1 /* 2 * Copyright (C) 2011 STRATO. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19 #include <linux/vmalloc.h> 20 #include "ctree.h" 21 #include "disk-io.h" 22 #include "backref.h" 23 #include "ulist.h" 24 #include "transaction.h" 25 #include "delayed-ref.h" 26 #include "locking.h" 27 28 /* Just an arbitrary number so we can be sure this happened */ 29 #define BACKREF_FOUND_SHARED 6 30 31 struct extent_inode_elem { 32 u64 inum; 33 u64 offset; 34 struct extent_inode_elem *next; 35 }; 36 37 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb, 38 struct btrfs_file_extent_item *fi, 39 u64 extent_item_pos, 40 struct extent_inode_elem **eie) 41 { 42 u64 offset = 0; 43 struct extent_inode_elem *e; 44 45 if (!btrfs_file_extent_compression(eb, fi) && 46 !btrfs_file_extent_encryption(eb, fi) && 47 !btrfs_file_extent_other_encoding(eb, fi)) { 48 u64 data_offset; 49 u64 data_len; 50 51 data_offset = btrfs_file_extent_offset(eb, fi); 52 data_len = btrfs_file_extent_num_bytes(eb, fi); 53 54 if (extent_item_pos < data_offset || 55 extent_item_pos >= data_offset + data_len) 56 return 1; 57 offset = extent_item_pos - data_offset; 58 } 59 60 e = kmalloc(sizeof(*e), GFP_NOFS); 61 if (!e) 62 return -ENOMEM; 63 64 e->next = *eie; 65 e->inum = key->objectid; 66 e->offset = key->offset + offset; 67 *eie = e; 68 69 return 0; 70 } 71 72 static void free_inode_elem_list(struct extent_inode_elem *eie) 73 { 74 struct extent_inode_elem *eie_next; 75 76 for (; eie; eie = eie_next) { 77 eie_next = eie->next; 78 kfree(eie); 79 } 80 } 81 82 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte, 83 u64 extent_item_pos, 84 struct extent_inode_elem **eie) 85 { 86 u64 disk_byte; 87 struct btrfs_key key; 88 struct btrfs_file_extent_item *fi; 89 int slot; 90 int nritems; 91 int extent_type; 92 int ret; 93 94 /* 95 * from the shared data ref, we only have the leaf but we need 96 * the key. thus, we must look into all items and see that we 97 * find one (some) with a reference to our extent item. 98 */ 99 nritems = btrfs_header_nritems(eb); 100 for (slot = 0; slot < nritems; ++slot) { 101 btrfs_item_key_to_cpu(eb, &key, slot); 102 if (key.type != BTRFS_EXTENT_DATA_KEY) 103 continue; 104 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); 105 extent_type = btrfs_file_extent_type(eb, fi); 106 if (extent_type == BTRFS_FILE_EXTENT_INLINE) 107 continue; 108 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */ 109 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); 110 if (disk_byte != wanted_disk_byte) 111 continue; 112 113 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie); 114 if (ret < 0) 115 return ret; 116 } 117 118 return 0; 119 } 120 121 /* 122 * this structure records all encountered refs on the way up to the root 123 */ 124 struct __prelim_ref { 125 struct list_head list; 126 u64 root_id; 127 struct btrfs_key key_for_search; 128 int level; 129 int count; 130 struct extent_inode_elem *inode_list; 131 u64 parent; 132 u64 wanted_disk_byte; 133 }; 134 135 static struct kmem_cache *btrfs_prelim_ref_cache; 136 137 int __init btrfs_prelim_ref_init(void) 138 { 139 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref", 140 sizeof(struct __prelim_ref), 141 0, 142 SLAB_MEM_SPREAD, 143 NULL); 144 if (!btrfs_prelim_ref_cache) 145 return -ENOMEM; 146 return 0; 147 } 148 149 void btrfs_prelim_ref_exit(void) 150 { 151 kmem_cache_destroy(btrfs_prelim_ref_cache); 152 } 153 154 /* 155 * the rules for all callers of this function are: 156 * - obtaining the parent is the goal 157 * - if you add a key, you must know that it is a correct key 158 * - if you cannot add the parent or a correct key, then we will look into the 159 * block later to set a correct key 160 * 161 * delayed refs 162 * ============ 163 * backref type | shared | indirect | shared | indirect 164 * information | tree | tree | data | data 165 * --------------------+--------+----------+--------+---------- 166 * parent logical | y | - | - | - 167 * key to resolve | - | y | y | y 168 * tree block logical | - | - | - | - 169 * root for resolving | y | y | y | y 170 * 171 * - column 1: we've the parent -> done 172 * - column 2, 3, 4: we use the key to find the parent 173 * 174 * on disk refs (inline or keyed) 175 * ============================== 176 * backref type | shared | indirect | shared | indirect 177 * information | tree | tree | data | data 178 * --------------------+--------+----------+--------+---------- 179 * parent logical | y | - | y | - 180 * key to resolve | - | - | - | y 181 * tree block logical | y | y | y | y 182 * root for resolving | - | y | y | y 183 * 184 * - column 1, 3: we've the parent -> done 185 * - column 2: we take the first key from the block to find the parent 186 * (see __add_missing_keys) 187 * - column 4: we use the key to find the parent 188 * 189 * additional information that's available but not required to find the parent 190 * block might help in merging entries to gain some speed. 191 */ 192 193 static int __add_prelim_ref(struct list_head *head, u64 root_id, 194 struct btrfs_key *key, int level, 195 u64 parent, u64 wanted_disk_byte, int count, 196 gfp_t gfp_mask) 197 { 198 struct __prelim_ref *ref; 199 200 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID) 201 return 0; 202 203 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask); 204 if (!ref) 205 return -ENOMEM; 206 207 ref->root_id = root_id; 208 if (key) { 209 ref->key_for_search = *key; 210 /* 211 * We can often find data backrefs with an offset that is too 212 * large (>= LLONG_MAX, maximum allowed file offset) due to 213 * underflows when subtracting a file's offset with the data 214 * offset of its corresponding extent data item. This can 215 * happen for example in the clone ioctl. 216 * So if we detect such case we set the search key's offset to 217 * zero to make sure we will find the matching file extent item 218 * at add_all_parents(), otherwise we will miss it because the 219 * offset taken form the backref is much larger then the offset 220 * of the file extent item. This can make us scan a very large 221 * number of file extent items, but at least it will not make 222 * us miss any. 223 * This is an ugly workaround for a behaviour that should have 224 * never existed, but it does and a fix for the clone ioctl 225 * would touch a lot of places, cause backwards incompatibility 226 * and would not fix the problem for extents cloned with older 227 * kernels. 