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55716d26 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
b8441ed2 TH |
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> | |
b8441ed2 | 8 | */ |
fd7b9f7b | 9 | |
abd54f02 | 10 | #include <linux/sched.h> |
fd7b9f7b TH |
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 | ||
3eef34ad | 20 | static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ |
1a702dc8 HL |
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 */ | |
7d35079f | 30 | static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ |
fd7b9f7b | 31 | |
adc5e8b5 | 32 | #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) |
fd7b9f7b | 33 | |
81c173cb TH |
34 | static bool kernfs_active(struct kernfs_node *kn) |
35 | { | |
393c3714 | 36 | lockdep_assert_held(&kernfs_root(kn)->kernfs_rwsem); |
81c173cb TH |
37 | return atomic_read(&kn->active) >= 0; |
38 | } | |
39 | ||
182fd64b TH |
40 | static bool kernfs_lockdep(struct kernfs_node *kn) |
41 | { | |
42 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
43 | return kn->flags & KERNFS_LOCKDEP; | |
44 | #else | |
45 | return false; | |
46 | #endif | |
47 | } | |
48 | ||
3eef34ad TH |
49 | static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) |
50 | { | |
17627157 KK |
51 | if (!kn) |
52 | return strlcpy(buf, "(null)", buflen); | |
53 | ||
3eef34ad TH |
54 | return strlcpy(buf, kn->parent ? kn->name : "/", buflen); |
55 | } | |
56 | ||
9f6df573 AK |
57 | /* kernfs_node_depth - compute depth from @from to @to */ |
58 | static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to) | |
3eef34ad | 59 | { |
9f6df573 | 60 | size_t depth = 0; |
3eef34ad | 61 | |
9f6df573 AK |
62 | while (to->parent && to != from) { |
63 | depth++; | |
64 | to = to->parent; | |
65 | } | |
66 | return depth; | |
67 | } | |
3eef34ad | 68 | |
9f6df573 AK |
69 | static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a, |
70 | struct kernfs_node *b) | |
71 | { | |
72 | size_t da, db; | |
73 | struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b); | |
74 | ||
75 | if (ra != rb) | |
76 | return NULL; | |
77 | ||
78 | da = kernfs_depth(ra->kn, a); | |
79 | db = kernfs_depth(rb->kn, b); | |
80 | ||
81 | while (da > db) { | |
82 | a = a->parent; | |
83 | da--; | |
84 | } | |
85 | while (db > da) { | |
86 | b = b->parent; | |
87 | db--; | |
88 | } | |
89 | ||
90 | /* worst case b and a will be the same at root */ | |
91 | while (b != a) { | |
92 | b = b->parent; | |
93 | a = a->parent; | |
94 | } | |
95 | ||
96 | return a; | |
97 | } | |
98 | ||
99 | /** | |
100 | * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to, | |
101 | * where kn_from is treated as root of the path. | |
102 | * @kn_from: kernfs node which should be treated as root for the path | |
103 | * @kn_to: kernfs node to which path is needed | |
104 | * @buf: buffer to copy the path into | |
105 | * @buflen: size of @buf | |
106 | * | |
107 | * We need to handle couple of scenarios here: | |
108 | * [1] when @kn_from is an ancestor of @kn_to at some level | |
109 | * kn_from: /n1/n2/n3 | |
110 | * kn_to: /n1/n2/n3/n4/n5 | |
111 | * result: /n4/n5 | |
112 | * | |
113 | * [2] when @kn_from is on a different hierarchy and we need to find common | |
114 | * ancestor between @kn_from and @kn_to. | |
115 | * kn_from: /n1/n2/n3/n4 | |
116 | * kn_to: /n1/n2/n5 | |
117 | * result: /../../n5 | |
118 | * OR | |
119 | * kn_from: /n1/n2/n3/n4/n5 [depth=5] | |
120 | * kn_to: /n1/n2/n3 [depth=3] | |
121 | * result: /../.. | |
122 | * | |
17627157 KK |
123 | * [3] when @kn_to is NULL result will be "(null)" |
124 | * | |
3abb1d90 TH |
125 | * Returns the length of the full path. If the full length is equal to or |
126 | * greater than @buflen, @buf contains the truncated path with the trailing | |
127 | * '\0'. On error, -errno is returned. | |
9f6df573 AK |
128 | */ |
129 | static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, | |
130 | struct kernfs_node *kn_from, | |
131 | char *buf, size_t buflen) | |
132 | { | |
133 | struct kernfs_node *kn, *common; | |
134 | const char parent_str[] = "/.."; | |
3abb1d90 TH |
135 | size_t depth_from, depth_to, len = 0; |
136 | int i, j; | |
9f6df573 | 137 | |
17627157 KK |
138 | if (!kn_to) |
139 | return strlcpy(buf, "(null)", buflen); | |
140 | ||
9f6df573 AK |
141 | if (!kn_from) |
142 | kn_from = kernfs_root(kn_to)->kn; | |
143 | ||
144 | if (kn_from == kn_to) | |
145 | return strlcpy(buf, "/", buflen); | |
146 | ||
bbe70e4e JJB |
147 | if (!buf) |
148 | return -EINVAL; | |
149 | ||
9f6df573 AK |
150 | common = kernfs_common_ancestor(kn_from, kn_to); |
151 | if (WARN_ON(!common)) | |
3abb1d90 | 152 | return -EINVAL; |
9f6df573 AK |
153 | |
154 | depth_to = kernfs_depth(common, kn_to); | |
155 | depth_from = kernfs_depth(common, kn_from); | |
156 | ||
bbe70e4e | 157 | buf[0] = '\0'; |
9f6df573 AK |
158 | |
159 | for (i = 0; i < depth_from; i++) | |
160 | len += strlcpy(buf + len, parent_str, | |
161 | len < buflen ? buflen - len : 0); | |
162 | ||
163 | /* Calculate how many bytes we need for the rest */ | |
3abb1d90 TH |
164 | for (i = depth_to - 1; i >= 0; i--) { |
165 | for (kn = kn_to, j = 0; j < i; j++) | |
166 | kn = kn->parent; | |
167 | len += strlcpy(buf + len, "/", | |
168 | len < buflen ? buflen - len : 0); | |
169 | len += strlcpy(buf + len, kn->name, | |
170 | len < buflen ? buflen - len : 0); | |
9f6df573 | 171 | } |
3eef34ad | 172 | |
3abb1d90 | 173 | return len; |
3eef34ad TH |
174 | } |
175 | ||
176 | /** | |
177 | * kernfs_name - obtain the name of a given node | |
178 | * @kn: kernfs_node of interest | |
179 | * @buf: buffer to copy @kn's name into | |
180 | * @buflen: size of @buf | |
181 | * | |
182 | * Copies the name of @kn into @buf of @buflen bytes. The behavior is | |
183 | * similar to strlcpy(). It returns the length of @kn's name and if @buf | |
184 | * isn't long enough, it's filled upto @buflen-1 and nul terminated. | |
185 | * | |
17627157 KK |
186 | * Fills buffer with "(null)" if @kn is NULL. |
187 | * | |
3eef34ad TH |
188 | * This function can be called from any context. |
189 | */ | |
190 | int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) | |
191 | { | |
192 | unsigned long flags; | |
193 | int ret; | |
194 | ||
195 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
196 | ret = kernfs_name_locked(kn, buf, buflen); | |
197 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
198 | return ret; | |
199 | } | |
200 | ||
9f6df573 AK |
201 | /** |
202 | * kernfs_path_from_node - build path of node @to relative to @from. | |
203 | * @from: parent kernfs_node relative to which we need to build the path | |
204 | * @to: kernfs_node of interest | |
205 | * @buf: buffer to copy @to's path into | |
206 | * @buflen: size of @buf | |
207 | * | |
208 | * Builds @to's path relative to @from in @buf. @from and @to must | |
209 | * be on the same kernfs-root. If @from is not parent of @to, then a relative | |
210 | * path (which includes '..'s) as needed to reach from @from to @to is | |
211 | * returned. | |
212 | * | |
3abb1d90 TH |
213 | * Returns the length of the full path. If the full length is equal to or |
214 | * greater than @buflen, @buf contains the truncated path with the trailing | |
215 | * '\0'. On error, -errno is returned. | |
9f6df573 AK |
216 | */ |
217 | int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from, | |
218 | char *buf, size_t buflen) | |
219 | { | |
220 | unsigned long flags; | |
221 | int ret; | |
222 | ||
223 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
224 | ret = kernfs_path_from_node_locked(to, from, buf, buflen); | |
225 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
226 | return ret; | |
227 | } | |
228 | EXPORT_SYMBOL_GPL(kernfs_path_from_node); | |
229 | ||
3eef34ad TH |
230 | /** |
231 | * pr_cont_kernfs_name - pr_cont name of a kernfs_node | |
232 | * @kn: kernfs_node of interest | |
233 | * | |
234 | * This function can be called from any context. | |
235 | */ | |
236 | void pr_cont_kernfs_name(struct kernfs_node *kn) | |
237 | { | |
238 | unsigned long flags; | |
239 | ||
1a702dc8 | 240 | spin_lock_irqsave(&kernfs_pr_cont_lock, flags); |
3eef34ad | 241 | |
1a702dc8 | 242 | kernfs_name(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); |
3eef34ad TH |
243 | pr_cont("%s", kernfs_pr_cont_buf); |
244 | ||
1a702dc8 | 245 | spin_unlock_irqrestore(&kernfs_pr_cont_lock, flags); |
3eef34ad TH |
246 | } |
247 | ||
248 | /** | |
249 | * pr_cont_kernfs_path - pr_cont path of a kernfs_node | |
250 | * @kn: kernfs_node of interest | |
251 | * | |
