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1 | /* | |
2 | * fs/kernfs/dir.c - kernfs directory implementation | |
3 | * | |
4 | * Copyright (c) 2001-3 Patrick Mochel | |
5 | * Copyright (c) 2007 SUSE Linux Products GmbH | |
6 | * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> | |
7 | * | |
8 | * This file is released under the GPLv2. | |
9 | */ | |
10 | ||
11 | #include <linux/sched.h> | |
12 | #include <linux/fs.h> | |
13 | #include <linux/namei.h> | |
14 | #include <linux/idr.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/security.h> | |
17 | #include <linux/hash.h> | |
18 | ||
19 | #include "kernfs-internal.h" | |
20 | ||
21 | DEFINE_MUTEX(kernfs_mutex); | |
22 | static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ | |
23 | static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */ | |
24 | ||
25 | #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) | |
26 | ||
27 | static bool kernfs_active(struct kernfs_node *kn) | |
28 | { | |
29 | lockdep_assert_held(&kernfs_mutex); | |
30 | return atomic_read(&kn->active) >= 0; | |
31 | } | |
32 | ||
33 | static bool kernfs_lockdep(struct kernfs_node *kn) | |
34 | { | |
35 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
36 | return kn->flags & KERNFS_LOCKDEP; | |
37 | #else | |
38 | return false; | |
39 | #endif | |
40 | } | |
41 | ||
42 | static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) | |
43 | { | |
44 | return strlcpy(buf, kn->parent ? kn->name : "/", buflen); | |
45 | } | |
46 | ||
47 | static char * __must_check kernfs_path_locked(struct kernfs_node *kn, char *buf, | |
48 | size_t buflen) | |
49 | { | |
50 | char *p = buf + buflen; | |
51 | int len; | |
52 | ||
53 | *--p = '\0'; | |
54 | ||
55 | do { | |
56 | len = strlen(kn->name); | |
57 | if (p - buf < len + 1) { | |
58 | buf[0] = '\0'; | |
59 | p = NULL; | |
60 | break; | |
61 | } | |
62 | p -= len; | |
63 | memcpy(p, kn->name, len); | |
64 | *--p = '/'; | |
65 | kn = kn->parent; | |
66 | } while (kn && kn->parent); | |
67 | ||
68 | return p; | |
69 | } | |
70 | ||
71 | /** | |
72 | * kernfs_name - obtain the name of a given node | |
73 | * @kn: kernfs_node of interest | |
74 | * @buf: buffer to copy @kn's name into | |
75 | * @buflen: size of @buf | |
76 | * | |
77 | * Copies the name of @kn into @buf of @buflen bytes. The behavior is | |
78 | * similar to strlcpy(). It returns the length of @kn's name and if @buf | |
79 | * isn't long enough, it's filled upto @buflen-1 and nul terminated. | |
80 | * | |
81 | * This function can be called from any context. | |
82 | */ | |
83 | int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) | |
84 | { | |
85 | unsigned long flags; | |
86 | int ret; | |
87 | ||
88 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
89 | ret = kernfs_name_locked(kn, buf, buflen); | |
90 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
91 | return ret; | |
92 | } | |
93 | ||
94 | /** | |
95 | * kernfs_path - build full path of a given node | |
96 | * @kn: kernfs_node of interest | |
97 | * @buf: buffer to copy @kn's name into | |
98 | * @buflen: size of @buf | |
99 | * | |
100 | * Builds and returns the full path of @kn in @buf of @buflen bytes. The | |
101 | * path is built from the end of @buf so the returned pointer usually | |
102 | * doesn't match @buf. If @buf isn't long enough, @buf is nul terminated | |
103 | * and %NULL is returned. | |
104 | */ | |
105 | char *kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen) | |
106 | { | |
107 | unsigned long flags; | |
108 | char *p; | |
109 | ||
110 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
111 | p = kernfs_path_locked(kn, buf, buflen); | |
112 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
113 | return p; | |
114 | } | |
115 | EXPORT_SYMBOL_GPL(kernfs_path); | |
116 | ||
117 | /** | |
118 | * pr_cont_kernfs_name - pr_cont name of a kernfs_node | |
119 | * @kn: kernfs_node of interest | |
120 | * | |
121 | * This function can be called from any context. | |
122 | */ | |
123 | void pr_cont_kernfs_name(struct kernfs_node *kn) | |
124 | { | |
125 | unsigned long flags; | |
126 | ||
127 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
128 | ||
129 | kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); | |
130 | pr_cont("%s", kernfs_pr_cont_buf); | |
131 | ||
132 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
133 | } | |
134 | ||
135 | /** | |
136 | * pr_cont_kernfs_path - pr_cont path of a kernfs_node | |
137 | * @kn: kernfs_node of interest | |
138 | * | |
139 | * This function can be called from any context. | |
140 | */ | |
141 | void pr_cont_kernfs_path(struct kernfs_node *kn) | |
142 | { | |
143 | unsigned long flags; | |
144 | char *p; | |
145 | ||
146 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
147 | ||
148 | p = kernfs_path_locked(kn, kernfs_pr_cont_buf, | |
149 | sizeof(kernfs_pr_cont_buf)); | |
150 | if (p) | |
151 | pr_cont("%s", p); | |
152 | else | |
153 | pr_cont("<name too long>"); | |
154 | ||
155 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
156 | } | |
157 | ||
158 | /** | |
159 | * kernfs_get_parent - determine the parent node and pin it | |
160 | * @kn: kernfs_node of interest | |
161 | * | |
162 | * Determines @kn's parent, pins and returns it. This function can be | |
163 | * called from any context. | |
164 | */ | |
165 | struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) | |
166 | { | |
167 | struct kernfs_node *parent; | |
168 | unsigned long flags; | |
169 | ||
170 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
171 | parent = kn->parent; | |
172 | kernfs_get(parent); | |
173 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
174 | ||
175 | return parent; | |
176 | } | |
177 | ||
178 | /** | |
179 | * kernfs_name_hash | |
180 | * @name: Null terminated string to hash | |
181 | * @ns: Namespace tag to hash | |
182 | * | |
183 | * Returns 31 bit hash of ns + name (so it fits in an off_t ) | |
184 | */ | |
185 | static unsigned int kernfs_name_hash(const char *name, const void *ns) | |
186 | { | |
187 | unsigned long hash = init_name_hash(); | |
