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 strlcpy(p: buf, q: "(null)" , size: buflen); |
58 | |
59 | return strlcpy(p: buf, q: kn->parent ? kn->name : "/" , size: 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 full path. If the full length is equal to or |
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 | int i, j; |
142 | |
143 | if (!kn_to) |
144 | return strlcpy(p: buf, q: "(null)" , size: buflen); |
145 | |
146 | if (!kn_from) |
147 | kn_from = kernfs_root(kn: kn_to)->kn; |
148 | |
149 | if (kn_from == kn_to) |
150 | return strlcpy(p: buf, q: "/" , size: buflen); |
151 | |
152 | common = kernfs_common_ancestor(a: kn_from, b: kn_to); |
153 | if (WARN_ON(!common)) |
154 | return -EINVAL; |
155 | |
156 | depth_to = kernfs_depth(from: common, to: kn_to); |
157 | depth_from = kernfs_depth(from: common, to: kn_from); |
158 | |
159 | buf[0] = '\0'; |
160 | |
161 | for (i = 0; i < depth_from; i++) |
162 | len += strlcpy(p: buf + len, q: parent_str, |
163 | size: len < buflen ? buflen - len : 0); |
164 | |
165 | /* Calculate how many bytes we need for the rest */ |
166 | for (i = depth_to - 1; i >= 0; i--) { |
167 | for (kn = kn_to, j = 0; j < i; j++) |
168 | kn = kn->parent; |
169 | len += strlcpy(p: buf + len, q: "/" , |
170 | size: len < buflen ? buflen - len : 0); |
171 | len += strlcpy(p: buf + len, q: kn->name, |
172 | size: len < buflen ? buflen - len : 0); |
173 | } |
174 | |
175 | return len; |
176 | } |
177 | |
178 | /** |
179 | * kernfs_name - obtain the name of a given node |
180 | * @kn: kernfs_node of interest |
181 | * @buf: buffer to copy @kn's name into |
182 | * @buflen: size of @buf |
183 | * |
184 | * Copies the name of @kn into @buf of @buflen bytes. The behavior is |
185 | * similar to strlcpy(). |
186 | * |
187 | * Fills buffer with "(null)" if @kn is %NULL. |
188 | * |
189 | * Return: the length of @kn's name and if @buf isn't long enough, |
190 | * it's filled up to @buflen-1 and nul terminated. |
191 | * |
192 | * This function can be called from any context. |
193 | */ |
194 | int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) |
195 | { |
196 | unsigned long flags; |
197 | int ret; |
198 | |
199 | read_lock_irqsave(&kernfs_rename_lock, flags); |
200 | ret = kernfs_name_locked(kn, buf, buflen); |
201 | read_unlock_irqrestore(&kernfs_rename_lock, flags); |
202 | return ret; |
203 | } |
204 | |
205 | /** |
206 | * kernfs_path_from_node - build path of node @to relative to @from. |
207 | * @from: parent kernfs_node relative to which we need to build the path |
208 | * @to: kernfs_node of interest |
209 | * @buf: buffer to copy @to's path into |
210 | * @buflen: size of @buf |
211 | * |
212 | * Builds @to's path relative to @from in @buf. @from and @to must |
213 | * be on the same kernfs-root. If @from is not parent of @to, then a relative |
214 | * path (which includes '..'s) as needed to reach from @from to @to is |
215 | * returned. |
216 | * |
217 | * Return: the length of the full path. If the full length is equal to or |
218 | * greater than @buflen, @buf contains the truncated path with the trailing |
219 | * '\0'. On error, -errno is returned. |
220 | */ |
221 | int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from, |
222 | char *buf, size_t buflen) |
223 | { |
224 | unsigned long flags; |
225 | int ret; |
226 | |
227 | read_lock_irqsave(&kernfs_rename_lock, flags); |
228 | ret = kernfs_path_from_node_locked(kn_to: to, kn_from: from, buf, buflen); |
229 | read_unlock_irqrestore(&kernfs_rename_lock, flags); |
230 | return ret; |
231 | } |
232 | EXPORT_SYMBOL_GPL(kernfs_path_from_node); |
233 | |
234 | /** |
235 | * pr_cont_kernfs_name - pr_cont name of a kernfs_node |
236 | * @kn: kernfs_node of interest |
237 | * |
238 | * This function can be called from any context. |
239 | */ |
240 | void pr_cont_kernfs_name(struct kernfs_node *kn) |
241 | { |
242 | unsigned long flags; |
243 | |
244 | spin_lock_irqsave(&kernfs_pr_cont_lock, flags); |
245 | |
246 | kernfs_name(kn, buf: kernfs_pr_cont_buf, buflen: sizeof(kernfs_pr_cont_buf)); |
247 | pr_cont("%s" , kernfs_pr_cont_buf); |
248 | |
249 | spin_unlock_irqrestore(lock: &kernfs_pr_cont_lock, flags); |
250 | } |
251 | |
252 | /** |
253 | * pr_cont_kernfs_path - pr_cont path of a kernfs_node |
254 | * @kn: kernfs_node of interest |
255 | * |
256 | * This function can be called from any context. |
257 | */ |
258 | void pr_cont_kernfs_path(struct kernfs_node *kn) |
259 | { |
260 | unsigned long flags; |
261 | int sz; |
262 | |
263 | spin_lock_irqsave(&kernfs_pr_cont_lock, flags); |
264 | |
265 | sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf, |
266 | sizeof(kernfs_pr_cont_buf)); |
267 | if (sz < 0) { |
268 | pr_cont("(error)" ); |
269 | goto out; |
270 | } |
271 | |
272 | if (sz >= sizeof(kernfs_pr_cont_buf)) { |
273 | pr_cont("(name too long)" ); |
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 | /** |
533 | * kernfs_put - put a reference count on a kernfs_node |
534 | * @kn: the target kernfs_node |
535 | * |
536 | * Put a reference count of @kn and destroy it if it reached zero. |
537 | */ |
538 | void kernfs_put(struct kernfs_node *kn) |
539 | { |
540 | struct kernfs_node *parent; |
541 | struct kernfs_root *root; |
542 | |
543 | if (!kn || !atomic_dec_and_test(v: &kn->count)) |
544 | return; |
545 | root = kernfs_root(kn); |
546 | repeat: |
547 | /* |
548 | * Moving/renaming is always done while holding reference. |
549 | * kn->parent won't change beneath us. |
550 | */ |
551 | parent = kn->parent; |
552 | |
553 | WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS, |
554 | "kernfs_put: %s/%s: released with incorrect active_ref %d\n" , |
555 | parent ? parent->name : "" , kn->name, atomic_read(&kn->active)); |
556 | |
557 | if (kernfs_type(kn) == KERNFS_LINK) |
558 | kernfs_put(kn: kn->symlink.target_kn); |
559 | |
560 | kfree_const(x: kn->name); |
561 | |
562 | if (kn->iattr) { |
563 | simple_xattrs_free(xattrs: &kn->iattr->xattrs, NULL); |
564 | kmem_cache_free(s: kernfs_iattrs_cache, objp: kn->iattr); |
565 | } |
566 | spin_lock(lock: &kernfs_idr_lock); |
567 | idr_remove(&root->ino_idr, id: (u32)kernfs_ino(kn)); |
568 | spin_unlock(lock: &kernfs_idr_lock); |
569 | kmem_cache_free(s: kernfs_node_cache, objp: kn); |
