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Commit | Line | Data |
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1da177e4 LT |
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 | ||
1da177e4 LT |
17 | #include <linux/syscalls.h> |
18 | #include <linux/string.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/fs.h> | |
7a91bf7f | 21 | #include <linux/fsnotify.h> |
1da177e4 LT |
22 | #include <linux/slab.h> |
23 | #include <linux/init.h> | |
24 | #include <linux/smp_lock.h> | |
25 | #include <linux/hash.h> | |
26 | #include <linux/cache.h> | |
27 | #include <linux/module.h> | |
28 | #include <linux/mount.h> | |
29 | #include <linux/file.h> | |
30 | #include <asm/uaccess.h> | |
31 | #include <linux/security.h> | |
32 | #include <linux/seqlock.h> | |
33 | #include <linux/swap.h> | |
34 | #include <linux/bootmem.h> | |
07f3f05c | 35 | #include "internal.h" |
1da177e4 | 36 | |
1da177e4 | 37 | |
fa3536cc | 38 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
39 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
40 | ||
41 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); | |
e4d91918 | 42 | static __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 LT |
43 | |
44 | EXPORT_SYMBOL(dcache_lock); | |
45 | ||
e18b890b | 46 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 LT |
47 | |
48 | #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) | |
49 | ||
50 | /* | |
51 | * This is the single most critical data structure when it comes | |
52 | * to the dcache: the hashtable for lookups. Somebody should try | |
53 | * to make this good - I've just made it work. | |
54 | * | |
55 | * This hash-function tries to avoid losing too many bits of hash | |
56 | * information, yet avoid using a prime hash-size or similar. | |
57 | */ | |
58 | #define D_HASHBITS d_hash_shift | |
59 | #define D_HASHMASK d_hash_mask | |
60 | ||
fa3536cc ED |
61 | static unsigned int d_hash_mask __read_mostly; |
62 | static unsigned int d_hash_shift __read_mostly; | |
63 | static struct hlist_head *dentry_hashtable __read_mostly; | |
1da177e4 LT |
64 | static LIST_HEAD(dentry_unused); |
65 | ||
66 | /* Statistics gathering. */ | |
67 | struct dentry_stat_t dentry_stat = { | |
68 | .age_limit = 45, | |
69 | }; | |
70 | ||
b3423415 | 71 | static void __d_free(struct dentry *dentry) |
1da177e4 | 72 | { |
1da177e4 LT |
73 | if (dname_external(dentry)) |
74 | kfree(dentry->d_name.name); | |
75 | kmem_cache_free(dentry_cache, dentry); | |
76 | } | |
77 | ||
b3423415 ED |
78 | static void d_callback(struct rcu_head *head) |
79 | { | |
80 | struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); | |
81 | __d_free(dentry); | |
82 | } | |
83 | ||
1da177e4 LT |
84 | /* |
85 | * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry | |
86 | * inside dcache_lock. | |
87 | */ | |
88 | static void d_free(struct dentry *dentry) | |
89 | { | |
90 | if (dentry->d_op && dentry->d_op->d_release) | |
91 | dentry->d_op->d_release(dentry); | |
b3423415 ED |
92 | /* if dentry was never inserted into hash, immediate free is OK */ |
93 | if (dentry->d_hash.pprev == NULL) | |
94 | __d_free(dentry); | |
95 | else | |
96 | call_rcu(&dentry->d_u.d_rcu, d_callback); | |
1da177e4 LT |
97 | } |
98 | ||
99 | /* | |
100 | * Release the dentry's inode, using the filesystem | |
101 | * d_iput() operation if defined. | |
102 | * Called with dcache_lock and per dentry lock held, drops both. | |
103 | */ | |
858119e1 | 104 | static void dentry_iput(struct dentry * dentry) |
1da177e4 LT |
105 | { |
106 | struct inode *inode = dentry->d_inode; | |
107 | if (inode) { | |
108 | dentry->d_inode = NULL; | |
109 | list_del_init(&dentry->d_alias); | |
110 | spin_unlock(&dentry->d_lock); | |
111 | spin_unlock(&dcache_lock); | |
f805fbda LT |
112 | if (!inode->i_nlink) |
113 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
114 | if (dentry->d_op && dentry->d_op->d_iput) |
115 | dentry->d_op->d_iput(dentry, inode); | |
116 | else | |
117 | iput(inode); | |
118 | } else { | |
119 | spin_unlock(&dentry->d_lock); | |
120 | spin_unlock(&dcache_lock); | |
121 | } | |
122 | } | |
123 | ||
124 | /* | |
125 | * This is dput | |
126 | * | |
127 | * This is complicated by the fact that we do not want to put | |
128 | * dentries that are no longer on any hash chain on the unused | |
129 | * list: we'd much rather just get rid of them immediately. | |
130 | * | |
131 | * However, that implies that we have to traverse the dentry | |
132 | * tree upwards to the parents which might _also_ now be | |
133 | * scheduled for deletion (it may have been only waiting for | |
134 | * its last child to go away). | |
135 | * | |
136 | * This tail recursion is done by hand as we don't want to depend | |
137 | * on the compiler to always get this right (gcc generally doesn't). | |
138 | * Real recursion would eat up our stack space. | |
139 | */ | |
140 | ||
141 | /* | |
142 | * dput - release a dentry | |
143 | * @dentry: dentry to release | |
144 | * | |
145 | * Release a dentry. This will drop the usage count and if appropriate | |
146 | * call the dentry unlink method as well as removing it from the queues and | |
147 | * releasing its resources. If the parent dentries were scheduled for release | |
148 | * they too may now get deleted. | |
149 | * | |
150 | * no dcache lock, please. | |
151 | */ | |
152 | ||
153 | void dput(struct dentry *dentry) | |
154 | { | |
155 | if (!dentry) | |
156 | return; | |
157 | ||
158 | repeat: | |
159 | if (atomic_read(&dentry->d_count) == 1) | |
160 | might_sleep(); | |
161 | if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) | |
162 | return; | |
163 | ||
164 | spin_lock(&dentry->d_lock); | |
165 | if (atomic_read(&dentry->d_count)) { | |
166 | spin_unlock(&dentry->d_lock); | |
167 | spin_unlock(&dcache_lock); | |
168 | return; | |
169 | } | |
170 | ||
171 | /* | |
172 | * AV: ->d_delete() is _NOT_ allowed to block now. | |
173 | */ | |
174 | if (dentry->d_op && dentry->d_op->d_delete) { | |
175 | if (dentry->d_op->d_delete(dentry)) | |
176 | goto unhash_it; | |
177 | } | |
178 | /* Unreachable? Get rid of it */ | |
179 | if (d_unhashed(dentry)) | |
180 | goto kill_it; | |
181 | if (list_empty(&dentry->d_lru)) { | |
182 | dentry->d_flags |= DCACHE_REFERENCED; | |
183 | list_add(&dentry->d_lru, &dentry_unused); | |
184 | dentry_stat.nr_unused++; | |
185 | } | |
186 | spin_unlock(&dentry->d_lock); | |
187 | spin_unlock(&dcache_lock); | |
188 | return; | |
189 | ||
190 | unhash_it: | |
191 | __d_drop(dentry); | |
192 | ||
193 | kill_it: { | |
194 | struct dentry *parent; | |
195 | ||
196 | /* If dentry was on d_lru list | |
197 | * delete it from there | |
198 | */ | |
199 | if (!list_empty(&dentry->d_lru)) { | |
200 | list_del(&dentry->d_lru); | |
201 | dentry_stat.nr_unused--; | |
202 | } | |
5160ee6f | 203 | list_del(&dentry->d_u.d_child); |
1da177e4 LT |
204 | dentry_stat.nr_dentry--; /* For d_free, below */ |
205 | /*drops the locks, at that point nobody can reach this dentry */ | |
206 | dentry_iput(dentry); | |
207 | parent = dentry->d_parent; | |
208 | d_free(dentry); | |
209 | if (dentry == parent) | |
210 | return; | |
211 | dentry = parent; | |
212 | goto repeat; | |
213 | } | |
214 | } | |
215 | ||
216 | /** | |
217 | * d_invalidate - invalidate a dentry | |
218 | * @dentry: dentry to invalidate | |
219 | * | |
220 | * Try to invalidate the dentry if it turns out to be | |
221 | * possible. If there are other dentries that can be | |
222 | * reached through this one we can't delete it and we | |
223 | * return -EBUSY. On success we return 0. | |
224 | * | |
225 | * no dcache lock. | |
226 | */ | |
227 | ||
228 | int d_invalidate(struct dentry * dentry) | |
229 | { | |
230 | /* | |
231 | * If it's already been dropped, return OK. | |
232 | */ | |
233 | spin_lock(&dcache_lock); | |
234 | if (d_unhashed(dentry)) { | |
235 | spin_unlock(&dcache_lock); | |
236 | return 0; | |
237 | } | |
238 | /* | |
239 | * Check whether to do a partial shrink_dcache | |
240 | * to get rid of unused child entries. | |
241 | */ | |
242 | if (!list_empty(&dentry->d_subdirs)) { | |
243 | spin_unlock(&dcache_lock); | |
244 | shrink_dcache_parent(dentry); | |
245 | spin_lock(&dcache_lock); | |
246 | } | |
247 | ||
248 | /* | |
249 | * Somebody else still using it? | |
250 | * | |
251 | * If it's a directory, we can't drop it | |
252 | * for fear of somebody re-populating it | |
253 | * with children (even though dropping it | |
254 | * would make it unreachable from the root, | |
255 | * we might still populate it if it was a | |
256 | * working directory or similar). | |
257 | */ | |
258 | spin_lock(&dentry->d_lock); | |
259 | if (atomic_read(&dentry->d_count) > 1) { | |
260 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { | |
261 | spin_unlock(&dentry->d_lock); | |
262 | spin_unlock(&dcache_lock); | |
263 | return -EBUSY; | |
264 | } | |
265 | } | |
266 | ||
267 | __d_drop(dentry); | |
268 | spin_unlock(&dentry->d_lock); | |
269 | spin_unlock(&dcache_lock); | |
270 | return 0; | |
271 | } | |
272 | ||
273 | /* This should be called _only_ with dcache_lock held */ | |
274 | ||
275 | static inline struct dentry * __dget_locked(struct dentry *dentry) | |
276 | { | |
277 | atomic_inc(&dentry->d_count); | |
278 | if (!list_empty(&dentry->d_lru)) { | |
279 | dentry_stat.nr_unused--; | |
