fs/btrfs/relocation.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2009 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/writeback.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/rbtree.h>
  11 #include <linux/slab.h>
  12 #include "ctree.h"
  13 #include "disk-io.h"
  14 #include "transaction.h"
  15 #include "volumes.h"
  16 #include "locking.h"
  17 #include "btrfs_inode.h"
  18 #include "async-thread.h"
  19 #include "free-space-cache.h"
  20 #include "inode-map.h"
  21 #include "qgroup.h"
  22 #include "print-tree.h"
  23
  24 /*
  25  * backref_node, mapping_node and tree_block start with this
  26  */
  27 struct tree_entry {
  28         struct rb_node rb_node;
  29         u64 bytenr;
  30 };
  31
  32 /*
  33  * present a tree block in the backref cache
  34  */
  35 struct backref_node {
  36         struct rb_node rb_node;
  37         u64 bytenr;
  38
  39         u64 new_bytenr;
  40         /* objectid of tree block owner, can be not uptodate */
  41         u64 owner;
  42         /* link to pending, changed or detached list */
  43         struct list_head list;
  44         /* list of upper level blocks reference this block */
  45         struct list_head upper;
  46         /* list of child blocks in the cache */
  47         struct list_head lower;
  48         /* NULL if this node is not tree root */
  49         struct btrfs_root *root;
  50         /* extent buffer got by COW the block */
  51         struct extent_buffer *eb;
  52         /* level of tree block */
  53         unsigned int level:8;
  54         /* is the block in non-reference counted tree */
  55         unsigned int cowonly:1;
  56         /* 1 if no child node in the cache */
  57         unsigned int lowest:1;
  58         /* is the extent buffer locked */
  59         unsigned int locked:1;
  60         /* has the block been processed */
  61         unsigned int processed:1;
  62         /* have backrefs of this block been checked */
  63         unsigned int checked:1;
  64         /*
  65          * 1 if corresponding block has been cowed but some upper
  66          * level block pointers may not point to the new location
  67          */
  68         unsigned int pending:1;
  69         /*
  70          * 1 if the backref node isn't connected to any other
  71          * backref node.
  72          */
  73         unsigned int detached:1;
  74 };
  75
  76 /*
  77  * present a block pointer in the backref cache
  78  */
  79 struct backref_edge {
  80         struct list_head list[2];
  81         struct backref_node *node[2];
  82 };
  83
  84 #define LOWER   0
  85 #define UPPER   1
  86 #define RELOCATION_RESERVED_NODES       256
  87
  88 struct backref_cache {
  89         /* red black tree of all backref nodes in the cache */
  90         struct rb_root rb_root;
  91         /* for passing backref nodes to btrfs_reloc_cow_block */
  92         struct backref_node *path[BTRFS_MAX_LEVEL];
  93         /*
  94          * list of blocks that have been cowed but some block
  95          * pointers in upper level blocks may not reflect the
  96          * new location
  97          */
  98         struct list_head pending[BTRFS_MAX_LEVEL];
  99         /* list of backref nodes with no child node */
 100         struct list_head leaves;
 101         /* list of blocks that have been cowed in current transaction */
 102         struct list_head changed;
 103         /* list of detached backref node. */
 104         struct list_head detached;
 105
 106         u64 last_trans;
 107
 108         int nr_nodes;
 109         int nr_edges;
 110 };
 111
 112 /*
 113  * map address of tree root to tree
 114  */
 115 struct mapping_node {
 116         struct rb_node rb_node;
 117         u64 bytenr;
 118         void *data;
 119 };
 120
 121 struct mapping_tree {
 122         struct rb_root rb_root;
 123         spinlock_t lock;
 124 };
 125
 126 /*
 127  * present a tree block to process
 128  */
 129 struct tree_block {
 130         struct rb_node rb_node;
 131         u64 bytenr;
 132         struct btrfs_key key;
 133         unsigned int level:8;
 134         unsigned int key_ready:1;
 135 };
 136
 137 #define MAX_EXTENTS 128
 138
 139 struct file_extent_cluster {
 140         u64 start;
 141         u64 end;
 142         u64 boundary[MAX_EXTENTS];
 143         unsigned int nr;
 144 };
 145
 146 struct reloc_control {
 147         /* block group to relocate */
 148         struct btrfs_block_group_cache *block_group;
 149         /* extent tree */
 150         struct btrfs_root *extent_root;
 151         /* inode for moving data */
 152         struct inode *data_inode;
 153
 154         struct btrfs_block_rsv *block_rsv;
 155
 156         struct backref_cache backref_cache;
 157
 158         struct file_extent_cluster cluster;
 159         /* tree blocks have been processed */
 160         struct extent_io_tree processed_blocks;
 161         /* map start of tree root to corresponding reloc tree */
 162         struct mapping_tree reloc_root_tree;
 163         /* list of reloc trees */
 164         struct list_head reloc_roots;
 165         /* size of metadata reservation for merging reloc trees */
 166         u64 merging_rsv_size;
 167         /* size of relocated tree nodes */
 168         u64 nodes_relocated;
 169         /* reserved size for block group relocation*/
 170         u64 reserved_bytes;
 171
 172         u64 search_start;
 173         u64 extents_found;
 174
 175         unsigned int stage:8;
 176         unsigned int create_reloc_tree:1;
 177         unsigned int merge_reloc_tree:1;
 178         unsigned int found_file_extent:1;
 179 };
 180
 181 /* stages of data relocation */
 182 #define MOVE_DATA_EXTENTS       0
 183 #define UPDATE_DATA_PTRS        1
 184
 185 static void remove_backref_node(struct backref_cache *cache,
 186                                 struct backref_node *node);
 187 static void __mark_block_processed(struct reloc_control *rc,
 188                                    struct backref_node *node);
 189
 190 static void mapping_tree_init(struct mapping_tree *tree)
 191 {
 192         tree->rb_root = RB_ROOT;
 193         spin_lock_init(&tree->lock);
 194 }
 195
 196 static void backref_cache_init(struct backref_cache *cache)
 197 {
 198         int i;
 199         cache->rb_root = RB_ROOT;
 200         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 201                 INIT_LIST_HEAD(&cache->pending[i]);
 202         INIT_LIST_HEAD(&cache->changed);
 203         INIT_LIST_HEAD(&cache->detached);
 204         INIT_LIST_HEAD(&cache->leaves);
 205 }
 206
 207 static void backref_cache_cleanup(struct backref_cache *cache)
 208 {
 209         struct backref_node *node;
 210         int i;
 211
 212         while (!list_empty(&cache->detached)) {
 213                 node = list_entry(cache->detached.next,
 214                                   struct backref_node, list);
 215                 remove_backref_node(cache, node);
 216         }
 217
 218         while (!list_empty(&cache->leaves)) {
 219                 node = list_entry(cache->leaves.next,
 220                                   struct backref_node, lower);
 221                 remove_backref_node(cache, node);
 222         }
 223
 224         cache->last_trans = 0;
 225
 226         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 227                 ASSERT(list_empty(&cache->pending[i]));
 228         ASSERT(list_empty(&cache->changed));
 229         ASSERT(list_empty(&cache->detached));
 230         ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
 231         ASSERT(!cache->nr_nodes);
 232         ASSERT(!cache->nr_edges);
 233 }
 234
 235 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 236 {
 237         struct backref_node *node;
 238
 239         node = kzalloc(sizeof(*node), GFP_NOFS);
 240         if (node) {
 241                 INIT_LIST_HEAD(&node->list);
 242                 INIT_LIST_HEAD(&node->upper);
 243                 INIT_LIST_HEAD(&node->lower);
 244                 RB_CLEAR_NODE(&node->rb_node);
 245                 cache->nr_nodes++;
 246         }
 247         return node;
 248 }
 249
 250 static void free_backref_node(struct backref_cache *cache,
 251                               struct backref_node *node)
 252 {
 253         if (node) {
 254                 cache->nr_nodes--;
 255                 kfree(node);
 256         }
 257 }
 258
 259 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 260 {
 261         struct backref_edge *edge;
 262
 263         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 264         if (edge)
 265                 cache->nr_edges++;
 266         return edge;
 267 }
 268
 269 static void free_backref_edge(struct backref_cache *cache,
 270                               struct backref_edge *edge)
 271 {
 272         if (edge) {
 273                 cache->nr_edges--;
 274                 kfree(edge);
 275         }
 276 }
 277
 278 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 279                                    struct rb_node *node)
 280 {
 281         struct rb_node **p = &root->rb_node;
 282         struct rb_node *parent = NULL;
 283         struct tree_entry *entry;
 284
 285         while (*p) {
 286                 parent = *p;
 287                 entry = rb_entry(parent, struct tree_entry, rb_node);
 288
 289                 if (bytenr < entry->bytenr)
 290                         p = &(*p)->rb_left;
 291                 else if (bytenr > entry->bytenr)
 292                         p = &(*p)->rb_right;
 293                 else
 294                         return parent;
 295         }
 296
 297         rb_link_node(node, parent, p);
 298         rb_insert_color(node, root);
 299         return NULL;
 300 }
 301
 302 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 303 {
 304         struct rb_node *n = root->rb_node;
 305         struct tree_entry *entry;
 306
 307         while (n) {
 308                 entry = rb_entry(n, struct tree_entry, rb_node);
 309
 310                 if (bytenr < entry->bytenr)
 311                         n = n->rb_left;
 312                 else if (bytenr > entry->bytenr)
 313                         n = n->rb_right;
 314                 else
 315                         return n;
 316         }
 317         return NULL;
 318 }
 319
 320 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 321 {
 322
 323         struct btrfs_fs_info *fs_info = NULL;
 324         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 325                                               rb_node);
 326         if (bnode->root)
 327                 fs_info = bnode->root->fs_info;
 328         btrfs_panic(fs_info, errno,
 329                     "Inconsistency in backref cache found at offset %llu",
 330                     bytenr);
 331 }
 332
 333 /*
 334  * walk up backref nodes until reach node presents tree root
 335  */
 336 static struct backref_node *walk_up_backref(struct backref_node *node,
 337                                             struct backref_edge *edges[],
 338                                             int *index)
 339 {
 340         struct backref_edge *edge;
 341         int idx = *index;
 342
 343         while (!list_empty(&node->upper)) {
 344                 edge = list_entry(node->upper.next,
 345                                   struct backref_edge, list[LOWER]);
 346                 edges[idx++] = edge;
 347                 node = edge->node[UPPER];
 348         }
 349         BUG_ON(node->detached);
 350         *index = idx;
 351         return node;
 352 }
 353
 354 /*
 355  * walk down backref nodes to find start of next reference path
 356  */
 357 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 358                                               int *index)
 359 {
 360         struct backref_edge *edge;
 361         struct backref_node *lower;
 362         int idx = *index;
 363
 364         while (idx > 0) {
 365                 edge = edges[idx - 1];
 366                 lower = edge->node[LOWER];
 367                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 368                         idx--;
 369                         continue;
 370                 }
 371                 edge = list_entry(edge->list[LOWER].next,
 372                                   struct backref_edge, list[LOWER]);
 373                 edges[idx - 1] = edge;
 374                 *index = idx;
 375                 return edge->node[UPPER];
 376         }
 377         *index = 0;
 378         return NULL;
 379 }
 380
 381 static void unlock_node_buffer(struct backref_node *node)
 382 {
 383         if (node->locked) {
 384                 btrfs_tree_unlock(node->eb);
 385                 node->locked = 0;
 386         }
 387 }
 388
 389 static void drop_node_buffer(struct backref_node *node)
 390 {
 391         if (node->eb) {
 392                 unlock_node_buffer(node);
 393                 free_extent_buffer(node->eb);
 394                 node->eb = NULL;
 395         }
 396 }
 397
 398 static void drop_backref_node(struct backref_cache *tree,
 399                               struct backref_node *node)
 400 {
 401         BUG_ON(!list_empty(&node->upper));
 402
 403         drop_node_buffer(node);
 404         list_del(&node->list);
 405         list_del(&node->lower);
 406         if (!RB_EMPTY_NODE(&node->rb_node))
 407                 rb_erase(&node->rb_node, &tree->rb_root);
 408         free_backref_node(tree, node);
 409 }
 410
 411 /*
 412  * remove a backref node from the backref cache
 413  */
 414 static void remove_backref_node(struct backref_cache *cache,
 415                                 struct backref_node *node)
 416 {
 417         struct backref_node *upper;
 418         struct backref_edge *edge;
 419
 420         if (!node)
 421                 return;
 422
 423         BUG_ON(!node->lowest && !node->detached);
 424         while (!list_empty(&node->upper)) {
 425                 edge = list_entry(node->upper.next, struct backref_edge,
 426                                   list[LOWER]);
 427                 upper = edge->node[UPPER];
 428                 list_del(&edge->list[LOWER]);
 429                 list_del(&edge->list[UPPER]);
 430                 free_backref_edge(cache, edge);
 431
 432                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 433                         BUG_ON(!list_empty(&node->upper));
 434                         drop_backref_node(cache, node);
 435                         node = upper;
 436                         node->lowest = 1;
 437                         continue;
 438                 }
 439                 /*
 440                  * add the node to leaf node list if no other
 441                  * child block cached.