570 | |
571 | kn = parent; |
572 | if (kn) { |
573 | if (atomic_dec_and_test(v: &kn->count)) |
574 | goto repeat; |
575 | } else { |
576 | /* just released the root kn, free @root too */ |
577 | idr_destroy(&root->ino_idr); |
578 | kfree(objp: root); |
579 | } |
580 | } |
581 | EXPORT_SYMBOL_GPL(kernfs_put); |
582 | |
583 | /** |
584 | * kernfs_node_from_dentry - determine kernfs_node associated with a dentry |
585 | * @dentry: the dentry in question |
586 | * |
587 | * Return: the kernfs_node associated with @dentry. If @dentry is not a |
588 | * kernfs one, %NULL is returned. |
589 | * |
590 | * While the returned kernfs_node will stay accessible as long as @dentry |
591 | * is accessible, the returned node can be in any state and the caller is |
592 | * fully responsible for determining what's accessible. |
593 | */ |
594 | struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) |
595 | { |
596 | if (dentry->d_sb->s_op == &kernfs_sops) |
597 | return kernfs_dentry_node(dentry); |
598 | return NULL; |
599 | } |
600 | |
601 | static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, |
602 | struct kernfs_node *parent, |
603 | const char *name, umode_t mode, |
604 | kuid_t uid, kgid_t gid, |
605 | unsigned flags) |
606 | { |
607 | struct kernfs_node *kn; |
608 | u32 id_highbits; |
609 | int ret; |
610 | |
611 | name = kstrdup_const(s: name, GFP_KERNEL); |
612 | if (!name) |
613 | return NULL; |
614 | |
615 | kn = kmem_cache_zalloc(k: kernfs_node_cache, GFP_KERNEL); |
616 | if (!kn) |
617 | goto err_out1; |
618 | |
619 | idr_preload(GFP_KERNEL); |
620 | spin_lock(lock: &kernfs_idr_lock); |
621 | ret = idr_alloc_cyclic(&root->ino_idr, ptr: kn, start: 1, end: 0, GFP_ATOMIC); |
622 | if (ret >= 0 && ret < root->last_id_lowbits) |
623 | root->id_highbits++; |
624 | id_highbits = root->id_highbits; |
625 | root->last_id_lowbits = ret; |
626 | spin_unlock(lock: &kernfs_idr_lock); |
627 | idr_preload_end(); |
628 | if (ret < 0) |
629 | goto err_out2; |
630 | |
631 | kn->id = (u64)id_highbits << 32 | ret; |
632 | |
633 | atomic_set(v: &kn->count, i: 1); |
634 | atomic_set(v: &kn->active, KN_DEACTIVATED_BIAS); |
635 | RB_CLEAR_NODE(&kn->rb); |
636 | |
637 | kn->name = name; |
638 | kn->mode = mode; |
639 | kn->flags = flags; |
640 | |
641 | if (!uid_eq(left: uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) { |
642 | struct iattr iattr = { |
643 | .ia_valid = ATTR_UID | ATTR_GID, |
644 | .ia_uid = uid, |
645 | .ia_gid = gid, |
646 | }; |
647 | |
648 | ret = __kernfs_setattr(kn, &iattr); |
649 | if (ret < 0) |
650 | goto err_out3; |
651 | } |
652 | |
653 | if (parent) { |
654 | ret = security_kernfs_init_security(parent, kn); |
655 | if (ret) |
656 | goto err_out3; |
657 | } |
658 | |
659 | return kn; |
660 | |
661 | err_out3: |
662 | spin_lock(&kernfs_idr_lock); |
663 | idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
664 | spin_unlock(&kernfs_idr_lock); |
665 | err_out2: |
666 | kmem_cache_free(kernfs_node_cache, kn); |
667 | err_out1: |
668 | kfree_const(name); |
669 | return NULL; |
670 | } |
671 | |
672 | struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, |
673 | const char *name, umode_t mode, |
674 | kuid_t uid, kgid_t gid, |
675 | unsigned flags) |
676 | { |
677 | struct kernfs_node *kn; |
678 | |
679 | kn = __kernfs_new_node(root: kernfs_root(kn: parent), parent, |
680 | name, mode, uid, gid, flags); |
681 | if (kn) { |
682 | kernfs_get(parent); |
683 | kn->parent = parent; |
684 | } |
685 | return kn; |
686 | } |
687 | |
688 | /* |
689 | * kernfs_find_and_get_node_by_id - get kernfs_node from node id |
690 | * @root: the kernfs root |
691 | * @id: the target node id |
692 | * |
693 | * @id's lower 32bits encode ino and upper gen. If the gen portion is |
694 | * zero, all generations are matched. |
695 | * |
696 | * Return: %NULL on failure, |
697 | * otherwise a kernfs node with reference counter incremented. |
698 | */ |
699 | struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, |
700 | u64 id) |
701 | { |
702 | struct kernfs_node *kn; |
703 | ino_t ino = kernfs_id_ino(id); |
704 | u32 gen = kernfs_id_gen(id); |
705 | |
706 | spin_lock(lock: &kernfs_idr_lock); |
707 | |
708 | kn = idr_find(&root->ino_idr, id: (u32)ino); |
709 | if (!kn) |
710 | goto err_unlock; |
711 | |
712 | if (sizeof(ino_t) >= sizeof(u64)) { |
713 | /* we looked up with the low 32bits, compare the whole */ |
714 | if (kernfs_ino(kn) != ino) |
715 | goto err_unlock; |
716 | } else { |
717 | /* 0 matches all generations */ |
718 | if (unlikely(gen && kernfs_gen(kn) != gen)) |
719 | goto err_unlock; |
720 | } |
721 | |
722 | /* |
723 | * We should fail if @kn has never been activated and guarantee success |
724 | * if the caller knows that @kn is active. Both can be achieved by |
725 | * __kernfs_active() which tests @kn->active without kernfs_rwsem. |
726 | */ |
727 | if (unlikely(!__kernfs_active(kn) || !atomic_inc_not_zero(&kn->count))) |
728 | goto err_unlock; |
729 | |
730 | spin_unlock(lock: &kernfs_idr_lock); |
731 | return kn; |
732 | err_unlock: |
733 | spin_unlock(lock: &kernfs_idr_lock); |
734 | return NULL; |
735 | } |
736 | |
737 | /** |
738 | * kernfs_add_one - add kernfs_node to parent without warning |
739 | * @kn: kernfs_node to be added |
740 | * |
741 | * The caller must already have initialized @kn->parent. This |
742 | * function increments nlink of the parent's inode if @kn is a |
743 | * directory and link into the children list of the parent. |
744 | * |
745 | * Return: |
746 | * %0 on success, -EEXIST if entry with the given name already |
747 | * exists. |
748 | */ |
749 | int kernfs_add_one(struct kernfs_node *kn) |
750 | { |
751 | struct kernfs_node *parent = kn->parent; |
752 | struct kernfs_root *root = kernfs_root(kn: parent); |
753 | struct kernfs_iattrs *ps_iattr; |
754 | bool has_ns; |
755 | int ret; |
756 | |
757 | down_write(sem: &root->kernfs_rwsem); |
758 | |
759 | ret = -EINVAL; |
760 | has_ns = kernfs_ns_enabled(kn: parent); |
761 | if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n" , |
762 | has_ns ? "required" : "invalid" , parent->name, kn->name)) |
763 | goto out_unlock; |
764 | |
765 | if (kernfs_type(kn: parent) != KERNFS_DIR) |
766 | goto out_unlock; |
767 | |
768 | ret = -ENOENT; |