252 | * This function can be called from any context. | |
253 | */ | |
254 | void pr_cont_kernfs_path(struct kernfs_node *kn) | |
255 | { | |
256 | unsigned long flags; | |
9f6df573 | 257 | int sz; |
3eef34ad | 258 | |
1a702dc8 | 259 | spin_lock_irqsave(&kernfs_pr_cont_lock, flags); |
3eef34ad | 260 | |
1a702dc8 HL |
261 | sz = kernfs_path_from_node(kn, NULL, kernfs_pr_cont_buf, |
262 | sizeof(kernfs_pr_cont_buf)); | |
9f6df573 AK |
263 | if (sz < 0) { |
264 | pr_cont("(error)"); | |
265 | goto out; | |
266 | } | |
267 | ||
268 | if (sz >= sizeof(kernfs_pr_cont_buf)) { | |
269 | pr_cont("(name too long)"); | |
270 | goto out; | |
271 | } | |
272 | ||
273 | pr_cont("%s", kernfs_pr_cont_buf); | |
3eef34ad | 274 | |
9f6df573 | 275 | out: |
1a702dc8 | 276 | spin_unlock_irqrestore(&kernfs_pr_cont_lock, flags); |
3eef34ad TH |
277 | } |
278 | ||
279 | /** | |
280 | * kernfs_get_parent - determine the parent node and pin it | |
281 | * @kn: kernfs_node of interest | |
282 | * | |
283 | * Determines @kn's parent, pins and returns it. This function can be | |
284 | * called from any context. | |
285 | */ | |
286 | struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) | |
287 | { | |
288 | struct kernfs_node *parent; | |
289 | unsigned long flags; | |
290 | ||
291 | spin_lock_irqsave(&kernfs_rename_lock, flags); | |
292 | parent = kn->parent; | |
293 | kernfs_get(parent); | |
294 | spin_unlock_irqrestore(&kernfs_rename_lock, flags); | |
295 | ||
296 | return parent; | |
297 | } | |
298 | ||
fd7b9f7b | 299 | /** |
c637b8ac | 300 | * kernfs_name_hash |
fd7b9f7b TH |
301 | * @name: Null terminated string to hash |
302 | * @ns: Namespace tag to hash | |
303 | * | |
304 | * Returns 31 bit hash of ns + name (so it fits in an off_t ) | |
305 | */ | |
c637b8ac | 306 | static unsigned int kernfs_name_hash(const char *name, const void *ns) |
fd7b9f7b | 307 | { |
8387ff25 | 308 | unsigned long hash = init_name_hash(ns); |
fd7b9f7b TH |
309 | unsigned int len = strlen(name); |
310 | while (len--) | |
311 | hash = partial_name_hash(*name++, hash); | |
8387ff25 | 312 | hash = end_name_hash(hash); |
fd7b9f7b TH |
313 | hash &= 0x7fffffffU; |
314 | /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ | |
88391d49 | 315 | if (hash < 2) |
fd7b9f7b TH |
316 | hash += 2; |
317 | if (hash >= INT_MAX) | |
318 | hash = INT_MAX - 1; | |
319 | return hash; | |
320 | } | |
321 | ||
c637b8ac TH |
322 | static int kernfs_name_compare(unsigned int hash, const char *name, |
323 | const void *ns, const struct kernfs_node *kn) | |
fd7b9f7b | 324 | { |
72392ed0 RV |
325 | if (hash < kn->hash) |
326 | return -1; | |
327 | if (hash > kn->hash) | |
328 | return 1; | |
329 | if (ns < kn->ns) | |
330 | return -1; | |
331 | if (ns > kn->ns) | |
332 | return 1; | |
adc5e8b5 | 333 | return strcmp(name, kn->name); |
fd7b9f7b TH |
334 | } |
335 | ||
c637b8ac TH |
336 | static int kernfs_sd_compare(const struct kernfs_node *left, |
337 | const struct kernfs_node *right) | |
fd7b9f7b | 338 | { |
c637b8ac | 339 | return kernfs_name_compare(left->hash, left->name, left->ns, right); |
fd7b9f7b TH |
340 | } |
341 | ||
342 | /** | |
c637b8ac | 343 | * kernfs_link_sibling - link kernfs_node into sibling rbtree |
324a56e1 | 344 | * @kn: kernfs_node of interest |
fd7b9f7b | 345 | * |
324a56e1 | 346 | * Link @kn into its sibling rbtree which starts from |
adc5e8b5 | 347 | * @kn->parent->dir.children. |
fd7b9f7b TH |
348 | * |
349 | * Locking: | |
7ba0273b | 350 | * kernfs_rwsem held exclusive |
fd7b9f7b TH |
351 | * |
352 | * RETURNS: | |
353 | * 0 on susccess -EEXIST on failure. | |
354 | */ | |
c637b8ac | 355 | static int kernfs_link_sibling(struct kernfs_node *kn) |
fd7b9f7b | 356 | { |
adc5e8b5 | 357 | struct rb_node **node = &kn->parent->dir.children.rb_node; |
fd7b9f7b TH |
358 | struct rb_node *parent = NULL; |
359 | ||
fd7b9f7b | 360 | while (*node) { |
324a56e1 | 361 | struct kernfs_node *pos; |
fd7b9f7b TH |
362 | int result; |
363 | ||
324a56e1 | 364 | pos = rb_to_kn(*node); |
fd7b9f7b | 365 | parent = *node; |
c637b8ac | 366 | result = kernfs_sd_compare(kn, pos); |
fd7b9f7b | 367 | if (result < 0) |
adc5e8b5 | 368 | node = &pos->rb.rb_left; |
fd7b9f7b | 369 | else if (result > 0) |
adc5e8b5 | 370 | node = &pos->rb.rb_right; |
fd7b9f7b TH |
371 | else |
372 | return -EEXIST; | |
373 | } | |
c1befb88 | 374 | |
fd7b9f7b | 375 | /* add new node and rebalance the tree */ |
adc5e8b5 TH |
376 | rb_link_node(&kn->rb, parent, node); |
377 | rb_insert_color(&kn->rb, &kn->parent->dir.children); | |
c1befb88 JZ |
378 | |
379 | /* successfully added, account subdir number */ | |
380 | if (kernfs_type(kn) == KERNFS_DIR) | |
381 | kn->parent->dir.subdirs++; | |
895adbec | 382 | kernfs_inc_rev(kn->parent); |
c1befb88 | 383 | |
fd7b9f7b TH |
384 | return 0; |
385 | } | |
386 | ||
387 | /** | |
c637b8ac | 388 | * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree |
324a56e1 | 389 | * @kn: kernfs_node of interest |
fd7b9f7b | 390 | * |
35beab06 TH |
391 | * Try to unlink @kn from its sibling rbtree which starts from |
392 | * kn->parent->dir.children. Returns %true if @kn was actually | |
393 | * removed, %false if @kn wasn't on the rbtree. | |
fd7b9f7b TH |
394 | * |
395 | * Locking: | |
7ba0273b | 396 | * kernfs_rwsem held exclusive |
fd7b9f7b | 397 | */ |
35beab06 | 398 | static bool kernfs_unlink_sibling(struct kernfs_node *kn) |
fd7b9f7b | 399 | { |
35beab06 TH |
400 | if (RB_EMPTY_NODE(&kn->rb)) |
401 | return false; | |
402 | ||
df23fc39 | 403 | if (kernfs_type(kn) == KERNFS_DIR) |
adc5e8b5 | 404 | kn->parent->dir.subdirs--; |
895adbec | 405 | kernfs_inc_rev(kn->parent); |
fd7b9f7b | 406 | |
adc5e8b5 | 407 | rb_erase(&kn->rb, &kn->parent->dir.children); |
35beab06 TH |
408 | RB_CLEAR_NODE(&kn->rb); |
409 | return true; | |
fd7b9f7b TH |
410 | } |
411 | ||
412 | /** | |
c637b8ac | 413 | * kernfs_get_active - get an active reference to kernfs_node |
324a56e1 | 414 | * @kn: kernfs_node to get an active reference to |
fd7b9f7b | 415 | * |
324a56e1 | 416 | * Get an active reference of @kn. This function is noop if @kn |
fd7b9f7b TH |
417 | * is NULL. |
418 | * | |
419 | * RETURNS: | |
324a56e1 | 420 | * Pointer to @kn on success, NULL on failure. |
fd7b9f7b | 421 | */ |
c637b8ac | 422 | struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) |
fd7b9f7b | 423 | { |
324a56e1 | 424 | if (unlikely(!kn)) |
fd7b9f7b TH |
425 | return NULL; |
426 | ||
f4b3e631 GKH |
427 | if (!atomic_inc_unless_negative(&kn->active)) |
428 | return NULL; | |
895a068a | 429 | |
182fd64b | 430 | if (kernfs_lockdep(kn)) |
f4b3e631 GKH |
431 | rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); |
432 | return kn; | |
fd7b9f7b TH |
433 | } |
434 | ||
435 | /** | |
c637b8ac | 436 | * kernfs_put_active - put an active reference to kernfs_node |
324a56e1 | 437 | * @kn: kernfs_node to put an active reference to |
fd7b9f7b | 438 | * |
324a56e1 | 439 | * Put an active reference to @kn. This function is noop if @kn |
fd7b9f7b TH |
440 | * is NULL. |
441 | */ | |
c637b8ac | 442 | void kernfs_put_active(struct kernfs_node *kn) |
fd7b9f7b TH |
443 | { |
444 | int v; | |
445 | ||
324a56e1 | 446 | if (unlikely(!kn)) |
fd7b9f7b TH |
447 | return; |
448 | ||
182fd64b | 449 | if (kernfs_lockdep(kn)) |
5facae4f | 450 | rwsem_release(&kn->dep_map, _RET_IP_); |
adc5e8b5 | 451 | v = atomic_dec_return(&kn->active); |
df23fc39 | 452 | if (likely(v != KN_DEACTIVATED_BIAS)) |
fd7b9f7b TH |
453 | return; |
454 | ||
2fd60da4 | 455 | wake_up_all(&kernfs_root(kn)->deactivate_waitq); |
fd7b9f7b TH |
456 | } |
457 | ||
458 | /** | |
81c173cb TH |
459 | * kernfs_drain - drain kernfs_node |
460 | * @kn: kernfs_node to drain | |
fd7b9f7b | 461 | * |
81c173cb TH |
462 | * Drain existing usages and nuke all existing mmaps of @kn. Mutiple |
463 | * removers may invoke this function concurrently on @kn and all will | |
464 | * return after draining is complete. | |
fd7b9f7b | 465 | */ |
81c173cb | 466 | static void kernfs_drain(struct kernfs_node *kn) |
393c3714 MK |
467 | __releases(&kernfs_root(kn)->kernfs_rwsem) |
468 | __acquires(&kernfs_root(kn)->kernfs_rwsem) | |
fd7b9f7b | 469 | { |
abd54f02 | 470 | struct kernfs_root *root = kernfs_root(kn); |
fd7b9f7b | 471 | |
393c3714 | 472 | lockdep_assert_held_write(&root->kernfs_rwsem); |
81c173cb | 473 | WARN_ON_ONCE(kernfs_active(kn)); |
ea1c472d | 474 | |
393c3714 | 475 | up_write(&root->kernfs_rwsem); |
abd54f02 | 476 | |
182fd64b | 477 | if (kernfs_lockdep(kn)) { |
35beab06 TH |
478 | rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); |
479 | if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) | |
