1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2007,2008 Oracle. All rights reserved. 4 */ 5 6 #include <linux/sched.h> 7 #include <linux/slab.h> 8 #include <linux/rbtree.h> 9 #include <linux/mm.h> 10 #include "ctree.h" 11 #include "disk-io.h" 12 #include "transaction.h" 13 #include "print-tree.h" 14 #include "locking.h" 15 #include "volumes.h" 16 17 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root 18 *root, struct btrfs_path *path, int level); 19 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root, 20 const struct btrfs_key *ins_key, struct btrfs_path *path, 21 int data_size, int extend); 22 static int push_node_left(struct btrfs_trans_handle *trans, 23 struct btrfs_fs_info *fs_info, 24 struct extent_buffer *dst, 25 struct extent_buffer *src, int empty); 26 static int balance_node_right(struct btrfs_trans_handle *trans, 27 struct btrfs_fs_info *fs_info, 28 struct extent_buffer *dst_buf, 29 struct extent_buffer *src_buf); 30 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path, 31 int level, int slot); 32 33 struct btrfs_path *btrfs_alloc_path(void) 34 { 35 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS); 36 } 37 38 /* 39 * set all locked nodes in the path to blocking locks. This should 40 * be done before scheduling 41 */ 42 noinline void btrfs_set_path_blocking(struct btrfs_path *p) 43 { 44 int i; 45 for (i = 0; i < BTRFS_MAX_LEVEL; i++) { 46 if (!p->nodes[i] || !p->locks[i]) 47 continue; 48 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]); 49 if (p->locks[i] == BTRFS_READ_LOCK) 50 p->locks[i] = BTRFS_READ_LOCK_BLOCKING; 51 else if (p->locks[i] == BTRFS_WRITE_LOCK) 52 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING; 53 } 54 } 55 56 /* this also releases the path */ 57 void btrfs_free_path(struct btrfs_path *p) 58 { 59 if (!p) 60 return; 61 btrfs_release_path(p); 62 kmem_cache_free(btrfs_path_cachep, p); 63 } 64 65 /* 66 * path release drops references on the extent buffers in the path 67 * and it drops any locks held by this path 68 * 69 * It is safe to call this on paths that no locks or extent buffers held. 70 */ 71 noinline void btrfs_release_path(struct btrfs_path *p) 72 { 73 int i; 74 75 for (i = 0; i < BTRFS_MAX_LEVEL; i++) { 76 p->slots[i] = 0; 77 if (!p->nodes[i]) 78 continue; 79 if (p->locks[i]) { 80 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]); 81 p->locks[i] = 0; 82 } 83 free_extent_buffer(p->nodes[i]); 84 p->nodes[i] = NULL; 85 } 86 } 87 88 /* 89 * safely gets a reference on the root node of a tree. A lock 90 * is not taken, so a concurrent writer may put a different node 91 * at the root of the tree. See btrfs_lock_root_node for the 92 * looping required. 93 * 94 * The extent buffer returned by this has a reference taken, so 95 * it won't disappear. It may stop being the root of the tree 96 * at any time because there are no locks held. 97 */ 98 struct extent_buffer *btrfs_root_node(struct btrfs_root *root) 99 { 100 struct extent_buffer *eb; 101 102 while (1) { 103 rcu_read_lock(); 104 eb = rcu_dereference(root->node); 105 106 /* 107 * RCU really hurts here, we could free up the root node because 108 * it was COWed but we may not get the new root node yet so do 109 * the inc_not_zero dance and if it doesn't work then 110 * synchronize_rcu and try again. 111 */ 112 if (atomic_inc_not_zero(&eb->refs)) { 113 rcu_read_unlock(); 114 break; 115 } 116 rcu_read_unlock(); 117 synchronize_rcu(); 118 } 119 return eb; 120 } 121 122 /* loop around taking references on and locking the root node of the 123 * tree until you end up with a lock on the root. A locked buffer 124 * is returned, with a reference held. 125 */ 126 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) 127 { 128 struct extent_buffer *eb; 129 130 while (1) { 131 eb = btrfs_root_node(root); 132 btrfs_tree_lock(eb); 133 if (eb == root->node) 134 break; 135 btrfs_tree_unlock(eb); 136 free_extent_buffer(eb); 137 } 138 return eb; 139 } 140 141 /* loop around taking references on and locking the root node of the 142 * tree until you end up with a lock on the root. A locked buffer 143 * is returned, with a reference held. 144 */ 145 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root) 146 { 147 struct extent_buffer *eb; 148 149 while (1) { 150 eb = btrfs_root_node(root); 151 btrfs_tree_read_lock(eb); 152 if (eb == root->node) 153 break; 154 btrfs_tree_read_unlock(eb); 155 free_extent_buffer(eb); 156 } 157 return eb; 158 } 159 160 /* cowonly root (everything not a reference counted cow subvolume), just get 161 * put onto a simple dirty list. transaction.c walks this to make sure they 162 * get properly updated on disk. 163 */ 164 static void add_root_to_dirty_list(struct btrfs_root *root) 165 { 166 struct btrfs_fs_info *fs_info = root->fs_info; 167 168 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) || 169 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state)) 170 return; 171 172 spin_lock(&fs_info->trans_lock); 173 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) { 174 /* Want the extent tree to be the last on the list */ 175 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID) 176 list_move_tail(&root->dirty_list, 177 &fs_info->dirty_cowonly_roots); 178 else 179 list_move(&root->dirty_list, 180 &fs_info->dirty_cowonly_roots); 181 } 182 spin_unlock(&fs_info->trans_lock); 183 } 184 185 /* 186 * used by snapshot creation to make a copy of a root for a tree with 187 * a given objectid. The buffer with the new root node is returned in 188 * cow_ret, and this func returns zero on success or a negative error code. 189 */ 190 int btrfs_copy_root(struct btrfs_trans_handle *trans, 191 struct btrfs_root *root, 192 struct extent_buffer *buf, 193 struct extent_buffer **cow_ret, u64 new_root_objectid) 194 { 195 struct btrfs_fs_info *fs_info = root->fs_info; 196 struct extent_buffer *cow; 197 int ret = 0; 198 int level; 199 struct btrfs_disk_key disk_key; 200 201 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) && 202 trans->transid != fs_info->running_transaction->transid); 203 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) && 204 trans->transid != root->last_trans); 205 206 level = btrfs_header_level(buf); 207 if (level == 0) 208 btrfs_item_key(buf, &disk_key, 0); 209 else 210 btrfs_node_key(buf, &disk_key, 0); 211 212 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid, 213 &disk_key, level, buf->start, 0); 214 if (IS_ERR(cow)) 215 return PTR_ERR(cow); 216 217 copy_extent_buffer_full(cow, buf); 218 btrfs_set_header_bytenr(cow, cow->start); 219 btrfs_set_header_generation(cow, trans->transid); 220 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV); 221 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN | 222 BTRFS_HEADER_FLAG_RELOC); 223 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) 224 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC); 225 else 226 btrfs_set_header_owner(cow, new_root_objectid); 227 228 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid); 229 230 WARN_ON(btrfs_header_generation(buf) > trans->transid); 231 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) 232 ret = btrfs_inc_ref(trans, root, cow, 1); 233 else 234 ret = btrfs_inc_ref(trans, root, cow, 0); 235 236 if (ret) 237 return ret; 238 239 btrfs_mark_buffer_dirty(cow); 240 *cow_ret = cow; 241 return 0; 242 } 243 244 enum mod_log_op { 245 MOD_LOG_KEY_REPLACE, 246 MOD_LOG_KEY_ADD, 247 MOD_LOG_KEY_REMOVE, 248 MOD_LOG_KEY_REMOVE_WHILE_FREEING, 249 MOD_LOG_KEY_REMOVE_WHILE_MOVING, 250 MOD_LOG_MOVE_KEYS, 251 MOD_LOG_ROOT_REPLACE, 252 }; 253 254 struct tree_mod_root { 255 u64 logical; 256 u8 level; 257 }; 258 259 struct tree_mod_elem { 260 struct rb_node node; 261 u64 logical; 262 u64 seq; 263 enum mod_log_op op; 264 265 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */ 266 int slot; 267 268 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */ 269 u64 generation; 270 271 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */ 272 struct btrfs_disk_key key; 273 u64 blockptr; 274 275 /* this is used for op == MOD_LOG_MOVE_KEYS */ 276 struct { 277 int dst_slot; 278 int nr_items; 279 } move; 280 281 /* this is used for op == MOD_LOG_ROOT_REPLACE */ 282 struct tree_mod_root old_root; 283 }; 284 285 /* 286 * Pull a new tree mod seq number for our operation. 287 */ 288 static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info) 289 { 290 return atomic64_inc_return(&fs_info->tree_mod_seq); 291 } 292 293 /* 294 * This adds a new blocker to the tree mod log's blocker list if the @elem 295 * passed does not already have a sequence number set. So when a caller expects 296 * to record tree modifications, it should ensure to set elem->seq to zero 297 * before calling btrfs_get_tree_mod_seq. 298 * Returns a fresh, unused tree log modification sequence number, even if no new 299 * blocker was added. 300 */ 301 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info, 302 struct seq_list *elem) 303 { 304 write_lock(&fs_info->tree_mod_log_lock); 305 spin_lock(&fs_info->tree_mod_seq_lock); 306 if (!elem->seq) { 307 elem->seq = btrfs_inc_tree_mod_seq(fs_info); 308 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list); 309 } 310 spin_unlock(&fs_info->tree_mod_seq_lock); 311 write_unlock(&fs_info->tree_mod_log_lock); 312 313 return elem->seq; 314 } 315 316 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info, 317 struct seq_list *elem) 318 { 319 struct rb_root *tm_root; 320 struct rb_node *node; 321 struct rb_node *next; 322 struct seq_list *cur_elem; 323 struct tree_mod_elem *tm; 324 u64 min_seq = (u64)-1; 325 u64 seq_putting = elem->seq; 326 327 if (!seq_putting) 328 return; 329 330 spin_lock(&fs_info->tree_mod_seq_lock); 331 list_del(&elem->list); 332 elem->seq = 0; 333 334 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) { 335 if (cur_elem->seq < min_seq) { 336 if (seq_putting > cur_elem->seq) { 337 /* 338 * blocker with lower sequence number exists, we 339 * cannot remove anything from the log 340 */ 341 spin_unlock(&fs_info->tree_mod_seq_lock); 342 return; 343 } 344 min_seq = cur_elem->seq; 345 } 346 } 347 spin_unlock(&fs_info->tree_mod_seq_lock); 348 349 /* 350 * anything that's lower than the lowest existing (read: blocked) 351 * sequence number can be removed from the tree. 352 */ 353 write_lock(&fs_info->tree_mod_log_lock); 354 tm_root = &fs_info->tree_mod_log; 355 for (node = rb_first(tm_root); node; node = next) { 356 next = rb_next(node); 357 tm = rb_entry(node, struct tree_mod_elem, node); 358 if (tm->seq > min_seq) 359 continue; 360 rb_erase(node, tm_root); 361 kfree(tm); 362 } 363 write_unlock(&fs_info->tree_mod_log_lock); 364 } 365 366 /* 367 * key order of the log: 368 * node/leaf start address -> sequence 369 * 370 * The 'start address' is the logical address of the *new* root node 371 * for root replace operations, or the logical address of the affected 372 * block for all other operations. 373 * 374 * Note: must be called with write lock for fs_info::tree_mod_log_lock. 375 */ 376 static noinline int 377 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm) 378 { 379 struct rb_root *tm_root; 380 struct rb_node **new; 381 struct rb_node *parent = NULL; 382 struct tree_mod_elem *cur; 383 384 tm->seq = btrfs_inc_tree_mod_seq(fs_info); 385 386 tm_root = &fs_info->tree_mod_log; 387 new = &tm_root->rb_node; 388 while (*new) { 389 cur = rb_entry(*new, struct tree_mod_elem, node); 390 parent = *new; 391 if (cur->logical < tm->logical) 392 new = &((*new)->rb_left); 393 else if (cur->logical > tm->logical) 394 new = &((*new)->rb_right); 395 else if (cur->seq < tm->seq) 396 new = &((*new)->rb_left); 397 else if (cur->seq > tm->seq) 398 new = &((*new)->rb_right); 399 else 400 return -EEXIST; 401 } 402 403 rb_link_node(&tm->node, parent, new); 404 rb_insert_color(&tm->node, tm_root); 405 return 0; 406 } 407 408 /* 409 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it 410 * returns zero with the tree_mod_log_lock acquired. The caller must hold 411 * this until all tree mod log insertions are recorded in the rb tree and then 412 * write unlock fs_info::tree_mod_log_lock. 413 */ 414 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info, 415 struct extent_buffer *eb) { 416 smp_mb(); 417 if (list_empty(&(fs_info)->tree_mod_seq_list)) 418 return 1; 419 if (eb && btrfs_header_level(eb) == 0) 420 return 1; 421 422 write_lock(&fs_info->tree_mod_log_lock); 423 if (list_empty(&(fs_info)->tree_mod_seq_list)) { 424 write_unlock(&fs_info->tree_mod_log_lock); 425 return 1; 426 } 427 428 return 0; 429 } 430 431 /* Similar to tree_mod_dont_log, but doesn't acquire any locks. */ 432 static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info, 433 struct extent_buffer *eb) 434 { 435 smp_mb(); 436 if (list_empty(&(fs_info)->tree_mod_seq_list)) 437 return 0; 438 if (eb && btrfs_header_level(eb) == 0) 439 return 0; 440 441 return 1; 442 } 443 444 static struct tree_mod_elem * 445 alloc_tree_mod_elem(struct extent_buffer *eb, int slot, 446 enum mod_log_op op, gfp_t flags) 447 { 448 struct tree_mod_elem *tm; 449 450 tm = kzalloc(sizeof(*tm), flags); 451 if (!tm) 452 return NULL; 453 454 tm->logical = eb->start; 455 if (op != MOD_LOG_KEY_ADD) { 456 btrfs_node_key(eb, &tm->key, slot); 457 tm->blockptr = btrfs_node_blockptr(eb, slot); 458 } 459 tm->op = op; 460 tm->slot = slot; 461 tm->generation = btrfs_node_ptr_generation(eb, slot); 462 RB_CLEAR_NODE(&tm->node); 463 464 return tm; 465 } 466 467 static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot, 468 enum mod_log_op op, gfp_t flags) 469 { 470 struct tree_mod_elem *tm; 471 int ret; 472 473 if (!tree_mod_need_log(eb->fs_info, eb)) 474 return 0; 475 476 tm = alloc_tree_mod_elem(eb, slot, op, flags); 477 if (!tm) 478 return -ENOMEM; 479 480 if (tree_mod_dont_log(eb->fs_info, eb)) { 481 kfree(tm); 482 return 0; 483 } 484 485 ret = __tree_mod_log_insert(eb->fs_info, tm); 486 write_unlock(&eb->fs_info->tree_mod_log_lock); 487 if (ret) 488 kfree(tm); 489 490 return ret; 491 } 492 493 static noinline int tree_mod_log_insert_move(struct extent_buffer *eb, 494 int dst_slot, int src_slot, int nr_items) 495 { 496 struct tree_mod_elem *tm = NULL; 497 struct tree_mod_elem **tm_list = NULL; 498 int ret = 0; 499 int i; 500 int locked = 0; 501 502 if (!tree_mod_need_log(eb->fs_info, eb)) 503 return 0; 504 505 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS); 506 if (!tm_list) 507 return -ENOMEM; 508 509 tm = kzalloc(sizeof(*tm), GFP_NOFS); 510 if (!tm) { 511 ret = -ENOMEM; 512 goto free_tms; 513 } 514 515 tm->logical = eb->start; 516 tm->slot = src_slot; 517 tm->move.dst_slot = dst_slot; 518 tm->move.nr_items = nr_items; 519 tm->op = MOD_LOG_MOVE_KEYS; 520 521 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) { 522 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot, 523 MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS); 524 if (!tm_list[i]) { 525 ret = -ENOMEM; 526 goto free_tms; 527 } 528 } 529 530 if (tree_mod_dont_log(eb->fs_info, eb)) 531 goto free_tms; 532 locked = 1; 533 534 /* 535 * When we override something during the move, we log these removals. 536 * This can only happen when we move towards the beginning of the 537 * buffer, i.e. dst_slot < src_slot. 538 */ 539 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) { 540 ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]); 541 if (ret) 542 goto free_tms; 543 } 544 545 ret = __tree_mod_log_insert(eb->fs_info, tm); 546 if (ret) 547 goto free_tms; 548 write_unlock(&eb->fs_info->tree_mod_log_lock); 549 kfree(tm_list); 550 551 return 0; 552 free_tms: 553 for (i = 0; i < nr_items; i++) { 554 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node)) 555 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log); 556 kfree(tm_list[i]); 557 } 558 if (locked) 559 write_unlock(&eb->fs_info->tree_mod_log_lock); 560 kfree(tm_list); 561 kfree(tm); 562 563 return ret; 564 } 565 566 static inline int 567 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, 568 struct tree_mod_elem **tm_list, 569 int nritems) 570 { 571 int i, j; 572 int ret; 573 574 for (i = nritems - 1; i >= 0; i--) { 575 ret = __tree_mod_log_insert(fs_info, tm_list[i]); 576 if (ret) { 577 for (j = nritems - 1; j > i; j--) 578 rb_erase(&tm_list[j]->node, 579 &fs_info->tree_mod_log); 580 return ret; 581 } 582 } 583 584 return 0; 585 } 586 587 static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root, 588 struct extent_buffer *new_root, int log_removal) 589 { 590 struct btrfs_fs_info *fs_info = old_root->fs_info; 591 struct tree_mod_elem *tm = NULL; 592 struct tree_mod_elem **tm_list = NULL; 593 int nritems = 0; 594 int ret = 0; 595 int i; 596 597 if (!tree_mod_need_log(fs_info, NULL)) 598 return 0; 599 600 if (log_removal && btrfs_header_level(old_root) > 0) { 601 nritems = btrfs_header_nritems(old_root); 602 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), 603 GFP_NOFS); 604 if (!tm_list) { 605 ret = -ENOMEM; 606 goto free_tms; 607 } 608 for (i = 0; i < nritems; i++) { 609 tm_list[i] = alloc_tree_mod_elem(old_root, i, 610 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS); 611 if (!tm_list[i]) { 612 ret = -ENOMEM; 613 goto free_tms; 614 } 615 } 616 } 617 618 tm = kzalloc(sizeof(*tm), GFP_NOFS); 619 if (!tm) { 620 ret = -ENOMEM; 621 goto free_tms; 622 } 623 624 tm->logical = new_root->start; 625 tm->old_root.logical = old_root->start; 626 tm->old_root.level = btrfs_header_level(old_root); 627 tm->generation = btrfs_header_generation(old_root); 628 tm->op = MOD_LOG_ROOT_REPLACE; 629 630 if (tree_mod_dont_log(fs_info, NULL)) 631 goto free_tms; 632 633 if (tm_list) 634 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems); 635 if (!ret) 636 ret = __tree_mod_log_insert(fs_info, tm); 637 638 write_unlock(&fs_info->tree_mod_log_lock); 639 if (ret) 640 goto free_tms; 641 kfree(tm_list); 642 643 return ret; 644 645 free_tms: 646 if (tm_list) { 647 for (i = 0; i < nritems; i++) 648 kfree(tm_list[i]); 649 kfree(tm_list); 650 } 651 kfree(tm); 652 653 return ret; 654 } 655 656 static struct tree_mod_elem * 657 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq, 658 int smallest) 659 { 660 struct rb_root *tm_root; 661 struct rb_node *node; 662 struct tree_mod_elem *cur = NULL; 663 struct tree_mod_elem *found = NULL; 664 665 read_lock(&fs_info->tree_mod_log_lock); 666 tm_root = &fs_info->tree_mod_log; 667 node = tm_root->rb_node; 668 while (node) { 669 cur = rb_entry(node, struct tree_mod_elem, node); 670 if (cur->logical < start) { 671 node = node->rb_left; 672 } else if (cur->logical > start) { 673 node = node->rb_right; 674 } else if (cur->seq < min_seq) { 675 node = node->rb_left; 676 } else if (!smallest) { 677 /* we want the node with the highest seq */ 678 if (found) 679 BUG_ON(found->seq > cur->seq); 680 found = cur; 681 node = node->rb_left; 682 } else if (cur->seq > min_seq) { 683 /* we want the node with the smallest seq */ 684 if (found) 685 BUG_ON(found->seq < cur->seq); 686 found = cur; 687 node = node->rb_right; 688 } else { 689 found = cur; 690 break; 691 } 692 } 693 read_unlock(&fs_info->tree_mod_log_lock); 694 695 return found; 696 } 697 698 /* 699 * this returns the element from the log with the smallest time sequence 700 * value that's in the log (the oldest log item). any element with a time 701 * sequence lower than min_seq will be ignored. 702 */ 703 static struct tree_mod_elem * 704 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start, 705 u64 min_seq) 706 { 707 return __tree_mod_log_search(fs_info, start, min_seq, 1); 708 } 709 710 /* 711 * this returns the element from the log with the largest time sequence 712 * value that's in the log (the most recent log item). any element with 713 * a time sequence lower than min_seq will be ignored. 