228 */ 229 if (ref->key_for_search.type == BTRFS_EXTENT_DATA_KEY && 230 ref->key_for_search.offset >= LLONG_MAX) 231 ref->key_for_search.offset = 0; 232 } else { 233 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search)); 234 } 235 236 ref->inode_list = NULL; 237 ref->level = level; 238 ref->count = count; 239 ref->parent = parent; 240 ref->wanted_disk_byte = wanted_disk_byte; 241 list_add_tail(&ref->list, head); 242 243 return 0; 244 } 245 246 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, 247 struct ulist *parents, struct __prelim_ref *ref, 248 int level, u64 time_seq, const u64 *extent_item_pos, 249 u64 total_refs) 250 { 251 int ret = 0; 252 int slot; 253 struct extent_buffer *eb; 254 struct btrfs_key key; 255 struct btrfs_key *key_for_search = &ref->key_for_search; 256 struct btrfs_file_extent_item *fi; 257 struct extent_inode_elem *eie = NULL, *old = NULL; 258 u64 disk_byte; 259 u64 wanted_disk_byte = ref->wanted_disk_byte; 260 u64 count = 0; 261 262 if (level != 0) { 263 eb = path->nodes[level]; 264 ret = ulist_add(parents, eb->start, 0, GFP_NOFS); 265 if (ret < 0) 266 return ret; 267 return 0; 268 } 269 270 /* 271 * We normally enter this function with the path already pointing to 272 * the first item to check. But sometimes, we may enter it with 273 * slot==nritems. In that case, go to the next leaf before we continue. 274 */ 275 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { 276 if (time_seq == (u64)-1) 277 ret = btrfs_next_leaf(root, path); 278 else 279 ret = btrfs_next_old_leaf(root, path, time_seq); 280 } 281 282 while (!ret && count < total_refs) { 283 eb = path->nodes[0]; 284 slot = path->slots[0]; 285 286 btrfs_item_key_to_cpu(eb, &key, slot); 287 288 if (key.objectid != key_for_search->objectid || 289 key.type != BTRFS_EXTENT_DATA_KEY) 290 break; 291 292 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); 293 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); 294 295 if (disk_byte == wanted_disk_byte) { 296 eie = NULL; 297 old = NULL; 298 count++; 299 if (extent_item_pos) { 300 ret = check_extent_in_eb(&key, eb, fi, 301 *extent_item_pos, 302 &eie); 303 if (ret < 0) 304 break; 305 } 306 if (ret > 0) 307 goto next; 308 ret = ulist_add_merge_ptr(parents, eb->start, 309 eie, (void **)&old, GFP_NOFS); 310 if (ret < 0) 311 break; 312 if (!ret && extent_item_pos) { 313 while (old->next) 314 old = old->next; 315 old->next = eie; 316 } 317 eie = NULL; 318 } 319 next: 320 if (time_seq == (u64)-1) 321 ret = btrfs_next_item(root, path); 322 else 323 ret = btrfs_next_old_item(root, path, time_seq); 324 } 325 326 if (ret > 0) 327 ret = 0; 328 else if (ret < 0) 329 free_inode_elem_list(eie); 330 return ret; 331 } 332 333 /* 334 * resolve an indirect backref in the form (root_id, key, level) 335 * to a logical address 336 */ 337 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info, 338 struct btrfs_path *path, u64 time_seq, 339 struct __prelim_ref *ref, 340 struct ulist *parents, 341 const u64 *extent_item_pos, u64 total_refs) 342 { 343 struct btrfs_root *root; 344 struct btrfs_key root_key; 345 struct extent_buffer *eb; 346 int ret = 0; 347 int root_level; 348 int level = ref->level; 349 int index; 350 351 root_key.objectid = ref->root_id; 352 root_key.type = BTRFS_ROOT_ITEM_KEY; 353 root_key.offset = (u64)-1; 354 355 index = srcu_read_lock(&fs_info->subvol_srcu); 356 357 root = btrfs_get_fs_root(fs_info, &root_key, false); 358 if (IS_ERR(root)) { 359 srcu_read_unlock(&fs_info->subvol_srcu, index); 360 ret = PTR_ERR(root); 361 goto out; 362 } 363 364 if (btrfs_is_testing(fs_info)) { 365 srcu_read_unlock(&fs_info->subvol_srcu, index); 366 ret = -ENOENT; 367 goto out; 368 } 369 370 if (path->search_commit_root) 371 root_level = btrfs_header_level(root->commit_root); 372 else if (time_seq == (u64)-1) 373 root_level = btrfs_header_level(root->node); 374 else 375 root_level = btrfs_old_root_level(root, time_seq); 376 377 if (root_level + 1 == level) { 378 srcu_read_unlock(&fs_info->subvol_srcu, index); 379 goto out; 380 } 381 382 path->lowest_level = level; 383 if (time_seq == (u64)-1) 384 ret = btrfs_search_slot(NULL, root, &ref->key_for_search, path, 385 0, 0); 386 else 387 ret = btrfs_search_old_slot(root, &ref->key_for_search, path, 388 time_seq); 389 390 /* root node has been locked, we can release @subvol_srcu safely here */ 391 srcu_read_unlock(&fs_info->subvol_srcu, index); 392 393 pr_debug("search slot in root %llu (level %d, ref count %d) returned " 394 "%d for key (%llu %u %llu)\n", 395 ref->root_id, level, ref->count, ret, 396 ref->key_for_search.objectid, ref->key_for_search.type, 397 ref->key_for_search.offset); 398 if (ret < 0) 399 goto out; 400 401 eb = path->nodes[level]; 402 while (!eb) { 403 if (WARN_ON(!level)) { 404 ret = 1; 405 goto out; 406 } 407 level--; 408 eb = path->nodes[level]; 409 } 410 411 ret = add_all_parents(root, path, parents, ref, level, time_seq, 412 extent_item_pos, total_refs); 413 out: 414 path->lowest_level = 0; 415 btrfs_release_path(path); 416 return ret; 417 } 418 419 /* 420 * resolve all indirect backrefs from the list 421 */ 422 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info, 423 struct btrfs_path *path, u64 time_seq, 424 struct list_head *head, 425 const u64 *extent_item_pos, u64 total_refs, 426 u64 root_objectid) 427 { 428 int err; 429 int ret = 0; 430 struct __prelim_ref *ref; 431 struct __prelim_ref *ref_safe; 432 struct __prelim_ref *new_ref; 433 struct ulist *parents; 434 struct ulist_node *node; 435 struct ulist_iterator uiter; 436 437 parents = ulist_alloc(GFP_NOFS); 438 if (!parents) 439 return -ENOMEM; 440 441 /* 442 * _safe allows us to insert directly after the current item without 443 * iterating over the newly inserted items. 444 * we're also allowed to re-assign ref during iteration. 445 */ 446 list_for_each_entry_safe(ref, ref_safe, head, list) { 447 if (ref->parent) /* already direct */ 448 continue; 449 if (ref->count == 0) 450 continue; 451 if (root_objectid && ref->root_id != root_objectid) { 452 ret = BACKREF_FOUND_SHARED; 453 goto out; 454 } 455 err = __resolve_indirect_ref(fs_info, path, time_seq, ref, 456 parents, extent_item_pos, 457 total_refs); 458 /* 459 * we can only tolerate ENOENT,otherwise,we should catch error 460 * and return directly. 461 */ 462 if (err == -ENOENT) { 463 continue; 464 } else if (err) { 465 ret = err; 466 goto out; 467 } 468 469 /* we put the first parent into the ref at hand */ 470 ULIST_ITER_INIT(&uiter); 471 node = ulist_next(parents, &uiter); 472 ref->parent = node ? node->val : 0; 473 ref->inode_list = node ? 474 (struct extent_inode_elem *)(uintptr_t)node->aux : NULL; 475 476 /* additional parents require new refs being added here */ 477 while ((node = ulist_next(parents, &uiter))) { 478 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache, 479 GFP_NOFS); 480 if (!new_ref) { 481 ret = -ENOMEM; 482 goto out; 483 } 484 memcpy(new_ref, ref, sizeof(*ref)); 485 new_ref->parent = node->val; 486 new_ref->inode_list = (struct extent_inode_elem *) 487 (uintptr_t)node->aux; 488 list_add(&new_ref->list, &ref->list); 489 } 490 ulist_reinit(parents); 491 } 492 out: 493 ulist_free(parents); 494 return ret; 495 } 496 497 static inline int ref_for_same_block(struct __prelim_ref *ref1, 498 struct __prelim_ref *ref2) 499 { 500 if (ref1->level != ref2->level) 501 return 0; 502 if (ref1->root_id != ref2->root_id) 503 return 0; 504 if (ref1->key_for_search.type != ref2->key_for_search.type) 505 return 0; 506 if (ref1->key_for_search.objectid != ref2->key_for_search.objectid) 507 return 0; 508 if (ref1->key_for_search.offset != ref2->key_for_search.offset) 509 return 0; 510 if (ref1->parent != ref2->parent) 511 return 0; 512 513 return 1; 514 } 515 516 /* 517 * read tree blocks and add keys where required. 