188 | unsigned int len = strlen(name); | |
189 | while (len--) | |
190 | hash = partial_name_hash(*name++, hash); | |
191 | hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31)); | |
192 | hash &= 0x7fffffffU; | |
193 | /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ | |
194 | if (hash < 2) | |
195 | hash += 2; | |
196 | if (hash >= INT_MAX) | |
197 | hash = INT_MAX - 1; | |
198 | return hash; | |
199 | } | |
200 | ||
201 | static int kernfs_name_compare(unsigned int hash, const char *name, | |
202 | const void *ns, const struct kernfs_node *kn) | |
203 | { | |
204 | if (hash < kn->hash) | |
205 | return -1; | |
206 | if (hash > kn->hash) | |
207 | return 1; | |
208 | if (ns < kn->ns) | |
209 | return -1; | |
210 | if (ns > kn->ns) | |
211 | return 1; | |
212 | return strcmp(name, kn->name); | |
213 | } | |
214 | ||
215 | static int kernfs_sd_compare(const struct kernfs_node *left, | |
216 | const struct kernfs_node *right) | |
217 | { | |
218 | return kernfs_name_compare(left->hash, left->name, left->ns, right); | |
219 | } | |
220 | ||
221 | /** | |
222 | * kernfs_link_sibling - link kernfs_node into sibling rbtree | |
223 | * @kn: kernfs_node of interest | |
224 | * | |
225 | * Link @kn into its sibling rbtree which starts from | |
226 | * @kn->parent->dir.children. | |
227 | * | |
228 | * Locking: | |
229 | * mutex_lock(kernfs_mutex) | |
230 | * | |
231 | * RETURNS: | |
232 | * 0 on susccess -EEXIST on failure. | |
233 | */ | |
234 | static int kernfs_link_sibling(struct kernfs_node *kn) | |
235 | { | |
236 | struct rb_node **node = &kn->parent->dir.children.rb_node; | |
237 | struct rb_node *parent = NULL; | |
238 | ||
239 | while (*node) { | |
240 | struct kernfs_node *pos; | |
241 | int result; | |
242 | ||
243 | pos = rb_to_kn(*node); | |
244 | parent = *node; | |
245 | result = kernfs_sd_compare(kn, pos); | |
246 | if (result < 0) | |
247 | node = &pos->rb.rb_left; | |
248 | else if (result > 0) | |
249 | node = &pos->rb.rb_right; | |
250 | else | |
251 | return -EEXIST; | |
252 | } | |
253 | ||
254 | /* add new node and rebalance the tree */ | |
255 | rb_link_node(&kn->rb, parent, node); | |
256 | rb_insert_color(&kn->rb, &kn->parent->dir.children); | |
257 | ||
258 | /* successfully added, account subdir number */ | |
259 | if (kernfs_type(kn) == KERNFS_DIR) | |
260 | kn->parent->dir.subdirs++; | |
261 | ||
262 | return 0; | |
263 | } | |
264 | ||
265 | /** | |
266 | * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree | |
267 | * @kn: kernfs_node of interest | |
268 | * | |
269 | * Try to unlink @kn from its sibling rbtree which starts from | |
270 | * kn->parent->dir.children. Returns %true if @kn was actually | |
271 | * removed, %false if @kn wasn't on the rbtree. | |
272 | * | |
273 | * Locking: | |
274 | * mutex_lock(kernfs_mutex) | |
275 | */ | |
276 | static bool kernfs_unlink_sibling(struct kernfs_node *kn) | |
277 | { | |
278 | if (RB_EMPTY_NODE(&kn->rb)) | |
279 | return false; | |
280 | ||
281 | if (kernfs_type(kn) == KERNFS_DIR) | |
282 | kn->parent->dir.subdirs--; | |
283 | ||
284 | rb_erase(&kn->rb, &kn->parent->dir.children); | |
285 | RB_CLEAR_NODE(&kn->rb); | |
286 | return true; | |
287 | } | |
288 | ||
289 | /** | |
290 | * kernfs_get_active - get an active reference to kernfs_node | |
291 | * @kn: kernfs_node to get an active reference to | |
292 | * | |
293 | * Get an active reference of @kn. This function is noop if @kn | |
294 | * is NULL. | |
295 | * | |
296 | * RETURNS: | |
297 | * Pointer to @kn on success, NULL on failure. | |
298 | */ | |
299 | struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) | |
300 | { | |
301 | if (unlikely(!kn)) | |
302 | return NULL; | |
303 | ||
304 | if (!atomic_inc_unless_negative(&kn->active)) | |
305 | return NULL; | |
306 | ||
307 | if (kernfs_lockdep(kn)) | |
308 | rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); | |
309 | return kn; | |
310 | } | |
311 | ||
312 | /** | |
313 | * kernfs_put_active - put an active reference to kernfs_node | |
314 | * @kn: kernfs_node to put an active reference to | |
315 | * | |
316 | * Put an active reference to @kn. This function is noop if @kn | |
317 | * is NULL. | |
318 | */ | |
319 | void kernfs_put_active(struct kernfs_node *kn) | |
320 | { | |
321 | struct kernfs_root *root = kernfs_root(kn); | |
322 | int v; | |
323 | ||
324 | if (unlikely(!kn)) | |
325 | return; | |
326 | ||
327 | if (kernfs_lockdep(kn)) | |
328 | rwsem_release(&kn->dep_map, 1, _RET_IP_); | |
329 | v = atomic_dec_return(&kn->active); | |
330 | if (likely(v != KN_DEACTIVATED_BIAS)) | |
331 | return; | |
332 | ||
333 | wake_up_all(&root->deactivate_waitq); | |
334 | } | |
335 | ||
336 | /** | |
337 | * kernfs_drain - drain kernfs_node | |
338 | * @kn: kernfs_node to drain | |
339 | * | |
340 | * Drain existing usages and nuke all existing mmaps of @kn. Mutiple | |
341 | * removers may invoke this function concurrently on @kn and all will | |
342 | * return after draining is complete. | |
343 | */ | |
344 | static void kernfs_drain(struct kernfs_node *kn) | |
345 | __releases(&kernfs_mutex) __acquires(&kernfs_mutex) | |
346 | { | |
347 | struct kernfs_root *root = kernfs_root(kn); | |
348 | ||
349 | lockdep_assert_held(&kernfs_mutex); | |
350 | WARN_ON_ONCE(kernfs_active(kn)); | |
351 | ||
352 | mutex_unlock(&kernfs_mutex); | |
353 | ||
354 | if (kernfs_lockdep(kn)) { | |
355 | rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); | |
356 | if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) | |
357 | lock_contended(&kn->dep_map, _RET_IP_); | |
358 | } | |
359 | ||
360 | /* but everyone should wait for draining */ | |
361 | wait_event(root->deactivate_waitq, | |
362 | atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); | |
363 | ||
364 | if (kernfs_lockdep(kn)) { | |
365 | lock_acquired(&kn->dep_map, _RET_IP_); | |
366 | rwsem_release(&kn->dep_map, 1, _RET_IP_); | |
367 | } | |
368 | ||
369 | kernfs_unmap_bin_file(kn); | |
370 | ||
371 | mutex_lock(&kernfs_mutex); | |
372 | } | |
373 | ||
374 | /** | |
