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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> | |
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> | |
5ad4e53b | 34 | #include <linux/fs_struct.h> |
613afbf8 | 35 | #include <linux/hardirq.h> |
07f3f05c | 36 | #include "internal.h" |
1da177e4 | 37 | |
789680d1 NP |
38 | /* |
39 | * Usage: | |
23044507 NP |
40 | * dcache_hash_lock protects: |
41 | * - the dcache hash table, s_anon lists | |
42 | * dcache_lru_lock protects: | |
43 | * - the dcache lru lists and counters | |
44 | * d_lock protects: | |
45 | * - d_flags | |
46 | * - d_name | |
47 | * - d_lru | |
b7ab39f6 | 48 | * - d_count |
789680d1 NP |
49 | * |
50 | * Ordering: | |
51 | * dcache_lock | |
52 | * dentry->d_lock | |
23044507 | 53 | * dcache_lru_lock |
789680d1 NP |
54 | * dcache_hash_lock |
55 | * | |
56 | * if (dentry1 < dentry2) | |
57 | * dentry1->d_lock | |
58 | * dentry2->d_lock | |
59 | */ | |
fa3536cc | 60 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
61 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
62 | ||
789680d1 | 63 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock); |
23044507 | 64 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); |
789680d1 | 65 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); |
74c3cbe3 | 66 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 LT |
67 | |
68 | EXPORT_SYMBOL(dcache_lock); | |
69 | ||
e18b890b | 70 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 LT |
71 | |
72 | #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) | |
73 | ||
74 | /* | |
75 | * This is the single most critical data structure when it comes | |
76 | * to the dcache: the hashtable for lookups. Somebody should try | |
77 | * to make this good - I've just made it work. | |
78 | * | |
79 | * This hash-function tries to avoid losing too many bits of hash | |
80 | * information, yet avoid using a prime hash-size or similar. | |
81 | */ | |
82 | #define D_HASHBITS d_hash_shift | |
83 | #define D_HASHMASK d_hash_mask | |
84 | ||
fa3536cc ED |
85 | static unsigned int d_hash_mask __read_mostly; |
86 | static unsigned int d_hash_shift __read_mostly; | |
87 | static struct hlist_head *dentry_hashtable __read_mostly; | |
1da177e4 LT |
88 | |
89 | /* Statistics gathering. */ | |
90 | struct dentry_stat_t dentry_stat = { | |
91 | .age_limit = 45, | |
92 | }; | |
93 | ||
3e880fb5 | 94 | static DEFINE_PER_CPU(unsigned int, nr_dentry); |
312d3ca8 CH |
95 | |
96 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
3e880fb5 NP |
97 | static int get_nr_dentry(void) |
98 | { | |
99 | int i; | |
100 | int sum = 0; | |
101 | for_each_possible_cpu(i) | |
102 | sum += per_cpu(nr_dentry, i); | |
103 | return sum < 0 ? 0 : sum; | |
104 | } | |
105 | ||
312d3ca8 CH |
106 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
107 | size_t *lenp, loff_t *ppos) | |
108 | { | |
3e880fb5 | 109 | dentry_stat.nr_dentry = get_nr_dentry(); |
312d3ca8 CH |
110 | return proc_dointvec(table, write, buffer, lenp, ppos); |
111 | } | |
112 | #endif | |
113 | ||
9c82ab9c | 114 | static void __d_free(struct rcu_head *head) |
1da177e4 | 115 | { |
9c82ab9c CH |
116 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
117 | ||
fd217f4d | 118 | WARN_ON(!list_empty(&dentry->d_alias)); |
1da177e4 LT |
119 | if (dname_external(dentry)) |
120 | kfree(dentry->d_name.name); | |
121 | kmem_cache_free(dentry_cache, dentry); | |
122 | } | |
123 | ||
124 | /* | |
312d3ca8 | 125 | * no dcache_lock, please. |
1da177e4 LT |
126 | */ |
127 | static void d_free(struct dentry *dentry) | |
128 | { | |
b7ab39f6 | 129 | BUG_ON(dentry->d_count); |
3e880fb5 | 130 | this_cpu_dec(nr_dentry); |
1da177e4 LT |
131 | if (dentry->d_op && dentry->d_op->d_release) |
132 | dentry->d_op->d_release(dentry); | |
312d3ca8 | 133 | |
b3423415 | 134 | /* if dentry was never inserted into hash, immediate free is OK */ |
e8462caa | 135 | if (hlist_unhashed(&dentry->d_hash)) |
9c82ab9c | 136 | __d_free(&dentry->d_u.d_rcu); |
b3423415 | 137 | else |
9c82ab9c | 138 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
1da177e4 LT |
139 | } |
140 | ||
141 | /* | |
142 | * Release the dentry's inode, using the filesystem | |
143 | * d_iput() operation if defined. | |
1da177e4 | 144 | */ |
858119e1 | 145 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 MS |
146 | __releases(dentry->d_lock) |
147 | __releases(dcache_lock) | |
1da177e4 LT |
148 | { |
149 | struct inode *inode = dentry->d_inode; | |
150 | if (inode) { | |
151 | dentry->d_inode = NULL; | |
152 | list_del_init(&dentry->d_alias); | |
153 | spin_unlock(&dentry->d_lock); | |
154 | spin_unlock(&dcache_lock); | |
f805fbda LT |
155 | if (!inode->i_nlink) |
156 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
157 | if (dentry->d_op && dentry->d_op->d_iput) |
158 | dentry->d_op->d_iput(dentry, inode); | |
159 | else | |
160 | iput(inode); | |
161 | } else { | |
162 | spin_unlock(&dentry->d_lock); | |
163 | spin_unlock(&dcache_lock); | |
164 | } | |
165 | } | |
166 | ||
da3bbdd4 | 167 | /* |
23044507 | 168 | * dentry_lru_(add|del|move_tail) must be called with d_lock held. |
da3bbdd4 KM |
169 | */ |
170 | static void dentry_lru_add(struct dentry *dentry) | |
171 | { | |
a4633357 | 172 | if (list_empty(&dentry->d_lru)) { |
23044507 | 173 | spin_lock(&dcache_lru_lock); |
a4633357 CH |
174 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
175 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 176 | dentry_stat.nr_unused++; |
23044507 | 177 | spin_unlock(&dcache_lru_lock); |
a4633357 | 178 | } |
da3bbdd4 KM |
179 | } |
180 | ||
23044507 NP |
181 | static void __dentry_lru_del(struct dentry *dentry) |
182 | { | |
183 | list_del_init(&dentry->d_lru); | |
184 | dentry->d_sb->s_nr_dentry_unused--; | |
185 | dentry_stat.nr_unused--; | |
186 | } | |
187 | ||
da3bbdd4 KM |
188 | static void dentry_lru_del(struct dentry *dentry) |
189 | { | |
190 | if (!list_empty(&dentry->d_lru)) { | |
23044507 NP |
191 | spin_lock(&dcache_lru_lock); |
192 | __dentry_lru_del(dentry); | |
193 | spin_unlock(&dcache_lru_lock); | |
da3bbdd4 KM |
194 | } |
195 | } | |
196 | ||
a4633357 | 197 | static void dentry_lru_move_tail(struct dentry *dentry) |
da3bbdd4 | 198 | { |
23044507 | 199 | spin_lock(&dcache_lru_lock); |
a4633357 CH |
200 | if (list_empty(&dentry->d_lru)) { |
201 | list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
202 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 203 | dentry_stat.nr_unused++; |
a4633357 CH |
204 | } else { |
205 | list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
da3bbdd4 | 206 | } |
23044507 | 207 | spin_unlock(&dcache_lru_lock); |
da3bbdd4 KM |
208 | } |
209 | ||
d52b9086 MS |
210 | /** |
211 | * d_kill - kill dentry and return parent | |
212 | * @dentry: dentry to kill | |
213 | * | |
31f3e0b3 | 214 | * The dentry must already be unhashed and removed from the LRU. |
d52b9086 MS |
215 | * |
216 | * If this is the root of the dentry tree, return NULL. | |
23044507 NP |
217 | * |
218 | * dcache_lock and d_lock must be held by caller, are dropped by d_kill. | |
d52b9086 MS |
219 | */ |
220 | static struct dentry *d_kill(struct dentry *dentry) | |
31f3e0b3 MS |
221 | __releases(dentry->d_lock) |
222 | __releases(dcache_lock) | |
d52b9086 MS |
223 | { |
224 | struct dentry *parent; | |
225 | ||
226 | list_del(&dentry->d_u.d_child); | |
d52b9086 | 227 | dentry_iput(dentry); |
b7ab39f6 NP |
228 | /* |
229 | * dentry_iput drops the locks, at which point nobody (except | |
230 | * transient RCU lookups) can reach this dentry. | |
231 | */ | |
871c0067 OH |
232 | if (IS_ROOT(dentry)) |
233 | parent = NULL; | |
234 | else | |
235 | parent = dentry->d_parent; | |
d52b9086 | 236 | d_free(dentry); |
871c0067 | 237 | return parent; |
d52b9086 MS |
238 | } |
239 | ||
789680d1 NP |
240 | /** |
241 | * d_drop - drop a dentry | |
242 | * @dentry: dentry to drop | |
243 | * | |
244 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
245 | * be found through a VFS lookup any more. Note that this is different from | |
246 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
247 | * possible, giving a successful _negative_ lookup, while d_drop will | |
248 | * just make the cache lookup fail. | |
249 | * | |
250 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
251 | * reason (NFS timeouts or autofs deletes). | |
252 | * | |
253 | * __d_drop requires dentry->d_lock. | |
254 | */ | |
255 | void __d_drop(struct dentry *dentry) | |
256 | { | |
257 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { | |
258 | dentry->d_flags |= DCACHE_UNHASHED; | |
259 | spin_lock(&dcache_hash_lock); | |
260 | hlist_del_rcu(&dentry->d_hash); | |
261 | spin_unlock(&dcache_hash_lock); | |
262 | } | |
263 | } | |
264 | EXPORT_SYMBOL(__d_drop); | |
265 | ||
266 | void d_drop(struct dentry *dentry) | |
267 | { | |
268 | spin_lock(&dcache_lock); | |
269 | spin_lock(&dentry->d_lock); | |
270 | __d_drop(dentry); | |
271 | spin_unlock(&dentry->d_lock); | |
272 | spin_unlock(&dcache_lock); | |
273 | } | |
274 | EXPORT_SYMBOL(d_drop); | |
275 | ||
1da177e4 LT |
276 | /* |
277 | * This is dput | |
278 | * | |
279 | * This is complicated by the fact that we do not want to put | |
280 | * dentries that are no longer on any hash chain on the unused | |
281 | * list: we'd much rather just get rid of them immediately. | |
282 | * | |
283 | * However, that implies that we have to traverse the dentry | |
284 | * tree upwards to the parents which might _also_ now be | |
285 | * scheduled for deletion (it may have been only waiting for | |
286 | * its last child to go away). | |
287 | * | |
288 | * This tail recursion is done by hand as we don't want to depend | |
289 | * on the compiler to always get this right (gcc generally doesn't). | |
290 | * Real recursion would eat up our stack space. | |
291 | */ | |
292 | ||
293 | /* | |
294 | * dput - release a dentry | |
295 | * @dentry: dentry to release | |
296 | * | |
297 | * Release a dentry. This will drop the usage count and if appropriate | |
298 | * call the dentry unlink method as well as removing it from the queues and | |
299 | * releasing its resources. If the parent dentries were scheduled for release | |
300 | * they too may now get deleted. | |
301 | * | |
302 | * no dcache lock, please. | |
303 | */ | |
304 | ||
305 | void dput(struct dentry *dentry) | |
306 | { | |
307 | if (!dentry) | |
308 | return; | |
309 | ||
310 | repeat: | |
b7ab39f6 | 311 | if (dentry->d_count == 1) |
1da177e4 | 312 | might_sleep(); |
1da177e4 | 313 | spin_lock(&dentry->d_lock); |
b7ab39f6 NP |
314 | if (dentry->d_count == 1) { |
315 | if (!spin_trylock(&dcache_lock)) { | |
316 | /* | |
317 | * Something of a livelock possibility we could avoid | |
318 | * by taking dcache_lock and trying again, but we | |
319 | * want to reduce dcache_lock anyway so this will | |
320 | * get improved. | |
321 | */ | |
322 | spin_unlock(&dentry->d_lock); | |
323 | goto repeat; | |
324 | } | |
325 | } | |
326 | dentry->d_count--; | |
327 | if (dentry->d_count) { | |
1da177e4 LT |
328 | spin_unlock(&dentry->d_lock); |
329 | spin_unlock(&dcache_lock); | |
330 | return; | |
331 | } | |
332 | ||
333 | /* | |
334 | * AV: ->d_delete() is _NOT_ allowed to block now. | |
335 | */ | |
336 | if (dentry->d_op && dentry->d_op->d_delete) { | |
337 | if (dentry->d_op->d_delete(dentry)) | |
338 | goto unhash_it; | |
339 | } | |
265ac902 | 340 | |
1da177e4 LT |
341 | /* Unreachable? Get rid of it */ |
342 | if (d_unhashed(dentry)) | |
343 | goto kill_it; | |
265ac902 NP |
344 | |
345 | /* Otherwise leave it cached and ensure it's on the LRU */ | |
346 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 347 | dentry_lru_add(dentry); |
265ac902 | 348 | |
1da177e4 LT |
349 | spin_unlock(&dentry->d_lock); |
350 | spin_unlock(&dcache_lock); | |
351 | return; | |
352 | ||
353 | unhash_it: | |
354 | __d_drop(dentry); | |
d52b9086 | 355 | kill_it: |
da3bbdd4 KM |
356 | /* if dentry was on the d_lru list delete it from there */ |
357 | dentry_lru_del(dentry); | |
d52b9086 MS |
358 | dentry = d_kill(dentry); |
359 | if (dentry) | |
360 | goto repeat; | |
1da177e4 | 361 | } |