518 */ 519 static int __add_missing_keys(struct btrfs_fs_info *fs_info, 520 struct list_head *head) 521 { 522 struct __prelim_ref *ref; 523 struct extent_buffer *eb; 524 525 list_for_each_entry(ref, head, list) { 526 if (ref->parent) 527 continue; 528 if (ref->key_for_search.type) 529 continue; 530 BUG_ON(!ref->wanted_disk_byte); 531 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte, 532 0); 533 if (IS_ERR(eb)) { 534 return PTR_ERR(eb); 535 } else if (!extent_buffer_uptodate(eb)) { 536 free_extent_buffer(eb); 537 return -EIO; 538 } 539 btrfs_tree_read_lock(eb); 540 if (btrfs_header_level(eb) == 0) 541 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0); 542 else 543 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0); 544 btrfs_tree_read_unlock(eb); 545 free_extent_buffer(eb); 546 } 547 return 0; 548 } 549 550 /* 551 * merge backrefs and adjust counts accordingly 552 * 553 * mode = 1: merge identical keys, if key is set 554 * FIXME: if we add more keys in __add_prelim_ref, we can merge more here. 555 * additionally, we could even add a key range for the blocks we 556 * looked into to merge even more (-> replace unresolved refs by those 557 * having a parent). 558 * mode = 2: merge identical parents 559 */ 560 static void __merge_refs(struct list_head *head, int mode) 561 { 562 struct __prelim_ref *pos1; 563 564 list_for_each_entry(pos1, head, list) { 565 struct __prelim_ref *pos2 = pos1, *tmp; 566 567 list_for_each_entry_safe_continue(pos2, tmp, head, list) { 568 struct __prelim_ref *ref1 = pos1, *ref2 = pos2; 569 struct extent_inode_elem *eie; 570 571 if (!ref_for_same_block(ref1, ref2)) 572 continue; 573 if (mode == 1) { 574 if (!ref1->parent && ref2->parent) 575 swap(ref1, ref2); 576 } else { 577 if (ref1->parent != ref2->parent) 578 continue; 579 } 580 581 eie = ref1->inode_list; 582 while (eie && eie->next) 583 eie = eie->next; 584 if (eie) 585 eie->next = ref2->inode_list; 586 else 587 ref1->inode_list = ref2->inode_list; 588 ref1->count += ref2->count; 589 590 list_del(&ref2->list); 591 kmem_cache_free(btrfs_prelim_ref_cache, ref2); 592 } 593 594 } 595 } 596 597 /* 598 * add all currently queued delayed refs from this head whose seq nr is 599 * smaller or equal that seq to the list 600 */ 601 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq, 602 struct list_head *prefs, u64 *total_refs, 603 u64 inum) 604 { 605 struct btrfs_delayed_ref_node *node; 606 struct btrfs_delayed_extent_op *extent_op = head->extent_op; 607 struct btrfs_key key; 608 struct btrfs_key op_key = {0}; 609 int sgn; 610 int ret = 0; 611 612 if (extent_op && extent_op->update_key) 613 btrfs_disk_key_to_cpu(&op_key, &extent_op->key); 614 615 spin_lock(&head->lock); 616 list_for_each_entry(node, &head->ref_list, list) { 617 if (node->seq > seq) 618 continue; 619 620 switch (node->action) { 621 case BTRFS_ADD_DELAYED_EXTENT: 622 case BTRFS_UPDATE_DELAYED_HEAD: 623 WARN_ON(1); 624 continue; 625 case BTRFS_ADD_DELAYED_REF: 626 sgn = 1; 627 break; 628 case BTRFS_DROP_DELAYED_REF: 629 sgn = -1; 630 break; 631 default: 632 BUG_ON(1); 633 } 634 *total_refs += (node->ref_mod * sgn); 635 switch (node->type) { 636 case BTRFS_TREE_BLOCK_REF_KEY: { 637 struct btrfs_delayed_tree_ref *ref; 638 639 ref = btrfs_delayed_node_to_tree_ref(node); 640 ret = __add_prelim_ref(prefs, ref->root, &op_key, 641 ref->level + 1, 0, node->bytenr, 642 node->ref_mod * sgn, GFP_ATOMIC); 643 break; 644 } 645 case BTRFS_SHARED_BLOCK_REF_KEY: { 646 struct btrfs_delayed_tree_ref *ref; 647 648 ref = btrfs_delayed_node_to_tree_ref(node); 649 ret = __add_prelim_ref(prefs, 0, NULL, 650 ref->level + 1, ref->parent, 651 node->bytenr, 652 node->ref_mod * sgn, GFP_ATOMIC); 653 break; 654 } 655 case BTRFS_EXTENT_DATA_REF_KEY: { 656 struct btrfs_delayed_data_ref *ref; 657 ref = btrfs_delayed_node_to_data_ref(node); 658 659 key.objectid = ref->objectid; 660 key.type = BTRFS_EXTENT_DATA_KEY; 661 key.offset = ref->offset; 662 663 /* 664 * Found a inum that doesn't match our known inum, we 665 * know it's shared. 666 */ 667 if (inum && ref->objectid != inum) { 668 ret = BACKREF_FOUND_SHARED; 669 break; 670 } 671 672 ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0, 673 node->bytenr, 674 node->ref_mod * sgn, GFP_ATOMIC); 675 break; 676 } 677 case BTRFS_SHARED_DATA_REF_KEY: { 678 struct btrfs_delayed_data_ref *ref; 679 680 ref = btrfs_delayed_node_to_data_ref(node); 681 ret = __add_prelim_ref(prefs, 0, NULL, 0, 682 ref->parent, node->bytenr, 683 node->ref_mod * sgn, GFP_ATOMIC); 684 break; 685 } 686 default: 687 WARN_ON(1); 688 } 689 if (ret) 690 break; 691 } 692 spin_unlock(&head->lock); 693 return ret; 694 } 695 696 /* 697 * add all inline backrefs for bytenr to the list 698 */ 699 static int __add_inline_refs(struct btrfs_fs_info *fs_info, 700 struct btrfs_path *path, u64 bytenr, 701 int *info_level, struct list_head *prefs, 702 u64 *total_refs, u64 inum) 703 { 704 int ret = 0; 705 int slot; 706 struct extent_buffer *leaf; 707 struct btrfs_key key; 708 struct btrfs_key found_key; 709 unsigned long ptr; 710 unsigned long end; 711 struct btrfs_extent_item *ei; 712 u64 flags; 713 u64 item_size; 714 715 /* 716 * enumerate all inline refs 717 */ 718 leaf = path->nodes[0]; 719 slot = path->slots[0]; 720 721 item_size = btrfs_item_size_nr(leaf, slot); 722 BUG_ON(item_size < sizeof(*ei)); 723 724 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item); 725 flags = btrfs_extent_flags(leaf, ei); 726 *total_refs += btrfs_extent_refs(leaf, ei); 727 btrfs_item_key_to_cpu(leaf, &found_key, slot); 728 729 ptr = (unsigned long)(ei + 1); 730 end = (unsigned long)ei + item_size; 731 732 if (found_key.type == BTRFS_EXTENT_ITEM_KEY && 733 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { 734 struct btrfs_tree_block_info *info; 735 736 info = (struct btrfs_tree_block_info *)ptr; 737 *info_level = btrfs_tree_block_level(leaf, info); 738 ptr += sizeof(struct btrfs_tree_block_info); 739 BUG_ON(ptr > end); 740 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) { 741 *info_level = found_key.offset; 742 } else { 743 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA)); 744 } 745 746 while (ptr < end) { 747 struct btrfs_extent_inline_ref *iref; 748 u64 offset; 749 int type; 750 751 iref = (struct btrfs_extent_inline_ref *)ptr; 752 type = btrfs_extent_inline_ref_type(leaf, iref); 753 offset = btrfs_extent_inline_ref_offset(leaf, iref); 754 755 switch (type) { 756 case BTRFS_SHARED_BLOCK_REF_KEY: 757 ret = __add_prelim_ref(prefs, 0, NULL, 758 *info_level + 1, offset, 759 bytenr, 1, GFP_NOFS); 760 break; 761 case BTRFS_SHARED_DATA_REF_KEY: { 762 struct btrfs_shared_data_ref *sdref; 763 int count; 764 765 sdref = (struct btrfs_shared_data_ref *)(iref + 1); 766 count = btrfs_shared_data_ref_count(leaf, sdref); 767 ret = __add_prelim_ref(prefs, 0, NULL, 0, offset, 768 bytenr, count, GFP_NOFS); 769 break; 770 } 771 case BTRFS_TREE_BLOCK_REF_KEY: 772 ret = __add_prelim_ref(prefs, offset, NULL, 773 *info_level + 1, 0, 774 bytenr, 1, GFP_NOFS); 775 break; 776 case BTRFS_EXTENT_DATA_REF_KEY: { 777 