Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * fs/dcache.c | |
3 | * | |
4 | * Complete reimplementation | |
5 | * (C) 1997 Thomas Schoebel-Theuer, | |
6 | * with heavy changes by Linus Torvalds | |
7 | */ | |
8 | ||
9 | /* | |
10 | * Notes on the allocation strategy: | |
11 | * | |
12 | * The dcache is a master of the icache - whenever a dcache entry | |
13 | * exists, the inode will always exist. "iput()" is done either when | |
14 | * the dcache entry is deleted or garbage collected. | |
15 | */ | |
16 | ||
1da177e4 LT |
17 | #include <linux/syscalls.h> |
18 | #include <linux/string.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/fs.h> | |
7a91bf7f | 21 | #include <linux/fsnotify.h> |
1da177e4 LT |
22 | #include <linux/slab.h> |
23 | #include <linux/init.h> | |
1da177e4 LT |
24 | #include <linux/hash.h> |
25 | #include <linux/cache.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/file.h> | |
29 | #include <asm/uaccess.h> | |
30 | #include <linux/security.h> | |
31 | #include <linux/seqlock.h> | |
32 | #include <linux/swap.h> | |
33 | #include <linux/bootmem.h> | |
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 |
da502956 | 49 | * - d_unhashed() |
2fd6b7f5 NP |
50 | * - d_parent and d_subdirs |
51 | * - childrens' d_child and d_parent | |
789680d1 NP |
52 | * |
53 | * Ordering: | |
54 | * dcache_lock | |
55 | * dentry->d_lock | |
23044507 | 56 | * dcache_lru_lock |
789680d1 NP |
57 | * dcache_hash_lock |
58 | * | |
da502956 NP |
59 | * If there is an ancestor relationship: |
60 | * dentry->d_parent->...->d_parent->d_lock | |
61 | * ... | |
62 | * dentry->d_parent->d_lock | |
63 | * dentry->d_lock | |
64 | * | |
65 | * If no ancestor relationship: | |
789680d1 NP |
66 | * if (dentry1 < dentry2) |
67 | * dentry1->d_lock | |
68 | * dentry2->d_lock | |
69 | */ | |
fa3536cc | 70 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
71 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
72 | ||
789680d1 | 73 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_hash_lock); |
23044507 | 74 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock); |
789680d1 | 75 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); |
74c3cbe3 | 76 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 LT |
77 | |
78 | EXPORT_SYMBOL(dcache_lock); | |
79 | ||
e18b890b | 80 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 LT |
81 | |
82 | #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) | |
83 | ||
84 | /* | |
85 | * This is the single most critical data structure when it comes | |
86 | * to the dcache: the hashtable for lookups. Somebody should try | |
87 | * to make this good - I've just made it work. | |
88 | * | |
89 | * This hash-function tries to avoid losing too many bits of hash | |
90 | * information, yet avoid using a prime hash-size or similar. | |
91 | */ | |
92 | #define D_HASHBITS d_hash_shift | |
93 | #define D_HASHMASK d_hash_mask | |
94 | ||
fa3536cc ED |
95 | static unsigned int d_hash_mask __read_mostly; |
96 | static unsigned int d_hash_shift __read_mostly; | |
97 | static struct hlist_head *dentry_hashtable __read_mostly; | |
1da177e4 LT |
98 | |
99 | /* Statistics gathering. */ | |
100 | struct dentry_stat_t dentry_stat = { | |
101 | .age_limit = 45, | |
102 | }; | |
103 | ||
3e880fb5 | 104 | static DEFINE_PER_CPU(unsigned int, nr_dentry); |
312d3ca8 CH |
105 | |
106 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
3e880fb5 NP |
107 | static int get_nr_dentry(void) |
108 | { | |
109 | int i; | |
110 | int sum = 0; | |
111 | for_each_possible_cpu(i) | |
112 | sum += per_cpu(nr_dentry, i); | |
113 | return sum < 0 ? 0 : sum; | |
114 | } | |
115 | ||
312d3ca8 CH |
116 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
117 | size_t *lenp, loff_t *ppos) | |
118 | { | |
3e880fb5 | 119 | dentry_stat.nr_dentry = get_nr_dentry(); |
312d3ca8 CH |
120 | return proc_dointvec(table, write, buffer, lenp, ppos); |
121 | } | |
122 | #endif | |
123 | ||
9c82ab9c | 124 | static void __d_free(struct rcu_head *head) |
1da177e4 | 125 | { |
9c82ab9c CH |
126 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
127 | ||
fd217f4d | 128 | WARN_ON(!list_empty(&dentry->d_alias)); |
1da177e4 LT |
129 | if (dname_external(dentry)) |
130 | kfree(dentry->d_name.name); | |
131 | kmem_cache_free(dentry_cache, dentry); | |
132 | } | |
133 | ||
134 | /* | |
312d3ca8 | 135 | * no dcache_lock, please. |
1da177e4 LT |
136 | */ |
137 | static void d_free(struct dentry *dentry) | |
138 | { | |
b7ab39f6 | 139 | BUG_ON(dentry->d_count); |
3e880fb5 | 140 | this_cpu_dec(nr_dentry); |
1da177e4 LT |
141 | if (dentry->d_op && dentry->d_op->d_release) |
142 | dentry->d_op->d_release(dentry); | |
312d3ca8 | 143 | |
b3423415 | 144 | /* if dentry was never inserted into hash, immediate free is OK */ |
e8462caa | 145 | if (hlist_unhashed(&dentry->d_hash)) |
9c82ab9c | 146 | __d_free(&dentry->d_u.d_rcu); |
b3423415 | 147 | else |
9c82ab9c | 148 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
1da177e4 LT |
149 | } |
150 | ||
151 | /* | |
152 | * Release the dentry's inode, using the filesystem | |
153 | * d_iput() operation if defined. | |
1da177e4 | 154 | */ |
858119e1 | 155 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 MS |
156 | __releases(dentry->d_lock) |
157 | __releases(dcache_lock) | |
1da177e4 LT |
158 | { |
159 | struct inode *inode = dentry->d_inode; | |
160 | if (inode) { | |
161 | dentry->d_inode = NULL; | |
162 | list_del_init(&dentry->d_alias); | |
163 | spin_unlock(&dentry->d_lock); | |
164 | spin_unlock(&dcache_lock); | |
f805fbda LT |
165 | if (!inode->i_nlink) |
166 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
167 | if (dentry->d_op && dentry->d_op->d_iput) |
168 | dentry->d_op->d_iput(dentry, inode); | |
169 | else | |
170 | iput(inode); | |
171 | } else { | |
172 | spin_unlock(&dentry->d_lock); | |
173 | spin_unlock(&dcache_lock); | |
174 | } | |
175 | } | |
176 | ||
da3bbdd4 | 177 | /* |
23044507 | 178 | * dentry_lru_(add|del|move_tail) must be called with d_lock held. |
da3bbdd4 KM |
179 | */ |
180 | static void dentry_lru_add(struct dentry *dentry) | |
181 | { | |
a4633357 | 182 | if (list_empty(&dentry->d_lru)) { |
23044507 | 183 | spin_lock(&dcache_lru_lock); |
a4633357 CH |
184 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); |
185 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 186 | dentry_stat.nr_unused++; |
23044507 | 187 | spin_unlock(&dcache_lru_lock); |
a4633357 | 188 | } |
da3bbdd4 KM |
189 | } |
190 | ||
23044507 NP |
191 | static void __dentry_lru_del(struct dentry *dentry) |
192 | { | |
193 | list_del_init(&dentry->d_lru); | |
194 | dentry->d_sb->s_nr_dentry_unused--; | |
195 | dentry_stat.nr_unused--; | |
196 | } | |
197 | ||
da3bbdd4 KM |
198 | static void dentry_lru_del(struct dentry *dentry) |
199 | { | |
200 | if (!list_empty(&dentry->d_lru)) { | |
23044507 NP |
201 | spin_lock(&dcache_lru_lock); |
202 | __dentry_lru_del(dentry); | |
203 | spin_unlock(&dcache_lru_lock); | |
da3bbdd4 KM |
204 | } |
205 | } | |
206 | ||
a4633357 | 207 | static void dentry_lru_move_tail(struct dentry *dentry) |
da3bbdd4 | 208 | { |
23044507 | 209 | spin_lock(&dcache_lru_lock); |
a4633357 CH |
210 | if (list_empty(&dentry->d_lru)) { |
211 | list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
212 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 213 | dentry_stat.nr_unused++; |
a4633357 CH |
214 | } else { |
215 | list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
da3bbdd4 | 216 | } |
23044507 | 217 | spin_unlock(&dcache_lru_lock); |
da3bbdd4 KM |
218 | } |
219 | ||
d52b9086 MS |
220 | /** |
221 | * d_kill - kill dentry and return parent | |
222 | * @dentry: dentry to kill | |
223 | * | |
31f3e0b3 | 224 | * The dentry must already be unhashed and removed from the LRU. |
d52b9086 MS |
225 | * |
226 | * If this is the root of the dentry tree, return NULL. | |
23044507 | 227 | * |
2fd6b7f5 NP |
228 | * dcache_lock and d_lock and d_parent->d_lock must be held by caller, and |
229 | * are dropped by d_kill. | |
d52b9086 | 230 | */ |
2fd6b7f5 | 231 | static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent) |
31f3e0b3 | 232 | __releases(dentry->d_lock) |
2fd6b7f5 | 233 | __releases(parent->d_lock) |
31f3e0b3 | 234 | __releases(dcache_lock) |
d52b9086 | 235 | { |
d52b9086 | 236 | list_del(&dentry->d_u.d_child); |
2fd6b7f5 NP |
237 | if (parent) |
238 | spin_unlock(&parent->d_lock); | |
d52b9086 | 239 | dentry_iput(dentry); |
b7ab39f6 NP |
240 | /* |
241 | * dentry_iput drops the locks, at which point nobody (except | |
242 | * transient RCU lookups) can reach this dentry. | |
243 | */ | |
d52b9086 | 244 | d_free(dentry); |
871c0067 | 245 | return parent; |
d52b9086 MS |
246 | } |
247 | ||
789680d1 NP |
248 | /** |
249 | * d_drop - drop a dentry | |
250 | * @dentry: dentry to drop | |
251 | * | |
252 | * d_drop() unhashes the entry from the parent dentry hashes, so that it won't | |
253 | * be found through a VFS lookup any more. Note that this is different from | |
254 | * deleting the dentry - d_delete will try to mark the dentry negative if | |
255 | * possible, giving a successful _negative_ lookup, while d_drop will | |
256 | * just make the cache lookup fail. | |
257 | * | |
258 | * d_drop() is used mainly for stuff that wants to invalidate a dentry for some | |
259 | * reason (NFS timeouts or autofs deletes). | |
260 | * | |
261 | * __d_drop requires dentry->d_lock. | |
262 | */ | |
263 | void __d_drop(struct dentry *dentry) | |
264 | { | |
265 | if (!(dentry->d_flags & DCACHE_UNHASHED)) { | |
266 | dentry->d_flags |= DCACHE_UNHASHED; | |
267 | spin_lock(&dcache_hash_lock); | |
268 | hlist_del_rcu(&dentry->d_hash); | |
269 | spin_unlock(&dcache_hash_lock); | |
270 | } | |
271 | } | |
272 | EXPORT_SYMBOL(__d_drop); | |
273 | ||
274 | void d_drop(struct dentry *dentry) | |
275 | { | |
276 | spin_lock(&dcache_lock); | |
277 | spin_lock(&dentry->d_lock); | |
278 | __d_drop(dentry); | |
279 | spin_unlock(&dentry->d_lock); | |
280 | spin_unlock(&dcache_lock); | |
281 | } | |
282 | EXPORT_SYMBOL(d_drop); | |
283 | ||
1da177e4 LT |
284 | /* |
285 | * This is dput | |
286 | * | |
287 | * This is complicated by the fact that we do not want to put | |
288 | * dentries that are no longer on any hash chain on the unused | |
289 | * list: we'd much rather just get rid of them immediately. | |
290 | * | |
291 | * However, that implies that we have to traverse the dentry | |
292 | * tree upwards to the parents which might _also_ now be | |
293 | * scheduled for deletion (it may have been only waiting for | |
294 | * its last child to go away). | |
295 | * | |
296 | * This tail recursion is done by hand as we don't want to depend | |
297 | * on the compiler to always get this right (gcc generally doesn't). | |
298 | * Real recursion would eat up our stack space. | |
299 | */ | |
300 | ||
301 | /* | |
302 | * dput - release a dentry | |
303 | * @dentry: dentry to release | |
304 | * | |
305 | * Release a dentry. This will drop the usage count and if appropriate | |
306 | * call the dentry unlink method as well as removing it from the queues and | |
307 | * releasing its resources. If the parent dentries were scheduled for release | |
308 | * they too may now get deleted. | |
309 | * | |
310 | * no dcache lock, please. | |
311 | */ | |
312 | ||
313 | void dput(struct dentry *dentry) | |
314 | { | |
2fd6b7f5 | 315 | struct dentry *parent; |
1da177e4 LT |
316 | if (!dentry) |
317 | return; | |
318 | ||
319 | repeat: | |
b7ab39f6 | 320 | if (dentry->d_count == 1) |
1da177e4 | 321 | might_sleep(); |
1da177e4 | 322 | spin_lock(&dentry->d_lock); |
2fd6b7f5 NP |
323 | if (IS_ROOT(dentry)) |
324 | parent = NULL; | |
325 | else | |
326 | parent = dentry->d_parent; | |
b7ab39f6 NP |
327 | if (dentry->d_count == 1) { |
328 | if (!spin_trylock(&dcache_lock)) { | |
329 | /* | |
330 | * Something of a livelock possibility we could avoid | |
331 | * by taking dcache_lock and trying again, but we | |
332 | * want to reduce dcache_lock anyway so this will | |
333 | * get improved. | |
334 | */ | |
335 | spin_unlock(&dentry->d_lock); | |
336 | goto repeat; | |
337 | } | |
2fd6b7f5 NP |
338 | if (parent && !spin_trylock(&parent->d_lock)) { |
339 | spin_unlock(&dentry->d_lock); | |
340 | spin_unlock(&dcache_lock); | |
341 | goto repeat; | |
342 | } | |
b7ab39f6 NP |
343 | } |
344 | dentry->d_count--; | |
345 | if (dentry->d_count) { | |
1da177e4 | 346 | spin_unlock(&dentry->d_lock); |
2fd6b7f5 NP |
347 | if (parent) |
348 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
349 | spin_unlock(&dcache_lock); |
350 | return; | |
351 | } | |
352 | ||
353 | /* | |
354 | * AV: ->d_delete() is _NOT_ allowed to block now. | |
355 | */ | |
356 | if (dentry->d_op && dentry->d_op->d_delete) { | |
357 | if (dentry->d_op->d_delete(dentry)) | |
358 | goto unhash_it; | |
359 | } | |
265ac902 | 360 | |
1da177e4 LT |
361 | /* Unreachable? Get rid of it */ |
362 | if (d_unhashed(dentry)) | |
363 | goto kill_it; | |