714 */ 715 static struct tree_mod_elem * 716 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq) 717 { 718 return __tree_mod_log_search(fs_info, start, min_seq, 0); 719 } 720 721 static noinline int 722 tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst, 723 struct extent_buffer *src, unsigned long dst_offset, 724 unsigned long src_offset, int nr_items) 725 { 726 int ret = 0; 727 struct tree_mod_elem **tm_list = NULL; 728 struct tree_mod_elem **tm_list_add, **tm_list_rem; 729 int i; 730 int locked = 0; 731 732 if (!tree_mod_need_log(fs_info, NULL)) 733 return 0; 734 735 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0) 736 return 0; 737 738 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *), 739 GFP_NOFS); 740 if (!tm_list) 741 return -ENOMEM; 742 743 tm_list_add = tm_list; 744 tm_list_rem = tm_list + nr_items; 745 for (i = 0; i < nr_items; i++) { 746 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset, 747 MOD_LOG_KEY_REMOVE, GFP_NOFS); 748 if (!tm_list_rem[i]) { 749 ret = -ENOMEM; 750 goto free_tms; 751 } 752 753 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset, 754 MOD_LOG_KEY_ADD, GFP_NOFS); 755 if (!tm_list_add[i]) { 756 ret = -ENOMEM; 757 goto free_tms; 758 } 759 } 760 761 if (tree_mod_dont_log(fs_info, NULL)) 762 goto free_tms; 763 locked = 1; 764 765 for (i = 0; i < nr_items; i++) { 766 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]); 767 if (ret) 768 goto free_tms; 769 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]); 770 if (ret) 771 goto free_tms; 772 } 773 774 write_unlock(&fs_info->tree_mod_log_lock); 775 kfree(tm_list); 776 777 return 0; 778 779 free_tms: 780 for (i = 0; i < nr_items * 2; i++) { 781 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node)) 782 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log); 783 kfree(tm_list[i]); 784 } 785 if (locked) 786 write_unlock(&fs_info->tree_mod_log_lock); 787 kfree(tm_list); 788 789 return ret; 790 } 791 792 static noinline int tree_mod_log_free_eb(struct extent_buffer *eb) 793 { 794 struct tree_mod_elem **tm_list = NULL; 795 int nritems = 0; 796 int i; 797 int ret = 0; 798 799 if (btrfs_header_level(eb) == 0) 800 return 0; 801 802 if (!tree_mod_need_log(eb->fs_info, NULL)) 803 return 0; 804 805 nritems = btrfs_header_nritems(eb); 806 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS); 807 if (!tm_list) 808 return -ENOMEM; 809 810 for (i = 0; i < nritems; i++) { 811 tm_list[i] = alloc_tree_mod_elem(eb, i, 812 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS); 813 if (!tm_list[i]) { 814 ret = -ENOMEM; 815 goto free_tms; 816 } 817 } 818 819 if (tree_mod_dont_log(eb->fs_info, eb)) 820 goto free_tms; 821 822 ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems); 823 write_unlock(&eb->fs_info->tree_mod_log_lock); 824 if (ret) 825 goto free_tms; 826 kfree(tm_list); 827 828 return 0; 829 830 free_tms: 831 for (i = 0; i < nritems; i++) 832 kfree(tm_list[i]); 833 kfree(tm_list); 834 835 return ret; 836 } 837 838 /* 839 * check if the tree block can be shared by multiple trees 840 */ 841 int btrfs_block_can_be_shared(struct btrfs_root *root, 842 struct extent_buffer *buf) 843 { 844 /* 845 * Tree blocks not in reference counted trees and tree roots 846 * are never shared. If a block was allocated after the last 847 * snapshot and the block was not allocated by tree relocation, 848 * we know the block is not shared. 849 */ 850 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) && 851 buf != root->node && buf != root->commit_root && 852 (btrfs_header_generation(buf) <= 853 btrfs_root_last_snapshot(&root->root_item) || 854 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) 855 return 1; 856 857 return 0; 858 } 859 860 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans, 861 struct btrfs_root *root, 862 struct extent_buffer *buf, 863 struct extent_buffer *cow, 864 int *last_ref) 865 { 866 struct btrfs_fs_info *fs_info = root->fs_info; 867 u64 refs; 868 u64 owner; 869 u64 flags; 870 u64 new_flags = 0; 871 int ret; 872 873 /* 874 * Backrefs update rules: 875 * 876 * Always use full backrefs for extent pointers in tree block 877 * allocated by tree relocation. 878 * 879 * If a shared tree block is no longer referenced by its owner 880 * tree (btrfs_header_owner(buf) == root->root_key.objectid), 881 * use full backrefs for extent pointers in tree block. 882 * 883 * If a tree block is been relocating 884 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID), 885 * use full backrefs for extent pointers in tree block. 886 * The reason for this is some operations (such as drop tree) 887 * are only allowed for blocks use full backrefs. 888 */ 889 890 if (btrfs_block_can_be_shared(root, buf)) { 891 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start, 892 btrfs_header_level(buf), 1, 893 &refs, &flags); 894 if (ret) 895 return ret; 896 if (refs == 0) { 897 ret = -EROFS; 898 btrfs_handle_fs_error(fs_info, ret, NULL); 899 return ret; 900 } 901 } else { 902 refs = 1; 903 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || 904 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) 905 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF; 906 else 907 flags = 0; 908 } 909 910 owner = btrfs_header_owner(buf); 911 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID && 912 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)); 913 914 if (refs > 1) { 915 if ((owner == root->root_key.objectid || 916 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && 917 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) { 918 ret = btrfs_inc_ref(trans, root, buf, 1); 919 if (ret) 920 return ret; 921 922 if (root->root_key.objectid == 923 BTRFS_TREE_RELOC_OBJECTID) { 924 ret = btrfs_dec_ref(trans, root, buf, 0); 925 if (ret) 926 return ret; 927 ret = btrfs_inc_ref(trans, root, cow, 1); 928 if (ret) 929 return ret; 930 } 931 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF; 932 } else { 933 934 if (root->root_key.objectid == 935 BTRFS_TREE_RELOC_OBJECTID) 936 ret = btrfs_inc_ref(trans, root, cow, 1); 937 else 938 ret = btrfs_inc_ref(trans, root, cow, 0); 939 if (ret) 940 return ret; 941 } 942 if (new_flags != 0) { 943 int level = btrfs_header_level(buf); 944 945 ret = btrfs_set_disk_extent_flags(trans, fs_info, 946 buf->start, 947 buf->len, 948 new_flags, level, 0); 949 if (ret) 950 return ret; 951 } 952 } else { 953 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) { 954 if (root->root_key.objectid == 955 BTRFS_TREE_RELOC_OBJECTID) 956 ret = btrfs_inc_ref(trans, root, cow, 1); 957 else 958 ret = btrfs_inc_ref(trans, root, cow, 0); 959 if (ret) 960 return ret; 961 ret = btrfs_dec_ref(trans, root, buf, 1); 962 if (ret) 963 return ret; 964 } 965 clean_tree_block(fs_info, buf); 966 *last_ref = 1; 967 } 968 return 0; 969 } 970 971 /* 972 * does the dirty work in cow of a single block. The parent block (if 973 * supplied) is updated to point to the new cow copy. The new buffer is marked 974 * dirty and returned locked. If you modify the block it needs to be marked 975 * dirty again. 976 * 977 * search_start -- an allocation hint for the new block 978 * 979 * empty_size -- a hint that you plan on doing more cow. This is the size in 980 * bytes the allocator should try to find free next to the block it returns. 981 * This is just a hint and may be ignored by the allocator. 982 */ 983 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, 984 struct btrfs_root *root, 985 struct extent_buffer *buf, 986 struct extent_buffer *parent, int parent_slot, 987 struct extent_buffer **cow_ret, 988 u64 search_start, u64 empty_size) 989 { 990 struct btrfs_fs_info *fs_info = root->fs_info; 991 struct btrfs_disk_key disk_key; 992 struct extent_buffer *cow; 993 int level, ret; 994 int last_ref = 0; 995 int unlock_orig = 0; 996 u64 parent_start = 0; 997 998 if (*cow_ret == buf) 999 unlock_orig = 1; 1000 1001 btrfs_assert_tree_locked(buf); 1002 1003 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) && 1004 trans->transid != fs_info->running_transaction->transid); 1005 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) && 1006 trans->transid != root->last_trans); 1007 1008 level = btrfs_header_level(buf); 1009 1010 if (level == 0) 1011 btrfs_item_key(buf, &disk_key, 0); 1012 else 1013 btrfs_node_key(buf, &disk_key, 0); 1014 1015 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent) 1016 parent_start = parent->start; 1017 1018 /* 1019 * If we are COWing a node/leaf from the extent, chunk, device or free 1020 * space trees, make sure that we do not finish block group creation of 1021 * pending block groups. We do this to avoid a deadlock. 1022 * COWing can result in allocation of a new chunk, and flushing pending 1023 * block groups (btrfs_create_pending_block_groups()) can be triggered 1024 * when finishing allocation of a new chunk. Creation of a pending block 1025 * group modifies the extent, chunk, device and free space trees, 1026 * therefore we could deadlock with ourselves since we are holding a 1027 * lock on an extent buffer that btrfs_create_pending_block_groups() may 1028 * try to COW later. 1029 */ 1030 if (root == fs_info->extent_root || 1031 root == fs_info->chunk_root || 1032 root == fs_info->dev_root || 1033 root == fs_info->free_space_root) 1034 trans->can_flush_pending_bgs = false; 1035 1036 cow = btrfs_alloc_tree_block(trans, root, parent_start, 1037 root->root_key.objectid, &disk_key, level, 1038 search_start, empty_size); 1039 trans->can_flush_pending_bgs = true; 1040 if (IS_ERR(cow)) 1041 return PTR_ERR(cow); 1042 1043 /* cow is set to blocking by btrfs_init_new_buffer */ 1044 1045 copy_extent_buffer_full(cow, buf); 1046 btrfs_set_header_bytenr(cow, cow->start); 1047 btrfs_set_header_generation(cow, trans->transid); 1048 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV); 1049 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN | 1050 BTRFS_HEADER_FLAG_RELOC); 1051 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) 1052 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC); 1053 else 1054 btrfs_set_header_owner(cow, root->root_key.objectid); 1055 1056 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid); 1057 1058 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref); 1059 if (ret) { 1060 btrfs_abort_transaction(trans, ret); 1061 return ret; 1062 } 1063 1064 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) { 1065 ret = btrfs_reloc_cow_block(trans, root, buf, cow); 1066 if (ret) { 1067 btrfs_abort_transaction(trans, ret); 1068 return ret; 1069 } 1070 } 1071 1072 if (buf == root->node) { 1073 WARN_ON(parent && parent != buf); 1074 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || 1075 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV) 1076 parent_start = buf->start; 1077 1078 extent_buffer_get(cow); 1079 ret = tree_mod_log_insert_root(root->node, cow, 1); 1080 BUG_ON(ret < 0); 1081 rcu_assign_pointer(root->node, cow); 1082 1083 btrfs_free_tree_block(trans, root, buf, parent_start, 1084 last_ref); 1085 free_extent_buffer(buf); 1086 add_root_to_dirty_list(root); 1087 } else { 1088 WARN_ON(trans->transid != btrfs_header_generation(parent)); 1089 tree_mod_log_insert_key(parent, parent_slot, 1090 MOD_LOG_KEY_REPLACE, GFP_NOFS); 1091 btrfs_set_node_blockptr(parent, parent_slot, 1092 cow->start); 1093 btrfs_set_node_ptr_generation(parent, parent_slot, 1094 trans->transid); 1095 btrfs_mark_buffer_dirty(parent); 1096 if (last_ref) { 1097 ret = tree_mod_log_free_eb(buf); 1098 if (ret) { 1099 btrfs_abort_transaction(trans, ret); 1100 return ret; 1101 } 1102 } 1103 btrfs_free_tree_block(trans, root, buf, parent_start, 1104 last_ref); 1105 } 1106 if (unlock_orig) 1107 btrfs_tree_unlock(buf); 1108 free_extent_buffer_stale(buf); 1109 btrfs_mark_buffer_dirty(cow); 1110 *cow_ret = cow; 1111 return 0; 1112 } 1113 1114 /* 1115 * returns the logical address of the oldest predecessor of the given root. 1116 * entries older than time_seq are ignored. 1117 */ 1118 static struct tree_mod_elem *__tree_mod_log_oldest_root( 1119 struct extent_buffer *eb_root, u64 time_seq) 1120 { 1121 struct tree_mod_elem *tm; 1122 struct tree_mod_elem *found = NULL; 1123 u64 root_logical = eb_root->start; 1124 int looped = 0; 1125 1126 if (!time_seq) 1127 return NULL; 1128 1129 /* 1130 * the very last operation that's logged for a root is the 1131 * replacement operation (if it is replaced at all). this has 1132 * the logical address of the *new* root, making it the very 1133 * first operation that's logged for this root. 1134 */ 1135 while (1) { 1136 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical, 1137 time_seq); 1138 if (!looped && !tm) 1139 return NULL; 1140 /* 1141 * if there are no tree operation for the oldest root, we simply 1142 * return it. this should only happen if that (old) root is at 1143 * level 0. 1144 */ 1145 if (!tm) 1146 break; 1147 1148 /* 1149 * if there's an operation that's not a root replacement, we 1150 * found the oldest version of our root. normally, we'll find a 1151 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here. 1152 */ 1153 if (tm->op != MOD_LOG_ROOT_REPLACE) 1154 break; 1155 1156 found = tm; 1157 root_logical = tm->old_root.logical; 1158 looped = 1; 1159 } 1160 1161 /* if there's no old root to return, return what we found instead */ 1162 if (!found) 1163 found = tm; 1164 1165 return found; 1166 } 1167 1168 /* 1169 * tm is a pointer to the first operation to rewind within eb. then, all 1170 * previous operations will be rewound (until we reach something older than 1171 * time_seq). 1172 */ 1173 static void 1174 __tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb, 1175 u64 time_seq, struct tree_mod_elem *first_tm) 1176 { 1177 u32 n; 1178 struct rb_node *next; 1179 struct tree_mod_elem *tm = first_tm; 1180 unsigned long o_dst; 1181 unsigned long o_src; 1182 unsigned long p_size = sizeof(struct btrfs_key_ptr); 1183 1184 n = btrfs_header_nritems(eb); 1185 read_lock(&fs_info->tree_mod_log_lock); 1186 while (tm && tm->seq >= time_seq) { 1187 /* 1188 * all the operations are recorded with the operator used for 1189 * the modification. as we're going backwards, we do the 1190 * opposite of each operation here. 1191 */ 1192 switch (tm->op) { 1193 case MOD_LOG_KEY_REMOVE_WHILE_FREEING: 1194 BUG_ON(tm->slot < n); 1195 /* Fallthrough */ 1196 case MOD_LOG_KEY_REMOVE_WHILE_MOVING: 1197 case MOD_LOG_KEY_REMOVE: 1198 btrfs_set_node_key(eb, &tm->key, tm->slot); 1199 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr); 1200 btrfs_set_node_ptr_generation(eb, tm->slot, 1201 tm->generation); 1202 n++; 1203 break; 1204 case MOD_LOG_KEY_REPLACE: 1205 BUG_ON(tm->slot >= n); 1206 btrfs_set_node_key(eb, &tm->key, tm->slot); 1207 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr); 1208 btrfs_set_node_ptr_generation(eb, tm->slot, 1209 tm->generation); 1210 break; 1211 case MOD_LOG_KEY_ADD: 1212 /* if a move operation is needed it's in the log */ 1213 n--; 1214 break; 1215 case MOD_LOG_MOVE_KEYS: 1216 o_dst = btrfs_node_key_ptr_offset(tm->slot); 1217 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot); 1218 memmove_extent_buffer(eb, o_dst, o_src, 1219 tm->move.nr_items * p_size); 1220 break; 1221 case MOD_LOG_ROOT_REPLACE: 1222 /* 1223 * this operation is special. for roots, this must be 1224 * handled explicitly before rewinding. 1225 * for non-roots, this operation may exist if the node 1226 * was a root: root A -> child B; then A gets empty and 1227 * B is promoted to the new root. in the mod log, we'll 1228 * have a root-replace operation for B, a tree block 1229 * that is no root. we simply ignore that operation. 1230 */ 1231 break; 1232 } 1233 next = rb_next(&tm->node); 1234 if (!next) 1235 break; 1236 tm = rb_entry(next, struct tree_mod_elem, node); 1237 if (tm->logical != first_tm->logical) 1238 break; 1239 } 1240 read_unlock(&fs_info->tree_mod_log_lock); 1241 btrfs_set_header_nritems(eb, n); 1242 } 1243 1244 /* 1245 * Called with eb read locked. If the buffer cannot be rewound, the same buffer 1246 * is returned. If rewind operations happen, a fresh buffer is returned. The 1247 * returned buffer is always read-locked. If the returned buffer is not the 1248 * input buffer, the lock on the input buffer is released and the input buffer 1249 * is freed (its refcount is decremented). 1250 */ 1251 static struct extent_buffer * 1252 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path, 1253 struct extent_buffer *eb, u64 time_seq) 1254 { 1255 struct extent_buffer *eb_rewin; 1256 struct tree_mod_elem *tm; 1257 1258 if (!time_seq) 1259 return eb; 1260 1261 if (btrfs_header_level(eb) == 0) 1262 return eb; 1263 1264 tm = tree_mod_log_search(fs_info, eb->start, time_seq); 1265 if (!tm) 1266 return eb; 1267 1268 btrfs_set_path_blocking(path); 1269 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); 1270 1271 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) { 1272 BUG_ON(tm->slot != 0); 1273 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start); 1274 if (!eb_rewin) { 1275 btrfs_tree_read_unlock_blocking(eb); 1276 free_extent_buffer(eb); 1277 return NULL; 1278 } 1279 btrfs_set_header_bytenr(eb_rewin, eb->start); 1280 btrfs_set_header_backref_rev(eb_rewin, 1281 btrfs_header_backref_rev(eb)); 1282 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb)); 1283 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb)); 1284 } else { 1285 eb_rewin = btrfs_clone_extent_buffer(eb); 1286 if (!eb_rewin) { 1287 btrfs_tree_read_unlock_blocking(eb); 1288 free_extent_buffer(eb); 1289 return NULL; 1290 } 1291 } 1292 1293 btrfs_tree_read_unlock_blocking(eb); 1294 free_extent_buffer(eb); 1295 1296 btrfs_tree_read_lock(eb_rewin); 1297 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm); 1298 WARN_ON(btrfs_header_nritems(eb_rewin) > 1299 BTRFS_NODEPTRS_PER_BLOCK(fs_info)); 1300 1301 return eb_rewin; 1302 } 1303 1304 /* 1305 * get_old_root() rewinds the state of @root's root node to the given @time_seq 1306 * value. If there are no changes, the current root->root_node is returned. If 1307 * anything changed in between, there's a fresh buffer allocated on which the 1308 * rewind operations are done. In any case, the returned buffer is read locked. 1309 * Returns NULL on error (with no locks held). 1310 */ 1311 static inline struct extent_buffer * 1312 get_old_root(struct btrfs_root *root, u64 time_seq) 1313 { 1314 struct btrfs_fs_info *fs_info = root->fs_info; 1315 struct tree_mod_elem *tm; 1316 struct extent_buffer *eb = NULL; 1317 struct extent_buffer *eb_root; 1318 struct extent_buffer *old; 1319 struct tree_mod_root *old_root = NULL; 1320 u64 old_generation = 0; 1321 u64 logical; 1322 int level; 1323 1324 eb_root = btrfs_read_lock_root_node(root); 1325 tm = __tree_mod_log_oldest_root(eb_root, time_seq); 1326 if (!tm) 1327 return eb_root; 1328 1329 if (tm->op == MOD_LOG_ROOT_REPLACE) { 1330 old_root = &tm->old_root; 1331 old_generation = tm->generation; 1332 logical = old_root->logical; 1333 level = old_root->level; 1334 } else { 1335 logical = eb_root->start; 1336 level = btrfs_header_level(eb_root); 1337 } 1338 1339 tm = tree_mod_log_search(fs_info, logical, time_seq); 1340 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) { 1341 btrfs_tree_read_unlock(eb_root); 1342 free_extent_buffer(eb_root); 1343 old = read_tree_block(fs_info, logical, 0, level, NULL); 1344 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) { 1345 if (!IS_ERR(old)) 1346 free_extent_buffer(old); 1347 btrfs_warn(fs_info, 1348 "failed to read tree block %llu from get_old_root", 1349 logical); 1350 } else { 1351 eb = btrfs_clone_extent_buffer(old); 1352 free_extent_buffer(old); 1353 } 1354 } else if (old_root) { 1355 btrfs_tree_read_unlock(eb_root); 1356 free_extent_buffer(eb_root); 1357 eb = alloc_dummy_extent_buffer(fs_info, logical); 1358 } else { 1359 btrfs_set_lock_blocking_rw(eb_root, BTRFS_READ_LOCK); 1360 eb = btrfs_clone_extent_buffer(eb_root); 1361 btrfs_tree_read_unlock_blocking(eb_root); 1362 free_extent_buffer(eb_root); 1363 } 1364 1365 if (!eb) 1366 return NULL; 1367 btrfs_tree_read_lock(eb); 1368 if (old_root) { 1369 btrfs_set_header_bytenr(eb, eb->start); 1370 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV); 1371 btrfs_set_header_owner(eb, btrfs_header_owner(eb_root)); 1372 btrfs_set_header_level(eb, old_root->level); 1373 btrfs_set_header_generation(eb, old_generation); 1374 } 1375 if (tm) 1376 __tree_mod_log_rewind(fs_info, eb, time_seq, tm); 1377 else 1378 WARN_ON(btrfs_header_level(eb) != 0); 1379 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info)); 1380 1381 return eb; 1382 } 1383 1384 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq) 1385 { 1386 struct tree_mod_elem *tm; 1387 int level; 1388 struct extent_buffer *eb_root = btrfs_root_node(root); 1389 1390 tm = __tree_mod_log_oldest_root(eb_root, time_seq); 1391 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) { 1392 level = tm->old_root.level; 1393 } else { 1394 level = btrfs_header_level(eb_root); 1395 } 1396 free_extent_buffer(eb_root); 1397 1398 return level; 1399 } 1400 1401 static inline int should_cow_block(struct btrfs_trans_handle *trans, 1402 struct btrfs_root *root, 1403 struct extent_buffer *buf) 1404 { 1405 if (btrfs_is_testing(root->fs_info)) 1406 return 0; 1407 1408 /* Ensure we can see the FORCE_COW bit */ 1409 smp_mb__before_atomic(); 1410 1411 /* 1412 * We do not need to cow a block if 1413 * 1) this block is not created or changed in this transaction; 1414 * 2) this block does not belong to TREE_RELOC tree; 1415 * 3) the root is not forced COW. 1416 * 1417 * What is forced COW: 1418 * when we create snapshot during committing the transaction, 1419 * after we've finished copying src root, we must COW the shared 1420 * block to ensure the metadata consistency. 