 442                  */
 443                 if (list_empty(&upper->lower)) {
 444                         list_add_tail(&upper->lower, &cache->leaves);
 445                         upper->lowest = 1;
 446                 }
 447         }
 448
 449         drop_backref_node(cache, node);
 450 }
 451
 452 static void update_backref_node(struct backref_cache *cache,
 453                                 struct backref_node *node, u64 bytenr)
 454 {
 455         struct rb_node *rb_node;
 456         rb_erase(&node->rb_node, &cache->rb_root);
 457         node->bytenr = bytenr;
 458         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 459         if (rb_node)
 460                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 461 }
 462
 463 /*
 464  * update backref cache after a transaction commit
 465  */
 466 static int update_backref_cache(struct btrfs_trans_handle *trans,
 467                                 struct backref_cache *cache)
 468 {
 469         struct backref_node *node;
 470         int level = 0;
 471
 472         if (cache->last_trans == 0) {
 473                 cache->last_trans = trans->transid;
 474                 return 0;
 475         }
 476
 477         if (cache->last_trans == trans->transid)
 478                 return 0;
 479
 480         /*
 481          * detached nodes are used to avoid unnecessary backref
 482          * lookup. transaction commit changes the extent tree.
 483          * so the detached nodes are no longer useful.
 484          */
 485         while (!list_empty(&cache->detached)) {
 486                 node = list_entry(cache->detached.next,
 487                                   struct backref_node, list);
 488                 remove_backref_node(cache, node);
 489         }
 490
 491         while (!list_empty(&cache->changed)) {
 492                 node = list_entry(cache->changed.next,
 493                                   struct backref_node, list);
 494                 list_del_init(&node->list);
 495                 BUG_ON(node->pending);
 496                 update_backref_node(cache, node, node->new_bytenr);
 497         }
 498
 499         /*
 500          * some nodes can be left in the pending list if there were
 501          * errors during processing the pending nodes.
 502          */
 503         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 504                 list_for_each_entry(node, &cache->pending[level], list) {
 505                         BUG_ON(!node->pending);
 506                         if (node->bytenr == node->new_bytenr)
 507                                 continue;
 508                         update_backref_node(cache, node, node->new_bytenr);
 509                 }
 510         }
 511
 512         cache->last_trans = 0;
 513         return 1;
 514 }
 515
 516
 517 static int should_ignore_root(struct btrfs_root *root)
 518 {
 519         struct btrfs_root *reloc_root;
 520
 521         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 522                 return 0;
 523
 524         reloc_root = root->reloc_root;
 525         if (!reloc_root)
 526                 return 0;
 527
 528         if (btrfs_header_generation(reloc_root->commit_root) ==
 529             root->fs_info->running_transaction->transid)
 530                 return 0;
 531         /*
 532          * if there is reloc tree and it was created in previous
 533          * transaction backref lookup can find the reloc tree,
 534          * so backref node for the fs tree root is useless for
 535          * relocation.
 536          */
 537         return 1;
 538 }
 539 /*
 540  * find reloc tree by address of tree root
 541  */
 542 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 543                                           u64 bytenr)
 544 {
 545         struct rb_node *rb_node;
 546         struct mapping_node *node;
 547         struct btrfs_root *root = NULL;
 548
 549         spin_lock(&rc->reloc_root_tree.lock);
 550         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 551         if (rb_node) {
 552                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 553                 root = (struct btrfs_root *)node->data;
 554         }
 555         spin_unlock(&rc->reloc_root_tree.lock);
 556         return root;
 557 }
 558
 559 static int is_cowonly_root(u64 root_objectid)
 560 {
 561         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 562             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 563             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 564             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 565             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 566             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 567             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 568             root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
 569             root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
 570                 return 1;
 571         return 0;
 572 }
 573
 574 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 575                                         u64 root_objectid)
 576 {
 577         struct btrfs_key key;
 578
 579         key.objectid = root_objectid;
 580         key.type = BTRFS_ROOT_ITEM_KEY;
 581         if (is_cowonly_root(root_objectid))
 582                 key.offset = 0;
 583         else
 584                 key.offset = (u64)-1;
 585
 586         return btrfs_get_fs_root(fs_info, &key, false);
 587 }
 588
 589 static noinline_for_stack
 590 int find_inline_backref(struct extent_buffer *leaf, int slot,
 591                         unsigned long *ptr, unsigned long *end)
 592 {
 593         struct btrfs_key key;
 594         struct btrfs_extent_item *ei;
 595         struct btrfs_tree_block_info *bi;
 596         u32 item_size;
 597
 598         btrfs_item_key_to_cpu(leaf, &key, slot);
 599
 600         item_size = btrfs_item_size_nr(leaf, slot);
 601         if (item_size < sizeof(*ei)) {
 602                 btrfs_print_v0_err(leaf->fs_info);
 603                 btrfs_handle_fs_error(leaf->fs_info, -EINVAL, NULL);
 604                 return 1;
 605         }
 606         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 607         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 608                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 609
 610         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 611             item_size <= sizeof(*ei) + sizeof(*bi)) {
 612                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 613                 return 1;
 614         }
 615         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 616             item_size <= sizeof(*ei)) {
 617                 WARN_ON(item_size < sizeof(*ei));
 618                 return 1;
 619         }
 620
 621         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 622                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 623                 *ptr = (unsigned long)(bi + 1);
 624         } else {
 625                 *ptr = (unsigned long)(ei + 1);
 626         }
 627         *end = (unsigned long)ei + item_size;
 628         return 0;
 629 }
 630
 631 /*
 632  * build backref tree for a given tree block. root of the backref tree
 633  * corresponds the tree block, leaves of the backref tree correspond
 634  * roots of b-trees that reference the tree block.
 635  *
 636  * the basic idea of this function is check backrefs of a given block
 637  * to find upper level blocks that reference the block, and then check
 638  * backrefs of these upper level blocks recursively. the recursion stop
 639  * when tree root is reached or backrefs for the block is cached.
 640  *
 641  * NOTE: if we find backrefs for a block are cached, we know backrefs
 642  * for all upper level blocks that directly/indirectly reference the
 643  * block are also cached.
 644  */
 645 static noinline_for_stack
 646 struct backref_node *build_backref_tree(struct reloc_control *rc,
 647                                         struct btrfs_key *node_key,
 648                                         int level, u64 bytenr)
 649 {
 650         struct backref_cache *cache = &rc->backref_cache;
 651         struct btrfs_path *path1;
 652         struct btrfs_path *path2;
 653         struct extent_buffer *eb;
 654         struct btrfs_root *root;
 655         struct backref_node *cur;
 656         struct backref_node *upper;
 657         struct backref_node *lower;
 658         struct backref_node *node = NULL;
 659         struct backref_node *exist = NULL;
 660         struct backref_edge *edge;
 661         struct rb_node *rb_node;
 662         struct btrfs_key key;
 663         unsigned long end;
 664         unsigned long ptr;
 665         LIST_HEAD(list);
 666         LIST_HEAD(useless);
 667         int cowonly;
 668         int ret;
 669         int err = 0;
 670         bool need_check = true;
 671
 672         path1 = btrfs_alloc_path();
 673         path2 = btrfs_alloc_path();
 674         if (!path1 || !path2) {
 675                 err = -ENOMEM;
 676                 goto out;
 677         }
 678         path1->reada = READA_FORWARD;
 679         path2->reada = READA_FORWARD;
 680
 681         node = alloc_backref_node(cache);
 682         if (!node) {
 683                 err = -ENOMEM;
 684                 goto out;
 685         }
 686
 687         node->bytenr = bytenr;
 688         node->level = level;
 689         node->lowest = 1;
 690         cur = node;
 691 again:
 692         end = 0;
 693         ptr = 0;
 694         key.objectid = cur->bytenr;
 695         key.type = BTRFS_METADATA_ITEM_KEY;
 696         key.offset = (u64)-1;
 697
 698         path1->search_commit_root = 1;
 699         path1->skip_locking = 1;
 700         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 701                                 0, 0);
 702         if (ret < 0) {
 703                 err = ret;
 704                 goto out;
 705         }
 706         ASSERT(ret);
 707         ASSERT(path1->slots[0]);
 708
 709         path1->slots[0]--;
 710
 711         WARN_ON(cur->checked);
 712         if (!list_empty(&cur->upper)) {
 713                 /*
 714                  * the backref was added previously when processing
 715                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 716                  */
 717                 ASSERT(list_is_singular(&cur->upper));
 718                 edge = list_entry(cur->upper.next, struct backref_edge,
 719                                   list[LOWER]);
 720                 ASSERT(list_empty(&edge->list[UPPER]));
 721                 exist = edge->node[UPPER];
 722                 /*
 723                  * add the upper level block to pending list if we need
 724                  * check its backrefs
 725                  */
 726                 if (!exist->checked)
 727                         list_add_tail(&edge->list[UPPER], &list);
 728         } else {
 729                 exist = NULL;
 730         }
 731
 732         while (1) {
 733                 cond_resched();
 734                 eb = path1->nodes[0];
 735
 736                 if (ptr >= end) {
 737                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 738                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 739                                 if (ret < 0) {
 740                                         err = ret;
 741                                         goto out;
 742                                 }
 743                                 if (ret > 0)
 744                                         break;
 745                                 eb = path1->nodes[0];
 746                         }
 747
 748                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 749                         if (key.objectid != cur->bytenr) {
 750                                 WARN_ON(exist);
 751                                 break;
 752                         }
 753
 754                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 755                             key.type == BTRFS_METADATA_ITEM_KEY) {
 756                                 ret = find_inline_backref(eb, path1->slots[0],
 757                                                           &ptr, &end);
 758                                 if (ret)
 759                                         goto next;
 760                         }
 761                 }
 762
 763                 if (ptr < end) {
 764                         /* update key for inline back ref */
 765                         struct btrfs_extent_inline_ref *iref;
 766                         int type;
 767                         iref = (struct btrfs_extent_inline_ref *)ptr;
 768                         type = btrfs_get_extent_inline_ref_type(eb, iref,
 769                                                         BTRFS_REF_TYPE_BLOCK);
 770                         if (type == BTRFS_REF_TYPE_INVALID) {
 771                                 err = -EUCLEAN;
 772                                 goto out;
 773                         }
 774                         key.type = type;
 775                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 776
 777                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 778                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 779                 }
 780
 781                 if (exist &&
 782                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 783                       exist->owner == key.offset) ||
 784                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 785                       exist->bytenr == key.offset))) {
 786                         exist = NULL;
 787                         goto next;
 788                 }
 789
 790                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 791                         if (key.objectid == key.offset) {
 792                                 /*
 793                                  * only root blocks of reloc trees use
 794                                  * backref of this type.