265ac902 NP |
364 | |
365 | /* Otherwise leave it cached and ensure it's on the LRU */ | |
366 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 367 | dentry_lru_add(dentry); |
265ac902 | 368 | |
1da177e4 | 369 | spin_unlock(&dentry->d_lock); |
2fd6b7f5 NP |
370 | if (parent) |
371 | spin_unlock(&parent->d_lock); | |
1da177e4 LT |
372 | spin_unlock(&dcache_lock); |
373 | return; | |
374 | ||
375 | unhash_it: | |
376 | __d_drop(dentry); | |
d52b9086 | 377 | kill_it: |
da3bbdd4 KM |
378 | /* if dentry was on the d_lru list delete it from there */ |
379 | dentry_lru_del(dentry); | |
2fd6b7f5 | 380 | dentry = d_kill(dentry, parent); |
d52b9086 MS |
381 | if (dentry) |
382 | goto repeat; | |
1da177e4 | 383 | } |
ec4f8605 | 384 | EXPORT_SYMBOL(dput); |
1da177e4 LT |
385 | |
386 | /** | |
387 | * d_invalidate - invalidate a dentry | |
388 | * @dentry: dentry to invalidate | |
389 | * | |
390 | * Try to invalidate the dentry if it turns out to be | |
391 | * possible. If there are other dentries that can be | |
392 | * reached through this one we can't delete it and we | |
393 | * return -EBUSY. On success we return 0. | |
394 | * | |
395 | * no dcache lock. | |
396 | */ | |
397 | ||
398 | int d_invalidate(struct dentry * dentry) | |
399 | { | |
400 | /* | |
401 | * If it's already been dropped, return OK. | |
402 | */ | |
403 | spin_lock(&dcache_lock); | |
da502956 | 404 | spin_lock(&dentry->d_lock); |
1da177e4 | 405 | if (d_unhashed(dentry)) { |
da502956 | 406 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
407 | spin_unlock(&dcache_lock); |
408 | return 0; | |
409 | } | |
410 | /* | |
411 | * Check whether to do a partial shrink_dcache | |
412 | * to get rid of unused child entries. | |
413 | */ | |
414 | if (!list_empty(&dentry->d_subdirs)) { | |
da502956 | 415 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
416 | spin_unlock(&dcache_lock); |
417 | shrink_dcache_parent(dentry); | |
418 | spin_lock(&dcache_lock); | |
da502956 | 419 | spin_lock(&dentry->d_lock); |
1da177e4 LT |
420 | } |
421 | ||
422 | /* | |
423 | * Somebody else still using it? | |
424 | * | |
425 | * If it's a directory, we can't drop it | |
426 | * for fear of somebody re-populating it | |
427 | * with children (even though dropping it | |
428 | * would make it unreachable from the root, | |
429 | * we might still populate it if it was a | |
430 | * working directory or similar). | |
431 | */ | |
b7ab39f6 | 432 | if (dentry->d_count > 1) { |
1da177e4 LT |
433 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { |
434 | spin_unlock(&dentry->d_lock); | |
435 | spin_unlock(&dcache_lock); | |
436 | return -EBUSY; | |
437 | } | |
438 | } | |
439 | ||
440 | __d_drop(dentry); | |
441 | spin_unlock(&dentry->d_lock); | |
442 | spin_unlock(&dcache_lock); | |
443 | return 0; | |
444 | } | |
ec4f8605 | 445 | EXPORT_SYMBOL(d_invalidate); |
1da177e4 | 446 | |
b7ab39f6 | 447 | /* This must be called with dcache_lock and d_lock held */ |
23044507 NP |
448 | static inline struct dentry * __dget_locked_dlock(struct dentry *dentry) |
449 | { | |
b7ab39f6 | 450 | dentry->d_count++; |
23044507 NP |
451 | dentry_lru_del(dentry); |
452 | return dentry; | |
453 | } | |
454 | ||
b7ab39f6 | 455 | /* This should be called _only_ with dcache_lock held */ |
1da177e4 LT |
456 | static inline struct dentry * __dget_locked(struct dentry *dentry) |
457 | { | |
23044507 | 458 | spin_lock(&dentry->d_lock); |
b7ab39f6 | 459 | __dget_locked_dlock(dentry); |
23044507 | 460 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
461 | return dentry; |
462 | } | |
463 | ||
b7ab39f6 NP |
464 | struct dentry * dget_locked_dlock(struct dentry *dentry) |
465 | { | |
466 | return __dget_locked_dlock(dentry); | |
467 | } | |
468 | ||
1da177e4 LT |
469 | struct dentry * dget_locked(struct dentry *dentry) |
470 | { | |
471 | return __dget_locked(dentry); | |
472 | } | |
ec4f8605 | 473 | EXPORT_SYMBOL(dget_locked); |
1da177e4 | 474 | |
b7ab39f6 NP |
475 | struct dentry *dget_parent(struct dentry *dentry) |
476 | { | |
477 | struct dentry *ret; | |
478 | ||
479 | repeat: | |
480 | spin_lock(&dentry->d_lock); | |
481 | ret = dentry->d_parent; | |
482 | if (!ret) | |
483 | goto out; | |
484 | if (dentry == ret) { | |
485 | ret->d_count++; | |
486 | goto out; | |
487 | } | |
488 | if (!spin_trylock(&ret->d_lock)) { | |
489 | spin_unlock(&dentry->d_lock); | |
490 | cpu_relax(); | |
491 | goto repeat; | |
492 | } | |
493 | BUG_ON(!ret->d_count); | |
494 | ret->d_count++; | |
495 | spin_unlock(&ret->d_lock); | |
496 | out: | |
497 | spin_unlock(&dentry->d_lock); | |
498 | return ret; | |
499 | } | |
500 | EXPORT_SYMBOL(dget_parent); | |
501 | ||
1da177e4 LT |
502 | /** |
503 | * d_find_alias - grab a hashed alias of inode | |
504 | * @inode: inode in question | |
505 | * @want_discon: flag, used by d_splice_alias, to request | |
506 | * that only a DISCONNECTED alias be returned. | |
507 | * | |
508 | * If inode has a hashed alias, or is a directory and has any alias, | |
509 | * acquire the reference to alias and return it. Otherwise return NULL. | |
510 | * Notice that if inode is a directory there can be only one alias and | |
511 | * it can be unhashed only if it has no children, or if it is the root | |
512 | * of a filesystem. | |
513 | * | |
21c0d8fd | 514 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
1da177e4 | 515 | * any other hashed alias over that one unless @want_discon is set, |
21c0d8fd | 516 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
1da177e4 | 517 | */ |
da502956 | 518 | static struct dentry *__d_find_alias(struct inode *inode, int want_discon) |
1da177e4 | 519 | { |
da502956 | 520 | struct dentry *alias, *discon_alias; |
1da177e4 | 521 | |
da502956 NP |
522 | again: |
523 | discon_alias = NULL; | |
524 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { | |
525 | spin_lock(&alias->d_lock); | |
1da177e4 | 526 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { |
21c0d8fd | 527 | if (IS_ROOT(alias) && |
da502956 | 528 | (alias->d_flags & DCACHE_DISCONNECTED)) { |
1da177e4 | 529 | discon_alias = alias; |
da502956 NP |
530 | } else if (!want_discon) { |
531 | __dget_locked_dlock(alias); | |
532 | spin_unlock(&alias->d_lock); | |
533 | return alias; | |
534 | } | |
535 | } | |
536 | spin_unlock(&alias->d_lock); | |
537 | } | |
538 | if (discon_alias) { | |
539 | alias = discon_alias; | |
540 | spin_lock(&alias->d_lock); | |
541 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
542 | if (IS_ROOT(alias) && | |
543 | (alias->d_flags & DCACHE_DISCONNECTED)) { | |
544 | __dget_locked_dlock(alias); | |
545 | spin_unlock(&alias->d_lock); | |
1da177e4 LT |
546 | return alias; |
547 | } | |
548 | } | |
da502956 NP |
549 | spin_unlock(&alias->d_lock); |
550 | goto again; | |
1da177e4 | 551 | } |
da502956 | 552 | return NULL; |
1da177e4 LT |
553 | } |
554 | ||
da502956 | 555 | struct dentry *d_find_alias(struct inode *inode) |
1da177e4 | 556 | { |
214fda1f DH |
557 | struct dentry *de = NULL; |
558 | ||
559 | if (!list_empty(&inode->i_dentry)) { | |
560 | spin_lock(&dcache_lock); | |
561 | de = __d_find_alias(inode, 0); | |
562 | spin_unlock(&dcache_lock); | |
563 | } | |
1da177e4 LT |
564 | return de; |
565 | } | |
ec4f8605 | 566 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
567 | |
568 | /* | |
569 | * Try to kill dentries associated with this inode. | |
570 | * WARNING: you must own a reference to inode. | |
571 | */ | |
572 | void d_prune_aliases(struct inode *inode) | |
573 | { | |
0cdca3f9 | 574 | struct dentry *dentry; |
1da177e4 LT |
575 | restart: |
576 | spin_lock(&dcache_lock); | |
0cdca3f9 | 577 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 | 578 | spin_lock(&dentry->d_lock); |
b7ab39f6 | 579 | if (!dentry->d_count) { |
23044507 | 580 | __dget_locked_dlock(dentry); |
1da177e4 LT |
581 | __d_drop(dentry); |
582 | spin_unlock(&dentry->d_lock); | |
583 | spin_unlock(&dcache_lock); | |
584 | dput(dentry); | |
585 | goto restart; | |
586 | } | |
587 | spin_unlock(&dentry->d_lock); | |
588 | } | |
589 | spin_unlock(&dcache_lock); | |
590 | } | |
ec4f8605 | 591 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 LT |
592 | |
593 | /* | |
d702ccb3 AM |
594 | * Throw away a dentry - free the inode, dput the parent. This requires that |
595 | * the LRU list has already been removed. | |
596 | * | |
85864e10 MS |
597 | * Try to prune ancestors as well. This is necessary to prevent |
598 | * quadratic behavior of shrink_dcache_parent(), but is also expected | |
599 | * to be beneficial in reducing dentry cache fragmentation. | |
1da177e4 | 600 | */ |
2fd6b7f5 | 601 | static void prune_one_dentry(struct dentry *dentry, struct dentry *parent) |
31f3e0b3 | 602 | __releases(dentry->d_lock) |
2fd6b7f5 | 603 | __releases(parent->d_lock) |
31f3e0b3 | 604 | __releases(dcache_lock) |
1da177e4 | 605 | { |
1da177e4 | 606 | __d_drop(dentry); |
2fd6b7f5 | 607 | dentry = d_kill(dentry, parent); |
d52b9086 MS |
608 | |
609 | /* | |
610 | * Prune ancestors. Locking is simpler than in dput(), | |
611 | * because dcache_lock needs to be taken anyway. | |
612 | */ | |
d52b9086 | 613 | while (dentry) { |
23044507 | 614 | spin_lock(&dcache_lock); |
2fd6b7f5 | 615 | again: |
b7ab39f6 | 616 | spin_lock(&dentry->d_lock); |
2fd6b7f5 NP |
617 | if (IS_ROOT(dentry)) |
618 | parent = NULL; | |
619 | else | |
620 | parent = dentry->d_parent; | |
621 | if (parent && !spin_trylock(&parent->d_lock)) { | |
622 | spin_unlock(&dentry->d_lock); | |
623 | goto again; | |
624 | } | |
b7ab39f6 NP |
625 | dentry->d_count--; |
626 | if (dentry->d_count) { | |
2fd6b7f5 NP |
627 | if (parent) |
628 | spin_unlock(&parent->d_lock); | |
b7ab39f6 | 629 | spin_unlock(&dentry->d_lock); |
23044507 | 630 | spin_unlock(&dcache_lock); |
d52b9086 | 631 | return; |
23044507 | 632 | } |
d52b9086 | 633 | |
a4633357 | 634 | dentry_lru_del(dentry); |
d52b9086 | 635 | __d_drop(dentry); |
2fd6b7f5 | 636 | dentry = d_kill(dentry, parent); |
d52b9086 | 637 | } |
1da177e4 LT |
638 | } |
639 | ||
3049cfe2 | 640 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 641 | { |
da3bbdd4 | 642 | struct dentry *dentry; |
da3bbdd4 | 643 | |
3049cfe2 | 644 | while (!list_empty(list)) { |
2fd6b7f5 NP |
645 | struct dentry *parent; |
646 | ||
3049cfe2 | 647 | dentry = list_entry(list->prev, struct dentry, d_lru); |
23044507 NP |
648 | |
649 | if (!spin_trylock(&dentry->d_lock)) { | |
2fd6b7f5 | 650 | relock: |
23044507 NP |
651 | spin_unlock(&dcache_lru_lock); |
652 | cpu_relax(); | |
653 | spin_lock(&dcache_lru_lock); | |
654 | continue; | |
655 | } | |
656 | ||
1da177e4 LT |
657 | /* |
658 | * We found an inuse dentry which was not removed from | |
da3bbdd4 KM |
659 | * the LRU because of laziness during lookup. Do not free |
660 | * it - just keep it off the LRU list. | |
1da177e4 | 661 | */ |
b7ab39f6 | 662 | if (dentry->d_count) { |
2fd6b7f5 | 663 | __dentry_lru_del(dentry); |
da3bbdd4 | 664 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
665 | continue; |
666 | } | |
2fd6b7f5 NP |
667 | if (IS_ROOT(dentry)) |
668 | parent = NULL; | |
669 | else | |
670 | parent = dentry->d_parent; | |
671 | if (parent && !spin_trylock(&parent->d_lock)) { | |
672 | spin_unlock(&dentry->d_lock); | |
673 | goto relock; | |
674 | } | |
675 | __dentry_lru_del(dentry); | |
23044507 NP |
676 | spin_unlock(&dcache_lru_lock); |
677 | ||
2fd6b7f5 | 678 | prune_one_dentry(dentry, parent); |
23044507 NP |
679 | /* dcache_lock and dentry->d_lock dropped */ |
680 | spin_lock(&dcache_lock); | |
681 | spin_lock(&dcache_lru_lock); | |
da3bbdd4 | 682 | } |
3049cfe2 CH |
683 | } |
684 | ||
685 | /** | |
686 | * __shrink_dcache_sb - shrink the dentry LRU on a given superblock | |
687 | * @sb: superblock to shrink dentry LRU. | |
688 | * @count: number of entries to prune | |
689 | * @flags: flags to control the dentry processing | |
690 | * | |
691 | * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. | |
692 | */ | |
693 | static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) | |
694 | { | |
695 | /* called from prune_dcache() and shrink_dcache_parent() */ | |
696 | struct dentry *dentry; | |
697 | LIST_HEAD(referenced); | |
698 | LIST_HEAD(tmp); | |
699 | int cnt = *count; | |
700 | ||
701 | spin_lock(&dcache_lock); | |
23044507 NP |
702 | relock: |
703 | spin_lock(&dcache_lru_lock); | |
3049cfe2 CH |
704 | while (!list_empty(&sb->s_dentry_lru)) { |
705 | dentry = list_entry(sb->s_dentry_lru.prev, | |
706 | struct dentry, d_lru); | |
707 | BUG_ON(dentry->d_sb != sb); | |
708 | ||
23044507 NP |
709 | if (!spin_trylock(&dentry->d_lock)) { |
710 | spin_unlock(&dcache_lru_lock); | |
711 | cpu_relax(); | |
712 | goto relock; | |
713 | } | |
714 | ||
3049cfe2 CH |
715 | /* |
716 | * If we are honouring the DCACHE_REFERENCED flag and the | |
717 | * dentry has this flag set, don't free it. Clear the flag | |
718 | * and put it back on the LRU. | |
719 | */ | |
23044507 NP |
720 | if (flags & DCACHE_REFERENCED && |
721 | dentry->d_flags & DCACHE_REFERENCED) { | |