480 | lock_contended(&kn->dep_map, _RET_IP_); | |
481 | } | |
abd54f02 | 482 | |
35beab06 | 483 | /* but everyone should wait for draining */ |
abd54f02 TH |
484 | wait_event(root->deactivate_waitq, |
485 | atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); | |
fd7b9f7b | 486 | |
182fd64b | 487 | if (kernfs_lockdep(kn)) { |
a6607930 | 488 | lock_acquired(&kn->dep_map, _RET_IP_); |
5facae4f | 489 | rwsem_release(&kn->dep_map, _RET_IP_); |
a6607930 | 490 | } |
35beab06 | 491 | |
0e67db2f | 492 | kernfs_drain_open_files(kn); |
ccf02aaf | 493 | |
393c3714 | 494 | down_write(&root->kernfs_rwsem); |
fd7b9f7b TH |
495 | } |
496 | ||
fd7b9f7b | 497 | /** |
324a56e1 TH |
498 | * kernfs_get - get a reference count on a kernfs_node |
499 | * @kn: the target kernfs_node | |
fd7b9f7b | 500 | */ |
324a56e1 | 501 | void kernfs_get(struct kernfs_node *kn) |
fd7b9f7b | 502 | { |
324a56e1 | 503 | if (kn) { |
adc5e8b5 TH |
504 | WARN_ON(!atomic_read(&kn->count)); |
505 | atomic_inc(&kn->count); | |
fd7b9f7b TH |
506 | } |
507 | } | |
508 | EXPORT_SYMBOL_GPL(kernfs_get); | |
509 | ||
510 | /** | |
324a56e1 TH |
511 | * kernfs_put - put a reference count on a kernfs_node |
512 | * @kn: the target kernfs_node | |
fd7b9f7b | 513 | * |
324a56e1 | 514 | * Put a reference count of @kn and destroy it if it reached zero. |
fd7b9f7b | 515 | */ |
324a56e1 | 516 | void kernfs_put(struct kernfs_node *kn) |
fd7b9f7b | 517 | { |
324a56e1 | 518 | struct kernfs_node *parent; |
ba7443bc | 519 | struct kernfs_root *root; |
fd7b9f7b | 520 | |
adc5e8b5 | 521 | if (!kn || !atomic_dec_and_test(&kn->count)) |
fd7b9f7b | 522 | return; |
324a56e1 | 523 | root = kernfs_root(kn); |
fd7b9f7b | 524 | repeat: |
81c173cb TH |
525 | /* |
526 | * Moving/renaming is always done while holding reference. | |
adc5e8b5 | 527 | * kn->parent won't change beneath us. |
fd7b9f7b | 528 | */ |
adc5e8b5 | 529 | parent = kn->parent; |
fd7b9f7b | 530 | |
81c173cb TH |
531 | WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS, |
532 | "kernfs_put: %s/%s: released with incorrect active_ref %d\n", | |
533 | parent ? parent->name : "", kn->name, atomic_read(&kn->active)); | |
324a56e1 | 534 | |
df23fc39 | 535 | if (kernfs_type(kn) == KERNFS_LINK) |
adc5e8b5 | 536 | kernfs_put(kn->symlink.target_kn); |
dfeb0750 TH |
537 | |
538 | kfree_const(kn->name); | |
539 | ||
adc5e8b5 | 540 | if (kn->iattr) { |
adc5e8b5 | 541 | simple_xattrs_free(&kn->iattr->xattrs); |
26e28d68 | 542 | kmem_cache_free(kernfs_iattrs_cache, kn->iattr); |
2322392b | 543 | } |
7d35079f | 544 | spin_lock(&kernfs_idr_lock); |
40430452 | 545 | idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
7d35079f | 546 | spin_unlock(&kernfs_idr_lock); |
a797bfc3 | 547 | kmem_cache_free(kernfs_node_cache, kn); |
fd7b9f7b | 548 | |
324a56e1 TH |
549 | kn = parent; |
550 | if (kn) { | |
adc5e8b5 | 551 | if (atomic_dec_and_test(&kn->count)) |
ba7443bc TH |
552 | goto repeat; |
553 | } else { | |
324a56e1 | 554 | /* just released the root kn, free @root too */ |
7d35079f | 555 | idr_destroy(&root->ino_idr); |
ba7443bc TH |
556 | kfree(root); |
557 | } | |
fd7b9f7b TH |
558 | } |
559 | EXPORT_SYMBOL_GPL(kernfs_put); | |
560 | ||
0c23b225 TH |
561 | /** |
562 | * kernfs_node_from_dentry - determine kernfs_node associated with a dentry | |
563 | * @dentry: the dentry in question | |
564 | * | |
565 | * Return the kernfs_node associated with @dentry. If @dentry is not a | |
566 | * kernfs one, %NULL is returned. | |
567 | * | |
568 | * While the returned kernfs_node will stay accessible as long as @dentry | |
569 | * is accessible, the returned node can be in any state and the caller is | |
570 | * fully responsible for determining what's accessible. | |
571 | */ | |
572 | struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) | |
573 | { | |
0288e7fa | 574 | if (dentry->d_sb->s_op == &kernfs_sops) |
319ba91d | 575 | return kernfs_dentry_node(dentry); |
0c23b225 TH |
576 | return NULL; |
577 | } | |
578 | ||
db4aad20 | 579 | static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, |
e19dfdc8 | 580 | struct kernfs_node *parent, |
db4aad20 | 581 | const char *name, umode_t mode, |
488dee96 | 582 | kuid_t uid, kgid_t gid, |
db4aad20 | 583 | unsigned flags) |
fd7b9f7b | 584 | { |
324a56e1 | 585 | struct kernfs_node *kn; |
40430452 | 586 | u32 id_highbits; |
bc755553 | 587 | int ret; |
fd7b9f7b | 588 | |
dfeb0750 TH |
589 | name = kstrdup_const(name, GFP_KERNEL); |
590 | if (!name) | |
591 | return NULL; | |
fd7b9f7b | 592 | |
a797bfc3 | 593 | kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL); |
324a56e1 | 594 | if (!kn) |
fd7b9f7b TH |
595 | goto err_out1; |
596 | ||
7d35079f SL |
597 | idr_preload(GFP_KERNEL); |
598 | spin_lock(&kernfs_idr_lock); | |
4a3ef68a | 599 | ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC); |
40430452 TH |
600 | if (ret >= 0 && ret < root->last_id_lowbits) |
601 | root->id_highbits++; | |
602 | id_highbits = root->id_highbits; | |
603 | root->last_id_lowbits = ret; | |
7d35079f SL |
604 | spin_unlock(&kernfs_idr_lock); |
605 | idr_preload_end(); | |
bc755553 | 606 | if (ret < 0) |
fd7b9f7b | 607 | goto err_out2; |
67c0496e | 608 | |
40430452 | 609 | kn->id = (u64)id_highbits << 32 | ret; |
fd7b9f7b | 610 | |
b680b081 | 611 | atomic_set(&kn->count, 1); |
81c173cb | 612 | atomic_set(&kn->active, KN_DEACTIVATED_BIAS); |
35beab06 | 613 | RB_CLEAR_NODE(&kn->rb); |
fd7b9f7b | 614 | |
adc5e8b5 TH |
615 | kn->name = name; |
616 | kn->mode = mode; | |
81c173cb | 617 | kn->flags = flags; |
fd7b9f7b | 618 | |
488dee96 DT |
619 | if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) { |
620 | struct iattr iattr = { | |
621 | .ia_valid = ATTR_UID | ATTR_GID, | |
622 | .ia_uid = uid, | |
623 | .ia_gid = gid, | |
624 | }; | |
625 | ||
626 | ret = __kernfs_setattr(kn, &iattr); | |
627 | if (ret < 0) | |
628 | goto err_out3; | |
629 | } | |
630 | ||
e19dfdc8 OM |
631 | if (parent) { |
632 | ret = security_kernfs_init_security(parent, kn); | |
633 | if (ret) | |
634 | goto err_out3; | |
635 | } | |
636 | ||
324a56e1 | 637 | return kn; |
fd7b9f7b | 638 | |
488dee96 | 639 | err_out3: |
40430452 | 640 | idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
fd7b9f7b | 641 | err_out2: |
a797bfc3 | 642 | kmem_cache_free(kernfs_node_cache, kn); |
fd7b9f7b | 643 | err_out1: |
dfeb0750 | 644 | kfree_const(name); |
fd7b9f7b TH |
645 | return NULL; |
646 | } | |
647 | ||
db4aad20 TH |
648 | struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, |
649 | const char *name, umode_t mode, | |
488dee96 | 650 | kuid_t uid, kgid_t gid, |
db4aad20 TH |
651 | unsigned flags) |
652 | { | |
653 | struct kernfs_node *kn; | |
654 | ||
e19dfdc8 | 655 | kn = __kernfs_new_node(kernfs_root(parent), parent, |
488dee96 | 656 | name, mode, uid, gid, flags); |
db4aad20 TH |
657 | if (kn) { |
658 | kernfs_get(parent); | |
659 | kn->parent = parent; | |
660 | } | |
661 | return kn; | |
662 | } | |
663 | ||
ba16b284 | 664 | /* |
fe0f726c | 665 | * kernfs_find_and_get_node_by_id - get kernfs_node from node id |
ba16b284 | 666 | * @root: the kernfs root |
fe0f726c TH |
667 | * @id: the target node id |
668 | * | |
669 | * @id's lower 32bits encode ino and upper gen. If the gen portion is | |
670 | * zero, all generations are matched. | |
ba16b284 SL |
671 | * |
672 | * RETURNS: | |
673 | * NULL on failure. Return a kernfs node with reference counter incremented | |
674 | */ | |
fe0f726c TH |
675 | struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, |
676 | u64 id) | |
ba16b284 SL |
677 | { |
678 | struct kernfs_node *kn; | |
fe0f726c TH |
679 | ino_t ino = kernfs_id_ino(id); |
680 | u32 gen = kernfs_id_gen(id); | |
ba16b284 | 681 | |
b680b081 TH |
682 | spin_lock(&kernfs_idr_lock); |
683 | ||
40430452 | 684 | kn = idr_find(&root->ino_idr, (u32)ino); |
ba16b284 | 685 | if (!kn) |
b680b081 | 686 | goto err_unlock; |
ba16b284 | 687 | |
40430452 TH |
688 | if (sizeof(ino_t) >= sizeof(u64)) { |
689 | /* we looked up with the low 32bits, compare the whole */ | |
690 | if (kernfs_ino(kn) != ino) | |
691 | goto err_unlock; | |
692 | } else { | |
693 | /* 0 matches all generations */ | |
694 | if (unlikely(gen && kernfs_gen(kn) != gen)) | |
695 | goto err_unlock; | |
696 | } | |
fe0f726c | 697 | |
880df131 TH |
698 | /* |
699 | * ACTIVATED is protected with kernfs_mutex but it was clear when | |
700 | * @kn was added to idr and we just wanna see it set. No need to | |
701 | * grab kernfs_mutex. | |
702 | */ | |
703 | if (unlikely(!(kn->flags & KERNFS_ACTIVATED) || | |
704 | !atomic_inc_not_zero(&kn->count))) | |
b680b081 | 705 | goto err_unlock; |
