1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2011 STRATO. All rights reserved. 4 */ 5 6 #include <linux/mm.h> 7 #include <linux/rbtree.h> 8 #include <trace/events/btrfs.h> 9 #include "ctree.h" 10 #include "disk-io.h" 11 #include "backref.h" 12 #include "ulist.h" 13 #include "transaction.h" 14 #include "delayed-ref.h" 15 #include "locking.h" 16 #include "misc.h" 17 18 /* Just an arbitrary number so we can be sure this happened */ 19 #define BACKREF_FOUND_SHARED 6 20 21 struct extent_inode_elem { 22 u64 inum; 23 u64 offset; 24 struct extent_inode_elem *next; 25 }; 26 27 static int check_extent_in_eb(const struct btrfs_key *key, 28 const struct extent_buffer *eb, 29 const struct btrfs_file_extent_item *fi, 30 u64 extent_item_pos, 31 struct extent_inode_elem **eie, 32 bool ignore_offset) 33 { 34 u64 offset = 0; 35 struct extent_inode_elem *e; 36 37 if (!ignore_offset && 38 !btrfs_file_extent_compression(eb, fi) && 39 !btrfs_file_extent_encryption(eb, fi) && 40 !btrfs_file_extent_other_encoding(eb, fi)) { 41 u64 data_offset; 42 u64 data_len; 43 44 data_offset = btrfs_file_extent_offset(eb, fi); 45 data_len = btrfs_file_extent_num_bytes(eb, fi); 46 47 if (extent_item_pos < data_offset || 48 extent_item_pos >= data_offset + data_len) 49 return 1; 50 offset = extent_item_pos - data_offset; 51 } 52 53 e = kmalloc(sizeof(*e), GFP_NOFS); 54 if (!e) 55 return -ENOMEM; 56 57 e->next = *eie; 58 e->inum = key->objectid; 59 e->offset = key->offset + offset; 60 *eie = e; 61 62 return 0; 63 } 64 65 static void free_inode_elem_list(struct extent_inode_elem *eie) 66 { 67 struct extent_inode_elem *eie_next; 68 69 for (; eie; eie = eie_next) { 70 eie_next = eie->next; 71 kfree(eie); 72 } 73 } 74 75 static int find_extent_in_eb(const struct extent_buffer *eb, 76 u64 wanted_disk_byte, u64 extent_item_pos, 77 struct extent_inode_elem **eie, 78 bool ignore_offset) 79 { 80 u64 disk_byte; 81 struct btrfs_key key; 82 struct btrfs_file_extent_item *fi; 83 int slot; 84 int nritems; 85 int extent_type; 86 int ret; 87 88 /* 89 * from the shared data ref, we only have the leaf but we need 90 * the key. thus, we must look into all items and see that we 91 * find one (some) with a reference to our extent item. 92 */ 93 nritems = btrfs_header_nritems(eb); 94 for (slot = 0; slot < nritems; ++slot) { 95 btrfs_item_key_to_cpu(eb, &key, slot); 96 if (key.type != BTRFS_EXTENT_DATA_KEY) 97 continue; 98 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); 99 extent_type = btrfs_file_extent_type(eb, fi); 100 if (extent_type == BTRFS_FILE_EXTENT_INLINE) 101 continue; 102 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */ 103 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); 104 if (disk_byte != wanted_disk_byte) 105 continue; 106 107 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie, ignore_offset); 108 if (ret < 0) 109 return ret; 110 } 111 112 return 0; 113 } 114 115 struct preftree { 116 struct rb_root_cached root; 117 unsigned int count; 118 }; 119 120 #define PREFTREE_INIT { .root = RB_ROOT_CACHED, .count = 0 } 121 122 struct preftrees { 123 struct preftree direct; /* BTRFS_SHARED_[DATA|BLOCK]_REF_KEY */ 124 struct preftree indirect; /* BTRFS_[TREE_BLOCK|EXTENT_DATA]_REF_KEY */ 125 struct preftree indirect_missing_keys; 126 }; 127 128 /* 129 * Checks for a shared extent during backref search. 130 * 131 * The share_count tracks prelim_refs (direct and indirect) having a 132 * ref->count >0: 133 * - incremented when a ref->count transitions to >0 134 * - decremented when a ref->count transitions to <1 135 */ 136 struct share_check { 137 u64 root_objectid; 138 u64 inum; 139 int share_count; 140 }; 141 142 static inline int extent_is_shared(struct share_check *sc) 143 { 144 return (sc && sc->share_count > 1) ? BACKREF_FOUND_SHARED : 0; 145 } 146 147 static struct kmem_cache *btrfs_prelim_ref_cache; 148 149 int __init btrfs_prelim_ref_init(void) 150 { 151 btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref", 152 sizeof(struct prelim_ref), 153 0, 154 SLAB_MEM_SPREAD, 155 NULL); 156 if (!btrfs_prelim_ref_cache) 157 return -ENOMEM; 158 return 0; 159 } 160 161 void __cold btrfs_prelim_ref_exit(void) 162 { 163 kmem_cache_destroy(btrfs_prelim_ref_cache); 164 } 165 166 static void free_pref(struct prelim_ref *ref) 167 { 168 kmem_cache_free(btrfs_prelim_ref_cache, ref); 169 } 170 171 /* 172 * Return 0 when both refs are for the same block (and can be merged). 173 * A -1 return indicates ref1 is a 'lower' block than ref2, while 1 174 * indicates a 'higher' block. 175 */ 176 static int prelim_ref_compare(struct prelim_ref *ref1, 177 struct prelim_ref *ref2) 178 { 179 if (ref1->level < ref2->level) 180 return -1; 181 if (ref1->level > ref2->level) 182 return 1; 183 if (ref1->root_id < ref2->root_id) 184 return -1; 185 if (ref1->root_id > ref2->root_id) 186 return 1; 187 if (ref1->key_for_search.type < ref2->key_for_search.type) 188 return -1; 189 if (ref1->key_for_search.type > ref2->key_for_search.type) 190 return 1; 191 if (ref1->key_for_search.objectid < ref2->key_for_search.objectid) 192 return -1; 193 if (ref1->key_for_search.objectid > ref2->key_for_search.objectid) 194 return 1; 195 if (ref1->key_for_search.offset < ref2->key_for_search.offset) 196 return -1; 197 if (ref1->key_for_search.offset > ref2->key_for_search.offset) 198 return 1; 199 if (ref1->parent < ref2->parent) 200 return -1; 201 if (ref1->parent > ref2->parent) 202 return 1; 203 204 return 0; 205 } 206 207 static void update_share_count(struct share_check *sc, int oldcount, 208 int newcount) 209 { 210 if ((!sc) || (oldcount == 0 && newcount < 1)) 211 return; 212 213 if (oldcount > 0 && newcount < 1) 214 sc->share_count--; 215 else if (oldcount < 1 && newcount > 0) 216 sc->share_count++; 217 } 218 219 /* 220 * Add @newref to the @root rbtree, merging identical refs. 221 * 222 * Callers should assume that newref has been freed after calling. 223 */ 224 static void prelim_ref_insert(const struct btrfs_fs_info *fs_info, 225 struct preftree *preftree, 226 struct prelim_ref *newref, 227 struct share_check *sc) 228 { 229 struct rb_root_cached *root; 230 struct rb_node **p; 231 struct rb_node *parent = NULL; 232 struct prelim_ref *ref; 233 int result; 234 bool leftmost = true; 235 236 root = &preftree->root; 237 p = &root->rb_root.rb_node; 238 239 while (*p) { 240 parent = *p; 241 ref = rb_entry(parent, struct prelim_ref, rbnode); 242 result = prelim_ref_compare(ref, newref); 243 if (result < 0) { 244 p = &(*p)->rb_left; 245 } else if (result > 0) { 246 p = &(*p)->rb_right; 247 leftmost = false; 248 } else { 249 /* Identical refs, merge them and free @newref */ 250 struct extent_inode_elem *eie = ref->inode_list; 251 252 while (eie && eie->next) 253 eie = eie->next; 254 255 if (!eie) 256 ref->inode_list = newref->inode_list; 257 else 258 eie->next = newref->inode_list; 259 trace_btrfs_prelim_ref_merge(fs_info, ref, newref, 260 preftree->count); 261 /* 262 * A delayed ref can have newref->count < 0. 263 * The ref->count is updated to follow any 264 * BTRFS_[ADD|DROP]_DELAYED_REF actions. 265 */ 266 update_share_count(sc, ref->count, 267 ref->count + newref->count); 268 ref->count += newref->count; 269 free_pref(newref); 270 return; 271 } 272 } 273 274 update_share_count(sc, 0, newref->count); 275 preftree->count++; 276 trace_btrfs_prelim_ref_insert(fs_info, newref, NULL, preftree->count); 277 rb_link_node(&newref->rbnode, parent, p); 278 rb_insert_color_cached(&newref->rbnode, root, leftmost); 279 } 280 281 /* 282 * Release the entire tree. We don't care about internal consistency so 283 * just free everything and then reset the tree root. 284 */ 285 static void prelim_release(struct preftree *preftree) 286 { 287 struct prelim_ref *ref, *next_ref; 288 289 rbtree_postorder_for_each_entry_safe(ref, next_ref, 290 &preftree->root.rb_root, rbnode) 291 free_pref(ref); 292 293 preftree->root = RB_ROOT_CACHED; 294 preftree->count = 0; 295 } 296 297 /* 298 * the rules for all callers of this function are: 299 * - obtaining the parent is the goal 300 * - if you add a key, you must know that it is a correct key 301 * - if you cannot add the parent or a correct key, then we will look into the 302 * block later to set a correct key 303 * 304 * delayed refs 305 * ============ 306 * backref type | shared | indirect | shared | indirect 307 * information | tree | tree | data | data 308 * --------------------+--------+----------+--------+---------- 309 * parent logical | y | - | - | - 310 * key to resolve | - | y | y | y 311 * tree block logical | - | - | - | - 312 * root for resolving | y | y | y | y 313 * 314 * - column 1: we've the parent -> done 315 * - column 2, 3, 4: we use the key to find the parent 316 * 317 * on disk refs (inline or keyed) 318 * ============================== 319 * backref type | shared | indirect | shared | indirect 320 * information | tree | tree | data | data 321 * --------------------+--------+----------+--------+---------- 322 * parent logical | y | - | y | - 323 * key to resolve | - | - | - | y 324 * tree block logical | y | y | y | y 325 * root for resolving | - | y | y | y 326 * 327 * - column 1, 3: we've the parent -> done 328 * - column 2: we take the first key from the block to find the parent 329 * (see add_missing_keys) 330 * - column 4: we use the key to find the parent 331 * 332 * additional information that's available but not required to find the parent 333 * block might help in merging entries to gain some speed. 334 */ 335 static int add_prelim_ref(const struct btrfs_fs_info *fs_info, 336 struct preftree *preftree, u64 root_id, 337 const struct btrfs_key *key, int level, u64 parent, 338 u64 wanted_disk_byte, int count, 339 struct share_check *sc, gfp_t gfp_mask) 340 { 341 struct prelim_ref *ref; 342 343 if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID) 344 return 0; 345 346 ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask); 347 if (!ref) 348 return -ENOMEM; 349 350 ref->root_id = root_id; 351 if (key) 352 ref->key_for_search = *key; 353 else 354 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search)); 355 356 ref->inode_list = NULL; 357 ref->level = level; 358 ref->count = count; 359 ref->parent = parent; 360 ref->wanted_disk_byte = wanted_disk_byte; 361 prelim_ref_insert(fs_info, preftree, ref, sc); 362 return extent_is_shared(sc); 363 } 364 365 /* direct refs use root == 0, key == NULL */ 366 static int add_direct_ref(const struct btrfs_fs_info *fs_info, 367 struct preftrees *preftrees, int level, u64 parent, 368 u64 wanted_disk_byte, int count, 369 struct share_check *sc, gfp_t gfp_mask) 370 { 371 return add_prelim_ref(fs_info, &preftrees->direct, 0, NULL, level, 372 parent, wanted_disk_byte, count, sc, gfp_mask); 373 } 374 375 /* indirect refs use parent == 0 */ 376 static int add_indirect_ref(const struct btrfs_fs_info *fs_info, 377 struct preftrees *preftrees, u64 root_id, 378 const struct btrfs_key *key, int level, 379 u64 wanted_disk_byte, int count, 380 struct share_check *sc, gfp_t gfp_mask) 381 { 382 struct preftree *tree = &preftrees->indirect; 383 384 if (!key) 385 tree = &preftrees->indirect_missing_keys; 386 return add_prelim_ref(fs_info, tree, root_id, key, level, 0, 387 wanted_disk_byte, count, sc, gfp_mask); 388 } 389 390 static int is_shared_data_backref(struct preftrees *preftrees, u64 bytenr) 391 { 392 struct rb_node **p = &preftrees->direct.root.rb_root.rb_node; 393 struct rb_node *parent = NULL; 394 struct prelim_ref *ref = NULL; 395 struct prelim_ref target = {}; 396 int result; 397 398 target.parent = bytenr; 399 400 while (*p) { 401 parent = *p; 402 ref = rb_entry(parent, struct prelim_ref, rbnode); 403 result = prelim_ref_compare(ref, &target); 404 405 if (result < 0) 406 p = &(*p)->rb_left; 407 else if (result > 0) 408 p = &(*p)->rb_right; 409 else 410 return 1; 411 } 412 return 0; 413 } 414 415 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path, 416 struct ulist *parents, 417 struct preftrees *preftrees, struct prelim_ref *ref, 418 int level, u64 time_seq, const u64 *extent_item_pos, 419 bool ignore_offset) 420 { 421 int ret = 0; 422 int slot; 423 struct extent_buffer *eb; 424 struct btrfs_key key; 425 struct btrfs_key *key_for_search = &ref->key_for_search; 426 struct btrfs_file_extent_item *fi; 427 struct extent_inode_elem *eie = NULL, *old = NULL; 428 u64 disk_byte; 429 u64 wanted_disk_byte = ref->wanted_disk_byte; 430 u64 count = 0; 431 u64 data_offset; 432 433 if (level != 0) { 434 eb = path->nodes[level]; 435 ret = ulist_add(parents, eb->start, 0, GFP_NOFS); 436 if (ret < 0) 437 return ret; 438 return 0; 439 } 440 441 /* 442 * 1. We normally enter this function with the path already pointing to 443 * the first item to check. But sometimes, we may enter it with 444 * slot == nritems. 