280 | list_del_init(&dentry->d_lru); | |
281 | } | |
282 | return dentry; | |
283 | } | |
284 | ||
285 | struct dentry * dget_locked(struct dentry *dentry) | |
286 | { | |
287 | return __dget_locked(dentry); | |
288 | } | |
289 | ||
290 | /** | |
291 | * d_find_alias - grab a hashed alias of inode | |
292 | * @inode: inode in question | |
293 | * @want_discon: flag, used by d_splice_alias, to request | |
294 | * that only a DISCONNECTED alias be returned. | |
295 | * | |
296 | * If inode has a hashed alias, or is a directory and has any alias, | |
297 | * acquire the reference to alias and return it. Otherwise return NULL. | |
298 | * Notice that if inode is a directory there can be only one alias and | |
299 | * it can be unhashed only if it has no children, or if it is the root | |
300 | * of a filesystem. | |
301 | * | |
21c0d8fd | 302 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
1da177e4 | 303 | * any other hashed alias over that one unless @want_discon is set, |
21c0d8fd | 304 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
1da177e4 LT |
305 | */ |
306 | ||
307 | static struct dentry * __d_find_alias(struct inode *inode, int want_discon) | |
308 | { | |
309 | struct list_head *head, *next, *tmp; | |
310 | struct dentry *alias, *discon_alias=NULL; | |
311 | ||
312 | head = &inode->i_dentry; | |
313 | next = inode->i_dentry.next; | |
314 | while (next != head) { | |
315 | tmp = next; | |
316 | next = tmp->next; | |
317 | prefetch(next); | |
318 | alias = list_entry(tmp, struct dentry, d_alias); | |
319 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
21c0d8fd N |
320 | if (IS_ROOT(alias) && |
321 | (alias->d_flags & DCACHE_DISCONNECTED)) | |
1da177e4 LT |
322 | discon_alias = alias; |
323 | else if (!want_discon) { | |
324 | __dget_locked(alias); | |
325 | return alias; | |
326 | } | |
327 | } | |
328 | } | |
329 | if (discon_alias) | |
330 | __dget_locked(discon_alias); | |
331 | return discon_alias; | |
332 | } | |
333 | ||
334 | struct dentry * d_find_alias(struct inode *inode) | |
335 | { | |
214fda1f DH |
336 | struct dentry *de = NULL; |
337 | ||
338 | if (!list_empty(&inode->i_dentry)) { | |
339 | spin_lock(&dcache_lock); | |
340 | de = __d_find_alias(inode, 0); | |
341 | spin_unlock(&dcache_lock); | |
342 | } | |
1da177e4 LT |
343 | return de; |
344 | } | |
345 | ||
346 | /* | |
347 | * Try to kill dentries associated with this inode. | |
348 | * WARNING: you must own a reference to inode. | |
349 | */ | |
350 | void d_prune_aliases(struct inode *inode) | |
351 | { | |
0cdca3f9 | 352 | struct dentry *dentry; |
1da177e4 LT |
353 | restart: |
354 | spin_lock(&dcache_lock); | |
0cdca3f9 | 355 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 LT |
356 | spin_lock(&dentry->d_lock); |
357 | if (!atomic_read(&dentry->d_count)) { | |
358 | __dget_locked(dentry); | |
359 | __d_drop(dentry); | |
360 | spin_unlock(&dentry->d_lock); | |
361 | spin_unlock(&dcache_lock); | |
362 | dput(dentry); | |
363 | goto restart; | |
364 | } | |
365 | spin_unlock(&dentry->d_lock); | |
366 | } | |
367 | spin_unlock(&dcache_lock); | |
368 | } | |
369 | ||
370 | /* | |
d702ccb3 AM |
371 | * Throw away a dentry - free the inode, dput the parent. This requires that |
372 | * the LRU list has already been removed. | |
373 | * | |
1da177e4 | 374 | * Called with dcache_lock, drops it and then regains. |
d702ccb3 | 375 | * Called with dentry->d_lock held, drops it. |
1da177e4 | 376 | */ |
d702ccb3 | 377 | static void prune_one_dentry(struct dentry * dentry) |
1da177e4 LT |
378 | { |
379 | struct dentry * parent; | |
380 | ||
381 | __d_drop(dentry); | |
5160ee6f | 382 | list_del(&dentry->d_u.d_child); |
1da177e4 LT |
383 | dentry_stat.nr_dentry--; /* For d_free, below */ |
384 | dentry_iput(dentry); | |
385 | parent = dentry->d_parent; | |
386 | d_free(dentry); | |
387 | if (parent != dentry) | |
388 | dput(parent); | |
389 | spin_lock(&dcache_lock); | |
390 | } | |
391 | ||
392 | /** | |
393 | * prune_dcache - shrink the dcache | |
394 | * @count: number of entries to try and free | |
0feae5c4 N |
395 | * @sb: if given, ignore dentries for other superblocks |
396 | * which are being unmounted. | |
1da177e4 LT |
397 | * |
398 | * Shrink the dcache. This is done when we need | |
399 | * more memory, or simply when we need to unmount | |
400 | * something (at which point we need to unuse | |
401 | * all dentries). | |
402 | * | |
403 | * This function may fail to free any resources if | |
404 | * all the dentries are in use. | |
405 | */ | |
406 | ||
0feae5c4 | 407 | static void prune_dcache(int count, struct super_block *sb) |
1da177e4 LT |
408 | { |
409 | spin_lock(&dcache_lock); | |
410 | for (; count ; count--) { | |
411 | struct dentry *dentry; | |
412 | struct list_head *tmp; | |
0feae5c4 | 413 | struct rw_semaphore *s_umount; |
1da177e4 LT |
414 | |
415 | cond_resched_lock(&dcache_lock); | |
416 | ||
417 | tmp = dentry_unused.prev; | |
f58a1ebb | 418 | if (sb) { |
0feae5c4 N |
419 | /* Try to find a dentry for this sb, but don't try |
420 | * too hard, if they aren't near the tail they will | |
421 | * be moved down again soon | |
422 | */ | |
423 | int skip = count; | |
424 | while (skip && tmp != &dentry_unused && | |
425 | list_entry(tmp, struct dentry, d_lru)->d_sb != sb) { | |
426 | skip--; | |
427 | tmp = tmp->prev; | |
428 | } | |
429 | } | |
1da177e4 LT |
430 | if (tmp == &dentry_unused) |
431 | break; | |
432 | list_del_init(tmp); | |
433 | prefetch(dentry_unused.prev); | |
434 | dentry_stat.nr_unused--; | |
435 | dentry = list_entry(tmp, struct dentry, d_lru); | |
436 | ||
437 | spin_lock(&dentry->d_lock); | |
438 | /* | |
439 | * We found an inuse dentry which was not removed from | |
440 | * dentry_unused because of laziness during lookup. Do not free | |
441 | * it - just keep it off the dentry_unused list. | |
442 | */ | |
443 | if (atomic_read(&dentry->d_count)) { | |
444 | spin_unlock(&dentry->d_lock); | |
445 | continue; | |
446 | } | |
447 | /* If the dentry was recently referenced, don't free it. */ | |
448 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
449 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
450 | list_add(&dentry->d_lru, &dentry_unused); | |
451 | dentry_stat.nr_unused++; | |
452 | spin_unlock(&dentry->d_lock); | |
453 | continue; | |
454 | } | |
0feae5c4 N |
455 | /* |
456 | * If the dentry is not DCACHED_REFERENCED, it is time | |
457 | * to remove it from the dcache, provided the super block is | |
458 | * NULL (which means we are trying to reclaim memory) | |
459 | * or this dentry belongs to the same super block that | |
460 | * we want to shrink. | |
461 | */ | |
462 | /* | |
463 | * If this dentry is for "my" filesystem, then I can prune it | |
464 | * without taking the s_umount lock (I already hold it). | |
465 | */ | |
466 | if (sb && dentry->d_sb == sb) { | |
467 | prune_one_dentry(dentry); | |
468 | continue; | |
469 | } | |
470 | /* | |
471 | * ...otherwise we need to be sure this filesystem isn't being | |
472 | * unmounted, otherwise we could race with | |
473 | * generic_shutdown_super(), and end up holding a reference to | |
474 | * an inode while the filesystem is unmounted. | |
475 | * So we try to get s_umount, and make sure s_root isn't NULL. | |
476 | * (Take a local copy of s_umount to avoid a use-after-free of | |
477 | * `dentry'). | |
478 | */ | |
479 | s_umount = &dentry->d_sb->s_umount; | |
480 | if (down_read_trylock(s_umount)) { | |
481 | if (dentry->d_sb->s_root != NULL) { | |
482 | prune_one_dentry(dentry); | |
483 | up_read(s_umount); | |
484 | continue; | |
485 | } | |
486 | up_read(s_umount); | |
487 | } | |
488 | spin_unlock(&dentry->d_lock); | |
6eac3f93 VA |
489 | /* |
490 | * Insert dentry at the head of the list as inserting at the | |
491 | * tail leads to a cycle. | |
0feae5c4 | 492 | */ |
6eac3f93 VA |
493 | list_add(&dentry->d_lru, &dentry_unused); |
494 | dentry_stat.nr_unused++; | |
1da177e4 LT |
495 | } |
496 | spin_unlock(&dcache_lock); | |
497 | } | |
498 | ||
499 | /* | |
500 | * Shrink the dcache for the specified super block. | |
501 | * This allows us to unmount a device without disturbing | |
502 | * the dcache for the other devices. | |
503 | * | |
504 | * This implementation makes just two traversals of the | |
505 | * unused list. On the first pass we move the selected | |
506 | * dentries to the most recent end, and on the second | |
507 | * pass we free them. The second pass must restart after | |
508 | * each dput(), but since the target dentries are all at | |
509 | * the end, it's really just a single traversal. | |
510 | */ | |
511 | ||
512 | /** | |
513 | * shrink_dcache_sb - shrink dcache for a superblock | |
514 | * @sb: superblock | |
515 | * | |
516 | * Shrink the dcache for the specified super block. This | |
517 | * is used to free the dcache before unmounting a file | |
518 | * system | |
519 | */ | |
520 | ||
521 | void shrink_dcache_sb(struct super_block * sb) | |
522 | { | |
523 | struct list_head *tmp, *next; | |
524 | struct dentry *dentry; | |
525 | ||
526 | /* | |
527 | * Pass one ... move the dentries for the specified | |
528 | * superblock to the most recent end of the unused list. | |
529 | */ | |
530 | spin_lock(&dcache_lock); | |
0cdca3f9 | 531 | list_for_each_safe(tmp, next, &dentry_unused) { |
1da177e4 LT |