ba16b284 | 706 | |
b680b081 | 707 | spin_unlock(&kernfs_idr_lock); |
ba16b284 | 708 | return kn; |
b680b081 TH |
709 | err_unlock: |
710 | spin_unlock(&kernfs_idr_lock); | |
ba16b284 SL |
711 | return NULL; |
712 | } | |
713 | ||
fd7b9f7b | 714 | /** |
c637b8ac | 715 | * kernfs_add_one - add kernfs_node to parent without warning |
324a56e1 | 716 | * @kn: kernfs_node to be added |
fd7b9f7b | 717 | * |
db4aad20 TH |
718 | * The caller must already have initialized @kn->parent. This |
719 | * function increments nlink of the parent's inode if @kn is a | |
720 | * directory and link into the children list of the parent. | |
fd7b9f7b | 721 | * |
fd7b9f7b TH |
722 | * RETURNS: |
723 | * 0 on success, -EEXIST if entry with the given name already | |
724 | * exists. | |
725 | */ | |
988cd7af | 726 | int kernfs_add_one(struct kernfs_node *kn) |
fd7b9f7b | 727 | { |
db4aad20 | 728 | struct kernfs_node *parent = kn->parent; |
393c3714 | 729 | struct kernfs_root *root = kernfs_root(parent); |
c525aadd | 730 | struct kernfs_iattrs *ps_iattr; |
988cd7af | 731 | bool has_ns; |
fd7b9f7b TH |
732 | int ret; |
733 | ||
393c3714 | 734 | down_write(&root->kernfs_rwsem); |
988cd7af TH |
735 | |
736 | ret = -EINVAL; | |
737 | has_ns = kernfs_ns_enabled(parent); | |
738 | if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", | |
739 | has_ns ? "required" : "invalid", parent->name, kn->name)) | |
740 | goto out_unlock; | |
fd7b9f7b | 741 | |
df23fc39 | 742 | if (kernfs_type(parent) != KERNFS_DIR) |
988cd7af | 743 | goto out_unlock; |
fd7b9f7b | 744 | |
988cd7af | 745 | ret = -ENOENT; |
ea015218 EB |
746 | if (parent->flags & KERNFS_EMPTY_DIR) |
747 | goto out_unlock; | |
748 | ||
d35258ef | 749 | if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent)) |
988cd7af | 750 | goto out_unlock; |
798c75a0 | 751 | |
c637b8ac | 752 | kn->hash = kernfs_name_hash(kn->name, kn->ns); |
fd7b9f7b | 753 | |
c637b8ac | 754 | ret = kernfs_link_sibling(kn); |
fd7b9f7b | 755 | if (ret) |
988cd7af | 756 | goto out_unlock; |
fd7b9f7b TH |
757 | |
758 | /* Update timestamps on the parent */ | |
adc5e8b5 | 759 | ps_iattr = parent->iattr; |
fd7b9f7b | 760 | if (ps_iattr) { |
05895219 OM |
761 | ktime_get_real_ts64(&ps_iattr->ia_ctime); |
762 | ps_iattr->ia_mtime = ps_iattr->ia_ctime; | |
fd7b9f7b TH |
763 | } |
764 | ||
393c3714 | 765 | up_write(&root->kernfs_rwsem); |
d35258ef TH |
766 | |
767 | /* | |
768 | * Activate the new node unless CREATE_DEACTIVATED is requested. | |
769 | * If not activated here, the kernfs user is responsible for | |
770 | * activating the node with kernfs_activate(). A node which hasn't | |
771 | * been activated is not visible to userland and its removal won't | |
772 | * trigger deactivation. | |
773 | */ | |
774 | if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) | |
775 | kernfs_activate(kn); | |
776 | return 0; | |
777 | ||
988cd7af | 778 | out_unlock: |
393c3714 | 779 | up_write(&root->kernfs_rwsem); |
988cd7af | 780 | return ret; |
fd7b9f7b TH |
781 | } |
782 | ||
783 | /** | |
324a56e1 TH |
784 | * kernfs_find_ns - find kernfs_node with the given name |
785 | * @parent: kernfs_node to search under | |
fd7b9f7b TH |
786 | * @name: name to look for |
787 | * @ns: the namespace tag to use | |
788 | * | |
324a56e1 TH |
789 | * Look for kernfs_node with name @name under @parent. Returns pointer to |
790 | * the found kernfs_node on success, %NULL on failure. | |
fd7b9f7b | 791 | */ |
324a56e1 TH |
792 | static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, |
793 | const unsigned char *name, | |
794 | const void *ns) | |
fd7b9f7b | 795 | { |
adc5e8b5 | 796 | struct rb_node *node = parent->dir.children.rb_node; |
ac9bba03 | 797 | bool has_ns = kernfs_ns_enabled(parent); |
fd7b9f7b TH |
798 | unsigned int hash; |
799 | ||
393c3714 | 800 | lockdep_assert_held(&kernfs_root(parent)->kernfs_rwsem); |
fd7b9f7b TH |
801 | |
802 | if (has_ns != (bool)ns) { | |
c637b8ac | 803 | WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", |
adc5e8b5 | 804 | has_ns ? "required" : "invalid", parent->name, name); |
fd7b9f7b TH |
805 | return NULL; |
806 | } | |
807 | ||
c637b8ac | 808 | hash = kernfs_name_hash(name, ns); |
fd7b9f7b | 809 | while (node) { |
324a56e1 | 810 | struct kernfs_node *kn; |
fd7b9f7b TH |
811 | int result; |
812 | ||
324a56e1 | 813 | kn = rb_to_kn(node); |
c637b8ac | 814 | result = kernfs_name_compare(hash, name, ns, kn); |
fd7b9f7b TH |
815 | if (result < 0) |
816 | node = node->rb_left; | |
817 | else if (result > 0) | |
818 | node = node->rb_right; | |
819 | else | |
324a56e1 | 820 | return kn; |
fd7b9f7b TH |
821 | } |
822 | return NULL; | |
823 | } | |
824 | ||
bd96f76a TH |
825 | static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, |
826 | const unsigned char *path, | |
827 | const void *ns) | |
828 | { | |
e56ed358 TH |
829 | size_t len; |
830 | char *p, *name; | |
bd96f76a | 831 | |
393c3714 | 832 | lockdep_assert_held_read(&kernfs_root(parent)->kernfs_rwsem); |
bd96f76a | 833 | |
1a702dc8 | 834 | spin_lock_irq(&kernfs_pr_cont_lock); |
e56ed358 TH |
835 | |
836 | len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); | |
837 | ||
838 | if (len >= sizeof(kernfs_pr_cont_buf)) { | |
1a702dc8 | 839 | spin_unlock_irq(&kernfs_pr_cont_lock); |
bd96f76a | 840 | return NULL; |
e56ed358 TH |
841 | } |
842 | ||
843 | p = kernfs_pr_cont_buf; | |
bd96f76a TH |
844 | |
845 | while ((name = strsep(&p, "/")) && parent) { | |
846 | if (*name == '\0') | |
847 | continue; | |
848 | parent = kernfs_find_ns(parent, name, ns); | |
849 | } | |
850 | ||
1a702dc8 | 851 | spin_unlock_irq(&kernfs_pr_cont_lock); |
e56ed358 | 852 | |
bd96f76a TH |
853 | return parent; |
854 | } | |
855 | ||
fd7b9f7b | 856 | /** |
324a56e1 TH |
857 | * kernfs_find_and_get_ns - find and get kernfs_node with the given name |
858 | * @parent: kernfs_node to search under | |
fd7b9f7b TH |
859 | * @name: name to look for |
860 | * @ns: the namespace tag to use | |
861 | * | |
324a56e1 | 862 | * Look for kernfs_node with name @name under @parent and get a reference |
fd7b9f7b | 863 | * if found. This function may sleep and returns pointer to the found |
324a56e1 | 864 | * kernfs_node on success, %NULL on failure. |
fd7b9f7b | 865 | */ |
324a56e1 TH |
866 | struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, |
867 | const char *name, const void *ns) | |
fd7b9f7b | 868 | { |
324a56e1 | 869 | struct kernfs_node *kn; |
393c3714 | 870 | struct kernfs_root *root = kernfs_root(parent); |
fd7b9f7b | 871 | |
393c3714 | 872 | down_read(&root->kernfs_rwsem); |
324a56e1 TH |
873 | kn = kernfs_find_ns(parent, name, ns); |
874 | kernfs_get(kn); | |
393c3714 | 875 | up_read(&root->kernfs_rwsem); |
fd7b9f7b | 876 | |
324a56e1 | 877 | return kn; |
fd7b9f7b TH |
878 | } |
879 | EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); | |
880 | ||
bd96f76a TH |
881 | /** |
882 | * kernfs_walk_and_get_ns - find and get kernfs_node with the given path | |
883 | * @parent: kernfs_node to search under | |
884 | * @path: path to look for | |
885 | * @ns: the namespace tag to use | |
886 | * | |
887 | * Look for kernfs_node with path @path under @parent and get a reference | |
888 | * if found. This function may sleep and returns pointer to the found | |
889 | * kernfs_node on success, %NULL on failure. | |
890 | */ | |
891 | struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent, | |
892 | const char *path, const void *ns) | |
893 | { | |
894 | struct kernfs_node *kn; | |
393c3714 | 895 | struct kernfs_root *root = kernfs_root(parent); |
bd96f76a | 896 | |
393c3714 | 897 | down_read(&root->kernfs_rwsem); |
bd96f76a TH |
898 | kn = kernfs_walk_ns(parent, path, ns); |
899 | kernfs_get(kn); | |
393c3714 | 900 | up_read(&root->kernfs_rwsem); |
bd96f76a TH |
901 | |
902 | return kn; | |
903 | } | |
904 | ||
ba7443bc TH |
905 | /** |
906 | * kernfs_create_root - create a new kernfs hierarchy | |
90c07c89 | 907 | * @scops: optional syscall operations for the hierarchy |
d35258ef | 908 | * @flags: KERNFS_ROOT_* flags |
ba7443bc TH |
909 | * @priv: opaque data associated with the new directory |
910 | * | |
911 | * Returns the root of the new hierarchy on success, ERR_PTR() value on | |
912 | * failure. | |
913 | */ | |
90c07c89 | 914 | struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, |
d35258ef | 915 | unsigned int flags, void *priv) |
ba7443bc TH |
916 | { |
917 | struct kernfs_root *root; | |
324a56e1 | 918 | struct kernfs_node *kn; |
ba7443bc TH |
919 | |
920 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
921 | if (!root) | |