 795                                  */
 796                                 root = find_reloc_root(rc, cur->bytenr);
 797                                 ASSERT(root);
 798                                 cur->root = root;
 799                                 break;
 800                         }
 801
 802                         edge = alloc_backref_edge(cache);
 803                         if (!edge) {
 804                                 err = -ENOMEM;
 805                                 goto out;
 806                         }
 807                         rb_node = tree_search(&cache->rb_root, key.offset);
 808                         if (!rb_node) {
 809                                 upper = alloc_backref_node(cache);
 810                                 if (!upper) {
 811                                         free_backref_edge(cache, edge);
 812                                         err = -ENOMEM;
 813                                         goto out;
 814                                 }
 815                                 upper->bytenr = key.offset;
 816                                 upper->level = cur->level + 1;
 817                                 /*
 818                                  *  backrefs for the upper level block isn't
 819                                  *  cached, add the block to pending list
 820                                  */
 821                                 list_add_tail(&edge->list[UPPER], &list);
 822                         } else {
 823                                 upper = rb_entry(rb_node, struct backref_node,
 824                                                  rb_node);
 825                                 ASSERT(upper->checked);
 826                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 827                         }
 828                         list_add_tail(&edge->list[LOWER], &cur->upper);
 829                         edge->node[LOWER] = cur;
 830                         edge->node[UPPER] = upper;
 831
 832                         goto next;
 833                 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
 834                         err = -EINVAL;
 835                         btrfs_print_v0_err(rc->extent_root->fs_info);
 836                         btrfs_handle_fs_error(rc->extent_root->fs_info, err,
 837                                               NULL);
 838                         goto out;
 839                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 840                         goto next;
 841                 }
 842
 843                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 844                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 845                 if (IS_ERR(root)) {
 846                         err = PTR_ERR(root);
 847                         goto out;
 848                 }
 849
 850                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 851                         cur->cowonly = 1;
 852
 853                 if (btrfs_root_level(&root->root_item) == cur->level) {
 854                         /* tree root */
 855                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
 856                                cur->bytenr);
 857                         if (should_ignore_root(root))
 858                                 list_add(&cur->list, &useless);
 859                         else
 860                                 cur->root = root;
 861                         break;
 862                 }
 863
 864                 level = cur->level + 1;
 865
 866                 /*
 867                  * searching the tree to find upper level blocks
 868                  * reference the block.
 869                  */
 870                 path2->search_commit_root = 1;
 871                 path2->skip_locking = 1;
 872                 path2->lowest_level = level;
 873                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 874                 path2->lowest_level = 0;
 875                 if (ret < 0) {
 876                         err = ret;
 877                         goto out;
 878                 }
 879                 if (ret > 0 && path2->slots[level] > 0)
 880                         path2->slots[level]--;
 881
 882                 eb = path2->nodes[level];
 883                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
 884                     cur->bytenr) {
 885                         btrfs_err(root->fs_info,
 886         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
 887                                   cur->bytenr, level - 1, root->objectid,
 888                                   node_key->objectid, node_key->type,
 889                                   node_key->offset);
 890                         err = -ENOENT;
 891                         goto out;
 892                 }
 893                 lower = cur;
 894                 need_check = true;
 895                 for (; level < BTRFS_MAX_LEVEL; level++) {
 896                         if (!path2->nodes[level]) {
 897                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
 898                                        lower->bytenr);
 899                                 if (should_ignore_root(root))
 900                                         list_add(&lower->list, &useless);
 901                                 else
 902                                         lower->root = root;
 903                                 break;
 904                         }
 905
 906                         edge = alloc_backref_edge(cache);
 907                         if (!edge) {
 908                                 err = -ENOMEM;
 909                                 goto out;
 910                         }
 911
 912                         eb = path2->nodes[level];
 913                         rb_node = tree_search(&cache->rb_root, eb->start);
 914                         if (!rb_node) {
 915                                 upper = alloc_backref_node(cache);
 916                                 if (!upper) {
 917                                         free_backref_edge(cache, edge);
 918                                         err = -ENOMEM;
 919                                         goto out;
 920                                 }
 921                                 upper->bytenr = eb->start;
 922                                 upper->owner = btrfs_header_owner(eb);
 923                                 upper->level = lower->level + 1;
 924                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 925                                               &root->state))
 926                                         upper->cowonly = 1;
 927
 928                                 /*
 929                                  * if we know the block isn't shared
 930                                  * we can void checking its backrefs.
 931                                  */
 932                                 if (btrfs_block_can_be_shared(root, eb))
 933                                         upper->checked = 0;
 934                                 else
 935                                         upper->checked = 1;
 936
 937                                 /*
 938                                  * add the block to pending list if we
 939                                  * need check its backrefs, we only do this once
 940                                  * while walking up a tree as we will catch
 941                                  * anything else later on.
 942                                  */
 943                                 if (!upper->checked && need_check) {
 944                                         need_check = false;
 945                                         list_add_tail(&edge->list[UPPER],
 946                                                       &list);
 947                                 } else {
 948                                         if (upper->checked)
 949                                                 need_check = true;
 950                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 951                                 }
 952                         } else {
 953                                 upper = rb_entry(rb_node, struct backref_node,
 954                                                  rb_node);
 955                                 ASSERT(upper->checked);
 956                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 957                                 if (!upper->owner)
 958                                         upper->owner = btrfs_header_owner(eb);
 959                         }
 960                         list_add_tail(&edge->list[LOWER], &lower->upper);
 961                         edge->node[LOWER] = lower;
 962                         edge->node[UPPER] = upper;
 963
 964                         if (rb_node)
 965                                 break;
 966                         lower = upper;
 967                         upper = NULL;
 968                 }
 969                 btrfs_release_path(path2);
 970 next:
 971                 if (ptr < end) {
 972                         ptr += btrfs_extent_inline_ref_size(key.type);
 973                         if (ptr >= end) {
 974                                 WARN_ON(ptr > end);
 975                                 ptr = 0;
 976                                 end = 0;
 977                         }
 978                 }
 979                 if (ptr >= end)
 980                         path1->slots[0]++;
 981         }
 982         btrfs_release_path(path1);
 983
 984         cur->checked = 1;
 985         WARN_ON(exist);
 986
 987         /* the pending list isn't empty, take the first block to process */
 988         if (!list_empty(&list)) {
 989                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 990                 list_del_init(&edge->list[UPPER]);
 991                 cur = edge->node[UPPER];
 992                 goto again;
 993         }
 994
 995         /*
 996          * everything goes well, connect backref nodes and insert backref nodes
 997          * into the cache.
 998          */
 999         ASSERT(node->checked);
1000         cowonly = node->cowonly;
1001         if (!cowonly) {
1002                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1003                                       &node->rb_node);
1004                 if (rb_node)
1005                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1006                 list_add_tail(&node->lower, &cache->leaves);
1007         }
1008
1009         list_for_each_entry(edge, &node->upper, list[LOWER])
1010                 list_add_tail(&edge->list[UPPER], &list);
1011
1012         while (!list_empty(&list)) {
1013                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1014                 list_del_init(&edge->list[UPPER]);
1015                 upper = edge->node[UPPER];
1016                 if (upper->detached) {
1017                         list_del(&edge->list[LOWER]);
1018                         lower = edge->node[LOWER];
1019                         free_backref_edge(cache, edge);
1020                         if (list_empty(&lower->upper))
1021                                 list_add(&lower->list, &useless);
1022                         continue;
1023                 }
1024
1025                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1026                         if (upper->lowest) {
1027                                 list_del_init(&upper->lower);
1028                                 upper->lowest = 0;
1029                         }
1030
1031                         list_add_tail(&edge->list[UPPER], &upper->lower);
1032                         continue;
1033                 }
1034
1035                 if (!upper->checked) {
1036                         /*
1037                          * Still want to blow up for developers since this is a
1038                          * logic bug.
1039                          */
1040                         ASSERT(0);
1041                         err = -EINVAL;
1042                         goto out;
1043                 }
1044                 if (cowonly != upper->cowonly) {
1045                         ASSERT(0);
1046                         err = -EINVAL;
1047                         goto out;
1048                 }
1049
1050                 if (!cowonly) {
1051                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1052                                               &upper->rb_node);
1053                         if (rb_node)
1054                                 backref_tree_panic(rb_node, -EEXIST,
1055                                                    upper->bytenr);
1056                 }
1057
1058                 list_add_tail(&edge->list[UPPER], &upper->lower);
1059
1060                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1061                         list_add_tail(&edge->list[UPPER], &list);
1062         }
1063         /*
1064          * process useless backref nodes. backref nodes for tree leaves
1065          * are deleted from the cache. backref nodes for upper level
1066          * tree blocks are left in the cache to avoid unnecessary backref
1067          * lookup.
1068          */
1069         while (!list_empty(&useless)) {
1070                 upper = list_entry(useless.next, struct backref_node, list);
1071                 list_del_init(&upper->list);
1072                 ASSERT(list_empty(&upper->upper));
1073                 if (upper == node)
1074                         node = NULL;
1075                 if (upper->lowest) {
1076                         list_del_init(&upper->lower);
1077                         upper->lowest = 0;
1078                 }
1079                 while (!list_empty(&upper->lower)) {
1080                         edge = list_entry(upper->lower.next,
1081                                           struct backref_edge, list[UPPER]);
1082                         list_del(&edge->list[UPPER]);
1083                         list_del(&edge->list[LOWER]);
1084                         lower = edge->node[LOWER];
1085                         free_backref_edge(cache, edge);
1086
1087                         if (list_empty(&lower->upper))
1088                                 list_add(&lower->list, &useless);
1089                 }
1090                 __mark_block_processed(rc, upper);
1091                 if (upper->level > 0) {
1092                         list_add(&upper->list, &cache->detached);
1093                         upper->detached = 1;
1094                 } else {
1095                         rb_erase(&upper->rb_node, &cache->rb_root);
1096                         free_backref_node(cache, upper);
1097                 }
1098         }
1099 out:
1100         btrfs_free_path(path1);
1101         btrfs_free_path(path2);
1102         if (err) {
1103                 while (!list_empty(&useless)) {
1104                         lower = list_entry(useless.next,
1105                                            struct backref_node, list);
1106                         list_del_init(&lower->list);
1107                 }
1108                 while (!list_empty(&list)) {
1109                         edge = list_first_entry(&list, struct backref_edge,
1110                                                 list[UPPER]);
1111                         list_del(&edge->list[UPPER]);
1112                         list_del(&edge->list[LOWER]);
1113                         lower = edge->node[LOWER];
1114                         upper = edge->node[UPPER];
1115                         free_backref_edge(cache, edge);
1116
1117                         /*
1118                          * Lower is no longer linked to any upper backref nodes
1119                          * and isn't in the cache, we can free it ourselves.
1120                          */
1121                         if (list_empty(&lower->upper) &&
1122                             RB_EMPTY_NODE(&lower->rb_node))
1123                                 list_add(&lower->list, &useless);
1124
1125                         if (!RB_EMPTY_NODE(&upper->rb_node))
1126                                 continue;
1127
1128                         /* Add this guy's upper edges to the list to process */
1129                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1130                                 list_add_tail(&edge->list[UPPER], &list);
1131                         if (list_empty(&upper->upper))
1132                                 list_add(&upper->list, &useless);
1133                 }
1134
1135                 while (!list_empty(&useless)) {
1136                         lower = list_entry(useless.next,
1137                                            struct backref_node, list);
1138                         list_del_init(&lower->list);
1139                         if (lower == node)
1140                                 node = NULL;
1141                         free_backref_node(cache, lower);
1142                 }
1143
1144                 remove_backref_node(cache, node);
1145                 return ERR_PTR(err);
1146         }
1147         ASSERT(!node || !node->detached);
1148         return node;
1149 }
1150
1151 /*
1152  * helper to add backref node for the newly created snapshot.
