(&dentry->d_lock); |
2560 | error = prepend_name(buffer, buflen, &dentry->d_name); |
2561 | spin_unlock(&dentry->d_lock); |
2562 | if (!error) |
2563 | error = prepend(buffer, buflen, "/", 1); |
2564 | if (error) |
2565 | break; |
2566 | |
2567 | slash = true; |
2568 | dentry = parent; |
2569 | } |
2570 | |
2571 | if (!error && !slash) |
2572 | error = prepend(buffer, buflen, "/", 1); |
2573 | |
2574 | return error; |
2575 | |
2576 | global_root: |
2577 | /* |
2578 | * Filesystems needing to implement special "root names" |
2579 | * should do so with ->d_dname() |
2580 | */ |
2581 | if (IS_ROOT(dentry) && |
2582 | (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { |
2583 | WARN(1, "Root dentry has weird name <%.*s>\n", |
2584 | (int) dentry->d_name.len, dentry->d_name.name); |
2585 | } |
2586 | if (!slash) |
2587 | error = prepend(buffer, buflen, "/", 1); |
2588 | if (!error) |
2589 | error = is_mounted(vfsmnt) ? 1 : 2; |
2590 | return error; |
2591 | } |
2592 | |
2593 | /** |
2594 | * __d_path - return the path of a dentry |
2595 | * @path: the dentry/vfsmount to report |
2596 | * @root: root vfsmnt/dentry |
2597 | * @buf: buffer to return value in |
2598 | * @buflen: buffer length |
2599 | * |
2600 | * Convert a dentry into an ASCII path name. |
2601 | * |
2602 | * Returns a pointer into the buffer or an error code if the |
2603 | * path was too long. |
2604 | * |
2605 | * "buflen" should be positive. |
2606 | * |
2607 | * If the path is not reachable from the supplied root, return %NULL. |
2608 | */ |
2609 | char *__d_path(const struct path *path, |
2610 | const struct path *root, |
2611 | char *buf, int buflen) |
2612 | { |
2613 | char *res = buf + buflen; |
2614 | int error; |
2615 | |
2616 | prepend(&res, &buflen, "\0", 1); |
2617 | br_read_lock(&vfsmount_lock); |
2618 | write_seqlock(&rename_lock); |
2619 | error = prepend_path(path, root, &res, &buflen); |
2620 | write_sequnlock(&rename_lock); |
2621 | br_read_unlock(&vfsmount_lock); |
2622 | |
2623 | if (error < 0) |
2624 | return ERR_PTR(error); |
2625 | if (error > 0) |
2626 | return NULL; |
2627 | return res; |
2628 | } |
2629 | |
2630 | char *d_absolute_path(const struct path *path, |
2631 | char *buf, int buflen) |
2632 | { |
2633 | struct path root = {}; |
2634 | char *res = buf + buflen; |
2635 | int error; |
2636 | |
2637 | prepend(&res, &buflen, "\0", 1); |
2638 | br_read_lock(&vfsmount_lock); |
2639 | write_seqlock(&rename_lock); |
2640 | error = prepend_path(path, &root, &res, &buflen); |
2641 | write_sequnlock(&rename_lock); |
2642 | br_read_unlock(&vfsmount_lock); |
2643 | |
2644 | if (error > 1) |
2645 | error = -EINVAL; |
2646 | if (error < 0) |
2647 | return ERR_PTR(error); |
2648 | return res; |
2649 | } |
2650 | |
2651 | /* |
2652 | * same as __d_path but appends "(deleted)" for unlinked files. |
2653 | */ |
2654 | static int path_with_deleted(const struct path *path, |
2655 | const struct path *root, |
2656 | char **buf, int *buflen) |
2657 | { |
2658 | prepend(buf, buflen, "\0", 1); |
2659 | if (d_unlinked(path->dentry)) { |
2660 | int error = prepend(buf, buflen, " (deleted)", 10); |
2661 | if (error) |
2662 | return error; |
2663 | } |
2664 | |
2665 | return prepend_path(path, root, buf, buflen); |
2666 | } |
2667 | |
2668 | static int prepend_unreachable(char **buffer, int *buflen) |
2669 | { |
2670 | return prepend(buffer, buflen, "(unreachable)", 13); |
2671 | } |
2672 | |
2673 | /** |
2674 | * d_path - return the path of a dentry |
2675 | * @path: path to report |
2676 | * @buf: buffer to return value in |
2677 | * @buflen: buffer length |
2678 | * |