375 | * kernfs_get - get a reference count on a kernfs_node | |
376 | * @kn: the target kernfs_node | |
377 | */ | |
378 | void kernfs_get(struct kernfs_node *kn) | |
379 | { | |
380 | if (kn) { | |
381 | WARN_ON(!atomic_read(&kn->count)); | |
382 | atomic_inc(&kn->count); | |
383 | } | |
384 | } | |
385 | EXPORT_SYMBOL_GPL(kernfs_get); | |
386 | ||
387 | /** | |
388 | * kernfs_put - put a reference count on a kernfs_node | |
389 | * @kn: the target kernfs_node | |
390 | * | |
391 | * Put a reference count of @kn and destroy it if it reached zero. | |
392 | */ | |
393 | void kernfs_put(struct kernfs_node *kn) | |
394 | { | |
395 | struct kernfs_node *parent; | |
396 | struct kernfs_root *root; | |
397 | ||
398 | if (!kn || !atomic_dec_and_test(&kn->count)) | |
399 | return; | |
400 | root = kernfs_root(kn); | |
401 | repeat: | |
402 | /* | |
403 | * Moving/renaming is always done while holding reference. | |
404 | * kn->parent won't change beneath us. | |
405 | */ | |
406 | parent = kn->parent; | |
407 | ||
408 | WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS, | |
409 | "kernfs_put: %s/%s: released with incorrect active_ref %d\n", | |
410 | parent ? parent->name : "", kn->name, atomic_read(&kn->active)); | |
411 | ||
412 | if (kernfs_type(kn) == KERNFS_LINK) | |
413 | kernfs_put(kn->symlink.target_kn); | |
414 | if (!(kn->flags & KERNFS_STATIC_NAME)) | |
415 | kfree(kn->name); | |
416 | if (kn->iattr) { | |
417 | if (kn->iattr->ia_secdata) | |
418 | security_release_secctx(kn->iattr->ia_secdata, | |
419 | kn->iattr->ia_secdata_len); | |
420 | simple_xattrs_free(&kn->iattr->xattrs); | |
421 | } | |
422 | kfree(kn->iattr); | |
423 | ida_simple_remove(&root->ino_ida, kn->ino); | |
424 | kmem_cache_free(kernfs_node_cache, kn); | |
425 | ||
426 | kn = parent; | |
427 | if (kn) { | |
428 | if (atomic_dec_and_test(&kn->count)) | |
429 | goto repeat; | |
430 | } else { | |
431 | /* just released the root kn, free @root too */ | |
432 | ida_destroy(&root->ino_ida); | |
433 | kfree(root); | |
434 | } | |
435 | } | |
436 | EXPORT_SYMBOL_GPL(kernfs_put); | |
437 | ||
438 | static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) | |
439 | { | |
440 | struct kernfs_node *kn; | |
441 | ||
442 | if (flags & LOOKUP_RCU) | |
443 | return -ECHILD; | |
444 | ||
445 | /* Always perform fresh lookup for negatives */ | |
446 | if (!dentry->d_inode) | |
447 | goto out_bad_unlocked; | |
448 | ||
449 | kn = dentry->d_fsdata; | |
450 | mutex_lock(&kernfs_mutex); | |
451 | ||
452 | /* The kernfs node has been deactivated */ | |
453 | if (!kernfs_active(kn)) | |
454 | goto out_bad; | |
455 | ||
456 | /* The kernfs node has been moved? */ | |
457 | if (dentry->d_parent->d_fsdata != kn->parent) | |
458 | goto out_bad; | |
459 | ||
460 | /* The kernfs node has been renamed */ | |
461 | if (strcmp(dentry->d_name.name, kn->name) != 0) | |
462 | goto out_bad; | |
463 | ||
464 | /* The kernfs node has been moved to a different namespace */ | |
465 | if (kn->parent && kernfs_ns_enabled(kn->parent) && | |
466 | kernfs_info(dentry->d_sb)->ns != kn->ns) | |
467 | goto out_bad; | |
468 | ||
469 | mutex_unlock(&kernfs_mutex); | |
470 | return 1; | |
471 | out_bad: | |
472 | mutex_unlock(&kernfs_mutex); | |
473 | out_bad_unlocked: | |
474 | return 0; | |
475 | } | |
476 | ||
477 | static void kernfs_dop_release(struct dentry *dentry) | |
478 | { | |
479 | kernfs_put(dentry->d_fsdata); | |
480 | } | |
481 | ||
482 | const struct dentry_operations kernfs_dops = { | |
483 | .d_revalidate = kernfs_dop_revalidate, | |
484 | .d_release = kernfs_dop_release, | |
485 | }; | |
486 | ||
487 | /** | |
488 | * kernfs_node_from_dentry - determine kernfs_node associated with a dentry | |
489 | * @dentry: the dentry in question | |
490 | * | |
491 | * Return the kernfs_node associated with @dentry. If @dentry is not a | |
492 | * kernfs one, %NULL is returned. | |
493 | * | |
494 | * While the returned kernfs_node will stay accessible as long as @dentry | |
495 | * is accessible, the returned node can be in any state and the caller is | |
496 | * fully responsible for determining what's accessible. | |
497 | */ | |
498 | struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) | |
499 | { | |
500 | if (dentry->d_sb->s_op == &kernfs_sops) | |
501 | return dentry->d_fsdata; | |
502 | return NULL; | |
503 | } | |
504 | ||
505 | static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, | |
506 | const char *name, umode_t mode, | |
507 | unsigned flags) | |
508 | { | |
509 | char *dup_name = NULL; | |
510 | struct kernfs_node *kn; | |
511 | int ret; | |
512 | ||
513 | if (!(flags & KERNFS_STATIC_NAME)) { | |
514 | name = dup_name = kstrdup(name, GFP_KERNEL); | |
515 | if (!name) | |
516 | return NULL; | |
517 | } | |
518 | ||
519 | kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL); | |
520 | if (!kn) | |
521 | goto err_out1; | |
522 | ||
523 | ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL); | |
524 | if (ret < 0) | |
525 | goto err_out2; | |
526 | kn->ino = ret; | |
527 | ||
528 | atomic_set(&kn->count, 1); | |
529 | atomic_set(&kn->active, KN_DEACTIVATED_BIAS); | |
530 | RB_CLEAR_NODE(&kn->rb); | |
531 | ||
532 | kn->name = name; | |
533 | kn->mode = mode; | |
534 | kn->flags = flags; | |
535 | ||
536 | return kn; | |
537 | ||
538 | err_out2: | |
539 | kmem_cache_free(kernfs_node_cache, kn); | |
540 | err_out1: | |
541 | kfree(dup_name); | |
542 | return NULL; | |
543 | } | |
544 | ||
545 | struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, | |
546 | const char *name, umode_t mode, | |
547 | unsigned flags) | |
548 | { | |
549 | struct kernfs_node *kn; | |
550 | ||
551 | kn = __kernfs_new_node(kernfs_root(parent), name, mode, flags); | |
552 | if (kn) { | |
553 | kernfs_get(parent); | |
554 | kn->parent = parent; | |
555 | } | |
556 | return kn; | |
557 | } | |
558 | ||
559 | /** | |
560 | * kernfs_add_one - add kernfs_node to parent without warning | |
561 | * @kn: kernfs_node to be added | |
562 | * | |
563 | * The caller must already have initialized @kn->parent. This | |
