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Source at commit 2604e7f9a98c27be50a0c3ff7503b6a5ea8f6cfe created 12 years 7 months ago. By Maarten ter Huurne, cpufreq_stats: Support runtime changes to frequency table | |
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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 | * d_clear_need_lookup - drop a dentry from cache and clear the need lookup flag |
459 | * @dentry: dentry to drop |
460 | * |
461 | * This is called when we do a lookup on a placeholder dentry that needed to be |
462 | * looked up. The dentry should have been hashed in order for it to be found by |
463 | * the lookup code, but now needs to be unhashed while we do the actual lookup |
464 | * and clear the DCACHE_NEED_LOOKUP flag. |
465 | */ |
466 | void d_clear_need_lookup(struct dentry *dentry) |
467 | { |
468 | spin_lock(&dentry->d_lock); |
469 | __d_drop(dentry); |
470 | dentry->d_flags &= ~DCACHE_NEED_LOOKUP; |
471 | spin_unlock(&dentry->d_lock); |
472 | } |
473 | EXPORT_SYMBOL(d_clear_need_lookup); |
474 | |
475 | /* |
476 | * Finish off a dentry we've decided to kill. |
477 | * dentry->d_lock must be held, returns with it unlocked. |
478 | * If ref is non-zero, then decrement the refcount too. |
479 | * Returns dentry requiring refcount drop, or NULL if we're done. |
480 | */ |
481 | static inline struct dentry *dentry_kill(struct dentry *dentry, int ref) |
482 | __releases(dentry->d_lock) |
483 | { |
484 | struct inode *inode; |
485 | struct dentry *parent; |
486 | |
487 | inode = dentry->d_inode; |
488 | if (inode && !spin_trylock(&inode->i_lock)) { |
489 | relock: |
490 | spin_unlock(&dentry->d_lock); |
491 | cpu_relax(); |
492 | return dentry; /* try again with same dentry */ |
493 | } |
494 | if (IS_ROOT(dentry)) |
495 | parent = NULL; |
496 | else |
497 | parent = dentry->d_parent; |
498 | if (parent && !spin_trylock(&parent->d_lock)) { |
499 | if (inode) |
500 | spin_unlock(&inode->i_lock); |
501 | goto relock; |
502 | } |
503 | |
504 | if (ref) |
505 | dentry->d_count--; |
506 | /* |
507 | * if dentry was on the d_lru list delete it from there. |
508 | * inform the fs via d_prune that this dentry is about to be |
509 | * unhashed and destroyed. |
510 | */ |
511 | dentry_lru_prune(dentry); |
512 | /* if it was on the hash then remove it */ |
513 | __d_drop(dentry); |
514 | return d_kill(dentry, parent); |
515 | } |
516 | |
517 | /* |
518 | * This is dput |
519 | * |
520 | * This is complicated by the fact that we do not want to put |
521 | * dentries that are no longer on any hash chain on the unused |
522 | * list: we'd much rather just get rid of them immediately. |
523 | * |
524 | * However, that implies that we have to traverse the dentry |
525 | * tree upwards to the parents which might _also_ now be |
526 | * scheduled for deletion (it may have been only waiting for |
527 | * its last child to go away). |
528 | * |
529 | * This tail recursion is done by hand as we don't want to depend |
530 | * on the compiler to always get this right (gcc generally doesn't). |
531 | * Real recursion would eat up our stack space. |
532 | */ |
533 | |
534 | /* |
535 | * dput - release a dentry |
536 | * @dentry: dentry to release |
537 | * |
538 | * Release a dentry. This will drop the usage count and if appropriate |
539 | * call the dentry unlink method as well as removing it from the queues and |
540 | * releasing its resources. If the parent dentries were scheduled for release |
541 | * they too may now get deleted. |
542 | */ |
543 | void dput(struct dentry *dentry) |
544 | { |
545 | if (!dentry) |
546 | return; |
547 | |
548 | repeat: |
549 | if (dentry->d_count == 1) |
550 | might_sleep(); |
551 | spin_lock(&dentry->d_lock); |
552 | BUG_ON(!dentry->d_count); |
553 | if (dentry->d_count > 1) { |
554 | dentry->d_count--; |
555 | spin_unlock(&dentry->d_lock); |
556 | return; |
557 | } |
558 | |
559 | if (dentry->d_flags & DCACHE_OP_DELETE) { |
560 | if (dentry->d_op->d_delete(dentry)) |
561 | goto kill_it; |
562 | } |
563 | |
564 | /* Unreachable? Get rid of it */ |
565 | if (d_unhashed(dentry)) |
566 | goto kill_it; |
567 | |
568 | /* |
569 | * If this dentry needs lookup, don't set the referenced flag so that it |
570 | * is more likely to be cleaned up by the dcache shrinker in case of |
571 | * memory pressure. |
572 | */ |
573 | if (!d_need_lookup(dentry)) |
574 | dentry->d_flags |= DCACHE_REFERENCED; |
575 | dentry_lru_add(dentry); |
576 | |
577 | dentry->d_count--; |
578 | spin_unlock(&dentry->d_lock); |
579 | return; |
580 | |
581 | kill_it: |
582 | dentry = dentry_kill(dentry, 1); |
583 | if (dentry) |
584 | goto repeat; |
585 | } |
586 | EXPORT_SYMBOL(dput); |
587 | |
588 | /** |
589 | * d_invalidate - invalidate a dentry |
590 | * @dentry: dentry to invalidate |
591 | * |
592 | * Try to invalidate the dentry if it turns out to be |
593 | * possible. If there are other dentries that can be |
594 | * reached through this one we can't delete it and we |
595 | * return -EBUSY. On success we return 0. |
596 | * |
597 | * no dcache lock. |
598 | */ |
599 | |
600 | int d_invalidate(struct dentry * dentry) |
601 | { |
602 | /* |
603 | * If it's already been dropped, return OK. |
604 | */ |
605 | spin_lock(&dentry->d_lock); |
606 | if (d_unhashed(dentry)) { |
607 | spin_unlock(&dentry->d_lock); |
608 | return 0; |
609 | } |
610 | /* |
611 | * Check whether to do a partial shrink_dcache |
612 | * to get rid of unused child entries. |
613 | */ |
614 | if (!list_empty(&dentry->d_subdirs)) { |
615 | spin_unlock(&dentry->d_lock); |
616 | shrink_dcache_parent(dentry); |
617 | spin_lock(&dentry->d_lock); |
618 | } |
619 | |
620 | /* |
621 | * Somebody else still using it? |
622 | * |
623 | * If it's a directory, we can't drop it |
624 | * for fear of somebody re-populating it |
625 | * with children (even though dropping it |
626 | * would make it unreachable from the root, |
627 | * we might still populate it if it was a |
628 | * working directory or similar). |
629 | * We also need to leave mountpoints alone, |
630 | * directory or not. |
631 | */ |
632 | if (dentry->d_count > 1 && dentry->d_inode) { |
633 | if (S_ISDIR(dentry->d_inode->i_mode) || d_mountpoint(dentry)) { |
634 | spin_unlock(&dentry->d_lock); |
635 | return -EBUSY; |
636 | } |
637 | } |
638 | |
639 | __d_drop(dentry); |
640 | spin_unlock(&dentry->d_lock); |
641 | return 0; |
642 | } |
643 | EXPORT_SYMBOL(d_invalidate); |
644 | |
645 | /* This must be called with d_lock held */ |
646 | static inline void __dget_dlock(struct dentry *dentry) |
647 | { |
648 | dentry->d_count++; |
649 | } |
650 | |
651 | static inline void __dget(struct dentry *dentry) |
652 | { |
653 | spin_lock(&dentry->d_lock); |
654 | __dget_dlock(dentry); |
655 | spin_unlock(&dentry->d_lock); |
656 | } |
657 | |
658 | struct dentry *dget_parent(struct dentry *dentry) |
659 | { |
660 | struct dentry *ret; |
661 | |
662 | repeat: |
663 | /* |
664 | * Don't need rcu_dereference because we re-check it was correct under |
665 | * the lock. |
666 | */ |
667 | rcu_read_lock(); |
668 | ret = dentry->d_parent; |
669 | spin_lock(&ret->d_lock); |
670 | if (unlikely(ret != dentry->d_parent)) { |
671 | spin_unlock(&ret->d_lock); |
672 | rcu_read_unlock(); |
673 | goto repeat; |
674 | } |
675 | rcu_read_unlock(); |
676 | BUG_ON(!ret->d_count); |
677 | ret->d_count++; |
678 | spin_unlock(&ret->d_lock); |
679 | return ret; |
680 | } |
681 | EXPORT_SYMBOL(dget_parent); |
682 | |
683 | /** |
684 | * d_find_alias - grab a hashed alias of inode |
685 | * @inode: inode in question |
686 | * @want_discon: flag, used by d_splice_alias, to request |
687 | * that only a DISCONNECTED alias be returned. |
688 | * |
689 | * If inode has a hashed alias, or is a directory and has any alias, |
690 | * acquire the reference to alias and return it. Otherwise return NULL. |
691 | * Notice that if inode is a directory there can be only one alias and |
692 | * it can be unhashed only if it has no children, or if it is the root |
693 | * of a filesystem. |
694 | * |
695 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
696 | * any other hashed alias over that one unless @want_discon is set, |
697 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
698 | */ |
699 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
700 | { |
701 | struct dentry *alias, *discon_alias; |
702 | struct hlist_node *p; |
703 | |
704 | again: |
705 | discon_alias = NULL; |
706 | hlist_for_each_entry(alias, p, &inode->i_dentry, d_alias) { |
707 | spin_lock(&alias->d_lock); |
708 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
709 | if (IS_ROOT(alias) && |
710 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
711 | discon_alias = alias; |
712 | } else if (!want_discon) { |
713 | __dget_dlock(alias); |
714 | spin_unlock(&alias->d_lock); |
715 | return alias; |
716 | } |
717 | } |
718 | spin_unlock(&alias->d_lock); |
719 | } |
720 | if (discon_alias) { |
721 | alias = discon_alias; |
722 | spin_lock(&alias->d_lock); |
723 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
724 | if (IS_ROOT(alias) && |
725 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
726 | __dget_dlock(alias); |
727 | spin_unlock(&alias->d_lock); |
728 | return alias; |
729 | } |
730 | } |
731 | spin_unlock(&alias->d_lock); |
732 | goto again; |
733 | } |
734 | return NULL; |
735 | } |
736 | |
737 | struct dentry *d_find_alias(struct inode *inode) |
738 | { |
739 | struct dentry *de = NULL; |
740 | |
741 | if (!hlist_empty(&inode->i_dentry)) { |
742 | spin_lock(&inode->i_lock); |
743 | de = __d_find_alias(inode, 0); |
744 | spin_unlock(&inode->i_lock); |
745 | } |
746 | return de; |
747 | } |
748 | EXPORT_SYMBOL(d_find_alias); |
749 | |
750 | /* |
751 | * Try to kill dentries associated with this inode. |
752 | * WARNING: you must own a reference to inode. |
753 | */ |
754 | void d_prune_aliases(struct inode *inode) |
755 | { |
756 | struct dentry *dentry; |
757 | struct hlist_node *p; |
758 | restart: |
759 | spin_lock(&inode->i_lock); |
760 | hlist_for_each_entry(dentry, p, &inode->i_dentry, d_alias) { |
761 | spin_lock(&dentry->d_lock); |
762 | if (!dentry->d_count) { |
763 | __dget_dlock(dentry); |
764 | __d_drop(dentry); |
765 | spin_unlock(&dentry->d_lock); |
766 | spin_unlock(&inode->i_lock); |
767 | dput(dentry); |
768 | goto restart; |
769 | } |
770 | spin_unlock(&dentry->d_lock); |
771 | } |
772 | spin_unlock(&inode->i_lock); |
773 | } |
774 | EXPORT_SYMBOL(d_prune_aliases); |
775 | |
776 | /* |
777 | * Try to throw away a dentry - free the inode, dput the parent. |
778 | * Requires dentry->d_lock is held, and dentry->d_count == 0. |
779 | * Releases dentry->d_lock. |
780 | * |
781 | * This may fail if locks cannot be acquired no problem, just try again. |
782 | */ |
783 | static void try_prune_one_dentry(struct dentry *dentry) |
784 | __releases(dentry->d_lock) |
785 | { |
786 | struct dentry *parent; |
787 | |
788 | parent = dentry_kill(dentry, 0); |
789 | /* |
790 | * If dentry_kill returns NULL, we have nothing more to do. |
791 | * if it returns the same dentry, trylocks failed. In either |
792 | * case, just loop again. |
793 | * |
794 | * Otherwise, we need to prune ancestors too. This is necessary |
