1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * fs/kernfs/dir.c - kernfs directory implementation |
4 | * |
5 | * Copyright (c) 2001-3 Patrick Mochel |
6 | * Copyright (c) 2007 SUSE Linux Products GmbH |
7 | * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> |
8 | */ |
9 | |
10 | #include <linux/sched.h> |
11 | #include <linux/fs.h> |
12 | #include <linux/namei.h> |
13 | #include <linux/idr.h> |
14 | #include <linux/slab.h> |
15 | #include <linux/security.h> |
16 | #include <linux/hash.h> |
17 | |
18 | #include "kernfs-internal.h" |
19 | |
20 | static DEFINE_RWLOCK(kernfs_rename_lock); /* kn->parent and ->name */ |
21 | /* |
22 | * Don't use rename_lock to piggy back on pr_cont_buf. We don't want to |
23 | * call pr_cont() while holding rename_lock. Because sometimes pr_cont() |
24 | * will perform wakeups when releasing console_sem. Holding rename_lock |
25 | * will introduce deadlock if the scheduler reads the kernfs_name in the |
26 | * wakeup path. |
27 | */ |
28 | static DEFINE_SPINLOCK(kernfs_pr_cont_lock); |
29 | static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by pr_cont_lock */ |
30 | static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ |
31 | |
32 | #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) |
33 | |
34 | static bool __kernfs_active(struct kernfs_node *kn) |
35 | { |
36 | return atomic_read(v: &kn->active) >= 0; |
37 | } |
38 | |
39 | static bool kernfs_active(struct kernfs_node *kn) |
40 | { |
41 | lockdep_assert_held(&kernfs_root(kn)->kernfs_rwsem); |
42 | return __kernfs_active(kn); |
43 | } |
44 | |
45 | static bool kernfs_lockdep(struct kernfs_node *kn) |
46 | { |
47 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
48 | return kn->flags & KERNFS_LOCKDEP; |
49 | #else |
50 | return false; |
51 | #endif |
52 | } |
53 | |
54 | static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) |
55 | { |
56 | if (!kn) |
57 | return strscpy(buf, "(null)" , buflen); |
58 | |
59 | return strscpy(buf, kn->parent ? kn->name : "/" , buflen); |
60 | } |
61 | |
62 | /* kernfs_node_depth - compute depth from @from to @to */ |
63 | static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to) |
64 | { |
65 | size_t depth = 0; |
66 | |
67 | while (to->parent && to != from) { |
68 | depth++; |
69 | to = to->parent; |
70 | } |
71 | return depth; |
72 | } |
73 | |
74 | static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a, |
75 | struct kernfs_node *b) |
76 | { |
77 | size_t da, db; |
78 | struct kernfs_root *ra = kernfs_root(kn: a), *rb = kernfs_root(kn: b); |
79 | |
80 | if (ra != rb) |
81 | return NULL; |
82 | |
83 | da = kernfs_depth(from: ra->kn, to: a); |
84 | db = kernfs_depth(from: rb->kn, to: b); |
85 | |
86 | while (da > db) { |
87 | a = a->parent; |
88 | da--; |
89 | } |
90 | while (db > da) { |
91 | b = b->parent; |
92 | db--; |
93 | } |
94 | |
95 | /* worst case b and a will be the same at root */ |
96 | while (b != a) { |
97 | b = b->parent; |
98 | a = a->parent; |
99 | } |
100 | |
101 | return a; |
102 | } |
103 | |
104 | /** |
105 | * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to, |
106 | * where kn_from is treated as root of the path. |
107 | * @kn_from: kernfs node which should be treated as root for the path |
108 | * @kn_to: kernfs node to which path is needed |
109 | * @buf: buffer to copy the path into |
110 | * @buflen: size of @buf |
111 | * |
112 | * We need to handle couple of scenarios here: |
113 | * [1] when @kn_from is an ancestor of @kn_to at some level |
114 | * kn_from: /n1/n2/n3 |
115 | * kn_to: /n1/n2/n3/n4/n5 |
116 | * result: /n4/n5 |
117 | * |
118 | * [2] when @kn_from is on a different hierarchy and we need to find common |
119 | * ancestor between @kn_from and @kn_to. |
120 | * kn_from: /n1/n2/n3/n4 |
121 | * kn_to: /n1/n2/n5 |
122 | * result: /../../n5 |
123 | * OR |
124 | * kn_from: /n1/n2/n3/n4/n5 [depth=5] |
125 | * kn_to: /n1/n2/n3 [depth=3] |
126 | * result: /../.. |
127 | * |
128 | * [3] when @kn_to is %NULL result will be "(null)" |
129 | * |
130 | * Return: the length of the constructed path. If the path would have been |
131 | * greater than @buflen, @buf contains the truncated path with the trailing |
132 | * '\0'. On error, -errno is returned. |
133 | */ |
134 | static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, |
135 | struct kernfs_node *kn_from, |
136 | char *buf, size_t buflen) |
137 | { |
138 | struct kernfs_node *kn, *common; |
139 | const char parent_str[] = "/.." ; |
140 | size_t depth_from, depth_to, len = 0; |
141 | ssize_t copied; |
142 | int i, j; |
143 | |
144 | if (!kn_to) |
145 | return strscpy(buf, "(null)" , buflen); |
146 | |
147 | if (!kn_from) |
148 | kn_from = kernfs_root(kn: kn_to)->kn; |
149 | |
150 | if (kn_from == kn_to) |
151 | return strscpy(buf, "/" , buflen); |
152 | |
153 | common = kernfs_common_ancestor(a: kn_from, b: kn_to); |
154 | if (WARN_ON(!common)) |
155 | return -EINVAL; |
156 | |
157 | depth_to = kernfs_depth(from: common, to: kn_to); |
158 | depth_from = kernfs_depth(from: common, to: kn_from); |
159 | |
160 | buf[0] = '\0'; |
161 | |
162 | for (i = 0; i < depth_from; i++) { |
163 | copied = strscpy(buf + len, parent_str, buflen - len); |
164 | if (copied < 0) |
165 | return copied; |
166 | len += copied; |
167 | } |
168 | |
169 | /* Calculate how many bytes we need for the rest */ |
170 | for (i = depth_to - 1; i >= 0; i--) { |
171 | for (kn = kn_to, j = 0; j < i; j++) |
172 | kn = kn->parent; |
173 | |
174 | len += scnprintf(buf: buf + len, size: buflen - len, fmt: "/%s" , kn->name); |
175 | } |
176 | |
177 | return len; |
178 | } |
179 | |
180 | /** |
181 | * kernfs_name - obtain the name of a given node |
182 | * @kn: kernfs_node of interest |
183 | * @buf: buffer to copy @kn's name into |
184 | * @buflen: size of @buf |
185 | * |
186 | * Copies the name of @kn into @buf of @buflen bytes. The behavior is |
187 | * similar to strscpy(). |
188 | * |
189 | * Fills buffer with "(null)" if @kn is %NULL. |
190 | * |
191 | * Return: the resulting length of @buf. If @buf isn't long enough, |
192 | * it's filled up to @buflen-1 and nul terminated, and returns -E2BIG. |
193 | * |
194 | * This function can be called from any context. |
195 | */ |
196 | int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) |
197 | { |
198 | unsigned long flags; |
199 | int ret; |
200 | |
201 | read_lock_irqsave(&kernfs_rename_lock, flags); |
202 | ret = kernfs_name_locked(kn, buf, buflen); |
203 | read_unlock_irqrestore(&kernfs_rename_lock, flags); |
204 | return ret; |
205 | } |
206 | |
207 | /** |
208 | * kernfs_path_from_node - build path of node @to relative to @from. |
209 | * @from: parent kernfs_node relative to which we need to build the path |
210 | * @to: kernfs_node of interest |
211 | * @buf: buffer to copy @to's path into |
212 | * @buflen: size of @buf |
213 | * |
214 | * Builds @to's path relative to @from in @buf. @from and @to must |
215 | * be on the same kernfs-root. If @from is not parent of @to, then a relative |
216 | * path (which includes '..'s) as needed to reach from @from to @to is |
217 | * returned. |
218 | * |
219 | * Return: the length of the constructed path. If the path would have been |
220 | * greater than @buflen, @buf contains the truncated path with the trailing |
221 | * '\0'. On error, -errno is returned. |
222 | */ |
223 | int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from, |
224 | char *buf, size_t buflen) |
225 | { |
226 | unsigned long flags; |
227 | int ret; |
228 | |
229 | read_lock_irqsave(&kernfs_rename_lock, flags); |
230 | ret = kernfs_path_from_node_locked(kn_to: to, kn_from: from, buf, buflen); |
231 | read_unlock_irqrestore(&kernfs_rename_lock, flags); |
232 | return ret; |
233 | } |
234 | EXPORT_SYMBOL_GPL(kernfs_path_from_node); |
235 | |
236 | /** |
237 | * pr_cont_kernfs_name - pr_cont name of a kernfs_node |