1153  * the backref node is created by cloning backref node that
1154  * corresponds to root of source tree
1155  */
1156 static int clone_backref_node(struct btrfs_trans_handle *trans,
1157                               struct reloc_control *rc,
1158                               struct btrfs_root *src,
1159                               struct btrfs_root *dest)
1160 {
1161         struct btrfs_root *reloc_root = src->reloc_root;
1162         struct backref_cache *cache = &rc->backref_cache;
1163         struct backref_node *node = NULL;
1164         struct backref_node *new_node;
1165         struct backref_edge *edge;
1166         struct backref_edge *new_edge;
1167         struct rb_node *rb_node;
1168
1169         if (cache->last_trans > 0)
1170                 update_backref_cache(trans, cache);
1171
1172         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1173         if (rb_node) {
1174                 node = rb_entry(rb_node, struct backref_node, rb_node);
1175                 if (node->detached)
1176                         node = NULL;
1177                 else
1178                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1179         }
1180
1181         if (!node) {
1182                 rb_node = tree_search(&cache->rb_root,
1183                                       reloc_root->commit_root->start);
1184                 if (rb_node) {
1185                         node = rb_entry(rb_node, struct backref_node,
1186                                         rb_node);
1187                         BUG_ON(node->detached);
1188                 }
1189         }
1190
1191         if (!node)
1192                 return 0;
1193
1194         new_node = alloc_backref_node(cache);
1195         if (!new_node)
1196                 return -ENOMEM;
1197
1198         new_node->bytenr = dest->node->start;
1199         new_node->level = node->level;
1200         new_node->lowest = node->lowest;
1201         new_node->checked = 1;
1202         new_node->root = dest;
1203
1204         if (!node->lowest) {
1205                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1206                         new_edge = alloc_backref_edge(cache);
1207                         if (!new_edge)
1208                                 goto fail;
1209
1210                         new_edge->node[UPPER] = new_node;
1211                         new_edge->node[LOWER] = edge->node[LOWER];
1212                         list_add_tail(&new_edge->list[UPPER],
1213                                       &new_node->lower);
1214                 }
1215         } else {
1216                 list_add_tail(&new_node->lower, &cache->leaves);
1217         }
1218
1219         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1220                               &new_node->rb_node);
1221         if (rb_node)
1222                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1223
1224         if (!new_node->lowest) {
1225                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1226                         list_add_tail(&new_edge->list[LOWER],
1227                                       &new_edge->node[LOWER]->upper);
1228                 }
1229         }
1230         return 0;
1231 fail:
1232         while (!list_empty(&new_node->lower)) {
1233                 new_edge = list_entry(new_node->lower.next,
1234                                       struct backref_edge, list[UPPER]);
1235                 list_del(&new_edge->list[UPPER]);
1236                 free_backref_edge(cache, new_edge);
1237         }
1238         free_backref_node(cache, new_node);
1239         return -ENOMEM;
1240 }
1241
1242 /*
1243  * helper to add 'address of tree root -> reloc tree' mapping
1244  */
1245 static int __must_check __add_reloc_root(struct btrfs_root *root)
1246 {
1247         struct btrfs_fs_info *fs_info = root->fs_info;
1248         struct rb_node *rb_node;
1249         struct mapping_node *node;
1250         struct reloc_control *rc = fs_info->reloc_ctl;
1251
1252         node = kmalloc(sizeof(*node), GFP_NOFS);
1253         if (!node)
1254                 return -ENOMEM;
1255
1256         node->bytenr = root->commit_root->start;
1257         node->data = root;
1258
1259         spin_lock(&rc->reloc_root_tree.lock);
1260         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1261                               node->bytenr, &node->rb_node);
1262         spin_unlock(&rc->reloc_root_tree.lock);
1263         if (rb_node) {
1264                 btrfs_panic(fs_info, -EEXIST,
1265                             "Duplicate root found for start=%llu while inserting into relocation tree",
1266                             node->bytenr);
1267         }
1268
1269         list_add_tail(&root->root_list, &rc->reloc_roots);
1270         return 0;
1271 }
1272
1273 /*
1274  * helper to delete the 'address of tree root -> reloc tree'
1275  * mapping
1276  */
1277 static void __del_reloc_root(struct btrfs_root *root)
1278 {
1279         struct btrfs_fs_info *fs_info = root->fs_info;
1280         struct rb_node *rb_node;
1281         struct mapping_node *node = NULL;
1282         struct reloc_control *rc = fs_info->reloc_ctl;
1283
1284         if (rc && root->node) {
1285                 spin_lock(&rc->reloc_root_tree.lock);
1286                 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1287                                       root->commit_root->start);
1288                 if (rb_node) {
1289                         node = rb_entry(rb_node, struct mapping_node, rb_node);
1290                         rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1291                         RB_CLEAR_NODE(&node->rb_node);
1292                 }
1293                 spin_unlock(&rc->reloc_root_tree.lock);
1294                 ASSERT(!node || (struct btrfs_root *)node->data == root);
1295         }
1296
1297         spin_lock(&fs_info->trans_lock);
1298         list_del_init(&root->root_list);
1299         spin_unlock(&fs_info->trans_lock);
1300         kfree(node);
1301 }
1302
1303 /*
1304  * helper to update the 'address of tree root -> reloc tree'
1305  * mapping
1306  */
1307 static int __update_reloc_root(struct btrfs_root *root)
1308 {
1309         struct btrfs_fs_info *fs_info = root->fs_info;
1310         struct rb_node *rb_node;
1311         struct mapping_node *node = NULL;
1312         struct reloc_control *rc = fs_info->reloc_ctl;
1313
1314         spin_lock(&rc->reloc_root_tree.lock);
1315         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1316                               root->commit_root->start);
1317         if (rb_node) {
1318                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1319                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1320         }
1321         spin_unlock(&rc->reloc_root_tree.lock);
1322
1323         if (!node)
1324                 return 0;
1325         BUG_ON((struct btrfs_root *)node->data != root);
1326
1327         spin_lock(&rc->reloc_root_tree.lock);
1328         node->bytenr = root->node->start;
1329         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1330                               node->bytenr, &node->rb_node);
1331         spin_unlock(&rc->reloc_root_tree.lock);
1332         if (rb_node)
1333                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1334         return 0;
1335 }
1336
1337 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1338                                         struct btrfs_root *root, u64 objectid)
1339 {
1340         struct btrfs_fs_info *fs_info = root->fs_info;
1341         struct btrfs_root *reloc_root;
1342         struct extent_buffer *eb;
1343         struct btrfs_root_item *root_item;
1344         struct btrfs_key root_key;
1345         int ret;
1346
1347         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1348         BUG_ON(!root_item);
1349
1350         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1351         root_key.type = BTRFS_ROOT_ITEM_KEY;
1352         root_key.offset = objectid;
1353
1354         if (root->root_key.objectid == objectid) {
1355                 u64 commit_root_gen;
1356
1357                 /* called by btrfs_init_reloc_root */
1358                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1359                                       BTRFS_TREE_RELOC_OBJECTID);
1360                 BUG_ON(ret);
1361                 /*
1362                  * Set the last_snapshot field to the generation of the commit
1363                  * root - like this ctree.c:btrfs_block_can_be_shared() behaves
1364                  * correctly (returns true) when the relocation root is created
1365                  * either inside the critical section of a transaction commit
1366                  * (through transaction.c:qgroup_account_snapshot()) and when
1367                  * it's created before the transaction commit is started.
1368                  */
1369                 commit_root_gen = btrfs_header_generation(root->commit_root);
1370                 btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
1371         } else {
1372                 /*
1373                  * called by btrfs_reloc_post_snapshot_hook.
1374                  * the source tree is a reloc tree, all tree blocks
1375                  * modified after it was created have RELOC flag
1376                  * set in their headers. so it's OK to not update
1377                  * the 'last_snapshot'.
1378                  */
1379                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1380                                       BTRFS_TREE_RELOC_OBJECTID);
1381                 BUG_ON(ret);
1382         }
1383
1384         memcpy(root_item, &root->root_item, sizeof(*root_item));
1385         btrfs_set_root_bytenr(root_item, eb->start);
1386         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1387         btrfs_set_root_generation(root_item, trans->transid);
1388
1389         if (root->root_key.objectid == objectid) {
1390                 btrfs_set_root_refs(root_item, 0);
1391                 memset(&root_item->drop_progress, 0,
1392                        sizeof(struct btrfs_disk_key));
1393                 root_item->drop_level = 0;
1394         }
1395
1396         btrfs_tree_unlock(eb);
1397         free_extent_buffer(eb);
1398
1399         ret = btrfs_insert_root(trans, fs_info->tree_root,
1400                                 &root_key, root_item);
1401         BUG_ON(ret);
1402         kfree(root_item);
1403
1404         reloc_root = btrfs_read_fs_root(fs_info->tree_root, &root_key);
1405         BUG_ON(IS_ERR(reloc_root));
1406         reloc_root->last_trans = trans->transid;
1407         return reloc_root;
1408 }
1409
1410 /*
1411  * create reloc tree for a given fs tree. reloc tree is just a
1412  * snapshot of the fs tree with special root objectid.
1413  */
1414 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1415                           struct btrfs_root *root)
1416 {
1417         struct btrfs_fs_info *fs_info = root->fs_info;
1418         struct btrfs_root *reloc_root;
1419         struct reloc_control *rc = fs_info->reloc_ctl;
1420         struct btrfs_block_rsv *rsv;
1421         int clear_rsv = 0;
1422         int ret;
1423
1424         if (root->reloc_root) {
1425                 reloc_root = root->reloc_root;
1426                 reloc_root->last_trans = trans->transid;
1427                 return 0;
1428         }
1429
1430         if (!rc || !rc->create_reloc_tree ||
1431             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1432                 return 0;
1433
1434         if (!trans->reloc_reserved) {
1435                 rsv = trans->block_rsv;
1436                 trans->block_rsv = rc->block_rsv;
1437                 clear_rsv = 1;
1438         }
1439         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1440         if (clear_rsv)
1441                 trans->block_rsv = rsv;
1442
1443         ret = __add_reloc_root(reloc_root);
1444         BUG_ON(ret < 0);
1445         root->reloc_root = reloc_root;
1446         return 0;
1447 }
1448
1449 /*
1450  * update root item of reloc tree
1451  */
1452 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1453                             struct btrfs_root *root)
1454 {
1455         struct btrfs_fs_info *fs_info = root->fs_info;
1456         struct btrfs_root *reloc_root;
1457         struct btrfs_root_item *root_item;
1458         int ret;
1459
1460         if (!root->reloc_root)
1461                 goto out;
1462
1463         reloc_root = root->reloc_root;
1464         root_item = &reloc_root->root_item;
1465
1466         if (fs_info->reloc_ctl->merge_reloc_tree &&
1467             btrfs_root_refs(root_item) == 0) {
1468                 root->reloc_root = NULL;
1469                 __del_reloc_root(reloc_root);
1470         }
1471
1472         if (reloc_root->commit_root != reloc_root->node) {
1473                 __update_reloc_root(reloc_root);
1474                 btrfs_set_root_node(root_item, reloc_root->node);
1475                 free_extent_buffer(reloc_root->commit_root);
1476                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1477         }
1478
1479         ret = btrfs_update_root(trans, fs_info->tree_root,
1480                                 &reloc_root->root_key, root_item);
1481         BUG_ON(ret);
1482
1483 out:
1484         return 0;
1485 }
1486
1487 /*
1488  * helper to find first cached inode with inode number >= objectid
1489  * in a subvolume
1490  */
1491 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1492 {
1493         struct rb_node *node;
1494         struct rb_node *prev;
1495         struct btrfs_inode *entry;
1496         struct inode *inode;
1497
1498         spin_lock(&root->inode_lock);
1499 again:
1500         node = root->inode_tree.rb_node;
1501         prev = NULL;
1502         while (node) {
1503                 prev = node;
1504                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1505
1506                 if (objectid < btrfs_ino(entry))
1507                         node = node->rb_left;
1508                 else if (objectid > btrfs_ino(entry))
1509                         node = node->rb_right;
1510                 else
1511                         break;
1512         }
1513         if (!node) {
1514                 while (prev) {
1515                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1516                         if (objectid <= btrfs_ino(entry)) {
1517                                 node = prev;
1518                                 break;
1519                         }
1520                         prev = rb_next(prev);
1521                 }
1522         }
1523         while (node) {
1524                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1525                 inode = igrab(&entry->vfs_inode);
1526                 if (inode) {
1527                         spin_unlock(&root->inode_lock);
1528                         return inode;
1529                 }
1530
1531                 objectid = btrfs_ino(entry) + 1;
1532                 if (cond_resched_lock(&root->inode_lock))
1533                         goto again;
1534
1535                 node = rb_next(node);
1536         }
1537         spin_unlock(&root->inode_lock);
1538         return NULL;
1539 }
1540
1541 static int in_block_group(u64 bytenr,
1542                           struct btrfs_block_group_cache *block_group)
1543 {
1544         if (bytenr >= block_group->key.objectid &&
1545             bytenr < block_group->key.objectid + block_group->key.offset)
1546                 return 1;
1547         return 0;
1548 }
1549
1550 /*
1551  * get new location of data
1552  */
1553 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1554                             u64 bytenr, u64 num_bytes)
1555 {
1556         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1557         struct btrfs_path *path;
1558         struct btrfs_file_extent_item *fi;
1559         struct extent_buffer *leaf;
1560         int ret;
1561
1562         path = btrfs_alloc_path();
1563         if (!path)
1564                 return -ENOMEM;
1565
1566         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1567         ret = btrfs_lookup_file_extent(NULL, root, path,
1568                         btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);
1569         if (ret < 0)
1570                 goto out;
1571         if (ret > 0) {
1572                 ret = -ENOENT;
1573                 goto out;
1574         }
1575
1576         leaf = path->nodes[0];
1577         fi = btrfs_item_ptr(leaf, path->slots[0],
1578                             struct btrfs_file_extent_item);
1579
1580         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1581                btrfs_file_extent_compression(leaf, fi) ||
1582                btrfs_file_extent_encryption(leaf, fi) ||
1583                btrfs_file_extent_other_encoding(leaf, fi));
1584
1585         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1586                 ret = -EINVAL;
1587                 goto out;
1588         }
1589
1590         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1591         ret = 0;
1592 out:
1593         btrfs_free_path(path);
1594         return ret;
1595 }
1596
1597 /*
1598  * update file extent items in the tree leaf to point to
1599  * the new locations.