445 * 2. We are searching for normal backref but bytenr of this leaf 446 * matches shared data backref 447 * 3. The leaf owner is not equal to the root we are searching 448 * 449 * For these cases, go to the next leaf before we continue. 450 */ 451 eb = path->nodes[0]; 452 if (path->slots[0] >= btrfs_header_nritems(eb) || 453 is_shared_data_backref(preftrees, eb->start) || 454 ref->root_id != btrfs_header_owner(eb)) { 455 if (time_seq == SEQ_LAST) 456 ret = btrfs_next_leaf(root, path); 457 else 458 ret = btrfs_next_old_leaf(root, path, time_seq); 459 } 460 461 while (!ret && count < ref->count) { 462 eb = path->nodes[0]; 463 slot = path->slots[0]; 464 465 btrfs_item_key_to_cpu(eb, &key, slot); 466 467 if (key.objectid != key_for_search->objectid || 468 key.type != BTRFS_EXTENT_DATA_KEY) 469 break; 470 471 /* 472 * We are searching for normal backref but bytenr of this leaf 473 * matches shared data backref, OR 474 * the leaf owner is not equal to the root we are searching for 475 */ 476 if (slot == 0 && 477 (is_shared_data_backref(preftrees, eb->start) || 478 ref->root_id != btrfs_header_owner(eb))) { 479 if (time_seq == SEQ_LAST) 480 ret = btrfs_next_leaf(root, path); 481 else 482 ret = btrfs_next_old_leaf(root, path, time_seq); 483 continue; 484 } 485 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item); 486 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi); 487 data_offset = btrfs_file_extent_offset(eb, fi); 488 489 if (disk_byte == wanted_disk_byte) { 490 eie = NULL; 491 old = NULL; 492 if (ref->key_for_search.offset == key.offset - data_offset) 493 count++; 494 else 495 goto next; 496 if (extent_item_pos) { 497 ret = check_extent_in_eb(&key, eb, fi, 498 *extent_item_pos, 499 &eie, ignore_offset); 500 if (ret < 0) 501 break; 502 } 503 if (ret > 0) 504 goto next; 505 ret = ulist_add_merge_ptr(parents, eb->start, 506 eie, (void **)&old, GFP_NOFS); 507 if (ret < 0) 508 break; 509 if (!ret && extent_item_pos) { 510 while (old->next) 511 old = old->next; 512 old->next = eie; 513 } 514 eie = NULL; 515 } 516 next: 517 if (time_seq == SEQ_LAST) 518 ret = btrfs_next_item(root, path); 519 else 520 ret = btrfs_next_old_item(root, path, time_seq); 521 } 522 523 if (ret > 0) 524 ret = 0; 525 else if (ret < 0) 526 free_inode_elem_list(eie); 527 return ret; 528 } 529 530 /* 531 * resolve an indirect backref in the form (root_id, key, level) 532 * to a logical address 533 */ 534 static int resolve_indirect_ref(struct btrfs_fs_info *fs_info, 535 struct btrfs_path *path, u64 time_seq, 536 struct preftrees *preftrees, 537 struct prelim_ref *ref, struct ulist *parents, 538 const u64 *extent_item_pos, bool ignore_offset) 539 { 540 struct btrfs_root *root; 541 struct extent_buffer *eb; 542 int ret = 0; 543 int root_level; 544 int level = ref->level; 545 struct btrfs_key search_key = ref->key_for_search; 546 547 root = btrfs_get_fs_root(fs_info, ref->root_id, false); 548 if (IS_ERR(root)) { 549 ret = PTR_ERR(root); 550 goto out_free; 551 } 552 553 if (!path->search_commit_root && 554 test_bit(BTRFS_ROOT_DELETING, &root->state)) { 555 ret = -ENOENT; 556 goto out; 557 } 558 559 if (btrfs_is_testing(fs_info)) { 560 ret = -ENOENT; 561 goto out; 562 } 563 564 if (path->search_commit_root) 565 root_level = btrfs_header_level(root->commit_root); 566 else if (time_seq == SEQ_LAST) 567 root_level = btrfs_header_level(root->node); 568 else 569 root_level = btrfs_old_root_level(root, time_seq); 570 571 if (root_level + 1 == level) 572 goto out; 573 574 /* 575 * We can often find data backrefs with an offset that is too large 576 * (>= LLONG_MAX, maximum allowed file offset) due to underflows when 577 * subtracting a file's offset with the data offset of its 578 * corresponding extent data item. This can happen for example in the 579 * clone ioctl. 580 * 581 * So if we detect such case we set the search key's offset to zero to 582 * make sure we will find the matching file extent item at 583 * add_all_parents(), otherwise we will miss it because the offset 584 * taken form the backref is much larger then the offset of the file 585 * extent item. This can make us scan a very large number of file 586 * extent items, but at least it will not make us miss any. 587 * 588 * This is an ugly workaround for a behaviour that should have never 589 * existed, but it does and a fix for the clone ioctl would touch a lot 590 * of places, cause backwards incompatibility and would not fix the 591 * problem for extents cloned with older kernels. 592 */ 593 if (search_key.type == BTRFS_EXTENT_DATA_KEY && 594 search_key.offset >= LLONG_MAX) 595 search_key.offset = 0; 596 path->lowest_level = level; 597 if (time_seq == SEQ_LAST) 598 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0); 599 else 600 ret = btrfs_search_old_slot(root, &search_key, path, time_seq); 601 602 btrfs_debug(fs_info, 603 "search slot in root %llu (level %d, ref count %d) returned %d for key (%llu %u %llu)", 604 ref->root_id, level, ref->count, ret, 605 ref->key_for_search.objectid, ref->key_for_search.type, 606 ref->key_for_search.offset); 607 if (ret < 0) 608 goto out; 609 610 eb = path->nodes[level]; 611 while (!eb) { 612 if (WARN_ON(!level)) { 613 ret = 1; 614 goto out; 615 } 616 level--; 617 eb = path->nodes[level]; 618 } 619 620 ret = add_all_parents(root, path, parents, preftrees, ref, level, 621 time_seq, extent_item_pos, ignore_offset); 622 out: 623 btrfs_put_root(root); 624 out_free: 625 path->lowest_level = 0; 626 btrfs_release_path(path); 627 return ret; 628 } 629 630 static struct extent_inode_elem * 631 unode_aux_to_inode_list(struct ulist_node *node) 632 { 633 if (!node) 634 return NULL; 635 return (struct extent_inode_elem *)(uintptr_t)node->aux; 636 } 637 638 /* 639 * We maintain three separate rbtrees: one for direct refs, one for 640 * indirect refs which have a key, and one for indirect refs which do not 641 * have a key. Each tree does merge on insertion. 642 * 643 * Once all of the references are located, we iterate over the tree of 644 * indirect refs with missing keys. An appropriate key is located and 645 * the ref is moved onto the tree for indirect refs. After all missing 646 * keys are thus located, we iterate over the indirect ref tree, resolve 647 * each reference, and then insert the resolved reference onto the 648 * direct tree (merging there too). 649 * 650 * New backrefs (i.e., for parent nodes) are added to the appropriate 651 * rbtree as they are encountered. The new backrefs are subsequently 652 * resolved as above. 653 */ 654 static int resolve_indirect_refs(struct btrfs_fs_info *fs_info, 655 struct btrfs_path *path, u64 time_seq, 656 struct preftrees *preftrees, 657 const u64 *extent_item_pos, 658 struct share_check *sc, bool ignore_offset) 659 { 660 int err; 661 int ret = 0; 662 struct ulist *parents; 663 struct ulist_node *node; 664 struct ulist_iterator uiter; 665 struct rb_node *rnode; 666 667 parents = ulist_alloc(GFP_NOFS); 668 if (!parents) 669 return -ENOMEM; 670 671 /* 672 * We could trade memory usage for performance here by iterating 673 * the tree, allocating new refs for each insertion, and then 674 * freeing the entire indirect tree when we're done. In some test 675 * cases, the tree can grow quite large (~200k objects). 676 */ 677 while ((rnode = rb_first_cached(&preftrees->indirect.root))) { 678 struct prelim_ref *ref; 679 680 ref = rb_entry(rnode, struct prelim_ref, rbnode); 681 if (WARN(ref->parent, 682 "BUG: direct ref found in indirect tree")) { 683 ret = -EINVAL; 684 goto out; 685 } 686 687 rb_erase_cached(&ref->rbnode, &preftrees->indirect.root); 688 preftrees->indirect.count--; 689 690 if (ref->count == 0) { 691 free_pref(ref); 692 continue; 693 } 694 695 if (sc && sc->root_objectid && 696 ref->root_id != sc->root_objectid) { 697 free_pref(ref); 698 ret = BACKREF_FOUND_SHARED; 699 goto out; 700 } 701 err = resolve_indirect_ref(fs_info, path, time_seq, preftrees, 702 ref, parents, extent_item_pos, 703 ignore_offset); 704 /* 705 * we can only tolerate ENOENT,otherwise,we should catch error 706 * and return directly. 707 */ 708 if (err == -ENOENT) { 709 prelim_ref_insert(fs_info, &preftrees->direct, ref, 710 NULL); 711 continue; 712 } else if (err) { 713 free_pref(ref); 714 ret = err; 715 goto out; 716 } 717 718 /* we put the first parent into the ref at hand */ 719 ULIST_ITER_INIT(&uiter); 720 node = ulist_next(parents, &uiter); 721 ref->parent = node ? node->val : 0; 722 ref->inode_list = unode_aux_to_inode_list(node); 723 724 /* Add a prelim_ref(s) for any other parent(s). */ 725 while ((node = ulist_next(parents, &uiter))) { 726 struct prelim_ref *new_ref; 727 728 new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache, 729 GFP_NOFS); 730 if (!new_ref) { 731 free_pref(ref); 732 ret = -ENOMEM; 733 goto out; 734 } 735 memcpy(new_ref, ref, sizeof(*ref)); 736 new_ref->parent = node->val; 737 new_ref->inode_list = unode_aux_to_inode_list(node); 738 prelim_ref_insert(fs_info, &preftrees->direct, 739 new_ref, NULL); 740 } 741 742 /* 743 * Now it's a direct ref, put it in the direct tree. We must 744 * do this last because the ref could be merged/freed here. 745 */ 746 prelim_ref_insert(fs_info, &preftrees->direct, ref, NULL); 747 748 ulist_reinit(parents); 749 cond_resched(); 750 } 751 out: 752 ulist_free(parents); 753 return ret; 754 } 755 756 /* 757 * read tree blocks and add keys where required. 