238 | * @kn: kernfs_node of interest |
239 | * |
240 | * This function can be called from any context. |
241 | */ |
242 | void pr_cont_kernfs_name(struct kernfs_node *kn) |
243 | { |
244 | unsigned long flags; |
245 | |
246 | spin_lock_irqsave(&kernfs_pr_cont_lock, flags); |
247 | |
248 | kernfs_name(kn, buf: kernfs_pr_cont_buf, buflen: sizeof(kernfs_pr_cont_buf)); |
249 | pr_cont("%s" , kernfs_pr_cont_buf); |
250 | |
251 | spin_unlock_irqrestore(lock: &kernfs_pr_cont_lock, flags); |
252 | } |
253 | |
254 | /** |
255 | * pr_cont_kernfs_path - pr_cont path of a kernfs_node |
256 | * @kn: kernfs_node of interest |
257 | * |
258 | * This function can be called from any context. |
259 | */ |
260 | void pr_cont_kernfs_path(struct kernfs_node *kn) |
261 | { |
262 | unsigned long flags; |
263 | int sz; |
264 | |
265 | spin_lock_irqsave(&kernfs_pr_cont_lock, flags); |
266 | |
267 | sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf, |
268 | sizeof(kernfs_pr_cont_buf)); |
269 | if (sz < 0) { |
270 | if (sz == -E2BIG) |
271 | pr_cont("(name too long)" ); |
272 | else |
273 | pr_cont("(error)" ); |
274 | goto out; |
275 | } |
276 | |
277 | pr_cont("%s" , kernfs_pr_cont_buf); |
278 | |
279 | out: |
280 | spin_unlock_irqrestore(lock: &kernfs_pr_cont_lock, flags); |
281 | } |
282 | |
283 | /** |
284 | * kernfs_get_parent - determine the parent node and pin it |
285 | * @kn: kernfs_node of interest |
286 | * |
287 | * Determines @kn's parent, pins and returns it. This function can be |
288 | * called from any context. |
289 | * |
290 | * Return: parent node of @kn |
291 | */ |
292 | struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) |
293 | { |
294 | struct kernfs_node *parent; |
295 | unsigned long flags; |
296 | |
297 | read_lock_irqsave(&kernfs_rename_lock, flags); |
298 | parent = kn->parent; |
299 | kernfs_get(kn: parent); |
300 | read_unlock_irqrestore(&kernfs_rename_lock, flags); |
301 | |
302 | return parent; |
303 | } |
304 | |
305 | /** |
306 | * kernfs_name_hash - calculate hash of @ns + @name |
307 | * @name: Null terminated string to hash |
308 | * @ns: Namespace tag to hash |
309 | * |
310 | * Return: 31-bit hash of ns + name (so it fits in an off_t) |
311 | */ |
312 | static unsigned int kernfs_name_hash(const char *name, const void *ns) |
313 | { |
314 | unsigned long hash = init_name_hash(ns); |
315 | unsigned int len = strlen(name); |
316 | while (len--) |
317 | hash = partial_name_hash(c: *name++, prevhash: hash); |
318 | hash = end_name_hash(hash); |
319 | hash &= 0x7fffffffU; |
320 | /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ |
321 | if (hash < 2) |
322 | hash += 2; |
323 | if (hash >= INT_MAX) |
324 | hash = INT_MAX - 1; |
325 | return hash; |
326 | } |
327 | |
328 | static int kernfs_name_compare(unsigned int hash, const char *name, |
329 | const void *ns, const struct kernfs_node *kn) |
330 | { |
331 | if (hash < kn->hash) |
332 | return -1; |
333 | if (hash > kn->hash) |
334 | return 1; |
335 | if (ns < kn->ns) |
336 | return -1; |
337 | if (ns > kn->ns) |
338 | return 1; |
339 | return strcmp(name, kn->name); |
340 | } |
341 | |
342 | static int kernfs_sd_compare(const struct kernfs_node *left, |
343 | const struct kernfs_node *right) |
344 | { |
345 | return kernfs_name_compare(hash: left->hash, name: left->name, ns: left->ns, kn: right); |
346 | } |
347 | |
348 | /** |
349 | * kernfs_link_sibling - link kernfs_node into sibling rbtree |
350 | * @kn: kernfs_node of interest |
351 | * |
352 | * Link @kn into its sibling rbtree which starts from |
353 | * @kn->parent->dir.children. |
354 | * |
355 | * Locking: |
356 | * kernfs_rwsem held exclusive |
357 | * |
358 | * Return: |
359 | * %0 on success, -EEXIST on failure. |
360 | */ |
361 | static int kernfs_link_sibling(struct kernfs_node *kn) |
362 | { |
363 | struct rb_node **node = &kn->parent->dir.children.rb_node; |
364 | struct rb_node *parent = NULL; |
365 | |
366 | while (*node) { |
367 | struct kernfs_node *pos; |
368 | int result; |
369 | |
370 | pos = rb_to_kn(*node); |
371 | parent = *node; |
372 | result = kernfs_sd_compare(left: kn, right: pos); |
373 | if (result < 0) |
374 | node = &pos->rb.rb_left; |
375 | else if (result > 0) |
376 | node = &pos->rb.rb_right; |
377 | else |
378 | return -EEXIST; |
379 | } |
380 | |
381 | /* add new node and rebalance the tree */ |
382 | rb_link_node(node: &kn->rb, parent, rb_link: node); |
383 | rb_insert_color(&kn->rb, &kn->parent->dir.children); |
384 | |
385 | /* successfully added, account subdir number */ |
386 | down_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
387 | if (kernfs_type(kn) == KERNFS_DIR) |
388 | kn->parent->dir.subdirs++; |
389 | kernfs_inc_rev(parent: kn->parent); |
390 | up_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
391 | |
392 | return 0; |
393 | } |
394 | |
395 | /** |
396 | * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree |
397 | * @kn: kernfs_node of interest |
398 | * |
399 | * Try to unlink @kn from its sibling rbtree which starts from |
400 | * kn->parent->dir.children. |
401 | * |
402 | * Return: %true if @kn was actually removed, |
403 | * %false if @kn wasn't on the rbtree. |
404 | * |
405 | * Locking: |
406 | * kernfs_rwsem held exclusive |
407 | */ |
408 | static bool kernfs_unlink_sibling(struct kernfs_node *kn) |
409 | { |
410 | if (RB_EMPTY_NODE(&kn->rb)) |
411 | return false; |
412 | |
413 | down_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
414 | if (kernfs_type(kn) == KERNFS_DIR) |
415 | kn->parent->dir.subdirs--; |
416 | kernfs_inc_rev(parent: kn->parent); |
417 | up_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
418 | |
419 | rb_erase(&kn->rb, &kn->parent->dir.children); |
420 | RB_CLEAR_NODE(&kn->rb); |
421 | return true; |
422 | } |
423 | |
424 | /** |
425 | * kernfs_get_active - get an active reference to kernfs_node |
426 | * @kn: kernfs_node to get an active reference to |
427 | * |
428 | * Get an active reference of @kn. This function is noop if @kn |
429 | * is %NULL. |
430 | * |
431 | * Return: |
432 | * Pointer to @kn on success, %NULL on failure. |
433 | */ |
434 | struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) |
435 | { |
436 | if (unlikely(!kn)) |
437 | return NULL; |
438 | |
439 | if (!atomic_inc_unless_negative(v: &kn->active)) |
440 | return NULL; |
441 | |
442 | if (kernfs_lockdep(kn)) |
443 | rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); |
444 | return kn; |
445 | } |
446 | |
447 | /** |
448 | * kernfs_put_active - put an active reference to kernfs_node |
449 | * @kn: kernfs_node to put an active reference to |
450 | * |
451 | * Put an active reference to @kn. This function is noop if @kn |
452 | * is %NULL. |
453 | */ |
454 | void kernfs_put_active(struct kernfs_node *kn) |
455 | { |
456 | int v; |
457 | |
458 | if (unlikely(!kn)) |
459 | return; |
460 | |
461 | if (kernfs_lockdep(kn)) |
462 | rwsem_release(&kn->dep_map, _RET_IP_); |
463 | v = atomic_dec_return(v: &kn->active); |
464 | if (likely(v != KN_DEACTIVATED_BIAS)) |
465 | return; |
466 | |
467 | wake_up_all(&kernfs_root(kn)->deactivate_waitq); |
468 | } |
469 | |
470 | /** |
471 | * kernfs_drain - drain kernfs_node |
472 | * @kn: kernfs_node to drain |
473 | * |
474 | * Drain existing usages and nuke all existing mmaps of @kn. Multiple |
475 | * removers may invoke this function concurrently on @kn and all will |
476 | * return after draining is complete. |
477 | */ |
478 | static void kernfs_drain(struct kernfs_node *kn) |
479 | __releases(&kernfs_root(kn)->kernfs_rwsem) |
480 | __acquires(&kernfs_root(kn)->kernfs_rwsem) |
481 | { |
482 | struct kernfs_root *root = kernfs_root(kn); |
483 | |
484 | lockdep_assert_held_write(&root->kernfs_rwsem); |
485 | WARN_ON_ONCE(kernfs_active(kn)); |
486 | |
487 | /* |
488 | * Skip draining if already fully drained. This avoids draining and its |