ec4f8605 | 362 | EXPORT_SYMBOL(dput); |
1da177e4 LT |
363 | |
364 | /** | |
365 | * d_invalidate - invalidate a dentry | |
366 | * @dentry: dentry to invalidate | |
367 | * | |
368 | * Try to invalidate the dentry if it turns out to be | |
369 | * possible. If there are other dentries that can be | |
370 | * reached through this one we can't delete it and we | |
371 | * return -EBUSY. On success we return 0. | |
372 | * | |
373 | * no dcache lock. | |
374 | */ | |
375 | ||
376 | int d_invalidate(struct dentry * dentry) | |
377 | { | |
378 | /* | |
379 | * If it's already been dropped, return OK. | |
380 | */ | |
381 | spin_lock(&dcache_lock); | |
382 | if (d_unhashed(dentry)) { | |
383 | spin_unlock(&dcache_lock); | |
384 | return 0; | |
385 | } | |
386 | /* | |
387 | * Check whether to do a partial shrink_dcache | |
388 | * to get rid of unused child entries. | |
389 | */ | |
390 | if (!list_empty(&dentry->d_subdirs)) { | |
391 | spin_unlock(&dcache_lock); | |
392 | shrink_dcache_parent(dentry); | |
393 | spin_lock(&dcache_lock); | |
394 | } | |
395 | ||
396 | /* | |
397 | * Somebody else still using it? | |
398 | * | |
399 | * If it's a directory, we can't drop it | |
400 | * for fear of somebody re-populating it | |
401 | * with children (even though dropping it | |
402 | * would make it unreachable from the root, | |
403 | * we might still populate it if it was a | |
404 | * working directory or similar). | |
405 | */ | |
406 | spin_lock(&dentry->d_lock); | |
b7ab39f6 | 407 | if (dentry->d_count > 1) { |
1da177e4 LT |
408 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
409 | spin_unlock(&dentry->d_lock); | |
410 | spin_unlock(&dcache_lock); | |
411 | return -EBUSY; | |
412 | } | |
413 | } | |
414 | ||
415 | __d_drop(dentry); | |
416 | spin_unlock(&dentry->d_lock); | |
417 | spin_unlock(&dcache_lock); | |
418 | return 0; | |
419 | } | |
ec4f8605 | 420 | EXPORT_SYMBOL(d_invalidate); |
1da177e4 | 421 | |
b7ab39f6 | 422 | /* This must be called with dcache_lock and d_lock held */ |
23044507 NP |
423 | static inline struct dentry * __dget_locked_dlock(struct dentry *dentry) |
424 | { | |
b7ab39f6 | 425 | dentry->d_count++; |
23044507 NP |
426 | dentry_lru_del(dentry); |
427 | return dentry; | |
428 | } | |
429 | ||
b7ab39f6 | 430 | /* This should be called _only_ with dcache_lock held */ |
1da177e4 LT |
431 | static inline struct dentry * __dget_locked(struct dentry *dentry) |
432 | { | |
23044507 | 433 | spin_lock(&dentry->d_lock); |
b7ab39f6 | 434 | __dget_locked_dlock(dentry); |
23044507 | 435 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
436 | return dentry; |
437 | } | |
438 | ||
b7ab39f6 NP |
439 | struct dentry * dget_locked_dlock(struct dentry *dentry) |
440 | { | |
441 | return __dget_locked_dlock(dentry); | |
442 | } | |
443 | ||
1da177e4 LT |
444 | struct dentry * dget_locked(struct dentry *dentry) |
445 | { | |
446 | return __dget_locked(dentry); | |
447 | } | |
ec4f8605 | 448 | EXPORT_SYMBOL(dget_locked); |
1da177e4 | 449 | |
b7ab39f6 NP |
450 | struct dentry *dget_parent(struct dentry *dentry) |
451 | { | |
452 | struct dentry *ret; | |
453 | ||
454 | repeat: | |
455 | spin_lock(&dentry->d_lock); | |
456 | ret = dentry->d_parent; | |
457 | if (!ret) | |
458 | goto out; | |
459 | if (dentry == ret) { | |
460 | ret->d_count++; | |
461 | goto out; | |
462 | } | |
463 | if (!spin_trylock(&ret->d_lock)) { | |
464 | spin_unlock(&dentry->d_lock); | |
465 | cpu_relax(); | |
466 | goto repeat; | |
467 | } | |
468 | BUG_ON(!ret->d_count); | |
469 | ret->d_count++; | |
470 | spin_unlock(&ret->d_lock); | |
471 | out: | |
472 | spin_unlock(&dentry->d_lock); | |
473 | return ret; | |
474 | } | |
475 | EXPORT_SYMBOL(dget_parent); | |
476 | ||
1da177e4 LT |
477 | /** |
478 | * d_find_alias - grab a hashed alias of inode | |
479 | * @inode: inode in question | |
480 | * @want_discon: flag, used by d_splice_alias, to request | |
481 | * that only a DISCONNECTED alias be returned. | |
482 | * | |
483 | * If inode has a hashed alias, or is a directory and has any alias, | |
484 | * acquire the reference to alias and return it. Otherwise return NULL. | |
485 | * Notice that if inode is a directory there can be only one alias and | |
486 | * it can be unhashed only if it has no children, or if it is the root | |
487 | * of a filesystem. | |
488 | * | |
21c0d8fd | 489 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
1da177e4 | 490 | * any other hashed alias over that one unless @want_discon is set, |
21c0d8fd | 491 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
1da177e4 LT |
492 | */ |
493 | ||
494 | static struct dentry * __d_find_alias(struct inode *inode, int want_discon) | |
495 | { | |
496 | struct list_head *head, *next, *tmp; | |
497 | struct dentry *alias, *discon_alias=NULL; | |
498 | ||
499 | head = &inode->i_dentry; | |
500 | next = inode->i_dentry.next; | |
501 | while (next != head) { | |
502 | tmp = next; | |
503 | next = tmp->next; | |
504 | prefetch(next); | |
505 | alias = list_entry(tmp, struct dentry, d_alias); | |
506 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
21c0d8fd N |
507 | if (IS_ROOT(alias) && |
508 | (alias->d_flags & DCACHE_DISCONNECTED)) | |
1da177e4 LT |
509 | discon_alias = alias; |
510 | else if (!want_discon) { | |
511 | __dget_locked(alias); | |
512 | return alias; | |
513 | } | |
514 | } | |
515 | } | |
516 | if (discon_alias) | |
517 | __dget_locked(discon_alias); | |
518 | return discon_alias; | |
519 | } | |
520 | ||
521 | struct dentry * d_find_alias(struct inode *inode) | |
522 | { | |
214fda1f DH |
523 | struct dentry *de = NULL; |
524 | ||
525 | if (!list_empty(&inode->i_dentry)) { | |
526 | spin_lock(&dcache_lock); | |
527 | de = __d_find_alias(inode, 0); | |
528 | spin_unlock(&dcache_lock); | |
529 | } | |
1da177e4 LT |
530 | return de; |
531 | } | |
ec4f8605 | 532 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
533 | |
534 | /* | |
535 | * Try to kill dentries associated with this inode. | |
536 | * WARNING: you must own a reference to inode. | |
537 | */ | |
538 | void d_prune_aliases(struct inode *inode) | |
539 | { | |
0cdca3f9 | 540 | struct dentry *dentry; |
1da177e4 LT |
541 | restart: |
542 | spin_lock(&dcache_lock); | |
0cdca3f9 | 543 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 | 544 | spin_lock(&dentry->d_lock); |
b7ab39f6 | 545 | if (!dentry->d_count) { |
23044507 | 546 | __dget_locked_dlock(dentry); |
1da177e4 LT |
547 | __d_drop(dentry); |
548 | spin_unlock(&dentry->d_lock); | |
549 | spin_unlock(&dcache_lock); | |
550 | dput(dentry); | |
551 | goto restart; | |
552 | } | |
553 | spin_unlock(&dentry->d_lock); | |
554 | } | |
555 | spin_unlock(&dcache_lock); | |
556 | } | |
ec4f8605 | 557 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 LT |
558 | |
559 | /* | |
d702ccb3 AM |
560 | * Throw away a dentry - free the inode, dput the parent. This requires that |
561 | * the LRU list has already been removed. | |
562 | * | |
85864e10 MS |
563 | * Try to prune ancestors as well. This is necessary to prevent |
564 | * quadratic behavior of shrink_dcache_parent(), but is also expected | |
565 | * to be beneficial in reducing dentry cache fragmentation. | |
1da177e4 | 566 | */ |
85864e10 | 567 | static void prune_one_dentry(struct dentry * dentry) |
31f3e0b3 MS |
568 | __releases(dentry->d_lock) |
569 | __releases(dcache_lock) | |
1da177e4 | 570 | { |
1da177e4 | 571 | __d_drop(dentry); |
d52b9086 | 572 | dentry = d_kill(dentry); |
d52b9086 MS |
573 | |
574 | /* | |
575 | * Prune ancestors. Locking is simpler than in dput(), | |
576 | * because dcache_lock needs to be taken anyway. | |
577 | */ | |
d52b9086 | 578 | while (dentry) { |
23044507 | 579 | spin_lock(&dcache_lock); |
b7ab39f6 NP |
580 | spin_lock(&dentry->d_lock); |
581 | dentry->d_count--; | |
582 | if (dentry->d_count) { | |
583 | spin_unlock(&dentry->d_lock); | |
23044507 | 584 | spin_unlock(&dcache_lock); |
d52b9086 | 585 | return; |
23044507 | 586 | } |
d52b9086 | 587 | |
a4633357 | 588 | dentry_lru_del(dentry); |
d52b9086 MS |
589 | __d_drop(dentry); |
590 | dentry = d_kill(dentry); | |
d52b9086 | 591 | } |
1da177e4 LT |
592 | } |
593 | ||
3049cfe2 | 594 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 595 | { |
da3bbdd4 | 596 | struct dentry *dentry; |
da3bbdd4 | 597 | |
3049cfe2 CH |
598 | while (!list_empty(list)) { |
599 | dentry = list_entry(list->prev, struct dentry, d_lru); | |
23044507 NP |
600 | |
601 | if (!spin_trylock(&dentry->d_lock)) { | |
602 | spin_unlock(&dcache_lru_lock); | |
603 | cpu_relax(); | |
604 | spin_lock(&dcache_lru_lock); | |
605 | continue; | |
606 | } | |
607 | ||
608 | __dentry_lru_del(dentry); | |
3049cfe2 | 609 | |
1da177e4 LT |
610 | /* |
611 | * We found an inuse dentry which was not removed from | |
da3bbdd4 KM |
612 | * the LRU because of laziness during lookup. Do not free |
613 | * it - just keep it off the LRU list. | |
1da177e4 | 614 | */ |
b7ab39f6 | 615 | if (dentry->d_count) { |
da3bbdd4 | 616 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
617 | continue; |
618 | } | |
23044507 NP |
619 | spin_unlock(&dcache_lru_lock); |
620 | ||
da3bbdd4 | 621 | prune_one_dentry(dentry); |
23044507 NP |
622 | /* dcache_lock and dentry->d_lock dropped */ |
623 | spin_lock(&dcache_lock); | |
624 | spin_lock(&dcache_lru_lock); | |
da3bbdd4 | 625 | } |
3049cfe2 CH |
626 | } |
627 | ||
628 | /** | |
629 | * __shrink_dcache_sb - shrink the dentry LRU on a given superblock | |
630 | * @sb: superblock to shrink dentry LRU. | |
631 | * @count: number of entries to prune | |
632 | * @flags: flags to control the dentry processing | |
633 | * | |
634 | * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. | |
635 | */ | |
636 | static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) | |
637 | { | |
638 | /* called from prune_dcache() and shrink_dcache_parent() */ | |
639 | struct dentry *dentry; | |
640 | LIST_HEAD(referenced); | |
641 | LIST_HEAD(tmp); | |
642 | int cnt = *count; | |
643 | ||
644 | spin_lock(&dcache_lock); | |
23044507 NP |
645 | relock: |
646 | spin_lock(&dcache_lru_lock); | |
3049cfe2 CH |
647 | while (!list_empty(&sb->s_dentry_lru)) { |
648 | dentry = list_entry(sb->s_dentry_lru.prev, | |
649 | struct dentry, d_lru); | |
650 | BUG_ON(dentry->d_sb != sb); | |
651 | ||
23044507 NP |
652 | if (!spin_trylock(&dentry->d_lock)) { |
653 | spin_unlock(&dcache_lru_lock); | |
654 | cpu_relax(); | |
655 | goto relock; | |
656 | } | |
657 | ||
3049cfe2 CH |
658 | /* |
659 | * If we are honouring the DCACHE_REFERENCED flag and the | |
660 | * dentry has this flag set, don't free it. Clear the flag | |
661 | * and put it back on the LRU. | |
662 | */ | |
23044507 NP |
663 | if (flags & DCACHE_REFERENCED && |
664 | dentry->d_flags & DCACHE_REFERENCED) { | |
665 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
666 | list_move(&dentry->d_lru, &referenced); | |
3049cfe2 | 667 | spin_unlock(&dentry->d_lock); |
23044507 NP |
668 | } else { |
669 | list_move_tail(&dentry->d_lru, &tmp); | |
670 | spin_unlock(&dentry->d_lock); | |
671 | if (!--cnt) | |
672 | break; | |
3049cfe2 | 673 | } |
23044507 | 674 | /* XXX: re-add cond_resched_lock when dcache_lock goes away */ |
3049cfe2 CH |
675 | } |
676 | ||
677 | *count = cnt; | |
678 | shrink_dentry_list(&tmp); | |
679 | ||
da3bbdd4 KM |
680 | if (!list_empty(&referenced)) |
681 | list_splice(&referenced, &sb->s_dentry_lru); | |
23044507 | 682 | spin_unlock(&dcache_lru_lock); |
da3bbdd4 | 683 | spin_unlock(&dcache_lock); |
3049cfe2 | 684 | |
da3bbdd4 KM |
685 | } |
686 | ||
687 | /** | |
688 | * prune_dcache - shrink the dcache | |
689 | * @count: number of entries to try to free | |
690 | * | |
691 | * Shrink the dcache. This is done when we need more memory, or simply when we | |
692 | * need to unmount something (at which point we need to unuse all dentries). | |
693 | * | |
694 | * This function may fail to free any resources if all the dentries are in use. | |
695 | */ | |
696 | static void prune_dcache(int count) | |
697 | { | |
dca33252 | 698 | struct super_block *sb, *p = NULL; |
da3bbdd4 | 699 | int w_count; |
86c8749e | 700 | int unused = dentry_stat.nr_unused; |