1421 */ 1422 if (btrfs_header_generation(buf) == trans->transid && 1423 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) && 1424 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID && 1425 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) && 1426 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state)) 1427 return 0; 1428 return 1; 1429 } 1430 1431 /* 1432 * cows a single block, see __btrfs_cow_block for the real work. 1433 * This version of it has extra checks so that a block isn't COWed more than 1434 * once per transaction, as long as it hasn't been written yet 1435 */ 1436 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, 1437 struct btrfs_root *root, struct extent_buffer *buf, 1438 struct extent_buffer *parent, int parent_slot, 1439 struct extent_buffer **cow_ret) 1440 { 1441 struct btrfs_fs_info *fs_info = root->fs_info; 1442 u64 search_start; 1443 int ret; 1444 1445 if (test_bit(BTRFS_ROOT_DELETING, &root->state)) 1446 btrfs_err(fs_info, 1447 "COW'ing blocks on a fs root that's being dropped"); 1448 1449 if (trans->transaction != fs_info->running_transaction) 1450 WARN(1, KERN_CRIT "trans %llu running %llu\n", 1451 trans->transid, 1452 fs_info->running_transaction->transid); 1453 1454 if (trans->transid != fs_info->generation) 1455 WARN(1, KERN_CRIT "trans %llu running %llu\n", 1456 trans->transid, fs_info->generation); 1457 1458 if (!should_cow_block(trans, root, buf)) { 1459 trans->dirty = true; 1460 *cow_ret = buf; 1461 return 0; 1462 } 1463 1464 search_start = buf->start & ~((u64)SZ_1G - 1); 1465 1466 if (parent) 1467 btrfs_set_lock_blocking(parent); 1468 btrfs_set_lock_blocking(buf); 1469 1470 ret = __btrfs_cow_block(trans, root, buf, parent, 1471 parent_slot, cow_ret, search_start, 0); 1472 1473 trace_btrfs_cow_block(root, buf, *cow_ret); 1474 1475 return ret; 1476 } 1477 1478 /* 1479 * helper function for defrag to decide if two blocks pointed to by a 1480 * node are actually close by 1481 */ 1482 static int close_blocks(u64 blocknr, u64 other, u32 blocksize) 1483 { 1484 if (blocknr < other && other - (blocknr + blocksize) < 32768) 1485 return 1; 1486 if (blocknr > other && blocknr - (other + blocksize) < 32768) 1487 return 1; 1488 return 0; 1489 } 1490 1491 /* 1492 * compare two keys in a memcmp fashion 1493 */ 1494 static int comp_keys(const struct btrfs_disk_key *disk, 1495 const struct btrfs_key *k2) 1496 { 1497 struct btrfs_key k1; 1498 1499 btrfs_disk_key_to_cpu(&k1, disk); 1500 1501 return btrfs_comp_cpu_keys(&k1, k2); 1502 } 1503 1504 /* 1505 * same as comp_keys only with two btrfs_key's 1506 */ 1507 int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2) 1508 { 1509 if (k1->objectid > k2->objectid) 1510 return 1; 1511 if (k1->objectid < k2->objectid) 1512 return -1; 1513 if (k1->type > k2->type) 1514 return 1; 1515 if (k1->type < k2->type) 1516 return -1; 1517 if (k1->offset > k2->offset) 1518 return 1; 1519 if (k1->offset < k2->offset) 1520 return -1; 1521 return 0; 1522 } 1523 1524 /* 1525 * this is used by the defrag code to go through all the 1526 * leaves pointed to by a node and reallocate them so that 1527 * disk order is close to key order 1528 */ 1529 int btrfs_realloc_node(struct btrfs_trans_handle *trans, 1530 struct btrfs_root *root, struct extent_buffer *parent, 1531 int start_slot, u64 *last_ret, 1532 struct btrfs_key *progress) 1533 { 1534 struct btrfs_fs_info *fs_info = root->fs_info; 1535 struct extent_buffer *cur; 1536 u64 blocknr; 1537 u64 gen; 1538 u64 search_start = *last_ret; 1539 u64 last_block = 0; 1540 u64 other; 1541 u32 parent_nritems; 1542 int end_slot; 1543 int i; 1544 int err = 0; 1545 int parent_level; 1546 int uptodate; 1547 u32 blocksize; 1548 int progress_passed = 0; 1549 struct btrfs_disk_key disk_key; 1550 1551 parent_level = btrfs_header_level(parent); 1552 1553 WARN_ON(trans->transaction != fs_info->running_transaction); 1554 WARN_ON(trans->transid != fs_info->generation); 1555 1556 parent_nritems = btrfs_header_nritems(parent); 1557 blocksize = fs_info->nodesize; 1558 end_slot = parent_nritems - 1; 1559 1560 if (parent_nritems <= 1) 1561 return 0; 1562 1563 btrfs_set_lock_blocking(parent); 1564 1565 for (i = start_slot; i <= end_slot; i++) { 1566 struct btrfs_key first_key; 1567 int close = 1; 1568 1569 btrfs_node_key(parent, &disk_key, i); 1570 if (!progress_passed && comp_keys(&disk_key, progress) < 0) 1571 continue; 1572 1573 progress_passed = 1; 1574 blocknr = btrfs_node_blockptr(parent, i); 1575 gen = btrfs_node_ptr_generation(parent, i); 1576 btrfs_node_key_to_cpu(parent, &first_key, i); 1577 if (last_block == 0) 1578 last_block = blocknr; 1579 1580 if (i > 0) { 1581 other = btrfs_node_blockptr(parent, i - 1); 1582 close = close_blocks(blocknr, other, blocksize); 1583 } 1584 if (!close && i < end_slot) { 1585 other = btrfs_node_blockptr(parent, i + 1); 1586 close = close_blocks(blocknr, other, blocksize); 1587 } 1588 if (close) { 1589 last_block = blocknr; 1590 continue; 1591 } 1592 1593 cur = find_extent_buffer(fs_info, blocknr); 1594 if (cur) 1595 uptodate = btrfs_buffer_uptodate(cur, gen, 0); 1596 else 1597 uptodate = 0; 1598 if (!cur || !uptodate) { 1599 if (!cur) { 1600 cur = read_tree_block(fs_info, blocknr, gen, 1601 parent_level - 1, 1602 &first_key); 1603 if (IS_ERR(cur)) { 1604 return PTR_ERR(cur); 1605 } else if (!extent_buffer_uptodate(cur)) { 1606 free_extent_buffer(cur); 1607 return -EIO; 1608 } 1609 } else if (!uptodate) { 1610 err = btrfs_read_buffer(cur, gen, 1611 parent_level - 1,&first_key); 1612 if (err) { 1613 free_extent_buffer(cur); 1614 return err; 1615 } 1616 } 1617 } 1618 if (search_start == 0) 1619 search_start = last_block; 1620 1621 btrfs_tree_lock(cur); 1622 btrfs_set_lock_blocking(cur); 1623 err = __btrfs_cow_block(trans, root, cur, parent, i, 1624 &cur, search_start, 1625 min(16 * blocksize, 1626 (end_slot - i) * blocksize)); 1627 if (err) { 1628 btrfs_tree_unlock(cur); 1629 free_extent_buffer(cur); 1630 break; 1631 } 1632 search_start = cur->start; 1633 last_block = cur->start; 1634 *last_ret = search_start; 1635 btrfs_tree_unlock(cur); 1636 free_extent_buffer(cur); 1637 } 1638 return err; 1639 } 1640 1641 /* 1642 * search for key in the extent_buffer. The items start at offset p, 1643 * and they are item_size apart. There are 'max' items in p. 1644 * 1645 * the slot in the array is returned via slot, and it points to 1646 * the place where you would insert key if it is not found in 1647 * the array. 1648 * 1649 * slot may point to max if the key is bigger than all of the keys 1650 */ 1651 static noinline int generic_bin_search(struct extent_buffer *eb, 1652 unsigned long p, int item_size, 1653 const struct btrfs_key *key, 1654 int max, int *slot) 1655 { 1656 int low = 0; 1657 int high = max; 1658 int mid; 1659 int ret; 1660 struct btrfs_disk_key *tmp = NULL; 1661 struct btrfs_disk_key unaligned; 1662 unsigned long offset; 1663 char *kaddr = NULL; 1664 unsigned long map_start = 0; 1665 unsigned long map_len = 0; 1666 int err; 1667 1668 if (low > high) { 1669 btrfs_err(eb->fs_info, 1670 "%s: low (%d) > high (%d) eb %llu owner %llu level %d", 1671 __func__, low, high, eb->start, 1672 btrfs_header_owner(eb), btrfs_header_level(eb)); 1673 return -EINVAL; 1674 } 1675 1676 while (low < high) { 1677 mid = (low + high) / 2; 1678 offset = p + mid * item_size; 1679 1680 if (!kaddr || offset < map_start || 1681 (offset + sizeof(struct btrfs_disk_key)) > 1682 map_start + map_len) { 1683 1684 err = map_private_extent_buffer(eb, offset, 1685 sizeof(struct btrfs_disk_key), 1686 &kaddr, &map_start, &map_len); 1687 1688 if (!err) { 1689 tmp = (struct btrfs_disk_key *)(kaddr + offset - 1690 map_start); 1691 } else if (err == 1) { 1692 read_extent_buffer(eb, &unaligned, 1693 offset, sizeof(unaligned)); 1694 tmp = &unaligned; 1695 } else { 1696 return err; 1697 } 1698 1699 } else { 1700 tmp = (struct btrfs_disk_key *)(kaddr + offset - 1701 map_start); 1702 } 1703 ret = comp_keys(tmp, key); 1704 1705 if (ret < 0) 1706 low = mid + 1; 1707 else if (ret > 0) 1708 high = mid; 1709 else { 1710 *slot = mid; 1711 return 0; 1712 } 1713 } 1714 *slot = low; 1715 return 1; 1716 } 1717 1718 /* 1719 * simple bin_search frontend that does the right thing for 1720 * leaves vs nodes 1721 */ 1722 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key, 1723 int level, int *slot) 1724 { 1725 if (level == 0) 1726 return generic_bin_search(eb, 1727 offsetof(struct btrfs_leaf, items), 1728 sizeof(struct btrfs_item), 1729 key, btrfs_header_nritems(eb), 1730 slot); 1731 else 1732 return generic_bin_search(eb, 1733 offsetof(struct btrfs_node, ptrs), 1734 sizeof(struct btrfs_key_ptr), 1735 key, btrfs_header_nritems(eb), 1736 slot); 1737 } 1738 1739 static void root_add_used(struct btrfs_root *root, u32 size) 1740 { 1741 spin_lock(&root->accounting_lock); 1742 btrfs_set_root_used(&root->root_item, 1743 btrfs_root_used(&root->root_item) + size); 1744 spin_unlock(&root->accounting_lock); 1745 } 1746 1747 static void root_sub_used(struct btrfs_root *root, u32 size) 1748 { 1749 spin_lock(&root->accounting_lock); 1750 btrfs_set_root_used(&root->root_item, 1751 btrfs_root_used(&root->root_item) - size); 1752 spin_unlock(&root->accounting_lock); 1753 } 1754 1755 /* given a node and slot number, this reads the blocks it points to. The 1756 * extent buffer is returned with a reference taken (but unlocked). 1757 */ 1758 static noinline struct extent_buffer * 1759 read_node_slot(struct btrfs_fs_info *fs_info, struct extent_buffer *parent, 1760 int slot) 1761 { 1762 int level = btrfs_header_level(parent); 1763 struct extent_buffer *eb; 1764 struct btrfs_key first_key; 1765 1766 if (slot < 0 || slot >= btrfs_header_nritems(parent)) 1767 return ERR_PTR(-ENOENT); 1768 1769 BUG_ON(level == 0); 1770 1771 btrfs_node_key_to_cpu(parent, &first_key, slot); 1772 eb = read_tree_block(fs_info, btrfs_node_blockptr(parent, slot), 1773 btrfs_node_ptr_generation(parent, slot), 1774 level - 1, &first_key); 1775 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) { 1776 free_extent_buffer(eb); 1777 eb = ERR_PTR(-EIO); 1778 } 1779 1780 return eb; 1781 } 1782 1783 /* 1784 * node level balancing, used to make sure nodes are in proper order for 1785 * item deletion. We balance from the top down, so we have to make sure 1786 * that a deletion won't leave an node completely empty later on. 1787 */ 1788 static noinline int balance_level(struct btrfs_trans_handle *trans, 1789 struct btrfs_root *root, 1790 struct btrfs_path *path, int level) 1791 { 1792 struct btrfs_fs_info *fs_info = root->fs_info; 1793 struct extent_buffer *right = NULL; 1794 struct extent_buffer *mid; 1795 struct extent_buffer *left = NULL; 1796 struct extent_buffer *parent = NULL; 1797 int ret = 0; 1798 int wret; 1799 int pslot; 1800 int orig_slot = path->slots[level]; 1801 u64 orig_ptr; 1802 1803 ASSERT(level > 0); 1804 1805 mid = path->nodes[level]; 1806 1807 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK && 1808 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING); 1809 WARN_ON(btrfs_header_generation(mid) != trans->transid); 1810 1811 orig_ptr = btrfs_node_blockptr(mid, orig_slot); 1812 1813 if (level < BTRFS_MAX_LEVEL - 1) { 1814 parent = path->nodes[level + 1]; 1815 pslot = path->slots[level + 1]; 1816 } 1817 1818 /* 1819 * deal with the case where there is only one pointer in the root 1820 * by promoting the node below to a root 1821 */ 1822 if (!parent) { 1823 struct extent_buffer *child; 1824 1825 if (btrfs_header_nritems(mid) != 1) 1826 return 0; 1827 1828 /* promote the child to a root */ 1829 child = read_node_slot(fs_info, mid, 0); 1830 if (IS_ERR(child)) { 1831 ret = PTR_ERR(child); 1832 btrfs_handle_fs_error(fs_info, ret, NULL); 1833 goto enospc; 1834 } 1835 1836 btrfs_tree_lock(child); 1837 btrfs_set_lock_blocking(child); 1838 ret = btrfs_cow_block(trans, root, child, mid, 0, &child); 1839 if (ret) { 1840 btrfs_tree_unlock(child); 1841 free_extent_buffer(child); 1842 goto enospc; 1843 } 1844 1845 ret = tree_mod_log_insert_root(root->node, child, 1); 1846 BUG_ON(ret < 0); 1847 rcu_assign_pointer(root->node, child); 1848 1849 add_root_to_dirty_list(root); 1850 btrfs_tree_unlock(child); 1851 1852 path->locks[level] = 0; 1853 path->nodes[level] = NULL; 1854 clean_tree_block(fs_info, mid); 1855 btrfs_tree_unlock(mid); 1856 /* once for the path */ 1857 free_extent_buffer(mid); 1858 1859 root_sub_used(root, mid->len); 1860 btrfs_free_tree_block(trans, root, mid, 0, 1); 1861 /* once for the root ptr */ 1862 free_extent_buffer_stale(mid); 1863 return 0; 1864 } 1865 if (btrfs_header_nritems(mid) > 1866 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4) 1867 return 0; 1868 1869 left = read_node_slot(fs_info, parent, pslot - 1); 1870 if (IS_ERR(left)) 1871 left = NULL; 1872 1873 if (left) { 1874 btrfs_tree_lock(left); 1875 btrfs_set_lock_blocking(left); 1876 wret = btrfs_cow_block(trans, root, left, 1877 parent, pslot - 1, &left); 1878 if (wret) { 1879 ret = wret; 1880 goto enospc; 1881 } 1882 } 1883 1884 right = read_node_slot(fs_info, parent, pslot + 1); 1885 if (IS_ERR(right)) 1886 right = NULL; 1887 1888 if (right) { 1889 btrfs_tree_lock(right); 1890 btrfs_set_lock_blocking(right); 1891 wret = btrfs_cow_block(trans, root, right, 1892 parent, pslot + 1, &right); 1893 if (wret) { 1894 ret = wret; 1895 goto enospc; 1896 } 1897 } 1898 1899 /* first, try to make some room in the middle buffer */ 1900 if (left) { 1901 orig_slot += btrfs_header_nritems(left); 1902 wret = push_node_left(trans, fs_info, left, mid, 1); 1903 if (wret < 0) 1904 ret = wret; 1905 } 1906 1907 /* 1908 * then try to empty the right most buffer into the middle 1909 */ 1910 if (right) { 1911 wret = push_node_left(trans, fs_info, mid, right, 1); 1912 if (wret < 0 && wret != -ENOSPC) 1913 ret = wret; 1914 if (btrfs_header_nritems(right) == 0) { 1915 clean_tree_block(fs_info, right); 1916 btrfs_tree_unlock(right); 1917 del_ptr(root, path, level + 1, pslot + 1); 1918 root_sub_used(root, right->len); 1919 btrfs_free_tree_block(trans, root, right, 0, 1); 1920 free_extent_buffer_stale(right); 1921 right = NULL; 1922 } else { 1923 struct btrfs_disk_key right_key; 1924 btrfs_node_key(right, &right_key, 0); 1925 ret = tree_mod_log_insert_key(parent, pslot + 1, 1926 MOD_LOG_KEY_REPLACE, GFP_NOFS); 1927 BUG_ON(ret < 0); 1928 btrfs_set_node_key(parent, &right_key, pslot + 1); 1929 btrfs_mark_buffer_dirty(parent); 1930 } 1931 } 1932 if (btrfs_header_nritems(mid) == 1) { 1933 /* 1934 * we're not allowed to leave a node with one item in the 1935 * tree during a delete. A deletion from lower in the tree 1936 * could try to delete the only pointer in this node. 1937 * So, pull some keys from the left. 1938 * There has to be a left pointer at this point because 1939 * otherwise we would have pulled some pointers from the 1940 * right 1941 */ 1942 if (!left) { 1943 ret = -EROFS; 1944 btrfs_handle_fs_error(fs_info, ret, NULL); 1945 goto enospc; 1946 } 1947 wret = balance_node_right(trans, fs_info, mid, left); 1948 if (wret < 0) { 1949 ret = wret; 1950 goto enospc; 1951 } 1952 if (wret == 1) { 1953 wret = push_node_left(trans, fs_info, left, mid, 1); 1954 if (wret < 0) 1955 ret = wret; 1956 } 1957 BUG_ON(wret == 1); 1958 } 1959 if (btrfs_header_nritems(mid) == 0) { 1960 clean_tree_block(fs_info, mid); 1961 btrfs_tree_unlock(mid); 1962 del_ptr(root, path, level + 1, pslot); 1963 root_sub_used(root, mid->len); 1964 btrfs_free_tree_block(trans, root, mid, 0, 1); 1965 free_extent_buffer_stale(mid); 1966 mid = NULL; 1967 } else { 1968 /* update the parent key to reflect our changes */ 1969 struct btrfs_disk_key mid_key; 1970 btrfs_node_key(mid, &mid_key, 0); 1971 ret = tree_mod_log_insert_key(parent, pslot, 1972 MOD_LOG_KEY_REPLACE, GFP_NOFS); 1973 BUG_ON(ret < 0); 1974 btrfs_set_node_key(parent, &mid_key, pslot); 1975 btrfs_mark_buffer_dirty(parent); 1976 } 1977 1978 /* update the path */ 1979 if (left) { 1980 if (btrfs_header_nritems(left) > orig_slot) { 1981 extent_buffer_get(left); 1982 /* left was locked after cow */ 1983 path->nodes[level] = left; 1984 path->slots[level + 1] -= 1; 1985 path->slots[level] = orig_slot; 1986 if (mid) { 1987 btrfs_tree_unlock(mid); 1988 free_extent_buffer(mid); 1989 } 1990 } else { 1991 orig_slot -= btrfs_header_nritems(left); 1992 path->slots[level] = orig_slot; 1993 } 1994 } 1995 /* double check we haven't messed things up */ 1996 if (orig_ptr != 1997 btrfs_node_blockptr(path->nodes[level], path->slots[level])) 1998 BUG(); 1999 enospc: 2000 if (right) { 2001 btrfs_tree_unlock(right); 2002 free_extent_buffer(right); 2003 } 2004 if (left) { 2005 if (path->nodes[level] != left) 2006 btrfs_tree_unlock(left); 2007 free_extent_buffer(left); 2008 } 2009 return ret; 2010 } 2011 2012 /* Node balancing for insertion. Here we only split or push nodes around 2013 * when they are completely full. This is also done top down, so we 2014 * have to be pessimistic. 2015 */ 2016 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, 2017 struct btrfs_root *root, 2018 struct btrfs_path *path, int level) 2019 { 2020 struct btrfs_fs_info *fs_info = root->fs_info; 2021 struct extent_buffer *right = NULL; 2022 struct extent_buffer *mid; 2023 struct extent_buffer *left = NULL; 2024 struct extent_buffer *parent = NULL; 2025 int ret = 0; 2026 int wret; 2027 int pslot; 2028 int orig_slot = path->slots[level]; 2029 2030 if (level == 0) 2031 return 1; 2032 2033 mid = path->nodes[level]; 2034 WARN_ON(btrfs_header_generation(mid) != trans->transid); 2035 2036 if (level < BTRFS_MAX_LEVEL - 1) { 2037 parent = path->nodes[level + 1]; 2038 pslot = path->slots[level + 1]; 2039 } 2040 2041 if (!parent) 2042 return 1; 2043 2044 left = read_node_slot(fs_info, parent, pslot - 1); 2045 if (IS_ERR(left)) 2046 left = NULL; 2047 2048 /* first, try to make some room in the middle buffer */ 2049 if (left) { 2050 u32 left_nr; 2051 2052 btrfs_tree_lock(left); 2053 btrfs_set_lock_blocking(left); 2054 2055 left_nr = btrfs_header_nritems(left); 2056 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) { 2057 wret = 1; 2058 } else { 2059 ret = btrfs_cow_block(trans, root, left, parent, 2060 pslot - 1, &left); 2061 if (ret) 2062 wret = 1; 2063 else { 2064 wret = push_node_left(trans, fs_info, 2065 left, mid, 0); 2066 } 2067 } 2068 if (wret < 0) 2069 ret = wret; 2070 if (wret == 0) { 2071 struct btrfs_disk_key disk_key; 2072 orig_slot += left_nr; 2073 btrfs_node_key(mid, &disk_key, 0); 2074 ret = tree_mod_log_insert_key(parent, pslot, 2075 MOD_LOG_KEY_REPLACE, GFP_NOFS); 2076 BUG_ON(ret < 0); 2077 btrfs_set_node_key(parent, &disk_key, pslot); 2078 btrfs_mark_buffer_dirty(parent); 2079 if (btrfs_header_nritems(left) > orig_slot) { 2080 path->nodes[level] = left; 2081 path->slots[level + 1] -= 1; 2082 path->slots[level] = orig_slot; 2083 btrfs_tree_unlock(mid); 2084 free_extent_buffer(mid); 2085 } else { 2086 orig_slot -= 2087 btrfs_header_nritems(left); 2088 path->slots[level] = orig_slot; 2089 btrfs_tree_unlock(left); 2090 free_extent_buffer(left); 2091 } 2092 return 0; 2093 } 2094 btrfs_tree_unlock(left); 2095 free_extent_buffer(left); 2096 } 2097 right = read_node_slot(fs_info, parent, pslot + 1); 2098 if (IS_ERR(right)) 2099 right = NULL; 2100 2101 /* 2102 * then try to empty the right most buffer into the middle 2103 */ 2104 if (right) { 2105 u32 right_nr; 2106 2107 btrfs_tree_lock(right); 2108 btrfs_set_lock_blocking(right); 2109 2110 right_nr = btrfs_header_nritems(right); 2111 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) { 2112 wret = 1; 2113 } else { 2114 ret = btrfs_cow_block(trans, root, right, 2115 parent, pslot + 1, 2116 &right); 2117 if (ret) 2118 wret = 1; 2119 else { 2120 wret = balance_node_right(trans, fs_info, 2121 right, mid); 2122 } 2123 } 2124 if (wret < 0) 2125 ret = wret; 2126 if (wret == 0) { 2127 struct btrfs_disk_key disk_key; 2128 2129 btrfs_node_key(right, &disk_key, 0); 2130 ret = tree_mod_log_insert_key(parent, pslot + 1, 2131 MOD_LOG_KEY_REPLACE, GFP_NOFS); 2132 BUG_ON(ret < 0); 2133 btrfs_set_node_key(parent, &disk_key, pslot + 1); 2134 btrfs_mark_buffer_dirty(parent); 2135 2136 if (btrfs_header_nritems(mid) <= orig_slot) { 2137 path->nodes[level] = right; 2138 path->slots[level + 1] += 1; 2139 path->slots[level] = orig_slot - 2140 btrfs_header_nritems(mid); 2141 btrfs_tree_unlock(mid); 2142 free_extent_buffer(mid); 2143 } else { 2144 btrfs_tree_unlock(right); 2145 free_extent_buffer(right); 2146 } 2147 return 0; 2148 } 2149 btrfs_tree_unlock(right); 2150 free_extent_buffer(right); 2151 } 2152 return 1; 2153 } 2154 2155 /* 2156 * readahead one full node of leaves, finding things that are close 2157 * to the block in 'slot', and triggering ra on them. 2158 */ 2159 static void reada_for_search(struct btrfs_fs_info *fs_info, 2160 struct btrfs_path *path, 2161 int level, int slot, u64 objectid) 2162 { 2163 struct extent_buffer *node; 2164 struct btrfs_disk_key disk_key; 2165 u32 nritems; 2166 u64 search; 2167 u64 target; 2168 u64 nread = 0; 2169 struct extent_buffer *eb; 2170 u32 nr; 2171 u32 blocksize; 2172 u32 nscan = 0; 2173 2174 if (level != 1) 2175 return; 2176 2177 if (!path->nodes[level]) 2178 return; 2179 2180 node = path->nodes[level]; 2181 2182 search = btrfs_node_blockptr(node, slot); 2183 blocksize = fs_info->nodesize; 2184 eb = find_extent_buffer(fs_info, search); 2185 if (eb) { 2186 free_extent_buffer(eb); 2187 return; 2188 } 2189 2190 target = search; 2191 2192 nritems = btrfs_header_nritems(node); 2193 nr = slot; 2194 2195 while (1) { 2196 if (path->reada == READA_BACK) { 2197 if (nr == 0) 2198 break; 2199 nr--; 2200 } else if (path->reada == READA_FORWARD) { 2201 nr++; 2202 if (nr >= nritems) 2203 break; 2204 } 2205 if (path->reada == READA_BACK && objectid) { 2206 btrfs_node_key(node, &disk_key, nr); 2207 if (btrfs_disk_key_objectid(&disk_key) != objectid) 2208 break; 2209 } 2210 search = btrfs_node_blockptr(node, nr); 2211 if ((search <= target && target - search <= 65536) || 2212 (search > target && search - target <= 65536)) { 2213 readahead_tree_block(fs_info, search); 2214 nread += blocksize; 2215 } 2216 nscan++; 2217 if ((nread > 65536 || nscan > 32)) 2218 break; 2219 } 2220 } 2221 2222 static noinline void reada_for_balance(struct btrfs_fs_info *fs_info, 2223 struct btrfs_path *path, int level) 2224 { 2225 int slot; 2226 int nritems; 2227 struct extent_buffer *parent; 2228 struct extent_buffer *eb; 2229 u64 gen; 2230 u64 block1 = 0; 2231 u64 block2 = 0; 2232 2233 parent = path->nodes[level + 1]; 2234 if (!parent) 2235 return; 2236 2237 nritems = btrfs_header_nritems(parent); 2238 slot = path->slots[level + 1]; 2239 2240 if (slot > 0) { 2241 block1 = btrfs_node_blockptr(parent, slot - 1); 2242 gen = btrfs_node_ptr_generation(parent, slot - 1); 2243 eb = find_extent_buffer(fs_info, block1); 2244 /* 2245 * if we get -eagain from btrfs_buffer_uptodate, we 2246 * don't want to return eagain here. That will loop 2247 * forever 2248 */ 2249 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0) 2250 block1 = 0; 2251 free_extent_buffer(eb); 2252 } 2253 if (slot + 1 < nritems) { 2254 block2 = btrfs_node_blockptr(parent, slot + 1); 2255 gen = btrfs_node_ptr_generation(parent, slot + 1); 2256 eb = find_extent_buffer(fs_info, block2); 2257 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0) 2258 block2 = 0; 2259 free_extent_buffer(eb); 2260 } 2261 2262 if (block1) 2263 readahead_tree_block(fs_info, block1); 2264 if (block2) 2265 readahead_tree_block(fs_info, block2); 2266 } 2267 2268 2269 /* 2270 * when we walk down the tree, it is usually safe to unlock the higher layers 2271 * in the tree. The exceptions are when our path goes through slot 0, because 2272 * operations on the tree might require changing key pointers higher up in the 2273 * tree. 2274 * 2275 * callers might also have set path->keep_locks, which tells this code to keep 2276 * the lock if the path points to the last slot in the block. This is part of 2277 * walking through the tree, and selecting the next slot in the higher block. 