1600  */
1601 static noinline_for_stack
1602 int replace_file_extents(struct btrfs_trans_handle *trans,
1603                          struct reloc_control *rc,
1604                          struct btrfs_root *root,
1605                          struct extent_buffer *leaf)
1606 {
1607         struct btrfs_fs_info *fs_info = root->fs_info;
1608         struct btrfs_key key;
1609         struct btrfs_file_extent_item *fi;
1610         struct inode *inode = NULL;
1611         u64 parent;
1612         u64 bytenr;
1613         u64 new_bytenr = 0;
1614         u64 num_bytes;
1615         u64 end;
1616         u32 nritems;
1617         u32 i;
1618         int ret = 0;
1619         int first = 1;
1620         int dirty = 0;
1621
1622         if (rc->stage != UPDATE_DATA_PTRS)
1623                 return 0;
1624
1625         /* reloc trees always use full backref */
1626         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1627                 parent = leaf->start;
1628         else
1629                 parent = 0;
1630
1631         nritems = btrfs_header_nritems(leaf);
1632         for (i = 0; i < nritems; i++) {
1633                 cond_resched();
1634                 btrfs_item_key_to_cpu(leaf, &key, i);
1635                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1636                         continue;
1637                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1638                 if (btrfs_file_extent_type(leaf, fi) ==
1639                     BTRFS_FILE_EXTENT_INLINE)
1640                         continue;
1641                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1642                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1643                 if (bytenr == 0)
1644                         continue;
1645                 if (!in_block_group(bytenr, rc->block_group))
1646                         continue;
1647
1648                 /*
1649                  * if we are modifying block in fs tree, wait for readpage
1650                  * to complete and drop the extent cache
1651                  */
1652                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1653                         if (first) {
1654                                 inode = find_next_inode(root, key.objectid);
1655                                 first = 0;
1656                         } else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
1657                                 btrfs_add_delayed_iput(inode);
1658                                 inode = find_next_inode(root, key.objectid);
1659                         }
1660                         if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
1661                                 end = key.offset +
1662                                       btrfs_file_extent_num_bytes(leaf, fi);
1663                                 WARN_ON(!IS_ALIGNED(key.offset,
1664                                                     fs_info->sectorsize));
1665                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
1666                                 end--;
1667                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1668                                                       key.offset, end);
1669                                 if (!ret)
1670                                         continue;
1671
1672                                 btrfs_drop_extent_cache(BTRFS_I(inode),
1673                                                 key.offset,     end, 1);
1674                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1675                                               key.offset, end);
1676                         }
1677                 }
1678
1679                 ret = get_new_location(rc->data_inode, &new_bytenr,
1680                                        bytenr, num_bytes);
1681                 if (ret) {
1682                         /*
1683                          * Don't have to abort since we've not changed anything
1684                          * in the file extent yet.
1685                          */
1686                         break;
1687                 }
1688
1689                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1690                 dirty = 1;
1691
1692                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1693                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1694                                            num_bytes, parent,
1695                                            btrfs_header_owner(leaf),
1696                                            key.objectid, key.offset);
1697                 if (ret) {
1698                         btrfs_abort_transaction(trans, ret);
1699                         break;
1700                 }
1701
1702                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1703                                         parent, btrfs_header_owner(leaf),
1704                                         key.objectid, key.offset);
1705                 if (ret) {
1706                         btrfs_abort_transaction(trans, ret);
1707                         break;
1708                 }
1709         }
1710         if (dirty)
1711                 btrfs_mark_buffer_dirty(leaf);
1712         if (inode)
1713                 btrfs_add_delayed_iput(inode);
1714         return ret;
1715 }
1716
1717 static noinline_for_stack
1718 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1719                      struct btrfs_path *path, int level)
1720 {
1721         struct btrfs_disk_key key1;
1722         struct btrfs_disk_key key2;
1723         btrfs_node_key(eb, &key1, slot);
1724         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1725         return memcmp(&key1, &key2, sizeof(key1));
1726 }
1727
1728 /*
1729  * try to replace tree blocks in fs tree with the new blocks
1730  * in reloc tree. tree blocks haven't been modified since the
1731  * reloc tree was create can be replaced.
1732  *
1733  * if a block was replaced, level of the block + 1 is returned.
1734  * if no block got replaced, 0 is returned. if there are other
1735  * errors, a negative error number is returned.
1736  */
1737 static noinline_for_stack
1738 int replace_path(struct btrfs_trans_handle *trans,
1739                  struct btrfs_root *dest, struct btrfs_root *src,
1740                  struct btrfs_path *path, struct btrfs_key *next_key,
1741                  int lowest_level, int max_level)
1742 {
1743         struct btrfs_fs_info *fs_info = dest->fs_info;
1744         struct extent_buffer *eb;
1745         struct extent_buffer *parent;
1746         struct btrfs_key key;
1747         u64 old_bytenr;
1748         u64 new_bytenr;
1749         u64 old_ptr_gen;
1750         u64 new_ptr_gen;
1751         u64 last_snapshot;
1752         u32 blocksize;
1753         int cow = 0;
1754         int level;
1755         int ret;
1756         int slot;
1757
1758         ASSERT(src->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1759         ASSERT(dest->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1760
1761         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1762 again:
1763         slot = path->slots[lowest_level];
1764         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1765
1766         eb = btrfs_lock_root_node(dest);
1767         btrfs_set_lock_blocking(eb);
1768         level = btrfs_header_level(eb);
1769
1770         if (level < lowest_level) {
1771                 btrfs_tree_unlock(eb);
1772                 free_extent_buffer(eb);
1773                 return 0;
1774         }
1775
1776         if (cow) {
1777                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1778                 BUG_ON(ret);
1779         }
1780         btrfs_set_lock_blocking(eb);
1781
1782         if (next_key) {
1783                 next_key->objectid = (u64)-1;
1784                 next_key->type = (u8)-1;
1785                 next_key->offset = (u64)-1;
1786         }
1787
1788         parent = eb;
1789         while (1) {
1790                 struct btrfs_key first_key;
1791
1792                 level = btrfs_header_level(parent);
1793                 ASSERT(level >= lowest_level);
1794
1795                 ret = btrfs_bin_search(parent, &key, level, &slot);
1796                 if (ret && slot > 0)
1797                         slot--;
1798
1799                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1800                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1801
1802                 old_bytenr = btrfs_node_blockptr(parent, slot);
1803                 blocksize = fs_info->nodesize;
1804                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1805                 btrfs_node_key_to_cpu(parent, &first_key, slot);
1806
1807                 if (level <= max_level) {
1808                         eb = path->nodes[level];
1809                         new_bytenr = btrfs_node_blockptr(eb,
1810                                                         path->slots[level]);
1811                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1812                                                         path->slots[level]);
1813                 } else {
1814                         new_bytenr = 0;
1815                         new_ptr_gen = 0;
1816                 }
1817
1818                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1819                         ret = level;
1820                         break;
1821                 }
1822
1823                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1824                     memcmp_node_keys(parent, slot, path, level)) {
1825                         if (level <= lowest_level) {
1826                                 ret = 0;
1827                                 break;
1828                         }
1829
1830                         eb = read_tree_block(fs_info, old_bytenr, old_ptr_gen,
1831                                              level - 1, &first_key);
1832                         if (IS_ERR(eb)) {
1833                                 ret = PTR_ERR(eb);
1834                                 break;
1835                         } else if (!extent_buffer_uptodate(eb)) {
1836                                 ret = -EIO;
1837                                 free_extent_buffer(eb);
1838                                 break;
1839                         }
1840                         btrfs_tree_lock(eb);
1841                         if (cow) {
1842                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1843                                                       slot, &eb);
1844                                 BUG_ON(ret);
1845                         }
1846                         btrfs_set_lock_blocking(eb);
1847
1848                         btrfs_tree_unlock(parent);
1849                         free_extent_buffer(parent);
1850
1851                         parent = eb;
1852                         continue;
1853                 }
1854
1855                 if (!cow) {
1856                         btrfs_tree_unlock(parent);
1857                         free_extent_buffer(parent);
1858                         cow = 1;
1859                         goto again;
1860                 }
1861
1862                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1863                                       path->slots[level]);
1864                 btrfs_release_path(path);
1865
1866                 path->lowest_level = level;
1867                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1868                 path->lowest_level = 0;
1869                 BUG_ON(ret);
1870
1871                 /*
1872                  * Info qgroup to trace both subtrees.
1873                  *
1874                  * We must trace both trees.
1875                  * 1) Tree reloc subtree
1876                  *    If not traced, we will leak data numbers
1877                  * 2) Fs subtree
1878                  *    If not traced, we will double count old data
1879                  *    and tree block numbers, if current trans doesn't free
1880                  *    data reloc tree inode.
1881                  */
1882                 ret = btrfs_qgroup_trace_subtree(trans, parent,
1883                                 btrfs_header_generation(parent),
1884                                 btrfs_header_level(parent));
1885                 if (ret < 0)
1886                         break;
1887                 ret = btrfs_qgroup_trace_subtree(trans, path->nodes[level],
1888                                 btrfs_header_generation(path->nodes[level]),
1889                                 btrfs_header_level(path->nodes[level]));
1890                 if (ret < 0)
1891                         break;
1892
1893                 /*
1894                  * swap blocks in fs tree and reloc tree.