da3bbdd4 KM |
701 | int prune_ratio; |
702 | int pruned; | |
703 | ||
704 | if (unused == 0 || count == 0) | |
705 | return; | |
706 | spin_lock(&dcache_lock); | |
da3bbdd4 KM |
707 | if (count >= unused) |
708 | prune_ratio = 1; | |
709 | else | |
710 | prune_ratio = unused / count; | |
711 | spin_lock(&sb_lock); | |
dca33252 | 712 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
713 | if (list_empty(&sb->s_instances)) |
714 | continue; | |
da3bbdd4 | 715 | if (sb->s_nr_dentry_unused == 0) |
1da177e4 | 716 | continue; |
da3bbdd4 KM |
717 | sb->s_count++; |
718 | /* Now, we reclaim unused dentrins with fairness. | |
719 | * We reclaim them same percentage from each superblock. | |
720 | * We calculate number of dentries to scan on this sb | |
721 | * as follows, but the implementation is arranged to avoid | |
722 | * overflows: | |
723 | * number of dentries to scan on this sb = | |
724 | * count * (number of dentries on this sb / | |
725 | * number of dentries in the machine) | |
0feae5c4 | 726 | */ |
da3bbdd4 KM |
727 | spin_unlock(&sb_lock); |
728 | if (prune_ratio != 1) | |
729 | w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1; | |
730 | else | |
731 | w_count = sb->s_nr_dentry_unused; | |
732 | pruned = w_count; | |
0feae5c4 | 733 | /* |
da3bbdd4 KM |
734 | * We need to be sure this filesystem isn't being unmounted, |
735 | * otherwise we could race with generic_shutdown_super(), and | |
736 | * end up holding a reference to an inode while the filesystem | |
737 | * is unmounted. So we try to get s_umount, and make sure | |
738 | * s_root isn't NULL. | |
0feae5c4 | 739 | */ |
da3bbdd4 KM |
740 | if (down_read_trylock(&sb->s_umount)) { |
741 | if ((sb->s_root != NULL) && | |
742 | (!list_empty(&sb->s_dentry_lru))) { | |
743 | spin_unlock(&dcache_lock); | |
744 | __shrink_dcache_sb(sb, &w_count, | |
745 | DCACHE_REFERENCED); | |
746 | pruned -= w_count; | |
747 | spin_lock(&dcache_lock); | |
0feae5c4 | 748 | } |
da3bbdd4 | 749 | up_read(&sb->s_umount); |
0feae5c4 | 750 | } |
da3bbdd4 | 751 | spin_lock(&sb_lock); |
dca33252 AV |
752 | if (p) |
753 | __put_super(p); | |
da3bbdd4 | 754 | count -= pruned; |
dca33252 | 755 | p = sb; |
79893c17 AV |
756 | /* more work left to do? */ |
757 | if (count <= 0) | |
758 | break; | |
1da177e4 | 759 | } |
dca33252 AV |
760 | if (p) |
761 | __put_super(p); | |
da3bbdd4 | 762 | spin_unlock(&sb_lock); |
1da177e4 LT |
763 | spin_unlock(&dcache_lock); |
764 | } | |
765 | ||
1da177e4 LT |
766 | /** |
767 | * shrink_dcache_sb - shrink dcache for a superblock | |
768 | * @sb: superblock | |
769 | * | |
3049cfe2 CH |
770 | * Shrink the dcache for the specified super block. This is used to free |
771 | * the dcache before unmounting a file system. | |
1da177e4 | 772 | */ |
3049cfe2 | 773 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 774 | { |
3049cfe2 CH |
775 | LIST_HEAD(tmp); |
776 | ||
777 | spin_lock(&dcache_lock); | |
23044507 | 778 | spin_lock(&dcache_lru_lock); |
3049cfe2 CH |
779 | while (!list_empty(&sb->s_dentry_lru)) { |
780 | list_splice_init(&sb->s_dentry_lru, &tmp); | |
781 | shrink_dentry_list(&tmp); | |
782 | } | |
23044507 | 783 | spin_unlock(&dcache_lru_lock); |
3049cfe2 | 784 | spin_unlock(&dcache_lock); |
1da177e4 | 785 | } |
ec4f8605 | 786 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 787 | |
c636ebdb DH |
788 | /* |
789 | * destroy a single subtree of dentries for unmount | |
790 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
791 | * locking | |
792 | */ | |
793 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
794 | { | |
795 | struct dentry *parent; | |
f8713576 | 796 | unsigned detached = 0; |
c636ebdb DH |
797 | |
798 | BUG_ON(!IS_ROOT(dentry)); | |
799 | ||
800 | /* detach this root from the system */ | |
801 | spin_lock(&dcache_lock); | |
23044507 | 802 | spin_lock(&dentry->d_lock); |
a4633357 | 803 | dentry_lru_del(dentry); |
23044507 | 804 | spin_unlock(&dentry->d_lock); |
c636ebdb DH |
805 | __d_drop(dentry); |
806 | spin_unlock(&dcache_lock); | |
807 | ||
808 | for (;;) { | |
809 | /* descend to the first leaf in the current subtree */ | |
810 | while (!list_empty(&dentry->d_subdirs)) { | |
811 | struct dentry *loop; | |
812 | ||
813 | /* this is a branch with children - detach all of them | |
814 | * from the system in one go */ | |
815 | spin_lock(&dcache_lock); | |
816 | list_for_each_entry(loop, &dentry->d_subdirs, | |
817 | d_u.d_child) { | |
23044507 | 818 | spin_lock(&loop->d_lock); |
a4633357 | 819 | dentry_lru_del(loop); |
23044507 | 820 | spin_unlock(&loop->d_lock); |
c636ebdb DH |
821 | __d_drop(loop); |
822 | cond_resched_lock(&dcache_lock); | |
823 | } | |
824 | spin_unlock(&dcache_lock); | |
825 | ||
826 | /* move to the first child */ | |
827 | dentry = list_entry(dentry->d_subdirs.next, | |
828 | struct dentry, d_u.d_child); | |
829 | } | |
830 | ||
831 | /* consume the dentries from this leaf up through its parents | |
832 | * until we find one with children or run out altogether */ | |
833 | do { | |
834 | struct inode *inode; | |
835 | ||
b7ab39f6 | 836 | if (dentry->d_count != 0) { |
c636ebdb DH |
837 | printk(KERN_ERR |
838 | "BUG: Dentry %p{i=%lx,n=%s}" | |
839 | " still in use (%d)" | |
840 | " [unmount of %s %s]\n", | |
841 | dentry, | |
842 | dentry->d_inode ? | |
843 | dentry->d_inode->i_ino : 0UL, | |
844 | dentry->d_name.name, | |
b7ab39f6 | 845 | dentry->d_count, |
c636ebdb DH |
846 | dentry->d_sb->s_type->name, |
847 | dentry->d_sb->s_id); | |
848 | BUG(); | |
849 | } | |
850 | ||
871c0067 | 851 | if (IS_ROOT(dentry)) |
c636ebdb | 852 | parent = NULL; |
871c0067 OH |
853 | else { |
854 | parent = dentry->d_parent; | |
b7ab39f6 NP |
855 | spin_lock(&parent->d_lock); |
856 | parent->d_count--; | |
857 | spin_unlock(&parent->d_lock); | |
871c0067 | 858 | } |
c636ebdb DH |
859 | |
860 | list_del(&dentry->d_u.d_child); | |
f8713576 | 861 | detached++; |
c636ebdb DH |
862 | |
863 | inode = dentry->d_inode; | |
864 | if (inode) { | |
865 | dentry->d_inode = NULL; | |
866 | list_del_init(&dentry->d_alias); | |
867 | if (dentry->d_op && dentry->d_op->d_iput) | |
868 | dentry->d_op->d_iput(dentry, inode); | |
869 | else | |
870 | iput(inode); | |
871 | } | |
872 | ||
873 | d_free(dentry); | |
874 | ||
875 | /* finished when we fall off the top of the tree, | |
876 | * otherwise we ascend to the parent and move to the | |
877 | * next sibling if there is one */ | |
878 | if (!parent) | |
312d3ca8 | 879 | return; |
c636ebdb | 880 | dentry = parent; |
c636ebdb DH |
881 | } while (list_empty(&dentry->d_subdirs)); |
882 | ||
883 | dentry = list_entry(dentry->d_subdirs.next, | |
884 | struct dentry, d_u.d_child); | |
885 | } | |
886 | } | |
887 | ||
888 | /* | |
889 | * destroy the dentries attached to a superblock on unmounting | |
890 | * - we don't need to use dentry->d_lock, and only need dcache_lock when | |
891 | * removing the dentry from the system lists and hashes because: | |
892 | * - the superblock is detached from all mountings and open files, so the | |
893 | * dentry trees will not be rearranged by the VFS | |
894 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
895 | * any dentries belonging to this superblock that it comes across | |
896 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
897 | * in this superblock | |
898 | */ | |
899 | void shrink_dcache_for_umount(struct super_block *sb) | |
900 | { | |
901 | struct dentry *dentry; | |
902 | ||
903 | if (down_read_trylock(&sb->s_umount)) | |
904 | BUG(); | |
905 | ||
906 | dentry = sb->s_root; | |
907 | sb->s_root = NULL; | |
b7ab39f6 NP |
908 | spin_lock(&dentry->d_lock); |
909 | dentry->d_count--; | |
910 | spin_unlock(&dentry->d_lock); | |
c636ebdb DH |
911 | shrink_dcache_for_umount_subtree(dentry); |
912 | ||
913 | while (!hlist_empty(&sb->s_anon)) { | |
914 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); | |
915 | shrink_dcache_for_umount_subtree(dentry); | |
916 | } | |
917 | } | |
918 | ||
1da177e4 LT |
919 | /* |
920 | * Search for at least 1 mount point in the dentry's subdirs. | |
921 | * We descend to the next level whenever the d_subdirs | |
922 | * list is non-empty and continue searching. | |
923 | */ | |
924 | ||
925 | /** | |
926 | * have_submounts - check for mounts over a dentry | |
927 | * @parent: dentry to check. | |
928 | * | |
929 | * Return true if the parent or its subdirectories contain | |
930 | * a mount point | |
931 | */ | |
932 | ||
933 | int have_submounts(struct dentry *parent) | |
934 | { | |
935 | struct dentry *this_parent = parent; | |
936 | struct list_head *next; | |
937 | ||
938 | spin_lock(&dcache_lock); | |
939 | if (d_mountpoint(parent)) | |
940 | goto positive; | |
941 | repeat: | |
942 | next = this_parent->d_subdirs.next; | |
943 | resume: | |
944 | while (next != &this_parent->d_subdirs) { | |
945 | struct list_head *tmp = next; | |
5160ee6f | 946 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
947 | next = tmp->next; |
948 | /* Have we found a mount point ? */ | |
949 | if (d_mountpoint(dentry)) | |
950 | goto positive; | |
951 | if (!list_empty(&dentry->d_subdirs)) { | |
952 | this_parent = dentry; | |
953 | goto repeat; | |
954 | } | |
955 | } | |
956 | /* | |
957 | * All done at this level ... ascend and resume the search. | |
958 | */ | |
959 | if (this_parent != parent) { | |
5160ee6f | 960 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
961 | this_parent = this_parent->d_parent; |
962 | goto resume; | |
963 | } | |
964 | spin_unlock(&dcache_lock); | |
965 | return 0; /* No mount points found in tree */ | |
966 | positive: | |
967 | spin_unlock(&dcache_lock); | |
968 | return 1; | |
969 | } | |
ec4f8605 | 970 | EXPORT_SYMBOL(have_submounts); |
1da177e4 LT |
971 | |
972 | /* | |
973 | * Search the dentry child list for the specified parent, | |
974 | * and move any unused dentries to the end of the unused | |
975 | * list for prune_dcache(). We descend to the next level | |
976 | * whenever the d_subdirs list is non-empty and continue | |
977 | * searching. | |
978 | * | |
979 | * It returns zero iff there are no unused children, | |
980 | * otherwise it returns the number of children moved to | |
981 | * the end of the unused list. This may not be the total | |
982 | * number of unused children, because select_parent can | |
983 | * drop the lock and return early due to latency | |
984 | * constraints. | |
985 | */ | |
986 | static int select_parent(struct dentry * parent) | |
987 | { | |
988 | struct dentry *this_parent = parent; | |
989 | struct list_head *next; | |
990 | int found = 0; | |
991 | ||
992 | spin_lock(&dcache_lock); | |
993 | repeat: | |
994 | next = this_parent->d_subdirs.next; | |
995 | resume: | |
996 | while (next != &this_parent->d_subdirs) { | |
997 | struct list_head *tmp = next; | |
5160ee6f | 998 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
999 | next = tmp->next; |
1000 | ||
23044507 NP |
1001 | spin_lock(&dentry->d_lock); |
1002 | ||
1da177e4 LT |
1003 | /* |
1004 | * move only zero ref count dentries to the end | |
1005 | * of the unused list for prune_dcache | |
1006 | */ | |
b7ab39f6 | 1007 | if (!dentry->d_count) { |
a4633357 | 1008 | dentry_lru_move_tail(dentry); |
1da177e4 | 1009 | found++; |
a4633357 CH |
1010 | } else { |
1011 | dentry_lru_del(dentry); | |
1da177e4 LT |
1012 | } |
1013 | ||
23044507 NP |
1014 | spin_unlock(&dentry->d_lock); |
1015 | ||
1da177e4 LT |
1016 | /* |
1017 | * We can return to the caller if we have found some (this | |
1018 | * ensures forward progress). We'll be coming back to find | |
1019 | * the rest. | |
1020 | */ | |
1021 | if (found && need_resched()) | |
1022 | goto out; | |
1023 | ||
1024 | /* | |
1025 | * Descend a level if the d_subdirs list is non-empty. | |
1026 | */ | |
1027 | if (!list_empty(&dentry->d_subdirs)) { | |
1028 | this_parent = dentry; | |
1da177e4 LT |
1029 | goto repeat; |
1030 | } | |
1031 | } | |
1032 | /* | |
1033 | * All done at this level ... ascend and resume the search. | |
1034 | */ | |
1035 | if (this_parent != parent) { | |
5160ee6f | 1036 | next = this_parent->d_u.d_child.next; |
1da177e4 | 1037 | this_parent = this_parent->d_parent; |