532 | dentry = list_entry(tmp, struct dentry, d_lru); |
533 | if (dentry->d_sb != sb) | |
534 | continue; | |
1bfba4e8 | 535 | list_move(tmp, &dentry_unused); |
1da177e4 LT |
536 | } |
537 | ||
538 | /* | |
539 | * Pass two ... free the dentries for this superblock. | |
540 | */ | |
541 | repeat: | |
0cdca3f9 | 542 | list_for_each_safe(tmp, next, &dentry_unused) { |
1da177e4 LT |
543 | dentry = list_entry(tmp, struct dentry, d_lru); |
544 | if (dentry->d_sb != sb) | |
545 | continue; | |
546 | dentry_stat.nr_unused--; | |
547 | list_del_init(tmp); | |
548 | spin_lock(&dentry->d_lock); | |
549 | if (atomic_read(&dentry->d_count)) { | |
550 | spin_unlock(&dentry->d_lock); | |
551 | continue; | |
552 | } | |
553 | prune_one_dentry(dentry); | |
2ab13460 | 554 | cond_resched_lock(&dcache_lock); |
1da177e4 LT |
555 | goto repeat; |
556 | } | |
557 | spin_unlock(&dcache_lock); | |
558 | } | |
559 | ||
c636ebdb DH |
560 | /* |
561 | * destroy a single subtree of dentries for unmount | |
562 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
563 | * locking | |
564 | */ | |
565 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
566 | { | |
567 | struct dentry *parent; | |
f8713576 | 568 | unsigned detached = 0; |
c636ebdb DH |
569 | |
570 | BUG_ON(!IS_ROOT(dentry)); | |
571 | ||
572 | /* detach this root from the system */ | |
573 | spin_lock(&dcache_lock); | |
574 | if (!list_empty(&dentry->d_lru)) { | |
575 | dentry_stat.nr_unused--; | |
576 | list_del_init(&dentry->d_lru); | |
577 | } | |
578 | __d_drop(dentry); | |
579 | spin_unlock(&dcache_lock); | |
580 | ||
581 | for (;;) { | |
582 | /* descend to the first leaf in the current subtree */ | |
583 | while (!list_empty(&dentry->d_subdirs)) { | |
584 | struct dentry *loop; | |
585 | ||
586 | /* this is a branch with children - detach all of them | |
587 | * from the system in one go */ | |
588 | spin_lock(&dcache_lock); | |
589 | list_for_each_entry(loop, &dentry->d_subdirs, | |
590 | d_u.d_child) { | |
591 | if (!list_empty(&loop->d_lru)) { | |
592 | dentry_stat.nr_unused--; | |
593 | list_del_init(&loop->d_lru); | |
594 | } | |
595 | ||
596 | __d_drop(loop); | |
597 | cond_resched_lock(&dcache_lock); | |
598 | } | |
599 | spin_unlock(&dcache_lock); | |
600 | ||
601 | /* move to the first child */ | |
602 | dentry = list_entry(dentry->d_subdirs.next, | |
603 | struct dentry, d_u.d_child); | |
604 | } | |
605 | ||
606 | /* consume the dentries from this leaf up through its parents | |
607 | * until we find one with children or run out altogether */ | |
608 | do { | |
609 | struct inode *inode; | |
610 | ||
611 | if (atomic_read(&dentry->d_count) != 0) { | |
612 | printk(KERN_ERR | |
613 | "BUG: Dentry %p{i=%lx,n=%s}" | |
614 | " still in use (%d)" | |
615 | " [unmount of %s %s]\n", | |
616 | dentry, | |
617 | dentry->d_inode ? | |
618 | dentry->d_inode->i_ino : 0UL, | |
619 | dentry->d_name.name, | |
620 | atomic_read(&dentry->d_count), | |
621 | dentry->d_sb->s_type->name, | |
622 | dentry->d_sb->s_id); | |
623 | BUG(); | |
624 | } | |
625 | ||
626 | parent = dentry->d_parent; | |
627 | if (parent == dentry) | |
628 | parent = NULL; | |
629 | else | |
630 | atomic_dec(&parent->d_count); | |
631 | ||
632 | list_del(&dentry->d_u.d_child); | |
f8713576 | 633 | detached++; |
c636ebdb DH |
634 | |
635 | inode = dentry->d_inode; | |
636 | if (inode) { | |
637 | dentry->d_inode = NULL; | |
638 | list_del_init(&dentry->d_alias); | |
639 | if (dentry->d_op && dentry->d_op->d_iput) | |
640 | dentry->d_op->d_iput(dentry, inode); | |
641 | else | |
642 | iput(inode); | |
643 | } | |
644 | ||
645 | d_free(dentry); | |
646 | ||
647 | /* finished when we fall off the top of the tree, | |
648 | * otherwise we ascend to the parent and move to the | |
649 | * next sibling if there is one */ | |
650 | if (!parent) | |
f8713576 | 651 | goto out; |
c636ebdb DH |
652 | |
653 | dentry = parent; | |
654 | ||
655 | } while (list_empty(&dentry->d_subdirs)); | |
656 | ||
657 | dentry = list_entry(dentry->d_subdirs.next, | |
658 | struct dentry, d_u.d_child); | |
659 | } | |
f8713576 DH |
660 | out: |
661 | /* several dentries were freed, need to correct nr_dentry */ | |
662 | spin_lock(&dcache_lock); | |
663 | dentry_stat.nr_dentry -= detached; | |
664 | spin_unlock(&dcache_lock); | |
c636ebdb DH |
665 | } |
666 | ||
667 | /* | |
668 | * destroy the dentries attached to a superblock on unmounting | |
669 | * - we don't need to use dentry->d_lock, and only need dcache_lock when | |
670 | * removing the dentry from the system lists and hashes because: | |
671 | * - the superblock is detached from all mountings and open files, so the | |
672 | * dentry trees will not be rearranged by the VFS | |
673 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
674 | * any dentries belonging to this superblock that it comes across | |
675 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
676 | * in this superblock | |
677 | */ | |
678 | void shrink_dcache_for_umount(struct super_block *sb) | |
679 | { | |
680 | struct dentry *dentry; | |
681 | ||
682 | if (down_read_trylock(&sb->s_umount)) | |
683 | BUG(); | |
684 | ||
685 | dentry = sb->s_root; | |
686 | sb->s_root = NULL; | |
687 | atomic_dec(&dentry->d_count); | |
688 | shrink_dcache_for_umount_subtree(dentry); | |
689 | ||
690 | while (!hlist_empty(&sb->s_anon)) { | |
691 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); | |
692 | shrink_dcache_for_umount_subtree(dentry); | |
693 | } | |
694 | } | |
695 | ||
1da177e4 LT |
696 | /* |
697 | * Search for at least 1 mount point in the dentry's subdirs. | |
698 | * We descend to the next level whenever the d_subdirs | |
699 | * list is non-empty and continue searching. | |
700 | */ | |
701 | ||
702 | /** | |
703 | * have_submounts - check for mounts over a dentry | |
704 | * @parent: dentry to check. | |
705 | * | |
706 | * Return true if the parent or its subdirectories contain | |
707 | * a mount point | |
708 | */ | |
709 | ||
710 | int have_submounts(struct dentry *parent) | |
711 | { | |
712 | struct dentry *this_parent = parent; | |
713 | struct list_head *next; | |
714 | ||
715 | spin_lock(&dcache_lock); | |
716 | if (d_mountpoint(parent)) | |
717 | goto positive; | |
718 | repeat: | |
719 | next = this_parent->d_subdirs.next; | |
720 | resume: | |
721 | while (next != &this_parent->d_subdirs) { | |
722 | struct list_head *tmp = next; | |
5160ee6f | 723 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
724 | next = tmp->next; |
725 | /* Have we found a mount point ? */ | |
726 | if (d_mountpoint(dentry)) | |
727 | goto positive; | |
728 | if (!list_empty(&dentry->d_subdirs)) { | |
729 | this_parent = dentry; | |
730 | goto repeat; | |
731 | } | |
732 | } | |
733 | /* | |
734 | * All done at this level ... ascend and resume the search. | |
735 | */ | |
736 | if (this_parent != parent) { | |
5160ee6f | 737 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
738 | this_parent = this_parent->d_parent; |
739 | goto resume; | |
740 | } | |
741 | spin_unlock(&dcache_lock); | |
742 | return 0; /* No mount points found in tree */ | |
743 | positive: | |
744 | spin_unlock(&dcache_lock); | |
745 | return 1; | |
746 | } | |
747 | ||
748 | /* | |
749 | * Search the dentry child list for the specified parent, | |
750 | * and move any unused dentries to the end of the unused | |
751 | * list for prune_dcache(). We descend to the next level | |
752 | * whenever the d_subdirs list is non-empty and continue | |
753 | * searching. | |
754 | * | |
755 | * It returns zero iff there are no unused children, | |
756 | * otherwise it returns the number of children moved to | |
757 | * the end of the unused list. This may not be the total | |
758 | * number of unused children, because select_parent can | |
759 | * drop the lock and return early due to latency | |
760 | * constraints. | |
761 | */ | |
762 | static int select_parent(struct dentry * parent) | |
763 | { | |
764 | struct dentry *this_parent = parent; | |
765 | struct list_head *next; | |
766 | int found = 0; | |
767 | ||
768 | spin_lock(&dcache_lock); | |
769 | repeat: | |
770 | next = this_parent->d_subdirs.next; | |
771 | resume: | |
772 | while (next != &this_parent->d_subdirs) { | |
773 | struct list_head *tmp = next; | |
5160ee6f | 774 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
775 | next = tmp->next; |
776 | ||
777 | if (!list_empty(&dentry->d_lru)) { | |
778 | dentry_stat.nr_unused--; | |
779 | list_del_init(&dentry->d_lru); | |
780 | } | |
781 | /* | |
782 | * move only zero ref count dentries to the end | |
783 | * of the unused list for prune_dcache | |
784 | */ | |
785 | if (!atomic_read(&dentry->d_count)) { | |
8e13059a | 786 | list_add_tail(&dentry->d_lru, &dentry_unused); |
1da177e4 LT |
787 | dentry_stat.nr_unused++; |
788 | found++; | |
789 | } | |
790 | ||
791 | /* | |
792 | * We can return to the caller if we have found some (this | |
793 | * ensures forward progress). We'll be coming back to find | |
794 | * the rest. | |
795 | */ | |
796 | if (found && need_resched()) | |
797 | goto out; | |
798 | ||
799 | /* | |
800 | * Descend a level if the d_subdirs list is non-empty. | |
801 | */ | |
802 | if (!list_empty(&dentry->d_subdirs)) { | |
803 | this_parent = dentry; | |
1da177e4 LT |
804 | goto repeat; |
805 | } | |
806 | } | |
807 | /* | |
