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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * fs/dcache.c | |
3 | * | |
4 | * Complete reimplementation | |
5 | * (C) 1997 Thomas Schoebel-Theuer, | |
6 | * with heavy changes by Linus Torvalds | |
7 | */ | |
8 | ||
9 | /* | |
10 | * Notes on the allocation strategy: | |
11 | * | |
12 | * The dcache is a master of the icache - whenever a dcache entry | |
13 | * exists, the inode will always exist. "iput()" is done either when | |
14 | * the dcache entry is deleted or garbage collected. | |
15 | */ | |
16 | ||
1da177e4 LT |
17 | #include <linux/syscalls.h> |
18 | #include <linux/string.h> | |
19 | #include <linux/mm.h> | |
20 | #include <linux/fs.h> | |
7a91bf7f | 21 | #include <linux/fsnotify.h> |
1da177e4 LT |
22 | #include <linux/slab.h> |
23 | #include <linux/init.h> | |
1da177e4 LT |
24 | #include <linux/hash.h> |
25 | #include <linux/cache.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/file.h> | |
29 | #include <asm/uaccess.h> | |
30 | #include <linux/security.h> | |
31 | #include <linux/seqlock.h> | |
32 | #include <linux/swap.h> | |
33 | #include <linux/bootmem.h> | |
5ad4e53b | 34 | #include <linux/fs_struct.h> |
613afbf8 | 35 | #include <linux/hardirq.h> |
07f3f05c | 36 | #include "internal.h" |
1da177e4 | 37 | |
fa3536cc | 38 | int sysctl_vfs_cache_pressure __read_mostly = 100; |
1da177e4 LT |
39 | EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
40 | ||
41 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock); | |
74c3cbe3 | 42 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
1da177e4 LT |
43 | |
44 | EXPORT_SYMBOL(dcache_lock); | |
45 | ||
e18b890b | 46 | static struct kmem_cache *dentry_cache __read_mostly; |
1da177e4 LT |
47 | |
48 | #define DNAME_INLINE_LEN (sizeof(struct dentry)-offsetof(struct dentry,d_iname)) | |
49 | ||
50 | /* | |
51 | * This is the single most critical data structure when it comes | |
52 | * to the dcache: the hashtable for lookups. Somebody should try | |
53 | * to make this good - I've just made it work. | |
54 | * | |
55 | * This hash-function tries to avoid losing too many bits of hash | |
56 | * information, yet avoid using a prime hash-size or similar. | |
57 | */ | |
58 | #define D_HASHBITS d_hash_shift | |
59 | #define D_HASHMASK d_hash_mask | |
60 | ||
fa3536cc ED |
61 | static unsigned int d_hash_mask __read_mostly; |
62 | static unsigned int d_hash_shift __read_mostly; | |
63 | static struct hlist_head *dentry_hashtable __read_mostly; | |
1da177e4 LT |
64 | |
65 | /* Statistics gathering. */ | |
66 | struct dentry_stat_t dentry_stat = { | |
67 | .age_limit = 45, | |
68 | }; | |
69 | ||
3e880fb5 | 70 | static DEFINE_PER_CPU(unsigned int, nr_dentry); |
312d3ca8 CH |
71 | |
72 | #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) | |
3e880fb5 NP |
73 | static int get_nr_dentry(void) |
74 | { | |
75 | int i; | |
76 | int sum = 0; | |
77 | for_each_possible_cpu(i) | |
78 | sum += per_cpu(nr_dentry, i); | |
79 | return sum < 0 ? 0 : sum; | |
80 | } | |
81 | ||
312d3ca8 CH |
82 | int proc_nr_dentry(ctl_table *table, int write, void __user *buffer, |
83 | size_t *lenp, loff_t *ppos) | |
84 | { | |
3e880fb5 | 85 | dentry_stat.nr_dentry = get_nr_dentry(); |
312d3ca8 CH |
86 | return proc_dointvec(table, write, buffer, lenp, ppos); |
87 | } | |
88 | #endif | |
89 | ||
9c82ab9c | 90 | static void __d_free(struct rcu_head *head) |
1da177e4 | 91 | { |
9c82ab9c CH |
92 | struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
93 | ||
fd217f4d | 94 | WARN_ON(!list_empty(&dentry->d_alias)); |
1da177e4 LT |
95 | if (dname_external(dentry)) |
96 | kfree(dentry->d_name.name); | |
97 | kmem_cache_free(dentry_cache, dentry); | |
98 | } | |
99 | ||
100 | /* | |
312d3ca8 | 101 | * no dcache_lock, please. |
1da177e4 LT |
102 | */ |
103 | static void d_free(struct dentry *dentry) | |
104 | { | |
3e880fb5 | 105 | this_cpu_dec(nr_dentry); |
1da177e4 LT |
106 | if (dentry->d_op && dentry->d_op->d_release) |
107 | dentry->d_op->d_release(dentry); | |
312d3ca8 | 108 | |
b3423415 | 109 | /* if dentry was never inserted into hash, immediate free is OK */ |
e8462caa | 110 | if (hlist_unhashed(&dentry->d_hash)) |
9c82ab9c | 111 | __d_free(&dentry->d_u.d_rcu); |
b3423415 | 112 | else |
9c82ab9c | 113 | call_rcu(&dentry->d_u.d_rcu, __d_free); |
1da177e4 LT |
114 | } |
115 | ||
116 | /* | |
117 | * Release the dentry's inode, using the filesystem | |
118 | * d_iput() operation if defined. | |
1da177e4 | 119 | */ |
858119e1 | 120 | static void dentry_iput(struct dentry * dentry) |
31f3e0b3 MS |
121 | __releases(dentry->d_lock) |
122 | __releases(dcache_lock) | |
1da177e4 LT |
123 | { |
124 | struct inode *inode = dentry->d_inode; | |
125 | if (inode) { | |
126 | dentry->d_inode = NULL; | |
127 | list_del_init(&dentry->d_alias); | |
128 | spin_unlock(&dentry->d_lock); | |
129 | spin_unlock(&dcache_lock); | |
f805fbda LT |
130 | if (!inode->i_nlink) |
131 | fsnotify_inoderemove(inode); | |
1da177e4 LT |
132 | if (dentry->d_op && dentry->d_op->d_iput) |
133 | dentry->d_op->d_iput(dentry, inode); | |
134 | else | |
135 | iput(inode); | |
136 | } else { | |
137 | spin_unlock(&dentry->d_lock); | |
138 | spin_unlock(&dcache_lock); | |
139 | } | |
140 | } | |
141 | ||
da3bbdd4 | 142 | /* |
a4633357 | 143 | * dentry_lru_(add|del|move_tail) must be called with dcache_lock held. |
da3bbdd4 KM |
144 | */ |
145 | static void dentry_lru_add(struct dentry *dentry) | |
146 | { | |
a4633357 CH |
147 | if (list_empty(&dentry->d_lru)) { |
148 | list_add(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
149 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 150 | dentry_stat.nr_unused++; |
a4633357 | 151 | } |
da3bbdd4 KM |
152 | } |
153 | ||
154 | static void dentry_lru_del(struct dentry *dentry) | |
155 | { | |
156 | if (!list_empty(&dentry->d_lru)) { | |
a4633357 | 157 | list_del_init(&dentry->d_lru); |
da3bbdd4 | 158 | dentry->d_sb->s_nr_dentry_unused--; |
86c8749e | 159 | dentry_stat.nr_unused--; |
da3bbdd4 KM |
160 | } |
161 | } | |
162 | ||
a4633357 | 163 | static void dentry_lru_move_tail(struct dentry *dentry) |
da3bbdd4 | 164 | { |
a4633357 CH |
165 | if (list_empty(&dentry->d_lru)) { |
166 | list_add_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
167 | dentry->d_sb->s_nr_dentry_unused++; | |
86c8749e | 168 | dentry_stat.nr_unused++; |
a4633357 CH |
169 | } else { |
170 | list_move_tail(&dentry->d_lru, &dentry->d_sb->s_dentry_lru); | |
da3bbdd4 KM |
171 | } |
172 | } | |
173 | ||
d52b9086 MS |
174 | /** |
175 | * d_kill - kill dentry and return parent | |
176 | * @dentry: dentry to kill | |
177 | * | |
31f3e0b3 | 178 | * The dentry must already be unhashed and removed from the LRU. |
d52b9086 MS |
179 | * |
180 | * If this is the root of the dentry tree, return NULL. | |
181 | */ | |
182 | static struct dentry *d_kill(struct dentry *dentry) | |
31f3e0b3 MS |
183 | __releases(dentry->d_lock) |
184 | __releases(dcache_lock) | |
d52b9086 MS |
185 | { |
186 | struct dentry *parent; | |
187 | ||
188 | list_del(&dentry->d_u.d_child); | |
d52b9086 MS |
189 | /*drops the locks, at that point nobody can reach this dentry */ |
190 | dentry_iput(dentry); | |
871c0067 OH |
191 | if (IS_ROOT(dentry)) |
192 | parent = NULL; | |
193 | else | |
194 | parent = dentry->d_parent; | |
d52b9086 | 195 | d_free(dentry); |
871c0067 | 196 | return parent; |
d52b9086 MS |
197 | } |
198 | ||
1da177e4 LT |
199 | /* |
200 | * This is dput | |
201 | * | |
202 | * This is complicated by the fact that we do not want to put | |
203 | * dentries that are no longer on any hash chain on the unused | |
204 | * list: we'd much rather just get rid of them immediately. | |
205 | * | |
206 | * However, that implies that we have to traverse the dentry | |
207 | * tree upwards to the parents which might _also_ now be | |
208 | * scheduled for deletion (it may have been only waiting for | |
209 | * its last child to go away). | |
210 | * | |
211 | * This tail recursion is done by hand as we don't want to depend | |
212 | * on the compiler to always get this right (gcc generally doesn't). | |
213 | * Real recursion would eat up our stack space. | |
214 | */ | |
215 | ||
216 | /* | |
217 | * dput - release a dentry | |
218 | * @dentry: dentry to release | |
219 | * | |
220 | * Release a dentry. This will drop the usage count and if appropriate | |
221 | * call the dentry unlink method as well as removing it from the queues and | |
222 | * releasing its resources. If the parent dentries were scheduled for release | |
223 | * they too may now get deleted. | |
224 | * | |
225 | * no dcache lock, please. | |
226 | */ | |
227 | ||
228 | void dput(struct dentry *dentry) | |
229 | { | |
230 | if (!dentry) | |
231 | return; | |
232 | ||
233 | repeat: | |
234 | if (atomic_read(&dentry->d_count) == 1) | |
235 | might_sleep(); | |
236 | if (!atomic_dec_and_lock(&dentry->d_count, &dcache_lock)) | |
237 | return; | |
238 | ||
239 | spin_lock(&dentry->d_lock); | |
240 | if (atomic_read(&dentry->d_count)) { | |
241 | spin_unlock(&dentry->d_lock); | |
242 | spin_unlock(&dcache_lock); | |
243 | return; | |
244 | } | |
245 | ||
246 | /* | |
247 | * AV: ->d_delete() is _NOT_ allowed to block now. | |
248 | */ | |
249 | if (dentry->d_op && dentry->d_op->d_delete) { | |
250 | if (dentry->d_op->d_delete(dentry)) | |
251 | goto unhash_it; | |
252 | } | |
265ac902 | 253 | |
1da177e4 LT |
254 | /* Unreachable? Get rid of it */ |
255 | if (d_unhashed(dentry)) | |
256 | goto kill_it; | |
265ac902 NP |
257 | |
258 | /* Otherwise leave it cached and ensure it's on the LRU */ | |
259 | dentry->d_flags |= DCACHE_REFERENCED; | |
a4633357 | 260 | dentry_lru_add(dentry); |
265ac902 | 261 | |
1da177e4 LT |
262 | spin_unlock(&dentry->d_lock); |
263 | spin_unlock(&dcache_lock); | |
264 | return; | |
265 | ||
266 | unhash_it: | |
267 | __d_drop(dentry); | |
d52b9086 | 268 | kill_it: |
da3bbdd4 KM |
269 | /* if dentry was on the d_lru list delete it from there */ |
270 | dentry_lru_del(dentry); | |
d52b9086 MS |
271 | dentry = d_kill(dentry); |
272 | if (dentry) | |
273 | goto repeat; | |
1da177e4 | 274 | } |
ec4f8605 | 275 | EXPORT_SYMBOL(dput); |
1da177e4 LT |
276 | |
277 | /** | |
278 | * d_invalidate - invalidate a dentry | |
279 | * @dentry: dentry to invalidate | |
280 | * | |
281 | * Try to invalidate the dentry if it turns out to be | |
282 | * possible. If there are other dentries that can be | |
283 | * reached through this one we can't delete it and we | |
284 | * return -EBUSY. On success we return 0. | |
285 | * | |
286 | * no dcache lock. | |
287 | */ | |
288 | ||
289 | int d_invalidate(struct dentry * dentry) | |
290 | { | |
291 | /* | |
292 | * If it's already been dropped, return OK. | |
293 | */ | |
294 | spin_lock(&dcache_lock); | |
295 | if (d_unhashed(dentry)) { | |
296 | spin_unlock(&dcache_lock); | |
297 | return 0; | |
298 | } | |
299 | /* | |
300 | * Check whether to do a partial shrink_dcache | |
301 | * to get rid of unused child entries. | |
302 | */ | |
303 | if (!list_empty(&dentry->d_subdirs)) { | |
304 | spin_unlock(&dcache_lock); | |
305 | shrink_dcache_parent(dentry); | |
306 | spin_lock(&dcache_lock); | |
307 | } | |
308 | ||
309 | /* | |
310 | * Somebody else still using it? | |
311 | * | |
312 | * If it's a directory, we can't drop it | |
313 | * for fear of somebody re-populating it | |
314 | * with children (even though dropping it | |
315 | * would make it unreachable from the root, | |
316 | * we might still populate it if it was a | |
317 | * working directory or similar). | |
318 | */ | |
319 | spin_lock(&dentry->d_lock); | |
320 | if (atomic_read(&dentry->d_count) > 1) { | |
