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