dir.c revision ba7443bc656e5236c316b2acacc8b551f872910f
1/* 2 * fs/kernfs/dir.c - kernfs directory implementation 3 * 4 * Copyright (c) 2001-3 Patrick Mochel 5 * Copyright (c) 2007 SUSE Linux Products GmbH 6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> 7 * 8 * This file is released under the GPLv2. 9 */ 10 11#include <linux/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 20DEFINE_MUTEX(sysfs_mutex); 21 22#define to_sysfs_dirent(X) rb_entry((X), struct sysfs_dirent, s_rb) 23 24static DEFINE_SPINLOCK(sysfs_ino_lock); 25static DEFINE_IDA(sysfs_ino_ida); 26 27/** 28 * sysfs_name_hash 29 * @name: Null terminated string to hash 30 * @ns: Namespace tag to hash 31 * 32 * Returns 31 bit hash of ns + name (so it fits in an off_t ) 33 */ 34static unsigned int sysfs_name_hash(const char *name, const void *ns) 35{ 36 unsigned long hash = init_name_hash(); 37 unsigned int len = strlen(name); 38 while (len--) 39 hash = partial_name_hash(*name++, hash); 40 hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31)); 41 hash &= 0x7fffffffU; 42 /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ 43 if (hash < 1) 44 hash += 2; 45 if (hash >= INT_MAX) 46 hash = INT_MAX - 1; 47 return hash; 48} 49 50static int sysfs_name_compare(unsigned int hash, const char *name, 51 const void *ns, const struct sysfs_dirent *sd) 52{ 53 if (hash != sd->s_hash) 54 return hash - sd->s_hash; 55 if (ns != sd->s_ns) 56 return ns - sd->s_ns; 57 return strcmp(name, sd->s_name); 58} 59 60static int sysfs_sd_compare(const struct sysfs_dirent *left, 61 const struct sysfs_dirent *right) 62{ 63 return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns, 64 right); 65} 66 67/** 68 * sysfs_link_sibling - link sysfs_dirent into sibling rbtree 69 * @sd: sysfs_dirent of interest 70 * 71 * Link @sd into its sibling rbtree which starts from 72 * sd->s_parent->s_dir.children. 73 * 74 * Locking: 75 * mutex_lock(sysfs_mutex) 76 * 77 * RETURNS: 78 * 0 on susccess -EEXIST on failure. 79 */ 80static int sysfs_link_sibling(struct sysfs_dirent *sd) 81{ 82 struct rb_node **node = &sd->s_parent->s_dir.children.rb_node; 83 struct rb_node *parent = NULL; 84 85 if (sysfs_type(sd) == SYSFS_DIR) 86 sd->s_parent->s_dir.subdirs++; 87 88 while (*node) { 89 struct sysfs_dirent *pos; 90 int result; 91 92 pos = to_sysfs_dirent(*node); 93 parent = *node; 94 result = sysfs_sd_compare(sd, pos); 95 if (result < 0) 96 node = &pos->s_rb.rb_left; 97 else if (result > 0) 98 node = &pos->s_rb.rb_right; 99 else 100 return -EEXIST; 101 } 102 /* add new node and rebalance the tree */ 103 rb_link_node(&sd->s_rb, parent, node); 104 rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children); 105 return 0; 106} 107 108/** 109 * sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree 110 * @sd: sysfs_dirent of interest 111 * 112 * Unlink @sd from its sibling rbtree which starts from 113 * sd->s_parent->s_dir.children. 114 * 115 * Locking: 116 * mutex_lock(sysfs_mutex) 117 */ 118static void sysfs_unlink_sibling(struct sysfs_dirent *sd) 119{ 120 if (sysfs_type(sd) == SYSFS_DIR) 121 sd->s_parent->s_dir.subdirs--; 122 123 rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children); 124} 125 126/** 127 * sysfs_get_active - get an active reference to sysfs_dirent 128 * @sd: sysfs_dirent to get an active reference to 129 * 130 * Get an active reference of @sd. This function is noop if @sd 131 * is NULL. 132 * 133 * RETURNS: 134 * Pointer to @sd on success, NULL on failure. 