321 | if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) { | |
322 | spin_unlock(&dentry->d_lock); | |
323 | spin_unlock(&dcache_lock); | |
324 | return -EBUSY; | |
325 | } | |
326 | } | |
327 | ||
328 | __d_drop(dentry); | |
329 | spin_unlock(&dentry->d_lock); | |
330 | spin_unlock(&dcache_lock); | |
331 | return 0; | |
332 | } | |
ec4f8605 | 333 | EXPORT_SYMBOL(d_invalidate); |
1da177e4 LT |
334 | |
335 | /* This should be called _only_ with dcache_lock held */ | |
1da177e4 LT |
336 | static inline struct dentry * __dget_locked(struct dentry *dentry) |
337 | { | |
338 | atomic_inc(&dentry->d_count); | |
a4633357 | 339 | dentry_lru_del(dentry); |
1da177e4 LT |
340 | return dentry; |
341 | } | |
342 | ||
343 | struct dentry * dget_locked(struct dentry *dentry) | |
344 | { | |
345 | return __dget_locked(dentry); | |
346 | } | |
ec4f8605 | 347 | EXPORT_SYMBOL(dget_locked); |
1da177e4 LT |
348 | |
349 | /** | |
350 | * d_find_alias - grab a hashed alias of inode | |
351 | * @inode: inode in question | |
352 | * @want_discon: flag, used by d_splice_alias, to request | |
353 | * that only a DISCONNECTED alias be returned. | |
354 | * | |
355 | * If inode has a hashed alias, or is a directory and has any alias, | |
356 | * acquire the reference to alias and return it. Otherwise return NULL. | |
357 | * Notice that if inode is a directory there can be only one alias and | |
358 | * it can be unhashed only if it has no children, or if it is the root | |
359 | * of a filesystem. | |
360 | * | |
21c0d8fd | 361 | * If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
1da177e4 | 362 | * any other hashed alias over that one unless @want_discon is set, |
21c0d8fd | 363 | * in which case only return an IS_ROOT, DCACHE_DISCONNECTED alias. |
1da177e4 LT |
364 | */ |
365 | ||
366 | static struct dentry * __d_find_alias(struct inode *inode, int want_discon) | |
367 | { | |
368 | struct list_head *head, *next, *tmp; | |
369 | struct dentry *alias, *discon_alias=NULL; | |
370 | ||
371 | head = &inode->i_dentry; | |
372 | next = inode->i_dentry.next; | |
373 | while (next != head) { | |
374 | tmp = next; | |
375 | next = tmp->next; | |
376 | prefetch(next); | |
377 | alias = list_entry(tmp, struct dentry, d_alias); | |
378 | if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) { | |
21c0d8fd N |
379 | if (IS_ROOT(alias) && |
380 | (alias->d_flags & DCACHE_DISCONNECTED)) | |
1da177e4 LT |
381 | discon_alias = alias; |
382 | else if (!want_discon) { | |
383 | __dget_locked(alias); | |
384 | return alias; | |
385 | } | |
386 | } | |
387 | } | |
388 | if (discon_alias) | |
389 | __dget_locked(discon_alias); | |
390 | return discon_alias; | |
391 | } | |
392 | ||
393 | struct dentry * d_find_alias(struct inode *inode) | |
394 | { | |
214fda1f DH |
395 | struct dentry *de = NULL; |
396 | ||
397 | if (!list_empty(&inode->i_dentry)) { | |
398 | spin_lock(&dcache_lock); | |
399 | de = __d_find_alias(inode, 0); | |
400 | spin_unlock(&dcache_lock); | |
401 | } | |
1da177e4 LT |
402 | return de; |
403 | } | |
ec4f8605 | 404 | EXPORT_SYMBOL(d_find_alias); |
1da177e4 LT |
405 | |
406 | /* | |
407 | * Try to kill dentries associated with this inode. | |
408 | * WARNING: you must own a reference to inode. | |
409 | */ | |
410 | void d_prune_aliases(struct inode *inode) | |
411 | { | |
0cdca3f9 | 412 | struct dentry *dentry; |
1da177e4 LT |
413 | restart: |
414 | spin_lock(&dcache_lock); | |
0cdca3f9 | 415 | list_for_each_entry(dentry, &inode->i_dentry, d_alias) { |
1da177e4 LT |
416 | spin_lock(&dentry->d_lock); |
417 | if (!atomic_read(&dentry->d_count)) { | |
418 | __dget_locked(dentry); | |
419 | __d_drop(dentry); | |
420 | spin_unlock(&dentry->d_lock); | |
421 | spin_unlock(&dcache_lock); | |
422 | dput(dentry); | |
423 | goto restart; | |
424 | } | |
425 | spin_unlock(&dentry->d_lock); | |
426 | } | |
427 | spin_unlock(&dcache_lock); | |
428 | } | |
ec4f8605 | 429 | EXPORT_SYMBOL(d_prune_aliases); |
1da177e4 LT |
430 | |
431 | /* | |
d702ccb3 AM |
432 | * Throw away a dentry - free the inode, dput the parent. This requires that |
433 | * the LRU list has already been removed. | |
434 | * | |
85864e10 MS |
435 | * Try to prune ancestors as well. This is necessary to prevent |
436 | * quadratic behavior of shrink_dcache_parent(), but is also expected | |
437 | * to be beneficial in reducing dentry cache fragmentation. | |
1da177e4 | 438 | */ |
85864e10 | 439 | static void prune_one_dentry(struct dentry * dentry) |
31f3e0b3 MS |
440 | __releases(dentry->d_lock) |
441 | __releases(dcache_lock) | |
442 | __acquires(dcache_lock) | |
1da177e4 | 443 | { |
1da177e4 | 444 | __d_drop(dentry); |
d52b9086 | 445 | dentry = d_kill(dentry); |
d52b9086 MS |
446 | |
447 | /* | |
448 | * Prune ancestors. Locking is simpler than in dput(), | |
449 | * because dcache_lock needs to be taken anyway. | |
450 | */ | |
1da177e4 | 451 | spin_lock(&dcache_lock); |
d52b9086 MS |
452 | while (dentry) { |
453 | if (!atomic_dec_and_lock(&dentry->d_count, &dentry->d_lock)) | |
454 | return; | |
455 | ||
a4633357 | 456 | dentry_lru_del(dentry); |
d52b9086 MS |
457 | __d_drop(dentry); |
458 | dentry = d_kill(dentry); | |
459 | spin_lock(&dcache_lock); | |
460 | } | |
1da177e4 LT |
461 | } |
462 | ||
3049cfe2 | 463 | static void shrink_dentry_list(struct list_head *list) |
1da177e4 | 464 | { |
da3bbdd4 | 465 | struct dentry *dentry; |
da3bbdd4 | 466 | |
3049cfe2 CH |
467 | while (!list_empty(list)) { |
468 | dentry = list_entry(list->prev, struct dentry, d_lru); | |
a4633357 | 469 | dentry_lru_del(dentry); |
3049cfe2 | 470 | |
1da177e4 LT |
471 | /* |
472 | * We found an inuse dentry which was not removed from | |
da3bbdd4 KM |
473 | * the LRU because of laziness during lookup. Do not free |
474 | * it - just keep it off the LRU list. | |
1da177e4 | 475 | */ |
3049cfe2 | 476 | spin_lock(&dentry->d_lock); |
da3bbdd4 KM |
477 | if (atomic_read(&dentry->d_count)) { |
478 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
479 | continue; |
480 | } | |
da3bbdd4 KM |
481 | prune_one_dentry(dentry); |
482 | /* dentry->d_lock was dropped in prune_one_dentry() */ | |
483 | cond_resched_lock(&dcache_lock); | |
484 | } | |
3049cfe2 CH |
485 | } |
486 | ||
487 | /** | |
488 | * __shrink_dcache_sb - shrink the dentry LRU on a given superblock | |
489 | * @sb: superblock to shrink dentry LRU. | |
490 | * @count: number of entries to prune | |
491 | * @flags: flags to control the dentry processing | |
492 | * | |
493 | * If flags contains DCACHE_REFERENCED reference dentries will not be pruned. | |
494 | */ | |
495 | static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags) | |
496 | { | |
497 | /* called from prune_dcache() and shrink_dcache_parent() */ | |
498 | struct dentry *dentry; | |
499 | LIST_HEAD(referenced); | |
500 | LIST_HEAD(tmp); | |
501 | int cnt = *count; | |
502 | ||
503 | spin_lock(&dcache_lock); | |
504 | while (!list_empty(&sb->s_dentry_lru)) { | |
505 | dentry = list_entry(sb->s_dentry_lru.prev, | |
506 | struct dentry, d_lru); | |
507 | BUG_ON(dentry->d_sb != sb); | |
508 | ||
509 | /* | |
510 | * If we are honouring the DCACHE_REFERENCED flag and the | |
511 | * dentry has this flag set, don't free it. Clear the flag | |
512 | * and put it back on the LRU. | |
513 | */ | |
514 | if (flags & DCACHE_REFERENCED) { | |
515 | spin_lock(&dentry->d_lock); | |
516 | if (dentry->d_flags & DCACHE_REFERENCED) { | |
517 | dentry->d_flags &= ~DCACHE_REFERENCED; | |
518 | list_move(&dentry->d_lru, &referenced); | |
519 | spin_unlock(&dentry->d_lock); | |
520 | cond_resched_lock(&dcache_lock); | |
521 | continue; | |
522 | } | |
523 | spin_unlock(&dentry->d_lock); | |
524 | } | |
525 | ||
526 | list_move_tail(&dentry->d_lru, &tmp); | |
527 | if (!--cnt) | |
528 | break; | |
529 | cond_resched_lock(&dcache_lock); | |
530 | } | |
531 | ||
532 | *count = cnt; | |
533 | shrink_dentry_list(&tmp); | |
534 | ||
da3bbdd4 KM |
535 | if (!list_empty(&referenced)) |
536 | list_splice(&referenced, &sb->s_dentry_lru); | |
537 | spin_unlock(&dcache_lock); | |
3049cfe2 | 538 | |
da3bbdd4 KM |
539 | } |
540 | ||
541 | /** | |
542 | * prune_dcache - shrink the dcache | |
543 | * @count: number of entries to try to free | |
544 | * | |
545 | * Shrink the dcache. This is done when we need more memory, or simply when we | |
546 | * need to unmount something (at which point we need to unuse all dentries). | |
547 | * | |
548 | * This function may fail to free any resources if all the dentries are in use. | |
549 | */ | |
550 | static void prune_dcache(int count) | |
551 | { | |
dca33252 | 552 | struct super_block *sb, *p = NULL; |
da3bbdd4 | 553 | int w_count; |
86c8749e | 554 | int unused = dentry_stat.nr_unused; |
da3bbdd4 KM |
555 | int prune_ratio; |
556 | int pruned; | |
557 | ||
558 | if (unused == 0 || count == 0) | |
559 | return; | |
560 | spin_lock(&dcache_lock); | |
da3bbdd4 KM |
561 | if (count >= unused) |
562 | prune_ratio = 1; | |
563 | else | |
564 | prune_ratio = unused / count; | |
565 | spin_lock(&sb_lock); | |
dca33252 | 566 | list_for_each_entry(sb, &super_blocks, s_list) { |
551de6f3 AV |
567 | if (list_empty(&sb->s_instances)) |
568 | continue; | |
da3bbdd4 | 569 | if (sb->s_nr_dentry_unused == 0) |
1da177e4 | 570 | continue; |
da3bbdd4 KM |
571 | sb->s_count++; |
572 | /* Now, we reclaim unused dentrins with fairness. | |
573 | * We reclaim them same percentage from each superblock. | |
574 | * We calculate number of dentries to scan on this sb | |
575 | * as follows, but the implementation is arranged to avoid | |
576 | * overflows: | |
577 | * number of dentries to scan on this sb = | |
578 | * count * (number of dentries on this sb / | |
579 | * number of dentries in the machine) | |
0feae5c4 | 580 | */ |
da3bbdd4 KM |
581 | spin_unlock(&sb_lock); |
582 | if (prune_ratio != 1) | |
583 | w_count = (sb->s_nr_dentry_unused / prune_ratio) + 1; | |
584 | else | |
585 | w_count = sb->s_nr_dentry_unused; | |
586 | pruned = w_count; | |
0feae5c4 | 587 | /* |
da3bbdd4 KM |
588 | * We need to be sure this filesystem isn't being unmounted, |
589 | * otherwise we could race with generic_shutdown_super(), and | |
590 | * end up holding a reference to an inode while the filesystem | |
591 | * is unmounted. So we try to get s_umount, and make sure | |
592 | * s_root isn't NULL. | |
0feae5c4 | 593 | */ |
da3bbdd4 KM |
594 | if (down_read_trylock(&sb->s_umount)) { |
595 | if ((sb->s_root != NULL) && | |
596 | (!list_empty(&sb->s_dentry_lru))) { | |
597 | spin_unlock(&dcache_lock); | |
598 | __shrink_dcache_sb(sb, &w_count, | |
599 | DCACHE_REFERENCED); | |
600 | pruned -= w_count; | |
601 | spin_lock(&dcache_lock); | |
0feae5c4 | 602 | } |
da3bbdd4 | 603 | up_read(&sb->s_umount); |
0feae5c4 | 604 | } |
da3bbdd4 | 605 | spin_lock(&sb_lock); |
dca33252 AV |
606 | if (p) |
607 | __put_super(p); | |
da3bbdd4 | 608 | count -= pruned; |
dca33252 | 609 | p = sb; |
79893c17 AV |
610 | /* more work left to do? */ |
611 | if (count <= 0) | |
612 | break; | |
1da177e4 | 613 | } |
dca33252 AV |
614 | if (p) |
615 | __put_super(p); | |
da3bbdd4 | 616 | spin_unlock(&sb_lock); |
1da177e4 LT |
617 | spin_unlock(&dcache_lock); |
618 | } | |
619 | ||
1da177e4 LT |
620 | /** |
621 | * shrink_dcache_sb - shrink dcache for a superblock | |
622 | * @sb: superblock | |
623 | * | |
3049cfe2 CH |
624 | * Shrink the dcache for the specified super block. This is used to free |
625 | * the dcache before unmounting a file system. | |
1da177e4 | 626 | */ |
3049cfe2 | 627 | void shrink_dcache_sb(struct super_block *sb) |
1da177e4 | 628 | { |
3049cfe2 CH |
629 | LIST_HEAD(tmp); |
630 | ||
631 | spin_lock(&dcache_lock); | |
632 | while (!list_empty(&sb->s_dentry_lru)) { | |