1da177e4 LT |
1038 | goto resume; |
1039 | } | |
1040 | out: | |
1041 | spin_unlock(&dcache_lock); | |
1042 | return found; | |
1043 | } | |
1044 | ||
1045 | /** | |
1046 | * shrink_dcache_parent - prune dcache | |
1047 | * @parent: parent of entries to prune | |
1048 | * | |
1049 | * Prune the dcache to remove unused children of the parent dentry. | |
1050 | */ | |
1051 | ||
1052 | void shrink_dcache_parent(struct dentry * parent) | |
1053 | { | |
da3bbdd4 | 1054 | struct super_block *sb = parent->d_sb; |
1da177e4 LT |
1055 | int found; |
1056 | ||
1057 | while ((found = select_parent(parent)) != 0) | |
da3bbdd4 | 1058 | __shrink_dcache_sb(sb, &found, 0); |
1da177e4 | 1059 | } |
ec4f8605 | 1060 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1061 | |
1da177e4 LT |
1062 | /* |
1063 | * Scan `nr' dentries and return the number which remain. | |
1064 | * | |
1065 | * We need to avoid reentering the filesystem if the caller is performing a | |
1066 | * GFP_NOFS allocation attempt. One example deadlock is: | |
1067 | * | |
1068 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> | |
1069 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> | |
1070 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. | |
1071 | * | |
1072 | * In this case we return -1 to tell the caller that we baled. | |
1073 | */ | |
7f8275d0 | 1074 | static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask) |
1da177e4 LT |
1075 | { |
1076 | if (nr) { | |
1077 | if (!(gfp_mask & __GFP_FS)) | |
1078 | return -1; | |
da3bbdd4 | 1079 | prune_dcache(nr); |
1da177e4 | 1080 | } |
312d3ca8 | 1081 | |
86c8749e | 1082 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; |
1da177e4 LT |
1083 | } |
1084 | ||
8e1f936b RR |
1085 | static struct shrinker dcache_shrinker = { |
1086 | .shrink = shrink_dcache_memory, | |
1087 | .seeks = DEFAULT_SEEKS, | |
1088 | }; | |
1089 | ||
1da177e4 LT |
1090 | /** |
1091 | * d_alloc - allocate a dcache entry | |
1092 | * @parent: parent of entry to allocate | |
1093 | * @name: qstr of the name | |
1094 | * | |
1095 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1096 | * available. On a success the dentry is returned. The name passed in is | |
1097 | * copied and the copy passed in may be reused after this call. | |
1098 | */ | |
1099 | ||
1100 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1101 | { | |
1102 | struct dentry *dentry; | |
1103 | char *dname; | |
1104 | ||
e12ba74d | 1105 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1106 | if (!dentry) |
1107 | return NULL; | |
1108 | ||
1109 | if (name->len > DNAME_INLINE_LEN-1) { | |
1110 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
1111 | if (!dname) { | |
1112 | kmem_cache_free(dentry_cache, dentry); | |
1113 | return NULL; | |
1114 | } | |
1115 | } else { | |
1116 | dname = dentry->d_iname; | |
1117 | } | |
1118 | dentry->d_name.name = dname; | |
1119 | ||
1120 | dentry->d_name.len = name->len; | |
1121 | dentry->d_name.hash = name->hash; | |
1122 | memcpy(dname, name->name, name->len); | |
1123 | dname[name->len] = 0; | |
1124 | ||
b7ab39f6 | 1125 | dentry->d_count = 1; |
1da177e4 LT |
1126 | dentry->d_flags = DCACHE_UNHASHED; |
1127 | spin_lock_init(&dentry->d_lock); | |
1128 | dentry->d_inode = NULL; | |
1129 | dentry->d_parent = NULL; | |
1130 | dentry->d_sb = NULL; | |
1131 | dentry->d_op = NULL; | |
1132 | dentry->d_fsdata = NULL; | |
1133 | dentry->d_mounted = 0; | |
1da177e4 LT |
1134 | INIT_HLIST_NODE(&dentry->d_hash); |
1135 | INIT_LIST_HEAD(&dentry->d_lru); | |
1136 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
1137 | INIT_LIST_HEAD(&dentry->d_alias); | |
1138 | ||
1139 | if (parent) { | |
1140 | dentry->d_parent = dget(parent); | |
1141 | dentry->d_sb = parent->d_sb; | |
1142 | } else { | |
5160ee6f | 1143 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1da177e4 LT |
1144 | } |
1145 | ||
1146 | spin_lock(&dcache_lock); | |
1147 | if (parent) | |
5160ee6f | 1148 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1da177e4 LT |
1149 | spin_unlock(&dcache_lock); |
1150 | ||
3e880fb5 | 1151 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1152 | |
1da177e4 LT |
1153 | return dentry; |
1154 | } | |
ec4f8605 | 1155 | EXPORT_SYMBOL(d_alloc); |
1da177e4 LT |
1156 | |
1157 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) | |
1158 | { | |
1159 | struct qstr q; | |
1160 | ||
1161 | q.name = name; | |
1162 | q.len = strlen(name); | |
1163 | q.hash = full_name_hash(q.name, q.len); | |
1164 | return d_alloc(parent, &q); | |
1165 | } | |
ef26ca97 | 1166 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1167 | |
360da900 OH |
1168 | /* the caller must hold dcache_lock */ |
1169 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) | |
1170 | { | |
1171 | if (inode) | |
1172 | list_add(&dentry->d_alias, &inode->i_dentry); | |
1173 | dentry->d_inode = inode; | |
1174 | fsnotify_d_instantiate(dentry, inode); | |
1175 | } | |
1176 | ||
1da177e4 LT |
1177 | /** |
1178 | * d_instantiate - fill in inode information for a dentry | |
1179 | * @entry: dentry to complete | |
1180 | * @inode: inode to attach to this dentry | |
1181 | * | |
1182 | * Fill in inode information in the entry. | |
1183 | * | |
1184 | * This turns negative dentries into productive full members | |
1185 | * of society. | |
1186 | * | |
1187 | * NOTE! This assumes that the inode count has been incremented | |
1188 | * (or otherwise set) by the caller to indicate that it is now | |
1189 | * in use by the dcache. | |
1190 | */ | |
1191 | ||
1192 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1193 | { | |
28133c7b | 1194 | BUG_ON(!list_empty(&entry->d_alias)); |
1da177e4 | 1195 | spin_lock(&dcache_lock); |
360da900 | 1196 | __d_instantiate(entry, inode); |
1da177e4 LT |
1197 | spin_unlock(&dcache_lock); |
1198 | security_d_instantiate(entry, inode); | |
1199 | } | |
ec4f8605 | 1200 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 LT |
1201 | |
1202 | /** | |
1203 | * d_instantiate_unique - instantiate a non-aliased dentry | |
1204 | * @entry: dentry to instantiate | |
1205 | * @inode: inode to attach to this dentry | |
1206 | * | |
1207 | * Fill in inode information in the entry. On success, it returns NULL. | |
1208 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 1209 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1210 | * |
1211 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1212 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1213 | * |
1214 | * This also assumes that the inode count has been incremented | |
1215 | * (or otherwise set) by the caller to indicate that it is now | |
1216 | * in use by the dcache. | |
1da177e4 | 1217 | */ |
770bfad8 DH |
1218 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1219 | struct inode *inode) | |
1da177e4 LT |
1220 | { |
1221 | struct dentry *alias; | |
1222 | int len = entry->d_name.len; | |
1223 | const char *name = entry->d_name.name; | |
1224 | unsigned int hash = entry->d_name.hash; | |
1225 | ||
770bfad8 | 1226 | if (!inode) { |
360da900 | 1227 | __d_instantiate(entry, NULL); |
770bfad8 DH |
1228 | return NULL; |
1229 | } | |
1230 | ||
1da177e4 LT |
1231 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1232 | struct qstr *qstr = &alias->d_name; | |
1233 | ||
1234 | if (qstr->hash != hash) | |
1235 | continue; | |
1236 | if (alias->d_parent != entry->d_parent) | |
1237 | continue; | |
1238 | if (qstr->len != len) | |
1239 | continue; | |
1240 | if (memcmp(qstr->name, name, len)) | |
1241 | continue; | |
1242 | dget_locked(alias); | |
1da177e4 LT |
1243 | return alias; |
1244 | } | |
770bfad8 | 1245 | |
360da900 | 1246 | __d_instantiate(entry, inode); |
1da177e4 LT |
1247 | return NULL; |
1248 | } | |
770bfad8 DH |
1249 | |
1250 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1251 | { | |
1252 | struct dentry *result; | |
1253 | ||
1254 | BUG_ON(!list_empty(&entry->d_alias)); | |
1255 | ||
1256 | spin_lock(&dcache_lock); | |
1257 | result = __d_instantiate_unique(entry, inode); | |
1258 | spin_unlock(&dcache_lock); | |
1259 | ||
1260 | if (!result) { | |
1261 | security_d_instantiate(entry, inode); | |
1262 | return NULL; | |
1263 | } | |
1264 | ||
1265 | BUG_ON(!d_unhashed(result)); | |
1266 | iput(inode); | |
1267 | return result; | |
1268 | } | |
1269 | ||
1da177e4 LT |
1270 | EXPORT_SYMBOL(d_instantiate_unique); |
1271 | ||
1272 | /** | |
1273 | * d_alloc_root - allocate root dentry | |
1274 | * @root_inode: inode to allocate the root for | |
1275 | * | |
1276 | * Allocate a root ("/") dentry for the inode given. The inode is | |
1277 | * instantiated and returned. %NULL is returned if there is insufficient | |
1278 | * memory or the inode passed is %NULL. | |
1279 | */ | |
1280 | ||
1281 | struct dentry * d_alloc_root(struct inode * root_inode) | |
1282 | { | |
1283 | struct dentry *res = NULL; | |
1284 | ||
1285 | if (root_inode) { | |
1286 | static const struct qstr name = { .name = "/", .len = 1 }; | |
1287 | ||
1288 | res = d_alloc(NULL, &name); | |
1289 | if (res) { | |
1290 | res->d_sb = root_inode->i_sb; | |
1291 | res->d_parent = res; | |
1292 | d_instantiate(res, root_inode); | |
1293 | } | |
1294 | } | |
1295 | return res; | |
1296 | } | |
ec4f8605 | 1297 | EXPORT_SYMBOL(d_alloc_root); |
1da177e4 LT |
1298 | |
1299 | static inline struct hlist_head *d_hash(struct dentry *parent, | |
1300 | unsigned long hash) | |
1301 | { | |
1302 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; | |
1303 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); | |
1304 | return dentry_hashtable + (hash & D_HASHMASK); | |
1305 | } | |
1306 | ||
4ea3ada2 CH |
1307 | /** |
1308 | * d_obtain_alias - find or allocate a dentry for a given inode | |
1309 | * @inode: inode to allocate the dentry for | |
1310 | * | |
1311 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1312 | * similar open by handle operations. The returned dentry may be anonymous, | |
1313 | * or may have a full name (if the inode was already in the cache). | |
1314 | * | |
1315 | * When called on a directory inode, we must ensure that the inode only ever | |
1316 | * has one dentry. If a dentry is found, that is returned instead of | |
1317 | * allocating a new one. | |
1318 | * | |
1319 | * On successful return, the reference to the inode has been transferred | |
44003728 CH |
1320 | * to the dentry. In case of an error the reference on the inode is released. |
1321 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1322 | * be passed in and will be the error will be propagate to the return value, | |
1323 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
4ea3ada2 CH |
1324 | */ |
1325 | struct dentry *d_obtain_alias(struct inode *inode) | |
1326 | { | |
9308a612 CH |
1327 | static const struct qstr anonstring = { .name = "" }; |
1328 | struct dentry *tmp; | |
1329 | struct dentry *res; | |
4ea3ada2 CH |
1330 | |
1331 | if (!inode) | |
44003728 | 1332 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1333 | if (IS_ERR(inode)) |
1334 | return ERR_CAST(inode); | |
1335 | ||
9308a612 CH |
1336 | res = d_find_alias(inode); |
1337 | if (res) | |
1338 | goto out_iput; | |
1339 | ||
1340 | tmp = d_alloc(NULL, &anonstring); | |
1341 | if (!tmp) { | |
1342 | res = ERR_PTR(-ENOMEM); | |
1343 | goto out_iput; | |
4ea3ada2 | 1344 | } |
9308a612 CH |
1345 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
1346 | ||
1347 | spin_lock(&dcache_lock); | |
1348 | res = __d_find_alias(inode, 0); | |
1349 | if (res) { | |
1350 | spin_unlock(&dcache_lock); | |
1351 | dput(tmp); | |
1352 | goto out_iput; | |
1353 | } | |
1354 | ||
1355 | /* attach a disconnected dentry */ | |
1356 | spin_lock(&tmp->d_lock); | |
1357 | tmp->d_sb = inode->i_sb; | |
1358 | tmp->d_inode = inode; | |
1359 | tmp->d_flags |= DCACHE_DISCONNECTED; | |
1360 | tmp->d_flags &= ~DCACHE_UNHASHED; | |
1361 | list_add(&tmp->d_alias, &inode->i_dentry); | |
789680d1 | 1362 | spin_lock(&dcache_hash_lock); |
9308a612 | 1363 | hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon); |
789680d1 | 1364 | spin_unlock(&dcache_hash_lock); |
9308a612 CH |
1365 | spin_unlock(&tmp->d_lock); |
1366 | ||
1367 | spin_unlock(&dcache_lock); | |