922 | return ERR_PTR(-ENOMEM); | |
923 | ||
7d35079f | 924 | idr_init(&root->ino_idr); |
393c3714 | 925 | init_rwsem(&root->kernfs_rwsem); |
7d568a83 | 926 | INIT_LIST_HEAD(&root->supers); |
40430452 TH |
927 | |
928 | /* | |
929 | * On 64bit ino setups, id is ino. On 32bit, low 32bits are ino. | |
930 | * High bits generation. The starting value for both ino and | |
931 | * genenration is 1. Initialize upper 32bit allocation | |
932 | * accordingly. | |
933 | */ | |
934 | if (sizeof(ino_t) >= sizeof(u64)) | |
935 | root->id_highbits = 0; | |
936 | else | |
937 | root->id_highbits = 1; | |
bc755553 | 938 | |
e19dfdc8 | 939 | kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO, |
488dee96 | 940 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
db4aad20 | 941 | KERNFS_DIR); |
324a56e1 | 942 | if (!kn) { |
7d35079f | 943 | idr_destroy(&root->ino_idr); |
ba7443bc TH |
944 | kfree(root); |
945 | return ERR_PTR(-ENOMEM); | |
946 | } | |
947 | ||
324a56e1 | 948 | kn->priv = priv; |
adc5e8b5 | 949 | kn->dir.root = root; |
ba7443bc | 950 | |
90c07c89 | 951 | root->syscall_ops = scops; |
d35258ef | 952 | root->flags = flags; |
324a56e1 | 953 | root->kn = kn; |
abd54f02 | 954 | init_waitqueue_head(&root->deactivate_waitq); |
ba7443bc | 955 | |
d35258ef TH |
956 | if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
957 | kernfs_activate(kn); | |
958 | ||
ba7443bc TH |
959 | return root; |
960 | } | |
961 | ||
962 | /** | |
963 | * kernfs_destroy_root - destroy a kernfs hierarchy | |
964 | * @root: root of the hierarchy to destroy | |
965 | * | |
966 | * Destroy the hierarchy anchored at @root by removing all existing | |
967 | * directories and destroying @root. | |
968 | */ | |
969 | void kernfs_destroy_root(struct kernfs_root *root) | |
970 | { | |
555a0ce4 MK |
971 | /* |
972 | * kernfs_remove holds kernfs_rwsem from the root so the root | |
973 | * shouldn't be freed during the operation. | |
974 | */ | |
975 | kernfs_get(root->kn); | |
976 | kernfs_remove(root->kn); | |
977 | kernfs_put(root->kn); /* will also free @root */ | |
ba7443bc TH |
978 | } |
979 | ||
f2eb478f GKH |
980 | /** |
981 | * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root | |
982 | * @root: root to use to lookup | |
983 | */ | |
984 | struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root) | |
985 | { | |
986 | return root->kn; | |
987 | } | |
988 | ||
fd7b9f7b TH |
989 | /** |
990 | * kernfs_create_dir_ns - create a directory | |
991 | * @parent: parent in which to create a new directory | |
992 | * @name: name of the new directory | |
bb8b9d09 | 993 | * @mode: mode of the new directory |
488dee96 DT |
994 | * @uid: uid of the new directory |
995 | * @gid: gid of the new directory | |
fd7b9f7b TH |
996 | * @priv: opaque data associated with the new directory |
997 | * @ns: optional namespace tag of the directory | |
998 | * | |
999 | * Returns the created node on success, ERR_PTR() value on failure. | |
1000 | */ | |
324a56e1 | 1001 | struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, |
bb8b9d09 | 1002 | const char *name, umode_t mode, |
488dee96 | 1003 | kuid_t uid, kgid_t gid, |
bb8b9d09 | 1004 | void *priv, const void *ns) |
fd7b9f7b | 1005 | { |
324a56e1 | 1006 | struct kernfs_node *kn; |
fd7b9f7b TH |
1007 | int rc; |
1008 | ||
1009 | /* allocate */ | |
488dee96 DT |
1010 | kn = kernfs_new_node(parent, name, mode | S_IFDIR, |
1011 | uid, gid, KERNFS_DIR); | |
324a56e1 | 1012 | if (!kn) |
fd7b9f7b TH |
1013 | return ERR_PTR(-ENOMEM); |
1014 | ||
adc5e8b5 TH |
1015 | kn->dir.root = parent->dir.root; |
1016 | kn->ns = ns; | |
324a56e1 | 1017 | kn->priv = priv; |
fd7b9f7b TH |
1018 | |
1019 | /* link in */ | |
988cd7af | 1020 | rc = kernfs_add_one(kn); |
fd7b9f7b | 1021 | if (!rc) |
324a56e1 | 1022 | return kn; |
fd7b9f7b | 1023 | |
324a56e1 | 1024 | kernfs_put(kn); |
fd7b9f7b TH |
1025 | return ERR_PTR(rc); |
1026 | } | |
1027 | ||
ea015218 EB |
1028 | /** |
1029 | * kernfs_create_empty_dir - create an always empty directory | |
1030 | * @parent: parent in which to create a new directory | |
1031 | * @name: name of the new directory | |
1032 | * | |
1033 | * Returns the created node on success, ERR_PTR() value on failure. | |
1034 | */ | |
1035 | struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent, | |
1036 | const char *name) | |
1037 | { | |
1038 | struct kernfs_node *kn; | |
1039 | int rc; | |
1040 | ||
1041 | /* allocate */ | |
488dee96 DT |
1042 | kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR, |
1043 | GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR); | |
ea015218 EB |
1044 | if (!kn) |
1045 | return ERR_PTR(-ENOMEM); | |
1046 | ||
1047 | kn->flags |= KERNFS_EMPTY_DIR; | |
1048 | kn->dir.root = parent->dir.root; | |
1049 | kn->ns = NULL; | |
1050 | kn->priv = NULL; | |
1051 | ||
1052 | /* link in */ | |
1053 | rc = kernfs_add_one(kn); | |
1054 | if (!rc) | |
1055 | return kn; | |
1056 | ||
1057 | kernfs_put(kn); | |
1058 | return ERR_PTR(rc); | |
1059 | } | |
1060 | ||
d826e036 IK |
1061 | static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) |
1062 | { | |
1063 | struct kernfs_node *kn; | |
393c3714 | 1064 | struct kernfs_root *root; |
d826e036 IK |
1065 | |
1066 | if (flags & LOOKUP_RCU) | |
1067 | return -ECHILD; | |
1068 | ||
c7e7c042 IK |
1069 | /* Negative hashed dentry? */ |
1070 | if (d_really_is_negative(dentry)) { | |
1071 | struct kernfs_node *parent; | |
1072 | ||
1073 | /* If the kernfs parent node has changed discard and | |
1074 | * proceed to ->lookup. | |
1075 | */ | |
c7e7c042 IK |
1076 | spin_lock(&dentry->d_lock); |
1077 | parent = kernfs_dentry_node(dentry->d_parent); | |
1078 | if (parent) { | |
393c3714 MK |
1079 | spin_unlock(&dentry->d_lock); |
1080 | root = kernfs_root(parent); | |
1081 | down_read(&root->kernfs_rwsem); | |
c7e7c042 | 1082 | if (kernfs_dir_changed(parent, dentry)) { |
393c3714 | 1083 | up_read(&root->kernfs_rwsem); |
c7e7c042 IK |
1084 | return 0; |
1085 | } | |
393c3714 MK |
1086 | up_read(&root->kernfs_rwsem); |
1087 | } else | |
1088 | spin_unlock(&dentry->d_lock); | |
c7e7c042 IK |
1089 | |
1090 | /* The kernfs parent node hasn't changed, leave the | |
1091 | * dentry negative and return success. | |
1092 | */ | |
1093 | return 1; | |
1094 | } | |
d826e036 IK |
1095 | |
1096 | kn = kernfs_dentry_node(dentry); | |
393c3714 MK |
1097 | root = kernfs_root(kn); |
1098 | down_read(&root->kernfs_rwsem); | |
d826e036 IK |
1099 | |
1100 | /* The kernfs node has been deactivated */ | |
1101 | if (!kernfs_active(kn)) | |
1102 | goto out_bad; | |
1103 | ||
1104 | /* The kernfs node has been moved? */ | |
1105 | if (kernfs_dentry_node(dentry->d_parent) != kn->parent) | |
1106 | goto out_bad; | |
1107 | ||
1108 | /* The kernfs node has been renamed */ | |
1109 | if (strcmp(dentry->d_name.name, kn->name) != 0) | |
1110 | goto out_bad; | |
1111 | ||
1112 | /* The kernfs node has been moved to a different namespace */ | |
1113 | if (kn->parent && kernfs_ns_enabled(kn->parent) && | |
1114 | kernfs_info(dentry->d_sb)->ns != kn->ns) | |
1115 | goto out_bad; | |
1116 | ||
393c3714 | 1117 | up_read(&root->kernfs_rwsem); |
d826e036 IK |
1118 | return 1; |
1119 | out_bad: | |
393c3714 | 1120 | up_read(&root->kernfs_rwsem); |
d826e036 IK |
1121 | return 0; |
1122 | } | |
1123 | ||
1124 | const struct dentry_operations kernfs_dops = { | |
1125 | .d_revalidate = kernfs_dop_revalidate, | |
1126 | }; | |
1127 | ||
c637b8ac TH |
1128 | static struct dentry *kernfs_iop_lookup(struct inode *dir, |
1129 | struct dentry *dentry, | |
1130 | unsigned int flags) | |
fd7b9f7b | 1131 | { |
319ba91d | 1132 | struct kernfs_node *parent = dir->i_private; |
324a56e1 | 1133 | struct kernfs_node *kn; |
393c3714 | 1134 | struct kernfs_root *root; |
c7e7c042 | 1135 | struct inode *inode = NULL; |
fd7b9f7b TH |
1136 | const void *ns = NULL; |
1137 | ||
393c3714 MK |
1138 | root = kernfs_root(parent); |
1139 | down_read(&root->kernfs_rwsem); | |
324a56e1 | 1140 | if (kernfs_ns_enabled(parent)) |
c525aadd | 1141 | ns = kernfs_info(dir->i_sb)->ns; |
fd7b9f7b | 1142 | |
324a56e1 | 1143 | kn = kernfs_find_ns(parent, dentry->d_name.name, ns); |
fd7b9f7b | 1144 | /* attach dentry and inode */ |
410d591a IK |
1145 | if (kn) { |
1146 | /* Inactive nodes are invisible to the VFS so don't | |
1147 | * create a negative. | |
1148 | */ | |
1149 | if (!kernfs_active(kn)) { | |
393c3714 | 1150 | up_read(&root->kernfs_rwsem); |
410d591a IK |
1151 | return NULL; |
1152 | } | |
c7e7c042 IK |
1153 | inode = kernfs_get_inode(dir->i_sb, kn); |
1154 | if (!inode) | |
1155 | inode = ERR_PTR(-ENOMEM); | |