758 */ 759 static int add_missing_keys(struct btrfs_fs_info *fs_info, 760 struct preftrees *preftrees, bool lock) 761 { 762 struct prelim_ref *ref; 763 struct extent_buffer *eb; 764 struct preftree *tree = &preftrees->indirect_missing_keys; 765 struct rb_node *node; 766 767 while ((node = rb_first_cached(&tree->root))) { 768 ref = rb_entry(node, struct prelim_ref, rbnode); 769 rb_erase_cached(node, &tree->root); 770 771 BUG_ON(ref->parent); /* should not be a direct ref */ 772 BUG_ON(ref->key_for_search.type); 773 BUG_ON(!ref->wanted_disk_byte); 774 775 eb = read_tree_block(fs_info, ref->wanted_disk_byte, 0, 776 ref->level - 1, NULL); 777 if (IS_ERR(eb)) { 778 free_pref(ref); 779 return PTR_ERR(eb); 780 } else if (!extent_buffer_uptodate(eb)) { 781 free_pref(ref); 782 free_extent_buffer(eb); 783 return -EIO; 784 } 785 if (lock) 786 btrfs_tree_read_lock(eb); 787 if (btrfs_header_level(eb) == 0) 788 btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0); 789 else 790 btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0); 791 if (lock) 792 btrfs_tree_read_unlock(eb); 793 free_extent_buffer(eb); 794 prelim_ref_insert(fs_info, &preftrees->indirect, ref, NULL); 795 cond_resched(); 796 } 797 return 0; 798 } 799 800 /* 801 * add all currently queued delayed refs from this head whose seq nr is 802 * smaller or equal that seq to the list 803 */ 804 static int add_delayed_refs(const struct btrfs_fs_info *fs_info, 805 struct btrfs_delayed_ref_head *head, u64 seq, 806 struct preftrees *preftrees, struct share_check *sc) 807 { 808 struct btrfs_delayed_ref_node *node; 809 struct btrfs_delayed_extent_op *extent_op = head->extent_op; 810 struct btrfs_key key; 811 struct btrfs_key tmp_op_key; 812 struct rb_node *n; 813 int count; 814 int ret = 0; 815 816 if (extent_op && extent_op->update_key) 817 btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key); 818 819 spin_lock(&head->lock); 820 for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) { 821 node = rb_entry(n, struct btrfs_delayed_ref_node, 822 ref_node); 823 if (node->seq > seq) 824 continue; 825 826 switch (node->action) { 827 case BTRFS_ADD_DELAYED_EXTENT: 828 case BTRFS_UPDATE_DELAYED_HEAD: 829 WARN_ON(1); 830 continue; 831 case BTRFS_ADD_DELAYED_REF: 832 count = node->ref_mod; 833 break; 834 case BTRFS_DROP_DELAYED_REF: 835 count = node->ref_mod * -1; 836 break; 837 default: 838 BUG(); 839 } 840 switch (node->type) { 841 case BTRFS_TREE_BLOCK_REF_KEY: { 842 /* NORMAL INDIRECT METADATA backref */ 843 struct btrfs_delayed_tree_ref *ref; 844 845 ref = btrfs_delayed_node_to_tree_ref(node); 846 ret = add_indirect_ref(fs_info, preftrees, ref->root, 847 &tmp_op_key, ref->level + 1, 848 node->bytenr, count, sc, 849 GFP_ATOMIC); 850 break; 851 } 852 case BTRFS_SHARED_BLOCK_REF_KEY: { 853 /* SHARED DIRECT METADATA backref */ 854 struct btrfs_delayed_tree_ref *ref; 855 856 ref = btrfs_delayed_node_to_tree_ref(node); 857 858 ret = add_direct_ref(fs_info, preftrees, ref->level + 1, 859 ref->parent, node->bytenr, count, 860 sc, GFP_ATOMIC); 861 break; 862 } 863 case BTRFS_EXTENT_DATA_REF_KEY: { 864 /* NORMAL INDIRECT DATA backref */ 865 struct btrfs_delayed_data_ref *ref; 866 ref = btrfs_delayed_node_to_data_ref(node); 867 868 key.objectid = ref->objectid; 869 key.type = BTRFS_EXTENT_DATA_KEY; 870 key.offset = ref->offset; 871 872 /* 873 * Found a inum that doesn't match our known inum, we 874 * know it's shared. 875 */ 876 if (sc && sc->inum && ref->objectid != sc->inum) { 877 ret = BACKREF_FOUND_SHARED; 878 goto out; 879 } 880 881 ret = add_indirect_ref(fs_info, preftrees, ref->root, 882 &key, 0, node->bytenr, count, sc, 883 GFP_ATOMIC); 884 break; 885 } 886 case BTRFS_SHARED_DATA_REF_KEY: { 887 /* SHARED DIRECT FULL backref */ 888 struct btrfs_delayed_data_ref *ref; 889 890 ref = btrfs_delayed_node_to_data_ref(node); 891 892 ret = add_direct_ref(fs_info, preftrees, 0, ref->parent, 893 node->bytenr, count, sc, 894 GFP_ATOMIC); 895 break; 896 } 897 default: 898 WARN_ON(1); 899 } 900 /* 901 * We must ignore BACKREF_FOUND_SHARED until all delayed 902 * refs have been checked. 903 */ 904 if (ret && (ret != BACKREF_FOUND_SHARED)) 905 break; 906 } 907 if (!ret) 908 ret = extent_is_shared(sc); 909 out: 910 spin_unlock(&head->lock); 911 return ret; 912 } 913 914 /* 915 * add all inline backrefs for bytenr to the list 916 * 917 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED. 918 */ 919 static int add_inline_refs(const struct btrfs_fs_info *fs_info, 920 struct btrfs_path *path, u64 bytenr, 921 int *info_level, struct preftrees *preftrees, 922 struct share_check *sc) 923 { 924 int ret = 0; 925 int slot; 926 struct extent_buffer *leaf; 927 struct btrfs_key key; 928 struct btrfs_key found_key; 929 unsigned long ptr; 930 unsigned long end; 931 struct btrfs_extent_item *ei; 932 u64 flags; 933 u64 item_size; 934 935 /* 936 * enumerate all inline refs 937 */ 938 leaf = path->nodes[0]; 939 slot = path->slots[0]; 940 941 item_size = btrfs_item_size_nr(leaf, slot); 942 BUG_ON(item_size < sizeof(*ei)); 943 944 ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item); 945 flags = btrfs_extent_flags(leaf, ei); 946 btrfs_item_key_to_cpu(leaf, &found_key, slot); 947 948 ptr = (unsigned long)(ei + 1); 949 end = (unsigned long)ei + item_size; 950 951 if (found_key.type == BTRFS_EXTENT_ITEM_KEY && 952 flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { 953 struct btrfs_tree_block_info *info; 954 955 info = (struct btrfs_tree_block_info *)ptr; 956 *info_level = btrfs_tree_block_level(leaf, info); 957 ptr += sizeof(struct btrfs_tree_block_info); 958 BUG_ON(ptr > end); 959 } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) { 960 *info_level = found_key.offset; 961 } else { 962 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA)); 963 } 964 965 while (ptr < end) { 966 struct btrfs_extent_inline_ref *iref; 967 u64 offset; 968 int type; 969 970 iref = (struct btrfs_extent_inline_ref *)ptr; 971 type = btrfs_get_extent_inline_ref_type(leaf, iref, 972 BTRFS_REF_TYPE_ANY); 973 if (type == BTRFS_REF_TYPE_INVALID) 974 return -EUCLEAN; 975 976 offset = btrfs_extent_inline_ref_offset(leaf, iref); 977 978 switch (type) { 979 case BTRFS_SHARED_BLOCK_REF_KEY: 980 ret = add_direct_ref(fs_info, preftrees, 981 *info_level + 1, offset, 982 bytenr, 1, NULL, GFP_NOFS); 983 break; 984 case BTRFS_SHARED_DATA_REF_KEY: { 985 struct btrfs_shared_data_ref *sdref; 986 int count; 987 988 sdref = (struct btrfs_shared_data_ref *)(iref + 1); 989 count = btrfs_shared_data_ref_count(leaf, sdref); 990 991 ret = add_direct_ref(fs_info, preftrees, 0, offset, 992 bytenr, count, sc, GFP_NOFS); 993 break; 994 } 995 case BTRFS_TREE_BLOCK_REF_KEY: 996 ret = add_indirect_ref(fs_info, preftrees, offset, 997 NULL, *info_level + 1, 998 bytenr, 1, NULL, GFP_NOFS); 999 break; 1000 case BTRFS_EXTENT_DATA_REF_KEY: { 1001 struct btrfs_extent_data_ref *dref; 1002 int count; 1003 u64 root; 1004 1005 dref = (struct btrfs_extent_data_ref *)(&iref->offset); 1006 count = btrfs_extent_data_ref_count(leaf, dref); 1007 key.objectid = btrfs_extent_data_ref_objectid(leaf, 1008 dref); 1009 key.type = BTRFS_EXTENT_DATA_KEY; 1010 key.offset = btrfs_extent_data_ref_offset(leaf, dref); 1011 1012 if (sc && sc->inum && key.objectid != sc->inum) { 1013 ret = BACKREF_FOUND_SHARED; 1014 break; 1015 } 1016 1017 root = btrfs_extent_data_ref_root(leaf, dref); 1018 1019 ret = add_indirect_ref(fs_info, preftrees, root, 1020 &key, 0, bytenr, count, 1021 sc, GFP_NOFS); 1022 break; 1023 } 1024 default: 1025 WARN_ON(1); 1026 } 1027 if (ret) 1028 return ret; 1029 ptr += btrfs_extent_inline_ref_size(type); 1030 } 1031 1032 return 0; 1033 } 1034 1035 /* 1036 * add all non-inline backrefs for bytenr to the list 1037 * 1038 * Returns 0 on success, <0 on error, or BACKREF_FOUND_SHARED. 1039 */ 1040 static int add_keyed_refs(struct btrfs_fs_info *fs_info, 1041 struct btrfs_path *path, u64 bytenr, 1042 int info_level, struct preftrees *preftrees, 1043 struct share_check *sc) 1044 { 1045 struct btrfs_root *extent_root = fs_info->extent_root; 1046 int ret; 1047 int slot; 1048 struct extent_buffer *leaf; 1049 struct btrfs_key key; 1050 1051 while (1) { 1052 ret = btrfs_next_item(extent_root, path); 1053 if (ret < 0) 1054 break; 1055 if (ret) { 1056 ret = 0; 1057 break; 1058 } 1059 1060 slot = path->slots[0]; 1061 leaf = path->nodes[0]; 1062 btrfs_item_key_to_cpu(leaf, &key, slot); 1063 1064 if (key.objectid != bytenr) 1065 break; 1066 if (key.type < BTRFS_TREE_BLOCK_REF_KEY) 1067 continue; 1068 if (key.type > BTRFS_SHARED_DATA_REF_KEY) 1069 break; 1070 1071 switch (key.type) { 1072 case BTRFS_SHARED_BLOCK_REF_KEY: 1073 /* SHARED DIRECT METADATA backref */ 1074 ret = add_direct_ref(fs_info, preftrees, 1075 info_level + 1, key.offset, 1076 bytenr, 1, NULL, GFP_NOFS); 1077 break; 1078 case BTRFS_SHARED_DATA_REF_KEY: { 1079 /* SHARED DIRECT FULL backref */ 1080 struct btrfs_shared_data_ref *sdref; 1081 int count; 1082 1083 sdref = btrfs_item_ptr(leaf, slot, 1084 struct btrfs_shared_data_ref); 1085 count = btrfs_shared_data_ref_count(leaf, sdref); 1086 ret = add_direct_ref(fs_info, preftrees, 0, 1087 key.offset, bytenr, count, 1088 sc, GFP_NOFS); 1089 break; 1090 } 1091 case BTRFS_TREE_BLOCK_REF_KEY: 1092 /* NORMAL INDIRECT METADATA backref */ 1093 ret = add_indirect_ref(fs_info, preftrees, key.offset, 1094 NULL, info_level + 1, bytenr, 1095 1, NULL, GFP_NOFS); 1096 break; 1097 case BTRFS_EXTENT_DATA_REF_KEY: { 1098 /* NORMAL INDIRECT DATA backref */ 1099 struct btrfs_extent_data_ref *dref; 1100 int count; 1101 u64 root; 1102 1103 dref = btrfs_item_ptr(leaf, slot, 1104 struct btrfs_extent_data_ref); 1105 count = btrfs_extent_data_ref_count(leaf, dref); 1106 key.objectid = btrfs_extent_data_ref_objectid(leaf, 1107 dref); 1108 key.type = BTRFS_EXTENT_DATA_KEY; 1109 key.offset = btrfs_extent_data_ref_offset(leaf, dref); 1110 1111 if (sc && sc->inum && key.objectid != sc->inum) { 1112 ret = BACKREF_FOUND_SHARED; 1113 break; 1114 } 1115 1116 root = btrfs_extent_data_ref_root(leaf, dref); 1117 ret = add_indirect_ref(fs_info, preftrees, root, 1118 &key, 0, bytenr, count, 1119 sc, GFP_NOFS); 1120 break; 1121 } 1122 default: 1123 WARN_ON(1); 1124 } 1125 if (ret) 1126 return ret; 1127 1128 } 1129 1130 return ret; 1131 } 1132 1133 /* 1134 * this adds all existing backrefs (inline backrefs, backrefs and delayed 1135 * refs) for the given bytenr to the refs list, merges duplicates and resolves 1136 * indirect refs to their parent bytenr. 1137 * When roots are found, they're added to the roots list 1138 * 1139 * If time_seq is set to SEQ_LAST, it will not search delayed_refs, and behave 1140 * much like trans == NULL case, the difference only lies in it will not 1141 * commit root. 1142 * The special case is for qgroup to search roots in commit_transaction(). 1143 * 1144 * @sc - if !NULL, then immediately return BACKREF_FOUND_SHARED when a 1145 * shared extent is detected. 1146 * 1147 * Otherwise this returns 0 for success and <0 for an error. 1148 * 1149 * If ignore_offset is set to false, only extent refs whose offsets match 1150 * extent_item_pos are returned. If true, every extent ref is returned 1151 * and extent_item_pos is ignored. 