Commit | Line | Data |
---|---|---|
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> | |
1da177e4 LT |
24 | #include <linux/hash.h> |
25 | #include <linux/cache.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/file.h> | |
29 | #include <asm/uaccess.h> | |
30 | #include <linux/security.h> | |
31 | #include <linux/seqlock.h> | |
32 | #include <linux/swap.h> | |
33 | #include <linux/bootmem.h> | |
07f3f05c | 34 | #include "internal.h" |
1da177e4 | 35 | |
1da177e4 | 36 | |
fa3536cc | 37 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
38 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
39 | ||
40 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); | |
74c3cbe3 | 41 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 LT |
42 | |
43 | EXPORT_SYMBOL(dcache_lock); | |
44 | ||
e18b890b | 45 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 LT |
46 | |
47 | #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) | |
48 | ||
49 | /* | |
50 | * This is the single most critical data structure when it comes | |
51 | * to the dcache: the hashtable for lookups. Somebody should try | |
52 | * to make this good - I've just made it work. | |
53 | * | |
54 | * This hash-function tries to avoid losing too many bits of hash | |
55 | * information, yet avoid using a prime hash-size or similar. | |
56 | */ | |
57 | #define D_HASHBITS d_hash_shift | |
58 | #define D_HASHMASK d_hash_mask | |
59 | ||
fa3536cc ED |
60 | static unsigned int d_hash_mask __read_mostly; |
61 | static unsigned int d_hash_shift __read_mostly; | |
62 | static struct hlist_head *dentry_hashtable __read_mostly; | |
1da177e4 LT |
63 | static LIST_HEAD(dentry_unused); |
64 | ||
65 | /* Statistics gathering. */ | |
66 | struct dentry_stat_t dentry_stat = { | |
67 | .age_limit = 45, | |
68 | }; | |
69 | ||
b3423415 | 70 | static void __d_free(struct dentry *dentry) |
1da177e4 | 71 | { |
1da177e4 LT |
72 | if (dname_external(dentry)) |
73 | kfree(dentry->d_name.name); | |
74 | kmem_cache_free(dentry_cache, dentry); | |
75 | } | |
76 | ||
b3423415 ED |
77 | static void d_callback(struct rcu_head *head) |
78 | { | |
79 | struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu); | |
80 | __d_free(dentry); | |
81 | } | |
82 | ||
1da177e4 LT |
83 | /* |
84 | * no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry | |
85 | * inside dcache_lock. | |
86 | */ | |
87 | static void d_free(struct dentry *dentry) | |
88 | { | |
89 | if (dentry->d_op && dentry->d_op->d_release) | |
90 | dentry->d_op->d_release(dentry); | |
b3423415 | 91 | /* if dentry was never inserted into hash, immediate free is OK */ |
e8462caa | 92 | if (hlist_unhashed(&dentry->d_hash)) |
b3423415 ED |
93 | __d_free(dentry); |
94 | else | |
95 | call_rcu(&dentry->d_u.d_rcu, d_callback); | |
1da177e4 LT |
96 | } |
97 | ||
4a0962ab CL |
98 | static void dentry_lru_remove(struct dentry *dentry) |
99 | { | |
100 | if (!list_empty(&dentry->d_lru)) { | |
101 | list_del_init(&dentry->d_lru); | |
102 | dentry_stat.nr_unused--; | |
103 | } | |
104 | } | |
105 | ||
1da177e4 LT |
106 | /* |
107 | * Release the dentry's inode, using the filesystem | |
108 | * d_iput() operation if defined. | |
109 | * Called with dcache_lock and per dentry lock held, drops both. | |
110 | */ | |
858119e1 | 111 | static void dentry_iput(struct dentry * dentry) |
1da177e4 LT |
112 | { |
113 | struct inode *inode = dentry->d_inode; | |
114 | if (inode) { | |
115 | dentry->d_inode = NULL; | |
116 | list_del_init(&dentry->d_alias); | |
117 | spin_unlock(&dentry->d_lock); | |
118 | spin_unlock(&dcache_lock); | |
f805fbda LT |
119 | if (!inode->i_nlink) |
120 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
121 | if (dentry->d_op && dentry->d_op->d_iput) |
122 | dentry->d_op->d_iput(dentry, inode); | |
123 | else | |
124 | iput(inode); | |
125 | } else { | |
126 | spin_unlock(&dentry->d_lock); | |
127 | spin_unlock(&dcache_lock); | |
128 | } | |
129 | } | |
130 | ||
d52b9086 MS |
131 | /** |
132 | * d_kill - kill dentry and return parent | |
133 | * @dentry: dentry to kill | |
134 | * | |
135 | * Called with dcache_lock and d_lock, releases both. The dentry must | |
136 | * already be unhashed and removed from the LRU. | |
137 | * | |
138 | * If this is the root of the dentry tree, return NULL. | |
139 | */ | |
140 | static struct dentry *d_kill(struct dentry *dentry) | |
141 | { | |
142 | struct dentry *parent; | |
143 | ||
144 | list_del(&dentry->d_u.d_child); | |
145 | dentry_stat.nr_dentry--; /* For d_free, below */ | |
146 | /*drops the locks, at that point nobody can reach this dentry */ | |
147 | dentry_iput(dentry); | |
148 | parent = dentry->d_parent; | |
149 | d_free(dentry); | |
150 | return dentry == parent ? NULL : parent; | |
151 | } | |
152 | ||
1da177e4 LT |
153 | /* |
154 | * This is dput | |
155 | * | |
156 | * This is complicated by the fact that we do not want to put | |
157 | * dentries that are no longer on any hash chain on the unused | |
158 | * list: we'd much rather just get rid of them immediately. | |
159 | * | |
160 | * However, that implies that we have to traverse the dentry | |
161 | * tree upwards to the parents which might _also_ now be | |
162 | * scheduled for deletion (it may have been only waiting for | |
163 | * its last child to go away). | |
164 | * | |
165 | * This tail recursion is done by hand as we don't want to depend | |
166 | * on the compiler to always get this right (gcc generally doesn't). | |
167 | * Real recursion would eat up our stack space. | |
168 | */ | |
169 | ||
170 | /* | |
171 | * dput - release a dentry | |
172 | * @dentry: dentry to release | |
173 | * | |
174 | * Release a dentry. This will drop the usage count and if appropriate | |
175 | * call the dentry unlink method as well as removing it from the queues and | |
176 | * releasing its resources. If the parent dentries were scheduled for release | |
177 | * they too may now get deleted. | |
178 | * | |
179 | * no dcache lock, please. | |
180 | */ | |
181 | ||
182 | void dput(struct dentry *dentry) | |
183 | { | |
184 | if (!dentry) | |
185 | return; | |
186 | ||
187 | repeat: | |
188 | if (atomic_read(&dentry->d_count) == 1) | |
189 | might_sleep(); | |
190 | if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) | |
191 | return; | |
192 | ||
193 | spin_lock(&dentry->d_lock); | |
194 | if (atomic_read(&dentry->d_count)) { | |
195 | spin_unlock(&dentry->d_lock); | |
196 | spin_unlock(&dcache_lock); | |
197 | return; | |
198 | } | |
199 | ||
200 | /* | |
201 | * AV: ->d_delete() is _NOT_ allowed to block now. | |
202 | */ | |
203 | if (dentry->d_op && dentry->d_op->d_delete) { | |
204 | if (dentry->d_op->d_delete(dentry)) | |
205 | goto unhash_it; | |
206 | } | |
207 | /* Unreachable? Get rid of it */ | |
208 | if (d_unhashed(dentry)) | |
209 | goto kill_it; | |
210 | if (list_empty(&dentry->d_lru)) { | |
211 | dentry->d_flags |= DCACHE_REFERENCED; | |
212 | list_add(&dentry->d_lru, &dentry_unused); | |
213 | dentry_stat.nr_unused++; | |
214 | } | |
215 | spin_unlock(&dentry->d_lock); | |
216 | spin_unlock(&dcache_lock); | |
217 | return; | |
218 | ||
219 | unhash_it: | |
220 | __d_drop(dentry); | |
d52b9086 | 221 | kill_it: |
4a0962ab | 222 | dentry_lru_remove(dentry); |
d52b9086 MS |
223 | dentry = d_kill(dentry); |
224 | if (dentry) | |
225 | goto repeat; | |
1da177e4 LT |
226 | } |
227 | ||
228 | /** | |
229 | * d_invalidate - invalidate a dentry | |
230 | * @dentry: dentry to invalidate | |
231 | * | |
232 | * Try to invalidate the dentry if it turns out to be | |
233 | * possible. If there are other dentries that can be | |
234 | * reached through this one we can't delete it and we | |
235 | * return -EBUSY. On success we return 0. | |
236 | * | |
237 | * no dcache lock. | |
238 | */ | |
239 | ||
240 | int d_invalidate(struct dentry * dentry) | |
241 | { | |
242 | /* | |
243 | * If it's already been dropped, return OK. | |
244 | */ | |
245 | spin_lock(&dcache_lock); | |
246 | if (d_unhashed(dentry)) { | |
247 | spin_unlock(&dcache_lock); | |
248 | return 0; | |
249 | } | |
250 | /* | |
251 | * Check whether to do a partial shrink_dcache | |
252 | * to get rid of unused child entries. | |
253 | */ | |
254 | if (!list_empty(&dentry->d_subdirs)) { | |
255 | spin_unlock(&dcache_lock); | |
256 | shrink_dcache_parent(dentry); | |
257 | spin_lock(&dcache_lock); | |
258 | } | |
259 | ||
260 | /* | |
261 | * Somebody else still using it? | |
262 | * | |
263 | * If it's a directory, we can't drop it | |
264 | * for fear of somebody re-populating it | |
265 | * with children (even though dropping it | |
266 | * would make it unreachable from the root, | |
267 | * we might still populate it if it was a | |
268 | * working directory or similar). | |
269 | */ | |
270 | spin_lock(&dentry->d_lock); | |
271 | if (atomic_read(&dentry->d_count) > 1) { | |
272 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { | |
273 | spin_unlock(&dentry->d_lock); | |
274 | spin_unlock(&dcache_lock); | |
275 | return -EBUSY; | |
276 | } | |
277 | } | |
278 | ||
279 | __d_drop(dentry); | |
280 | spin_unlock(&dentry->d_lock); | |
281 | spin_unlock(&dcache_lock); | |
282 | return 0; | |
283 | } | |
284 | ||
285 | /* This should be called _only_ with dcache_lock held */ | |
286 | ||
287 | static inline struct dentry * __dget_locked(struct dentry *dentry) | |
288 | { | |
289 | atomic_inc(&dentry->d_count); | |
4a0962ab | 290 | dentry_lru_remove(dentry); |
1da177e4 LT |
291 | return dentry; |
292 | } | |
293 | ||
294 | struct dentry * dget_locked(struct dentry *dentry) | |
295 | { | |
296 | return __dget_locked(dentry); | |
297 | } | |
298 | ||
299 | /** | |
300 | * d_find_alias - grab a hashed alias of inode | |
301 | * @inode: inode in question | |
302 | * @want_discon: flag, used by d_splice_alias, to request | |
303 | * that only a DISCONNECTED alias be returned. | |
304 | * | |