722 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
723 | list_move(&dentry->d_lru, &referenced); | |
3049cfe2 | 724 | spin_unlock(&dentry->d_lock); |
23044507 NP |
725 | } else { |
726 | list_move_tail(&dentry->d_lru, &tmp); | |
727 | spin_unlock(&dentry->d_lock); | |
728 | if (!--cnt) | |
729 | break; | |
3049cfe2 | 730 | } |
23044507 | 731 | /* XXX: re-add cond_resched_lock when dcache_lock goes away */ |
3049cfe2 CH |
732 | } |
733 | ||
734 | *count = cnt; | |
735 | shrink_dentry_list(&tmp); | |
736 | ||
da3bbdd4 KM |
737 | if (!list_empty(&referenced)) |
738 | list_splice(&referenced, &sb->s_dentry_lru); | |
23044507 | 739 | spin_unlock(&dcache_lru_lock); |
da3bbdd4 | 740 | spin_unlock(&dcache_lock); |
3049cfe2 | 741 | |
da3bbdd4 KM |
742 | } |
743 | ||
744 | /** | |
745 | * prune_dcache - shrink the dcache | |
746 | * @count: number of entries to try to free | |
747 | * | |
748 | * Shrink the dcache. This is done when we need more memory, or simply when we | |
749 | * need to unmount something (at which point we need to unuse all dentries). | |
750 | * | |
751 | * This function may fail to free any resources if all the dentries are in use. | |
752 | */ | |
753 | static void prune_dcache(int count) | |
754 | { | |
dca33252 | 755 | struct super_block *sb, *p = NULL; |
da3bbdd4 | 756 | int w_count; |
86c8749e | 757 | int unused = dentry_stat.nr_unused; |
da3bbdd4 KM |
758 | int prune_ratio; |
759 | int pruned; | |
760 | ||
761 | if (unused == 0 || count == 0) | |
762 | return; | |
763 | spin_lock(&dcache_lock); | |
da3bbdd4 KM |
764 | if (count >= unused) |
765 | prune_ratio = 1; | |
766 | else | |
767 | prune_ratio = unused / count; | |
768 | spin_lock(&sb_lock); | |
dca33252 | 769 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
770 | if (list_empty(&sb->s_instances)) |
771 | continue; | |
da3bbdd4 | 772 | if (sb->s_nr_dentry_unused == 0) |
1da177e4 | 773 | continue; |
da3bbdd4 KM |
774 | sb->s_count++; |
775 | /* Now, we reclaim unused dentrins with fairness. | |
776 | * We reclaim them same percentage from each superblock. | |
777 | * We calculate number of dentries to scan on this sb | |
778 | * as follows, but the implementation is arranged to avoid | |
779 | * overflows: | |
780 | * number of dentries to scan on this sb = | |
781 | * count * (number of dentries on this sb / | |
782 | * number of dentries in the machine) | |
0feae5c4 | 783 | */ |
da3bbdd4 KM |
784 | spin_unlock(&sb_lock); |
785 | if (prune_ratio != 1) | |
786 | w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1; | |
787 | else | |
788 | w_count = sb->s_nr_dentry_unused; | |
789 | pruned = w_count; | |
0feae5c4 | 790 | /* |
da3bbdd4 KM |
791 | * We need to be sure this filesystem isn't being unmounted, |
792 | * otherwise we could race with generic_shutdown_super(), and | |
793 | * end up holding a reference to an inode while the filesystem | |
794 | * is unmounted. So we try to get s_umount, and make sure | |
795 | * s_root isn't NULL. | |
0feae5c4 | 796 | */ |
da3bbdd4 KM |
797 | if (down_read_trylock(&sb->s_umount)) { |
798 | if ((sb->s_root != NULL) && | |
799 | (!list_empty(&sb->s_dentry_lru))) { | |
800 | spin_unlock(&dcache_lock); | |
801 | __shrink_dcache_sb(sb, &w_count, | |
802 | DCACHE_REFERENCED); | |
803 | pruned -= w_count; | |
804 | spin_lock(&dcache_lock); | |
0feae5c4 | 805 | } |
da3bbdd4 | 806 | up_read(&sb->s_umount); |
0feae5c4 | 807 | } |
da3bbdd4 | 808 | spin_lock(&sb_lock); |
dca33252 AV |
809 | if (p) |
810 | __put_super(p); | |
da3bbdd4 | 811 | count -= pruned; |
dca33252 | 812 | p = sb; |
79893c17 AV |
813 | /* more work left to do? */ |
814 | if (count <= 0) | |
815 | break; | |
1da177e4 | 816 | } |
dca33252 AV |
817 | if (p) |
818 | __put_super(p); | |
da3bbdd4 | 819 | spin_unlock(&sb_lock); |
1da177e4 LT |
820 | spin_unlock(&dcache_lock); |
821 | } | |
822 | ||
1da177e4 LT |
823 | /** |
824 | * shrink_dcache_sb - shrink dcache for a superblock | |
825 | * @sb: superblock | |
826 | * | |
3049cfe2 CH |
827 | * Shrink the dcache for the specified super block. This is used to free |
828 | * the dcache before unmounting a file system. | |
1da177e4 | 829 | */ |
3049cfe2 | 830 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 831 | { |
3049cfe2 CH |
832 | LIST_HEAD(tmp); |
833 | ||
834 | spin_lock(&dcache_lock); | |
23044507 | 835 | spin_lock(&dcache_lru_lock); |
3049cfe2 CH |
836 | while (!list_empty(&sb->s_dentry_lru)) { |
837 | list_splice_init(&sb->s_dentry_lru, &tmp); | |
838 | shrink_dentry_list(&tmp); | |
839 | } | |
23044507 | 840 | spin_unlock(&dcache_lru_lock); |
3049cfe2 | 841 | spin_unlock(&dcache_lock); |
1da177e4 | 842 | } |
ec4f8605 | 843 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 844 | |
c636ebdb DH |
845 | /* |
846 | * destroy a single subtree of dentries for unmount | |
847 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
848 | * locking | |
849 | */ | |
850 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
851 | { | |
852 | struct dentry *parent; | |
f8713576 | 853 | unsigned detached = 0; |
c636ebdb DH |
854 | |
855 | BUG_ON(!IS_ROOT(dentry)); | |
856 | ||
857 | /* detach this root from the system */ | |
858 | spin_lock(&dcache_lock); | |
23044507 | 859 | spin_lock(&dentry->d_lock); |
a4633357 | 860 | dentry_lru_del(dentry); |
c636ebdb | 861 | __d_drop(dentry); |
da502956 | 862 | spin_unlock(&dentry->d_lock); |
c636ebdb DH |
863 | spin_unlock(&dcache_lock); |
864 | ||
865 | for (;;) { | |
866 | /* descend to the first leaf in the current subtree */ | |
867 | while (!list_empty(&dentry->d_subdirs)) { | |
868 | struct dentry *loop; | |
869 | ||
870 | /* this is a branch with children - detach all of them | |
871 | * from the system in one go */ | |
872 | spin_lock(&dcache_lock); | |
2fd6b7f5 | 873 | spin_lock(&dentry->d_lock); |
c636ebdb DH |
874 | list_for_each_entry(loop, &dentry->d_subdirs, |
875 | d_u.d_child) { | |
2fd6b7f5 NP |
876 | spin_lock_nested(&loop->d_lock, |
877 | DENTRY_D_LOCK_NESTED); | |
a4633357 | 878 | dentry_lru_del(loop); |
c636ebdb | 879 | __d_drop(loop); |
da502956 | 880 | spin_unlock(&loop->d_lock); |
c636ebdb | 881 | } |
2fd6b7f5 | 882 | spin_unlock(&dentry->d_lock); |
c636ebdb DH |
883 | spin_unlock(&dcache_lock); |
884 | ||
885 | /* move to the first child */ | |
886 | dentry = list_entry(dentry->d_subdirs.next, | |
887 | struct dentry, d_u.d_child); | |
888 | } | |
889 | ||
890 | /* consume the dentries from this leaf up through its parents | |
891 | * until we find one with children or run out altogether */ | |
892 | do { | |
893 | struct inode *inode; | |
894 | ||
b7ab39f6 | 895 | if (dentry->d_count != 0) { |
c636ebdb DH |
896 | printk(KERN_ERR |
897 | "BUG: Dentry %p{i=%lx,n=%s}" | |
898 | " still in use (%d)" | |
899 | " [unmount of %s %s]\n", | |
900 | dentry, | |
901 | dentry->d_inode ? | |
902 | dentry->d_inode->i_ino : 0UL, | |
903 | dentry->d_name.name, | |
b7ab39f6 | 904 | dentry->d_count, |
c636ebdb DH |
905 | dentry->d_sb->s_type->name, |
906 | dentry->d_sb->s_id); | |
907 | BUG(); | |
908 | } | |
909 | ||
2fd6b7f5 | 910 | if (IS_ROOT(dentry)) { |
c636ebdb | 911 | parent = NULL; |
2fd6b7f5 NP |
912 | list_del(&dentry->d_u.d_child); |
913 | } else { | |
871c0067 | 914 | parent = dentry->d_parent; |
b7ab39f6 NP |
915 | spin_lock(&parent->d_lock); |
916 | parent->d_count--; | |
2fd6b7f5 | 917 | list_del(&dentry->d_u.d_child); |
b7ab39f6 | 918 | spin_unlock(&parent->d_lock); |
871c0067 | 919 | } |
c636ebdb | 920 | |
f8713576 | 921 | detached++; |
c636ebdb DH |
922 | |
923 | inode = dentry->d_inode; | |
924 | if (inode) { | |
925 | dentry->d_inode = NULL; | |
926 | list_del_init(&dentry->d_alias); | |
927 | if (dentry->d_op && dentry->d_op->d_iput) | |
928 | dentry->d_op->d_iput(dentry, inode); | |
929 | else | |
930 | iput(inode); | |
931 | } | |
932 | ||
933 | d_free(dentry); | |
934 | ||
935 | /* finished when we fall off the top of the tree, | |
936 | * otherwise we ascend to the parent and move to the | |
937 | * next sibling if there is one */ | |
938 | if (!parent) | |
312d3ca8 | 939 | return; |
c636ebdb | 940 | dentry = parent; |
c636ebdb DH |
941 | } while (list_empty(&dentry->d_subdirs)); |
942 | ||
943 | dentry = list_entry(dentry->d_subdirs.next, | |
944 | struct dentry, d_u.d_child); | |
945 | } | |
946 | } | |
947 | ||
948 | /* | |
949 | * destroy the dentries attached to a superblock on unmounting | |
950 | * - we don't need to use dentry->d_lock, and only need dcache_lock when | |
951 | * removing the dentry from the system lists and hashes because: | |
952 | * - the superblock is detached from all mountings and open files, so the | |
953 | * dentry trees will not be rearranged by the VFS | |
954 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
955 | * any dentries belonging to this superblock that it comes across | |
956 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
957 | * in this superblock | |
958 | */ | |
959 | void shrink_dcache_for_umount(struct super_block *sb) | |
960 | { | |
961 | struct dentry *dentry; | |
962 | ||
963 | if (down_read_trylock(&sb->s_umount)) | |
964 | BUG(); | |
965 | ||
966 | dentry = sb->s_root; | |
967 | sb->s_root = NULL; | |
b7ab39f6 NP |
968 | spin_lock(&dentry->d_lock); |
969 | dentry->d_count--; | |
970 | spin_unlock(&dentry->d_lock); | |
c636ebdb DH |
971 | shrink_dcache_for_umount_subtree(dentry); |
972 | ||
973 | while (!hlist_empty(&sb->s_anon)) { | |
974 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); | |
975 | shrink_dcache_for_umount_subtree(dentry); | |
976 | } | |
977 | } | |
978 | ||
1da177e4 LT |
979 | /* |
980 | * Search for at least 1 mount point in the dentry's subdirs. | |
981 | * We descend to the next level whenever the d_subdirs | |
982 | * list is non-empty and continue searching. | |
983 | */ | |
984 | ||
985 | /** | |
986 | * have_submounts - check for mounts over a dentry | |
987 | * @parent: dentry to check. | |
988 | * | |
989 | * Return true if the parent or its subdirectories contain | |
990 | * a mount point | |
991 | */ | |
992 | ||
993 | int have_submounts(struct dentry *parent) | |
994 | { | |
995 | struct dentry *this_parent = parent; | |
996 | struct list_head *next; | |
997 | ||
998 | spin_lock(&dcache_lock); | |
999 | if (d_mountpoint(parent)) | |
1000 | goto positive; | |
2fd6b7f5 | 1001 | spin_lock(&this_parent->d_lock); |
1da177e4 LT |
1002 | repeat: |
1003 | next = this_parent->d_subdirs.next; | |
1004 | resume: | |
1005 | while (next != &this_parent->d_subdirs) { | |
1006 | struct list_head *tmp = next; | |
5160ee6f | 1007 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 | 1008 | next = tmp->next; |
2fd6b7f5 NP |
1009 | |
1010 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
1da177e4 | 1011 | /* Have we found a mount point ? */ |
2fd6b7f5 NP |
1012 | if (d_mountpoint(dentry)) { |
1013 | spin_unlock(&dentry->d_lock); | |
1014 | spin_unlock(&this_parent->d_lock); | |
1da177e4 | 1015 | goto positive; |
2fd6b7f5 | 1016 | } |
1da177e4 | 1017 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
1018 | spin_unlock(&this_parent->d_lock); |
1019 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1020 | this_parent = dentry; |
2fd6b7f5 | 1021 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1022 | goto repeat; |
1023 | } | |
2fd6b7f5 | 1024 | spin_unlock(&dentry->d_lock); |
1da177e4 LT |
1025 | } |
1026 | /* | |
1027 | * All done at this level ... ascend and resume the search. | |
1028 | */ | |
1029 | if (this_parent != parent) { | |
5160ee6f | 1030 | next = this_parent->d_u.d_child.next; |
2fd6b7f5 | 1031 | spin_unlock(&this_parent->d_lock); |
1da177e4 | 1032 | this_parent = this_parent->d_parent; |
2fd6b7f5 | 1033 | spin_lock(&this_parent->d_lock); |
1da177e4 LT |
1034 | goto resume; |
1035 | } | |
2fd6b7f5 | 1036 | spin_unlock(&this_parent->d_lock); |
1da177e4 LT |
1037 | spin_unlock(&dcache_lock); |
1038 | return 0; /* No mount points found in tree */ | |
1039 | positive: | |
1040 | spin_unlock(&dcache_lock); | |
1041 | return 1; | |
1042 | } | |
ec4f8605 | 1043 | EXPORT_SYMBOL(have_submounts); |
1da177e4 LT |
1044 | |
1045 | /* | |
1046 | * Search the dentry child list for the specified parent, | |
1047 | * and move any unused dentries to the end of the unused | |
1048 | * list for prune_dcache(). We descend to the next level | |
1049 | * whenever the d_subdirs list is non-empty and continue | |
1050 | * searching. | |
1051 | * | |
1052 | * It returns zero iff there are no unused children, | |
1053 | * otherwise it returns the number of children moved to | |
1054 | * the end of the unused list. This may not be the total | |
1055 | * number of unused children, because select_parent can | |
1056 | * drop the lock and return early due to latency | |
1057 | * constraints. | |
1058 | */ | |
1059 | static int select_parent(struct dentry * parent) | |
1060 | { | |
1061 | struct dentry *this_parent = parent; | |
1062 | struct list_head *next; | |
1063 | int found = 0; | |
1064 | ||
1065 | spin_lock(&dcache_lock); | |