489 | * lockdep annotations for nodes which have never been activated |
490 | * allowing embedding kernfs_remove() in create error paths without |
491 | * worrying about draining. |
492 | */ |
493 | if (atomic_read(v: &kn->active) == KN_DEACTIVATED_BIAS && |
494 | !kernfs_should_drain_open_files(kn)) |
495 | return; |
496 | |
497 | up_write(sem: &root->kernfs_rwsem); |
498 | |
499 | if (kernfs_lockdep(kn)) { |
500 | rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); |
501 | if (atomic_read(v: &kn->active) != KN_DEACTIVATED_BIAS) |
502 | lock_contended(lock: &kn->dep_map, _RET_IP_); |
503 | } |
504 | |
505 | wait_event(root->deactivate_waitq, |
506 | atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); |
507 | |
508 | if (kernfs_lockdep(kn)) { |
509 | lock_acquired(lock: &kn->dep_map, _RET_IP_); |
510 | rwsem_release(&kn->dep_map, _RET_IP_); |
511 | } |
512 | |
513 | if (kernfs_should_drain_open_files(kn)) |
514 | kernfs_drain_open_files(kn); |
515 | |
516 | down_write(sem: &root->kernfs_rwsem); |
517 | } |
518 | |
519 | /** |
520 | * kernfs_get - get a reference count on a kernfs_node |
521 | * @kn: the target kernfs_node |
522 | */ |
523 | void kernfs_get(struct kernfs_node *kn) |
524 | { |
525 | if (kn) { |
526 | WARN_ON(!atomic_read(&kn->count)); |
527 | atomic_inc(v: &kn->count); |
528 | } |
529 | } |
530 | EXPORT_SYMBOL_GPL(kernfs_get); |
531 | |
532 | static void kernfs_free_rcu(struct rcu_head *rcu) |
533 | { |
534 | struct kernfs_node *kn = container_of(rcu, struct kernfs_node, rcu); |
535 | |
536 | kfree_const(x: kn->name); |
537 | |
538 | if (kn->iattr) { |
539 | simple_xattrs_free(xattrs: &kn->iattr->xattrs, NULL); |
540 | kmem_cache_free(s: kernfs_iattrs_cache, objp: kn->iattr); |
541 | } |
542 | |
543 | kmem_cache_free(s: kernfs_node_cache, objp: kn); |
544 | } |
545 | |
546 | /** |
547 | * kernfs_put - put a reference count on a kernfs_node |
548 | * @kn: the target kernfs_node |
549 | * |
550 | * Put a reference count of @kn and destroy it if it reached zero. |
551 | */ |
552 | void kernfs_put(struct kernfs_node *kn) |
553 | { |
554 | struct kernfs_node *parent; |
555 | struct kernfs_root *root; |
556 | |
557 | if (!kn || !atomic_dec_and_test(v: &kn->count)) |
558 | return; |
559 | root = kernfs_root(kn); |
560 | repeat: |
561 | /* |
562 | * Moving/renaming is always done while holding reference. |
563 | * kn->parent won't change beneath us. |
564 | */ |
565 | parent = kn->parent; |
566 | |
567 | WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS, |
568 | "kernfs_put: %s/%s: released with incorrect active_ref %d\n" , |
569 | parent ? parent->name : "" , kn->name, atomic_read(&kn->active)); |
570 | |
571 | if (kernfs_type(kn) == KERNFS_LINK) |
572 | kernfs_put(kn: kn->symlink.target_kn); |
573 | |
574 | spin_lock(lock: &kernfs_idr_lock); |
575 | idr_remove(&root->ino_idr, id: (u32)kernfs_ino(kn)); |
576 | spin_unlock(lock: &kernfs_idr_lock); |
577 | |
578 | call_rcu(head: &kn->rcu, func: kernfs_free_rcu); |
579 | |
580 | kn = parent; |
581 | if (kn) { |
582 | if (atomic_dec_and_test(v: &kn->count)) |
583 | goto repeat; |
584 | } else { |
585 | /* just released the root kn, free @root too */ |
586 | idr_destroy(&root->ino_idr); |
587 | kfree_rcu(root, rcu); |
588 | } |
589 | } |
590 | EXPORT_SYMBOL_GPL(kernfs_put); |
591 | |
592 | /** |
593 | * kernfs_node_from_dentry - determine kernfs_node associated with a dentry |
594 | * @dentry: the dentry in question |
595 | * |
596 | * Return: the kernfs_node associated with @dentry. If @dentry is not a |
597 | * kernfs one, %NULL is returned. |
598 | * |
599 | * While the returned kernfs_node will stay accessible as long as @dentry |
600 | * is accessible, the returned node can be in any state and the caller is |
601 | * fully responsible for determining what's accessible. |
602 | */ |
603 | struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) |
604 | { |
605 | if (dentry->d_sb->s_op == &kernfs_sops) |
606 | return kernfs_dentry_node(dentry); |
607 | return NULL; |
608 | } |
609 | |
610 | static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, |
611 | struct kernfs_node *parent, |
612 | const char *name, umode_t mode, |
613 | kuid_t uid, kgid_t gid, |
614 | unsigned flags) |
615 | { |
616 | struct kernfs_node *kn; |
617 | u32 id_highbits; |
618 | int ret; |
619 | |
620 | name = kstrdup_const(s: name, GFP_KERNEL); |
621 | if (!name) |
622 | return NULL; |
623 | |
624 | kn = kmem_cache_zalloc(k: kernfs_node_cache, GFP_KERNEL); |
625 | if (!kn) |
626 | goto err_out1; |
627 | |
628 | idr_preload(GFP_KERNEL); |
629 | spin_lock(lock: &kernfs_idr_lock); |
630 | ret = idr_alloc_cyclic(&root->ino_idr, ptr: kn, start: 1, end: 0, GFP_ATOMIC); |
631 | if (ret >= 0 && ret < root->last_id_lowbits) |
632 | root->id_highbits++; |
633 | id_highbits = root->id_highbits; |
634 | root->last_id_lowbits = ret; |
635 | spin_unlock(lock: &kernfs_idr_lock); |
636 | idr_preload_end(); |
637 | if (ret < 0) |
638 | goto err_out2; |
639 | |
640 | kn->id = (u64)id_highbits << 32 | ret; |
641 | |
642 | atomic_set(v: &kn->count, i: 1); |
643 | atomic_set(v: &kn->active, KN_DEACTIVATED_BIAS); |
644 | RB_CLEAR_NODE(&kn->rb); |
645 | |
646 | kn->name = name; |
647 | kn->mode = mode; |
648 | kn->flags = flags; |
649 | |
650 | if (!uid_eq(left: uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) { |
651 | struct iattr iattr = { |
652 | .ia_valid = ATTR_UID | ATTR_GID, |
653 | .ia_uid = uid, |
654 | .ia_gid = gid, |
655 | }; |
656 | |
657 | ret = __kernfs_setattr(kn, &iattr); |
658 | if (ret < 0) |
659 | goto err_out3; |
660 | } |
661 | |
662 | if (parent) { |
663 | ret = security_kernfs_init_security(parent, kn); |
664 | if (ret) |
665 | goto err_out3; |
666 | } |
667 | |
668 | return kn; |
669 | |
670 | err_out3: |
671 | spin_lock(&kernfs_idr_lock); |
672 | idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
673 | spin_unlock(&kernfs_idr_lock); |
674 | err_out2: |
675 | kmem_cache_free(kernfs_node_cache, kn); |
676 | err_out1: |
677 | kfree_const(name); |
678 | return NULL; |
679 | } |
680 | |
681 | struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, |
682 | const char *name, umode_t mode, |
683 | kuid_t uid, kgid_t gid, |
684 | unsigned flags) |
685 | { |
686 | struct kernfs_node *kn; |
687 | |
688 | if (parent->mode & S_ISGID) { |
689 | /* this code block imitates inode_init_owner() for |
690 | * kernfs |
691 | */ |
692 | |
693 | if (parent->iattr) |
694 | gid = parent->iattr->ia_gid; |
695 | |
696 | if (flags & KERNFS_DIR) |
697 | mode |= S_ISGID; |
698 | } |
699 | |
700 | kn = __kernfs_new_node(root: kernfs_root(kn: parent), parent, |
701 | name, mode, uid, gid, flags); |
702 | if (kn) { |
703 | kernfs_get(parent); |
704 | kn->parent = parent; |
705 | } |
706 | return kn; |
707 | } |
708 | |
709 | /* |
710 | * kernfs_find_and_get_node_by_id - get kernfs_node from node id |
711 | * @root: the kernfs root |
712 | * @id: the target node id |
713 | * |
714 | * @id's lower 32bits encode ino and upper gen. If the gen portion is |
715 | * zero, all generations are matched. |
716 | * |
717 | * Return: %NULL on failure, |
718 | * otherwise a kernfs node with reference counter incremented. |
719 | */ |
720 | struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, |
721 | u64 id) |
722 | { |
723 | struct kernfs_node *kn; |
724 | ino_t ino = kernfs_id_ino(id); |
725 | u32 gen = kernfs_id_gen(id); |
726 | |
727 | rcu_read_lock(); |
728 | |
729 | kn = idr_find(&root->ino_idr, id: (u32)ino); |
730 | if (!kn) |
731 | goto err_unlock; |
732 | |
733 | if (sizeof(ino_t) >= sizeof(u64)) { |
734 | /* we looked up with the low 32bits, compare the whole */ |
735 | if (kernfs_ino(kn) != ino) |
736 | goto err_unlock; |
737 | } else { |
738 | /* 0 matches all generations */ |
739 | if (unlikely(gen && kernfs_gen(kn) != gen)) |
