dir.c revision bc755553df9ab33f389c1a0a8bd0b4f4646e80ef
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 24/** 25 * sysfs_name_hash 26 * @name: Null terminated string to hash 27 * @ns: Namespace tag to hash 28 * 29 * Returns 31 bit hash of ns + name (so it fits in an off_t ) 30 */ 31static unsigned int sysfs_name_hash(const char *name, const void *ns) 32{ 33 unsigned long hash = init_name_hash(); 34 unsigned int len = strlen(name); 35 while (len--) 36 hash = partial_name_hash(*name++, hash); 37 hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31)); 38 hash &= 0x7fffffffU; 39 /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ 40 if (hash < 1) 41 hash += 2; 42 if (hash >= INT_MAX) 43 hash = INT_MAX - 1; 44 return hash; 45} 46 47static int sysfs_name_compare(unsigned int hash, const char *name, 48 const void *ns, const struct sysfs_dirent *sd) 49{ 50 if (hash != sd->s_hash) 51 return hash - sd->s_hash; 52 if (ns != sd->s_ns) 53 return ns - sd->s_ns; 54 return strcmp(name, sd->s_name); 55} 56 57static int sysfs_sd_compare(const struct sysfs_dirent *left, 58 const struct sysfs_dirent *right) 59{ 60 return sysfs_name_compare(left->s_hash, left->s_name, left->s_ns, 61 right); 62} 63 64/** 65 * sysfs_link_sibling - link sysfs_dirent into sibling rbtree 66 * @sd: sysfs_dirent of interest 67 * 68 * Link @sd into its sibling rbtree which starts from 69 * sd->s_parent->s_dir.children. 70 * 71 * Locking: 72 * mutex_lock(sysfs_mutex) 73 * 74 * RETURNS: 75 * 0 on susccess -EEXIST on failure. 76 */ 77static int sysfs_link_sibling(struct sysfs_dirent *sd) 78{ 79 struct rb_node **node = &sd->s_parent->s_dir.children.rb_node; 80 struct rb_node *parent = NULL; 81 82 if (sysfs_type(sd) == SYSFS_DIR) 83 sd->s_parent->s_dir.subdirs++; 84 85 while (*node) { 86 struct sysfs_dirent *pos; 87 int result; 88 89 pos = to_sysfs_dirent(*node); 90 parent = *node; 91 result = sysfs_sd_compare(sd, pos); 92 if (result < 0) 93 node = &pos->s_rb.rb_left; 94 else if (result > 0) 95 node = &pos->s_rb.rb_right; 96 else 97 return -EEXIST; 98 } 99 /* add new node and rebalance the tree */ 100 rb_link_node(&sd->s_rb, parent, node); 101 rb_insert_color(&sd->s_rb, &sd->s_parent->s_dir.children); 102 return 0; 103} 104 105/** 106 * sysfs_unlink_sibling - unlink sysfs_dirent from sibling rbtree 107 * @sd: sysfs_dirent of interest 108 * 109 * Unlink @sd from its sibling rbtree which starts from 110 * sd->s_parent->s_dir.children. 111 * 112 * Locking: 113 * mutex_lock(sysfs_mutex) 114 */ 115static void sysfs_unlink_sibling(struct sysfs_dirent *sd) 116{ 117 if (sysfs_type(sd) == SYSFS_DIR) 118 sd->s_parent->s_dir.subdirs--; 119 120 rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children); 121} 122 123/** 124 * sysfs_get_active - get an active reference to sysfs_dirent 125 * @sd: sysfs_dirent to get an active reference to 126 * 127 * Get an active reference of @sd. This function is noop if @sd 128 * is NULL. 129 * 130 * RETURNS: 131 * Pointer to @sd on success, NULL on failure. 