2278 * 2279 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so 2280 * if lowest_unlock is 1, level 0 won't be unlocked 2281 */ 2282 static noinline void unlock_up(struct btrfs_path *path, int level, 2283 int lowest_unlock, int min_write_lock_level, 2284 int *write_lock_level) 2285 { 2286 int i; 2287 int skip_level = level; 2288 int no_skips = 0; 2289 struct extent_buffer *t; 2290 2291 for (i = level; i < BTRFS_MAX_LEVEL; i++) { 2292 if (!path->nodes[i]) 2293 break; 2294 if (!path->locks[i]) 2295 break; 2296 if (!no_skips && path->slots[i] == 0) { 2297 skip_level = i + 1; 2298 continue; 2299 } 2300 if (!no_skips && path->keep_locks) { 2301 u32 nritems; 2302 t = path->nodes[i]; 2303 nritems = btrfs_header_nritems(t); 2304 if (nritems < 1 || path->slots[i] >= nritems - 1) { 2305 skip_level = i + 1; 2306 continue; 2307 } 2308 } 2309 if (skip_level < i && i >= lowest_unlock) 2310 no_skips = 1; 2311 2312 t = path->nodes[i]; 2313 if (i >= lowest_unlock && i > skip_level) { 2314 btrfs_tree_unlock_rw(t, path->locks[i]); 2315 path->locks[i] = 0; 2316 if (write_lock_level && 2317 i > min_write_lock_level && 2318 i <= *write_lock_level) { 2319 *write_lock_level = i - 1; 2320 } 2321 } 2322 } 2323 } 2324 2325 /* 2326 * This releases any locks held in the path starting at level and 2327 * going all the way up to the root. 2328 * 2329 * btrfs_search_slot will keep the lock held on higher nodes in a few 2330 * corner cases, such as COW of the block at slot zero in the node. This 2331 * ignores those rules, and it should only be called when there are no 2332 * more updates to be done higher up in the tree. 2333 */ 2334 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) 2335 { 2336 int i; 2337 2338 if (path->keep_locks) 2339 return; 2340 2341 for (i = level; i < BTRFS_MAX_LEVEL; i++) { 2342 if (!path->nodes[i]) 2343 continue; 2344 if (!path->locks[i]) 2345 continue; 2346 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]); 2347 path->locks[i] = 0; 2348 } 2349 } 2350 2351 /* 2352 * helper function for btrfs_search_slot. The goal is to find a block 2353 * in cache without setting the path to blocking. If we find the block 2354 * we return zero and the path is unchanged. 2355 * 2356 * If we can't find the block, we set the path blocking and do some 2357 * reada. -EAGAIN is returned and the search must be repeated. 2358 */ 2359 static int 2360 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p, 2361 struct extent_buffer **eb_ret, int level, int slot, 2362 const struct btrfs_key *key) 2363 { 2364 struct btrfs_fs_info *fs_info = root->fs_info; 2365 u64 blocknr; 2366 u64 gen; 2367 struct extent_buffer *b = *eb_ret; 2368 struct extent_buffer *tmp; 2369 struct btrfs_key first_key; 2370 int ret; 2371 int parent_level; 2372 2373 blocknr = btrfs_node_blockptr(b, slot); 2374 gen = btrfs_node_ptr_generation(b, slot); 2375 parent_level = btrfs_header_level(b); 2376 btrfs_node_key_to_cpu(b, &first_key, slot); 2377 2378 tmp = find_extent_buffer(fs_info, blocknr); 2379 if (tmp) { 2380 /* first we do an atomic uptodate check */ 2381 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) { 2382 *eb_ret = tmp; 2383 return 0; 2384 } 2385 2386 /* the pages were up to date, but we failed 2387 * the generation number check. Do a full 2388 * read for the generation number that is correct. 2389 * We must do this without dropping locks so 2390 * we can trust our generation number 2391 */ 2392 btrfs_set_path_blocking(p); 2393 2394 /* now we're allowed to do a blocking uptodate check */ 2395 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key); 2396 if (!ret) { 2397 *eb_ret = tmp; 2398 return 0; 2399 } 2400 free_extent_buffer(tmp); 2401 btrfs_release_path(p); 2402 return -EIO; 2403 } 2404 2405 /* 2406 * reduce lock contention at high levels 2407 * of the btree by dropping locks before 2408 * we read. Don't release the lock on the current 2409 * level because we need to walk this node to figure 2410 * out which blocks to read. 2411 */ 2412 btrfs_unlock_up_safe(p, level + 1); 2413 btrfs_set_path_blocking(p); 2414 2415 if (p->reada != READA_NONE) 2416 reada_for_search(fs_info, p, level, slot, key->objectid); 2417 2418 ret = -EAGAIN; 2419 tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1, 2420 &first_key); 2421 if (!IS_ERR(tmp)) { 2422 /* 2423 * If the read above didn't mark this buffer up to date, 2424 * it will never end up being up to date. Set ret to EIO now 2425 * and give up so that our caller doesn't loop forever 2426 * on our EAGAINs. 2427 */ 2428 if (!extent_buffer_uptodate(tmp)) 2429 ret = -EIO; 2430 free_extent_buffer(tmp); 2431 } else { 2432 ret = PTR_ERR(tmp); 2433 } 2434 2435 btrfs_release_path(p); 2436 return ret; 2437 } 2438 2439 /* 2440 * helper function for btrfs_search_slot. This does all of the checks 2441 * for node-level blocks and does any balancing required based on 2442 * the ins_len. 2443 * 2444 * If no extra work was required, zero is returned. If we had to 2445 * drop the path, -EAGAIN is returned and btrfs_search_slot must 2446 * start over 2447 */ 2448 static int 2449 setup_nodes_for_search(struct btrfs_trans_handle *trans, 2450 struct btrfs_root *root, struct btrfs_path *p, 2451 struct extent_buffer *b, int level, int ins_len, 2452 int *write_lock_level) 2453 { 2454 struct btrfs_fs_info *fs_info = root->fs_info; 2455 int ret; 2456 2457 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= 2458 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) { 2459 int sret; 2460 2461 if (*write_lock_level < level + 1) { 2462 *write_lock_level = level + 1; 2463 btrfs_release_path(p); 2464 goto again; 2465 } 2466 2467 btrfs_set_path_blocking(p); 2468 reada_for_balance(fs_info, p, level); 2469 sret = split_node(trans, root, p, level); 2470 2471 BUG_ON(sret > 0); 2472 if (sret) { 2473 ret = sret; 2474 goto done; 2475 } 2476 b = p->nodes[level]; 2477 } else if (ins_len < 0 && btrfs_header_nritems(b) < 2478 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) { 2479 int sret; 2480 2481 if (*write_lock_level < level + 1) { 2482 *write_lock_level = level + 1; 2483 btrfs_release_path(p); 2484 goto again; 2485 } 2486 2487 btrfs_set_path_blocking(p); 2488 reada_for_balance(fs_info, p, level); 2489 sret = balance_level(trans, root, p, level); 2490 2491 if (sret) { 2492 ret = sret; 2493 goto done; 2494 } 2495 b = p->nodes[level]; 2496 if (!b) { 2497 btrfs_release_path(p); 2498 goto again; 2499 } 2500 BUG_ON(btrfs_header_nritems(b) == 1); 2501 } 2502 return 0; 2503 2504 again: 2505 ret = -EAGAIN; 2506 done: 2507 return ret; 2508 } 2509 2510 static void key_search_validate(struct extent_buffer *b, 2511 const struct btrfs_key *key, 2512 int level) 2513 { 2514 #ifdef CONFIG_BTRFS_ASSERT 2515 struct btrfs_disk_key disk_key; 2516 2517 btrfs_cpu_key_to_disk(&disk_key, key); 2518 2519 if (level == 0) 2520 ASSERT(!memcmp_extent_buffer(b, &disk_key, 2521 offsetof(struct btrfs_leaf, items[0].key), 2522 sizeof(disk_key))); 2523 else 2524 ASSERT(!memcmp_extent_buffer(b, &disk_key, 2525 offsetof(struct btrfs_node, ptrs[0].key), 2526 sizeof(disk_key))); 2527 #endif 2528 } 2529 2530 static int key_search(struct extent_buffer *b, const struct btrfs_key *key, 2531 int level, int *prev_cmp, int *slot) 2532 { 2533 if (*prev_cmp != 0) { 2534 *prev_cmp = btrfs_bin_search(b, key, level, slot); 2535 return *prev_cmp; 2536 } 2537 2538 key_search_validate(b, key, level); 2539 *slot = 0; 2540 2541 return 0; 2542 } 2543 2544 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path, 2545 u64 iobjectid, u64 ioff, u8 key_type, 2546 struct btrfs_key *found_key) 2547 { 2548 int ret; 2549 struct btrfs_key key; 2550 struct extent_buffer *eb; 2551 2552 ASSERT(path); 2553 ASSERT(found_key); 2554 2555 key.type = key_type; 2556 key.objectid = iobjectid; 2557 key.offset = ioff; 2558 2559 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0); 2560 if (ret < 0) 2561 return ret; 2562 2563 eb = path->nodes[0]; 2564 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) { 2565 ret = btrfs_next_leaf(fs_root, path); 2566 if (ret) 2567 return ret; 2568 eb = path->nodes[0]; 2569 } 2570 2571 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]); 2572 if (found_key->type != key.type || 2573 found_key->objectid != key.objectid) 2574 return 1; 2575 2576 return 0; 2577 } 2578 2579 static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root, 2580 struct btrfs_path *p, 2581 int write_lock_level) 2582 { 2583 struct btrfs_fs_info *fs_info = root->fs_info; 2584 struct extent_buffer *b; 2585 int root_lock; 2586 int level = 0; 2587 2588 /* We try very hard to do read locks on the root */ 2589 root_lock = BTRFS_READ_LOCK; 2590 2591 if (p->search_commit_root) { 2592 /* 2593 * The commit roots are read only so we always do read locks, 2594 * and we always must hold the commit_root_sem when doing 2595 * searches on them, the only exception is send where we don't 2596 * want to block transaction commits for a long time, so 2597 * we need to clone the commit root in order to avoid races 2598 * with transaction commits that create a snapshot of one of 2599 * the roots used by a send operation. 2600 */ 2601 if (p->need_commit_sem) { 2602 down_read(&fs_info->commit_root_sem); 2603 b = btrfs_clone_extent_buffer(root->commit_root); 2604 up_read(&fs_info->commit_root_sem); 2605 if (!b) 2606 return ERR_PTR(-ENOMEM); 2607 2608 } else { 2609 b = root->commit_root; 2610 extent_buffer_get(b); 2611 } 2612 level = btrfs_header_level(b); 2613 /* 2614 * Ensure that all callers have set skip_locking when 2615 * p->search_commit_root = 1. 2616 */ 2617 ASSERT(p->skip_locking == 1); 2618 2619 goto out; 2620 } 2621 2622 if (p->skip_locking) { 2623 b = btrfs_root_node(root); 2624 level = btrfs_header_level(b); 2625 goto out; 2626 } 2627 2628 /* 2629 * If the level is set to maximum, we can skip trying to get the read 2630 * lock. 2631 */ 2632 if (write_lock_level < BTRFS_MAX_LEVEL) { 2633 /* 2634 * We don't know the level of the root node until we actually 2635 * have it read locked 2636 */ 2637 b = btrfs_read_lock_root_node(root); 2638 level = btrfs_header_level(b); 2639 if (level > write_lock_level) 2640 goto out; 2641 2642 /* Whoops, must trade for write lock */ 2643 btrfs_tree_read_unlock(b); 2644 free_extent_buffer(b); 2645 } 2646 2647 b = btrfs_lock_root_node(root); 2648 root_lock = BTRFS_WRITE_LOCK; 2649 2650 /* The level might have changed, check again */ 2651 level = btrfs_header_level(b); 2652 2653 out: 2654 p->nodes[level] = b; 2655 if (!p->skip_locking) 2656 p->locks[level] = root_lock; 2657 /* 2658 * Callers are responsible for dropping b's references. 2659 */ 2660 return b; 2661 } 2662 2663 2664 /* 2665 * btrfs_search_slot - look for a key in a tree and perform necessary 2666 * modifications to preserve tree invariants. 2667 * 2668 * @trans: Handle of transaction, used when modifying the tree 2669 * @p: Holds all btree nodes along the search path 2670 * @root: The root node of the tree 2671 * @key: The key we are looking for 2672 * @ins_len: Indicates purpose of search, for inserts it is 1, for 2673 * deletions it's -1. 0 for plain searches 2674 * @cow: boolean should CoW operations be performed. Must always be 1 2675 * when modifying the tree. 2676 * 2677 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree. 2678 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible) 2679 * 2680 * If @key is found, 0 is returned and you can find the item in the leaf level 2681 * of the path (level 0) 2682 * 2683 * If @key isn't found, 1 is returned and the leaf level of the path (level 0) 2684 * points to the slot where it should be inserted 2685 * 2686 * If an error is encountered while searching the tree a negative error number 2687 * is returned 2688 */ 2689 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, 2690 const struct btrfs_key *key, struct btrfs_path *p, 2691 int ins_len, int cow) 2692 { 2693 struct btrfs_fs_info *fs_info = root->fs_info; 2694 struct extent_buffer *b; 2695 int slot; 2696 int ret; 2697 int err; 2698 int level; 2699 int lowest_unlock = 1; 2700 /* everything at write_lock_level or lower must be write locked */ 2701 int write_lock_level = 0; 2702 u8 lowest_level = 0; 2703 int min_write_lock_level; 2704 int prev_cmp; 2705 2706 lowest_level = p->lowest_level; 2707 WARN_ON(lowest_level && ins_len > 0); 2708 WARN_ON(p->nodes[0] != NULL); 2709 BUG_ON(!cow && ins_len); 2710 2711 if (ins_len < 0) { 2712 lowest_unlock = 2; 2713 2714 /* when we are removing items, we might have to go up to level 2715 * two as we update tree pointers Make sure we keep write 2716 * for those levels as well 2717 */ 2718 write_lock_level = 2; 2719 } else if (ins_len > 0) { 2720 /* 2721 * for inserting items, make sure we have a write lock on 2722 * level 1 so we can update keys 2723 */ 2724 write_lock_level = 1; 2725 } 2726 2727 if (!cow) 2728 write_lock_level = -1; 2729 2730 if (cow && (p->keep_locks || p->lowest_level)) 2731 write_lock_level = BTRFS_MAX_LEVEL; 2732 2733 min_write_lock_level = write_lock_level; 2734 2735 again: 2736 prev_cmp = -1; 2737 b = btrfs_search_slot_get_root(root, p, write_lock_level); 2738 if (IS_ERR(b)) { 2739 ret = PTR_ERR(b); 2740 goto done; 2741 } 2742 2743 while (b) { 2744 level = btrfs_header_level(b); 2745 2746 /* 2747 * setup the path here so we can release it under lock 2748 * contention with the cow code 2749 */ 2750 if (cow) { 2751 bool last_level = (level == (BTRFS_MAX_LEVEL - 1)); 2752 2753 /* 2754 * if we don't really need to cow this block 2755 * then we don't want to set the path blocking, 2756 * so we test it here 2757 */ 2758 if (!should_cow_block(trans, root, b)) { 2759 trans->dirty = true; 2760 goto cow_done; 2761 } 2762 2763 /* 2764 * must have write locks on this node and the 2765 * parent 2766 */ 2767 if (level > write_lock_level || 2768 (level + 1 > write_lock_level && 2769 level + 1 < BTRFS_MAX_LEVEL && 2770 p->nodes[level + 1])) { 2771 write_lock_level = level + 1; 2772 btrfs_release_path(p); 2773 goto again; 2774 } 2775 2776 btrfs_set_path_blocking(p); 2777 if (last_level) 2778 err = btrfs_cow_block(trans, root, b, NULL, 0, 2779 &b); 2780 else 2781 err = btrfs_cow_block(trans, root, b, 2782 p->nodes[level + 1], 2783 p->slots[level + 1], &b); 2784 if (err) { 2785 ret = err; 2786 goto done; 2787 } 2788 } 2789 cow_done: 2790 p->nodes[level] = b; 2791 /* 2792 * Leave path with blocking locks to avoid massive 2793 * lock context switch, this is made on purpose. 2794 */ 2795 2796 /* 2797 * we have a lock on b and as long as we aren't changing 2798 * the tree, there is no way to for the items in b to change. 2799 * It is safe to drop the lock on our parent before we 2800 * go through the expensive btree search on b. 2801 * 2802 * If we're inserting or deleting (ins_len != 0), then we might 2803 * be changing slot zero, which may require changing the parent. 2804 * So, we can't drop the lock until after we know which slot 2805 * we're operating on. 2806 */ 2807 if (!ins_len && !p->keep_locks) { 2808 int u = level + 1; 2809 2810 if (u < BTRFS_MAX_LEVEL && p->locks[u]) { 2811 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]); 2812 p->locks[u] = 0; 2813 } 2814 } 2815 2816 ret = key_search(b, key, level, &prev_cmp, &slot); 2817 if (ret < 0) 2818 goto done; 2819 2820 if (level != 0) { 2821 int dec = 0; 2822 if (ret && slot > 0) { 2823 dec = 1; 2824 slot -= 1; 2825 } 2826 p->slots[level] = slot; 2827 err = setup_nodes_for_search(trans, root, p, b, level, 2828 ins_len, &write_lock_level); 2829 if (err == -EAGAIN) 2830 goto again; 2831 if (err) { 2832 ret = err; 2833 goto done; 2834 } 2835 b = p->nodes[level]; 2836 slot = p->slots[level]; 2837 2838 /* 2839 * slot 0 is special, if we change the key 2840 * we have to update the parent pointer 2841 * which means we must have a write lock 2842 * on the parent 2843 */ 2844 if (slot == 0 && ins_len && 2845 write_lock_level < level + 1) { 2846 write_lock_level = level + 1; 2847 btrfs_release_path(p); 2848 goto again; 2849 } 2850 2851 unlock_up(p, level, lowest_unlock, 2852 min_write_lock_level, &write_lock_level); 2853 2854 if (level == lowest_level) { 2855 if (dec) 2856 p->slots[level]++; 2857 goto done; 2858 } 2859 2860 err = read_block_for_search(root, p, &b, level, 2861 slot, key); 2862 if (err == -EAGAIN) 2863 goto again; 2864 if (err) { 2865 ret = err; 2866 goto done; 2867 } 2868 2869 if (!p->skip_locking) { 2870 level = btrfs_header_level(b); 2871 if (level <= write_lock_level) { 2872 err = btrfs_try_tree_write_lock(b); 2873 if (!err) { 2874 btrfs_set_path_blocking(p); 2875 btrfs_tree_lock(b); 2876 } 2877 p->locks[level] = BTRFS_WRITE_LOCK; 2878 } else { 2879 err = btrfs_tree_read_lock_atomic(b); 2880 if (!err) { 2881 btrfs_set_path_blocking(p); 2882 btrfs_tree_read_lock(b); 2883 } 2884 p->locks[level] = BTRFS_READ_LOCK; 2885 } 2886 p->nodes[level] = b; 2887 } 2888 } else { 2889 p->slots[level] = slot; 2890 if (ins_len > 0 && 2891 btrfs_leaf_free_space(fs_info, b) < ins_len) { 2892 if (write_lock_level < 1) { 2893 write_lock_level = 1; 2894 btrfs_release_path(p); 2895 goto again; 2896 } 2897 2898 btrfs_set_path_blocking(p); 2899 err = split_leaf(trans, root, key, 2900 p, ins_len, ret == 0); 2901 2902 BUG_ON(err > 0); 2903 if (err) { 2904 ret = err; 2905 goto done; 2906 } 2907 } 2908 if (!p->search_for_split) 2909 unlock_up(p, level, lowest_unlock, 2910 min_write_lock_level, NULL); 2911 goto done; 2912 } 2913 } 2914 ret = 1; 2915 done: 2916 /* 2917 * we don't really know what they plan on doing with the path 2918 * from here on, so for now just mark it as blocking 2919 */ 2920 if (!p->leave_spinning) 2921 btrfs_set_path_blocking(p); 2922 if (ret < 0 && !p->skip_release_on_error) 2923 btrfs_release_path(p); 2924 return ret; 2925 } 2926 2927 /* 2928 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the 2929 * current state of the tree together with the operations recorded in the tree 2930 * modification log to search for the key in a previous version of this tree, as 2931 * denoted by the time_seq parameter. 2932 * 2933 * Naturally, there is no support for insert, delete or cow operations. 2934 * 2935 * The resulting path and return value will be set up as if we called 2936 * btrfs_search_slot at that point in time with ins_len and cow both set to 0. 2937 */ 2938 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key, 2939 struct btrfs_path *p, u64 time_seq) 2940 { 2941 struct btrfs_fs_info *fs_info = root->fs_info; 2942 struct extent_buffer *b; 2943 int slot; 2944 int ret; 2945 int err; 2946 int level; 2947 int lowest_unlock = 1; 2948 u8 lowest_level = 0; 2949 int prev_cmp = -1; 2950 2951 lowest_level = p->lowest_level; 2952 WARN_ON(p->nodes[0] != NULL); 2953 2954 if (p->search_commit_root) { 2955 BUG_ON(time_seq); 2956 return btrfs_search_slot(NULL, root, key, p, 0, 0); 2957 } 2958 2959 again: 2960 b = get_old_root(root, time_seq); 2961 if (!b) { 2962 ret = -EIO; 2963 goto done; 2964 } 2965 level = btrfs_header_level(b); 2966 p->locks[level] = BTRFS_READ_LOCK; 2967 2968 while (b) { 2969 level = btrfs_header_level(b); 2970 p->nodes[level] = b; 2971 2972 /* 2973 * we have a lock on b and as long as we aren't changing 2974 * the tree, there is no way to for the items in b to change. 