135 */ 136struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd) 137{ 138 if (unlikely(!sd)) 139 return NULL; 140 141 if (!atomic_inc_unless_negative(&sd->s_active)) 142 return NULL; 143 144 if (sd->s_flags & SYSFS_FLAG_LOCKDEP) 145 rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_); 146 return sd; 147} 148 149/** 150 * sysfs_put_active - put an active reference to sysfs_dirent 151 * @sd: sysfs_dirent to put an active reference to 152 * 153 * Put an active reference to @sd. This function is noop if @sd 154 * is NULL. 155 */ 156void sysfs_put_active(struct sysfs_dirent *sd) 157{ 158 int v; 159 160 if (unlikely(!sd)) 161 return; 162 163 if (sd->s_flags & SYSFS_FLAG_LOCKDEP) 164 rwsem_release(&sd->dep_map, 1, _RET_IP_); 165 v = atomic_dec_return(&sd->s_active); 166 if (likely(v != SD_DEACTIVATED_BIAS)) 167 return; 168 169 /* atomic_dec_return() is a mb(), we'll always see the updated 170 * sd->u.completion. 171 */ 172 complete(sd->u.completion); 173} 174 175/** 176 * sysfs_deactivate - deactivate sysfs_dirent 177 * @sd: sysfs_dirent to deactivate 178 * 179 * Deny new active references and drain existing ones. 180 */ 181static void sysfs_deactivate(struct sysfs_dirent *sd) 182{ 183 DECLARE_COMPLETION_ONSTACK(wait); 184 int v; 185 186 BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED)); 187 188 if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF)) 189 return; 190 191 sd->u.completion = (void *)&wait; 192 193 rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_); 194 /* atomic_add_return() is a mb(), put_active() will always see 195 * the updated sd->u.completion. 196 */ 197 v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active); 198 199 if (v != SD_DEACTIVATED_BIAS) { 200 lock_contended(&sd->dep_map, _RET_IP_); 201 wait_for_completion(&wait); 202 } 203 204 lock_acquired(&sd->dep_map, _RET_IP_); 205 rwsem_release(&sd->dep_map, 1, _RET_IP_); 206} 207 208static int sysfs_alloc_ino(unsigned int *pino) 209{ 210 int ino, rc; 211 212 retry: 213 spin_lock(&sysfs_ino_lock); 214 rc = ida_get_new_above(&sysfs_ino_ida, 1, &ino); 215 spin_unlock(&sysfs_ino_lock); 216 217 if (rc == -EAGAIN) { 218 if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL)) 219 goto retry; 220 rc = -ENOMEM; 221 } 222 223 *pino = ino; 224 return rc; 225} 226 227static void sysfs_free_ino(unsigned int ino) 228{ 229 spin_lock(&sysfs_ino_lock); 230 ida_remove(&sysfs_ino_ida, ino); 231 spin_unlock(&sysfs_ino_lock); 232} 233 234/** 235 * kernfs_get - get a reference count on a sysfs_dirent 236 * @sd: the target sysfs_dirent 237 */ 238void kernfs_get(struct sysfs_dirent *sd) 239{ 240 if (sd) { 241 WARN_ON(!atomic_read(&sd->s_count)); 242 atomic_inc(&sd->s_count); 243 } 244} 245EXPORT_SYMBOL_GPL(kernfs_get); 246 247/** 248 * kernfs_put - put a reference count on a sysfs_dirent 249 * @sd: the target sysfs_dirent 250 * 251 * Put a reference count of @sd and destroy it if it reached zero. 252 */ 253void kernfs_put(struct sysfs_dirent *sd) 254{ 255 struct sysfs_dirent *parent_sd; 256 struct kernfs_root *root; 257 258 if (!sd || !atomic_dec_and_test(&sd->s_count)) 259 return; 260 root = kernfs_root(sd); 261 repeat: 262 /* Moving/renaming is always done while holding reference. 