1895                  */
1896                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1897                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1898                 btrfs_mark_buffer_dirty(parent);
1899
1900                 btrfs_set_node_blockptr(path->nodes[level],
1901                                         path->slots[level], old_bytenr);
1902                 btrfs_set_node_ptr_generation(path->nodes[level],
1903                                               path->slots[level], old_ptr_gen);
1904                 btrfs_mark_buffer_dirty(path->nodes[level]);
1905
1906                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr,
1907                                         blocksize, path->nodes[level]->start,
1908                                         src->root_key.objectid, level - 1, 0);
1909                 BUG_ON(ret);
1910                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr,
1911                                         blocksize, 0, dest->root_key.objectid,
1912                                         level - 1, 0);
1913                 BUG_ON(ret);
1914
1915                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1916                                         path->nodes[level]->start,
1917                                         src->root_key.objectid, level - 1, 0);
1918                 BUG_ON(ret);
1919
1920                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1921                                         0, dest->root_key.objectid, level - 1,
1922                                         0);
1923                 BUG_ON(ret);
1924
1925                 btrfs_unlock_up_safe(path, 0);
1926
1927                 ret = level;
1928                 break;
1929         }
1930         btrfs_tree_unlock(parent);
1931         free_extent_buffer(parent);
1932         return ret;
1933 }
1934
1935 /*
1936  * helper to find next relocated block in reloc tree
1937  */
1938 static noinline_for_stack
1939 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1940                        int *level)
1941 {
1942         struct extent_buffer *eb;
1943         int i;
1944         u64 last_snapshot;
1945         u32 nritems;
1946
1947         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1948
1949         for (i = 0; i < *level; i++) {
1950                 free_extent_buffer(path->nodes[i]);
1951                 path->nodes[i] = NULL;
1952         }
1953
1954         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1955                 eb = path->nodes[i];
1956                 nritems = btrfs_header_nritems(eb);
1957                 while (path->slots[i] + 1 < nritems) {
1958                         path->slots[i]++;
1959                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1960                             last_snapshot)
1961                                 continue;
1962
1963                         *level = i;
1964                         return 0;
1965                 }
1966                 free_extent_buffer(path->nodes[i]);
1967                 path->nodes[i] = NULL;
1968         }
1969         return 1;
1970 }
1971
1972 /*
1973  * walk down reloc tree to find relocated block of lowest level
1974  */
1975 static noinline_for_stack
1976 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1977                          int *level)
1978 {
1979         struct btrfs_fs_info *fs_info = root->fs_info;
1980         struct extent_buffer *eb = NULL;
1981         int i;
1982         u64 bytenr;
1983         u64 ptr_gen = 0;
1984         u64 last_snapshot;
1985         u32 nritems;
1986
1987         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1988
1989         for (i = *level; i > 0; i--) {
1990                 struct btrfs_key first_key;
1991
1992                 eb = path->nodes[i];
1993                 nritems = btrfs_header_nritems(eb);
1994                 while (path->slots[i] < nritems) {
1995                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1996                         if (ptr_gen > last_snapshot)
1997                                 break;
1998                         path->slots[i]++;
1999                 }
2000                 if (path->slots[i] >= nritems) {
2001                         if (i == *level)
2002                                 break;
2003                         *level = i + 1;
2004                         return 0;
2005                 }
2006                 if (i == 1) {
2007                         *level = i;
2008                         return 0;
2009                 }
2010
2011                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2012                 btrfs_node_key_to_cpu(eb, &first_key, path->slots[i]);
2013                 eb = read_tree_block(fs_info, bytenr, ptr_gen, i - 1,
2014                                      &first_key);
2015                 if (IS_ERR(eb)) {
2016                         return PTR_ERR(eb);
2017                 } else if (!extent_buffer_uptodate(eb)) {
2018                         free_extent_buffer(eb);
2019                         return -EIO;
2020                 }
2021                 BUG_ON(btrfs_header_level(eb) != i - 1);
2022                 path->nodes[i - 1] = eb;
2023                 path->slots[i - 1] = 0;
2024         }
2025         return 1;
2026 }
2027
2028 /*
2029  * invalidate extent cache for file extents whose key in range of
2030  * [min_key, max_key)
2031  */
2032 static int invalidate_extent_cache(struct btrfs_root *root,
2033                                    struct btrfs_key *min_key,
2034                                    struct btrfs_key *max_key)
2035 {
2036         struct btrfs_fs_info *fs_info = root->fs_info;
2037         struct inode *inode = NULL;
2038         u64 objectid;
2039         u64 start, end;
2040         u64 ino;
2041
2042         objectid = min_key->objectid;
2043         while (1) {
2044                 cond_resched();
2045                 iput(inode);
2046
2047                 if (objectid > max_key->objectid)
2048                         break;
2049
2050                 inode = find_next_inode(root, objectid);
2051                 if (!inode)
2052                         break;
2053                 ino = btrfs_ino(BTRFS_I(inode));
2054
2055                 if (ino > max_key->objectid) {
2056                         iput(inode);
2057                         break;
2058                 }
2059
2060                 objectid = ino + 1;
2061                 if (!S_ISREG(inode->i_mode))
2062                         continue;
2063
2064                 if (unlikely(min_key->objectid == ino)) {
2065                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2066                                 continue;
2067                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2068                                 start = 0;
2069                         else {
2070                                 start = min_key->offset;
2071                                 WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));
2072                         }
2073                 } else {
2074                         start = 0;
2075                 }
2076
2077                 if (unlikely(max_key->objectid == ino)) {
2078                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2079                                 continue;
2080                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2081                                 end = (u64)-1;
2082                         } else {
2083                                 if (max_key->offset == 0)
2084                                         continue;
2085                                 end = max_key->offset;
2086                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
2087                                 end--;
2088                         }
2089                 } else {
2090                         end = (u64)-1;
2091                 }
2092
2093                 /* the lock_extent waits for readpage to complete */
2094                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2095                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
2096                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2097         }
2098         return 0;
2099 }
2100
2101 static int find_next_key(struct btrfs_path *path, int level,
2102                          struct btrfs_key *key)
2103
2104 {
2105         while (level < BTRFS_MAX_LEVEL) {
2106                 if (!path->nodes[level])
2107                         break;
2108                 if (path->slots[level] + 1 <
2109                     btrfs_header_nritems(path->nodes[level])) {
2110                         btrfs_node_key_to_cpu(path->nodes[level], key,
2111                                               path->slots[level] + 1);
2112                         return 0;
2113                 }
2114                 level++;
2115         }
2116         return 1;
2117 }
2118
2119 /*
2120  * merge the relocated tree blocks in reloc tree with corresponding
2121  * fs tree.
2122  */
2123 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2124                                                struct btrfs_root *root)
2125 {
2126         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2127         LIST_HEAD(inode_list);
2128         struct btrfs_key key;
2129         struct btrfs_key next_key;
2130         struct btrfs_trans_handle *trans = NULL;
2131         struct btrfs_root *reloc_root;
2132         struct btrfs_root_item *root_item;
2133         struct btrfs_path *path;
2134         struct extent_buffer *leaf;
2135         int level;
2136         int max_level;
2137         int replaced = 0;
2138         int ret;
2139         int err = 0;
2140         u32 min_reserved;
2141
2142         path = btrfs_alloc_path();
2143         if (!path)
2144                 return -ENOMEM;
2145         path->reada = READA_FORWARD;
2146
2147         reloc_root = root->reloc_root;
2148         root_item = &reloc_root->root_item;
2149
2150         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2151                 level = btrfs_root_level(root_item);
2152                 extent_buffer_get(reloc_root->node);
2153                 path->nodes[level] = reloc_root->node;
2154                 path->slots[level] = 0;
2155         } else {
2156                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2157
2158                 level = root_item->drop_level;
2159                 BUG_ON(level == 0);
2160                 path->lowest_level = level;
2161                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2162                 path->lowest_level = 0;
2163                 if (ret < 0) {
2164                         btrfs_free_path(path);
2165                         return ret;
2166                 }
2167
2168                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2169                                       path->slots[level]);
2170                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2171
2172                 btrfs_unlock_up_safe(path, 0);
2173         }
2174
2175         min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2176         memset(&next_key, 0, sizeof(next_key));
2177
2178         while (1) {
2179                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2180                                              BTRFS_RESERVE_FLUSH_ALL);
2181                 if (ret) {
2182                         err = ret;
2183                         goto out;
2184                 }
2185                 trans = btrfs_start_transaction(root, 0);
2186                 if (IS_ERR(trans)) {
2187                         err = PTR_ERR(trans);
2188                         trans = NULL;
2189                         goto out;
2190                 }
2191                 trans->block_rsv = rc->block_rsv;
2192
2193                 replaced = 0;
2194                 max_level = level;
2195
2196                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2197                 if (ret < 0) {
2198                         err = ret;
2199                         goto out;
2200                 }
2201                 if (ret > 0)
2202                         break;
2203
2204                 if (!find_next_key(path, level, &key) &&
2205                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2206                         ret = 0;
2207                 } else {
2208                         ret = replace_path(trans, root, reloc_root, path,
2209                                            &next_key, level, max_level);
2210                 }
2211                 if (ret < 0) {
2212                         err = ret;
2213                         goto out;
2214                 }
2215
2216                 if (ret > 0) {
2217                         level = ret;
2218                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2219                                               path->slots[level]);
2220                         replaced = 1;
2221                 }
2222
2223                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2224                 if (ret > 0)
2225                         break;
2226
2227                 BUG_ON(level == 0);
2228                 /*
2229                  * save the merging progress in the drop_progress.
2230                  * this is OK since root refs == 1 in this case.
2231                  */
2232                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2233                                path->slots[level]);
2234                 root_item->drop_level = level;
2235
2236                 btrfs_end_transaction_throttle(trans);
2237                 trans = NULL;
2238
2239                 btrfs_btree_balance_dirty(fs_info);
2240
2241                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2242                         invalidate_extent_cache(root, &key, &next_key);
2243         }
2244
2245         /*
2246          * handle the case only one block in the fs tree need to be
2247          * relocated and the block is tree root.
2248          */
2249         leaf = btrfs_lock_root_node(root);
2250         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2251         btrfs_tree_unlock(leaf);
2252         free_extent_buffer(leaf);
2253         if (ret < 0)
2254                 err = ret;
2255 out:
2256         btrfs_free_path(path);
2257
2258         if (err == 0) {
2259                 memset(&root_item->drop_progress, 0,
2260                        sizeof(root_item->drop_progress));
2261                 root_item->drop_level = 0;
2262                 btrfs_set_root_refs(root_item, 0);
2263                 btrfs_update_reloc_root(trans, root);
2264         }
2265
2266         if (trans)
2267                 btrfs_end_transaction_throttle(trans);
2268
2269         btrfs_btree_balance_dirty(fs_info);
2270
2271         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2272                 invalidate_extent_cache(root, &key, &next_key);
2273
2274         return err;
2275 }
2276
2277 static noinline_for_stack
2278 int prepare_to_merge(struct reloc_control *rc, int err)
2279 {
2280         struct btrfs_root *root = rc->extent_root;
2281         struct btrfs_fs_info *fs_info = root->fs_info;
2282         struct btrfs_root *reloc_root;
2283         struct btrfs_trans_handle *trans;
2284         LIST_HEAD(reloc_roots);
2285         u64 num_bytes = 0;
2286         int ret;
2287
2288         mutex_lock(&fs_info->reloc_mutex);
2289         rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2290         rc->merging_rsv_size += rc->nodes_relocated * 2;
2291         mutex_unlock(&fs_info->reloc_mutex);
2292
2293 again:
2294         if (!err) {
2295                 num_bytes = rc->merging_rsv_size;
2296                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2297                                           BTRFS_RESERVE_FLUSH_ALL);
2298                 if (ret)
2299                         err = ret;
2300         }
2301
2302         trans = btrfs_join_transaction(rc->extent_root);
2303         if (IS_ERR(trans)) {
2304                 if (!err)
2305                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2306                                                 num_bytes);
2307                 return PTR_ERR(trans);
2308         }
2309
2310         if (!err) {
2311                 if (num_bytes != rc->merging_rsv_size) {
2312                         btrfs_end_transaction(trans);
2313                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2314                                                 num_bytes);
2315                         goto again;
2316                 }
2317         }
2318
2319         rc->merge_reloc_tree = 1;
2320
2321         while (!list_empty(&rc->reloc_roots)) {
2322                 reloc_root = list_entry(rc->reloc_roots.next,
2323                                         struct btrfs_root, root_list);
2324                 list_del_init(&reloc_root->root_list);
2325
2326                 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2327                 BUG_ON(IS_ERR(root));
2328                 BUG_ON(root->reloc_root != reloc_root);
2329
2330                 /*
2331                  * set reference count to 1, so btrfs_recover_relocation
2332                  * knows it should resumes merging
2333                  */
2334                 if (!err)
2335                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2336                 btrfs_update_reloc_root(trans, root);
2337
2338                 list_add(&reloc_root->root_list, &reloc_roots);
2339         }
2340
2341         list_splice(&reloc_roots, &rc->reloc_roots);
2342
2343         if (!err)
2344                 btrfs_commit_transaction(trans);
2345         else
2346                 btrfs_end_transaction(trans);
2347         return err;
2348 }
2349
2350 static noinline_for_stack
2351 void free_reloc_roots(struct list_head *list)
2352 {
2353         struct btrfs_root *reloc_root;
2354
2355         while (!list_empty(list)) {
2356                 reloc_root = list_entry(list->next, struct btrfs_root,
2357                                         root_list);
2358                 __del_reloc_root(reloc_root);
2359                 free_extent_buffer(reloc_root->node);
2360                 free_extent_buffer(reloc_root->commit_root);
2361                 reloc_root->node = NULL;
2362                 reloc_root->commit_root = NULL;
2363         }
2364 }
2365
2366 static noinline_for_stack
2367 void merge_reloc_roots(struct reloc_control *rc)
2368 {
2369         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2370         struct btrfs_root *root;
2371         struct btrfs_root *reloc_root;
2372         LIST_HEAD(reloc_roots);
2373         int found = 0;
2374         int ret = 0;
2375 again:
2376         root = rc->extent_root;
2377
2378         /*
2379          * this serializes us with btrfs_record_root_in_transaction,
2380          * we have to make sure nobody is in the middle of
2381          * adding their roots to the list while we are
2382          * doing this splice
2383          */
2384         mutex_lock(&fs_info->reloc_mutex);
2385         list_splice_init(&rc->reloc_roots, &reloc_roots);
2386         mutex_unlock(&fs_info->reloc_mutex);
2387
2388         while (!list_empty(&reloc_roots)) {
2389                 found = 1;
2390                 reloc_root = list_entry(reloc_roots.next,
2391                                         struct btrfs_root, root_list);
2392
2393                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2394                         root = read_fs_root(fs_info,
2395                                             reloc_root->root_key.offset);
2396                         BUG_ON(IS_ERR(root));
2397                         BUG_ON(root->reloc_root != reloc_root);
2398
2399                         ret = merge_reloc_root(rc, root);
2400                         if (ret) {
2401                                 if (list_empty(&reloc_root->root_list))
2402                                         list_add_tail(&reloc_root->root_list,
2403                                                       &reloc_roots);
2404                                 goto out;
2405                         }
2406                 } else {
2407                         list_del_init(&reloc_root->root_list);
2408                 }
2409
2410                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2411                 if (ret < 0) {
2412                         if (list_empty(&reloc_root->root_list))
2413                                 list_add_tail(&reloc_root->root_list,
2414                                               &reloc_roots);
2415                         goto out;
2416                 }
2417         }
2418
2419         if (found) {
2420                 found = 0;
2421                 goto again;
2422         }
2423 out:
2424         if (ret) {
2425                 btrfs_handle_fs_error(fs_info, ret, NULL);
2426                 if (!list_empty(&reloc_roots))
2427                         free_reloc_roots(&reloc_roots);
2428
2429                 /* new reloc root may be added */
2430                 mutex_lock(&fs_info->reloc_mutex);
2431                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2432                 mutex_unlock(&fs_info->reloc_mutex);
2433                 if (!list_empty(&reloc_roots))
2434                         free_reloc_roots(&reloc_roots);
2435         }
2436
2437         /*
2438          * We used to have
2439          *
2440          * BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2441          *
2442          * here, but it's wrong.  If we fail to start the transaction in
2443          * prepare_to_merge() we will have only 0 ref reloc roots, none of which
2444          * have actually been removed from the reloc_root_tree rb tree.  This is
2445          * fine because we're bailing here, and we hold a reference on the root
2446          * for the list that holds it, so these roots will be cleaned up when we
2447          * do the reloc_dirty_list afterwards.  Meanwhile the root->reloc_root
2448          * will be cleaned up on unmount.