305 | * If inode has a hashed alias, or is a directory and has any alias, | |
306 | * acquire the reference to alias and return it. Otherwise return NULL. | |
307 | * Notice that if inode is a directory there can be only one alias and | |
308 | * it can be unhashed only if it has no children, or if it is the root | |
309 | * of a filesystem. | |
310 | * | |
21c0d8fd | 311 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
1da177e4 | 312 | * any other hashed alias over that one unless @want_discon is set, |
21c0d8fd | 313 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
1da177e4 LT |
314 | */ |
315 | ||
316 | static struct dentry * __d_find_alias(struct inode *inode, int want_discon) | |
317 | { | |
318 | struct list_head *head, *next, *tmp; | |
319 | struct dentry *alias, *discon_alias=NULL; | |
320 | ||
321 | head = &inode->i_dentry; | |
322 | next = inode->i_dentry.next; | |
323 | while (next != head) { | |
324 | tmp = next; | |
325 | next = tmp->next; | |
326 | prefetch(next); | |
327 | alias = list_entry(tmp, struct dentry, d_alias); | |
328 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
21c0d8fd N |
329 | if (IS_ROOT(alias) && |
330 | (alias->d_flags & DCACHE_DISCONNECTED)) | |
1da177e4 LT |
331 | discon_alias = alias; |
332 | else if (!want_discon) { | |
333 | __dget_locked(alias); | |
334 | return alias; | |
335 | } | |
336 | } | |
337 | } | |
338 | if (discon_alias) | |
339 | __dget_locked(discon_alias); | |
340 | return discon_alias; | |
341 | } | |
342 | ||
343 | struct dentry * d_find_alias(struct inode *inode) | |
344 | { | |
214fda1f DH |
345 | struct dentry *de = NULL; |
346 | ||
347 | if (!list_empty(&inode->i_dentry)) { | |
348 | spin_lock(&dcache_lock); | |
349 | de = __d_find_alias(inode, 0); | |
350 | spin_unlock(&dcache_lock); | |
351 | } | |
1da177e4 LT |
352 | return de; |
353 | } | |
354 | ||
355 | /* | |
356 | * Try to kill dentries associated with this inode. | |
357 | * WARNING: you must own a reference to inode. | |
358 | */ | |
359 | void d_prune_aliases(struct inode *inode) | |
360 | { | |
0cdca3f9 | 361 | struct dentry *dentry; |
1da177e4 LT |
362 | restart: |
363 | spin_lock(&dcache_lock); | |
0cdca3f9 | 364 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 LT |
365 | spin_lock(&dentry->d_lock); |
366 | if (!atomic_read(&dentry->d_count)) { | |
367 | __dget_locked(dentry); | |
368 | __d_drop(dentry); | |
369 | spin_unlock(&dentry->d_lock); | |
370 | spin_unlock(&dcache_lock); | |
371 | dput(dentry); | |
372 | goto restart; | |
373 | } | |
374 | spin_unlock(&dentry->d_lock); | |
375 | } | |
376 | spin_unlock(&dcache_lock); | |
377 | } | |
378 | ||
379 | /* | |
d702ccb3 AM |
380 | * Throw away a dentry - free the inode, dput the parent. This requires that |
381 | * the LRU list has already been removed. | |
382 | * | |
85864e10 MS |
383 | * Try to prune ancestors as well. This is necessary to prevent |
384 | * quadratic behavior of shrink_dcache_parent(), but is also expected | |
385 | * to be beneficial in reducing dentry cache fragmentation. | |
d52b9086 | 386 | * |
1da177e4 | 387 | * Called with dcache_lock, drops it and then regains. |
d702ccb3 | 388 | * Called with dentry->d_lock held, drops it. |
1da177e4 | 389 | */ |
85864e10 | 390 | static void prune_one_dentry(struct dentry * dentry) |
1da177e4 | 391 | { |
1da177e4 | 392 | __d_drop(dentry); |
d52b9086 | 393 | dentry = d_kill(dentry); |
d52b9086 MS |
394 | |
395 | /* | |
396 | * Prune ancestors. Locking is simpler than in dput(), | |
397 | * because dcache_lock needs to be taken anyway. | |
398 | */ | |
1da177e4 | 399 | spin_lock(&dcache_lock); |
d52b9086 MS |
400 | while (dentry) { |
401 | if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) | |
402 | return; | |
403 | ||
404 | if (dentry->d_op && dentry->d_op->d_delete) | |
405 | dentry->d_op->d_delete(dentry); | |
4a0962ab | 406 | dentry_lru_remove(dentry); |
d52b9086 MS |
407 | __d_drop(dentry); |
408 | dentry = d_kill(dentry); | |
409 | spin_lock(&dcache_lock); | |
410 | } | |
1da177e4 LT |
411 | } |
412 | ||
413 | /** | |
414 | * prune_dcache - shrink the dcache | |
415 | * @count: number of entries to try and free | |
0feae5c4 N |
416 | * @sb: if given, ignore dentries for other superblocks |
417 | * which are being unmounted. | |
1da177e4 LT |
418 | * |
419 | * Shrink the dcache. This is done when we need | |
420 | * more memory, or simply when we need to unmount | |
421 | * something (at which point we need to unuse | |
422 | * all dentries). | |
423 | * | |
424 | * This function may fail to free any resources if | |
425 | * all the dentries are in use. | |
426 | */ | |
427 | ||
85864e10 | 428 | static void prune_dcache(int count, struct super_block *sb) |
1da177e4 LT |
429 | { |
430 | spin_lock(&dcache_lock); | |
431 | for (; count ; count--) { | |
432 | struct dentry *dentry; | |
433 | struct list_head *tmp; | |
0feae5c4 | 434 | struct rw_semaphore *s_umount; |
1da177e4 LT |
435 | |
436 | cond_resched_lock(&dcache_lock); | |
437 | ||
438 | tmp = dentry_unused.prev; | |
f58a1ebb | 439 | if (sb) { |
0feae5c4 N |
440 | /* Try to find a dentry for this sb, but don't try |
441 | * too hard, if they aren't near the tail they will | |
442 | * be moved down again soon | |
443 | */ | |
444 | int skip = count; | |
445 | while (skip && tmp != &dentry_unused && | |
446 | list_entry(tmp, struct dentry, d_lru)->d_sb != sb) { | |
447 | skip--; | |
448 | tmp = tmp->prev; | |
449 | } | |
450 | } | |
1da177e4 LT |
451 | if (tmp == &dentry_unused) |
452 | break; | |
453 | list_del_init(tmp); | |
454 | prefetch(dentry_unused.prev); | |
455 | dentry_stat.nr_unused--; | |
456 | dentry = list_entry(tmp, struct dentry, d_lru); | |
457 | ||
458 | spin_lock(&dentry->d_lock); | |
459 | /* | |
460 | * We found an inuse dentry which was not removed from | |
461 | * dentry_unused because of laziness during lookup. Do not free | |
462 | * it - just keep it off the dentry_unused list. | |
463 | */ | |
464 | if (atomic_read(&dentry->d_count)) { | |
465 | spin_unlock(&dentry->d_lock); | |
466 | continue; | |
467 | } | |
468 | /* If the dentry was recently referenced, don't free it. */ | |
469 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
470 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
471 | list_add(&dentry->d_lru, &dentry_unused); | |
472 | dentry_stat.nr_unused++; | |
473 | spin_unlock(&dentry->d_lock); | |
474 | continue; | |
475 | } | |
0feae5c4 N |
476 | /* |
477 | * If the dentry is not DCACHED_REFERENCED, it is time | |
478 | * to remove it from the dcache, provided the super block is | |
479 | * NULL (which means we are trying to reclaim memory) | |
480 | * or this dentry belongs to the same super block that | |
481 | * we want to shrink. | |
482 | */ | |
483 | /* | |
484 | * If this dentry is for "my" filesystem, then I can prune it | |
485 | * without taking the s_umount lock (I already hold it). | |
486 | */ | |
487 | if (sb && dentry->d_sb == sb) { | |
85864e10 | 488 | prune_one_dentry(dentry); |
0feae5c4 N |
489 | continue; |
490 | } | |
491 | /* | |
492 | * ...otherwise we need to be sure this filesystem isn't being | |
493 | * unmounted, otherwise we could race with | |
494 | * generic_shutdown_super(), and end up holding a reference to | |
495 | * an inode while the filesystem is unmounted. | |
496 | * So we try to get s_umount, and make sure s_root isn't NULL. | |
497 | * (Take a local copy of s_umount to avoid a use-after-free of | |
498 | * `dentry'). | |
499 | */ | |
500 | s_umount = &dentry->d_sb->s_umount; | |
501 | if (down_read_trylock(s_umount)) { | |
502 | if (dentry->d_sb->s_root != NULL) { | |
85864e10 | 503 | prune_one_dentry(dentry); |
0feae5c4 N |
504 | up_read(s_umount); |
505 | continue; | |
506 | } | |
507 | up_read(s_umount); | |
508 | } | |
509 | spin_unlock(&dentry->d_lock); | |
6eac3f93 VA |
510 | /* |
511 | * Insert dentry at the head of the list as inserting at the | |
512 | * tail leads to a cycle. | |
0feae5c4 | 513 | */ |
6eac3f93 VA |
514 | list_add(&dentry->d_lru, &dentry_unused); |
515 | dentry_stat.nr_unused++; | |
1da177e4 LT |
516 | } |
517 | spin_unlock(&dcache_lock); | |
518 | } | |
519 | ||
520 | /* | |
521 | * Shrink the dcache for the specified super block. | |
522 | * This allows us to unmount a device without disturbing | |
523 | * the dcache for the other devices. | |
524 | * | |
525 | * This implementation makes just two traversals of the | |
526 | * unused list. On the first pass we move the selected | |
527 | * dentries to the most recent end, and on the second | |
528 | * pass we free them. The second pass must restart after | |
529 | * each dput(), but since the target dentries are all at | |
530 | * the end, it's really just a single traversal. | |
531 | */ | |
532 | ||
533 | /** | |
534 | * shrink_dcache_sb - shrink dcache for a superblock | |
535 | * @sb: superblock | |
536 | * | |
537 | * Shrink the dcache for the specified super block. This | |
538 | * is used to free the dcache before unmounting a file | |
539 | * system | |
540 | */ | |
541 | ||
542 | void shrink_dcache_sb(struct super_block * sb) | |
543 | { | |
544 | struct list_head *tmp, *next; | |
545 | struct dentry *dentry; | |
546 | ||
547 | /* | |
548 | * Pass one ... move the dentries for the specified | |
549 | * superblock to the most recent end of the unused list. | |
550 | */ | |
551 | spin_lock(&dcache_lock); | |
37c42524 | 552 | list_for_each_prev_safe(tmp, next, &dentry_unused) { |
1da177e4 LT |
553 | dentry = list_entry(tmp, struct dentry, d_lru); |
554 | if (dentry->d_sb != sb) | |
555 | continue; | |
37c42524 | 556 | list_move_tail(tmp, &dentry_unused); |
1da177e4 LT |
557 | } |
558 | ||
559 | /* | |
560 | * Pass two ... free the dentries for this superblock. | |
561 | */ | |
562 | repeat: | |
37c42524 | 563 | list_for_each_prev_safe(tmp, next, &dentry_unused) { |
1da177e4 LT |