1152 * 1153 * FIXME some caching might speed things up 1154 */ 1155 static int find_parent_nodes(struct btrfs_trans_handle *trans, 1156 struct btrfs_fs_info *fs_info, u64 bytenr, 1157 u64 time_seq, struct ulist *refs, 1158 struct ulist *roots, const u64 *extent_item_pos, 1159 struct share_check *sc, bool ignore_offset) 1160 { 1161 struct btrfs_key key; 1162 struct btrfs_path *path; 1163 struct btrfs_delayed_ref_root *delayed_refs = NULL; 1164 struct btrfs_delayed_ref_head *head; 1165 int info_level = 0; 1166 int ret; 1167 struct prelim_ref *ref; 1168 struct rb_node *node; 1169 struct extent_inode_elem *eie = NULL; 1170 struct preftrees preftrees = { 1171 .direct = PREFTREE_INIT, 1172 .indirect = PREFTREE_INIT, 1173 .indirect_missing_keys = PREFTREE_INIT 1174 }; 1175 1176 key.objectid = bytenr; 1177 key.offset = (u64)-1; 1178 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA)) 1179 key.type = BTRFS_METADATA_ITEM_KEY; 1180 else 1181 key.type = BTRFS_EXTENT_ITEM_KEY; 1182 1183 path = btrfs_alloc_path(); 1184 if (!path) 1185 return -ENOMEM; 1186 if (!trans) { 1187 path->search_commit_root = 1; 1188 path->skip_locking = 1; 1189 } 1190 1191 if (time_seq == SEQ_LAST) 1192 path->skip_locking = 1; 1193 1194 /* 1195 * grab both a lock on the path and a lock on the delayed ref head. 1196 * We need both to get a consistent picture of how the refs look 1197 * at a specified point in time 1198 */ 1199 again: 1200 head = NULL; 1201 1202 ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0); 1203 if (ret < 0) 1204 goto out; 1205 BUG_ON(ret == 0); 1206 1207 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS 1208 if (trans && likely(trans->type != __TRANS_DUMMY) && 1209 time_seq != SEQ_LAST) { 1210 #else 1211 if (trans && time_seq != SEQ_LAST) { 1212 #endif 1213 /* 1214 * look if there are updates for this ref queued and lock the 1215 * head 1216 */ 1217 delayed_refs = &trans->transaction->delayed_refs; 1218 spin_lock(&delayed_refs->lock); 1219 head = btrfs_find_delayed_ref_head(delayed_refs, bytenr); 1220 if (head) { 1221 if (!mutex_trylock(&head->mutex)) { 1222 refcount_inc(&head->refs); 1223 spin_unlock(&delayed_refs->lock); 1224 1225 btrfs_release_path(path); 1226 1227 /* 1228 * Mutex was contended, block until it's 1229 * released and try again 1230 */ 1231 mutex_lock(&head->mutex); 1232 mutex_unlock(&head->mutex); 1233 btrfs_put_delayed_ref_head(head); 1234 goto again; 1235 } 1236 spin_unlock(&delayed_refs->lock); 1237 ret = add_delayed_refs(fs_info, head, time_seq, 1238 &preftrees, sc); 1239 mutex_unlock(&head->mutex); 1240 if (ret) 1241 goto out; 1242 } else { 1243 spin_unlock(&delayed_refs->lock); 1244 } 1245 } 1246 1247 if (path->slots[0]) { 1248 struct extent_buffer *leaf; 1249 int slot; 1250 1251 path->slots[0]--; 1252 leaf = path->nodes[0]; 1253 slot = path->slots[0]; 1254 btrfs_item_key_to_cpu(leaf, &key, slot); 1255 if (key.objectid == bytenr && 1256 (key.type == BTRFS_EXTENT_ITEM_KEY || 1257 key.type == BTRFS_METADATA_ITEM_KEY)) { 1258 ret = add_inline_refs(fs_info, path, bytenr, 1259 &info_level, &preftrees, sc); 1260 if (ret) 1261 goto out; 1262 ret = add_keyed_refs(fs_info, path, bytenr, info_level, 1263 &preftrees, sc); 1264 if (ret) 1265 goto out; 1266 } 1267 } 1268 1269 btrfs_release_path(path); 1270 1271 ret = add_missing_keys(fs_info, &preftrees, path->skip_locking == 0); 1272 if (ret) 1273 goto out; 1274 1275 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect_missing_keys.root.rb_root)); 1276 1277 ret = resolve_indirect_refs(fs_info, path, time_seq, &preftrees, 1278 extent_item_pos, sc, ignore_offset); 1279 if (ret) 1280 goto out; 1281 1282 WARN_ON(!RB_EMPTY_ROOT(&preftrees.indirect.root.rb_root)); 1283 1284 /* 1285 * This walks the tree of merged and resolved refs. Tree blocks are 1286 * read in as needed. Unique entries are added to the ulist, and 1287 * the list of found roots is updated. 1288 * 1289 * We release the entire tree in one go before returning. 1290 */ 1291 node = rb_first_cached(&preftrees.direct.root); 1292 while (node) { 1293 ref = rb_entry(node, struct prelim_ref, rbnode); 1294 node = rb_next(&ref->rbnode); 1295 /* 1296 * ref->count < 0 can happen here if there are delayed 1297 * refs with a node->action of BTRFS_DROP_DELAYED_REF. 1298 * prelim_ref_insert() relies on this when merging 1299 * identical refs to keep the overall count correct. 1300 * prelim_ref_insert() will merge only those refs 1301 * which compare identically. Any refs having 1302 * e.g. different offsets would not be merged, 1303 * and would retain their original ref->count < 0. 1304 */ 1305 if (roots && ref->count && ref->root_id && ref->parent == 0) { 1306 if (sc && sc->root_objectid && 1307 ref->root_id != sc->root_objectid) { 1308 ret = BACKREF_FOUND_SHARED; 1309 goto out; 1310 } 1311 1312 /* no parent == root of tree */ 1313 ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS); 1314 if (ret < 0) 1315 goto out; 1316 } 1317 if (ref->count && ref->parent) { 1318 if (extent_item_pos && !ref->inode_list && 1319 ref->level == 0) { 1320 struct extent_buffer *eb; 1321 1322 eb = read_tree_block(fs_info, ref->parent, 0, 1323 ref->level, NULL); 1324 if (IS_ERR(eb)) { 1325 ret = PTR_ERR(eb); 1326 goto out; 1327 } else if (!extent_buffer_uptodate(eb)) { 1328 free_extent_buffer(eb); 1329 ret = -EIO; 1330 goto out; 1331 } 1332 1333 if (!path->skip_locking) { 1334 btrfs_tree_read_lock(eb); 1335 btrfs_set_lock_blocking_read(eb); 1336 } 1337 ret = find_extent_in_eb(eb, bytenr, 1338 *extent_item_pos, &eie, ignore_offset); 1339 if (!path->skip_locking) 1340 btrfs_tree_read_unlock_blocking(eb); 1341 free_extent_buffer(eb); 1342 if (ret < 0) 1343 goto out; 1344 ref->inode_list = eie; 1345 } 1346 ret = ulist_add_merge_ptr(refs, ref->parent, 1347 ref->inode_list, 1348 (void **)&eie, GFP_NOFS); 1349 if (ret < 0) 1350 goto out; 1351 if (!ret && extent_item_pos) { 1352 /* 1353 * we've recorded that parent, so we must extend 1354 * its inode list here 1355 */ 1356 BUG_ON(!eie); 1357 while (eie->next) 1358 eie = eie->next; 1359 eie->next = ref->inode_list; 1360 } 1361 eie = NULL; 1362 } 1363 cond_resched(); 1364 } 1365 1366 out: 1367 btrfs_free_path(path); 1368 1369 prelim_release(&preftrees.direct); 1370 prelim_release(&preftrees.indirect); 1371 prelim_release(&preftrees.indirect_missing_keys); 1372 1373 if (ret < 0) 1374 free_inode_elem_list(eie); 1375 return ret; 1376 } 1377 1378 static void free_leaf_list(struct ulist *blocks) 1379 { 1380 struct ulist_node *node = NULL; 1381 struct extent_inode_elem *eie; 1382 struct ulist_iterator uiter; 1383 1384 ULIST_ITER_INIT(&uiter); 1385 while ((node = ulist_next(blocks, &uiter))) { 1386 if (!node->aux) 1387 continue; 1388 eie = unode_aux_to_inode_list(node); 1389 free_inode_elem_list(eie); 1390 node->aux = 0; 1391 } 1392 1393 ulist_free(blocks); 1394 } 1395 1396 /* 1397 * Finds all leafs with a reference to the specified combination of bytenr and 1398 * offset. key_list_head will point to a list of corresponding keys (caller must 1399 * free each list element). The leafs will be stored in the leafs ulist, which 1400 * must be freed with ulist_free. 1401 * 1402 * returns 0 on success, <0 on error 1403 */ 1404 int btrfs_find_all_leafs(struct btrfs_trans_handle *trans, 1405 struct btrfs_fs_info *fs_info, u64 bytenr, 1406 u64 time_seq, struct ulist **leafs, 1407 const u64 *extent_item_pos, bool ignore_offset) 1408 { 1409 int ret; 1410 1411 *leafs = ulist_alloc(GFP_NOFS); 1412 if (!*leafs) 1413 return -ENOMEM; 1414 1415 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq, 1416 *leafs, NULL, extent_item_pos, NULL, ignore_offset); 1417 if (ret < 0 && ret != -ENOENT) { 1418 free_leaf_list(*leafs); 1419 return ret; 1420 } 1421 1422 return 0; 1423 } 1424 1425 /* 1426 * walk all backrefs for a given extent to find all roots that reference this 1427 * extent. Walking a backref means finding all extents that reference this 1428 * extent and in turn walk the backrefs of those, too. Naturally this is a 1429 * recursive process, but here it is implemented in an iterative fashion: We 1430 * find all referencing extents for the extent in question and put them on a 1431 * list. In turn, we find all referencing extents for those, further appending 1432 * to the list. The way we iterate the list allows adding more elements after 1433 * the current while iterating. The process stops when we reach the end of the 1434 * list. Found roots are added to the roots list. 1435 * 1436 * returns 0 on success, < 0 on error. 1437 */ 1438 static int btrfs_find_all_roots_safe(struct btrfs_trans_handle *trans, 1439 struct btrfs_fs_info *fs_info, u64 bytenr, 1440 u64 time_seq, struct ulist **roots, 1441 bool ignore_offset) 1442 { 1443 struct ulist *tmp; 1444 struct ulist_node *node = NULL; 1445 struct ulist_iterator uiter; 1446 int ret; 1447 1448 tmp = ulist_alloc(GFP_NOFS); 1449 if (!tmp) 1450 return -ENOMEM; 1451 *roots = ulist_alloc(GFP_NOFS); 1452 if (!*roots) { 1453 ulist_free(tmp); 1454 return -ENOMEM; 1455 } 1456 1457 ULIST_ITER_INIT(&uiter); 1458 while (1) { 1459 ret = find_parent_nodes(trans, fs_info, bytenr, time_seq, 1460 tmp, *roots, NULL, NULL, ignore_offset); 1461 if (ret < 0 && ret != -ENOENT) { 1462 ulist_free(tmp); 1463 ulist_free(*roots); 1464 return ret; 1465 } 1466 node = ulist_next(tmp, &uiter); 1467 if (!node) 1468 break; 1469 bytenr = node->val; 1470 cond_resched(); 1471 } 1472 1473 ulist_free(tmp); 1474 return 0; 1475 } 1476 1477 int btrfs_find_all_roots(struct btrfs_trans_handle *trans, 1478 struct btrfs_fs_info *fs_info, u64 bytenr, 1479 u64 time_seq, struct ulist **roots, 1480 bool ignore_offset) 1481 { 1482 int ret; 1483 1484 if (!trans) 1485 down_read(&fs_info->commit_root_sem); 1486 ret = btrfs_find_all_roots_safe(trans, fs_info, bytenr, 1487 time_seq, roots, ignore_offset); 1488 if (!trans) 1489 up_read(&fs_info->commit_root_sem); 1490 return ret; 1491 } 1492 1493 /** 1494 * btrfs_check_shared - tell us whether an extent is shared 1495 * 1496 * btrfs_check_shared uses the backref walking code but will short 1497 * circuit as soon as it finds a root or inode that doesn't match the 1498 * one passed in. This provides a significant performance benefit for 1499 * callers (such as fiemap) which want to know whether the extent is 1500 * shared but do not need a ref count. 1501 * 1502 * This attempts to attach to the running transaction in order to account for 1503 * delayed refs, but continues on even when no running transaction exists. 1504 * 1505 * Return: 0 if extent is not shared, 1 if it is shared, < 0 on error. 1506 */ 1507 int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr, 1508 struct ulist *roots, struct ulist *tmp) 1509 { 1510 struct btrfs_fs_info *fs_info = root->fs_info; 1511 struct btrfs_trans_handle *trans; 1512 struct ulist_iterator uiter; 1513 struct ulist_node *node; 1514 struct seq_list elem = SEQ_LIST_INIT(elem); 1515 int ret = 0; 1516 struct share_check shared = { 1517 .root_objectid = root->root_key.objectid, 1518 .inum = inum, 1519 .share_count = 0, 1520 }; 1521 1522 ulist_init(roots); 1523 ulist_init(tmp); 1524 1525 trans = btrfs_join_transaction_nostart(root); 1526 if (IS_ERR(trans)) { 1527 if (PTR_ERR(trans) != -ENOENT && PTR_ERR(trans) != -EROFS) { 1528 ret = PTR_ERR(trans); 1529 goto out; 1530 } 1531 trans = NULL; 1532 down_read(&fs_info->commit_root_sem); 1533 } else { 1534 btrfs_get_tree_mod_seq(fs_info, &elem); 1535 } 1536 1537 ULIST_ITER_INIT(&uiter); 1538 while (1) { 1539 ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp, 1540 roots, NULL, &shared, false); 1541 if (ret == BACKREF_FOUND_SHARED) { 1542 /* this is the only condition under which we return 1 */ 1543 ret = 1; 1544 break; 1545 } 1546 if (ret < 0 && ret != -ENOENT) 1547 break; 1548 ret = 0; 1549 node = ulist_next(tmp, &uiter); 1550 if (!node) 1551 break; 1552 bytenr = node->val; 1553 shared.share_count = 0; 1554 cond_resched(); 1555 } 1556 1557 if (trans) { 1558 btrfs_put_tree_mod_seq(fs_info, &elem); 1559 btrfs_end_transaction(trans); 1560 } else { 1561 up_read(&fs_info->commit_root_sem); 1562 } 1563 out: 1564 ulist_release(roots); 1565 ulist_release(tmp); 1566 return ret; 1567 } 1568 1569 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid, 1570 u64 start_off, struct btrfs_path *path, 1571 struct btrfs_inode_extref **ret_extref, 1572 u64 *found_off) 1573 { 1574 int ret, slot; 1575 struct btrfs_key key; 1576 struct btrfs_key found_key; 1577 struct btrfs_inode_extref *extref; 1578 const struct extent_buffer *leaf; 1579 unsigned long ptr; 1580 1581 key.objectid = inode_objectid; 1582 key.type = BTRFS_INODE_EXTREF_KEY; 1583 key.offset = start_off; 1584 1585 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 1586 if (ret < 0) 1587 return ret; 1588 1589 while (1) { 1590 leaf = path->nodes[0]; 1591 slot = path->slots[0]; 1592 if (slot >= btrfs_header_nritems(leaf)) { 1593 /* 1594 * If the item at offset is not found, 1595 * btrfs_search_slot will point us to the slot 1596 * where it should be inserted. In our case 1597 * that will be the slot directly before the 1598 * next INODE_REF_KEY_V2 item. In the case 1599 * that we're pointing to the last slot in a 1600 * leaf, we must move one leaf over. 1601 */ 1602 ret = btrfs_next_leaf(root, path); 1603 if (ret) { 1604 if (ret >= 1) 1605 ret = -ENOENT; 1606 break; 1607 } 1608 continue; 1609 } 1610 1611 btrfs_item_key_to_cpu(leaf, &found_key, slot); 1612 1613 /* 1614 * Check that we're still looking at an extended ref key for 1615 * this particular objectid. If we have different 1616 * objectid or type then there are no more to be found 1617 * in the tree and we can exit. 1618 */ 1619 ret = -ENOENT; 1620 if (found_key.objectid != inode_objectid) 1621 break; 1622 if (found_key.type != BTRFS_INODE_EXTREF_KEY) 1623 break; 1624 1625 ret = 0; 1626 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); 1627 extref = (struct btrfs_inode_extref *)ptr; 1628 *ret_extref = extref; 1629 if (found_off) 1630 *found_off = found_key.offset; 1631 break; 1632 } 1633 1634 return ret; 1635 } 1636 1637 /* 1638 * this iterates to turn a name (from iref/extref) into a full filesystem path. 1639 * Elements of the path are separated by '/' and the path is guaranteed to be 1640 * 0-terminated. the path is only given within the current file system. 