263 * sd->s_parent won't change beneath us. 264 */ 265 parent_sd = sd->s_parent; 266 267 WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED), 268 "sysfs: free using entry: %s/%s\n", 269 parent_sd ? parent_sd->s_name : "", sd->s_name); 270 271 if (sysfs_type(sd) == SYSFS_KOBJ_LINK) 272 kernfs_put(sd->s_symlink.target_sd); 273 if (sysfs_type(sd) & SYSFS_COPY_NAME) 274 kfree(sd->s_name); 275 if (sd->s_iattr && sd->s_iattr->ia_secdata) 276 security_release_secctx(sd->s_iattr->ia_secdata, 277 sd->s_iattr->ia_secdata_len); 278 kfree(sd->s_iattr); 279 sysfs_free_ino(sd->s_ino); 280 kmem_cache_free(sysfs_dir_cachep, sd); 281 282 sd = parent_sd; 283 if (sd) { 284 if (atomic_dec_and_test(&sd->s_count)) 285 goto repeat; 286 } else { 287 /* just released the root sd, free @root too */ 288 kfree(root); 289 } 290} 291EXPORT_SYMBOL_GPL(kernfs_put); 292 293static int sysfs_dentry_delete(const struct dentry *dentry) 294{ 295 struct sysfs_dirent *sd = dentry->d_fsdata; 296 return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED)); 297} 298 299static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags) 300{ 301 struct sysfs_dirent *sd; 302 303 if (flags & LOOKUP_RCU) 304 return -ECHILD; 305 306 sd = dentry->d_fsdata; 307 mutex_lock(&sysfs_mutex); 308 309 /* The sysfs dirent has been deleted */ 310 if (sd->s_flags & SYSFS_FLAG_REMOVED) 311 goto out_bad; 312 313 /* The sysfs dirent has been moved? */ 314 if (dentry->d_parent->d_fsdata != sd->s_parent) 315 goto out_bad; 316 317 /* The sysfs dirent has been renamed */ 318 if (strcmp(dentry->d_name.name, sd->s_name) != 0) 319 goto out_bad; 320 321 /* The sysfs dirent has been moved to a different namespace */ 322 if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) && 323 sysfs_info(dentry->d_sb)->ns != sd->s_ns) 324 goto out_bad; 325 326 mutex_unlock(&sysfs_mutex); 327out_valid: 328 return 1; 329out_bad: 330 /* Remove the dentry from the dcache hashes. 331 * If this is a deleted dentry we use d_drop instead of d_delete 332 * so sysfs doesn't need to cope with negative dentries. 333 * 334 * If this is a dentry that has simply been renamed we 335 * use d_drop to remove it from the dcache lookup on its 336 * old parent. If this dentry persists later when a lookup 337 * is performed at its new name the dentry will be readded 338 * to the dcache hashes. 339 */ 340 mutex_unlock(&sysfs_mutex); 341 342 /* If we have submounts we must allow the vfs caches 343 * to lie about the state of the filesystem to prevent 344 * leaks and other nasty things. 345 */ 346 if (check_submounts_and_drop(dentry) != 0) 347 goto out_valid; 348 349 return 0; 350} 351 352static void sysfs_dentry_release(struct dentry *dentry) 353{ 354 kernfs_put(dentry->d_fsdata); 355} 356 357const struct dentry_operations sysfs_dentry_ops = { 358 .d_revalidate = sysfs_dentry_revalidate, 359 .d_delete = sysfs_dentry_delete, 360 .d_release = sysfs_dentry_release, 361}; 362 363struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type) 364{ 365 char *dup_name = NULL; 366 struct sysfs_dirent *sd; 367 368 if (type & SYSFS_COPY_NAME) { 369 name = dup_name = kstrdup(name, GFP_KERNEL); 370 if (!name) 371 return NULL; 372 } 373 374 sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL); 375 if (!sd) 376 goto err_out1; 377 378 if (sysfs_alloc_ino(&sd->s_ino)) 379 goto err_out2; 380 381 atomic_set(&sd->s_count, 1); 382 atomic_set(&sd->s_active, 0); 383 384 sd->s_name = name; 385 sd->s_mode = mode; 386 sd->s_flags = type | SYSFS_FLAG_REMOVED; 387 388 return sd; 389 390 err_out2: 391 kmem_cache_free(sysfs_dir_cachep, sd); 392 err_out1: 393 kfree(dup_name); 394 return NULL; 395} 396 397/** 398 * sysfs_addrm_start - prepare for sysfs_dirent add/remove 399 * @acxt: pointer to sysfs_addrm_cxt to be used 400 * 401 * This function is called when the caller is about to add or remove 402 * sysfs_dirent. This function acquires sysfs_mutex. @acxt is used 403 * to keep and pass context to other addrm functions. 