2449          *
2450          * The remaining nodes will be cleaned up by free_reloc_control.
2451          */
2452 }
2453
2454 static void free_block_list(struct rb_root *blocks)
2455 {
2456         struct tree_block *block;
2457         struct rb_node *rb_node;
2458         while ((rb_node = rb_first(blocks))) {
2459                 block = rb_entry(rb_node, struct tree_block, rb_node);
2460                 rb_erase(rb_node, blocks);
2461                 kfree(block);
2462         }
2463 }
2464
2465 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2466                                       struct btrfs_root *reloc_root)
2467 {
2468         struct btrfs_fs_info *fs_info = reloc_root->fs_info;
2469         struct btrfs_root *root;
2470
2471         if (reloc_root->last_trans == trans->transid)
2472                 return 0;
2473
2474         root = read_fs_root(fs_info, reloc_root->root_key.offset);
2475         BUG_ON(IS_ERR(root));
2476         BUG_ON(root->reloc_root != reloc_root);
2477
2478         return btrfs_record_root_in_trans(trans, root);
2479 }
2480
2481 static noinline_for_stack
2482 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2483                                      struct reloc_control *rc,
2484                                      struct backref_node *node,
2485                                      struct backref_edge *edges[])
2486 {
2487         struct backref_node *next;
2488         struct btrfs_root *root;
2489         int index = 0;
2490
2491         next = node;
2492         while (1) {
2493                 cond_resched();
2494                 next = walk_up_backref(next, edges, &index);
2495                 root = next->root;
2496                 BUG_ON(!root);
2497                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2498
2499                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2500                         record_reloc_root_in_trans(trans, root);
2501                         break;
2502                 }
2503
2504                 btrfs_record_root_in_trans(trans, root);
2505                 root = root->reloc_root;
2506
2507                 if (next->new_bytenr != root->node->start) {
2508                         BUG_ON(next->new_bytenr);
2509                         BUG_ON(!list_empty(&next->list));
2510                         next->new_bytenr = root->node->start;
2511                         next->root = root;
2512                         list_add_tail(&next->list,
2513                                       &rc->backref_cache.changed);
2514                         __mark_block_processed(rc, next);
2515                         break;
2516                 }
2517
2518                 WARN_ON(1);
2519                 root = NULL;
2520                 next = walk_down_backref(edges, &index);
2521                 if (!next || next->level <= node->level)
2522                         break;
2523         }
2524         if (!root)
2525                 return NULL;
2526
2527         next = node;
2528         /* setup backref node path for btrfs_reloc_cow_block */
2529         while (1) {
2530                 rc->backref_cache.path[next->level] = next;
2531                 if (--index < 0)
2532                         break;
2533                 next = edges[index]->node[UPPER];
2534         }
2535         return root;
2536 }
2537
2538 /*
2539  * select a tree root for relocation. return NULL if the block
2540  * is reference counted. we should use do_relocation() in this
2541  * case. return a tree root pointer if the block isn't reference
2542  * counted. return -ENOENT if the block is root of reloc tree.
2543  */
2544 static noinline_for_stack
2545 struct btrfs_root *select_one_root(struct backref_node *node)
2546 {
2547         struct backref_node *next;
2548         struct btrfs_root *root;
2549         struct btrfs_root *fs_root = NULL;
2550         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2551         int index = 0;
2552
2553         next = node;
2554         while (1) {
2555                 cond_resched();
2556                 next = walk_up_backref(next, edges, &index);
2557                 root = next->root;
2558                 BUG_ON(!root);
2559
2560                 /* no other choice for non-references counted tree */
2561                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2562                         return root;
2563
2564                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2565                         fs_root = root;
2566
2567                 if (next != node)
2568                         return NULL;
2569
2570                 next = walk_down_backref(edges, &index);
2571                 if (!next || next->level <= node->level)
2572                         break;
2573         }
2574
2575         if (!fs_root)
2576                 return ERR_PTR(-ENOENT);
2577         return fs_root;
2578 }
2579
2580 static noinline_for_stack
2581 u64 calcu_metadata_size(struct reloc_control *rc,
2582                         struct backref_node *node, int reserve)
2583 {
2584         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2585         struct backref_node *next = node;
2586         struct backref_edge *edge;
2587         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2588         u64 num_bytes = 0;
2589         int index = 0;
2590
2591         BUG_ON(reserve && node->processed);
2592
2593         while (next) {
2594                 cond_resched();
2595                 while (1) {
2596                         if (next->processed && (reserve || next != node))
2597                                 break;
2598
2599                         num_bytes += fs_info->nodesize;
2600
2601                         if (list_empty(&next->upper))
2602                                 break;
2603
2604                         edge = list_entry(next->upper.next,
2605                                           struct backref_edge, list[LOWER]);
2606                         edges[index++] = edge;
2607                         next = edge->node[UPPER];
2608                 }
2609                 next = walk_down_backref(edges, &index);
2610         }
2611         return num_bytes;
2612 }
2613
2614 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2615                                   struct reloc_control *rc,
2616                                   struct backref_node *node)
2617 {
2618         struct btrfs_root *root = rc->extent_root;
2619         struct btrfs_fs_info *fs_info = root->fs_info;
2620         u64 num_bytes;
2621         int ret;
2622         u64 tmp;
2623
2624         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2625
2626         trans->block_rsv = rc->block_rsv;
2627         rc->reserved_bytes += num_bytes;
2628
2629         /*
2630          * We are under a transaction here so we can only do limited flushing.
2631          * If we get an enospc just kick back -EAGAIN so we know to drop the
2632          * transaction and try to refill when we can flush all the things.
2633          */
2634         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2635                                 BTRFS_RESERVE_FLUSH_LIMIT);
2636         if (ret) {
2637                 tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
2638                 while (tmp <= rc->reserved_bytes)
2639                         tmp <<= 1;
2640                 /*
2641                  * only one thread can access block_rsv at this point,
2642                  * so we don't need hold lock to protect block_rsv.
2643                  * we expand more reservation size here to allow enough
2644                  * space for relocation and we will return eailer in
2645                  * enospc case.
2646                  */
2647                 rc->block_rsv->size = tmp + fs_info->nodesize *
2648                                       RELOCATION_RESERVED_NODES;
2649                 return -EAGAIN;
2650         }
2651
2652         return 0;
2653 }
2654
2655 /*
2656  * relocate a block tree, and then update pointers in upper level
2657  * blocks that reference the block to point to the new location.
2658  *
2659  * if called by link_to_upper, the block has already been relocated.
2660  * in that case this function just updates pointers.
2661  */
2662 static int do_relocation(struct btrfs_trans_handle *trans,
2663                          struct reloc_control *rc,
2664                          struct backref_node *node,
2665                          struct btrfs_key *key,
2666                          struct btrfs_path *path, int lowest)
2667 {
2668         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2669         struct backref_node *upper;
2670         struct backref_edge *edge;
2671         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2672         struct btrfs_root *root;
2673         struct extent_buffer *eb;
2674         u32 blocksize;
2675         u64 bytenr;
2676         u64 generation;
2677         int slot;
2678         int ret;
2679         int err = 0;
2680
2681         BUG_ON(lowest && node->eb);
2682
2683         path->lowest_level = node->level + 1;
2684         rc->backref_cache.path[node->level] = node;
2685         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2686                 struct btrfs_key first_key;
2687
2688                 cond_resched();
2689
2690                 upper = edge->node[UPPER];
2691                 root = select_reloc_root(trans, rc, upper, edges);
2692                 BUG_ON(!root);
2693
2694                 if (upper->eb && !upper->locked) {
2695                         if (!lowest) {
2696                                 ret = btrfs_bin_search(upper->eb, key,
2697                                                        upper->level, &slot);
2698                                 BUG_ON(ret);
2699                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2700                                 if (node->eb->start == bytenr)
2701                                         goto next;
2702                         }
2703                         drop_node_buffer(upper);
2704                 }
2705
2706                 if (!upper->eb) {
2707                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2708                         if (ret) {
2709                                 if (ret < 0)
2710                                         err = ret;
2711                                 else
2712                                         err = -ENOENT;
2713
2714                                 btrfs_release_path(path);
2715                                 break;
2716                         }
2717
2718                         if (!upper->eb) {
2719                                 upper->eb = path->nodes[upper->level];
2720                                 path->nodes[upper->level] = NULL;
2721                         } else {
2722                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2723                         }
2724
2725                         upper->locked = 1;
2726                         path->locks[upper->level] = 0;
2727
2728                         slot = path->slots[upper->level];
2729                         btrfs_release_path(path);
2730                 } else {
2731                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2732                                                &slot);
2733                         BUG_ON(ret);
2734                 }
2735
2736                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2737                 if (lowest) {
2738                         if (bytenr != node->bytenr) {
2739                                 btrfs_err(root->fs_info,
2740                 "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
2741                                           bytenr, node->bytenr, slot,
2742                                           upper->eb->start);
2743                                 err = -EIO;
2744                                 goto next;
2745                         }
2746                 } else {
2747                         if (node->eb->start == bytenr)
2748                                 goto next;
2749                 }
2750
2751                 blocksize = root->fs_info->nodesize;
2752                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2753                 btrfs_node_key_to_cpu(upper->eb, &first_key, slot);
2754                 eb = read_tree_block(fs_info, bytenr, generation,
2755                                      upper->level - 1, &first_key);
2756                 if (IS_ERR(eb)) {
2757                         err = PTR_ERR(eb);
2758                         goto next;
2759                 } else if (!extent_buffer_uptodate(eb)) {
2760                         free_extent_buffer(eb);
2761                         err = -EIO;
2762                         goto next;
2763                 }
2764                 btrfs_tree_lock(eb);
2765                 btrfs_set_lock_blocking(eb);
2766
2767                 if (!node->eb) {
2768                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2769                                               slot, &eb);
2770                         btrfs_tree_unlock(eb);
2771                         free_extent_buffer(eb);
2772                         if (ret < 0) {
2773                                 err = ret;
2774                                 goto next;
2775                         }
2776                         BUG_ON(node->eb != eb);
2777                 } else {
2778                         btrfs_set_node_blockptr(upper->eb, slot,
2779                                                 node->eb->start);
2780                         btrfs_set_node_ptr_generation(upper->eb, slot,
2781                                                       trans->transid);
2782                         btrfs_mark_buffer_dirty(upper->eb);
2783
2784                         ret = btrfs_inc_extent_ref(trans, root,
2785                                                 node->eb->start, blocksize,
2786                                                 upper->eb->start,
2787                                                 btrfs_header_owner(upper->eb),
2788                                                 node->level, 0);
2789                         BUG_ON(ret);
2790
2791                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2792                         BUG_ON(ret);
2793                 }
2794 next:
2795                 if (!upper->pending)
2796                         drop_node_buffer(upper);
2797                 else
2798                         unlock_node_buffer(upper);
2799                 if (err)
2800                         break;
2801         }
2802
2803         if (!err && node->pending) {
2804                 drop_node_buffer(node);
2805                 list_move_tail(&node->list, &rc->backref_cache.changed);
2806                 node->pending = 0;
2807         }
2808
2809         path->lowest_level = 0;
2810         BUG_ON(err == -ENOSPC);
2811         return err;
2812 }
2813
2814 static int link_to_upper(struct btrfs_trans_handle *trans,
2815                          struct reloc_control *rc,
2816                          struct backref_node *node,
2817                          struct btrfs_path *path)
2818 {
2819         struct btrfs_key key;
2820
2821         btrfs_node_key_to_cpu(node->eb, &key, 0);
2822         return do_relocation(trans, rc, node, &key, path, 0);
2823 }
2824
2825 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2826                                 struct reloc_control *rc,
2827                                 struct btrfs_path *path, int err)
2828 {
2829         LIST_HEAD(list);
2830         struct backref_cache *cache = &rc->backref_cache;
2831         struct backref_node *node;
2832         int level;
2833         int ret;
2834
2835         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2836                 while (!list_empty(&cache->pending[level])) {
2837                         node = list_entry(cache->pending[level].next,
2838                                           struct backref_node, list);
2839                         list_move_tail(&node->list, &list);
2840                         BUG_ON(!node->pending);
2841
2842                         if (!err) {
2843                                 ret = link_to_upper(trans, rc, node, path);
2844                                 if (ret < 0)
2845                                         err = ret;
2846                         }
2847                 }
2848                 list_splice_init(&list, &cache->pending[level]);
2849         }
2850         return err;
2851 }
2852
2853 static void mark_block_processed(struct reloc_control *rc,
2854                                  u64 bytenr, u32 blocksize)
2855 {
2856         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2857                         EXTENT_DIRTY);
2858 }
2859
2860 static void __mark_block_processed(struct reloc_control *rc,
2861                                    struct backref_node *node)
2862 {
2863         u32 blocksize;
2864         if (node->level == 0 ||
2865             in_block_group(node->bytenr, rc->block_group)) {
2866                 blocksize = rc->extent_root->fs_info->nodesize;
2867                 mark_block_processed(rc, node->bytenr, blocksize);
2868         }
2869         node->processed = 1;
2870 }
2871
2872 /*
2873  * mark a block and all blocks directly/indirectly reference the block
2874  * as processed.