564 | dentry = list_entry(tmp, struct dentry, d_lru); |
565 | if (dentry->d_sb != sb) | |
566 | continue; | |
567 | dentry_stat.nr_unused--; | |
568 | list_del_init(tmp); | |
569 | spin_lock(&dentry->d_lock); | |
570 | if (atomic_read(&dentry->d_count)) { | |
571 | spin_unlock(&dentry->d_lock); | |
572 | continue; | |
573 | } | |
85864e10 | 574 | prune_one_dentry(dentry); |
2ab13460 | 575 | cond_resched_lock(&dcache_lock); |
1da177e4 LT |
576 | goto repeat; |
577 | } | |
578 | spin_unlock(&dcache_lock); | |
579 | } | |
580 | ||
c636ebdb DH |
581 | /* |
582 | * destroy a single subtree of dentries for unmount | |
583 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
584 | * locking | |
585 | */ | |
586 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
587 | { | |
588 | struct dentry *parent; | |
f8713576 | 589 | unsigned detached = 0; |
c636ebdb DH |
590 | |
591 | BUG_ON(!IS_ROOT(dentry)); | |
592 | ||
593 | /* detach this root from the system */ | |
594 | spin_lock(&dcache_lock); | |
4a0962ab | 595 | dentry_lru_remove(dentry); |
c636ebdb DH |
596 | __d_drop(dentry); |
597 | spin_unlock(&dcache_lock); | |
598 | ||
599 | for (;;) { | |
600 | /* descend to the first leaf in the current subtree */ | |
601 | while (!list_empty(&dentry->d_subdirs)) { | |
602 | struct dentry *loop; | |
603 | ||
604 | /* this is a branch with children - detach all of them | |
605 | * from the system in one go */ | |
606 | spin_lock(&dcache_lock); | |
607 | list_for_each_entry(loop, &dentry->d_subdirs, | |
608 | d_u.d_child) { | |
4a0962ab | 609 | dentry_lru_remove(loop); |
c636ebdb DH |
610 | __d_drop(loop); |
611 | cond_resched_lock(&dcache_lock); | |
612 | } | |
613 | spin_unlock(&dcache_lock); | |
614 | ||
615 | /* move to the first child */ | |
616 | dentry = list_entry(dentry->d_subdirs.next, | |
617 | struct dentry, d_u.d_child); | |
618 | } | |
619 | ||
620 | /* consume the dentries from this leaf up through its parents | |
621 | * until we find one with children or run out altogether */ | |
622 | do { | |
623 | struct inode *inode; | |
624 | ||
625 | if (atomic_read(&dentry->d_count) != 0) { | |
626 | printk(KERN_ERR | |
627 | "BUG: Dentry %p{i=%lx,n=%s}" | |
628 | " still in use (%d)" | |
629 | " [unmount of %s %s]\n", | |
630 | dentry, | |
631 | dentry->d_inode ? | |
632 | dentry->d_inode->i_ino : 0UL, | |
633 | dentry->d_name.name, | |
634 | atomic_read(&dentry->d_count), | |
635 | dentry->d_sb->s_type->name, | |
636 | dentry->d_sb->s_id); | |
637 | BUG(); | |
638 | } | |
639 | ||
640 | parent = dentry->d_parent; | |
641 | if (parent == dentry) | |
642 | parent = NULL; | |
643 | else | |
644 | atomic_dec(&parent->d_count); | |
645 | ||
646 | list_del(&dentry->d_u.d_child); | |
f8713576 | 647 | detached++; |
c636ebdb DH |
648 | |
649 | inode = dentry->d_inode; | |
650 | if (inode) { | |
651 | dentry->d_inode = NULL; | |
652 | list_del_init(&dentry->d_alias); | |
653 | if (dentry->d_op && dentry->d_op->d_iput) | |
654 | dentry->d_op->d_iput(dentry, inode); | |
655 | else | |
656 | iput(inode); | |
657 | } | |
658 | ||
659 | d_free(dentry); | |
660 | ||
661 | /* finished when we fall off the top of the tree, | |
662 | * otherwise we ascend to the parent and move to the | |
663 | * next sibling if there is one */ | |
664 | if (!parent) | |
f8713576 | 665 | goto out; |
c636ebdb DH |
666 | |
667 | dentry = parent; | |
668 | ||
669 | } while (list_empty(&dentry->d_subdirs)); | |
670 | ||
671 | dentry = list_entry(dentry->d_subdirs.next, | |
672 | struct dentry, d_u.d_child); | |
673 | } | |
f8713576 DH |
674 | out: |
675 | /* several dentries were freed, need to correct nr_dentry */ | |
676 | spin_lock(&dcache_lock); | |
677 | dentry_stat.nr_dentry -= detached; | |
678 | spin_unlock(&dcache_lock); | |
c636ebdb DH |
679 | } |
680 | ||
681 | /* | |
682 | * destroy the dentries attached to a superblock on unmounting | |
683 | * - we don't need to use dentry->d_lock, and only need dcache_lock when | |
684 | * removing the dentry from the system lists and hashes because: | |
685 | * - the superblock is detached from all mountings and open files, so the | |
686 | * dentry trees will not be rearranged by the VFS | |
687 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
688 | * any dentries belonging to this superblock that it comes across | |
689 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
690 | * in this superblock | |
691 | */ | |
692 | void shrink_dcache_for_umount(struct super_block *sb) | |
693 | { | |
694 | struct dentry *dentry; | |
695 | ||
696 | if (down_read_trylock(&sb->s_umount)) | |
697 | BUG(); | |
698 | ||
699 | dentry = sb->s_root; | |
700 | sb->s_root = NULL; | |
701 | atomic_dec(&dentry->d_count); | |
702 | shrink_dcache_for_umount_subtree(dentry); | |
703 | ||
704 | while (!hlist_empty(&sb->s_anon)) { | |
705 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); | |
706 | shrink_dcache_for_umount_subtree(dentry); | |
707 | } | |
708 | } | |
709 | ||
1da177e4 LT |
710 | /* |
711 | * Search for at least 1 mount point in the dentry's subdirs. | |
712 | * We descend to the next level whenever the d_subdirs | |
713 | * list is non-empty and continue searching. | |
714 | */ | |
715 | ||
716 | /** | |
717 | * have_submounts - check for mounts over a dentry | |
718 | * @parent: dentry to check. | |
719 | * | |
720 | * Return true if the parent or its subdirectories contain | |
721 | * a mount point | |
722 | */ | |
723 | ||
724 | int have_submounts(struct dentry *parent) | |
725 | { | |
726 | struct dentry *this_parent = parent; | |
727 | struct list_head *next; | |
728 | ||
729 | spin_lock(&dcache_lock); | |
730 | if (d_mountpoint(parent)) | |
731 | goto positive; | |
732 | repeat: | |
733 | next = this_parent->d_subdirs.next; | |
734 | resume: | |
735 | while (next != &this_parent->d_subdirs) { | |
736 | struct list_head *tmp = next; | |
5160ee6f | 737 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
738 | next = tmp->next; |
739 | /* Have we found a mount point ? */ | |
740 | if (d_mountpoint(dentry)) | |
741 | goto positive; | |
742 | if (!list_empty(&dentry->d_subdirs)) { | |
743 | this_parent = dentry; | |
744 | goto repeat; | |
745 | } | |
746 | } | |
747 | /* | |
748 | * All done at this level ... ascend and resume the search. | |
749 | */ | |
750 | if (this_parent != parent) { | |
5160ee6f | 751 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
752 | this_parent = this_parent->d_parent; |
753 | goto resume; | |
754 | } | |
755 | spin_unlock(&dcache_lock); | |
756 | return 0; /* No mount points found in tree */ | |
757 | positive: | |
758 | spin_unlock(&dcache_lock); | |
759 | return 1; | |
760 | } | |
761 | ||
762 | /* | |
763 | * Search the dentry child list for the specified parent, | |
764 | * and move any unused dentries to the end of the unused | |
765 | * list for prune_dcache(). We descend to the next level | |
766 | * whenever the d_subdirs list is non-empty and continue | |
767 | * searching. | |
768 | * | |
769 | * It returns zero iff there are no unused children, | |
770 | * otherwise it returns the number of children moved to | |
771 | * the end of the unused list. This may not be the total | |
772 | * number of unused children, because select_parent can | |
773 | * drop the lock and return early due to latency | |
774 | * constraints. | |
775 | */ | |
776 | static int select_parent(struct dentry * parent) | |
777 | { | |
778 | struct dentry *this_parent = parent; | |
779 | struct list_head *next; | |
780 | int found = 0; | |
781 | ||
782 | spin_lock(&dcache_lock); | |
783 | repeat: | |
784 | next = this_parent->d_subdirs.next; | |
785 | resume: | |
786 | while (next != &this_parent->d_subdirs) { | |
787 | struct list_head *tmp = next; | |
5160ee6f | 788 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
789 | next = tmp->next; |
790 | ||
4a0962ab | 791 | dentry_lru_remove(dentry); |
1da177e4 LT |
792 | /* |
793 | * move only zero ref count dentries to the end | |
794 | * of the unused list for prune_dcache | |
795 | */ | |
796 | if (!atomic_read(&dentry->d_count)) { | |
8e13059a | 797 | list_add_tail(&dentry->d_lru, &dentry_unused); |
1da177e4 LT |
798 | dentry_stat.nr_unused++; |
799 | found++; | |
800 | } | |
801 | ||
802 | /* | |
803 | * We can return to the caller if we have found some (this | |
804 | * ensures forward progress). We'll be coming back to find | |
805 | * the rest. | |
806 | */ | |
807 | if (found && need_resched()) | |
808 | goto out; | |
809 | ||
810 | /* | |
811 | * Descend a level if the d_subdirs list is non-empty. | |
812 | */ | |
813 | if (!list_empty(&dentry->d_subdirs)) { | |
814 | this_parent = dentry; | |
1da177e4 LT |
815 | goto repeat; |
816 | } | |
817 | } | |
818 | /* | |
819 | * All done at this level ... ascend and resume the search. | |
820 | */ | |
821 | if (this_parent != parent) { | |
5160ee6f | 822 | next = this_parent->d_u.d_child.next; |
1da177e4 | 823 | this_parent = this_parent->d_parent; |
1da177e4 LT |
824 | goto resume; |
825 | } | |
826 | out: | |
827 | spin_unlock(&dcache_lock); | |
828 | return found; | |
829 | } | |
830 | ||
831 | /** | |
832 | * shrink_dcache_parent - prune dcache | |
833 | * @parent: parent of entries to prune | |
834 | * | |
835 | * Prune the dcache to remove unused children of the parent dentry. | |
836 | */ | |
837 | ||
838 | void shrink_dcache_parent(struct dentry * parent) | |
839 | { | |
840 | int found; | |
841 | ||
842 | while ((found = select_parent(parent)) != 0) | |
85864e10 | 843 | prune_dcache(found, parent->d_sb); |
1da177e4 LT |
844 | } |
845 | ||
1da177e4 LT |
846 | /* |
847 | * Scan `nr' dentries and return the number which remain. | |
848 | * | |
849 | * We need to avoid reentering the filesystem if the caller is performing a | |
850 | * GFP_NOFS allocation attempt. One example deadlock is: | |
851 | * | |
852 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> | |