132 */ 133struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd) 134{ 135 if (unlikely(!sd)) 136 return NULL; 137 138 if (!atomic_inc_unless_negative(&sd->s_active)) 139 return NULL; 140 141 if (sd->s_flags & SYSFS_FLAG_LOCKDEP) 142 rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_); 143 return sd; 144} 145 146/** 147 * sysfs_put_active - put an active reference to sysfs_dirent 148 * @sd: sysfs_dirent to put an active reference to 149 * 150 * Put an active reference to @sd. This function is noop if @sd 151 * is NULL. 152 */ 153void sysfs_put_active(struct sysfs_dirent *sd) 154{ 155 int v; 156 157 if (unlikely(!sd)) 158 return; 159 160 if (sd->s_flags & SYSFS_FLAG_LOCKDEP) 161 rwsem_release(&sd->dep_map, 1, _RET_IP_); 162 v = atomic_dec_return(&sd->s_active); 163 if (likely(v != SD_DEACTIVATED_BIAS)) 164 return; 165 166 /* atomic_dec_return() is a mb(), we'll always see the updated 167 * sd->u.completion. 168 */ 169 complete(sd->u.completion); 170} 171 172/** 173 * sysfs_deactivate - deactivate sysfs_dirent 174 * @sd: sysfs_dirent to deactivate 175 * 176 * Deny new active references and drain existing ones. 177 */ 178static void sysfs_deactivate(struct sysfs_dirent *sd) 179{ 180 DECLARE_COMPLETION_ONSTACK(wait); 181 int v; 182 183 BUG_ON(!(sd->s_flags & SYSFS_FLAG_REMOVED)); 184 185 if (!(sysfs_type(sd) & SYSFS_ACTIVE_REF)) 186 return; 187 188 sd->u.completion = (void *)&wait; 189 190 rwsem_acquire(&sd->dep_map, 0, 0, _RET_IP_); 191 /* atomic_add_return() is a mb(), put_active() will always see 192 * the updated sd->u.completion. 193 */ 194 v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active); 195 196 if (v != SD_DEACTIVATED_BIAS) { 197 lock_contended(&sd->dep_map, _RET_IP_); 198 wait_for_completion(&wait); 199 } 200 201 lock_acquired(&sd->dep_map, _RET_IP_); 202 rwsem_release(&sd->dep_map, 1, _RET_IP_); 203} 204 205/** 206 * kernfs_get - get a reference count on a sysfs_dirent 207 * @sd: the target sysfs_dirent 208 */ 209void kernfs_get(struct sysfs_dirent *sd) 210{ 211 if (sd) { 212 WARN_ON(!atomic_read(&sd->s_count)); 213 atomic_inc(&sd->s_count); 214 } 215} 216EXPORT_SYMBOL_GPL(kernfs_get); 217 218/** 219 * kernfs_put - put a reference count on a sysfs_dirent 220 * @sd: the target sysfs_dirent 221 * 222 * Put a reference count of @sd and destroy it if it reached zero. 223 */ 224void kernfs_put(struct sysfs_dirent *sd) 225{ 226 struct sysfs_dirent *parent_sd; 227 struct kernfs_root *root; 228 229 if (!sd || !atomic_dec_and_test(&sd->s_count)) 230 return; 231 root = kernfs_root(sd); 232 repeat: 233 /* Moving/renaming is always done while holding reference. 234 * sd->s_parent won't change beneath us. 235 */ 236 parent_sd = sd->s_parent; 237 238 WARN(!(sd->s_flags & SYSFS_FLAG_REMOVED), 239 "sysfs: free using entry: %s/%s\n", 240 parent_sd ? parent_sd->s_name : "", sd->s_name); 241 242 if (sysfs_type(sd) == SYSFS_KOBJ_LINK) 243 kernfs_put(sd->s_symlink.target_sd); 244 if (sysfs_type(sd) & SYSFS_COPY_NAME) 245 kfree(sd->s_name); 246 if (sd->s_iattr && sd->s_iattr->ia_secdata) 247 security_release_secctx(sd->s_iattr->ia_secdata, 248 sd->s_iattr->ia_secdata_len); 249 kfree(sd->s_iattr); 250 ida_simple_remove(&root->ino_ida, sd->s_ino); 251 kmem_cache_free(sysfs_dir_cachep, sd); 252 253 sd = parent_sd; 254 if (sd) { 255 if (atomic_dec_and_test(&sd->s_count)) 256 goto repeat; 257 } else { 258 /* just released the root sd, free @root too */ 259 ida_destroy(&root->ino_ida); 260 kfree(root); 261 } 262} 263EXPORT_SYMBOL_GPL(kernfs_put); 264 265static int sysfs_dentry_delete(const struct dentry *dentry) 266{ 267 struct sysfs_dirent *sd = dentry->d_fsdata; 268 return !(sd && !