1368 | return tmp; | |
1369 | ||
1370 | out_iput: | |
1371 | iput(inode); | |
1372 | return res; | |
4ea3ada2 | 1373 | } |
adc48720 | 1374 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 LT |
1375 | |
1376 | /** | |
1377 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1378 | * @inode: the inode which may have a disconnected dentry | |
1379 | * @dentry: a negative dentry which we want to point to the inode. | |
1380 | * | |
1381 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1382 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1383 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1384 | * | |
1385 | * This is needed in the lookup routine of any filesystem that is exportable | |
1386 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1387 | * | |
1388 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1389 | * is returned. This matches the expected return value of ->lookup. | |
1390 | * | |
1391 | */ | |
1392 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1393 | { | |
1394 | struct dentry *new = NULL; | |
1395 | ||
21c0d8fd | 1396 | if (inode && S_ISDIR(inode->i_mode)) { |
1da177e4 LT |
1397 | spin_lock(&dcache_lock); |
1398 | new = __d_find_alias(inode, 1); | |
1399 | if (new) { | |
1400 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); | |
1401 | spin_unlock(&dcache_lock); | |
1402 | security_d_instantiate(new, inode); | |
1da177e4 LT |
1403 | d_move(new, dentry); |
1404 | iput(inode); | |
1405 | } else { | |
360da900 OH |
1406 | /* already taking dcache_lock, so d_add() by hand */ |
1407 | __d_instantiate(dentry, inode); | |
1da177e4 LT |
1408 | spin_unlock(&dcache_lock); |
1409 | security_d_instantiate(dentry, inode); | |
1410 | d_rehash(dentry); | |
1411 | } | |
1412 | } else | |
1413 | d_add(dentry, inode); | |
1414 | return new; | |
1415 | } | |
ec4f8605 | 1416 | EXPORT_SYMBOL(d_splice_alias); |
1da177e4 | 1417 | |
9403540c BN |
1418 | /** |
1419 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
1420 | * @inode: the inode case-insensitive lookup has found | |
1421 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
1422 | * @name: the case-exact name to be associated with the returned dentry | |
1423 | * | |
1424 | * This is to avoid filling the dcache with case-insensitive names to the | |
1425 | * same inode, only the actual correct case is stored in the dcache for | |
1426 | * case-insensitive filesystems. | |
1427 | * | |
1428 | * For a case-insensitive lookup match and if the the case-exact dentry | |
1429 | * already exists in in the dcache, use it and return it. | |
1430 | * | |
1431 | * If no entry exists with the exact case name, allocate new dentry with | |
1432 | * the exact case, and return the spliced entry. | |
1433 | */ | |
e45b590b | 1434 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
1435 | struct qstr *name) |
1436 | { | |
1437 | int error; | |
1438 | struct dentry *found; | |
1439 | struct dentry *new; | |
1440 | ||
b6520c81 CH |
1441 | /* |
1442 | * First check if a dentry matching the name already exists, | |
1443 | * if not go ahead and create it now. | |
1444 | */ | |
9403540c | 1445 | found = d_hash_and_lookup(dentry->d_parent, name); |
9403540c BN |
1446 | if (!found) { |
1447 | new = d_alloc(dentry->d_parent, name); | |
1448 | if (!new) { | |
1449 | error = -ENOMEM; | |
1450 | goto err_out; | |
1451 | } | |
b6520c81 | 1452 | |
9403540c BN |
1453 | found = d_splice_alias(inode, new); |
1454 | if (found) { | |
1455 | dput(new); | |
1456 | return found; | |
1457 | } | |
1458 | return new; | |
1459 | } | |
b6520c81 CH |
1460 | |
1461 | /* | |
1462 | * If a matching dentry exists, and it's not negative use it. | |
1463 | * | |
1464 | * Decrement the reference count to balance the iget() done | |
1465 | * earlier on. | |
1466 | */ | |
9403540c BN |
1467 | if (found->d_inode) { |
1468 | if (unlikely(found->d_inode != inode)) { | |
1469 | /* This can't happen because bad inodes are unhashed. */ | |
1470 | BUG_ON(!is_bad_inode(inode)); | |
1471 | BUG_ON(!is_bad_inode(found->d_inode)); | |
1472 | } | |
9403540c BN |
1473 | iput(inode); |
1474 | return found; | |
1475 | } | |
b6520c81 | 1476 | |
9403540c BN |
1477 | /* |
1478 | * Negative dentry: instantiate it unless the inode is a directory and | |
b6520c81 | 1479 | * already has a dentry. |
9403540c | 1480 | */ |
9403540c | 1481 | spin_lock(&dcache_lock); |
b6520c81 | 1482 | if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) { |
360da900 | 1483 | __d_instantiate(found, inode); |
9403540c BN |
1484 | spin_unlock(&dcache_lock); |
1485 | security_d_instantiate(found, inode); | |
1486 | return found; | |
1487 | } | |
b6520c81 | 1488 | |
9403540c | 1489 | /* |
b6520c81 CH |
1490 | * In case a directory already has a (disconnected) entry grab a |
1491 | * reference to it, move it in place and use it. | |
9403540c BN |
1492 | */ |
1493 | new = list_entry(inode->i_dentry.next, struct dentry, d_alias); | |
1494 | dget_locked(new); | |
1495 | spin_unlock(&dcache_lock); | |
9403540c | 1496 | security_d_instantiate(found, inode); |
9403540c | 1497 | d_move(new, found); |
9403540c | 1498 | iput(inode); |
9403540c | 1499 | dput(found); |
9403540c BN |
1500 | return new; |
1501 | ||
1502 | err_out: | |
1503 | iput(inode); | |
1504 | return ERR_PTR(error); | |
1505 | } | |
ec4f8605 | 1506 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 LT |
1507 | |
1508 | /** | |
1509 | * d_lookup - search for a dentry | |
1510 | * @parent: parent dentry | |
1511 | * @name: qstr of name we wish to find | |
b04f784e | 1512 | * Returns: dentry, or NULL |
1da177e4 | 1513 | * |
b04f784e NP |
1514 | * d_lookup searches the children of the parent dentry for the name in |
1515 | * question. If the dentry is found its reference count is incremented and the | |
1516 | * dentry is returned. The caller must use dput to free the entry when it has | |
1517 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 1518 | */ |
1da177e4 LT |
1519 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
1520 | { | |
1521 | struct dentry * dentry = NULL; | |
1522 | unsigned long seq; | |
1523 | ||
1524 | do { | |
1525 | seq = read_seqbegin(&rename_lock); | |
1526 | dentry = __d_lookup(parent, name); | |
1527 | if (dentry) | |
1528 | break; | |
1529 | } while (read_seqretry(&rename_lock, seq)); | |
1530 | return dentry; | |
1531 | } | |
ec4f8605 | 1532 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 1533 | |
b04f784e NP |
1534 | /* |
1535 | * __d_lookup - search for a dentry (racy) | |
1536 | * @parent: parent dentry | |
1537 | * @name: qstr of name we wish to find | |
1538 | * Returns: dentry, or NULL | |
1539 | * | |
1540 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
1541 | * false-negative result due to unrelated rename activity. | |
1542 | * | |
1543 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
1544 | * however it must be used carefully, eg. with a following d_lookup in | |
1545 | * the case of failure. | |
1546 | * | |
1547 | * __d_lookup callers must be commented. | |
1548 | */ | |
1da177e4 LT |
1549 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) |
1550 | { | |
1551 | unsigned int len = name->len; | |
1552 | unsigned int hash = name->hash; | |
1553 | const unsigned char *str = name->name; | |
1554 | struct hlist_head *head = d_hash(parent,hash); | |
1555 | struct dentry *found = NULL; | |
1556 | struct hlist_node *node; | |
665a7583 | 1557 | struct dentry *dentry; |
1da177e4 | 1558 | |
b04f784e NP |
1559 | /* |
1560 | * The hash list is protected using RCU. | |
1561 | * | |
1562 | * Take d_lock when comparing a candidate dentry, to avoid races | |
1563 | * with d_move(). | |
1564 | * | |
1565 | * It is possible that concurrent renames can mess up our list | |
1566 | * walk here and result in missing our dentry, resulting in the | |
1567 | * false-negative result. d_lookup() protects against concurrent | |
1568 | * renames using rename_lock seqlock. | |
1569 | * | |
1570 | * See Documentation/vfs/dcache-locking.txt for more details. | |
1571 | */ | |
1da177e4 LT |
1572 | rcu_read_lock(); |
1573 | ||
665a7583 | 1574 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
1da177e4 LT |
1575 | struct qstr *qstr; |
1576 | ||
1da177e4 LT |
1577 | if (dentry->d_name.hash != hash) |
1578 | continue; | |
1579 | if (dentry->d_parent != parent) | |
1580 | continue; | |
1581 | ||
1582 | spin_lock(&dentry->d_lock); | |
1583 | ||
1584 | /* | |
1585 | * Recheck the dentry after taking the lock - d_move may have | |
b04f784e NP |
1586 | * changed things. Don't bother checking the hash because |
1587 | * we're about to compare the whole name anyway. | |
1da177e4 LT |
1588 | */ |
1589 | if (dentry->d_parent != parent) | |
1590 | goto next; | |
1591 | ||
d0185c08 LT |
1592 | /* non-existing due to RCU? */ |
1593 | if (d_unhashed(dentry)) | |
1594 | goto next; | |
1595 | ||
1da177e4 LT |
1596 | /* |
1597 | * It is safe to compare names since d_move() cannot | |
1598 | * change the qstr (protected by d_lock). | |
1599 | */ | |
1600 | qstr = &dentry->d_name; | |
1601 | if (parent->d_op && parent->d_op->d_compare) { | |
621e155a NP |
1602 | if (parent->d_op->d_compare(parent, parent->d_inode, |
1603 | dentry, dentry->d_inode, | |
1604 | qstr->len, qstr->name, name)) | |
1da177e4 LT |
1605 | goto next; |
1606 | } else { | |
1607 | if (qstr->len != len) | |
1608 | goto next; | |
1609 | if (memcmp(qstr->name, str, len)) | |
1610 | goto next; | |
1611 | } | |
1612 | ||
b7ab39f6 | 1613 | dentry->d_count++; |
d0185c08 | 1614 | found = dentry; |
1da177e4 LT |
1615 | spin_unlock(&dentry->d_lock); |
1616 | break; | |
1617 | next: | |
1618 | spin_unlock(&dentry->d_lock); | |
1619 | } | |
1620 | rcu_read_unlock(); | |
1621 | ||
1622 | return found; | |
1623 | } | |
1624 | ||
3e7e241f EB |
1625 | /** |
1626 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
1627 | * @dir: Directory to search in | |
1628 | * @name: qstr of name we wish to find | |
1629 | * | |
1630 | * On hash failure or on lookup failure NULL is returned. | |
1631 | */ | |
1632 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
1633 | { | |
1634 | struct dentry *dentry = NULL; | |
1635 | ||
1636 | /* | |
1637 | * Check for a fs-specific hash function. Note that we must | |
1638 | * calculate the standard hash first, as the d_op->d_hash() | |
1639 | * routine may choose to leave the hash value unchanged. | |
1640 | */ | |
1641 | name->hash = full_name_hash(name->name, name->len); | |
1642 | if (dir->d_op && dir->d_op->d_hash) { | |
b1e6a015 | 1643 | if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) |
3e7e241f EB |
1644 | goto out; |
1645 | } | |
1646 | dentry = d_lookup(dir, name); | |
1647 | out: | |
1648 | return dentry; | |
1649 | } | |
1650 | ||
1da177e4 | 1651 | /** |
786a5e15 | 1652 | * d_validate - verify dentry provided from insecure source (deprecated) |
1da177e4 LT |
1653 | * @dentry: The dentry alleged to be valid child of @dparent |
1654 | * @dparent: The parent dentry (known to be valid) | |
1da177e4 LT |
1655 | * |
1656 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
1657 | * This is used by ncpfs in its readdir implementation. | |
1658 | * Zero is returned in the dentry is invalid. | |
786a5e15 NP |
1659 | * |
1660 | * This function is slow for big directories, and deprecated, do not use it. | |
1da177e4 | 1661 | */ |
d3a23e16 | 1662 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
1da177e4 | 1663 | { |
786a5e15 | 1664 | struct dentry *child; |
d3a23e16 NP |
1665 | |
1666 | spin_lock(&dcache_lock); | |
786a5e15 NP |
1667 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
1668 | if (dentry == child) { | |
d3a23e16 NP |
1669 | __dget_locked(dentry); |
1670 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
1671 | return 1; |
1672 | } | |
1673 | } | |
d3a23e16 | 1674 | spin_unlock(&dcache_lock); |
786a5e15 | 1675 | |
1da177e4 LT |
1676 | return 0; |
1677 | } | |
ec4f8605 | 1678 | EXPORT_SYMBOL(d_validate); |
1da177e4 LT |
1679 | |
1680 | /* | |
1681 | * When a file is deleted, we have two options: | |
1682 | * - turn this dentry into a negative dentry | |
1683 | * - unhash this dentry and free it. | |
1684 | * | |