1641 * Therefore, it never starts with a '/'. the caller is responsible to provide 1642 * "size" bytes in "dest". the dest buffer will be filled backwards. finally, 1643 * the start point of the resulting string is returned. this pointer is within 1644 * dest, normally. 1645 * in case the path buffer would overflow, the pointer is decremented further 1646 * as if output was written to the buffer, though no more output is actually 1647 * generated. that way, the caller can determine how much space would be 1648 * required for the path to fit into the buffer. in that case, the returned 1649 * value will be smaller than dest. callers must check this! 1650 */ 1651 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path, 1652 u32 name_len, unsigned long name_off, 1653 struct extent_buffer *eb_in, u64 parent, 1654 char *dest, u32 size) 1655 { 1656 int slot; 1657 u64 next_inum; 1658 int ret; 1659 s64 bytes_left = ((s64)size) - 1; 1660 struct extent_buffer *eb = eb_in; 1661 struct btrfs_key found_key; 1662 int leave_spinning = path->leave_spinning; 1663 struct btrfs_inode_ref *iref; 1664 1665 if (bytes_left >= 0) 1666 dest[bytes_left] = '\0'; 1667 1668 path->leave_spinning = 1; 1669 while (1) { 1670 bytes_left -= name_len; 1671 if (bytes_left >= 0) 1672 read_extent_buffer(eb, dest + bytes_left, 1673 name_off, name_len); 1674 if (eb != eb_in) { 1675 if (!path->skip_locking) 1676 btrfs_tree_read_unlock_blocking(eb); 1677 free_extent_buffer(eb); 1678 } 1679 ret = btrfs_find_item(fs_root, path, parent, 0, 1680 BTRFS_INODE_REF_KEY, &found_key); 1681 if (ret > 0) 1682 ret = -ENOENT; 1683 if (ret) 1684 break; 1685 1686 next_inum = found_key.offset; 1687 1688 /* regular exit ahead */ 1689 if (parent == next_inum) 1690 break; 1691 1692 slot = path->slots[0]; 1693 eb = path->nodes[0]; 1694 /* make sure we can use eb after releasing the path */ 1695 if (eb != eb_in) { 1696 if (!path->skip_locking) 1697 btrfs_set_lock_blocking_read(eb); 1698 path->nodes[0] = NULL; 1699 path->locks[0] = 0; 1700 } 1701 btrfs_release_path(path); 1702 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); 1703 1704 name_len = btrfs_inode_ref_name_len(eb, iref); 1705 name_off = (unsigned long)(iref + 1); 1706 1707 parent = next_inum; 1708 --bytes_left; 1709 if (bytes_left >= 0) 1710 dest[bytes_left] = '/'; 1711 } 1712 1713 btrfs_release_path(path); 1714 path->leave_spinning = leave_spinning; 1715 1716 if (ret) 1717 return ERR_PTR(ret); 1718 1719 return dest + bytes_left; 1720 } 1721 1722 /* 1723 * this makes the path point to (logical EXTENT_ITEM *) 1724 * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for 1725 * tree blocks and <0 on error. 1726 */ 1727 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical, 1728 struct btrfs_path *path, struct btrfs_key *found_key, 1729 u64 *flags_ret) 1730 { 1731 int ret; 1732 u64 flags; 1733 u64 size = 0; 1734 u32 item_size; 1735 const struct extent_buffer *eb; 1736 struct btrfs_extent_item *ei; 1737 struct btrfs_key key; 1738 1739 if (btrfs_fs_incompat(fs_info, SKINNY_METADATA)) 1740 key.type = BTRFS_METADATA_ITEM_KEY; 1741 else 1742 key.type = BTRFS_EXTENT_ITEM_KEY; 1743 key.objectid = logical; 1744 key.offset = (u64)-1; 1745 1746 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0); 1747 if (ret < 0) 1748 return ret; 1749 1750 ret = btrfs_previous_extent_item(fs_info->extent_root, path, 0); 1751 if (ret) { 1752 if (ret > 0) 1753 ret = -ENOENT; 1754 return ret; 1755 } 1756 btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]); 1757 if (found_key->type == BTRFS_METADATA_ITEM_KEY) 1758 size = fs_info->nodesize; 1759 else if (found_key->type == BTRFS_EXTENT_ITEM_KEY) 1760 size = found_key->offset; 1761 1762 if (found_key->objectid > logical || 1763 found_key->objectid + size <= logical) { 1764 btrfs_debug(fs_info, 1765 "logical %llu is not within any extent", logical); 1766 return -ENOENT; 1767 } 1768 1769 eb = path->nodes[0]; 1770 item_size = btrfs_item_size_nr(eb, path->slots[0]); 1771 BUG_ON(item_size < sizeof(*ei)); 1772 1773 ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item); 1774 flags = btrfs_extent_flags(eb, ei); 1775 1776 btrfs_debug(fs_info, 1777 "logical %llu is at position %llu within the extent (%llu EXTENT_ITEM %llu) flags %#llx size %u", 1778 logical, logical - found_key->objectid, found_key->objectid, 1779 found_key->offset, flags, item_size); 1780 1781 WARN_ON(!flags_ret); 1782 if (flags_ret) { 1783 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) 1784 *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK; 1785 else if (flags & BTRFS_EXTENT_FLAG_DATA) 1786 *flags_ret = BTRFS_EXTENT_FLAG_DATA; 1787 else 1788 BUG(); 1789 return 0; 1790 } 1791 1792 return -EIO; 1793 } 1794 1795 /* 1796 * helper function to iterate extent inline refs. ptr must point to a 0 value 1797 * for the first call and may be modified. it is used to track state. 1798 * if more refs exist, 0 is returned and the next call to 1799 * get_extent_inline_ref must pass the modified ptr parameter to get the 1800 * next ref. after the last ref was processed, 1 is returned. 1801 * returns <0 on error 1802 */ 1803 static int get_extent_inline_ref(unsigned long *ptr, 1804 const struct extent_buffer *eb, 1805 const struct btrfs_key *key, 1806 const struct btrfs_extent_item *ei, 1807 u32 item_size, 1808 struct btrfs_extent_inline_ref **out_eiref, 1809 int *out_type) 1810 { 1811 unsigned long end; 1812 u64 flags; 1813 struct btrfs_tree_block_info *info; 1814 1815 if (!*ptr) { 1816 /* first call */ 1817 flags = btrfs_extent_flags(eb, ei); 1818 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) { 1819 if (key->type == BTRFS_METADATA_ITEM_KEY) { 1820 /* a skinny metadata extent */ 1821 *out_eiref = 1822 (struct btrfs_extent_inline_ref *)(ei + 1); 1823 } else { 1824 WARN_ON(key->type != BTRFS_EXTENT_ITEM_KEY); 1825 info = (struct btrfs_tree_block_info *)(ei + 1); 1826 *out_eiref = 1827 (struct btrfs_extent_inline_ref *)(info + 1); 1828 } 1829 } else { 1830 *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1); 1831 } 1832 *ptr = (unsigned long)*out_eiref; 1833 if ((unsigned long)(*ptr) >= (unsigned long)ei + item_size) 1834 return -ENOENT; 1835 } 1836 1837 end = (unsigned long)ei + item_size; 1838 *out_eiref = (struct btrfs_extent_inline_ref *)(*ptr); 1839 *out_type = btrfs_get_extent_inline_ref_type(eb, *out_eiref, 1840 BTRFS_REF_TYPE_ANY); 1841 if (*out_type == BTRFS_REF_TYPE_INVALID) 1842 return -EUCLEAN; 1843 1844 *ptr += btrfs_extent_inline_ref_size(*out_type); 1845 WARN_ON(*ptr > end); 1846 if (*ptr == end) 1847 return 1; /* last */ 1848 1849 return 0; 1850 } 1851 1852 /* 1853 * reads the tree block backref for an extent. tree level and root are returned 1854 * through out_level and out_root. ptr must point to a 0 value for the first 1855 * call and may be modified (see get_extent_inline_ref comment). 1856 * returns 0 if data was provided, 1 if there was no more data to provide or 1857 * <0 on error. 1858 */ 1859 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb, 1860 struct btrfs_key *key, struct btrfs_extent_item *ei, 1861 u32 item_size, u64 *out_root, u8 *out_level) 1862 { 1863 int ret; 1864 int type; 1865 struct btrfs_extent_inline_ref *eiref; 1866 1867 if (*ptr == (unsigned long)-1) 1868 return 1; 1869 1870 while (1) { 1871 ret = get_extent_inline_ref(ptr, eb, key, ei, item_size, 1872 &eiref, &type); 1873 if (ret < 0) 1874 return ret; 1875 1876 if (type == BTRFS_TREE_BLOCK_REF_KEY || 1877 type == BTRFS_SHARED_BLOCK_REF_KEY) 1878 break; 1879 1880 if (ret == 1) 1881 return 1; 1882 } 1883 1884 /* we can treat both ref types equally here */ 1885 *out_root = btrfs_extent_inline_ref_offset(eb, eiref); 1886 1887 if (key->type == BTRFS_EXTENT_ITEM_KEY) { 1888 struct btrfs_tree_block_info *info; 1889 1890 info = (struct btrfs_tree_block_info *)(ei + 1); 1891 *out_level = btrfs_tree_block_level(eb, info); 1892 } else { 1893 ASSERT(key->type == BTRFS_METADATA_ITEM_KEY); 1894 *out_level = (u8)key->offset; 1895 } 1896 1897 if (ret == 1) 1898 *ptr = (unsigned long)-1; 1899 1900 return 0; 1901 } 1902 1903 static int iterate_leaf_refs(struct btrfs_fs_info *fs_info, 1904 struct extent_inode_elem *inode_list, 1905 u64 root, u64 extent_item_objectid, 1906 iterate_extent_inodes_t *iterate, void *ctx) 1907 { 1908 struct extent_inode_elem *eie; 1909 int ret = 0; 1910 1911 for (eie = inode_list; eie; eie = eie->next) { 1912 btrfs_debug(fs_info, 1913 "ref for %llu resolved, key (%llu EXTEND_DATA %llu), root %llu", 1914 extent_item_objectid, eie->inum, 1915 eie->offset, root); 1916 ret = iterate(eie->inum, eie->offset, root, ctx); 1917 if (ret) { 1918 btrfs_debug(fs_info, 1919 "stopping iteration for %llu due to ret=%d", 1920 extent_item_objectid, ret); 1921 break; 1922 } 1923 } 1924 1925 return ret; 1926 } 1927 1928 /* 1929 * calls iterate() for every inode that references the extent identified by 1930 * the given parameters. 1931 * when the iterator function returns a non-zero value, iteration stops. 