(sd->s_flags & SYSFS_FLAG_REMOVED)); 269} 270 271static int sysfs_dentry_revalidate(struct dentry *dentry, unsigned int flags) 272{ 273 struct sysfs_dirent *sd; 274 275 if (flags & LOOKUP_RCU) 276 return -ECHILD; 277 278 sd = dentry->d_fsdata; 279 mutex_lock(&sysfs_mutex); 280 281 /* The sysfs dirent has been deleted */ 282 if (sd->s_flags & SYSFS_FLAG_REMOVED) 283 goto out_bad; 284 285 /* The sysfs dirent has been moved? */ 286 if (dentry->d_parent->d_fsdata != sd->s_parent) 287 goto out_bad; 288 289 /* The sysfs dirent has been renamed */ 290 if (strcmp(dentry->d_name.name, sd->s_name) != 0) 291 goto out_bad; 292 293 /* The sysfs dirent has been moved to a different namespace */ 294 if (sd->s_parent && (sd->s_parent->s_flags & SYSFS_FLAG_NS) && 295 sysfs_info(dentry->d_sb)->ns != sd->s_ns) 296 goto out_bad; 297 298 mutex_unlock(&sysfs_mutex); 299out_valid: 300 return 1; 301out_bad: 302 /* Remove the dentry from the dcache hashes. 303 * If this is a deleted dentry we use d_drop instead of d_delete 304 * so sysfs doesn't need to cope with negative dentries. 305 * 306 * If this is a dentry that has simply been renamed we 307 * use d_drop to remove it from the dcache lookup on its 308 * old parent. If this dentry persists later when a lookup 309 * is performed at its new name the dentry will be readded 310 * to the dcache hashes. 311 */ 312 mutex_unlock(&sysfs_mutex); 313 314 /* If we have submounts we must allow the vfs caches 315 * to lie about the state of the filesystem to prevent 316 * leaks and other nasty things. 317 */ 318 if (check_submounts_and_drop(dentry) != 0) 319 goto out_valid; 320 321 return 0; 322} 323 324static void sysfs_dentry_release(struct dentry *dentry) 325{ 326 kernfs_put(dentry->d_fsdata); 327} 328 329const struct dentry_operations sysfs_dentry_ops = { 330 .d_revalidate = sysfs_dentry_revalidate, 331 .d_delete = sysfs_dentry_delete, 332 .d_release = sysfs_dentry_release, 333}; 334 335struct sysfs_dirent *sysfs_new_dirent(struct kernfs_root *root, 336 const char *name, umode_t mode, int type) 337{ 338 char *dup_name = NULL; 339 struct sysfs_dirent *sd; 340 int ret; 341 342 if (type & SYSFS_COPY_NAME) { 343 name = dup_name = kstrdup(name, GFP_KERNEL); 344 if (!name) 345 return NULL; 346 } 347 348 sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL); 349 if (!sd) 350 goto err_out1; 351 352 ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL); 353 if (ret < 0) 354 goto err_out2; 355 sd->s_ino = ret; 356 357 atomic_set(&sd->s_count, 1); 358 atomic_set(&sd->s_active, 0); 359 360 sd->s_name = name; 361 sd->s_mode = mode; 362 sd->s_flags = type | SYSFS_FLAG_REMOVED; 363 364 return sd; 365 366 err_out2: 367 kmem_cache_free(sysfs_dir_cachep, sd); 368 err_out1: 369 kfree(dup_name); 370 return NULL; 371} 372 373/** 374 * sysfs_addrm_start - prepare for sysfs_dirent add/remove 375 * @acxt: pointer to sysfs_addrm_cxt to be used 376 * 377 * This function is called when the caller is about to add or remove 378 * sysfs_dirent. This function acquires sysfs_mutex. @acxt is used 379 * to keep and pass context to other addrm functions. 380 * 381 * LOCKING: 382 * Kernel thread context (may sleep). sysfs_mutex is locked on 383 * return. 384 */ 385void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt) 386 __acquires(sysfs_mutex) 387{ 388 memset(acxt, 0, sizeof(*acxt)); 389 390 mutex_lock(&sysfs_mutex); 391} 392 393/** 394 * sysfs_add_one - add sysfs_dirent to parent without warning 395 * @acxt: addrm context to use 396 * @sd: sysfs_dirent to be added 397 * @parent_sd: the parent sysfs_dirent to add @sd to 398 * 399 * Get @parent_sd and set @sd->s_parent to it and increment nlink of 400 * the parent inode if @sd is a directory and link into the children 401 * list of the parent. 