633 | list_splice_init(&sb->s_dentry_lru, &tmp); | |
634 | shrink_dentry_list(&tmp); | |
635 | } | |
636 | spin_unlock(&dcache_lock); | |
1da177e4 | 637 | } |
ec4f8605 | 638 | EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4 | 639 | |
c636ebdb DH |
640 | /* |
641 | * destroy a single subtree of dentries for unmount | |
642 | * - see the comments on shrink_dcache_for_umount() for a description of the | |
643 | * locking | |
644 | */ | |
645 | static void shrink_dcache_for_umount_subtree(struct dentry *dentry) | |
646 | { | |
647 | struct dentry *parent; | |
f8713576 | 648 | unsigned detached = 0; |
c636ebdb DH |
649 | |
650 | BUG_ON(!IS_ROOT(dentry)); | |
651 | ||
652 | /* detach this root from the system */ | |
653 | spin_lock(&dcache_lock); | |
a4633357 | 654 | dentry_lru_del(dentry); |
c636ebdb DH |
655 | __d_drop(dentry); |
656 | spin_unlock(&dcache_lock); | |
657 | ||
658 | for (;;) { | |
659 | /* descend to the first leaf in the current subtree */ | |
660 | while (!list_empty(&dentry->d_subdirs)) { | |
661 | struct dentry *loop; | |
662 | ||
663 | /* this is a branch with children - detach all of them | |
664 | * from the system in one go */ | |
665 | spin_lock(&dcache_lock); | |
666 | list_for_each_entry(loop, &dentry->d_subdirs, | |
667 | d_u.d_child) { | |
a4633357 | 668 | dentry_lru_del(loop); |
c636ebdb DH |
669 | __d_drop(loop); |
670 | cond_resched_lock(&dcache_lock); | |
671 | } | |
672 | spin_unlock(&dcache_lock); | |
673 | ||
674 | /* move to the first child */ | |
675 | dentry = list_entry(dentry->d_subdirs.next, | |
676 | struct dentry, d_u.d_child); | |
677 | } | |
678 | ||
679 | /* consume the dentries from this leaf up through its parents | |
680 | * until we find one with children or run out altogether */ | |
681 | do { | |
682 | struct inode *inode; | |
683 | ||
684 | if (atomic_read(&dentry->d_count) != 0) { | |
685 | printk(KERN_ERR | |
686 | "BUG: Dentry %p{i=%lx,n=%s}" | |
687 | " still in use (%d)" | |
688 | " [unmount of %s %s]\n", | |
689 | dentry, | |
690 | dentry->d_inode ? | |
691 | dentry->d_inode->i_ino : 0UL, | |
692 | dentry->d_name.name, | |
693 | atomic_read(&dentry->d_count), | |
694 | dentry->d_sb->s_type->name, | |
695 | dentry->d_sb->s_id); | |
696 | BUG(); | |
697 | } | |
698 | ||
871c0067 | 699 | if (IS_ROOT(dentry)) |
c636ebdb | 700 | parent = NULL; |
871c0067 OH |
701 | else { |
702 | parent = dentry->d_parent; | |
c636ebdb | 703 | atomic_dec(&parent->d_count); |
871c0067 | 704 | } |
c636ebdb DH |
705 | |
706 | list_del(&dentry->d_u.d_child); | |
f8713576 | 707 | detached++; |
c636ebdb DH |
708 | |
709 | inode = dentry->d_inode; | |
710 | if (inode) { | |
711 | dentry->d_inode = NULL; | |
712 | list_del_init(&dentry->d_alias); | |
713 | if (dentry->d_op && dentry->d_op->d_iput) | |
714 | dentry->d_op->d_iput(dentry, inode); | |
715 | else | |
716 | iput(inode); | |
717 | } | |
718 | ||
719 | d_free(dentry); | |
720 | ||
721 | /* finished when we fall off the top of the tree, | |
722 | * otherwise we ascend to the parent and move to the | |
723 | * next sibling if there is one */ | |
724 | if (!parent) | |
312d3ca8 | 725 | return; |
c636ebdb | 726 | dentry = parent; |
c636ebdb DH |
727 | } while (list_empty(&dentry->d_subdirs)); |
728 | ||
729 | dentry = list_entry(dentry->d_subdirs.next, | |
730 | struct dentry, d_u.d_child); | |
731 | } | |
732 | } | |
733 | ||
734 | /* | |
735 | * destroy the dentries attached to a superblock on unmounting | |
736 | * - we don't need to use dentry->d_lock, and only need dcache_lock when | |
737 | * removing the dentry from the system lists and hashes because: | |
738 | * - the superblock is detached from all mountings and open files, so the | |
739 | * dentry trees will not be rearranged by the VFS | |
740 | * - s_umount is write-locked, so the memory pressure shrinker will ignore | |
741 | * any dentries belonging to this superblock that it comes across | |
742 | * - the filesystem itself is no longer permitted to rearrange the dentries | |
743 | * in this superblock | |
744 | */ | |
745 | void shrink_dcache_for_umount(struct super_block *sb) | |
746 | { | |
747 | struct dentry *dentry; | |
748 | ||
749 | if (down_read_trylock(&sb->s_umount)) | |
750 | BUG(); | |
751 | ||
752 | dentry = sb->s_root; | |
753 | sb->s_root = NULL; | |
754 | atomic_dec(&dentry->d_count); | |
755 | shrink_dcache_for_umount_subtree(dentry); | |
756 | ||
757 | while (!hlist_empty(&sb->s_anon)) { | |
758 | dentry = hlist_entry(sb->s_anon.first, struct dentry, d_hash); | |
759 | shrink_dcache_for_umount_subtree(dentry); | |
760 | } | |
761 | } | |
762 | ||
1da177e4 LT |
763 | /* |
764 | * Search for at least 1 mount point in the dentry's subdirs. | |
765 | * We descend to the next level whenever the d_subdirs | |
766 | * list is non-empty and continue searching. | |
767 | */ | |
768 | ||
769 | /** | |
770 | * have_submounts - check for mounts over a dentry | |
771 | * @parent: dentry to check. | |
772 | * | |
773 | * Return true if the parent or its subdirectories contain | |
774 | * a mount point | |
775 | */ | |
776 | ||
777 | int have_submounts(struct dentry *parent) | |
778 | { | |
779 | struct dentry *this_parent = parent; | |
780 | struct list_head *next; | |
781 | ||
782 | spin_lock(&dcache_lock); | |
783 | if (d_mountpoint(parent)) | |
784 | goto positive; | |
785 | repeat: | |
786 | next = this_parent->d_subdirs.next; | |
787 | resume: | |
788 | while (next != &this_parent->d_subdirs) { | |
789 | struct list_head *tmp = next; | |
5160ee6f | 790 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
791 | next = tmp->next; |
792 | /* Have we found a mount point ? */ | |
793 | if (d_mountpoint(dentry)) | |
794 | goto positive; | |
795 | if (!list_empty(&dentry->d_subdirs)) { | |
796 | this_parent = dentry; | |
797 | goto repeat; | |
798 | } | |
799 | } | |
800 | /* | |
801 | * All done at this level ... ascend and resume the search. | |
802 | */ | |
803 | if (this_parent != parent) { | |
5160ee6f | 804 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
805 | this_parent = this_parent->d_parent; |
806 | goto resume; | |
807 | } | |
808 | spin_unlock(&dcache_lock); | |
809 | return 0; /* No mount points found in tree */ | |
810 | positive: | |
811 | spin_unlock(&dcache_lock); | |
812 | return 1; | |
813 | } | |
ec4f8605 | 814 | EXPORT_SYMBOL(have_submounts); |
1da177e4 LT |
815 | |
816 | /* | |
817 | * Search the dentry child list for the specified parent, | |
818 | * and move any unused dentries to the end of the unused | |
819 | * list for prune_dcache(). We descend to the next level | |
820 | * whenever the d_subdirs list is non-empty and continue | |
821 | * searching. | |
822 | * | |
823 | * It returns zero iff there are no unused children, | |
824 | * otherwise it returns the number of children moved to | |
825 | * the end of the unused list. This may not be the total | |
826 | * number of unused children, because select_parent can | |
827 | * drop the lock and return early due to latency | |
828 | * constraints. | |
829 | */ | |
830 | static int select_parent(struct dentry * parent) | |
831 | { | |
832 | struct dentry *this_parent = parent; | |
833 | struct list_head *next; | |
834 | int found = 0; | |
835 | ||
836 | spin_lock(&dcache_lock); | |
837 | repeat: | |
838 | next = this_parent->d_subdirs.next; | |
839 | resume: | |
840 | while (next != &this_parent->d_subdirs) { | |
841 | struct list_head *tmp = next; | |
5160ee6f | 842 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
843 | next = tmp->next; |
844 | ||
1da177e4 LT |
845 | /* |
846 | * move only zero ref count dentries to the end | |
847 | * of the unused list for prune_dcache | |
848 | */ | |
849 | if (!atomic_read(&dentry->d_count)) { | |
a4633357 | 850 | dentry_lru_move_tail(dentry); |
1da177e4 | 851 | found++; |
a4633357 CH |
852 | } else { |
853 | dentry_lru_del(dentry); | |
1da177e4 LT |
854 | } |
855 | ||
856 | /* | |
857 | * We can return to the caller if we have found some (this | |
858 | * ensures forward progress). We'll be coming back to find | |
859 | * the rest. | |
860 | */ | |
861 | if (found && need_resched()) | |
862 | goto out; | |
863 | ||
864 | /* | |
865 | * Descend a level if the d_subdirs list is non-empty. | |
866 | */ | |
867 | if (!list_empty(&dentry->d_subdirs)) { | |
868 | this_parent = dentry; | |
1da177e4 LT |
869 | goto repeat; |
870 | } | |
871 | } | |
872 | /* | |
873 | * All done at this level ... ascend and resume the search. | |
874 | */ | |
875 | if (this_parent != parent) { | |
5160ee6f | 876 | next = this_parent->d_u.d_child.next; |
1da177e4 | 877 | this_parent = this_parent->d_parent; |
1da177e4 LT |
878 | goto resume; |
879 | } | |
880 | out: | |
881 | spin_unlock(&dcache_lock); | |
882 | return found; | |
883 | } | |
884 | ||
885 | /** | |
886 | * shrink_dcache_parent - prune dcache | |
887 | * @parent: parent of entries to prune | |
888 | * | |
889 | * Prune the dcache to remove unused children of the parent dentry. | |
890 | */ | |
891 | ||
892 | void shrink_dcache_parent(struct dentry * parent) | |
893 | { | |
da3bbdd4 | 894 | struct super_block *sb = parent->d_sb; |
1da177e4 LT |
895 | int found; |
896 | ||
897 | while ((found = select_parent(parent)) != 0) | |
da3bbdd4 | 898 | __shrink_dcache_sb(sb, &found, 0); |
1da177e4 | 899 | } |
ec4f8605 | 900 | EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4 | 901 | |
1da177e4 LT |
902 | /* |
903 | * Scan `nr' dentries and return the number which remain. | |
904 | * | |
905 | * We need to avoid reentering the filesystem if the caller is performing a | |
906 | * GFP_NOFS allocation attempt. One example deadlock is: | |
907 | * | |
908 | * ext2_new_block->getblk->GFP->shrink_dcache_memory->prune_dcache-> | |
909 | * prune_one_dentry->dput->dentry_iput->iput->inode->i_sb->s_op->put_inode-> | |
910 | * ext2_discard_prealloc->ext2_free_blocks->lock_super->DEADLOCK. | |
911 | * | |
912 | * In this case we return -1 to tell the caller that we baled. | |
913 | */ | |
7f8275d0 | 914 | static int shrink_dcache_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask) |
1da177e4 LT |
915 | { |
916 | if (nr) { | |
917 | if (!(gfp_mask & __GFP_FS)) | |
918 | return -1; | |
da3bbdd4 | 919 | prune_dcache(nr); |
1da177e4 | 920 | } |
312d3ca8 | 921 | |
86c8749e | 922 | return (dentry_stat.nr_unused / 100) * sysctl_vfs_cache_pressure; |
1da177e4 LT |
923 | } |
924 | ||
8e1f936b RR |
925 | static struct shrinker dcache_shrinker = { |
926 | .shrink = shrink_dcache_memory, | |
927 | .seeks = DEFAULT_SEEKS, | |
928 | }; | |
929 | ||
1da177e4 LT |
930 | /** |
931 | * d_alloc - allocate a dcache entry | |
932 | * @parent: parent of entry to allocate | |
933 | * @name: qstr of the name | |
934 | * | |
935 | * Allocates a dentry. It returns %NULL if there is insufficient memory | |
936 | * available. On a success the dentry is returned. The name passed in is | |
937 | * copied and the copy passed in may be reused after this call. | |
938 | */ | |
939 | ||
940 | struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) | |
941 | { | |
942 | struct dentry *dentry; | |
943 | char *dname; | |
944 | ||
e12ba74d | 945 | dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4 LT |
946 | if (!dentry) |
947 | return NULL; | |
948 | ||
949 | if (name->len > DNAME_INLINE_LEN-1) { | |
950 | dname = kmalloc(name->len + 1, GFP_KERNEL); | |
951 | if (!dname) { | |
952 | kmem_cache_free(dentry_cache, dentry); | |
953 | return NULL; | |
954 | } | |
955 | } else { | |
956 | dname = dentry->d_iname; | |
957 | } | |
958 | dentry->d_name.name = dname; | |
959 | ||
960 | dentry->d_name.len = name->len; | |
961 | dentry->d_name.hash = name->hash; | |