769 | if (parent->flags & (KERNFS_REMOVING | KERNFS_EMPTY_DIR)) |
770 | goto out_unlock; |
771 | |
772 | kn->hash = kernfs_name_hash(name: kn->name, ns: kn->ns); |
773 | |
774 | ret = kernfs_link_sibling(kn); |
775 | if (ret) |
776 | goto out_unlock; |
777 | |
778 | /* Update timestamps on the parent */ |
779 | down_write(sem: &root->kernfs_iattr_rwsem); |
780 | |
781 | ps_iattr = parent->iattr; |
782 | if (ps_iattr) { |
783 | ktime_get_real_ts64(tv: &ps_iattr->ia_ctime); |
784 | ps_iattr->ia_mtime = ps_iattr->ia_ctime; |
785 | } |
786 | |
787 | up_write(sem: &root->kernfs_iattr_rwsem); |
788 | up_write(sem: &root->kernfs_rwsem); |
789 | |
790 | /* |
791 | * Activate the new node unless CREATE_DEACTIVATED is requested. |
792 | * If not activated here, the kernfs user is responsible for |
793 | * activating the node with kernfs_activate(). A node which hasn't |
794 | * been activated is not visible to userland and its removal won't |
795 | * trigger deactivation. |
796 | */ |
797 | if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
798 | kernfs_activate(kn); |
799 | return 0; |
800 | |
801 | out_unlock: |
802 | up_write(sem: &root->kernfs_rwsem); |
803 | return ret; |
804 | } |
805 | |
806 | /** |
807 | * kernfs_find_ns - find kernfs_node with the given name |
808 | * @parent: kernfs_node to search under |
809 | * @name: name to look for |
810 | * @ns: the namespace tag to use |
811 | * |
812 | * Look for kernfs_node with name @name under @parent. |
813 | * |
814 | * Return: pointer to the found kernfs_node on success, %NULL on failure. |
815 | */ |
816 | static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, |
817 | const unsigned char *name, |
818 | const void *ns) |
819 | { |
820 | struct rb_node *node = parent->dir.children.rb_node; |
821 | bool has_ns = kernfs_ns_enabled(kn: parent); |
822 | unsigned int hash; |
823 | |
824 | lockdep_assert_held(&kernfs_root(parent)->kernfs_rwsem); |
825 | |
826 | if (has_ns != (bool)ns) { |
827 | WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n" , |
828 | has_ns ? "required" : "invalid" , parent->name, name); |
829 | return NULL; |
830 | } |
831 | |
832 | hash = kernfs_name_hash(name, ns); |
833 | while (node) { |
834 | struct kernfs_node *kn; |
835 | int result; |
836 | |
837 | kn = rb_to_kn(node); |
838 | result = kernfs_name_compare(hash, name, ns, kn); |
839 | if (result < 0) |
840 | node = node->rb_left; |
841 | else if (result > 0) |
842 | node = node->rb_right; |
843 | else |
844 | return kn; |
845 | } |
846 | return NULL; |
847 | } |
848 | |
849 | static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, |
850 | const unsigned char *path, |
851 | const void *ns) |
852 | { |
853 | size_t len; |
854 | char *p, *name; |
855 | |
856 | lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem); |
857 | |
858 | spin_lock_irq(lock: &kernfs_pr_cont_lock); |
859 | |
860 | len = strlcpy(p: kernfs_pr_cont_buf, q: path, size: sizeof(kernfs_pr_cont_buf)); |
861 | |
862 | if (len >= sizeof(kernfs_pr_cont_buf)) { |
863 | spin_unlock_irq(lock: &kernfs_pr_cont_lock); |
864 | return NULL; |
865 | } |
866 | |
867 | p = kernfs_pr_cont_buf; |
868 | |
869 | while ((name = strsep(&p, "/" )) && parent) { |
870 | if (*name == '\0') |
871 | continue; |
872 | parent = kernfs_find_ns(parent, name, ns); |
873 | } |
874 | |
875 | spin_unlock_irq(lock: &kernfs_pr_cont_lock); |
876 | |
877 | return parent; |
878 | } |
879 | |
880 | /** |
881 | * kernfs_find_and_get_ns - find and get kernfs_node with the given name |
882 | * @parent: kernfs_node to search under |
883 | * @name: name to look for |
884 | * @ns: the namespace tag to use |
885 | * |
886 | * Look for kernfs_node with name @name under @parent and get a reference |
887 | * if found. This function may sleep. |
888 | * |
889 | * Return: pointer to the found kernfs_node on success, %NULL on failure. |
890 | */ |
891 | struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, |
892 | const char *name, const void *ns) |
893 | { |
894 | struct kernfs_node *kn; |
895 | struct kernfs_root *root = kernfs_root(kn: parent); |
896 | |
897 | down_read(sem: &root->kernfs_rwsem); |
898 | kn = kernfs_find_ns(parent, name, ns); |
899 | kernfs_get(kn); |
900 | up_read(sem: &root->kernfs_rwsem); |
901 | |
902 | return kn; |
903 | } |
904 | EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); |
905 | |
906 | /** |
907 | * kernfs_walk_and_get_ns - find and get kernfs_node with the given path |
908 | * @parent: kernfs_node to search under |
909 | * @path: path to look for |
910 | * @ns: the namespace tag to use |
911 | * |
912 | * Look for kernfs_node with path @path under @parent and get a reference |
913 | * if found. This function may sleep. |
914 | * |
915 | * Return: pointer to the found kernfs_node on success, %NULL on failure. |
916 | */ |
917 | struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent, |
918 | const char *path, const void *ns) |
919 | { |
920 | struct kernfs_node *kn; |
921 | struct kernfs_root *root = kernfs_root(kn: parent); |
922 | |
923 | down_read(sem: &root->kernfs_rwsem); |
924 | kn = kernfs_walk_ns(parent, path, ns); |
925 | kernfs_get(kn); |
926 | up_read(sem: &root->kernfs_rwsem); |
927 | |
928 | return kn; |
929 | } |
930 | |
931 | /** |
932 | * kernfs_create_root - create a new kernfs hierarchy |
933 | * @scops: optional syscall operations for the hierarchy |
934 | * @flags: KERNFS_ROOT_* flags |
935 | * @priv: opaque data associated with the new directory |
936 | * |
937 | * Return: the root of the new hierarchy on success, ERR_PTR() value on |
938 | * failure. |
939 | */ |
940 | struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, |
941 | unsigned int flags, void *priv) |
942 | { |
943 | struct kernfs_root *root; |
944 | struct kernfs_node *kn; |
945 | |
946 | root = kzalloc(size: sizeof(*root), GFP_KERNEL); |
947 | if (!root) |
948 | return ERR_PTR(error: -ENOMEM); |
949 | |
950 | idr_init(idr: &root->ino_idr); |
951 | init_rwsem(&root->kernfs_rwsem); |
952 | init_rwsem(&root->kernfs_iattr_rwsem); |
953 | init_rwsem(&root->kernfs_supers_rwsem); |
954 | INIT_LIST_HEAD(list: &root->supers); |
955 | |
956 | /* |
957 | * On 64bit ino setups, id is ino. On 32bit, low 32bits are ino. |