1932 */ 1933 int iterate_extent_inodes(struct btrfs_fs_info *fs_info, 1934 u64 extent_item_objectid, u64 extent_item_pos, 1935 int search_commit_root, 1936 iterate_extent_inodes_t *iterate, void *ctx, 1937 bool ignore_offset) 1938 { 1939 int ret; 1940 struct btrfs_trans_handle *trans = NULL; 1941 struct ulist *refs = NULL; 1942 struct ulist *roots = NULL; 1943 struct ulist_node *ref_node = NULL; 1944 struct ulist_node *root_node = NULL; 1945 struct seq_list tree_mod_seq_elem = SEQ_LIST_INIT(tree_mod_seq_elem); 1946 struct ulist_iterator ref_uiter; 1947 struct ulist_iterator root_uiter; 1948 1949 btrfs_debug(fs_info, "resolving all inodes for extent %llu", 1950 extent_item_objectid); 1951 1952 if (!search_commit_root) { 1953 trans = btrfs_attach_transaction(fs_info->extent_root); 1954 if (IS_ERR(trans)) { 1955 if (PTR_ERR(trans) != -ENOENT && 1956 PTR_ERR(trans) != -EROFS) 1957 return PTR_ERR(trans); 1958 trans = NULL; 1959 } 1960 } 1961 1962 if (trans) 1963 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem); 1964 else 1965 down_read(&fs_info->commit_root_sem); 1966 1967 ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid, 1968 tree_mod_seq_elem.seq, &refs, 1969 &extent_item_pos, ignore_offset); 1970 if (ret) 1971 goto out; 1972 1973 ULIST_ITER_INIT(&ref_uiter); 1974 while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) { 1975 ret = btrfs_find_all_roots_safe(trans, fs_info, ref_node->val, 1976 tree_mod_seq_elem.seq, &roots, 1977 ignore_offset); 1978 if (ret) 1979 break; 1980 ULIST_ITER_INIT(&root_uiter); 1981 while (!ret && (root_node = ulist_next(roots, &root_uiter))) { 1982 btrfs_debug(fs_info, 1983 "root %llu references leaf %llu, data list %#llx", 1984 root_node->val, ref_node->val, 1985 ref_node->aux); 1986 ret = iterate_leaf_refs(fs_info, 1987 (struct extent_inode_elem *) 1988 (uintptr_t)ref_node->aux, 1989 root_node->val, 1990 extent_item_objectid, 1991 iterate, ctx); 1992 } 1993 ulist_free(roots); 1994 } 1995 1996 free_leaf_list(refs); 1997 out: 1998 if (trans) { 1999 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem); 2000 btrfs_end_transaction(trans); 2001 } else { 2002 up_read(&fs_info->commit_root_sem); 2003 } 2004 2005 return ret; 2006 } 2007 2008 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info, 2009 struct btrfs_path *path, 2010 iterate_extent_inodes_t *iterate, void *ctx, 2011 bool ignore_offset) 2012 { 2013 int ret; 2014 u64 extent_item_pos; 2015 u64 flags = 0; 2016 struct btrfs_key found_key; 2017 int search_commit_root = path->search_commit_root; 2018 2019 ret = extent_from_logical(fs_info, logical, path, &found_key, &flags); 2020 btrfs_release_path(path); 2021 if (ret < 0) 2022 return ret; 2023 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) 2024 return -EINVAL; 2025 2026 extent_item_pos = logical - found_key.objectid; 2027 ret = iterate_extent_inodes(fs_info, found_key.objectid, 2028 extent_item_pos, search_commit_root, 2029 iterate, ctx, ignore_offset); 2030 2031 return ret; 2032 } 2033 2034 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off, 2035 struct extent_buffer *eb, void *ctx); 2036 2037 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root, 2038 struct btrfs_path *path, 2039 iterate_irefs_t *iterate, void *ctx) 2040 { 2041 int ret = 0; 2042 int slot; 2043 u32 cur; 2044 u32 len; 2045 u32 name_len; 2046 u64 parent = 0; 2047 int found = 0; 2048 struct extent_buffer *eb; 2049 struct btrfs_item *item; 2050 struct btrfs_inode_ref *iref; 2051 struct btrfs_key found_key; 2052 2053 while (!ret) { 2054 ret = btrfs_find_item(fs_root, path, inum, 2055 parent ? parent + 1 : 0, BTRFS_INODE_REF_KEY, 2056 &found_key); 2057 2058 if (ret < 0) 2059 break; 2060 if (ret) { 2061 ret = found ? 0 : -ENOENT; 2062 break; 2063 } 2064 ++found; 2065 2066 parent = found_key.offset; 2067 slot = path->slots[0]; 2068 eb = btrfs_clone_extent_buffer(path->nodes[0]); 2069 if (!eb) { 2070 ret = -ENOMEM; 2071 break; 2072 } 2073 btrfs_release_path(path); 2074 2075 item = btrfs_item_nr(slot); 2076 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref); 2077 2078 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) { 2079 name_len = btrfs_inode_ref_name_len(eb, iref); 2080 /* path must be released before calling iterate()! */ 2081 btrfs_debug(fs_root->fs_info, 2082 "following ref at offset %u for inode %llu in tree %llu", 2083 cur, found_key.objectid, 2084 fs_root->root_key.objectid); 2085 ret = iterate(parent, name_len, 2086 (unsigned long)(iref + 1), eb, ctx); 2087 if (ret) 2088 break; 2089 len = sizeof(*iref) + name_len; 2090 iref = (struct btrfs_inode_ref *)((char *)iref + len); 2091 } 2092 free_extent_buffer(eb); 2093 } 2094 2095 btrfs_release_path(path); 2096 2097 return ret; 2098 } 2099 2100 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root, 2101 struct btrfs_path *path, 2102 iterate_irefs_t *iterate, void *ctx) 2103 { 2104 int ret; 2105 int slot; 2106 u64 offset = 0; 2107 u64 parent; 2108 int found = 0; 2109 struct extent_buffer *eb; 2110 struct btrfs_inode_extref *extref; 2111 u32 item_size; 2112 u32 cur_offset; 2113 unsigned long ptr; 2114 2115 while (1) { 2116 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref, 2117 &offset); 2118 if (ret < 0) 2119 break; 2120 if (ret) { 2121 ret = found ? 0 : -ENOENT; 2122 break; 2123 } 2124 ++found; 2125 2126 slot = path->slots[0]; 2127 eb = btrfs_clone_extent_buffer(path->nodes[0]); 2128 if (!eb) { 2129 ret = -ENOMEM; 2130 break; 2131 } 2132 btrfs_release_path(path); 2133 2134 item_size = btrfs_item_size_nr(eb, slot); 2135 ptr = btrfs_item_ptr_offset(eb, slot); 2136 cur_offset = 0; 2137 2138 while (cur_offset < item_size) { 2139 u32 name_len; 2140 2141 extref = (struct btrfs_inode_extref *)(ptr + cur_offset); 2142 parent = btrfs_inode_extref_parent(eb, extref); 2143 name_len = btrfs_inode_extref_name_len(eb, extref); 2144 ret = iterate(parent, name_len, 2145 (unsigned long)&extref->name, eb, ctx); 2146 if (ret) 2147 break; 2148 2149 cur_offset += btrfs_inode_extref_name_len(eb, extref); 2150 cur_offset += sizeof(*extref); 2151 } 2152 free_extent_buffer(eb); 2153 2154 offset++; 2155 } 2156 2157 btrfs_release_path(path); 2158 2159 return ret; 2160 } 2161 2162 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root, 2163 struct btrfs_path *path, iterate_irefs_t *iterate, 2164 void *ctx) 2165 { 2166 int ret; 2167 int found_refs = 0; 2168 2169 ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx); 2170 if (!ret) 2171 ++found_refs; 2172 else if (ret != -ENOENT) 2173 return ret; 2174 2175 ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx); 2176 if (ret == -ENOENT && found_refs) 2177 return 0; 2178 2179 return ret; 2180 } 2181 2182 /* 2183 * returns 0 if the path could be dumped (probably truncated) 2184 * returns <0 in case of an error 2185 */ 2186 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off, 2187 struct extent_buffer *eb, void *ctx) 2188 { 2189 struct inode_fs_paths *ipath = ctx; 2190 char *fspath; 2191 char *fspath_min; 2192 int i = ipath->fspath->elem_cnt; 2193 const int s_ptr = sizeof(char *); 2194 u32 bytes_left; 2195 2196 bytes_left = ipath->fspath->bytes_left > s_ptr ? 2197 ipath->fspath->bytes_left - s_ptr : 0; 2198 2199 fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr; 2200 fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len, 2201 name_off, eb, inum, fspath_min, bytes_left); 2202 if (IS_ERR(fspath)) 2203 return PTR_ERR(fspath); 2204 2205 if (fspath > fspath_min) { 2206 ipath->fspath->val[i] = (u64)(unsigned long)fspath; 2207 ++ipath->fspath->elem_cnt; 2208 ipath->fspath->bytes_left = fspath - fspath_min; 2209 } else { 2210 ++ipath->fspath->elem_missed; 2211 ipath->fspath->bytes_missing += fspath_min - fspath; 2212 ipath->fspath->bytes_left = 0; 2213 } 2214 2215 return 0; 2216 } 2217 2218 /* 2219 * this dumps all file system paths to the inode into the ipath struct, provided 2220 * is has been created large enough. each path is zero-terminated and accessed 2221 * from ipath->fspath->val[i]. 2222 * when it returns, there are ipath->fspath->elem_cnt number of paths available 2223 * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the 2224 * number of missed paths is recorded in ipath->fspath->elem_missed, otherwise, 2225 * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would 2226 * have been needed to return all paths. 2227 */ 2228 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath) 2229 { 2230 return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path, 2231 inode_to_path, ipath); 2232 } 2233 2234 struct btrfs_data_container *init_data_container(u32 total_bytes) 2235 { 2236 struct btrfs_data_container *data; 2237 size_t alloc_bytes; 2238 2239 alloc_bytes = max_t(size_t, total_bytes, sizeof(*data)); 2240 data = kvmalloc(alloc_bytes, GFP_KERNEL); 2241 if (!data) 2242 return ERR_PTR(-ENOMEM); 2243 2244 if (total_bytes >= sizeof(*data)) { 2245 data->bytes_left = total_bytes - sizeof(*data); 2246 data->bytes_missing = 0; 2247 } else { 2248 data->bytes_missing = sizeof(*data) - total_bytes; 2249 data->bytes_left = 0; 2250 } 2251 2252 data->elem_cnt = 0; 2253 data->elem_missed = 0; 2254 2255 return data; 2256 } 2257 2258 /* 2259 * allocates space to return multiple file system paths for an inode. 2260 * total_bytes to allocate are passed, note that space usable for actual path 2261 * information will be total_bytes - sizeof(struct inode_fs_paths). 2262 * the returned pointer must be freed with free_ipath() in the end. 2263 */ 2264 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root, 2265 struct btrfs_path *path) 2266 { 2267 struct inode_fs_paths *ifp; 2268 struct btrfs_data_container *fspath; 2269 2270 fspath = init_data_container(total_bytes); 2271 if (IS_ERR(fspath)) 2272 return ERR_CAST(fspath); 2273 2274 ifp = kmalloc(sizeof(*ifp), GFP_KERNEL); 2275 if (!ifp) { 2276 kvfree(fspath); 2277 return ERR_PTR(-ENOMEM); 2278 } 2279 2280 ifp->btrfs_path = path; 2281 ifp->fspath = fspath; 2282 ifp->fs_root = fs_root; 2283 2284 return ifp; 2285 } 2286 2287 void free_ipath(struct inode_fs_paths *ipath) 2288 { 2289 if (!ipath) 2290 return; 2291 kvfree(ipath->fspath); 2292 kfree(ipath); 2293 } 2294 2295 struct btrfs_backref_iter *btrfs_backref_iter_alloc( 2296 struct btrfs_fs_info *fs_info, gfp_t gfp_flag) 2297 { 2298 struct btrfs_backref_iter *ret; 2299 2300 ret = kzalloc(sizeof(*ret), gfp_flag); 2301 if (!ret) 2302 return NULL; 2303 2304 ret->path = btrfs_alloc_path(); 2305 if (!ret) { 2306 kfree(ret); 2307 return NULL; 2308 } 2309 2310 /* Current backref iterator only supports iteration in commit root */ 2311 ret->path->search_commit_root = 1; 2312 ret->path->skip_locking = 1; 2313 ret->fs_info = fs_info; 2314 2315 return ret; 2316 } 2317 2318 int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr) 2319 { 2320 struct btrfs_fs_info *fs_info = iter->fs_info; 2321 struct btrfs_path *path = iter->path; 2322 struct btrfs_extent_item *ei; 2323 struct btrfs_key key; 2324 int ret; 2325 2326 key.objectid = bytenr; 2327 key.type = BTRFS_METADATA_ITEM_KEY; 2328 key.offset = (u64)-1; 2329 iter->bytenr = bytenr; 2330 2331 ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0); 2332 if (ret < 0) 2333 return ret; 2334 if (ret == 0) { 2335 ret = -EUCLEAN; 2336 goto release; 2337 } 2338 if (path->slots[0] == 0) { 2339 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG)); 2340 ret = -EUCLEAN; 2341 goto release; 2342 } 2343 path->slots[0]--; 2344 2345 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); 2346 if ((key.type != BTRFS_EXTENT_ITEM_KEY && 2347 key.type != BTRFS_METADATA_ITEM_KEY) || key.objectid != bytenr) { 2348 ret = -ENOENT; 2349 goto release; 2350 } 2351 memcpy(&iter->cur_key, &key, sizeof(key)); 2352 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], 2353 path->slots[0]); 2354 iter->end_ptr = (u32)(iter->item_ptr + 2355 btrfs_item_size_nr(path->nodes[0], path->slots[0])); 2356 ei = btrfs_item_ptr(path->nodes[0], path->slots[0], 2357 struct btrfs_extent_item); 2358 2359 /* 2360 * Only support iteration on tree backref yet. 2361 * 2362 * This is an extra precaution for non skinny-metadata, where 2363 * EXTENT_ITEM is also used for tree blocks, that we can only use 2364 * extent flags to determine if it's a tree block. 