struct btrfs_extent_data_ref *dref; 778 int count; 779 u64 root; 780 781 dref = (struct btrfs_extent_data_ref *)(&iref->offset); 782 count = btrfs_extent_data_ref_count(leaf, dref); 783 key.objectid = btrfs_extent_data_ref_objectid(leaf, 784 dref); 785 key.type = BTRFS_EXTENT_DATA_KEY; 786 key.offset = btrfs_extent_data_ref_offset(leaf, dref); 787 788 if (inum && key.objectid != inum) { 789 ret = BACKREF_FOUND_SHARED; 790 break; 791 } 792 793 root = btrfs_extent_data_ref_root(leaf, dref); 794 ret = __add_prelim_ref(prefs, root, &key, 0, 0, 795 bytenr, count, GFP_NOFS); 796 break; 797 } 798 default: 799 WARN_ON(1); 800 } 801 if (ret) 802 return ret; 803 ptr += btrfs_extent_inline_ref_size(type); 804 } 805 806 return 0; 807 } 808 809 /* 810 * add all non-inline backrefs for bytenr to the list 811 */ 812 static int __add_keyed_refs(struct btrfs_fs_info *fs_info, 813 struct btrfs_path *path, u64 bytenr, 814 int info_level, struct list_head *prefs, u64 inum) 815 { 816 struct btrfs_root *extent_root = fs_info->extent_root; 817 int ret; 818 int slot; 819 struct extent_buffer *leaf; 820 struct btrfs_key key; 821 822 while (1) { 823 ret = btrfs_next_item(extent_root, path); 824 if (ret < 0) 825 break; 826 if (ret) { 827 ret = 0; 828 break; 829 } 830 831 slot = path->slots[0]; 832 leaf = path->nodes[0]; 833 btrfs_item_key_to_cpu(leaf, &key, slot); 834 835 if (key.objectid != bytenr) 836 break; 837 if (key.type < BTRFS_TREE_BLOCK_REF_KEY) 838 continue; 839 if (key.type > BTRFS_SHARED_DATA_REF_KEY) 840 break; 841 842 switch (key.type) { 843 case BTRFS_SHARED_BLOCK_REF_KEY: 844 ret = __add_prelim_ref(prefs, 0, NULL, 845 info_level + 1, key.offset, 846 bytenr, 1, GFP_NOFS); 847 break; 848 case BTRFS_SHARED_DATA_REF_KEY: { 849 struct btrfs_shared_data_ref *sdref; 850 int count; 851 852 sdref = btrfs_item_ptr(leaf, slot, 853 struct btrfs_shared_data_ref); 854 count = btrfs_shared_data_ref_count(leaf, sdref); 855 ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset, 856 bytenr, count, GFP_NOFS); 857 break; 858 } 859 case BTRFS_TREE_BLOCK_REF_KEY: 860 ret = __add_prelim_ref(prefs, key.offset, NULL, 861 info_level + 1, 0, 862 bytenr, 1, GFP_NOFS); 863 break; 864 case BTRFS_EXTENT_DATA_REF_KEY: { 865 struct btrfs_extent_data_ref *dref; 866 int count; 867 u64 root; 868 869 dref = btrfs_item_ptr(leaf, slot, 870 struct btrfs_extent_data_ref); 871 count = btrfs_extent_data_ref_count(leaf, dref); 872 key.objectid = btrfs_extent_data_ref_objectid(leaf, 873 dref); 874 key.type = BTRFS_EXTENT_DATA_KEY; 875 key.offset = btrfs_extent_data_ref_offset(leaf, dref); 876 877 if (inum && key.objectid != inum) { 878 ret = BACKREF_FOUND_SHARED; 879 break; 880 } 881 882 root = btrfs_extent_data_ref_root(leaf, dref); 883 ret = __add_prelim_ref(prefs, root, &key, 0, 0, 884 bytenr, count, GFP_NOFS); 885 break; 886 } 887 default: 888 WARN_ON(1); 889 } 890 if (ret) 891 return ret; 892 893 } 894 895 return ret; 896 } 897 898 /* 899 * this adds all existing backrefs (inline backrefs, backrefs and delayed 900 * refs) for the given bytenr to the refs list, merges duplicates and resolves 901 * indirect refs to their parent bytenr. 902 * When roots are found, they're added to the roots list 903 * 904 * NOTE: This can return values > 0 905 * 906 * If time_seq is set to (u64)-1, it will not search delayed_refs, and behave 907 * much like trans == NULL case, the difference only lies in it will not 908 * commit root. 909 * The special case is for qgroup to search roots in commit_transaction(). 910 * 911 * FIXME some caching might speed things up 912 */ 913 static int find_parent_nodes(struct btrfs_trans_handle *trans, 914 struct btrfs_fs_info *fs_info, u64 bytenr, 915 u64 time_seq, struct ulist *refs, 916 struct ulist *roots, const u64 *extent_item_pos, 917 u64 root_objectid, u64 inum) 918 { 919 struct btrfs_key key; 920 struct btrfs_path *path; 921 struct btrfs_delayed_ref_root *delayed_refs = NULL; 922 struct btrfs_delayed_ref_head *head; 923 int info_level = 0; 924 int ret; 925 struct list_head prefs_delayed; 926 struct list_head prefs; 927 struct __prelim_ref *ref; 928 struct extent_inode_elem *eie = NULL; 929 u64 total_refs = 0; 930 931 INIT_LIST_HEAD(&prefs); 932 INIT_LIST_HEAD(&prefs_delayed); 933 934 key.objectid = bytenr; 935 key.offset = (u64)-1; 936 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA)) 937 key.type = BTRFS_METADATA_ITEM_KEY; 938 else 939 key.type = BTRFS_EXTENT_ITEM_KEY; 940 941 path = btrfs_alloc_path(); 942 if (!path) 943 return -ENOMEM; 944 if (!trans) { 945 path->search_commit_root = 1; 946 path->skip_locking = 1; 947 } 948 949 if (time_seq == (u64)-1) 950 path->skip_locking = 1; 951 952 /* 953 * grab both a lock on the path and a lock on the delayed ref head. 954 * We need both to get a consistent picture of how the refs look 955 * at a specified point in time 956 */ 957 again: 958 head = NULL; 959 960 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0); 961 if (ret < 0) 962 goto out; 963 BUG_ON(ret == 0); 964 965 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS 966 if (trans && likely(trans->type != __TRANS_DUMMY) && 967 time_seq != (u64)-1) { 968 #else 969 if (trans && time_seq != (u64)-1) { 970 #endif 971 /* 972 * look if there are updates for this ref queued and lock the 973 * head 974 */ 975 delayed_refs = &trans->transaction->delayed_refs; 976 spin_lock(&delayed_refs->lock); 977 head = btrfs_find_delayed_ref_head(trans, bytenr); 978 if (head) { 979 if (!mutex_trylock(&head->mutex)) { 980 atomic_inc(&head->node.refs); 981 spin_unlock(&delayed_refs->lock); 982 983 btrfs_release_path(path); 984 985 /* 986 * Mutex was contended, block until it's 987 * released and try again 988 */ 989 mutex_lock(&head->mutex); 990 mutex_unlock(&head->mutex); 991 btrfs_put_delayed_ref(&head->node); 992 goto again; 993 } 994 spin_unlock(&delayed_refs->lock); 995 ret = __add_delayed_refs(head, time_seq, 996 &prefs_delayed, &total_refs, 997 inum); 998 mutex_unlock(&head->mutex); 999 if (ret) 1000 goto out; 1001 } else { 1002 spin_unlock(&delayed_refs->lock); 1003 } 1004 } 1005 1006 if (path->slots[0]) { 1007 struct extent_buffer *leaf; 1008 int slot; 1009 1010 path->slots[0]--; 1011 leaf = path->nodes[0]; 1012 slot = path->slots[0]; 1013 btrfs_item_key_to_cpu(leaf, &key, slot); 1014 if (key.objectid == bytenr && 1015 (key.type == BTRFS_EXTENT_ITEM_KEY || 1016 key.type == BTRFS_METADATA_ITEM_KEY)) { 1017 ret = __add_inline_refs(fs_info, path, bytenr, 1018 &info_level, &prefs, 1019 &total_refs, inum); 1020 if (ret) 1021 goto out; 1022 ret = __add_keyed_refs(fs_info, path, bytenr, 1023 info_level, &prefs, inum); 1024 if (ret) 1025 goto out; 1026 } 1027 } 1028 btrfs_release_path(path); 1029 1030 list_splice_init(&prefs_delayed, &prefs); 1031 1032 ret = __add_missing_keys(fs_info, &prefs); 1033 if (ret) 1034 goto out; 1035 1036 __merge_refs(&prefs, 1); 1037 1038 ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs, 1039 extent_item_pos, total_refs, 1040 root_objectid); 1041 if (ret) 1042 goto out; 1043 1044 __merge_refs(&prefs, 2); 1045 1046 while (!list_empty(&prefs)) { 1047 ref = list_first_entry(&prefs, struct __prelim_ref, list); 1048 WARN_ON(ref->count < 0); 1049 if (roots && ref->count && ref->root_id && ref->parent == 0) { 1050 if (root_objectid && ref->root_id != root_objectid) { 1051 ret = BACKREF_FOUND_SHARED; 1052 goto out; 1053 } 1054 1055 /* no parent == root of tree */ 1056 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); 1057 if (ret < 0) 1058 goto out; 1059 } 1060 if (ref->count && ref->parent) { 1061 if (extent_item_pos && !ref->inode_list && 1062 ref->level == 0) { 1063 struct extent_buffer *eb; 1064 1065 eb = read_tree_block(fs_info->extent_root, 1066 ref->parent, 0); 1067 if (IS_ERR(eb)) { 1068 ret = PTR_ERR(eb); 1069 goto out; 1070 } else if (!extent_buffer_uptodate(eb)) { 1071 free_extent_buffer(eb); 1072 ret = -EIO; 1073 goto out; 1074 } 1075 btrfs_tree_read_lock(eb); 1076 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); 1077 ret = find_extent_in_eb(eb, bytenr, 1078 *extent_item_pos, &eie); 1079 btrfs_tree_read_unlock_blocking(eb); 1080 free_extent_buffer(eb); 1081 if (ret < 0) 1082 goto out; 1083 ref->inode_list = eie; 1084 } 1085 ret = ulist_add_merge_ptr(refs, ref->parent, 1086 ref->inode_list, 1087 (void **)&eie, GFP_NOFS); 1088 if (ret < 0) 1089 goto out; 1090 if (!ret && extent_item_pos) { 1091 /* 1092 * we've recorded that parent, so we must extend 1093 * its inode list here 1094 */ 1095 BUG_ON(!eie); 1096 while (eie->next) 1097 eie = eie->next; 1098 eie->next = ref->inode_list; 1099 } 1100 eie = NULL; 1101 } 1102 list_del(&ref->list); 1103 kmem_cache_free(btrfs_prelim_ref_cache, ref); 1104 } 1105 1106 out: 1107 btrfs_free_path(path); 1108 while (!list_empty(&prefs)) { 1109 ref = list_first_entry(&prefs, struct __prelim_ref, list); 1110 list_del(&ref->list); 1111 kmem_cache_free(btrfs_prelim_ref_cache, ref); 1112 } 1113 while (!list_empty(&prefs_delayed)) { 1114 ref = list_first_entry(&prefs_delayed, struct __prelim_ref, 1115 list); 1116 list_del(&ref->list); 1117 kmem_cache_free(btrfs_prelim_ref_cache, ref); 1118 } 1119 if (ret < 0) 1120 free_inode_elem_list(eie); 1121 return ret; 1122 } 1123 1124 static void free_leaf_list(struct ulist *blocks) 1125 { 1126 struct ulist_node *node = NULL; 1127 struct extent_inode_elem *eie; 1128 struct ulist_iterator uiter; 1129 1130 ULIST_ITER_INIT(&uiter); 1131 while ((node = ulist_next(blocks, &uiter))) { 1132 if (!node->aux) 1133 continue; 1134 eie = (struct extent_inode_elem *)(uintptr_t)node->aux; 1135 free_inode_elem_list(eie); 1136 node->aux = 0; 1137 } 1138 1139 ulist_free(blocks); 1140 } 1141 1142 /* 1143 * Finds all leafs with a reference to the specified combination of bytenr and 1144 * offset. key_list_head will point to a list of corresponding keys (caller must 1145 * free each list element). The leafs will be stored in the leafs ulist, which 1146 * must be freed with ulist_free. 1147 * 1148 * returns 0 on success, <0 on error 1149 */ 1150 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans, 1151 struct btrfs_fs_info *fs_info, u64 bytenr, 1152 u64 time_seq, struct ulist **leafs, 1153 const u64 *extent_item_pos) 1154 { 1155 int ret; 1156 1157 *leafs = ulist_alloc(GFP_NOFS); 1158 if (!*leafs) 1159 return -ENOMEM; 1160 1161 ret = find_parent_nodes(trans, fs_info, bytenr, 1162 time_seq, *leafs, NULL, extent_item_pos, 0, 0); 1163 if (ret < 0 && ret != -ENOENT) { 1164 free_leaf_list(*leafs); 1165 return ret; 1166 } 1167 1168 return 0; 1169 } 1170 1171 /* 1172 * walk all backrefs for a given extent to find all roots that reference this 1173 * extent. Walking a backref means finding all extents that reference this 1174 * extent and in turn walk the backrefs of those, too. Naturally this is a 1175 * recursive process, but here it is implemented in an iterative fashion: We 1176 * find all referencing extents for the extent in question and put them on a 1177 * list. In turn, we find all referencing extents for those, further appending 1178 * to the list. The way we iterate the list allows adding more elements after 1179 * the current while iterating. The process stops when we reach the end of the 1180 * list. Found roots are added to the roots list. 1181 * 1182 * returns 0 on success, < 0 on error. 1183 */ 1184 static int __btrfs_find_all_roots(struct btrfs_trans_handle *trans, 1185 struct btrfs_fs_info *fs_info, u64 bytenr, 1186 u64 time_seq, struct ulist **roots) 1187 { 1188 struct ulist *tmp; 1189 struct ulist_node *node = NULL; 1190 struct ulist_iterator uiter; 1191 int ret; 1192 1193 tmp = ulist_alloc(GFP_NOFS); 1194 if (!tmp) 1195 return -ENOMEM; 1196 *roots = ulist_alloc(GFP_NOFS); 1197 if (!*roots) { 1198 ulist_free(tmp); 1199 return -ENOMEM; 1200 } 1201 1202 ULIST_ITER_INIT(&uiter); 1203 while (1) { 1204 ret = find_parent_nodes(trans, fs_info, bytenr, 1205 time_seq, tmp, *roots, NULL, 0, 0); 1206 if (ret < 0 && ret != -ENOENT) { 1207 ulist_free(tmp); 1208 ulist_free(*roots); 1209 return ret; 1210 } 1211 node = ulist_next(tmp, &uiter); 1212 if (!node) 1213 break; 1214 bytenr = node->val; 1215 cond_resched(); 1216 } 1217 1218 ulist_free(tmp); 1219 return 0; 1220 } 1221 1222 int btrfs_find_all_roots(struct btrfs_trans_handle *trans, 1223 struct btrfs_fs_info *fs_info, u64 bytenr, 1224 u64 time_seq, struct ulist **roots) 1225 { 1226 int ret; 1227 1228 if (!trans) 1229 down_read(&fs_info->commit_root_sem); 1230 ret = __btrfs_find_all_roots(trans, fs_info, bytenr, time_seq, roots); 1231 if (!trans) 1232 up_read(&fs_info->commit_root_sem); 1233 return ret; 1234 } 1235 1236 /** 1237 * btrfs_check_shared - tell us whether an extent is shared 1238 * 1239 * @trans: optional trans handle 1240 * 1241 * btrfs_check_shared uses the backref walking code but will short 1242 * circuit as soon as it finds a root or inode that doesn't match the 1243 * one passed in. This provides a significant performance benefit for 1244 * callers (such as fiemap) which want to know whether the extent is 1245 * shared but do not need a ref count. 1246 * 1247 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error. 1248 */ 1249 int btrfs_check_shared(struct btrfs_trans_handle *trans, 1250 struct btrfs_fs_info *fs_info, u64 root_objectid, 1251 u64 inum, u64 bytenr) 1252 { 1253 struct ulist *tmp = NULL; 1254 struct ulist *roots = NULL; 1255 struct ulist_iterator uiter; 1256 struct ulist_node *node; 1257 struct seq_list elem = SEQ_LIST_INIT(elem); 1258 int ret = 0; 1259 1260 tmp = ulist_alloc(GFP_NOFS); 1261 roots = ulist_alloc(GFP_NOFS); 1262 if (!tmp || !roots) { 1263 ulist_free(tmp); 1264 ulist_free(roots); 1265 return -ENOMEM; 1266 } 1267 1268 if (trans) 1269 btrfs_get_tree_mod_seq(fs_info, &elem); 1270 else 1271 down_read(&fs_info->commit_root_sem); 1272 ULIST_ITER_INIT(&uiter); 1273 while (1) { 1274 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp, 1275 roots, NULL, root_objectid, inum); 1276 if (ret == BACKREF_FOUND_SHARED) { 1277 /* this is the only condition under which we return 1 */ 1278 ret = 1; 1279 break; 1280 } 1281 if (ret < 0 && ret != -ENOENT) 1282 break; 1283 ret = 0; 1284 node = ulist_next(tmp, &uiter); 1285 if (!node) 1286 break; 1287 bytenr = node->val; 1288 cond_resched(); 1289 } 1290 if (trans) 1291 btrfs_put_tree_mod_seq(fs_info, &elem); 1292 else 1293 up_read(&fs_info->commit_root_sem); 1294 ulist_free(tmp); 1295 ulist_free(roots); 1296 return ret; 1297 } 1298 1299 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, 1300 u64 start_off, struct btrfs_path *path, 1301 struct btrfs_inode_extref **ret_extref, 1302 u64 *found_off) 1303 { 1304 int ret, slot; 1305 struct btrfs_key key; 1306 struct btrfs_key found_key; 1307 struct btrfs_inode_extref *extref; 1308 struct extent_buffer *leaf; 1309 unsigned long ptr; 1310 1311 key.objectid = inode_objectid; 1312 key.type = BTRFS_INODE_EXTREF_KEY; 1313 key.offset = start_off; 1314 1315 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 1316 if (ret < 0) 1317 return ret; 1318 1319 while (1) { 1320 leaf = path->nodes[0]; 1321 slot = path->slots[0]; 1322 if (slot >= btrfs_header_nritems(leaf)) { 1323 /* 1324 * If the item at offset is not found, 1325 * btrfs_search_slot will point us to the slot 1326 * where it should be inserted. In our case 1327 * that will be the slot directly before the 1328 * next INODE_REF_KEY_V2 item. In the case 1329 * that we're pointing to the last slot in a 1330 * leaf, we must move one leaf over. 1331 */ 1332 ret = btrfs_next_leaf(root, path); 1333 if (ret) { 1334 if (ret >= 1) 1335 ret = -ENOENT; 1336 break; 1337 } 1338 continue; 1339 } 1340 1341 btrfs_item_key_to_cpu(leaf, &found_key, slot); 1342 1343 /* 1344 * Check that we're still looking at an extended ref key for 1345 * this particular objectid. If we have different 1346 * objectid or type then there are no more to be found 1347 * in the tree and we can exit. 1348 */ 1349 ret = -ENOENT; 1350 if (found_key.objectid != inode_objectid) 1351 break; 1352 if (found_key.type != BTRFS_INODE_EXTREF_KEY) 1353 break; 1354 1355 ret = 0; 1356 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); 1357 extref = (struct btrfs_inode_extref *)ptr; 1358 *ret_extref = extref; 1359 if (found_off) 1360 *found_off = found_key.offset; 1361 break; 1362 } 1363 1364 return ret; 1365 } 1366 1367 /* 1368 * this iterates to turn a name (from iref/extref) into a full filesystem path. 1369 * Elements of the path are separated by '/' and the path is guaranteed to be 1370 * 0-terminated. the path is only given within the current file system. 1371 * Therefore, it never starts with a '/'. the caller is responsible to provide 1372 * "size" bytes in "dest". the dest buffer will be filled backwards. finally, 1373 * the start point of the resulting string is returned. this pointer is within 1374 * dest, normally. 1375 * in case the path buffer would overflow, the pointer is decremented further 1376 * as if output was written to the buffer, though no more output is actually 1377 * generated. that way, the caller can determine how much space would be 1378 * required for the path to fit into the buffer. in that case, the returned 1379 * value will be smaller than dest. callers must check this! 1380 */ 1381 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path, 1382 u32 name_len, unsigned long name_off, 1383 struct extent_buffer *eb_in, u64 parent, 1384 char *dest, u32 size) 1385 { 1386 int slot; 1387 u64 next_inum; 1388 int ret; 1389 s64 bytes_left = ((s64)size) - 1; 1390 struct extent_buffer *eb = eb_in; 1391 struct btrfs_key found_key; 1392 int leave_spinning = path->leave_spinning; 1393 struct btrfs_inode_ref *iref; 1394 1395 if (bytes_left >= 0) 1396 dest[bytes_left] = '\0'; 1397 1398 path->leave_spinning = 1; 1399 while (1) { 1400 bytes_left -= name_len; 1401 if (bytes_left >= 0) 1402 read_extent_buffer(eb, dest + bytes_left, 1403 name_off, name_len); 1404 if (eb != eb_in) { 1405 if (!path->skip_locking) 1406 btrfs_tree_read_unlock_blocking(eb); 1407 free_extent_buffer(eb); 1408 } 1409 ret = btrfs_find_item(fs_root, path, parent, 0, 1410 BTRFS_INODE_REF_KEY, &found_key); 1411 if (ret > 0) 1412 ret = -ENOENT; 1413 if (ret) 1414 break; 1415 1416 next_inum = found_key.offset; 1417 1418 /* regular exit ahead */ 1419 if (parent == next_inum) 1420 break; 1421 1422 slot = path->slots[0]; 1423 eb = path->nodes[0]; 1424 /* make sure we can use eb after releasing the path */ 1425 if (eb != eb_in) { 1426 if (!path->skip_locking) 1427 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); 1428 path->nodes[0] = NULL; 1429 path->locks[0] = 0; 1430 } 1431 btrfs_release_path(path); 1432 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); 1433 1434 name_len = btrfs_inode_ref_name_len(eb, iref); 1435 name_off = (unsigned long)(iref + 1); 1436 1437 parent = next_inum; 1438 --bytes_left; 1439 if (bytes_left >= 0) 1440 dest[bytes_left] = '/'; 1441 } 1442 1443 btrfs_release_path(path); 1444 path->leave_spinning = leave_spinning; 1445 1446 if (ret) 1447 return ERR_PTR(ret); 1448 1449 return dest + bytes_left; 1450 } 1451 1452 /* 1453 * this makes the path point to (logical EXTENT_ITEM *) 1454 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for 1455 * tree blocks and <0 on error. 1456 */ 1457 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical, 1458 struct btrfs_path *path, struct btrfs_key *found_key, 1459 u64 *flags_ret) 1460 { 1461 int ret; 1462 u64 flags; 1463 u64 size = 0; 1464 u32 item_size; 1465 struct extent_buffer *eb; 1466 struct btrfs_extent_item *ei; 1467 struct btrfs_key key; 1468 1469 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA)) 1470 key.type = BTRFS_METADATA_ITEM_KEY; 1471 else 1472 key.type = BTRFS_EXTENT_ITEM_KEY; 1473 key.objectid = logical; 1474 key.offset = (u64)-1; 1475 1476 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0); 1477 if (ret < 0) 1478 return ret; 1479 1480 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0); 1481 if (ret) { 1482 if (ret > 0) 1483 ret = -ENOENT; 1484 return ret; 1485 } 1486 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]); 1487 if (found_key->type == BTRFS_METADATA_ITEM_KEY) 1488 size = fs_info->extent_root->nodesize; 1489 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY) 1490 size = found_key->offset; 1491 1492 if (found_key->objectid > logical || 1493 found_key->objectid + size <= logical) { 1494 pr_debug("logical %llu is not within any extent\n", logical); 1495 return -ENOENT; 1496 } 1497 1498 eb = path->nodes[0]; 1499 item_size = btrfs_item_size_nr(eb, path->slots[0]); 1500 BUG_ON(item_size < sizeof(*ei)); 1501 1502 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item); 1503 flags = btrfs_extent_flags(eb, ei); 1504 1505 pr_debug("logical %llu is at position %llu within the extent (%llu " 1506 "EXTENT_ITEM %llu) flags %#llx size %u\n", 1507 logical, logical - found_key->objectid, found_key->objectid, 1508 found_key->offset, flags, item_size); 1509 1510 WARN_ON(!flags_ret); 1511 if (flags_ret) { 1512 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) 1513 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK; 1514 else if (flags & BTRFS_EXTENT_FLAG_DATA) 1515 *flags_ret = BTRFS_EXTENT_FLAG_DATA; 1516 else 1517 BUG_ON(1); 1518 return 0; 1519 } 1520 1521 return -EIO; 1522 } 1523 1524 /* 1525 * helper function to iterate extent inline refs. ptr must point to a 0 value 1526 * for the first call and may be modified. it is used to track state. 