404 * 405 * LOCKING: 406 * Kernel thread context (may sleep). sysfs_mutex is locked on 407 * return. 408 */ 409void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt) 410 __acquires(sysfs_mutex) 411{ 412 memset(acxt, 0, sizeof(*acxt)); 413 414 mutex_lock(&sysfs_mutex); 415} 416 417/** 418 * sysfs_add_one - add sysfs_dirent to parent without warning 419 * @acxt: addrm context to use 420 * @sd: sysfs_dirent to be added 421 * @parent_sd: the parent sysfs_dirent to add @sd to 422 * 423 * Get @parent_sd and set @sd->s_parent to it and increment nlink of 424 * the parent inode if @sd is a directory and link into the children 425 * list of the parent. 426 * 427 * This function should be called between calls to 428 * sysfs_addrm_start() and sysfs_addrm_finish() and should be 429 * passed the same @acxt as passed to sysfs_addrm_start(). 430 * 431 * LOCKING: 432 * Determined by sysfs_addrm_start(). 433 * 434 * RETURNS: 435 * 0 on success, -EEXIST if entry with the given name already 436 * exists. 437 */ 438int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd, 439 struct sysfs_dirent *parent_sd) 440{ 441 bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS; 442 struct sysfs_inode_attrs *ps_iattr; 443 int ret; 444 445 if (has_ns != (bool)sd->s_ns) { 446 WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n", 447 has_ns ? "required" : "invalid", 448 parent_sd->s_name, sd->s_name); 449 return -EINVAL; 450 } 451 452 if (sysfs_type(parent_sd) != SYSFS_DIR) 453 return -EINVAL; 454 455 sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns); 456 sd->s_parent = parent_sd; 457 kernfs_get(parent_sd); 458 459 ret = sysfs_link_sibling(sd); 460 if (ret) 461 return ret; 462 463 /* Update timestamps on the parent */ 464 ps_iattr = parent_sd->s_iattr; 465 if (ps_iattr) { 466 struct iattr *ps_iattrs = &ps_iattr->ia_iattr; 467 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; 468 } 469 470 /* Mark the entry added into directory tree */ 471 sd->s_flags &= ~SYSFS_FLAG_REMOVED; 472 473 return 0; 474} 475 476/** 477 * sysfs_remove_one - remove sysfs_dirent from parent 478 * @acxt: addrm context to use 479 * @sd: sysfs_dirent to be removed 480 * 481 * Mark @sd removed and drop nlink of parent inode if @sd is a 482 * directory. @sd is unlinked from the children list. 483 * 484 * This function should be called between calls to 485 * sysfs_addrm_start() and sysfs_addrm_finish() and should be 486 * passed the same @acxt as passed to sysfs_addrm_start(). 487 * 488 * LOCKING: 489 * Determined by sysfs_addrm_start(). 490 */ 491static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, 492 struct sysfs_dirent *sd) 493{ 494 struct sysfs_inode_attrs *ps_iattr; 495 496 /* 497 * Removal can be called multiple times on the same node. Only the 498 * first invocation is effective and puts the base ref. 499 */ 500 if (sd->s_flags & SYSFS_FLAG_REMOVED) 501 return; 502 503 if (sd->s_parent) { 504 sysfs_unlink_sibling(sd); 505 506 /* Update timestamps on the parent */ 507 ps_iattr = sd->s_parent->s_iattr; 508 if (ps_iattr) { 509 ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME; 510 ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME; 511 } 512 } 513 514 sd->s_flags |= SYSFS_FLAG_REMOVED; 515 sd->u.removed_list = acxt->removed; 516 acxt->removed = sd; 517} 518 519/** 520 * sysfs_addrm_finish - finish up sysfs_dirent add/remove 521 * @acxt: addrm context to finish up 522 * 523 * Finish up sysfs_dirent add/remove. Resources acquired by 524 * sysfs_addrm_start() are released and removed sysfs_dirents are 525 * cleaned up. 526 * 527 * LOCKING: 528 * sysfs_mutex is released. 