564 | * function increments nlink of the parent's inode if @kn is a | |
565 | * directory and link into the children list of the parent. | |
566 | * | |
567 | * RETURNS: | |
568 | * 0 on success, -EEXIST if entry with the given name already | |
569 | * exists. | |
570 | */ | |
571 | int kernfs_add_one(struct kernfs_node *kn) | |
572 | { | |
573 | struct kernfs_node *parent = kn->parent; | |
574 | struct kernfs_iattrs *ps_iattr; | |
575 | bool has_ns; | |
576 | int ret; | |
577 | ||
578 | mutex_lock(&kernfs_mutex); | |
579 | ||
580 | ret = -EINVAL; | |
581 | has_ns = kernfs_ns_enabled(parent); | |
582 | if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", | |
583 | has_ns ? "required" : "invalid", parent->name, kn->name)) | |
584 | goto out_unlock; | |
585 | ||
586 | if (kernfs_type(parent) != KERNFS_DIR) | |
587 | goto out_unlock; | |
588 | ||
589 | ret = -ENOENT; | |
590 | if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent)) | |
591 | goto out_unlock; | |
592 | ||
593 | kn->hash = kernfs_name_hash(kn->name, kn->ns); | |
594 | ||
595 | ret = kernfs_link_sibling(kn); | |
596 | if (ret) | |
597 | goto out_unlock; | |
598 | ||
599 | /* Update timestamps on the parent */ | |
600 | ps_iattr = parent->iattr; | |
601 | if (ps_iattr) { | |
602 | struct iattr *ps_iattrs = &ps_iattr->ia_iattr; | |
603 | ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; | |
604 | } | |
605 | ||
606 | mutex_unlock(&kernfs_mutex); | |
607 | ||
608 | /* | |
609 | * Activate the new node unless CREATE_DEACTIVATED is requested. | |
610 | * If not activated here, the kernfs user is responsible for | |
611 | * activating the node with kernfs_activate(). A node which hasn't | |
612 | * been activated is not visible to userland and its removal won't | |
613 | * trigger deactivation. | |
614 | */ | |
615 | if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) | |
616 | kernfs_activate(kn); | |
617 | return 0; | |
618 | ||
619 | out_unlock: | |
620 | mutex_unlock(&kernfs_mutex); | |
621 | return ret; | |
622 | } | |
623 | ||
624 | /** | |
625 | * kernfs_find_ns - find kernfs_node with the given name | |
626 | * @parent: kernfs_node to search under | |
627 | * @name: name to look for | |
628 | * @ns: the namespace tag to use | |
629 | * | |
630 | * Look for kernfs_node with name @name under @parent. Returns pointer to | |
631 | * the found kernfs_node on success, %NULL on failure. | |
632 | */ | |
633 | static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, | |
634 | const unsigned char *name, | |
635 | const void *ns) | |
636 | { | |
637 | struct rb_node *node = parent->dir.children.rb_node; | |
638 | bool has_ns = kernfs_ns_enabled(parent); | |
639 | unsigned int hash; | |
640 | ||
641 | lockdep_assert_held(&kernfs_mutex); | |
642 | ||
643 | if (has_ns != (bool)ns) { | |
644 | WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", | |
645 | has_ns ? "required" : "invalid", parent->name, name); | |
646 | return NULL; | |
647 | } | |
648 | ||
649 | hash = kernfs_name_hash(name, ns); | |
650 | while (node) { | |
651 | struct kernfs_node *kn; | |
652 | int result; | |
653 | ||
654 | kn = rb_to_kn(node); | |
655 | result = kernfs_name_compare(hash, name, ns, kn); | |
656 | if (result < 0) | |
657 | node = node->rb_left; | |
658 | else if (result > 0) | |
659 | node = node->rb_right; | |
660 | else | |
661 | return kn; | |
662 | } | |
663 | return NULL; | |
664 | } | |
665 | ||
666 | /** | |
667 | * kernfs_find_and_get_ns - find and get kernfs_node with the given name | |
668 | * @parent: kernfs_node to search under | |
669 | * @name: name to look for | |
670 | * @ns: the namespace tag to use | |
671 | * | |
672 | * Look for kernfs_node with name @name under @parent and get a reference | |
673 | * if found. This function may sleep and returns pointer to the found | |
674 | * kernfs_node on success, %NULL on failure. | |
675 | */ | |
676 | struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, | |
677 | const char *name, const void *ns) | |
678 | { | |
679 | struct kernfs_node *kn; | |
680 | ||
681 | mutex_lock(&kernfs_mutex); | |
682 | kn = kernfs_find_ns(parent, name, ns); | |
683 | kernfs_get(kn); | |
684 | mutex_unlock(&kernfs_mutex); | |
685 | ||
686 | return kn; | |
687 | } | |
688 | EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); | |
689 | ||
690 | /** | |
691 | * kernfs_create_root - create a new kernfs hierarchy | |
692 | * @scops: optional syscall operations for the hierarchy | |
693 | * @flags: KERNFS_ROOT_* flags | |
694 | * @priv: opaque data associated with the new directory | |
695 | * | |
696 | * Returns the root of the new hierarchy on success, ERR_PTR() value on | |
697 | * failure. | |
698 | */ | |
699 | struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, | |
700 | unsigned int flags, void *priv) | |
701 | { | |
702 | struct kernfs_root *root; | |
703 | struct kernfs_node *kn; | |
704 | ||
705 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
706 | if (!root) | |
707 | return ERR_PTR(-ENOMEM); | |
708 | ||
709 | ida_init(&root->ino_ida); | |
710 | INIT_LIST_HEAD(&root->supers); | |
711 | ||
712 | kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO, | |
713 | KERNFS_DIR); | |
714 | if (!kn) { | |
715 | ida_destroy(&root->ino_ida); | |
716 | kfree(root); | |
717 | return ERR_PTR(-ENOMEM); | |
718 | } | |
719 | ||
720 | kn->priv = priv; | |
721 | kn->dir.root = root; | |
722 | ||
723 | root->syscall_ops = scops; | |
724 | root->flags = flags; | |
725 | root->kn = kn; | |
726 | init_waitqueue_head(&root->deactivate_waitq); | |
727 | ||
728 | if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) | |
729 | kernfs_activate(kn); | |
730 | ||
731 | return root; | |
732 | } | |
733 | ||
734 | /** | |
735 | * kernfs_destroy_root - destroy a kernfs hierarchy | |
736 | * @root: root of the hierarchy to destroy | |
737 | * | |
738 | * Destroy the hierarchy anchored at @root by removing all existing | |
739 | * directories and destroying @root. | |
740 | */ | |
741 | void kernfs_destroy_root(struct kernfs_root *root) | |
742 | { | |