853 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> | |
854 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. | |
855 | * | |
856 | * In this case we return -1 to tell the caller that we baled. | |
857 | */ | |
27496a8c | 858 | static int shrink_dcache_memory(int nr, gfp_t gfp_mask) |
1da177e4 LT |
859 | { |
860 | if (nr) { | |
861 | if (!(gfp_mask & __GFP_FS)) | |
862 | return -1; | |
85864e10 | 863 | prune_dcache(nr, NULL); |
1da177e4 LT |
864 | } |
865 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; | |
866 | } | |
867 | ||
8e1f936b RR |
868 | static struct shrinker dcache_shrinker = { |
869 | .shrink = shrink_dcache_memory, | |
870 | .seeks = DEFAULT_SEEKS, | |
871 | }; | |
872 | ||
1da177e4 LT |
873 | /** |
874 | * d_alloc - allocate a dcache entry | |
875 | * @parent: parent of entry to allocate | |
876 | * @name: qstr of the name | |
877 | * | |
878 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
879 | * available. On a success the dentry is returned. The name passed in is | |
880 | * copied and the copy passed in may be reused after this call. | |
881 | */ | |
882 | ||
883 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
884 | { | |
885 | struct dentry *dentry; | |
886 | char *dname; | |
887 | ||
e12ba74d | 888 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
889 | if (!dentry) |
890 | return NULL; | |
891 | ||
892 | if (name->len > DNAME_INLINE_LEN-1) { | |
893 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
894 | if (!dname) { | |
895 | kmem_cache_free(dentry_cache, dentry); | |
896 | return NULL; | |
897 | } | |
898 | } else { | |
899 | dname = dentry->d_iname; | |
900 | } | |
901 | dentry->d_name.name = dname; | |
902 | ||
903 | dentry->d_name.len = name->len; | |
904 | dentry->d_name.hash = name->hash; | |
905 | memcpy(dname, name->name, name->len); | |
906 | dname[name->len] = 0; | |
907 | ||
908 | atomic_set(&dentry->d_count, 1); | |
909 | dentry->d_flags = DCACHE_UNHASHED; | |
910 | spin_lock_init(&dentry->d_lock); | |
911 | dentry->d_inode = NULL; | |
912 | dentry->d_parent = NULL; | |
913 | dentry->d_sb = NULL; | |
914 | dentry->d_op = NULL; | |
915 | dentry->d_fsdata = NULL; | |
916 | dentry->d_mounted = 0; | |
47ba87e0 | 917 | #ifdef CONFIG_PROFILING |
1da177e4 | 918 | dentry->d_cookie = NULL; |
47ba87e0 | 919 | #endif |
1da177e4 LT |
920 | INIT_HLIST_NODE(&dentry->d_hash); |
921 | INIT_LIST_HEAD(&dentry->d_lru); | |
922 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
923 | INIT_LIST_HEAD(&dentry->d_alias); | |
924 | ||
925 | if (parent) { | |
926 | dentry->d_parent = dget(parent); | |
927 | dentry->d_sb = parent->d_sb; | |
928 | } else { | |
5160ee6f | 929 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1da177e4 LT |
930 | } |
931 | ||
932 | spin_lock(&dcache_lock); | |
933 | if (parent) | |
5160ee6f | 934 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1da177e4 LT |
935 | dentry_stat.nr_dentry++; |
936 | spin_unlock(&dcache_lock); | |
937 | ||
938 | return dentry; | |
939 | } | |
940 | ||
941 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) | |
942 | { | |
943 | struct qstr q; | |
944 | ||
945 | q.name = name; | |
946 | q.len = strlen(name); | |
947 | q.hash = full_name_hash(q.name, q.len); | |
948 | return d_alloc(parent, &q); | |
949 | } | |
950 | ||
951 | /** | |
952 | * d_instantiate - fill in inode information for a dentry | |
953 | * @entry: dentry to complete | |
954 | * @inode: inode to attach to this dentry | |
955 | * | |
956 | * Fill in inode information in the entry. | |
957 | * | |
958 | * This turns negative dentries into productive full members | |
959 | * of society. | |
960 | * | |
961 | * NOTE! This assumes that the inode count has been incremented | |
962 | * (or otherwise set) by the caller to indicate that it is now | |
963 | * in use by the dcache. | |
964 | */ | |
965 | ||
966 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
967 | { | |
28133c7b | 968 | BUG_ON(!list_empty(&entry->d_alias)); |
1da177e4 LT |
969 | spin_lock(&dcache_lock); |
970 | if (inode) | |
971 | list_add(&entry->d_alias, &inode->i_dentry); | |
972 | entry->d_inode = inode; | |
c32ccd87 | 973 | fsnotify_d_instantiate(entry, inode); |
1da177e4 LT |
974 | spin_unlock(&dcache_lock); |
975 | security_d_instantiate(entry, inode); | |
976 | } | |
977 | ||
978 | /** | |
979 | * d_instantiate_unique - instantiate a non-aliased dentry | |
980 | * @entry: dentry to instantiate | |
981 | * @inode: inode to attach to this dentry | |
982 | * | |
983 | * Fill in inode information in the entry. On success, it returns NULL. | |
984 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 985 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
986 | * |
987 | * Note that in order to avoid conflicts with rename() etc, the caller | |
988 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
989 | * |
990 | * This also assumes that the inode count has been incremented | |
991 | * (or otherwise set) by the caller to indicate that it is now | |
992 | * in use by the dcache. | |
1da177e4 | 993 | */ |
770bfad8 DH |
994 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
995 | struct inode *inode) | |
1da177e4 LT |
996 | { |
997 | struct dentry *alias; | |
998 | int len = entry->d_name.len; | |
999 | const char *name = entry->d_name.name; | |
1000 | unsigned int hash = entry->d_name.hash; | |
1001 | ||
770bfad8 DH |
1002 | if (!inode) { |
1003 | entry->d_inode = NULL; | |
1004 | return NULL; | |
1005 | } | |
1006 | ||
1da177e4 LT |
1007 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1008 | struct qstr *qstr = &alias->d_name; | |
1009 | ||
1010 | if (qstr->hash != hash) | |
1011 | continue; | |
1012 | if (alias->d_parent != entry->d_parent) | |
1013 | continue; | |
1014 | if (qstr->len != len) | |
1015 | continue; | |
1016 | if (memcmp(qstr->name, name, len)) | |
1017 | continue; | |
1018 | dget_locked(alias); | |
1da177e4 LT |
1019 | return alias; |
1020 | } | |
770bfad8 | 1021 | |
1da177e4 | 1022 | list_add(&entry->d_alias, &inode->i_dentry); |
1da177e4 | 1023 | entry->d_inode = inode; |
c32ccd87 | 1024 | fsnotify_d_instantiate(entry, inode); |
1da177e4 LT |
1025 | return NULL; |
1026 | } | |
770bfad8 DH |
1027 | |
1028 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1029 | { | |
1030 | struct dentry *result; | |
1031 | ||
1032 | BUG_ON(!list_empty(&entry->d_alias)); | |
1033 | ||
1034 | spin_lock(&dcache_lock); | |
1035 | result = __d_instantiate_unique(entry, inode); | |
1036 | spin_unlock(&dcache_lock); | |
1037 | ||
1038 | if (!result) { | |
1039 | security_d_instantiate(entry, inode); | |
1040 | return NULL; | |
1041 | } | |
1042 | ||
1043 | BUG_ON(!d_unhashed(result)); | |
1044 | iput(inode); | |
1045 | return result; | |
1046 | } | |
1047 | ||
1da177e4 LT |
1048 | EXPORT_SYMBOL(d_instantiate_unique); |
1049 | ||
1050 | /** | |
1051 | * d_alloc_root - allocate root dentry | |
1052 | * @root_inode: inode to allocate the root for | |
1053 | * | |
1054 | * Allocate a root ("/") dentry for the inode given. The inode is | |
1055 | * instantiated and returned. %NULL is returned if there is insufficient | |
1056 | * memory or the inode passed is %NULL. | |
1057 | */ | |
1058 | ||
1059 | struct dentry * d_alloc_root(struct inode * root_inode) | |
1060 | { | |
1061 | struct dentry *res = NULL; | |
1062 | ||
1063 | if (root_inode) { | |
1064 | static const struct qstr name = { .name = "/", .len = 1 }; | |
1065 | ||
1066 | res = d_alloc(NULL, &name); | |
1067 | if (res) { | |
1068 | res->d_sb = root_inode->i_sb; | |
1069 | res->d_parent = res; | |
1070 | d_instantiate(res, root_inode); | |
1071 | } | |
1072 | } | |
1073 | return res; | |
1074 | } | |
1075 | ||
1076 | static inline struct hlist_head *d_hash(struct dentry *parent, | |
1077 | unsigned long hash) | |
1078 | { | |
1079 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; | |
1080 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); | |
1081 | return dentry_hashtable + (hash & D_HASHMASK); | |
1082 | } | |
1083 | ||
1084 | /** | |
1085 | * d_alloc_anon - allocate an anonymous dentry | |
1086 | * @inode: inode to allocate the dentry for | |
1087 | * | |
1088 | * This is similar to d_alloc_root. It is used by filesystems when | |
1089 | * creating a dentry for a given inode, often in the process of | |
1090 | * mapping a filehandle to a dentry. The returned dentry may be | |
1091 | * anonymous, or may have a full name (if the inode was already | |
1092 | * in the cache). The file system may need to make further | |
1093 | * efforts to connect this dentry into the dcache properly. | |
1094 | * | |
1095 | * When called on a directory inode, we must ensure that | |
1096 | * the inode only ever has one dentry. If a dentry is | |
1097 | * found, that is returned instead of allocating a new one. | |
1098 | * | |
1099 | * On successful return, the reference to the inode has been transferred | |
1100 | * to the dentry. If %NULL is returned (indicating kmalloc failure), | |
1101 | * the reference on the inode has not been released. | |
1102 | */ | |
1103 | ||
1104 | struct dentry * d_alloc_anon(struct inode *inode) | |
1105 | { | |
1106 | static const struct qstr anonstring = { .name = "" }; | |
1107 | struct dentry *tmp; | |
1108 | struct dentry *res; | |
1109 | ||
1110 | if ((res = d_find_alias(inode))) { | |
1111 | iput(inode); | |
1112 | return res; | |
1113 | } | |
1114 | ||
1115 | tmp = d_alloc(NULL, &anonstring); | |
1116 | if (!tmp) | |
1117 | return NULL; | |
1118 | ||
1119 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ | |
1120 | ||
1121 | spin_lock(&dcache_lock); | |
1122 | res = __d_find_alias(inode, 0); | |
1123 | if (!res) { | |
1124 | /* attach a disconnected dentry */ | |
1125 | res = tmp; | |
1126 | tmp = NULL; | |
1127 | spin_lock(&res->d_lock); | |
1128 | res->d_sb = inode->i_sb; | |
1129 | res->d_parent = res; | |