2975 * It is safe to drop the lock on our parent before we 2976 * go through the expensive btree search on b. 2977 */ 2978 btrfs_unlock_up_safe(p, level + 1); 2979 2980 /* 2981 * Since we can unwind ebs we want to do a real search every 2982 * time. 2983 */ 2984 prev_cmp = -1; 2985 ret = key_search(b, key, level, &prev_cmp, &slot); 2986 2987 if (level != 0) { 2988 int dec = 0; 2989 if (ret && slot > 0) { 2990 dec = 1; 2991 slot -= 1; 2992 } 2993 p->slots[level] = slot; 2994 unlock_up(p, level, lowest_unlock, 0, NULL); 2995 2996 if (level == lowest_level) { 2997 if (dec) 2998 p->slots[level]++; 2999 goto done; 3000 } 3001 3002 err = read_block_for_search(root, p, &b, level, 3003 slot, key); 3004 if (err == -EAGAIN) 3005 goto again; 3006 if (err) { 3007 ret = err; 3008 goto done; 3009 } 3010 3011 level = btrfs_header_level(b); 3012 err = btrfs_tree_read_lock_atomic(b); 3013 if (!err) { 3014 btrfs_set_path_blocking(p); 3015 btrfs_tree_read_lock(b); 3016 } 3017 b = tree_mod_log_rewind(fs_info, p, b, time_seq); 3018 if (!b) { 3019 ret = -ENOMEM; 3020 goto done; 3021 } 3022 p->locks[level] = BTRFS_READ_LOCK; 3023 p->nodes[level] = b; 3024 } else { 3025 p->slots[level] = slot; 3026 unlock_up(p, level, lowest_unlock, 0, NULL); 3027 goto done; 3028 } 3029 } 3030 ret = 1; 3031 done: 3032 if (!p->leave_spinning) 3033 btrfs_set_path_blocking(p); 3034 if (ret < 0) 3035 btrfs_release_path(p); 3036 3037 return ret; 3038 } 3039 3040 /* 3041 * helper to use instead of search slot if no exact match is needed but 3042 * instead the next or previous item should be returned. 3043 * When find_higher is true, the next higher item is returned, the next lower 3044 * otherwise. 3045 * When return_any and find_higher are both true, and no higher item is found, 3046 * return the next lower instead. 3047 * When return_any is true and find_higher is false, and no lower item is found, 3048 * return the next higher instead. 3049 * It returns 0 if any item is found, 1 if none is found (tree empty), and 3050 * < 0 on error 3051 */ 3052 int btrfs_search_slot_for_read(struct btrfs_root *root, 3053 const struct btrfs_key *key, 3054 struct btrfs_path *p, int find_higher, 3055 int return_any) 3056 { 3057 int ret; 3058 struct extent_buffer *leaf; 3059 3060 again: 3061 ret = btrfs_search_slot(NULL, root, key, p, 0, 0); 3062 if (ret <= 0) 3063 return ret; 3064 /* 3065 * a return value of 1 means the path is at the position where the 3066 * item should be inserted. Normally this is the next bigger item, 3067 * but in case the previous item is the last in a leaf, path points 3068 * to the first free slot in the previous leaf, i.e. at an invalid 3069 * item. 3070 */ 3071 leaf = p->nodes[0]; 3072 3073 if (find_higher) { 3074 if (p->slots[0] >= btrfs_header_nritems(leaf)) { 3075 ret = btrfs_next_leaf(root, p); 3076 if (ret <= 0) 3077 return ret; 3078 if (!return_any) 3079 return 1; 3080 /* 3081 * no higher item found, return the next 3082 * lower instead 3083 */ 3084 return_any = 0; 3085 find_higher = 0; 3086 btrfs_release_path(p); 3087 goto again; 3088 } 3089 } else { 3090 if (p->slots[0] == 0) { 3091 ret = btrfs_prev_leaf(root, p); 3092 if (ret < 0) 3093 return ret; 3094 if (!ret) { 3095 leaf = p->nodes[0]; 3096 if (p->slots[0] == btrfs_header_nritems(leaf)) 3097 p->slots[0]--; 3098 return 0; 3099 } 3100 if (!return_any) 3101 return 1; 3102 /* 3103 * no lower item found, return the next 3104 * higher instead 3105 */ 3106 return_any = 0; 3107 find_higher = 1; 3108 btrfs_release_path(p); 3109 goto again; 3110 } else { 3111 --p->slots[0]; 3112 } 3113 } 3114 return 0; 3115 } 3116 3117 /* 3118 * adjust the pointers going up the tree, starting at level 3119 * making sure the right key of each node is points to 'key'. 3120 * This is used after shifting pointers to the left, so it stops 3121 * fixing up pointers when a given leaf/node is not in slot 0 of the 3122 * higher levels 3123 * 3124 */ 3125 static void fixup_low_keys(struct btrfs_path *path, 3126 struct btrfs_disk_key *key, int level) 3127 { 3128 int i; 3129 struct extent_buffer *t; 3130 int ret; 3131 3132 for (i = level; i < BTRFS_MAX_LEVEL; i++) { 3133 int tslot = path->slots[i]; 3134 3135 if (!path->nodes[i]) 3136 break; 3137 t = path->nodes[i]; 3138 ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE, 3139 GFP_ATOMIC); 3140 BUG_ON(ret < 0); 3141 btrfs_set_node_key(t, key, tslot); 3142 btrfs_mark_buffer_dirty(path->nodes[i]); 3143 if (tslot != 0) 3144 break; 3145 } 3146 } 3147 3148 /* 3149 * update item key. 3150 * 3151 * This function isn't completely safe. It's the caller's responsibility 3152 * that the new key won't break the order 3153 */ 3154 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info, 3155 struct btrfs_path *path, 3156 const struct btrfs_key *new_key) 3157 { 3158 struct btrfs_disk_key disk_key; 3159 struct extent_buffer *eb; 3160 int slot; 3161 3162 eb = path->nodes[0]; 3163 slot = path->slots[0]; 3164 if (slot > 0) { 3165 btrfs_item_key(eb, &disk_key, slot - 1); 3166 BUG_ON(comp_keys(&disk_key, new_key) >= 0); 3167 } 3168 if (slot < btrfs_header_nritems(eb) - 1) { 3169 btrfs_item_key(eb, &disk_key, slot + 1); 3170 BUG_ON(comp_keys(&disk_key, new_key) <= 0); 3171 } 3172 3173 btrfs_cpu_key_to_disk(&disk_key, new_key); 3174 btrfs_set_item_key(eb, &disk_key, slot); 3175 btrfs_mark_buffer_dirty(eb); 3176 if (slot == 0) 3177 fixup_low_keys(path, &disk_key, 1); 3178 } 3179 3180 /* 3181 * try to push data from one node into the next node left in the 3182 * tree. 3183 * 3184 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible 3185 * error, and > 0 if there was no room in the left hand block. 3186 */ 3187 static int push_node_left(struct btrfs_trans_handle *trans, 3188 struct btrfs_fs_info *fs_info, 3189 struct extent_buffer *dst, 3190 struct extent_buffer *src, int empty) 3191 { 3192 int push_items = 0; 3193 int src_nritems; 3194 int dst_nritems; 3195 int ret = 0; 3196 3197 src_nritems = btrfs_header_nritems(src); 3198 dst_nritems = btrfs_header_nritems(dst); 3199 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems; 3200 WARN_ON(btrfs_header_generation(src) != trans->transid); 3201 WARN_ON(btrfs_header_generation(dst) != trans->transid); 3202 3203 if (!empty && src_nritems <= 8) 3204 return 1; 3205 3206 if (push_items <= 0) 3207 return 1; 3208 3209 if (empty) { 3210 push_items = min(src_nritems, push_items); 3211 if (push_items < src_nritems) { 3212 /* leave at least 8 pointers in the node if 3213 * we aren't going to empty it 3214 */ 3215 if (src_nritems - push_items < 8) { 3216 if (push_items <= 8) 3217 return 1; 3218 push_items -= 8; 3219 } 3220 } 3221 } else 3222 push_items = min(src_nritems - 8, push_items); 3223 3224 ret = tree_mod_log_eb_copy(fs_info, dst, src, dst_nritems, 0, 3225 push_items); 3226 if (ret) { 3227 btrfs_abort_transaction(trans, ret); 3228 return ret; 3229 } 3230 copy_extent_buffer(dst, src, 3231 btrfs_node_key_ptr_offset(dst_nritems), 3232 btrfs_node_key_ptr_offset(0), 3233 push_items * sizeof(struct btrfs_key_ptr)); 3234 3235 if (push_items < src_nritems) { 3236 /* 3237 * Don't call tree_mod_log_insert_move here, key removal was 3238 * already fully logged by tree_mod_log_eb_copy above. 3239 */ 3240 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0), 3241 btrfs_node_key_ptr_offset(push_items), 3242 (src_nritems - push_items) * 3243 sizeof(struct btrfs_key_ptr)); 3244 } 3245 btrfs_set_header_nritems(src, src_nritems - push_items); 3246 btrfs_set_header_nritems(dst, dst_nritems + push_items); 3247 btrfs_mark_buffer_dirty(src); 3248 btrfs_mark_buffer_dirty(dst); 3249 3250 return ret; 3251 } 3252 3253 /* 3254 * try to push data from one node into the next node right in the 3255 * tree. 3256 * 3257 * returns 0 if some ptrs were pushed, < 0 if there was some horrible 3258 * error, and > 0 if there was no room in the right hand block. 3259 * 3260 * this will only push up to 1/2 the contents of the left node over 3261 */ 3262 static int balance_node_right(struct btrfs_trans_handle *trans, 3263 struct btrfs_fs_info *fs_info, 3264 struct extent_buffer *dst, 3265 struct extent_buffer *src) 3266 { 3267 int push_items = 0; 3268 int max_push; 3269 int src_nritems; 3270 int dst_nritems; 3271 int ret = 0; 3272 3273 WARN_ON(btrfs_header_generation(src) != trans->transid); 3274 WARN_ON(btrfs_header_generation(dst) != trans->transid); 3275 3276 src_nritems = btrfs_header_nritems(src); 3277 dst_nritems = btrfs_header_nritems(dst); 3278 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems; 3279 if (push_items <= 0) 3280 return 1; 3281 3282 if (src_nritems < 4) 3283 return 1; 3284 3285 max_push = src_nritems / 2 + 1; 3286 /* don't try to empty the node */ 3287 if (max_push >= src_nritems) 3288 return 1; 3289 3290 if (max_push < push_items) 3291 push_items = max_push; 3292 3293 ret = tree_mod_log_insert_move(dst, push_items, 0, dst_nritems); 3294 BUG_ON(ret < 0); 3295 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items), 3296 btrfs_node_key_ptr_offset(0), 3297 (dst_nritems) * 3298 sizeof(struct btrfs_key_ptr)); 3299 3300 ret = tree_mod_log_eb_copy(fs_info, dst, src, 0, 3301 src_nritems - push_items, push_items); 3302 if (ret) { 3303 btrfs_abort_transaction(trans, ret); 3304 return ret; 3305 } 3306 copy_extent_buffer(dst, src, 3307 btrfs_node_key_ptr_offset(0), 3308 btrfs_node_key_ptr_offset(src_nritems - push_items), 3309 push_items * sizeof(struct btrfs_key_ptr)); 3310 3311 btrfs_set_header_nritems(src, src_nritems - push_items); 3312 btrfs_set_header_nritems(dst, dst_nritems + push_items); 3313 3314 btrfs_mark_buffer_dirty(src); 3315 btrfs_mark_buffer_dirty(dst); 3316 3317 return ret; 3318 } 3319 3320 /* 3321 * helper function to insert a new root level in the tree. 3322 * A new node is allocated, and a single item is inserted to 3323 * point to the existing root 3324 * 3325 * returns zero on success or < 0 on failure. 3326 */ 3327 static noinline int insert_new_root(struct btrfs_trans_handle *trans, 3328 struct btrfs_root *root, 3329 struct btrfs_path *path, int level) 3330 { 3331 struct btrfs_fs_info *fs_info = root->fs_info; 3332 u64 lower_gen; 3333 struct extent_buffer *lower; 3334 struct extent_buffer *c; 3335 struct extent_buffer *old; 3336 struct btrfs_disk_key lower_key; 3337 int ret; 3338 3339 BUG_ON(path->nodes[level]); 3340 BUG_ON(path->nodes[level-1] != root->node); 3341 3342 lower = path->nodes[level-1]; 3343 if (level == 1) 3344 btrfs_item_key(lower, &lower_key, 0); 3345 else 3346 btrfs_node_key(lower, &lower_key, 0); 3347 3348 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid, 3349 &lower_key, level, root->node->start, 0); 3350 if (IS_ERR(c)) 3351 return PTR_ERR(c); 3352 3353 root_add_used(root, fs_info->nodesize); 3354 3355 btrfs_set_header_nritems(c, 1); 3356 btrfs_set_node_key(c, &lower_key, 0); 3357 btrfs_set_node_blockptr(c, 0, lower->start); 3358 lower_gen = btrfs_header_generation(lower); 3359 WARN_ON(lower_gen != trans->transid); 3360 3361 btrfs_set_node_ptr_generation(c, 0, lower_gen); 3362 3363 btrfs_mark_buffer_dirty(c); 3364 3365 old = root->node; 3366 ret = tree_mod_log_insert_root(root->node, c, 0); 3367 BUG_ON(ret < 0); 3368 rcu_assign_pointer(root->node, c); 3369 3370 /* the super has an extra ref to root->node */ 3371 free_extent_buffer(old); 3372 3373 add_root_to_dirty_list(root); 3374 extent_buffer_get(c); 3375 path->nodes[level] = c; 3376 path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING; 3377 path->slots[level] = 0; 3378 return 0; 3379 } 3380 3381 /* 3382 * worker function to insert a single pointer in a node. 3383 * the node should have enough room for the pointer already 3384 * 3385 * slot and level indicate where you want the key to go, and 3386 * blocknr is the block the key points to. 3387 */ 3388 static void insert_ptr(struct btrfs_trans_handle *trans, 3389 struct btrfs_fs_info *fs_info, struct btrfs_path *path, 3390 struct btrfs_disk_key *key, u64 bytenr, 3391 int slot, int level) 3392 { 3393 struct extent_buffer *lower; 3394 int nritems; 3395 int ret; 3396 3397 BUG_ON(!path->nodes[level]); 3398 btrfs_assert_tree_locked(path->nodes[level]); 3399 lower = path->nodes[level]; 3400 nritems = btrfs_header_nritems(lower); 3401 BUG_ON(slot > nritems); 3402 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(fs_info)); 3403 if (slot != nritems) { 3404 if (level) { 3405 ret = tree_mod_log_insert_move(lower, slot + 1, slot, 3406 nritems - slot); 3407 BUG_ON(ret < 0); 3408 } 3409 memmove_extent_buffer(lower, 3410 btrfs_node_key_ptr_offset(slot + 1), 3411 btrfs_node_key_ptr_offset(slot), 3412 (nritems - slot) * sizeof(struct btrfs_key_ptr)); 3413 } 3414 if (level) { 3415 ret = tree_mod_log_insert_key(lower, slot, MOD_LOG_KEY_ADD, 3416 GFP_NOFS); 3417 BUG_ON(ret < 0); 3418 } 3419 btrfs_set_node_key(lower, key, slot); 3420 btrfs_set_node_blockptr(lower, slot, bytenr); 3421 WARN_ON(trans->transid == 0); 3422 btrfs_set_node_ptr_generation(lower, slot, trans->transid); 3423 btrfs_set_header_nritems(lower, nritems + 1); 3424 btrfs_mark_buffer_dirty(lower); 3425 } 3426 3427 /* 3428 * split the node at the specified level in path in two. 3429 * The path is corrected to point to the appropriate node after the split 3430 * 3431 * Before splitting this tries to make some room in the node by pushing 3432 * left and right, if either one works, it returns right away. 3433 * 3434 * returns 0 on success and < 0 on failure 3435 */ 3436 static noinline int split_node(struct btrfs_trans_handle *trans, 3437 struct btrfs_root *root, 3438 struct btrfs_path *path, int level) 3439 { 3440 struct btrfs_fs_info *fs_info = root->fs_info; 3441 struct extent_buffer *c; 3442 struct extent_buffer *split; 3443 struct btrfs_disk_key disk_key; 3444 int mid; 3445 int ret; 3446 u32 c_nritems; 3447 3448 c = path->nodes[level]; 3449 WARN_ON(btrfs_header_generation(c) != trans->transid); 3450 if (c == root->node) { 3451 /* 3452 * trying to split the root, lets make a new one 3453 * 3454 * tree mod log: We don't log_removal old root in 3455 * insert_new_root, because that root buffer will be kept as a 3456 * normal node. We are going to log removal of half of the 3457 * elements below with tree_mod_log_eb_copy. We're holding a 3458 * tree lock on the buffer, which is why we cannot race with 3459 * other tree_mod_log users. 3460 */ 3461 ret = insert_new_root(trans, root, path, level + 1); 3462 if (ret) 3463 return ret; 3464 } else { 3465 ret = push_nodes_for_insert(trans, root, path, level); 3466 c = path->nodes[level]; 3467 if (!ret && btrfs_header_nritems(c) < 3468 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) 3469 return 0; 3470 if (ret < 0) 3471 return ret; 3472 } 3473 3474 c_nritems = btrfs_header_nritems(c); 3475 mid = (c_nritems + 1) / 2; 3476 btrfs_node_key(c, &disk_key, mid); 3477 3478 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid, 3479 &disk_key, level, c->start, 0); 3480 if (IS_ERR(split)) 3481 return PTR_ERR(split); 3482 3483 root_add_used(root, fs_info->nodesize); 3484 ASSERT(btrfs_header_level(c) == level); 3485 3486 ret = tree_mod_log_eb_copy(fs_info, split, c, 0, mid, c_nritems - mid); 3487 if (ret) { 3488 btrfs_abort_transaction(trans, ret); 3489 return ret; 3490 } 3491 copy_extent_buffer(split, c, 3492 btrfs_node_key_ptr_offset(0), 3493 btrfs_node_key_ptr_offset(mid), 3494 (c_nritems - mid) * sizeof(struct btrfs_key_ptr)); 3495 btrfs_set_header_nritems(split, c_nritems - mid); 3496 btrfs_set_header_nritems(c, mid); 3497 ret = 0; 3498 3499 btrfs_mark_buffer_dirty(c); 3500 btrfs_mark_buffer_dirty(split); 3501 3502 insert_ptr(trans, fs_info, path, &disk_key, split->start, 3503 path->slots[level + 1] + 1, level + 1); 3504 3505 if (path->slots[level] >= mid) { 3506 path->slots[level] -= mid; 3507 btrfs_tree_unlock(c); 3508 free_extent_buffer(c); 3509 path->nodes[level] = split; 3510 path->slots[level + 1] += 1; 3511 } else { 3512 btrfs_tree_unlock(split); 3513 free_extent_buffer(split); 3514 } 3515 return ret; 3516 } 3517 3518 /* 3519 * how many bytes are required to store the items in a leaf. start 3520 * and nr indicate which items in the leaf to check. This totals up the 3521 * space used both by the item structs and the item data 3522 */ 3523 static int leaf_space_used(struct extent_buffer *l, int start, int nr) 3524 { 3525 struct btrfs_item *start_item; 3526 struct btrfs_item *end_item; 3527 struct btrfs_map_token token; 3528 int data_len; 3529 int nritems = btrfs_header_nritems(l); 3530 int end = min(nritems, start + nr) - 1; 3531 3532 if (!nr) 3533 return 0; 3534 btrfs_init_map_token(&token); 3535 start_item = btrfs_item_nr(start); 3536 end_item = btrfs_item_nr(end); 3537 data_len = btrfs_token_item_offset(l, start_item, &token) + 3538 btrfs_token_item_size(l, start_item, &token); 3539 data_len = data_len - btrfs_token_item_offset(l, end_item, &token); 3540 data_len += sizeof(struct btrfs_item) * nr; 3541 WARN_ON(data_len < 0); 3542 return data_len; 3543 } 3544 3545 /* 3546 * The space between the end of the leaf items and 3547 * the start of the leaf data. IOW, how much room 3548 * the leaf has left for both items and data 3549 */ 3550 noinline int btrfs_leaf_free_space(struct btrfs_fs_info *fs_info, 3551 struct extent_buffer *leaf) 3552 { 3553 int nritems = btrfs_header_nritems(leaf); 3554 int ret; 3555 3556 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems); 3557 if (ret < 0) { 3558 btrfs_crit(fs_info, 3559 "leaf free space ret %d, leaf data size %lu, used %d nritems %d", 3560 ret, 3561 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info), 3562 leaf_space_used(leaf, 0, nritems), nritems); 3563 } 3564 return ret; 3565 } 3566 3567 /* 3568 * min slot controls the lowest index we're willing to push to the 3569 * right. We'll push up to and including min_slot, but no lower 3570 */ 3571 static noinline int __push_leaf_right(struct btrfs_fs_info *fs_info, 3572 struct btrfs_path *path, 3573 int data_size, int empty, 3574 struct extent_buffer *right, 3575 int free_space, u32 left_nritems, 3576 u32 min_slot) 3577 { 3578 struct extent_buffer *left = path->nodes[0]; 3579 struct extent_buffer *upper = path->nodes[1]; 3580 struct btrfs_map_token token; 3581 struct btrfs_disk_key disk_key; 3582 int slot; 3583 u32 i; 3584 int push_space = 0; 3585 int push_items = 0; 3586 struct btrfs_item *item; 3587 u32 nr; 3588 u32 right_nritems; 3589 u32 data_end; 3590 u32 this_item_size; 3591 3592 btrfs_init_map_token(&token); 3593 3594 if (empty) 3595 nr = 0; 3596 else 3597 nr = max_t(u32, 1, min_slot); 3598 3599 if (path->slots[0] >= left_nritems) 3600 push_space += data_size; 3601 3602 slot = path->slots[1]; 3603 i = left_nritems - 1; 3604 while (i >= nr) { 3605 item = btrfs_item_nr(i); 3606 3607 if (!empty && push_items > 0) { 3608 if (path->slots[0] > i) 3609 break; 3610 if (path->slots[0] == i) { 3611 int space = btrfs_leaf_free_space(fs_info, left); 3612 if (space + push_space * 2 > free_space) 3613 break; 3614 } 3615 } 3616 3617 if (path->slots[0] == i) 3618 push_space += data_size; 3619 3620 this_item_size = btrfs_item_size(left, item); 3621 if (this_item_size + sizeof(*item) + push_space > free_space) 3622 break; 3623 3624 push_items++; 3625 push_space += this_item_size + sizeof(*item); 3626 if (i == 0) 3627 break; 3628 i--; 3629 } 3630 3631 if (push_items == 0) 3632 goto out_unlock; 3633 3634 WARN_ON(!empty && push_items == left_nritems); 3635 3636 /* push left to right */ 3637 right_nritems = btrfs_header_nritems(right); 3638 3639 push_space = btrfs_item_end_nr(left, left_nritems - push_items); 3640 push_space -= leaf_data_end(fs_info, left); 3641 3642 /* make room in the right data area */ 3643 data_end = leaf_data_end(fs_info, right); 3644 memmove_extent_buffer(right, 3645 BTRFS_LEAF_DATA_OFFSET + data_end - push_space, 3646 BTRFS_LEAF_DATA_OFFSET + data_end, 3647 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end); 3648 3649 /* copy from the left data area */ 3650 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET + 3651 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space, 3652 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(fs_info, left), 3653 push_space); 3654 3655 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items), 3656 btrfs_item_nr_offset(0), 3657 right_nritems * sizeof(struct btrfs_item)); 3658 3659 /* copy the items from left to right */ 3660 copy_extent_buffer(right, left, btrfs_item_nr_offset(0), 3661 btrfs_item_nr_offset(left_nritems - push_items), 3662 push_items * sizeof(struct btrfs_item)); 3663 3664 /* update the item pointers */ 3665 right_nritems += push_items; 3666 btrfs_set_header_nritems(right, right_nritems); 3667 push_space = BTRFS_LEAF_DATA_SIZE(fs_info); 3668 for (i = 0; i < right_nritems; i++) { 3669 item = btrfs_item_nr(i); 3670 push_space -= btrfs_token_item_size(right, item, &token); 3671 btrfs_set_token_item_offset(right, item, push_space, &token); 3672 } 3673 3674 left_nritems -= push_items; 3675 btrfs_set_header_nritems(left, left_nritems); 3676 3677 if (left_nritems) 3678 btrfs_mark_buffer_dirty(left); 3679 else 3680 clean_tree_block(fs_info, left); 3681 3682 btrfs_mark_buffer_dirty(right); 3683 3684 btrfs_item_key(right, &disk_key, 0); 3685 btrfs_set_node_key(upper, &disk_key, slot + 1); 3686 btrfs_mark_buffer_dirty(upper); 3687 3688 /* then fixup the leaf pointer in the path */ 3689 if (path->slots[0] >= left_nritems) { 3690 path->slots[0] -= left_nritems; 3691 if (btrfs_header_nritems(path->nodes[0]) == 0) 3692 clean_tree_block(fs_info, path->nodes[0]); 3693 btrfs_tree_unlock(path->nodes[0]); 3694 free_extent_buffer(path->nodes[0]); 3695 path->nodes[0] = right; 3696 path->slots[1] += 1; 3697 } else { 3698 btrfs_tree_unlock(right); 3699 free_extent_buffer(right); 3700 } 3701 return 0; 3702 3703 out_unlock: 3704 btrfs_tree_unlock(right); 3705 free_extent_buffer(right); 3706 return 1; 3707 } 3708 3709 /* 3710 * push some data in the path leaf to the right, trying to free up at 3711 * least data_size bytes. returns zero if the push worked, nonzero otherwise 3712 * 3713 * returns 1 if the push failed because the other node didn't have enough 3714 * room, 0 if everything worked out and < 0 if there were major errors. 