1685 | * Usually, we want to just turn this into | |
1686 | * a negative dentry, but if anybody else is | |
1687 | * currently using the dentry or the inode | |
1688 | * we can't do that and we fall back on removing | |
1689 | * it from the hash queues and waiting for | |
1690 | * it to be deleted later when it has no users | |
1691 | */ | |
1692 | ||
1693 | /** | |
1694 | * d_delete - delete a dentry | |
1695 | * @dentry: The dentry to delete | |
1696 | * | |
1697 | * Turn the dentry into a negative dentry if possible, otherwise | |
1698 | * remove it from the hash queues so it can be deleted later | |
1699 | */ | |
1700 | ||
1701 | void d_delete(struct dentry * dentry) | |
1702 | { | |
7a91bf7f | 1703 | int isdir = 0; |
1da177e4 LT |
1704 | /* |
1705 | * Are we the only user? | |
1706 | */ | |
1707 | spin_lock(&dcache_lock); | |
1708 | spin_lock(&dentry->d_lock); | |
7a91bf7f | 1709 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
b7ab39f6 | 1710 | if (dentry->d_count == 1) { |
13e3c5e5 | 1711 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
1da177e4 | 1712 | dentry_iput(dentry); |
7a91bf7f | 1713 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
1714 | return; |
1715 | } | |
1716 | ||
1717 | if (!d_unhashed(dentry)) | |
1718 | __d_drop(dentry); | |
1719 | ||
1720 | spin_unlock(&dentry->d_lock); | |
1721 | spin_unlock(&dcache_lock); | |
7a91bf7f JM |
1722 | |
1723 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 1724 | } |
ec4f8605 | 1725 | EXPORT_SYMBOL(d_delete); |
1da177e4 LT |
1726 | |
1727 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) | |
1728 | { | |
1729 | ||
1730 | entry->d_flags &= ~DCACHE_UNHASHED; | |
1731 | hlist_add_head_rcu(&entry->d_hash, list); | |
1732 | } | |
1733 | ||
770bfad8 DH |
1734 | static void _d_rehash(struct dentry * entry) |
1735 | { | |
1736 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
1737 | } | |
1738 | ||
1da177e4 LT |
1739 | /** |
1740 | * d_rehash - add an entry back to the hash | |
1741 | * @entry: dentry to add to the hash | |
1742 | * | |
1743 | * Adds a dentry to the hash according to its name. | |
1744 | */ | |
1745 | ||
1746 | void d_rehash(struct dentry * entry) | |
1747 | { | |
1da177e4 LT |
1748 | spin_lock(&dcache_lock); |
1749 | spin_lock(&entry->d_lock); | |
789680d1 | 1750 | spin_lock(&dcache_hash_lock); |
770bfad8 | 1751 | _d_rehash(entry); |
789680d1 | 1752 | spin_unlock(&dcache_hash_lock); |
1da177e4 LT |
1753 | spin_unlock(&entry->d_lock); |
1754 | spin_unlock(&dcache_lock); | |
1755 | } | |
ec4f8605 | 1756 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 1757 | |
fb2d5b86 NP |
1758 | /** |
1759 | * dentry_update_name_case - update case insensitive dentry with a new name | |
1760 | * @dentry: dentry to be updated | |
1761 | * @name: new name | |
1762 | * | |
1763 | * Update a case insensitive dentry with new case of name. | |
1764 | * | |
1765 | * dentry must have been returned by d_lookup with name @name. Old and new | |
1766 | * name lengths must match (ie. no d_compare which allows mismatched name | |
1767 | * lengths). | |
1768 | * | |
1769 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
1770 | * keep renames and concurrent inserts, and readdir(2) away). | |
1771 | */ | |
1772 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
1773 | { | |
1774 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
1775 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ | |
1776 | ||
1777 | spin_lock(&dcache_lock); | |
1778 | spin_lock(&dentry->d_lock); | |
1779 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); | |
1780 | spin_unlock(&dentry->d_lock); | |
1781 | spin_unlock(&dcache_lock); | |
1782 | } | |
1783 | EXPORT_SYMBOL(dentry_update_name_case); | |
1784 | ||
1da177e4 LT |
1785 | /* |
1786 | * When switching names, the actual string doesn't strictly have to | |
1787 | * be preserved in the target - because we're dropping the target | |
1788 | * anyway. As such, we can just do a simple memcpy() to copy over | |
1789 | * the new name before we switch. | |
1790 | * | |
1791 | * Note that we have to be a lot more careful about getting the hash | |
1792 | * switched - we have to switch the hash value properly even if it | |
1793 | * then no longer matches the actual (corrupted) string of the target. | |
1794 | * The hash value has to match the hash queue that the dentry is on.. | |
1795 | */ | |
1796 | static void switch_names(struct dentry *dentry, struct dentry *target) | |
1797 | { | |
1798 | if (dname_external(target)) { | |
1799 | if (dname_external(dentry)) { | |
1800 | /* | |
1801 | * Both external: swap the pointers | |
1802 | */ | |
9a8d5bb4 | 1803 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
1804 | } else { |
1805 | /* | |
1806 | * dentry:internal, target:external. Steal target's | |
1807 | * storage and make target internal. | |
1808 | */ | |
321bcf92 BF |
1809 | memcpy(target->d_iname, dentry->d_name.name, |
1810 | dentry->d_name.len + 1); | |
1da177e4 LT |
1811 | dentry->d_name.name = target->d_name.name; |
1812 | target->d_name.name = target->d_iname; | |
1813 | } | |
1814 | } else { | |
1815 | if (dname_external(dentry)) { | |
1816 | /* | |
1817 | * dentry:external, target:internal. Give dentry's | |
1818 | * storage to target and make dentry internal | |
1819 | */ | |
1820 | memcpy(dentry->d_iname, target->d_name.name, | |
1821 | target->d_name.len + 1); | |
1822 | target->d_name.name = dentry->d_name.name; | |
1823 | dentry->d_name.name = dentry->d_iname; | |
1824 | } else { | |
1825 | /* | |
1826 | * Both are internal. Just copy target to dentry | |
1827 | */ | |
1828 | memcpy(dentry->d_iname, target->d_name.name, | |
1829 | target->d_name.len + 1); | |
dc711ca3 AV |
1830 | dentry->d_name.len = target->d_name.len; |
1831 | return; | |
1da177e4 LT |
1832 | } |
1833 | } | |
9a8d5bb4 | 1834 | swap(dentry->d_name.len, target->d_name.len); |
1da177e4 LT |
1835 | } |
1836 | ||
1837 | /* | |
1838 | * We cannibalize "target" when moving dentry on top of it, | |
1839 | * because it's going to be thrown away anyway. We could be more | |
1840 | * polite about it, though. | |
1841 | * | |
1842 | * This forceful removal will result in ugly /proc output if | |
1843 | * somebody holds a file open that got deleted due to a rename. | |
1844 | * We could be nicer about the deleted file, and let it show | |
bc154b1e BF |
1845 | * up under the name it had before it was deleted rather than |
1846 | * under the original name of the file that was moved on top of it. | |
1da177e4 LT |
1847 | */ |
1848 | ||
9eaef27b TM |
1849 | /* |
1850 | * d_move_locked - move a dentry | |
1da177e4 LT |
1851 | * @dentry: entry to move |
1852 | * @target: new dentry | |
1853 | * | |
1854 | * Update the dcache to reflect the move of a file name. Negative | |
1855 | * dcache entries should not be moved in this way. | |
1856 | */ | |
9eaef27b | 1857 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
1da177e4 | 1858 | { |
1da177e4 LT |
1859 | if (!dentry->d_inode) |
1860 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
1861 | ||
1da177e4 LT |
1862 | write_seqlock(&rename_lock); |
1863 | /* | |
1864 | * XXXX: do we really need to take target->d_lock? | |
1865 | */ | |
1866 | if (target < dentry) { | |
1867 | spin_lock(&target->d_lock); | |
a90b9c05 | 1868 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1869 | } else { |
1870 | spin_lock(&dentry->d_lock); | |
a90b9c05 | 1871 | spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1872 | } |
1873 | ||
1874 | /* Move the dentry to the target hash queue, if on different bucket */ | |
789680d1 NP |
1875 | spin_lock(&dcache_hash_lock); |
1876 | if (!d_unhashed(dentry)) | |
1877 | hlist_del_rcu(&dentry->d_hash); | |
1878 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); | |
1879 | spin_unlock(&dcache_hash_lock); | |
1da177e4 LT |
1880 | |
1881 | /* Unhash the target: dput() will then get rid of it */ | |
1882 | __d_drop(target); | |
1883 | ||
5160ee6f ED |
1884 | list_del(&dentry->d_u.d_child); |
1885 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
1886 | |
1887 | /* Switch the names.. */ | |
1888 | switch_names(dentry, target); | |
9a8d5bb4 | 1889 | swap(dentry->d_name.hash, target->d_name.hash); |
1da177e4 LT |
1890 | |
1891 | /* ... and switch the parents */ | |
1892 | if (IS_ROOT(dentry)) { | |
1893 | dentry->d_parent = target->d_parent; | |
1894 | target->d_parent = target; | |
5160ee6f | 1895 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 | 1896 | } else { |
9a8d5bb4 | 1897 | swap(dentry->d_parent, target->d_parent); |
1da177e4 LT |
1898 | |
1899 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 1900 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
1901 | } |
1902 | ||
5160ee6f | 1903 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
1da177e4 | 1904 | spin_unlock(&target->d_lock); |
c32ccd87 | 1905 | fsnotify_d_move(dentry); |
1da177e4 LT |
1906 | spin_unlock(&dentry->d_lock); |
1907 | write_sequnlock(&rename_lock); | |
9eaef27b TM |
1908 | } |
1909 | ||
1910 | /** | |
1911 | * d_move - move a dentry | |
1912 | * @dentry: entry to move | |
1913 | * @target: new dentry | |
1914 | * | |
1915 | * Update the dcache to reflect the move of a file name. Negative | |
1916 | * dcache entries should not be moved in this way. | |
1917 | */ | |
1918 | ||
1919 | void d_move(struct dentry * dentry, struct dentry * target) | |
1920 | { | |
1921 | spin_lock(&dcache_lock); | |
1922 | d_move_locked(dentry, target); | |
1da177e4 LT |
1923 | spin_unlock(&dcache_lock); |
1924 | } | |
ec4f8605 | 1925 | EXPORT_SYMBOL(d_move); |
1da177e4 | 1926 | |
e2761a11 OH |
1927 | /** |
1928 | * d_ancestor - search for an ancestor | |
1929 | * @p1: ancestor dentry | |
1930 | * @p2: child dentry | |
1931 | * | |
1932 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
1933 | * an ancestor of p2, else NULL. | |
9eaef27b | 1934 | */ |
e2761a11 | 1935 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
1936 | { |
1937 | struct dentry *p; | |
1938 | ||
871c0067 | 1939 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 1940 | if (p->d_parent == p1) |
e2761a11 | 1941 | return p; |
9eaef27b | 1942 | } |
e2761a11 | 1943 | return NULL; |
9eaef27b TM |
1944 | } |
1945 | ||
1946 | /* | |
1947 | * This helper attempts to cope with remotely renamed directories | |
1948 | * | |
1949 | * It assumes that the caller is already holding | |
1950 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock | |
1951 | * | |
1952 | * Note: If ever the locking in lock_rename() changes, then please | |
1953 | * remember to update this too... | |
9eaef27b TM |
1954 | */ |
1955 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) | |
31f3e0b3 | 1956 | __releases(dcache_lock) |
9eaef27b TM |
1957 | { |
1958 | struct mutex *m1 = NULL, *m2 = NULL; | |
1959 | struct dentry *ret; | |
1960 | ||
1961 | /* If alias and dentry share a parent, then no extra locks required */ | |
1962 | if (alias->d_parent == dentry->d_parent) | |
1963 | goto out_unalias; | |
1964 | ||
1965 | /* Check for loops */ | |
1966 | ret = ERR_PTR(-ELOOP); | |
e2761a11 | 1967 | if (d_ancestor(alias, dentry)) |
9eaef27b TM |
1968 | goto out_err; |
1969 | ||
1970 | /* See lock_rename() */ | |
1971 | ret = ERR_PTR(-EBUSY); | |
1972 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) | |
1973 | goto out_err; | |
1974 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
1975 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
1976 | goto out_err; | |
1977 | m2 = &alias->d_parent->d_inode->i_mutex; | |
1978 | out_unalias: | |
1979 | d_move_locked(alias, dentry); | |
1980 | ret = alias; | |
1981 | out_err: | |
1982 | spin_unlock(&dcache_lock); | |
1983 | if (m2) | |
1984 | mutex_unlock(m2); | |
1985 | if (m1) | |
1986 | mutex_unlock(m1); | |
1987 | return ret; | |
1988 | } | |
1989 | ||
770bfad8 DH |
1990 | /* |
1991 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
1992 | * named dentry in place of the dentry to be replaced. | |
1993 | */ | |
1994 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
1995 | { | |
1996 | struct dentry *dparent, *aparent; | |
1997 | ||
1998 | switch_names(dentry, anon); | |