1130 | res->d_inode = inode; | |
1131 | res->d_flags |= DCACHE_DISCONNECTED; | |
1132 | res->d_flags &= ~DCACHE_UNHASHED; | |
1133 | list_add(&res->d_alias, &inode->i_dentry); | |
1134 | hlist_add_head(&res->d_hash, &inode->i_sb->s_anon); | |
1135 | spin_unlock(&res->d_lock); | |
1136 | ||
1137 | inode = NULL; /* don't drop reference */ | |
1138 | } | |
1139 | spin_unlock(&dcache_lock); | |
1140 | ||
1141 | if (inode) | |
1142 | iput(inode); | |
1143 | if (tmp) | |
1144 | dput(tmp); | |
1145 | return res; | |
1146 | } | |
1147 | ||
1148 | ||
1149 | /** | |
1150 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1151 | * @inode: the inode which may have a disconnected dentry | |
1152 | * @dentry: a negative dentry which we want to point to the inode. | |
1153 | * | |
1154 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1155 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1156 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1157 | * | |
1158 | * This is needed in the lookup routine of any filesystem that is exportable | |
1159 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1160 | * | |
1161 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1162 | * is returned. This matches the expected return value of ->lookup. | |
1163 | * | |
1164 | */ | |
1165 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1166 | { | |
1167 | struct dentry *new = NULL; | |
1168 | ||
21c0d8fd | 1169 | if (inode && S_ISDIR(inode->i_mode)) { |
1da177e4 LT |
1170 | spin_lock(&dcache_lock); |
1171 | new = __d_find_alias(inode, 1); | |
1172 | if (new) { | |
1173 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); | |
c32ccd87 | 1174 | fsnotify_d_instantiate(new, inode); |
1da177e4 LT |
1175 | spin_unlock(&dcache_lock); |
1176 | security_d_instantiate(new, inode); | |
1177 | d_rehash(dentry); | |
1178 | d_move(new, dentry); | |
1179 | iput(inode); | |
1180 | } else { | |
1181 | /* d_instantiate takes dcache_lock, so we do it by hand */ | |
1182 | list_add(&dentry->d_alias, &inode->i_dentry); | |
1183 | dentry->d_inode = inode; | |
c32ccd87 | 1184 | fsnotify_d_instantiate(dentry, inode); |
1da177e4 LT |
1185 | spin_unlock(&dcache_lock); |
1186 | security_d_instantiate(dentry, inode); | |
1187 | d_rehash(dentry); | |
1188 | } | |
1189 | } else | |
1190 | d_add(dentry, inode); | |
1191 | return new; | |
1192 | } | |
1193 | ||
1194 | ||
1195 | /** | |
1196 | * d_lookup - search for a dentry | |
1197 | * @parent: parent dentry | |
1198 | * @name: qstr of name we wish to find | |
1199 | * | |
1200 | * Searches the children of the parent dentry for the name in question. If | |
1201 | * the dentry is found its reference count is incremented and the dentry | |
1202 | * is returned. The caller must use d_put to free the entry when it has | |
1203 | * finished using it. %NULL is returned on failure. | |
1204 | * | |
1205 | * __d_lookup is dcache_lock free. The hash list is protected using RCU. | |
1206 | * Memory barriers are used while updating and doing lockless traversal. | |
1207 | * To avoid races with d_move while rename is happening, d_lock is used. | |
1208 | * | |
1209 | * Overflows in memcmp(), while d_move, are avoided by keeping the length | |
1210 | * and name pointer in one structure pointed by d_qstr. | |
1211 | * | |
1212 | * rcu_read_lock() and rcu_read_unlock() are used to disable preemption while | |
1213 | * lookup is going on. | |
1214 | * | |
1215 | * dentry_unused list is not updated even if lookup finds the required dentry | |
1216 | * in there. It is updated in places such as prune_dcache, shrink_dcache_sb, | |
1217 | * select_parent and __dget_locked. This laziness saves lookup from dcache_lock | |
1218 | * acquisition. | |
1219 | * | |
1220 | * d_lookup() is protected against the concurrent renames in some unrelated | |
1221 | * directory using the seqlockt_t rename_lock. | |
1222 | */ | |
1223 | ||
1224 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) | |
1225 | { | |
1226 | struct dentry * dentry = NULL; | |
1227 | unsigned long seq; | |
1228 | ||
1229 | do { | |
1230 | seq = read_seqbegin(&rename_lock); | |
1231 | dentry = __d_lookup(parent, name); | |
1232 | if (dentry) | |
1233 | break; | |
1234 | } while (read_seqretry(&rename_lock, seq)); | |
1235 | return dentry; | |
1236 | } | |
1237 | ||
1238 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) | |
1239 | { | |
1240 | unsigned int len = name->len; | |
1241 | unsigned int hash = name->hash; | |
1242 | const unsigned char *str = name->name; | |
1243 | struct hlist_head *head = d_hash(parent,hash); | |
1244 | struct dentry *found = NULL; | |
1245 | struct hlist_node *node; | |
665a7583 | 1246 | struct dentry *dentry; |
1da177e4 LT |
1247 | |
1248 | rcu_read_lock(); | |
1249 | ||
665a7583 | 1250 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
1da177e4 LT |
1251 | struct qstr *qstr; |
1252 | ||
1da177e4 LT |
1253 | if (dentry->d_name.hash != hash) |
1254 | continue; | |
1255 | if (dentry->d_parent != parent) | |
1256 | continue; | |
1257 | ||
1258 | spin_lock(&dentry->d_lock); | |
1259 | ||
1260 | /* | |
1261 | * Recheck the dentry after taking the lock - d_move may have | |
1262 | * changed things. Don't bother checking the hash because we're | |
1263 | * about to compare the whole name anyway. | |
1264 | */ | |
1265 | if (dentry->d_parent != parent) | |
1266 | goto next; | |
1267 | ||
1268 | /* | |
1269 | * It is safe to compare names since d_move() cannot | |
1270 | * change the qstr (protected by d_lock). | |
1271 | */ | |
1272 | qstr = &dentry->d_name; | |
1273 | if (parent->d_op && parent->d_op->d_compare) { | |
1274 | if (parent->d_op->d_compare(parent, qstr, name)) | |
1275 | goto next; | |
1276 | } else { | |
1277 | if (qstr->len != len) | |
1278 | goto next; | |
1279 | if (memcmp(qstr->name, str, len)) | |
1280 | goto next; | |
1281 | } | |
1282 | ||
1283 | if (!d_unhashed(dentry)) { | |
1284 | atomic_inc(&dentry->d_count); | |
1285 | found = dentry; | |
1286 | } | |
1287 | spin_unlock(&dentry->d_lock); | |
1288 | break; | |
1289 | next: | |
1290 | spin_unlock(&dentry->d_lock); | |
1291 | } | |
1292 | rcu_read_unlock(); | |
1293 | ||
1294 | return found; | |
1295 | } | |
1296 | ||
3e7e241f EB |
1297 | /** |
1298 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
1299 | * @dir: Directory to search in | |
1300 | * @name: qstr of name we wish to find | |
1301 | * | |
1302 | * On hash failure or on lookup failure NULL is returned. | |
1303 | */ | |
1304 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
1305 | { | |
1306 | struct dentry *dentry = NULL; | |
1307 | ||
1308 | /* | |
1309 | * Check for a fs-specific hash function. Note that we must | |
1310 | * calculate the standard hash first, as the d_op->d_hash() | |
1311 | * routine may choose to leave the hash value unchanged. | |
1312 | */ | |
1313 | name->hash = full_name_hash(name->name, name->len); | |
1314 | if (dir->d_op && dir->d_op->d_hash) { | |
1315 | if (dir->d_op->d_hash(dir, name) < 0) | |
1316 | goto out; | |
1317 | } | |
1318 | dentry = d_lookup(dir, name); | |
1319 | out: | |
1320 | return dentry; | |
1321 | } | |
1322 | ||
1da177e4 LT |
1323 | /** |
1324 | * d_validate - verify dentry provided from insecure source | |
1325 | * @dentry: The dentry alleged to be valid child of @dparent | |
1326 | * @dparent: The parent dentry (known to be valid) | |
1327 | * @hash: Hash of the dentry | |
1328 | * @len: Length of the name | |
1329 | * | |
1330 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
1331 | * This is used by ncpfs in its readdir implementation. | |
1332 | * Zero is returned in the dentry is invalid. | |
1333 | */ | |
1334 | ||
1335 | int d_validate(struct dentry *dentry, struct dentry *dparent) | |
1336 | { | |
1337 | struct hlist_head *base; | |
1338 | struct hlist_node *lhp; | |
1339 | ||
1340 | /* Check whether the ptr might be valid at all.. */ | |
1341 | if (!kmem_ptr_validate(dentry_cache, dentry)) | |
1342 | goto out; | |
1343 | ||
1344 | if (dentry->d_parent != dparent) | |
1345 | goto out; | |
1346 | ||
1347 | spin_lock(&dcache_lock); | |
1348 | base = d_hash(dparent, dentry->d_name.hash); | |
1349 | hlist_for_each(lhp,base) { | |
665a7583 | 1350 | /* hlist_for_each_entry_rcu() not required for d_hash list |
1da177e4 LT |
1351 | * as it is parsed under dcache_lock |
1352 | */ | |
1353 | if (dentry == hlist_entry(lhp, struct dentry, d_hash)) { | |
1354 | __dget_locked(dentry); | |
1355 | spin_unlock(&dcache_lock); | |
1356 | return 1; | |
1357 | } | |
1358 | } | |
1359 | spin_unlock(&dcache_lock); | |
1360 | out: | |
1361 | return 0; | |
1362 | } | |
1363 | ||
1364 | /* | |
1365 | * When a file is deleted, we have two options: | |
1366 | * - turn this dentry into a negative dentry | |
1367 | * - unhash this dentry and free it. | |
1368 | * | |
1369 | * Usually, we want to just turn this into | |
1370 | * a negative dentry, but if anybody else is | |
1371 | * currently using the dentry or the inode | |
1372 | * we can't do that and we fall back on removing | |
1373 | * it from the hash queues and waiting for | |
1374 | * it to be deleted later when it has no users | |
1375 | */ | |
1376 | ||
1377 | /** | |
1378 | * d_delete - delete a dentry | |
1379 | * @dentry: The dentry to delete | |
1380 | * | |
1381 | * Turn the dentry into a negative dentry if possible, otherwise | |
1382 | * remove it from the hash queues so it can be deleted later | |
1383 | */ | |
1384 | ||
1385 | void d_delete(struct dentry * dentry) | |
1386 | { | |
7a91bf7f | 1387 | int isdir = 0; |
1da177e4 LT |
1388 | /* |
1389 | * Are we the only user? | |
1390 | */ | |
1391 | spin_lock(&dcache_lock); | |
1392 | spin_lock(&dentry->d_lock); | |
7a91bf7f | 1393 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
1da177e4 LT |
1394 | if (atomic_read(&dentry->d_count) == 1) { |
1395 | dentry_iput(dentry); | |
7a91bf7f | 1396 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