1527 * if more refs exist, 0 is returned and the next call to 1528 * __get_extent_inline_ref must pass the modified ptr parameter to get the 1529 * next ref. after the last ref was processed, 1 is returned. 1530 * returns <0 on error 1531 */ 1532 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb, 1533 struct btrfs_key *key, 1534 struct btrfs_extent_item *ei, u32 item_size, 1535 struct btrfs_extent_inline_ref **out_eiref, 1536 int *out_type) 1537 { 1538 unsigned long end; 1539 u64 flags; 1540 struct btrfs_tree_block_info *info; 1541 1542 if (!*ptr) { 1543 /* first call */ 1544 flags = btrfs_extent_flags(eb, ei); 1545 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { 1546 if (key->type == BTRFS_METADATA_ITEM_KEY) { 1547 /* a skinny metadata extent */ 1548 *out_eiref = 1549 (struct btrfs_extent_inline_ref *)(ei + 1); 1550 } else { 1551 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY); 1552 info = (struct btrfs_tree_block_info *)(ei + 1); 1553 *out_eiref = 1554 (struct btrfs_extent_inline_ref *)(info + 1); 1555 } 1556 } else { 1557 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1); 1558 } 1559 *ptr = (unsigned long)*out_eiref; 1560 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size) 1561 return -ENOENT; 1562 } 1563 1564 end = (unsigned long)ei + item_size; 1565 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr); 1566 *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref); 1567 1568 *ptr += btrfs_extent_inline_ref_size(*out_type); 1569 WARN_ON(*ptr > end); 1570 if (*ptr == end) 1571 return 1; /* last */ 1572 1573 return 0; 1574 } 1575 1576 /* 1577 * reads the tree block backref for an extent. tree level and root are returned 1578 * through out_level and out_root. ptr must point to a 0 value for the first 1579 * call and may be modified (see __get_extent_inline_ref comment). 1580 * returns 0 if data was provided, 1 if there was no more data to provide or 1581 * <0 on error. 1582 */ 1583 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, 1584 struct btrfs_key *key, struct btrfs_extent_item *ei, 1585 u32 item_size, u64 *out_root, u8 *out_level) 1586 { 1587 int ret; 1588 int type; 1589 struct btrfs_extent_inline_ref *eiref; 1590 1591 if (*ptr == (unsigned long)-1) 1592 return 1; 1593 1594 while (1) { 1595 ret = __get_extent_inline_ref(ptr, eb, key, ei, item_size, 1596 &eiref, &type); 1597 if (ret < 0) 1598 return ret; 1599 1600 if (type == BTRFS_TREE_BLOCK_REF_KEY || 1601 type == BTRFS_SHARED_BLOCK_REF_KEY) 1602 break; 1603 1604 if (ret == 1) 1605 return 1; 1606 } 1607 1608 /* we can treat both ref types equally here */ 1609 *out_root = btrfs_extent_inline_ref_offset(eb, eiref); 1610 1611 if (key->type == BTRFS_EXTENT_ITEM_KEY) { 1612 struct btrfs_tree_block_info *info; 1613 1614 info = (struct btrfs_tree_block_info *)(ei + 1); 1615 *out_level = btrfs_tree_block_level(eb, info); 1616 } else { 1617 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY); 1618 *out_level = (u8)key->offset; 1619 } 1620 1621 if (ret == 1) 1622 *ptr = (unsigned long)-1; 1623 1624 return 0; 1625 } 1626 1627 static int iterate_leaf_refs(struct extent_inode_elem *inode_list, 1628 u64 root, u64 extent_item_objectid, 1629 iterate_extent_inodes_t *iterate, void *ctx) 1630 { 1631 struct extent_inode_elem *eie; 1632 int ret = 0; 1633 1634 for (eie = inode_list; eie; eie = eie->next) { 1635 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), " 1636 "root %llu\n", extent_item_objectid, 1637 eie->inum, eie->offset, root); 1638 ret = iterate(eie->inum, eie->offset, root, ctx); 1639 if (ret) { 1640 pr_debug("stopping iteration for %llu due to ret=%d\n", 1641 extent_item_objectid, ret); 1642 break; 1643 } 1644 } 1645 1646 return ret; 1647 } 1648 1649 /* 1650 * calls iterate() for every inode that references the extent identified by 1651 * the given parameters. 1652 * when the iterator function returns a non-zero value, iteration stops. 1653 */ 1654 int iterate_extent_inodes(struct btrfs_fs_info *fs_info, 1655 u64 extent_item_objectid, u64 extent_item_pos, 1656 int search_commit_root, 1657 iterate_extent_inodes_t *iterate, void *ctx) 1658 { 1659 int ret; 1660 struct btrfs_trans_handle *trans = NULL; 1661 struct ulist *refs = NULL; 1662 struct ulist *roots = NULL; 1663 struct ulist_node *ref_node = NULL; 1664 struct ulist_node *root_node = NULL; 1665 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem); 1666 struct ulist_iterator ref_uiter; 1667 struct ulist_iterator root_uiter; 1668 1669 pr_debug("resolving all inodes for extent %llu\n", 1670 extent_item_objectid); 1671 1672 if (!search_commit_root) { 1673 trans = btrfs_join_transaction(fs_info->extent_root); 1674 if (IS_ERR(trans)) 1675 return PTR_ERR(trans); 1676 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem); 1677 } else { 1678 down_read(&fs_info->commit_root_sem); 1679 } 1680 1681 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid, 1682 tree_mod_seq_elem.seq, &refs, 1683 &extent_item_pos); 1684 if (ret) 1685 goto out; 1686 1687 ULIST_ITER_INIT(&ref_uiter); 1688 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) { 1689 ret = __btrfs_find_all_roots(trans, fs_info, ref_node->val, 1690 tree_mod_seq_elem.seq, &roots); 1691 if (ret) 1692 break; 1693 ULIST_ITER_INIT(&root_uiter); 1694 while (!ret && (root_node = ulist_next(roots, &root_uiter))) { 1695 pr_debug("root %llu references leaf %llu, data list " 1696 "%#llx\n", root_node->val, ref_node->val, 1697 ref_node->aux); 1698 ret = iterate_leaf_refs((struct extent_inode_elem *) 1699 (uintptr_t)ref_node->aux, 1700 root_node->val, 1701 extent_item_objectid, 1702 iterate, ctx); 1703 } 1704 ulist_free(roots); 1705 } 1706 1707 free_leaf_list(refs); 1708 out: 1709 if (!search_commit_root) { 1710 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem); 1711 btrfs_end_transaction(trans, fs_info->extent_root); 1712 } else { 1713 up_read(&fs_info->commit_root_sem); 1714 } 1715 1716 return ret; 1717 } 1718 1719 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, 1720 struct btrfs_path *path, 1721 iterate_extent_inodes_t *iterate, void *ctx) 1722 { 1723 int ret; 1724 u64 extent_item_pos; 1725 u64 flags = 0; 1726 struct btrfs_key found_key; 1727 int search_commit_root = path->search_commit_root; 1728 1729 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags); 1730 btrfs_release_path(path); 1731 if (ret < 0) 1732 return ret; 1733 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) 1734 return -EINVAL; 1735 1736 extent_item_pos = logical - found_key.objectid; 1737 ret = iterate_extent_inodes(fs_info, found_key.objectid, 1738 extent_item_pos, search_commit_root, 1739 iterate, ctx); 1740 1741 return ret; 1742 } 1743 1744 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off, 1745 struct extent_buffer *eb, void *ctx); 1746 1747 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root, 1748 struct btrfs_path *path, 1749 iterate_irefs_t *iterate, void *ctx) 1750 { 1751 int ret = 0; 1752 int slot; 1753 u32 cur; 1754 u32 len; 1755 u32 name_len; 1756 u64 parent = 0; 1757 int found = 0; 1758 struct extent_buffer *eb; 1759 struct btrfs_item *item; 1760 struct btrfs_inode_ref *iref; 1761 struct btrfs_key found_key; 1762 1763 while (!ret) { 1764 ret = btrfs_find_item(fs_root, path, inum, 1765 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY, 1766 &found_key); 1767 1768 if (ret < 0) 1769 break; 1770 if (ret) { 1771 ret = found ? 