529 */ 530void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) 531 __releases(sysfs_mutex) 532{ 533 /* release resources acquired by sysfs_addrm_start() */ 534 mutex_unlock(&sysfs_mutex); 535 536 /* kill removed sysfs_dirents */ 537 while (acxt->removed) { 538 struct sysfs_dirent *sd = acxt->removed; 539 540 acxt->removed = sd->u.removed_list; 541 542 sysfs_deactivate(sd); 543 sysfs_unmap_bin_file(sd); 544 kernfs_put(sd); 545 } 546} 547 548/** 549 * kernfs_find_ns - find sysfs_dirent with the given name 550 * @parent: sysfs_dirent to search under 551 * @name: name to look for 552 * @ns: the namespace tag to use 553 * 554 * Look for sysfs_dirent with name @name under @parent. Returns pointer to 555 * the found sysfs_dirent on success, %NULL on failure. 556 */ 557static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent, 558 const unsigned char *name, 559 const void *ns) 560{ 561 struct rb_node *node = parent->s_dir.children.rb_node; 562 bool has_ns = parent->s_flags & SYSFS_FLAG_NS; 563 unsigned int hash; 564 565 lockdep_assert_held(&sysfs_mutex); 566 567 if (has_ns != (bool)ns) { 568 WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n", 569 has_ns ? "required" : "invalid", 570 parent->s_name, name); 571 return NULL; 572 } 573 574 hash = sysfs_name_hash(name, ns); 575 while (node) { 576 struct sysfs_dirent *sd; 577 int result; 578 579 sd = to_sysfs_dirent(node); 580 result = sysfs_name_compare(hash, name, ns, sd); 581 if (result < 0) 582 node = node->rb_left; 583 else if (result > 0) 584 node = node->rb_right; 585 else 586 return sd; 587 } 588 return NULL; 589} 590 591/** 592 * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name 593 * @parent: sysfs_dirent to search under 594 * @name: name to look for 595 * @ns: the namespace tag to use 596 * 597 * Look for sysfs_dirent with name @name under @parent and get a reference 598 * if found. This function may sleep and returns pointer to the found 599 * sysfs_dirent on success, %NULL on failure. 600 */ 601struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent, 602 const char *name, const void *ns) 603{ 604 struct sysfs_dirent *sd; 605 606 mutex_lock(&sysfs_mutex); 607 sd = kernfs_find_ns(parent, name, ns); 608 kernfs_get(sd); 609 mutex_unlock(&sysfs_mutex); 610 611 return sd; 612} 613EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); 614 615/** 616 * kernfs_create_root - create a new kernfs hierarchy 617 * @priv: opaque data associated with the new directory 618 * 619 * Returns the root of the new hierarchy on success, ERR_PTR() value on 620 * failure. 621 */ 622struct kernfs_root *kernfs_create_root(void *priv) 623{ 624 struct kernfs_root *root; 625 struct sysfs_dirent *sd; 626 627 root = kzalloc(sizeof(*root), GFP_KERNEL); 628 if (!root) 629 return ERR_PTR(-ENOMEM); 630 631 sd = sysfs_new_dirent("", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR); 632 if (!sd) { 633 kfree(root); 634 return ERR_PTR(-ENOMEM); 635 } 636 637 sd->s_flags &= ~SYSFS_FLAG_REMOVED; 638 sd->priv = priv; 639 sd->s_dir.root = root; 640 641 root->sd = sd; 642 643 return root; 644} 645 646/** 647 * kernfs_destroy_root - destroy a kernfs hierarchy 648 * @root: root of the