2679 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
2680 | * the string " (deleted)" is appended. Note that this is ambiguous. |
2681 | * |
2682 | * Returns a pointer into the buffer or an error code if the path was |
2683 | * too long. Note: Callers should use the returned pointer, not the passed |
2684 | * in buffer, to use the name! The implementation often starts at an offset |
2685 | * into the buffer, and may leave 0 bytes at the start. |
2686 | * |
2687 | * "buflen" should be positive. |
2688 | */ |
2689 | char *d_path(const struct path *path, char *buf, int buflen) |
2690 | { |
2691 | char *res = buf + buflen; |
2692 | struct path root; |
2693 | int error; |
2694 | |
2695 | /* |
2696 | * We have various synthetic filesystems that never get mounted. On |
2697 | * these filesystems dentries are never used for lookup purposes, and |
2698 | * thus don't need to be hashed. They also don't need a name until a |
2699 | * user wants to identify the object in /proc/pid/fd/. The little hack |
2700 | * below allows us to generate a name for these objects on demand: |
2701 | */ |
2702 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2703 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
2704 | |
2705 | get_fs_root(current->fs, &root); |
2706 | br_read_lock(&vfsmount_lock); |
2707 | write_seqlock(&rename_lock); |
2708 | error = path_with_deleted(path, &root, &res, &buflen); |
2709 | write_sequnlock(&rename_lock); |
2710 | br_read_unlock(&vfsmount_lock); |
2711 | if (error < 0) |
2712 | res = ERR_PTR(error); |
2713 | path_put(&root); |
2714 | return res; |
2715 | } |
2716 | EXPORT_SYMBOL(d_path); |
2717 | |
2718 | /* |
2719 | * Helper function for dentry_operations.d_dname() members |
2720 | */ |
2721 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
2722 | const char *fmt, ...) |
2723 | { |
2724 | va_list args; |
2725 | char temp[64]; |
2726 | int sz; |
2727 | |
2728 | va_start(args, fmt); |
2729 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
2730 | va_end(args); |
2731 | |
2732 | if (sz > sizeof(temp) || sz > buflen) |
2733 | return ERR_PTR(-ENAMETOOLONG); |
2734 | |
2735 | buffer += buflen - sz; |
2736 | return memcpy(buffer, temp, sz); |
2737 | } |
2738 | |
2739 | /* |
2740 | * Write full pathname from the root of the filesystem into the buffer. |
2741 | */ |
2742 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
2743 | { |
2744 | char *end = buf + buflen; |
2745 | char *retval; |
2746 | |
2747 | prepend(&end, &buflen, "\0", 1); |
2748 | if (buflen < 1) |
2749 | goto Elong; |
2750 | /* Get '/' right */ |
2751 | retval = end-1; |
2752 | *retval = '/'; |
2753 | |
2754 | while (!IS_ROOT(dentry)) { |
2755 | struct dentry *parent = dentry->d_parent; |
2756 | int error; |
2757 | |
2758 | prefetch(parent); |
2759 | spin_lock(&dentry->d_lock); |
2760 | error = prepend_name(&end, &buflen, &dentry->d_name); |
2761 | spin_unlock(&dentry->d_lock); |
2762 | if (error != 0 || prepend(&end, &buflen, "/", 1) != 0) |
2763 | goto Elong; |
2764 | |
2765 | retval = end; |
2766 | dentry = parent; |
2767 | } |
2768 | return retval; |
2769 | Elong: |
2770 | return ERR_PTR(-ENAMETOOLONG); |
2771 | } |
2772 | |
2773 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
2774 | { |
2775 | char *retval; |
2776 | |
2777 | write_seqlock(&rename_lock); |
2778 | retval = __dentry_path(dentry, buf, buflen); |
2779 | write_sequnlock(&rename_lock); |
2780 | |
2781 | return retval; |
2782 | } |
2783 | EXPORT_SYMBOL(dentry_path_raw); |
2784 | |
2785 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
2786 | { |
2787 | char *p = NULL; |
2788 | char *retval; |
2789 | |