1397 | return; |
1398 | } | |
1399 | ||
1400 | if (!d_unhashed(dentry)) | |
1401 | __d_drop(dentry); | |
1402 | ||
1403 | spin_unlock(&dentry->d_lock); | |
1404 | spin_unlock(&dcache_lock); | |
7a91bf7f JM |
1405 | |
1406 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 LT |
1407 | } |
1408 | ||
1409 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) | |
1410 | { | |
1411 | ||
1412 | entry->d_flags &= ~DCACHE_UNHASHED; | |
1413 | hlist_add_head_rcu(&entry->d_hash, list); | |
1414 | } | |
1415 | ||
770bfad8 DH |
1416 | static void _d_rehash(struct dentry * entry) |
1417 | { | |
1418 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
1419 | } | |
1420 | ||
1da177e4 LT |
1421 | /** |
1422 | * d_rehash - add an entry back to the hash | |
1423 | * @entry: dentry to add to the hash | |
1424 | * | |
1425 | * Adds a dentry to the hash according to its name. | |
1426 | */ | |
1427 | ||
1428 | void d_rehash(struct dentry * entry) | |
1429 | { | |
1da177e4 LT |
1430 | spin_lock(&dcache_lock); |
1431 | spin_lock(&entry->d_lock); | |
770bfad8 | 1432 | _d_rehash(entry); |
1da177e4 LT |
1433 | spin_unlock(&entry->d_lock); |
1434 | spin_unlock(&dcache_lock); | |
1435 | } | |
1436 | ||
1437 | #define do_switch(x,y) do { \ | |
1438 | __typeof__ (x) __tmp = x; \ | |
1439 | x = y; y = __tmp; } while (0) | |
1440 | ||
1441 | /* | |
1442 | * When switching names, the actual string doesn't strictly have to | |
1443 | * be preserved in the target - because we're dropping the target | |
1444 | * anyway. As such, we can just do a simple memcpy() to copy over | |
1445 | * the new name before we switch. | |
1446 | * | |
1447 | * Note that we have to be a lot more careful about getting the hash | |
1448 | * switched - we have to switch the hash value properly even if it | |
1449 | * then no longer matches the actual (corrupted) string of the target. | |
1450 | * The hash value has to match the hash queue that the dentry is on.. | |
1451 | */ | |
1452 | static void switch_names(struct dentry *dentry, struct dentry *target) | |
1453 | { | |
1454 | if (dname_external(target)) { | |
1455 | if (dname_external(dentry)) { | |
1456 | /* | |
1457 | * Both external: swap the pointers | |
1458 | */ | |
1459 | do_switch(target->d_name.name, dentry->d_name.name); | |
1460 | } else { | |
1461 | /* | |
1462 | * dentry:internal, target:external. Steal target's | |
1463 | * storage and make target internal. | |
1464 | */ | |
321bcf92 BF |
1465 | memcpy(target->d_iname, dentry->d_name.name, |
1466 | dentry->d_name.len + 1); | |
1da177e4 LT |
1467 | dentry->d_name.name = target->d_name.name; |
1468 | target->d_name.name = target->d_iname; | |
1469 | } | |
1470 | } else { | |
1471 | if (dname_external(dentry)) { | |
1472 | /* | |
1473 | * dentry:external, target:internal. Give dentry's | |
1474 | * storage to target and make dentry internal | |
1475 | */ | |
1476 | memcpy(dentry->d_iname, target->d_name.name, | |
1477 | target->d_name.len + 1); | |
1478 | target->d_name.name = dentry->d_name.name; | |
1479 | dentry->d_name.name = dentry->d_iname; | |
1480 | } else { | |
1481 | /* | |
1482 | * Both are internal. Just copy target to dentry | |
1483 | */ | |
1484 | memcpy(dentry->d_iname, target->d_name.name, | |
1485 | target->d_name.len + 1); | |
1486 | } | |
1487 | } | |
1488 | } | |
1489 | ||
1490 | /* | |
1491 | * We cannibalize "target" when moving dentry on top of it, | |
1492 | * because it's going to be thrown away anyway. We could be more | |
1493 | * polite about it, though. | |
1494 | * | |
1495 | * This forceful removal will result in ugly /proc output if | |
1496 | * somebody holds a file open that got deleted due to a rename. | |
1497 | * We could be nicer about the deleted file, and let it show | |
bc154b1e BF |
1498 | * up under the name it had before it was deleted rather than |
1499 | * under the original name of the file that was moved on top of it. | |
1da177e4 LT |
1500 | */ |
1501 | ||
9eaef27b TM |
1502 | /* |
1503 | * d_move_locked - move a dentry | |
1da177e4 LT |
1504 | * @dentry: entry to move |
1505 | * @target: new dentry | |
1506 | * | |
1507 | * Update the dcache to reflect the move of a file name. Negative | |
1508 | * dcache entries should not be moved in this way. | |
1509 | */ | |
9eaef27b | 1510 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
1da177e4 LT |
1511 | { |
1512 | struct hlist_head *list; | |
1513 | ||
1514 | if (!dentry->d_inode) | |
1515 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
1516 | ||
1da177e4 LT |
1517 | write_seqlock(&rename_lock); |
1518 | /* | |
1519 | * XXXX: do we really need to take target->d_lock? | |
1520 | */ | |
1521 | if (target < dentry) { | |
1522 | spin_lock(&target->d_lock); | |
a90b9c05 | 1523 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1524 | } else { |
1525 | spin_lock(&dentry->d_lock); | |
a90b9c05 | 1526 | spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1527 | } |
1528 | ||
1529 | /* Move the dentry to the target hash queue, if on different bucket */ | |
f77e3498 | 1530 | if (d_unhashed(dentry)) |
1da177e4 LT |
1531 | goto already_unhashed; |
1532 | ||
1533 | hlist_del_rcu(&dentry->d_hash); | |
1534 | ||
1535 | already_unhashed: | |
1536 | list = d_hash(target->d_parent, target->d_name.hash); | |
1537 | __d_rehash(dentry, list); | |
1538 | ||
1539 | /* Unhash the target: dput() will then get rid of it */ | |
1540 | __d_drop(target); | |
1541 | ||
5160ee6f ED |
1542 | list_del(&dentry->d_u.d_child); |
1543 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
1544 | |
1545 | /* Switch the names.. */ | |
1546 | switch_names(dentry, target); | |
1547 | do_switch(dentry->d_name.len, target->d_name.len); | |
1548 | do_switch(dentry->d_name.hash, target->d_name.hash); | |
1549 | ||
1550 | /* ... and switch the parents */ | |
1551 | if (IS_ROOT(dentry)) { | |
1552 | dentry->d_parent = target->d_parent; | |
1553 | target->d_parent = target; | |
5160ee6f | 1554 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 LT |
1555 | } else { |
1556 | do_switch(dentry->d_parent, target->d_parent); | |
1557 | ||
1558 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 1559 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
1560 | } |
1561 | ||
5160ee6f | 1562 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
1da177e4 | 1563 | spin_unlock(&target->d_lock); |
c32ccd87 | 1564 | fsnotify_d_move(dentry); |
1da177e4 LT |
1565 | spin_unlock(&dentry->d_lock); |
1566 | write_sequnlock(&rename_lock); | |
9eaef27b TM |
1567 | } |
1568 | ||
1569 | /** | |
1570 | * d_move - move a dentry | |
1571 | * @dentry: entry to move | |
1572 | * @target: new dentry | |
1573 | * | |
1574 | * Update the dcache to reflect the move of a file name. Negative | |
1575 | * dcache entries should not be moved in this way. | |
1576 | */ | |
1577 | ||
1578 | void d_move(struct dentry * dentry, struct dentry * target) | |
1579 | { | |
1580 | spin_lock(&dcache_lock); | |
1581 | d_move_locked(dentry, target); | |
1da177e4 LT |
1582 | spin_unlock(&dcache_lock); |
1583 | } | |
1584 | ||
9eaef27b TM |
1585 | /* |
1586 | * Helper that returns 1 if p1 is a parent of p2, else 0 | |
1587 | */ | |
1588 | static int d_isparent(struct dentry *p1, struct dentry *p2) | |
1589 | { | |
1590 | struct dentry *p; | |
1591 | ||
1592 | for (p = p2; p->d_parent != p; p = p->d_parent) { | |
1593 | if (p->d_parent == p1) | |
1594 | return 1; | |
1595 | } | |
1596 | return 0; | |
1597 | } | |
1598 | ||
1599 | /* | |
1600 | * This helper attempts to cope with remotely renamed directories | |
1601 | * | |
1602 | * It assumes that the caller is already holding | |
1603 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock | |
1604 | * | |
1605 | * Note: If ever the locking in lock_rename() changes, then please | |
1606 | * remember to update this too... | |
1607 | * | |
1608 | * On return, dcache_lock will have been unlocked. | |
1609 | */ | |
1610 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) | |
1611 | { | |
1612 | struct mutex *m1 = NULL, *m2 = NULL; | |
1613 | struct dentry *ret; | |
1614 | ||
1615 | /* If alias and dentry share a parent, then no extra locks required */ | |
1616 | if (alias->d_parent == dentry->d_parent) | |
1617 | goto out_unalias; | |
1618 | ||
1619 | /* Check for loops */ | |
1620 | ret = ERR_PTR(-ELOOP); | |
1621 | if (d_isparent(alias, dentry)) | |
1622 | goto out_err; | |
1623 | ||
1624 | /* See lock_rename() */ | |
1625 | ret = ERR_PTR(-EBUSY); | |
1626 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) | |
1627 | goto out_err; | |
1628 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
1629 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
1630 | goto out_err; | |
1631 | m2 = &alias->d_parent->d_inode->i_mutex; | |
1632 | out_unalias: | |
1633 | d_move_locked(alias, dentry); | |
1634 | ret = alias; | |
1635 | out_err: | |
1636 | spin_unlock(&dcache_lock); | |
1637 | if (m2) | |
1638 | mutex_unlock(m2); | |
1639 | if (m1) | |
1640 | mutex_unlock(m1); | |
1641 | return ret; | |
1642 | } | |
1643 | ||
770bfad8 DH |
1644 | /* |
1645 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
1646 | * named dentry in place of the dentry to be replaced. | |
1647 | */ | |
1648 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
1649 | { | |
1650 | struct dentry *dparent, *aparent; | |
1651 | ||
1652 | switch_names(dentry, anon); | |
1653 | do_switch(dentry->d_name.len, anon->d_name.len); | |
1654 | do_switch(dentry->d_name.hash, anon->d_name.hash); | |
1655 | ||
1656 | dparent = dentry->d_parent; | |
1657 | aparent = anon->d_parent; | |
1658 | ||
1659 | dentry->d_parent = (aparent == anon) ? dentry : aparent; | |
1660 | list_del(&dentry->d_u.d_child); | |
1661 | if (!IS_ROOT(dentry)) | |
1662 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); | |
1663 | else | |
1664 | INIT_LIST_HEAD(&dentry->d_u.d_child); | |