0 : -ENOENT; 1772 break; 1773 } 1774 ++found; 1775 1776 parent = found_key.offset; 1777 slot = path->slots[0]; 1778 eb = btrfs_clone_extent_buffer(path->nodes[0]); 1779 if (!eb) { 1780 ret = -ENOMEM; 1781 break; 1782 } 1783 extent_buffer_get(eb); 1784 btrfs_tree_read_lock(eb); 1785 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); 1786 btrfs_release_path(path); 1787 1788 item = btrfs_item_nr(slot); 1789 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); 1790 1791 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) { 1792 name_len = btrfs_inode_ref_name_len(eb, iref); 1793 /* path must be released before calling iterate()! */ 1794 pr_debug("following ref at offset %u for inode %llu in " 1795 "tree %llu\n", cur, found_key.objectid, 1796 fs_root->objectid); 1797 ret = iterate(parent, name_len, 1798 (unsigned long)(iref + 1), eb, ctx); 1799 if (ret) 1800 break; 1801 len = sizeof(*iref) + name_len; 1802 iref = (struct btrfs_inode_ref *)((char *)iref + len); 1803 } 1804 btrfs_tree_read_unlock_blocking(eb); 1805 free_extent_buffer(eb); 1806 } 1807 1808 btrfs_release_path(path); 1809 1810 return ret; 1811 } 1812 1813 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, 1814 struct btrfs_path *path, 1815 iterate_irefs_t *iterate, void *ctx) 1816 { 1817 int ret; 1818 int slot; 1819 u64 offset = 0; 1820 u64 parent; 1821 int found = 0; 1822 struct extent_buffer *eb; 1823 struct btrfs_inode_extref *extref; 1824 u32 item_size; 1825 u32 cur_offset; 1826 unsigned long ptr; 1827 1828 while (1) { 1829 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref, 1830 &offset); 1831 if (ret < 0) 1832 break; 1833 if (ret) { 1834 ret = found ? 0 : -ENOENT; 1835 break; 1836 } 1837 ++found; 1838 1839 slot = path->slots[0]; 1840 eb = btrfs_clone_extent_buffer(path->nodes[0]); 1841 if (!eb) { 1842 ret = -ENOMEM; 1843 break; 1844 } 1845 extent_buffer_get(eb); 1846 1847 btrfs_tree_read_lock(eb); 1848 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); 1849 btrfs_release_path(path); 1850 1851 item_size = btrfs_item_size_nr(eb, slot); 1852 ptr = btrfs_item_ptr_offset(eb, slot); 1853 cur_offset = 0; 1854 1855 while (cur_offset < item_size) { 1856 u32 name_len; 1857 1858 extref = (struct btrfs_inode_extref *)(ptr + cur_offset); 1859 parent = btrfs_inode_extref_parent(eb, extref); 1860 name_len = btrfs_inode_extref_name_len(eb, extref); 1861 ret = iterate(parent, name_len, 1862 (unsigned long)&extref->name, eb, ctx); 1863 if (ret) 1864 break; 1865 1866 cur_offset += btrfs_inode_extref_name_len(eb, extref); 1867 cur_offset += sizeof(*extref); 1868 } 1869 btrfs_tree_read_unlock_blocking(eb); 1870 free_extent_buffer(eb); 1871 1872 offset++; 1873 } 1874 1875 btrfs_release_path(path); 1876 1877 return ret; 1878 } 1879 1880 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root, 1881 struct btrfs_path *path, iterate_irefs_t *iterate, 1882 void *ctx) 1883 { 1884 int ret; 1885 int found_refs = 0; 1886 1887 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx); 1888 if (!ret) 1889 ++found_refs; 1890 else if (ret != -ENOENT) 1891 return ret; 1892 1893 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx); 1894 if (ret == -ENOENT && found_refs) 1895 return 0; 1896 1897 return ret; 1898 } 1899 1900 /* 1901 * returns 0 if the path could be dumped (probably truncated) 1902 * returns <0 in case of an error 1903 */ 1904 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off, 1905 struct extent_buffer *eb, void *ctx) 1906 { 1907 struct inode_fs_paths *ipath = ctx; 1908 char *fspath; 1909 char *fspath_min; 1910 int i = ipath->fspath->elem_cnt; 1911 const int s_ptr = sizeof(char *); 1912 u32 bytes_left; 1913 1914 bytes_left = ipath->fspath->bytes_left > s_ptr ? 1915 ipath->fspath->bytes_left - s_ptr : 0; 1916 1917 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr; 1918 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len, 1919 name_off, eb, inum, fspath_min, bytes_left); 1920 if (IS_ERR(fspath)) 1921 return PTR_ERR(fspath); 1922 1923 if (fspath > fspath_min) { 1924 ipath->fspath->val[i] = (u64)(unsigned long)fspath; 1925 ++ipath->fspath->elem_cnt; 1926 ipath->fspath->bytes_left = fspath - fspath_min; 1927 } else { 1928 ++ipath->fspath->elem_missed; 1929 ipath->fspath->bytes_missing += fspath_min - fspath; 1930 ipath->fspath->bytes_left = 0; 1931 } 1932 1933 return 0; 1934 } 1935 1936 /* 1937 * this dumps all file system paths to the inode into the ipath struct, provided 1938 * is has been created large enough. each path is zero-terminated and accessed 1939 * from ipath->fspath->val[i]. 1940 * when it returns, there are ipath->fspath->elem_cnt number of paths available 1941 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the 1942 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise, 1943 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would 1944 * have been needed to return all paths. 1945 */ 1946 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath) 1947 { 1948 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path, 1949 inode_to_path, ipath); 1950 } 1951 1952 struct btrfs_data_container *init_data_container(u32 total_bytes) 1953 { 1954 struct btrfs_data_container *data; 1955 size_t alloc_bytes; 1956 1957 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data)); 1958 data = vmalloc(alloc_bytes); 1959 if (!data) 1960 return ERR_PTR(-ENOMEM); 1961 1962 if (total_bytes >= sizeof(*data)) { 1963 data->bytes_left = total_bytes - sizeof(*data); 1964 data->bytes_missing = 0; 1965 } else { 1966 data->bytes_missing = sizeof(*data) - total_bytes; 1967 data->bytes_left = 0; 1968 } 1969 1970 data->elem_cnt = 0; 1971 data->elem_missed = 0; 1972 1973 return data; 1974 } 1975 1976 /* 1977 * allocates space to return multiple file system paths for an inode. 1978 * total_bytes to allocate are passed, note that space usable for actual path 1979 * information will be total_bytes - sizeof(struct inode_fs_paths). 1980 * the returned pointer must be freed with free_ipath() in the end. 1981 */ 1982 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root, 1983 struct btrfs_path *path) 1984 { 1985 struct inode_fs_paths *ifp; 1986 struct btrfs_data_container *fspath; 1987 1988 fspath = init_data_container(total_bytes); 1989 if (IS_ERR(fspath)) 1990 return (void *)fspath; 1991 1992 ifp = kmalloc(sizeof(*ifp), GFP_NOFS); 1993 if (!ifp) { 1994 vfree(fspath); 1995 return ERR_PTR(-ENOMEM); 1996 } 1997 1998 ifp->btrfs_path = path; 1999 ifp->fspath = fspath; 2000 ifp->fs_root = fs_root; 2001 2002 return ifp; 2003 } 2004 2005 void free_ipath(struct inode_fs_paths *ipath) 2006 { 2007 if (!ipath) 2008 return; 2009 vfree(ipath->fspath); 2010 kfree(ipath); 2011 } 2012