2365 */ 2366 if (btrfs_extent_flags(path->nodes[0], ei) & BTRFS_EXTENT_FLAG_DATA) { 2367 ret = -ENOTSUPP; 2368 goto release; 2369 } 2370 iter->cur_ptr = (u32)(iter->item_ptr + sizeof(*ei)); 2371 2372 /* If there is no inline backref, go search for keyed backref */ 2373 if (iter->cur_ptr >= iter->end_ptr) { 2374 ret = btrfs_next_item(fs_info->extent_root, path); 2375 2376 /* No inline nor keyed ref */ 2377 if (ret > 0) { 2378 ret = -ENOENT; 2379 goto release; 2380 } 2381 if (ret < 0) 2382 goto release; 2383 2384 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, 2385 path->slots[0]); 2386 if (iter->cur_key.objectid != bytenr || 2387 (iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY && 2388 iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY)) { 2389 ret = -ENOENT; 2390 goto release; 2391 } 2392 iter->cur_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], 2393 path->slots[0]); 2394 iter->item_ptr = iter->cur_ptr; 2395 iter->end_ptr = (u32)(iter->item_ptr + btrfs_item_size_nr( 2396 path->nodes[0], path->slots[0])); 2397 } 2398 2399 return 0; 2400 release: 2401 btrfs_backref_iter_release(iter); 2402 return ret; 2403 } 2404 2405 /* 2406 * Go to the next backref item of current bytenr, can be either inlined or 2407 * keyed. 2408 * 2409 * Caller needs to check whether it's inline ref or not by iter->cur_key. 2410 * 2411 * Return 0 if we get next backref without problem. 2412 * Return >0 if there is no extra backref for this bytenr. 2413 * Return <0 if there is something wrong happened. 2414 */ 2415 int btrfs_backref_iter_next(struct btrfs_backref_iter *iter) 2416 { 2417 struct extent_buffer *eb = btrfs_backref_get_eb(iter); 2418 struct btrfs_path *path = iter->path; 2419 struct btrfs_extent_inline_ref *iref; 2420 int ret; 2421 u32 size; 2422 2423 if (btrfs_backref_iter_is_inline_ref(iter)) { 2424 /* We're still inside the inline refs */ 2425 ASSERT(iter->cur_ptr < iter->end_ptr); 2426 2427 if (btrfs_backref_has_tree_block_info(iter)) { 2428 /* First tree block info */ 2429 size = sizeof(struct btrfs_tree_block_info); 2430 } else { 2431 /* Use inline ref type to determine the size */ 2432 int type; 2433 2434 iref = (struct btrfs_extent_inline_ref *) 2435 ((unsigned long)iter->cur_ptr); 2436 type = btrfs_extent_inline_ref_type(eb, iref); 2437 2438 size = btrfs_extent_inline_ref_size(type); 2439 } 2440 iter->cur_ptr += size; 2441 if (iter->cur_ptr < iter->end_ptr) 2442 return 0; 2443 2444 /* All inline items iterated, fall through */ 2445 } 2446 2447 /* We're at keyed items, there is no inline item, go to the next one */ 2448 ret = btrfs_next_item(iter->fs_info->extent_root, iter->path); 2449 if (ret) 2450 return ret; 2451 2452 btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]); 2453 if (iter->cur_key.objectid != iter->bytenr || 2454 (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY && 2455 iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY)) 2456 return 1; 2457 iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], 2458 path->slots[0]); 2459 iter->cur_ptr = iter->item_ptr; 2460 iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size_nr(path->nodes[0], 2461 path->slots[0]); 2462 return 0; 2463 } 2464 2465 void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info, 2466 struct btrfs_backref_cache *cache, int is_reloc) 2467 { 2468 int i; 2469 2470 cache->rb_root = RB_ROOT; 2471 for (i = 0; i < BTRFS_MAX_LEVEL; i++) 2472 INIT_LIST_HEAD(&cache->pending[i]); 2473 INIT_LIST_HEAD(&cache->changed); 2474 INIT_LIST_HEAD(&cache->detached); 2475 INIT_LIST_HEAD(&cache->leaves); 2476 INIT_LIST_HEAD(&cache->pending_edge); 2477 INIT_LIST_HEAD(&cache->useless_node); 2478 cache->fs_info = fs_info; 2479 cache->is_reloc = is_reloc; 2480 } 2481 2482 struct btrfs_backref_node *btrfs_backref_alloc_node( 2483 struct btrfs_backref_cache *cache, u64 bytenr, int level) 2484 { 2485 struct btrfs_backref_node *node; 2486 2487 ASSERT(level >= 0 && level < BTRFS_MAX_LEVEL); 2488 node = kzalloc(sizeof(*node), GFP_NOFS); 2489 if (!node) 2490 return node; 2491 2492 INIT_LIST_HEAD(&node->list); 2493 INIT_LIST_HEAD(&node->upper); 2494 INIT_LIST_HEAD(&node->lower); 2495 RB_CLEAR_NODE(&node->rb_node); 2496 cache->nr_nodes++; 2497 node->level = level; 2498 node->bytenr = bytenr; 2499 2500 return node; 2501 } 2502 2503 struct btrfs_backref_edge *btrfs_backref_alloc_edge( 2504 struct btrfs_backref_cache *cache) 2505 { 2506 struct btrfs_backref_edge *edge; 2507 2508 edge = kzalloc(sizeof(*edge), GFP_NOFS); 2509 if (edge) 2510 cache->nr_edges++; 2511 return edge; 2512 } 2513 2514 /* 2515 * Drop the backref node from cache, also cleaning up all its 2516 * upper edges and any uncached nodes in the path. 2517 * 2518 * This cleanup happens bottom up, thus the node should either 2519 * be the lowest node in the cache or a detached node. 2520 */ 2521 void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache, 2522 struct btrfs_backref_node *node) 2523 { 2524 struct btrfs_backref_node *upper; 2525 struct btrfs_backref_edge *edge; 2526 2527 if (!node) 2528 return; 2529 2530 BUG_ON(!node->lowest && !node->detached); 2531 while (!list_empty(&node->upper)) { 2532 edge = list_entry(node->upper.next, struct btrfs_backref_edge, 2533 list[LOWER]); 2534 upper = edge->node[UPPER]; 2535 list_del(&edge->list[LOWER]); 2536 list_del(&edge->list[UPPER]); 2537 btrfs_backref_free_edge(cache, edge); 2538 2539 if (RB_EMPTY_NODE(&upper->rb_node)) { 2540 BUG_ON(!list_empty(&node->upper)); 2541 btrfs_backref_drop_node(cache, node); 2542 node = upper; 2543 node->lowest = 1; 2544 continue; 2545 } 2546 /* 2547 * Add the node to leaf node list if no other child block 2548 * cached. 2549 */ 2550 if (list_empty(&upper->lower)) { 2551 list_add_tail(&upper->lower, &cache->leaves); 2552 upper->lowest = 1; 2553 } 2554 } 2555 2556 btrfs_backref_drop_node(cache, node); 2557 } 2558 2559 /* 2560 * Release all nodes/edges from current cache 2561 */ 2562 void btrfs_backref_release_cache(struct btrfs_backref_cache *cache) 2563 { 2564 struct btrfs_backref_node *node; 2565 int i; 2566 2567 while (!list_empty(&cache->detached)) { 2568 node = list_entry(cache->detached.next, 2569 struct btrfs_backref_node, list); 2570 btrfs_backref_cleanup_node(cache, node); 2571 } 2572 2573 while (!list_empty(&cache->leaves)) { 2574 node = list_entry(cache->leaves.next, 2575 struct btrfs_backref_node, lower); 2576 btrfs_backref_cleanup_node(cache, node); 2577 } 2578 2579 cache->last_trans = 0; 2580 2581 for (i = 0; i < BTRFS_MAX_LEVEL; i++) 2582 ASSERT(list_empty(&cache->pending[i])); 2583 ASSERT(list_empty(&cache->pending_edge)); 2584 ASSERT(list_empty(&cache->useless_node)); 2585 ASSERT(list_empty(&cache->changed)); 2586 ASSERT(list_empty(&cache->detached)); 2587 ASSERT(RB_EMPTY_ROOT(&cache->rb_root)); 2588 ASSERT(!cache->nr_nodes); 2589 ASSERT(!cache->nr_edges); 2590 } 2591 2592 /* 2593 * Handle direct tree backref 2594 * 2595 * Direct tree backref means, the backref item shows its parent bytenr 2596 * directly. This is for SHARED_BLOCK_REF backref (keyed or inlined). 2597 * 2598 * @ref_key: The converted backref key. 2599 * For keyed backref, it's the item key. 2600 * For inlined backref, objectid is the bytenr, 2601 * type is btrfs_inline_ref_type, offset is 2602 * btrfs_inline_ref_offset. 2603 */ 2604 static int handle_direct_tree_backref(struct btrfs_backref_cache *cache, 2605 struct btrfs_key *ref_key, 2606 struct btrfs_backref_node *cur) 2607 { 2608 struct btrfs_backref_edge *edge; 2609 struct btrfs_backref_node *upper; 2610 struct rb_node *rb_node; 2611 2612 ASSERT(ref_key->type == BTRFS_SHARED_BLOCK_REF_KEY); 2613 2614 /* Only reloc root uses backref pointing to itself */ 2615 if (ref_key->objectid == ref_key->offset) { 2616 struct btrfs_root *root; 2617 2618 cur->is_reloc_root = 1; 2619 /* Only reloc backref cache cares about a specific root */ 2620 if (cache->is_reloc) { 2621 root = find_reloc_root(cache->fs_info, cur->bytenr); 2622 if (WARN_ON(!root)) 2623 return -ENOENT; 2624 cur->root = root; 2625 } else { 2626 /* 2627 * For generic purpose backref cache, reloc root node 2628 * is useless. 2629 */ 2630 list_add(&cur->list, &cache->useless_node); 2631 } 2632 return 0; 2633 } 2634 2635 edge = btrfs_backref_alloc_edge(cache); 2636 if (!edge) 2637 return -ENOMEM; 2638 2639 rb_node = rb_simple_search(&cache->rb_root, ref_key->offset); 2640 if (!rb_node) { 2641 /* Parent node not yet cached */ 2642 upper = btrfs_backref_alloc_node(cache, ref_key->offset, 2643 cur->level + 1); 2644 if (!upper) { 2645 btrfs_backref_free_edge(cache, edge); 2646 return -ENOMEM; 2647 } 2648 2649 /* 2650 * Backrefs for the upper level block isn't cached, add the 2651 * block to pending list 2652 */ 2653 list_add_tail(&edge->list[UPPER], &cache->pending_edge); 2654 } else { 2655 /* Parent node already cached */ 2656 upper = rb_entry(rb_node, struct btrfs_backref_node, rb_node); 2657 ASSERT(upper->checked); 2658 INIT_LIST_HEAD(&edge->list[UPPER]); 2659 } 2660 btrfs_backref_link_edge(edge, cur, upper, LINK_LOWER); 2661 return 0; 2662 } 2663 2664 /* 2665 * Handle indirect tree backref 2666 * 2667 * Indirect tree backref means, we only know which tree the node belongs to. 2668 * We still need to do a tree search to find out the parents. This is for 2669 * TREE_BLOCK_REF backref (keyed or inlined). 2670 * 2671 * @ref_key: The same as @ref_key in handle_direct_tree_backref() 2672 * @tree_key: The first key of this tree block. 2673 * @path: A clean (released) path, to avoid allocating path everytime 2674 * the function get called. 2675 */ 2676 static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache, 2677 struct btrfs_path *path, 2678 struct btrfs_key *ref_key, 2679 struct btrfs_key *tree_key, 2680 struct btrfs_backref_node *cur) 2681 { 2682 struct btrfs_fs_info *fs_info = cache->fs_info; 2683 struct btrfs_backref_node *upper; 2684 struct btrfs_backref_node *lower; 2685 struct btrfs_backref_edge *edge; 2686 struct extent_buffer *eb; 2687 struct btrfs_root *root; 2688 struct rb_node *rb_node; 2689 int level; 2690 bool need_check = true; 2691 int ret; 2692 2693 root = btrfs_get_fs_root(fs_info, ref_key->offset, false); 2694 if (IS_ERR(root)) 2695 return PTR_ERR(root); 2696 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) 2697 cur->cowonly = 1; 2698 2699 if (btrfs_root_level(&root->root_item) == cur->level) { 2700 /* Tree root */ 2701 ASSERT(btrfs_root_bytenr(&root->root_item) == cur->bytenr); 2702 /* 2703 * For reloc backref cache, we may ignore reloc root. But for 2704 * general purpose backref cache, we can't rely on 2705 * btrfs_should_ignore_reloc_root() as it may conflict with 2706 * current running relocation and lead to missing root. 2707 * 2708 * For general purpose backref cache, reloc root detection is 2709 * completely relying on direct backref (key->offset is parent 2710 * bytenr), thus only do such check for reloc cache. 