808 | * All done at this level ... ascend and resume the search. | |
809 | */ | |
810 | if (this_parent != parent) { | |
5160ee6f | 811 | next = this_parent->d_u.d_child.next; |
1da177e4 | 812 | this_parent = this_parent->d_parent; |
1da177e4 LT |
813 | goto resume; |
814 | } | |
815 | out: | |
816 | spin_unlock(&dcache_lock); | |
817 | return found; | |
818 | } | |
819 | ||
820 | /** | |
821 | * shrink_dcache_parent - prune dcache | |
822 | * @parent: parent of entries to prune | |
823 | * | |
824 | * Prune the dcache to remove unused children of the parent dentry. | |
825 | */ | |
826 | ||
827 | void shrink_dcache_parent(struct dentry * parent) | |
828 | { | |
829 | int found; | |
830 | ||
831 | while ((found = select_parent(parent)) != 0) | |
0feae5c4 | 832 | prune_dcache(found, parent->d_sb); |
1da177e4 LT |
833 | } |
834 | ||
1da177e4 LT |
835 | /* |
836 | * Scan `nr' dentries and return the number which remain. | |
837 | * | |
838 | * We need to avoid reentering the filesystem if the caller is performing a | |
839 | * GFP_NOFS allocation attempt. One example deadlock is: | |
840 | * | |
841 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> | |
842 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> | |
843 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. | |
844 | * | |
845 | * In this case we return -1 to tell the caller that we baled. | |
846 | */ | |
27496a8c | 847 | static int shrink_dcache_memory(int nr, gfp_t gfp_mask) |
1da177e4 LT |
848 | { |
849 | if (nr) { | |
850 | if (!(gfp_mask & __GFP_FS)) | |
851 | return -1; | |
0feae5c4 | 852 | prune_dcache(nr, NULL); |
1da177e4 LT |
853 | } |
854 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; | |
855 | } | |
856 | ||
857 | /** | |
858 | * d_alloc - allocate a dcache entry | |
859 | * @parent: parent of entry to allocate | |
860 | * @name: qstr of the name | |
861 | * | |
862 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
863 | * available. On a success the dentry is returned. The name passed in is | |
864 | * copied and the copy passed in may be reused after this call. | |
865 | */ | |
866 | ||
867 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
868 | { | |
869 | struct dentry *dentry; | |
870 | char *dname; | |
871 | ||
872 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); | |
873 | if (!dentry) | |
874 | return NULL; | |
875 | ||
876 | if (name->len > DNAME_INLINE_LEN-1) { | |
877 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
878 | if (!dname) { | |
879 | kmem_cache_free(dentry_cache, dentry); | |
880 | return NULL; | |
881 | } | |
882 | } else { | |
883 | dname = dentry->d_iname; | |
884 | } | |
885 | dentry->d_name.name = dname; | |
886 | ||
887 | dentry->d_name.len = name->len; | |
888 | dentry->d_name.hash = name->hash; | |
889 | memcpy(dname, name->name, name->len); | |
890 | dname[name->len] = 0; | |
891 | ||
892 | atomic_set(&dentry->d_count, 1); | |
893 | dentry->d_flags = DCACHE_UNHASHED; | |
894 | spin_lock_init(&dentry->d_lock); | |
895 | dentry->d_inode = NULL; | |
896 | dentry->d_parent = NULL; | |
897 | dentry->d_sb = NULL; | |
898 | dentry->d_op = NULL; | |
899 | dentry->d_fsdata = NULL; | |
900 | dentry->d_mounted = 0; | |
47ba87e0 | 901 | #ifdef CONFIG_PROFILING |
1da177e4 | 902 | dentry->d_cookie = NULL; |
47ba87e0 | 903 | #endif |
1da177e4 LT |
904 | INIT_HLIST_NODE(&dentry->d_hash); |
905 | INIT_LIST_HEAD(&dentry->d_lru); | |
906 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
907 | INIT_LIST_HEAD(&dentry->d_alias); | |
908 | ||
909 | if (parent) { | |
910 | dentry->d_parent = dget(parent); | |
911 | dentry->d_sb = parent->d_sb; | |
912 | } else { | |
5160ee6f | 913 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1da177e4 LT |
914 | } |
915 | ||
916 | spin_lock(&dcache_lock); | |
917 | if (parent) | |
5160ee6f | 918 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1da177e4 LT |
919 | dentry_stat.nr_dentry++; |
920 | spin_unlock(&dcache_lock); | |
921 | ||
922 | return dentry; | |
923 | } | |
924 | ||
925 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) | |
926 | { | |
927 | struct qstr q; | |
928 | ||
929 | q.name = name; | |
930 | q.len = strlen(name); | |
931 | q.hash = full_name_hash(q.name, q.len); | |
932 | return d_alloc(parent, &q); | |
933 | } | |
934 | ||
935 | /** | |
936 | * d_instantiate - fill in inode information for a dentry | |
937 | * @entry: dentry to complete | |
938 | * @inode: inode to attach to this dentry | |
939 | * | |
940 | * Fill in inode information in the entry. | |
941 | * | |
942 | * This turns negative dentries into productive full members | |
943 | * of society. | |
944 | * | |
945 | * NOTE! This assumes that the inode count has been incremented | |
946 | * (or otherwise set) by the caller to indicate that it is now | |
947 | * in use by the dcache. | |
948 | */ | |
949 | ||
950 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
951 | { | |
28133c7b | 952 | BUG_ON(!list_empty(&entry->d_alias)); |
1da177e4 LT |
953 | spin_lock(&dcache_lock); |
954 | if (inode) | |
955 | list_add(&entry->d_alias, &inode->i_dentry); | |
956 | entry->d_inode = inode; | |
c32ccd87 | 957 | fsnotify_d_instantiate(entry, inode); |
1da177e4 LT |
958 | spin_unlock(&dcache_lock); |
959 | security_d_instantiate(entry, inode); | |
960 | } | |
961 | ||
962 | /** | |
963 | * d_instantiate_unique - instantiate a non-aliased dentry | |
964 | * @entry: dentry to instantiate | |
965 | * @inode: inode to attach to this dentry | |
966 | * | |
967 | * Fill in inode information in the entry. On success, it returns NULL. | |
968 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 969 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
970 | * |
971 | * Note that in order to avoid conflicts with rename() etc, the caller | |
972 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
973 | * |
974 | * This also assumes that the inode count has been incremented | |
975 | * (or otherwise set) by the caller to indicate that it is now | |
976 | * in use by the dcache. | |
1da177e4 | 977 | */ |
770bfad8 DH |
978 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
979 | struct inode *inode) | |
1da177e4 LT |
980 | { |
981 | struct dentry *alias; | |
982 | int len = entry->d_name.len; | |
983 | const char *name = entry->d_name.name; | |
984 | unsigned int hash = entry->d_name.hash; | |
985 | ||
770bfad8 DH |
986 | if (!inode) { |
987 | entry->d_inode = NULL; | |
988 | return NULL; | |
989 | } | |
990 | ||
1da177e4 LT |
991 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
992 | struct qstr *qstr = &alias->d_name; | |
993 | ||
994 | if (qstr->hash != hash) | |
995 | continue; | |
996 | if (alias->d_parent != entry->d_parent) | |
997 | continue; | |
998 | if (qstr->len != len) | |
999 | continue; | |
1000 | if (memcmp(qstr->name, name, len)) | |
1001 | continue; | |
1002 | dget_locked(alias); | |
1da177e4 LT |
1003 | return alias; |
1004 | } | |
770bfad8 | 1005 | |
1da177e4 | 1006 | list_add(&entry->d_alias, &inode->i_dentry); |
1da177e4 | 1007 | entry->d_inode = inode; |
c32ccd87 | 1008 | fsnotify_d_instantiate(entry, inode); |
1da177e4 LT |
1009 | return NULL; |
1010 | } | |
770bfad8 DH |
1011 | |
1012 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1013 | { | |
1014 | struct dentry *result; | |
1015 | ||
1016 | BUG_ON(!list_empty(&entry->d_alias)); | |
1017 | ||
1018 | spin_lock(&dcache_lock); | |
1019 | result = __d_instantiate_unique(entry, inode); | |
1020 | spin_unlock(&dcache_lock); | |
1021 | ||
1022 | if (!result) { | |
1023 | security_d_instantiate(entry, inode); | |
1024 | return NULL; | |
1025 | } | |
1026 | ||
1027 | BUG_ON(!d_unhashed(result)); | |
1028 | iput(inode); | |
1029 | return result; | |
1030 | } | |
1031 | ||
1da177e4 LT |
1032 | EXPORT_SYMBOL(d_instantiate_unique); |
1033 | ||
1034 | /** | |
1035 | * d_alloc_root - allocate root dentry | |
1036 | * @root_inode: inode to allocate the root for | |
1037 | * | |
1038 | * Allocate a root ("/") dentry for the inode given. The inode is | |
1039 | * instantiated and returned. %NULL is returned if there is insufficient | |
1040 | * memory or the inode passed is %NULL. | |
1041 | */ | |
1042 | ||
1043 | struct dentry * d_alloc_root(struct inode * root_inode) | |
1044 | { | |
1045 | struct dentry *res = NULL; | |
1046 | ||
1047 | if (root_inode) { | |
1048 | static const struct qstr name = { .name = "/", .len = 1 }; | |
1049 | ||
1050 | res = d_alloc(NULL, &name); | |
1051 | if (res) { | |
1052 | res->d_sb = root_inode->i_sb; | |
1053 | res->d_parent = res; | |
1054 | d_instantiate(res, root_inode); | |
1055 | } | |
1056 | } | |
1057 | return res; | |
1058 | } | |
1059 | ||
1060 | static inline struct hlist_head *d_hash(struct dentry *parent, | |
1061 | unsigned long hash) | |
1062 | { | |
1063 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; | |
1064 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); | |
1065 | return dentry_hashtable + (hash & D_HASHMASK); | |
1066 | } | |
1067 | ||
1068 | /** | |
1069 | * d_alloc_anon - allocate an anonymous dentry | |
1070 | * @inode: inode to allocate the dentry for | |
1071 | * | |
1072 | * This is similar to d_alloc_root. It is used by filesystems when | |
1073 | * creating a dentry for a given inode, often in the process of | |
1074 | * mapping a filehandle to a dentry. The returned dentry may be | |
