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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 | ||
d52b9086 MS |
124 | /** |
125 | * d_kill - kill dentry and return parent | |
126 | * @dentry: dentry to kill | |
127 | * | |
128 | * Called with dcache_lock and d_lock, releases both. The dentry must | |
129 | * already be unhashed and removed from the LRU. | |
130 | * | |
131 | * If this is the root of the dentry tree, return NULL. | |
132 | */ | |
133 | static struct dentry *d_kill(struct dentry *dentry) | |
134 | { | |
135 | struct dentry *parent; | |
136 | ||
137 | list_del(&dentry->d_u.d_child); | |
138 | dentry_stat.nr_dentry--; /* For d_free, below */ | |
139 | /*drops the locks, at that point nobody can reach this dentry */ | |
140 | dentry_iput(dentry); | |
141 | parent = dentry->d_parent; | |
142 | d_free(dentry); | |
143 | return dentry == parent ? NULL : parent; | |
144 | } | |
145 | ||
1da177e4 LT |
146 | /* |
147 | * This is dput | |
148 | * | |
149 | * This is complicated by the fact that we do not want to put | |
150 | * dentries that are no longer on any hash chain on the unused | |
151 | * list: we'd much rather just get rid of them immediately. | |
152 | * | |
153 | * However, that implies that we have to traverse the dentry | |
154 | * tree upwards to the parents which might _also_ now be | |
155 | * scheduled for deletion (it may have been only waiting for | |
156 | * its last child to go away). | |
157 | * | |
158 | * This tail recursion is done by hand as we don't want to depend | |
159 | * on the compiler to always get this right (gcc generally doesn't). | |
160 | * Real recursion would eat up our stack space. | |
161 | */ | |
162 | ||
163 | /* | |
164 | * dput - release a dentry | |
165 | * @dentry: dentry to release | |
166 | * | |
167 | * Release a dentry. This will drop the usage count and if appropriate | |
168 | * call the dentry unlink method as well as removing it from the queues and | |
169 | * releasing its resources. If the parent dentries were scheduled for release | |
170 | * they too may now get deleted. | |
171 | * | |
172 | * no dcache lock, please. | |
173 | */ | |
174 | ||
175 | void dput(struct dentry *dentry) | |
176 | { | |
177 | if (!dentry) | |
178 | return; | |
179 | ||
180 | repeat: | |
181 | if (atomic_read(&dentry->d_count) == 1) | |
182 | might_sleep(); | |
183 | if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) | |
184 | return; | |
185 | ||
186 | spin_lock(&dentry->d_lock); | |
187 | if (atomic_read(&dentry->d_count)) { | |
188 | spin_unlock(&dentry->d_lock); | |
189 | spin_unlock(&dcache_lock); | |
190 | return; | |
191 | } | |
192 | ||
193 | /* | |
194 | * AV: ->d_delete() is _NOT_ allowed to block now. | |
195 | */ | |
196 | if (dentry->d_op && dentry->d_op->d_delete) { | |
197 | if (dentry->d_op->d_delete(dentry)) | |
198 | goto unhash_it; | |
199 | } | |
200 | /* Unreachable? Get rid of it */ | |
201 | if (d_unhashed(dentry)) | |
202 | goto kill_it; | |
203 | if (list_empty(&dentry->d_lru)) { | |
204 | dentry->d_flags |= DCACHE_REFERENCED; | |
205 | list_add(&dentry->d_lru, &dentry_unused); | |
206 | dentry_stat.nr_unused++; | |
207 | } | |
208 | spin_unlock(&dentry->d_lock); | |
209 | spin_unlock(&dcache_lock); | |
210 | return; | |
211 | ||
212 | unhash_it: | |
213 | __d_drop(dentry); | |
d52b9086 MS |
214 | kill_it: |
215 | /* If dentry was on d_lru list | |
216 | * delete it from there | |
217 | */ | |
218 | if (!list_empty(&dentry->d_lru)) { | |
219 | list_del(&dentry->d_lru); | |
220 | dentry_stat.nr_unused--; | |
1da177e4 | 221 | } |
d52b9086 MS |
222 | dentry = d_kill(dentry); |
223 | if (dentry) | |
224 | goto repeat; | |
1da177e4 LT |
225 | } |
226 | ||
227 | /** | |
228 | * d_invalidate - invalidate a dentry | |
229 | * @dentry: dentry to invalidate | |
230 | * | |
231 | * Try to invalidate the dentry if it turns out to be | |
232 | * possible. If there are other dentries that can be | |
233 | * reached through this one we can't delete it and we | |
234 | * return -EBUSY. On success we return 0. | |
235 | * | |
236 | * no dcache lock. | |
237 | */ | |
238 | ||
239 | int d_invalidate(struct dentry * dentry) | |
240 | { | |
241 | /* | |
242 | * If it's already been dropped, return OK. | |
243 | */ | |
244 | spin_lock(&dcache_lock); | |
245 | if (d_unhashed(dentry)) { | |
246 | spin_unlock(&dcache_lock); | |
247 | return 0; | |
248 | } | |
249 | /* | |
250 | * Check whether to do a partial shrink_dcache | |
251 | * to get rid of unused child entries. | |
252 | */ | |
253 | if (!list_empty(&dentry->d_subdirs)) { | |
254 | spin_unlock(&dcache_lock); | |
255 | shrink_dcache_parent(dentry); | |
256 | spin_lock(&dcache_lock); | |
257 | } | |
258 | ||
259 | /* | |
260 | * Somebody else still using it? | |
261 | * | |
262 | * If it's a directory, we can't drop it | |
263 | * for fear of somebody re-populating it | |
264 | * with children (even though dropping it | |
265 | * would make it unreachable from the root, | |
266 | * we might still populate it if it was a | |
267 | * working directory or similar). | |
268 | */ | |
269 | spin_lock(&dentry->d_lock); | |
270 | if (atomic_read(&dentry->d_count) > 1) { | |
271 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { | |
272 | spin_unlock(&dentry->d_lock); | |
273 | spin_unlock(&dcache_lock); | |
274 | return -EBUSY; | |
275 | } | |
276 | } | |
277 | ||
278 | __d_drop(dentry); | |
279 | spin_unlock(&dentry->d_lock); | |
280 | spin_unlock(&dcache_lock); | |
281 | return 0; | |
282 | } | |
283 | ||
284 | /* This should be called _only_ with dcache_lock held */ | |
285 | ||
286 | static inline struct dentry * __dget_locked(struct dentry *dentry) | |
287 | { | |
288 | atomic_inc(&dentry->d_count); | |
289 | if (!list_empty(&dentry->d_lru)) { | |
290 | dentry_stat.nr_unused--; | |
291 | list_del_init(&dentry->d_lru); | |
292 | } | |
293 | return dentry; | |
294 | } | |
295 | ||
296 | struct dentry * dget_locked(struct dentry *dentry) | |
297 | { | |
298 | return __dget_locked(dentry); | |
299 | } | |
300 | ||
301 | /** | |
302 | * d_find_alias - grab a hashed alias of inode | |
303 | * @inode: inode in question | |
304 | * @want_discon: flag, used by d_splice_alias, to request | |
305 | * that only a DISCONNECTED alias be returned. | |
306 | * | |
307 | * If inode has a hashed alias, or is a directory and has any alias, | |
308 | * acquire the reference to alias and return it. Otherwise return NULL. | |
309 | * Notice that if inode is a directory there can be only one alias and | |
310 | * it can be unhashed only if it has no children, or if it is the root | |
311 | * of a filesystem. | |
312 | * | |
21c0d8fd | 313 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
1da177e4 | 314 | * any other hashed alias over that one unless @want_discon is set, |
21c0d8fd | 315 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
1da177e4 LT |
316 | */ |
317 | ||
318 | static struct dentry * __d_find_alias(struct inode *inode, int want_discon) | |
319 | { | |
320 | struct list_head *head, *next, *tmp; | |
321 | struct dentry *alias, *discon_alias=NULL; | |
322 | ||
323 | head = &inode->i_dentry; | |
324 | next = inode->i_dentry.next; | |
325 | while (next != head) { | |
326 | tmp = next; | |
327 | next = tmp->next; | |
328 | prefetch(next); | |
329 | alias = list_entry(tmp, struct dentry, d_alias); | |
330 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
21c0d8fd N |
331 | if (IS_ROOT(alias) && |
332 | (alias->d_flags & DCACHE_DISCONNECTED)) | |
1da177e4 LT |
333 | discon_alias = alias; |
334 | else if (!want_discon) { | |
335 | __dget_locked(alias); | |
336 | return alias; | |
337 | } | |
338 | } | |
339 | } | |
340 | if (discon_alias) | |
341 | __dget_locked(discon_alias); | |
342 | return discon_alias; | |
343 | } | |
344 | ||
345 | struct dentry * d_find_alias(struct inode *inode) | |
346 | { | |
214fda1f DH |
347 | struct dentry *de = NULL; |
348 | ||
349 | if (!list_empty(&inode->i_dentry)) { | |
350 | spin_lock(&dcache_lock); | |
351 | de = __d_find_alias(inode, 0); | |
352 | spin_unlock(&dcache_lock); | |
353 | } | |
1da177e4 LT |
354 | return de; |
355 | } | |
356 | ||
357 | /* | |
358 | * Try to kill dentries associated with this inode. | |
359 | * WARNING: you must own a reference to inode. | |
360 | */ | |
361 | void d_prune_aliases(struct inode *inode) | |
362 | { | |
0cdca3f9 | 363 | struct dentry *dentry; |
1da177e4 LT |
364 | restart: |
365 | spin_lock(&dcache_lock); | |
0cdca3f9 | 366 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 LT |
367 | spin_lock(&dentry->d_lock); |
368 | if (!atomic_read(&dentry->d_count)) { | |
369 | __dget_locked(dentry); | |
370 | __d_drop(dentry); | |
371 | spin_unlock(&dentry->d_lock); | |
372 | spin_unlock(&dcache_lock); | |
373 | dput(dentry); | |
374 | goto restart; | |
375 | } | |
376 | spin_unlock(&dentry->d_lock); | |
377 | } | |
378 | spin_unlock(&dcache_lock); | |
379 | } | |
380 | ||
381 | /* | |
d702ccb3 AM |
382 | * Throw away a dentry - free the inode, dput the parent. This requires that |