hierarchy to destroy 649 * 650 * Destroy the hierarchy anchored at @root by removing all existing 651 * directories and destroying @root. 652 */ 653void kernfs_destroy_root(struct kernfs_root *root) 654{ 655 kernfs_remove(root->sd); /* will also free @root */ 656} 657 658/** 659 * kernfs_create_dir_ns - create a directory 660 * @parent: parent in which to create a new directory 661 * @name: name of the new directory 662 * @priv: opaque data associated with the new directory 663 * @ns: optional namespace tag of the directory 664 * 665 * Returns the created node on success, ERR_PTR() value on failure. 666 */ 667struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent, 668 const char *name, void *priv, 669 const void *ns) 670{ 671 umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; 672 struct sysfs_addrm_cxt acxt; 673 struct sysfs_dirent *sd; 674 int rc; 675 676 /* allocate */ 677 sd = sysfs_new_dirent(name, mode, SYSFS_DIR); 678 if (!sd) 679 return ERR_PTR(-ENOMEM); 680 681 sd->s_dir.root = parent->s_dir.root; 682 sd->s_ns = ns; 683 sd->priv = priv; 684 685 /* link in */ 686 sysfs_addrm_start(&acxt); 687 rc = sysfs_add_one(&acxt, sd, parent); 688 sysfs_addrm_finish(&acxt); 689 690 if (!rc) 691 return sd; 692 693 kernfs_put(sd); 694 return ERR_PTR(rc); 695} 696 697static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry, 698 unsigned int flags) 699{ 700 struct dentry *ret = NULL; 701 struct dentry *parent = dentry->d_parent; 702 struct sysfs_dirent *parent_sd = parent->d_fsdata; 703 struct sysfs_dirent *sd; 704 struct inode *inode; 705 const void *ns = NULL; 706 707 mutex_lock(&sysfs_mutex); 708 709 if (parent_sd->s_flags & SYSFS_FLAG_NS) 710 ns = sysfs_info(dir->i_sb)->ns; 711 712 sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns); 713 714 /* no such entry */ 715 if (!sd) { 716 ret = ERR_PTR(-ENOENT); 717 goto out_unlock; 718 } 719 kernfs_get(sd); 720 dentry->d_fsdata = sd; 721 722 /* attach dentry and inode */ 723 inode = sysfs_get_inode(dir->i_sb, sd); 724 if (!inode) { 725 ret = ERR_PTR(-ENOMEM); 726 goto out_unlock; 727 } 728 729 /* instantiate and hash dentry */ 730 ret = d_materialise_unique(dentry, inode); 731 out_unlock: 732 mutex_unlock(&sysfs_mutex); 733 return ret; 734} 735 736const struct inode_operations sysfs_dir_inode_operations = { 737 .lookup = sysfs_lookup, 738 .permission = sysfs_permission, 739 .setattr = sysfs_setattr, 740 .getattr = sysfs_getattr, 741 .setxattr = sysfs_setxattr, 742}; 743 744static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos) 745{ 746 struct sysfs_dirent *last; 747 748 while (true) { 749 struct rb_node *rbn; 750 751 last = pos; 752 753 if (sysfs_type(pos) != SYSFS_DIR) 754 break; 755 756 rbn = rb_first(&pos->s_dir.children); 757 if (!rbn) 758 break; 759 760 pos = to_sysfs_dirent(rbn); 761 } 762 763 return last; 764} 765 766/** 767 * sysfs_next_descendant_post - find the next descendant for post-order walk 768 * @pos: the current position (%NULL to initiate traversal) 769 * @root: sysfs_dirent whose descendants to walk 770 * 771 * Find the next descendant to visit for post-order traversal of @root's 772 * descendants. @root is included in the iteration and the last node to be 773 * visited. 