1665 | ||
1666 | anon->d_parent = (dparent == dentry) ? anon : dparent; | |
1667 | list_del(&anon->d_u.d_child); | |
1668 | if (!IS_ROOT(anon)) | |
1669 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); | |
1670 | else | |
1671 | INIT_LIST_HEAD(&anon->d_u.d_child); | |
1672 | ||
1673 | anon->d_flags &= ~DCACHE_DISCONNECTED; | |
1674 | } | |
1675 | ||
1676 | /** | |
1677 | * d_materialise_unique - introduce an inode into the tree | |
1678 | * @dentry: candidate dentry | |
1679 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
1680 | * | |
1681 | * Introduces an dentry into the tree, substituting an extant disconnected | |
1682 | * root directory alias in its place if there is one | |
1683 | */ | |
1684 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
1685 | { | |
9eaef27b | 1686 | struct dentry *actual; |
770bfad8 DH |
1687 | |
1688 | BUG_ON(!d_unhashed(dentry)); | |
1689 | ||
1690 | spin_lock(&dcache_lock); | |
1691 | ||
1692 | if (!inode) { | |
1693 | actual = dentry; | |
1694 | dentry->d_inode = NULL; | |
1695 | goto found_lock; | |
1696 | } | |
1697 | ||
9eaef27b TM |
1698 | if (S_ISDIR(inode->i_mode)) { |
1699 | struct dentry *alias; | |
1700 | ||
1701 | /* Does an aliased dentry already exist? */ | |
1702 | alias = __d_find_alias(inode, 0); | |
1703 | if (alias) { | |
1704 | actual = alias; | |
1705 | /* Is this an anonymous mountpoint that we could splice | |
1706 | * into our tree? */ | |
1707 | if (IS_ROOT(alias)) { | |
1708 | spin_lock(&alias->d_lock); | |
1709 | __d_materialise_dentry(dentry, alias); | |
1710 | __d_drop(alias); | |
1711 | goto found; | |
1712 | } | |
1713 | /* Nope, but we must(!) avoid directory aliasing */ | |
1714 | actual = __d_unalias(dentry, alias); | |
1715 | if (IS_ERR(actual)) | |
1716 | dput(alias); | |
1717 | goto out_nolock; | |
1718 | } | |
770bfad8 DH |
1719 | } |
1720 | ||
1721 | /* Add a unique reference */ | |
1722 | actual = __d_instantiate_unique(dentry, inode); | |
1723 | if (!actual) | |
1724 | actual = dentry; | |
1725 | else if (unlikely(!d_unhashed(actual))) | |
1726 | goto shouldnt_be_hashed; | |
1727 | ||
1728 | found_lock: | |
1729 | spin_lock(&actual->d_lock); | |
1730 | found: | |
1731 | _d_rehash(actual); | |
1732 | spin_unlock(&actual->d_lock); | |
1733 | spin_unlock(&dcache_lock); | |
9eaef27b | 1734 | out_nolock: |
770bfad8 DH |
1735 | if (actual == dentry) { |
1736 | security_d_instantiate(dentry, inode); | |
1737 | return NULL; | |
1738 | } | |
1739 | ||
1740 | iput(inode); | |
1741 | return actual; | |
1742 | ||
770bfad8 DH |
1743 | shouldnt_be_hashed: |
1744 | spin_unlock(&dcache_lock); | |
1745 | BUG(); | |
1746 | goto shouldnt_be_hashed; | |
1747 | } | |
1748 | ||
6092d048 RP |
1749 | static int prepend(char **buffer, int *buflen, const char *str, |
1750 | int namelen) | |
1751 | { | |
1752 | *buflen -= namelen; | |
1753 | if (*buflen < 0) | |
1754 | return -ENAMETOOLONG; | |
1755 | *buffer -= namelen; | |
1756 | memcpy(*buffer, str, namelen); | |
1757 | return 0; | |
1758 | } | |
1759 | ||
1da177e4 LT |
1760 | /** |
1761 | * d_path - return the path of a dentry | |
9d1bc601 MS |
1762 | * @path: the dentry/vfsmount to report |
1763 | * @root: root vfsmnt/dentry (may be modified by this function) | |
1da177e4 LT |
1764 | * @buffer: buffer to return value in |
1765 | * @buflen: buffer length | |
1766 | * | |
552ce544 LT |
1767 | * Convert a dentry into an ASCII path name. If the entry has been deleted |
1768 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
1da177e4 | 1769 | * |
552ce544 LT |
1770 | * Returns the buffer or an error code if the path was too long. |
1771 | * | |
1772 | * "buflen" should be positive. Caller holds the dcache_lock. | |
9d1bc601 MS |
1773 | * |
1774 | * If path is not reachable from the supplied root, then the value of | |
1775 | * root is changed (without modifying refcounts). | |
1da177e4 | 1776 | */ |
9d1bc601 MS |
1777 | char *__d_path(const struct path *path, struct path *root, |
1778 | char *buffer, int buflen) | |
1da177e4 | 1779 | { |
9d1bc601 MS |
1780 | struct dentry *dentry = path->dentry; |
1781 | struct vfsmount *vfsmnt = path->mnt; | |
552ce544 LT |
1782 | char * end = buffer+buflen; |
1783 | char * retval; | |
6092d048 RP |
1784 | |
1785 | prepend(&end, &buflen, "\0", 1); | |
1786 | if (!IS_ROOT(dentry) && d_unhashed(dentry) && | |
1787 | (prepend(&end, &buflen, " (deleted)", 10) != 0)) | |
552ce544 | 1788 | goto Elong; |
552ce544 LT |
1789 | |
1790 | if (buflen < 1) | |
1791 | goto Elong; | |
1792 | /* Get '/' right */ | |
1793 | retval = end-1; | |
1794 | *retval = '/'; | |
1795 | ||
1796 | for (;;) { | |
1da177e4 LT |
1797 | struct dentry * parent; |
1798 | ||
329c97f0 | 1799 | if (dentry == root->dentry && vfsmnt == root->mnt) |
552ce544 | 1800 | break; |
1da177e4 | 1801 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 1802 | /* Global root? */ |
1da177e4 LT |
1803 | spin_lock(&vfsmount_lock); |
1804 | if (vfsmnt->mnt_parent == vfsmnt) { | |
1805 | spin_unlock(&vfsmount_lock); | |
1806 | goto global_root; | |
1807 | } | |
1808 | dentry = vfsmnt->mnt_mountpoint; | |
1809 | vfsmnt = vfsmnt->mnt_parent; | |
1810 | spin_unlock(&vfsmount_lock); | |
1811 | continue; | |
1812 | } | |
1813 | parent = dentry->d_parent; | |
1814 | prefetch(parent); | |
6092d048 RP |
1815 | if ((prepend(&end, &buflen, dentry->d_name.name, |
1816 | dentry->d_name.len) != 0) || | |
1817 | (prepend(&end, &buflen, "/", 1) != 0)) | |
552ce544 | 1818 | goto Elong; |
552ce544 | 1819 | retval = end; |
1da177e4 LT |
1820 | dentry = parent; |
1821 | } | |
1822 | ||
552ce544 | 1823 | return retval; |
1da177e4 LT |
1824 | |
1825 | global_root: | |
6092d048 RP |
1826 | retval += 1; /* hit the slash */ |
1827 | if (prepend(&retval, &buflen, dentry->d_name.name, | |
1828 | dentry->d_name.len) != 0) | |
1da177e4 | 1829 | goto Elong; |
9d1bc601 MS |
1830 | root->mnt = vfsmnt; |
1831 | root->dentry = dentry; | |
552ce544 | 1832 | return retval; |
1da177e4 | 1833 | Elong: |
552ce544 | 1834 | return ERR_PTR(-ENAMETOOLONG); |
1da177e4 LT |
1835 | } |
1836 | ||
a03a8a70 JB |
1837 | /** |
1838 | * d_path - return the path of a dentry | |
cf28b486 | 1839 | * @path: path to report |
a03a8a70 JB |
1840 | * @buf: buffer to return value in |
1841 | * @buflen: buffer length | |
1842 | * | |
1843 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
1844 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
1845 | * | |
1846 | * Returns the buffer or an error code if the path was too long. | |
1847 | * | |
1848 | * "buflen" should be positive. Caller holds the dcache_lock. | |
1849 | */ | |
cf28b486 | 1850 | char *d_path(struct path *path, char *buf, int buflen) |
1da177e4 LT |
1851 | { |
1852 | char *res; | |
6ac08c39 | 1853 | struct path root; |
9d1bc601 | 1854 | struct path tmp; |
1da177e4 | 1855 | |
c23fbb6b ED |
1856 | /* |
1857 | * We have various synthetic filesystems that never get mounted. On | |
1858 | * these filesystems dentries are never used for lookup purposes, and | |
1859 | * thus don't need to be hashed. They also don't need a name until a | |
1860 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
1861 | * below allows us to generate a name for these objects on demand: | |
1862 | */ | |
cf28b486 JB |
1863 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
1864 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
c23fbb6b | 1865 | |
1da177e4 | 1866 | read_lock(¤t->fs->lock); |
6ac08c39 | 1867 | root = current->fs->root; |
6092d048 | 1868 | path_get(&root); |
1da177e4 | 1869 | read_unlock(¤t->fs->lock); |
552ce544 | 1870 | spin_lock(&dcache_lock); |
9d1bc601 MS |
1871 | tmp = root; |
1872 | res = __d_path(path, &tmp, buf, buflen); | |
552ce544 | 1873 | spin_unlock(&dcache_lock); |
6ac08c39 | 1874 | path_put(&root); |
1da177e4 LT |
1875 | return res; |
1876 | } | |
1877 | ||
c23fbb6b ED |
1878 | /* |
1879 | * Helper function for dentry_operations.d_dname() members | |
1880 | */ | |
1881 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
1882 | const char *fmt, ...) | |
1883 | { | |
1884 | va_list args; | |
1885 | char temp[64]; | |
1886 | int sz; | |
1887 | ||
1888 | va_start(args, fmt); | |
1889 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
1890 | va_end(args); | |
1891 | ||
1892 | if (sz > sizeof(temp) || sz > buflen) | |
1893 | return ERR_PTR(-ENAMETOOLONG); | |
1894 | ||
1895 | buffer += buflen - sz; | |
1896 | return memcpy(buffer, temp, sz); | |
1897 | } | |
1898 | ||
6092d048 RP |
1899 | /* |
1900 | * Write full pathname from the root of the filesystem into the buffer. | |
1901 | */ | |
1902 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
1903 | { | |
1904 | char *end = buf + buflen; | |
1905 | char *retval; | |
1906 | ||
1907 | spin_lock(&dcache_lock); | |
1908 | prepend(&end, &buflen, "\0", 1); | |
1909 | if (!IS_ROOT(dentry) && d_unhashed(dentry) && | |
1910 | (prepend(&end, &buflen, "//deleted", 9) != 0)) | |
1911 | goto Elong; | |
1912 | if (buflen < 1) | |
1913 | goto Elong; | |
1914 | /* Get '/' right */ | |
1915 | retval = end-1; | |
1916 | *retval = '/'; | |
1917 | ||
1918 | for (;;) { | |
1919 | struct dentry *parent; | |
1920 | if (IS_ROOT(dentry)) | |
1921 | break; | |
1922 | ||
1923 | parent = dentry->d_parent; | |
1924 | prefetch(parent); | |
1925 | ||
1926 | if ((prepend(&end, &buflen, dentry->d_name.name, | |
1927 | dentry->d_name.len) != 0) || | |
1928 | (prepend(&end, &buflen, "/", 1) != 0)) | |
1929 | goto Elong; | |
1930 | ||
1931 | retval = end; | |
1932 | dentry = parent; | |
1933 | } | |
1934 | spin_unlock(&dcache_lock); | |
1935 | return retval; | |
1936 | Elong: | |
1937 | spin_unlock(&dcache_lock); | |
1938 | return ERR_PTR(-ENAMETOOLONG); | |
1939 | } | |
1940 | ||
1da177e4 LT |
1941 | /* |
1942 | * NOTE! The user-level library version returns a | |
1943 | * character pointer. The kernel system call just | |