383 | * the LRU list has already been removed. | |
384 | * | |
d52b9086 MS |
385 | * If prune_parents is true, try to prune ancestors as well. |
386 | * | |
1da177e4 | 387 | * Called with dcache_lock, drops it and then regains. |
d702ccb3 | 388 | * Called with dentry->d_lock held, drops it. |
1da177e4 | 389 | */ |
d52b9086 | 390 | static void prune_one_dentry(struct dentry * dentry, int prune_parents) |
1da177e4 | 391 | { |
1da177e4 | 392 | __d_drop(dentry); |
d52b9086 MS |
393 | dentry = d_kill(dentry); |
394 | if (!prune_parents) { | |
395 | dput(dentry); | |
396 | spin_lock(&dcache_lock); | |
397 | return; | |
398 | } | |
399 | ||
400 | /* | |
401 | * Prune ancestors. Locking is simpler than in dput(), | |
402 | * because dcache_lock needs to be taken anyway. | |
403 | */ | |
1da177e4 | 404 | spin_lock(&dcache_lock); |
d52b9086 MS |
405 | while (dentry) { |
406 | if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) | |
407 | return; | |
408 | ||
409 | if (dentry->d_op && dentry->d_op->d_delete) | |
410 | dentry->d_op->d_delete(dentry); | |
411 | if (!list_empty(&dentry->d_lru)) { | |
412 | list_del(&dentry->d_lru); | |
413 | dentry_stat.nr_unused--; | |
414 | } | |
415 | __d_drop(dentry); | |
416 | dentry = d_kill(dentry); | |
417 | spin_lock(&dcache_lock); | |
418 | } | |
1da177e4 LT |
419 | } |
420 | ||
421 | /** | |
422 | * prune_dcache - shrink the dcache | |
423 | * @count: number of entries to try and free | |
0feae5c4 N |
424 | * @sb: if given, ignore dentries for other superblocks |
425 | * which are being unmounted. | |
d52b9086 | 426 | * @prune_parents: if true, try to prune ancestors as well in one go |
1da177e4 LT |
427 | * |
428 | * Shrink the dcache. This is done when we need | |
429 | * more memory, or simply when we need to unmount | |
430 | * something (at which point we need to unuse | |
431 | * all dentries). | |
432 | * | |
433 | * This function may fail to free any resources if | |
434 | * all the dentries are in use. | |
435 | */ | |
436 | ||
d52b9086 | 437 | static void prune_dcache(int count, struct super_block *sb, int prune_parents) |
1da177e4 LT |
438 | { |
439 | spin_lock(&dcache_lock); | |
440 | for (; count ; count--) { | |
441 | struct dentry *dentry; | |
442 | struct list_head *tmp; | |
0feae5c4 | 443 | struct rw_semaphore *s_umount; |
1da177e4 LT |
444 | |
445 | cond_resched_lock(&dcache_lock); | |
446 | ||
447 | tmp = dentry_unused.prev; | |
f58a1ebb | 448 | if (sb) { |
0feae5c4 N |
449 | /* Try to find a dentry for this sb, but don't try |
450 | * too hard, if they aren't near the tail they will | |
451 | * be moved down again soon | |
452 | */ | |
453 | int skip = count; | |
454 | while (skip && tmp != &dentry_unused && | |
455 | list_entry(tmp, struct dentry, d_lru)->d_sb != sb) { | |
456 | skip--; | |
457 | tmp = tmp->prev; | |
458 | } | |
459 | } | |
1da177e4 LT |
460 | if (tmp == &dentry_unused) |
461 | break; | |
462 | list_del_init(tmp); | |
463 | prefetch(dentry_unused.prev); | |
464 | dentry_stat.nr_unused--; | |
465 | dentry = list_entry(tmp, struct dentry, d_lru); | |
466 | ||
467 | spin_lock(&dentry->d_lock); | |
468 | /* | |
469 | * We found an inuse dentry which was not removed from | |
470 | * dentry_unused because of laziness during lookup. Do not free | |
471 | * it - just keep it off the dentry_unused list. | |
472 | */ | |
473 | if (atomic_read(&dentry->d_count)) { | |
474 | spin_unlock(&dentry->d_lock); | |
475 | continue; | |
476 | } | |
477 | /* If the dentry was recently referenced, don't free it. */ | |
478 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
479 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
480 | list_add(&dentry->d_lru, &dentry_unused); | |
481 | dentry_stat.nr_unused++; | |
482 | spin_unlock(&dentry->d_lock); | |
483 | continue; | |
484 | } | |
0feae5c4 N |
485 | /* |
486 | * If the dentry is not DCACHED_REFERENCED, it is time | |
487 | * to remove it from the dcache, provided the super block is | |
488 | * NULL (which means we are trying to reclaim memory) | |
489 | * or this dentry belongs to the same super block that | |
490 | * we want to shrink. | |
491 | */ | |
492 | /* | |
493 | * If this dentry is for "my" filesystem, then I can prune it | |
494 | * without taking the s_umount lock (I already hold it). | |
495 | */ | |
496 | if (sb && dentry->d_sb == sb) { | |
d52b9086 | 497 | prune_one_dentry(dentry, prune_parents); |
0feae5c4 N |
498 | continue; |
499 | } | |
500 | /* | |
501 | * ...otherwise we need to be sure this filesystem isn't being | |
502 | * unmounted, otherwise we could race with | |
503 | * generic_shutdown_super(), and end up holding a reference to | |
504 | * an inode while the filesystem is unmounted. | |
505 | * So we try to get s_umount, and make sure s_root isn't NULL. | |
506 | * (Take a local copy of s_umount to avoid a use-after-free of | |
507 | * `dentry'). | |
508 | */ | |
509 | s_umount = &dentry->d_sb->s_umount; | |
510 | if (down_read_trylock(s_umount)) { | |
511 | if (dentry->d_sb->s_root != NULL) { | |
d52b9086 | 512 | prune_one_dentry(dentry, prune_parents); |
0feae5c4 N |
513 | up_read(s_umount); |
514 | continue; | |
515 | } | |
516 | up_read(s_umount); | |
517 | } | |
518 | spin_unlock(&dentry->d_lock); | |
6eac3f93 VA |
519 | /* |
520 | * Insert dentry at the head of the list as inserting at the | |
521 | * tail leads to a cycle. | |
0feae5c4 | 522 | */ |
6eac3f93 VA |
523 | list_add(&dentry->d_lru, &dentry_unused); |
524 | dentry_stat.nr_unused++; | |
1da177e4 LT |
525 | } |
526 | spin_unlock(&dcache_lock); | |
527 | } | |
528 | ||
529 | /* | |
530 | * Shrink the dcache for the specified super block. | |
531 | * This allows us to unmount a device without disturbing | |
532 | * the dcache for the other devices. | |
533 | * | |
534 | * This implementation makes just two traversals of the | |
535 | * unused list. On the first pass we move the selected | |
536 | * dentries to the most recent end, and on the second | |
537 | * pass we free them. The second pass must restart after | |
538 | * each dput(), but since the target dentries are all at | |
539 | * the end, it's really just a single traversal. | |
540 | */ | |
541 | ||
542 | /** | |
543 | * shrink_dcache_sb - shrink dcache for a superblock | |
544 | * @sb: superblock | |
545 | * | |
546 | * Shrink the dcache for the specified super block. This | |
547 | * is used to free the dcache before unmounting a file | |
548 | * system | |
549 | */ | |
550 | ||
551 | void shrink_dcache_sb(struct super_block * sb) | |
552 | { | |
553 | struct list_head *tmp, *next; | |
554 | struct dentry *dentry; | |
555 | ||
556 | /* | |
557 | * Pass one ... move the dentries for the specified | |
558 | * superblock to the most recent end of the unused list. | |
559 | */ | |
560 | spin_lock(&dcache_lock); | |
0cdca3f9 | 561 | list_for_each_safe(tmp, next, &dentry_unused) { |
1da177e4 LT |
562 | dentry = list_entry(tmp, struct dentry, d_lru); |
563 | if (dentry->d_sb != sb) | |
564 | continue; | |
1bfba4e8 | 565 | list_move(tmp, &dentry_unused); |
1da177e4 LT |
566 | } |
567 | ||
568 | /* | |
569 | * Pass two ... free the dentries for this superblock. | |
570 | */ | |
571 | repeat: | |
0cdca3f9 | 572 | list_for_each_safe(tmp, next, &dentry_unused) { |
1da177e4 LT |
573 | dentry = list_entry(tmp, struct dentry, d_lru); |
574 | if (dentry->d_sb != sb) | |
575 | continue; | |
576 | dentry_stat.nr_unused--; | |
577 | list_del_init(tmp); | |
578 | spin_lock(&dentry->d_lock); | |
579 | if (atomic_read(&dentry->d_count)) { | |
580 | spin_unlock(&dentry->d_lock); | |
581 | continue; | |
582 | } | |
d52b9086 | 583 | prune_one_dentry(dentry, 1); |
2ab13460 | 584 | cond_resched_lock(&dcache_lock); |
1da177e4 LT |
585 | goto repeat; |
586 | } | |
587 | spin_unlock(&dcache_lock); | |
588 | } | |
589 | ||
c636ebdb DH |
590 | /* |
591 | * destroy a single subtree of dentries for unmount | |
592 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
593 | * locking | |
594 | */ | |
595 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
596 | { | |
597 | struct dentry *parent; | |
f8713576 | 598 | unsigned detached = 0; |
c636ebdb DH |
599 | |
600 | BUG_ON(!IS_ROOT(dentry)); | |
601 | ||
602 | /* detach this root from the system */ | |
603 | spin_lock(&dcache_lock); | |
604 | if (!list_empty(&dentry->d_lru)) { | |
605 | dentry_stat.nr_unused--; | |
606 | list_del_init(&dentry->d_lru); | |
607 | } | |
608 | __d_drop(dentry); | |
609 | spin_unlock(&dcache_lock); | |
610 | ||
611 | for (;;) { | |
612 | /* descend to the first leaf in the current subtree */ | |
613 | while (!list_empty(&dentry->d_subdirs)) { | |
614 | struct dentry *loop; | |
615 | ||
616 | /* this is a branch with children - detach all of them | |
617 | * from the system in one go */ | |
618 | spin_lock(&dcache_lock); | |
619 | list_for_each_entry(loop, &dentry->d_subdirs, | |
620 | d_u.d_child) { | |
621 | if (!list_empty(&loop->d_lru)) { | |
622 | dentry_stat.nr_unused--; | |
623 | list_del_init(&loop->d_lru); | |
624 | } | |
625 | ||