958 | * High bits generation. The starting value for both ino and |
959 | * genenration is 1. Initialize upper 32bit allocation |
960 | * accordingly. |
961 | */ |
962 | if (sizeof(ino_t) >= sizeof(u64)) |
963 | root->id_highbits = 0; |
964 | else |
965 | root->id_highbits = 1; |
966 | |
967 | kn = __kernfs_new_node(root, NULL, name: "" , S_IFDIR | S_IRUGO | S_IXUGO, |
968 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
969 | flags: KERNFS_DIR); |
970 | if (!kn) { |
971 | idr_destroy(&root->ino_idr); |
972 | kfree(root); |
973 | return ERR_PTR(-ENOMEM); |
974 | } |
975 | |
976 | kn->priv = priv; |
977 | kn->dir.root = root; |
978 | |
979 | root->syscall_ops = scops; |
980 | root->flags = flags; |
981 | root->kn = kn; |
982 | init_waitqueue_head(&root->deactivate_waitq); |
983 | |
984 | if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
985 | kernfs_activate(kn); |
986 | |
987 | return root; |
988 | } |
989 | |
990 | /** |
991 | * kernfs_destroy_root - destroy a kernfs hierarchy |
992 | * @root: root of the hierarchy to destroy |
993 | * |
994 | * Destroy the hierarchy anchored at @root by removing all existing |
995 | * directories and destroying @root. |
996 | */ |
997 | void kernfs_destroy_root(struct kernfs_root *root) |
998 | { |
999 | /* |
1000 | * kernfs_remove holds kernfs_rwsem from the root so the root |
1001 | * shouldn't be freed during the operation. |
1002 | */ |
1003 | kernfs_get(root->kn); |
1004 | kernfs_remove(kn: root->kn); |
1005 | kernfs_put(root->kn); /* will also free @root */ |
1006 | } |
1007 | |
1008 | /** |
1009 | * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root |
1010 | * @root: root to use to lookup |
1011 | * |
1012 | * Return: @root's kernfs_node |
1013 | */ |
1014 | struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root) |
1015 | { |
1016 | return root->kn; |
1017 | } |
1018 | |
1019 | /** |
1020 | * kernfs_create_dir_ns - create a directory |
1021 | * @parent: parent in which to create a new directory |
1022 | * @name: name of the new directory |
1023 | * @mode: mode of the new directory |
1024 | * @uid: uid of the new directory |
1025 | * @gid: gid of the new directory |
1026 | * @priv: opaque data associated with the new directory |
1027 | * @ns: optional namespace tag of the directory |
1028 | * |
1029 | * Return: the created node on success, ERR_PTR() value on failure. |
1030 | */ |
1031 | struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, |
1032 | const char *name, umode_t mode, |
1033 | kuid_t uid, kgid_t gid, |
1034 | void *priv, const void *ns) |
1035 | { |
1036 | struct kernfs_node *kn; |
1037 | int rc; |
1038 | |
1039 | /* allocate */ |
1040 | kn = kernfs_new_node(parent, name, mode: mode | S_IFDIR, |
1041 | uid, gid, flags: KERNFS_DIR); |
1042 | if (!kn) |
1043 | return ERR_PTR(error: -ENOMEM); |
1044 | |
1045 | kn->dir.root = parent->dir.root; |
1046 | kn->ns = ns; |
1047 | kn->priv = priv; |
1048 | |
1049 | /* link in */ |
1050 | rc = kernfs_add_one(kn); |
1051 | if (!rc) |
1052 | return kn; |
1053 | |
1054 | kernfs_put(kn); |
1055 | return ERR_PTR(error: rc); |
1056 | } |
1057 | |
1058 | /** |
1059 | * kernfs_create_empty_dir - create an always empty directory |
1060 | * @parent: parent in which to create a new directory |
1061 | * @name: name of the new directory |
1062 | * |
1063 | * Return: the created node on success, ERR_PTR() value on failure. |
1064 | */ |
1065 | struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent, |
1066 | const char *name) |
1067 | { |
1068 | struct kernfs_node *kn; |
1069 | int rc; |
1070 | |
1071 | /* allocate */ |
1072 | kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR, |
1073 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, flags: KERNFS_DIR); |
1074 | if (!kn) |
1075 | return ERR_PTR(-ENOMEM); |
1076 | |
1077 | kn->flags |= KERNFS_EMPTY_DIR; |
1078 | kn->dir.root = parent->dir.root; |
1079 | kn->ns = NULL; |
1080 | kn->priv = NULL; |
1081 | |
1082 | /* link in */ |
1083 | rc = kernfs_add_one(kn); |
1084 | if (!rc) |
1085 | return kn; |
1086 | |
1087 | kernfs_put(kn); |
1088 | return ERR_PTR(rc); |
1089 | } |
1090 | |
1091 | static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) |
1092 | { |
1093 | struct kernfs_node *kn; |
1094 | struct kernfs_root *root; |
1095 | |
1096 | if (flags & LOOKUP_RCU) |
1097 | return -ECHILD; |
1098 | |
1099 | /* Negative hashed dentry? */ |
1100 | if (d_really_is_negative(dentry)) { |
1101 | struct kernfs_node *parent; |
1102 | |
1103 | /* If the kernfs parent node has changed discard and |
1104 | * proceed to ->lookup. |
1105 | * |
1106 | * There's nothing special needed here when getting the |
1107 | * dentry parent, even if a concurrent rename is in |
1108 | * progress. That's because the dentry is negative so |
1109 | * it can only be the target of the rename and it will |
1110 | * be doing a d_move() not a replace. Consequently the |
1111 | * dentry d_parent won't change over the d_move(). |
1112 | * |
1113 | * Also kernfs negative dentries transitioning from |
1114 | * negative to positive during revalidate won't happen |
1115 | * because they are invalidated on containing directory |
1116 | * changes and the lookup re-done so that a new positive |
1117 | * dentry can be properly created. |
1118 | */ |
1119 | root = kernfs_root_from_sb(sb: dentry->d_sb); |
1120 | down_read(sem: &root->kernfs_rwsem); |
1121 | parent = kernfs_dentry_node(dentry: dentry->d_parent); |
1122 | if (parent) { |
1123 | if (kernfs_dir_changed(parent, dentry)) { |
1124 | up_read(sem: &root->kernfs_rwsem); |
1125 | return 0; |
1126 | } |
1127 | } |
1128 | up_read(sem: &root->kernfs_rwsem); |
1129 | |
1130 | /* The kernfs parent node hasn't changed, leave the |
1131 | * dentry negative and return success. |
1132 | */ |
1133 | return 1; |
1134 | } |
1135 | |
1136 | kn = kernfs_dentry_node(dentry); |
1137 | root = kernfs_root(kn); |
1138 | down_read(sem: &root->kernfs_rwsem); |
1139 | |
1140 | /* The kernfs node has been deactivated */ |
1141 | if (!kernfs_active(kn)) |
1142 | goto out_bad; |
1143 | |
1144 | /* The kernfs node has been moved? */ |
1145 | if (kernfs_dentry_node(dentry: dentry->d_parent) != kn->parent) |
1146 | goto out_bad; |
1147 | |
1148 | /* The kernfs node has been renamed */ |