2fd6b7f5 | 1066 | spin_lock(&this_parent->d_lock); |
1da177e4 LT |
1067 | repeat: |
1068 | next = this_parent->d_subdirs.next; | |
1069 | resume: | |
1070 | while (next != &this_parent->d_subdirs) { | |
1071 | struct list_head *tmp = next; | |
5160ee6f | 1072 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 | 1073 | next = tmp->next; |
2fd6b7f5 | 1074 | BUG_ON(this_parent == dentry); |
1da177e4 | 1075 | |
2fd6b7f5 | 1076 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
23044507 | 1077 | |
1da177e4 LT |
1078 | /* |
1079 | * move only zero ref count dentries to the end | |
1080 | * of the unused list for prune_dcache | |
1081 | */ | |
b7ab39f6 | 1082 | if (!dentry->d_count) { |
a4633357 | 1083 | dentry_lru_move_tail(dentry); |
1da177e4 | 1084 | found++; |
a4633357 CH |
1085 | } else { |
1086 | dentry_lru_del(dentry); | |
1da177e4 LT |
1087 | } |
1088 | ||
1089 | /* | |
1090 | * We can return to the caller if we have found some (this | |
1091 | * ensures forward progress). We'll be coming back to find | |
1092 | * the rest. | |
1093 | */ | |
2fd6b7f5 NP |
1094 | if (found && need_resched()) { |
1095 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 1096 | goto out; |
2fd6b7f5 | 1097 | } |
1da177e4 LT |
1098 | |
1099 | /* | |
1100 | * Descend a level if the d_subdirs list is non-empty. | |
1101 | */ | |
1102 | if (!list_empty(&dentry->d_subdirs)) { | |
2fd6b7f5 NP |
1103 | spin_unlock(&this_parent->d_lock); |
1104 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 1105 | this_parent = dentry; |
2fd6b7f5 | 1106 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
1107 | goto repeat; |
1108 | } | |
2fd6b7f5 NP |
1109 | |
1110 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
1111 | } |
1112 | /* | |
1113 | * All done at this level ... ascend and resume the search. | |
1114 | */ | |
1115 | if (this_parent != parent) { | |
2fd6b7f5 | 1116 | struct dentry *tmp; |
5160ee6f | 1117 | next = this_parent->d_u.d_child.next; |
2fd6b7f5 NP |
1118 | tmp = this_parent->d_parent; |
1119 | spin_unlock(&this_parent->d_lock); | |
1120 | BUG_ON(tmp == this_parent); | |
1121 | this_parent = tmp; | |
1122 | spin_lock(&this_parent->d_lock); | |
1da177e4 LT |
1123 | goto resume; |
1124 | } | |
1125 | out: | |
2fd6b7f5 | 1126 | spin_unlock(&this_parent->d_lock); |
1da177e4 LT |
1127 | spin_unlock(&dcache_lock); |
1128 | return found; | |
1129 | } | |
1130 | ||
1131 | /** | |
1132 | * shrink_dcache_parent - prune dcache | |
1133 | * @parent: parent of entries to prune | |
1134 | * | |
1135 | * Prune the dcache to remove unused children of the parent dentry. | |
1136 | */ | |
1137 | ||
1138 | void shrink_dcache_parent(struct dentry * parent) | |
1139 | { | |
da3bbdd4 | 1140 | struct super_block *sb = parent->d_sb; |
1da177e4 LT |
1141 | int found; |
1142 | ||
1143 | while ((found = select_parent(parent)) != 0) | |
da3bbdd4 | 1144 | __shrink_dcache_sb(sb, &found, 0); |
1da177e4 | 1145 | } |
ec4f8605 | 1146 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 1147 | |
1da177e4 LT |
1148 | /* |
1149 | * Scan `nr' dentries and return the number which remain. | |
1150 | * | |
1151 | * We need to avoid reentering the filesystem if the caller is performing a | |
1152 | * GFP_NOFS allocation attempt. One example deadlock is: | |
1153 | * | |
1154 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> | |
1155 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> | |
1156 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. | |
1157 | * | |
1158 | * In this case we return -1 to tell the caller that we baled. | |
1159 | */ | |
7f8275d0 | 1160 | static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask) |
1da177e4 LT |
1161 | { |
1162 | if (nr) { | |
1163 | if (!(gfp_mask & __GFP_FS)) | |
1164 | return -1; | |
da3bbdd4 | 1165 | prune_dcache(nr); |
1da177e4 | 1166 | } |
312d3ca8 | 1167 | |
86c8749e | 1168 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; |
1da177e4 LT |
1169 | } |
1170 | ||
8e1f936b RR |
1171 | static struct shrinker dcache_shrinker = { |
1172 | .shrink = shrink_dcache_memory, | |
1173 | .seeks = DEFAULT_SEEKS, | |
1174 | }; | |
1175 | ||
1da177e4 LT |
1176 | /** |
1177 | * d_alloc - allocate a dcache entry | |
1178 | * @parent: parent of entry to allocate | |
1179 | * @name: qstr of the name | |
1180 | * | |
1181 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
1182 | * available. On a success the dentry is returned. The name passed in is | |
1183 | * copied and the copy passed in may be reused after this call. | |
1184 | */ | |
1185 | ||
1186 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
1187 | { | |
1188 | struct dentry *dentry; | |
1189 | char *dname; | |
1190 | ||
e12ba74d | 1191 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
1192 | if (!dentry) |
1193 | return NULL; | |
1194 | ||
1195 | if (name->len > DNAME_INLINE_LEN-1) { | |
1196 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
1197 | if (!dname) { | |
1198 | kmem_cache_free(dentry_cache, dentry); | |
1199 | return NULL; | |
1200 | } | |
1201 | } else { | |
1202 | dname = dentry->d_iname; | |
1203 | } | |
1204 | dentry->d_name.name = dname; | |
1205 | ||
1206 | dentry->d_name.len = name->len; | |
1207 | dentry->d_name.hash = name->hash; | |
1208 | memcpy(dname, name->name, name->len); | |
1209 | dname[name->len] = 0; | |
1210 | ||
b7ab39f6 | 1211 | dentry->d_count = 1; |
1da177e4 LT |
1212 | dentry->d_flags = DCACHE_UNHASHED; |
1213 | spin_lock_init(&dentry->d_lock); | |
1214 | dentry->d_inode = NULL; | |
1215 | dentry->d_parent = NULL; | |
1216 | dentry->d_sb = NULL; | |
1217 | dentry->d_op = NULL; | |
1218 | dentry->d_fsdata = NULL; | |
1219 | dentry->d_mounted = 0; | |
1da177e4 LT |
1220 | INIT_HLIST_NODE(&dentry->d_hash); |
1221 | INIT_LIST_HEAD(&dentry->d_lru); | |
1222 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
1223 | INIT_LIST_HEAD(&dentry->d_alias); | |
2fd6b7f5 | 1224 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1da177e4 LT |
1225 | |
1226 | if (parent) { | |
2fd6b7f5 NP |
1227 | spin_lock(&dcache_lock); |
1228 | spin_lock(&parent->d_lock); | |
1229 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); | |
1230 | dentry->d_parent = dget_dlock(parent); | |
1da177e4 | 1231 | dentry->d_sb = parent->d_sb; |
5160ee6f | 1232 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
2fd6b7f5 NP |
1233 | spin_unlock(&dentry->d_lock); |
1234 | spin_unlock(&parent->d_lock); | |
1235 | spin_unlock(&dcache_lock); | |
1236 | } | |
1da177e4 | 1237 | |
3e880fb5 | 1238 | this_cpu_inc(nr_dentry); |
312d3ca8 | 1239 | |
1da177e4 LT |
1240 | return dentry; |
1241 | } | |
ec4f8605 | 1242 | EXPORT_SYMBOL(d_alloc); |
1da177e4 LT |
1243 | |
1244 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) | |
1245 | { | |
1246 | struct qstr q; | |
1247 | ||
1248 | q.name = name; | |
1249 | q.len = strlen(name); | |
1250 | q.hash = full_name_hash(q.name, q.len); | |
1251 | return d_alloc(parent, &q); | |
1252 | } | |
ef26ca97 | 1253 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1254 | |
360da900 OH |
1255 | /* the caller must hold dcache_lock */ |
1256 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) | |
1257 | { | |
1258 | if (inode) | |
1259 | list_add(&dentry->d_alias, &inode->i_dentry); | |
1260 | dentry->d_inode = inode; | |
1261 | fsnotify_d_instantiate(dentry, inode); | |
1262 | } | |
1263 | ||
1da177e4 LT |
1264 | /** |
1265 | * d_instantiate - fill in inode information for a dentry | |
1266 | * @entry: dentry to complete | |
1267 | * @inode: inode to attach to this dentry | |
1268 | * | |
1269 | * Fill in inode information in the entry. | |
1270 | * | |
1271 | * This turns negative dentries into productive full members | |
1272 | * of society. | |
1273 | * | |
1274 | * NOTE! This assumes that the inode count has been incremented | |
1275 | * (or otherwise set) by the caller to indicate that it is now | |
1276 | * in use by the dcache. | |
1277 | */ | |
1278 | ||
1279 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1280 | { | |
28133c7b | 1281 | BUG_ON(!list_empty(&entry->d_alias)); |
1da177e4 | 1282 | spin_lock(&dcache_lock); |
360da900 | 1283 | __d_instantiate(entry, inode); |
1da177e4 LT |
1284 | spin_unlock(&dcache_lock); |
1285 | security_d_instantiate(entry, inode); | |
1286 | } | |
ec4f8605 | 1287 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 LT |
1288 | |
1289 | /** | |
1290 | * d_instantiate_unique - instantiate a non-aliased dentry | |
1291 | * @entry: dentry to instantiate | |
1292 | * @inode: inode to attach to this dentry | |
1293 | * | |
1294 | * Fill in inode information in the entry. On success, it returns NULL. | |
1295 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 1296 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1297 | * |
1298 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1299 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1300 | * |
1301 | * This also assumes that the inode count has been incremented | |
1302 | * (or otherwise set) by the caller to indicate that it is now | |
1303 | * in use by the dcache. | |
1da177e4 | 1304 | */ |
770bfad8 DH |
1305 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1306 | struct inode *inode) | |
1da177e4 LT |
1307 | { |
1308 | struct dentry *alias; | |
1309 | int len = entry->d_name.len; | |
1310 | const char *name = entry->d_name.name; | |
1311 | unsigned int hash = entry->d_name.hash; | |
1312 | ||
770bfad8 | 1313 | if (!inode) { |
360da900 | 1314 | __d_instantiate(entry, NULL); |
770bfad8 DH |
1315 | return NULL; |
1316 | } | |
1317 | ||
1da177e4 LT |
1318 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1319 | struct qstr *qstr = &alias->d_name; | |
1320 | ||
1321 | if (qstr->hash != hash) | |
1322 | continue; | |
1323 | if (alias->d_parent != entry->d_parent) | |
1324 | continue; | |
1325 | if (qstr->len != len) | |
1326 | continue; | |
1327 | if (memcmp(qstr->name, name, len)) | |
1328 | continue; | |
1329 | dget_locked(alias); | |
1da177e4 LT |
1330 | return alias; |
1331 | } | |
770bfad8 | 1332 | |
360da900 | 1333 | __d_instantiate(entry, inode); |
1da177e4 LT |
1334 | return NULL; |
1335 | } | |
770bfad8 DH |
1336 | |
1337 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1338 | { | |
1339 | struct dentry *result; | |
1340 | ||
1341 | BUG_ON(!list_empty(&entry->d_alias)); | |
1342 | ||
1343 | spin_lock(&dcache_lock); | |
1344 | result = __d_instantiate_unique(entry, inode); | |
1345 | spin_unlock(&dcache_lock); | |
1346 | ||
1347 | if (!result) { | |
1348 | security_d_instantiate(entry, inode); | |
1349 | return NULL; | |
1350 | } | |
1351 | ||
1352 | BUG_ON(!d_unhashed(result)); | |
1353 | iput(inode); | |
1354 | return result; | |
1355 | } | |
1356 | ||
1da177e4 LT |
1357 | EXPORT_SYMBOL(d_instantiate_unique); |
1358 | ||
1359 | /** | |
1360 | * d_alloc_root - allocate root dentry | |
1361 | * @root_inode: inode to allocate the root for | |
1362 | * | |
1363 | * Allocate a root ("/") dentry for the inode given. The inode is | |
1364 | * instantiated and returned. %NULL is returned if there is insufficient | |
1365 | * memory or the inode passed is %NULL. | |
1366 | */ | |
1367 | ||
1368 | struct dentry * d_alloc_root(struct inode * root_inode) | |
1369 | { | |
1370 | struct dentry *res = NULL; | |
1371 | ||
1372 | if (root_inode) { | |
1373 | static const struct qstr name = { .name = "/", .len = 1 }; | |
1374 | ||
1375 | res = d_alloc(NULL, &name); | |
1376 | if (res) { | |
1377 | res->d_sb = root_inode->i_sb; | |
1378 | res->d_parent = res; | |
1379 | d_instantiate(res, root_inode); | |
1380 | } | |
1381 | } | |
1382 | return res; | |
1383 | } | |
ec4f8605 | 1384 | EXPORT_SYMBOL(d_alloc_root); |
1da177e4 LT |
1385 | |
1386 | static inline struct hlist_head *d_hash(struct dentry *parent, | |
1387 | unsigned long hash) | |
1388 | { | |
1389 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; | |
1390 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); | |
1391 | return dentry_hashtable + (hash & D_HASHMASK); | |
1392 | } | |
1393 | ||
4ea3ada2 CH |
1394 | /** |
1395 | * d_obtain_alias - find or allocate a dentry for a given inode | |
1396 | * @inode: inode to allocate the dentry for | |
1397 | * | |
1398 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1399 | * similar open by handle operations. The returned dentry may be anonymous, | |
1400 | * or may have a full name (if the inode was already in the cache). | |
1401 | * | |
1402 | * When called on a directory inode, we must ensure that the inode only ever | |
1403 | * has one dentry. If a dentry is found, that is returned instead of | |
1404 | * allocating a new one. | |
1405 | * | |
1406 | * On successful return, the reference to the inode has been transferred | |
44003728 CH |
1407 | * to the dentry. In case of an error the reference on the inode is released. |
1408 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1409 | * be passed in and will be the error will be propagate to the return value, | |
1410 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