740 | goto err_unlock; |
741 | } |
742 | |
743 | /* |
744 | * We should fail if @kn has never been activated and guarantee success |
745 | * if the caller knows that @kn is active. Both can be achieved by |
746 | * __kernfs_active() which tests @kn->active without kernfs_rwsem. |
747 | */ |
748 | if (unlikely(!__kernfs_active(kn) || !atomic_inc_not_zero(&kn->count))) |
749 | goto err_unlock; |
750 | |
751 | rcu_read_unlock(); |
752 | return kn; |
753 | err_unlock: |
754 | rcu_read_unlock(); |
755 | return NULL; |
756 | } |
757 | |
758 | /** |
759 | * kernfs_add_one - add kernfs_node to parent without warning |
760 | * @kn: kernfs_node to be added |
761 | * |
762 | * The caller must already have initialized @kn->parent. This |
763 | * function increments nlink of the parent's inode if @kn is a |
764 | * directory and link into the children list of the parent. |
765 | * |
766 | * Return: |
767 | * %0 on success, -EEXIST if entry with the given name already |
768 | * exists. |
769 | */ |
770 | int kernfs_add_one(struct kernfs_node *kn) |
771 | { |
772 | struct kernfs_node *parent = kn->parent; |
773 | struct kernfs_root *root = kernfs_root(kn: parent); |
774 | struct kernfs_iattrs *ps_iattr; |
775 | bool has_ns; |
776 | int ret; |
777 | |
778 | down_write(sem: &root->kernfs_rwsem); |
779 | |
780 | ret = -EINVAL; |
781 | has_ns = kernfs_ns_enabled(kn: parent); |
782 | if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n" , |
783 | has_ns ? "required" : "invalid" , parent->name, kn->name)) |
784 | goto out_unlock; |
785 | |
786 | if (kernfs_type(kn: parent) != KERNFS_DIR) |
787 | goto out_unlock; |
788 | |
789 | ret = -ENOENT; |
790 | if (parent->flags & (KERNFS_REMOVING | KERNFS_EMPTY_DIR)) |
791 | goto out_unlock; |
792 | |
793 | kn->hash = kernfs_name_hash(name: kn->name, ns: kn->ns); |
794 | |
795 | ret = kernfs_link_sibling(kn); |
796 | if (ret) |
797 | goto out_unlock; |
798 | |
799 | /* Update timestamps on the parent */ |
800 | down_write(sem: &root->kernfs_iattr_rwsem); |
801 | |
802 | ps_iattr = parent->iattr; |
803 | if (ps_iattr) { |
804 | ktime_get_real_ts64(tv: &ps_iattr->ia_ctime); |
805 | ps_iattr->ia_mtime = ps_iattr->ia_ctime; |
806 | } |
807 | |
808 | up_write(sem: &root->kernfs_iattr_rwsem); |
809 | up_write(sem: &root->kernfs_rwsem); |
810 | |
811 | /* |
812 | * Activate the new node unless CREATE_DEACTIVATED is requested. |
813 | * If not activated here, the kernfs user is responsible for |
814 | * activating the node with kernfs_activate(). A node which hasn't |
815 | * been activated is not visible to userland and its removal won't |
816 | * trigger deactivation. |
817 | */ |
818 | if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
819 | kernfs_activate(kn); |
820 | return 0; |
821 | |
822 | out_unlock: |
823 | up_write(sem: &root->kernfs_rwsem); |
824 | return ret; |
825 | } |
826 | |
827 | /** |
828 | * kernfs_find_ns - find kernfs_node with the given name |
829 | * @parent: kernfs_node to search under |
830 | * @name: name to look for |
831 | * @ns: the namespace tag to use |
832 | * |
833 | * Look for kernfs_node with name @name under @parent. |
834 | * |
835 | * Return: pointer to the found kernfs_node on success, %NULL on failure. |
836 | */ |
837 | static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, |
838 | const unsigned char *name, |
839 | const void *ns) |
840 | { |
841 | struct rb_node *node = parent->dir.children.rb_node; |
842 | bool has_ns = kernfs_ns_enabled(kn: parent); |
843 | unsigned int hash; |
844 | |
845 | lockdep_assert_held(&kernfs_root(parent)->kernfs_rwsem); |
846 | |
847 | if (has_ns != (bool)ns) { |
848 | WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n" , |
849 | has_ns ? "required" : "invalid" , parent->name, name); |
850 | return NULL; |
851 | } |
852 | |
853 | hash = kernfs_name_hash(name, ns); |
854 | while (node) { |
855 | struct kernfs_node *kn; |
856 | int result; |
857 | |
858 | kn = rb_to_kn(node); |
859 | result = kernfs_name_compare(hash, name, ns, kn); |
860 | if (result < 0) |
861 | node = node->rb_left; |
862 | else if (result > 0) |
863 | node = node->rb_right; |
864 | else |
865 | return kn; |
866 | } |
867 | return NULL; |
868 | } |
869 | |
870 | static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, |
871 | const unsigned char *path, |
872 | const void *ns) |
873 | { |
874 | ssize_t len; |
875 | char *p, *name; |
876 | |
877 | lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem); |
878 | |
879 | spin_lock_irq(lock: &kernfs_pr_cont_lock); |
880 | |
881 | len = strscpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); |
882 | |
883 | if (len < 0) { |
884 | spin_unlock_irq(lock: &kernfs_pr_cont_lock); |
885 | return NULL; |
886 | } |
887 | |
888 | p = kernfs_pr_cont_buf; |
889 | |
890 | while ((name = strsep(&p, "/" )) && parent) { |
891 | if (*name == '\0') |
892 | continue; |
893 | parent = kernfs_find_ns(parent, name, ns); |
894 | } |
895 | |
896 | spin_unlock_irq(lock: &kernfs_pr_cont_lock); |
897 | |
898 | return parent; |
899 | } |
900 | |
901 | /** |
902 | * kernfs_find_and_get_ns - find and get kernfs_node with the given name |
903 | * @parent: kernfs_node to search under |
904 | * @name: name to look for |
905 | * @ns: the namespace tag to use |
906 | * |
907 | * Look for kernfs_node with name @name under @parent and get a reference |
908 | * if found. This function may sleep. |
909 | * |
910 | * Return: pointer to the found kernfs_node on success, %NULL on failure. |
911 | */ |
912 | struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, |
913 | const char *name, const void *ns) |
914 | { |
915 | struct kernfs_node *kn; |
916 | struct kernfs_root *root = kernfs_root(kn: parent); |
917 | |
918 | down_read(sem: &root->kernfs_rwsem); |
919 | kn = kernfs_find_ns(parent, name, ns); |
920 | kernfs_get(kn); |
921 | up_read(sem: &root->kernfs_rwsem); |
922 | |
923 | return kn; |
924 | } |
925 | EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); |
926 | |
927 | /** |
928 | * kernfs_walk_and_get_ns - find and get kernfs_node with the given path |
929 | * @parent: kernfs_node to search under |
930 | * @path: path to look for |
931 | * @ns: the namespace tag to use |
932 | * |
933 | * Look for kernfs_node with path @path under @parent and get a reference |
934 | * if found. This function may sleep. |
935 | * |
936 | * Return: pointer to the found kernfs_node on success, %NULL on failure. |
937 | */ |
938 | struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent, |
939 | const char *path, const void *ns) |
940 | { |
941 | struct kernfs_node *kn; |
942 | struct kernfs_root *root = kernfs_root(kn: parent); |
943 | |
944 | down_read(sem: &root->kernfs_rwsem); |
945 | kn = kernfs_walk_ns(parent, path, ns); |
946 | kernfs_get(kn); |
947 | up_read(sem: &root->kernfs_rwsem); |
948 | |
949 | return kn; |
950 | } |
951 | |
952 | /** |
953 | * kernfs_create_root - create a new kernfs hierarchy |
954 | * @scops: optional syscall operations for the hierarchy |
955 | * @flags: KERNFS_ROOT_* flags |
956 | * @priv: opaque data associated with the new directory |
957 | * |
958 | * Return: the root of the new hierarchy on success, ERR_PTR() value on |
959 | * failure. |
960 | */ |
961 | struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, |
962 | unsigned int flags, void *priv) |
963 | { |
964 | struct kernfs_root *root; |
965 | struct kernfs_node *kn; |
966 | |
967 | root = kzalloc(size: sizeof(*root), GFP_KERNEL); |
968 | if (!root) |
969 | return ERR_PTR(error: -ENOMEM); |
970 | |
971 | idr_init(idr: &root->ino_idr); |
972 | init_rwsem(&root->kernfs_rwsem); |
973 | init_rwsem(&root->kernfs_iattr_rwsem); |
974 | init_rwsem(&root->kernfs_supers_rwsem); |
975 | INIT_LIST_HEAD(list: &root->supers); |
976 | |
977 | /* |
978 | * On 64bit ino setups, id is ino. On 32bit, low 32bits are ino. |