795 | * to prevent quadratic behavior of shrink_dcache_parent(), but |
796 | * is also expected to be beneficial in reducing dentry cache |
797 | * fragmentation. |
798 | */ |
799 | if (!parent) |
800 | return; |
801 | if (parent == dentry) |
802 | return; |
803 | |
804 | /* Prune ancestors. */ |
805 | dentry = parent; |
806 | while (dentry) { |
807 | spin_lock(&dentry->d_lock); |
808 | if (dentry->d_count > 1) { |
809 | dentry->d_count--; |
810 | spin_unlock(&dentry->d_lock); |
811 | return; |
812 | } |
813 | dentry = dentry_kill(dentry, 1); |
814 | } |
815 | } |
816 | |
817 | static void shrink_dentry_list(struct list_head *list) |
818 | { |
819 | struct dentry *dentry; |
820 | |
821 | rcu_read_lock(); |
822 | for (;;) { |
823 | dentry = list_entry_rcu(list->prev, struct dentry, d_lru); |
824 | if (&dentry->d_lru == list) |
825 | break; /* empty */ |
826 | spin_lock(&dentry->d_lock); |
827 | if (dentry != list_entry(list->prev, struct dentry, d_lru)) { |
828 | spin_unlock(&dentry->d_lock); |
829 | continue; |
830 | } |
831 | |
832 | /* |
833 | * We found an inuse dentry which was not removed from |
834 | * the LRU because of laziness during lookup. Do not free |
835 | * it - just keep it off the LRU list. |
836 | */ |
837 | if (dentry->d_count) { |
838 | dentry_lru_del(dentry); |
839 | spin_unlock(&dentry->d_lock); |
840 | continue; |
841 | } |
842 | |
843 | rcu_read_unlock(); |
844 | |
845 | try_prune_one_dentry(dentry); |
846 | |
847 | rcu_read_lock(); |
848 | } |
849 | rcu_read_unlock(); |
850 | } |
851 | |
852 | /** |
853 | * prune_dcache_sb - shrink the dcache |
854 | * @sb: superblock |
855 | * @count: number of entries to try to free |
856 | * |
857 | * Attempt to shrink the superblock dcache LRU by @count entries. This is |
858 | * done when we need more memory an called from the superblock shrinker |
859 | * function. |
860 | * |
861 | * This function may fail to free any resources if all the dentries are in |
862 | * use. |
863 | */ |
864 | void prune_dcache_sb(struct super_block *sb, int count) |
865 | { |
866 | struct dentry *dentry; |
867 | LIST_HEAD(referenced); |
868 | LIST_HEAD(tmp); |
869 | |
870 | relock: |
871 | spin_lock(&dcache_lru_lock); |
872 | while (!list_empty(&sb->s_dentry_lru)) { |
873 | dentry = list_entry(sb->s_dentry_lru.prev, |
874 | struct dentry, d_lru); |
875 | BUG_ON(dentry->d_sb != sb); |
876 | |
877 | if (!spin_trylock(&dentry->d_lock)) { |
878 | spin_unlock(&dcache_lru_lock); |
879 | cpu_relax(); |
880 | goto relock; |
881 | } |
882 | |
883 | if (dentry->d_flags & DCACHE_REFERENCED) { |
884 | dentry->d_flags &= ~DCACHE_REFERENCED; |
885 | list_move(&dentry->d_lru, &referenced); |
886 | spin_unlock(&dentry->d_lock); |
887 | } else { |
888 | list_move_tail(&dentry->d_lru, &tmp); |
889 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
890 | spin_unlock(&dentry->d_lock); |
891 | if (!--count) |
892 | break; |
893 | } |
894 | cond_resched_lock(&dcache_lru_lock); |
895 | } |
896 | if (!list_empty(&referenced)) |
897 | list_splice(&referenced, &sb->s_dentry_lru); |
898 | spin_unlock(&dcache_lru_lock); |
899 | |
900 | shrink_dentry_list(&tmp); |
901 | } |
902 | |
903 | /** |
904 | * shrink_dcache_sb - shrink dcache for a superblock |
905 | * @sb: superblock |
906 | * |
907 | * Shrink the dcache for the specified super block. This is used to free |
908 | * the dcache before unmounting a file system. |
909 | */ |
910 | void shrink_dcache_sb(struct super_block *sb) |
911 | { |
912 | LIST_HEAD(tmp); |
913 | |
914 | spin_lock(&dcache_lru_lock); |
915 | while (!list_empty(&sb->s_dentry_lru)) { |
916 | list_splice_init(&sb->s_dentry_lru, &tmp); |
917 | spin_unlock(&dcache_lru_lock); |
918 | shrink_dentry_list(&tmp); |
919 | spin_lock(&dcache_lru_lock); |
920 | } |
921 | spin_unlock(&dcache_lru_lock); |
922 | } |
923 | EXPORT_SYMBOL(shrink_dcache_sb); |
924 | |
925 | /* |
926 | * destroy a single subtree of dentries for unmount |
927 | * - see the comments on shrink_dcache_for_umount() for a description of the |
928 | * locking |
929 | */ |
930 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) |
931 | { |
932 | struct dentry *parent; |
933 | |
934 | BUG_ON(!IS_ROOT(dentry)); |
935 | |
936 | for (;;) { |
937 | /* descend to the first leaf in the current subtree */ |
938 | while (!list_empty(&dentry->d_subdirs)) |
939 | dentry = list_entry(dentry->d_subdirs.next, |
940 | struct dentry, d_u.d_child); |
941 | |
942 | /* consume the dentries from this leaf up through its parents |
943 | * until we find one with children or run out altogether */ |
944 | do { |
945 | struct inode *inode; |
946 | |
947 | /* |
948 | * remove the dentry from the lru, and inform |
949 | * the fs that this dentry is about to be |
950 | * unhashed and destroyed. |
951 | */ |
952 | dentry_lru_prune(dentry); |
953 | __d_shrink(dentry); |
954 | |
955 | if (dentry->d_count != 0) { |
956 | printk(KERN_ERR |
957 | "BUG: Dentry %p{i=%lx,n=%s}" |
958 | " still in use (%d)" |
959 | " [unmount of %s %s]\n", |
960 | dentry, |
961 | dentry->d_inode ? |
962 | dentry->d_inode->i_ino : 0UL, |
963 | dentry->d_name.name, |
964 | dentry->d_count, |
965 | dentry->d_sb->s_type->name, |
966 | dentry->d_sb->s_id); |
967 | BUG(); |
968 | } |
969 | |
970 | if (IS_ROOT(dentry)) { |
971 | parent = NULL; |
972 | list_del(&dentry->d_u.d_child); |
973 | } else { |
974 | parent = dentry->d_parent; |
975 | parent->d_count--; |
976 | list_del(&dentry->d_u.d_child); |
977 | } |
978 | |
979 | inode = dentry->d_inode; |
980 | if (inode) { |
981 | dentry->d_inode = NULL; |
982 | hlist_del_init(&dentry->d_alias); |
983 | if (dentry->d_op && dentry->d_op->d_iput) |
984 | dentry->d_op->d_iput(dentry, inode); |
985 | else |
986 | iput(inode); |
987 | } |
988 | |
989 | d_free(dentry); |
990 | |
991 | /* finished when we fall off the top of the tree, |
992 | * otherwise we ascend to the parent and move to the |
993 | * next sibling if there is one */ |
994 | if (!parent) |
995 | return; |
996 | dentry = parent; |
997 | } while (list_empty(&dentry->d_subdirs)); |
998 | |
999 | dentry = list_entry(dentry->d_subdirs.next, |
1000 | struct dentry, d_u.d_child); |
1001 | } |
1002 | } |
1003 | |
1004 | /* |
1005 | * destroy the dentries attached to a superblock on unmounting |
1006 | * - we don't need to use dentry->d_lock because: |
1007 | * - the superblock is detached from all mountings and open files, so the |
1008 | * dentry trees will not be rearranged by the VFS |
1009 | * - s_umount is write-locked, so the memory pressure shrinker will ignore |
1010 | * any dentries belonging to this superblock that it comes across |
1011 | * - the filesystem itself is no longer permitted to rearrange the dentries |
1012 | * in this superblock |
1013 | */ |
1014 | void shrink_dcache_for_umount(struct super_block *sb) |
1015 | { |
1016 | struct dentry *dentry; |
1017 | |
1018 | if (down_read_trylock(&sb->s_umount)) |
1019 | BUG(); |
1020 | |
1021 | dentry = sb->s_root; |
1022 | sb->s_root = NULL; |
1023 | dentry->d_count--; |
1024 | shrink_dcache_for_umount_subtree(dentry); |
1025 | |
1026 | while (!hlist_bl_empty(&sb->s_anon)) { |
1027 | dentry = hlist_bl_entry(hlist_bl_first(&sb->s_anon), struct dentry, d_hash); |
1028 | shrink_dcache_for_umount_subtree(dentry); |
1029 | } |
1030 | } |
1031 | |
1032 | /* |
1033 | * This tries to ascend one level of parenthood, but |
1034 | * we can race with renaming, so we need to re-check |
1035 | * the parenthood after dropping the lock and check |
1036 | * that the sequence number still matches. |
1037 | */ |
1038 | static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq) |
1039 | { |
1040 | struct dentry *new = old->d_parent; |
1041 | |
1042 | rcu_read_lock(); |
1043 | spin_unlock(&old->d_lock); |
1044 | spin_lock(&new->d_lock); |
1045 | |
1046 | /* |
1047 | * might go back up the wrong parent if we have had a rename |
1048 | * or deletion |
1049 | */ |
1050 | if (new != old->d_parent || |
1051 | (old->d_flags & DCACHE_DENTRY_KILLED) || |
1052 | (!locked && read_seqretry(&rename_lock, seq))) { |
1053 | spin_unlock(&new->d_lock); |
1054 | new = NULL; |
1055 | } |
1056 | rcu_read_unlock(); |
1057 | return new; |
1058 | } |
1059 | |
1060 | |
1061 | /* |
1062 | * Search for at least 1 mount point in the dentry's subdirs. |
1063 | * We descend to the next level whenever the d_subdirs |
1064 | * list is non-empty and continue searching. |
1065 | */ |
1066 | |
1067 | /** |
1068 | * have_submounts - check for mounts over a dentry |
1069 | * @parent: dentry to check. |
1070 | * |
1071 | * Return true if the parent or its subdirectories contain |
1072 | * a mount point |
1073 | */ |
1074 | int have_submounts(struct dentry *parent) |
1075 | { |
1076 | struct dentry *this_parent; |
1077 | struct list_head *next; |
1078 | unsigned seq; |
1079 | int locked = 0; |
1080 | |
1081 | seq = read_seqbegin(&rename_lock); |
1082 | again: |
1083 | this_parent = parent; |
1084 | |
1085 | if (d_mountpoint(parent)) |
1086 | goto positive; |
1087 | spin_lock(&this_parent->d_lock); |
1088 | repeat: |
1089 | next = this_parent->d_subdirs.next; |
1090 | resume: |
1091 | while (next != &this_parent->d_subdirs) { |
1092 | struct list_head *tmp = next; |
1093 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1094 | next = tmp->next; |
1095 | |
1096 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1097 | /* Have we found a mount point ? */ |
1098 | if (d_mountpoint(dentry)) { |
1099 | spin_unlock(&dentry->d_lock); |
1100 | spin_unlock(&this_parent->d_lock); |
1101 | goto positive; |
1102 | } |
1103 | if (!list_empty(&dentry->d_subdirs)) { |
1104 | spin_unlock(&this_parent->d_lock); |
1105 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
1106 | this_parent = dentry; |
1107 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1108 | goto repeat; |
1109 | } |
1110 | spin_unlock(&dentry->d_lock); |
1111 | } |
1112 | /* |
1113 | * All done at this level ... ascend and resume the search. |
1114 | */ |
1115 | if (this_parent != parent) { |
1116 | struct dentry *child = this_parent; |
1117 | this_parent = try_to_ascend(this_parent, locked, seq); |
1118 | if (!this_parent) |
1119 | goto rename_retry; |
1120 | next = child->d_u.d_child.next; |
1121 | goto resume; |
1122 | } |
1123 | spin_unlock(&this_parent->d_lock); |
1124 | if (!locked && read_seqretry(&rename_lock, seq)) |
1125 | goto rename_retry; |
1126 | if (locked) |
1127 | write_sequnlock(&rename_lock); |
1128 | return 0; /* No mount points found in tree */ |
1129 | positive: |
1130 | if (!locked && read_seqretry(&rename_lock, seq)) |
1131 | goto rename_retry; |
1132 | if (locked) |
1133 | write_sequnlock(&rename_lock); |
1134 | return 1; |
1135 | |
1136 | rename_retry: |
1137 | if (locked) |
1138 | goto again; |
1139 | locked = 1; |
1140 | write_seqlock(&rename_lock); |
1141 | goto again; |
1142 | } |
1143 | EXPORT_SYMBOL(have_submounts); |
1144 | |
1145 | /* |
1146 | * Search the dentry child list of the specified parent, |
1147 | * and move any unused dentries to the end of the unused |
1148 | * list for prune_dcache(). We descend to the next level |
1149 | * whenever the d_subdirs list is non-empty and continue |
1150 | * searching. |
1151 | * |
1152 | * It returns zero iff there are no unused children, |