4ea3ada2 CH |
1411 | */ |
1412 | struct dentry *d_obtain_alias(struct inode *inode) | |
1413 | { | |
9308a612 CH |
1414 | static const struct qstr anonstring = { .name = "" }; |
1415 | struct dentry *tmp; | |
1416 | struct dentry *res; | |
4ea3ada2 CH |
1417 | |
1418 | if (!inode) | |
44003728 | 1419 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1420 | if (IS_ERR(inode)) |
1421 | return ERR_CAST(inode); | |
1422 | ||
9308a612 CH |
1423 | res = d_find_alias(inode); |
1424 | if (res) | |
1425 | goto out_iput; | |
1426 | ||
1427 | tmp = d_alloc(NULL, &anonstring); | |
1428 | if (!tmp) { | |
1429 | res = ERR_PTR(-ENOMEM); | |
1430 | goto out_iput; | |
4ea3ada2 | 1431 | } |
9308a612 CH |
1432 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
1433 | ||
1434 | spin_lock(&dcache_lock); | |
1435 | res = __d_find_alias(inode, 0); | |
1436 | if (res) { | |
1437 | spin_unlock(&dcache_lock); | |
1438 | dput(tmp); | |
1439 | goto out_iput; | |
1440 | } | |
1441 | ||
1442 | /* attach a disconnected dentry */ | |
1443 | spin_lock(&tmp->d_lock); | |
1444 | tmp->d_sb = inode->i_sb; | |
1445 | tmp->d_inode = inode; | |
1446 | tmp->d_flags |= DCACHE_DISCONNECTED; | |
1447 | tmp->d_flags &= ~DCACHE_UNHASHED; | |
1448 | list_add(&tmp->d_alias, &inode->i_dentry); | |
789680d1 | 1449 | spin_lock(&dcache_hash_lock); |
9308a612 | 1450 | hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon); |
789680d1 | 1451 | spin_unlock(&dcache_hash_lock); |
9308a612 CH |
1452 | spin_unlock(&tmp->d_lock); |
1453 | ||
1454 | spin_unlock(&dcache_lock); | |
1455 | return tmp; | |
1456 | ||
1457 | out_iput: | |
1458 | iput(inode); | |
1459 | return res; | |
4ea3ada2 | 1460 | } |
adc48720 | 1461 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 LT |
1462 | |
1463 | /** | |
1464 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1465 | * @inode: the inode which may have a disconnected dentry | |
1466 | * @dentry: a negative dentry which we want to point to the inode. | |
1467 | * | |
1468 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1469 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1470 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1471 | * | |
1472 | * This is needed in the lookup routine of any filesystem that is exportable | |
1473 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1474 | * | |
1475 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1476 | * is returned. This matches the expected return value of ->lookup. | |
1477 | * | |
1478 | */ | |
1479 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1480 | { | |
1481 | struct dentry *new = NULL; | |
1482 | ||
21c0d8fd | 1483 | if (inode && S_ISDIR(inode->i_mode)) { |
1da177e4 LT |
1484 | spin_lock(&dcache_lock); |
1485 | new = __d_find_alias(inode, 1); | |
1486 | if (new) { | |
1487 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); | |
1488 | spin_unlock(&dcache_lock); | |
1489 | security_d_instantiate(new, inode); | |
1da177e4 LT |
1490 | d_move(new, dentry); |
1491 | iput(inode); | |
1492 | } else { | |
360da900 OH |
1493 | /* already taking dcache_lock, so d_add() by hand */ |
1494 | __d_instantiate(dentry, inode); | |
1da177e4 LT |
1495 | spin_unlock(&dcache_lock); |
1496 | security_d_instantiate(dentry, inode); | |
1497 | d_rehash(dentry); | |
1498 | } | |
1499 | } else | |
1500 | d_add(dentry, inode); | |
1501 | return new; | |
1502 | } | |
ec4f8605 | 1503 | EXPORT_SYMBOL(d_splice_alias); |
1da177e4 | 1504 | |
9403540c BN |
1505 | /** |
1506 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
1507 | * @inode: the inode case-insensitive lookup has found | |
1508 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
1509 | * @name: the case-exact name to be associated with the returned dentry | |
1510 | * | |
1511 | * This is to avoid filling the dcache with case-insensitive names to the | |
1512 | * same inode, only the actual correct case is stored in the dcache for | |
1513 | * case-insensitive filesystems. | |
1514 | * | |
1515 | * For a case-insensitive lookup match and if the the case-exact dentry | |
1516 | * already exists in in the dcache, use it and return it. | |
1517 | * | |
1518 | * If no entry exists with the exact case name, allocate new dentry with | |
1519 | * the exact case, and return the spliced entry. | |
1520 | */ | |
e45b590b | 1521 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
1522 | struct qstr *name) |
1523 | { | |
1524 | int error; | |
1525 | struct dentry *found; | |
1526 | struct dentry *new; | |
1527 | ||
b6520c81 CH |
1528 | /* |
1529 | * First check if a dentry matching the name already exists, | |
1530 | * if not go ahead and create it now. | |
1531 | */ | |
9403540c | 1532 | found = d_hash_and_lookup(dentry->d_parent, name); |
9403540c BN |
1533 | if (!found) { |
1534 | new = d_alloc(dentry->d_parent, name); | |
1535 | if (!new) { | |
1536 | error = -ENOMEM; | |
1537 | goto err_out; | |
1538 | } | |
b6520c81 | 1539 | |
9403540c BN |
1540 | found = d_splice_alias(inode, new); |
1541 | if (found) { | |
1542 | dput(new); | |
1543 | return found; | |
1544 | } | |
1545 | return new; | |
1546 | } | |
b6520c81 CH |
1547 | |
1548 | /* | |
1549 | * If a matching dentry exists, and it's not negative use it. | |
1550 | * | |
1551 | * Decrement the reference count to balance the iget() done | |
1552 | * earlier on. | |
1553 | */ | |
9403540c BN |
1554 | if (found->d_inode) { |
1555 | if (unlikely(found->d_inode != inode)) { | |
1556 | /* This can't happen because bad inodes are unhashed. */ | |
1557 | BUG_ON(!is_bad_inode(inode)); | |
1558 | BUG_ON(!is_bad_inode(found->d_inode)); | |
1559 | } | |
9403540c BN |
1560 | iput(inode); |
1561 | return found; | |
1562 | } | |
b6520c81 | 1563 | |
9403540c BN |
1564 | /* |
1565 | * Negative dentry: instantiate it unless the inode is a directory and | |
b6520c81 | 1566 | * already has a dentry. |
9403540c | 1567 | */ |
9403540c | 1568 | spin_lock(&dcache_lock); |
b6520c81 | 1569 | if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) { |
360da900 | 1570 | __d_instantiate(found, inode); |
9403540c BN |
1571 | spin_unlock(&dcache_lock); |
1572 | security_d_instantiate(found, inode); | |
1573 | return found; | |
1574 | } | |
b6520c81 | 1575 | |
9403540c | 1576 | /* |
b6520c81 CH |
1577 | * In case a directory already has a (disconnected) entry grab a |
1578 | * reference to it, move it in place and use it. | |
9403540c BN |
1579 | */ |
1580 | new = list_entry(inode->i_dentry.next, struct dentry, d_alias); | |
1581 | dget_locked(new); | |
1582 | spin_unlock(&dcache_lock); | |
9403540c | 1583 | security_d_instantiate(found, inode); |
9403540c | 1584 | d_move(new, found); |
9403540c | 1585 | iput(inode); |
9403540c | 1586 | dput(found); |
9403540c BN |
1587 | return new; |
1588 | ||
1589 | err_out: | |
1590 | iput(inode); | |
1591 | return ERR_PTR(error); | |
1592 | } | |
ec4f8605 | 1593 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 LT |
1594 | |
1595 | /** | |
1596 | * d_lookup - search for a dentry | |
1597 | * @parent: parent dentry | |
1598 | * @name: qstr of name we wish to find | |
b04f784e | 1599 | * Returns: dentry, or NULL |
1da177e4 | 1600 | * |
b04f784e NP |
1601 | * d_lookup searches the children of the parent dentry for the name in |
1602 | * question. If the dentry is found its reference count is incremented and the | |
1603 | * dentry is returned. The caller must use dput to free the entry when it has | |
1604 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 1605 | */ |
1da177e4 LT |
1606 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
1607 | { | |
1608 | struct dentry * dentry = NULL; | |
1609 | unsigned long seq; | |
1610 | ||
1611 | do { | |
1612 | seq = read_seqbegin(&rename_lock); | |
1613 | dentry = __d_lookup(parent, name); | |
1614 | if (dentry) | |
1615 | break; | |
1616 | } while (read_seqretry(&rename_lock, seq)); | |
1617 | return dentry; | |
1618 | } | |
ec4f8605 | 1619 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 1620 | |
b04f784e NP |
1621 | /* |
1622 | * __d_lookup - search for a dentry (racy) | |
1623 | * @parent: parent dentry | |
1624 | * @name: qstr of name we wish to find | |
1625 | * Returns: dentry, or NULL | |
1626 | * | |
1627 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
1628 | * false-negative result due to unrelated rename activity. | |
1629 | * | |
1630 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
1631 | * however it must be used carefully, eg. with a following d_lookup in | |
1632 | * the case of failure. | |
1633 | * | |
1634 | * __d_lookup callers must be commented. | |
1635 | */ | |
1da177e4 LT |
1636 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) |
1637 | { | |
1638 | unsigned int len = name->len; | |
1639 | unsigned int hash = name->hash; | |
1640 | const unsigned char *str = name->name; | |
1641 | struct hlist_head *head = d_hash(parent,hash); | |
1642 | struct dentry *found = NULL; | |
1643 | struct hlist_node *node; | |
665a7583 | 1644 | struct dentry *dentry; |
1da177e4 | 1645 | |
b04f784e NP |
1646 | /* |
1647 | * The hash list is protected using RCU. | |
1648 | * | |
1649 | * Take d_lock when comparing a candidate dentry, to avoid races | |
1650 | * with d_move(). | |
1651 | * | |
1652 | * It is possible that concurrent renames can mess up our list | |
1653 | * walk here and result in missing our dentry, resulting in the | |
1654 | * false-negative result. d_lookup() protects against concurrent | |
1655 | * renames using rename_lock seqlock. | |
1656 | * | |
1657 | * See Documentation/vfs/dcache-locking.txt for more details. | |
1658 | */ | |
1da177e4 LT |
1659 | rcu_read_lock(); |
1660 | ||
665a7583 | 1661 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
1da177e4 LT |
1662 | struct qstr *qstr; |
1663 | ||
1da177e4 LT |
1664 | if (dentry->d_name.hash != hash) |
1665 | continue; | |
1666 | if (dentry->d_parent != parent) | |
1667 | continue; | |
1668 | ||
1669 | spin_lock(&dentry->d_lock); | |
1670 | ||
1671 | /* | |
1672 | * Recheck the dentry after taking the lock - d_move may have | |
b04f784e NP |
1673 | * changed things. Don't bother checking the hash because |
1674 | * we're about to compare the whole name anyway. | |
1da177e4 LT |
1675 | */ |
1676 | if (dentry->d_parent != parent) | |
1677 | goto next; | |
1678 | ||
d0185c08 LT |
1679 | /* non-existing due to RCU? */ |
1680 | if (d_unhashed(dentry)) | |
1681 | goto next; | |
1682 | ||
1da177e4 LT |
1683 | /* |
1684 | * It is safe to compare names since d_move() cannot | |
1685 | * change the qstr (protected by d_lock). | |
1686 | */ | |
1687 | qstr = &dentry->d_name; | |
1688 | if (parent->d_op && parent->d_op->d_compare) { | |
621e155a NP |
1689 | if (parent->d_op->d_compare(parent, parent->d_inode, |
1690 | dentry, dentry->d_inode, | |
1691 | qstr->len, qstr->name, name)) | |
1da177e4 LT |
1692 | goto next; |
1693 | } else { | |
1694 | if (qstr->len != len) | |
1695 | goto next; | |
1696 | if (memcmp(qstr->name, str, len)) | |
1697 | goto next; | |
1698 | } | |
1699 | ||
b7ab39f6 | 1700 | dentry->d_count++; |
d0185c08 | 1701 | found = dentry; |
1da177e4 LT |
1702 | spin_unlock(&dentry->d_lock); |
1703 | break; | |
1704 | next: | |
1705 | spin_unlock(&dentry->d_lock); | |
1706 | } | |
1707 | rcu_read_unlock(); | |
1708 | ||
1709 | return found; | |
1710 | } | |
1711 | ||
3e7e241f EB |
1712 | /** |
1713 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
1714 | * @dir: Directory to search in | |
1715 | * @name: qstr of name we wish to find | |
1716 | * | |
1717 | * On hash failure or on lookup failure NULL is returned. | |
1718 | */ | |
1719 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
1720 | { | |
1721 | struct dentry *dentry = NULL; | |
1722 | ||
1723 | /* | |
1724 | * Check for a fs-specific hash function. Note that we must | |
1725 | * calculate the standard hash first, as the d_op->d_hash() | |
1726 | * routine may choose to leave the hash value unchanged. | |
1727 | */ | |
1728 | name->hash = full_name_hash(name->name, name->len); | |
1729 | if (dir->d_op && dir->d_op->d_hash) { | |
b1e6a015 | 1730 | if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) |
3e7e241f EB |
1731 | goto out; |
1732 | } | |
1733 | dentry = d_lookup(dir, name); | |
1734 | out: | |
1735 | return dentry; | |
1736 | } | |
1737 | ||
1da177e4 | 1738 | /** |
786a5e15 | 1739 | * d_validate - verify dentry provided from insecure source (deprecated) |
1da177e4 LT |
1740 | * @dentry: The dentry alleged to be valid child of @dparent |
1741 | * @dparent: The parent dentry (known to be valid) | |
1da177e4 LT |
1742 | * |
1743 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
1744 | * This is used by ncpfs in its readdir implementation. | |
1745 | * Zero is returned in the dentry is invalid. | |
786a5e15 NP |
1746 | * |
1747 | * This function is slow for big directories, and deprecated, do not use it. | |
1da177e4 | 1748 | */ |
d3a23e16 | 1749 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
1da177e4 | 1750 | { |