962 | memcpy(dname, name->name, name->len); | |
963 | dname[name->len] = 0; | |
964 | ||
965 | atomic_set(&dentry->d_count, 1); | |
966 | dentry->d_flags = DCACHE_UNHASHED; | |
967 | spin_lock_init(&dentry->d_lock); | |
968 | dentry->d_inode = NULL; | |
969 | dentry->d_parent = NULL; | |
970 | dentry->d_sb = NULL; | |
971 | dentry->d_op = NULL; | |
972 | dentry->d_fsdata = NULL; | |
973 | dentry->d_mounted = 0; | |
1da177e4 LT |
974 | INIT_HLIST_NODE(&dentry->d_hash); |
975 | INIT_LIST_HEAD(&dentry->d_lru); | |
976 | INIT_LIST_HEAD(&dentry->d_subdirs); | |
977 | INIT_LIST_HEAD(&dentry->d_alias); | |
978 | ||
979 | if (parent) { | |
980 | dentry->d_parent = dget(parent); | |
981 | dentry->d_sb = parent->d_sb; | |
982 | } else { | |
5160ee6f | 983 | INIT_LIST_HEAD(&dentry->d_u.d_child); |
1da177e4 LT |
984 | } |
985 | ||
986 | spin_lock(&dcache_lock); | |
987 | if (parent) | |
5160ee6f | 988 | list_add(&dentry->d_u.d_child, &parent->d_subdirs); |
1da177e4 LT |
989 | spin_unlock(&dcache_lock); |
990 | ||
3e880fb5 | 991 | this_cpu_inc(nr_dentry); |
312d3ca8 | 992 | |
1da177e4 LT |
993 | return dentry; |
994 | } | |
ec4f8605 | 995 | EXPORT_SYMBOL(d_alloc); |
1da177e4 LT |
996 | |
997 | struct dentry *d_alloc_name(struct dentry *parent, const char *name) | |
998 | { | |
999 | struct qstr q; | |
1000 | ||
1001 | q.name = name; | |
1002 | q.len = strlen(name); | |
1003 | q.hash = full_name_hash(q.name, q.len); | |
1004 | return d_alloc(parent, &q); | |
1005 | } | |
ef26ca97 | 1006 | EXPORT_SYMBOL(d_alloc_name); |
1da177e4 | 1007 | |
360da900 OH |
1008 | /* the caller must hold dcache_lock */ |
1009 | static void __d_instantiate(struct dentry *dentry, struct inode *inode) | |
1010 | { | |
1011 | if (inode) | |
1012 | list_add(&dentry->d_alias, &inode->i_dentry); | |
1013 | dentry->d_inode = inode; | |
1014 | fsnotify_d_instantiate(dentry, inode); | |
1015 | } | |
1016 | ||
1da177e4 LT |
1017 | /** |
1018 | * d_instantiate - fill in inode information for a dentry | |
1019 | * @entry: dentry to complete | |
1020 | * @inode: inode to attach to this dentry | |
1021 | * | |
1022 | * Fill in inode information in the entry. | |
1023 | * | |
1024 | * This turns negative dentries into productive full members | |
1025 | * of society. | |
1026 | * | |
1027 | * NOTE! This assumes that the inode count has been incremented | |
1028 | * (or otherwise set) by the caller to indicate that it is now | |
1029 | * in use by the dcache. | |
1030 | */ | |
1031 | ||
1032 | void d_instantiate(struct dentry *entry, struct inode * inode) | |
1033 | { | |
28133c7b | 1034 | BUG_ON(!list_empty(&entry->d_alias)); |
1da177e4 | 1035 | spin_lock(&dcache_lock); |
360da900 | 1036 | __d_instantiate(entry, inode); |
1da177e4 LT |
1037 | spin_unlock(&dcache_lock); |
1038 | security_d_instantiate(entry, inode); | |
1039 | } | |
ec4f8605 | 1040 | EXPORT_SYMBOL(d_instantiate); |
1da177e4 LT |
1041 | |
1042 | /** | |
1043 | * d_instantiate_unique - instantiate a non-aliased dentry | |
1044 | * @entry: dentry to instantiate | |
1045 | * @inode: inode to attach to this dentry | |
1046 | * | |
1047 | * Fill in inode information in the entry. On success, it returns NULL. | |
1048 | * If an unhashed alias of "entry" already exists, then we return the | |
e866cfa9 | 1049 | * aliased dentry instead and drop one reference to inode. |
1da177e4 LT |
1050 | * |
1051 | * Note that in order to avoid conflicts with rename() etc, the caller | |
1052 | * had better be holding the parent directory semaphore. | |
e866cfa9 OD |
1053 | * |
1054 | * This also assumes that the inode count has been incremented | |
1055 | * (or otherwise set) by the caller to indicate that it is now | |
1056 | * in use by the dcache. | |
1da177e4 | 1057 | */ |
770bfad8 DH |
1058 | static struct dentry *__d_instantiate_unique(struct dentry *entry, |
1059 | struct inode *inode) | |
1da177e4 LT |
1060 | { |
1061 | struct dentry *alias; | |
1062 | int len = entry->d_name.len; | |
1063 | const char *name = entry->d_name.name; | |
1064 | unsigned int hash = entry->d_name.hash; | |
1065 | ||
770bfad8 | 1066 | if (!inode) { |
360da900 | 1067 | __d_instantiate(entry, NULL); |
770bfad8 DH |
1068 | return NULL; |
1069 | } | |
1070 | ||
1da177e4 LT |
1071 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
1072 | struct qstr *qstr = &alias->d_name; | |
1073 | ||
1074 | if (qstr->hash != hash) | |
1075 | continue; | |
1076 | if (alias->d_parent != entry->d_parent) | |
1077 | continue; | |
1078 | if (qstr->len != len) | |
1079 | continue; | |
1080 | if (memcmp(qstr->name, name, len)) | |
1081 | continue; | |
1082 | dget_locked(alias); | |
1da177e4 LT |
1083 | return alias; |
1084 | } | |
770bfad8 | 1085 | |
360da900 | 1086 | __d_instantiate(entry, inode); |
1da177e4 LT |
1087 | return NULL; |
1088 | } | |
770bfad8 DH |
1089 | |
1090 | struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode) | |
1091 | { | |
1092 | struct dentry *result; | |
1093 | ||
1094 | BUG_ON(!list_empty(&entry->d_alias)); | |
1095 | ||
1096 | spin_lock(&dcache_lock); | |
1097 | result = __d_instantiate_unique(entry, inode); | |
1098 | spin_unlock(&dcache_lock); | |
1099 | ||
1100 | if (!result) { | |
1101 | security_d_instantiate(entry, inode); | |
1102 | return NULL; | |
1103 | } | |
1104 | ||
1105 | BUG_ON(!d_unhashed(result)); | |
1106 | iput(inode); | |
1107 | return result; | |
1108 | } | |
1109 | ||
1da177e4 LT |
1110 | EXPORT_SYMBOL(d_instantiate_unique); |
1111 | ||
1112 | /** | |
1113 | * d_alloc_root - allocate root dentry | |
1114 | * @root_inode: inode to allocate the root for | |
1115 | * | |
1116 | * Allocate a root ("/") dentry for the inode given. The inode is | |
1117 | * instantiated and returned. %NULL is returned if there is insufficient | |
1118 | * memory or the inode passed is %NULL. | |
1119 | */ | |
1120 | ||
1121 | struct dentry * d_alloc_root(struct inode * root_inode) | |
1122 | { | |
1123 | struct dentry *res = NULL; | |
1124 | ||
1125 | if (root_inode) { | |
1126 | static const struct qstr name = { .name = "/", .len = 1 }; | |
1127 | ||
1128 | res = d_alloc(NULL, &name); | |
1129 | if (res) { | |
1130 | res->d_sb = root_inode->i_sb; | |
1131 | res->d_parent = res; | |
1132 | d_instantiate(res, root_inode); | |
1133 | } | |
1134 | } | |
1135 | return res; | |
1136 | } | |
ec4f8605 | 1137 | EXPORT_SYMBOL(d_alloc_root); |
1da177e4 LT |
1138 | |
1139 | static inline struct hlist_head *d_hash(struct dentry *parent, | |
1140 | unsigned long hash) | |
1141 | { | |
1142 | hash += ((unsigned long) parent ^ GOLDEN_RATIO_PRIME) / L1_CACHE_BYTES; | |
1143 | hash = hash ^ ((hash ^ GOLDEN_RATIO_PRIME) >> D_HASHBITS); | |
1144 | return dentry_hashtable + (hash & D_HASHMASK); | |
1145 | } | |
1146 | ||
4ea3ada2 CH |
1147 | /** |
1148 | * d_obtain_alias - find or allocate a dentry for a given inode | |
1149 | * @inode: inode to allocate the dentry for | |
1150 | * | |
1151 | * Obtain a dentry for an inode resulting from NFS filehandle conversion or | |
1152 | * similar open by handle operations. The returned dentry may be anonymous, | |
1153 | * or may have a full name (if the inode was already in the cache). | |
1154 | * | |
1155 | * When called on a directory inode, we must ensure that the inode only ever | |
1156 | * has one dentry. If a dentry is found, that is returned instead of | |
1157 | * allocating a new one. | |
1158 | * | |
1159 | * On successful return, the reference to the inode has been transferred | |
44003728 CH |
1160 | * to the dentry. In case of an error the reference on the inode is released. |
1161 | * To make it easier to use in export operations a %NULL or IS_ERR inode may | |
1162 | * be passed in and will be the error will be propagate to the return value, | |
1163 | * with a %NULL @inode replaced by ERR_PTR(-ESTALE). | |
4ea3ada2 CH |
1164 | */ |
1165 | struct dentry *d_obtain_alias(struct inode *inode) | |
1166 | { | |
9308a612 CH |
1167 | static const struct qstr anonstring = { .name = "" }; |
1168 | struct dentry *tmp; | |
1169 | struct dentry *res; | |
4ea3ada2 CH |
1170 | |
1171 | if (!inode) | |
44003728 | 1172 | return ERR_PTR(-ESTALE); |
4ea3ada2 CH |
1173 | if (IS_ERR(inode)) |
1174 | return ERR_CAST(inode); | |
1175 | ||
9308a612 CH |
1176 | res = d_find_alias(inode); |
1177 | if (res) | |
1178 | goto out_iput; | |
1179 | ||
1180 | tmp = d_alloc(NULL, &anonstring); | |
1181 | if (!tmp) { | |
1182 | res = ERR_PTR(-ENOMEM); | |
1183 | goto out_iput; | |
4ea3ada2 | 1184 | } |
9308a612 CH |
1185 | tmp->d_parent = tmp; /* make sure dput doesn't croak */ |
1186 | ||
1187 | spin_lock(&dcache_lock); | |
1188 | res = __d_find_alias(inode, 0); | |
1189 | if (res) { | |
1190 | spin_unlock(&dcache_lock); | |
1191 | dput(tmp); | |
1192 | goto out_iput; | |
1193 | } | |
1194 | ||
1195 | /* attach a disconnected dentry */ | |
1196 | spin_lock(&tmp->d_lock); | |
1197 | tmp->d_sb = inode->i_sb; | |
1198 | tmp->d_inode = inode; | |
1199 | tmp->d_flags |= DCACHE_DISCONNECTED; | |
1200 | tmp->d_flags &= ~DCACHE_UNHASHED; | |
1201 | list_add(&tmp->d_alias, &inode->i_dentry); | |
1202 | hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon); | |
1203 | spin_unlock(&tmp->d_lock); | |
1204 | ||
1205 | spin_unlock(&dcache_lock); | |
1206 | return tmp; | |
1207 | ||
1208 | out_iput: | |
1209 | iput(inode); | |
1210 | return res; | |
4ea3ada2 | 1211 | } |
adc48720 | 1212 | EXPORT_SYMBOL(d_obtain_alias); |
1da177e4 LT |
1213 | |
1214 | /** | |
1215 | * d_splice_alias - splice a disconnected dentry into the tree if one exists | |
1216 | * @inode: the inode which may have a disconnected dentry | |
1217 | * @dentry: a negative dentry which we want to point to the inode. | |
1218 | * | |
1219 | * If inode is a directory and has a 'disconnected' dentry (i.e. IS_ROOT and | |
1220 | * DCACHE_DISCONNECTED), then d_move that in place of the given dentry | |
1221 | * and return it, else simply d_add the inode to the dentry and return NULL. | |
1222 | * | |
1223 | * This is needed in the lookup routine of any filesystem that is exportable | |
1224 | * (via knfsd) so that we can build dcache paths to directories effectively. | |
1225 | * | |
1226 | * If a dentry was found and moved, then it is returned. Otherwise NULL | |
1227 | * is returned. This matches the expected return value of ->lookup. | |
1228 | * | |
1229 | */ | |
1230 | struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) | |
1231 | { | |
1232 | struct dentry *new = NULL; | |
1233 | ||
21c0d8fd | 1234 | if (inode && S_ISDIR(inode->i_mode)) { |
1da177e4 LT |
1235 | spin_lock(&dcache_lock); |
1236 | new = __d_find_alias(inode, 1); | |
1237 | if (new) { | |
1238 | BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED)); | |
1239 | spin_unlock(&dcache_lock); | |
1240 | security_d_instantiate(new, inode); | |
1da177e4 LT |
1241 | d_move(new, dentry); |
1242 | iput(inode); | |
1243 | } else { | |
360da900 OH |
1244 | /* already taking dcache_lock, so d_add() by hand */ |
1245 | __d_instantiate(dentry, inode); | |
1da177e4 LT |
1246 | spin_unlock(&dcache_lock); |
1247 | security_d_instantiate(dentry, inode); | |
1248 | d_rehash(dentry); | |
1249 | } | |
1250 | } else | |
1251 | d_add(dentry, inode); | |
1252 | return new; | |
1253 | } | |
ec4f8605 | 1254 | EXPORT_SYMBOL(d_splice_alias); |
1da177e4 | 1255 | |
9403540c BN |
1256 | /** |
1257 | * d_add_ci - lookup or allocate new dentry with case-exact name | |
1258 | * @inode: the inode case-insensitive lookup has found | |
1259 | * @dentry: the negative dentry that was passed to the parent's lookup func | |
1260 | * @name: the case-exact name to be associated with the returned dentry | |
1261 | * | |
1262 | * This is to avoid filling the dcache with case-insensitive names to the | |