1153 | * otherwise it returns the number of children moved to |
1154 | * the end of the unused list. This may not be the total |
1155 | * number of unused children, because select_parent can |
1156 | * drop the lock and return early due to latency |
1157 | * constraints. |
1158 | */ |
1159 | static int select_parent(struct dentry *parent, struct list_head *dispose) |
1160 | { |
1161 | struct dentry *this_parent; |
1162 | struct list_head *next; |
1163 | unsigned seq; |
1164 | int found = 0; |
1165 | int locked = 0; |
1166 | |
1167 | seq = read_seqbegin(&rename_lock); |
1168 | again: |
1169 | this_parent = parent; |
1170 | spin_lock(&this_parent->d_lock); |
1171 | repeat: |
1172 | next = this_parent->d_subdirs.next; |
1173 | resume: |
1174 | while (next != &this_parent->d_subdirs) { |
1175 | struct list_head *tmp = next; |
1176 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1177 | next = tmp->next; |
1178 | |
1179 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1180 | |
1181 | /* |
1182 | * move only zero ref count dentries to the dispose list. |
1183 | * |
1184 | * Those which are presently on the shrink list, being processed |
1185 | * by shrink_dentry_list(), shouldn't be moved. Otherwise the |
1186 | * loop in shrink_dcache_parent() might not make any progress |
1187 | * and loop forever. |
1188 | */ |
1189 | if (dentry->d_count) { |
1190 | dentry_lru_del(dentry); |
1191 | } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) { |
1192 | dentry_lru_move_list(dentry, dispose); |
1193 | dentry->d_flags |= DCACHE_SHRINK_LIST; |
1194 | found++; |
1195 | } |
1196 | /* |
1197 | * We can return to the caller if we have found some (this |
1198 | * ensures forward progress). We'll be coming back to find |
1199 | * the rest. |
1200 | */ |
1201 | if (found && need_resched()) { |
1202 | spin_unlock(&dentry->d_lock); |
1203 | goto out; |
1204 | } |
1205 | |
1206 | /* |
1207 | * Descend a level if the d_subdirs list is non-empty. |
1208 | */ |
1209 | if (!list_empty(&dentry->d_subdirs)) { |
1210 | spin_unlock(&this_parent->d_lock); |
1211 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
1212 | this_parent = dentry; |
1213 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1214 | goto repeat; |
1215 | } |
1216 | |
1217 | spin_unlock(&dentry->d_lock); |
1218 | } |
1219 | /* |
1220 | * All done at this level ... ascend and resume the search. |
1221 | */ |
1222 | if (this_parent != parent) { |
1223 | struct dentry *child = this_parent; |
1224 | this_parent = try_to_ascend(this_parent, locked, seq); |
1225 | if (!this_parent) |
1226 | goto rename_retry; |
1227 | next = child->d_u.d_child.next; |
1228 | goto resume; |
1229 | } |
1230 | out: |
1231 | spin_unlock(&this_parent->d_lock); |
1232 | if (!locked && read_seqretry(&rename_lock, seq)) |
1233 | goto rename_retry; |
1234 | if (locked) |
1235 | write_sequnlock(&rename_lock); |
1236 | return found; |
1237 | |
1238 | rename_retry: |
1239 | if (found) |
1240 | return found; |
1241 | if (locked) |
1242 | goto again; |
1243 | locked = 1; |
1244 | write_seqlock(&rename_lock); |
1245 | goto again; |
1246 | } |
1247 | |
1248 | /** |
1249 | * shrink_dcache_parent - prune dcache |
1250 | * @parent: parent of entries to prune |
1251 | * |
1252 | * Prune the dcache to remove unused children of the parent dentry. |
1253 | */ |
1254 | void shrink_dcache_parent(struct dentry * parent) |
1255 | { |
1256 | LIST_HEAD(dispose); |
1257 | int found; |
1258 | |
1259 | while ((found = select_parent(parent, &dispose)) != 0) |
1260 | shrink_dentry_list(&dispose); |
1261 | } |
1262 | EXPORT_SYMBOL(shrink_dcache_parent); |
1263 | |
1264 | /** |
1265 | * __d_alloc - allocate a dcache entry |
1266 | * @sb: filesystem it will belong to |
1267 | * @name: qstr of the name |
1268 | * |
1269 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
1270 | * available. On a success the dentry is returned. The name passed in is |
1271 | * copied and the copy passed in may be reused after this call. |
1272 | */ |
1273 | |
1274 | struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1275 | { |
1276 | struct dentry *dentry; |
1277 | char *dname; |
1278 | |
1279 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1280 | if (!dentry) |
1281 | return NULL; |
1282 | |
1283 | /* |
1284 | * We guarantee that the inline name is always NUL-terminated. |
1285 | * This way the memcpy() done by the name switching in rename |
1286 | * will still always have a NUL at the end, even if we might |
1287 | * be overwriting an internal NUL character |
1288 | */ |
1289 | dentry->d_iname[DNAME_INLINE_LEN-1] = 0; |
1290 | if (name->len > DNAME_INLINE_LEN-1) { |
1291 | dname = kmalloc(name->len + 1, GFP_KERNEL); |
1292 | if (!dname) { |
1293 | kmem_cache_free(dentry_cache, dentry); |
1294 | return NULL; |
1295 | } |
1296 | } else { |
1297 | dname = dentry->d_iname; |
1298 | } |
1299 | |
1300 | dentry->d_name.len = name->len; |
1301 | dentry->d_name.hash = name->hash; |
1302 | memcpy(dname, name->name, name->len); |
1303 | dname[name->len] = 0; |
1304 | |
1305 | /* Make sure we always see the terminating NUL character */ |
1306 | smp_wmb(); |
1307 | dentry->d_name.name = dname; |
1308 | |
1309 | dentry->d_count = 1; |
1310 | dentry->d_flags = 0; |
1311 | spin_lock_init(&dentry->d_lock); |
1312 | seqcount_init(&dentry->d_seq); |
1313 | dentry->d_inode = NULL; |
1314 | dentry->d_parent = dentry; |
1315 | dentry->d_sb = sb; |
1316 | dentry->d_op = NULL; |
1317 | dentry->d_fsdata = NULL; |
1318 | INIT_HLIST_BL_NODE(&dentry->d_hash); |
1319 | INIT_LIST_HEAD(&dentry->d_lru); |
1320 | INIT_LIST_HEAD(&dentry->d_subdirs); |
1321 | INIT_HLIST_NODE(&dentry->d_alias); |
1322 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1323 | d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1324 | |
1325 | this_cpu_inc(nr_dentry); |
1326 | |
1327 | return dentry; |
1328 | } |
1329 | |
1330 | /** |
1331 | * d_alloc - allocate a dcache entry |
1332 | * @parent: parent of entry to allocate |
1333 | * @name: qstr of the name |
1334 | * |
1335 | * Allocates a dentry. It returns %NULL if there is insufficient memory |
1336 | * available. On a success the dentry is returned. The name passed in is |
1337 | * copied and the copy passed in may be reused after this call. |
1338 | */ |
1339 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) |
1340 | { |
1341 | struct dentry *dentry = __d_alloc(parent->d_sb, name); |
1342 | if (!dentry) |
1343 | return NULL; |
1344 | |
1345 | spin_lock(&parent->d_lock); |
1346 | /* |
1347 | * don't need child lock because it is not subject |
1348 | * to concurrency here |
1349 | */ |
1350 | __dget_dlock(parent); |
1351 | dentry->d_parent = parent; |
1352 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1353 | spin_unlock(&parent->d_lock); |
1354 | |
1355 | return dentry; |
1356 | } |
1357 | EXPORT_SYMBOL(d_alloc); |
1358 | |
1359 | struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) |
1360 | { |
1361 | struct dentry *dentry = __d_alloc(sb, name); |
1362 | if (dentry) |
1363 | dentry->d_flags |= DCACHE_DISCONNECTED; |
1364 | return dentry; |
1365 | } |
1366 | EXPORT_SYMBOL(d_alloc_pseudo); |
1367 | |
1368 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) |
1369 | { |
1370 | struct qstr q; |
1371 | |
1372 | q.name = name; |
1373 | q.len = strlen(name); |
1374 | q.hash = full_name_hash(q.name, q.len); |
1375 | return d_alloc(parent, &q); |
1376 | } |
1377 | EXPORT_SYMBOL(d_alloc_name); |
1378 | |
1379 | void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) |
1380 | { |
1381 | WARN_ON_ONCE(dentry->d_op); |
1382 | WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
1383 | DCACHE_OP_COMPARE | |
1384 | DCACHE_OP_REVALIDATE | |
1385 | DCACHE_OP_DELETE )); |
1386 | dentry->d_op = op; |
1387 | if (!op) |
1388 | return; |
1389 | if (op->d_hash) |
1390 | dentry->d_flags |= DCACHE_OP_HASH; |
1391 | if (op->d_compare) |
1392 | dentry->d_flags |= DCACHE_OP_COMPARE; |
1393 | if (op->d_revalidate) |
1394 | dentry->d_flags |= DCACHE_OP_REVALIDATE; |
1395 | if (op->d_delete) |
1396 | dentry->d_flags |= DCACHE_OP_DELETE; |
1397 | if (op->d_prune) |
1398 | dentry->d_flags |= DCACHE_OP_PRUNE; |
1399 | |
1400 | } |
1401 | EXPORT_SYMBOL(d_set_d_op); |
1402 | |
1403 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) |
1404 | { |
1405 | spin_lock(&dentry->d_lock); |
1406 | if (inode) { |
1407 | if (unlikely(IS_AUTOMOUNT(inode))) |
1408 | dentry->d_flags |= DCACHE_NEED_AUTOMOUNT; |
1409 | hlist_add_head(&dentry->d_alias, &inode->i_dentry); |
1410 | } |
1411 | dentry->d_inode = inode; |
1412 | dentry_rcuwalk_barrier(dentry); |
1413 | spin_unlock(&dentry->d_lock); |
1414 | fsnotify_d_instantiate(dentry, inode); |
1415 | } |
1416 | |
1417 | /** |
1418 | * d_instantiate - fill in inode information for a dentry |
1419 | * @entry: dentry to complete |
1420 | * @inode: inode to attach to this dentry |
1421 | * |
1422 | * Fill in inode information in the entry. |
1423 | * |
1424 | * This turns negative dentries into productive full members |
1425 | * of society. |
1426 | * |
1427 | * NOTE! This assumes that the inode count has been incremented |
1428 | * (or otherwise set) by the caller to indicate that it is now |
1429 | * in use by the dcache. |
1430 | */ |
1431 | |
1432 | void d_instantiate(struct dentry *entry, struct inode * inode) |
1433 | { |
1434 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
1435 | if (inode) |
1436 | spin_lock(&inode->i_lock); |
1437 | __d_instantiate(entry, inode); |
1438 | if (inode) |
1439 | spin_unlock(&inode->i_lock); |
1440 | security_d_instantiate(entry, inode); |
1441 | } |
1442 | EXPORT_SYMBOL(d_instantiate); |
1443 | |
1444 | /** |
1445 | * d_instantiate_unique - instantiate a non-aliased dentry |
1446 | * @entry: dentry to instantiate |
1447 | * @inode: inode to attach to this dentry |
1448 | * |
1449 | * Fill in inode information in the entry. On success, it returns NULL. |
1450 | * If an unhashed alias of "entry" already exists, then we return the |
1451 | * aliased dentry instead and drop one reference to inode. |
1452 | * |
1453 | * Note that in order to avoid conflicts with rename() etc, the caller |
1454 | * had better be holding the parent directory semaphore. |
1455 | * |
1456 | * This also assumes that the inode count has been incremented |
1457 | * (or otherwise set) by the caller to indicate that it is now |
1458 | * in use by the dcache. |
1459 | */ |
1460 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1461 | struct inode *inode) |
1462 | { |
1463 | struct dentry *alias; |
1464 | int len = entry->d_name.len; |
1465 | const char *name = entry->d_name.name; |
1466 | unsigned int hash = entry->d_name.hash; |
1467 | struct hlist_node *p; |
1468 | |
1469 | if (!inode) { |
1470 | __d_instantiate(entry, NULL); |
1471 | return NULL; |
1472 | } |
1473 | |
1474 | hlist_for_each_entry(alias, p, &inode->i_dentry, d_alias) { |
1475 | /* |
1476 | * Don't need alias->d_lock here, because aliases with |
1477 | * d_parent == entry->d_parent are not subject to name or |
1478 | * parent changes, because the parent inode i_mutex is held. |
1479 | */ |
1480 | if (alias->d_name.hash != hash) |
1481 | continue; |
1482 | if (alias->d_parent != entry->d_parent) |
1483 | continue; |