fd7b9f7b | 1156 | } |
df38d852 HT |
1157 | /* |
1158 | * Needed for negative dentry validation. | |
1159 | * The negative dentry can be created in kernfs_iop_lookup() | |
1160 | * or transforms from positive dentry in dentry_unlink_inode() | |
1161 | * called from vfs_rmdir(). | |
1162 | */ | |
1163 | if (!IS_ERR(inode)) | |
c7e7c042 | 1164 | kernfs_set_rev(parent, dentry); |
393c3714 | 1165 | up_read(&root->kernfs_rwsem); |
c7e7c042 | 1166 | |
df6192f4 IK |
1167 | /* instantiate and hash (possibly negative) dentry */ |
1168 | return d_splice_alias(inode, dentry); | |
fd7b9f7b TH |
1169 | } |
1170 | ||
549c7297 CB |
1171 | static int kernfs_iop_mkdir(struct user_namespace *mnt_userns, |
1172 | struct inode *dir, struct dentry *dentry, | |
80b9bbef TH |
1173 | umode_t mode) |
1174 | { | |
1175 | struct kernfs_node *parent = dir->i_private; | |
90c07c89 | 1176 | struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops; |
07c7530d | 1177 | int ret; |
80b9bbef | 1178 | |
90c07c89 | 1179 | if (!scops || !scops->mkdir) |
80b9bbef TH |
1180 | return -EPERM; |
1181 | ||
07c7530d TH |
1182 | if (!kernfs_get_active(parent)) |
1183 | return -ENODEV; | |
1184 | ||
90c07c89 | 1185 | ret = scops->mkdir(parent, dentry->d_name.name, mode); |
07c7530d TH |
1186 | |
1187 | kernfs_put_active(parent); | |
1188 | return ret; | |
80b9bbef TH |
1189 | } |
1190 | ||
1191 | static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) | |
1192 | { | |
319ba91d | 1193 | struct kernfs_node *kn = kernfs_dentry_node(dentry); |
90c07c89 | 1194 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
07c7530d | 1195 | int ret; |
80b9bbef | 1196 | |
90c07c89 | 1197 | if (!scops || !scops->rmdir) |
80b9bbef TH |
1198 | return -EPERM; |
1199 | ||
07c7530d TH |
1200 | if (!kernfs_get_active(kn)) |
1201 | return -ENODEV; | |
1202 | ||
90c07c89 | 1203 | ret = scops->rmdir(kn); |
07c7530d TH |
1204 | |
1205 | kernfs_put_active(kn); | |
1206 | return ret; | |
80b9bbef TH |
1207 | } |
1208 | ||
549c7297 CB |
1209 | static int kernfs_iop_rename(struct user_namespace *mnt_userns, |
1210 | struct inode *old_dir, struct dentry *old_dentry, | |
1cd66c93 MS |
1211 | struct inode *new_dir, struct dentry *new_dentry, |
1212 | unsigned int flags) | |
80b9bbef | 1213 | { |
319ba91d | 1214 | struct kernfs_node *kn = kernfs_dentry_node(old_dentry); |
80b9bbef | 1215 | struct kernfs_node *new_parent = new_dir->i_private; |
90c07c89 | 1216 | struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
07c7530d | 1217 | int ret; |
80b9bbef | 1218 | |
1cd66c93 MS |
1219 | if (flags) |
1220 | return -EINVAL; | |
1221 | ||
90c07c89 | 1222 | if (!scops || !scops->rename) |
80b9bbef TH |
1223 | return -EPERM; |
1224 | ||
07c7530d TH |
1225 | if (!kernfs_get_active(kn)) |
1226 | return -ENODEV; | |
1227 | ||
1228 | if (!kernfs_get_active(new_parent)) { | |
1229 | kernfs_put_active(kn); | |
1230 | return -ENODEV; | |
1231 | } | |
1232 | ||
90c07c89 | 1233 | ret = scops->rename(kn, new_parent, new_dentry->d_name.name); |
07c7530d TH |
1234 | |
1235 | kernfs_put_active(new_parent); | |
1236 | kernfs_put_active(kn); | |
1237 | return ret; | |
80b9bbef TH |
1238 | } |
1239 | ||
a797bfc3 | 1240 | const struct inode_operations kernfs_dir_iops = { |
c637b8ac TH |
1241 | .lookup = kernfs_iop_lookup, |
1242 | .permission = kernfs_iop_permission, | |
1243 | .setattr = kernfs_iop_setattr, | |
1244 | .getattr = kernfs_iop_getattr, | |
c637b8ac | 1245 | .listxattr = kernfs_iop_listxattr, |
80b9bbef TH |
1246 | |
1247 | .mkdir = kernfs_iop_mkdir, | |
1248 | .rmdir = kernfs_iop_rmdir, | |
1249 | .rename = kernfs_iop_rename, | |
fd7b9f7b TH |
1250 | }; |
1251 | ||
c637b8ac | 1252 | static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos) |
fd7b9f7b | 1253 | { |
324a56e1 | 1254 | struct kernfs_node *last; |
fd7b9f7b TH |
1255 | |
1256 | while (true) { | |
1257 | struct rb_node *rbn; | |
1258 | ||
1259 | last = pos; | |
1260 | ||
df23fc39 | 1261 | if (kernfs_type(pos) != KERNFS_DIR) |
fd7b9f7b TH |
1262 | break; |
1263 | ||
adc5e8b5 | 1264 | rbn = rb_first(&pos->dir.children); |
fd7b9f7b TH |
1265 | if (!rbn) |
1266 | break; | |
1267 | ||
324a56e1 | 1268 | pos = rb_to_kn(rbn); |
fd7b9f7b TH |
1269 | } |
1270 | ||
1271 | return last; | |
1272 | } | |
1273 | ||
1274 | /** | |
c637b8ac | 1275 | * kernfs_next_descendant_post - find the next descendant for post-order walk |
fd7b9f7b | 1276 | * @pos: the current position (%NULL to initiate traversal) |
324a56e1 | 1277 | * @root: kernfs_node whose descendants to walk |
fd7b9f7b TH |
1278 | * |
1279 | * Find the next descendant to visit for post-order traversal of @root's | |
1280 | * descendants. @root is included in the iteration and the last node to be | |
1281 | * visited. | |
1282 | */ | |
c637b8ac TH |
1283 | static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, |
1284 | struct kernfs_node *root) | |
fd7b9f7b TH |
1285 | { |
1286 | struct rb_node *rbn; | |
1287 | ||
393c3714 | 1288 | lockdep_assert_held_write(&kernfs_root(root)->kernfs_rwsem); |
fd7b9f7b TH |
1289 | |
1290 | /* if first iteration, visit leftmost descendant which may be root */ | |
1291 | if (!pos) | |
c637b8ac | 1292 | return kernfs_leftmost_descendant(root); |
fd7b9f7b TH |
1293 | |
1294 | /* if we visited @root, we're done */ | |
1295 | if (pos == root) | |
1296 | return NULL; | |
1297 | ||
1298 | /* if there's an unvisited sibling, visit its leftmost descendant */ | |
adc5e8b5 | 1299 | rbn = rb_next(&pos->rb); |
fd7b9f7b | 1300 | if (rbn) |
c637b8ac | 1301 | return kernfs_leftmost_descendant(rb_to_kn(rbn)); |
fd7b9f7b TH |
1302 | |
1303 | /* no sibling left, visit parent */ | |
adc5e8b5 | 1304 | return pos->parent; |
fd7b9f7b TH |
1305 | } |
1306 | ||
d35258ef TH |
1307 | /** |
1308 | * kernfs_activate - activate a node which started deactivated | |
1309 | * @kn: kernfs_node whose subtree is to be activated | |
1310 | * | |
1311 | * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node | |
1312 | * needs to be explicitly activated. A node which hasn't been activated | |
1313 | * isn't visible to userland and deactivation is skipped during its | |
1314 | * removal. This is useful to construct atomic init sequences where | |
1315 | * creation of multiple nodes should either succeed or fail atomically. | |
1316 | * | |
1317 | * The caller is responsible for ensuring that this function is not called | |
1318 | * after kernfs_remove*() is invoked on @kn. | |
1319 | */ | |
1320 | void kernfs_activate(struct kernfs_node *kn) | |
1321 | { | |
1322 | struct kernfs_node *pos; | |
393c3714 | 1323 | struct kernfs_root *root = kernfs_root(kn); |
d35258ef | 1324 | |
393c3714 | 1325 | down_write(&root->kernfs_rwsem); |
d35258ef TH |
1326 | |
1327 | pos = NULL; | |
1328 | while ((pos = kernfs_next_descendant_post(pos, kn))) { | |
5bf33f04 | 1329 | if (pos->flags & KERNFS_ACTIVATED) |
d35258ef TH |
1330 | continue; |
1331 | ||
1332 | WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb)); | |
1333 | WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS); | |
1334 | ||
1335 | atomic_sub(KN_DEACTIVATED_BIAS, &pos->active); | |
1336 | pos->flags |= KERNFS_ACTIVATED; | |
1337 | } | |
1338 | ||
393c3714 | 1339 | up_write(&root->kernfs_rwsem); |
d35258ef TH |
1340 | } |
1341 | ||
988cd7af | 1342 | static void __kernfs_remove(struct kernfs_node *kn) |
fd7b9f7b | 1343 | { |
35beab06 TH |
1344 | struct kernfs_node *pos; |
1345 | ||
72b5d5ae YZ |
1346 | /* Short-circuit if non-root @kn has already finished removal. */ |
1347 | if (!kn) | |
1348 | return; | |
1349 | ||
393c3714 | 1350 | lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); |
fd7b9f7b | 1351 | |
6b0afc2a | 1352 | /* |
6b0afc2a TH |
1353 | * This is for kernfs_remove_self() which plays with active ref |
1354 | * after removal. | |
1355 | */ | |
72b5d5ae | 1356 | if (kn->parent && RB_EMPTY_NODE(&kn->rb)) |
ce9b499c GKH |
1357 | return; |
1358 | ||
c637b8ac | 1359 | pr_debug("kernfs %s: removing\n", kn->name); |
fd7b9f7b | 1360 | |
81c173cb | 1361 | /* prevent any new usage under @kn by deactivating all nodes */ |
35beab06 TH |
1362 | pos = NULL; |
1363 | while ((pos = kernfs_next_descendant_post(pos, kn))) | |
81c173cb TH |
1364 | if (kernfs_active(pos)) |
1365 | atomic_add(KN_DEACTIVATED_BIAS, &pos->active); | |
35beab06 TH |
1366 | |
1367 | /* deactivate and unlink the subtree node-by-node */ | |
fd7b9f7b | 1368 | do { |
35beab06 TH |
1369 | pos = kernfs_leftmost_descendant(kn); |
1370 | ||
1371 | /* | |
7ba0273b | 1372 | * kernfs_drain() drops kernfs_rwsem temporarily and @pos's |
81c173cb TH |