3715 * 3716 * this will push starting from min_slot to the end of the leaf. It won't 3717 * push any slot lower than min_slot 3718 */ 3719 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root 3720 *root, struct btrfs_path *path, 3721 int min_data_size, int data_size, 3722 int empty, u32 min_slot) 3723 { 3724 struct btrfs_fs_info *fs_info = root->fs_info; 3725 struct extent_buffer *left = path->nodes[0]; 3726 struct extent_buffer *right; 3727 struct extent_buffer *upper; 3728 int slot; 3729 int free_space; 3730 u32 left_nritems; 3731 int ret; 3732 3733 if (!path->nodes[1]) 3734 return 1; 3735 3736 slot = path->slots[1]; 3737 upper = path->nodes[1]; 3738 if (slot >= btrfs_header_nritems(upper) - 1) 3739 return 1; 3740 3741 btrfs_assert_tree_locked(path->nodes[1]); 3742 3743 right = read_node_slot(fs_info, upper, slot + 1); 3744 /* 3745 * slot + 1 is not valid or we fail to read the right node, 3746 * no big deal, just return. 3747 */ 3748 if (IS_ERR(right)) 3749 return 1; 3750 3751 btrfs_tree_lock(right); 3752 btrfs_set_lock_blocking(right); 3753 3754 free_space = btrfs_leaf_free_space(fs_info, right); 3755 if (free_space < data_size) 3756 goto out_unlock; 3757 3758 /* cow and double check */ 3759 ret = btrfs_cow_block(trans, root, right, upper, 3760 slot + 1, &right); 3761 if (ret) 3762 goto out_unlock; 3763 3764 free_space = btrfs_leaf_free_space(fs_info, right); 3765 if (free_space < data_size) 3766 goto out_unlock; 3767 3768 left_nritems = btrfs_header_nritems(left); 3769 if (left_nritems == 0) 3770 goto out_unlock; 3771 3772 if (path->slots[0] == left_nritems && !empty) { 3773 /* Key greater than all keys in the leaf, right neighbor has 3774 * enough room for it and we're not emptying our leaf to delete 3775 * it, therefore use right neighbor to insert the new item and 3776 * no need to touch/dirty our left leaf. */ 3777 btrfs_tree_unlock(left); 3778 free_extent_buffer(left); 3779 path->nodes[0] = right; 3780 path->slots[0] = 0; 3781 path->slots[1]++; 3782 return 0; 3783 } 3784 3785 return __push_leaf_right(fs_info, path, min_data_size, empty, 3786 right, free_space, left_nritems, min_slot); 3787 out_unlock: 3788 btrfs_tree_unlock(right); 3789 free_extent_buffer(right); 3790 return 1; 3791 } 3792 3793 /* 3794 * push some data in the path leaf to the left, trying to free up at 3795 * least data_size bytes. returns zero if the push worked, nonzero otherwise 3796 * 3797 * max_slot can put a limit on how far into the leaf we'll push items. The 3798 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the 3799 * items 3800 */ 3801 static noinline int __push_leaf_left(struct btrfs_fs_info *fs_info, 3802 struct btrfs_path *path, int data_size, 3803 int empty, struct extent_buffer *left, 3804 int free_space, u32 right_nritems, 3805 u32 max_slot) 3806 { 3807 struct btrfs_disk_key disk_key; 3808 struct extent_buffer *right = path->nodes[0]; 3809 int i; 3810 int push_space = 0; 3811 int push_items = 0; 3812 struct btrfs_item *item; 3813 u32 old_left_nritems; 3814 u32 nr; 3815 int ret = 0; 3816 u32 this_item_size; 3817 u32 old_left_item_size; 3818 struct btrfs_map_token token; 3819 3820 btrfs_init_map_token(&token); 3821 3822 if (empty) 3823 nr = min(right_nritems, max_slot); 3824 else 3825 nr = min(right_nritems - 1, max_slot); 3826 3827 for (i = 0; i < nr; i++) { 3828 item = btrfs_item_nr(i); 3829 3830 if (!empty && push_items > 0) { 3831 if (path->slots[0] < i) 3832 break; 3833 if (path->slots[0] == i) { 3834 int space = btrfs_leaf_free_space(fs_info, right); 3835 if (space + push_space * 2 > free_space) 3836 break; 3837 } 3838 } 3839 3840 if (path->slots[0] == i) 3841 push_space += data_size; 3842 3843 this_item_size = btrfs_item_size(right, item); 3844 if (this_item_size + sizeof(*item) + push_space > free_space) 3845 break; 3846 3847 push_items++; 3848 push_space += this_item_size + sizeof(*item); 3849 } 3850 3851 if (push_items == 0) { 3852 ret = 1; 3853 goto out; 3854 } 3855 WARN_ON(!empty && push_items == btrfs_header_nritems(right)); 3856 3857 /* push data from right to left */ 3858 copy_extent_buffer(left, right, 3859 btrfs_item_nr_offset(btrfs_header_nritems(left)), 3860 btrfs_item_nr_offset(0), 3861 push_items * sizeof(struct btrfs_item)); 3862 3863 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) - 3864 btrfs_item_offset_nr(right, push_items - 1); 3865 3866 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET + 3867 leaf_data_end(fs_info, left) - push_space, 3868 BTRFS_LEAF_DATA_OFFSET + 3869 btrfs_item_offset_nr(right, push_items - 1), 3870 push_space); 3871 old_left_nritems = btrfs_header_nritems(left); 3872 BUG_ON(old_left_nritems <= 0); 3873 3874 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1); 3875 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) { 3876 u32 ioff; 3877 3878 item = btrfs_item_nr(i); 3879 3880 ioff = btrfs_token_item_offset(left, item, &token); 3881 btrfs_set_token_item_offset(left, item, 3882 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size), 3883 &token); 3884 } 3885 btrfs_set_header_nritems(left, old_left_nritems + push_items); 3886 3887 /* fixup right node */ 3888 if (push_items > right_nritems) 3889 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items, 3890 right_nritems); 3891 3892 if (push_items < right_nritems) { 3893 push_space = btrfs_item_offset_nr(right, push_items - 1) - 3894 leaf_data_end(fs_info, right); 3895 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET + 3896 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space, 3897 BTRFS_LEAF_DATA_OFFSET + 3898 leaf_data_end(fs_info, right), push_space); 3899 3900 memmove_extent_buffer(right, btrfs_item_nr_offset(0), 3901 btrfs_item_nr_offset(push_items), 3902 (btrfs_header_nritems(right) - push_items) * 3903 sizeof(struct btrfs_item)); 3904 } 3905 right_nritems -= push_items; 3906 btrfs_set_header_nritems(right, right_nritems); 3907 push_space = BTRFS_LEAF_DATA_SIZE(fs_info); 3908 for (i = 0; i < right_nritems; i++) { 3909 item = btrfs_item_nr(i); 3910 3911 push_space = push_space - btrfs_token_item_size(right, 3912 item, &token); 3913 btrfs_set_token_item_offset(right, item, push_space, &token); 3914 } 3915 3916 btrfs_mark_buffer_dirty(left); 3917 if (right_nritems) 3918 btrfs_mark_buffer_dirty(right); 3919 else 3920 clean_tree_block(fs_info, right); 3921 3922 btrfs_item_key(right, &disk_key, 0); 3923 fixup_low_keys(path, &disk_key, 1); 3924 3925 /* then fixup the leaf pointer in the path */ 3926 if (path->slots[0] < push_items) { 3927 path->slots[0] += old_left_nritems; 3928 btrfs_tree_unlock(path->nodes[0]); 3929 free_extent_buffer(path->nodes[0]); 3930 path->nodes[0] = left; 3931 path->slots[1] -= 1; 3932 } else { 3933 btrfs_tree_unlock(left); 3934 free_extent_buffer(left); 3935 path->slots[0] -= push_items; 3936 } 3937 BUG_ON(path->slots[0] < 0); 3938 return ret; 3939 out: 3940 btrfs_tree_unlock(left); 3941 free_extent_buffer(left); 3942 return ret; 3943 } 3944 3945 /* 3946 * push some data in the path leaf to the left, trying to free up at 3947 * least data_size bytes. returns zero if the push worked, nonzero otherwise 3948 * 3949 * max_slot can put a limit on how far into the leaf we'll push items. The 3950 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the 3951 * items 3952 */ 3953 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root 3954 *root, struct btrfs_path *path, int min_data_size, 3955 int data_size, int empty, u32 max_slot) 3956 { 3957 struct btrfs_fs_info *fs_info = root->fs_info; 3958 struct extent_buffer *right = path->nodes[0]; 3959 struct extent_buffer *left; 3960 int slot; 3961 int free_space; 3962 u32 right_nritems; 3963 int ret = 0; 3964 3965 slot = path->slots[1]; 3966 if (slot == 0) 3967 return 1; 3968 if (!path->nodes[1]) 3969 return 1; 3970 3971 right_nritems = btrfs_header_nritems(right); 3972 if (right_nritems == 0) 3973 return 1; 3974 3975 btrfs_assert_tree_locked(path->nodes[1]); 3976 3977 left = read_node_slot(fs_info, path->nodes[1], slot - 1); 3978 /* 3979 * slot - 1 is not valid or we fail to read the left node, 3980 * no big deal, just return. 3981 */ 3982 if (IS_ERR(left)) 3983 return 1; 3984 3985 btrfs_tree_lock(left); 3986 btrfs_set_lock_blocking(left); 3987 3988 free_space = btrfs_leaf_free_space(fs_info, left); 3989 if (free_space < data_size) { 3990 ret = 1; 3991 goto out; 3992 } 3993 3994 /* cow and double check */ 3995 ret = btrfs_cow_block(trans, root, left, 3996 path->nodes[1], slot - 1, &left); 3997 if (ret) { 3998 /* we hit -ENOSPC, but it isn't fatal here */ 3999 if (ret == -ENOSPC) 4000 ret = 1; 4001 goto out; 4002 } 4003 4004 free_space = btrfs_leaf_free_space(fs_info, left); 4005 if (free_space < data_size) { 4006 ret = 1; 4007 goto out; 4008 } 4009 4010 return __push_leaf_left(fs_info, path, min_data_size, 4011 empty, left, free_space, right_nritems, 4012 max_slot); 4013 out: 4014 btrfs_tree_unlock(left); 4015 free_extent_buffer(left); 4016 return ret; 4017 } 4018 4019 /* 4020 * split the path's leaf in two, making sure there is at least data_size 4021 * available for the resulting leaf level of the path. 4022 */ 4023 static noinline void copy_for_split(struct btrfs_trans_handle *trans, 4024 struct btrfs_fs_info *fs_info, 4025 struct btrfs_path *path, 4026 struct extent_buffer *l, 4027 struct extent_buffer *right, 4028 int slot, int mid, int nritems) 4029 { 4030 int data_copy_size; 4031 int rt_data_off; 4032 int i; 4033 struct btrfs_disk_key disk_key; 4034 struct btrfs_map_token token; 4035 4036 btrfs_init_map_token(&token); 4037 4038 nritems = nritems - mid; 4039 btrfs_set_header_nritems(right, nritems); 4040 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(fs_info, l); 4041 4042 copy_extent_buffer(right, l, btrfs_item_nr_offset(0), 4043 btrfs_item_nr_offset(mid), 4044 nritems * sizeof(struct btrfs_item)); 4045 4046 copy_extent_buffer(right, l, 4047 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) - 4048 data_copy_size, BTRFS_LEAF_DATA_OFFSET + 4049 leaf_data_end(fs_info, l), data_copy_size); 4050 4051 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid); 4052 4053 for (i = 0; i < nritems; i++) { 4054 struct btrfs_item *item = btrfs_item_nr(i); 4055 u32 ioff; 4056 4057 ioff = btrfs_token_item_offset(right, item, &token); 4058 btrfs_set_token_item_offset(right, item, 4059 ioff + rt_data_off, &token); 4060 } 4061 4062 btrfs_set_header_nritems(l, mid); 4063 btrfs_item_key(right, &disk_key, 0); 4064 insert_ptr(trans, fs_info, path, &disk_key, right->start, 4065 path->slots[1] + 1, 1); 4066 4067 btrfs_mark_buffer_dirty(right); 4068 btrfs_mark_buffer_dirty(l); 4069 BUG_ON(path->slots[0] != slot); 4070 4071 if (mid <= slot) { 4072 btrfs_tree_unlock(path->nodes[0]); 4073 free_extent_buffer(path->nodes[0]); 4074 path->nodes[0] = right; 4075 path->slots[0] -= mid; 4076 path->slots[1] += 1; 4077 } else { 4078 btrfs_tree_unlock(right); 4079 free_extent_buffer(right); 4080 } 4081 4082 BUG_ON(path->slots[0] < 0); 4083 } 4084 4085 /* 4086 * double splits happen when we need to insert a big item in the middle 4087 * of a leaf. A double split can leave us with 3 mostly empty leaves: 4088 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ] 4089 * A B C 4090 * 4091 * We avoid this by trying to push the items on either side of our target 4092 * into the adjacent leaves. If all goes well we can avoid the double split 4093 * completely. 4094 */ 4095 static noinline int push_for_double_split(struct btrfs_trans_handle *trans, 4096 struct btrfs_root *root, 4097 struct btrfs_path *path, 4098 int data_size) 4099 { 4100 struct btrfs_fs_info *fs_info = root->fs_info; 4101 int ret; 4102 int progress = 0; 4103 int slot; 4104 u32 nritems; 4105 int space_needed = data_size; 4106 4107 slot = path->slots[0]; 4108 if (slot < btrfs_header_nritems(path->nodes[0])) 4109 space_needed -= btrfs_leaf_free_space(fs_info, path->nodes[0]); 4110 4111 /* 4112 * try to push all the items after our slot into the 4113 * right leaf 4114 */ 4115 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot); 4116 if (ret < 0) 4117 return ret; 4118 4119 if (ret == 0) 4120 progress++; 4121 4122 nritems = btrfs_header_nritems(path->nodes[0]); 4123 /* 4124 * our goal is to get our slot at the start or end of a leaf. If 4125 * we've done so we're done 4126 */ 4127 if (path->slots[0] == 0 || path->slots[0] == nritems) 4128 return 0; 4129 4130 if (btrfs_leaf_free_space(fs_info, path->nodes[0]) >= data_size) 4131 return 0; 4132 4133 /* try to push all the items before our slot into the next leaf */ 4134 slot = path->slots[0]; 4135 space_needed = data_size; 4136 if (slot > 0) 4137 space_needed -= btrfs_leaf_free_space(fs_info, path->nodes[0]); 4138 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot); 4139 if (ret < 0) 4140 return ret; 4141 4142 if (ret == 0) 4143 progress++; 4144 4145 if (progress) 4146 return 0; 4147 return 1; 4148 } 4149 4150 /* 4151 * split the path's leaf in two, making sure there is at least data_size 4152 * available for the resulting leaf level of the path. 4153 * 4154 * returns 0 if all went well and < 0 on failure. 4155 */ 4156 static noinline int split_leaf(struct btrfs_trans_handle *trans, 4157 struct btrfs_root *root, 4158 const struct btrfs_key *ins_key, 4159 struct btrfs_path *path, int data_size, 4160 int extend) 4161 { 4162 struct btrfs_disk_key disk_key; 4163 struct extent_buffer *l; 4164 u32 nritems; 4165 int mid; 4166 int slot; 4167 struct extent_buffer *right; 4168 struct btrfs_fs_info *fs_info = root->fs_info; 4169 int ret = 0; 4170 int wret; 4171 int split; 4172 int num_doubles = 0; 4173 int tried_avoid_double = 0; 4174 4175 l = path->nodes[0]; 4176 slot = path->slots[0]; 4177 if (extend && data_size + btrfs_item_size_nr(l, slot) + 4178 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info)) 4179 return -EOVERFLOW; 4180 4181 /* first try to make some room by pushing left and right */ 4182 if (data_size && path->nodes[1]) { 4183 int space_needed = data_size; 4184 4185 if (slot < btrfs_header_nritems(l)) 4186 space_needed -= btrfs_leaf_free_space(fs_info, l); 4187 4188 wret = push_leaf_right(trans, root, path, space_needed, 4189 space_needed, 0, 0); 4190 if (wret < 0) 4191 return wret; 4192 if (wret) { 4193 space_needed = data_size; 4194 if (slot > 0) 4195 space_needed -= btrfs_leaf_free_space(fs_info, 4196 l); 4197 wret = push_leaf_left(trans, root, path, space_needed, 4198 space_needed, 0, (u32)-1); 4199 if (wret < 0) 4200 return wret; 4201 } 4202 l = path->nodes[0]; 4203 4204 /* did the pushes work? */ 4205 if (btrfs_leaf_free_space(fs_info, l) >= data_size) 4206 return 0; 4207 } 4208 4209 if (!path->nodes[1]) { 4210 ret = insert_new_root(trans, root, path, 1); 4211 if (ret) 4212 return ret; 4213 } 4214 again: 4215 split = 1; 4216 l = path->nodes[0]; 4217 slot = path->slots[0]; 4218 nritems = btrfs_header_nritems(l); 4219 mid = (nritems + 1) / 2; 4220 4221 if (mid <= slot) { 4222 if (nritems == 1 || 4223 leaf_space_used(l, mid, nritems - mid) + data_size > 4224 BTRFS_LEAF_DATA_SIZE(fs_info)) { 4225 if (slot >= nritems) { 4226 split = 0; 4227 } else { 4228 mid = slot; 4229 if (mid != nritems && 4230 leaf_space_used(l, mid, nritems - mid) + 4231 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) { 4232 if (data_size && !tried_avoid_double) 4233 goto push_for_double; 4234 split = 2; 4235 } 4236 } 4237 } 4238 } else { 4239 if (leaf_space_used(l, 0, mid) + data_size > 4240 BTRFS_LEAF_DATA_SIZE(fs_info)) { 4241 if (!extend && data_size && slot == 0) { 4242 split = 0; 4243 } else if ((extend || !data_size) && slot == 0) { 4244 mid = 1; 4245 } else { 4246 mid = slot; 4247 if (mid != nritems && 4248 leaf_space_used(l, mid, nritems - mid) + 4249 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) { 4250 if (data_size && !tried_avoid_double) 4251 goto push_for_double; 4252 split = 2; 4253 } 4254 } 4255 } 4256 } 4257 4258 if (split == 0) 4259 btrfs_cpu_key_to_disk(&disk_key, ins_key); 4260 else 4261 btrfs_item_key(l, &disk_key, mid); 4262 4263 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid, 4264 &disk_key, 0, l->start, 0); 4265 if (IS_ERR(right)) 4266 return PTR_ERR(right); 4267 4268 root_add_used(root, fs_info->nodesize); 4269 4270 if (split == 0) { 4271 if (mid <= slot) { 4272 btrfs_set_header_nritems(right, 0); 4273 insert_ptr(trans, fs_info, path, &disk_key, 4274 right->start, path->slots[1] + 1, 1); 4275 btrfs_tree_unlock(path->nodes[0]); 4276 free_extent_buffer(path->nodes[0]); 4277 path->nodes[0] = right; 4278 path->slots[0] = 0; 4279 path->slots[1] += 1; 4280 } else { 4281 btrfs_set_header_nritems(right, 0); 4282 insert_ptr(trans, fs_info, path, &disk_key, 4283 right->start, path->slots[1], 1); 4284 btrfs_tree_unlock(path->nodes[0]); 4285 free_extent_buffer(path->nodes[0]); 4286 path->nodes[0] = right; 4287 path->slots[0] = 0; 4288 if (path->slots[1] == 0) 4289 fixup_low_keys(path, &disk_key, 1); 4290 } 4291 /* 4292 * We create a new leaf 'right' for the required ins_len and 4293 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying 4294 * the content of ins_len to 'right'. 4295 */ 4296 return ret; 4297 } 4298 4299 copy_for_split(trans, fs_info, path, l, right, slot, mid, nritems); 4300 4301 if (split == 2) { 4302 BUG_ON(num_doubles != 0); 4303 num_doubles++; 4304 goto again; 4305 } 4306 4307 return 0; 4308 4309 push_for_double: 4310 push_for_double_split(trans, root, path, data_size); 4311 tried_avoid_double = 1; 4312 if (btrfs_leaf_free_space(fs_info, path->nodes[0]) >= data_size) 4313 return 0; 4314 goto again; 4315 } 4316 4317 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans, 4318 struct btrfs_root *root, 4319 struct btrfs_path *path, int ins_len) 4320 { 4321 struct btrfs_fs_info *fs_info = root->fs_info; 4322 struct btrfs_key key; 4323 struct extent_buffer *leaf; 4324 struct btrfs_file_extent_item *fi; 4325 u64 extent_len = 0; 4326 u32 item_size; 4327 int ret; 4328 4329 leaf = path->nodes[0]; 4330 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); 4331 4332 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY && 4333 key.type != BTRFS_EXTENT_CSUM_KEY); 4334 4335 if (btrfs_leaf_free_space(fs_info, leaf) >= ins_len) 4336 return 0; 4337 4338 item_size = btrfs_item_size_nr(leaf, path->slots[0]); 4339 if (key.type == BTRFS_EXTENT_DATA_KEY) { 4340 fi = btrfs_item_ptr(leaf, path->slots[0], 4341 struct btrfs_file_extent_item); 4342 extent_len = btrfs_file_extent_num_bytes(leaf, fi); 4343 } 4344 btrfs_release_path(path); 4345 4346 path->keep_locks = 1; 4347 path->search_for_split = 1; 4348 ret = btrfs_search_slot(trans, root, &key, path, 0, 1); 4349 path->search_for_split = 0; 4350 if (ret > 0) 4351 ret = -EAGAIN; 4352 if (ret < 0) 4353 goto err; 4354 4355 ret = -EAGAIN; 4356 leaf = path->nodes[0]; 4357 /* if our item isn't there, return now */ 4358 if (item_size != btrfs_item_size_nr(leaf, path->slots[0])) 4359 goto err; 4360 4361 /* the leaf has changed, it now has room. return now */ 4362 if (btrfs_leaf_free_space(fs_info, path->nodes[0]) >= ins_len) 4363 goto err; 4364 4365 if (key.type == BTRFS_EXTENT_DATA_KEY) { 4366 fi = btrfs_item_ptr(leaf, path->slots[0], 4367 struct btrfs_file_extent_item); 4368 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi)) 4369 goto err; 4370 } 4371 4372 btrfs_set_path_blocking(path); 4373 ret = split_leaf(trans, root, &key, path, ins_len, 1); 4374 if (ret) 4375 goto err; 4376 4377 path->keep_locks = 0; 4378 btrfs_unlock_up_safe(path, 1); 4379 return 0; 4380 err: 4381 path->keep_locks = 0; 4382 return ret; 4383 } 4384 4385 static noinline int split_item(struct btrfs_fs_info *fs_info, 4386 struct btrfs_path *path, 4387 const struct btrfs_key *new_key, 4388 unsigned long split_offset) 4389 { 4390 struct extent_buffer *leaf; 4391 struct btrfs_item *item; 4392 struct btrfs_item *new_item; 4393 int slot; 4394 char *buf; 4395 u32 nritems; 4396 u32 item_size; 4397 u32 orig_offset; 4398 struct btrfs_disk_key disk_key; 4399 4400 leaf = path->nodes[0]; 4401 BUG_ON(btrfs_leaf_free_space(fs_info, leaf) < sizeof(struct btrfs_item)); 4402 4403 btrfs_set_path_blocking(path); 4404 4405 item = btrfs_item_nr(path->slots[0]); 4406 orig_offset = btrfs_item_offset(leaf, item); 4407 item_size = btrfs_item_size(leaf, item); 4408 4409 buf = kmalloc(item_size, GFP_NOFS); 4410 if (!buf) 4411 return -ENOMEM; 4412 4413 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, 4414 path->slots[0]), item_size); 4415 4416 slot = path->slots[0] + 1; 4417 nritems = btrfs_header_nritems(leaf); 4418 if (slot != nritems) { 4419 /* shift the items */ 4420 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1), 4421 btrfs_item_nr_offset(slot), 4422 (nritems - slot) * sizeof(struct btrfs_item)); 4423 } 4424 4425 btrfs_cpu_key_to_disk(&disk_key, new_key); 4426 btrfs_set_item_key(leaf, &disk_key, slot); 4427 4428 new_item = btrfs_item_nr(slot); 4429 4430 btrfs_set_item_offset(leaf, new_item, orig_offset); 4431 btrfs_set_item_size(leaf, new_item, item_size - split_offset); 4432 4433 btrfs_set_item_offset(leaf, item, 4434 orig_offset + item_size - split_offset); 4435 btrfs_set_item_size(leaf, item, split_offset); 4436 4437 btrfs_set_header_nritems(leaf, nritems + 1); 4438 4439 /* write the data for the start of the original item */ 4440 write_extent_buffer(leaf, buf, 4441 btrfs_item_ptr_offset(leaf, path->slots[0]), 4442 split_offset); 4443 4444 /* write the data for the new item */ 4445 write_extent_buffer(leaf, buf + split_offset, 4446 btrfs_item_ptr_offset(leaf, slot), 4447 item_size - split_offset); 4448 btrfs_mark_buffer_dirty(leaf); 4449 4450 BUG_ON(btrfs_leaf_free_space(fs_info, leaf) < 0); 4451 kfree(buf); 4452 return 0; 4453 } 4454 4455 /* 4456 * This function splits a single item into two items, 4457 * giving 'new_key' to the new item and splitting the 4458 * old one at split_offset (from the start of the item). 