402 * 403 * This function should be called between calls to 404 * sysfs_addrm_start() and sysfs_addrm_finish() and should be 405 * passed the same @acxt as passed to sysfs_addrm_start(). 406 * 407 * LOCKING: 408 * Determined by sysfs_addrm_start(). 409 * 410 * RETURNS: 411 * 0 on success, -EEXIST if entry with the given name already 412 * exists. 413 */ 414int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd, 415 struct sysfs_dirent *parent_sd) 416{ 417 bool has_ns = parent_sd->s_flags & SYSFS_FLAG_NS; 418 struct sysfs_inode_attrs *ps_iattr; 419 int ret; 420 421 if (has_ns != (bool)sd->s_ns) { 422 WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n", 423 has_ns ? "required" : "invalid", 424 parent_sd->s_name, sd->s_name); 425 return -EINVAL; 426 } 427 428 if (sysfs_type(parent_sd) != SYSFS_DIR) 429 return -EINVAL; 430 431 sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns); 432 sd->s_parent = parent_sd; 433 kernfs_get(parent_sd); 434 435 ret = sysfs_link_sibling(sd); 436 if (ret) 437 return ret; 438 439 /* Update timestamps on the parent */ 440 ps_iattr = parent_sd->s_iattr; 441 if (ps_iattr) { 442 struct iattr *ps_iattrs = &ps_iattr->ia_iattr; 443 ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; 444 } 445 446 /* Mark the entry added into directory tree */ 447 sd->s_flags &= ~SYSFS_FLAG_REMOVED; 448 449 return 0; 450} 451 452/** 453 * sysfs_remove_one - remove sysfs_dirent from parent 454 * @acxt: addrm context to use 455 * @sd: sysfs_dirent to be removed 456 * 457 * Mark @sd removed and drop nlink of parent inode if @sd is a 458 * directory. @sd is unlinked from the children list. 459 * 460 * This function should be called between calls to 461 * sysfs_addrm_start() and sysfs_addrm_finish() and should be 462 * passed the same @acxt as passed to sysfs_addrm_start(). 463 * 464 * LOCKING: 465 * Determined by sysfs_addrm_start(). 466 */ 467static void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, 468 struct sysfs_dirent *sd) 469{ 470 struct sysfs_inode_attrs *ps_iattr; 471 472 /* 473 * Removal can be called multiple times on the same node. Only the 474 * first invocation is effective and puts the base ref. 475 */ 476 if (sd->s_flags & SYSFS_FLAG_REMOVED) 477 return; 478 479 if (sd->s_parent) { 480 sysfs_unlink_sibling(sd); 481 482 /* Update timestamps on the parent */ 483 ps_iattr = sd->s_parent->s_iattr; 484 if (ps_iattr) { 485 ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME; 486 ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME; 487 } 488 } 489 490 sd->s_flags |= SYSFS_FLAG_REMOVED; 491 sd->u.removed_list = acxt->removed; 492 acxt->removed = sd; 493} 494 495/** 496 * sysfs_addrm_finish - finish up sysfs_dirent add/remove 497 * @acxt: addrm context to finish up 498 * 499 * Finish up sysfs_dirent add/remove. Resources acquired by 500 * sysfs_addrm_start() are released and removed sysfs_dirents are 501 * cleaned up. 502 * 503 * LOCKING: 504 * sysfs_mutex is released. 