1484 | if (alias->d_name.len != len) |
1485 | continue; |
1486 | if (dentry_cmp(alias, name, len)) |
1487 | continue; |
1488 | __dget(alias); |
1489 | return alias; |
1490 | } |
1491 | |
1492 | __d_instantiate(entry, inode); |
1493 | return NULL; |
1494 | } |
1495 | |
1496 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) |
1497 | { |
1498 | struct dentry *result; |
1499 | |
1500 | BUG_ON(!hlist_unhashed(&entry->d_alias)); |
1501 | |
1502 | if (inode) |
1503 | spin_lock(&inode->i_lock); |
1504 | result = __d_instantiate_unique(entry, inode); |
1505 | if (inode) |
1506 | spin_unlock(&inode->i_lock); |
1507 | |
1508 | if (!result) { |
1509 | security_d_instantiate(entry, inode); |
1510 | return NULL; |
1511 | } |
1512 | |
1513 | BUG_ON(!d_unhashed(result)); |
1514 | iput(inode); |
1515 | return result; |
1516 | } |
1517 | |
1518 | EXPORT_SYMBOL(d_instantiate_unique); |
1519 | |
1520 | struct dentry *d_make_root(struct inode *root_inode) |
1521 | { |
1522 | struct dentry *res = NULL; |
1523 | |
1524 | if (root_inode) { |
1525 | static const struct qstr name = QSTR_INIT("/", 1); |
1526 | |
1527 | res = __d_alloc(root_inode->i_sb, &name); |
1528 | if (res) |
1529 | d_instantiate(res, root_inode); |
1530 | else |
1531 | iput(root_inode); |
1532 | } |
1533 | return res; |
1534 | } |
1535 | EXPORT_SYMBOL(d_make_root); |
1536 | |
1537 | static struct dentry * __d_find_any_alias(struct inode *inode) |
1538 | { |
1539 | struct dentry *alias; |
1540 | |
1541 | if (hlist_empty(&inode->i_dentry)) |
1542 | return NULL; |
1543 | alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias); |
1544 | __dget(alias); |
1545 | return alias; |
1546 | } |
1547 | |
1548 | /** |
1549 | * d_find_any_alias - find any alias for a given inode |
1550 | * @inode: inode to find an alias for |
1551 | * |
1552 | * If any aliases exist for the given inode, take and return a |
1553 | * reference for one of them. If no aliases exist, return %NULL. |
1554 | */ |
1555 | struct dentry *d_find_any_alias(struct inode *inode) |
1556 | { |
1557 | struct dentry *de; |
1558 | |
1559 | spin_lock(&inode->i_lock); |
1560 | de = __d_find_any_alias(inode); |
1561 | spin_unlock(&inode->i_lock); |
1562 | return de; |
1563 | } |
1564 | EXPORT_SYMBOL(d_find_any_alias); |
1565 | |
1566 | /** |
1567 | * d_obtain_alias - find or allocate a dentry for a given inode |
1568 | * @inode: inode to allocate the dentry for |
1569 | * |
1570 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or |
1571 | * similar open by handle operations. The returned dentry may be anonymous, |
1572 | * or may have a full name (if the inode was already in the cache). |
1573 | * |
1574 | * When called on a directory inode, we must ensure that the inode only ever |
1575 | * has one dentry. If a dentry is found, that is returned instead of |
1576 | * allocating a new one. |
1577 | * |
1578 | * On successful return, the reference to the inode has been transferred |
1579 | * to the dentry. In case of an error the reference on the inode is released. |
1580 | * To make it easier to use in export operations a %NULL or IS_ERR inode may |
1581 | * be passed in and will be the error will be propagate to the return value, |
1582 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). |
1583 | */ |
1584 | struct dentry *d_obtain_alias(struct inode *inode) |
1585 | { |
1586 | static const struct qstr anonstring = { .name = "" }; |
1587 | struct dentry *tmp; |
1588 | struct dentry *res; |
1589 | |
1590 | if (!inode) |
1591 | return ERR_PTR(-ESTALE); |
1592 | if (IS_ERR(inode)) |
1593 | return ERR_CAST(inode); |
1594 | |
1595 | res = d_find_any_alias(inode); |
1596 | if (res) |
1597 | goto out_iput; |
1598 | |
1599 | tmp = __d_alloc(inode->i_sb, &anonstring); |
1600 | if (!tmp) { |
1601 | res = ERR_PTR(-ENOMEM); |
1602 | goto out_iput; |
1603 | } |
1604 | |
1605 | spin_lock(&inode->i_lock); |
1606 | res = __d_find_any_alias(inode); |
1607 | if (res) { |
1608 | spin_unlock(&inode->i_lock); |
1609 | dput(tmp); |
1610 | goto out_iput; |
1611 | } |
1612 | |
1613 | /* attach a disconnected dentry */ |
1614 | spin_lock(&tmp->d_lock); |
1615 | tmp->d_inode = inode; |
1616 | tmp->d_flags |= DCACHE_DISCONNECTED; |
1617 | hlist_add_head(&tmp->d_alias, &inode->i_dentry); |
1618 | hlist_bl_lock(&tmp->d_sb->s_anon); |
1619 | hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon); |
1620 | hlist_bl_unlock(&tmp->d_sb->s_anon); |
1621 | spin_unlock(&tmp->d_lock); |
1622 | spin_unlock(&inode->i_lock); |
1623 | security_d_instantiate(tmp, inode); |
1624 | |
1625 | return tmp; |
1626 | |
1627 | out_iput: |
1628 | if (res && !IS_ERR(res)) |
1629 | security_d_instantiate(res, inode); |
1630 | iput(inode); |
1631 | return res; |
1632 | } |
1633 | EXPORT_SYMBOL(d_obtain_alias); |
1634 | |
1635 | /** |
1636 | * d_splice_alias - splice a disconnected dentry into the tree if one exists |
1637 | * @inode: the inode which may have a disconnected dentry |
1638 | * @dentry: a negative dentry which we want to point to the inode. |
1639 | * |
1640 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and |
1641 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry |
1642 | * and return it, else simply d_add the inode to the dentry and return NULL. |
1643 | * |
1644 | * This is needed in the lookup routine of any filesystem that is exportable |
1645 | * (via knfsd) so that we can build dcache paths to directories effectively. |
1646 | * |
1647 | * If a dentry was found and moved, then it is returned. Otherwise NULL |
1648 | * is returned. This matches the expected return value of ->lookup. |
1649 | * |
1650 | */ |
1651 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) |
1652 | { |
1653 | struct dentry *new = NULL; |
1654 | |
1655 | if (IS_ERR(inode)) |
1656 | return ERR_CAST(inode); |
1657 | |
1658 | if (inode && S_ISDIR(inode->i_mode)) { |
1659 | spin_lock(&inode->i_lock); |
1660 | new = __d_find_alias(inode, 1); |
1661 | if (new) { |
1662 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); |
1663 | spin_unlock(&inode->i_lock); |
1664 | security_d_instantiate(new, inode); |
1665 | d_move(new, dentry); |
1666 | iput(inode); |
1667 | } else { |
1668 | /* already taking inode->i_lock, so d_add() by hand */ |
1669 | __d_instantiate(dentry, inode); |
1670 | spin_unlock(&inode->i_lock); |
1671 | security_d_instantiate(dentry, inode); |
1672 | d_rehash(dentry); |
1673 | } |
1674 | } else |
1675 | d_add(dentry, inode); |
1676 | return new; |
1677 | } |
1678 | EXPORT_SYMBOL(d_splice_alias); |
1679 | |
1680 | /** |
1681 | * d_add_ci - lookup or allocate new dentry with case-exact name |
1682 | * @inode: the inode case-insensitive lookup has found |
1683 | * @dentry: the negative dentry that was passed to the parent's lookup func |
1684 | * @name: the case-exact name to be associated with the returned dentry |
1685 | * |
1686 | * This is to avoid filling the dcache with case-insensitive names to the |
1687 | * same inode, only the actual correct case is stored in the dcache for |
1688 | * case-insensitive filesystems. |
1689 | * |
1690 | * For a case-insensitive lookup match and if the the case-exact dentry |
1691 | * already exists in in the dcache, use it and return it. |
1692 | * |
1693 | * If no entry exists with the exact case name, allocate new dentry with |
1694 | * the exact case, and return the spliced entry. |
1695 | */ |
1696 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
1697 | struct qstr *name) |
1698 | { |
1699 | int error; |
1700 | struct dentry *found; |
1701 | struct dentry *new; |
1702 | |
1703 | /* |
1704 | * First check if a dentry matching the name already exists, |
1705 | * if not go ahead and create it now. |
1706 | */ |
1707 | found = d_hash_and_lookup(dentry->d_parent, name); |
1708 | if (!found) { |
1709 | new = d_alloc(dentry->d_parent, name); |
1710 | if (!new) { |
1711 | error = -ENOMEM; |
1712 | goto err_out; |
1713 | } |
1714 | |
1715 | found = d_splice_alias(inode, new); |
1716 | if (found) { |
1717 | dput(new); |
1718 | return found; |
1719 | } |
1720 | return new; |
1721 | } |
1722 | |
1723 | /* |
1724 | * If a matching dentry exists, and it's not negative use it. |
1725 | * |
1726 | * Decrement the reference count to balance the iget() done |
1727 | * earlier on. |
1728 | */ |
1729 | if (found->d_inode) { |
1730 | if (unlikely(found->d_inode != inode)) { |
1731 | /* This can't happen because bad inodes are unhashed. */ |
1732 | BUG_ON(!is_bad_inode(inode)); |
1733 | BUG_ON(!is_bad_inode(found->d_inode)); |
1734 | } |
1735 | iput(inode); |
1736 | return found; |
1737 | } |
1738 | |
1739 | /* |
1740 | * We are going to instantiate this dentry, unhash it and clear the |
1741 | * lookup flag so we can do that. |
1742 | */ |
1743 | if (unlikely(d_need_lookup(found))) |
1744 | d_clear_need_lookup(found); |
1745 | |
1746 | /* |
1747 | * Negative dentry: instantiate it unless the inode is a directory and |
1748 | * already has a dentry. |
1749 | */ |
1750 | new = d_splice_alias(inode, found); |
1751 | if (new) { |
1752 | dput(found); |
1753 | found = new; |
1754 | } |
1755 | return found; |
1756 | |
1757 | err_out: |
1758 | iput(inode); |
1759 | return ERR_PTR(error); |
1760 | } |
1761 | EXPORT_SYMBOL(d_add_ci); |
1762 | |
1763 | /* |
1764 | * Do the slow-case of the dentry name compare. |
1765 | * |
1766 | * Unlike the dentry_cmp() function, we need to atomically |
1767 | * load the name, length and inode information, so that the |
1768 | * filesystem can rely on them, and can use the 'name' and |
1769 | * 'len' information without worrying about walking off the |
1770 | * end of memory etc. |
1771 | * |
1772 | * Thus the read_seqcount_retry() and the "duplicate" info |
1773 | * in arguments (the low-level filesystem should not look |
1774 | * at the dentry inode or name contents directly, since |
1775 | * rename can change them while we're in RCU mode). |
1776 | */ |
1777 | enum slow_d_compare { |
1778 | D_COMP_OK, |
1779 | D_COMP_NOMATCH, |
1780 | D_COMP_SEQRETRY, |
1781 | }; |
1782 | |
1783 | static noinline enum slow_d_compare slow_dentry_cmp( |
1784 | const struct dentry *parent, |
1785 | struct inode *inode, |
1786 | struct dentry *dentry, |
1787 | unsigned int seq, |
1788 | const struct qstr *name) |
1789 | { |
1790 | int tlen = dentry->d_name.len; |
1791 | const char *tname = dentry->d_name.name; |
1792 | struct inode *i = dentry->d_inode; |
1793 | |
1794 | if (read_seqcount_retry(&dentry->d_seq, seq)) { |
1795 | cpu_relax(); |
1796 | return D_COMP_SEQRETRY; |
1797 | } |
1798 | if (parent->d_op->d_compare(parent, inode, |
1799 | dentry, i, |
1800 | tlen, tname, name)) |
1801 | return D_COMP_NOMATCH; |
1802 | return D_COMP_OK; |
1803 | } |
1804 | |
1805 | /** |
1806 | * __d_lookup_rcu - search for a dentry (racy, store-free) |
1807 | * @parent: parent dentry |
1808 | * @name: qstr of name we wish to find |
1809 | * @seqp: returns d_seq value at the point where the dentry was found |
1810 | * @inode: returns dentry->d_inode when the inode was found valid. |
1811 | * Returns: dentry, or NULL |
1812 | * |
1813 | * __d_lookup_rcu is the dcache lookup function for rcu-walk name |
1814 | * resolution (store-free path walking) design described in |
1815 | * Documentation/filesystems/path-lookup.txt. |
1816 | * |