743 | kernfs_remove(root->kn); /* will also free @root */ | |
744 | } | |
745 | ||
746 | /** | |
747 | * kernfs_create_dir_ns - create a directory | |
748 | * @parent: parent in which to create a new directory | |
749 | * @name: name of the new directory | |
750 | * @mode: mode of the new directory | |
751 | * @priv: opaque data associated with the new directory | |
752 | * @ns: optional namespace tag of the directory | |
753 | * | |
754 | * Returns the created node on success, ERR_PTR() value on failure. | |
755 | */ | |
756 | struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, | |
757 | const char *name, umode_t mode, | |
758 | void *priv, const void *ns) | |
759 | { | |
760 | struct kernfs_node *kn; | |
761 | int rc; | |
762 | ||
763 | /* allocate */ | |
764 | kn = kernfs_new_node(parent, name, mode | S_IFDIR, KERNFS_DIR); | |
765 | if (!kn) | |
766 | return ERR_PTR(-ENOMEM); | |
767 | ||
768 | kn->dir.root = parent->dir.root; | |
769 | kn->ns = ns; | |
770 | kn->priv = priv; | |
771 | ||
772 | /* link in */ | |
773 | rc = kernfs_add_one(kn); | |
774 | if (!rc) | |
775 | return kn; | |
776 | ||
777 | kernfs_put(kn); | |
778 | return ERR_PTR(rc); | |
779 | } | |
780 | ||
781 | static struct dentry *kernfs_iop_lookup(struct inode *dir, | |
782 | struct dentry *dentry, | |
783 | unsigned int flags) | |
784 | { | |
785 | struct dentry *ret; | |
786 | struct kernfs_node *parent = dentry->d_parent->d_fsdata; | |
787 | struct kernfs_node *kn; | |
788 | struct inode *inode; | |
789 | const void *ns = NULL; | |
790 | ||
791 | mutex_lock(&kernfs_mutex); | |
792 | ||
793 | if (kernfs_ns_enabled(parent)) | |
794 | ns = kernfs_info(dir->i_sb)->ns; | |
795 | ||
796 | kn = kernfs_find_ns(parent, dentry->d_name.name, ns); | |
797 | ||
798 | /* no such entry */ | |
799 | if (!kn || !kernfs_active(kn)) { | |
800 | ret = NULL; | |
801 | goto out_unlock; | |
802 | } | |
803 | kernfs_get(kn); | |
804 | dentry->d_fsdata = kn; | |
805 | ||
806 | /* attach dentry and inode */ | |
807 | inode = kernfs_get_inode(dir->i_sb, kn); | |
808 | if (!inode) { | |
809 | ret = ERR_PTR(-ENOMEM); | |
810 | goto out_unlock; | |
811 | } | |
812 | ||
813 | /* instantiate and hash dentry */ | |
814 | ret = d_splice_alias(inode, dentry); | |
815 | out_unlock: | |
816 | mutex_unlock(&kernfs_mutex); | |
817 | return ret; | |
818 | } | |
819 | ||
820 | static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry, | |
821 | umode_t mode) | |
822 | { | |
823 | struct kernfs_node *parent = dir->i_private; | |
824 | struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops; | |
825 | int ret; | |
826 | ||
827 | if (!scops || !scops->mkdir) | |
828 | return -EPERM; | |
829 | ||
830 | if (!kernfs_get_active(parent)) | |
831 | return -ENODEV; | |
832 | ||
833 | ret = scops->mkdir(parent, dentry->d_name.name, mode); | |
834 | ||
835 | kernfs_put_active(parent); | |
836 | return ret; | |
837 | } | |
838 | ||
839 | static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) | |
840 | { | |
841 | struct kernfs_node *kn = dentry->d_fsdata; | |
842 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; | |
843 | int ret; | |
844 | ||
845 | if (!scops || !scops->rmdir) | |
846 | return -EPERM; | |
847 | ||
848 | if (!kernfs_get_active(kn)) | |
849 | return -ENODEV; | |
850 | ||
851 | ret = scops->rmdir(kn); | |
852 | ||
853 | kernfs_put_active(kn); | |
854 | return ret; | |
855 | } | |
856 | ||
857 | static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry, | |
858 | struct inode *new_dir, struct dentry *new_dentry) | |
859 | { | |
860 | struct kernfs_node *kn = old_dentry->d_fsdata; | |
861 | struct kernfs_node *new_parent = new_dir->i_private; | |
862 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; | |
863 | int ret; | |
864 | ||
865 | if (!scops || !scops->rename) | |
866 | return -EPERM; | |
867 | ||
868 | if (!kernfs_get_active(kn)) | |
869 | return -ENODEV; | |
870 | ||
871 | if (!kernfs_get_active(new_parent)) { | |
872 | kernfs_put_active(kn); | |
873 | return -ENODEV; | |
874 | } | |
875 | ||
876 | ret = scops->rename(kn, new_parent, new_dentry->d_name.name); | |
877 | ||
878 | kernfs_put_active(new_parent); | |
879 | kernfs_put_active(kn); | |
880 | return ret; | |
881 | } | |
882 | ||
883 | const struct inode_operations kernfs_dir_iops = { | |
884 | .lookup = kernfs_iop_lookup, | |
885 | .permission = kernfs_iop_permission, | |
886 | .setattr = kernfs_iop_setattr, | |
887 | .getattr = kernfs_iop_getattr, | |
888 | .setxattr = kernfs_iop_setxattr, | |
889 | .removexattr = kernfs_iop_removexattr, | |
890 | .getxattr = kernfs_iop_getxattr, | |
891 | .listxattr = kernfs_iop_listxattr, | |
892 | ||
893 | .mkdir = kernfs_iop_mkdir, | |
894 | .rmdir = kernfs_iop_rmdir, | |
895 | .rename = kernfs_iop_rename, | |
896 | }; | |
897 | ||
898 | static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos) | |
899 | { | |
900 | struct kernfs_node *last; | |
901 | ||
902 | while (true) { | |
903 | struct rb_node *rbn; | |
904 | ||
905 | last = pos; | |
906 | ||
907 | if (kernfs_type(pos) != KERNFS_DIR) | |
908 | break; | |
909 | ||
910 | rbn = rb_first(&pos->dir.children); | |
911 | if (!rbn) | |
912 | break; | |
913 | ||
914 | pos = rb_to_kn(rbn); | |
915 | } | |
916 | ||
917 | return last; | |
918 | } | |
919 | ||
920 | /** | |
921 | * kernfs_next_descendant_post - find the next descendant for post-order walk | |
922 | * @pos: the current position (%NULL to initiate traversal) | |
923 | * @root: kernfs_node whose descendants to walk | |
924 | * | |
925 | * Find the next descendant to visit for post-order traversal of @root's | |
926 | * descendants. @root is included in the iteration and the last node to be | |
927 | * visited. | |
928 | */ | |
929 | static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, | |
930 | struct kernfs_node *root) | |
931 | { | |
932 | struct rb_node *rbn; | |
933 | ||
934 | lockdep_assert_held(&kernfs_mutex); | |
935 | ||
936 | /* if first iteration, visit leftmost descendant which may be root */ | |
937 | if (!pos) | |
938 | return kernfs_leftmost_descendant(root); | |