786a5e15 | 1751 | struct dentry *child; |
d3a23e16 NP |
1752 | |
1753 | spin_lock(&dcache_lock); | |
2fd6b7f5 | 1754 | spin_lock(&dparent->d_lock); |
786a5e15 NP |
1755 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
1756 | if (dentry == child) { | |
2fd6b7f5 NP |
1757 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1758 | __dget_locked_dlock(dentry); | |
1759 | spin_unlock(&dentry->d_lock); | |
1760 | spin_unlock(&dparent->d_lock); | |
d3a23e16 | 1761 | spin_unlock(&dcache_lock); |
1da177e4 LT |
1762 | return 1; |
1763 | } | |
1764 | } | |
2fd6b7f5 | 1765 | spin_unlock(&dparent->d_lock); |
d3a23e16 | 1766 | spin_unlock(&dcache_lock); |
786a5e15 | 1767 | |
1da177e4 LT |
1768 | return 0; |
1769 | } | |
ec4f8605 | 1770 | EXPORT_SYMBOL(d_validate); |
1da177e4 LT |
1771 | |
1772 | /* | |
1773 | * When a file is deleted, we have two options: | |
1774 | * - turn this dentry into a negative dentry | |
1775 | * - unhash this dentry and free it. | |
1776 | * | |
1777 | * Usually, we want to just turn this into | |
1778 | * a negative dentry, but if anybody else is | |
1779 | * currently using the dentry or the inode | |
1780 | * we can't do that and we fall back on removing | |
1781 | * it from the hash queues and waiting for | |
1782 | * it to be deleted later when it has no users | |
1783 | */ | |
1784 | ||
1785 | /** | |
1786 | * d_delete - delete a dentry | |
1787 | * @dentry: The dentry to delete | |
1788 | * | |
1789 | * Turn the dentry into a negative dentry if possible, otherwise | |
1790 | * remove it from the hash queues so it can be deleted later | |
1791 | */ | |
1792 | ||
1793 | void d_delete(struct dentry * dentry) | |
1794 | { | |
7a91bf7f | 1795 | int isdir = 0; |
1da177e4 LT |
1796 | /* |
1797 | * Are we the only user? | |
1798 | */ | |
1799 | spin_lock(&dcache_lock); | |
1800 | spin_lock(&dentry->d_lock); | |
7a91bf7f | 1801 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
b7ab39f6 | 1802 | if (dentry->d_count == 1) { |
13e3c5e5 | 1803 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
1da177e4 | 1804 | dentry_iput(dentry); |
7a91bf7f | 1805 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
1806 | return; |
1807 | } | |
1808 | ||
1809 | if (!d_unhashed(dentry)) | |
1810 | __d_drop(dentry); | |
1811 | ||
1812 | spin_unlock(&dentry->d_lock); | |
1813 | spin_unlock(&dcache_lock); | |
7a91bf7f JM |
1814 | |
1815 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 1816 | } |
ec4f8605 | 1817 | EXPORT_SYMBOL(d_delete); |
1da177e4 LT |
1818 | |
1819 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) | |
1820 | { | |
1821 | ||
1822 | entry->d_flags &= ~DCACHE_UNHASHED; | |
1823 | hlist_add_head_rcu(&entry->d_hash, list); | |
1824 | } | |
1825 | ||
770bfad8 DH |
1826 | static void _d_rehash(struct dentry * entry) |
1827 | { | |
1828 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
1829 | } | |
1830 | ||
1da177e4 LT |
1831 | /** |
1832 | * d_rehash - add an entry back to the hash | |
1833 | * @entry: dentry to add to the hash | |
1834 | * | |
1835 | * Adds a dentry to the hash according to its name. | |
1836 | */ | |
1837 | ||
1838 | void d_rehash(struct dentry * entry) | |
1839 | { | |
1da177e4 LT |
1840 | spin_lock(&dcache_lock); |
1841 | spin_lock(&entry->d_lock); | |
789680d1 | 1842 | spin_lock(&dcache_hash_lock); |
770bfad8 | 1843 | _d_rehash(entry); |
789680d1 | 1844 | spin_unlock(&dcache_hash_lock); |
1da177e4 LT |
1845 | spin_unlock(&entry->d_lock); |
1846 | spin_unlock(&dcache_lock); | |
1847 | } | |
ec4f8605 | 1848 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 1849 | |
fb2d5b86 NP |
1850 | /** |
1851 | * dentry_update_name_case - update case insensitive dentry with a new name | |
1852 | * @dentry: dentry to be updated | |
1853 | * @name: new name | |
1854 | * | |
1855 | * Update a case insensitive dentry with new case of name. | |
1856 | * | |
1857 | * dentry must have been returned by d_lookup with name @name. Old and new | |
1858 | * name lengths must match (ie. no d_compare which allows mismatched name | |
1859 | * lengths). | |
1860 | * | |
1861 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
1862 | * keep renames and concurrent inserts, and readdir(2) away). | |
1863 | */ | |
1864 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
1865 | { | |
1866 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
1867 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ | |
1868 | ||
1869 | spin_lock(&dcache_lock); | |
1870 | spin_lock(&dentry->d_lock); | |
1871 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); | |
1872 | spin_unlock(&dentry->d_lock); | |
1873 | spin_unlock(&dcache_lock); | |
1874 | } | |
1875 | EXPORT_SYMBOL(dentry_update_name_case); | |
1876 | ||
1da177e4 LT |
1877 | static void switch_names(struct dentry *dentry, struct dentry *target) |
1878 | { | |
1879 | if (dname_external(target)) { | |
1880 | if (dname_external(dentry)) { | |
1881 | /* | |
1882 | * Both external: swap the pointers | |
1883 | */ | |
9a8d5bb4 | 1884 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
1885 | } else { |
1886 | /* | |
1887 | * dentry:internal, target:external. Steal target's | |
1888 | * storage and make target internal. | |
1889 | */ | |
321bcf92 BF |
1890 | memcpy(target->d_iname, dentry->d_name.name, |
1891 | dentry->d_name.len + 1); | |
1da177e4 LT |
1892 | dentry->d_name.name = target->d_name.name; |
1893 | target->d_name.name = target->d_iname; | |
1894 | } | |
1895 | } else { | |
1896 | if (dname_external(dentry)) { | |
1897 | /* | |
1898 | * dentry:external, target:internal. Give dentry's | |
1899 | * storage to target and make dentry internal | |
1900 | */ | |
1901 | memcpy(dentry->d_iname, target->d_name.name, | |
1902 | target->d_name.len + 1); | |
1903 | target->d_name.name = dentry->d_name.name; | |
1904 | dentry->d_name.name = dentry->d_iname; | |
1905 | } else { | |
1906 | /* | |
1907 | * Both are internal. Just copy target to dentry | |
1908 | */ | |
1909 | memcpy(dentry->d_iname, target->d_name.name, | |
1910 | target->d_name.len + 1); | |
dc711ca3 AV |
1911 | dentry->d_name.len = target->d_name.len; |
1912 | return; | |
1da177e4 LT |
1913 | } |
1914 | } | |
9a8d5bb4 | 1915 | swap(dentry->d_name.len, target->d_name.len); |
1da177e4 LT |
1916 | } |
1917 | ||
2fd6b7f5 NP |
1918 | static void dentry_lock_for_move(struct dentry *dentry, struct dentry *target) |
1919 | { | |
1920 | /* | |
1921 | * XXXX: do we really need to take target->d_lock? | |
1922 | */ | |
1923 | if (IS_ROOT(dentry) || dentry->d_parent == target->d_parent) | |
1924 | spin_lock(&target->d_parent->d_lock); | |
1925 | else { | |
1926 | if (d_ancestor(dentry->d_parent, target->d_parent)) { | |
1927 | spin_lock(&dentry->d_parent->d_lock); | |
1928 | spin_lock_nested(&target->d_parent->d_lock, | |
1929 | DENTRY_D_LOCK_NESTED); | |
1930 | } else { | |
1931 | spin_lock(&target->d_parent->d_lock); | |
1932 | spin_lock_nested(&dentry->d_parent->d_lock, | |
1933 | DENTRY_D_LOCK_NESTED); | |
1934 | } | |
1935 | } | |
1936 | if (target < dentry) { | |
1937 | spin_lock_nested(&target->d_lock, 2); | |
1938 | spin_lock_nested(&dentry->d_lock, 3); | |
1939 | } else { | |
1940 | spin_lock_nested(&dentry->d_lock, 2); | |
1941 | spin_lock_nested(&target->d_lock, 3); | |
1942 | } | |
1943 | } | |
1944 | ||
1945 | static void dentry_unlock_parents_for_move(struct dentry *dentry, | |
1946 | struct dentry *target) | |
1947 | { | |
1948 | if (target->d_parent != dentry->d_parent) | |
1949 | spin_unlock(&dentry->d_parent->d_lock); | |
1950 | if (target->d_parent != target) | |
1951 | spin_unlock(&target->d_parent->d_lock); | |
1952 | } | |
1953 | ||
1da177e4 | 1954 | /* |
2fd6b7f5 NP |
1955 | * When switching names, the actual string doesn't strictly have to |
1956 | * be preserved in the target - because we're dropping the target | |
1957 | * anyway. As such, we can just do a simple memcpy() to copy over | |
1958 | * the new name before we switch. | |
1959 | * | |
1960 | * Note that we have to be a lot more careful about getting the hash | |
1961 | * switched - we have to switch the hash value properly even if it | |
1962 | * then no longer matches the actual (corrupted) string of the target. | |
1963 | * The hash value has to match the hash queue that the dentry is on.. | |
1da177e4 | 1964 | */ |
9eaef27b TM |
1965 | /* |
1966 | * d_move_locked - move a dentry | |
1da177e4 LT |
1967 | * @dentry: entry to move |
1968 | * @target: new dentry | |
1969 | * | |
1970 | * Update the dcache to reflect the move of a file name. Negative | |
1971 | * dcache entries should not be moved in this way. | |
1972 | */ | |
9eaef27b | 1973 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
1da177e4 | 1974 | { |
1da177e4 LT |
1975 | if (!dentry->d_inode) |
1976 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
1977 | ||
2fd6b7f5 NP |
1978 | BUG_ON(d_ancestor(dentry, target)); |
1979 | BUG_ON(d_ancestor(target, dentry)); | |
1980 | ||
1da177e4 | 1981 | write_seqlock(&rename_lock); |
2fd6b7f5 NP |
1982 | |
1983 | dentry_lock_for_move(dentry, target); | |
1da177e4 LT |
1984 | |
1985 | /* Move the dentry to the target hash queue, if on different bucket */ | |
789680d1 NP |
1986 | spin_lock(&dcache_hash_lock); |
1987 | if (!d_unhashed(dentry)) | |
1988 | hlist_del_rcu(&dentry->d_hash); | |
1989 | __d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash)); | |
1990 | spin_unlock(&dcache_hash_lock); | |
1da177e4 LT |
1991 | |
1992 | /* Unhash the target: dput() will then get rid of it */ | |
1993 | __d_drop(target); | |
1994 | ||
5160ee6f ED |
1995 | list_del(&dentry->d_u.d_child); |
1996 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
1997 | |
1998 | /* Switch the names.. */ | |
1999 | switch_names(dentry, target); | |
9a8d5bb4 | 2000 | swap(dentry->d_name.hash, target->d_name.hash); |
1da177e4 LT |
2001 | |
2002 | /* ... and switch the parents */ | |
2003 | if (IS_ROOT(dentry)) { | |
2004 | dentry->d_parent = target->d_parent; | |
2005 | target->d_parent = target; | |
5160ee6f | 2006 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 | 2007 | } else { |
9a8d5bb4 | 2008 | swap(dentry->d_parent, target->d_parent); |
1da177e4 LT |
2009 | |
2010 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 2011 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
2012 | } |
2013 | ||
5160ee6f | 2014 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
2fd6b7f5 NP |
2015 | |
2016 | dentry_unlock_parents_for_move(dentry, target); | |
1da177e4 | 2017 | spin_unlock(&target->d_lock); |
c32ccd87 | 2018 | fsnotify_d_move(dentry); |
1da177e4 LT |
2019 | spin_unlock(&dentry->d_lock); |
2020 | write_sequnlock(&rename_lock); | |
9eaef27b TM |
2021 | } |
2022 | ||
2023 | /** | |
2024 | * d_move - move a dentry | |
2025 | * @dentry: entry to move | |
2026 | * @target: new dentry | |
2027 | * | |
2028 | * Update the dcache to reflect the move of a file name. Negative | |
2029 | * dcache entries should not be moved in this way. | |
2030 | */ | |
2031 | ||
2032 | void d_move(struct dentry * dentry, struct dentry * target) | |
2033 | { | |
2034 | spin_lock(&dcache_lock); | |
2035 | d_move_locked(dentry, target); | |
1da177e4 LT |
2036 | spin_unlock(&dcache_lock); |
2037 | } | |
ec4f8605 | 2038 | EXPORT_SYMBOL(d_move); |
1da177e4 | 2039 | |
e2761a11 OH |
2040 | /** |
2041 | * d_ancestor - search for an ancestor | |
2042 | * @p1: ancestor dentry | |
2043 | * @p2: child dentry | |
2044 | * | |
2045 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
2046 | * an ancestor of p2, else NULL. | |
9eaef27b | 2047 | */ |
e2761a11 | 2048 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
2049 | { |
2050 | struct dentry *p; | |
2051 | ||
871c0067 | 2052 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 2053 | if (p->d_parent == p1) |
e2761a11 | 2054 | return p; |
9eaef27b | 2055 | } |
e2761a11 | 2056 | return NULL; |
9eaef27b TM |
2057 | } |
2058 | ||
2059 | /* | |
2060 | * This helper attempts to cope with remotely renamed directories | |
2061 | * | |
2062 | * It assumes that the caller is already holding | |
2063 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock | |
2064 | * | |
2065 | * Note: If ever the locking in lock_rename() changes, then please | |
2066 | * remember to update this too... | |
9eaef27b TM |
2067 | */ |
2068 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) | |
31f3e0b3 | 2069 | __releases(dcache_lock) |
9eaef27b TM |
2070 | { |
2071 | struct mutex *m1 = NULL, *m2 = NULL; | |
2072 | struct dentry *ret; | |
2073 | ||
2074 | /* If alias and dentry share a parent, then no extra locks required */ | |
2075 | if (alias->d_parent == dentry->d_parent) | |
2076 | goto out_unalias; | |
2077 | ||
2078 | /* Check for loops */ | |
2079 | ret = ERR_PTR(-ELOOP); | |
e2761a11 | 2080 | if (d_ancestor(alias, dentry)) |
9eaef27b TM |
2081 | goto out_err; |
2082 | ||
2083 | /* See lock_rename() */ | |
2084 | ret = ERR_PTR(-EBUSY); | |
2085 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) | |
2086 | goto out_err; | |