1373 | * base ref could have been put by someone else by the time |
1374 | * the function returns. Make sure it doesn't go away | |
1375 | * underneath us. | |
35beab06 TH |
1376 | */ |
1377 | kernfs_get(pos); | |
1378 | ||
d35258ef TH |
1379 | /* |
1380 | * Drain iff @kn was activated. This avoids draining and | |
1381 | * its lockdep annotations for nodes which have never been | |
1382 | * activated and allows embedding kernfs_remove() in create | |
1383 | * error paths without worrying about draining. | |
1384 | */ | |
1385 | if (kn->flags & KERNFS_ACTIVATED) | |
1386 | kernfs_drain(pos); | |
1387 | else | |
1388 | WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); | |
35beab06 TH |
1389 | |
1390 | /* | |
1391 | * kernfs_unlink_sibling() succeeds once per node. Use it | |
1392 | * to decide who's responsible for cleanups. | |
1393 | */ | |
1394 | if (!pos->parent || kernfs_unlink_sibling(pos)) { | |
1395 | struct kernfs_iattrs *ps_iattr = | |
1396 | pos->parent ? pos->parent->iattr : NULL; | |
1397 | ||
1398 | /* update timestamps on the parent */ | |
1399 | if (ps_iattr) { | |
05895219 OM |
1400 | ktime_get_real_ts64(&ps_iattr->ia_ctime); |
1401 | ps_iattr->ia_mtime = ps_iattr->ia_ctime; | |
35beab06 TH |
1402 | } |
1403 | ||
988cd7af | 1404 | kernfs_put(pos); |
35beab06 TH |
1405 | } |
1406 | ||
1407 | kernfs_put(pos); | |
1408 | } while (pos != kn); | |
fd7b9f7b TH |
1409 | } |
1410 | ||
1411 | /** | |
324a56e1 TH |
1412 | * kernfs_remove - remove a kernfs_node recursively |
1413 | * @kn: the kernfs_node to remove | |
fd7b9f7b | 1414 | * |
324a56e1 | 1415 | * Remove @kn along with all its subdirectories and files. |
fd7b9f7b | 1416 | */ |
324a56e1 | 1417 | void kernfs_remove(struct kernfs_node *kn) |
fd7b9f7b | 1418 | { |
ad8d8693 MK |
1419 | struct kernfs_root *root; |
1420 | ||
1421 | if (!kn) | |
1422 | return; | |
1423 | ||
1424 | root = kernfs_root(kn); | |
393c3714 MK |
1425 | |
1426 | down_write(&root->kernfs_rwsem); | |
988cd7af | 1427 | __kernfs_remove(kn); |
393c3714 | 1428 | up_write(&root->kernfs_rwsem); |
fd7b9f7b TH |
1429 | } |
1430 | ||
6b0afc2a TH |
1431 | /** |
1432 | * kernfs_break_active_protection - break out of active protection | |
1433 | * @kn: the self kernfs_node | |
1434 | * | |
1435 | * The caller must be running off of a kernfs operation which is invoked | |
1436 | * with an active reference - e.g. one of kernfs_ops. Each invocation of | |
1437 | * this function must also be matched with an invocation of | |
1438 | * kernfs_unbreak_active_protection(). | |
1439 | * | |
1440 | * This function releases the active reference of @kn the caller is | |
1441 | * holding. Once this function is called, @kn may be removed at any point | |
1442 | * and the caller is solely responsible for ensuring that the objects it | |
1443 | * dereferences are accessible. | |
1444 | */ | |
1445 | void kernfs_break_active_protection(struct kernfs_node *kn) | |
1446 | { | |
1447 | /* | |
1448 | * Take out ourself out of the active ref dependency chain. If | |
1449 | * we're called without an active ref, lockdep will complain. | |
1450 | */ | |
1451 | kernfs_put_active(kn); | |
1452 | } | |
1453 | ||
1454 | /** | |
1455 | * kernfs_unbreak_active_protection - undo kernfs_break_active_protection() | |
1456 | * @kn: the self kernfs_node | |
1457 | * | |
1458 | * If kernfs_break_active_protection() was called, this function must be | |
1459 | * invoked before finishing the kernfs operation. Note that while this | |
1460 | * function restores the active reference, it doesn't and can't actually | |
1461 | * restore the active protection - @kn may already or be in the process of | |
1462 | * being removed. Once kernfs_break_active_protection() is invoked, that | |
1463 | * protection is irreversibly gone for the kernfs operation instance. | |
1464 | * | |
1465 | * While this function may be called at any point after | |
1466 | * kernfs_break_active_protection() is invoked, its most useful location | |
1467 | * would be right before the enclosing kernfs operation returns. | |
1468 | */ | |
1469 | void kernfs_unbreak_active_protection(struct kernfs_node *kn) | |
1470 | { | |
1471 | /* | |
1472 | * @kn->active could be in any state; however, the increment we do | |
1473 | * here will be undone as soon as the enclosing kernfs operation | |
1474 | * finishes and this temporary bump can't break anything. If @kn | |
1475 | * is alive, nothing changes. If @kn is being deactivated, the | |
1476 | * soon-to-follow put will either finish deactivation or restore | |
1477 | * deactivated state. If @kn is already removed, the temporary | |
1478 | * bump is guaranteed to be gone before @kn is released. | |
1479 | */ | |
1480 | atomic_inc(&kn->active); | |
1481 | if (kernfs_lockdep(kn)) | |
1482 | rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_); | |
1483 | } | |
1484 | ||
1485 | /** | |
1486 | * kernfs_remove_self - remove a kernfs_node from its own method | |
1487 | * @kn: the self kernfs_node to remove | |
1488 | * | |
1489 | * The caller must be running off of a kernfs operation which is invoked | |
1490 | * with an active reference - e.g. one of kernfs_ops. This can be used to | |
1491 | * implement a file operation which deletes itself. | |
1492 | * | |
1493 | * For example, the "delete" file for a sysfs device directory can be | |
1494 | * implemented by invoking kernfs_remove_self() on the "delete" file | |
1495 | * itself. This function breaks the circular dependency of trying to | |
1496 | * deactivate self while holding an active ref itself. It isn't necessary | |
1497 | * to modify the usual removal path to use kernfs_remove_self(). The | |
1498 | * "delete" implementation can simply invoke kernfs_remove_self() on self | |
1499 | * before proceeding with the usual removal path. kernfs will ignore later | |
1500 | * kernfs_remove() on self. | |
1501 | * | |
1502 | * kernfs_remove_self() can be called multiple times concurrently on the | |
1503 | * same kernfs_node. Only the first one actually performs removal and | |
1504 | * returns %true. All others will wait until the kernfs operation which | |
1505 | * won self-removal finishes and return %false. Note that the losers wait | |
1506 | * for the completion of not only the winning kernfs_remove_self() but also | |
1507 | * the whole kernfs_ops which won the arbitration. This can be used to | |
1508 | * guarantee, for example, all concurrent writes to a "delete" file to | |
1509 | * finish only after the whole operation is complete. | |
1510 | */ | |
1511 | bool kernfs_remove_self(struct kernfs_node *kn) | |
1512 | { | |
1513 | bool ret; | |
393c3714 | 1514 | struct kernfs_root *root = kernfs_root(kn); |
6b0afc2a | 1515 | |
393c3714 | 1516 | down_write(&root->kernfs_rwsem); |
6b0afc2a TH |
1517 | kernfs_break_active_protection(kn); |
1518 | ||
1519 | /* | |
1520 | * SUICIDAL is used to arbitrate among competing invocations. Only | |
1521 | * the first one will actually perform removal. When the removal | |
1522 | * is complete, SUICIDED is set and the active ref is restored | |
7ba0273b IK |
1523 | * while kernfs_rwsem for held exclusive. The ones which lost |
1524 | * arbitration waits for SUICIDED && drained which can happen only | |
1525 | * after the enclosing kernfs operation which executed the winning | |
1526 | * instance of kernfs_remove_self() finished. | |
6b0afc2a TH |
1527 | */ |
1528 | if (!(kn->flags & KERNFS_SUICIDAL)) { | |
1529 | kn->flags |= KERNFS_SUICIDAL; | |
1530 | __kernfs_remove(kn); | |
1531 | kn->flags |= KERNFS_SUICIDED; | |
1532 | ret = true; | |
1533 | } else { | |
1534 | wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq; | |
1535 | DEFINE_WAIT(wait); | |
1536 | ||
1537 | while (true) { | |
1538 | prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE); | |
1539 | ||
1540 | if ((kn->flags & KERNFS_SUICIDED) && | |
1541 | atomic_read(&kn->active) == KN_DEACTIVATED_BIAS) | |
1542 | break; | |
1543 | ||
393c3714 | 1544 | up_write(&root->kernfs_rwsem); |
6b0afc2a | 1545 | schedule(); |
393c3714 | 1546 | down_write(&root->kernfs_rwsem); |
6b0afc2a TH |
1547 | } |
1548 | finish_wait(waitq, &wait); | |
1549 | WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb)); | |
1550 | ret = false; | |
1551 | } | |
1552 | ||
1553 | /* | |
7ba0273b IK |
1554 | * This must be done while kernfs_rwsem held exclusive; otherwise, |
1555 | * waiting for SUICIDED && deactivated could finish prematurely. | |
6b0afc2a TH |
1556 | */ |
1557 | kernfs_unbreak_active_protection(kn); | |
1558 | ||
393c3714 | 1559 | up_write(&root->kernfs_rwsem); |
6b0afc2a TH |
1560 | return ret; |
1561 | } | |