1817 | * This is not to be used outside core vfs. |
1818 | * |
1819 | * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock |
1820 | * held, and rcu_read_lock held. The returned dentry must not be stored into |
1821 | * without taking d_lock and checking d_seq sequence count against @seq |
1822 | * returned here. |
1823 | * |
1824 | * A refcount may be taken on the found dentry with the __d_rcu_to_refcount |
1825 | * function. |
1826 | * |
1827 | * Alternatively, __d_lookup_rcu may be called again to look up the child of |
1828 | * the returned dentry, so long as its parent's seqlock is checked after the |
1829 | * child is looked up. Thus, an interlocking stepping of sequence lock checks |
1830 | * is formed, giving integrity down the path walk. |
1831 | * |
1832 | * NOTE! The caller *has* to check the resulting dentry against the sequence |
1833 | * number we've returned before using any of the resulting dentry state! |
1834 | */ |
1835 | struct dentry *__d_lookup_rcu(const struct dentry *parent, |
1836 | const struct qstr *name, |
1837 | unsigned *seqp, struct inode *inode) |
1838 | { |
1839 | u64 hashlen = name->hash_len; |
1840 | const unsigned char *str = name->name; |
1841 | struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen)); |
1842 | struct hlist_bl_node *node; |
1843 | struct dentry *dentry; |
1844 | |
1845 | /* |
1846 | * Note: There is significant duplication with __d_lookup_rcu which is |
1847 | * required to prevent single threaded performance regressions |
1848 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
1849 | * Keep the two functions in sync. |
1850 | */ |
1851 | |
1852 | /* |
1853 | * The hash list is protected using RCU. |
1854 | * |
1855 | * Carefully use d_seq when comparing a candidate dentry, to avoid |
1856 | * races with d_move(). |
1857 | * |
1858 | * It is possible that concurrent renames can mess up our list |
1859 | * walk here and result in missing our dentry, resulting in the |
1860 | * false-negative result. d_lookup() protects against concurrent |
1861 | * renames using rename_lock seqlock. |
1862 | * |
1863 | * See Documentation/filesystems/path-lookup.txt for more details. |
1864 | */ |
1865 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1866 | unsigned seq; |
1867 | |
1868 | seqretry: |
1869 | /* |
1870 | * The dentry sequence count protects us from concurrent |
1871 | * renames, and thus protects inode, parent and name fields. |
1872 | * |
1873 | * The caller must perform a seqcount check in order |
1874 | * to do anything useful with the returned dentry, |
1875 | * including using the 'd_inode' pointer. |
1876 | * |
1877 | * NOTE! We do a "raw" seqcount_begin here. That means that |
1878 | * we don't wait for the sequence count to stabilize if it |
1879 | * is in the middle of a sequence change. If we do the slow |
1880 | * dentry compare, we will do seqretries until it is stable, |
1881 | * and if we end up with a successful lookup, we actually |
1882 | * want to exit RCU lookup anyway. |
1883 | */ |
1884 | seq = raw_seqcount_begin(&dentry->d_seq); |
1885 | if (dentry->d_parent != parent) |
1886 | continue; |
1887 | if (d_unhashed(dentry)) |
1888 | continue; |
1889 | *seqp = seq; |
1890 | |
1891 | if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
1892 | if (dentry->d_name.hash != hashlen_hash(hashlen)) |
1893 | continue; |
1894 | switch (slow_dentry_cmp(parent, inode, dentry, seq, name)) { |
1895 | case D_COMP_OK: |
1896 | return dentry; |
1897 | case D_COMP_NOMATCH: |
1898 | continue; |
1899 | default: |
1900 | goto seqretry; |
1901 | } |
1902 | } |
1903 | |
1904 | if (dentry->d_name.hash_len != hashlen) |
1905 | continue; |
1906 | if (!dentry_cmp(dentry, str, hashlen_len(hashlen))) |
1907 | return dentry; |
1908 | } |
1909 | return NULL; |
1910 | } |
1911 | |
1912 | /** |
1913 | * d_lookup - search for a dentry |
1914 | * @parent: parent dentry |
1915 | * @name: qstr of name we wish to find |
1916 | * Returns: dentry, or NULL |
1917 | * |
1918 | * d_lookup searches the children of the parent dentry for the name in |
1919 | * question. If the dentry is found its reference count is incremented and the |
1920 | * dentry is returned. The caller must use dput to free the entry when it has |
1921 | * finished using it. %NULL is returned if the dentry does not exist. |
1922 | */ |
1923 | struct dentry *d_lookup(struct dentry *parent, struct qstr *name) |
1924 | { |
1925 | struct dentry *dentry; |
1926 | unsigned seq; |
1927 | |
1928 | do { |
1929 | seq = read_seqbegin(&rename_lock); |
1930 | dentry = __d_lookup(parent, name); |
1931 | if (dentry) |
1932 | break; |
1933 | } while (read_seqretry(&rename_lock, seq)); |
1934 | return dentry; |
1935 | } |
1936 | EXPORT_SYMBOL(d_lookup); |
1937 | |
1938 | /** |
1939 | * __d_lookup - search for a dentry (racy) |
1940 | * @parent: parent dentry |
1941 | * @name: qstr of name we wish to find |
1942 | * Returns: dentry, or NULL |
1943 | * |
1944 | * __d_lookup is like d_lookup, however it may (rarely) return a |
1945 | * false-negative result due to unrelated rename activity. |
1946 | * |
1947 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, |
1948 | * however it must be used carefully, eg. with a following d_lookup in |
1949 | * the case of failure. |
1950 | * |
1951 | * __d_lookup callers must be commented. |
1952 | */ |
1953 | struct dentry *__d_lookup(struct dentry *parent, struct qstr *name) |
1954 | { |
1955 | unsigned int len = name->len; |
1956 | unsigned int hash = name->hash; |
1957 | const unsigned char *str = name->name; |
1958 | struct hlist_bl_head *b = d_hash(parent, hash); |
1959 | struct hlist_bl_node *node; |
1960 | struct dentry *found = NULL; |
1961 | struct dentry *dentry; |
1962 | |
1963 | /* |
1964 | * Note: There is significant duplication with __d_lookup_rcu which is |
1965 | * required to prevent single threaded performance regressions |
1966 | * especially on architectures where smp_rmb (in seqcounts) are costly. |
1967 | * Keep the two functions in sync. |
1968 | */ |
1969 | |
1970 | /* |
1971 | * The hash list is protected using RCU. |
1972 | * |
1973 | * Take d_lock when comparing a candidate dentry, to avoid races |
1974 | * with d_move(). |
1975 | * |
1976 | * It is possible that concurrent renames can mess up our list |
1977 | * walk here and result in missing our dentry, resulting in the |
1978 | * false-negative result. d_lookup() protects against concurrent |
1979 | * renames using rename_lock seqlock. |
1980 | * |
1981 | * See Documentation/filesystems/path-lookup.txt for more details. |
1982 | */ |
1983 | rcu_read_lock(); |
1984 | |
1985 | hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1986 | |
1987 | if (dentry->d_name.hash != hash) |
1988 | continue; |
1989 | |
1990 | spin_lock(&dentry->d_lock); |
1991 | if (dentry->d_parent != parent) |
1992 | goto next; |
1993 | if (d_unhashed(dentry)) |
1994 | goto next; |
1995 | |
1996 | /* |
1997 | * It is safe to compare names since d_move() cannot |
1998 | * change the qstr (protected by d_lock). |
1999 | */ |
2000 | if (parent->d_flags & DCACHE_OP_COMPARE) { |
2001 | int tlen = dentry->d_name.len; |
2002 | const char *tname = dentry->d_name.name; |
2003 | if (parent->d_op->d_compare(parent, parent->d_inode, |
2004 | dentry, dentry->d_inode, |
2005 | tlen, tname, name)) |
2006 | goto next; |
2007 | } else { |
2008 | if (dentry->d_name.len != len) |
2009 | goto next; |
2010 | if (dentry_cmp(dentry, str, len)) |
2011 | goto next; |
2012 | } |
2013 | |
2014 | dentry->d_count++; |
2015 | found = dentry; |
2016 | spin_unlock(&dentry->d_lock); |
2017 | break; |
2018 | next: |
2019 | spin_unlock(&dentry->d_lock); |
2020 | } |
2021 | rcu_read_unlock(); |
2022 | |
2023 | return found; |
2024 | } |
2025 | |
2026 | /** |
2027 | * d_hash_and_lookup - hash the qstr then search for a dentry |
2028 | * @dir: Directory to search in |
2029 | * @name: qstr of name we wish to find |
2030 | * |
2031 | * On hash failure or on lookup failure NULL is returned. |
2032 | */ |
2033 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) |
2034 | { |
2035 | struct dentry *dentry = NULL; |
2036 | |
2037 | /* |
2038 | * Check for a fs-specific hash function. Note that we must |
2039 | * calculate the standard hash first, as the d_op->d_hash() |
2040 | * routine may choose to leave the hash value unchanged. |
2041 | */ |
2042 | name->hash = full_name_hash(name->name, name->len); |
2043 | if (dir->d_flags & DCACHE_OP_HASH) { |
2044 | if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) |
2045 | goto out; |
2046 | } |
2047 | dentry = d_lookup(dir, name); |
2048 | out: |
2049 | return dentry; |
2050 | } |
2051 | |
2052 | /** |
2053 | * d_validate - verify dentry provided from insecure source (deprecated) |
2054 | * @dentry: The dentry alleged to be valid child of @dparent |
2055 | * @dparent: The parent dentry (known to be valid) |
2056 | * |
2057 | * An insecure source has sent us a dentry, here we verify it and dget() it. |
2058 | * This is used by ncpfs in its readdir implementation. |
2059 | * Zero is returned in the dentry is invalid. |
2060 | * |
2061 | * This function is slow for big directories, and deprecated, do not use it. |
2062 | */ |
2063 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
2064 | { |
2065 | struct dentry *child; |
2066 | |
2067 | spin_lock(&dparent->d_lock); |
2068 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
2069 | if (dentry == child) { |
2070 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
2071 | __dget_dlock(dentry); |
2072 | spin_unlock(&dentry->d_lock); |
2073 | spin_unlock(&dparent->d_lock); |
2074 | return 1; |
2075 | } |
2076 | } |
2077 | spin_unlock(&dparent->d_lock); |
2078 | |
2079 | return 0; |
2080 | } |
2081 | EXPORT_SYMBOL(d_validate); |
2082 | |
2083 | /* |
2084 | * When a file is deleted, we have two options: |
2085 | * - turn this dentry into a negative dentry |
2086 | * - unhash this dentry and free it. |
2087 | * |
2088 | * Usually, we want to just turn this into |
2089 | * a negative dentry, but if anybody else is |
2090 | * currently using the dentry or the inode |
2091 | * we can't do that and we fall back on removing |
2092 | * it from the hash queues and waiting for |
2093 | * it to be deleted later when it has no users |
2094 | */ |
2095 | |
2096 | /** |
2097 | * d_delete - delete a dentry |
2098 | * @dentry: The dentry to delete |
2099 | * |
2100 | * Turn the dentry into a negative dentry if possible, otherwise |
2101 | * remove it from the hash queues so it can be deleted later |
2102 | */ |
2103 | |
2104 | void d_delete(struct dentry * dentry) |
2105 | { |
2106 | struct inode *inode; |
2107 | int isdir = 0; |
2108 | /* |
2109 | * Are we the only user? |
2110 | */ |
2111 | again: |
2112 | spin_lock(&dentry->d_lock); |
2113 | inode = dentry->d_inode; |
2114 | isdir = S_ISDIR(inode->i_mode); |
2115 | if (dentry->d_count == 1) { |
2116 | if (inode && !spin_trylock(&inode->i_lock)) { |
2117 | spin_unlock(&dentry->d_lock); |
2118 | cpu_relax(); |
2119 | goto again; |
2120 | } |
2121 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
2122 | dentry_unlink_inode(dentry); |
2123 | fsnotify_nameremove(dentry, isdir); |
2124 | return; |
2125 | } |
2126 | |
2127 | if (!d_unhashed(dentry)) |