1075 | * anonymous, or may have a full name (if the inode was already | |
1076 | * in the cache). The file system may need to make further | |
1077 | * efforts to connect this dentry into the dcache properly. | |
1078 | * | |
1079 | * When called on a directory inode, we must ensure that | |
1080 | * the inode only ever has one dentry. If a dentry is | |
1081 | * found, that is returned instead of allocating a new one. | |
1082 | * | |
1083 | * On successful return, the reference to the inode has been transferred | |
1084 | * to the dentry. If %NULL is returned (indicating kmalloc failure), | |
1085 | * the reference on the inode has not been released. | |
1086 | */ | |
1087 | ||
1088 | struct dentry * d_alloc_anon(struct inode *inode) | |
1089 | { | |
1090 | static const struct qstr anonstring = { .name = "" }; | |
1091 | struct dentry *tmp; | |
1092 | struct dentry *res; | |
1093 | ||
1094 | if ((res = d_find_alias(inode))) { | |
1095 | iput(inode); | |
1096 | return res; | |
1097 | } | |
1098 | ||
1099 | tmp = d_alloc(NULL, &anonstring); | |
1100 | if (!tmp) | |
1101 | return NULL; | |
1102 | ||
1103 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ | |
1104 | ||
1105 | spin_lock(&dcache_lock); | |
1106 | res = __d_find_alias(inode, 0); | |
1107 | if (!res) { | |
1108 | /* attach a disconnected dentry */ | |
1109 | res = tmp; | |
1110 | tmp = NULL; | |
1111 | spin_lock(&res->d_lock); | |
1112 | res->d_sb = inode->i_sb; | |
1113 | res->d_parent = res; | |
1114 | res->d_inode = inode; | |
1115 | res->d_flags |= DCACHE_DISCONNECTED; | |
1116 | res->d_flags &= ~DCACHE_UNHASHED; | |
1117 | list_add(&res->d_alias, &inode->i_dentry); | |
1118 | hlist_add_head(&res->d_hash, &inode->i_sb->s_anon); | |
1119 | spin_unlock(&res->d_lock); | |
1120 | ||
1121 | inode = NULL; /* don't drop reference */ | |
1122 | } | |
1123 | spin_unlock(&dcache_lock); | |
1124 | ||
1125 | if (inode) | |
1126 | iput(inode); | |
1127 | if (tmp) | |
1128 | dput(tmp); | |
1129 | return res; | |
1130 | } | |
1131 | ||
1132 | ||
1133 | /** | |
1134 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1135 | * @inode: the inode which may have a disconnected dentry | |
1136 | * @dentry: a negative dentry which we want to point to the inode. | |
1137 | * | |
1138 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1139 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1140 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1141 | * | |
1142 | * This is needed in the lookup routine of any filesystem that is exportable | |
1143 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1144 | * | |
1145 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1146 | * is returned. This matches the expected return value of ->lookup. | |
1147 | * | |
1148 | */ | |
1149 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1150 | { | |
1151 | struct dentry *new = NULL; | |
1152 | ||
21c0d8fd | 1153 | if (inode && S_ISDIR(inode->i_mode)) { |
1da177e4 LT |
1154 | spin_lock(&dcache_lock); |
1155 | new = __d_find_alias(inode, 1); | |
1156 | if (new) { | |
1157 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); | |
c32ccd87 | 1158 | fsnotify_d_instantiate(new, inode); |
1da177e4 LT |
1159 | spin_unlock(&dcache_lock); |
1160 | security_d_instantiate(new, inode); | |
1161 | d_rehash(dentry); | |
1162 | d_move(new, dentry); | |
1163 | iput(inode); | |
1164 | } else { | |
1165 | /* d_instantiate takes dcache_lock, so we do it by hand */ | |
1166 | list_add(&dentry->d_alias, &inode->i_dentry); | |
1167 | dentry->d_inode = inode; | |
c32ccd87 | 1168 | fsnotify_d_instantiate(dentry, inode); |
1da177e4 LT |
1169 | spin_unlock(&dcache_lock); |
1170 | security_d_instantiate(dentry, inode); | |
1171 | d_rehash(dentry); | |
1172 | } | |
1173 | } else | |
1174 | d_add(dentry, inode); | |
1175 | return new; | |
1176 | } | |
1177 | ||
1178 | ||
1179 | /** | |
1180 | * d_lookup - search for a dentry | |
1181 | * @parent: parent dentry | |
1182 | * @name: qstr of name we wish to find | |
1183 | * | |
1184 | * Searches the children of the parent dentry for the name in question. If | |
1185 | * the dentry is found its reference count is incremented and the dentry | |
1186 | * is returned. The caller must use d_put to free the entry when it has | |
1187 | * finished using it. %NULL is returned on failure. | |
1188 | * | |
1189 | * __d_lookup is dcache_lock free. The hash list is protected using RCU. | |
1190 | * Memory barriers are used while updating and doing lockless traversal. | |
1191 | * To avoid races with d_move while rename is happening, d_lock is used. | |
1192 | * | |
1193 | * Overflows in memcmp(), while d_move, are avoided by keeping the length | |
1194 | * and name pointer in one structure pointed by d_qstr. | |
1195 | * | |
1196 | * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while | |
1197 | * lookup is going on. | |
1198 | * | |
1199 | * dentry_unused list is not updated even if lookup finds the required dentry | |
1200 | * in there. It is updated in places such as prune_dcache, shrink_dcache_sb, | |
1201 | * select_parent and __dget_locked. This laziness saves lookup from dcache_lock | |
1202 | * acquisition. | |
1203 | * | |
1204 | * d_lookup() is protected against the concurrent renames in some unrelated | |
1205 | * directory using the seqlockt_t rename_lock. | |
1206 | */ | |
1207 | ||
1208 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) | |
1209 | { | |
1210 | struct dentry * dentry = NULL; | |
1211 | unsigned long seq; | |
1212 | ||
1213 | do { | |
1214 | seq = read_seqbegin(&rename_lock); | |
1215 | dentry = __d_lookup(parent, name); | |
1216 | if (dentry) | |
1217 | break; | |
1218 | } while (read_seqretry(&rename_lock, seq)); | |
1219 | return dentry; | |
1220 | } | |
1221 | ||
1222 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) | |
1223 | { | |
1224 | unsigned int len = name->len; | |
1225 | unsigned int hash = name->hash; | |
1226 | const unsigned char *str = name->name; | |
1227 | struct hlist_head *head = d_hash(parent,hash); | |
1228 | struct dentry *found = NULL; | |
1229 | struct hlist_node *node; | |
665a7583 | 1230 | struct dentry *dentry; |
1da177e4 LT |
1231 | |
1232 | rcu_read_lock(); | |
1233 | ||
665a7583 | 1234 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
1da177e4 LT |
1235 | struct qstr *qstr; |
1236 | ||
1da177e4 LT |
1237 | if (dentry->d_name.hash != hash) |
1238 | continue; | |
1239 | if (dentry->d_parent != parent) | |
1240 | continue; | |
1241 | ||
1242 | spin_lock(&dentry->d_lock); | |
1243 | ||
1244 | /* | |
1245 | * Recheck the dentry after taking the lock - d_move may have | |
1246 | * changed things. Don't bother checking the hash because we're | |
1247 | * about to compare the whole name anyway. | |
1248 | */ | |
1249 | if (dentry->d_parent != parent) | |
1250 | goto next; | |
1251 | ||
1252 | /* | |
1253 | * It is safe to compare names since d_move() cannot | |
1254 | * change the qstr (protected by d_lock). | |
1255 | */ | |
1256 | qstr = &dentry->d_name; | |
1257 | if (parent->d_op && parent->d_op->d_compare) { | |
1258 | if (parent->d_op->d_compare(parent, qstr, name)) | |
1259 | goto next; | |
1260 | } else { | |
1261 | if (qstr->len != len) | |
1262 | goto next; | |
1263 | if (memcmp(qstr->name, str, len)) | |
1264 | goto next; | |
1265 | } | |
1266 | ||
1267 | if (!d_unhashed(dentry)) { | |
1268 | atomic_inc(&dentry->d_count); | |
1269 | found = dentry; | |
1270 | } | |
1271 | spin_unlock(&dentry->d_lock); | |
1272 | break; | |
1273 | next: | |
1274 | spin_unlock(&dentry->d_lock); | |
1275 | } | |
1276 | rcu_read_unlock(); | |
1277 | ||
1278 | return found; | |
1279 | } | |
1280 | ||
3e7e241f EB |
1281 | /** |
1282 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
1283 | * @dir: Directory to search in | |
1284 | * @name: qstr of name we wish to find | |
1285 | * | |
1286 | * On hash failure or on lookup failure NULL is returned. | |
1287 | */ | |
1288 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
1289 | { | |
1290 | struct dentry *dentry = NULL; | |
1291 | ||
1292 | /* | |
1293 | * Check for a fs-specific hash function. Note that we must | |
1294 | * calculate the standard hash first, as the d_op->d_hash() | |
1295 | * routine may choose to leave the hash value unchanged. | |
1296 | */ | |
1297 | name->hash = full_name_hash(name->name, name->len); | |
1298 | if (dir->d_op && dir->d_op->d_hash) { | |
1299 | if (dir->d_op->d_hash(dir, name) < 0) | |
1300 | goto out; | |
1301 | } | |
1302 | dentry = d_lookup(dir, name); | |
1303 | out: | |
1304 | return dentry; | |
1305 | } | |
1306 | ||
1da177e4 LT |
1307 | /** |
1308 | * d_validate - verify dentry provided from insecure source | |
1309 | * @dentry: The dentry alleged to be valid child of @dparent | |
1310 | * @dparent: The parent dentry (known to be valid) | |
1311 | * @hash: Hash of the dentry | |
1312 | * @len: Length of the name | |
1313 | * | |
1314 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
1315 | * This is used by ncpfs in its readdir implementation. | |
1316 | * Zero is returned in the dentry is invalid. | |
1317 | */ | |
1318 | ||
1319 | int d_validate(struct dentry *dentry, struct dentry *dparent) | |
1320 | { | |
1321 | struct hlist_head *base; | |
1322 | struct hlist_node *lhp; | |
1323 | ||
1324 | /* Check whether the ptr might be valid at all.. */ | |