1562 | ||
fd7b9f7b | 1563 | /** |
324a56e1 TH |
1564 | * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it |
1565 | * @parent: parent of the target | |
1566 | * @name: name of the kernfs_node to remove | |
1567 | * @ns: namespace tag of the kernfs_node to remove | |
fd7b9f7b | 1568 | * |
324a56e1 TH |
1569 | * Look for the kernfs_node with @name and @ns under @parent and remove it. |
1570 | * Returns 0 on success, -ENOENT if such entry doesn't exist. | |
fd7b9f7b | 1571 | */ |
324a56e1 | 1572 | int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, |
fd7b9f7b TH |
1573 | const void *ns) |
1574 | { | |
324a56e1 | 1575 | struct kernfs_node *kn; |
393c3714 | 1576 | struct kernfs_root *root; |
fd7b9f7b | 1577 | |
324a56e1 | 1578 | if (!parent) { |
c637b8ac | 1579 | WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n", |
fd7b9f7b TH |
1580 | name); |
1581 | return -ENOENT; | |
1582 | } | |
1583 | ||
393c3714 MK |
1584 | root = kernfs_root(parent); |
1585 | down_write(&root->kernfs_rwsem); | |
fd7b9f7b | 1586 | |
324a56e1 TH |
1587 | kn = kernfs_find_ns(parent, name, ns); |
1588 | if (kn) | |
988cd7af | 1589 | __kernfs_remove(kn); |
fd7b9f7b | 1590 | |
393c3714 | 1591 | up_write(&root->kernfs_rwsem); |
fd7b9f7b | 1592 | |
324a56e1 | 1593 | if (kn) |
fd7b9f7b TH |
1594 | return 0; |
1595 | else | |
1596 | return -ENOENT; | |
1597 | } | |
1598 | ||
1599 | /** | |
1600 | * kernfs_rename_ns - move and rename a kernfs_node | |
324a56e1 | 1601 | * @kn: target node |
fd7b9f7b TH |
1602 | * @new_parent: new parent to put @sd under |
1603 | * @new_name: new name | |
1604 | * @new_ns: new namespace tag | |
1605 | */ | |
324a56e1 | 1606 | int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, |
fd7b9f7b TH |
1607 | const char *new_name, const void *new_ns) |
1608 | { | |
3eef34ad | 1609 | struct kernfs_node *old_parent; |
393c3714 | 1610 | struct kernfs_root *root; |
3eef34ad | 1611 | const char *old_name = NULL; |
fd7b9f7b TH |
1612 | int error; |
1613 | ||
3eef34ad TH |
1614 | /* can't move or rename root */ |
1615 | if (!kn->parent) | |
1616 | return -EINVAL; | |
1617 | ||
393c3714 MK |
1618 | root = kernfs_root(kn); |
1619 | down_write(&root->kernfs_rwsem); | |
798c75a0 | 1620 | |
d0ae3d43 | 1621 | error = -ENOENT; |
ea015218 EB |
1622 | if (!kernfs_active(kn) || !kernfs_active(new_parent) || |
1623 | (new_parent->flags & KERNFS_EMPTY_DIR)) | |
d0ae3d43 TH |
1624 | goto out; |
1625 | ||
fd7b9f7b | 1626 | error = 0; |
adc5e8b5 TH |
1627 | if ((kn->parent == new_parent) && (kn->ns == new_ns) && |
1628 | (strcmp(kn->name, new_name) == 0)) | |
798c75a0 | 1629 | goto out; /* nothing to rename */ |
fd7b9f7b TH |
1630 | |
1631 | error = -EEXIST; | |
1632 | if (kernfs_find_ns(new_parent, new_name, new_ns)) | |
798c75a0 | 1633 | goto out; |
fd7b9f7b | 1634 | |
324a56e1 | 1635 | /* rename kernfs_node */ |
adc5e8b5 | 1636 | if (strcmp(kn->name, new_name) != 0) { |
fd7b9f7b | 1637 | error = -ENOMEM; |
75287a67 | 1638 | new_name = kstrdup_const(new_name, GFP_KERNEL); |
fd7b9f7b | 1639 | if (!new_name) |
798c75a0 | 1640 | goto out; |
3eef34ad TH |
1641 | } else { |
1642 | new_name = NULL; | |
fd7b9f7b TH |
1643 | } |
1644 | ||
1645 | /* | |
1646 | * Move to the appropriate place in the appropriate directories rbtree. | |
1647 | */ | |
c637b8ac | 1648 | kernfs_unlink_sibling(kn); |
fd7b9f7b | 1649 | kernfs_get(new_parent); |
3eef34ad TH |
1650 | |
1651 | /* rename_lock protects ->parent and ->name accessors */ | |
1652 | spin_lock_irq(&kernfs_rename_lock); | |
1653 | ||
1654 | old_parent = kn->parent; | |
adc5e8b5 | 1655 | kn->parent = new_parent; |
3eef34ad TH |
1656 | |
1657 | kn->ns = new_ns; | |
1658 | if (new_name) { | |
dfeb0750 | 1659 | old_name = kn->name; |
3eef34ad TH |
1660 | kn->name = new_name; |
1661 | } | |
1662 | ||
1663 | spin_unlock_irq(&kernfs_rename_lock); | |
1664 | ||
9561a896 | 1665 | kn->hash = kernfs_name_hash(kn->name, kn->ns); |
c637b8ac | 1666 | kernfs_link_sibling(kn); |
fd7b9f7b | 1667 | |
3eef34ad | 1668 | kernfs_put(old_parent); |
75287a67 | 1669 | kfree_const(old_name); |
3eef34ad | 1670 | |
fd7b9f7b | 1671 | error = 0; |
798c75a0 | 1672 | out: |
393c3714 | 1673 | up_write(&root->kernfs_rwsem); |
fd7b9f7b TH |
1674 | return error; |
1675 | } | |
1676 | ||
21774fd8 | 1677 | /* Relationship between mode and the DT_xxx types */ |
324a56e1 | 1678 | static inline unsigned char dt_type(struct kernfs_node *kn) |
fd7b9f7b | 1679 | { |
adc5e8b5 | 1680 | return (kn->mode >> 12) & 15; |
fd7b9f7b TH |
1681 | } |
1682 | ||
c637b8ac | 1683 | static int kernfs_dir_fop_release(struct inode *inode, struct file *filp) |
fd7b9f7b TH |
1684 | { |
1685 | kernfs_put(filp->private_data); | |
1686 | return 0; | |
1687 | } | |
1688 | ||
c637b8ac | 1689 | static struct kernfs_node *kernfs_dir_pos(const void *ns, |
324a56e1 | 1690 | struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) |
fd7b9f7b TH |
1691 | { |
1692 | if (pos) { | |
81c173cb | 1693 | int valid = kernfs_active(pos) && |
798c75a0 | 1694 | pos->parent == parent && hash == pos->hash; |
fd7b9f7b TH |
1695 | kernfs_put(pos); |
1696 | if (!valid) | |
1697 | pos = NULL; | |
1698 | } | |
1699 | if (!pos && (hash > 1) && (hash < INT_MAX)) { | |
adc5e8b5 | 1700 | struct rb_node *node = parent->dir.children.rb_node; |
fd7b9f7b | 1701 | while (node) { |
324a56e1 | 1702 | pos = rb_to_kn(node); |
fd7b9f7b | 1703 | |
adc5e8b5 | 1704 | if (hash < pos->hash) |
fd7b9f7b | 1705 | node = node->rb_left; |
adc5e8b5 | 1706 | else if (hash > pos->hash) |
fd7b9f7b TH |
1707 | node = node->rb_right; |
1708 | else | |
1709 | break; | |
1710 | } | |
1711 | } | |
b9c9dad0 TH |
1712 | /* Skip over entries which are dying/dead or in the wrong namespace */ |
1713 | while (pos && (!kernfs_active(pos) || pos->ns != ns)) { | |
adc5e8b5 | 1714 | struct rb_node *node = rb_next(&pos->rb); |
fd7b9f7b TH |
1715 | if (!node) |
1716 | pos = NULL; | |
1717 | else | |
324a56e1 | 1718 | pos = rb_to_kn(node); |
fd7b9f7b TH |
1719 | } |
1720 | return pos; | |
1721 | } | |
1722 | ||
c637b8ac | 1723 | static struct kernfs_node *kernfs_dir_next_pos(const void *ns, |
324a56e1 | 1724 | struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos) |
fd7b9f7b | 1725 | { |
c637b8ac | 1726 | pos = kernfs_dir_pos(ns, parent, ino, pos); |
b9c9dad0 | 1727 | if (pos) { |
fd7b9f7b | 1728 | do { |
adc5e8b5 | 1729 | struct rb_node *node = rb_next(&pos->rb); |
fd7b9f7b TH |
1730 | if (!node) |
1731 | pos = NULL; | |
1732 | else | |
324a56e1 | 1733 | pos = rb_to_kn(node); |
b9c9dad0 TH |
1734 | } while (pos && (!kernfs_active(pos) || pos->ns != ns)); |
1735 | } | |
fd7b9f7b TH |
1736 | return pos; |
1737 | } | |
1738 | ||
c637b8ac | 1739 | static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) |
fd7b9f7b TH |
1740 | { |
1741 | struct dentry *dentry = file->f_path.dentry; | |
319ba91d | 1742 | struct kernfs_node *parent = kernfs_dentry_node(dentry); |
324a56e1 | 1743 | struct kernfs_node *pos = file->private_data; |
393c3714 | 1744 | struct kernfs_root *root; |
fd7b9f7b TH |
1745 | const void *ns = NULL; |
1746 | ||
1747 | if (!dir_emit_dots(file, ctx)) | |
1748 | return 0; | |
393c3714 MK |
1749 | |
1750 | root = kernfs_root(parent); | |
1751 | down_read(&root->kernfs_rwsem); | |
fd7b9f7b | 1752 | |
324a56e1 | 1753 | if (kernfs_ns_enabled(parent)) |
c525aadd | 1754 | ns = kernfs_info(dentry->d_sb)->ns; |
fd7b9f7b | 1755 | |
c637b8ac | 1756 | for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos); |
fd7b9f7b | 1757 | pos; |
c637b8ac | 1758 | pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) { |
adc5e8b5 | 1759 | const char *name = pos->name; |
fd7b9f7b TH |
1760 | unsigned int type = dt_type(pos); |
1761 | int len = strlen(name); | |
67c0496e | 1762 | ino_t ino = kernfs_ino(pos); |
fd7b9f7b | 1763 | |
adc5e8b5 | 1764 | ctx->pos = pos->hash; |
fd7b9f7b TH |
1765 | file->private_data = pos; |
1766 | kernfs_get(pos); | |
1767 | ||
393c3714 | 1768 | up_read(&root->kernfs_rwsem); |
fd7b9f7b TH |
1769 | if (!dir_emit(ctx, name, len, ino, type)) |
1770 | return 0; | |
393c3714 | 1771 | down_read(&root->kernfs_rwsem); |
fd7b9f7b | 1772 | } |
393c3714 | 1773 | up_read(&root->kernfs_rwsem); |
fd7b9f7b TH |
1774 | file->private_data = NULL; |
1775 | ctx->pos = INT_MAX; | |
1776 | return 0; | |
1777 | } | |
1778 | ||
a797bfc3 | 1779 | const struct file_operations kernfs_dir_fops = { |
fd7b9f7b | 1780 | .read = generic_read_dir, |
8cb0d2c1 | 1781 | .iterate_shared = kernfs_fop_readdir, |
c637b8ac | 1782 | .release = kernfs_dir_fop_release, |
8cb0d2c1 | 1783 | .llseek = generic_file_llseek, |
fd7b9f7b | 1784 | }; |