1149 | if (strcmp(dentry->d_name.name, kn->name) != 0) |
1150 | goto out_bad; |
1151 | |
1152 | /* The kernfs node has been moved to a different namespace */ |
1153 | if (kn->parent && kernfs_ns_enabled(kn: kn->parent) && |
1154 | kernfs_info(dentry->d_sb)->ns != kn->ns) |
1155 | goto out_bad; |
1156 | |
1157 | up_read(sem: &root->kernfs_rwsem); |
1158 | return 1; |
1159 | out_bad: |
1160 | up_read(sem: &root->kernfs_rwsem); |
1161 | return 0; |
1162 | } |
1163 | |
1164 | const struct dentry_operations kernfs_dops = { |
1165 | .d_revalidate = kernfs_dop_revalidate, |
1166 | }; |
1167 | |
1168 | static struct dentry *kernfs_iop_lookup(struct inode *dir, |
1169 | struct dentry *dentry, |
1170 | unsigned int flags) |
1171 | { |
1172 | struct kernfs_node *parent = dir->i_private; |
1173 | struct kernfs_node *kn; |
1174 | struct kernfs_root *root; |
1175 | struct inode *inode = NULL; |
1176 | const void *ns = NULL; |
1177 | |
1178 | root = kernfs_root(kn: parent); |
1179 | down_read(sem: &root->kernfs_rwsem); |
1180 | if (kernfs_ns_enabled(kn: parent)) |
1181 | ns = kernfs_info(dir->i_sb)->ns; |
1182 | |
1183 | kn = kernfs_find_ns(parent, name: dentry->d_name.name, ns); |
1184 | /* attach dentry and inode */ |
1185 | if (kn) { |
1186 | /* Inactive nodes are invisible to the VFS so don't |
1187 | * create a negative. |
1188 | */ |
1189 | if (!kernfs_active(kn)) { |
1190 | up_read(sem: &root->kernfs_rwsem); |
1191 | return NULL; |
1192 | } |
1193 | inode = kernfs_get_inode(sb: dir->i_sb, kn); |
1194 | if (!inode) |
1195 | inode = ERR_PTR(error: -ENOMEM); |
1196 | } |
1197 | /* |
1198 | * Needed for negative dentry validation. |
1199 | * The negative dentry can be created in kernfs_iop_lookup() |
1200 | * or transforms from positive dentry in dentry_unlink_inode() |
1201 | * called from vfs_rmdir(). |
1202 | */ |
1203 | if (!IS_ERR(ptr: inode)) |
1204 | kernfs_set_rev(parent, dentry); |
1205 | up_read(sem: &root->kernfs_rwsem); |
1206 | |
1207 | /* instantiate and hash (possibly negative) dentry */ |
1208 | return d_splice_alias(inode, dentry); |
1209 | } |
1210 | |
1211 | static int kernfs_iop_mkdir(struct mnt_idmap *idmap, |
1212 | struct inode *dir, struct dentry *dentry, |
1213 | umode_t mode) |
1214 | { |
1215 | struct kernfs_node *parent = dir->i_private; |
1216 | struct kernfs_syscall_ops *scops = kernfs_root(kn: parent)->syscall_ops; |
1217 | int ret; |
1218 | |
1219 | if (!scops || !scops->mkdir) |
1220 | return -EPERM; |
1221 | |
1222 | if (!kernfs_get_active(kn: parent)) |
1223 | return -ENODEV; |
1224 | |
1225 | ret = scops->mkdir(parent, dentry->d_name.name, mode); |
1226 | |
1227 | kernfs_put_active(kn: parent); |
1228 | return ret; |
1229 | } |
1230 | |
1231 | static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) |
1232 | { |
1233 | struct kernfs_node *kn = kernfs_dentry_node(dentry); |
1234 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
1235 | int ret; |
1236 | |
1237 | if (!scops || !scops->rmdir) |
1238 | return -EPERM; |
1239 | |
1240 | if (!kernfs_get_active(kn)) |
1241 | return -ENODEV; |
1242 | |
1243 | ret = scops->rmdir(kn); |
1244 | |
1245 | kernfs_put_active(kn); |
1246 | return ret; |
1247 | } |
1248 | |
1249 | static int kernfs_iop_rename(struct mnt_idmap *idmap, |
1250 | struct inode *old_dir, struct dentry *old_dentry, |
1251 | struct inode *new_dir, struct dentry *new_dentry, |
1252 | unsigned int flags) |
1253 | { |
1254 | struct kernfs_node *kn = kernfs_dentry_node(dentry: old_dentry); |
1255 | struct kernfs_node *new_parent = new_dir->i_private; |
1256 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
1257 | int ret; |
1258 | |
1259 | if (flags) |
1260 | return -EINVAL; |
1261 | |
1262 | if (!scops || !scops->rename) |
1263 | return -EPERM; |
1264 | |
1265 | if (!kernfs_get_active(kn)) |
1266 | return -ENODEV; |
1267 | |
1268 | if (!kernfs_get_active(kn: new_parent)) { |
1269 | kernfs_put_active(kn); |
1270 | return -ENODEV; |
1271 | } |
1272 | |
1273 | ret = scops->rename(kn, new_parent, new_dentry->d_name.name); |
1274 | |
1275 | kernfs_put_active(kn: new_parent); |
1276 | kernfs_put_active(kn); |
1277 | return ret; |
1278 | } |
1279 | |
1280 | const struct inode_operations kernfs_dir_iops = { |
1281 | .lookup = kernfs_iop_lookup, |
1282 | .permission = kernfs_iop_permission, |
1283 | .setattr = kernfs_iop_setattr, |
1284 | .getattr = kernfs_iop_getattr, |
1285 | .listxattr = kernfs_iop_listxattr, |
1286 | |
1287 | .mkdir = kernfs_iop_mkdir, |
1288 | .rmdir = kernfs_iop_rmdir, |
1289 | .rename = kernfs_iop_rename, |
1290 | }; |
1291 | |
1292 | static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos) |
1293 | { |
1294 | struct kernfs_node *last; |
1295 | |
1296 | while (true) { |
1297 | struct rb_node *rbn; |
1298 | |
1299 | last = pos; |
1300 | |
1301 | if (kernfs_type(kn: pos) != KERNFS_DIR) |
1302 | break; |
1303 | |
1304 | rbn = rb_first(&pos->dir.children); |
1305 | if (!rbn) |
1306 | break; |
1307 | |
1308 | pos = rb_to_kn(rbn); |
1309 | } |
1310 | |
1311 | return last; |
1312 | } |
1313 | |
1314 | /** |
1315 | * kernfs_next_descendant_post - find the next descendant for post-order walk |
1316 | * @pos: the current position (%NULL to initiate traversal) |
1317 | * @root: kernfs_node whose descendants to walk |
1318 | * |
1319 | * Find the next descendant to visit for post-order traversal of @root's |
1320 | * descendants. @root is included in the iteration and the last node to be |
1321 | * visited. |
1322 | * |
1323 | * Return: the next descendant to visit or %NULL when done. |
1324 | */ |
1325 | static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, |
1326 | struct kernfs_node *root) |
1327 | { |
1328 | struct rb_node *rbn; |
1329 | |
1330 | lockdep_assert_held_write(&kernfs_root(root)->kernfs_rwsem); |
1331 | |
1332 | /* if first iteration, visit leftmost descendant which may be root */ |
1333 | if (!pos) |
1334 | return kernfs_leftmost_descendant(pos: root); |
1335 | |
1336 | /* if we visited @root, we're done */ |
1337 | if (pos == root) |
1338 | return NULL; |
1339 | |
1340 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
1341 | rbn = rb_next(&pos->rb); |
1342 | if (rbn) |
1343 | return kernfs_leftmost_descendant(rb_to_kn(rbn)); |
1344 | |
1345 | /* no sibling left, visit parent */ |