626 | __d_drop(loop); | |
627 | cond_resched_lock(&dcache_lock); | |
628 | } | |
629 | spin_unlock(&dcache_lock); | |
630 | ||
631 | /* move to the first child */ | |
632 | dentry = list_entry(dentry->d_subdirs.next, | |
633 | struct dentry, d_u.d_child); | |
634 | } | |
635 | ||
636 | /* consume the dentries from this leaf up through its parents | |
637 | * until we find one with children or run out altogether */ | |
638 | do { | |
639 | struct inode *inode; | |
640 | ||
641 | if (atomic_read(&dentry->d_count) != 0) { | |
642 | printk(KERN_ERR | |
643 | "BUG: Dentry %p{i=%lx,n=%s}" | |
644 | " still in use (%d)" | |
645 | " [unmount of %s %s]\n", | |
646 | dentry, | |
647 | dentry->d_inode ? | |
648 | dentry->d_inode->i_ino : 0UL, | |
649 | dentry->d_name.name, | |
650 | atomic_read(&dentry->d_count), | |
651 | dentry->d_sb->s_type->name, | |
652 | dentry->d_sb->s_id); | |
653 | BUG(); | |
654 | } | |
655 | ||
656 | parent = dentry->d_parent; | |
657 | if (parent == dentry) | |
658 | parent = NULL; | |
659 | else | |
660 | atomic_dec(&parent->d_count); | |
661 | ||
662 | list_del(&dentry->d_u.d_child); | |
f8713576 | 663 | detached++; |
c636ebdb DH |
664 | |
665 | inode = dentry->d_inode; | |
666 | if (inode) { | |
667 | dentry->d_inode = NULL; | |
668 | list_del_init(&dentry->d_alias); | |
669 | if (dentry->d_op && dentry->d_op->d_iput) | |
670 | dentry->d_op->d_iput(dentry, inode); | |
671 | else | |
672 | iput(inode); | |
673 | } | |
674 | ||
675 | d_free(dentry); | |
676 | ||
677 | /* finished when we fall off the top of the tree, | |
678 | * otherwise we ascend to the parent and move to the | |
679 | * next sibling if there is one */ | |
680 | if (!parent) | |
f8713576 | 681 | goto out; |
c636ebdb DH |
682 | |
683 | dentry = parent; | |
684 | ||
685 | } while (list_empty(&dentry->d_subdirs)); | |
686 | ||
687 | dentry = list_entry(dentry->d_subdirs.next, | |
688 | struct dentry, d_u.d_child); | |
689 | } | |
f8713576 DH |
690 | out: |
691 | /* several dentries were freed, need to correct nr_dentry */ | |
692 | spin_lock(&dcache_lock); | |
693 | dentry_stat.nr_dentry -= detached; | |
694 | spin_unlock(&dcache_lock); | |
c636ebdb DH |
695 | } |
696 | ||
697 | /* | |
698 | * destroy the dentries attached to a superblock on unmounting | |
699 | * - we don't need to use dentry->d_lock, and only need dcache_lock when | |
700 | * removing the dentry from the system lists and hashes because: | |
701 | * - the superblock is detached from all mountings and open files, so the | |
702 | * dentry trees will not be rearranged by the VFS | |
703 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
704 | * any dentries belonging to this superblock that it comes across | |
705 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
706 | * in this superblock | |
707 | */ | |
708 | void shrink_dcache_for_umount(struct super_block *sb) | |
709 | { | |
710 | struct dentry *dentry; | |
711 | ||
712 | if (down_read_trylock(&sb->s_umount)) | |
713 | BUG(); | |
714 | ||
715 | dentry = sb->s_root; | |
716 | sb->s_root = NULL; | |
717 | atomic_dec(&dentry->d_count); | |
718 | shrink_dcache_for_umount_subtree(dentry); | |
719 | ||
720 | while (!hlist_empty(&sb->s_anon)) { | |
721 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); | |
722 | shrink_dcache_for_umount_subtree(dentry); | |
723 | } | |
724 | } | |
725 | ||
1da177e4 LT |
726 | /* |
727 | * Search for at least 1 mount point in the dentry's subdirs. | |
728 | * We descend to the next level whenever the d_subdirs | |
729 | * list is non-empty and continue searching. | |
730 | */ | |
731 | ||
732 | /** | |
733 | * have_submounts - check for mounts over a dentry | |
734 | * @parent: dentry to check. | |
735 | * | |
736 | * Return true if the parent or its subdirectories contain | |
737 | * a mount point | |
738 | */ | |
739 | ||
740 | int have_submounts(struct dentry *parent) | |
741 | { | |
742 | struct dentry *this_parent = parent; | |
743 | struct list_head *next; | |
744 | ||
745 | spin_lock(&dcache_lock); | |
746 | if (d_mountpoint(parent)) | |
747 | goto positive; | |
748 | repeat: | |
749 | next = this_parent->d_subdirs.next; | |
750 | resume: | |
751 | while (next != &this_parent->d_subdirs) { | |
752 | struct list_head *tmp = next; | |
5160ee6f | 753 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
754 | next = tmp->next; |
755 | /* Have we found a mount point ? */ | |
756 | if (d_mountpoint(dentry)) | |
757 | goto positive; | |
758 | if (!list_empty(&dentry->d_subdirs)) { | |
759 | this_parent = dentry; | |
760 | goto repeat; | |
761 | } | |
762 | } | |
763 | /* | |
764 | * All done at this level ... ascend and resume the search. | |
765 | */ | |
766 | if (this_parent != parent) { | |
5160ee6f | 767 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
768 | this_parent = this_parent->d_parent; |
769 | goto resume; | |
770 | } | |
771 | spin_unlock(&dcache_lock); | |
772 | return 0; /* No mount points found in tree */ | |
773 | positive: | |
774 | spin_unlock(&dcache_lock); | |
775 | return 1; | |
776 | } | |
777 | ||
778 | /* | |
779 | * Search the dentry child list for the specified parent, | |
780 | * and move any unused dentries to the end of the unused | |
781 | * list for prune_dcache(). We descend to the next level | |
782 | * whenever the d_subdirs list is non-empty and continue | |
783 | * searching. | |
784 | * | |
785 | * It returns zero iff there are no unused children, | |
786 | * otherwise it returns the number of children moved to | |
787 | * the end of the unused list. This may not be the total | |
788 | * number of unused children, because select_parent can | |
789 | * drop the lock and return early due to latency | |
790 | * constraints. | |
791 | */ | |
792 | static int select_parent(struct dentry * parent) | |
793 | { | |
794 | struct dentry *this_parent = parent; | |
795 | struct list_head *next; | |
796 | int found = 0; | |
797 | ||
798 | spin_lock(&dcache_lock); | |
799 | repeat: | |
800 | next = this_parent->d_subdirs.next; | |
801 | resume: | |
802 | while (next != &this_parent->d_subdirs) { | |
803 | struct list_head *tmp = next; | |
5160ee6f | 804 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
805 | next = tmp->next; |
806 | ||
807 | if (!list_empty(&dentry->d_lru)) { | |
808 | dentry_stat.nr_unused--; | |
809 | list_del_init(&dentry->d_lru); | |
810 | } | |
811 | /* | |
812 | * move only zero ref count dentries to the end | |
813 | * of the unused list for prune_dcache | |
814 | */ | |
815 | if (!atomic_read(&dentry->d_count)) { | |
8e13059a | 816 | list_add_tail(&dentry->d_lru, &dentry_unused); |
1da177e4 LT |
817 | dentry_stat.nr_unused++; |
818 | found++; | |
819 | } | |
820 | ||
821 | /* | |
822 | * We can return to the caller if we have found some (this | |
823 | * ensures forward progress). We'll be coming back to find | |
824 | * the rest. | |
825 | */ | |
826 | if (found && need_resched()) | |
827 | goto out; | |
828 | ||
829 | /* | |
830 | * Descend a level if the d_subdirs list is non-empty. | |
831 | */ | |
832 | if (!list_empty(&dentry->d_subdirs)) { | |
833 | this_parent = dentry; | |
1da177e4 LT |
834 | goto repeat; |
835 | } | |
836 | } | |
837 | /* | |
838 | * All done at this level ... ascend and resume the search. | |
839 | */ | |
840 | if (this_parent != parent) { | |
5160ee6f | 841 | next = this_parent->d_u.d_child.next; |
1da177e4 | 842 | this_parent = this_parent->d_parent; |
1da177e4 LT |
843 | goto resume; |
844 | } | |
845 | out: | |
846 | spin_unlock(&dcache_lock); | |
847 | return found; | |
848 | } | |
849 | ||
850 | /** | |
851 | * shrink_dcache_parent - prune dcache | |
852 | * @parent: parent of entries to prune | |
853 | * | |
854 | * Prune the dcache to remove unused children of the parent dentry. | |
855 | */ | |
856 | ||
857 | void shrink_dcache_parent(struct dentry * parent) | |
858 | { | |
859 | int found; | |
860 | ||
861 | while ((found = select_parent(parent)) != 0) | |
d52b9086 | 862 | prune_dcache(found, parent->d_sb, 1); |
1da177e4 LT |
863 | } |
864 | ||
1da177e4 LT |
865 | /* |
866 | * Scan `nr' dentries and return the number which remain. | |
867 | * | |
868 | * We need to avoid reentering the filesystem if the caller is performing a | |
869 | * GFP_NOFS allocation attempt. One example deadlock is: | |
870 | * | |
871 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> | |
872 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> | |
873 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. | |
874 | * | |
875 | * In this case we return -1 to tell the caller that we baled. | |
876 | */ | |
27496a8c | 877 | static int shrink_dcache_memory(int nr, gfp_t gfp_mask) |
1da177e4 LT |
878 | { |
879 | if (nr) { | |
880 | if (!(gfp_mask & __GFP_FS)) | |
881 | return -1; | |
24c32d73 | 882 | prune_dcache(nr, NULL, 1); |
1da177e4 LT |
883 | } |
884 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; | |
885 | } | |
886 | ||
887 | /** | |
888 | * d_alloc - allocate a dcache entry | |
889 | * @parent: parent of entry to allocate | |