2087 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
2088 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
2089 | goto out_err; | |
2090 | m2 = &alias->d_parent->d_inode->i_mutex; | |
2091 | out_unalias: | |
2092 | d_move_locked(alias, dentry); | |
2093 | ret = alias; | |
2094 | out_err: | |
2095 | spin_unlock(&dcache_lock); | |
2096 | if (m2) | |
2097 | mutex_unlock(m2); | |
2098 | if (m1) | |
2099 | mutex_unlock(m1); | |
2100 | return ret; | |
2101 | } | |
2102 | ||
770bfad8 DH |
2103 | /* |
2104 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
2105 | * named dentry in place of the dentry to be replaced. | |
2fd6b7f5 | 2106 | * returns with anon->d_lock held! |
770bfad8 DH |
2107 | */ |
2108 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
2109 | { | |
2110 | struct dentry *dparent, *aparent; | |
2111 | ||
2fd6b7f5 | 2112 | dentry_lock_for_move(anon, dentry); |
770bfad8 DH |
2113 | |
2114 | dparent = dentry->d_parent; | |
2115 | aparent = anon->d_parent; | |
2116 | ||
2fd6b7f5 NP |
2117 | switch_names(dentry, anon); |
2118 | swap(dentry->d_name.hash, anon->d_name.hash); | |
2119 | ||
770bfad8 DH |
2120 | dentry->d_parent = (aparent == anon) ? dentry : aparent; |
2121 | list_del(&dentry->d_u.d_child); | |
2122 | if (!IS_ROOT(dentry)) | |
2123 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); | |
2124 | else | |
2125 | INIT_LIST_HEAD(&dentry->d_u.d_child); | |
2126 | ||
2127 | anon->d_parent = (dparent == dentry) ? anon : dparent; | |
2128 | list_del(&anon->d_u.d_child); | |
2129 | if (!IS_ROOT(anon)) | |
2130 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); | |
2131 | else | |
2132 | INIT_LIST_HEAD(&anon->d_u.d_child); | |
2133 | ||
2fd6b7f5 NP |
2134 | dentry_unlock_parents_for_move(anon, dentry); |
2135 | spin_unlock(&dentry->d_lock); | |
2136 | ||
2137 | /* anon->d_lock still locked, returns locked */ | |
770bfad8 DH |
2138 | anon->d_flags &= ~DCACHE_DISCONNECTED; |
2139 | } | |
2140 | ||
2141 | /** | |
2142 | * d_materialise_unique - introduce an inode into the tree | |
2143 | * @dentry: candidate dentry | |
2144 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
2145 | * | |
2146 | * Introduces an dentry into the tree, substituting an extant disconnected | |
2147 | * root directory alias in its place if there is one | |
2148 | */ | |
2149 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
2150 | { | |
9eaef27b | 2151 | struct dentry *actual; |
770bfad8 DH |
2152 | |
2153 | BUG_ON(!d_unhashed(dentry)); | |
2154 | ||
2155 | spin_lock(&dcache_lock); | |
2156 | ||
2157 | if (!inode) { | |
2158 | actual = dentry; | |
360da900 | 2159 | __d_instantiate(dentry, NULL); |
770bfad8 DH |
2160 | goto found_lock; |
2161 | } | |
2162 | ||
9eaef27b TM |
2163 | if (S_ISDIR(inode->i_mode)) { |
2164 | struct dentry *alias; | |
2165 | ||
2166 | /* Does an aliased dentry already exist? */ | |
2167 | alias = __d_find_alias(inode, 0); | |
2168 | if (alias) { | |
2169 | actual = alias; | |
2170 | /* Is this an anonymous mountpoint that we could splice | |
2171 | * into our tree? */ | |
2172 | if (IS_ROOT(alias)) { | |
9eaef27b TM |
2173 | __d_materialise_dentry(dentry, alias); |
2174 | __d_drop(alias); | |
2175 | goto found; | |
2176 | } | |
2177 | /* Nope, but we must(!) avoid directory aliasing */ | |
2178 | actual = __d_unalias(dentry, alias); | |
2179 | if (IS_ERR(actual)) | |
2180 | dput(alias); | |
2181 | goto out_nolock; | |
2182 | } | |
770bfad8 DH |
2183 | } |
2184 | ||
2185 | /* Add a unique reference */ | |
2186 | actual = __d_instantiate_unique(dentry, inode); | |
2187 | if (!actual) | |
2188 | actual = dentry; | |
2189 | else if (unlikely(!d_unhashed(actual))) | |
2190 | goto shouldnt_be_hashed; | |
2191 | ||
2192 | found_lock: | |
2193 | spin_lock(&actual->d_lock); | |
2194 | found: | |
789680d1 | 2195 | spin_lock(&dcache_hash_lock); |
770bfad8 | 2196 | _d_rehash(actual); |
789680d1 | 2197 | spin_unlock(&dcache_hash_lock); |
770bfad8 DH |
2198 | spin_unlock(&actual->d_lock); |
2199 | spin_unlock(&dcache_lock); | |
9eaef27b | 2200 | out_nolock: |
770bfad8 DH |
2201 | if (actual == dentry) { |
2202 | security_d_instantiate(dentry, inode); | |
2203 | return NULL; | |
2204 | } | |
2205 | ||
2206 | iput(inode); | |
2207 | return actual; | |
2208 | ||
770bfad8 DH |
2209 | shouldnt_be_hashed: |
2210 | spin_unlock(&dcache_lock); | |
2211 | BUG(); | |
770bfad8 | 2212 | } |
ec4f8605 | 2213 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
770bfad8 | 2214 | |
cdd16d02 | 2215 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
2216 | { |
2217 | *buflen -= namelen; | |
2218 | if (*buflen < 0) | |
2219 | return -ENAMETOOLONG; | |
2220 | *buffer -= namelen; | |
2221 | memcpy(*buffer, str, namelen); | |
2222 | return 0; | |
2223 | } | |
2224 | ||
cdd16d02 MS |
2225 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
2226 | { | |
2227 | return prepend(buffer, buflen, name->name, name->len); | |
2228 | } | |
2229 | ||
1da177e4 | 2230 | /** |
f2eb6575 MS |
2231 | * Prepend path string to a buffer |
2232 | * | |
9d1bc601 MS |
2233 | * @path: the dentry/vfsmount to report |
2234 | * @root: root vfsmnt/dentry (may be modified by this function) | |
f2eb6575 MS |
2235 | * @buffer: pointer to the end of the buffer |
2236 | * @buflen: pointer to buffer length | |
552ce544 | 2237 | * |
f2eb6575 | 2238 | * Caller holds the dcache_lock. |
9d1bc601 MS |
2239 | * |
2240 | * If path is not reachable from the supplied root, then the value of | |
2241 | * root is changed (without modifying refcounts). | |
1da177e4 | 2242 | */ |
f2eb6575 MS |
2243 | static int prepend_path(const struct path *path, struct path *root, |
2244 | char **buffer, int *buflen) | |
1da177e4 | 2245 | { |
9d1bc601 MS |
2246 | struct dentry *dentry = path->dentry; |
2247 | struct vfsmount *vfsmnt = path->mnt; | |
f2eb6575 MS |
2248 | bool slash = false; |
2249 | int error = 0; | |
6092d048 | 2250 | |
99b7db7b | 2251 | br_read_lock(vfsmount_lock); |
f2eb6575 | 2252 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
2253 | struct dentry * parent; |
2254 | ||
1da177e4 | 2255 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 2256 | /* Global root? */ |
1da177e4 | 2257 | if (vfsmnt->mnt_parent == vfsmnt) { |
1da177e4 LT |
2258 | goto global_root; |
2259 | } | |
2260 | dentry = vfsmnt->mnt_mountpoint; | |
2261 | vfsmnt = vfsmnt->mnt_parent; | |
1da177e4 LT |
2262 | continue; |
2263 | } | |
2264 | parent = dentry->d_parent; | |
2265 | prefetch(parent); | |
f2eb6575 MS |
2266 | error = prepend_name(buffer, buflen, &dentry->d_name); |
2267 | if (!error) | |
2268 | error = prepend(buffer, buflen, "/", 1); | |
2269 | if (error) | |
2270 | break; | |
2271 | ||
2272 | slash = true; | |
1da177e4 LT |
2273 | dentry = parent; |
2274 | } | |
2275 | ||
be285c71 | 2276 | out: |
f2eb6575 MS |
2277 | if (!error && !slash) |
2278 | error = prepend(buffer, buflen, "/", 1); | |
2279 | ||
99b7db7b | 2280 | br_read_unlock(vfsmount_lock); |
f2eb6575 | 2281 | return error; |
1da177e4 LT |
2282 | |
2283 | global_root: | |
98dc568b MS |
2284 | /* |
2285 | * Filesystems needing to implement special "root names" | |
2286 | * should do so with ->d_dname() | |
2287 | */ | |
2288 | if (IS_ROOT(dentry) && | |
2289 | (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { | |
2290 | WARN(1, "Root dentry has weird name <%.*s>\n", | |
2291 | (int) dentry->d_name.len, dentry->d_name.name); | |
2292 | } | |
9d1bc601 MS |
2293 | root->mnt = vfsmnt; |
2294 | root->dentry = dentry; | |
be285c71 | 2295 | goto out; |
f2eb6575 | 2296 | } |
be285c71 | 2297 | |
f2eb6575 MS |
2298 | /** |
2299 | * __d_path - return the path of a dentry | |
2300 | * @path: the dentry/vfsmount to report | |
2301 | * @root: root vfsmnt/dentry (may be modified by this function) | |
cd956a1c | 2302 | * @buf: buffer to return value in |
f2eb6575 MS |
2303 | * @buflen: buffer length |
2304 | * | |
ffd1f4ed | 2305 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
2306 | * |
2307 | * Returns a pointer into the buffer or an error code if the | |
2308 | * path was too long. | |
2309 | * | |
be148247 | 2310 | * "buflen" should be positive. |
f2eb6575 MS |
2311 | * |
2312 | * If path is not reachable from the supplied root, then the value of | |
2313 | * root is changed (without modifying refcounts). | |
2314 | */ | |
2315 | char *__d_path(const struct path *path, struct path *root, | |
2316 | char *buf, int buflen) | |
2317 | { | |
2318 | char *res = buf + buflen; | |
2319 | int error; | |
2320 | ||
2321 | prepend(&res, &buflen, "\0", 1); | |
be148247 | 2322 | spin_lock(&dcache_lock); |
f2eb6575 | 2323 | error = prepend_path(path, root, &res, &buflen); |
be148247 CH |
2324 | spin_unlock(&dcache_lock); |
2325 | ||
f2eb6575 MS |
2326 | if (error) |
2327 | return ERR_PTR(error); | |
f2eb6575 | 2328 | return res; |
1da177e4 LT |
2329 | } |
2330 | ||
ffd1f4ed MS |
2331 | /* |
2332 | * same as __d_path but appends "(deleted)" for unlinked files. | |
2333 | */ | |
2334 | static int path_with_deleted(const struct path *path, struct path *root, | |
2335 | char **buf, int *buflen) | |
2336 | { | |
2337 | prepend(buf, buflen, "\0", 1); | |
2338 | if (d_unlinked(path->dentry)) { | |
2339 | int error = prepend(buf, buflen, " (deleted)", 10); | |
2340 | if (error) | |
2341 | return error; | |
2342 | } | |
2343 | ||
2344 | return prepend_path(path, root, buf, buflen); | |
2345 | } | |
2346 | ||
8df9d1a4 MS |
2347 | static int prepend_unreachable(char **buffer, int *buflen) |
2348 | { | |
2349 | return prepend(buffer, buflen, "(unreachable)", 13); | |
2350 | } | |
2351 | ||
a03a8a70 JB |
2352 | /** |
2353 | * d_path - return the path of a dentry | |
cf28b486 | 2354 | * @path: path to report |
a03a8a70 JB |
2355 | * @buf: buffer to return value in |
2356 | * @buflen: buffer length | |
2357 | * | |
2358 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
2359 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
2360 | * | |
52afeefb AV |
2361 | * Returns a pointer into the buffer or an error code if the path was |
2362 | * too long. Note: Callers should use the returned pointer, not the passed | |
2363 | * in buffer, to use the name! The implementation often starts at an offset | |
2364 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 2365 | * |
31f3e0b3 | 2366 | * "buflen" should be positive. |
a03a8a70 | 2367 | */ |
20d4fdc1 | 2368 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 2369 | { |
ffd1f4ed | 2370 | char *res = buf + buflen; |
6ac08c39 | 2371 | struct path root; |
9d1bc601 | 2372 | struct path tmp; |
ffd1f4ed | 2373 | int error; |
1da177e4 | 2374 | |
c23fbb6b ED |
2375 | /* |
2376 | * We have various synthetic filesystems that never get mounted. On | |
2377 | * these filesystems dentries are never used for lookup purposes, and | |
2378 | * thus don't need to be hashed. They also don't need a name until a | |
2379 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
2380 | * below allows us to generate a name for these objects on demand: | |
2381 | */ | |
cf28b486 JB |
2382 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2383 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
c23fbb6b | 2384 | |
f7ad3c6b | 2385 | get_fs_root(current->fs, &root); |
552ce544 | 2386 | spin_lock(&dcache_lock); |
9d1bc601 | 2387 | tmp = root; |
ffd1f4ed MS |
2388 | error = path_with_deleted(path, &tmp, &res, &buflen); |
2389 | if (error) | |
2390 | res = ERR_PTR(error); | |
552ce544 | 2391 | spin_unlock(&dcache_lock); |
6ac08c39 | 2392 | path_put(&root); |
1da177e4 LT |
2393 | return res; |
2394 | } | |
ec4f8605 | 2395 | EXPORT_SYMBOL(d_path); |
1da177e4 | 2396 | |
8df9d1a4 MS |
2397 | /** |
2398 | * d_path_with_unreachable - return the path of a dentry | |
2399 | * @path: path to report | |
2400 | * @buf: buffer to return value in | |
2401 | * @buflen: buffer length | |
2402 | * | |
2403 | * The difference from d_path() is that this prepends "(unreachable)" | |
2404 | * to paths which are unreachable from the current process' root. | |
2405 | */ | |
2406 | char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) | |
2407 | { | |
2408 | char *res = buf + buflen; | |
2409 | struct path root; | |
2410 | struct path tmp; | |
2411 | int error; | |
2412 | ||
2413 | if (path->dentry->d_op && path->dentry->d_op->d_dname) | |
2414 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
2415 | ||
2416 | get_fs_root(current->fs, &root); | |
2417 | spin_lock(&dcache_lock); | |
2418 | tmp = root; | |
2419 | error = path_with_deleted(path, &tmp, &res, &buflen); | |
2420 | if (!error && !path_equal(&tmp, &root)) | |
2421 | error = prepend_unreachable(&res, &buflen); | |
2422 | spin_unlock(&dcache_lock); | |
2423 | path_put(&root); | |
2424 | if (error) | |
2425 | res = ERR_PTR(error); | |
2426 | ||
2427 | return res; | |
2428 | } | |
2429 | ||
c23fbb6b ED |
2430 | /* |
2431 | * Helper function for dentry_operations.d_dname() members | |
2432 | */ | |
2433 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
2434 | const char *fmt, ...) | |