2128 | __d_drop(dentry); |
2129 | |
2130 | spin_unlock(&dentry->d_lock); |
2131 | |
2132 | fsnotify_nameremove(dentry, isdir); |
2133 | } |
2134 | EXPORT_SYMBOL(d_delete); |
2135 | |
2136 | static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b) |
2137 | { |
2138 | BUG_ON(!d_unhashed(entry)); |
2139 | hlist_bl_lock(b); |
2140 | entry->d_flags |= DCACHE_RCUACCESS; |
2141 | hlist_bl_add_head_rcu(&entry->d_hash, b); |
2142 | hlist_bl_unlock(b); |
2143 | } |
2144 | |
2145 | static void _d_rehash(struct dentry * entry) |
2146 | { |
2147 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); |
2148 | } |
2149 | |
2150 | /** |
2151 | * d_rehash - add an entry back to the hash |
2152 | * @entry: dentry to add to the hash |
2153 | * |
2154 | * Adds a dentry to the hash according to its name. |
2155 | */ |
2156 | |
2157 | void d_rehash(struct dentry * entry) |
2158 | { |
2159 | spin_lock(&entry->d_lock); |
2160 | _d_rehash(entry); |
2161 | spin_unlock(&entry->d_lock); |
2162 | } |
2163 | EXPORT_SYMBOL(d_rehash); |
2164 | |
2165 | /** |
2166 | * dentry_update_name_case - update case insensitive dentry with a new name |
2167 | * @dentry: dentry to be updated |
2168 | * @name: new name |
2169 | * |
2170 | * Update a case insensitive dentry with new case of name. |
2171 | * |
2172 | * dentry must have been returned by d_lookup with name @name. Old and new |
2173 | * name lengths must match (ie. no d_compare which allows mismatched name |
2174 | * lengths). |
2175 | * |
2176 | * Parent inode i_mutex must be held over d_lookup and into this call (to |
2177 | * keep renames and concurrent inserts, and readdir(2) away). |
2178 | */ |
2179 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) |
2180 | { |
2181 | BUG_ON(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex)); |
2182 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ |
2183 | |
2184 | spin_lock(&dentry->d_lock); |
2185 | write_seqcount_begin(&dentry->d_seq); |
2186 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); |
2187 | write_seqcount_end(&dentry->d_seq); |
2188 | spin_unlock(&dentry->d_lock); |
2189 | } |
2190 | EXPORT_SYMBOL(dentry_update_name_case); |
2191 | |
2192 | static void switch_names(struct dentry *dentry, struct dentry *target) |
2193 | { |
2194 | if (dname_external(target)) { |
2195 | if (dname_external(dentry)) { |
2196 | /* |
2197 | * Both external: swap the pointers |
2198 | */ |
2199 | swap(target->d_name.name, dentry->d_name.name); |
2200 | } else { |
2201 | /* |
2202 | * dentry:internal, target:external. Steal target's |
2203 | * storage and make target internal. |
2204 | */ |
2205 | memcpy(target->d_iname, dentry->d_name.name, |
2206 | dentry->d_name.len + 1); |
2207 | dentry->d_name.name = target->d_name.name; |
2208 | target->d_name.name = target->d_iname; |
2209 | } |
2210 | } else { |
2211 | if (dname_external(dentry)) { |
2212 | /* |
2213 | * dentry:external, target:internal. Give dentry's |
2214 | * storage to target and make dentry internal |
2215 | */ |
2216 | memcpy(dentry->d_iname, target->d_name.name, |
2217 | target->d_name.len + 1); |
2218 | target->d_name.name = dentry->d_name.name; |
2219 | dentry->d_name.name = dentry->d_iname; |
2220 | } else { |
2221 | /* |
2222 | * Both are internal. Just copy target to dentry |
2223 | */ |
2224 | memcpy(dentry->d_iname, target->d_name.name, |
2225 | target->d_name.len + 1); |
2226 | dentry->d_name.len = target->d_name.len; |
2227 | return; |
2228 | } |
2229 | } |
2230 | swap(dentry->d_name.len, target->d_name.len); |
2231 | } |
2232 | |
2233 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
2234 | { |
2235 | /* |
2236 | * XXXX: do we really need to take target->d_lock? |
2237 | */ |
2238 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) |
2239 | spin_lock(&target->d_parent->d_lock); |
2240 | else { |
2241 | if (d_ancestor(dentry->d_parent, target->d_parent)) { |
2242 | spin_lock(&dentry->d_parent->d_lock); |
2243 | spin_lock_nested(&target->d_parent->d_lock, |
2244 | DENTRY_D_LOCK_NESTED); |
2245 | } else { |
2246 | spin_lock(&target->d_parent->d_lock); |
2247 | spin_lock_nested(&dentry->d_parent->d_lock, |
2248 | DENTRY_D_LOCK_NESTED); |
2249 | } |
2250 | } |
2251 | if (target < dentry) { |
2252 | spin_lock_nested(&target->d_lock, 2); |
2253 | spin_lock_nested(&dentry->d_lock, 3); |
2254 | } else { |
2255 | spin_lock_nested(&dentry->d_lock, 2); |
2256 | spin_lock_nested(&target->d_lock, 3); |
2257 | } |
2258 | } |
2259 | |
2260 | static void dentry_unlock_parents_for_move(struct dentry *dentry, |
2261 | struct dentry *target) |
2262 | { |
2263 | if (target->d_parent != dentry->d_parent) |
2264 | spin_unlock(&dentry->d_parent->d_lock); |
2265 | if (target->d_parent != target) |
2266 | spin_unlock(&target->d_parent->d_lock); |
2267 | } |
2268 | |
2269 | /* |
2270 | * When switching names, the actual string doesn't strictly have to |
2271 | * be preserved in the target - because we're dropping the target |
2272 | * anyway. As such, we can just do a simple memcpy() to copy over |
2273 | * the new name before we switch. |
2274 | * |
2275 | * Note that we have to be a lot more careful about getting the hash |
2276 | * switched - we have to switch the hash value properly even if it |
2277 | * then no longer matches the actual (corrupted) string of the target. |
2278 | * The hash value has to match the hash queue that the dentry is on.. |
2279 | */ |
2280 | /* |
2281 | * __d_move - move a dentry |
2282 | * @dentry: entry to move |
2283 | * @target: new dentry |
2284 | * |
2285 | * Update the dcache to reflect the move of a file name. Negative |
2286 | * dcache entries should not be moved in this way. Caller must hold |
2287 | * rename_lock, the i_mutex of the source and target directories, |
2288 | * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). |
2289 | */ |
2290 | static void __d_move(struct dentry * dentry, struct dentry * target) |
2291 | { |
2292 | if (!dentry->d_inode) |
2293 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); |
2294 | |
2295 | BUG_ON(d_ancestor(dentry, target)); |
2296 | BUG_ON(d_ancestor(target, dentry)); |
2297 | |
2298 | dentry_lock_for_move(dentry, target); |
2299 | |
2300 | write_seqcount_begin(&dentry->d_seq); |
2301 | write_seqcount_begin(&target->d_seq); |
2302 | |
2303 | /* __d_drop does write_seqcount_barrier, but they're OK to nest. */ |
2304 | |
2305 | /* |
2306 | * Move the dentry to the target hash queue. Don't bother checking |
2307 | * for the same hash queue because of how unlikely it is. |
2308 | */ |
2309 | __d_drop(dentry); |
2310 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); |
2311 | |
2312 | /* Unhash the target: dput() will then get rid of it */ |
2313 | __d_drop(target); |
2314 | |
2315 | list_del(&dentry->d_u.d_child); |
2316 | list_del(&target->d_u.d_child); |
2317 | |
2318 | /* Switch the names.. */ |
2319 | switch_names(dentry, target); |
2320 | swap(dentry->d_name.hash, target->d_name.hash); |
2321 | |
2322 | /* ... and switch the parents */ |
2323 | if (IS_ROOT(dentry)) { |
2324 | dentry->d_parent = target->d_parent; |
2325 | target->d_parent = target; |
2326 | INIT_LIST_HEAD(&target->d_u.d_child); |
2327 | } else { |
2328 | swap(dentry->d_parent, target->d_parent); |
2329 | |
2330 | /* And add them back to the (new) parent lists */ |
2331 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
2332 | } |
2333 | |
2334 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2335 | |
2336 | write_seqcount_end(&target->d_seq); |
2337 | write_seqcount_end(&dentry->d_seq); |
2338 | |
2339 | dentry_unlock_parents_for_move(dentry, target); |
2340 | spin_unlock(&target->d_lock); |
2341 | fsnotify_d_move(dentry); |
2342 | spin_unlock(&dentry->d_lock); |
2343 | } |
2344 | |
2345 | /* |
2346 | * d_move - move a dentry |
2347 | * @dentry: entry to move |
2348 | * @target: new dentry |
2349 | * |
2350 | * Update the dcache to reflect the move of a file name. Negative |
2351 | * dcache entries should not be moved in this way. See the locking |
2352 | * requirements for __d_move. |
2353 | */ |
2354 | void d_move(struct dentry *dentry, struct dentry *target) |
2355 | { |
2356 | write_seqlock(&rename_lock); |
2357 | __d_move(dentry, target); |
2358 | write_sequnlock(&rename_lock); |
2359 | } |
2360 | EXPORT_SYMBOL(d_move); |
2361 | |
2362 | /** |
2363 | * d_ancestor - search for an ancestor |
2364 | * @p1: ancestor dentry |
2365 | * @p2: child dentry |
2366 | * |
2367 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is |
2368 | * an ancestor of p2, else NULL. |
2369 | */ |
2370 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
2371 | { |
2372 | struct dentry *p; |
2373 | |
2374 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
2375 | if (p->d_parent == p1) |
2376 | return p; |
2377 | } |
2378 | return NULL; |
2379 | } |
2380 | |
2381 | /* |
2382 | * This helper attempts to cope with remotely renamed directories |
2383 | * |
2384 | * It assumes that the caller is already holding |
2385 | * dentry->d_parent->d_inode->i_mutex, inode->i_lock and rename_lock |
2386 | * |
2387 | * Note: If ever the locking in lock_rename() changes, then please |
2388 | * remember to update this too... |
2389 | */ |
2390 | static struct dentry *__d_unalias(struct inode *inode, |
2391 | struct dentry *dentry, struct dentry *alias) |
2392 | { |
2393 | struct mutex *m1 = NULL, *m2 = NULL; |
2394 | struct dentry *ret = ERR_PTR(-EBUSY); |
2395 | |
2396 | /* If alias and dentry share a parent, then no extra locks required */ |
2397 | if (alias->d_parent == dentry->d_parent) |
2398 | goto out_unalias; |
2399 | |
2400 | /* See lock_rename() */ |
2401 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) |
2402 | goto out_err; |
2403 | m1 = &dentry->d_sb->s_vfs_rename_mutex; |
2404 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) |
2405 | goto out_err; |
2406 | m2 = &alias->d_parent->d_inode->i_mutex; |
2407 | out_unalias: |
2408 | if (likely(!d_mountpoint(alias))) { |
2409 | __d_move(alias, dentry); |
2410 | ret = alias; |
2411 | } |
2412 | out_err: |
2413 | spin_unlock(&inode->i_lock); |
2414 | if (m2) |
2415 | mutex_unlock(m2); |
2416 | if (m1) |
2417 | mutex_unlock(m1); |
2418 | return ret; |
2419 | } |
2420 | |
2421 | /* |
2422 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a |
2423 | * named dentry in place of the dentry to be replaced. |
2424 | * returns with anon->d_lock held! |
2425 | */ |
2426 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) |
2427 | { |
2428 | struct dentry *dparent, *aparent; |
2429 | |
2430 | dentry_lock_for_move(anon, dentry); |
2431 | |
2432 | write_seqcount_begin(&dentry->d_seq); |
2433 | write_seqcount_begin(&anon->d_seq); |
2434 | |
2435 | dparent = dentry->d_parent; |
2436 | aparent = anon->d_parent; |
2437 | |
2438 | switch_names(dentry, anon); |
2439 | swap(dentry->d_name.hash, anon->d_name.hash); |
2440 | |
2441 | dentry->d_parent = (aparent == anon) ? dentry : aparent; |
2442 | list_del(&dentry->d_u.d_child); |
2443 | if (!IS_ROOT(dentry)) |
2444 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2445 | else |
2446 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
2447 | |
2448 | anon->d_parent = (dparent == dentry) ? anon : dparent; |
2449 | list_del(&anon->d_u.d_child); |