939 | ||
940 | /* if we visited @root, we're done */ | |
941 | if (pos == root) | |
942 | return NULL; | |
943 | ||
944 | /* if there's an unvisited sibling, visit its leftmost descendant */ | |
945 | rbn = rb_next(&pos->rb); | |
946 | if (rbn) | |
947 | return kernfs_leftmost_descendant(rb_to_kn(rbn)); | |
948 | ||
949 | /* no sibling left, visit parent */ | |
950 | return pos->parent; | |
951 | } | |
952 | ||
953 | /** | |
954 | * kernfs_activate - activate a node which started deactivated | |
955 | * @kn: kernfs_node whose subtree is to be activated | |
956 | * | |
957 | * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node | |
958 | * needs to be explicitly activated. A node which hasn't been activated | |
959 | * isn't visible to userland and deactivation is skipped during its | |
960 | * removal. This is useful to construct atomic init sequences where | |
961 | * creation of multiple nodes should either succeed or fail atomically. | |
962 | * | |
963 | * The caller is responsible for ensuring that this function is not called | |
964 | * after kernfs_remove*() is invoked on @kn. | |
965 | */ | |
966 | void kernfs_activate(struct kernfs_node *kn) | |
967 | { | |
968 | struct kernfs_node *pos; | |
969 | ||
970 | mutex_lock(&kernfs_mutex); | |
971 | ||
972 | pos = NULL; | |
973 | while ((pos = kernfs_next_descendant_post(pos, kn))) { | |
974 | if (!pos || (pos->flags & KERNFS_ACTIVATED)) | |
975 | continue; | |
976 | ||
977 | WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb)); | |
978 | WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS); | |
979 | ||
980 | atomic_sub(KN_DEACTIVATED_BIAS, &pos->active); | |
981 | pos->flags |= KERNFS_ACTIVATED; | |
982 | } | |
983 | ||
984 | mutex_unlock(&kernfs_mutex); | |
985 | } | |
986 | ||
987 | static void __kernfs_remove(struct kernfs_node *kn) | |
988 | { | |
989 | struct kernfs_node *pos; | |
990 | ||
991 | lockdep_assert_held(&kernfs_mutex); | |
992 | ||
993 | /* | |
994 | * Short-circuit if non-root @kn has already finished removal. | |
995 | * This is for kernfs_remove_self() which plays with active ref | |
996 | * after removal. | |
997 | */ | |
998 | if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb))) | |
999 | return; | |
1000 | ||
1001 | pr_debug("kernfs %s: removing\n", kn->name); | |
1002 | ||
1003 | /* prevent any new usage under @kn by deactivating all nodes */ | |
1004 | pos = NULL; | |
1005 | while ((pos = kernfs_next_descendant_post(pos, kn))) | |
1006 | if (kernfs_active(pos)) | |
1007 | atomic_add(KN_DEACTIVATED_BIAS, &pos->active); | |
1008 | ||
1009 | /* deactivate and unlink the subtree node-by-node */ | |
1010 | do { | |
1011 | pos = kernfs_leftmost_descendant(kn); | |
1012 | ||
1013 | /* | |
1014 | * kernfs_drain() drops kernfs_mutex temporarily and @pos's | |
1015 | * base ref could have been put by someone else by the time | |
1016 | * the function returns. Make sure it doesn't go away | |
1017 | * underneath us. | |
1018 | */ | |
1019 | kernfs_get(pos); | |
1020 | ||
1021 | /* | |
1022 | * Drain iff @kn was activated. This avoids draining and | |
1023 | * its lockdep annotations for nodes which have never been | |
1024 | * activated and allows embedding kernfs_remove() in create | |
1025 | * error paths without worrying about draining. | |
1026 | */ | |
1027 | if (kn->flags & KERNFS_ACTIVATED) | |
1028 | kernfs_drain(pos); | |
1029 | else | |
1030 | WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); | |
1031 | ||
1032 | /* | |
1033 | * kernfs_unlink_sibling() succeeds once per node. Use it | |
1034 | * to decide who's responsible for cleanups. | |
1035 | */ | |
1036 | if (!pos->parent || kernfs_unlink_sibling(pos)) { | |
1037 | struct kernfs_iattrs *ps_iattr = | |
1038 | pos->parent ? pos->parent->iattr : NULL; | |
1039 | ||
1040 | /* update timestamps on the parent */ | |
1041 | if (ps_iattr) { | |
1042 | ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME; | |
1043 | ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME; | |
1044 | } | |
1045 | ||
1046 | kernfs_put(pos); | |
1047 | } | |
1048 | ||
1049 | kernfs_put(pos); | |
1050 | } while (pos != kn); | |
1051 | } | |
1052 | ||
1053 | /** | |
1054 | * kernfs_remove - remove a kernfs_node recursively | |
1055 | * @kn: the kernfs_node to remove | |
1056 | * | |
1057 | * Remove @kn along with all its subdirectories and files. | |
1058 | */ | |
1059 | void kernfs_remove(struct kernfs_node *kn) | |
1060 | { | |
1061 | mutex_lock(&kernfs_mutex); | |
1062 | __kernfs_remove(kn); | |
1063 | mutex_unlock(&kernfs_mutex); | |
1064 | } | |
1065 | ||
1066 | /** | |
1067 | * kernfs_break_active_protection - break out of active protection | |
1068 | * @kn: the self kernfs_node | |
1069 | * | |
1070 | * The caller must be running off of a kernfs operation which is invoked | |
1071 | * with an active reference - e.g. one of kernfs_ops. Each invocation of | |
1072 | * this function must also be matched with an invocation of | |
1073 | * kernfs_unbreak_active_protection(). | |
1074 | * | |
1075 | * This function releases the active reference of @kn the caller is | |
1076 | * holding. Once this function is called, @kn may be removed at any point | |
1077 | * and the caller is solely responsible for ensuring that the objects it | |
1078 | * dereferences are accessible. | |
1079 | */ | |
1080 | void kernfs_break_active_protection(struct kernfs_node *kn) | |
1081 | { | |
1082 | /* | |
1083 | * Take out ourself out of the active ref dependency chain. If | |
1084 | * we're called without an active ref, lockdep will complain. | |
1085 | */ | |
1086 | kernfs_put_active(kn); | |
1087 | } | |
1088 | ||
1089 | /** | |
1090 | * kernfs_unbreak_active_protection - undo kernfs_break_active_protection() | |
1091 | * @kn: the self kernfs_node | |
1092 | * | |
1093 | * If kernfs_break_active_protection() was called, this function must be | |
1094 | * invoked before finishing the kernfs operation. Note that while this | |
1095 | * function restores the active reference, it doesn't and can't actually | |