890 | * @name: qstr of the name | |
891 | * | |
892 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
893 | * available. On a success the dentry is returned. The name passed in is | |
894 | * copied and the copy passed in may be reused after this call. | |
895 | */ | |
896 | ||
897 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
898 | { | |
899 | struct dentry *dentry; | |
900 | char *dname; | |
901 | ||
902 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); | |
903 | if (!dentry) | |
904 | return NULL; | |
905 | ||
906 | if (name->len > DNAME_INLINE_LEN-1) { | |
907 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
908 | if (!dname) { | |
909 | kmem_cache_free(dentry_cache, dentry); | |
910 | return NULL; | |
911 | } | |
912 | } else { | |
913 | dname = dentry->d_iname; | |
914 | } | |
915 | dentry->d_name.name = dname; | |
916 | ||
917 | dentry->d_name.len = name->len; | |
918 | dentry->d_name.hash = name->hash; | |
919 | memcpy(dname, name->name, name->len); | |
920 | dname[name->len] = 0; | |
921 | ||
922 | atomic_set(&dentry->d_count, 1); | |
923 | dentry->d_flags = DCACHE_UNHASHED; | |
924 | spin_lock_init(&dentry->d_lock); | |
925 | dentry->d_inode = NULL; | |
926 | dentry->d_parent = NULL; | |
927 | dentry->d_sb = NULL; | |
928 | dentry->d_op = NULL; | |
929 | dentry->d_fsdata = NULL; | |
930 | dentry->d_mounted = 0; | |
47ba87e0 | 931 | #ifdef CONFIG_PROFILING |
1da177e4 | 932 | dentry->d_cookie = NULL; |
47ba87e0 | 933 | #endif |
1da177e4 LT |
934 | INIT_HLIST_NODE(&dentry->d_hash); |
935 | INIT_LIST_HEAD(&dentry->d_lru); | |
936 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
937 | INIT_LIST_HEAD(&dentry->d_alias); | |
938 | ||
939 | if (parent) { | |
940 | dentry->d_parent = dget(parent); | |
941 | dentry->d_sb = parent->d_sb; | |
942 | } else { | |
5160ee6f | 943 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1da177e4 LT |
944 | } |
945 | ||
946 | spin_lock(&dcache_lock); | |
947 | if (parent) | |
5160ee6f | 948 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1da177e4 LT |
949 | dentry_stat.nr_dentry++; |
950 | spin_unlock(&dcache_lock); | |
951 | ||
952 | return dentry; | |
953 | } | |
954 | ||
955 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) | |
956 | { | |
957 | struct qstr q; | |
958 | ||
959 | q.name = name; | |
960 | q.len = strlen(name); | |
961 | q.hash = full_name_hash(q.name, q.len); | |
962 | return d_alloc(parent, &q); | |
963 | } | |
964 | ||
965 | /** | |
966 | * d_instantiate - fill in inode information for a dentry | |
967 | * @entry: dentry to complete | |
968 | * @inode: inode to attach to this dentry | |
969 | * | |
970 | * Fill in inode information in the entry. | |
971 | * | |
972 | * This turns negative dentries into productive full members | |
973 | * of society. | |
974 | * | |
975 | * NOTE! This assumes that the inode count has been incremented | |
976 | * (or otherwise set) by the caller to indicate that it is now | |
977 | * in use by the dcache. | |
978 | */ | |
979 | ||
980 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
981 | { | |
28133c7b | 982 | BUG_ON(!list_empty(&entry->d_alias)); |
1da177e4 LT |
983 | spin_lock(&dcache_lock); |
984 | if (inode) | |
985 | list_add(&entry->d_alias, &inode->i_dentry); | |
986 | entry->d_inode = inode; | |
c32ccd87 | 987 | fsnotify_d_instantiate(entry, inode); |
1da177e4 LT |
988 | spin_unlock(&dcache_lock); |
989 | security_d_instantiate(entry, inode); | |
990 | } | |
991 | ||
992 | /** | |
993 | * d_instantiate_unique - instantiate a non-aliased dentry | |
994 | * @entry: dentry to instantiate | |
995 | * @inode: inode to attach to this dentry | |
996 | * | |
997 | * Fill in inode information in the entry. On success, it returns NULL. | |
998 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 999 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1000 | * |
1001 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1002 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1003 | * |
1004 | * This also assumes that the inode count has been incremented | |
1005 | * (or otherwise set) by the caller to indicate that it is now | |
1006 | * in use by the dcache. | |
1da177e4 | 1007 | */ |
770bfad8 DH |
1008 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1009 | struct inode *inode) | |
1da177e4 LT |
1010 | { |
1011 | struct dentry *alias; | |
1012 | int len = entry->d_name.len; | |
1013 | const char *name = entry->d_name.name; | |
1014 | unsigned int hash = entry->d_name.hash; | |
1015 | ||
770bfad8 DH |
1016 | if (!inode) { |
1017 | entry->d_inode = NULL; | |
1018 | return NULL; | |
1019 | } | |
1020 | ||
1da177e4 LT |
1021 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1022 | struct qstr *qstr = &alias->d_name; | |
1023 | ||
1024 | if (qstr->hash != hash) | |
1025 | continue; | |
1026 | if (alias->d_parent != entry->d_parent) | |
1027 | continue; | |
1028 | if (qstr->len != len) | |
1029 | continue; | |
1030 | if (memcmp(qstr->name, name, len)) | |
1031 | continue; | |
1032 | dget_locked(alias); | |
1da177e4 LT |
1033 | return alias; |
1034 | } | |
770bfad8 | 1035 | |
1da177e4 | 1036 | list_add(&entry->d_alias, &inode->i_dentry); |
1da177e4 | 1037 | entry->d_inode = inode; |
c32ccd87 | 1038 | fsnotify_d_instantiate(entry, inode); |
1da177e4 LT |
1039 | return NULL; |
1040 | } | |
770bfad8 DH |
1041 | |
1042 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1043 | { | |
1044 | struct dentry *result; | |
1045 | ||
1046 | BUG_ON(!list_empty(&entry->d_alias)); | |
1047 | ||
1048 | spin_lock(&dcache_lock); | |
1049 | result = __d_instantiate_unique(entry, inode); | |
1050 | spin_unlock(&dcache_lock); | |
1051 | ||
1052 | if (!result) { | |
1053 | security_d_instantiate(entry, inode); | |
1054 | return NULL; | |
1055 | } | |
1056 | ||
1057 | BUG_ON(!d_unhashed(result)); | |
1058 | iput(inode); | |
1059 | return result; | |
1060 | } | |
1061 | ||
1da177e4 LT |
1062 | EXPORT_SYMBOL(d_instantiate_unique); |
1063 | ||
1064 | /** | |
1065 | * d_alloc_root - allocate root dentry | |
1066 | * @root_inode: inode to allocate the root for | |
1067 | * | |
1068 | * Allocate a root ("/") dentry for the inode given. The inode is | |
1069 | * instantiated and returned. %NULL is returned if there is insufficient | |
1070 | * memory or the inode passed is %NULL. | |
1071 | */ | |
1072 | ||
1073 | struct dentry * d_alloc_root(struct inode * root_inode) | |
1074 | { | |
1075 | struct dentry *res = NULL; | |
1076 | ||
1077 | if (root_inode) { | |
1078 | static const struct qstr name = { .name = "/", .len = 1 }; | |
1079 | ||
1080 | res = d_alloc(NULL, &name); | |
1081 | if (res) { | |
1082 | res->d_sb = root_inode->i_sb; | |
1083 | res->d_parent = res; | |
1084 | d_instantiate(res, root_inode); | |
1085 | } | |
1086 | } | |
1087 | return res; | |
1088 | } | |
1089 | ||
1090 | static inline struct hlist_head *d_hash(struct dentry *parent, | |
1091 | unsigned long hash) | |
1092 | { | |
1093 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; | |
1094 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); | |
1095 | return dentry_hashtable + (hash & D_HASHMASK); | |
1096 | } | |
1097 | ||
1098 | /** | |
1099 | * d_alloc_anon - allocate an anonymous dentry | |
1100 | * @inode: inode to allocate the dentry for | |
1101 | * | |
1102 | * This is similar to d_alloc_root. It is used by filesystems when | |
1103 | * creating a dentry for a given inode, often in the process of | |
1104 | * mapping a filehandle to a dentry. The returned dentry may be | |
1105 | * anonymous, or may have a full name (if the inode was already | |
1106 | * in the cache). The file system may need to make further | |
1107 | * efforts to connect this dentry into the dcache properly. | |
1108 | * | |
1109 | * When called on a directory inode, we must ensure that | |
1110 | * the inode only ever has one dentry. If a dentry is | |
1111 | * found, that is returned instead of allocating a new one. | |
1112 | * | |
1113 | * On successful return, the reference to the inode has been transferred | |
1114 | * to the dentry. If %NULL is returned (indicating kmalloc failure), | |
1115 | * the reference on the inode has not been released. | |
1116 | */ | |
1117 | ||
1118 | struct dentry * d_alloc_anon(struct inode *inode) | |
1119 | { | |
1120 | static const struct qstr anonstring = { .name = "" }; | |
1121 | struct dentry *tmp; | |
1122 | struct dentry *res; | |
1123 | ||
1124 | if ((res = d_find_alias(inode))) { | |
1125 | iput(inode); | |
1126 | return res; | |
1127 | } | |
1128 | ||
1129 | tmp = d_alloc(NULL, &anonstring); | |
1130 | if (!tmp) | |
1131 | return NULL; | |
1132 | ||
1133 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ | |
1134 | ||
1135 | spin_lock(&dcache_lock); | |
1136 | res = __d_find_alias(inode, 0); | |
1137 | if (!res) { | |
1138 | /* attach a disconnected dentry */ | |
1139 | res = tmp; | |
1140 | tmp = NULL; | |
1141 | spin_lock(&res->d_lock); | |
1142 | res->d_sb = inode->i_sb; | |
1143 | res->d_parent = res; | |
1144 | res->d_inode = inode; | |