2790 | write_seqlock(&rename_lock); |
2791 | if (d_unlinked(dentry)) { |
2792 | p = buf + buflen; |
2793 | if (prepend(&p, &buflen, "//deleted", 10) != 0) |
2794 | goto Elong; |
2795 | buflen++; |
2796 | } |
2797 | retval = __dentry_path(dentry, buf, buflen); |
2798 | write_sequnlock(&rename_lock); |
2799 | if (!IS_ERR(retval) && p) |
2800 | *p = '/'; /* restore '/' overriden with '\0' */ |
2801 | return retval; |
2802 | Elong: |
2803 | return ERR_PTR(-ENAMETOOLONG); |
2804 | } |
2805 | |
2806 | /* |
2807 | * NOTE! The user-level library version returns a |
2808 | * character pointer. The kernel system call just |
2809 | * returns the length of the buffer filled (which |
2810 | * includes the ending '\0' character), or a negative |
2811 | * error value. So libc would do something like |
2812 | * |
2813 | * char *getcwd(char * buf, size_t size) |
2814 | * { |
2815 | * int retval; |
2816 | * |
2817 | * retval = sys_getcwd(buf, size); |
2818 | * if (retval >= 0) |
2819 | * return buf; |
2820 | * errno = -retval; |
2821 | * return NULL; |
2822 | * } |
2823 | */ |
2824 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
2825 | { |
2826 | int error; |
2827 | struct path pwd, root; |
2828 | char *page = (char *) __get_free_page(GFP_USER); |
2829 | |
2830 | if (!page) |
2831 | return -ENOMEM; |
2832 | |
2833 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
2834 | |
2835 | error = -ENOENT; |
2836 | br_read_lock(&vfsmount_lock); |
2837 | write_seqlock(&rename_lock); |
2838 | if (!d_unlinked(pwd.dentry)) { |
2839 | unsigned long len; |
2840 | char *cwd = page + PAGE_SIZE; |
2841 | int buflen = PAGE_SIZE; |
2842 | |
2843 | prepend(&cwd, &buflen, "\0", 1); |
2844 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
2845 | write_sequnlock(&rename_lock); |
2846 | br_read_unlock(&vfsmount_lock); |
2847 | |
2848 | if (error < 0) |
2849 | goto out; |
2850 | |
2851 | /* Unreachable from current root */ |
2852 | if (error > 0) { |
2853 | error = prepend_unreachable(&cwd, &buflen); |
2854 | if (error) |
2855 | goto out; |
2856 | } |
2857 | |
2858 | error = -ERANGE; |
2859 | len = PAGE_SIZE + page - cwd; |
2860 | if (len <= size) { |
2861 | error = len; |
2862 | if (copy_to_user(buf, cwd, len)) |
2863 | error = -EFAULT; |
2864 | } |
2865 | } else { |
2866 | write_sequnlock(&rename_lock); |
2867 | br_read_unlock(&vfsmount_lock); |
2868 | } |
2869 | |
2870 | out: |
2871 | path_put(&pwd); |
2872 | path_put(&root); |
2873 | free_page((unsigned long) page); |
2874 | return error; |
2875 | } |
2876 | |
2877 | /* |
2878 | * Test whether new_dentry is a subdirectory of old_dentry. |
2879 | * |
2880 | * Trivially implemented using the dcache structure |
2881 | */ |
2882 | |
2883 | /** |
2884 | * is_subdir - is new dentry a subdirectory of old_dentry |
2885 | * @new_dentry: new dentry |
2886 | * @old_dentry: old dentry |
2887 | * |
2888 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
2889 | * Returns 0 otherwise. |
2890 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
2891 | */ |
2892 | |
2893 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
2894 | { |
2895 | int result; |
2896 | unsigned seq; |
2897 | |
2898 | if (new_dentry == old_dentry) |
2899 | return 1; |
2900 | |
2901 | do { |
2902 | /* for restarting inner loop in case of seq retry */ |
2903 | seq = read_seqbegin(&rename_lock); |
2904 | /* |
2905 | * Need rcu_readlock to protect against the d_parent trashing |
2906 | * due to d_move |
2907 | */ |
2908 | rcu_read_lock(); |
2909 | if (d_ancestor(old_dentry, new_dentry)) |
2910 | result = 1; |
2911 | else |
2912 | result = 0; |
2913 | rcu_read_unlock(); |