2450 | if (!IS_ROOT(anon)) |
2451 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); |
2452 | else |
2453 | INIT_LIST_HEAD(&anon->d_u.d_child); |
2454 | |
2455 | write_seqcount_end(&dentry->d_seq); |
2456 | write_seqcount_end(&anon->d_seq); |
2457 | |
2458 | dentry_unlock_parents_for_move(anon, dentry); |
2459 | spin_unlock(&dentry->d_lock); |
2460 | |
2461 | /* anon->d_lock still locked, returns locked */ |
2462 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
2463 | } |
2464 | |
2465 | /** |
2466 | * d_materialise_unique - introduce an inode into the tree |
2467 | * @dentry: candidate dentry |
2468 | * @inode: inode to bind to the dentry, to which aliases may be attached |
2469 | * |
2470 | * Introduces an dentry into the tree, substituting an extant disconnected |
2471 | * root directory alias in its place if there is one. Caller must hold the |
2472 | * i_mutex of the parent directory. |
2473 | */ |
2474 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) |
2475 | { |
2476 | struct dentry *actual; |
2477 | |
2478 | BUG_ON(!d_unhashed(dentry)); |
2479 | |
2480 | if (!inode) { |
2481 | actual = dentry; |
2482 | __d_instantiate(dentry, NULL); |
2483 | d_rehash(actual); |
2484 | goto out_nolock; |
2485 | } |
2486 | |
2487 | spin_lock(&inode->i_lock); |
2488 | |
2489 | if (S_ISDIR(inode->i_mode)) { |
2490 | struct dentry *alias; |
2491 | |
2492 | /* Does an aliased dentry already exist? */ |
2493 | alias = __d_find_alias(inode, 0); |
2494 | if (alias) { |
2495 | actual = alias; |
2496 | write_seqlock(&rename_lock); |
2497 | |
2498 | if (d_ancestor(alias, dentry)) { |
2499 | /* Check for loops */ |
2500 | actual = ERR_PTR(-ELOOP); |
2501 | spin_unlock(&inode->i_lock); |
2502 | } else if (IS_ROOT(alias)) { |
2503 | /* Is this an anonymous mountpoint that we |
2504 | * could splice into our tree? */ |
2505 | __d_materialise_dentry(dentry, alias); |
2506 | write_sequnlock(&rename_lock); |
2507 | __d_drop(alias); |
2508 | goto found; |
2509 | } else { |
2510 | /* Nope, but we must(!) avoid directory |
2511 | * aliasing. This drops inode->i_lock */ |
2512 | actual = __d_unalias(inode, dentry, alias); |
2513 | } |
2514 | write_sequnlock(&rename_lock); |
2515 | if (IS_ERR(actual)) { |
2516 | if (PTR_ERR(actual) == -ELOOP) |
2517 | pr_warn_ratelimited( |
2518 | "VFS: Lookup of '%s' in %s %s" |
2519 | " would have caused loop\n", |
2520 | dentry->d_name.name, |
2521 | inode->i_sb->s_type->name, |
2522 | inode->i_sb->s_id); |
2523 | dput(alias); |
2524 | } |
2525 | goto out_nolock; |
2526 | } |
2527 | } |
2528 | |
2529 | /* Add a unique reference */ |
2530 | actual = __d_instantiate_unique(dentry, inode); |
2531 | if (!actual) |
2532 | actual = dentry; |
2533 | else |
2534 | BUG_ON(!d_unhashed(actual)); |
2535 | |
2536 | spin_lock(&actual->d_lock); |
2537 | found: |
2538 | _d_rehash(actual); |
2539 | spin_unlock(&actual->d_lock); |
2540 | spin_unlock(&inode->i_lock); |
2541 | out_nolock: |
2542 | if (actual == dentry) { |
2543 | security_d_instantiate(dentry, inode); |
2544 | return NULL; |
2545 | } |
2546 | |
2547 | iput(inode); |
2548 | return actual; |
2549 | } |
2550 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
2551 | |
2552 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
2553 | { |
2554 | *buflen -= namelen; |
2555 | if (*buflen < 0) |
2556 | return -ENAMETOOLONG; |
2557 | *buffer -= namelen; |
2558 | memcpy(*buffer, str, namelen); |
2559 | return 0; |
2560 | } |
2561 | |
2562 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2563 | { |
2564 | return prepend(buffer, buflen, name->name, name->len); |
2565 | } |
2566 | |
2567 | /** |
2568 | * prepend_path - Prepend path string to a buffer |
2569 | * @path: the dentry/vfsmount to report |
2570 | * @root: root vfsmnt/dentry |
2571 | * @buffer: pointer to the end of the buffer |
2572 | * @buflen: pointer to buffer length |
2573 | * |
2574 | * Caller holds the rename_lock. |
2575 | */ |
2576 | static int prepend_path(const struct path *path, |
2577 | const struct path *root, |
2578 | char **buffer, int *buflen) |
2579 | { |
2580 | struct dentry *dentry = path->dentry; |
2581 | struct vfsmount *vfsmnt = path->mnt; |
2582 | struct mount *mnt = real_mount(vfsmnt); |
2583 | bool slash = false; |
2584 | int error = 0; |
2585 | |
2586 | br_read_lock(&vfsmount_lock); |
2587 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
2588 | struct dentry * parent; |
2589 | |
2590 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
2591 | /* Global root? */ |
2592 | if (!mnt_has_parent(mnt)) |
2593 | goto global_root; |
2594 | dentry = mnt->mnt_mountpoint; |
2595 | mnt = mnt->mnt_parent; |
2596 | vfsmnt = &mnt->mnt; |
2597 | continue; |
2598 | } |
2599 | parent = dentry->d_parent; |
2600 | prefetch(parent); |
2601 | spin_lock(&dentry->d_lock); |
2602 | error = prepend_name(buffer, buflen, &dentry->d_name); |
2603 | spin_unlock(&dentry->d_lock); |
2604 | if (!error) |
2605 | error = prepend(buffer, buflen, "/", 1); |
2606 | if (error) |
2607 | break; |
2608 | |
2609 | slash = true; |
2610 | dentry = parent; |
2611 | } |
2612 | |
2613 | if (!error && !slash) |
2614 | error = prepend(buffer, buflen, "/", 1); |
2615 | |
2616 | out: |
2617 | br_read_unlock(&vfsmount_lock); |
2618 | return error; |
2619 | |
2620 | global_root: |
2621 | /* |
2622 | * Filesystems needing to implement special "root names" |
2623 | * should do so with ->d_dname() |
2624 | */ |
2625 | if (IS_ROOT(dentry) && |
2626 | (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { |
2627 | WARN(1, "Root dentry has weird name <%.*s>\n", |
2628 | (int) dentry->d_name.len, dentry->d_name.name); |
2629 | } |
2630 | if (!slash) |
2631 | error = prepend(buffer, buflen, "/", 1); |
2632 | if (!error) |
2633 | error = is_mounted(vfsmnt) ? 1 : 2; |
2634 | goto out; |
2635 | } |
2636 | |
2637 | /** |
2638 | * __d_path - return the path of a dentry |
2639 | * @path: the dentry/vfsmount to report |
2640 | * @root: root vfsmnt/dentry |
2641 | * @buf: buffer to return value in |
2642 | * @buflen: buffer length |
2643 | * |
2644 | * Convert a dentry into an ASCII path name. |
2645 | * |
2646 | * Returns a pointer into the buffer or an error code if the |
2647 | * path was too long. |
2648 | * |
2649 | * "buflen" should be positive. |
2650 | * |
2651 | * If the path is not reachable from the supplied root, return %NULL. |
2652 | */ |
2653 | char *__d_path(const struct path *path, |
2654 | const struct path *root, |
2655 | char *buf, int buflen) |
2656 | { |
2657 | char *res = buf + buflen; |
2658 | int error; |
2659 | |
2660 | prepend(&res, &buflen, "\0", 1); |
2661 | write_seqlock(&rename_lock); |
2662 | error = prepend_path(path, root, &res, &buflen); |
2663 | write_sequnlock(&rename_lock); |
2664 | |
2665 | if (error < 0) |
2666 | return ERR_PTR(error); |
2667 | if (error > 0) |
2668 | return NULL; |
2669 | return res; |
2670 | } |
2671 | |
2672 | char *d_absolute_path(const struct path *path, |
2673 | char *buf, int buflen) |
2674 | { |
2675 | struct path root = {}; |
2676 | char *res = buf + buflen; |
2677 | int error; |
2678 | |
2679 | prepend(&res, &buflen, "\0", 1); |
2680 | write_seqlock(&rename_lock); |
2681 | error = prepend_path(path, &root, &res, &buflen); |
2682 | write_sequnlock(&rename_lock); |
2683 | |
2684 | if (error > 1) |
2685 | error = -EINVAL; |
2686 | if (error < 0) |
2687 | return ERR_PTR(error); |
2688 | return res; |
2689 | } |
2690 | |
2691 | /* |
2692 | * same as __d_path but appends "(deleted)" for unlinked files. |
2693 | */ |
2694 | static int path_with_deleted(const struct path *path, |
2695 | const struct path *root, |
2696 | char **buf, int *buflen) |
2697 | { |
2698 | prepend(buf, buflen, "\0", 1); |
2699 | if (d_unlinked(path->dentry)) { |
2700 | int error = prepend(buf, buflen, " (deleted)", 10); |
2701 | if (error) |
2702 | return error; |
2703 | } |
2704 | |
2705 | return prepend_path(path, root, buf, buflen); |
2706 | } |
2707 | |
2708 | static int prepend_unreachable(char **buffer, int *buflen) |
2709 | { |
2710 | return prepend(buffer, buflen, "(unreachable)", 13); |
2711 | } |
2712 | |
2713 | /** |
2714 | * d_path - return the path of a dentry |
2715 | * @path: path to report |
2716 | * @buf: buffer to return value in |
2717 | * @buflen: buffer length |
2718 | * |
2719 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
2720 | * the string " (deleted)" is appended. Note that this is ambiguous. |
2721 | * |
2722 | * Returns a pointer into the buffer or an error code if the path was |
2723 | * too long. Note: Callers should use the returned pointer, not the passed |
2724 | * in buffer, to use the name! The implementation often starts at an offset |
2725 | * into the buffer, and may leave 0 bytes at the start. |
2726 | * |
2727 | * "buflen" should be positive. |
2728 | */ |
2729 | char *d_path(const struct path *path, char *buf, int buflen) |
2730 | { |
2731 | char *res = buf + buflen; |
2732 | struct path root; |
2733 | int error; |
2734 | |
2735 | /* |
2736 | * We have various synthetic filesystems that never get mounted. On |
2737 | * these filesystems dentries are never used for lookup purposes, and |
2738 | * thus don't need to be hashed. They also don't need a name until a |
2739 | * user wants to identify the object in /proc/pid/fd/. The little hack |
2740 | * below allows us to generate a name for these objects on demand: |
2741 | */ |
2742 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2743 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
2744 | |
2745 | get_fs_root(current->fs, &root); |
2746 | write_seqlock(&rename_lock); |
2747 | error = path_with_deleted(path, &root, &res, &buflen); |
2748 | if (error < 0) |
2749 | res = ERR_PTR(error); |
2750 | write_sequnlock(&rename_lock); |
2751 | path_put(&root); |
2752 | return res; |
2753 | } |
2754 | EXPORT_SYMBOL(d_path); |
2755 | |
2756 | /** |
2757 | * d_path_with_unreachable - return the path of a dentry |
2758 | * @path: path to report |
2759 | * @buf: buffer to return value in |
2760 | * @buflen: buffer length |
2761 | * |
2762 | * The difference from d_path() is that this prepends "(unreachable)" |
2763 | * to paths which are unreachable from the current process' root. |
2764 | */ |
2765 | char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) |
2766 | { |
2767 | char *res = buf + buflen; |
2768 | struct path root; |
2769 | int error; |
2770 | |
2771 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2772 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); |
2773 | |
2774 | get_fs_root(current->fs, &root); |
2775 | write_seqlock(&rename_lock); |
2776 | error = path_with_deleted(path, &root, &res, &buflen); |
2777 | if (error > 0) |
2778 | error = prepend_unreachable(&res, &buflen); |
2779 | write_sequnlock(&rename_lock); |
2780 | path_put(&root); |
2781 | if (error) |
2782 | res = ERR_PTR(error); |
2783 | |
2784 | return res; |
2785 | } |
2786 | |
2787 | /* |
2788 | * Helper function for dentry_operations.d_dname() members |
2789 | */ |
2790 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, |
2791 | const char *fmt, ...) |
2792 | { |
2793 | va_list args; |
2794 | char temp[64]; |
2795 | int sz; |
2796 | |
2797 | va_start(args, fmt); |
2798 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; |