4459 * 4460 * The path may be released by this operation. After 4461 * the split, the path is pointing to the old item. The 4462 * new item is going to be in the same node as the old one. 4463 * 4464 * Note, the item being split must be smaller enough to live alone on 4465 * a tree block with room for one extra struct btrfs_item 4466 * 4467 * This allows us to split the item in place, keeping a lock on the 4468 * leaf the entire time. 4469 */ 4470 int btrfs_split_item(struct btrfs_trans_handle *trans, 4471 struct btrfs_root *root, 4472 struct btrfs_path *path, 4473 const struct btrfs_key *new_key, 4474 unsigned long split_offset) 4475 { 4476 int ret; 4477 ret = setup_leaf_for_split(trans, root, path, 4478 sizeof(struct btrfs_item)); 4479 if (ret) 4480 return ret; 4481 4482 ret = split_item(root->fs_info, path, new_key, split_offset); 4483 return ret; 4484 } 4485 4486 /* 4487 * This function duplicate a item, giving 'new_key' to the new item. 4488 * It guarantees both items live in the same tree leaf and the new item 4489 * is contiguous with the original item. 4490 * 4491 * This allows us to split file extent in place, keeping a lock on the 4492 * leaf the entire time. 4493 */ 4494 int btrfs_duplicate_item(struct btrfs_trans_handle *trans, 4495 struct btrfs_root *root, 4496 struct btrfs_path *path, 4497 const struct btrfs_key *new_key) 4498 { 4499 struct extent_buffer *leaf; 4500 int ret; 4501 u32 item_size; 4502 4503 leaf = path->nodes[0]; 4504 item_size = btrfs_item_size_nr(leaf, path->slots[0]); 4505 ret = setup_leaf_for_split(trans, root, path, 4506 item_size + sizeof(struct btrfs_item)); 4507 if (ret) 4508 return ret; 4509 4510 path->slots[0]++; 4511 setup_items_for_insert(root, path, new_key, &item_size, 4512 item_size, item_size + 4513 sizeof(struct btrfs_item), 1); 4514 leaf = path->nodes[0]; 4515 memcpy_extent_buffer(leaf, 4516 btrfs_item_ptr_offset(leaf, path->slots[0]), 4517 btrfs_item_ptr_offset(leaf, path->slots[0] - 1), 4518 item_size); 4519 return 0; 4520 } 4521 4522 /* 4523 * make the item pointed to by the path smaller. new_size indicates 4524 * how small to make it, and from_end tells us if we just chop bytes 4525 * off the end of the item or if we shift the item to chop bytes off 4526 * the front. 4527 */ 4528 void btrfs_truncate_item(struct btrfs_fs_info *fs_info, 4529 struct btrfs_path *path, u32 new_size, int from_end) 4530 { 4531 int slot; 4532 struct extent_buffer *leaf; 4533 struct btrfs_item *item; 4534 u32 nritems; 4535 unsigned int data_end; 4536 unsigned int old_data_start; 4537 unsigned int old_size; 4538 unsigned int size_diff; 4539 int i; 4540 struct btrfs_map_token token; 4541 4542 btrfs_init_map_token(&token); 4543 4544 leaf = path->nodes[0]; 4545 slot = path->slots[0]; 4546 4547 old_size = btrfs_item_size_nr(leaf, slot); 4548 if (old_size == new_size) 4549 return; 4550 4551 nritems = btrfs_header_nritems(leaf); 4552 data_end = leaf_data_end(fs_info, leaf); 4553 4554 old_data_start = btrfs_item_offset_nr(leaf, slot); 4555 4556 size_diff = old_size - new_size; 4557 4558 BUG_ON(slot < 0); 4559 BUG_ON(slot >= nritems); 4560 4561 /* 4562 * item0..itemN ... dataN.offset..dataN.size .. data0.size 4563 */ 4564 /* first correct the data pointers */ 4565 for (i = slot; i < nritems; i++) { 4566 u32 ioff; 4567 item = btrfs_item_nr(i); 4568 4569 ioff = btrfs_token_item_offset(leaf, item, &token); 4570 btrfs_set_token_item_offset(leaf, item, 4571 ioff + size_diff, &token); 4572 } 4573 4574 /* shift the data */ 4575 if (from_end) { 4576 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET + 4577 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET + 4578 data_end, old_data_start + new_size - data_end); 4579 } else { 4580 struct btrfs_disk_key disk_key; 4581 u64 offset; 4582 4583 btrfs_item_key(leaf, &disk_key, slot); 4584 4585 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) { 4586 unsigned long ptr; 4587 struct btrfs_file_extent_item *fi; 4588 4589 fi = btrfs_item_ptr(leaf, slot, 4590 struct btrfs_file_extent_item); 4591 fi = (struct btrfs_file_extent_item *)( 4592 (unsigned long)fi - size_diff); 4593 4594 if (btrfs_file_extent_type(leaf, fi) == 4595 BTRFS_FILE_EXTENT_INLINE) { 4596 ptr = btrfs_item_ptr_offset(leaf, slot); 4597 memmove_extent_buffer(leaf, ptr, 4598 (unsigned long)fi, 4599 BTRFS_FILE_EXTENT_INLINE_DATA_START); 4600 } 4601 } 4602 4603 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET + 4604 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET + 4605 data_end, old_data_start - data_end); 4606 4607 offset = btrfs_disk_key_offset(&disk_key); 4608 btrfs_set_disk_key_offset(&disk_key, offset + size_diff); 4609 btrfs_set_item_key(leaf, &disk_key, slot); 4610 if (slot == 0) 4611 fixup_low_keys(path, &disk_key, 1); 4612 } 4613 4614 item = btrfs_item_nr(slot); 4615 btrfs_set_item_size(leaf, item, new_size); 4616 btrfs_mark_buffer_dirty(leaf); 4617 4618 if (btrfs_leaf_free_space(fs_info, leaf) < 0) { 4619 btrfs_print_leaf(leaf); 4620 BUG(); 4621 } 4622 } 4623 4624 /* 4625 * make the item pointed to by the path bigger, data_size is the added size. 4626 */ 4627 void btrfs_extend_item(struct btrfs_fs_info *fs_info, struct btrfs_path *path, 4628 u32 data_size) 4629 { 4630 int slot; 4631 struct extent_buffer *leaf; 4632 struct btrfs_item *item; 4633 u32 nritems; 4634 unsigned int data_end; 4635 unsigned int old_data; 4636 unsigned int old_size; 4637 int i; 4638 struct btrfs_map_token token; 4639 4640 btrfs_init_map_token(&token); 4641 4642 leaf = path->nodes[0]; 4643 4644 nritems = btrfs_header_nritems(leaf); 4645 data_end = leaf_data_end(fs_info, leaf); 4646 4647 if (btrfs_leaf_free_space(fs_info, leaf) < data_size) { 4648 btrfs_print_leaf(leaf); 4649 BUG(); 4650 } 4651 slot = path->slots[0]; 4652 old_data = btrfs_item_end_nr(leaf, slot); 4653 4654 BUG_ON(slot < 0); 4655 if (slot >= nritems) { 4656 btrfs_print_leaf(leaf); 4657 btrfs_crit(fs_info, "slot %d too large, nritems %d", 4658 slot, nritems); 4659 BUG_ON(1); 4660 } 4661 4662 /* 4663 * item0..itemN ... dataN.offset..dataN.size .. data0.size 4664 */ 4665 /* first correct the data pointers */ 4666 for (i = slot; i < nritems; i++) { 4667 u32 ioff; 4668 item = btrfs_item_nr(i); 4669 4670 ioff = btrfs_token_item_offset(leaf, item, &token); 4671 btrfs_set_token_item_offset(leaf, item, 4672 ioff - data_size, &token); 4673 } 4674 4675 /* shift the data */ 4676 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET + 4677 data_end - data_size, BTRFS_LEAF_DATA_OFFSET + 4678 data_end, old_data - data_end); 4679 4680 data_end = old_data; 4681 old_size = btrfs_item_size_nr(leaf, slot); 4682 item = btrfs_item_nr(slot); 4683 btrfs_set_item_size(leaf, item, old_size + data_size); 4684 btrfs_mark_buffer_dirty(leaf); 4685 4686 if (btrfs_leaf_free_space(fs_info, leaf) < 0) { 4687 btrfs_print_leaf(leaf); 4688 BUG(); 4689 } 4690 } 4691 4692 /* 4693 * this is a helper for btrfs_insert_empty_items, the main goal here is 4694 * to save stack depth by doing the bulk of the work in a function 4695 * that doesn't call btrfs_search_slot 4696 */ 4697 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path, 4698 const struct btrfs_key *cpu_key, u32 *data_size, 4699 u32 total_data, u32 total_size, int nr) 4700 { 4701 struct btrfs_fs_info *fs_info = root->fs_info; 4702 struct btrfs_item *item; 4703 int i; 4704 u32 nritems; 4705 unsigned int data_end; 4706 struct btrfs_disk_key disk_key; 4707 struct extent_buffer *leaf; 4708 int slot; 4709 struct btrfs_map_token token; 4710 4711 if (path->slots[0] == 0) { 4712 btrfs_cpu_key_to_disk(&disk_key, cpu_key); 4713 fixup_low_keys(path, &disk_key, 1); 4714 } 4715 btrfs_unlock_up_safe(path, 1); 4716 4717 btrfs_init_map_token(&token); 4718 4719 leaf = path->nodes[0]; 4720 slot = path->slots[0]; 4721 4722 nritems = btrfs_header_nritems(leaf); 4723 data_end = leaf_data_end(fs_info, leaf); 4724 4725 if (btrfs_leaf_free_space(fs_info, leaf) < total_size) { 4726 btrfs_print_leaf(leaf); 4727 btrfs_crit(fs_info, "not enough freespace need %u have %d", 4728 total_size, btrfs_leaf_free_space(fs_info, leaf)); 4729 BUG(); 4730 } 4731 4732 if (slot != nritems) { 4733 unsigned int old_data = btrfs_item_end_nr(leaf, slot); 4734 4735 if (old_data < data_end) { 4736 btrfs_print_leaf(leaf); 4737 btrfs_crit(fs_info, "slot %d old_data %d data_end %d", 4738 slot, old_data, data_end); 4739 BUG_ON(1); 4740 } 4741 /* 4742 * item0..itemN ... dataN.offset..dataN.size .. data0.size 4743 */ 4744 /* first correct the data pointers */ 4745 for (i = slot; i < nritems; i++) { 4746 u32 ioff; 4747 4748 item = btrfs_item_nr(i); 4749 ioff = btrfs_token_item_offset(leaf, item, &token); 4750 btrfs_set_token_item_offset(leaf, item, 4751 ioff - total_data, &token); 4752 } 4753 /* shift the items */ 4754 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr), 4755 btrfs_item_nr_offset(slot), 4756 (nritems - slot) * sizeof(struct btrfs_item)); 4757 4758 /* shift the data */ 4759 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET + 4760 data_end - total_data, BTRFS_LEAF_DATA_OFFSET + 4761 data_end, old_data - data_end); 4762 data_end = old_data; 4763 } 4764 4765 /* setup the item for the new data */ 4766 for (i = 0; i < nr; i++) { 4767 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i); 4768 btrfs_set_item_key(leaf, &disk_key, slot + i); 4769 item = btrfs_item_nr(slot + i); 4770 btrfs_set_token_item_offset(leaf, item, 4771 data_end - data_size[i], &token); 4772 data_end -= data_size[i]; 4773 btrfs_set_token_item_size(leaf, item, data_size[i], &token); 4774 } 4775 4776 btrfs_set_header_nritems(leaf, nritems + nr); 4777 btrfs_mark_buffer_dirty(leaf); 4778 4779 if (btrfs_leaf_free_space(fs_info, leaf) < 0) { 4780 btrfs_print_leaf(leaf); 4781 BUG(); 4782 } 4783 } 4784 4785 /* 4786 * Given a key and some data, insert items into the tree. 4787 * This does all the path init required, making room in the tree if needed. 4788 */ 4789 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, 4790 struct btrfs_root *root, 4791 struct btrfs_path *path, 4792 const struct btrfs_key *cpu_key, u32 *data_size, 4793 int nr) 4794 { 4795 int ret = 0; 4796 int slot; 4797 int i; 4798 u32 total_size = 0; 4799 u32 total_data = 0; 4800 4801 for (i = 0; i < nr; i++) 4802 total_data += data_size[i]; 4803 4804 total_size = total_data + (nr * sizeof(struct btrfs_item)); 4805 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1); 4806 if (ret == 0) 4807 return -EEXIST; 4808 if (ret < 0) 4809 return ret; 4810 4811 slot = path->slots[0]; 4812 BUG_ON(slot < 0); 4813 4814 setup_items_for_insert(root, path, cpu_key, data_size, 4815 total_data, total_size, nr); 4816 return 0; 4817 } 4818 4819 /* 4820 * Given a key and some data, insert an item into the tree. 4821 * This does all the path init required, making room in the tree if needed. 4822 */ 4823 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, 4824 const struct btrfs_key *cpu_key, void *data, 4825 u32 data_size) 4826 { 4827 int ret = 0; 4828 struct btrfs_path *path; 4829 struct extent_buffer *leaf; 4830 unsigned long ptr; 4831 4832 path = btrfs_alloc_path(); 4833 if (!path) 4834 return -ENOMEM; 4835 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size); 4836 if (!ret) { 4837 leaf = path->nodes[0]; 4838 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); 4839 write_extent_buffer(leaf, data, ptr, data_size); 4840 btrfs_mark_buffer_dirty(leaf); 4841 } 4842 btrfs_free_path(path); 4843 return ret; 4844 } 4845 4846 /* 4847 * delete the pointer from a given node. 4848 * 4849 * the tree should have been previously balanced so the deletion does not 4850 * empty a node. 4851 */ 4852 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path, 4853 int level, int slot) 4854 { 4855 struct extent_buffer *parent = path->nodes[level]; 4856 u32 nritems; 4857 int ret; 4858 4859 nritems = btrfs_header_nritems(parent); 4860 if (slot != nritems - 1) { 4861 if (level) { 4862 ret = tree_mod_log_insert_move(parent, slot, slot + 1, 4863 nritems - slot - 1); 4864 BUG_ON(ret < 0); 4865 } 4866 memmove_extent_buffer(parent, 4867 btrfs_node_key_ptr_offset(slot), 4868 btrfs_node_key_ptr_offset(slot + 1), 4869 sizeof(struct btrfs_key_ptr) * 4870 (nritems - slot - 1)); 4871 } else if (level) { 4872 ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE, 4873 GFP_NOFS); 4874 BUG_ON(ret < 0); 4875 } 4876 4877 nritems--; 4878 btrfs_set_header_nritems(parent, nritems); 4879 if (nritems == 0 && parent == root->node) { 4880 BUG_ON(btrfs_header_level(root->node) != 1); 4881 /* just turn the root into a leaf and break */ 4882 btrfs_set_header_level(root->node, 0); 4883 } else if (slot == 0) { 4884 struct btrfs_disk_key disk_key; 4885 4886 btrfs_node_key(parent, &disk_key, 0); 4887 fixup_low_keys(path, &disk_key, level + 1); 4888 } 4889 btrfs_mark_buffer_dirty(parent); 4890 } 4891 4892 /* 4893 * a helper function to delete the leaf pointed to by path->slots[1] and 4894 * path->nodes[1]. 4895 * 4896 * This deletes the pointer in path->nodes[1] and frees the leaf 4897 * block extent. zero is returned if it all worked out, < 0 otherwise. 4898 * 4899 * The path must have already been setup for deleting the leaf, including 4900 * all the proper balancing. path->nodes[1] must be locked. 4901 */ 4902 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans, 4903 struct btrfs_root *root, 4904 struct btrfs_path *path, 4905 struct extent_buffer *leaf) 4906 { 4907 WARN_ON(btrfs_header_generation(leaf) != trans->transid); 4908 del_ptr(root, path, 1, path->slots[1]); 4909 4910 /* 4911 * btrfs_free_extent is expensive, we want to make sure we 4912 * aren't holding any locks when we call it 4913 */ 4914 btrfs_unlock_up_safe(path, 0); 4915 4916 root_sub_used(root, leaf->len); 4917 4918 extent_buffer_get(leaf); 4919 btrfs_free_tree_block(trans, root, leaf, 0, 1); 4920 free_extent_buffer_stale(leaf); 4921 } 4922 /* 4923 * delete the item at the leaf level in path. If that empties 4924 * the leaf, remove it from the tree 4925 */ 4926 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, 4927 struct btrfs_path *path, int slot, int nr) 4928 { 4929 struct btrfs_fs_info *fs_info = root->fs_info; 4930 struct extent_buffer *leaf; 4931 struct btrfs_item *item; 4932 u32 last_off; 4933 u32 dsize = 0; 4934 int ret = 0; 4935 int wret; 4936 int i; 4937 u32 nritems; 4938 struct btrfs_map_token token; 4939 4940 btrfs_init_map_token(&token); 4941 4942 leaf = path->nodes[0]; 4943 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1); 4944 4945 for (i = 0; i < nr; i++) 4946 dsize += btrfs_item_size_nr(leaf, slot + i); 4947 4948 nritems = btrfs_header_nritems(leaf); 4949 4950 if (slot + nr != nritems) { 4951 int data_end = leaf_data_end(fs_info, leaf); 4952 4953 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET + 4954 data_end + dsize, 4955 BTRFS_LEAF_DATA_OFFSET + data_end, 4956 last_off - data_end); 4957 4958 for (i = slot + nr; i < nritems; i++) { 4959 u32 ioff; 4960 4961 item = btrfs_item_nr(i); 4962 ioff = btrfs_token_item_offset(leaf, item, &token); 4963 btrfs_set_token_item_offset(leaf, item, 4964 ioff + dsize, &token); 4965 } 4966 4967 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot), 4968 btrfs_item_nr_offset(slot + nr), 4969 sizeof(struct btrfs_item) * 4970 (nritems - slot - nr)); 4971 } 4972 btrfs_set_header_nritems(leaf, nritems - nr); 4973 nritems -= nr; 4974 4975 /* delete the leaf if we've emptied it */ 4976 if (nritems == 0) { 4977 if (leaf == root->node) { 4978 btrfs_set_header_level(leaf, 0); 4979 } else { 4980 btrfs_set_path_blocking(path); 4981 clean_tree_block(fs_info, leaf); 4982 btrfs_del_leaf(trans, root, path, leaf); 4983 } 4984 } else { 4985 int used = leaf_space_used(leaf, 0, nritems); 4986 if (slot == 0) { 4987 struct btrfs_disk_key disk_key; 4988 4989 btrfs_item_key(leaf, &disk_key, 0); 4990 fixup_low_keys(path, &disk_key, 1); 4991 } 4992 4993 /* delete the leaf if it is mostly empty */ 4994 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) { 4995 /* push_leaf_left fixes the path. 4996 * make sure the path still points to our leaf 4997 * for possible call to del_ptr below 4998 */ 4999 slot = path->slots[1]; 5000 extent_buffer_get(leaf); 5001 5002 btrfs_set_path_blocking(path); 5003 wret = push_leaf_left(trans, root, path, 1, 1, 5004 1, (u32)-1); 5005 if (wret < 0 && wret != -ENOSPC) 5006 ret = wret; 5007 5008 if (path->nodes[0] == leaf && 5009 btrfs_header_nritems(leaf)) { 5010 wret = push_leaf_right(trans, root, path, 1, 5011 1, 1, 0); 5012 if (wret < 0 && wret != -ENOSPC) 5013 ret = wret; 5014 } 5015 5016 if (btrfs_header_nritems(leaf) == 0) { 5017 path->slots[1] = slot; 5018 btrfs_del_leaf(trans, root, path, leaf); 5019 free_extent_buffer(leaf); 5020 ret = 0; 5021 } else { 5022 /* if we're still in the path, make sure 5023 * we're dirty. Otherwise, one of the 5024 * push_leaf functions must have already 5025 * dirtied this buffer 5026 */ 5027 if (path->nodes[0] == leaf) 5028 btrfs_mark_buffer_dirty(leaf); 5029 free_extent_buffer(leaf); 5030 } 5031 } else { 5032 btrfs_mark_buffer_dirty(leaf); 5033 } 5034 } 5035 return ret; 5036 } 5037 5038 /* 5039 * search the tree again to find a leaf with lesser keys 5040 * returns 0 if it found something or 1 if there are no lesser leaves. 5041 * returns < 0 on io errors. 5042 * 5043 * This may release the path, and so you may lose any locks held at the 5044 * time you call it. 5045 */ 5046 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) 5047 { 5048 struct btrfs_key key; 5049 struct btrfs_disk_key found_key; 5050 int ret; 5051 5052 btrfs_item_key_to_cpu(path->nodes[0], &key, 0); 5053 5054 if (key.offset > 0) { 5055 key.offset--; 5056 } else if (key.type > 0) { 5057 key.type--; 5058 key.offset = (u64)-1; 5059 } else if (key.objectid > 0) { 5060 key.objectid--; 5061 key.type = (u8)-1; 5062 key.offset = (u64)-1; 5063 } else { 5064 return 1; 5065 } 5066 5067 btrfs_release_path(path); 5068 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 5069 if (ret < 0) 5070 return ret; 5071 btrfs_item_key(path->nodes[0], &found_key, 0); 5072 ret = comp_keys(&found_key, &key); 5073 /* 5074 * We might have had an item with the previous key in the tree right 5075 * before we released our path. And after we released our path, that 5076 * item might have been pushed to the first slot (0) of the leaf we 5077 * were holding due to a tree balance. Alternatively, an item with the 5078 * previous key can exist as the only element of a leaf (big fat item). 5079 * Therefore account for these 2 cases, so that our callers (like 5080 * btrfs_previous_item) don't miss an existing item with a key matching 5081 * the previous key we computed above. 5082 */ 5083 if (ret <= 0) 5084 return 0; 5085 return 1; 5086 } 5087 5088 /* 5089 * A helper function to walk down the tree starting at min_key, and looking 5090 * for nodes or leaves that are have a minimum transaction id. 5091 * This is used by the btree defrag code, and tree logging 5092 * 5093 * This does not cow, but it does stuff the starting key it finds back 5094 * into min_key, so you can call btrfs_search_slot with cow=1 on the 5095 * key and get a writable path. 5096 * 5097 * This honors path->lowest_level to prevent descent past a given level 5098 * of the tree. 5099 * 5100 * min_trans indicates the oldest transaction that you are interested 5101 * in walking through. Any nodes or leaves older than min_trans are 5102 * skipped over (without reading them). 5103 * 5104 * returns zero if something useful was found, < 0 on error and 1 if there 5105 * was nothing in the tree that matched the search criteria. 5106 */ 5107 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key, 5108 struct btrfs_path *path, 5109 u64 min_trans) 5110 { 5111 struct btrfs_fs_info *fs_info = root->fs_info; 5112 struct extent_buffer *cur; 5113 struct btrfs_key found_key; 5114 int slot; 5115 int sret; 5116 u32 nritems; 5117 int level; 5118 int ret = 1; 5119 int keep_locks = path->keep_locks; 5120 5121 path->keep_locks = 1; 5122 again: 5123 cur = btrfs_read_lock_root_node(root); 5124 level = btrfs_header_level(cur); 5125 WARN_ON(path->nodes[level]); 5126 path->nodes[level] = cur; 5127 path->locks[level] = BTRFS_READ_LOCK; 5128 5129 if (btrfs_header_generation(cur) < min_trans) { 5130 ret = 1; 5131 goto out; 5132 } 5133 while (1) { 5134 nritems = btrfs_header_nritems(cur); 5135 level = btrfs_header_level(cur); 5136 sret = btrfs_bin_search(cur, min_key, level, &slot); 5137 5138 /* at the lowest level, we're done, setup the path and exit */ 5139 if (level == path->lowest_level) { 5140 if (slot >= nritems) 5141 goto find_next_key; 5142 ret = 0; 5143 path->slots[level] = slot; 5144 btrfs_item_key_to_cpu(cur, &found_key, slot); 5145 goto out; 5146 } 5147 if (sret && slot > 0) 5148 slot--; 5149 /* 5150 * check this node pointer against the min_trans parameters. 