2435 | { | |
2436 | va_list args; | |
2437 | char temp[64]; | |
2438 | int sz; | |
2439 | ||
2440 | va_start(args, fmt); | |
2441 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
2442 | va_end(args); | |
2443 | ||
2444 | if (sz > sizeof(temp) || sz > buflen) | |
2445 | return ERR_PTR(-ENAMETOOLONG); | |
2446 | ||
2447 | buffer += buflen - sz; | |
2448 | return memcpy(buffer, temp, sz); | |
2449 | } | |
2450 | ||
6092d048 RP |
2451 | /* |
2452 | * Write full pathname from the root of the filesystem into the buffer. | |
2453 | */ | |
ec2447c2 | 2454 | static char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
6092d048 RP |
2455 | { |
2456 | char *end = buf + buflen; | |
2457 | char *retval; | |
2458 | ||
6092d048 | 2459 | prepend(&end, &buflen, "\0", 1); |
6092d048 RP |
2460 | if (buflen < 1) |
2461 | goto Elong; | |
2462 | /* Get '/' right */ | |
2463 | retval = end-1; | |
2464 | *retval = '/'; | |
2465 | ||
cdd16d02 MS |
2466 | while (!IS_ROOT(dentry)) { |
2467 | struct dentry *parent = dentry->d_parent; | |
6092d048 | 2468 | |
6092d048 | 2469 | prefetch(parent); |
cdd16d02 | 2470 | if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || |
6092d048 RP |
2471 | (prepend(&end, &buflen, "/", 1) != 0)) |
2472 | goto Elong; | |
2473 | ||
2474 | retval = end; | |
2475 | dentry = parent; | |
2476 | } | |
c103135c AV |
2477 | return retval; |
2478 | Elong: | |
2479 | return ERR_PTR(-ENAMETOOLONG); | |
2480 | } | |
ec2447c2 NP |
2481 | |
2482 | char *dentry_path_raw(struct dentry *dentry, char *buf, int buflen) | |
2483 | { | |
2484 | char *retval; | |
2485 | ||
2486 | spin_lock(&dcache_lock); | |
2487 | retval = __dentry_path(dentry, buf, buflen); | |
2488 | spin_unlock(&dcache_lock); | |
2489 | ||
2490 | return retval; | |
2491 | } | |
2492 | EXPORT_SYMBOL(dentry_path_raw); | |
c103135c AV |
2493 | |
2494 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
2495 | { | |
2496 | char *p = NULL; | |
2497 | char *retval; | |
2498 | ||
2499 | spin_lock(&dcache_lock); | |
2500 | if (d_unlinked(dentry)) { | |
2501 | p = buf + buflen; | |
2502 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
2503 | goto Elong; | |
2504 | buflen++; | |
2505 | } | |
2506 | retval = __dentry_path(dentry, buf, buflen); | |
6092d048 | 2507 | spin_unlock(&dcache_lock); |
c103135c AV |
2508 | if (!IS_ERR(retval) && p) |
2509 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
2510 | return retval; |
2511 | Elong: | |
2512 | spin_unlock(&dcache_lock); | |
2513 | return ERR_PTR(-ENAMETOOLONG); | |
2514 | } | |
2515 | ||
1da177e4 LT |
2516 | /* |
2517 | * NOTE! The user-level library version returns a | |
2518 | * character pointer. The kernel system call just | |
2519 | * returns the length of the buffer filled (which | |
2520 | * includes the ending '\0' character), or a negative | |
2521 | * error value. So libc would do something like | |
2522 | * | |
2523 | * char *getcwd(char * buf, size_t size) | |
2524 | * { | |
2525 | * int retval; | |
2526 | * | |
2527 | * retval = sys_getcwd(buf, size); | |
2528 | * if (retval >= 0) | |
2529 | * return buf; | |
2530 | * errno = -retval; | |
2531 | * return NULL; | |
2532 | * } | |
2533 | */ | |
3cdad428 | 2534 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 2535 | { |
552ce544 | 2536 | int error; |
6ac08c39 | 2537 | struct path pwd, root; |
552ce544 | 2538 | char *page = (char *) __get_free_page(GFP_USER); |
1da177e4 LT |
2539 | |
2540 | if (!page) | |
2541 | return -ENOMEM; | |
2542 | ||
f7ad3c6b | 2543 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
1da177e4 | 2544 | |
552ce544 | 2545 | error = -ENOENT; |
552ce544 | 2546 | spin_lock(&dcache_lock); |
f3da392e | 2547 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 2548 | unsigned long len; |
9d1bc601 | 2549 | struct path tmp = root; |
8df9d1a4 MS |
2550 | char *cwd = page + PAGE_SIZE; |
2551 | int buflen = PAGE_SIZE; | |
1da177e4 | 2552 | |
8df9d1a4 MS |
2553 | prepend(&cwd, &buflen, "\0", 1); |
2554 | error = prepend_path(&pwd, &tmp, &cwd, &buflen); | |
552ce544 LT |
2555 | spin_unlock(&dcache_lock); |
2556 | ||
8df9d1a4 | 2557 | if (error) |
552ce544 LT |
2558 | goto out; |
2559 | ||
8df9d1a4 MS |
2560 | /* Unreachable from current root */ |
2561 | if (!path_equal(&tmp, &root)) { | |
2562 | error = prepend_unreachable(&cwd, &buflen); | |
2563 | if (error) | |
2564 | goto out; | |
2565 | } | |
2566 | ||
552ce544 LT |
2567 | error = -ERANGE; |
2568 | len = PAGE_SIZE + page - cwd; | |
2569 | if (len <= size) { | |
2570 | error = len; | |
2571 | if (copy_to_user(buf, cwd, len)) | |
2572 | error = -EFAULT; | |
2573 | } | |
2574 | } else | |
2575 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
2576 | |
2577 | out: | |
6ac08c39 JB |
2578 | path_put(&pwd); |
2579 | path_put(&root); | |
1da177e4 LT |
2580 | free_page((unsigned long) page); |
2581 | return error; | |
2582 | } | |
2583 | ||
2584 | /* | |
2585 | * Test whether new_dentry is a subdirectory of old_dentry. | |
2586 | * | |
2587 | * Trivially implemented using the dcache structure | |
2588 | */ | |
2589 | ||
2590 | /** | |
2591 | * is_subdir - is new dentry a subdirectory of old_dentry | |
2592 | * @new_dentry: new dentry | |
2593 | * @old_dentry: old dentry | |
2594 | * | |
2595 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
2596 | * Returns 0 otherwise. | |
2597 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
2598 | */ | |
2599 | ||
e2761a11 | 2600 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 LT |
2601 | { |
2602 | int result; | |
1da177e4 LT |
2603 | unsigned long seq; |
2604 | ||
e2761a11 OH |
2605 | if (new_dentry == old_dentry) |
2606 | return 1; | |
2607 | ||
2608 | /* | |
2609 | * Need rcu_readlock to protect against the d_parent trashing | |
2610 | * due to d_move | |
1da177e4 LT |
2611 | */ |
2612 | rcu_read_lock(); | |
e2761a11 | 2613 | do { |
1da177e4 | 2614 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 2615 | seq = read_seqbegin(&rename_lock); |
e2761a11 | 2616 | if (d_ancestor(old_dentry, new_dentry)) |
1da177e4 | 2617 | result = 1; |
e2761a11 OH |
2618 | else |
2619 | result = 0; | |
1da177e4 LT |
2620 | } while (read_seqretry(&rename_lock, seq)); |
2621 | rcu_read_unlock(); | |
2622 | ||
2623 | return result; | |
2624 | } | |
2625 | ||
2096f759 AV |
2626 | int path_is_under(struct path *path1, struct path *path2) |
2627 | { | |
2628 | struct vfsmount *mnt = path1->mnt; | |
2629 | struct dentry *dentry = path1->dentry; | |
2630 | int res; | |
99b7db7b NP |
2631 | |
2632 | br_read_lock(vfsmount_lock); | |
2096f759 AV |
2633 | if (mnt != path2->mnt) { |
2634 | for (;;) { | |
2635 | if (mnt->mnt_parent == mnt) { | |
99b7db7b | 2636 | br_read_unlock(vfsmount_lock); |
2096f759 AV |
2637 | return 0; |
2638 | } | |
2639 | if (mnt->mnt_parent == path2->mnt) | |
2640 | break; | |
2641 | mnt = mnt->mnt_parent; | |
2642 | } | |
2643 | dentry = mnt->mnt_mountpoint; | |
2644 | } | |
2645 | res = is_subdir(dentry, path2->dentry); | |
99b7db7b | 2646 | br_read_unlock(vfsmount_lock); |
2096f759 AV |
2647 | return res; |
2648 | } | |
2649 | EXPORT_SYMBOL(path_is_under); | |
2650 | ||
1da177e4 LT |
2651 | void d_genocide(struct dentry *root) |
2652 | { | |
2653 | struct dentry *this_parent = root; | |
2654 | struct list_head *next; | |
2655 | ||
2656 | spin_lock(&dcache_lock); | |
2fd6b7f5 | 2657 | spin_lock(&this_parent->d_lock); |
1da177e4 LT |
2658 | repeat: |
2659 | next = this_parent->d_subdirs.next; | |
2660 | resume: | |
2661 | while (next != &this_parent->d_subdirs) { | |
2662 | struct list_head *tmp = next; | |
5160ee6f | 2663 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 | 2664 | next = tmp->next; |
da502956 NP |
2665 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
2666 | if (d_unhashed(dentry) || !dentry->d_inode) { | |
2667 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 2668 | continue; |
da502956 | 2669 | } |
1da177e4 | 2670 | if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f5 NP |
2671 | spin_unlock(&this_parent->d_lock); |
2672 | spin_release(&dentry->d_lock.dep_map, 1, _RET_IP_); | |
1da177e4 | 2673 | this_parent = dentry; |
2fd6b7f5 | 2674 | spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4 LT |
2675 | goto repeat; |
2676 | } | |
b7ab39f6 NP |
2677 | dentry->d_count--; |
2678 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
2679 | } |
2680 | if (this_parent != root) { | |
5160ee6f | 2681 | next = this_parent->d_u.d_child.next; |
b7ab39f6 NP |
2682 | this_parent->d_count--; |
2683 | spin_unlock(&this_parent->d_lock); | |
1da177e4 | 2684 | this_parent = this_parent->d_parent; |
2fd6b7f5 | 2685 | spin_lock(&this_parent->d_lock); |
1da177e4 LT |
2686 | goto resume; |
2687 | } | |
2fd6b7f5 | 2688 | spin_unlock(&this_parent->d_lock); |
1da177e4 LT |
2689 | spin_unlock(&dcache_lock); |
2690 | } | |
2691 | ||
2692 | /** | |
2693 | * find_inode_number - check for dentry with name | |
2694 | * @dir: directory to check | |
2695 | * @name: Name to find. | |
2696 | * | |
2697 | * Check whether a dentry already exists for the given name, | |
2698 | * and return the inode number if it has an inode. Otherwise | |
2699 | * 0 is returned. | |
2700 | * | |
2701 | * This routine is used to post-process directory listings for | |
2702 | * filesystems using synthetic inode numbers, and is necessary | |
2703 | * to keep getcwd() working. | |
2704 | */ | |
2705 | ||
2706 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) | |
2707 | { | |
2708 | struct dentry * dentry; | |
2709 | ino_t ino = 0; | |
2710 | ||
3e7e241f EB |
2711 | dentry = d_hash_and_lookup(dir, name); |
2712 | if (dentry) { | |
1da177e4 LT |
2713 | if (dentry->d_inode) |
2714 | ino = dentry->d_inode->i_ino; | |
2715 | dput(dentry); | |
2716 | } | |
1da177e4 LT |
2717 | return ino; |
2718 | } | |
ec4f8605 | 2719 | EXPORT_SYMBOL(find_inode_number); |
1da177e4 LT |
2720 | |
2721 | static __initdata unsigned long dhash_entries; | |
2722 | static int __init set_dhash_entries(char *str) | |
2723 | { | |
2724 | if (!str) | |
2725 | return 0; | |
2726 | dhash_entries = simple_strtoul(str, &str, 0); | |
2727 | return 1; | |
2728 | } | |
2729 | __setup("dhash_entries=", set_dhash_entries); | |
2730 | ||
2731 | static void __init dcache_init_early(void) | |
2732 | { | |
2733 | int loop; | |
2734 | ||
2735 | /* If hashes are distributed across NUMA nodes, defer | |
2736 | * hash allocation until vmalloc space is available. | |
2737 | */ | |
2738 | if (hashdist) | |
2739 | return; | |
2740 | ||
2741 | dentry_hashtable = | |
2742 | alloc_large_system_hash("Dentry cache", | |
2743 | sizeof(struct hlist_head), | |
2744 | dhash_entries, | |
2745 | 13, | |
2746 | HASH_EARLY, | |
2747 | &d_hash_shift, | |
2748 | &d_hash_mask, | |
2749 | 0); | |
2750 | ||
2751 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2752 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2753 | } | |
2754 | ||
74bf17cf | 2755 | static void __init dcache_init(void) |
1da177e4 LT |
2756 | { |
2757 | int loop; | |
2758 | ||
2759 | /* | |
2760 | * A constructor could be added for stable state like the lists, | |
2761 | * but it is probably not worth it because of the cache nature | |
2762 | * of the dcache. | |
2763 | */ | |
0a31bd5f CL |
2764 | dentry_cache = KMEM_CACHE(dentry, |
2765 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 | 2766 | |
8e1f936b | 2767 | register_shrinker(&dcache_shrinker); |
1da177e4 LT |
2768 | |
2769 | /* Hash may have been set up in dcache_init_early */ | |
2770 | if (!hashdist) | |
2771 | return; | |
2772 | ||
2773 | dentry_hashtable = | |
2774 | alloc_large_system_hash("Dentry cache", | |
2775 | sizeof(struct hlist_head), | |
2776 | dhash_entries, | |
2777 | 13, | |
2778 | 0, | |
2779 | &d_hash_shift, | |
2780 | &d_hash_mask, | |
2781 | 0); | |
2782 | ||
2783 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2784 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2785 | } | |
2786 | ||
2787 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 2788 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 2789 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 2790 | |
1da177e4 LT |
2791 | EXPORT_SYMBOL(d_genocide); |
2792 | ||
1da177e4 LT |
2793 | void __init vfs_caches_init_early(void) |
2794 | { | |
2795 | dcache_init_early(); | |
2796 | inode_init_early(); | |
2797 | } | |
2798 | ||
2799 | void __init vfs_caches_init(unsigned long mempages) | |
2800 | { | |
2801 | unsigned long reserve; | |
2802 | ||
2803 | /* Base hash sizes on available memory, with a reserve equal to | |
2804 | 150% of current kernel size */ | |
2805 | ||
2806 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
2807 | mempages -= reserve; | |
2808 | ||
2809 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 2810 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 2811 | |
74bf17cf DC |
2812 | dcache_init(); |
2813 | inode_init(); | |
1da177e4 | 2814 | files_init(mempages); |
74bf17cf | 2815 | mnt_init(); |
1da177e4 LT |
2816 | bdev_cache_init(); |
2817 | chrdev_init(); | |
2818 | } |