1263 | * same inode, only the actual correct case is stored in the dcache for | |
1264 | * case-insensitive filesystems. | |
1265 | * | |
1266 | * For a case-insensitive lookup match and if the the case-exact dentry | |
1267 | * already exists in in the dcache, use it and return it. | |
1268 | * | |
1269 | * If no entry exists with the exact case name, allocate new dentry with | |
1270 | * the exact case, and return the spliced entry. | |
1271 | */ | |
e45b590b | 1272 | struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c BN |
1273 | struct qstr *name) |
1274 | { | |
1275 | int error; | |
1276 | struct dentry *found; | |
1277 | struct dentry *new; | |
1278 | ||
b6520c81 CH |
1279 | /* |
1280 | * First check if a dentry matching the name already exists, | |
1281 | * if not go ahead and create it now. | |
1282 | */ | |
9403540c | 1283 | found = d_hash_and_lookup(dentry->d_parent, name); |
9403540c BN |
1284 | if (!found) { |
1285 | new = d_alloc(dentry->d_parent, name); | |
1286 | if (!new) { | |
1287 | error = -ENOMEM; | |
1288 | goto err_out; | |
1289 | } | |
b6520c81 | 1290 | |
9403540c BN |
1291 | found = d_splice_alias(inode, new); |
1292 | if (found) { | |
1293 | dput(new); | |
1294 | return found; | |
1295 | } | |
1296 | return new; | |
1297 | } | |
b6520c81 CH |
1298 | |
1299 | /* | |
1300 | * If a matching dentry exists, and it's not negative use it. | |
1301 | * | |
1302 | * Decrement the reference count to balance the iget() done | |
1303 | * earlier on. | |
1304 | */ | |
9403540c BN |
1305 | if (found->d_inode) { |
1306 | if (unlikely(found->d_inode != inode)) { | |
1307 | /* This can't happen because bad inodes are unhashed. */ | |
1308 | BUG_ON(!is_bad_inode(inode)); | |
1309 | BUG_ON(!is_bad_inode(found->d_inode)); | |
1310 | } | |
9403540c BN |
1311 | iput(inode); |
1312 | return found; | |
1313 | } | |
b6520c81 | 1314 | |
9403540c BN |
1315 | /* |
1316 | * Negative dentry: instantiate it unless the inode is a directory and | |
b6520c81 | 1317 | * already has a dentry. |
9403540c | 1318 | */ |
9403540c | 1319 | spin_lock(&dcache_lock); |
b6520c81 | 1320 | if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) { |
360da900 | 1321 | __d_instantiate(found, inode); |
9403540c BN |
1322 | spin_unlock(&dcache_lock); |
1323 | security_d_instantiate(found, inode); | |
1324 | return found; | |
1325 | } | |
b6520c81 | 1326 | |
9403540c | 1327 | /* |
b6520c81 CH |
1328 | * In case a directory already has a (disconnected) entry grab a |
1329 | * reference to it, move it in place and use it. | |
9403540c BN |
1330 | */ |
1331 | new = list_entry(inode->i_dentry.next, struct dentry, d_alias); | |
1332 | dget_locked(new); | |
1333 | spin_unlock(&dcache_lock); | |
9403540c | 1334 | security_d_instantiate(found, inode); |
9403540c | 1335 | d_move(new, found); |
9403540c | 1336 | iput(inode); |
9403540c | 1337 | dput(found); |
9403540c BN |
1338 | return new; |
1339 | ||
1340 | err_out: | |
1341 | iput(inode); | |
1342 | return ERR_PTR(error); | |
1343 | } | |
ec4f8605 | 1344 | EXPORT_SYMBOL(d_add_ci); |
1da177e4 LT |
1345 | |
1346 | /** | |
1347 | * d_lookup - search for a dentry | |
1348 | * @parent: parent dentry | |
1349 | * @name: qstr of name we wish to find | |
b04f784e | 1350 | * Returns: dentry, or NULL |
1da177e4 | 1351 | * |
b04f784e NP |
1352 | * d_lookup searches the children of the parent dentry for the name in |
1353 | * question. If the dentry is found its reference count is incremented and the | |
1354 | * dentry is returned. The caller must use dput to free the entry when it has | |
1355 | * finished using it. %NULL is returned if the dentry does not exist. | |
1da177e4 | 1356 | */ |
1da177e4 LT |
1357 | struct dentry * d_lookup(struct dentry * parent, struct qstr * name) |
1358 | { | |
1359 | struct dentry * dentry = NULL; | |
1360 | unsigned long seq; | |
1361 | ||
1362 | do { | |
1363 | seq = read_seqbegin(&rename_lock); | |
1364 | dentry = __d_lookup(parent, name); | |
1365 | if (dentry) | |
1366 | break; | |
1367 | } while (read_seqretry(&rename_lock, seq)); | |
1368 | return dentry; | |
1369 | } | |
ec4f8605 | 1370 | EXPORT_SYMBOL(d_lookup); |
1da177e4 | 1371 | |
b04f784e NP |
1372 | /* |
1373 | * __d_lookup - search for a dentry (racy) | |
1374 | * @parent: parent dentry | |
1375 | * @name: qstr of name we wish to find | |
1376 | * Returns: dentry, or NULL | |
1377 | * | |
1378 | * __d_lookup is like d_lookup, however it may (rarely) return a | |
1379 | * false-negative result due to unrelated rename activity. | |
1380 | * | |
1381 | * __d_lookup is slightly faster by avoiding rename_lock read seqlock, | |
1382 | * however it must be used carefully, eg. with a following d_lookup in | |
1383 | * the case of failure. | |
1384 | * | |
1385 | * __d_lookup callers must be commented. | |
1386 | */ | |
1da177e4 LT |
1387 | struct dentry * __d_lookup(struct dentry * parent, struct qstr * name) |
1388 | { | |
1389 | unsigned int len = name->len; | |
1390 | unsigned int hash = name->hash; | |
1391 | const unsigned char *str = name->name; | |
1392 | struct hlist_head *head = d_hash(parent,hash); | |
1393 | struct dentry *found = NULL; | |
1394 | struct hlist_node *node; | |
665a7583 | 1395 | struct dentry *dentry; |
1da177e4 | 1396 | |
b04f784e NP |
1397 | /* |
1398 | * The hash list is protected using RCU. | |
1399 | * | |
1400 | * Take d_lock when comparing a candidate dentry, to avoid races | |
1401 | * with d_move(). | |
1402 | * | |
1403 | * It is possible that concurrent renames can mess up our list | |
1404 | * walk here and result in missing our dentry, resulting in the | |
1405 | * false-negative result. d_lookup() protects against concurrent | |
1406 | * renames using rename_lock seqlock. | |
1407 | * | |
1408 | * See Documentation/vfs/dcache-locking.txt for more details. | |
1409 | */ | |
1da177e4 LT |
1410 | rcu_read_lock(); |
1411 | ||
665a7583 | 1412 | hlist_for_each_entry_rcu(dentry, node, head, d_hash) { |
1da177e4 LT |
1413 | struct qstr *qstr; |
1414 | ||
1da177e4 LT |
1415 | if (dentry->d_name.hash != hash) |
1416 | continue; | |
1417 | if (dentry->d_parent != parent) | |
1418 | continue; | |
1419 | ||
1420 | spin_lock(&dentry->d_lock); | |
1421 | ||
1422 | /* | |
1423 | * Recheck the dentry after taking the lock - d_move may have | |
b04f784e NP |
1424 | * changed things. Don't bother checking the hash because |
1425 | * we're about to compare the whole name anyway. | |
1da177e4 LT |
1426 | */ |
1427 | if (dentry->d_parent != parent) | |
1428 | goto next; | |
1429 | ||
d0185c08 LT |
1430 | /* non-existing due to RCU? */ |
1431 | if (d_unhashed(dentry)) | |
1432 | goto next; | |
1433 | ||
1da177e4 LT |
1434 | /* |
1435 | * It is safe to compare names since d_move() cannot | |
1436 | * change the qstr (protected by d_lock). | |
1437 | */ | |
1438 | qstr = &dentry->d_name; | |
1439 | if (parent->d_op && parent->d_op->d_compare) { | |
621e155a NP |
1440 | if (parent->d_op->d_compare(parent, parent->d_inode, |
1441 | dentry, dentry->d_inode, | |
1442 | qstr->len, qstr->name, name)) | |
1da177e4 LT |
1443 | goto next; |
1444 | } else { | |
1445 | if (qstr->len != len) | |
1446 | goto next; | |
1447 | if (memcmp(qstr->name, str, len)) | |
1448 | goto next; | |
1449 | } | |
1450 | ||
d0185c08 LT |
1451 | atomic_inc(&dentry->d_count); |
1452 | found = dentry; | |
1da177e4 LT |
1453 | spin_unlock(&dentry->d_lock); |
1454 | break; | |
1455 | next: | |
1456 | spin_unlock(&dentry->d_lock); | |
1457 | } | |
1458 | rcu_read_unlock(); | |
1459 | ||
1460 | return found; | |
1461 | } | |
1462 | ||
3e7e241f EB |
1463 | /** |
1464 | * d_hash_and_lookup - hash the qstr then search for a dentry | |
1465 | * @dir: Directory to search in | |
1466 | * @name: qstr of name we wish to find | |
1467 | * | |
1468 | * On hash failure or on lookup failure NULL is returned. | |
1469 | */ | |
1470 | struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) | |
1471 | { | |
1472 | struct dentry *dentry = NULL; | |
1473 | ||
1474 | /* | |
1475 | * Check for a fs-specific hash function. Note that we must | |
1476 | * calculate the standard hash first, as the d_op->d_hash() | |
1477 | * routine may choose to leave the hash value unchanged. | |
1478 | */ | |
1479 | name->hash = full_name_hash(name->name, name->len); | |
1480 | if (dir->d_op && dir->d_op->d_hash) { | |
b1e6a015 | 1481 | if (dir->d_op->d_hash(dir, dir->d_inode, name) < 0) |
3e7e241f EB |
1482 | goto out; |
1483 | } | |
1484 | dentry = d_lookup(dir, name); | |
1485 | out: | |
1486 | return dentry; | |
1487 | } | |
1488 | ||
1da177e4 | 1489 | /** |
786a5e15 | 1490 | * d_validate - verify dentry provided from insecure source (deprecated) |
1da177e4 LT |
1491 | * @dentry: The dentry alleged to be valid child of @dparent |
1492 | * @dparent: The parent dentry (known to be valid) | |
1da177e4 LT |
1493 | * |
1494 | * An insecure source has sent us a dentry, here we verify it and dget() it. | |
1495 | * This is used by ncpfs in its readdir implementation. | |
1496 | * Zero is returned in the dentry is invalid. | |
786a5e15 NP |
1497 | * |
1498 | * This function is slow for big directories, and deprecated, do not use it. | |
1da177e4 | 1499 | */ |
d3a23e16 | 1500 | int d_validate(struct dentry *dentry, struct dentry *dparent) |
1da177e4 | 1501 | { |
786a5e15 | 1502 | struct dentry *child; |
d3a23e16 NP |
1503 | |
1504 | spin_lock(&dcache_lock); | |
786a5e15 NP |
1505 | list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) { |
1506 | if (dentry == child) { | |
d3a23e16 NP |
1507 | __dget_locked(dentry); |
1508 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
1509 | return 1; |
1510 | } | |
1511 | } | |
d3a23e16 | 1512 | spin_unlock(&dcache_lock); |
786a5e15 | 1513 | |
1da177e4 LT |
1514 | return 0; |
1515 | } | |
ec4f8605 | 1516 | EXPORT_SYMBOL(d_validate); |
1da177e4 LT |
1517 | |
1518 | /* | |
1519 | * When a file is deleted, we have two options: | |
1520 | * - turn this dentry into a negative dentry | |
1521 | * - unhash this dentry and free it. | |
1522 | * | |
1523 | * Usually, we want to just turn this into | |
1524 | * a negative dentry, but if anybody else is | |
1525 | * currently using the dentry or the inode | |
1526 | * we can't do that and we fall back on removing | |
1527 | * it from the hash queues and waiting for | |
1528 | * it to be deleted later when it has no users | |
1529 | */ | |
1530 | ||
1531 | /** | |
1532 | * d_delete - delete a dentry | |
1533 | * @dentry: The dentry to delete | |
1534 | * | |
1535 | * Turn the dentry into a negative dentry if possible, otherwise | |
1536 | * remove it from the hash queues so it can be deleted later | |
1537 | */ | |
1538 | ||
1539 | void d_delete(struct dentry * dentry) | |
1540 | { | |
7a91bf7f | 1541 | int isdir = 0; |
1da177e4 LT |
1542 | /* |
1543 | * Are we the only user? | |
1544 | */ | |
1545 | spin_lock(&dcache_lock); | |
1546 | spin_lock(&dentry->d_lock); | |
7a91bf7f | 1547 | isdir = S_ISDIR(dentry->d_inode->i_mode); |
1da177e4 | 1548 | if (atomic_read(&dentry->d_count) == 1) { |
13e3c5e5 | 1549 | dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
1da177e4 | 1550 | dentry_iput(dentry); |
7a91bf7f | 1551 | fsnotify_nameremove(dentry, isdir); |
1da177e4 LT |
1552 | return; |
1553 | } | |
1554 | ||
1555 | if (!d_unhashed(dentry)) | |
1556 | __d_drop(dentry); | |
1557 | ||
1558 | spin_unlock(&dentry->d_lock); | |
1559 | spin_unlock(&dcache_lock); | |
7a91bf7f JM |
1560 | |
1561 | fsnotify_nameremove(dentry, isdir); | |
1da177e4 | 1562 | } |
ec4f8605 | 1563 | EXPORT_SYMBOL(d_delete); |
1da177e4 LT |
1564 | |
1565 | static void __d_rehash(struct dentry * entry, struct hlist_head *list) | |