1346 | return pos->parent; |
1347 | } |
1348 | |
1349 | static void kernfs_activate_one(struct kernfs_node *kn) |
1350 | { |
1351 | lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); |
1352 | |
1353 | kn->flags |= KERNFS_ACTIVATED; |
1354 | |
1355 | if (kernfs_active(kn) || (kn->flags & (KERNFS_HIDDEN | KERNFS_REMOVING))) |
1356 | return; |
1357 | |
1358 | WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb)); |
1359 | WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); |
1360 | |
1361 | atomic_sub(KN_DEACTIVATED_BIAS, v: &kn->active); |
1362 | } |
1363 | |
1364 | /** |
1365 | * kernfs_activate - activate a node which started deactivated |
1366 | * @kn: kernfs_node whose subtree is to be activated |
1367 | * |
1368 | * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node |
1369 | * needs to be explicitly activated. A node which hasn't been activated |
1370 | * isn't visible to userland and deactivation is skipped during its |
1371 | * removal. This is useful to construct atomic init sequences where |
1372 | * creation of multiple nodes should either succeed or fail atomically. |
1373 | * |
1374 | * The caller is responsible for ensuring that this function is not called |
1375 | * after kernfs_remove*() is invoked on @kn. |
1376 | */ |
1377 | void kernfs_activate(struct kernfs_node *kn) |
1378 | { |
1379 | struct kernfs_node *pos; |
1380 | struct kernfs_root *root = kernfs_root(kn); |
1381 | |
1382 | down_write(sem: &root->kernfs_rwsem); |
1383 | |
1384 | pos = NULL; |
1385 | while ((pos = kernfs_next_descendant_post(pos, root: kn))) |
1386 | kernfs_activate_one(kn: pos); |
1387 | |
1388 | up_write(sem: &root->kernfs_rwsem); |
1389 | } |
1390 | |
1391 | /** |
1392 | * kernfs_show - show or hide a node |
1393 | * @kn: kernfs_node to show or hide |
1394 | * @show: whether to show or hide |
1395 | * |
1396 | * If @show is %false, @kn is marked hidden and deactivated. A hidden node is |
1397 | * ignored in future activaitons. If %true, the mark is removed and activation |
1398 | * state is restored. This function won't implicitly activate a new node in a |
1399 | * %KERNFS_ROOT_CREATE_DEACTIVATED root which hasn't been activated yet. |
1400 | * |
1401 | * To avoid recursion complexities, directories aren't supported for now. |
1402 | */ |
1403 | void kernfs_show(struct kernfs_node *kn, bool show) |
1404 | { |
1405 | struct kernfs_root *root = kernfs_root(kn); |
1406 | |
1407 | if (WARN_ON_ONCE(kernfs_type(kn) == KERNFS_DIR)) |
1408 | return; |
1409 | |
1410 | down_write(sem: &root->kernfs_rwsem); |
1411 | |
1412 | if (show) { |
1413 | kn->flags &= ~KERNFS_HIDDEN; |
1414 | if (kn->flags & KERNFS_ACTIVATED) |
1415 | kernfs_activate_one(kn); |
1416 | } else { |
1417 | kn->flags |= KERNFS_HIDDEN; |
1418 | if (kernfs_active(kn)) |
1419 | atomic_add(KN_DEACTIVATED_BIAS, v: &kn->active); |
1420 | kernfs_drain(kn); |
1421 | } |
1422 | |
1423 | up_write(sem: &root->kernfs_rwsem); |
1424 | } |
1425 | |
1426 | static void __kernfs_remove(struct kernfs_node *kn) |
1427 | { |
1428 | struct kernfs_node *pos; |
1429 | |
1430 | /* Short-circuit if non-root @kn has already finished removal. */ |
1431 | if (!kn) |
1432 | return; |
1433 | |
1434 | lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); |
1435 | |
1436 | /* |
1437 | * This is for kernfs_remove_self() which plays with active ref |
1438 | * after removal. |
1439 | */ |
1440 | if (kn->parent && RB_EMPTY_NODE(&kn->rb)) |
1441 | return; |
1442 | |
1443 | pr_debug("kernfs %s: removing\n" , kn->name); |
1444 | |
1445 | /* prevent new usage by marking all nodes removing and deactivating */ |
1446 | pos = NULL; |
1447 | while ((pos = kernfs_next_descendant_post(pos, root: kn))) { |
1448 | pos->flags |= KERNFS_REMOVING; |
1449 | if (kernfs_active(kn: pos)) |
1450 | atomic_add(KN_DEACTIVATED_BIAS, v: &pos->active); |
1451 | } |
1452 | |
1453 | /* deactivate and unlink the subtree node-by-node */ |
1454 | do { |
1455 | pos = kernfs_leftmost_descendant(pos: kn); |
1456 | |
1457 | /* |
1458 | * kernfs_drain() may drop kernfs_rwsem temporarily and @pos's |
1459 | * base ref could have been put by someone else by the time |
1460 | * the function returns. Make sure it doesn't go away |
1461 | * underneath us. |
1462 | */ |
1463 | kernfs_get(pos); |
1464 | |
1465 | kernfs_drain(kn: pos); |
1466 | |
1467 | /* |
1468 | * kernfs_unlink_sibling() succeeds once per node. Use it |
1469 | * to decide who's responsible for cleanups. |
1470 | */ |
1471 | if (!pos->parent || kernfs_unlink_sibling(kn: pos)) { |
1472 | struct kernfs_iattrs *ps_iattr = |
1473 | pos->parent ? pos->parent->iattr : NULL; |
1474 | |
1475 | /* update timestamps on the parent */ |
1476 | down_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
1477 | |
1478 | if (ps_iattr) { |
1479 | ktime_get_real_ts64(tv: &ps_iattr->ia_ctime); |
1480 | ps_iattr->ia_mtime = ps_iattr->ia_ctime; |
1481 | } |
1482 | |
1483 | up_write(sem: &kernfs_root(kn)->kernfs_iattr_rwsem); |
1484 | kernfs_put(pos); |
1485 | } |
1486 | |
1487 | kernfs_put(pos); |
1488 | } while (pos != kn); |
1489 | } |
1490 | |
1491 | /** |
1492 | * kernfs_remove - remove a kernfs_node recursively |
1493 | * @kn: the kernfs_node to remove |
1494 | * |
1495 | * Remove @kn along with all its subdirectories and files. |
1496 | */ |
1497 | void kernfs_remove(struct kernfs_node *kn) |
1498 | { |
1499 | struct kernfs_root *root; |
1500 | |
1501 | if (!kn) |
1502 | return; |
1503 | |
1504 | root = kernfs_root(kn); |
1505 | |
1506 | down_write(sem: &root->kernfs_rwsem); |
1507 | __kernfs_remove(kn); |
1508 | up_write(sem: &root->kernfs_rwsem); |
1509 | } |
1510 | |
1511 | /** |
1512 | * kernfs_break_active_protection - break out of active protection |
1513 | * @kn: the self kernfs_node |
1514 | * |
1515 | * The caller must be running off of a kernfs operation which is invoked |
1516 | * with an active reference - e.g. one of kernfs_ops. Each invocation of |
1517 | * this function must also be matched with an invocation of |
1518 | * kernfs_unbreak_active_protection(). |
1519 | * |
1520 | * This function releases the active reference of @kn the caller is |
1521 | * holding. Once this function is called, @kn may be removed at any point |
1522 | * and the caller is solely responsible for ensuring that the objects it |