2914 | } while (read_seqretry(&rename_lock, seq)); |
2915 | |
2916 | return result; |
2917 | } |
2918 | |
2919 | void d_genocide(struct dentry *root) |
2920 | { |
2921 | struct dentry *this_parent; |
2922 | struct list_head *next; |
2923 | unsigned seq; |
2924 | int locked = 0; |
2925 | |
2926 | seq = read_seqbegin(&rename_lock); |
2927 | again: |
2928 | this_parent = root; |
2929 | spin_lock(&this_parent->d_lock); |
2930 | repeat: |
2931 | next = this_parent->d_subdirs.next; |
2932 | resume: |
2933 | while (next != &this_parent->d_subdirs) { |
2934 | struct list_head *tmp = next; |
2935 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
2936 | next = tmp->next; |
2937 | |
2938 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
2939 | if (d_unhashed(dentry) || !dentry->d_inode) { |
2940 | spin_unlock(&dentry->d_lock); |
2941 | continue; |
2942 | } |
2943 | if (!list_empty(&dentry->d_subdirs)) { |
2944 | spin_unlock(&this_parent->d_lock); |
2945 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
2946 | this_parent = dentry; |
2947 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
2948 | goto repeat; |
2949 | } |
2950 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
2951 | dentry->d_flags |= DCACHE_GENOCIDE; |
2952 | dentry->d_count--; |
2953 | } |
2954 | spin_unlock(&dentry->d_lock); |
2955 | } |
2956 | if (this_parent != root) { |
2957 | struct dentry *child = this_parent; |
2958 | if (!(this_parent->d_flags & DCACHE_GENOCIDE)) { |
2959 | this_parent->d_flags |= DCACHE_GENOCIDE; |
2960 | this_parent->d_count--; |
2961 | } |
2962 | this_parent = try_to_ascend(this_parent, locked, seq); |
2963 | if (!this_parent) |
2964 | goto rename_retry; |
2965 | next = child->d_u.d_child.next; |
2966 | goto resume; |
2967 | } |
2968 | spin_unlock(&this_parent->d_lock); |
2969 | if (!locked && read_seqretry(&rename_lock, seq)) |
2970 | goto rename_retry; |
2971 | if (locked) |
2972 | write_sequnlock(&rename_lock); |
2973 | return; |
2974 | |
2975 | rename_retry: |
2976 | if (locked) |
2977 | goto again; |
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 (!IS_ERR_OR_NULL(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 | unsigned 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 hlist_bl_head), |
3035 | dhash_entries, |
3036 | 13, |
3037 | HASH_EARLY, |
3038 | &d_hash_shift, |
3039 | &d_hash_mask, |
3040 | 0, |
3041 | 0); |
3042 | |
3043 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
3044 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
3045 | } |
3046 | |
3047 | static void __init dcache_init(void) |
3048 | { |
3049 | unsigned int loop; |
3050 | |
3051 | /* |
3052 | * A constructor could be added for stable state like the lists, |
3053 | * but it is probably not worth it because of the cache nature |
3054 | * of the dcache. |
3055 | */ |
3056 | dentry_cache = KMEM_CACHE(dentry, |
3057 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
3058 | |
3059 | /* Hash may have been set up in dcache_init_early */ |
3060 | if (!hashdist) |
3061 | return; |
3062 | |
3063 | dentry_hashtable = |
3064 | alloc_large_system_hash("Dentry cache", |
3065 | sizeof(struct hlist_bl_head), |
3066 | dhash_entries, |
3067 | 13, |
3068 | 0, |
3069 | &d_hash_shift, |
3070 | &d_hash_mask, |
3071 | 0, |
3072 | 0); |
3073 | |
3074 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
3075 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
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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javiroman/ks7010
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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