774 */ 775static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos, 776 struct sysfs_dirent *root) 777{ 778 struct rb_node *rbn; 779 780 lockdep_assert_held(&sysfs_mutex); 781 782 /* if first iteration, visit leftmost descendant which may be root */ 783 if (!pos) 784 return sysfs_leftmost_descendant(root); 785 786 /* if we visited @root, we're done */ 787 if (pos == root) 788 return NULL; 789 790 /* if there's an unvisited sibling, visit its leftmost descendant */ 791 rbn = rb_next(&pos->s_rb); 792 if (rbn) 793 return sysfs_leftmost_descendant(to_sysfs_dirent(rbn)); 794 795 /* no sibling left, visit parent */ 796 return pos->s_parent; 797} 798 799static void __kernfs_remove(struct sysfs_addrm_cxt *acxt, 800 struct sysfs_dirent *sd) 801{ 802 struct sysfs_dirent *pos, *next; 803 804 if (!sd) 805 return; 806 807 pr_debug("sysfs %s: removing\n", sd->s_name); 808 809 next = NULL; 810 do { 811 pos = next; 812 next = sysfs_next_descendant_post(pos, sd); 813 if (pos) 814 sysfs_remove_one(acxt, pos); 815 } while (next); 816} 817 818/** 819 * kernfs_remove - remove a sysfs_dirent recursively 820 * @sd: the sysfs_dirent to remove 821 * 822 * Remove @sd along with all its subdirectories and files. 823 */ 824void kernfs_remove(struct sysfs_dirent *sd) 825{ 826 struct sysfs_addrm_cxt acxt; 827 828 sysfs_addrm_start(&acxt); 829 __kernfs_remove(&acxt, sd); 830 sysfs_addrm_finish(&acxt); 831} 832 833/** 834 * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it 835 * @dir_sd: parent of the target 836 * @name: name of the sysfs_dirent to remove 837 * @ns: namespace tag of the sysfs_dirent to remove 838 * 839 * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove 840 * it. Returns 0 on success, -ENOENT if such entry doesn't exist. 841 */ 842int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name, 843 const void *ns) 844{ 845 struct sysfs_addrm_cxt acxt; 846 struct sysfs_dirent *sd; 847 848 if (!dir_sd) { 849 WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n", 850 name); 851 return -ENOENT; 852 } 853 854 sysfs_addrm_start(&acxt); 855 856 sd = kernfs_find_ns(dir_sd, name, ns); 857 if (sd) 858 __kernfs_remove(&acxt, sd); 859 860 sysfs_addrm_finish(&acxt); 861 862 if (sd) 863 return 0; 864 else 865 return -ENOENT; 866} 867 868/** 869 * kernfs_rename_ns - move and rename a kernfs_node 870 * @sd: target node 871 * @new_parent: new parent to put @sd under 872 * @new_name: new name 873 * @new_ns: new namespace tag 874 */ 875int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent, 876 const char *new_name, const void *new_ns) 877{ 878 int error; 879 880 mutex_lock(&sysfs_mutex); 881 882 error = 0; 883 if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) && 884 (strcmp(sd->s_name, new_name) == 0)) 885 goto out; /* nothing to rename */ 886 887 error = -EEXIST; 888 if (kernfs_find_ns(new_parent, new_name, new_ns)) 889 goto out; 890 891 /* rename sysfs_dirent */ 892 if (strcmp(sd->s_name, new_name) != 0) { 893 error = -ENOMEM; 894 new_name = kstrdup(new_name, GFP_KERNEL); 895 if (!new_name) 896 goto out; 897 898 kfree(sd->s_name); 899 sd->s_name = new_name; 900 } 901 902 /* 903 * Move to the appropriate place in the appropriate directories rbtree. 904 */ 905 sysfs_unlink_sibling(sd); 906 kernfs_get(new_parent); 907 kernfs_put(sd->s_parent); 908 sd->s_ns = new_ns; 909 sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns); 910 sd->s_parent = new_parent; 911 sysfs_link_sibling(sd); 912 913 error = 0; 914 out: 915 mutex_unlock(&sysfs_mutex); 916 return error; 917} 918 919/** 920 * kernfs_enable_ns - enable namespace under a directory 921 * @sd: directory of interest, should be empty 922 * 923 * This is to be called right after @sd is created to enable namespace 924 * under it. All children of @sd must have non-NULL namespace tags and 925 * only the ones which match the super_block's tag will be visible. 