505 */ 506void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) 507 __releases(sysfs_mutex) 508{ 509 /* release resources acquired by sysfs_addrm_start() */ 510 mutex_unlock(&sysfs_mutex); 511 512 /* kill removed sysfs_dirents */ 513 while (acxt->removed) { 514 struct sysfs_dirent *sd = acxt->removed; 515 516 acxt->removed = sd->u.removed_list; 517 518 sysfs_deactivate(sd); 519 sysfs_unmap_bin_file(sd); 520 kernfs_put(sd); 521 } 522} 523 524/** 525 * kernfs_find_ns - find sysfs_dirent with the given name 526 * @parent: sysfs_dirent to search under 527 * @name: name to look for 528 * @ns: the namespace tag to use 529 * 530 * Look for sysfs_dirent with name @name under @parent. Returns pointer to 531 * the found sysfs_dirent on success, %NULL on failure. 532 */ 533static struct sysfs_dirent *kernfs_find_ns(struct sysfs_dirent *parent, 534 const unsigned char *name, 535 const void *ns) 536{ 537 struct rb_node *node = parent->s_dir.children.rb_node; 538 bool has_ns = parent->s_flags & SYSFS_FLAG_NS; 539 unsigned int hash; 540 541 lockdep_assert_held(&sysfs_mutex); 542 543 if (has_ns != (bool)ns) { 544 WARN(1, KERN_WARNING "sysfs: ns %s in '%s' for '%s'\n", 545 has_ns ? "required" : "invalid", 546 parent->s_name, name); 547 return NULL; 548 } 549 550 hash = sysfs_name_hash(name, ns); 551 while (node) { 552 struct sysfs_dirent *sd; 553 int result; 554 555 sd = to_sysfs_dirent(node); 556 result = sysfs_name_compare(hash, name, ns, sd); 557 if (result < 0) 558 node = node->rb_left; 559 else if (result > 0) 560 node = node->rb_right; 561 else 562 return sd; 563 } 564 return NULL; 565} 566 567/** 568 * kernfs_find_and_get_ns - find and get sysfs_dirent with the given name 569 * @parent: sysfs_dirent to search under 570 * @name: name to look for 571 * @ns: the namespace tag to use 572 * 573 * Look for sysfs_dirent with name @name under @parent and get a reference 574 * if found. This function may sleep and returns pointer to the found 575 * sysfs_dirent on success, %NULL on failure. 576 */ 577struct sysfs_dirent *kernfs_find_and_get_ns(struct sysfs_dirent *parent, 578 const char *name, const void *ns) 579{ 580 struct sysfs_dirent *sd; 581 582 mutex_lock(&sysfs_mutex); 583 sd = kernfs_find_ns(parent, name, ns); 584 kernfs_get(sd); 585 mutex_unlock(&sysfs_mutex); 586 587 return sd; 588} 589EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); 590 591/** 592 * kernfs_create_root - create a new kernfs hierarchy 593 * @priv: opaque data associated with the new directory 594 * 595 * Returns the root of the new hierarchy on success, ERR_PTR() value on 596 * failure. 597 */ 598struct kernfs_root *kernfs_create_root(void *priv) 599{ 600 struct kernfs_root *root; 601 struct sysfs_dirent *sd; 602 603 root = kzalloc(sizeof(*root), GFP_KERNEL); 604 if (!root) 605 return ERR_PTR(-ENOMEM); 606 607 ida_init(&root->ino_ida); 608 609 sd = sysfs_new_dirent(root, "", S_IFDIR | S_IRUGO | S_IXUGO, SYSFS_DIR); 610 if (!sd) { 611 ida_destroy(&root->ino_ida); 612 kfree(root); 613 return ERR_PTR(-ENOMEM); 614 } 615 616 sd->s_flags &= ~SYSFS_FLAG_REMOVED; 617 sd->priv = priv; 618 sd->s_dir.root = root; 619 620 root->sd = sd; 621 622 return root; 623} 624 625/** 626 * kernfs_destroy_root - destroy a kernfs hierarchy 627 * @root: root of the hierarchy to destroy 628 * 629 * Destroy the hierarchy anchored at @root by removing all existing 630 * directories and destroying @root. 631 */ 632void kernfs_destroy_root(struct kernfs_root *root) 633{ 634 kernfs_remove(root->sd); /* will also free @root */ 635} 636 637/** 638 * kernfs_create_dir_ns - create a directory 639 * @parent: parent in which to create a new directory 640 * @name: name of the new directory 641 * @priv: opaque data associated with the new directory 642 * @ns: optional namespace tag of the directory 643 * 644 * Returns the created node on success, ERR_PTR() value on failure. 