1566 | { | |
1567 | ||
1568 | entry->d_flags &= ~DCACHE_UNHASHED; | |
1569 | hlist_add_head_rcu(&entry->d_hash, list); | |
1570 | } | |
1571 | ||
770bfad8 DH |
1572 | static void _d_rehash(struct dentry * entry) |
1573 | { | |
1574 | __d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash)); | |
1575 | } | |
1576 | ||
1da177e4 LT |
1577 | /** |
1578 | * d_rehash - add an entry back to the hash | |
1579 | * @entry: dentry to add to the hash | |
1580 | * | |
1581 | * Adds a dentry to the hash according to its name. | |
1582 | */ | |
1583 | ||
1584 | void d_rehash(struct dentry * entry) | |
1585 | { | |
1da177e4 LT |
1586 | spin_lock(&dcache_lock); |
1587 | spin_lock(&entry->d_lock); | |
770bfad8 | 1588 | _d_rehash(entry); |
1da177e4 LT |
1589 | spin_unlock(&entry->d_lock); |
1590 | spin_unlock(&dcache_lock); | |
1591 | } | |
ec4f8605 | 1592 | EXPORT_SYMBOL(d_rehash); |
1da177e4 | 1593 | |
fb2d5b86 NP |
1594 | /** |
1595 | * dentry_update_name_case - update case insensitive dentry with a new name | |
1596 | * @dentry: dentry to be updated | |
1597 | * @name: new name | |
1598 | * | |
1599 | * Update a case insensitive dentry with new case of name. | |
1600 | * | |
1601 | * dentry must have been returned by d_lookup with name @name. Old and new | |
1602 | * name lengths must match (ie. no d_compare which allows mismatched name | |
1603 | * lengths). | |
1604 | * | |
1605 | * Parent inode i_mutex must be held over d_lookup and into this call (to | |
1606 | * keep renames and concurrent inserts, and readdir(2) away). | |
1607 | */ | |
1608 | void dentry_update_name_case(struct dentry *dentry, struct qstr *name) | |
1609 | { | |
1610 | BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex)); | |
1611 | BUG_ON(dentry->d_name.len != name->len); /* d_lookup gives this */ | |
1612 | ||
1613 | spin_lock(&dcache_lock); | |
1614 | spin_lock(&dentry->d_lock); | |
1615 | memcpy((unsigned char *)dentry->d_name.name, name->name, name->len); | |
1616 | spin_unlock(&dentry->d_lock); | |
1617 | spin_unlock(&dcache_lock); | |
1618 | } | |
1619 | EXPORT_SYMBOL(dentry_update_name_case); | |
1620 | ||
1da177e4 LT |
1621 | /* |
1622 | * When switching names, the actual string doesn't strictly have to | |
1623 | * be preserved in the target - because we're dropping the target | |
1624 | * anyway. As such, we can just do a simple memcpy() to copy over | |
1625 | * the new name before we switch. | |
1626 | * | |
1627 | * Note that we have to be a lot more careful about getting the hash | |
1628 | * switched - we have to switch the hash value properly even if it | |
1629 | * then no longer matches the actual (corrupted) string of the target. | |
1630 | * The hash value has to match the hash queue that the dentry is on.. | |
1631 | */ | |
1632 | static void switch_names(struct dentry *dentry, struct dentry *target) | |
1633 | { | |
1634 | if (dname_external(target)) { | |
1635 | if (dname_external(dentry)) { | |
1636 | /* | |
1637 | * Both external: swap the pointers | |
1638 | */ | |
9a8d5bb4 | 1639 | swap(target->d_name.name, dentry->d_name.name); |
1da177e4 LT |
1640 | } else { |
1641 | /* | |
1642 | * dentry:internal, target:external. Steal target's | |
1643 | * storage and make target internal. | |
1644 | */ | |
321bcf92 BF |
1645 | memcpy(target->d_iname, dentry->d_name.name, |
1646 | dentry->d_name.len + 1); | |
1da177e4 LT |
1647 | dentry->d_name.name = target->d_name.name; |
1648 | target->d_name.name = target->d_iname; | |
1649 | } | |
1650 | } else { | |
1651 | if (dname_external(dentry)) { | |
1652 | /* | |
1653 | * dentry:external, target:internal. Give dentry's | |
1654 | * storage to target and make dentry internal | |
1655 | */ | |
1656 | memcpy(dentry->d_iname, target->d_name.name, | |
1657 | target->d_name.len + 1); | |
1658 | target->d_name.name = dentry->d_name.name; | |
1659 | dentry->d_name.name = dentry->d_iname; | |
1660 | } else { | |
1661 | /* | |
1662 | * Both are internal. Just copy target to dentry | |
1663 | */ | |
1664 | memcpy(dentry->d_iname, target->d_name.name, | |
1665 | target->d_name.len + 1); | |
dc711ca3 AV |
1666 | dentry->d_name.len = target->d_name.len; |
1667 | return; | |
1da177e4 LT |
1668 | } |
1669 | } | |
9a8d5bb4 | 1670 | swap(dentry->d_name.len, target->d_name.len); |
1da177e4 LT |
1671 | } |
1672 | ||
1673 | /* | |
1674 | * We cannibalize "target" when moving dentry on top of it, | |
1675 | * because it's going to be thrown away anyway. We could be more | |
1676 | * polite about it, though. | |
1677 | * | |
1678 | * This forceful removal will result in ugly /proc output if | |
1679 | * somebody holds a file open that got deleted due to a rename. | |
1680 | * We could be nicer about the deleted file, and let it show | |
bc154b1e BF |
1681 | * up under the name it had before it was deleted rather than |
1682 | * under the original name of the file that was moved on top of it. | |
1da177e4 LT |
1683 | */ |
1684 | ||
9eaef27b TM |
1685 | /* |
1686 | * d_move_locked - move a dentry | |
1da177e4 LT |
1687 | * @dentry: entry to move |
1688 | * @target: new dentry | |
1689 | * | |
1690 | * Update the dcache to reflect the move of a file name. Negative | |
1691 | * dcache entries should not be moved in this way. | |
1692 | */ | |
9eaef27b | 1693 | static void d_move_locked(struct dentry * dentry, struct dentry * target) |
1da177e4 LT |
1694 | { |
1695 | struct hlist_head *list; | |
1696 | ||
1697 | if (!dentry->d_inode) | |
1698 | printk(KERN_WARNING "VFS: moving negative dcache entry\n"); | |
1699 | ||
1da177e4 LT |
1700 | write_seqlock(&rename_lock); |
1701 | /* | |
1702 | * XXXX: do we really need to take target->d_lock? | |
1703 | */ | |
1704 | if (target < dentry) { | |
1705 | spin_lock(&target->d_lock); | |
a90b9c05 | 1706 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1707 | } else { |
1708 | spin_lock(&dentry->d_lock); | |
a90b9c05 | 1709 | spin_lock_nested(&target->d_lock, DENTRY_D_LOCK_NESTED); |
1da177e4 LT |
1710 | } |
1711 | ||
1712 | /* Move the dentry to the target hash queue, if on different bucket */ | |
f77e3498 | 1713 | if (d_unhashed(dentry)) |
1da177e4 LT |
1714 | goto already_unhashed; |
1715 | ||
1716 | hlist_del_rcu(&dentry->d_hash); | |
1717 | ||
1718 | already_unhashed: | |
1719 | list = d_hash(target->d_parent, target->d_name.hash); | |
1720 | __d_rehash(dentry, list); | |
1721 | ||
1722 | /* Unhash the target: dput() will then get rid of it */ | |
1723 | __d_drop(target); | |
1724 | ||
5160ee6f ED |
1725 | list_del(&dentry->d_u.d_child); |
1726 | list_del(&target->d_u.d_child); | |
1da177e4 LT |
1727 | |
1728 | /* Switch the names.. */ | |
1729 | switch_names(dentry, target); | |
9a8d5bb4 | 1730 | swap(dentry->d_name.hash, target->d_name.hash); |
1da177e4 LT |
1731 | |
1732 | /* ... and switch the parents */ | |
1733 | if (IS_ROOT(dentry)) { | |
1734 | dentry->d_parent = target->d_parent; | |
1735 | target->d_parent = target; | |
5160ee6f | 1736 | INIT_LIST_HEAD(&target->d_u.d_child); |
1da177e4 | 1737 | } else { |
9a8d5bb4 | 1738 | swap(dentry->d_parent, target->d_parent); |
1da177e4 LT |
1739 | |
1740 | /* And add them back to the (new) parent lists */ | |
5160ee6f | 1741 | list_add(&target->d_u.d_child, &target->d_parent->d_subdirs); |
1da177e4 LT |
1742 | } |
1743 | ||
5160ee6f | 1744 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); |
1da177e4 | 1745 | spin_unlock(&target->d_lock); |
c32ccd87 | 1746 | fsnotify_d_move(dentry); |
1da177e4 LT |
1747 | spin_unlock(&dentry->d_lock); |
1748 | write_sequnlock(&rename_lock); | |
9eaef27b TM |
1749 | } |
1750 | ||
1751 | /** | |
1752 | * d_move - move a dentry | |
1753 | * @dentry: entry to move | |
1754 | * @target: new dentry | |
1755 | * | |
1756 | * Update the dcache to reflect the move of a file name. Negative | |
1757 | * dcache entries should not be moved in this way. | |
1758 | */ | |
1759 | ||
1760 | void d_move(struct dentry * dentry, struct dentry * target) | |
1761 | { | |
1762 | spin_lock(&dcache_lock); | |
1763 | d_move_locked(dentry, target); | |
1da177e4 LT |
1764 | spin_unlock(&dcache_lock); |
1765 | } | |
ec4f8605 | 1766 | EXPORT_SYMBOL(d_move); |
1da177e4 | 1767 | |
e2761a11 OH |
1768 | /** |
1769 | * d_ancestor - search for an ancestor | |
1770 | * @p1: ancestor dentry | |
1771 | * @p2: child dentry | |
1772 | * | |
1773 | * Returns the ancestor dentry of p2 which is a child of p1, if p1 is | |
1774 | * an ancestor of p2, else NULL. | |
9eaef27b | 1775 | */ |
e2761a11 | 1776 | struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b TM |
1777 | { |
1778 | struct dentry *p; | |
1779 | ||
871c0067 | 1780 | for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b | 1781 | if (p->d_parent == p1) |
e2761a11 | 1782 | return p; |
9eaef27b | 1783 | } |
e2761a11 | 1784 | return NULL; |
9eaef27b TM |
1785 | } |
1786 | ||
1787 | /* | |
1788 | * This helper attempts to cope with remotely renamed directories | |
1789 | * | |
1790 | * It assumes that the caller is already holding | |
1791 | * dentry->d_parent->d_inode->i_mutex and the dcache_lock | |
1792 | * | |
1793 | * Note: If ever the locking in lock_rename() changes, then please | |
1794 | * remember to update this too... | |
9eaef27b TM |
1795 | */ |
1796 | static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias) | |
31f3e0b3 | 1797 | __releases(dcache_lock) |
9eaef27b TM |
1798 | { |
1799 | struct mutex *m1 = NULL, *m2 = NULL; | |
1800 | struct dentry *ret; | |
1801 | ||
1802 | /* If alias and dentry share a parent, then no extra locks required */ | |
1803 | if (alias->d_parent == dentry->d_parent) | |
1804 | goto out_unalias; | |
1805 | ||
1806 | /* Check for loops */ | |
1807 | ret = ERR_PTR(-ELOOP); | |
e2761a11 | 1808 | if (d_ancestor(alias, dentry)) |
9eaef27b TM |
1809 | goto out_err; |
1810 | ||
1811 | /* See lock_rename() */ | |
1812 | ret = ERR_PTR(-EBUSY); | |
1813 | if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) | |
1814 | goto out_err; | |
1815 | m1 = &dentry->d_sb->s_vfs_rename_mutex; | |
1816 | if (!mutex_trylock(&alias->d_parent->d_inode->i_mutex)) | |
1817 | goto out_err; | |
1818 | m2 = &alias->d_parent->d_inode->i_mutex; | |
1819 | out_unalias: | |
1820 | d_move_locked(alias, dentry); | |
1821 | ret = alias; | |
1822 | out_err: | |
1823 | spin_unlock(&dcache_lock); | |
1824 | if (m2) | |
1825 | mutex_unlock(m2); | |
1826 | if (m1) | |
1827 | mutex_unlock(m1); | |
1828 | return ret; | |
1829 | } | |
1830 | ||
770bfad8 DH |
1831 | /* |
1832 | * Prepare an anonymous dentry for life in the superblock's dentry tree as a | |
1833 | * named dentry in place of the dentry to be replaced. | |
1834 | */ | |
1835 | static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) | |
1836 | { | |
1837 | struct dentry *dparent, *aparent; | |
1838 | ||
1839 | switch_names(dentry, anon); | |
9a8d5bb4 | 1840 | swap(dentry->d_name.hash, anon->d_name.hash); |
770bfad8 DH |
1841 | |
1842 | dparent = dentry->d_parent; | |
1843 | aparent = anon->d_parent; | |
1844 | ||
1845 | dentry->d_parent = (aparent == anon) ? dentry : aparent; | |
1846 | list_del(&dentry->d_u.d_child); | |
1847 | if (!IS_ROOT(dentry)) | |
1848 | list_add(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs); | |
1849 | else | |
1850 | INIT_LIST_HEAD(&dentry->d_u.d_child); | |
1851 | ||
1852 | anon->d_parent = (dparent == dentry) ? anon : dparent; | |
1853 | list_del(&anon->d_u.d_child); | |
1854 | if (!IS_ROOT(anon)) | |
1855 | list_add(&anon->d_u.d_child, &anon->d_parent->d_subdirs); | |
1856 | else | |
1857 | INIT_LIST_HEAD(&anon->d_u.d_child); | |
1858 | ||
1859 | anon->d_flags &= ~DCACHE_DISCONNECTED; | |
1860 | } | |
1861 | ||
1862 | /** | |
1863 | * d_materialise_unique - introduce an inode into the tree | |