979 | * High bits generation. The starting value for both ino and |
980 | * genenration is 1. Initialize upper 32bit allocation |
981 | * accordingly. |
982 | */ |
983 | if (sizeof(ino_t) >= sizeof(u64)) |
984 | root->id_highbits = 0; |
985 | else |
986 | root->id_highbits = 1; |
987 | |
988 | kn = __kernfs_new_node(root, NULL, name: "" , S_IFDIR | S_IRUGO | S_IXUGO, |
989 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
990 | flags: KERNFS_DIR); |
991 | if (!kn) { |
992 | idr_destroy(&root->ino_idr); |
993 | kfree(root); |
994 | return ERR_PTR(-ENOMEM); |
995 | } |
996 | |
997 | kn->priv = priv; |
998 | kn->dir.root = root; |
999 | |
1000 | root->syscall_ops = scops; |
1001 | root->flags = flags; |
1002 | root->kn = kn; |
1003 | init_waitqueue_head(&root->deactivate_waitq); |
1004 | |
1005 | if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
1006 | kernfs_activate(kn); |
1007 | |
1008 | return root; |
1009 | } |
1010 | |
1011 | /** |
1012 | * kernfs_destroy_root - destroy a kernfs hierarchy |
1013 | * @root: root of the hierarchy to destroy |
1014 | * |
1015 | * Destroy the hierarchy anchored at @root by removing all existing |
1016 | * directories and destroying @root. |
1017 | */ |
1018 | void kernfs_destroy_root(struct kernfs_root *root) |
1019 | { |
1020 | /* |
1021 | * kernfs_remove holds kernfs_rwsem from the root so the root |
1022 | * shouldn't be freed during the operation. |
1023 | */ |
1024 | kernfs_get(root->kn); |
1025 | kernfs_remove(kn: root->kn); |
1026 | kernfs_put(root->kn); /* will also free @root */ |
1027 | } |
1028 | |
1029 | /** |
1030 | * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root |
1031 | * @root: root to use to lookup |
1032 | * |
1033 | * Return: @root's kernfs_node |
1034 | */ |
1035 | struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root) |
1036 | { |
1037 | return root->kn; |
1038 | } |
1039 | |
1040 | /** |
1041 | * kernfs_create_dir_ns - create a directory |
1042 | * @parent: parent in which to create a new directory |
1043 | * @name: name of the new directory |
1044 | * @mode: mode of the new directory |
1045 | * @uid: uid of the new directory |
1046 | * @gid: gid of the new directory |
1047 | * @priv: opaque data associated with the new directory |
1048 | * @ns: optional namespace tag of the directory |
1049 | * |
1050 | * Return: the created node on success, ERR_PTR() value on failure. |
1051 | */ |
1052 | struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, |
1053 | const char *name, umode_t mode, |
1054 | kuid_t uid, kgid_t gid, |
1055 | void *priv, const void *ns) |
1056 | { |
1057 | struct kernfs_node *kn; |
1058 | int rc; |
1059 | |
1060 | /* allocate */ |
1061 | kn = kernfs_new_node(parent, name, mode: mode | S_IFDIR, |
1062 | uid, gid, flags: KERNFS_DIR); |
1063 | if (!kn) |
1064 | return ERR_PTR(error: -ENOMEM); |
1065 | |
1066 | kn->dir.root = parent->dir.root; |
1067 | kn->ns = ns; |
1068 | kn->priv = priv; |
1069 | |
1070 | /* link in */ |
1071 | rc = kernfs_add_one(kn); |
1072 | if (!rc) |
1073 | return kn; |
1074 | |
1075 | kernfs_put(kn); |
1076 | return ERR_PTR(error: rc); |
1077 | } |
1078 | |
1079 | /** |
1080 | * kernfs_create_empty_dir - create an always empty directory |
1081 | * @parent: parent in which to create a new directory |
1082 | * @name: name of the new directory |
1083 | * |
1084 | * Return: the created node on success, ERR_PTR() value on failure. |
1085 | */ |
1086 | struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent, |
1087 | const char *name) |
1088 | { |
1089 | struct kernfs_node *kn; |
1090 | int rc; |
1091 | |
1092 | /* allocate */ |
1093 | kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR, |
1094 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, flags: KERNFS_DIR); |
1095 | if (!kn) |
1096 | return ERR_PTR(-ENOMEM); |
1097 | |
1098 | kn->flags |= KERNFS_EMPTY_DIR; |
1099 | kn->dir.root = parent->dir.root; |
1100 | kn->ns = NULL; |
1101 | kn->priv = NULL; |
1102 | |
1103 | /* link in */ |
1104 | rc = kernfs_add_one(kn); |
1105 | if (!rc) |
1106 | return kn; |
1107 | |
1108 | kernfs_put(kn); |
1109 | return ERR_PTR(rc); |
1110 | } |
1111 | |
1112 | static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) |
1113 | { |
1114 | struct kernfs_node *kn; |
1115 | struct kernfs_root *root; |
1116 | |
1117 | if (flags & LOOKUP_RCU) |
1118 | return -ECHILD; |
1119 | |
1120 | /* Negative hashed dentry? */ |
1121 | if (d_really_is_negative(dentry)) { |
1122 | struct kernfs_node *parent; |
1123 | |
1124 | /* If the kernfs parent node has changed discard and |
1125 | * proceed to ->lookup. |
1126 | * |
1127 | * There's nothing special needed here when getting the |
1128 | * dentry parent, even if a concurrent rename is in |
1129 | * progress. That's because the dentry is negative so |
1130 | * it can only be the target of the rename and it will |
1131 | * be doing a d_move() not a replace. Consequently the |
1132 | * dentry d_parent won't change over the d_move(). |
1133 | * |
1134 | * Also kernfs negative dentries transitioning from |
1135 | * negative to positive during revalidate won't happen |
1136 | * because they are invalidated on containing directory |
1137 | * changes and the lookup re-done so that a new positive |
1138 | * dentry can be properly created. |
1139 | */ |
1140 | root = kernfs_root_from_sb(sb: dentry->d_sb); |
1141 | down_read(sem: &root->kernfs_rwsem); |
1142 | parent = kernfs_dentry_node(dentry: dentry->d_parent); |
1143 | if (parent) { |
1144 | if (kernfs_dir_changed(parent, dentry)) { |
1145 | up_read(sem: &root->kernfs_rwsem); |
1146 | return 0; |
1147 | } |
1148 | } |
1149 | up_read(sem: &root->kernfs_rwsem); |
1150 | |
1151 | /* The kernfs parent node hasn't changed, leave the |
1152 | * dentry negative and return success. |
1153 | */ |
1154 | return 1; |
1155 | } |
1156 | |
1157 | kn = kernfs_dentry_node(dentry); |
1158 | root = kernfs_root(kn); |
1159 | down_read(sem: &root->kernfs_rwsem); |
1160 | |
1161 | /* The kernfs node has been deactivated */ |
1162 | if (!kernfs_active(kn)) |
1163 | goto out_bad; |
1164 | |
1165 | /* The kernfs node has been moved? */ |
1166 | if (kernfs_dentry_node(dentry: dentry->d_parent) != kn->parent) |
1167 | goto out_bad; |
1168 | |
1169 | /* The kernfs node has been renamed */ |
1170 | if (strcmp(dentry->d_name.name, kn->name) != 0) |
1171 | goto out_bad; |
1172 | |
1173 | /* The kernfs node has been moved to a different namespace */ |
1174 | if (kn->parent && kernfs_ns_enabled(kn: kn->parent) && |
1175 | kernfs_info(dentry->d_sb)->ns != kn->ns) |
1176 | goto out_bad; |
1177 | |
1178 | up_read(sem: &root->kernfs_rwsem); |
1179 | return 1; |
1180 | out_bad: |
1181 | up_read(sem: &root->kernfs_rwsem); |
1182 | return 0; |
1183 | } |
1184 | |
1185 | const struct dentry_operations kernfs_dops = { |
1186 | .d_revalidate = kernfs_dop_revalidate, |
1187 | }; |
1188 | |
1189 | static struct dentry *kernfs_iop_lookup(struct inode *dir, |
1190 | struct dentry *dentry, |
1191 | unsigned int flags) |
1192 | { |
1193 | struct kernfs_node *parent = dir->i_private; |
1194 | struct kernfs_node *kn; |
1195 | struct kernfs_root *root; |
1196 | struct inode *inode = NULL; |
1197 | const void *ns = NULL; |
1198 | |
1199 | root = kernfs_root(kn: parent); |
1200 | down_read(sem: &root->kernfs_rwsem); |
1201 | if (kernfs_ns_enabled(kn: parent)) |
1202 | ns = kernfs_info(dir->i_sb)->ns; |
1203 | |
1204 | kn = kernfs_find_ns(parent, name: dentry->d_name.name, ns); |
1205 | /* attach dentry and inode */ |
1206 | if (kn) { |
1207 | /* Inactive nodes are invisible to the VFS so don't |
1208 | * create a negative. |
1209 | */ |
1210 | if (!kernfs_active(kn)) { |
1211 | up_read(sem: &root->kernfs_rwsem); |
1212 | return NULL; |
1213 | } |
1214 | inode = kernfs_get_inode(sb: dir->i_sb, kn); |
1215 | if (!inode) |