645 */ 646struct sysfs_dirent *kernfs_create_dir_ns(struct sysfs_dirent *parent, 647 const char *name, void *priv, 648 const void *ns) 649{ 650 umode_t mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; 651 struct sysfs_addrm_cxt acxt; 652 struct sysfs_dirent *sd; 653 int rc; 654 655 /* allocate */ 656 sd = sysfs_new_dirent(kernfs_root(parent), name, mode, SYSFS_DIR); 657 if (!sd) 658 return ERR_PTR(-ENOMEM); 659 660 sd->s_dir.root = parent->s_dir.root; 661 sd->s_ns = ns; 662 sd->priv = priv; 663 664 /* link in */ 665 sysfs_addrm_start(&acxt); 666 rc = sysfs_add_one(&acxt, sd, parent); 667 sysfs_addrm_finish(&acxt); 668 669 if (!rc) 670 return sd; 671 672 kernfs_put(sd); 673 return ERR_PTR(rc); 674} 675 676static struct dentry *sysfs_lookup(struct inode *dir, struct dentry *dentry, 677 unsigned int flags) 678{ 679 struct dentry *ret = NULL; 680 struct dentry *parent = dentry->d_parent; 681 struct sysfs_dirent *parent_sd = parent->d_fsdata; 682 struct sysfs_dirent *sd; 683 struct inode *inode; 684 const void *ns = NULL; 685 686 mutex_lock(&sysfs_mutex); 687 688 if (parent_sd->s_flags & SYSFS_FLAG_NS) 689 ns = sysfs_info(dir->i_sb)->ns; 690 691 sd = kernfs_find_ns(parent_sd, dentry->d_name.name, ns); 692 693 /* no such entry */ 694 if (!sd) { 695 ret = ERR_PTR(-ENOENT); 696 goto out_unlock; 697 } 698 kernfs_get(sd); 699 dentry->d_fsdata = sd; 700 701 /* attach dentry and inode */ 702 inode = sysfs_get_inode(dir->i_sb, sd); 703 if (!inode) { 704 ret = ERR_PTR(-ENOMEM); 705 goto out_unlock; 706 } 707 708 /* instantiate and hash dentry */ 709 ret = d_materialise_unique(dentry, inode); 710 out_unlock: 711 mutex_unlock(&sysfs_mutex); 712 return ret; 713} 714 715const struct inode_operations sysfs_dir_inode_operations = { 716 .lookup = sysfs_lookup, 717 .permission = sysfs_permission, 718 .setattr = sysfs_setattr, 719 .getattr = sysfs_getattr, 720 .setxattr = sysfs_setxattr, 721}; 722 723static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos) 724{ 725 struct sysfs_dirent *last; 726 727 while (true) { 728 struct rb_node *rbn; 729 730 last = pos; 731 732 if (sysfs_type(pos) != SYSFS_DIR) 733 break; 734 735 rbn = rb_first(&pos->s_dir.children); 736 if (!rbn) 737 break; 738 739 pos = to_sysfs_dirent(rbn); 740 } 741 742 return last; 743} 744 745/** 746 * sysfs_next_descendant_post - find the next descendant for post-order walk 747 * @pos: the current position (%NULL to initiate traversal) 748 * @root: sysfs_dirent whose descendants to walk 749 * 750 * Find the next descendant to visit for post-order traversal of @root's 751 * descendants. @root is included in the iteration and the last node to be 752 * visited. 