1145 | res->d_flags |= DCACHE_DISCONNECTED; | |
1146 | res->d_flags &= ~DCACHE_UNHASHED; | |
1147 | list_add(&res->d_alias, &inode->i_dentry); | |
1148 | hlist_add_head(&res->d_hash, &inode->i_sb->s_anon); | |
1149 | spin_unlock(&res->d_lock); | |
1150 | ||
1151 | inode = NULL; /* don't drop reference */ | |
1152 | } | |
1153 | spin_unlock(&dcache_lock); | |
1154 | ||
1155 | if (inode) | |
1156 | iput(inode); | |
1157 | if (tmp) | |
1158 | dput(tmp); | |
1159 | return res; | |
1160 | } | |
1161 | ||
1162 | ||
1163 | /** | |
1164 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1165 | * @inode: the inode which may have a disconnected dentry | |
1166 | * @dentry: a negative dentry which we want to point to the inode. | |
1167 | * | |
1168 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1169 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1170 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1171 | * | |
1172 | * This is needed in the lookup routine of any filesystem that is exportable | |
1173 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1174 | * | |
1175 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1176 | * is returned. This matches the expected return value of ->lookup. | |
1177 | * | |
1178 | */ | |
1179 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1180 | { | |
1181 | struct dentry *new = NULL; | |
1182 | ||
21c0d8fd | 1183 | if (inode && S_ISDIR(inode->i_mode)) { |
1da177e4 LT |
1184 | spin_lock(&dcache_lock); |
1185 | new = __d_find_alias(inode, 1); | |
1186 | if (new) { | |
1187 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); | |
c32ccd87 | 1188 | fsnotify_d_instantiate(new, inode); |
1da177e4 LT |
1189 | spin_unlock(&dcache_lock); |
1190 | security_d_instantiate(new, inode); | |
1191 | d_rehash(dentry); | |
1192 | d_move(new, dentry); | |
1193 | iput(inode); | |
1194 | } else { | |
1195 | /* d_instantiate takes dcache_lock, so we do it by hand */ | |
1196 | list_add(&dentry->d_alias, &inode->i_dentry); | |
1197 | dentry->d_inode = inode; | |
c32ccd87 | 1198 | fsnotify_d_instantiate(dentry, inode); |
1da177e4 LT |
1199 | spin_unlock(&dcache_lock); |
1200 | security_d_instantiate(dentry, inode); | |
1201 | d_rehash(dentry); | |
1202 | } | |
1203 | } else | |
1204 | d_add(dentry, inode); | |
1205 | return new; | |
1206 | } | |
1207 | ||
1208 | ||
1209 | /** | |
1210 | * d_lookup - search for a dentry | |
1211 | * @parent: parent dentry | |
1212 | * @name: qstr of name we wish to find | |
1213 | * | |
1214 | * Searches the children of the parent dentry for the name in question. If | |
1215 | * the dentry is found its reference count is incremented and the dentry | |
1216 | * is returned. The caller must use d_put to free the entry when it has | |
1217 | * finished using it. %NULL is returned on failure. | |
1218 | * | |
1219 | * __d_lookup is dcache_lock free. The hash list is protected using RCU. | |
1220 | * Memory barriers are used while updating and doing lockless traversal. | |
1221 | * To avoid races with d_move while rename is happening, d_lock is used. | |
1222 | * | |
1223 | * Overflows in memcmp(), while d_move, are avoided by keeping the length | |
1224 | * and name pointer in one structure pointed by d_qstr. | |
1225 | * | |
1226 | * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while | |
1227 | * lookup is going on. | |
1228 | * | |
1229 | * dentry_unused list is not updated even if lookup finds the required dentry | |
1230 | * in there. It is updated in places such as prune_dcache, shrink_dcache_sb, | |
1231 | * select_parent and __dget_locked. This laziness saves lookup from dcache_lock | |
1232 | * acquisition. | |
1233 | * | |
1234 | * d_lookup() is protected against the concurrent renames in some unrelated | |
1235 | * directory using the seqlockt_t rename_lock. | |
1236 | */ | |
1237 | ||
1238 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) | |
1239 | { | |
1240 | struct dentry * dentry = NULL; | |
1241 | unsigned long seq; | |
1242 | ||
1243 | do { | |
1244 | seq = read_seqbegin(&rename_lock); | |
1245 | dentry = __d_lookup(parent, name); | |
1246 | if (dentry) | |
1247 | break; | |
1248 | } while (read_seqretry(&rename_lock, seq)); | |
1249 | return dentry; | |
1250 | } | |
1251 | ||
1252 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) | |
1253 | { | |
1254 | unsigned int len = name->len; | |
1255 | unsigned int hash = name->hash; | |
1256 | const unsigned char *str = name->name; | |
1257 | struct hlist_head *head = d_hash(parent,hash); | |
1258 | struct dentry *found = NULL; | |
1259 | struct hlist_node *node; | |
665a7583 | 1260 | struct dentry *dentry; |
1da177e4 LT |
1261 | |
1262 | rcu_read_lock(); | |
1263 | ||
665a7583 | 1264 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
1da177e4 LT |
1265 | struct qstr *qstr; |
1266 | ||
1da177e4 LT |
1267 | if (dentry->d_name.hash != hash) |
1268 | continue; | |
1269 | if (dentry->d_parent != parent) | |
1270 | continue; | |
1271 | ||
1272 | spin_lock(&dentry->d_lock); | |
1273 | ||
1274 | /* | |
1275 | * Recheck the dentry after taking the lock - d_move may have | |
1276 | * changed things. Don't bother checking the hash because we're | |
1277 | * about to compare the whole name anyway. | |
1278 | */ | |
1279 | if (dentry->d_parent != parent) | |
1280 | goto next; | |
1281 | ||
1282 | /* | |
1283 | * It is safe to compare names since d_move() cannot | |
1284 | * change the qstr (protected by d_lock). | |
1285 | */ | |
1286 | qstr = &dentry->d_name; | |
1287 | if (parent->d_op && parent->d_op->d_compare) { | |
1288 | if (parent->d_op->d_compare(parent, qstr, name)) | |
1289 | goto next; | |
1290 | } else { | |
1291 | if (qstr->len != len) | |
1292 | goto next; | |
1293 | if (memcmp(qstr->name, str, len)) | |
1294 | goto next; | |
1295 | } | |
1296 | ||
1297 | if (!d_unhashed(dentry)) { | |
1298 | atomic_inc(&dentry->d_count); | |
1299 | found = dentry; | |
1300 | } | |
1301 | spin_unlock(&dentry->d_lock); | |
1302 | break; | |
1303 | next: | |
1304 | spin_unlock(&dentry->d_lock); | |
1305 | } | |
1306 | rcu_read_unlock(); | |
1307 | ||
1308 | return found; | |
1309 | } | |
1310 | ||
3e7e241f EB |
1311 | /** |
1312 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
1313 | * @dir: Directory to search in | |
1314 | * @name: qstr of name we wish to find | |
1315 | * | |
1316 | * On hash failure or on lookup failure NULL is returned. | |
1317 | */ | |
1318 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
1319 | { | |
1320 | struct dentry *dentry = NULL; | |
1321 | ||
1322 | /* | |
1323 | * Check for a fs-specific hash function. Note that we must | |
1324 | * calculate the standard hash first, as the d_op->d_hash() | |
1325 | * routine may choose to leave the hash value unchanged. | |
1326 | */ | |
1327 | name->hash = full_name_hash(name->name, name->len); | |
1328 | if (dir->d_op && dir->d_op->d_hash) { | |
1329 | if (dir->d_op->d_hash(dir, name) < 0) | |
1330 | goto out; | |
1331 | } | |
1332 | dentry = d_lookup(dir, name); | |
1333 | out: | |
1334 | return dentry; | |
1335 | } | |
1336 | ||
1da177e4 LT |
1337 | /** |
1338 | * d_validate - verify dentry provided from insecure source | |
1339 | * @dentry: The dentry alleged to be valid child of @dparent | |
1340 | * @dparent: The parent dentry (known to be valid) | |
1341 | * @hash: Hash of the dentry | |
1342 | * @len: Length of the name | |
1343 | * | |
1344 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
1345 | * This is used by ncpfs in its readdir implementation. | |
1346 | * Zero is returned in the dentry is invalid. | |
1347 | */ | |
1348 | ||
1349 | int d_validate(struct dentry *dentry, struct dentry *dparent) | |
1350 | { | |
1351 | struct hlist_head *base; | |
1352 | struct hlist_node *lhp; | |
1353 | ||
1354 | /* Check whether the ptr might be valid at all.. */ | |
1355 | if (!kmem_ptr_validate(dentry_cache, dentry)) | |
1356 | goto out; | |
1357 | ||
1358 | if (dentry->d_parent != dparent) | |
1359 | goto out; | |
1360 | ||
1361 | spin_lock(&dcache_lock); | |
1362 | base = d_hash(dparent, dentry->d_name.hash); | |
1363 | hlist_for_each(lhp,base) { | |
665a7583 | 1364 | /* hlist_for_each_entry_rcu() not required for d_hash list |
1da177e4 LT |
1365 | * as it is parsed under dcache_lock |
1366 | */ | |
1367 | if (dentry == hlist_entry(lhp, struct dentry, d_hash)) { | |
1368 | __dget_locked(dentry); | |
1369 | spin_unlock(&dcache_lock); | |
1370 | return 1; | |
1371 | } | |
1372 | } | |
1373 | spin_unlock(&dcache_lock); | |
1374 | out: | |
1375 | return 0; | |
1376 | } | |
1377 | ||
1378 | /* | |
1379 | * When a file is deleted, we have two options: | |
1380 | * - turn this dentry into a negative dentry | |
1381 | * - unhash this dentry and free it. | |
1382 | * | |
1383 | * Usually, we want to just turn this into | |
1384 | * a negative dentry, but if anybody else is | |
1385 | * currently using the dentry or the inode | |
1386 | * we can't do that and we fall back on removing | |
1387 | * it from the hash queues and waiting for | |