1325 | if (!kmem_ptr_validate(dentry_cache, dentry)) | |
1326 | goto out; | |
1327 | ||
1328 | if (dentry->d_parent != dparent) | |
1329 | goto out; | |
1330 | ||
1331 | spin_lock(&dcache_lock); | |
1332 | base = d_hash(dparent, dentry->d_name.hash); | |
1333 | hlist_for_each(lhp,base) { | |
665a7583 | 1334 | /* hlist_for_each_entry_rcu() not required for d_hash list |
1da177e4 LT |
1335 | * as it is parsed under dcache_lock |
1336 | */ | |
1337 | if (dentry == hlist_entry(lhp, struct dentry, d_hash)) { | |
1338 | __dget_locked(dentry); | |
1339 | spin_unlock(&dcache_lock); | |
1340 | return 1; | |
1341 | } | |
1342 | } | |
1343 | spin_unlock(&dcache_lock); | |
1344 | out: | |
1345 | return 0; | |
1346 | } | |
1347 | ||
1348 | /* | |
1349 | * When a file is deleted, we have two options: | |
1350 | * - turn this dentry into a negative dentry | |
1351 | * - unhash this dentry and free it. | |
1352 | * | |
1353 | * Usually, we want to just turn this into | |
1354 | * a negative dentry, but if anybody else is | |
1355 | * currently using the dentry or the inode | |
1356 | * we can't do that and we fall back on removing | |
1357 | * it from the hash queues and waiting for | |
1358 | * it to be deleted later when it has no users | |
1359 | */ | |
1360 | ||
1361 | /** | |
1362 | * d_delete - delete a dentry | |
1363 | * @dentry: The dentry to delete | |
1364 | * | |
1365 | * Turn the dentry into a negative dentry if possible, otherwise | |
1366 | * remove it from the hash queues so it can be deleted later | |
1367 | */ | |
1368 | ||
1369 | void d_delete(struct dentry * dentry) | |
1370 | { | |
7a91bf7f | 1371 | int isdir = 0; |
1da177e4 LT |
1372 | /* |
1373 | * Are we the only user? | |
1374 | */ | |
1375 | spin_lock(&dcache_lock); | |
1376 | spin_lock(&dentry->d_lock); | |
7a91bf7f | 1377 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
1da177e4 LT |
1378 | if (atomic_read(&dentry->d_count) == 1) { |
1379 | dentry_iput(dentry); | |
7a91bf7f | 1380 | fsnotify_nameremove(dentry, isdir); |
7a2bd3f7 AG |
1381 | |
1382 | /* remove this and other inotify debug checks after 2.6.18 */ | |
1383 | dentry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED; | |
1da177e4 LT |
1384 | return; |
1385 | } | |
1386 | ||
1387 | if (!d_unhashed(dentry)) | |
1388 | __d_drop(dentry); | |
1389 | ||
1390 | spin_unlock(&dentry->d_lock); | |
1391 | spin_unlock(&dcache_lock); | |
7a91bf7f JM |
1392 | |
1393 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 LT |
1394 | } |
1395 | ||
1396 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) | |
1397 | { | |
1398 | ||
1399 | entry->d_flags &= ~DCACHE_UNHASHED; | |
1400 | hlist_add_head_rcu(&entry->d_hash, list); | |
1401 | } | |
1402 | ||
770bfad8 DH |
1403 | static void _d_rehash(struct dentry * entry) |
1404 | { | |
1405 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
1406 | } | |
1407 | ||
1da177e4 LT |
1408 | /** |
1409 | * d_rehash - add an entry back to the hash | |
1410 | * @entry: dentry to add to the hash | |
1411 | * | |
1412 | * Adds a dentry to the hash according to its name. | |
1413 | */ | |
1414 | ||
1415 | void d_rehash(struct dentry * entry) | |
1416 | { | |
1da177e4 LT |
1417 | spin_lock(&dcache_lock); |
1418 | spin_lock(&entry->d_lock); | |
770bfad8 | 1419 | _d_rehash(entry); |
1da177e4 LT |
1420 | spin_unlock(&entry->d_lock); |
1421 | spin_unlock(&dcache_lock); | |
1422 | } | |
1423 | ||
1424 | #define do_switch(x,y) do { \ | |
1425 | __typeof__ (x) __tmp = x; \ | |
1426 | x = y; y = __tmp; } while (0) | |
1427 | ||
1428 | /* | |
1429 | * When switching names, the actual string doesn't strictly have to | |
1430 | * be preserved in the target - because we're dropping the target | |
1431 | * anyway. As such, we can just do a simple memcpy() to copy over | |
1432 | * the new name before we switch. | |
1433 | * | |
1434 | * Note that we have to be a lot more careful about getting the hash | |
1435 | * switched - we have to switch the hash value properly even if it | |
1436 | * then no longer matches the actual (corrupted) string of the target. | |
1437 | * The hash value has to match the hash queue that the dentry is on.. | |
1438 | */ | |
1439 | static void switch_names(struct dentry *dentry, struct dentry *target) | |
1440 | { | |
1441 | if (dname_external(target)) { | |
1442 | if (dname_external(dentry)) { | |
1443 | /* | |
1444 | * Both external: swap the pointers | |
1445 | */ | |
1446 | do_switch(target->d_name.name, dentry->d_name.name); | |
1447 | } else { | |
1448 | /* | |
1449 | * dentry:internal, target:external. Steal target's | |
1450 | * storage and make target internal. | |
1451 | */ | |
1452 | dentry->d_name.name = target->d_name.name; | |
1453 | target->d_name.name = target->d_iname; | |
1454 | } | |
1455 | } else { | |
1456 | if (dname_external(dentry)) { | |
1457 | /* | |
1458 | * dentry:external, target:internal. Give dentry's | |
1459 | * storage to target and make dentry internal | |
1460 | */ | |
1461 | memcpy(dentry->d_iname, target->d_name.name, | |
1462 | target->d_name.len + 1); | |
1463 | target->d_name.name = dentry->d_name.name; | |
1464 | dentry->d_name.name = dentry->d_iname; | |
1465 | } else { | |
1466 | /* | |
1467 | * Both are internal. Just copy target to dentry | |
1468 | */ | |
1469 | memcpy(dentry->d_iname, target->d_name.name, | |
1470 | target->d_name.len + 1); | |
1471 | } | |
1472 | } | |
1473 | } | |
1474 | ||
1475 | /* | |
1476 | * We cannibalize "target" when moving dentry on top of it, | |
1477 | * because it's going to be thrown away anyway. We could be more | |
1478 | * polite about it, though. | |
1479 | * | |
1480 | * This forceful removal will result in ugly /proc output if | |
1481 | * somebody holds a file open that got deleted due to a rename. | |
1482 | * We could be nicer about the deleted file, and let it show | |
1483 | * up under the name it got deleted rather than the name that | |
1484 | * deleted it. | |
1485 | */ | |
1486 | ||
9eaef27b TM |
1487 | /* |
1488 | * d_move_locked - move a dentry | |
1da177e4 LT |
1489 | * @dentry: entry to move |
1490 | * @target: new dentry | |
1491 | * | |
1492 | * Update the dcache to reflect the move of a file name. Negative | |
1493 | * dcache entries should not be moved in this way. | |
1494 | */ | |
9eaef27b | 1495 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
1da177e4 LT |
1496 | { |
1497 | struct hlist_head *list; | |
1498 | ||
1499 | if (!dentry->d_inode) | |
1500 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
1501 | ||
1da177e4 LT |
1502 | write_seqlock(&rename_lock); |
1503 | /* | |
1504 | * XXXX: do we really need to take target->d_lock? | |
1505 | */ | |
1506 | if (target < dentry) { | |
1507 | spin_lock(&target->d_lock); | |
a90b9c05 | 1508 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1509 | } else { |
1510 | spin_lock(&dentry->d_lock); | |
a90b9c05 | 1511 | spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1512 | } |
1513 | ||
1514 | /* Move the dentry to the target hash queue, if on different bucket */ | |
1515 | if (dentry->d_flags & DCACHE_UNHASHED) | |
1516 | goto already_unhashed; | |
1517 | ||
1518 | hlist_del_rcu(&dentry->d_hash); | |
1519 | ||
1520 | already_unhashed: | |
1521 | list = d_hash(target->d_parent, target->d_name.hash); | |
1522 | __d_rehash(dentry, list); | |
1523 | ||
1524 | /* Unhash the target: dput() will then get rid of it */ | |
1525 | __d_drop(target); | |
1526 | ||
5160ee6f ED |
1527 | list_del(&dentry->d_u.d_child); |
1528 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
1529 | |
1530 | /* Switch the names.. */ | |
1531 | switch_names(dentry, target); | |
1532 | do_switch(dentry->d_name.len, target->d_name.len); | |
1533 | do_switch(dentry->d_name.hash, target->d_name.hash); | |
1534 | ||
1535 | /* ... and switch the parents */ | |
1536 | if (IS_ROOT(dentry)) { | |
1537 | dentry->d_parent = target->d_parent; | |
1538 | target->d_parent = target; | |
5160ee6f | 1539 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 LT |
1540 | } else { |
1541 | do_switch(dentry->d_parent, target->d_parent); | |
1542 | ||
1543 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 1544 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
1545 | } |
1546 | ||
5160ee6f | 1547 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
1da177e4 | 1548 | spin_unlock(&target->d_lock); |
c32ccd87 | 1549 | fsnotify_d_move(dentry); |
1da177e4 LT |
1550 | spin_unlock(&dentry->d_lock); |
1551 | write_sequnlock(&rename_lock); | |
9eaef27b TM |
1552 | } |
1553 | ||
1554 | /** | |
1555 | * d_move - move a dentry | |
1556 | * @dentry: entry to move | |
1557 | * @target: new dentry | |
1558 | * | |
1559 | * Update the dcache to reflect the move of a file name. Negative | |
1560 | * dcache entries should not be moved in this way. | |
1561 | */ | |
1562 | ||
1563 | void d_move(struct dentry * dentry, struct dentry * target) | |
1564 | { | |
1565 | spin_lock(&dcache_lock); | |
1566 | d_move_locked(dentry, target); | |
1da177e4 LT |
1567 | spin_unlock(&dcache_lock); |
1568 | } | |
1569 | ||
9eaef27b TM |
1570 | /* |
1571 | * Helper that returns 1 if p1 is a parent of p2, else 0 | |
1572 | */ | |
1573 | static int d_isparent(struct dentry *p1, struct dentry *p2) | |
1574 | { | |
1575 | struct dentry *p; | |
1576 | ||
1577 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1578 | if (p->d_parent == p1) | |