753 */ 754static struct sysfs_dirent *sysfs_next_descendant_post(struct sysfs_dirent *pos, 755 struct sysfs_dirent *root) 756{ 757 struct rb_node *rbn; 758 759 lockdep_assert_held(&sysfs_mutex); 760 761 /* if first iteration, visit leftmost descendant which may be root */ 762 if (!pos) 763 return sysfs_leftmost_descendant(root); 764 765 /* if we visited @root, we're done */ 766 if (pos == root) 767 return NULL; 768 769 /* if there's an unvisited sibling, visit its leftmost descendant */ 770 rbn = rb_next(&pos->s_rb); 771 if (rbn) 772 return sysfs_leftmost_descendant(to_sysfs_dirent(rbn)); 773 774 /* no sibling left, visit parent */ 775 return pos->s_parent; 776} 777 778static void __kernfs_remove(struct sysfs_addrm_cxt *acxt, 779 struct sysfs_dirent *sd) 780{ 781 struct sysfs_dirent *pos, *next; 782 783 if (!sd) 784 return; 785 786 pr_debug("sysfs %s: removing\n", sd->s_name); 787 788 next = NULL; 789 do { 790 pos = next; 791 next = sysfs_next_descendant_post(pos, sd); 792 if (pos) 793 sysfs_remove_one(acxt, pos); 794 } while (next); 795} 796 797/** 798 * kernfs_remove - remove a sysfs_dirent recursively 799 * @sd: the sysfs_dirent to remove 800 * 801 * Remove @sd along with all its subdirectories and files. 802 */ 803void kernfs_remove(struct sysfs_dirent *sd) 804{ 805 struct sysfs_addrm_cxt acxt; 806 807 sysfs_addrm_start(&acxt); 808 __kernfs_remove(&acxt, sd); 809 sysfs_addrm_finish(&acxt); 810} 811 812/** 813 * kernfs_remove_by_name_ns - find a sysfs_dirent by name and remove it 814 * @dir_sd: parent of the target 815 * @name: name of the sysfs_dirent to remove 816 * @ns: namespace tag of the sysfs_dirent to remove 817 * 818 * Look for the sysfs_dirent with @name and @ns under @dir_sd and remove 819 * it. Returns 0 on success, -ENOENT if such entry doesn't exist. 820 */ 821int kernfs_remove_by_name_ns(struct sysfs_dirent *dir_sd, const char *name, 822 const void *ns) 823{ 824 struct sysfs_addrm_cxt acxt; 825 struct sysfs_dirent *sd; 826 827 if (!dir_sd) { 828 WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n", 829 name); 830 return -ENOENT; 831 } 832 833 sysfs_addrm_start(&acxt); 834 835 sd = kernfs_find_ns(dir_sd, name, ns); 836 if (sd) 837 __kernfs_remove(&acxt, sd); 838 839 sysfs_addrm_finish(&acxt); 840 841 if (sd) 842 return 0; 843 else 844 return -ENOENT; 845} 846 847/** 848 * kernfs_rename_ns - move and rename a kernfs_node 849 * @sd: target node 850 * @new_parent: new parent to put @sd under 851 * @new_name: new name 852 * @new_ns: new namespace tag 853 */ 854int kernfs_rename_ns(struct sysfs_dirent *sd, struct sysfs_dirent *new_parent, 855 const char *new_name, const void *new_ns) 856{ 857 int error; 858 859 mutex_lock(&sysfs_mutex); 860 861 error = 0; 862 if ((sd->s_parent == new_parent) && (sd->s_ns == new_ns) && 863 (strcmp(sd->s_name, new_name) == 0)) 864 goto out; /* nothing to rename */ 865 866 error = -EEXIST; 867 if (kernfs_find_ns(new_parent, new_name, new_ns)) 868 goto out; 869 870 /* rename sysfs_dirent */ 871 if (strcmp(sd->s_name, new_name) != 0) { 872 error = -ENOMEM; 873 new_name = kstrdup(new_name, GFP_KERNEL); 874 if (!new_name) 875 goto out; 876 877 kfree(sd->s_name); 878 sd->s_name = new_name; 879 } 880 881 /* 882 * Move to the appropriate place in the appropriate directories rbtree. 883 */ 884 sysfs_unlink_sibling(sd); 885 kernfs_get(new_parent); 886 kernfs_put(sd->s_parent); 887 sd->s_ns = new_ns; 888 sd->s_hash = sysfs_name_hash(sd->s_name, sd->s_ns); 889 sd->s_parent = new_parent; 890 sysfs_link_sibling(sd); 891 892 error = 0; 893 out: 894 mutex_unlock(&sysfs_mutex); 895 return error; 896} 897 898/** 899 * kernfs_enable_ns - enable namespace under a directory 900 * @sd: directory of interest, should be empty 901 * 902 * This is to be called right after @sd is created to enable namespace 903 * under it. All children of @sd must have non-NULL namespace tags and 904 * only the ones which match the super_block's tag will be visible. 