1944 | * returns the length of the buffer filled (which | |
1945 | * includes the ending '\0' character), or a negative | |
1946 | * error value. So libc would do something like | |
1947 | * | |
1948 | * char *getcwd(char * buf, size_t size) | |
1949 | * { | |
1950 | * int retval; | |
1951 | * | |
1952 | * retval = sys_getcwd(buf, size); | |
1953 | * if (retval >= 0) | |
1954 | * return buf; | |
1955 | * errno = -retval; | |
1956 | * return NULL; | |
1957 | * } | |
1958 | */ | |
1959 | asmlinkage long sys_getcwd(char __user *buf, unsigned long size) | |
1960 | { | |
552ce544 | 1961 | int error; |
6ac08c39 | 1962 | struct path pwd, root; |
552ce544 | 1963 | char *page = (char *) __get_free_page(GFP_USER); |
1da177e4 LT |
1964 | |
1965 | if (!page) | |
1966 | return -ENOMEM; | |
1967 | ||
1968 | read_lock(¤t->fs->lock); | |
6ac08c39 | 1969 | pwd = current->fs->pwd; |
6092d048 | 1970 | path_get(&pwd); |
6ac08c39 | 1971 | root = current->fs->root; |
6092d048 | 1972 | path_get(&root); |
1da177e4 LT |
1973 | read_unlock(¤t->fs->lock); |
1974 | ||
552ce544 LT |
1975 | error = -ENOENT; |
1976 | /* Has the current directory has been unlinked? */ | |
1977 | spin_lock(&dcache_lock); | |
6ac08c39 | 1978 | if (pwd.dentry->d_parent == pwd.dentry || !d_unhashed(pwd.dentry)) { |
552ce544 | 1979 | unsigned long len; |
9d1bc601 | 1980 | struct path tmp = root; |
552ce544 | 1981 | char * cwd; |
1da177e4 | 1982 | |
9d1bc601 | 1983 | cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE); |
552ce544 LT |
1984 | spin_unlock(&dcache_lock); |
1985 | ||
1986 | error = PTR_ERR(cwd); | |
1987 | if (IS_ERR(cwd)) | |
1988 | goto out; | |
1989 | ||
1990 | error = -ERANGE; | |
1991 | len = PAGE_SIZE + page - cwd; | |
1992 | if (len <= size) { | |
1993 | error = len; | |
1994 | if (copy_to_user(buf, cwd, len)) | |
1995 | error = -EFAULT; | |
1996 | } | |
1997 | } else | |
1998 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
1999 | |
2000 | out: | |
6ac08c39 JB |
2001 | path_put(&pwd); |
2002 | path_put(&root); | |
1da177e4 LT |
2003 | free_page((unsigned long) page); |
2004 | return error; | |
2005 | } | |
2006 | ||
2007 | /* | |
2008 | * Test whether new_dentry is a subdirectory of old_dentry. | |
2009 | * | |
2010 | * Trivially implemented using the dcache structure | |
2011 | */ | |
2012 | ||
2013 | /** | |
2014 | * is_subdir - is new dentry a subdirectory of old_dentry | |
2015 | * @new_dentry: new dentry | |
2016 | * @old_dentry: old dentry | |
2017 | * | |
2018 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
2019 | * Returns 0 otherwise. | |
2020 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
2021 | */ | |
2022 | ||
2023 | int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry) | |
2024 | { | |
2025 | int result; | |
2026 | struct dentry * saved = new_dentry; | |
2027 | unsigned long seq; | |
2028 | ||
2029 | /* need rcu_readlock to protect against the d_parent trashing due to | |
2030 | * d_move | |
2031 | */ | |
2032 | rcu_read_lock(); | |
2033 | do { | |
2034 | /* for restarting inner loop in case of seq retry */ | |
2035 | new_dentry = saved; | |
2036 | result = 0; | |
2037 | seq = read_seqbegin(&rename_lock); | |
2038 | for (;;) { | |
2039 | if (new_dentry != old_dentry) { | |
2040 | struct dentry * parent = new_dentry->d_parent; | |
2041 | if (parent == new_dentry) | |
2042 | break; | |
2043 | new_dentry = parent; | |
2044 | continue; | |
2045 | } | |
2046 | result = 1; | |
2047 | break; | |
2048 | } | |
2049 | } while (read_seqretry(&rename_lock, seq)); | |
2050 | rcu_read_unlock(); | |
2051 | ||
2052 | return result; | |
2053 | } | |
2054 | ||
2055 | void d_genocide(struct dentry *root) | |
2056 | { | |
2057 | struct dentry *this_parent = root; | |
2058 | struct list_head *next; | |
2059 | ||
2060 | spin_lock(&dcache_lock); | |
2061 | repeat: | |
2062 | next = this_parent->d_subdirs.next; | |
2063 | resume: | |
2064 | while (next != &this_parent->d_subdirs) { | |
2065 | struct list_head *tmp = next; | |
5160ee6f | 2066 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
2067 | next = tmp->next; |
2068 | if (d_unhashed(dentry)||!dentry->d_inode) | |
2069 | continue; | |
2070 | if (!list_empty(&dentry->d_subdirs)) { | |
2071 | this_parent = dentry; | |
2072 | goto repeat; | |
2073 | } | |
2074 | atomic_dec(&dentry->d_count); | |
2075 | } | |
2076 | if (this_parent != root) { | |
5160ee6f | 2077 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
2078 | atomic_dec(&this_parent->d_count); |
2079 | this_parent = this_parent->d_parent; | |
2080 | goto resume; | |
2081 | } | |
2082 | spin_unlock(&dcache_lock); | |
2083 | } | |
2084 | ||
2085 | /** | |
2086 | * find_inode_number - check for dentry with name | |
2087 | * @dir: directory to check | |
2088 | * @name: Name to find. | |
2089 | * | |
2090 | * Check whether a dentry already exists for the given name, | |
2091 | * and return the inode number if it has an inode. Otherwise | |
2092 | * 0 is returned. | |
2093 | * | |
2094 | * This routine is used to post-process directory listings for | |
2095 | * filesystems using synthetic inode numbers, and is necessary | |
2096 | * to keep getcwd() working. | |
2097 | */ | |
2098 | ||
2099 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) | |
2100 | { | |
2101 | struct dentry * dentry; | |
2102 | ino_t ino = 0; | |
2103 | ||
3e7e241f EB |
2104 | dentry = d_hash_and_lookup(dir, name); |
2105 | if (dentry) { | |
1da177e4 LT |
2106 | if (dentry->d_inode) |
2107 | ino = dentry->d_inode->i_ino; | |
2108 | dput(dentry); | |
2109 | } | |
1da177e4 LT |
2110 | return ino; |
2111 | } | |
2112 | ||
2113 | static __initdata unsigned long dhash_entries; | |
2114 | static int __init set_dhash_entries(char *str) | |
2115 | { | |
2116 | if (!str) | |
2117 | return 0; | |
2118 | dhash_entries = simple_strtoul(str, &str, 0); | |
2119 | return 1; | |
2120 | } | |
2121 | __setup("dhash_entries=", set_dhash_entries); | |
2122 | ||
2123 | static void __init dcache_init_early(void) | |
2124 | { | |
2125 | int loop; | |
2126 | ||
2127 | /* If hashes are distributed across NUMA nodes, defer | |
2128 | * hash allocation until vmalloc space is available. | |
2129 | */ | |
2130 | if (hashdist) | |
2131 | return; | |
2132 | ||
2133 | dentry_hashtable = | |
2134 | alloc_large_system_hash("Dentry cache", | |
2135 | sizeof(struct hlist_head), | |
2136 | dhash_entries, | |
2137 | 13, | |
2138 | HASH_EARLY, | |
2139 | &d_hash_shift, | |
2140 | &d_hash_mask, | |
2141 | 0); | |
2142 | ||
2143 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2144 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2145 | } | |
2146 | ||
74bf17cf | 2147 | static void __init dcache_init(void) |
1da177e4 LT |
2148 | { |
2149 | int loop; | |
2150 | ||
2151 | /* | |
2152 | * A constructor could be added for stable state like the lists, | |
2153 | * but it is probably not worth it because of the cache nature | |
2154 | * of the dcache. | |
2155 | */ | |
0a31bd5f CL |
2156 | dentry_cache = KMEM_CACHE(dentry, |
2157 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 | 2158 | |
8e1f936b | 2159 | register_shrinker(&dcache_shrinker); |
1da177e4 LT |
2160 | |
2161 | /* Hash may have been set up in dcache_init_early */ | |
2162 | if (!hashdist) | |
2163 | return; | |
2164 | ||
2165 | dentry_hashtable = | |
2166 | alloc_large_system_hash("Dentry cache", | |
2167 | sizeof(struct hlist_head), | |
2168 | dhash_entries, | |
2169 | 13, | |
2170 | 0, | |
2171 | &d_hash_shift, | |
2172 | &d_hash_mask, | |
2173 | 0); | |
2174 | ||
2175 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2176 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2177 | } | |
2178 | ||
2179 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 2180 | struct kmem_cache *names_cachep __read_mostly; |
1da177e4 LT |
2181 | |
2182 | /* SLAB cache for file structures */ | |
e18b890b | 2183 | struct kmem_cache *filp_cachep __read_mostly; |
1da177e4 LT |
2184 | |
2185 | EXPORT_SYMBOL(d_genocide); | |
2186 | ||
1da177e4 LT |
2187 | void __init vfs_caches_init_early(void) |
2188 | { | |
2189 | dcache_init_early(); | |
2190 | inode_init_early(); | |
2191 | } | |
2192 | ||
2193 | void __init vfs_caches_init(unsigned long mempages) | |
2194 | { | |
2195 | unsigned long reserve; | |
2196 | ||
2197 | /* Base hash sizes on available memory, with a reserve equal to | |
2198 | 150% of current kernel size */ | |
2199 | ||
2200 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
2201 | mempages -= reserve; | |
2202 | ||
2203 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 2204 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 LT |
2205 | |
2206 | filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0, | |
20c2df83 | 2207 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 2208 | |
74bf17cf DC |
2209 | dcache_init(); |
2210 | inode_init(); | |
1da177e4 | 2211 | files_init(mempages); |
74bf17cf | 2212 | mnt_init(); |
1da177e4 LT |
2213 | bdev_cache_init(); |
2214 | chrdev_init(); | |
2215 | } | |
2216 | ||
2217 | EXPORT_SYMBOL(d_alloc); | |
2218 | EXPORT_SYMBOL(d_alloc_anon); | |
2219 | EXPORT_SYMBOL(d_alloc_root); | |
2220 | EXPORT_SYMBOL(d_delete); | |
2221 | EXPORT_SYMBOL(d_find_alias); | |
2222 | EXPORT_SYMBOL(d_instantiate); | |
2223 | EXPORT_SYMBOL(d_invalidate); | |
2224 | EXPORT_SYMBOL(d_lookup); | |
2225 | EXPORT_SYMBOL(d_move); | |
770bfad8 | 2226 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
1da177e4 LT |
2227 | EXPORT_SYMBOL(d_path); |
2228 | EXPORT_SYMBOL(d_prune_aliases); | |
2229 | EXPORT_SYMBOL(d_rehash); | |
2230 | EXPORT_SYMBOL(d_splice_alias); | |
2231 | EXPORT_SYMBOL(d_validate); | |
2232 | EXPORT_SYMBOL(dget_locked); | |
2233 | EXPORT_SYMBOL(dput); | |
2234 | EXPORT_SYMBOL(find_inode_number); | |
2235 | EXPORT_SYMBOL(have_submounts); | |
2236 | EXPORT_SYMBOL(names_cachep); | |
2237 | EXPORT_SYMBOL(shrink_dcache_parent); | |
2238 | EXPORT_SYMBOL(shrink_dcache_sb); |