1523 | * dereferences are accessible. |
1524 | */ |
1525 | void kernfs_break_active_protection(struct kernfs_node *kn) |
1526 | { |
1527 | /* |
1528 | * Take out ourself out of the active ref dependency chain. If |
1529 | * we're called without an active ref, lockdep will complain. |
1530 | */ |
1531 | kernfs_put_active(kn); |
1532 | } |
1533 | |
1534 | /** |
1535 | * kernfs_unbreak_active_protection - undo kernfs_break_active_protection() |
1536 | * @kn: the self kernfs_node |
1537 | * |
1538 | * If kernfs_break_active_protection() was called, this function must be |
1539 | * invoked before finishing the kernfs operation. Note that while this |
1540 | * function restores the active reference, it doesn't and can't actually |
1541 | * restore the active protection - @kn may already or be in the process of |
1542 | * being removed. Once kernfs_break_active_protection() is invoked, that |
1543 | * protection is irreversibly gone for the kernfs operation instance. |
1544 | * |
1545 | * While this function may be called at any point after |
1546 | * kernfs_break_active_protection() is invoked, its most useful location |
1547 | * would be right before the enclosing kernfs operation returns. |
1548 | */ |
1549 | void kernfs_unbreak_active_protection(struct kernfs_node *kn) |
1550 | { |
1551 | /* |
1552 | * @kn->active could be in any state; however, the increment we do |
1553 | * here will be undone as soon as the enclosing kernfs operation |
1554 | * finishes and this temporary bump can't break anything. If @kn |
1555 | * is alive, nothing changes. If @kn is being deactivated, the |
1556 | * soon-to-follow put will either finish deactivation or restore |
1557 | * deactivated state. If @kn is already removed, the temporary |
1558 | * bump is guaranteed to be gone before @kn is released. |
1559 | */ |
1560 | atomic_inc(v: &kn->active); |
1561 | if (kernfs_lockdep(kn)) |
1562 | rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_); |
1563 | } |
1564 | |
1565 | /** |
1566 | * kernfs_remove_self - remove a kernfs_node from its own method |
1567 | * @kn: the self kernfs_node to remove |
1568 | * |
1569 | * The caller must be running off of a kernfs operation which is invoked |
1570 | * with an active reference - e.g. one of kernfs_ops. This can be used to |
1571 | * implement a file operation which deletes itself. |
1572 | * |
1573 | * For example, the "delete" file for a sysfs device directory can be |
1574 | * implemented by invoking kernfs_remove_self() on the "delete" file |
1575 | * itself. This function breaks the circular dependency of trying to |
1576 | * deactivate self while holding an active ref itself. It isn't necessary |
1577 | * to modify the usual removal path to use kernfs_remove_self(). The |
1578 | * "delete" implementation can simply invoke kernfs_remove_self() on self |
1579 | * before proceeding with the usual removal path. kernfs will ignore later |
1580 | * kernfs_remove() on self. |
1581 | * |
1582 | * kernfs_remove_self() can be called multiple times concurrently on the |
1583 | * same kernfs_node. Only the first one actually performs removal and |
1584 | * returns %true. All others will wait until the kernfs operation which |
1585 | * won self-removal finishes and return %false. Note that the losers wait |
1586 | * for the completion of not only the winning kernfs_remove_self() but also |
1587 | * the whole kernfs_ops which won the arbitration. This can be used to |
1588 | * guarantee, for example, all concurrent writes to a "delete" file to |
1589 | * finish only after the whole operation is complete. |
1590 | * |
1591 | * Return: %true if @kn is removed by this call, otherwise %false. |
1592 | */ |
1593 | bool kernfs_remove_self(struct kernfs_node *kn) |
1594 | { |
1595 | bool ret; |
1596 | struct kernfs_root *root = kernfs_root(kn); |
1597 | |
1598 | down_write(sem: &root->kernfs_rwsem); |
1599 | kernfs_break_active_protection(kn); |
1600 | |
1601 | /* |
1602 | * SUICIDAL is used to arbitrate among competing invocations. Only |
1603 | * the first one will actually perform removal. When the removal |
1604 | * is complete, SUICIDED is set and the active ref is restored |
1605 | * while kernfs_rwsem for held exclusive. The ones which lost |
1606 | * arbitration waits for SUICIDED && drained which can happen only |
1607 | * after the enclosing kernfs operation which executed the winning |
1608 | * instance of kernfs_remove_self() finished. |
1609 | */ |
1610 | if (!(kn->flags & KERNFS_SUICIDAL)) { |
1611 | kn->flags |= KERNFS_SUICIDAL; |
1612 | __kernfs_remove(kn); |
1613 | kn->flags |= KERNFS_SUICIDED; |
1614 | ret = true; |
1615 | } else { |
1616 | wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq; |
1617 | DEFINE_WAIT(wait); |
1618 | |
1619 | while (true) { |
1620 | prepare_to_wait(wq_head: waitq, wq_entry: &wait, TASK_UNINTERRUPTIBLE); |
1621 | |
1622 | if ((kn->flags & KERNFS_SUICIDED) && |
1623 | atomic_read(v: &kn->active) == KN_DEACTIVATED_BIAS) |
1624 | break; |
1625 | |
1626 | up_write(sem: &root->kernfs_rwsem); |
1627 | schedule(); |
1628 | down_write(sem: &root->kernfs_rwsem); |
1629 | } |
1630 | finish_wait(wq_head: waitq, wq_entry: &wait); |
1631 | WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb)); |
1632 | ret = false; |
1633 | } |
1634 | |
1635 | /* |
1636 | * This must be done while kernfs_rwsem held exclusive; otherwise, |
1637 | * waiting for SUICIDED && deactivated could finish prematurely. |
1638 | */ |
1639 | kernfs_unbreak_active_protection(kn); |
1640 | |
1641 | up_write(sem: &root->kernfs_rwsem); |
1642 | return ret; |
1643 | } |
1644 | |
1645 | /** |
1646 | * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it |
1647 | * @parent: parent of the target |
1648 | * @name: name of the kernfs_node to remove |
1649 | * @ns: namespace tag of the kernfs_node to remove |
1650 | * |
1651 | * Look for the kernfs_node with @name and @ns under @parent and remove it. |
1652 | * |
1653 | * Return: %0 on success, -ENOENT if such entry doesn't exist. |
1654 | */ |
1655 | int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, |
1656 | const void *ns) |
1657 | { |
1658 | struct kernfs_node *kn; |
1659 | struct kernfs_root *root; |
1660 | |
1661 | if (!parent) { |