1579 | return 1; | |
1580 | } | |
1581 | return 0; | |
1582 | } | |
1583 | ||
1584 | /* | |
1585 | * This helper attempts to cope with remotely renamed directories | |
1586 | * | |
1587 | * It assumes that the caller is already holding | |
1588 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock | |
1589 | * | |
1590 | * Note: If ever the locking in lock_rename() changes, then please | |
1591 | * remember to update this too... | |
1592 | * | |
1593 | * On return, dcache_lock will have been unlocked. | |
1594 | */ | |
1595 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) | |
1596 | { | |
1597 | struct mutex *m1 = NULL, *m2 = NULL; | |
1598 | struct dentry *ret; | |
1599 | ||
1600 | /* If alias and dentry share a parent, then no extra locks required */ | |
1601 | if (alias->d_parent == dentry->d_parent) | |
1602 | goto out_unalias; | |
1603 | ||
1604 | /* Check for loops */ | |
1605 | ret = ERR_PTR(-ELOOP); | |
1606 | if (d_isparent(alias, dentry)) | |
1607 | goto out_err; | |
1608 | ||
1609 | /* See lock_rename() */ | |
1610 | ret = ERR_PTR(-EBUSY); | |
1611 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) | |
1612 | goto out_err; | |
1613 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
1614 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
1615 | goto out_err; | |
1616 | m2 = &alias->d_parent->d_inode->i_mutex; | |
1617 | out_unalias: | |
1618 | d_move_locked(alias, dentry); | |
1619 | ret = alias; | |
1620 | out_err: | |
1621 | spin_unlock(&dcache_lock); | |
1622 | if (m2) | |
1623 | mutex_unlock(m2); | |
1624 | if (m1) | |
1625 | mutex_unlock(m1); | |
1626 | return ret; | |
1627 | } | |
1628 | ||
770bfad8 DH |
1629 | /* |
1630 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
1631 | * named dentry in place of the dentry to be replaced. | |
1632 | */ | |
1633 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
1634 | { | |
1635 | struct dentry *dparent, *aparent; | |
1636 | ||
1637 | switch_names(dentry, anon); | |
1638 | do_switch(dentry->d_name.len, anon->d_name.len); | |
1639 | do_switch(dentry->d_name.hash, anon->d_name.hash); | |
1640 | ||
1641 | dparent = dentry->d_parent; | |
1642 | aparent = anon->d_parent; | |
1643 | ||
1644 | dentry->d_parent = (aparent == anon) ? dentry : aparent; | |
1645 | list_del(&dentry->d_u.d_child); | |
1646 | if (!IS_ROOT(dentry)) | |
1647 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); | |
1648 | else | |
1649 | INIT_LIST_HEAD(&dentry->d_u.d_child); | |
1650 | ||
1651 | anon->d_parent = (dparent == dentry) ? anon : dparent; | |
1652 | list_del(&anon->d_u.d_child); | |
1653 | if (!IS_ROOT(anon)) | |
1654 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); | |
1655 | else | |
1656 | INIT_LIST_HEAD(&anon->d_u.d_child); | |
1657 | ||
1658 | anon->d_flags &= ~DCACHE_DISCONNECTED; | |
1659 | } | |
1660 | ||
1661 | /** | |
1662 | * d_materialise_unique - introduce an inode into the tree | |
1663 | * @dentry: candidate dentry | |
1664 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
1665 | * | |
1666 | * Introduces an dentry into the tree, substituting an extant disconnected | |
1667 | * root directory alias in its place if there is one | |
1668 | */ | |
1669 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
1670 | { | |
9eaef27b | 1671 | struct dentry *actual; |
770bfad8 DH |
1672 | |
1673 | BUG_ON(!d_unhashed(dentry)); | |
1674 | ||
1675 | spin_lock(&dcache_lock); | |
1676 | ||
1677 | if (!inode) { | |
1678 | actual = dentry; | |
1679 | dentry->d_inode = NULL; | |
1680 | goto found_lock; | |
1681 | } | |
1682 | ||
9eaef27b TM |
1683 | if (S_ISDIR(inode->i_mode)) { |
1684 | struct dentry *alias; | |
1685 | ||
1686 | /* Does an aliased dentry already exist? */ | |
1687 | alias = __d_find_alias(inode, 0); | |
1688 | if (alias) { | |
1689 | actual = alias; | |
1690 | /* Is this an anonymous mountpoint that we could splice | |
1691 | * into our tree? */ | |
1692 | if (IS_ROOT(alias)) { | |
1693 | spin_lock(&alias->d_lock); | |
1694 | __d_materialise_dentry(dentry, alias); | |
1695 | __d_drop(alias); | |
1696 | goto found; | |
1697 | } | |
1698 | /* Nope, but we must(!) avoid directory aliasing */ | |
1699 | actual = __d_unalias(dentry, alias); | |
1700 | if (IS_ERR(actual)) | |
1701 | dput(alias); | |
1702 | goto out_nolock; | |
1703 | } | |
770bfad8 DH |
1704 | } |
1705 | ||
1706 | /* Add a unique reference */ | |
1707 | actual = __d_instantiate_unique(dentry, inode); | |
1708 | if (!actual) | |
1709 | actual = dentry; | |
1710 | else if (unlikely(!d_unhashed(actual))) | |
1711 | goto shouldnt_be_hashed; | |
1712 | ||
1713 | found_lock: | |
1714 | spin_lock(&actual->d_lock); | |
1715 | found: | |
1716 | _d_rehash(actual); | |
1717 | spin_unlock(&actual->d_lock); | |
1718 | spin_unlock(&dcache_lock); | |
9eaef27b | 1719 | out_nolock: |
770bfad8 DH |
1720 | if (actual == dentry) { |
1721 | security_d_instantiate(dentry, inode); | |
1722 | return NULL; | |
1723 | } | |
1724 | ||
1725 | iput(inode); | |
1726 | return actual; | |
1727 | ||
770bfad8 DH |
1728 | shouldnt_be_hashed: |
1729 | spin_unlock(&dcache_lock); | |
1730 | BUG(); | |
1731 | goto shouldnt_be_hashed; | |
1732 | } | |
1733 | ||
1da177e4 LT |
1734 | /** |
1735 | * d_path - return the path of a dentry | |
1736 | * @dentry: dentry to report | |
1737 | * @vfsmnt: vfsmnt to which the dentry belongs | |
1738 | * @root: root dentry | |
1739 | * @rootmnt: vfsmnt to which the root dentry belongs | |
1740 | * @buffer: buffer to return value in | |
1741 | * @buflen: buffer length | |
1742 | * | |
1743 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
1744 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
1745 | * | |
1746 | * Returns the buffer or an error code if the path was too long. | |
1747 | * | |
1748 | * "buflen" should be positive. Caller holds the dcache_lock. | |
1749 | */ | |
1750 | static char * __d_path( struct dentry *dentry, struct vfsmount *vfsmnt, | |
1751 | struct dentry *root, struct vfsmount *rootmnt, | |
1752 | char *buffer, int buflen) | |
1753 | { | |
1754 | char * end = buffer+buflen; | |
1755 | char * retval; | |
1756 | int namelen; | |
1757 | ||
1758 | *--end = '\0'; | |
1759 | buflen--; | |
1760 | if (!IS_ROOT(dentry) && d_unhashed(dentry)) { | |
1761 | buflen -= 10; | |
1762 | end -= 10; | |
1763 | if (buflen < 0) | |
1764 | goto Elong; | |
1765 | memcpy(end, " (deleted)", 10); | |
1766 | } | |
1767 | ||
1768 | if (buflen < 1) | |
1769 | goto Elong; | |
1770 | /* Get '/' right */ | |
1771 | retval = end-1; | |
1772 | *retval = '/'; | |
1773 | ||
1774 | for (;;) { | |
1775 | struct dentry * parent; | |
1776 | ||
1777 | if (dentry == root && vfsmnt == rootmnt) | |
1778 | break; | |
1779 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { | |
1780 | /* Global root? */ | |
1781 | spin_lock(&vfsmount_lock); | |
1782 | if (vfsmnt->mnt_parent == vfsmnt) { | |
1783 | spin_unlock(&vfsmount_lock); | |
1784 | goto global_root; | |
1785 | } | |
1786 | dentry = vfsmnt->mnt_mountpoint; | |
1787 | vfsmnt = vfsmnt->mnt_parent; | |
1788 | spin_unlock(&vfsmount_lock); | |
1789 | continue; | |
1790 | } | |
1791 | parent = dentry->d_parent; | |
1792 | prefetch(parent); | |
1793 | namelen = dentry->d_name.len; | |
1794 | buflen -= namelen + 1; | |
1795 | if (buflen < 0) | |
1796 | goto Elong; | |
1797 | end -= namelen; | |
1798 | memcpy(end, dentry->d_name.name, namelen); | |
1799 | *--end = '/'; | |
1800 | retval = end; | |
1801 | dentry = parent; | |
1802 | } | |
1803 | ||
1804 | return retval; | |
1805 | ||
1806 | global_root: | |
1807 | namelen = dentry->d_name.len; | |
1808 | buflen -= namelen; | |
1809 | if (buflen < 0) | |
1810 | goto Elong; | |
1811 | retval -= namelen-1; /* hit the slash */ | |
1812 | memcpy(retval, dentry->d_name.name, namelen); | |
1813 | return retval; | |
1814 | Elong: | |
1815 | return ERR_PTR(-ENAMETOOLONG); | |
1816 | } | |
1817 | ||
1818 | /* write full pathname into buffer and return start of pathname */ | |
1819 | char * d_path(struct dentry *dentry, struct vfsmount *vfsmnt, | |
1820 | char *buf, int buflen) | |
1821 | { | |
1822 | char *res; | |
1823 | struct vfsmount *rootmnt; | |
1824 | struct dentry *root; | |
1825 | ||
1826 | read_lock(¤t->fs->lock); | |
1827 | rootmnt = mntget(current->fs->rootmnt); | |
1828 | root = dget(current->fs->root); | |
1829 | read_unlock(¤t->fs->lock); | |
1830 | spin_lock(&dcache_lock); | |
1831 | res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen); | |
1832 | spin_unlock(&dcache_lock); | |
1833 | dput(root); | |
1834 | mntput(rootmnt); | |
1835 | return res; | |
1836 | } | |
1837 | ||
1838 | /* | |
1839 | * NOTE! The user-level library version returns a | |
1840 | * character pointer. The kernel system call just | |
1841 | * returns the length of the buffer filled (which | |
1842 | * includes the ending '\0' character), or a negative | |
1843 | * error value. So libc would do something like | |
1844 | * | |
1845 | * char *getcwd(char * buf, size_t size) | |
1846 | * { | |
1847 | * int retval; | |
1848 | * | |
1849 | * retval = sys_getcwd(buf, size); | |
1850 | * if (retval >= 0) | |
1851 | * return buf; | |
1852 | * errno = -retval; | |
1853 | * return NULL; | |
1854 | * } | |
1855 | */ | |
1856 | asmlinkage long sys_getcwd(char __user *buf, unsigned long size) | |
1857 | { | |