1216 | inode = ERR_PTR(error: -ENOMEM); |
1217 | } |
1218 | /* |
1219 | * Needed for negative dentry validation. |
1220 | * The negative dentry can be created in kernfs_iop_lookup() |
1221 | * or transforms from positive dentry in dentry_unlink_inode() |
1222 | * called from vfs_rmdir(). |
1223 | */ |
1224 | if (!IS_ERR(ptr: inode)) |
1225 | kernfs_set_rev(parent, dentry); |
1226 | up_read(sem: &root->kernfs_rwsem); |
1227 | |
1228 | /* instantiate and hash (possibly negative) dentry */ |
1229 | return d_splice_alias(inode, dentry); |
1230 | } |
1231 | |
1232 | static int kernfs_iop_mkdir(struct mnt_idmap *idmap, |
1233 | struct inode *dir, struct dentry *dentry, |
1234 | umode_t mode) |
1235 | { |
1236 | struct kernfs_node *parent = dir->i_private; |
1237 | struct kernfs_syscall_ops *scops = kernfs_root(kn: parent)->syscall_ops; |
1238 | int ret; |
1239 | |
1240 | if (!scops || !scops->mkdir) |
1241 | return -EPERM; |
1242 | |
1243 | if (!kernfs_get_active(kn: parent)) |
1244 | return -ENODEV; |
1245 | |
1246 | ret = scops->mkdir(parent, dentry->d_name.name, mode); |
1247 | |
1248 | kernfs_put_active(kn: parent); |
1249 | return ret; |
1250 | } |
1251 | |
1252 | static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) |
1253 | { |
1254 | struct kernfs_node *kn = kernfs_dentry_node(dentry); |
1255 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
1256 | int ret; |
1257 | |
1258 | if (!scops || !scops->rmdir) |
1259 | return -EPERM; |
1260 | |
1261 | if (!kernfs_get_active(kn)) |
1262 | return -ENODEV; |
1263 | |
1264 | ret = scops->rmdir(kn); |
1265 | |
1266 | kernfs_put_active(kn); |
1267 | return ret; |
1268 | } |
1269 | |
1270 | static int kernfs_iop_rename(struct mnt_idmap *idmap, |
1271 | struct inode *old_dir, struct dentry *old_dentry, |
1272 | struct inode *new_dir, struct dentry *new_dentry, |
1273 | unsigned int flags) |
1274 | { |
1275 | struct kernfs_node *kn = kernfs_dentry_node(dentry: old_dentry); |
1276 | struct kernfs_node *new_parent = new_dir->i_private; |
1277 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
1278 | int ret; |
1279 | |
1280 | if (flags) |
1281 | return -EINVAL; |
1282 | |
1283 | if (!scops || !scops->rename) |
1284 | return -EPERM; |
1285 | |
1286 | if (!kernfs_get_active(kn)) |
1287 | return -ENODEV; |
1288 | |
1289 | if (!kernfs_get_active(kn: new_parent)) { |
1290 | kernfs_put_active(kn); |
1291 | return -ENODEV; |
1292 | } |
1293 | |
1294 | ret = scops->rename(kn, new_parent, new_dentry->d_name.name); |
1295 | |
1296 | kernfs_put_active(kn: new_parent); |
1297 | kernfs_put_active(kn); |
1298 | return ret; |
1299 | } |
1300 | |
1301 | const struct inode_operations kernfs_dir_iops = { |
1302 | .lookup = kernfs_iop_lookup, |
1303 | .permission = kernfs_iop_permission, |
1304 | .setattr = kernfs_iop_setattr, |
1305 | .getattr = kernfs_iop_getattr, |
1306 | .listxattr = kernfs_iop_listxattr, |
1307 | |
1308 | .mkdir = kernfs_iop_mkdir, |
1309 | .rmdir = kernfs_iop_rmdir, |
1310 | .rename = kernfs_iop_rename, |
1311 | }; |
1312 | |
1313 | static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos) |
1314 | { |
1315 | struct kernfs_node *last; |
1316 | |
1317 | while (true) { |
1318 | struct rb_node *rbn; |
1319 | |
1320 | last = pos; |
1321 | |
1322 | if (kernfs_type(kn: pos) != KERNFS_DIR) |
1323 | break; |
1324 | |
1325 | rbn = rb_first(&pos->dir.children); |
1326 | if (!rbn) |
1327 | break; |
1328 | |
1329 | pos = rb_to_kn(rbn); |
1330 | } |
1331 | |
1332 | return last; |
1333 | } |
1334 | |
1335 | /** |
1336 | * kernfs_next_descendant_post - find the next descendant for post-order walk |
1337 | * @pos: the current position (%NULL to initiate traversal) |
1338 | * @root: kernfs_node whose descendants to walk |
1339 | * |
1340 | * Find the next descendant to visit for post-order traversal of @root's |
1341 | * descendants. @root is included in the iteration and the last node to be |
1342 | * visited. |
1343 | * |
1344 | * Return: the next descendant to visit or %NULL when done. |
1345 | */ |
1346 | static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, |
1347 | struct kernfs_node *root) |
1348 | { |
1349 | struct rb_node *rbn; |
1350 | |
1351 | lockdep_assert_held_write(&kernfs_root(root)->kernfs_rwsem); |
1352 | |
1353 | /* if first iteration, visit leftmost descendant which may be root */ |
1354 | if (!pos) |
1355 | return kernfs_leftmost_descendant(pos: root); |
1356 | |
1357 | /* if we visited @root, we're done */ |
1358 | if (pos == root) |
1359 | return NULL; |
1360 | |
1361 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
1362 | rbn = rb_next(&pos->rb); |
1363 | if (rbn) |
1364 | return kernfs_leftmost_descendant(rb_to_kn(rbn)); |
1365 | |
1366 | /* no sibling left, visit parent */ |
1367 | return pos->parent; |
1368 | } |
1369 | |
1370 | static void kernfs_activate_one(struct kernfs_node *kn) |
1371 | { |
1372 | lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); |
1373 | |
1374 | kn->flags |= KERNFS_ACTIVATED; |
1375 | |
1376 | if (kernfs_active(kn) || (kn->flags & (KERNFS_HIDDEN | KERNFS_REMOVING))) |
1377 | return; |
1378 | |
1379 | WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb)); |
1380 | WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); |
1381 | |
1382 | atomic_sub(KN_DEACTIVATED_BIAS, v: &kn->active); |
1383 | } |
1384 | |
1385 | /** |
1386 | * kernfs_activate - activate a node which started deactivated |
1387 | * @kn: kernfs_node whose subtree is to be activated |
1388 | * |
1389 | * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node |
1390 | * needs to be explicitly activated. A node which hasn't been activated |
1391 | * isn't visible to userland and deactivation is skipped during its |
1392 | * removal. This is useful to construct atomic init sequences where |
1393 | * creation of multiple nodes should either succeed or fail atomically. |
1394 | * |
1395 | * The caller is responsible for ensuring that this function is not called |
1396 | * after kernfs_remove*() is invoked on @kn. |
1397 | */ |
1398 | void kernfs_activate(struct kernfs_node *kn) |
1399 | { |
1400 | struct kernfs_node *pos; |
1401 | struct kernfs_root *root = kernfs_root(kn); |
1402 | |
1403 | down_write(sem: &root->kernfs_rwsem); |
1404 | |
1405 | pos = NULL; |
1406 | while ((pos = kernfs_next_descendant_post(pos, root: kn))) |
1407 | kernfs_activate_one(kn: pos); |
1408 | |
1409 | up_write(sem: &root->kernfs_rwsem); |
1410 | } |
1411 | |
1412 | /** |
1413 | * kernfs_show - show or hide a node |
1414 | * @kn: kernfs_node to show or hide |
1415 | * @show: whether to show or hide |
1416 | * |
1417 | * If @show is %false, @kn is marked hidden and deactivated. A hidden node is |
1418 | * ignored in future activaitons. If %true, the mark is removed and activation |
1419 | * state is restored. This function won't implicitly activate a new node in a |
1420 | * %KERNFS_ROOT_CREATE_DEACTIVATED root which hasn't been activated yet. |
1421 | * |
1422 | * To avoid recursion complexities, directories aren't supported for now. |
1423 | */ |
1424 | void kernfs_show(struct kernfs_node *kn, bool show) |
1425 | { |
1426 | struct kernfs_root *root = kernfs_root(kn); |
1427 | |
1428 | if (WARN_ON_ONCE(kernfs_type(kn) == KERNFS_DIR)) |
1429 | return; |
1430 | |
1431 | down_write(sem: &root->kernfs_rwsem); |
1432 | |
1433 | if (show) { |
1434 | kn->flags &= ~KERNFS_HIDDEN; |
1435 | if (kn->flags & KERNFS_ACTIVATED) |
1436 | kernfs_activate_one(kn); |
1437 | } else { |
1438 | kn->flags |= KERNFS_HIDDEN; |
1439 | if (kernfs_active(kn)) |
1440 | atomic_add(KN_DEACTIVATED_BIAS, v: &kn->active); |
1441 | kernfs_drain(kn); |
1442 | } |
1443 | |
1444 | up_write(sem: &root->kernfs_rwsem); |
1445 | } |
1446 | |
1447 | static void __kernfs_remove(struct kernfs_node *kn) |
1448 | { |
1449 | struct kernfs_node *pos; |
1450 | |