926 */ 927void kernfs_enable_ns(struct sysfs_dirent *sd) 928{ 929 WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR); 930 WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children)); 931 sd->s_flags |= SYSFS_FLAG_NS; 932} 933 934/* Relationship between s_mode and the DT_xxx types */ 935static inline unsigned char dt_type(struct sysfs_dirent *sd) 936{ 937 return (sd->s_mode >> 12) & 15; 938} 939 940static int sysfs_dir_release(struct inode *inode, struct file *filp) 941{ 942 kernfs_put(filp->private_data); 943 return 0; 944} 945 946static struct sysfs_dirent *sysfs_dir_pos(const void *ns, 947 struct sysfs_dirent *parent_sd, loff_t hash, struct sysfs_dirent *pos) 948{ 949 if (pos) { 950 int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) && 951 pos->s_parent == parent_sd && 952 hash == pos->s_hash; 953 kernfs_put(pos); 954 if (!valid) 955 pos = NULL; 956 } 957 if (!pos && (hash > 1) && (hash < INT_MAX)) { 958 struct rb_node *node = parent_sd->s_dir.children.rb_node; 959 while (node) { 960 pos = to_sysfs_dirent(node); 961 962 if (hash < pos->s_hash) 963 node = node->rb_left; 964 else if (hash > pos->s_hash) 965 node = node->rb_right; 966 else 967 break; 968 } 969 } 970 /* Skip over entries in the wrong namespace */ 971 while (pos && pos->s_ns != ns) { 972 struct rb_node *node = rb_next(&pos->s_rb); 973 if (!node) 974 pos = NULL; 975 else 976 pos = to_sysfs_dirent(node); 977 } 978 return pos; 979} 980 981static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns, 982 struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos) 983{ 984 pos = sysfs_dir_pos(ns, parent_sd, ino, pos); 985 if (pos) 986 do { 987 struct rb_node *node = rb_next(&pos->s_rb); 988 if (!node) 989 pos = NULL; 990 else 991 pos = to_sysfs_dirent(node); 992 } while (pos && pos->s_ns != ns); 993 return pos; 994} 995 996static int sysfs_readdir(struct file *file, struct dir_context *ctx) 997{ 998 struct dentry *dentry = file->f_path.dentry; 999 struct sysfs_dirent *parent_sd = dentry->d_fsdata; 1000 struct sysfs_dirent *pos = file->private_data; 1001 const void *ns = NULL; 1002 1003 if (!dir_emit_dots(file, ctx)) 1004 return 0; 1005 mutex_lock(&sysfs_mutex); 1006 1007 if (parent_sd->s_flags & SYSFS_FLAG_NS) 1008 ns = sysfs_info(dentry->d_sb)->ns; 1009 1010 for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos); 1011 pos; 1012 pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) { 1013 const char *name = pos->s_name; 1014 unsigned int type = dt_type(pos); 1015 int len = strlen(name); 1016 ino_t ino = pos->s_ino; 1017 1018 ctx->pos = pos->s_hash; 1019 file->private_data = pos; 1020 kernfs_get(pos); 1021 1022 mutex_unlock(&sysfs_mutex); 1023 if (!dir_emit(ctx, name, len, ino, type)) 1024 return 0; 1025 mutex_lock(&sysfs_mutex); 1026 } 1027 mutex_unlock(&sysfs_mutex); 1028 file->private_data = NULL; 1029 ctx->pos = INT_MAX; 1030 return 0; 1031} 1032 1033static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence) 1034{ 1035 struct inode *inode = file_inode(file); 1036 loff_t ret; 1037 1038 mutex_lock(&inode->i_mutex); 1039 ret = generic_file_llseek(file, offset, whence); 1040 mutex_unlock(&inode->i_mutex); 1041 1042 return ret; 1043} 1044 1045const struct file_operations sysfs_dir_operations = { 1046 .read = generic_read_dir, 1047 .iterate = sysfs_readdir, 1048 .release = sysfs_dir_release, 1049 .llseek = sysfs_dir_llseek, 1050}; 1051