9a8d5bb4 | 1999 | swap(dentry->d_name.hash, anon->d_name.hash); |
770bfad8 DH |
2000 | |
2001 | dparent = dentry->d_parent; | |
2002 | aparent = anon->d_parent; | |
2003 | ||
2004 | dentry->d_parent = (aparent == anon) ? dentry : aparent; | |
2005 | list_del(&dentry->d_u.d_child); | |
2006 | if (!IS_ROOT(dentry)) | |
2007 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); | |
2008 | else | |
2009 | INIT_LIST_HEAD(&dentry->d_u.d_child); | |
2010 | ||
2011 | anon->d_parent = (dparent == dentry) ? anon : dparent; | |
2012 | list_del(&anon->d_u.d_child); | |
2013 | if (!IS_ROOT(anon)) | |
2014 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); | |
2015 | else | |
2016 | INIT_LIST_HEAD(&anon->d_u.d_child); | |
2017 | ||
2018 | anon->d_flags &= ~DCACHE_DISCONNECTED; | |
2019 | } | |
2020 | ||
2021 | /** | |
2022 | * d_materialise_unique - introduce an inode into the tree | |
2023 | * @dentry: candidate dentry | |
2024 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
2025 | * | |
2026 | * Introduces an dentry into the tree, substituting an extant disconnected | |
2027 | * root directory alias in its place if there is one | |
2028 | */ | |
2029 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
2030 | { | |
9eaef27b | 2031 | struct dentry *actual; |
770bfad8 DH |
2032 | |
2033 | BUG_ON(!d_unhashed(dentry)); | |
2034 | ||
2035 | spin_lock(&dcache_lock); | |
2036 | ||
2037 | if (!inode) { | |
2038 | actual = dentry; | |
360da900 | 2039 | __d_instantiate(dentry, NULL); |
770bfad8 DH |
2040 | goto found_lock; |
2041 | } | |
2042 | ||
9eaef27b TM |
2043 | if (S_ISDIR(inode->i_mode)) { |
2044 | struct dentry *alias; | |
2045 | ||
2046 | /* Does an aliased dentry already exist? */ | |
2047 | alias = __d_find_alias(inode, 0); | |
2048 | if (alias) { | |
2049 | actual = alias; | |
2050 | /* Is this an anonymous mountpoint that we could splice | |
2051 | * into our tree? */ | |
2052 | if (IS_ROOT(alias)) { | |
2053 | spin_lock(&alias->d_lock); | |
2054 | __d_materialise_dentry(dentry, alias); | |
2055 | __d_drop(alias); | |
2056 | goto found; | |
2057 | } | |
2058 | /* Nope, but we must(!) avoid directory aliasing */ | |
2059 | actual = __d_unalias(dentry, alias); | |
2060 | if (IS_ERR(actual)) | |
2061 | dput(alias); | |
2062 | goto out_nolock; | |
2063 | } | |
770bfad8 DH |
2064 | } |
2065 | ||
2066 | /* Add a unique reference */ | |
2067 | actual = __d_instantiate_unique(dentry, inode); | |
2068 | if (!actual) | |
2069 | actual = dentry; | |
2070 | else if (unlikely(!d_unhashed(actual))) | |
2071 | goto shouldnt_be_hashed; | |
2072 | ||
2073 | found_lock: | |
2074 | spin_lock(&actual->d_lock); | |
2075 | found: | |
789680d1 | 2076 | spin_lock(&dcache_hash_lock); |
770bfad8 | 2077 | _d_rehash(actual); |
789680d1 | 2078 | spin_unlock(&dcache_hash_lock); |
770bfad8 DH |
2079 | spin_unlock(&actual->d_lock); |
2080 | spin_unlock(&dcache_lock); | |
9eaef27b | 2081 | out_nolock: |
770bfad8 DH |
2082 | if (actual == dentry) { |
2083 | security_d_instantiate(dentry, inode); | |
2084 | return NULL; | |
2085 | } | |
2086 | ||
2087 | iput(inode); | |
2088 | return actual; | |
2089 | ||
770bfad8 DH |
2090 | shouldnt_be_hashed: |
2091 | spin_unlock(&dcache_lock); | |
2092 | BUG(); | |
770bfad8 | 2093 | } |
ec4f8605 | 2094 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
770bfad8 | 2095 | |
cdd16d02 | 2096 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
2097 | { |
2098 | *buflen -= namelen; | |
2099 | if (*buflen < 0) | |
2100 | return -ENAMETOOLONG; | |
2101 | *buffer -= namelen; | |
2102 | memcpy(*buffer, str, namelen); | |
2103 | return 0; | |
2104 | } | |
2105 | ||
cdd16d02 MS |
2106 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2107 | { | |
2108 | return prepend(buffer, buflen, name->name, name->len); | |
2109 | } | |
2110 | ||
1da177e4 | 2111 | /** |
f2eb6575 MS |
2112 | * Prepend path string to a buffer |
2113 | * | |
9d1bc601 MS |
2114 | * @path: the dentry/vfsmount to report |
2115 | * @root: root vfsmnt/dentry (may be modified by this function) | |
f2eb6575 MS |
2116 | * @buffer: pointer to the end of the buffer |
2117 | * @buflen: pointer to buffer length | |
552ce544 | 2118 | * |
f2eb6575 | 2119 | * Caller holds the dcache_lock. |
9d1bc601 MS |
2120 | * |
2121 | * If path is not reachable from the supplied root, then the value of | |
2122 | * root is changed (without modifying refcounts). | |
1da177e4 | 2123 | */ |
f2eb6575 MS |
2124 | static int prepend_path(const struct path *path, struct path *root, |
2125 | char **buffer, int *buflen) | |
1da177e4 | 2126 | { |
9d1bc601 MS |
2127 | struct dentry *dentry = path->dentry; |
2128 | struct vfsmount *vfsmnt = path->mnt; | |
f2eb6575 MS |
2129 | bool slash = false; |
2130 | int error = 0; | |
6092d048 | 2131 | |
99b7db7b | 2132 | br_read_lock(vfsmount_lock); |
f2eb6575 | 2133 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
2134 | struct dentry * parent; |
2135 | ||
1da177e4 | 2136 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 2137 | /* Global root? */ |
1da177e4 | 2138 | if (vfsmnt->mnt_parent == vfsmnt) { |
1da177e4 LT |
2139 | goto global_root; |
2140 | } | |
2141 | dentry = vfsmnt->mnt_mountpoint; | |
2142 | vfsmnt = vfsmnt->mnt_parent; | |
1da177e4 LT |
2143 | continue; |
2144 | } | |
2145 | parent = dentry->d_parent; | |
2146 | prefetch(parent); | |
f2eb6575 MS |
2147 | error = prepend_name(buffer, buflen, &dentry->d_name); |
2148 | if (!error) | |
2149 | error = prepend(buffer, buflen, "/", 1); | |
2150 | if (error) | |
2151 | break; | |
2152 | ||
2153 | slash = true; | |
1da177e4 LT |
2154 | dentry = parent; |
2155 | } | |
2156 | ||
be285c71 | 2157 | out: |
f2eb6575 MS |
2158 | if (!error && !slash) |
2159 | error = prepend(buffer, buflen, "/", 1); | |
2160 | ||
99b7db7b | 2161 | br_read_unlock(vfsmount_lock); |
f2eb6575 | 2162 | return error; |
1da177e4 LT |
2163 | |
2164 | global_root: | |
98dc568b MS |
2165 | /* |
2166 | * Filesystems needing to implement special "root names" | |
2167 | * should do so with ->d_dname() | |
2168 | */ | |
2169 | if (IS_ROOT(dentry) && | |
2170 | (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { | |
2171 | WARN(1, "Root dentry has weird name <%.*s>\n", | |
2172 | (int) dentry->d_name.len, dentry->d_name.name); | |
2173 | } | |
9d1bc601 MS |
2174 | root->mnt = vfsmnt; |
2175 | root->dentry = dentry; | |
be285c71 | 2176 | goto out; |
f2eb6575 | 2177 | } |
be285c71 | 2178 | |
f2eb6575 MS |
2179 | /** |
2180 | * __d_path - return the path of a dentry | |
2181 | * @path: the dentry/vfsmount to report | |
2182 | * @root: root vfsmnt/dentry (may be modified by this function) | |
cd956a1c | 2183 | * @buf: buffer to return value in |
f2eb6575 MS |
2184 | * @buflen: buffer length |
2185 | * | |
ffd1f4ed | 2186 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
2187 | * |
2188 | * Returns a pointer into the buffer or an error code if the | |
2189 | * path was too long. | |
2190 | * | |
be148247 | 2191 | * "buflen" should be positive. |
f2eb6575 MS |
2192 | * |
2193 | * If path is not reachable from the supplied root, then the value of | |
2194 | * root is changed (without modifying refcounts). | |
2195 | */ | |
2196 | char *__d_path(const struct path *path, struct path *root, | |
2197 | char *buf, int buflen) | |
2198 | { | |
2199 | char *res = buf + buflen; | |
2200 | int error; | |
2201 | ||
2202 | prepend(&res, &buflen, "\0", 1); | |
be148247 | 2203 | spin_lock(&dcache_lock); |
f2eb6575 | 2204 | error = prepend_path(path, root, &res, &buflen); |
be148247 CH |
2205 | spin_unlock(&dcache_lock); |
2206 | ||
f2eb6575 MS |
2207 | if (error) |
2208 | return ERR_PTR(error); | |
f2eb6575 | 2209 | return res; |
1da177e4 LT |
2210 | } |
2211 | ||
ffd1f4ed MS |
2212 | /* |
2213 | * same as __d_path but appends "(deleted)" for unlinked files. | |
2214 | */ | |
2215 | static int path_with_deleted(const struct path *path, struct path *root, | |
2216 | char **buf, int *buflen) | |
2217 | { | |
2218 | prepend(buf, buflen, "\0", 1); | |
2219 | if (d_unlinked(path->dentry)) { | |
2220 | int error = prepend(buf, buflen, " (deleted)", 10); | |
2221 | if (error) | |
2222 | return error; | |
2223 | } | |
2224 | ||
2225 | return prepend_path(path, root, buf, buflen); | |
2226 | } | |
2227 | ||
8df9d1a4 MS |
2228 | static int prepend_unreachable(char **buffer, int *buflen) |
2229 | { | |
2230 | return prepend(buffer, buflen, "(unreachable)", 13); | |
2231 | } | |
2232 | ||
a03a8a70 JB |
2233 | /** |
2234 | * d_path - return the path of a dentry | |
cf28b486 | 2235 | * @path: path to report |
a03a8a70 JB |
2236 | * @buf: buffer to return value in |
2237 | * @buflen: buffer length | |
2238 | * | |
2239 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
2240 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
2241 | * | |
52afeefb AV |
2242 | * Returns a pointer into the buffer or an error code if the path was |
2243 | * too long. Note: Callers should use the returned pointer, not the passed | |
2244 | * in buffer, to use the name! The implementation often starts at an offset | |
2245 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 2246 | * |
31f3e0b3 | 2247 | * "buflen" should be positive. |
a03a8a70 | 2248 | */ |
20d4fdc1 | 2249 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 2250 | { |
ffd1f4ed | 2251 | char *res = buf + buflen; |
6ac08c39 | 2252 | struct path root; |
9d1bc601 | 2253 | struct path tmp; |
ffd1f4ed | 2254 | int error; |
1da177e4 | 2255 | |
c23fbb6b ED |
2256 | /* |
2257 | * We have various synthetic filesystems that never get mounted. On | |
2258 | * these filesystems dentries are never used for lookup purposes, and | |
2259 | * thus don't need to be hashed. They also don't need a name until a | |
2260 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
2261 | * below allows us to generate a name for these objects on demand: | |
2262 | */ | |
cf28b486 JB |
2263 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2264 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
c23fbb6b | 2265 | |
f7ad3c6b | 2266 | get_fs_root(current->fs, &root); |
552ce544 | 2267 | spin_lock(&dcache_lock); |
9d1bc601 | 2268 | tmp = root; |
ffd1f4ed MS |
2269 | error = path_with_deleted(path, &tmp, &res, &buflen); |
2270 | if (error) | |
2271 | res = ERR_PTR(error); | |
552ce544 | 2272 | spin_unlock(&dcache_lock); |
6ac08c39 | 2273 | path_put(&root); |
1da177e4 LT |
2274 | return res; |
2275 | } | |
ec4f8605 | 2276 | EXPORT_SYMBOL(d_path); |
1da177e4 | 2277 | |
8df9d1a4 MS |
2278 | /** |
2279 | * d_path_with_unreachable - return the path of a dentry | |
2280 | * @path: path to report | |
2281 | * @buf: buffer to return value in | |
2282 | * @buflen: buffer length | |
2283 | * | |
2284 | * The difference from d_path() is that this prepends "(unreachable)" | |
2285 | * to paths which are unreachable from the current process' root. | |
2286 | */ | |
2287 | char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) | |
2288 | { | |
2289 | char *res = buf + buflen; | |
2290 | struct path root; | |
2291 | struct path tmp; | |
2292 | int error; | |
2293 | ||
2294 | if (path->dentry->d_op && path->dentry->d_op->d_dname) | |
2295 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
2296 | ||
2297 | get_fs_root(current->fs, &root); | |
2298 | spin_lock(&dcache_lock); | |
2299 | tmp = root; | |
2300 | error = path_with_deleted(path, &tmp, &res, &buflen); | |
2301 | if (!error && !path_equal(&tmp, &root)) | |
2302 | error = prepend_unreachable(&res, &buflen); | |
2303 | spin_unlock(&dcache_lock); | |
2304 | path_put(&root); | |
2305 | if (error) | |
2306 | res = ERR_PTR(error); | |
2307 | ||
2308 | return res; | |
2309 | } | |
2310 | ||
c23fbb6b ED |
2311 | /* |
2312 | * Helper function for dentry_operations.d_dname() members | |
2313 | */ | |
2314 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
2315 | const char *fmt, ...) | |
2316 | { | |
2317 | va_list args; | |
2318 | char temp[64]; | |
2319 | int sz; | |
2320 | ||
2321 | va_start(args, fmt); | |
2322 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
2323 | va_end(args); | |
2324 | ||
2325 | if (sz > sizeof(temp) || sz > buflen) | |
2326 | return ERR_PTR(-ENAMETOOLONG); | |
2327 | ||