1451 | /* Short-circuit if non-root @kn has already finished removal. */ |
1452 | if (!kn) |
1453 | return; |
1454 | |
1455 | lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); |
1456 | |
1457 | /* |
1458 | * This is for kernfs_remove_self() which plays with active ref |
1459 | * after removal. |
1460 | */ |
1461 | if (kn->parent && RB_EMPTY_NODE(&kn->rb)) |
1462 | return; |
1463 | |
1464 | pr_debug("kernfs %s: removing\n" , kn->name); |
1465 | |
1466 | /* prevent new usage by marking all nodes removing and deactivating */ |
1467 | pos = NULL; |
1468 | while ((pos = kernfs_next_descendant_post(pos, root: kn))) { |
1469 | pos->flags |= KERNFS_REMOVING; |
1470 | if (kernfs_active(kn: pos)) |
1471 | atomic_add(KN_DEACTIVATED_BIAS, v: &pos->active); |
1472 | } |
1473 | |
1474 | /* deactivate and unlink the subtree node-by-node */ |
1475 | do { |
1476 | pos = kernfs_leftmost_descendant(pos: kn); |
1477 | |
1478 | /* |
1479 | * kernfs_drain() may drop kernfs_rwsem temporarily and @pos's |
1480 | * base ref could have been put by someone else by the time |
1481 | * the function returns. Make sure it doesn't go away |
1482 | * underneath us. |
1483 | */ |
1484 | kernfs_get(pos); |
1485 | |
1486 | kernfs_drain(kn: pos); |
1487 | |
1488 | /* |
1489 | * kernfs_unlink_sibling() succeeds once per node. Use it |
1490 | * to decide who's responsible for cleanups. |
1491 | */ |
1492 | if (!pos->parent || kernfs_unlink_sibling(kn: pos)) { |
1493 | struct kernfs_iattrs *ps_iattr = |
1494 | pos->parent ? pos->parent->iattr : NULL; |
1495 | |
1496 | /* update timestamps on the parent */ |
1497 | down_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
1498 | |
1499 | if (ps_iattr) { |
1500 | ktime_get_real_ts64(tv: &ps_iattr->ia_ctime); |
1501 | ps_iattr->ia_mtime = ps_iattr->ia_ctime; |
1502 | } |
1503 | |
1504 | up_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
1505 | kernfs_put(pos); |
1506 | } |
1507 | |
1508 | kernfs_put(pos); |
1509 | } while (pos != kn); |
1510 | } |
1511 | |
1512 | /** |
1513 | * kernfs_remove - remove a kernfs_node recursively |
1514 | * @kn: the kernfs_node to remove |
1515 | * |
1516 | * Remove @kn along with all its subdirectories and files. |
1517 | */ |
1518 | void kernfs_remove(struct kernfs_node *kn) |
1519 | { |
1520 | struct kernfs_root *root; |
1521 | |
1522 | if (!kn) |
1523 | return; |
1524 | |
1525 | root = kernfs_root(kn); |
1526 | |
1527 | down_write(sem: &root->kernfs_rwsem); |
1528 | __kernfs_remove(kn); |
1529 | up_write(sem: &root->kernfs_rwsem); |
1530 | } |
1531 | |
1532 | /** |
1533 | * kernfs_break_active_protection - break out of active protection |
1534 | * @kn: the self kernfs_node |
1535 | * |
1536 | * The caller must be running off of a kernfs operation which is invoked |
1537 | * with an active reference - e.g. one of kernfs_ops. Each invocation of |
1538 | * this function must also be matched with an invocation of |
1539 | * kernfs_unbreak_active_protection(). |
1540 | * |
1541 | * This function releases the active reference of @kn the caller is |
1542 | * holding. Once this function is called, @kn may be removed at any point |
1543 | * and the caller is solely responsible for ensuring that the objects it |
1544 | * dereferences are accessible. |
1545 | */ |
1546 | void kernfs_break_active_protection(struct kernfs_node *kn) |
1547 | { |
1548 | /* |
1549 | * Take out ourself out of the active ref dependency chain. If |
1550 | * we're called without an active ref, lockdep will complain. |
1551 | */ |
1552 | kernfs_put_active(kn); |
1553 | } |
1554 | |
1555 | /** |
1556 | * kernfs_unbreak_active_protection - undo kernfs_break_active_protection() |
1557 | * @kn: the self kernfs_node |
1558 | * |
1559 | * If kernfs_break_active_protection() was called, this function must be |
1560 | * invoked before finishing the kernfs operation. Note that while this |
1561 | * function restores the active reference, it doesn't and can't actually |
1562 | * restore the active protection - @kn may already or be in the process of |
1563 | * being removed. Once kernfs_break_active_protection() is invoked, that |
1564 | * protection is irreversibly gone for the kernfs operation instance. |
1565 | * |
1566 | * While this function may be called at any point after |
1567 | * kernfs_break_active_protection() is invoked, its most useful location |
1568 | * would be right before the enclosing kernfs operation returns. |
1569 | */ |
1570 | void kernfs_unbreak_active_protection(struct kernfs_node *kn) |
1571 | { |
1572 | /* |
1573 | * @kn->active could be in any state; however, the increment we do |
1574 | * here will be undone as soon as the enclosing kernfs operation |
1575 | * finishes and this temporary bump can't break anything. If @kn |
1576 | * is alive, nothing changes. If @kn is being deactivated, the |
1577 | * soon-to-follow put will either finish deactivation or restore |
1578 | * deactivated state. If @kn is already removed, the temporary |
1579 | * bump is guaranteed to be gone before @kn is released. |
1580 | */ |
1581 | atomic_inc(v: &kn->active); |
1582 | if (kernfs_lockdep(kn)) |
1583 | rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_); |
1584 | } |
1585 | |
1586 | /** |
1587 | * kernfs_remove_self - remove a kernfs_node from its own method |
1588 | * @kn: the self kernfs_node to remove |
1589 | * |
1590 | * The caller must be running off of a kernfs operation which is invoked |
1591 | * with an active reference - e.g. one of kernfs_ops. This can be used to |
1592 | * implement a file operation which deletes itself. |
1593 | * |
1594 | * For example, the "delete" file for a sysfs device directory can be |
1595 | * implemented by invoking kernfs_remove_self() on the "delete" file |
1596 | * itself. This function breaks the circular dependency of trying to |
1597 | * deactivate self while holding an active ref itself. It isn't necessary |
1598 | * to modify the usual removal path to use kernfs_remove_self(). The |
1599 | * "delete" implementation can simply invoke kernfs_remove_self() on self |
1600 | * before proceeding with the usual removal path. kernfs will ignore later |
1601 | * kernfs_remove() on self. |
1602 | * |
1603 | * kernfs_remove_self() can be called multiple times concurrently on the |
1604 | * same kernfs_node. Only the first one actually performs removal and |
1605 | * returns %true. All others will wait until the kernfs operation which |
1606 | * won self-removal finishes and return %false. Note that the losers wait |
1607 | * for the completion of not only the winning kernfs_remove_self() but also |
1608 | * the whole kernfs_ops which won the arbitration. This can be used to |
1609 | * guarantee, for example, all concurrent writes to a "delete" file to |
1610 | * finish only after the whole operation is complete. |
1611 | * |
1612 | * Return: %true if @kn is removed by this call, otherwise %false. |
1613 | */ |
1614 | bool kernfs_remove_self(struct kernfs_node *kn) |
1615 | { |
1616 | bool ret; |
1617 | struct kernfs_root *root = kernfs_root(kn); |
1618 | |
1619 | down_write(sem: &root->kernfs_rwsem); |
1620 | kernfs_break_active_protection(kn); |
1621 | |
1622 | /* |
1623 | * SUICIDAL is used to arbitrate among competing invocations. Only |
1624 | * the first one will actually perform removal. When the removal |
1625 | * is complete, SUICIDED is set and the active ref is restored |
1626 | * while kernfs_rwsem for held exclusive. The ones which lost |
1627 | * arbitration waits for SUICIDED && drained which can happen only |
1628 | * after the enclosing kernfs operation which executed the winning |
1629 | * instance of kernfs_remove_self() finished. |
1630 | */ |
1631 | if (!(kn->flags & KERNFS_SUICIDAL)) { |
1632 | kn->flags |= KERNFS_SUICIDAL; |
1633 | __kernfs_remove(kn); |
1634 | kn->flags |= KERNFS_SUICIDED; |
1635 | ret = true; |
1636 | } else { |