2799 | va_end(args); |
2800 | |
2801 | if (sz > sizeof(temp) || sz > buflen) |
2802 | return ERR_PTR(-ENAMETOOLONG); |
2803 | |
2804 | buffer += buflen - sz; |
2805 | return memcpy(buffer, temp, sz); |
2806 | } |
2807 | |
2808 | /* |
2809 | * Write full pathname from the root of the filesystem into the buffer. |
2810 | */ |
2811 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
2812 | { |
2813 | char *end = buf + buflen; |
2814 | char *retval; |
2815 | |
2816 | prepend(&end, &buflen, "\0", 1); |
2817 | if (buflen < 1) |
2818 | goto Elong; |
2819 | /* Get '/' right */ |
2820 | retval = end-1; |
2821 | *retval = '/'; |
2822 | |
2823 | while (!IS_ROOT(dentry)) { |
2824 | struct dentry *parent = dentry->d_parent; |
2825 | int error; |
2826 | |
2827 | prefetch(parent); |
2828 | spin_lock(&dentry->d_lock); |
2829 | error = prepend_name(&end, &buflen, &dentry->d_name); |
2830 | spin_unlock(&dentry->d_lock); |
2831 | if (error != 0 || prepend(&end, &buflen, "/", 1) != 0) |
2832 | goto Elong; |
2833 | |
2834 | retval = end; |
2835 | dentry = parent; |
2836 | } |
2837 | return retval; |
2838 | Elong: |
2839 | return ERR_PTR(-ENAMETOOLONG); |
2840 | } |
2841 | |
2842 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) |
2843 | { |
2844 | char *retval; |
2845 | |
2846 | write_seqlock(&rename_lock); |
2847 | retval = __dentry_path(dentry, buf, buflen); |
2848 | write_sequnlock(&rename_lock); |
2849 | |
2850 | return retval; |
2851 | } |
2852 | EXPORT_SYMBOL(dentry_path_raw); |
2853 | |
2854 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) |
2855 | { |
2856 | char *p = NULL; |
2857 | char *retval; |
2858 | |
2859 | write_seqlock(&rename_lock); |
2860 | if (d_unlinked(dentry)) { |
2861 | p = buf + buflen; |
2862 | if (prepend(&p, &buflen, "//deleted", 10) != 0) |
2863 | goto Elong; |
2864 | buflen++; |
2865 | } |
2866 | retval = __dentry_path(dentry, buf, buflen); |
2867 | write_sequnlock(&rename_lock); |
2868 | if (!IS_ERR(retval) && p) |
2869 | *p = '/'; /* restore '/' overriden with '\0' */ |
2870 | return retval; |
2871 | Elong: |
2872 | return ERR_PTR(-ENAMETOOLONG); |
2873 | } |
2874 | |
2875 | /* |
2876 | * NOTE! The user-level library version returns a |
2877 | * character pointer. The kernel system call just |
2878 | * returns the length of the buffer filled (which |
2879 | * includes the ending '\0' character), or a negative |
2880 | * error value. So libc would do something like |
2881 | * |
2882 | * char *getcwd(char * buf, size_t size) |
2883 | * { |
2884 | * int retval; |
2885 | * |
2886 | * retval = sys_getcwd(buf, size); |
2887 | * if (retval >= 0) |
2888 | * return buf; |
2889 | * errno = -retval; |
2890 | * return NULL; |
2891 | * } |
2892 | */ |
2893 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
2894 | { |
2895 | int error; |
2896 | struct path pwd, root; |
2897 | char *page = (char *) __get_free_page(GFP_USER); |
2898 | |
2899 | if (!page) |
2900 | return -ENOMEM; |
2901 | |
2902 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
2903 | |
2904 | error = -ENOENT; |
2905 | write_seqlock(&rename_lock); |
2906 | if (!d_unlinked(pwd.dentry)) { |
2907 | unsigned long len; |
2908 | char *cwd = page + PAGE_SIZE; |
2909 | int buflen = PAGE_SIZE; |
2910 | |
2911 | prepend(&cwd, &buflen, "\0", 1); |
2912 | error = prepend_path(&pwd, &root, &cwd, &buflen); |
2913 | write_sequnlock(&rename_lock); |
2914 | |
2915 | if (error < 0) |
2916 | goto out; |
2917 | |
2918 | /* Unreachable from current root */ |
2919 | if (error > 0) { |
2920 | error = prepend_unreachable(&cwd, &buflen); |
2921 | if (error) |
2922 | goto out; |
2923 | } |
2924 | |
2925 | error = -ERANGE; |
2926 | len = PAGE_SIZE + page - cwd; |
2927 | if (len <= size) { |
2928 | error = len; |
2929 | if (copy_to_user(buf, cwd, len)) |
2930 | error = -EFAULT; |
2931 | } |
2932 | } else { |
2933 | write_sequnlock(&rename_lock); |
2934 | } |
2935 | |
2936 | out: |
2937 | path_put(&pwd); |
2938 | path_put(&root); |
2939 | free_page((unsigned long) page); |
2940 | return error; |
2941 | } |
2942 | |
2943 | /* |
2944 | * Test whether new_dentry is a subdirectory of old_dentry. |
2945 | * |
2946 | * Trivially implemented using the dcache structure |
2947 | */ |
2948 | |
2949 | /** |
2950 | * is_subdir - is new dentry a subdirectory of old_dentry |
2951 | * @new_dentry: new dentry |
2952 | * @old_dentry: old dentry |
2953 | * |
2954 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). |
2955 | * Returns 0 otherwise. |
2956 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() |
2957 | */ |
2958 | |
2959 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
2960 | { |
2961 | int result; |
2962 | unsigned seq; |
2963 | |
2964 | if (new_dentry == old_dentry) |
2965 | return 1; |
2966 | |
2967 | do { |
2968 | /* for restarting inner loop in case of seq retry */ |
2969 | seq = read_seqbegin(&rename_lock); |
2970 | /* |
2971 | * Need rcu_readlock to protect against the d_parent trashing |
2972 | * due to d_move |
2973 | */ |
2974 | rcu_read_lock(); |
2975 | if (d_ancestor(old_dentry, new_dentry)) |
2976 | result = 1; |
2977 | else |
2978 | result = 0; |
2979 | rcu_read_unlock(); |
2980 | } while (read_seqretry(&rename_lock, seq)); |
2981 | |
2982 | return result; |
2983 | } |
2984 | |
2985 | void d_genocide(struct dentry *root) |
2986 | { |
2987 | struct dentry *this_parent; |
2988 | struct list_head *next; |
2989 | unsigned seq; |
2990 | int locked = 0; |
2991 | |
2992 | seq = read_seqbegin(&rename_lock); |
2993 | again: |
2994 | this_parent = root; |
2995 | spin_lock(&this_parent->d_lock); |
2996 | repeat: |
2997 | next = this_parent->d_subdirs.next; |
2998 | resume: |
2999 | while (next != &this_parent->d_subdirs) { |
3000 | struct list_head *tmp = next; |
3001 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
3002 | next = tmp->next; |
3003 | |
3004 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
3005 | if (d_unhashed(dentry) || !dentry->d_inode) { |
3006 | spin_unlock(&dentry->d_lock); |
3007 | continue; |
3008 | } |
3009 | if (!list_empty(&dentry->d_subdirs)) { |
3010 | spin_unlock(&this_parent->d_lock); |
3011 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); |
3012 | this_parent = dentry; |
3013 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
3014 | goto repeat; |
3015 | } |
3016 | if (!(dentry->d_flags & DCACHE_GENOCIDE)) { |
3017 | dentry->d_flags |= DCACHE_GENOCIDE; |
3018 | dentry->d_count--; |
3019 | } |
3020 | spin_unlock(&dentry->d_lock); |
3021 | } |
3022 | if (this_parent != root) { |
3023 | struct dentry *child = this_parent; |
3024 | if (!(this_parent->d_flags & DCACHE_GENOCIDE)) { |
3025 | this_parent->d_flags |= DCACHE_GENOCIDE; |
3026 | this_parent->d_count--; |
3027 | } |
3028 | this_parent = try_to_ascend(this_parent, locked, seq); |
3029 | if (!this_parent) |
3030 | goto rename_retry; |
3031 | next = child->d_u.d_child.next; |
3032 | goto resume; |
3033 | } |
3034 | spin_unlock(&this_parent->d_lock); |
3035 | if (!locked && read_seqretry(&rename_lock, seq)) |
3036 | goto rename_retry; |
3037 | if (locked) |
3038 | write_sequnlock(&rename_lock); |
3039 | return; |
3040 | |
3041 | rename_retry: |
3042 | if (locked) |
3043 | goto again; |
3044 | locked = 1; |
3045 | write_seqlock(&rename_lock); |
3046 | goto again; |
3047 | } |
3048 | |
3049 | /** |
3050 | * find_inode_number - check for dentry with name |
3051 | * @dir: directory to check |
3052 | * @name: Name to find. |
3053 | * |
3054 | * Check whether a dentry already exists for the given name, |
3055 | * and return the inode number if it has an inode. Otherwise |
3056 | * 0 is returned. |
3057 | * |
3058 | * This routine is used to post-process directory listings for |
3059 | * filesystems using synthetic inode numbers, and is necessary |
3060 | * to keep getcwd() working. |
3061 | */ |
3062 | |
3063 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) |
3064 | { |
3065 | struct dentry * dentry; |
3066 | ino_t ino = 0; |
3067 | |
3068 | dentry = d_hash_and_lookup(dir, name); |
3069 | if (dentry) { |
3070 | if (dentry->d_inode) |
3071 | ino = dentry->d_inode->i_ino; |
3072 | dput(dentry); |
3073 | } |
3074 | return ino; |
3075 | } |
3076 | EXPORT_SYMBOL(find_inode_number); |
3077 | |
3078 | static __initdata unsigned long dhash_entries; |
3079 | static int __init set_dhash_entries(char *str) |
3080 | { |
3081 | if (!str) |
3082 | return 0; |
3083 | dhash_entries = simple_strtoul(str, &str, 0); |
3084 | return 1; |
3085 | } |
3086 | __setup("dhash_entries=", set_dhash_entries); |
3087 | |
3088 | static void __init dcache_init_early(void) |
3089 | { |
3090 | unsigned int loop; |
3091 | |
3092 | /* If hashes are distributed across NUMA nodes, defer |
3093 | * hash allocation until vmalloc space is available. |
3094 | */ |
3095 | if (hashdist) |
3096 | return; |
3097 | |
3098 | dentry_hashtable = |
3099 | alloc_large_system_hash("Dentry cache", |
3100 | sizeof(struct hlist_bl_head), |
3101 | dhash_entries, |
3102 | 13, |
3103 | HASH_EARLY, |
3104 | &d_hash_shift, |
3105 | &d_hash_mask, |
3106 | 0, |
3107 | 0); |
3108 | |
3109 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
3110 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
3111 | } |
3112 | |
3113 | static void __init dcache_init(void) |
3114 | { |
3115 | unsigned int loop; |
3116 | |
3117 | /* |
3118 | * A constructor could be added for stable state like the lists, |
3119 | * but it is probably not worth it because of the cache nature |
3120 | * of the dcache. |
3121 | */ |
3122 | dentry_cache = KMEM_CACHE(dentry, |
3123 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); |
3124 | |
3125 | /* Hash may have been set up in dcache_init_early */ |
3126 | if (!hashdist) |
3127 | return; |
3128 | |
3129 | dentry_hashtable = |
3130 | alloc_large_system_hash("Dentry cache", |
3131 | sizeof(struct hlist_bl_head), |
3132 | dhash_entries, |
3133 | 13, |
3134 | 0, |
3135 | &d_hash_shift, |
3136 | &d_hash_mask, |
3137 | 0, |
3138 | 0); |
3139 | |
3140 | for (loop = 0; loop < (1U << d_hash_shift); loop++) |
3141 | INIT_HLIST_BL_HEAD(dentry_hashtable + loop); |
3142 | } |
3143 | |
3144 | /* SLAB cache for __getname() consumers */ |
3145 | struct kmem_cache *names_cachep __read_mostly; |
3146 | EXPORT_SYMBOL(names_cachep); |
3147 | |
3148 | EXPORT_SYMBOL(d_genocide); |
3149 | |
3150 | void __init vfs_caches_init_early(void) |
3151 | { |
3152 | dcache_init_early(); |
3153 | inode_init_early(); |
3154 | } |
3155 | |
3156 | void __init vfs_caches_init(unsigned long mempages) |
3157 | { |
3158 | unsigned long reserve; |
3159 | |
3160 | /* Base hash sizes on available memory, with a reserve equal to |
3161 | 150% of current kernel size */ |
3162 | |
3163 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); |
3164 | mempages -= reserve; |
3165 | |
3166 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, |
3167 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
3168 | |
3169 | dcache_init(); |
3170 | inode_init(); |
3171 | files_init(mempages); |
3172 | mnt_init(); |
3173 | bdev_cache_init(); |
3174 | chrdev_init(); |
3175 | } |
3176 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
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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