2328 | buffer += buflen - sz; | |
2329 | return memcpy(buffer, temp, sz); | |
2330 | } | |
2331 | ||
6092d048 RP |
2332 | /* |
2333 | * Write full pathname from the root of the filesystem into the buffer. | |
2334 | */ | |
ec2447c2 | 2335 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
6092d048 RP |
2336 | { |
2337 | char *end = buf + buflen; | |
2338 | char *retval; | |
2339 | ||
6092d048 | 2340 | prepend(&end, &buflen, "\0", 1); |
6092d048 RP |
2341 | if (buflen < 1) |
2342 | goto Elong; | |
2343 | /* Get '/' right */ | |
2344 | retval = end-1; | |
2345 | *retval = '/'; | |
2346 | ||
cdd16d02 MS |
2347 | while (!IS_ROOT(dentry)) { |
2348 | struct dentry *parent = dentry->d_parent; | |
6092d048 | 2349 | |
6092d048 | 2350 | prefetch(parent); |
cdd16d02 | 2351 | if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || |
6092d048 RP |
2352 | (prepend(&end, &buflen, "/", 1) != 0)) |
2353 | goto Elong; | |
2354 | ||
2355 | retval = end; | |
2356 | dentry = parent; | |
2357 | } | |
c103135c AV |
2358 | return retval; |
2359 | Elong: | |
2360 | return ERR_PTR(-ENAMETOOLONG); | |
2361 | } | |
ec2447c2 NP |
2362 | |
2363 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
2364 | { | |
2365 | char *retval; | |
2366 | ||
2367 | spin_lock(&dcache_lock); | |
2368 | retval = __dentry_path(dentry, buf, buflen); | |
2369 | spin_unlock(&dcache_lock); | |
2370 | ||
2371 | return retval; | |
2372 | } | |
2373 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
2374 | |
2375 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
2376 | { | |
2377 | char *p = NULL; | |
2378 | char *retval; | |
2379 | ||
2380 | spin_lock(&dcache_lock); | |
2381 | if (d_unlinked(dentry)) { | |
2382 | p = buf + buflen; | |
2383 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
2384 | goto Elong; | |
2385 | buflen++; | |
2386 | } | |
2387 | retval = __dentry_path(dentry, buf, buflen); | |
6092d048 | 2388 | spin_unlock(&dcache_lock); |
c103135c AV |
2389 | if (!IS_ERR(retval) && p) |
2390 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
2391 | return retval; |
2392 | Elong: | |
2393 | spin_unlock(&dcache_lock); | |
2394 | return ERR_PTR(-ENAMETOOLONG); | |
2395 | } | |
2396 | ||
1da177e4 LT |
2397 | /* |
2398 | * NOTE! The user-level library version returns a | |
2399 | * character pointer. The kernel system call just | |
2400 | * returns the length of the buffer filled (which | |
2401 | * includes the ending '\0' character), or a negative | |
2402 | * error value. So libc would do something like | |
2403 | * | |
2404 | * char *getcwd(char * buf, size_t size) | |
2405 | * { | |
2406 | * int retval; | |
2407 | * | |
2408 | * retval = sys_getcwd(buf, size); | |
2409 | * if (retval >= 0) | |
2410 | * return buf; | |
2411 | * errno = -retval; | |
2412 | * return NULL; | |
2413 | * } | |
2414 | */ | |
3cdad428 | 2415 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 2416 | { |
552ce544 | 2417 | int error; |
6ac08c39 | 2418 | struct path pwd, root; |
552ce544 | 2419 | char *page = (char *) __get_free_page(GFP_USER); |
1da177e4 LT |
2420 | |
2421 | if (!page) | |
2422 | return -ENOMEM; | |
2423 | ||
f7ad3c6b | 2424 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
1da177e4 | 2425 | |
552ce544 | 2426 | error = -ENOENT; |
552ce544 | 2427 | spin_lock(&dcache_lock); |
f3da392e | 2428 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 2429 | unsigned long len; |
9d1bc601 | 2430 | struct path tmp = root; |
8df9d1a4 MS |
2431 | char *cwd = page + PAGE_SIZE; |
2432 | int buflen = PAGE_SIZE; | |
1da177e4 | 2433 | |
8df9d1a4 MS |
2434 | prepend(&cwd, &buflen, "\0", 1); |
2435 | error = prepend_path(&pwd, &tmp, &cwd, &buflen); | |
552ce544 LT |
2436 | spin_unlock(&dcache_lock); |
2437 | ||
8df9d1a4 | 2438 | if (error) |
552ce544 LT |
2439 | goto out; |
2440 | ||
8df9d1a4 MS |
2441 | /* Unreachable from current root */ |
2442 | if (!path_equal(&tmp, &root)) { | |
2443 | error = prepend_unreachable(&cwd, &buflen); | |
2444 | if (error) | |
2445 | goto out; | |
2446 | } | |
2447 | ||
552ce544 LT |
2448 | error = -ERANGE; |
2449 | len = PAGE_SIZE + page - cwd; | |
2450 | if (len <= size) { | |
2451 | error = len; | |
2452 | if (copy_to_user(buf, cwd, len)) | |
2453 | error = -EFAULT; | |
2454 | } | |
2455 | } else | |
2456 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
2457 | |
2458 | out: | |
6ac08c39 JB |
2459 | path_put(&pwd); |
2460 | path_put(&root); | |
1da177e4 LT |
2461 | free_page((unsigned long) page); |
2462 | return error; | |
2463 | } | |
2464 | ||
2465 | /* | |
2466 | * Test whether new_dentry is a subdirectory of old_dentry. | |
2467 | * | |
2468 | * Trivially implemented using the dcache structure | |
2469 | */ | |
2470 | ||
2471 | /** | |
2472 | * is_subdir - is new dentry a subdirectory of old_dentry | |
2473 | * @new_dentry: new dentry | |
2474 | * @old_dentry: old dentry | |
2475 | * | |
2476 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
2477 | * Returns 0 otherwise. | |
2478 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
2479 | */ | |
2480 | ||
e2761a11 | 2481 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 LT |
2482 | { |
2483 | int result; | |
1da177e4 LT |
2484 | unsigned long seq; |
2485 | ||
e2761a11 OH |
2486 | if (new_dentry == old_dentry) |
2487 | return 1; | |
2488 | ||
2489 | /* | |
2490 | * Need rcu_readlock to protect against the d_parent trashing | |
2491 | * due to d_move | |
1da177e4 LT |
2492 | */ |
2493 | rcu_read_lock(); | |
e2761a11 | 2494 | do { |
1da177e4 | 2495 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 2496 | seq = read_seqbegin(&rename_lock); |
e2761a11 | 2497 | if (d_ancestor(old_dentry, new_dentry)) |
1da177e4 | 2498 | result = 1; |
e2761a11 OH |
2499 | else |
2500 | result = 0; | |
1da177e4 LT |
2501 | } while (read_seqretry(&rename_lock, seq)); |
2502 | rcu_read_unlock(); | |
2503 | ||
2504 | return result; | |
2505 | } | |
2506 | ||
2096f759 AV |
2507 | int path_is_under(struct path *path1, struct path *path2) |
2508 | { | |
2509 | struct vfsmount *mnt = path1->mnt; | |
2510 | struct dentry *dentry = path1->dentry; | |
2511 | int res; | |
99b7db7b NP |
2512 | |
2513 | br_read_lock(vfsmount_lock); | |
2096f759 AV |
2514 | if (mnt != path2->mnt) { |
2515 | for (;;) { | |
2516 | if (mnt->mnt_parent == mnt) { | |
99b7db7b | 2517 | br_read_unlock(vfsmount_lock); |
2096f759 AV |
2518 | return 0; |
2519 | } | |
2520 | if (mnt->mnt_parent == path2->mnt) | |
2521 | break; | |
2522 | mnt = mnt->mnt_parent; | |
2523 | } | |
2524 | dentry = mnt->mnt_mountpoint; | |
2525 | } | |
2526 | res = is_subdir(dentry, path2->dentry); | |
99b7db7b | 2527 | br_read_unlock(vfsmount_lock); |
2096f759 AV |
2528 | return res; |
2529 | } | |
2530 | EXPORT_SYMBOL(path_is_under); | |
2531 | ||
1da177e4 LT |
2532 | void d_genocide(struct dentry *root) |
2533 | { | |
2534 | struct dentry *this_parent = root; | |
2535 | struct list_head *next; | |
2536 | ||
2537 | spin_lock(&dcache_lock); | |
2538 | repeat: | |
2539 | next = this_parent->d_subdirs.next; | |
2540 | resume: | |
2541 | while (next != &this_parent->d_subdirs) { | |
2542 | struct list_head *tmp = next; | |
5160ee6f | 2543 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
2544 | next = tmp->next; |
2545 | if (d_unhashed(dentry)||!dentry->d_inode) | |
2546 | continue; | |
2547 | if (!list_empty(&dentry->d_subdirs)) { | |
2548 | this_parent = dentry; | |
2549 | goto repeat; | |
2550 | } | |
b7ab39f6 NP |
2551 | spin_lock(&dentry->d_lock); |
2552 | dentry->d_count--; | |
2553 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
2554 | } |
2555 | if (this_parent != root) { | |
5160ee6f | 2556 | next = this_parent->d_u.d_child.next; |
b7ab39f6 NP |
2557 | spin_lock(&this_parent->d_lock); |
2558 | this_parent->d_count--; | |
2559 | spin_unlock(&this_parent->d_lock); | |
1da177e4 LT |
2560 | this_parent = this_parent->d_parent; |
2561 | goto resume; | |
2562 | } | |
2563 | spin_unlock(&dcache_lock); | |
2564 | } | |
2565 | ||
2566 | /** | |
2567 | * find_inode_number - check for dentry with name | |
2568 | * @dir: directory to check | |
2569 | * @name: Name to find. | |
2570 | * | |
2571 | * Check whether a dentry already exists for the given name, | |
2572 | * and return the inode number if it has an inode. Otherwise | |
2573 | * 0 is returned. | |
2574 | * | |
2575 | * This routine is used to post-process directory listings for | |
2576 | * filesystems using synthetic inode numbers, and is necessary | |
2577 | * to keep getcwd() working. | |
2578 | */ | |
2579 | ||
2580 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) | |
2581 | { | |
2582 | struct dentry * dentry; | |
2583 | ino_t ino = 0; | |
2584 | ||
3e7e241f EB |
2585 | dentry = d_hash_and_lookup(dir, name); |
2586 | if (dentry) { | |
1da177e4 LT |
2587 | if (dentry->d_inode) |
2588 | ino = dentry->d_inode->i_ino; | |
2589 | dput(dentry); | |
2590 | } | |
1da177e4 LT |
2591 | return ino; |
2592 | } | |
ec4f8605 | 2593 | EXPORT_SYMBOL(find_inode_number); |
1da177e4 LT |
2594 | |
2595 | static __initdata unsigned long dhash_entries; | |
2596 | static int __init set_dhash_entries(char *str) | |
2597 | { | |
2598 | if (!str) | |
2599 | return 0; | |
2600 | dhash_entries = simple_strtoul(str, &str, 0); | |
2601 | return 1; | |
2602 | } | |
2603 | __setup("dhash_entries=", set_dhash_entries); | |
2604 | ||
2605 | static void __init dcache_init_early(void) | |
2606 | { | |
2607 | int loop; | |
2608 | ||
2609 | /* If hashes are distributed across NUMA nodes, defer | |
2610 | * hash allocation until vmalloc space is available. | |
2611 | */ | |
2612 | if (hashdist) | |
2613 | return; | |
2614 | ||
2615 | dentry_hashtable = | |
2616 | alloc_large_system_hash("Dentry cache", | |
2617 | sizeof(struct hlist_head), | |
2618 | dhash_entries, | |
2619 | 13, | |
2620 | HASH_EARLY, | |
2621 | &d_hash_shift, | |
2622 | &d_hash_mask, | |
2623 | 0); | |
2624 | ||
2625 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2626 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2627 | } | |
2628 | ||
74bf17cf | 2629 | static void __init dcache_init(void) |
1da177e4 LT |
2630 | { |
2631 | int loop; | |
2632 | ||
2633 | /* | |
2634 | * A constructor could be added for stable state like the lists, | |
2635 | * but it is probably not worth it because of the cache nature | |
2636 | * of the dcache. | |
2637 | */ | |
0a31bd5f CL |
2638 | dentry_cache = KMEM_CACHE(dentry, |
2639 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 | 2640 | |
8e1f936b | 2641 | register_shrinker(&dcache_shrinker); |
1da177e4 LT |
2642 | |
2643 | /* Hash may have been set up in dcache_init_early */ | |
2644 | if (!hashdist) | |
2645 | return; | |
2646 | ||
2647 | dentry_hashtable = | |
2648 | alloc_large_system_hash("Dentry cache", | |
2649 | sizeof(struct hlist_head), | |
2650 | dhash_entries, | |
2651 | 13, | |
2652 | 0, | |
2653 | &d_hash_shift, | |
2654 | &d_hash_mask, | |
2655 | 0); | |
2656 | ||
2657 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2658 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2659 | } | |
2660 | ||
2661 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 2662 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 2663 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 2664 | |
1da177e4 LT |
2665 | EXPORT_SYMBOL(d_genocide); |
2666 | ||
1da177e4 LT |
2667 | void __init vfs_caches_init_early(void) |
2668 | { | |
2669 | dcache_init_early(); | |
2670 | inode_init_early(); | |
2671 | } | |
2672 | ||
2673 | void __init vfs_caches_init(unsigned long mempages) | |
2674 | { | |
2675 | unsigned long reserve; | |
2676 | ||
2677 | /* Base hash sizes on available memory, with a reserve equal to | |
2678 | 150% of current kernel size */ | |
2679 | ||
2680 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
2681 | mempages -= reserve; | |
2682 | ||
2683 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 2684 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 2685 | |
74bf17cf DC |
2686 | dcache_init(); |
2687 | inode_init(); | |
1da177e4 | 2688 | files_init(mempages); |
74bf17cf | 2689 | mnt_init(); |
1da177e4 LT |
2690 | bdev_cache_init(); |
2691 | chrdev_init(); | |
2692 | } |