1388 | * it to be deleted later when it has no users | |
1389 | */ | |
1390 | ||
1391 | /** | |
1392 | * d_delete - delete a dentry | |
1393 | * @dentry: The dentry to delete | |
1394 | * | |
1395 | * Turn the dentry into a negative dentry if possible, otherwise | |
1396 | * remove it from the hash queues so it can be deleted later | |
1397 | */ | |
1398 | ||
1399 | void d_delete(struct dentry * dentry) | |
1400 | { | |
7a91bf7f | 1401 | int isdir = 0; |
1da177e4 LT |
1402 | /* |
1403 | * Are we the only user? | |
1404 | */ | |
1405 | spin_lock(&dcache_lock); | |
1406 | spin_lock(&dentry->d_lock); | |
7a91bf7f | 1407 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
1da177e4 LT |
1408 | if (atomic_read(&dentry->d_count) == 1) { |
1409 | dentry_iput(dentry); | |
7a91bf7f | 1410 | fsnotify_nameremove(dentry, isdir); |
7a2bd3f7 AG |
1411 | |
1412 | /* remove this and other inotify debug checks after 2.6.18 */ | |
1413 | dentry->d_flags &= ~DCACHE_INOTIFY_PARENT_WATCHED; | |
1da177e4 LT |
1414 | return; |
1415 | } | |
1416 | ||
1417 | if (!d_unhashed(dentry)) | |
1418 | __d_drop(dentry); | |
1419 | ||
1420 | spin_unlock(&dentry->d_lock); | |
1421 | spin_unlock(&dcache_lock); | |
7a91bf7f JM |
1422 | |
1423 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 LT |
1424 | } |
1425 | ||
1426 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) | |
1427 | { | |
1428 | ||
1429 | entry->d_flags &= ~DCACHE_UNHASHED; | |
1430 | hlist_add_head_rcu(&entry->d_hash, list); | |
1431 | } | |
1432 | ||
770bfad8 DH |
1433 | static void _d_rehash(struct dentry * entry) |
1434 | { | |
1435 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
1436 | } | |
1437 | ||
1da177e4 LT |
1438 | /** |
1439 | * d_rehash - add an entry back to the hash | |
1440 | * @entry: dentry to add to the hash | |
1441 | * | |
1442 | * Adds a dentry to the hash according to its name. | |
1443 | */ | |
1444 | ||
1445 | void d_rehash(struct dentry * entry) | |
1446 | { | |
1da177e4 LT |
1447 | spin_lock(&dcache_lock); |
1448 | spin_lock(&entry->d_lock); | |
770bfad8 | 1449 | _d_rehash(entry); |
1da177e4 LT |
1450 | spin_unlock(&entry->d_lock); |
1451 | spin_unlock(&dcache_lock); | |
1452 | } | |
1453 | ||
1454 | #define do_switch(x,y) do { \ | |
1455 | __typeof__ (x) __tmp = x; \ | |
1456 | x = y; y = __tmp; } while (0) | |
1457 | ||
1458 | /* | |
1459 | * When switching names, the actual string doesn't strictly have to | |
1460 | * be preserved in the target - because we're dropping the target | |
1461 | * anyway. As such, we can just do a simple memcpy() to copy over | |
1462 | * the new name before we switch. | |
1463 | * | |
1464 | * Note that we have to be a lot more careful about getting the hash | |
1465 | * switched - we have to switch the hash value properly even if it | |
1466 | * then no longer matches the actual (corrupted) string of the target. | |
1467 | * The hash value has to match the hash queue that the dentry is on.. | |
1468 | */ | |
1469 | static void switch_names(struct dentry *dentry, struct dentry *target) | |
1470 | { | |
1471 | if (dname_external(target)) { | |
1472 | if (dname_external(dentry)) { | |
1473 | /* | |
1474 | * Both external: swap the pointers | |
1475 | */ | |
1476 | do_switch(target->d_name.name, dentry->d_name.name); | |
1477 | } else { | |
1478 | /* | |
1479 | * dentry:internal, target:external. Steal target's | |
1480 | * storage and make target internal. | |
1481 | */ | |
1482 | dentry->d_name.name = target->d_name.name; | |
1483 | target->d_name.name = target->d_iname; | |
1484 | } | |
1485 | } else { | |
1486 | if (dname_external(dentry)) { | |
1487 | /* | |
1488 | * dentry:external, target:internal. Give dentry's | |
1489 | * storage to target and make dentry internal | |
1490 | */ | |
1491 | memcpy(dentry->d_iname, target->d_name.name, | |
1492 | target->d_name.len + 1); | |
1493 | target->d_name.name = dentry->d_name.name; | |
1494 | dentry->d_name.name = dentry->d_iname; | |
1495 | } else { | |
1496 | /* | |
1497 | * Both are internal. Just copy target to dentry | |
1498 | */ | |
1499 | memcpy(dentry->d_iname, target->d_name.name, | |
1500 | target->d_name.len + 1); | |
1501 | } | |
1502 | } | |
1503 | } | |
1504 | ||
1505 | /* | |
1506 | * We cannibalize "target" when moving dentry on top of it, | |
1507 | * because it's going to be thrown away anyway. We could be more | |
1508 | * polite about it, though. | |
1509 | * | |
1510 | * This forceful removal will result in ugly /proc output if | |
1511 | * somebody holds a file open that got deleted due to a rename. | |
1512 | * We could be nicer about the deleted file, and let it show | |
1513 | * up under the name it got deleted rather than the name that | |
1514 | * deleted it. | |
1515 | */ | |
1516 | ||
9eaef27b TM |
1517 | /* |
1518 | * d_move_locked - move a dentry | |
1da177e4 LT |
1519 | * @dentry: entry to move |
1520 | * @target: new dentry | |
1521 | * | |
1522 | * Update the dcache to reflect the move of a file name. Negative | |
1523 | * dcache entries should not be moved in this way. | |
1524 | */ | |
9eaef27b | 1525 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
1da177e4 LT |
1526 | { |
1527 | struct hlist_head *list; | |
1528 | ||
1529 | if (!dentry->d_inode) | |
1530 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
1531 | ||
1da177e4 LT |
1532 | write_seqlock(&rename_lock); |
1533 | /* | |
1534 | * XXXX: do we really need to take target->d_lock? | |
1535 | */ | |
1536 | if (target < dentry) { | |
1537 | spin_lock(&target->d_lock); | |
a90b9c05 | 1538 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1539 | } else { |
1540 | spin_lock(&dentry->d_lock); | |
a90b9c05 | 1541 | spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1542 | } |
1543 | ||
1544 | /* Move the dentry to the target hash queue, if on different bucket */ | |
1545 | if (dentry->d_flags & DCACHE_UNHASHED) | |
1546 | goto already_unhashed; | |
1547 | ||
1548 | hlist_del_rcu(&dentry->d_hash); | |
1549 | ||
1550 | already_unhashed: | |
1551 | list = d_hash(target->d_parent, target->d_name.hash); | |
1552 | __d_rehash(dentry, list); | |
1553 | ||
1554 | /* Unhash the target: dput() will then get rid of it */ | |
1555 | __d_drop(target); | |
1556 | ||
5160ee6f ED |
1557 | list_del(&dentry->d_u.d_child); |
1558 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
1559 | |
1560 | /* Switch the names.. */ | |
1561 | switch_names(dentry, target); | |
1562 | do_switch(dentry->d_name.len, target->d_name.len); | |
1563 | do_switch(dentry->d_name.hash, target->d_name.hash); | |
1564 | ||
1565 | /* ... and switch the parents */ | |
1566 | if (IS_ROOT(dentry)) { | |
1567 | dentry->d_parent = target->d_parent; | |
1568 | target->d_parent = target; | |
5160ee6f | 1569 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 LT |
1570 | } else { |
1571 | do_switch(dentry->d_parent, target->d_parent); | |
1572 | ||
1573 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 1574 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
1575 | } |
1576 | ||
5160ee6f | 1577 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
1da177e4 | 1578 | spin_unlock(&target->d_lock); |
c32ccd87 | 1579 | fsnotify_d_move(dentry); |
1da177e4 LT |
1580 | spin_unlock(&dentry->d_lock); |
1581 | write_sequnlock(&rename_lock); | |
9eaef27b TM |
1582 | } |
1583 | ||
1584 | /** | |
1585 | * d_move - move a dentry | |
1586 | * @dentry: entry to move | |
1587 | * @target: new dentry | |
1588 | * | |
1589 | * Update the dcache to reflect the move of a file name. Negative | |
1590 | * dcache entries should not be moved in this way. | |
1591 | */ | |
1592 | ||
1593 | void d_move(struct dentry * dentry, struct dentry * target) | |
1594 | { | |
1595 | spin_lock(&dcache_lock); | |
1596 | d_move_locked(dentry, target); | |
1da177e4 LT |
1597 | spin_unlock(&dcache_lock); |
1598 | } | |
1599 | ||
9eaef27b TM |
1600 | /* |
1601 | * Helper that returns 1 if p1 is a parent of p2, else 0 | |
1602 | */ | |
1603 | static int d_isparent(struct dentry *p1, struct dentry *p2) | |
1604 | { | |
1605 | struct dentry *p; | |
1606 | ||
1607 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1608 | if (p->d_parent == p1) | |
1609 | return 1; | |
1610 | } | |
1611 | return 0; | |
1612 | } | |
1613 | ||
1614 | /* | |
1615 | * This helper attempts to cope with remotely renamed directories | |
1616 | * | |
1617 | * It assumes that the caller is already holding | |
1618 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock | |
1619 | * | |
1620 | * Note: If ever the locking in lock_rename() changes, then please | |
1621 | * remember to update this too... | |
1622 | * | |
1623 | * On return, dcache_lock will have been unlocked. | |
1624 | */ | |
1625 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) | |
1626 | { | |
1627 | struct mutex *m1 = NULL, *m2 = NULL; | |
1628 | struct dentry *ret; | |
1629 | ||
1630 | /* If alias and dentry share a parent, then no extra locks required */ | |
1631 | if (alias->d_parent == dentry->d_parent) | |
1632 | goto out_unalias; | |
1633 | ||