905 */ 906void kernfs_enable_ns(struct sysfs_dirent *sd) 907{ 908 WARN_ON_ONCE(sysfs_type(sd) != SYSFS_DIR); 909 WARN_ON_ONCE(!RB_EMPTY_ROOT(&sd->s_dir.children)); 910 sd->s_flags |= SYSFS_FLAG_NS; 911} 912 913/* Relationship between s_mode and the DT_xxx types */ 914static inline unsigned char dt_type(struct sysfs_dirent *sd) 915{ 916 return (sd->s_mode >> 12) & 15; 917} 918 919static int sysfs_dir_release(struct inode *inode, struct file *filp) 920{ 921 kernfs_put(filp->private_data); 922 return 0; 923} 924 925static struct sysfs_dirent *sysfs_dir_pos(const void *ns, 926 struct sysfs_dirent *parent_sd, loff_t hash, struct sysfs_dirent *pos) 927{ 928 if (pos) { 929 int valid = !(pos->s_flags & SYSFS_FLAG_REMOVED) && 930 pos->s_parent == parent_sd && 931 hash == pos->s_hash; 932 kernfs_put(pos); 933 if (!valid) 934 pos = NULL; 935 } 936 if (!pos && (hash > 1) && (hash < INT_MAX)) { 937 struct rb_node *node = parent_sd->s_dir.children.rb_node; 938 while (node) { 939 pos = to_sysfs_dirent(node); 940 941 if (hash < pos->s_hash) 942 node = node->rb_left; 943 else if (hash > pos->s_hash) 944 node = node->rb_right; 945 else 946 break; 947 } 948 } 949 /* Skip over entries in the wrong namespace */ 950 while (pos && pos->s_ns != ns) { 951 struct rb_node *node = rb_next(&pos->s_rb); 952 if (!node) 953 pos = NULL; 954 else 955 pos = to_sysfs_dirent(node); 956 } 957 return pos; 958} 959 960static struct sysfs_dirent *sysfs_dir_next_pos(const void *ns, 961 struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos) 962{ 963 pos = sysfs_dir_pos(ns, parent_sd, ino, pos); 964 if (pos) 965 do { 966 struct rb_node *node = rb_next(&pos->s_rb); 967 if (!node) 968 pos = NULL; 969 else 970 pos = to_sysfs_dirent(node); 971 } while (pos && pos->s_ns != ns); 972 return pos; 973} 974 975static int sysfs_readdir(struct file *file, struct dir_context *ctx) 976{ 977 struct dentry *dentry = file->f_path.dentry; 978 struct sysfs_dirent *parent_sd = dentry->d_fsdata; 979 struct sysfs_dirent *pos = file->private_data; 980 const void *ns = NULL; 981 982 if (!dir_emit_dots(file, ctx)) 983 return 0; 984 mutex_lock(&sysfs_mutex); 985 986 if (parent_sd->s_flags & SYSFS_FLAG_NS) 987 ns = sysfs_info(dentry->d_sb)->ns; 988 989 for (pos = sysfs_dir_pos(ns, parent_sd, ctx->pos, pos); 990 pos; 991 pos = sysfs_dir_next_pos(ns, parent_sd, ctx->pos, pos)) { 992 const char *name = pos->s_name; 993 unsigned int type = dt_type(pos); 994 int len = strlen(name); 995 ino_t ino = pos->s_ino; 996 997 ctx->pos = pos->s_hash; 998 file->private_data = pos; 999 kernfs_get(pos); 1000 1001 mutex_unlock(&sysfs_mutex); 1002 if (!dir_emit(ctx, name, len, ino, type)) 1003 return 0; 1004 mutex_lock(&sysfs_mutex); 1005 } 1006 mutex_unlock(&sysfs_mutex); 1007 file->private_data = NULL; 1008 ctx->pos = INT_MAX; 1009 return 0; 1010} 1011 1012static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence) 1013{ 1014 struct inode *inode = file_inode(file); 1015 loff_t ret; 1016 1017 mutex_lock(&inode->i_mutex); 1018 ret = generic_file_llseek(file, offset, whence); 1019 mutex_unlock(&inode->i_mutex); 1020 1021 return ret; 1022} 1023 1024const struct file_operations sysfs_dir_operations = { 1025 .read = generic_read_dir, 1026 .iterate = sysfs_readdir, 1027 .release = sysfs_dir_release, 1028 .llseek = sysfs_dir_llseek, 1029}; 1030