2711 */ 2712 if (btrfs_should_ignore_reloc_root(root) && cache->is_reloc) { 2713 btrfs_put_root(root); 2714 list_add(&cur->list, &cache->useless_node); 2715 } else { 2716 cur->root = root; 2717 } 2718 return 0; 2719 } 2720 2721 level = cur->level + 1; 2722 2723 /* Search the tree to find parent blocks referring to the block */ 2724 path->search_commit_root = 1; 2725 path->skip_locking = 1; 2726 path->lowest_level = level; 2727 ret = btrfs_search_slot(NULL, root, tree_key, path, 0, 0); 2728 path->lowest_level = 0; 2729 if (ret < 0) { 2730 btrfs_put_root(root); 2731 return ret; 2732 } 2733 if (ret > 0 && path->slots[level] > 0) 2734 path->slots[level]--; 2735 2736 eb = path->nodes[level]; 2737 if (btrfs_node_blockptr(eb, path->slots[level]) != cur->bytenr) { 2738 btrfs_err(fs_info, 2739 "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)", 2740 cur->bytenr, level - 1, root->root_key.objectid, 2741 tree_key->objectid, tree_key->type, tree_key->offset); 2742 btrfs_put_root(root); 2743 ret = -ENOENT; 2744 goto out; 2745 } 2746 lower = cur; 2747 2748 /* Add all nodes and edges in the path */ 2749 for (; level < BTRFS_MAX_LEVEL; level++) { 2750 if (!path->nodes[level]) { 2751 ASSERT(btrfs_root_bytenr(&root->root_item) == 2752 lower->bytenr); 2753 /* Same as previous should_ignore_reloc_root() call */ 2754 if (btrfs_should_ignore_reloc_root(root) && 2755 cache->is_reloc) { 2756 btrfs_put_root(root); 2757 list_add(&lower->list, &cache->useless_node); 2758 } else { 2759 lower->root = root; 2760 } 2761 break; 2762 } 2763 2764 edge = btrfs_backref_alloc_edge(cache); 2765 if (!edge) { 2766 btrfs_put_root(root); 2767 ret = -ENOMEM; 2768 goto out; 2769 } 2770 2771 eb = path->nodes[level]; 2772 rb_node = rb_simple_search(&cache->rb_root, eb->start); 2773 if (!rb_node) { 2774 upper = btrfs_backref_alloc_node(cache, eb->start, 2775 lower->level + 1); 2776 if (!upper) { 2777 btrfs_put_root(root); 2778 btrfs_backref_free_edge(cache, edge); 2779 ret = -ENOMEM; 2780 goto out; 2781 } 2782 upper->owner = btrfs_header_owner(eb); 2783 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) 2784 upper->cowonly = 1; 2785 2786 /* 2787 * If we know the block isn't shared we can avoid 2788 * checking its backrefs. 2789 */ 2790 if (btrfs_block_can_be_shared(root, eb)) 2791 upper->checked = 0; 2792 else 2793 upper->checked = 1; 2794 2795 /* 2796 * Add the block to pending list if we need to check its 2797 * backrefs, we only do this once while walking up a 2798 * tree as we will catch anything else later on. 2799 */ 2800 if (!upper->checked && need_check) { 2801 need_check = false; 2802 list_add_tail(&edge->list[UPPER], 2803 &cache->pending_edge); 2804 } else { 2805 if (upper->checked) 2806 need_check = true; 2807 INIT_LIST_HEAD(&edge->list[UPPER]); 2808 } 2809 } else { 2810 upper = rb_entry(rb_node, struct btrfs_backref_node, 2811 rb_node); 2812 ASSERT(upper->checked); 2813 INIT_LIST_HEAD(&edge->list[UPPER]); 2814 if (!upper->owner) 2815 upper->owner = btrfs_header_owner(eb); 2816 } 2817 btrfs_backref_link_edge(edge, lower, upper, LINK_LOWER); 2818 2819 if (rb_node) { 2820 btrfs_put_root(root); 2821 break; 2822 } 2823 lower = upper; 2824 upper = NULL; 2825 } 2826 out: 2827 btrfs_release_path(path); 2828 return ret; 2829 } 2830 2831 /* 2832 * Add backref node @cur into @cache. 2833 * 2834 * NOTE: Even if the function returned 0, @cur is not yet cached as its upper 2835 * links aren't yet bi-directional. Needs to finish such links. 2836 * Use btrfs_backref_finish_upper_links() to finish such linkage. 2837 * 2838 * @path: Released path for indirect tree backref lookup 2839 * @iter: Released backref iter for extent tree search 2840 * @node_key: The first key of the tree block 2841 */ 2842 int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache, 2843 struct btrfs_path *path, 2844 struct btrfs_backref_iter *iter, 2845 struct btrfs_key *node_key, 2846 struct btrfs_backref_node *cur) 2847 { 2848 struct btrfs_fs_info *fs_info = cache->fs_info; 2849 struct btrfs_backref_edge *edge; 2850 struct btrfs_backref_node *exist; 2851 int ret; 2852 2853 ret = btrfs_backref_iter_start(iter, cur->bytenr); 2854 if (ret < 0) 2855 return ret; 2856 /* 2857 * We skip the first btrfs_tree_block_info, as we don't use the key 2858 * stored in it, but fetch it from the tree block 2859 */ 2860 if (btrfs_backref_has_tree_block_info(iter)) { 2861 ret = btrfs_backref_iter_next(iter); 2862 if (ret < 0) 2863 goto out; 2864 /* No extra backref? This means the tree block is corrupted */ 2865 if (ret > 0) { 2866 ret = -EUCLEAN; 2867 goto out; 2868 } 2869 } 2870 WARN_ON(cur->checked); 2871 if (!list_empty(&cur->upper)) { 2872 /* 2873 * The backref was added previously when processing backref of 2874 * type BTRFS_TREE_BLOCK_REF_KEY 2875 */ 2876 ASSERT(list_is_singular(&cur->upper)); 2877 edge = list_entry(cur->upper.next, struct btrfs_backref_edge, 2878 list[LOWER]); 2879 ASSERT(list_empty(&edge->list[UPPER])); 2880 exist = edge->node[UPPER]; 2881 /* 2882 * Add the upper level block to pending list if we need check 2883 * its backrefs 2884 */ 2885 if (!exist->checked) 2886 list_add_tail(&edge->list[UPPER], &cache->pending_edge); 2887 } else { 2888 exist = NULL; 2889 } 2890 2891 for (; ret == 0; ret = btrfs_backref_iter_next(iter)) { 2892 struct extent_buffer *eb; 2893 struct btrfs_key key; 2894 int type; 2895 2896 cond_resched(); 2897 eb = btrfs_backref_get_eb(iter); 2898 2899 key.objectid = iter->bytenr; 2900 if (btrfs_backref_iter_is_inline_ref(iter)) { 2901 struct btrfs_extent_inline_ref *iref; 2902 2903 /* Update key for inline backref */ 2904 iref = (struct btrfs_extent_inline_ref *) 2905 ((unsigned long)iter->cur_ptr); 2906 type = btrfs_get_extent_inline_ref_type(eb, iref, 2907 BTRFS_REF_TYPE_BLOCK); 2908 if (type == BTRFS_REF_TYPE_INVALID) { 2909 ret = -EUCLEAN; 2910 goto out; 2911 } 2912 key.type = type; 2913 key.offset = btrfs_extent_inline_ref_offset(eb, iref); 2914 } else { 2915 key.type = iter->cur_key.type; 2916 key.offset = iter->cur_key.offset; 2917 } 2918 2919 /* 2920 * Parent node found and matches current inline ref, no need to 2921 * rebuild this node for this inline ref 2922 */ 2923 if (exist && 2924 ((key.type == BTRFS_TREE_BLOCK_REF_KEY && 2925 exist->owner == key.offset) || 2926 (key.type == BTRFS_SHARED_BLOCK_REF_KEY && 2927 exist->bytenr == key.offset))) { 2928 exist = NULL; 2929 continue; 2930 } 2931 2932 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */ 2933 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) { 2934 ret = handle_direct_tree_backref(cache, &key, cur); 2935 if (ret < 0) 2936 goto out; 2937 continue; 2938 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) { 2939 ret = -EINVAL; 2940 btrfs_print_v0_err(fs_info); 2941 btrfs_handle_fs_error(fs_info, ret, NULL); 2942 goto out; 2943 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) { 2944 continue; 2945 } 2946 2947 /* 2948 * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset 2949 * means the root objectid. We need to search the tree to get 2950 * its parent bytenr. 2951 */ 2952 ret = handle_indirect_tree_backref(cache, path, &key, node_key, 2953 cur); 2954 if (ret < 0) 2955 goto out; 2956 } 2957 ret = 0; 2958 cur->checked = 1; 2959 WARN_ON(exist); 2960 out: 2961 btrfs_backref_iter_release(iter); 2962 return ret; 2963 } 2964 2965 /* 2966 * Finish the upwards linkage created by btrfs_backref_add_tree_node() 2967 */ 2968 int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache, 2969 struct btrfs_backref_node *start) 2970 { 2971 struct list_head *useless_node = &cache->useless_node; 2972 struct btrfs_backref_edge *edge; 2973 struct rb_node *rb_node; 2974 LIST_HEAD(pending_edge); 2975 2976 ASSERT(start->checked); 2977 2978 /* Insert this node to cache if it's not COW-only */ 2979 if (!start->cowonly) { 2980 rb_node = rb_simple_insert(&cache->rb_root, start->bytenr, 2981 &start->rb_node); 2982 if (rb_node) 2983 btrfs_backref_panic(cache->fs_info, start->bytenr, 2984 -EEXIST); 2985 list_add_tail(&start->lower, &cache->leaves); 2986 } 2987 2988 /* 2989 * Use breadth first search to iterate all related edges. 2990 * 2991 * The starting points are all the edges of this node 2992 */ 2993 list_for_each_entry(edge, &start->upper, list[LOWER]) 2994 list_add_tail(&edge->list[UPPER], &pending_edge); 2995 2996 while (!list_empty(&pending_edge)) { 2997 struct btrfs_backref_node *upper; 2998 struct btrfs_backref_node *lower; 2999 struct rb_node *rb_node; 3000 3001 edge = list_first_entry(&pending_edge, 3002 struct btrfs_backref_edge, list[UPPER]); 3003 list_del_init(&edge->list[UPPER]); 3004 upper = edge->node[UPPER]; 3005 lower = edge->node[LOWER]; 3006 3007 /* Parent is detached, no need to keep any edges */ 3008 if (upper->detached) { 3009 list_del(&edge->list[LOWER]); 3010 btrfs_backref_free_edge(cache, edge); 3011 3012 /* Lower node is orphan, queue for cleanup */ 3013 if (list_empty(&lower->upper)) 3014 list_add(&lower->list, useless_node); 3015 continue; 3016 } 3017 3018 /* 3019 * All new nodes added in current build_backref_tree() haven't 3020 * been linked to the cache rb tree. 3021 * So if we have upper->rb_node populated, this means a cache 3022 * hit. We only need to link the edge, as @upper and all its 3023 * parents have already been linked. 3024 */ 3025 if (!RB_EMPTY_NODE(&upper->rb_node)) { 3026 if (upper->lowest) { 3027 list_del_init(&upper->lower); 3028 upper->lowest = 0; 3029 } 3030 3031 list_add_tail(&edge->list[UPPER], &upper->lower); 3032 continue; 3033 } 3034 3035 /* Sanity check, we shouldn't have any unchecked nodes */ 3036 if (!upper->checked) { 3037 ASSERT(0); 3038 return -EUCLEAN; 3039 } 3040 3041 /* Sanity check, COW-only node has non-COW-only parent */ 3042 if (start->cowonly != upper->cowonly) { 3043 ASSERT(0); 3044 return -EUCLEAN; 3045 } 3046 3047 /* Only cache non-COW-only (subvolume trees) tree blocks */ 3048 if (!upper->cowonly) { 3049 rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr, 3050 &upper->rb_node); 3051 if (rb_node) { 3052 btrfs_backref_panic(cache->fs_info, 3053 upper->bytenr, -EEXIST); 3054 return -EUCLEAN; 3055 } 3056 } 3057 3058 list_add_tail(&edge->list[UPPER], &upper->lower); 3059 3060 /* 3061 * Also queue all the parent edges of this uncached node 3062 * to finish the upper linkage 3063 */ 3064 list_for_each_entry(edge, &upper->upper, list[LOWER]) 3065 list_add_tail(&edge->list[UPPER], &pending_edge); 3066 } 3067 return 0; 3068 } 3069 3070 void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache, 3071 struct btrfs_backref_node *node) 3072 { 3073 struct btrfs_backref_node *lower; 3074 struct btrfs_backref_node *upper; 3075 struct btrfs_backref_edge *edge; 3076 3077 while (!list_empty(&cache->useless_node)) { 3078 lower = list_first_entry(&cache->useless_node, 3079 struct btrfs_backref_node, list); 3080 list_del_init(&lower->list); 3081 } 3082 while (!list_empty(&cache->pending_edge)) { 3083 edge = list_first_entry(&cache->pending_edge, 3084 struct btrfs_backref_edge, list[UPPER]); 3085 list_del(&edge->list[UPPER]); 3086 list_del(&edge->list[LOWER]); 3087 lower = edge->node[LOWER]; 3088 upper = edge->node[UPPER]; 3089 btrfs_backref_free_edge(cache, edge); 3090 3091 /* 3092 * Lower is no longer linked to any upper backref nodes and 3093 * isn't in the cache, we can free it ourselves. 3094 */ 3095 if (list_empty(&lower->upper) && 3096 RB_EMPTY_NODE(&lower->rb_node)) 3097 list_add(&lower->list, &cache->useless_node); 3098 3099 if (!RB_EMPTY_NODE(&upper->rb_node)) 3100 continue; 3101 3102 /* Add this guy's upper edges to the list to process */ 3103 list_for_each_entry(edge, &upper->upper, list[LOWER]) 3104 list_add_tail(&edge->list[UPPER], 3105 &cache->pending_edge); 3106 if (list_empty(&upper->upper)) 3107 list_add(&upper->list, &cache->useless_node); 3108 } 3109 3110 while (!list_empty(&cache->useless_node)) { 3111 lower = list_first_entry(&cache->useless_node, 3112 struct btrfs_backref_node, list); 3113 list_del_init(&lower->list); 3114 if (lower == node) 3115 node = NULL; 3116 btrfs_backref_free_node(cache, lower); 3117 } 3118 3119 btrfs_backref_cleanup_node(cache, node); 3120 ASSERT(list_empty(&cache->useless_node) && 3121 list_empty(&cache->pending_edge)); 3122 } 3123