1634 | /* Check for loops */ | |
1635 | ret = ERR_PTR(-ELOOP); | |
1636 | if (d_isparent(alias, dentry)) | |
1637 | goto out_err; | |
1638 | ||
1639 | /* See lock_rename() */ | |
1640 | ret = ERR_PTR(-EBUSY); | |
1641 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) | |
1642 | goto out_err; | |
1643 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
1644 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
1645 | goto out_err; | |
1646 | m2 = &alias->d_parent->d_inode->i_mutex; | |
1647 | out_unalias: | |
1648 | d_move_locked(alias, dentry); | |
1649 | ret = alias; | |
1650 | out_err: | |
1651 | spin_unlock(&dcache_lock); | |
1652 | if (m2) | |
1653 | mutex_unlock(m2); | |
1654 | if (m1) | |
1655 | mutex_unlock(m1); | |
1656 | return ret; | |
1657 | } | |
1658 | ||
770bfad8 DH |
1659 | /* |
1660 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
1661 | * named dentry in place of the dentry to be replaced. | |
1662 | */ | |
1663 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
1664 | { | |
1665 | struct dentry *dparent, *aparent; | |
1666 | ||
1667 | switch_names(dentry, anon); | |
1668 | do_switch(dentry->d_name.len, anon->d_name.len); | |
1669 | do_switch(dentry->d_name.hash, anon->d_name.hash); | |
1670 | ||
1671 | dparent = dentry->d_parent; | |
1672 | aparent = anon->d_parent; | |
1673 | ||
1674 | dentry->d_parent = (aparent == anon) ? dentry : aparent; | |
1675 | list_del(&dentry->d_u.d_child); | |
1676 | if (!IS_ROOT(dentry)) | |
1677 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); | |
1678 | else | |
1679 | INIT_LIST_HEAD(&dentry->d_u.d_child); | |
1680 | ||
1681 | anon->d_parent = (dparent == dentry) ? anon : dparent; | |
1682 | list_del(&anon->d_u.d_child); | |
1683 | if (!IS_ROOT(anon)) | |
1684 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); | |
1685 | else | |
1686 | INIT_LIST_HEAD(&anon->d_u.d_child); | |
1687 | ||
1688 | anon->d_flags &= ~DCACHE_DISCONNECTED; | |
1689 | } | |
1690 | ||
1691 | /** | |
1692 | * d_materialise_unique - introduce an inode into the tree | |
1693 | * @dentry: candidate dentry | |
1694 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
1695 | * | |
1696 | * Introduces an dentry into the tree, substituting an extant disconnected | |
1697 | * root directory alias in its place if there is one | |
1698 | */ | |
1699 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
1700 | { | |
9eaef27b | 1701 | struct dentry *actual; |
770bfad8 DH |
1702 | |
1703 | BUG_ON(!d_unhashed(dentry)); | |
1704 | ||
1705 | spin_lock(&dcache_lock); | |
1706 | ||
1707 | if (!inode) { | |
1708 | actual = dentry; | |
1709 | dentry->d_inode = NULL; | |
1710 | goto found_lock; | |
1711 | } | |
1712 | ||
9eaef27b TM |
1713 | if (S_ISDIR(inode->i_mode)) { |
1714 | struct dentry *alias; | |
1715 | ||
1716 | /* Does an aliased dentry already exist? */ | |
1717 | alias = __d_find_alias(inode, 0); | |
1718 | if (alias) { | |
1719 | actual = alias; | |
1720 | /* Is this an anonymous mountpoint that we could splice | |
1721 | * into our tree? */ | |
1722 | if (IS_ROOT(alias)) { | |
1723 | spin_lock(&alias->d_lock); | |
1724 | __d_materialise_dentry(dentry, alias); | |
1725 | __d_drop(alias); | |
1726 | goto found; | |
1727 | } | |
1728 | /* Nope, but we must(!) avoid directory aliasing */ | |
1729 | actual = __d_unalias(dentry, alias); | |
1730 | if (IS_ERR(actual)) | |
1731 | dput(alias); | |
1732 | goto out_nolock; | |
1733 | } | |
770bfad8 DH |
1734 | } |
1735 | ||
1736 | /* Add a unique reference */ | |
1737 | actual = __d_instantiate_unique(dentry, inode); | |
1738 | if (!actual) | |
1739 | actual = dentry; | |
1740 | else if (unlikely(!d_unhashed(actual))) | |
1741 | goto shouldnt_be_hashed; | |
1742 | ||
1743 | found_lock: | |
1744 | spin_lock(&actual->d_lock); | |
1745 | found: | |
1746 | _d_rehash(actual); | |
1747 | spin_unlock(&actual->d_lock); | |
1748 | spin_unlock(&dcache_lock); | |
9eaef27b | 1749 | out_nolock: |
770bfad8 DH |
1750 | if (actual == dentry) { |
1751 | security_d_instantiate(dentry, inode); | |
1752 | return NULL; | |
1753 | } | |
1754 | ||
1755 | iput(inode); | |
1756 | return actual; | |
1757 | ||
770bfad8 DH |
1758 | shouldnt_be_hashed: |
1759 | spin_unlock(&dcache_lock); | |
1760 | BUG(); | |
1761 | goto shouldnt_be_hashed; | |
1762 | } | |
1763 | ||
1da177e4 LT |
1764 | /** |
1765 | * d_path - return the path of a dentry | |
1766 | * @dentry: dentry to report | |
1767 | * @vfsmnt: vfsmnt to which the dentry belongs | |
1768 | * @root: root dentry | |
1769 | * @rootmnt: vfsmnt to which the root dentry belongs | |
1770 | * @buffer: buffer to return value in | |
1771 | * @buflen: buffer length | |
1772 | * | |
552ce544 LT |
1773 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
1774 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
1da177e4 | 1775 | * |
552ce544 LT |
1776 | * Returns the buffer or an error code if the path was too long. |
1777 | * | |
1778 | * "buflen" should be positive. Caller holds the dcache_lock. | |
1da177e4 | 1779 | */ |
552ce544 LT |
1780 | static char * __d_path( struct dentry *dentry, struct vfsmount *vfsmnt, |
1781 | struct dentry *root, struct vfsmount *rootmnt, | |
1782 | char *buffer, int buflen) | |
1da177e4 | 1783 | { |
552ce544 LT |
1784 | char * end = buffer+buflen; |
1785 | char * retval; | |
1786 | int namelen; | |
1da177e4 | 1787 | |
552ce544 LT |
1788 | *--end = '\0'; |
1789 | buflen--; | |
1da177e4 | 1790 | if (!IS_ROOT(dentry) && d_unhashed(dentry)) { |
eb3dfb0c | 1791 | buflen -= 10; |
552ce544 LT |
1792 | end -= 10; |
1793 | if (buflen < 0) | |
1794 | goto Elong; | |
1795 | memcpy(end, " (deleted)", 10); | |
1da177e4 | 1796 | } |
552ce544 LT |
1797 | |
1798 | if (buflen < 1) | |
1799 | goto Elong; | |
1800 | /* Get '/' right */ | |
1801 | retval = end-1; | |
1802 | *retval = '/'; | |
1803 | ||
1804 | for (;;) { | |
1da177e4 LT |
1805 | struct dentry * parent; |
1806 | ||
552ce544 LT |
1807 | if (dentry == root && vfsmnt == rootmnt) |
1808 | break; | |
1da177e4 | 1809 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 1810 | /* Global root? */ |
1da177e4 LT |
1811 | spin_lock(&vfsmount_lock); |
1812 | if (vfsmnt->mnt_parent == vfsmnt) { | |
1813 | spin_unlock(&vfsmount_lock); | |
1814 | goto global_root; | |
1815 | } | |
1816 | dentry = vfsmnt->mnt_mountpoint; | |
1817 | vfsmnt = vfsmnt->mnt_parent; | |
1818 | spin_unlock(&vfsmount_lock); | |
1819 | continue; | |
1820 | } | |
1821 | parent = dentry->d_parent; | |
1822 | prefetch(parent); | |
1823 | namelen = dentry->d_name.len; | |
eb3dfb0c | 1824 | buflen -= namelen + 1; |
552ce544 LT |
1825 | if (buflen < 0) |
1826 | goto Elong; | |
1827 | end -= namelen; | |
1828 | memcpy(end, dentry->d_name.name, namelen); | |
1829 | *--end = '/'; | |
1830 | retval = end; | |
1da177e4 LT |
1831 | dentry = parent; |
1832 | } | |
1833 | ||
552ce544 | 1834 | return retval; |
1da177e4 LT |
1835 | |
1836 | global_root: | |
1837 | namelen = dentry->d_name.len; | |
552ce544 LT |
1838 | buflen -= namelen; |
1839 | if (buflen < 0) | |
1da177e4 | 1840 | goto Elong; |
552ce544 LT |
1841 | retval -= namelen-1; /* hit the slash */ |
1842 | memcpy(retval, dentry->d_name.name, namelen); | |
1843 | return retval; | |
1da177e4 | 1844 | Elong: |
552ce544 | 1845 | return ERR_PTR(-ENAMETOOLONG); |
1da177e4 LT |
1846 | } |
1847 | ||
1848 | /* write full pathname into buffer and return start of pathname */ | |
552ce544 LT |
1849 | char * d_path(struct dentry *dentry, struct vfsmount *vfsmnt, |
1850 | char *buf, int buflen) | |
1da177e4 LT |
1851 | { |
1852 | char *res; | |
1853 | struct vfsmount *rootmnt; | |
1854 | struct dentry *root; | |
1855 | ||
1856 | read_lock(¤t->fs->lock); | |
1857 | rootmnt = mntget(current->fs->rootmnt); | |
1858 | root = dget(current->fs->root); | |
1859 | read_unlock(¤t->fs->lock); | |
552ce544 LT |
1860 | spin_lock(&dcache_lock); |
1861 | res = __d_path(dentry, vfsmnt, root, rootmnt, buf, buflen); | |
1862 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
1863 | dput(root); |
1864 | mntput(rootmnt); | |
1865 | return res; | |
1866 | } | |
1867 | ||
1868 | /* | |
1869 | * NOTE! The user-level library version returns a | |
1870 | * character pointer. The kernel system call just | |
1871 | * returns the length of the buffer filled (which | |
1872 | * includes the ending '\0' character), or a negative | |
1873 | * error value. So libc would do something like | |
1874 | * | |
1875 | * char *getcwd(char * buf, size_t size) | |
1876 | * { | |
1877 | * int retval; | |
1878 | * | |
1879 | * retval = sys_getcwd(buf, size); | |
1880 | * if (retval >= 0) | |
1881 | * return buf; | |
1882 | * errno = -retval; | |
1883 | * return NULL; | |
1884 | * } | |
1885 | */ | |
1886 | asmlinkage long sys_getcwd(char __user *buf, unsigned long size) | |
1887 | { | |
552ce544 | 1888 | int error; |
1da177e4 LT |
1889 | struct vfsmount *pwdmnt, *rootmnt; |
1890 | struct dentry *pwd, *root; | |
552ce544 | 1891 | char *page = (char *) __get_free_page(GFP_USER); |
1da177e4 LT |
1892 | |
1893 | if (!page) | |
1894 | return -ENOMEM; | |