1864 | * @dentry: candidate dentry | |
1865 | * @inode: inode to bind to the dentry, to which aliases may be attached | |
1866 | * | |
1867 | * Introduces an dentry into the tree, substituting an extant disconnected | |
1868 | * root directory alias in its place if there is one | |
1869 | */ | |
1870 | struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) | |
1871 | { | |
9eaef27b | 1872 | struct dentry *actual; |
770bfad8 DH |
1873 | |
1874 | BUG_ON(!d_unhashed(dentry)); | |
1875 | ||
1876 | spin_lock(&dcache_lock); | |
1877 | ||
1878 | if (!inode) { | |
1879 | actual = dentry; | |
360da900 | 1880 | __d_instantiate(dentry, NULL); |
770bfad8 DH |
1881 | goto found_lock; |
1882 | } | |
1883 | ||
9eaef27b TM |
1884 | if (S_ISDIR(inode->i_mode)) { |
1885 | struct dentry *alias; | |
1886 | ||
1887 | /* Does an aliased dentry already exist? */ | |
1888 | alias = __d_find_alias(inode, 0); | |
1889 | if (alias) { | |
1890 | actual = alias; | |
1891 | /* Is this an anonymous mountpoint that we could splice | |
1892 | * into our tree? */ | |
1893 | if (IS_ROOT(alias)) { | |
1894 | spin_lock(&alias->d_lock); | |
1895 | __d_materialise_dentry(dentry, alias); | |
1896 | __d_drop(alias); | |
1897 | goto found; | |
1898 | } | |
1899 | /* Nope, but we must(!) avoid directory aliasing */ | |
1900 | actual = __d_unalias(dentry, alias); | |
1901 | if (IS_ERR(actual)) | |
1902 | dput(alias); | |
1903 | goto out_nolock; | |
1904 | } | |
770bfad8 DH |
1905 | } |
1906 | ||
1907 | /* Add a unique reference */ | |
1908 | actual = __d_instantiate_unique(dentry, inode); | |
1909 | if (!actual) | |
1910 | actual = dentry; | |
1911 | else if (unlikely(!d_unhashed(actual))) | |
1912 | goto shouldnt_be_hashed; | |
1913 | ||
1914 | found_lock: | |
1915 | spin_lock(&actual->d_lock); | |
1916 | found: | |
1917 | _d_rehash(actual); | |
1918 | spin_unlock(&actual->d_lock); | |
1919 | spin_unlock(&dcache_lock); | |
9eaef27b | 1920 | out_nolock: |
770bfad8 DH |
1921 | if (actual == dentry) { |
1922 | security_d_instantiate(dentry, inode); | |
1923 | return NULL; | |
1924 | } | |
1925 | ||
1926 | iput(inode); | |
1927 | return actual; | |
1928 | ||
770bfad8 DH |
1929 | shouldnt_be_hashed: |
1930 | spin_unlock(&dcache_lock); | |
1931 | BUG(); | |
770bfad8 | 1932 | } |
ec4f8605 | 1933 | EXPORT_SYMBOL_GPL(d_materialise_unique); |
770bfad8 | 1934 | |
cdd16d02 | 1935 | static int prepend(char **buffer, int *buflen, const char *str, int namelen) |
6092d048 RP |
1936 | { |
1937 | *buflen -= namelen; | |
1938 | if (*buflen < 0) | |
1939 | return -ENAMETOOLONG; | |
1940 | *buffer -= namelen; | |
1941 | memcpy(*buffer, str, namelen); | |
1942 | return 0; | |
1943 | } | |
1944 | ||
cdd16d02 MS |
1945 | static int prepend_name(char **buffer, int *buflen, struct qstr *name) |
1946 | { | |
1947 | return prepend(buffer, buflen, name->name, name->len); | |
1948 | } | |
1949 | ||
1da177e4 | 1950 | /** |
f2eb6575 MS |
1951 | * Prepend path string to a buffer |
1952 | * | |
9d1bc601 MS |
1953 | * @path: the dentry/vfsmount to report |
1954 | * @root: root vfsmnt/dentry (may be modified by this function) | |
f2eb6575 MS |
1955 | * @buffer: pointer to the end of the buffer |
1956 | * @buflen: pointer to buffer length | |
552ce544 | 1957 | * |
f2eb6575 | 1958 | * Caller holds the dcache_lock. |
9d1bc601 MS |
1959 | * |
1960 | * If path is not reachable from the supplied root, then the value of | |
1961 | * root is changed (without modifying refcounts). | |
1da177e4 | 1962 | */ |
f2eb6575 MS |
1963 | static int prepend_path(const struct path *path, struct path *root, |
1964 | char **buffer, int *buflen) | |
1da177e4 | 1965 | { |
9d1bc601 MS |
1966 | struct dentry *dentry = path->dentry; |
1967 | struct vfsmount *vfsmnt = path->mnt; | |
f2eb6575 MS |
1968 | bool slash = false; |
1969 | int error = 0; | |
6092d048 | 1970 | |
99b7db7b | 1971 | br_read_lock(vfsmount_lock); |
f2eb6575 | 1972 | while (dentry != root->dentry || vfsmnt != root->mnt) { |
1da177e4 LT |
1973 | struct dentry * parent; |
1974 | ||
1da177e4 | 1975 | if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) { |
552ce544 | 1976 | /* Global root? */ |
1da177e4 | 1977 | if (vfsmnt->mnt_parent == vfsmnt) { |
1da177e4 LT |
1978 | goto global_root; |
1979 | } | |
1980 | dentry = vfsmnt->mnt_mountpoint; | |
1981 | vfsmnt = vfsmnt->mnt_parent; | |
1da177e4 LT |
1982 | continue; |
1983 | } | |
1984 | parent = dentry->d_parent; | |
1985 | prefetch(parent); | |
f2eb6575 MS |
1986 | error = prepend_name(buffer, buflen, &dentry->d_name); |
1987 | if (!error) | |
1988 | error = prepend(buffer, buflen, "/", 1); | |
1989 | if (error) | |
1990 | break; | |
1991 | ||
1992 | slash = true; | |
1da177e4 LT |
1993 | dentry = parent; |
1994 | } | |
1995 | ||
be285c71 | 1996 | out: |
f2eb6575 MS |
1997 | if (!error && !slash) |
1998 | error = prepend(buffer, buflen, "/", 1); | |
1999 | ||
99b7db7b | 2000 | br_read_unlock(vfsmount_lock); |
f2eb6575 | 2001 | return error; |
1da177e4 LT |
2002 | |
2003 | global_root: | |
98dc568b MS |
2004 | /* |
2005 | * Filesystems needing to implement special "root names" | |
2006 | * should do so with ->d_dname() | |
2007 | */ | |
2008 | if (IS_ROOT(dentry) && | |
2009 | (dentry->d_name.len != 1 || dentry->d_name.name[0] != '/')) { | |
2010 | WARN(1, "Root dentry has weird name <%.*s>\n", | |
2011 | (int) dentry->d_name.len, dentry->d_name.name); | |
2012 | } | |
9d1bc601 MS |
2013 | root->mnt = vfsmnt; |
2014 | root->dentry = dentry; | |
be285c71 | 2015 | goto out; |
f2eb6575 | 2016 | } |
be285c71 | 2017 | |
f2eb6575 MS |
2018 | /** |
2019 | * __d_path - return the path of a dentry | |
2020 | * @path: the dentry/vfsmount to report | |
2021 | * @root: root vfsmnt/dentry (may be modified by this function) | |
cd956a1c | 2022 | * @buf: buffer to return value in |
f2eb6575 MS |
2023 | * @buflen: buffer length |
2024 | * | |
ffd1f4ed | 2025 | * Convert a dentry into an ASCII path name. |
f2eb6575 MS |
2026 | * |
2027 | * Returns a pointer into the buffer or an error code if the | |
2028 | * path was too long. | |
2029 | * | |
be148247 | 2030 | * "buflen" should be positive. |
f2eb6575 MS |
2031 | * |
2032 | * If path is not reachable from the supplied root, then the value of | |
2033 | * root is changed (without modifying refcounts). | |
2034 | */ | |
2035 | char *__d_path(const struct path *path, struct path *root, | |
2036 | char *buf, int buflen) | |
2037 | { | |
2038 | char *res = buf + buflen; | |
2039 | int error; | |
2040 | ||
2041 | prepend(&res, &buflen, "\0", 1); | |
be148247 | 2042 | spin_lock(&dcache_lock); |
f2eb6575 | 2043 | error = prepend_path(path, root, &res, &buflen); |
be148247 CH |
2044 | spin_unlock(&dcache_lock); |
2045 | ||
f2eb6575 MS |
2046 | if (error) |
2047 | return ERR_PTR(error); | |
f2eb6575 | 2048 | return res; |
1da177e4 LT |
2049 | } |
2050 | ||
ffd1f4ed MS |
2051 | /* |
2052 | * same as __d_path but appends "(deleted)" for unlinked files. | |
2053 | */ | |
2054 | static int path_with_deleted(const struct path *path, struct path *root, | |
2055 | char **buf, int *buflen) | |
2056 | { | |
2057 | prepend(buf, buflen, "\0", 1); | |
2058 | if (d_unlinked(path->dentry)) { | |
2059 | int error = prepend(buf, buflen, " (deleted)", 10); | |
2060 | if (error) | |
2061 | return error; | |
2062 | } | |
2063 | ||
2064 | return prepend_path(path, root, buf, buflen); | |
2065 | } | |
2066 | ||
8df9d1a4 MS |
2067 | static int prepend_unreachable(char **buffer, int *buflen) |
2068 | { | |
2069 | return prepend(buffer, buflen, "(unreachable)", 13); | |
2070 | } | |
2071 | ||
a03a8a70 JB |
2072 | /** |
2073 | * d_path - return the path of a dentry | |
cf28b486 | 2074 | * @path: path to report |
a03a8a70 JB |
2075 | * @buf: buffer to return value in |
2076 | * @buflen: buffer length | |
2077 | * | |
2078 | * Convert a dentry into an ASCII path name. If the entry has been deleted | |
2079 | * the string " (deleted)" is appended. Note that this is ambiguous. | |
2080 | * | |
52afeefb AV |
2081 | * Returns a pointer into the buffer or an error code if the path was |
2082 | * too long. Note: Callers should use the returned pointer, not the passed | |
2083 | * in buffer, to use the name! The implementation often starts at an offset | |
2084 | * into the buffer, and may leave 0 bytes at the start. | |
a03a8a70 | 2085 | * |
31f3e0b3 | 2086 | * "buflen" should be positive. |
a03a8a70 | 2087 | */ |
20d4fdc1 | 2088 | char *d_path(const struct path *path, char *buf, int buflen) |
1da177e4 | 2089 | { |
ffd1f4ed | 2090 | char *res = buf + buflen; |
6ac08c39 | 2091 | struct path root; |
9d1bc601 | 2092 | struct path tmp; |
ffd1f4ed | 2093 | int error; |
1da177e4 | 2094 | |
c23fbb6b ED |
2095 | /* |
2096 | * We have various synthetic filesystems that never get mounted. On | |
2097 | * these filesystems dentries are never used for lookup purposes, and | |
2098 | * thus don't need to be hashed. They also don't need a name until a | |
2099 | * user wants to identify the object in /proc/pid/fd/. The little hack | |
2100 | * below allows us to generate a name for these objects on demand: | |
2101 | */ | |
cf28b486 JB |
2102 | if (path->dentry->d_op && path->dentry->d_op->d_dname) |
2103 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
c23fbb6b | 2104 | |
f7ad3c6b | 2105 | get_fs_root(current->fs, &root); |
552ce544 | 2106 | spin_lock(&dcache_lock); |
9d1bc601 | 2107 | tmp = root; |
ffd1f4ed MS |
2108 | error = path_with_deleted(path, &tmp, &res, &buflen); |
2109 | if (error) | |
2110 | res = ERR_PTR(error); | |
552ce544 | 2111 | spin_unlock(&dcache_lock); |
6ac08c39 | 2112 | path_put(&root); |
1da177e4 LT |
2113 | return res; |
2114 | } | |
ec4f8605 | 2115 | EXPORT_SYMBOL(d_path); |
1da177e4 | 2116 | |
8df9d1a4 MS |
2117 | /** |
2118 | * d_path_with_unreachable - return the path of a dentry | |
2119 | * @path: path to report | |
2120 | * @buf: buffer to return value in | |
2121 | * @buflen: buffer length | |
2122 | * | |
2123 | * The difference from d_path() is that this prepends "(unreachable)" | |
2124 | * to paths which are unreachable from the current process' root. | |
2125 | */ | |
2126 | char *d_path_with_unreachable(const struct path *path, char *buf, int buflen) | |
2127 | { | |
2128 | char *res = buf + buflen; | |
2129 | struct path root; | |
2130 | struct path tmp; | |
2131 | int error; | |
2132 | ||
2133 | if (path->dentry->d_op && path->dentry->d_op->d_dname) | |
2134 | return path->dentry->d_op->d_dname(path->dentry, buf, buflen); | |
2135 | ||
2136 | get_fs_root(current->fs, &root); | |
2137 | spin_lock(&dcache_lock); | |
2138 | tmp = root; | |
2139 | error = path_with_deleted(path, &tmp, &res, &buflen); | |
2140 | if (!error && !path_equal(&tmp, &root)) | |
2141 | error = prepend_unreachable(&res, &buflen); | |
2142 | spin_unlock(&dcache_lock); | |
2143 | path_put(&root); | |
2144 | if (error) | |
2145 | res = ERR_PTR(error); | |
2146 | ||
2147 | return res; | |
2148 | } | |
2149 | ||
c23fbb6b ED |
2150 | /* |
2151 | * Helper function for dentry_operations.d_dname() members | |
2152 | */ | |
2153 | char *dynamic_dname(struct dentry *dentry, char *buffer, int buflen, | |
2154 | const char *fmt, ...) | |
2155 | { | |
2156 | va_list args; | |
2157 | char temp[64]; | |
2158 | int sz; | |
2159 | ||
2160 | va_start(args, fmt); | |
2161 | sz = vsnprintf(temp, sizeof(temp), fmt, args) + 1; | |
2162 | va_end(args); | |
2163 | ||
2164 | if (sz > sizeof(temp) || sz > buflen) | |
2165 | return ERR_PTR(-ENAMETOOLONG); | |
2166 | ||
2167 | buffer += buflen - sz; | |
2168 | return memcpy(buffer, temp, sz); | |
2169 | } | |
2170 | ||
6092d048 RP |
2171 | /* |
2172 | * Write full pathname from the root of the filesystem into the buffer. | |