5151 * If it is too old, old, skip to the next one. 5152 */ 5153 while (slot < nritems) { 5154 u64 gen; 5155 5156 gen = btrfs_node_ptr_generation(cur, slot); 5157 if (gen < min_trans) { 5158 slot++; 5159 continue; 5160 } 5161 break; 5162 } 5163 find_next_key: 5164 /* 5165 * we didn't find a candidate key in this node, walk forward 5166 * and find another one 5167 */ 5168 if (slot >= nritems) { 5169 path->slots[level] = slot; 5170 btrfs_set_path_blocking(path); 5171 sret = btrfs_find_next_key(root, path, min_key, level, 5172 min_trans); 5173 if (sret == 0) { 5174 btrfs_release_path(path); 5175 goto again; 5176 } else { 5177 goto out; 5178 } 5179 } 5180 /* save our key for returning back */ 5181 btrfs_node_key_to_cpu(cur, &found_key, slot); 5182 path->slots[level] = slot; 5183 if (level == path->lowest_level) { 5184 ret = 0; 5185 goto out; 5186 } 5187 btrfs_set_path_blocking(path); 5188 cur = read_node_slot(fs_info, cur, slot); 5189 if (IS_ERR(cur)) { 5190 ret = PTR_ERR(cur); 5191 goto out; 5192 } 5193 5194 btrfs_tree_read_lock(cur); 5195 5196 path->locks[level - 1] = BTRFS_READ_LOCK; 5197 path->nodes[level - 1] = cur; 5198 unlock_up(path, level, 1, 0, NULL); 5199 } 5200 out: 5201 path->keep_locks = keep_locks; 5202 if (ret == 0) { 5203 btrfs_unlock_up_safe(path, path->lowest_level + 1); 5204 btrfs_set_path_blocking(path); 5205 memcpy(min_key, &found_key, sizeof(found_key)); 5206 } 5207 return ret; 5208 } 5209 5210 static int tree_move_down(struct btrfs_fs_info *fs_info, 5211 struct btrfs_path *path, 5212 int *level) 5213 { 5214 struct extent_buffer *eb; 5215 5216 BUG_ON(*level == 0); 5217 eb = read_node_slot(fs_info, path->nodes[*level], path->slots[*level]); 5218 if (IS_ERR(eb)) 5219 return PTR_ERR(eb); 5220 5221 path->nodes[*level - 1] = eb; 5222 path->slots[*level - 1] = 0; 5223 (*level)--; 5224 return 0; 5225 } 5226 5227 static int tree_move_next_or_upnext(struct btrfs_path *path, 5228 int *level, int root_level) 5229 { 5230 int ret = 0; 5231 int nritems; 5232 nritems = btrfs_header_nritems(path->nodes[*level]); 5233 5234 path->slots[*level]++; 5235 5236 while (path->slots[*level] >= nritems) { 5237 if (*level == root_level) 5238 return -1; 5239 5240 /* move upnext */ 5241 path->slots[*level] = 0; 5242 free_extent_buffer(path->nodes[*level]); 5243 path->nodes[*level] = NULL; 5244 (*level)++; 5245 path->slots[*level]++; 5246 5247 nritems = btrfs_header_nritems(path->nodes[*level]); 5248 ret = 1; 5249 } 5250 return ret; 5251 } 5252 5253 /* 5254 * Returns 1 if it had to move up and next. 0 is returned if it moved only next 5255 * or down. 5256 */ 5257 static int tree_advance(struct btrfs_fs_info *fs_info, 5258 struct btrfs_path *path, 5259 int *level, int root_level, 5260 int allow_down, 5261 struct btrfs_key *key) 5262 { 5263 int ret; 5264 5265 if (*level == 0 || !allow_down) { 5266 ret = tree_move_next_or_upnext(path, level, root_level); 5267 } else { 5268 ret = tree_move_down(fs_info, path, level); 5269 } 5270 if (ret >= 0) { 5271 if (*level == 0) 5272 btrfs_item_key_to_cpu(path->nodes[*level], key, 5273 path->slots[*level]); 5274 else 5275 btrfs_node_key_to_cpu(path->nodes[*level], key, 5276 path->slots[*level]); 5277 } 5278 return ret; 5279 } 5280 5281 static int tree_compare_item(struct btrfs_path *left_path, 5282 struct btrfs_path *right_path, 5283 char *tmp_buf) 5284 { 5285 int cmp; 5286 int len1, len2; 5287 unsigned long off1, off2; 5288 5289 len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]); 5290 len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]); 5291 if (len1 != len2) 5292 return 1; 5293 5294 off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]); 5295 off2 = btrfs_item_ptr_offset(right_path->nodes[0], 5296 right_path->slots[0]); 5297 5298 read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1); 5299 5300 cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1); 5301 if (cmp) 5302 return 1; 5303 return 0; 5304 } 5305 5306 #define ADVANCE 1 5307 #define ADVANCE_ONLY_NEXT -1 5308 5309 /* 5310 * This function compares two trees and calls the provided callback for 5311 * every changed/new/deleted item it finds. 5312 * If shared tree blocks are encountered, whole subtrees are skipped, making 5313 * the compare pretty fast on snapshotted subvolumes. 5314 * 5315 * This currently works on commit roots only. As commit roots are read only, 5316 * we don't do any locking. The commit roots are protected with transactions. 5317 * Transactions are ended and rejoined when a commit is tried in between. 5318 * 5319 * This function checks for modifications done to the trees while comparing. 5320 * If it detects a change, it aborts immediately. 5321 */ 5322 int btrfs_compare_trees(struct btrfs_root *left_root, 5323 struct btrfs_root *right_root, 5324 btrfs_changed_cb_t changed_cb, void *ctx) 5325 { 5326 struct btrfs_fs_info *fs_info = left_root->fs_info; 5327 int ret; 5328 int cmp; 5329 struct btrfs_path *left_path = NULL; 5330 struct btrfs_path *right_path = NULL; 5331 struct btrfs_key left_key; 5332 struct btrfs_key right_key; 5333 char *tmp_buf = NULL; 5334 int left_root_level; 5335 int right_root_level; 5336 int left_level; 5337 int right_level; 5338 int left_end_reached; 5339 int right_end_reached; 5340 int advance_left; 5341 int advance_right; 5342 u64 left_blockptr; 5343 u64 right_blockptr; 5344 u64 left_gen; 5345 u64 right_gen; 5346 5347 left_path = btrfs_alloc_path(); 5348 if (!left_path) { 5349 ret = -ENOMEM; 5350 goto out; 5351 } 5352 right_path = btrfs_alloc_path(); 5353 if (!right_path) { 5354 ret = -ENOMEM; 5355 goto out; 5356 } 5357 5358 tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL); 5359 if (!tmp_buf) { 5360 ret = -ENOMEM; 5361 goto out; 5362 } 5363 5364 left_path->search_commit_root = 1; 5365 left_path->skip_locking = 1; 5366 right_path->search_commit_root = 1; 5367 right_path->skip_locking = 1; 5368 5369 /* 5370 * Strategy: Go to the first items of both trees. Then do 5371 * 5372 * If both trees are at level 0 5373 * Compare keys of current items 5374 * If left < right treat left item as new, advance left tree 5375 * and repeat 5376 * If left > right treat right item as deleted, advance right tree 5377 * and repeat 5378 * If left == right do deep compare of items, treat as changed if 5379 * needed, advance both trees and repeat 5380 * If both trees are at the same level but not at level 0 5381 * Compare keys of current nodes/leafs 5382 * If left < right advance left tree and repeat 5383 * If left > right advance right tree and repeat 5384 * If left == right compare blockptrs of the next nodes/leafs 5385 * If they match advance both trees but stay at the same level 5386 * and repeat 5387 * If they don't match advance both trees while allowing to go 5388 * deeper and repeat 5389 * If tree levels are different 5390 * Advance the tree that needs it and repeat 5391 * 5392 * Advancing a tree means: 5393 * If we are at level 0, try to go to the next slot. If that's not 5394 * possible, go one level up and repeat. Stop when we found a level 5395 * where we could go to the next slot. We may at this point be on a 5396 * node or a leaf. 5397 * 5398 * If we are not at level 0 and not on shared tree blocks, go one 5399 * level deeper. 5400 * 5401 * If we are not at level 0 and on shared tree blocks, go one slot to 5402 * the right if possible or go up and right. 5403 */ 5404 5405 down_read(&fs_info->commit_root_sem); 5406 left_level = btrfs_header_level(left_root->commit_root); 5407 left_root_level = left_level; 5408 left_path->nodes[left_level] = 5409 btrfs_clone_extent_buffer(left_root->commit_root); 5410 if (!left_path->nodes[left_level]) { 5411 up_read(&fs_info->commit_root_sem); 5412 ret = -ENOMEM; 5413 goto out; 5414 } 5415 5416 right_level = btrfs_header_level(right_root->commit_root); 5417 right_root_level = right_level; 5418 right_path->nodes[right_level] = 5419 btrfs_clone_extent_buffer(right_root->commit_root); 5420 if (!right_path->nodes[right_level]) { 5421 up_read(&fs_info->commit_root_sem); 5422 ret = -ENOMEM; 5423 goto out; 5424 } 5425 up_read(&fs_info->commit_root_sem); 5426 5427 if (left_level == 0) 5428 btrfs_item_key_to_cpu(left_path->nodes[left_level], 5429 &left_key, left_path->slots[left_level]); 5430 else 5431 btrfs_node_key_to_cpu(left_path->nodes[left_level], 5432 &left_key, left_path->slots[left_level]); 5433 if (right_level == 0) 5434 btrfs_item_key_to_cpu(right_path->nodes[right_level], 5435 &right_key, right_path->slots[right_level]); 5436 else 5437 btrfs_node_key_to_cpu(right_path->nodes[right_level], 5438 &right_key, right_path->slots[right_level]); 5439 5440 left_end_reached = right_end_reached = 0; 5441 advance_left = advance_right = 0; 5442 5443 while (1) { 5444 if (advance_left && !left_end_reached) { 5445 ret = tree_advance(fs_info, left_path, &left_level, 5446 left_root_level, 5447 advance_left != ADVANCE_ONLY_NEXT, 5448 &left_key); 5449 if (ret == -1) 5450 left_end_reached = ADVANCE; 5451 else if (ret < 0) 5452 goto out; 5453 advance_left = 0; 5454 } 5455 if (advance_right && !right_end_reached) { 5456 ret = tree_advance(fs_info, right_path, &right_level, 5457 right_root_level, 5458 advance_right != ADVANCE_ONLY_NEXT, 5459 &right_key); 5460 if (ret == -1) 5461 right_end_reached = ADVANCE; 5462 else if (ret < 0) 5463 goto out; 5464 advance_right = 0; 5465 } 5466 5467 if (left_end_reached && right_end_reached) { 5468 ret = 0; 5469 goto out; 5470 } else if (left_end_reached) { 5471 if (right_level == 0) { 5472 ret = changed_cb(left_path, right_path, 5473 &right_key, 5474 BTRFS_COMPARE_TREE_DELETED, 5475 ctx); 5476 if (ret < 0) 5477 goto out; 5478 } 5479 advance_right = ADVANCE; 5480 continue; 5481 } else if (right_end_reached) { 5482 if (left_level == 0) { 5483 ret = changed_cb(left_path, right_path, 5484 &left_key, 5485 BTRFS_COMPARE_TREE_NEW, 5486 ctx); 5487 if (ret < 0) 5488 goto out; 5489 } 5490 advance_left = ADVANCE; 5491 continue; 5492 } 5493 5494 if (left_level == 0 && right_level == 0) { 5495 cmp = btrfs_comp_cpu_keys(&left_key, &right_key); 5496 if (cmp < 0) { 5497 ret = changed_cb(left_path, right_path, 5498 &left_key, 5499 BTRFS_COMPARE_TREE_NEW, 5500 ctx); 5501 if (ret < 0) 5502 goto out; 5503 advance_left = ADVANCE; 5504 } else if (cmp > 0) { 5505 ret = changed_cb(left_path, right_path, 5506 &right_key, 5507 BTRFS_COMPARE_TREE_DELETED, 5508 ctx); 5509 if (ret < 0) 5510 goto out; 5511 advance_right = ADVANCE; 5512 } else { 5513 enum btrfs_compare_tree_result result; 5514 5515 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0])); 5516 ret = tree_compare_item(left_path, right_path, 5517 tmp_buf); 5518 if (ret) 5519 result = BTRFS_COMPARE_TREE_CHANGED; 5520 else 5521 result = BTRFS_COMPARE_TREE_SAME; 5522 ret = changed_cb(left_path, right_path, 5523 &left_key, result, ctx); 5524 if (ret < 0) 5525 goto out; 5526 advance_left = ADVANCE; 5527 advance_right = ADVANCE; 5528 } 5529 } else if (left_level == right_level) { 5530 cmp = btrfs_comp_cpu_keys(&left_key, &right_key); 5531 if (cmp < 0) { 5532 advance_left = ADVANCE; 5533 } else if (cmp > 0) { 5534 advance_right = ADVANCE; 5535 } else { 5536 left_blockptr = btrfs_node_blockptr( 5537 left_path->nodes[left_level], 5538 left_path->slots[left_level]); 5539 right_blockptr = btrfs_node_blockptr( 5540 right_path->nodes[right_level], 5541 right_path->slots[right_level]); 5542 left_gen = btrfs_node_ptr_generation( 5543 left_path->nodes[left_level], 5544 left_path->slots[left_level]); 5545 right_gen = btrfs_node_ptr_generation( 5546 right_path->nodes[right_level], 5547 right_path->slots[right_level]); 5548 if (left_blockptr == right_blockptr && 5549 left_gen == right_gen) { 5550 /* 5551 * As we're on a shared block, don't 5552 * allow to go deeper. 5553 */ 5554 advance_left = ADVANCE_ONLY_NEXT; 5555 advance_right = ADVANCE_ONLY_NEXT; 5556 } else { 5557 advance_left = ADVANCE; 5558 advance_right = ADVANCE; 5559 } 5560 } 5561 } else if (left_level < right_level) { 5562 advance_right = ADVANCE; 5563 } else { 5564 advance_left = ADVANCE; 5565 } 5566 } 5567 5568 out: 5569 btrfs_free_path(left_path); 5570 btrfs_free_path(right_path); 5571 kvfree(tmp_buf); 5572 return ret; 5573 } 5574 5575 /* 5576 * this is similar to btrfs_next_leaf, but does not try to preserve 5577 * and fixup the path. It looks for and returns the next key in the 5578 * tree based on the current path and the min_trans parameters. 5579 * 5580 * 0 is returned if another key is found, < 0 if there are any errors 5581 * and 1 is returned if there are no higher keys in the tree 5582 * 5583 * path->keep_locks should be set to 1 on the search made before 5584 * calling this function. 5585 */ 5586 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path, 5587 struct btrfs_key *key, int level, u64 min_trans) 5588 { 5589 int slot; 5590 struct extent_buffer *c; 5591 5592 WARN_ON(!path->keep_locks); 5593 while (level < BTRFS_MAX_LEVEL) { 5594 if (!path->nodes[level]) 5595 return 1; 5596 5597 slot = path->slots[level] + 1; 5598 c = path->nodes[level]; 5599 next: 5600 if (slot >= btrfs_header_nritems(c)) { 5601 int ret; 5602 int orig_lowest; 5603 struct btrfs_key cur_key; 5604 if (level + 1 >= BTRFS_MAX_LEVEL || 5605 !path->nodes[level + 1]) 5606 return 1; 5607 5608 if (path->locks[level + 1]) { 5609 level++; 5610 continue; 5611 } 5612 5613 slot = btrfs_header_nritems(c) - 1; 5614 if (level == 0) 5615 btrfs_item_key_to_cpu(c, &cur_key, slot); 5616 else 5617 btrfs_node_key_to_cpu(c, &cur_key, slot); 5618 5619 orig_lowest = path->lowest_level; 5620 btrfs_release_path(path); 5621 path->lowest_level = level; 5622 ret = btrfs_search_slot(NULL, root, &cur_key, path, 5623 0, 0); 5624 path->lowest_level = orig_lowest; 5625 if (ret < 0) 5626 return ret; 5627 5628 c = path->nodes[level]; 5629 slot = path->slots[level]; 5630 if (ret == 0) 5631 slot++; 5632 goto next; 5633 } 5634 5635 if (level == 0) 5636 btrfs_item_key_to_cpu(c, key, slot); 5637 else { 5638 u64 gen = btrfs_node_ptr_generation(c, slot); 5639 5640 if (gen < min_trans) { 5641 slot++; 5642 goto next; 5643 } 5644 btrfs_node_key_to_cpu(c, key, slot); 5645 } 5646 return 0; 5647 } 5648 return 1; 5649 } 5650 5651 /* 5652 * search the tree again to find a leaf with greater keys 5653 * returns 0 if it found something or 1 if there are no greater leaves. 5654 * returns < 0 on io errors. 5655 */ 5656 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) 5657 { 5658 return btrfs_next_old_leaf(root, path, 0); 5659 } 5660 5661 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path, 5662 u64 time_seq) 5663 { 5664 int slot; 5665 int level; 5666 struct extent_buffer *c; 5667 struct extent_buffer *next; 5668 struct btrfs_key key; 5669 u32 nritems; 5670 int ret; 5671 int old_spinning = path->leave_spinning; 5672 int next_rw_lock = 0; 5673 5674 nritems = btrfs_header_nritems(path->nodes[0]); 5675 if (nritems == 0) 5676 return 1; 5677 5678 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1); 5679 again: 5680 level = 1; 5681 next = NULL; 5682 next_rw_lock = 0; 5683 btrfs_release_path(path); 5684 5685 path->keep_locks = 1; 5686 path->leave_spinning = 1; 5687 5688 if (time_seq) 5689 ret = btrfs_search_old_slot(root, &key, path, time_seq); 5690 else 5691 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 5692 path->keep_locks = 0; 5693 5694 if (ret < 0) 5695 return ret; 5696 5697 nritems = btrfs_header_nritems(path->nodes[0]); 5698 /* 5699 * by releasing the path above we dropped all our locks. A balance 5700 * could have added more items next to the key that used to be 5701 * at the very end of the block. So, check again here and 5702 * advance the path if there are now more items available. 5703 */ 5704 if (nritems > 0 && path->slots[0] < nritems - 1) { 5705 if (ret == 0) 5706 path->slots[0]++; 5707 ret = 0; 5708 goto done; 5709 } 5710 /* 5711 * So the above check misses one case: 5712 * - after releasing the path above, someone has removed the item that 5713 * used to be at the very end of the block, and balance between leafs 5714 * gets another one with bigger key.offset to replace it. 5715 * 5716 * This one should be returned as well, or we can get leaf corruption 5717 * later(esp. in __btrfs_drop_extents()). 5718 * 5719 * And a bit more explanation about this check, 5720 * with ret > 0, the key isn't found, the path points to the slot 5721 * where it should be inserted, so the path->slots[0] item must be the 5722 * bigger one. 5723 */ 5724 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) { 5725 ret = 0; 5726 goto done; 5727 } 5728 5729 while (level < BTRFS_MAX_LEVEL) { 5730 if (!path->nodes[level]) { 5731 ret = 1; 5732 goto done; 5733 } 5734 5735 slot = path->slots[level] + 1; 5736 c = path->nodes[level]; 5737 if (slot >= btrfs_header_nritems(c)) { 5738 level++; 5739 if (level == BTRFS_MAX_LEVEL) { 5740 ret = 1; 5741 goto done; 5742 } 5743 continue; 5744 } 5745 5746 if (next) { 5747 btrfs_tree_unlock_rw(next, next_rw_lock); 5748 free_extent_buffer(next); 5749 } 5750 5751 next = c; 5752 next_rw_lock = path->locks[level]; 5753 ret = read_block_for_search(root, path, &next, level, 5754 slot, &key); 5755 if (ret == -EAGAIN) 5756 goto again; 5757 5758 if (ret < 0) { 5759 btrfs_release_path(path); 5760 goto done; 5761 } 5762 5763 if (!path->skip_locking) { 5764 ret = btrfs_try_tree_read_lock(next); 5765 if (!ret && time_seq) { 5766 /* 5767 * If we don't get the lock, we may be racing 5768 * with push_leaf_left, holding that lock while 5769 * itself waiting for the leaf we've currently 5770 * locked. To solve this situation, we give up 5771 * on our lock and cycle. 5772 */ 5773 free_extent_buffer(next); 5774 btrfs_release_path(path); 5775 cond_resched(); 5776 goto again; 5777 } 5778 if (!ret) { 5779 btrfs_set_path_blocking(path); 5780 btrfs_tree_read_lock(next); 5781 } 5782 next_rw_lock = BTRFS_READ_LOCK; 5783 } 5784 break; 5785 } 5786 path->slots[level] = slot; 5787 while (1) { 5788 level--; 5789 c = path->nodes[level]; 5790 if (path->locks[level]) 5791 btrfs_tree_unlock_rw(c, path->locks[level]); 5792 5793 free_extent_buffer(c); 5794 path->nodes[level] = next; 5795 path->slots[level] = 0; 5796 if (!path->skip_locking) 5797 path->locks[level] = next_rw_lock; 5798 if (!level) 5799 break; 5800 5801 ret = read_block_for_search(root, path, &next, level, 5802 0, &key); 5803 if (ret == -EAGAIN) 5804 goto again; 5805 5806 if (ret < 0) { 5807 btrfs_release_path(path); 5808 goto done; 5809 } 5810 5811 if (!path->skip_locking) { 5812 ret = btrfs_try_tree_read_lock(next); 5813 if (!ret) { 5814 btrfs_set_path_blocking(path); 5815 btrfs_tree_read_lock(next); 5816 } 5817 next_rw_lock = BTRFS_READ_LOCK; 5818 } 5819 } 5820 ret = 0; 5821 done: 5822 unlock_up(path, 0, 1, 0, NULL); 5823 path->leave_spinning = old_spinning; 5824 if (!old_spinning) 5825 btrfs_set_path_blocking(path); 5826 5827 return ret; 5828 } 5829 5830 /* 5831 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps 5832 * searching until it gets past min_objectid or finds an item of 'type' 5833 * 5834 * returns 0 if something is found, 1 if nothing was found and < 0 on error 5835 */ 5836 int btrfs_previous_item(struct btrfs_root *root, 5837 struct btrfs_path *path, u64 min_objectid, 5838 int type) 5839 { 5840 struct btrfs_key found_key; 5841 struct extent_buffer *leaf; 5842 u32 nritems; 5843 int ret; 5844 5845 while (1) { 5846 if (path->slots[0] == 0) { 5847 btrfs_set_path_blocking(path); 5848 ret = btrfs_prev_leaf(root, path); 5849 if (ret != 0) 5850 return ret; 5851 } else { 5852 path->slots[0]--; 5853 } 5854 leaf = path->nodes[0]; 5855 nritems = btrfs_header_nritems(leaf); 5856 if (nritems == 0) 5857 return 1; 5858 if (path->slots[0] == nritems) 5859 path->slots[0]--; 5860 5861 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 5862 if (found_key.objectid < min_objectid) 5863 break; 5864 if (found_key.type == type) 5865 return 0; 5866 if (found_key.objectid == min_objectid && 5867 found_key.type < type) 5868 break; 5869 } 5870 return 1; 5871 } 5872 5873 /* 5874 * search in extent tree to find a previous Metadata/Data extent item with 5875 * min objecitd. 5876 * 5877 * returns 0 if something is found, 1 if nothing was found and < 0 on error 5878 */ 5879 int btrfs_previous_extent_item(struct btrfs_root *root, 5880 struct btrfs_path *path, u64 min_objectid) 5881 { 5882 struct btrfs_key found_key; 5883 struct extent_buffer *leaf; 5884 u32 nritems; 5885 int ret; 5886 5887 while (1) { 5888 if (path->slots[0] == 0) { 5889 btrfs_set_path_blocking(path); 5890 ret = btrfs_prev_leaf(root, path); 5891 if (ret != 0) 5892 return ret; 5893 } else { 5894 path->slots[0]--; 5895 } 5896 leaf = path->nodes[0]; 5897 nritems = btrfs_header_nritems(leaf); 5898 if (nritems == 0) 5899 return 1; 5900 if (path->slots[0] == nritems) 5901 path->slots[0]--; 5902 5903 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 5904 if (found_key.objectid < min_objectid) 5905 break; 5906 if (found_key.type == BTRFS_EXTENT_ITEM_KEY || 5907 found_key.type == BTRFS_METADATA_ITEM_KEY) 5908 return 0; 5909 if (found_key.objectid == min_objectid && 5910 found_key.type < BTRFS_EXTENT_ITEM_KEY) 5911 break; 5912 } 5913 return 1; 5914 } 5915