1895 | ||
1896 | read_lock(¤t->fs->lock); | |
1897 | pwdmnt = mntget(current->fs->pwdmnt); | |
1898 | pwd = dget(current->fs->pwd); | |
1899 | rootmnt = mntget(current->fs->rootmnt); | |
1900 | root = dget(current->fs->root); | |
1901 | read_unlock(¤t->fs->lock); | |
1902 | ||
552ce544 LT |
1903 | error = -ENOENT; |
1904 | /* Has the current directory has been unlinked? */ | |
1905 | spin_lock(&dcache_lock); | |
1906 | if (pwd->d_parent == pwd || !d_unhashed(pwd)) { | |
1907 | unsigned long len; | |
1908 | char * cwd; | |
1da177e4 | 1909 | |
552ce544 LT |
1910 | cwd = __d_path(pwd, pwdmnt, root, rootmnt, page, PAGE_SIZE); |
1911 | spin_unlock(&dcache_lock); | |
1912 | ||
1913 | error = PTR_ERR(cwd); | |
1914 | if (IS_ERR(cwd)) | |
1915 | goto out; | |
1916 | ||
1917 | error = -ERANGE; | |
1918 | len = PAGE_SIZE + page - cwd; | |
1919 | if (len <= size) { | |
1920 | error = len; | |
1921 | if (copy_to_user(buf, cwd, len)) | |
1922 | error = -EFAULT; | |
1923 | } | |
1924 | } else | |
1925 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
1926 | |
1927 | out: | |
1928 | dput(pwd); | |
1929 | mntput(pwdmnt); | |
1930 | dput(root); | |
1931 | mntput(rootmnt); | |
1932 | free_page((unsigned long) page); | |
1933 | return error; | |
1934 | } | |
1935 | ||
1936 | /* | |
1937 | * Test whether new_dentry is a subdirectory of old_dentry. | |
1938 | * | |
1939 | * Trivially implemented using the dcache structure | |
1940 | */ | |
1941 | ||
1942 | /** | |
1943 | * is_subdir - is new dentry a subdirectory of old_dentry | |
1944 | * @new_dentry: new dentry | |
1945 | * @old_dentry: old dentry | |
1946 | * | |
1947 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
1948 | * Returns 0 otherwise. | |
1949 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
1950 | */ | |
1951 | ||
1952 | int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) | |
1953 | { | |
1954 | int result; | |
1955 | struct dentry * saved = new_dentry; | |
1956 | unsigned long seq; | |
1957 | ||
1958 | /* need rcu_readlock to protect against the d_parent trashing due to | |
1959 | * d_move | |
1960 | */ | |
1961 | rcu_read_lock(); | |
1962 | do { | |
1963 | /* for restarting inner loop in case of seq retry */ | |
1964 | new_dentry = saved; | |
1965 | result = 0; | |
1966 | seq = read_seqbegin(&rename_lock); | |
1967 | for (;;) { | |
1968 | if (new_dentry != old_dentry) { | |
1969 | struct dentry * parent = new_dentry->d_parent; | |
1970 | if (parent == new_dentry) | |
1971 | break; | |
1972 | new_dentry = parent; | |
1973 | continue; | |
1974 | } | |
1975 | result = 1; | |
1976 | break; | |
1977 | } | |
1978 | } while (read_seqretry(&rename_lock, seq)); | |
1979 | rcu_read_unlock(); | |
1980 | ||
1981 | return result; | |
1982 | } | |
1983 | ||
1984 | void d_genocide(struct dentry *root) | |
1985 | { | |
1986 | struct dentry *this_parent = root; | |
1987 | struct list_head *next; | |
1988 | ||
1989 | spin_lock(&dcache_lock); | |
1990 | repeat: | |
1991 | next = this_parent->d_subdirs.next; | |
1992 | resume: | |
1993 | while (next != &this_parent->d_subdirs) { | |
1994 | struct list_head *tmp = next; | |
5160ee6f | 1995 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
1996 | next = tmp->next; |
1997 | if (d_unhashed(dentry)||!dentry->d_inode) | |
1998 | continue; | |
1999 | if (!list_empty(&dentry->d_subdirs)) { | |
2000 | this_parent = dentry; | |
2001 | goto repeat; | |
2002 | } | |
2003 | atomic_dec(&dentry->d_count); | |
2004 | } | |
2005 | if (this_parent != root) { | |
5160ee6f | 2006 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
2007 | atomic_dec(&this_parent->d_count); |
2008 | this_parent = this_parent->d_parent; | |
2009 | goto resume; | |
2010 | } | |
2011 | spin_unlock(&dcache_lock); | |
2012 | } | |
2013 | ||
2014 | /** | |
2015 | * find_inode_number - check for dentry with name | |
2016 | * @dir: directory to check | |
2017 | * @name: Name to find. | |
2018 | * | |
2019 | * Check whether a dentry already exists for the given name, | |
2020 | * and return the inode number if it has an inode. Otherwise | |
2021 | * 0 is returned. | |
2022 | * | |
2023 | * This routine is used to post-process directory listings for | |
2024 | * filesystems using synthetic inode numbers, and is necessary | |
2025 | * to keep getcwd() working. | |
2026 | */ | |
2027 | ||
2028 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) | |
2029 | { | |
2030 | struct dentry * dentry; | |
2031 | ino_t ino = 0; | |
2032 | ||
3e7e241f EB |
2033 | dentry = d_hash_and_lookup(dir, name); |
2034 | if (dentry) { | |
1da177e4 LT |
2035 | if (dentry->d_inode) |
2036 | ino = dentry->d_inode->i_ino; | |
2037 | dput(dentry); | |
2038 | } | |
1da177e4 LT |
2039 | return ino; |
2040 | } | |
2041 | ||
2042 | static __initdata unsigned long dhash_entries; | |
2043 | static int __init set_dhash_entries(char *str) | |
2044 | { | |
2045 | if (!str) | |
2046 | return 0; | |
2047 | dhash_entries = simple_strtoul(str, &str, 0); | |
2048 | return 1; | |
2049 | } | |
2050 | __setup("dhash_entries=", set_dhash_entries); | |
2051 | ||
2052 | static void __init dcache_init_early(void) | |
2053 | { | |
2054 | int loop; | |
2055 | ||
2056 | /* If hashes are distributed across NUMA nodes, defer | |
2057 | * hash allocation until vmalloc space is available. | |
2058 | */ | |
2059 | if (hashdist) | |
2060 | return; | |
2061 | ||
2062 | dentry_hashtable = | |
2063 | alloc_large_system_hash("Dentry cache", | |
2064 | sizeof(struct hlist_head), | |
2065 | dhash_entries, | |
2066 | 13, | |
2067 | HASH_EARLY, | |
2068 | &d_hash_shift, | |
2069 | &d_hash_mask, | |
2070 | 0); | |
2071 | ||
2072 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2073 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2074 | } | |
2075 | ||
2076 | static void __init dcache_init(unsigned long mempages) | |
2077 | { | |
2078 | int loop; | |
2079 | ||
2080 | /* | |
2081 | * A constructor could be added for stable state like the lists, | |
2082 | * but it is probably not worth it because of the cache nature | |
2083 | * of the dcache. | |
2084 | */ | |
0a31bd5f CL |
2085 | dentry_cache = KMEM_CACHE(dentry, |
2086 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 LT |
2087 | |
2088 | set_shrinker(DEFAULT_SEEKS, shrink_dcache_memory); | |
2089 | ||
2090 | /* Hash may have been set up in dcache_init_early */ | |
2091 | if (!hashdist) | |
2092 | return; | |
2093 | ||
2094 | dentry_hashtable = | |
2095 | alloc_large_system_hash("Dentry cache", | |
2096 | sizeof(struct hlist_head), | |
2097 | dhash_entries, | |
2098 | 13, | |
2099 | 0, | |
2100 | &d_hash_shift, | |
2101 | &d_hash_mask, | |
2102 | 0); | |
2103 | ||
2104 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2105 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2106 | } | |
2107 | ||
2108 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 2109 | struct kmem_cache *names_cachep __read_mostly; |
1da177e4 LT |
2110 | |
2111 | /* SLAB cache for file structures */ | |
e18b890b | 2112 | struct kmem_cache *filp_cachep __read_mostly; |
1da177e4 LT |
2113 | |
2114 | EXPORT_SYMBOL(d_genocide); | |
2115 | ||
1da177e4 LT |
2116 | void __init vfs_caches_init_early(void) |
2117 | { | |
2118 | dcache_init_early(); | |
2119 | inode_init_early(); | |
2120 | } | |
2121 | ||
2122 | void __init vfs_caches_init(unsigned long mempages) | |
2123 | { | |
2124 | unsigned long reserve; | |
2125 | ||
2126 | /* Base hash sizes on available memory, with a reserve equal to | |
2127 | 150% of current kernel size */ | |
2128 | ||
2129 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
2130 | mempages -= reserve; | |
2131 | ||
2132 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
2133 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
2134 | ||
2135 | filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, | |
529bf6be | 2136 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); |
1da177e4 LT |
2137 | |
2138 | dcache_init(mempages); | |
2139 | inode_init(mempages); | |
2140 | files_init(mempages); | |
2141 | mnt_init(mempages); | |
2142 | bdev_cache_init(); | |
2143 | chrdev_init(); | |
2144 | } | |
2145 | ||
2146 | EXPORT_SYMBOL(d_alloc); | |
2147 | EXPORT_SYMBOL(d_alloc_anon); | |
2148 | EXPORT_SYMBOL(d_alloc_root); | |
2149 | EXPORT_SYMBOL(d_delete); | |
2150 | EXPORT_SYMBOL(d_find_alias); | |
2151 | EXPORT_SYMBOL(d_instantiate); | |
2152 | EXPORT_SYMBOL(d_invalidate); | |
2153 | EXPORT_SYMBOL(d_lookup); | |
2154 | EXPORT_SYMBOL(d_move); | |
770bfad8 | 2155 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
1da177e4 LT |
2156 | EXPORT_SYMBOL(d_path); |
2157 | EXPORT_SYMBOL(d_prune_aliases); | |
2158 | EXPORT_SYMBOL(d_rehash); | |
2159 | EXPORT_SYMBOL(d_splice_alias); | |
2160 | EXPORT_SYMBOL(d_validate); | |
2161 | EXPORT_SYMBOL(dget_locked); | |
2162 | EXPORT_SYMBOL(dput); | |
2163 | EXPORT_SYMBOL(find_inode_number); | |
2164 | EXPORT_SYMBOL(have_submounts); | |
2165 | EXPORT_SYMBOL(names_cachep); | |
2166 | EXPORT_SYMBOL(shrink_dcache_parent); | |
2167 | EXPORT_SYMBOL(shrink_dcache_sb); |