1637 | wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq; |
1638 | DEFINE_WAIT(wait); |
1639 | |
1640 | while (true) { |
1641 | prepare_to_wait(wq_head: waitq, wq_entry: &wait, TASK_UNINTERRUPTIBLE); |
1642 | |
1643 | if ((kn->flags & KERNFS_SUICIDED) && |
1644 | atomic_read(v: &kn->active) == KN_DEACTIVATED_BIAS) |
1645 | break; |
1646 | |
1647 | up_write(sem: &root->kernfs_rwsem); |
1648 | schedule(); |
1649 | down_write(sem: &root->kernfs_rwsem); |
1650 | } |
1651 | finish_wait(wq_head: waitq, wq_entry: &wait); |
1652 | WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb)); |
1653 | ret = false; |
1654 | } |
1655 | |
1656 | /* |
1657 | * This must be done while kernfs_rwsem held exclusive; otherwise, |
1658 | * waiting for SUICIDED && deactivated could finish prematurely. |
1659 | */ |
1660 | kernfs_unbreak_active_protection(kn); |
1661 | |
1662 | up_write(sem: &root->kernfs_rwsem); |
1663 | return ret; |
1664 | } |
1665 | |
1666 | /** |
1667 | * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it |
1668 | * @parent: parent of the target |
1669 | * @name: name of the kernfs_node to remove |
1670 | * @ns: namespace tag of the kernfs_node to remove |
1671 | * |
1672 | * Look for the kernfs_node with @name and @ns under @parent and remove it. |
1673 | * |
1674 | * Return: %0 on success, -ENOENT if such entry doesn't exist. |
1675 | */ |
1676 | int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, |
1677 | const void *ns) |
1678 | { |
1679 | struct kernfs_node *kn; |
1680 | struct kernfs_root *root; |
1681 | |
1682 | if (!parent) { |
1683 | WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n" , |
1684 | name); |
1685 | return -ENOENT; |
1686 | } |
1687 | |
1688 | root = kernfs_root(kn: parent); |
1689 | down_write(sem: &root->kernfs_rwsem); |
1690 | |
1691 | kn = kernfs_find_ns(parent, name, ns); |
1692 | if (kn) { |
1693 | kernfs_get(kn); |
1694 | __kernfs_remove(kn); |
1695 | kernfs_put(kn); |
1696 | } |
1697 | |
1698 | up_write(sem: &root->kernfs_rwsem); |
1699 | |
1700 | if (kn) |
1701 | return 0; |
1702 | else |
1703 | return -ENOENT; |
1704 | } |
1705 | |
1706 | /** |
1707 | * kernfs_rename_ns - move and rename a kernfs_node |
1708 | * @kn: target node |
1709 | * @new_parent: new parent to put @sd under |
1710 | * @new_name: new name |
1711 | * @new_ns: new namespace tag |
1712 | * |
1713 | * Return: %0 on success, -errno on failure. |
1714 | */ |
1715 | int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, |
1716 | const char *new_name, const void *new_ns) |
1717 | { |
1718 | struct kernfs_node *old_parent; |
1719 | struct kernfs_root *root; |
1720 | const char *old_name = NULL; |
1721 | int error; |
1722 | |
1723 | /* can't move or rename root */ |
1724 | if (!kn->parent) |
1725 | return -EINVAL; |
1726 | |
1727 | root = kernfs_root(kn); |
1728 | down_write(sem: &root->kernfs_rwsem); |
1729 | |
1730 | error = -ENOENT; |
1731 | if (!kernfs_active(kn) || !kernfs_active(kn: new_parent) || |
1732 | (new_parent->flags & KERNFS_EMPTY_DIR)) |
1733 | goto out; |
1734 | |
1735 | error = 0; |
1736 | if ((kn->parent == new_parent) && (kn->ns == new_ns) && |
1737 | (strcmp(kn->name, new_name) == 0)) |
1738 | goto out; /* nothing to rename */ |
1739 | |
1740 | error = -EEXIST; |
1741 | if (kernfs_find_ns(parent: new_parent, name: new_name, ns: new_ns)) |
1742 | goto out; |
1743 | |
1744 | /* rename kernfs_node */ |
1745 | if (strcmp(kn->name, new_name) != 0) { |
1746 | error = -ENOMEM; |
1747 | new_name = kstrdup_const(s: new_name, GFP_KERNEL); |
1748 | if (!new_name) |
1749 | goto out; |
1750 | } else { |
1751 | new_name = NULL; |
1752 | } |
1753 | |
1754 | /* |
1755 | * Move to the appropriate place in the appropriate directories rbtree. |
1756 | */ |
1757 | kernfs_unlink_sibling(kn); |
1758 | kernfs_get(new_parent); |
1759 | |
1760 | /* rename_lock protects ->parent and ->name accessors */ |
1761 | write_lock_irq(&kernfs_rename_lock); |
1762 | |
1763 | old_parent = kn->parent; |
1764 | kn->parent = new_parent; |
1765 | |
1766 | kn->ns = new_ns; |
1767 | if (new_name) { |
1768 | old_name = kn->name; |
1769 | kn->name = new_name; |
1770 | } |
1771 | |
1772 | write_unlock_irq(&kernfs_rename_lock); |
1773 | |
1774 | kn->hash = kernfs_name_hash(name: kn->name, ns: kn->ns); |
1775 | kernfs_link_sibling(kn); |
1776 | |
1777 | kernfs_put(old_parent); |
1778 | kfree_const(x: old_name); |
1779 | |
1780 | error = 0; |
1781 | out: |
1782 | up_write(sem: &root->kernfs_rwsem); |
1783 | return error; |
1784 | } |
1785 | |
1786 | static int kernfs_dir_fop_release(struct inode *inode, struct file *filp) |
1787 | { |
1788 | kernfs_put(filp->private_data); |
1789 | return 0; |
1790 | } |
1791 | |
1792 | static struct kernfs_node *kernfs_dir_pos(const void *ns, |
1793 | struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) |
1794 | { |
1795 | if (pos) { |
1796 | int valid = kernfs_active(kn: pos) && |
1797 | pos->parent == parent && hash == pos->hash; |
1798 | kernfs_put(pos); |
1799 | if (!valid) |
1800 | pos = NULL; |
1801 | } |
1802 | if (!pos && (hash > 1) && (hash < INT_MAX)) { |
1803 | struct rb_node *node = parent->dir.children.rb_node; |
1804 | while (node) { |
1805 | pos = rb_to_kn(node); |
1806 | |
1807 | if (hash < pos->hash) |
1808 | node = node->rb_left; |
1809 | else if (hash > pos->hash) |
1810 | node = node->rb_right; |
1811 | else |
1812 | break; |
1813 | } |
1814 | } |
1815 | /* Skip over entries which are dying/dead or in the wrong namespace */ |
1816 | while (pos && (!kernfs_active(kn: pos) || pos->ns != ns)) { |
1817 | struct rb_node *node = rb_next(&pos->rb); |
1818 | if (!node) |
1819 | pos = NULL; |
1820 | else |
1821 | pos = rb_to_kn(node); |
1822 | } |
1823 | return pos; |
1824 | } |
1825 | |
1826 | static struct kernfs_node *kernfs_dir_next_pos(const void *ns, |
1827 | struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos) |
1828 | { |
1829 | pos = kernfs_dir_pos(ns, parent, hash: ino, pos); |
1830 | if (pos) { |
1831 | do { |
1832 | struct rb_node *node = rb_next(&pos->rb); |
1833 | if (!node) |
1834 | pos = NULL; |
1835 | else |
1836 | pos = rb_to_kn(node); |
1837 | } while (pos && (!kernfs_active(kn: pos) || pos->ns != ns)); |
1838 | } |
1839 | return pos; |
1840 | } |
1841 | |
1842 | static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) |
1843 | { |
1844 | struct dentry *dentry = file->f_path.dentry; |
1845 | struct kernfs_node *parent = kernfs_dentry_node(dentry); |
1846 | struct kernfs_node *pos = file->private_data; |
1847 | struct kernfs_root *root; |
1848 | const void *ns = NULL; |
1849 | |
1850 | if (!dir_emit_dots(file, ctx)) |
1851 | return 0; |
1852 | |
1853 | root = kernfs_root(kn: parent); |
1854 | down_read(sem: &root->kernfs_rwsem); |
1855 | |
1856 | if (kernfs_ns_enabled(kn: parent)) |
1857 | ns = kernfs_info(dentry->d_sb)->ns; |
1858 | |
1859 | for (pos = kernfs_dir_pos(ns, parent, hash: ctx->pos, pos); |
1860 | pos; |
1861 | pos = kernfs_dir_next_pos(ns, parent, ino: ctx->pos, pos)) { |
1862 | const char *name = pos->name; |
1863 | unsigned int type = fs_umode_to_dtype(mode: pos->mode); |
1864 | int len = strlen(name); |
1865 | ino_t ino = kernfs_ino(kn: pos); |
1866 | |
1867 | ctx->pos = pos->hash; |
1868 | file->private_data = pos; |
1869 | kernfs_get(pos); |
1870 | |
1871 | up_read(sem: &root->kernfs_rwsem); |
1872 | if (!dir_emit(ctx, name, namelen: len, ino, type)) |
1873 | return 0; |
1874 | down_read(sem: &root->kernfs_rwsem); |
1875 | } |
1876 | up_read(sem: &root->kernfs_rwsem); |
1877 | file->private_data = NULL; |
1878 | ctx->pos = INT_MAX; |
1879 | return 0; |
1880 | } |
1881 | |
1882 | const struct file_operations kernfs_dir_fops = { |
1883 | .read = generic_read_dir, |
1884 | .iterate_shared = kernfs_fop_readdir, |
1885 | .release = kernfs_dir_fop_release, |
1886 | .llseek = generic_file_llseek, |
1887 | }; |
1888 | |