1096 | * restore the active protection - @kn may already or be in the process of | |
1097 | * being removed. Once kernfs_break_active_protection() is invoked, that | |
1098 | * protection is irreversibly gone for the kernfs operation instance. | |
1099 | * | |
1100 | * While this function may be called at any point after | |
1101 | * kernfs_break_active_protection() is invoked, its most useful location | |
1102 | * would be right before the enclosing kernfs operation returns. | |
1103 | */ | |
1104 | void kernfs_unbreak_active_protection(struct kernfs_node *kn) | |
1105 | { | |
1106 | /* | |
1107 | * @kn->active could be in any state; however, the increment we do | |
1108 | * here will be undone as soon as the enclosing kernfs operation | |
1109 | * finishes and this temporary bump can't break anything. If @kn | |
1110 | * is alive, nothing changes. If @kn is being deactivated, the | |
1111 | * soon-to-follow put will either finish deactivation or restore | |
1112 | * deactivated state. If @kn is already removed, the temporary | |
1113 | * bump is guaranteed to be gone before @kn is released. | |
1114 | */ | |
1115 | atomic_inc(&kn->active); | |
1116 | if (kernfs_lockdep(kn)) | |
1117 | rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_); | |
1118 | } | |
1119 | ||
1120 | /** | |
1121 | * kernfs_remove_self - remove a kernfs_node from its own method | |
1122 | * @kn: the self kernfs_node to remove | |
1123 | * | |
1124 | * The caller must be running off of a kernfs operation which is invoked | |
1125 | * with an active reference - e.g. one of kernfs_ops. This can be used to | |
1126 | * implement a file operation which deletes itself. | |
1127 | * | |
1128 | * For example, the "delete" file for a sysfs device directory can be | |
1129 | * implemented by invoking kernfs_remove_self() on the "delete" file | |
1130 | * itself. This function breaks the circular dependency of trying to | |
1131 | * deactivate self while holding an active ref itself. It isn't necessary | |
1132 | * to modify the usual removal path to use kernfs_remove_self(). The | |
1133 | * "delete" implementation can simply invoke kernfs_remove_self() on self | |
1134 | * before proceeding with the usual removal path. kernfs will ignore later | |
1135 | * kernfs_remove() on self. | |
1136 | * | |
1137 | * kernfs_remove_self() can be called multiple times concurrently on the | |
1138 | * same kernfs_node. Only the first one actually performs removal and | |
1139 | * returns %true. All others will wait until the kernfs operation which | |
1140 | * won self-removal finishes and return %false. Note that the losers wait | |
1141 | * for the completion of not only the winning kernfs_remove_self() but also | |
1142 | * the whole kernfs_ops which won the arbitration. This can be used to | |
1143 | * guarantee, for example, all concurrent writes to a "delete" file to | |
1144 | * finish only after the whole operation is complete. | |
1145 | */ | |
1146 | bool kernfs_remove_self(struct kernfs_node *kn) | |
1147 | { | |
1148 | bool ret; | |
1149 | ||
1150 | mutex_lock(&kernfs_mutex); | |
1151 | kernfs_break_active_protection(kn); | |
1152 | ||
1153 | /* | |
1154 | * SUICIDAL is used to arbitrate among competing invocations. Only | |
1155 | * the first one will actually perform removal. When the removal | |
1156 | * is complete, SUICIDED is set and the active ref is restored | |
1157 | * while holding kernfs_mutex. The ones which lost arbitration | |
1158 | * waits for SUICDED && drained which can happen only after the | |
1159 | * enclosing kernfs operation which executed the winning instance | |
1160 | * of kernfs_remove_self() finished. | |
1161 | */ | |
1162 | if (!(kn->flags & KERNFS_SUICIDAL)) { | |
1163 | kn->flags |= KERNFS_SUICIDAL; | |
1164 | __kernfs_remove(kn); | |
1165 | kn->flags |= KERNFS_SUICIDED; | |
1166 | ret = true; | |
1167 | } else { | |
1168 | wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq; | |
1169 | DEFINE_WAIT(wait); | |
1170 | ||
1171 | while (true) { | |
1172 | prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE); | |
1173 | ||
1174 | if ((kn->flags & KERNFS_SUICIDED) && | |
1175 | atomic_read(&kn->active) == KN_DEACTIVATED_BIAS) | |
1176 | break; | |
1177 | ||
1178 | mutex_unlock(&kernfs_mutex); | |
1179 | schedule(); | |
1180 | mutex_lock(&kernfs_mutex); | |
1181 | } | |
1182 | finish_wait(waitq, &wait); | |
1183 | WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb)); | |
1184 | ret = false; | |
1185 | } | |
1186 | ||
1187 | /* | |
1188 | * This must be done while holding kernfs_mutex; otherwise, waiting | |
1189 | * for SUICIDED && deactivated could finish prematurely. | |
1190 | */ | |
1191 | kernfs_unbreak_active_protection(kn); | |
1192 | ||
1193 | mutex_unlock(&kernfs_mutex); | |
1194 | return ret; | |
1195 | } | |
1196 | ||
1197 | /** | |
1198 | * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it | |
1199 | * @parent: parent of the target | |
1200 | * @name: name of the kernfs_node to remove | |
1201 | * @ns: namespace tag of the kernfs_node to remove | |
1202 | * | |
1203 | * Look for the kernfs_node with @name and @ns under @parent and remove it. | |
1204 | * Returns 0 on success, -ENOENT if such entry doesn't exist. | |
1205 | */ | |
1206 | int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, | |
1207 | const void *ns) | |
1208 | { | |
1209 | struct kernfs_node *kn; | |
1210 | ||
1211 | if (!parent) { | |
1212 | WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n", | |
1213 | name); | |
1214 | return -ENOENT; | |
1215 | } | |
1216 | ||
1217 | mutex_lock(&kernfs_mutex); | |
1218 | ||
1219 | kn = kernfs_find_ns(parent, name, ns); | |
1220 | if (kn) | |
1221 | __kernfs_remove(kn); | |
1222 | ||
1223 | mutex_unlock(&kernfs_mutex); | |
1224 | ||
1225 | if (kn) | |
1226 | return 0; | |
1227 | else | |
1228 | return -ENOENT; | |
1229 | } | |
1230 | ||
1231 | /** | |
1232 | * kernfs_rename_ns - move and rename a kernfs_node | |
1233 | * @kn: target node | |
1234 | * @new_parent: new parent to put @sd under | |
1235 | * @new_name: new name | |
1236 | * @new_ns: new namespace tag | |