2173 | */ | |
c103135c | 2174 | char *__dentry_path(struct dentry *dentry, char *buf, int buflen) |
6092d048 RP |
2175 | { |
2176 | char *end = buf + buflen; | |
2177 | char *retval; | |
2178 | ||
6092d048 | 2179 | prepend(&end, &buflen, "\0", 1); |
6092d048 RP |
2180 | if (buflen < 1) |
2181 | goto Elong; | |
2182 | /* Get '/' right */ | |
2183 | retval = end-1; | |
2184 | *retval = '/'; | |
2185 | ||
cdd16d02 MS |
2186 | while (!IS_ROOT(dentry)) { |
2187 | struct dentry *parent = dentry->d_parent; | |
6092d048 | 2188 | |
6092d048 | 2189 | prefetch(parent); |
cdd16d02 | 2190 | if ((prepend_name(&end, &buflen, &dentry->d_name) != 0) || |
6092d048 RP |
2191 | (prepend(&end, &buflen, "/", 1) != 0)) |
2192 | goto Elong; | |
2193 | ||
2194 | retval = end; | |
2195 | dentry = parent; | |
2196 | } | |
c103135c AV |
2197 | return retval; |
2198 | Elong: | |
2199 | return ERR_PTR(-ENAMETOOLONG); | |
2200 | } | |
2201 | EXPORT_SYMBOL(__dentry_path); | |
2202 | ||
2203 | char *dentry_path(struct dentry *dentry, char *buf, int buflen) | |
2204 | { | |
2205 | char *p = NULL; | |
2206 | char *retval; | |
2207 | ||
2208 | spin_lock(&dcache_lock); | |
2209 | if (d_unlinked(dentry)) { | |
2210 | p = buf + buflen; | |
2211 | if (prepend(&p, &buflen, "//deleted", 10) != 0) | |
2212 | goto Elong; | |
2213 | buflen++; | |
2214 | } | |
2215 | retval = __dentry_path(dentry, buf, buflen); | |
6092d048 | 2216 | spin_unlock(&dcache_lock); |
c103135c AV |
2217 | if (!IS_ERR(retval) && p) |
2218 | *p = '/'; /* restore '/' overriden with '\0' */ | |
6092d048 RP |
2219 | return retval; |
2220 | Elong: | |
2221 | spin_unlock(&dcache_lock); | |
2222 | return ERR_PTR(-ENAMETOOLONG); | |
2223 | } | |
2224 | ||
1da177e4 LT |
2225 | /* |
2226 | * NOTE! The user-level library version returns a | |
2227 | * character pointer. The kernel system call just | |
2228 | * returns the length of the buffer filled (which | |
2229 | * includes the ending '\0' character), or a negative | |
2230 | * error value. So libc would do something like | |
2231 | * | |
2232 | * char *getcwd(char * buf, size_t size) | |
2233 | * { | |
2234 | * int retval; | |
2235 | * | |
2236 | * retval = sys_getcwd(buf, size); | |
2237 | * if (retval >= 0) | |
2238 | * return buf; | |
2239 | * errno = -retval; | |
2240 | * return NULL; | |
2241 | * } | |
2242 | */ | |
3cdad428 | 2243 | SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) |
1da177e4 | 2244 | { |
552ce544 | 2245 | int error; |
6ac08c39 | 2246 | struct path pwd, root; |
552ce544 | 2247 | char *page = (char *) __get_free_page(GFP_USER); |
1da177e4 LT |
2248 | |
2249 | if (!page) | |
2250 | return -ENOMEM; | |
2251 | ||
f7ad3c6b | 2252 | get_fs_root_and_pwd(current->fs, &root, &pwd); |
1da177e4 | 2253 | |
552ce544 | 2254 | error = -ENOENT; |
552ce544 | 2255 | spin_lock(&dcache_lock); |
f3da392e | 2256 | if (!d_unlinked(pwd.dentry)) { |
552ce544 | 2257 | unsigned long len; |
9d1bc601 | 2258 | struct path tmp = root; |
8df9d1a4 MS |
2259 | char *cwd = page + PAGE_SIZE; |
2260 | int buflen = PAGE_SIZE; | |
1da177e4 | 2261 | |
8df9d1a4 MS |
2262 | prepend(&cwd, &buflen, "\0", 1); |
2263 | error = prepend_path(&pwd, &tmp, &cwd, &buflen); | |
552ce544 LT |
2264 | spin_unlock(&dcache_lock); |
2265 | ||
8df9d1a4 | 2266 | if (error) |
552ce544 LT |
2267 | goto out; |
2268 | ||
8df9d1a4 MS |
2269 | /* Unreachable from current root */ |
2270 | if (!path_equal(&tmp, &root)) { | |
2271 | error = prepend_unreachable(&cwd, &buflen); | |
2272 | if (error) | |
2273 | goto out; | |
2274 | } | |
2275 | ||
552ce544 LT |
2276 | error = -ERANGE; |
2277 | len = PAGE_SIZE + page - cwd; | |
2278 | if (len <= size) { | |
2279 | error = len; | |
2280 | if (copy_to_user(buf, cwd, len)) | |
2281 | error = -EFAULT; | |
2282 | } | |
2283 | } else | |
2284 | spin_unlock(&dcache_lock); | |
1da177e4 LT |
2285 | |
2286 | out: | |
6ac08c39 JB |
2287 | path_put(&pwd); |
2288 | path_put(&root); | |
1da177e4 LT |
2289 | free_page((unsigned long) page); |
2290 | return error; | |
2291 | } | |
2292 | ||
2293 | /* | |
2294 | * Test whether new_dentry is a subdirectory of old_dentry. | |
2295 | * | |
2296 | * Trivially implemented using the dcache structure | |
2297 | */ | |
2298 | ||
2299 | /** | |
2300 | * is_subdir - is new dentry a subdirectory of old_dentry | |
2301 | * @new_dentry: new dentry | |
2302 | * @old_dentry: old dentry | |
2303 | * | |
2304 | * Returns 1 if new_dentry is a subdirectory of the parent (at any depth). | |
2305 | * Returns 0 otherwise. | |
2306 | * Caller must ensure that "new_dentry" is pinned before calling is_subdir() | |
2307 | */ | |
2308 | ||
e2761a11 | 2309 | int is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4 LT |
2310 | { |
2311 | int result; | |
1da177e4 LT |
2312 | unsigned long seq; |
2313 | ||
e2761a11 OH |
2314 | if (new_dentry == old_dentry) |
2315 | return 1; | |
2316 | ||
2317 | /* | |
2318 | * Need rcu_readlock to protect against the d_parent trashing | |
2319 | * due to d_move | |
1da177e4 LT |
2320 | */ |
2321 | rcu_read_lock(); | |
e2761a11 | 2322 | do { |
1da177e4 | 2323 | /* for restarting inner loop in case of seq retry */ |
1da177e4 | 2324 | seq = read_seqbegin(&rename_lock); |
e2761a11 | 2325 | if (d_ancestor(old_dentry, new_dentry)) |
1da177e4 | 2326 | result = 1; |
e2761a11 OH |
2327 | else |
2328 | result = 0; | |
1da177e4 LT |
2329 | } while (read_seqretry(&rename_lock, seq)); |
2330 | rcu_read_unlock(); | |
2331 | ||
2332 | return result; | |
2333 | } | |
2334 | ||
2096f759 AV |
2335 | int path_is_under(struct path *path1, struct path *path2) |
2336 | { | |
2337 | struct vfsmount *mnt = path1->mnt; | |
2338 | struct dentry *dentry = path1->dentry; | |
2339 | int res; | |
99b7db7b NP |
2340 | |
2341 | br_read_lock(vfsmount_lock); | |
2096f759 AV |
2342 | if (mnt != path2->mnt) { |
2343 | for (;;) { | |
2344 | if (mnt->mnt_parent == mnt) { | |
99b7db7b | 2345 | br_read_unlock(vfsmount_lock); |
2096f759 AV |
2346 | return 0; |
2347 | } | |
2348 | if (mnt->mnt_parent == path2->mnt) | |
2349 | break; | |
2350 | mnt = mnt->mnt_parent; | |
2351 | } | |
2352 | dentry = mnt->mnt_mountpoint; | |
2353 | } | |
2354 | res = is_subdir(dentry, path2->dentry); | |
99b7db7b | 2355 | br_read_unlock(vfsmount_lock); |
2096f759 AV |
2356 | return res; |
2357 | } | |
2358 | EXPORT_SYMBOL(path_is_under); | |
2359 | ||
1da177e4 LT |
2360 | void d_genocide(struct dentry *root) |
2361 | { | |
2362 | struct dentry *this_parent = root; | |
2363 | struct list_head *next; | |
2364 | ||
2365 | spin_lock(&dcache_lock); | |
2366 | repeat: | |
2367 | next = this_parent->d_subdirs.next; | |
2368 | resume: | |
2369 | while (next != &this_parent->d_subdirs) { | |
2370 | struct list_head *tmp = next; | |
5160ee6f | 2371 | struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child); |
1da177e4 LT |
2372 | next = tmp->next; |
2373 | if (d_unhashed(dentry)||!dentry->d_inode) | |
2374 | continue; | |
2375 | if (!list_empty(&dentry->d_subdirs)) { | |
2376 | this_parent = dentry; | |
2377 | goto repeat; | |
2378 | } | |
2379 | atomic_dec(&dentry->d_count); | |
2380 | } | |
2381 | if (this_parent != root) { | |
5160ee6f | 2382 | next = this_parent->d_u.d_child.next; |
1da177e4 LT |
2383 | atomic_dec(&this_parent->d_count); |
2384 | this_parent = this_parent->d_parent; | |
2385 | goto resume; | |
2386 | } | |
2387 | spin_unlock(&dcache_lock); | |
2388 | } | |
2389 | ||
2390 | /** | |
2391 | * find_inode_number - check for dentry with name | |
2392 | * @dir: directory to check | |
2393 | * @name: Name to find. | |
2394 | * | |
2395 | * Check whether a dentry already exists for the given name, | |
2396 | * and return the inode number if it has an inode. Otherwise | |
2397 | * 0 is returned. | |
2398 | * | |
2399 | * This routine is used to post-process directory listings for | |
2400 | * filesystems using synthetic inode numbers, and is necessary | |
2401 | * to keep getcwd() working. | |
2402 | */ | |
2403 | ||
2404 | ino_t find_inode_number(struct dentry *dir, struct qstr *name) | |
2405 | { | |
2406 | struct dentry * dentry; | |
2407 | ino_t ino = 0; | |
2408 | ||
3e7e241f EB |
2409 | dentry = d_hash_and_lookup(dir, name); |
2410 | if (dentry) { | |
1da177e4 LT |
2411 | if (dentry->d_inode) |
2412 | ino = dentry->d_inode->i_ino; | |
2413 | dput(dentry); | |
2414 | } | |
1da177e4 LT |
2415 | return ino; |
2416 | } | |
ec4f8605 | 2417 | EXPORT_SYMBOL(find_inode_number); |
1da177e4 LT |
2418 | |
2419 | static __initdata unsigned long dhash_entries; | |
2420 | static int __init set_dhash_entries(char *str) | |
2421 | { | |
2422 | if (!str) | |
2423 | return 0; | |
2424 | dhash_entries = simple_strtoul(str, &str, 0); | |
2425 | return 1; | |
2426 | } | |
2427 | __setup("dhash_entries=", set_dhash_entries); | |
2428 | ||
2429 | static void __init dcache_init_early(void) | |
2430 | { | |
2431 | int loop; | |
2432 | ||
2433 | /* If hashes are distributed across NUMA nodes, defer | |
2434 | * hash allocation until vmalloc space is available. | |
2435 | */ | |
2436 | if (hashdist) | |
2437 | return; | |
2438 | ||
2439 | dentry_hashtable = | |
2440 | alloc_large_system_hash("Dentry cache", | |
2441 | sizeof(struct hlist_head), | |
2442 | dhash_entries, | |
2443 | 13, | |
2444 | HASH_EARLY, | |
2445 | &d_hash_shift, | |
2446 | &d_hash_mask, | |
2447 | 0); | |
2448 | ||
2449 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2450 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2451 | } | |
2452 | ||
74bf17cf | 2453 | static void __init dcache_init(void) |
1da177e4 LT |
2454 | { |
2455 | int loop; | |
2456 | ||
2457 | /* | |
2458 | * A constructor could be added for stable state like the lists, | |
2459 | * but it is probably not worth it because of the cache nature | |
2460 | * of the dcache. | |
2461 | */ | |
0a31bd5f CL |
2462 | dentry_cache = KMEM_CACHE(dentry, |
2463 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 | 2464 | |
8e1f936b | 2465 | register_shrinker(&dcache_shrinker); |
1da177e4 LT |
2466 | |
2467 | /* Hash may have been set up in dcache_init_early */ | |
2468 | if (!hashdist) | |
2469 | return; | |
2470 | ||
2471 | dentry_hashtable = | |
2472 | alloc_large_system_hash("Dentry cache", | |
2473 | sizeof(struct hlist_head), | |
2474 | dhash_entries, | |
2475 | 13, | |
2476 | 0, | |
2477 | &d_hash_shift, | |
2478 | &d_hash_mask, | |
2479 | 0); | |
2480 | ||
2481 | for (loop = 0; loop < (1 << d_hash_shift); loop++) | |
2482 | INIT_HLIST_HEAD(&dentry_hashtable[loop]); | |
2483 | } | |
2484 | ||
2485 | /* SLAB cache for __getname() consumers */ | |
e18b890b | 2486 | struct kmem_cache *names_cachep __read_mostly; |
ec4f8605 | 2487 | EXPORT_SYMBOL(names_cachep); |
1da177e4 | 2488 | |
1da177e4 LT |
2489 | EXPORT_SYMBOL(d_genocide); |
2490 | ||
1da177e4 LT |
2491 | void __init vfs_caches_init_early(void) |
2492 | { | |
2493 | dcache_init_early(); | |
2494 | inode_init_early(); | |
2495 | } | |
2496 | ||
2497 | void __init vfs_caches_init(unsigned long mempages) | |
2498 | { | |
2499 | unsigned long reserve; | |
2500 | ||
2501 | /* Base hash sizes on available memory, with a reserve equal to | |
2502 | 150% of current kernel size */ | |
2503 | ||
2504 | reserve = min((mempages - nr_free_pages()) * 3/2, mempages - 1); | |
2505 | mempages -= reserve; | |
2506 | ||
2507 | names_cachep = kmem_cache_create("names_cache", PATH_MAX, 0, | |
20c2df83 | 2508 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); |
1da177e4 | 2509 | |
74bf17cf DC |
2510 | dcache_init(); |
2511 | inode_init(); | |
1da177e4 | 2512 | files_init(mempages); |
74bf17cf | 2513 | mnt_init(); |
1da177e4 LT |
2514 | bdev_cache_init(); |
2515 | chrdev_init(); | |
2516 | } |