1662 | WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n" , |
1663 | name); |
1664 | return -ENOENT; |
1665 | } |
1666 | |
1667 | root = kernfs_root(kn: parent); |
1668 | down_write(sem: &root->kernfs_rwsem); |
1669 | |
1670 | kn = kernfs_find_ns(parent, name, ns); |
1671 | if (kn) { |
1672 | kernfs_get(kn); |
1673 | __kernfs_remove(kn); |
1674 | kernfs_put(kn); |
1675 | } |
1676 | |
1677 | up_write(sem: &root->kernfs_rwsem); |
1678 | |
1679 | if (kn) |
1680 | return 0; |
1681 | else |
1682 | return -ENOENT; |
1683 | } |
1684 | |
1685 | /** |
1686 | * kernfs_rename_ns - move and rename a kernfs_node |
1687 | * @kn: target node |
1688 | * @new_parent: new parent to put @sd under |
1689 | * @new_name: new name |
1690 | * @new_ns: new namespace tag |
1691 | * |
1692 | * Return: %0 on success, -errno on failure. |
1693 | */ |
1694 | int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, |
1695 | const char *new_name, const void *new_ns) |
1696 | { |
1697 | struct kernfs_node *old_parent; |
1698 | struct kernfs_root *root; |
1699 | const char *old_name = NULL; |
1700 | int error; |
1701 | |
1702 | /* can't move or rename root */ |
1703 | if (!kn->parent) |
1704 | return -EINVAL; |
1705 | |
1706 | root = kernfs_root(kn); |
1707 | down_write(sem: &root->kernfs_rwsem); |
1708 | |
1709 | error = -ENOENT; |
1710 | if (!kernfs_active(kn) || !kernfs_active(kn: new_parent) || |
1711 | (new_parent->flags & KERNFS_EMPTY_DIR)) |
1712 | goto out; |
1713 | |
1714 | error = 0; |
1715 | if ((kn->parent == new_parent) && (kn->ns == new_ns) && |
1716 | (strcmp(kn->name, new_name) == 0)) |
1717 | goto out; /* nothing to rename */ |
1718 | |
1719 | error = -EEXIST; |
1720 | if (kernfs_find_ns(parent: new_parent, name: new_name, ns: new_ns)) |
1721 | goto out; |
1722 | |
1723 | /* rename kernfs_node */ |
1724 | if (strcmp(kn->name, new_name) != 0) { |
1725 | error = -ENOMEM; |
1726 | new_name = kstrdup_const(s: new_name, GFP_KERNEL); |
1727 | if (!new_name) |
1728 | goto out; |
1729 | } else { |
1730 | new_name = NULL; |
1731 | } |
1732 | |
1733 | /* |
1734 | * Move to the appropriate place in the appropriate directories rbtree. |
1735 | */ |
1736 | kernfs_unlink_sibling(kn); |
1737 | kernfs_get(new_parent); |
1738 | |
1739 | /* rename_lock protects ->parent and ->name accessors */ |
1740 | write_lock_irq(&kernfs_rename_lock); |
1741 | |
1742 | old_parent = kn->parent; |
1743 | kn->parent = new_parent; |
1744 | |
1745 | kn->ns = new_ns; |
1746 | if (new_name) { |
1747 | old_name = kn->name; |
1748 | kn->name = new_name; |
1749 | } |
1750 | |
1751 | write_unlock_irq(&kernfs_rename_lock); |
1752 | |
1753 | kn->hash = kernfs_name_hash(name: kn->name, ns: kn->ns); |
1754 | kernfs_link_sibling(kn); |
1755 | |
1756 | kernfs_put(old_parent); |
1757 | kfree_const(x: old_name); |
1758 | |
1759 | error = 0; |
1760 | out: |
1761 | up_write(sem: &root->kernfs_rwsem); |
1762 | return error; |
1763 | } |
1764 | |
1765 | static int kernfs_dir_fop_release(struct inode *inode, struct file *filp) |
1766 | { |
1767 | kernfs_put(filp->private_data); |
1768 | return 0; |
1769 | } |
1770 | |
1771 | static struct kernfs_node *kernfs_dir_pos(const void *ns, |
1772 | struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) |
1773 | { |
1774 | if (pos) { |
1775 | int valid = kernfs_active(kn: pos) && |
1776 | pos->parent == parent && hash == pos->hash; |
1777 | kernfs_put(pos); |
1778 | if (!valid) |
1779 | pos = NULL; |
1780 | } |
1781 | if (!pos && (hash > 1) && (hash < INT_MAX)) { |
1782 | struct rb_node *node = parent->dir.children.rb_node; |
1783 | while (node) { |
1784 | pos = rb_to_kn(node); |
1785 | |
1786 | if (hash < pos->hash) |
1787 | node = node->rb_left; |
1788 | else if (hash > pos->hash) |
1789 | node = node->rb_right; |
1790 | else |
1791 | break; |
1792 | } |
1793 | } |
1794 | /* Skip over entries which are dying/dead or in the wrong namespace */ |
1795 | while (pos && (!kernfs_active(kn: pos) || pos->ns != ns)) { |
1796 | struct rb_node *node = rb_next(&pos->rb); |
1797 | if (!node) |
1798 | pos = NULL; |
1799 | else |
1800 | pos = rb_to_kn(node); |
1801 | } |
1802 | return pos; |
1803 | } |
1804 | |
1805 | static struct kernfs_node *kernfs_dir_next_pos(const void *ns, |
1806 | struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos) |
1807 | { |
1808 | pos = kernfs_dir_pos(ns, parent, hash: ino, pos); |
1809 | if (pos) { |
1810 | do { |
1811 | struct rb_node *node = rb_next(&pos->rb); |
1812 | if (!node) |
1813 | pos = NULL; |
1814 | else |
1815 | pos = rb_to_kn(node); |
1816 | } while (pos && (!kernfs_active(kn: pos) || pos->ns != ns)); |
1817 | } |
1818 | return pos; |
1819 | } |
1820 | |
1821 | static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) |
1822 | { |
1823 | struct dentry *dentry = file->f_path.dentry; |
1824 | struct kernfs_node *parent = kernfs_dentry_node(dentry); |
1825 | struct kernfs_node *pos = file->private_data; |
1826 | struct kernfs_root *root; |
1827 | const void *ns = NULL; |
1828 | |
1829 | if (!dir_emit_dots(file, ctx)) |
1830 | return 0; |
1831 | |
1832 | root = kernfs_root(kn: parent); |
1833 | down_read(sem: &root->kernfs_rwsem); |
1834 | |
1835 | if (kernfs_ns_enabled(kn: parent)) |
1836 | ns = kernfs_info(dentry->d_sb)->ns; |
1837 | |
1838 | for (pos = kernfs_dir_pos(ns, parent, hash: ctx->pos, pos); |
1839 | pos; |
1840 | pos = kernfs_dir_next_pos(ns, parent, ino: ctx->pos, pos)) { |
1841 | const char *name = pos->name; |
1842 | unsigned int type = fs_umode_to_dtype(mode: pos->mode); |
1843 | int len = strlen(name); |
1844 | ino_t ino = kernfs_ino(kn: pos); |
1845 | |
1846 | ctx->pos = pos->hash; |
1847 | file->private_data = pos; |
1848 | kernfs_get(pos); |
1849 | |
1850 | up_read(sem: &root->kernfs_rwsem); |
1851 | if (!dir_emit(ctx, name, namelen: len, ino, type)) |
1852 | return 0; |
1853 | down_read(sem: &root->kernfs_rwsem); |
1854 | } |
1855 | up_read(sem: &root->kernfs_rwsem); |
1856 | file->private_data = NULL; |
1857 | ctx->pos = INT_MAX; |
1858 | return 0; |
1859 | } |
1860 | |
1861 | const struct file_operations kernfs_dir_fops = { |
1862 | .read = generic_read_dir, |
1863 | .iterate_shared = kernfs_fop_readdir, |
1864 | .release = kernfs_dir_fop_release, |
1865 | .llseek = generic_file_llseek, |
1866 | }; |
1867 | |