1237 | */ | |
1238 | int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, | |
1239 | const char *new_name, const void *new_ns) | |
1240 | { | |
1241 | struct kernfs_node *old_parent; | |
1242 | const char *old_name = NULL; | |
1243 | int error; | |
1244 | ||
1245 | /* can't move or rename root */ | |
1246 | if (!kn->parent) | |
1247 | return -EINVAL; | |
1248 | ||
1249 | mutex_lock(&kernfs_mutex); | |
1250 | ||
1251 | error = -ENOENT; | |
1252 | if (!kernfs_active(kn) || !kernfs_active(new_parent)) | |
1253 | goto out; | |
1254 | ||
1255 | error = 0; | |
1256 | if ((kn->parent == new_parent) && (kn->ns == new_ns) && | |
1257 | (strcmp(kn->name, new_name) == 0)) | |
1258 | goto out; /* nothing to rename */ | |
1259 | ||
1260 | error = -EEXIST; | |
1261 | if (kernfs_find_ns(new_parent, new_name, new_ns)) | |
1262 | goto out; | |
1263 | ||
1264 | /* rename kernfs_node */ | |
1265 | if (strcmp(kn->name, new_name) != 0) { | |
1266 | error = -ENOMEM; | |
1267 | new_name = kstrdup(new_name, GFP_KERNEL); | |
1268 | if (!new_name) | |
1269 | goto out; | |
1270 | } else { | |
1271 | new_name = NULL; | |
1272 | } | |
1273 | ||
1274 | /* | |
1275 | * Move to the appropriate place in the appropriate directories rbtree. | |
1276 | */ | |
1277 | kernfs_unlink_sibling(kn); | |
1278 | kernfs_get(new_parent); | |
1279 | ||
1280 | /* rename_lock protects ->parent and ->name accessors */ | |
1281 | spin_lock_irq(&kernfs_rename_lock); | |
1282 | ||
1283 | old_parent = kn->parent; | |
1284 | kn->parent = new_parent; | |
1285 | ||
1286 | kn->ns = new_ns; | |
1287 | if (new_name) { | |
1288 | if (!(kn->flags & KERNFS_STATIC_NAME)) | |
1289 | old_name = kn->name; | |
1290 | kn->flags &= ~KERNFS_STATIC_NAME; | |
1291 | kn->name = new_name; | |
1292 | } | |
1293 | ||
1294 | spin_unlock_irq(&kernfs_rename_lock); | |
1295 | ||
1296 | kn->hash = kernfs_name_hash(kn->name, kn->ns); | |
1297 | kernfs_link_sibling(kn); | |
1298 | ||
1299 | kernfs_put(old_parent); | |
1300 | kfree(old_name); | |
1301 | ||
1302 | error = 0; | |
1303 | out: | |
1304 | mutex_unlock(&kernfs_mutex); | |
1305 | return error; | |
1306 | } | |
1307 | ||
1308 | /* Relationship between s_mode and the DT_xxx types */ | |
1309 | static inline unsigned char dt_type(struct kernfs_node *kn) | |
1310 | { | |
1311 | return (kn->mode >> 12) & 15; | |
1312 | } | |
1313 | ||
1314 | static int kernfs_dir_fop_release(struct inode *inode, struct file *filp) | |
1315 | { | |
1316 | kernfs_put(filp->private_data); | |
1317 | return 0; | |
1318 | } | |
1319 | ||
1320 | static struct kernfs_node *kernfs_dir_pos(const void *ns, | |
1321 | struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) | |
1322 | { | |
1323 | if (pos) { | |
1324 | int valid = kernfs_active(pos) && | |
1325 | pos->parent == parent && hash == pos->hash; | |
1326 | kernfs_put(pos); | |
1327 | if (!valid) | |
1328 | pos = NULL; | |
1329 | } | |
1330 | if (!pos && (hash > 1) && (hash < INT_MAX)) { | |
1331 | struct rb_node *node = parent->dir.children.rb_node; | |
1332 | while (node) { | |
1333 | pos = rb_to_kn(node); | |
1334 | ||
1335 | if (hash < pos->hash) | |
1336 | node = node->rb_left; | |
1337 | else if (hash > pos->hash) | |
1338 | node = node->rb_right; | |
1339 | else | |
1340 | break; | |
1341 | } | |
1342 | } | |
1343 | /* Skip over entries which are dying/dead or in the wrong namespace */ | |
1344 | while (pos && (!kernfs_active(pos) || pos->ns != ns)) { | |
1345 | struct rb_node *node = rb_next(&pos->rb); | |
1346 | if (!node) | |
1347 | pos = NULL; | |
1348 | else | |
1349 | pos = rb_to_kn(node); | |
1350 | } | |
1351 | return pos; | |
1352 | } | |
1353 | ||
1354 | static struct kernfs_node *kernfs_dir_next_pos(const void *ns, | |
1355 | struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos) | |
1356 | { | |
1357 | pos = kernfs_dir_pos(ns, parent, ino, pos); | |
1358 | if (pos) { | |
1359 | do { | |
1360 | struct rb_node *node = rb_next(&pos->rb); | |
1361 | if (!node) | |
1362 | pos = NULL; | |
1363 | else | |
1364 | pos = rb_to_kn(node); | |
1365 | } while (pos && (!kernfs_active(pos) || pos->ns != ns)); | |
1366 | } | |
1367 | return pos; | |
1368 | } | |
1369 | ||
1370 | static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) | |
1371 | { | |
1372 | struct dentry *dentry = file->f_path.dentry; | |
1373 | struct kernfs_node *parent = dentry->d_fsdata; | |
1374 | struct kernfs_node *pos = file->private_data; | |
1375 | const void *ns = NULL; | |
1376 | ||
1377 | if (!dir_emit_dots(file, ctx)) | |
1378 | return 0; | |
1379 | mutex_lock(&kernfs_mutex); | |
1380 | ||
1381 | if (kernfs_ns_enabled(parent)) | |
1382 | ns = kernfs_info(dentry->d_sb)->ns; | |
1383 | ||
1384 | for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos); | |
1385 | pos; | |
1386 | pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) { | |
1387 | const char *name = pos->name; | |
1388 | unsigned int type = dt_type(pos); | |
1389 | int len = strlen(name); | |
1390 | ino_t ino = pos->ino; | |
1391 | ||
1392 | ctx->pos = pos->hash; | |
1393 | file->private_data = pos; | |
1394 | kernfs_get(pos); | |
1395 | ||
1396 | mutex_unlock(&kernfs_mutex); | |
1397 | if (!dir_emit(ctx, name, len, ino, type)) | |
1398 | return 0; | |
1399 | mutex_lock(&kernfs_mutex); | |
1400 | } | |
1401 | mutex_unlock(&kernfs_mutex); | |
1402 | file->private_data = NULL; | |
1403 | ctx->pos = INT_MAX; | |
1404 | return 0; | |
1405 | } | |
1406 | ||
1407 | static loff_t kernfs_dir_fop_llseek(struct file *file, loff_t offset, | |
1408 | int whence) | |
1409 | { | |
1410 | struct inode *inode = file_inode(file); | |
1411 | loff_t ret; | |
1412 | ||
1413 | mutex_lock(&inode->i_mutex); | |
1414 | ret = generic_file_llseek(file, offset, whence); | |
1415 | mutex_unlock(&inode->i_mutex); | |
1416 | ||
1417 | return ret; | |
1418 | } | |
1419 | ||
1420 | const struct file_operations kernfs_dir_fops = { | |
1421 | .read = generic_read_dir, | |
1422 | .iterate = kernfs_fop_readdir, | |
1423 | .release = kernfs_dir_fop_release, | |
1424 | .llseek = kernfs_dir_fop_llseek, | |
1425 | }; |