1858 | int error; | |
1859 | struct vfsmount *pwdmnt, *rootmnt; | |
1860 | struct dentry *pwd, *root; | |
1861 | char *page = (char *) __get_free_page(GFP_USER); | |
1862 | ||
1863 | if (!page) | |
1864 | return -ENOMEM; | |
1865 | ||
1866 | read_lock(¤t->fs->lock); | |
1867 | pwdmnt = mntget(current->fs->pwdmnt); | |
1868 | pwd = dget(current->fs->pwd); | |
1869 | rootmnt = mntget(current->fs->rootmnt); | |
1870 | root = dget(current->fs->root); | |
1871 | read_unlock(¤t->fs->lock); | |
1872 | ||
1873 | error = -ENOENT; | |
1874 | /* Has the current directory has been unlinked? */ | |
1875 | spin_lock(&dcache_lock); | |
1876 | if (pwd->d_parent == pwd || !d_unhashed(pwd)) { | |
1877 | unsigned long len; | |
1878 | char * cwd; | |
1879 | ||
1880 | cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE); | |
1881 | spin_unlock(&dcache_lock); | |
1882 | ||
1883 | error = PTR_ERR(cwd); | |
1884 | if (IS_ERR(cwd)) | |
1885 | goto out; | |
1886 | ||
1887 | error = -ERANGE; | |
1888 | len = PAGE_SIZE + page - cwd; | |
1889 | if (len <= size) { | |
1890 | error = len; | |
1891 | if (copy_to_user(buf, cwd, len)) | |
1892 | error = -EFAULT; | |
1893 | } | |
1894 | } else | |
1895 | spin_unlock(&dcache_lock); | |
1896 | ||
1897 | out: | |
1898 | dput(pwd); | |
1899 | mntput(pwdmnt); | |
1900 | dput(root); | |
1901 | mntput(rootmnt); | |
1902 | free_page((unsigned long) page); | |
1903 | return error; | |
1904 | } | |
1905 | ||
1906 | /* | |
1907 | * Test whether new_dentry is a subdirectory of old_dentry. | |
1908 | * | |
1909 | * Trivially implemented using the dcache structure | |
1910 | */ | |
1911 | ||
1912 | /** | |
1913 | * is_subdir - is new dentry a subdirectory of old_dentry | |
1914 | * @new_dentry: new dentry | |
1915 | * @old_dentry: old dentry | |
1916 | * | |
1917 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
1918 | * Returns 0 otherwise. | |
1919 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
1920 | */ | |
1921 | ||
1922 | int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) | |
1923 | { | |
1924 | int result; | |
1925 | struct dentry * saved = new_dentry; | |
1926 | unsigned long seq; | |
1927 | ||
1928 | /* need rcu_readlock to protect against the d_parent trashing due to | |
1929 | * d_move | |
1930 | */ | |
1931 | rcu_read_lock(); | |
1932 | do { | |
1933 | /* for restarting inner loop in case of seq retry */ | |
1934 | new_dentry = saved; | |
1935 | result = 0; | |
1936 | seq = read_seqbegin(&rename_lock); | |
1937 | for (;;) { | |
1938 | if (new_dentry != old_dentry) { | |
1939 | struct dentry * parent = new_dentry->d_parent; | |
1940 | if (parent == new_dentry) | |
1941 | break; | |
1942 | new_dentry = parent; | |
1943 | continue; | |
1944 | } | |
1945 | result = 1; | |
1946 | break; | |
1947 | } | |
1948 | } while (read_seqretry(&rename_lock, seq)); | |
1949 | rcu_read_unlock(); | |
1950 | ||
1951 | return result; | |
1952 | } | |
1953 | ||
1954 | void d_genocide(struct dentry *root) | |
1955 | { | |
1956 | struct dentry *this_parent = root; | |
1957 | struct list_head *next; | |
1958 | ||
1959 | spin_lock(&dcache_lock); | |
1960 | repeat: | |
1961 | next = this_parent->d_subdirs.next; | |
1962 | resume: | |
1963 | while (next != &this_parent->d_subdirs) { | |
1964 | struct list_head *tmp = next; | |
5160ee6f | 1965 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
1966 | next = tmp->next; |
1967 | if (d_unhashed(dentry)||!dentry->d_inode) | |
1968 | continue; | |
1969 | if (!list_empty(&dentry->d_subdirs)) { | |
1970 | this_parent = dentry; | |
1971 | goto repeat; | |
1972 | } | |
1973 | atomic_dec(&dentry->d_count); | |
1974 | } | |
1975 | if (this_parent != root) { | |
5160ee6f | 1976 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
1977 | atomic_dec(&this_parent->d_count); |
1978 | this_parent = this_parent->d_parent; | |
1979 | goto resume; | |
1980 | } | |
1981 | spin_unlock(&dcache_lock); | |
1982 | } | |
1983 | ||
1984 | /** | |
1985 | * find_inode_number - check for dentry with name | |
1986 | * @dir: directory to check | |
1987 | * @name: Name to find. | |
1988 | * | |
1989 | * Check whether a dentry already exists for the given name, | |
1990 | * and return the inode number if it has an inode. Otherwise | |
1991 | * 0 is returned. | |
1992 | * | |
1993 | * This routine is used to post-process directory listings for | |
1994 | * filesystems using synthetic inode numbers, and is necessary | |
1995 | * to keep getcwd() working. | |
1996 | */ | |
1997 | ||
1998 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) | |
1999 | { | |
2000 | struct dentry * dentry; | |
2001 | ino_t ino = 0; | |
2002 | ||
3e7e241f EB |
2003 | dentry = d_hash_and_lookup(dir, name); |
2004 | if (dentry) { | |
1da177e4 LT |
2005 | if (dentry->d_inode) |
2006 | ino = dentry->d_inode->i_ino; | |
2007 | dput(dentry); | |
2008 | } | |
1da177e4 LT |
2009 | return ino; |
2010 | } | |
2011 | ||
2012 | static __initdata unsigned long dhash_entries; | |
2013 | static int __init set_dhash_entries(char *str) | |
2014 | { | |
2015 | if (!str) | |
2016 | return 0; | |
2017 | dhash_entries = simple_strtoul(str, &str, 0); | |
2018 | return 1; | |
2019 | } | |
2020 | __setup("dhash_entries=", set_dhash_entries); | |
2021 | ||
2022 | static void __init dcache_init_early(void) | |
2023 | { | |
2024 | int loop; | |
2025 | ||
2026 | /* If hashes are distributed across NUMA nodes, defer | |
2027 | * hash allocation until vmalloc space is available. | |
2028 | */ | |
2029 | if (hashdist) | |
2030 | return; | |
2031 | ||
2032 | dentry_hashtable = | |
2033 | alloc_large_system_hash("Dentry cache", | |
2034 | sizeof(struct hlist_head), | |
2035 | dhash_entries, | |
2036 | 13, | |
2037 | HASH_EARLY, | |
2038 | &d_hash_shift, | |
2039 | &d_hash_mask, | |
2040 | 0); | |
2041 | ||
2042 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2043 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2044 | } | |
2045 | ||
2046 | static void __init dcache_init(unsigned long mempages) | |
2047 | { | |
2048 | int loop; | |
2049 | ||
2050 | /* | |
2051 | * A constructor could be added for stable state like the lists, | |
2052 | * but it is probably not worth it because of the cache nature | |
2053 | * of the dcache. | |
2054 | */ | |
2055 | dentry_cache = kmem_cache_create("dentry_cache", | |
2056 | sizeof(struct dentry), | |
2057 | 0, | |
b0196009 PJ |
2058 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| |
2059 | SLAB_MEM_SPREAD), | |
1da177e4 LT |
2060 | NULL, NULL); |
2061 | ||
2062 | set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory); | |
2063 | ||
2064 | /* Hash may have been set up in dcache_init_early */ | |
2065 | if (!hashdist) | |
2066 | return; | |
2067 | ||
2068 | dentry_hashtable = | |
2069 | alloc_large_system_hash("Dentry cache", | |
2070 | sizeof(struct hlist_head), | |
2071 | dhash_entries, | |
2072 | 13, | |
2073 | 0, | |
2074 | &d_hash_shift, | |
2075 | &d_hash_mask, | |
2076 | 0); | |
2077 | ||
2078 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2079 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2080 | } | |
2081 | ||
2082 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 2083 | struct kmem_cache *names_cachep __read_mostly; |
1da177e4 LT |
2084 | |
2085 | /* SLAB cache for file structures */ | |
e18b890b | 2086 | struct kmem_cache *filp_cachep __read_mostly; |
1da177e4 LT |
2087 | |
2088 | EXPORT_SYMBOL(d_genocide); | |
2089 | ||
1da177e4 LT |
2090 | void __init vfs_caches_init_early(void) |
2091 | { | |
2092 | dcache_init_early(); | |
2093 | inode_init_early(); | |
2094 | } | |
2095 | ||
2096 | void __init vfs_caches_init(unsigned long mempages) | |
2097 | { | |
2098 | unsigned long reserve; | |
2099 | ||
2100 | /* Base hash sizes on available memory, with a reserve equal to | |
2101 | 150% of current kernel size */ | |
2102 | ||
2103 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
2104 | mempages -= reserve; | |
2105 | ||
2106 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
2107 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
2108 | ||
2109 | filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, | |
529bf6be | 2110 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); |
1da177e4 LT |
2111 | |
2112 | dcache_init(mempages); | |
2113 | inode_init(mempages); | |
2114 | files_init(mempages); | |
2115 | mnt_init(mempages); | |
2116 | bdev_cache_init(); | |
2117 | chrdev_init(); | |
2118 | } | |
2119 | ||
2120 | EXPORT_SYMBOL(d_alloc); | |
2121 | EXPORT_SYMBOL(d_alloc_anon); | |
2122 | EXPORT_SYMBOL(d_alloc_root); | |
2123 | EXPORT_SYMBOL(d_delete); | |
2124 | EXPORT_SYMBOL(d_find_alias); | |
2125 | EXPORT_SYMBOL(d_instantiate); | |
2126 | EXPORT_SYMBOL(d_invalidate); | |
2127 | EXPORT_SYMBOL(d_lookup); | |
2128 | EXPORT_SYMBOL(d_move); | |
770bfad8 | 2129 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
1da177e4 LT |
2130 | EXPORT_SYMBOL(d_path); |
2131 | EXPORT_SYMBOL(d_prune_aliases); | |
2132 | EXPORT_SYMBOL(d_rehash); | |
2133 | EXPORT_SYMBOL(d_splice_alias); | |
2134 | EXPORT_SYMBOL(d_validate); | |
2135 | EXPORT_SYMBOL(dget_locked); | |
2136 | EXPORT_SYMBOL(dput); | |
2137 | EXPORT_SYMBOL(find_inode_number); | |
2138 | EXPORT_SYMBOL(have_submounts); | |
2139 | EXPORT_SYMBOL(names_cachep); | |
2140 | EXPORT_SYMBOL(shrink_dcache_parent); | |
2141 | EXPORT_SYMBOL(shrink_dcache_sb); |