2875  */
2876 static void update_processed_blocks(struct reloc_control *rc,
2877                                     struct backref_node *node)
2878 {
2879         struct backref_node *next = node;
2880         struct backref_edge *edge;
2881         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2882         int index = 0;
2883
2884         while (next) {
2885                 cond_resched();
2886                 while (1) {
2887                         if (next->processed)
2888                                 break;
2889
2890                         __mark_block_processed(rc, next);
2891
2892                         if (list_empty(&next->upper))
2893                                 break;
2894
2895                         edge = list_entry(next->upper.next,
2896                                           struct backref_edge, list[LOWER]);
2897                         edges[index++] = edge;
2898                         next = edge->node[UPPER];
2899                 }
2900                 next = walk_down_backref(edges, &index);
2901         }
2902 }
2903
2904 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2905 {
2906         u32 blocksize = rc->extent_root->fs_info->nodesize;
2907
2908         if (test_range_bit(&rc->processed_blocks, bytenr,
2909                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2910                 return 1;
2911         return 0;
2912 }
2913
2914 static int get_tree_block_key(struct btrfs_fs_info *fs_info,
2915                               struct tree_block *block)
2916 {
2917         struct extent_buffer *eb;
2918
2919         BUG_ON(block->key_ready);
2920         eb = read_tree_block(fs_info, block->bytenr, block->key.offset,
2921                              block->level, NULL);
2922         if (IS_ERR(eb)) {
2923                 return PTR_ERR(eb);
2924         } else if (!extent_buffer_uptodate(eb)) {
2925                 free_extent_buffer(eb);
2926                 return -EIO;
2927         }
2928         WARN_ON(btrfs_header_level(eb) != block->level);
2929         if (block->level == 0)
2930                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2931         else
2932                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2933         free_extent_buffer(eb);
2934         block->key_ready = 1;
2935         return 0;
2936 }
2937
2938 /*
2939  * helper function to relocate a tree block
2940  */
2941 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2942                                 struct reloc_control *rc,
2943                                 struct backref_node *node,
2944                                 struct btrfs_key *key,
2945                                 struct btrfs_path *path)
2946 {
2947         struct btrfs_root *root;
2948         int ret = 0;
2949
2950         if (!node)
2951                 return 0;
2952
2953         BUG_ON(node->processed);
2954         root = select_one_root(node);
2955         if (root == ERR_PTR(-ENOENT)) {
2956                 update_processed_blocks(rc, node);
2957                 goto out;
2958         }
2959
2960         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2961                 ret = reserve_metadata_space(trans, rc, node);
2962                 if (ret)
2963                         goto out;
2964         }
2965
2966         if (root) {
2967                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2968                         BUG_ON(node->new_bytenr);
2969                         BUG_ON(!list_empty(&node->list));
2970                         btrfs_record_root_in_trans(trans, root);
2971                         root = root->reloc_root;
2972                         node->new_bytenr = root->node->start;
2973                         node->root = root;
2974                         list_add_tail(&node->list, &rc->backref_cache.changed);
2975                 } else {
2976                         path->lowest_level = node->level;
2977                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2978                         btrfs_release_path(path);
2979                         if (ret > 0)
2980                                 ret = 0;
2981                 }
2982                 if (!ret)
2983                         update_processed_blocks(rc, node);
2984         } else {
2985                 ret = do_relocation(trans, rc, node, key, path, 1);
2986         }
2987 out:
2988         if (ret || node->level == 0 || node->cowonly)
2989                 remove_backref_node(&rc->backref_cache, node);
2990         return ret;
2991 }
2992
2993 /*
2994  * relocate a list of blocks
2995  */
2996 static noinline_for_stack
2997 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2998                          struct reloc_control *rc, struct rb_root *blocks)
2999 {
3000         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3001         struct backref_node *node;
3002         struct btrfs_path *path;
3003         struct tree_block *block;
3004         struct rb_node *rb_node;
3005         int ret;
3006         int err = 0;
3007
3008         path = btrfs_alloc_path();
3009         if (!path) {
3010                 err = -ENOMEM;
3011                 goto out_free_blocks;
3012         }
3013
3014         rb_node = rb_first(blocks);
3015         while (rb_node) {
3016                 block = rb_entry(rb_node, struct tree_block, rb_node);
3017                 if (!block->key_ready)
3018                         readahead_tree_block(fs_info, block->bytenr);
3019                 rb_node = rb_next(rb_node);
3020         }
3021
3022         rb_node = rb_first(blocks);
3023         while (rb_node) {
3024                 block = rb_entry(rb_node, struct tree_block, rb_node);
3025                 if (!block->key_ready) {
3026                         err = get_tree_block_key(fs_info, block);
3027                         if (err)
3028                                 goto out_free_path;
3029                 }
3030                 rb_node = rb_next(rb_node);
3031         }
3032
3033         rb_node = rb_first(blocks);
3034         while (rb_node) {
3035                 block = rb_entry(rb_node, struct tree_block, rb_node);
3036
3037                 node = build_backref_tree(rc, &block->key,
3038                                           block->level, block->bytenr);
3039                 if (IS_ERR(node)) {
3040                         err = PTR_ERR(node);
3041                         goto out;
3042                 }
3043
3044                 ret = relocate_tree_block(trans, rc, node, &block->key,
3045                                           path);
3046                 if (ret < 0) {
3047                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3048                                 err = ret;
3049                         goto out;
3050                 }
3051                 rb_node = rb_next(rb_node);
3052         }
3053 out:
3054         err = finish_pending_nodes(trans, rc, path, err);
3055
3056 out_free_path:
3057         btrfs_free_path(path);
3058 out_free_blocks:
3059         free_block_list(blocks);
3060         return err;
3061 }
3062
3063 static noinline_for_stack
3064 int prealloc_file_extent_cluster(struct inode *inode,
3065                                  struct file_extent_cluster *cluster)
3066 {
3067         u64 alloc_hint = 0;
3068         u64 start;
3069         u64 end;
3070         u64 offset = BTRFS_I(inode)->index_cnt;
3071         u64 num_bytes;
3072         int nr = 0;
3073         int ret = 0;
3074         u64 prealloc_start = cluster->start - offset;
3075         u64 prealloc_end = cluster->end - offset;
3076         u64 cur_offset;
3077         struct extent_changeset *data_reserved = NULL;
3078
3079         BUG_ON(cluster->start != cluster->boundary[0]);
3080         inode_lock(inode);
3081
3082         ret = btrfs_check_data_free_space(inode, &data_reserved, prealloc_start,
3083                                           prealloc_end + 1 - prealloc_start);
3084         if (ret)
3085                 goto out;
3086
3087         cur_offset = prealloc_start;
3088         while (nr < cluster->nr) {
3089                 start = cluster->boundary[nr] - offset;
3090                 if (nr + 1 < cluster->nr)
3091                         end = cluster->boundary[nr + 1] - 1 - offset;
3092                 else
3093                         end = cluster->end - offset;
3094
3095                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3096                 num_bytes = end + 1 - start;
3097                 if (cur_offset < start)
3098                         btrfs_free_reserved_data_space(inode, data_reserved,
3099                                         cur_offset, start - cur_offset);
3100                 ret = btrfs_prealloc_file_range(inode, 0, start,
3101                                                 num_bytes, num_bytes,
3102                                                 end + 1, &alloc_hint);
3103                 cur_offset = end + 1;
3104                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3105                 if (ret)
3106                         break;
3107                 nr++;
3108         }
3109         if (cur_offset < prealloc_end)
3110                 btrfs_free_reserved_data_space(inode, data_reserved,
3111                                 cur_offset, prealloc_end + 1 - cur_offset);
3112 out:
3113         inode_unlock(inode);
3114         extent_changeset_free(data_reserved);
3115         return ret;
3116 }
3117
3118 static noinline_for_stack
3119 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3120                          u64 block_start)
3121 {
3122         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3123         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3124         struct extent_map *em;
3125         int ret = 0;
3126
3127         em = alloc_extent_map();
3128         if (!em)
3129                 return -ENOMEM;
3130
3131         em->start = start;
3132         em->len = end + 1 - start;
3133         em->block_len = em->len;
3134         em->block_start = block_start;
3135         em->bdev = fs_info->fs_devices->latest_bdev;
3136         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3137
3138         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3139         while (1) {
3140                 write_lock(&em_tree->lock);
3141                 ret = add_extent_mapping(em_tree, em, 0);
3142                 write_unlock(&em_tree->lock);
3143                 if (ret != -EEXIST) {
3144                         free_extent_map(em);
3145                         break;
3146                 }
3147                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
3148         }
3149         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3150         return ret;
3151 }
3152
3153 static int relocate_file_extent_cluster(struct inode *inode,
3154                                         struct file_extent_cluster *cluster)
3155 {
3156         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3157         u64 page_start;
3158         u64 page_end;
3159         u64 offset = BTRFS_I(inode)->index_cnt;
3160         unsigned long index;
3161         unsigned long last_index;
3162         struct page *page;
3163         struct file_ra_state *ra;
3164         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3165         int nr = 0;
3166         int ret = 0;
3167
3168         if (!cluster->nr)
3169                 return 0;
3170
3171         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3172         if (!ra)
3173                 return -ENOMEM;
3174
3175         ret = prealloc_file_extent_cluster(inode, cluster);
3176         if (ret)
3177                 goto out;
3178
3179         file_ra_state_init(ra, inode->i_mapping);
3180
3181         ret = setup_extent_mapping(inode, cluster->start - offset,
3182                                    cluster->end - offset, cluster->start);
3183         if (ret)
3184                 goto out;
3185
3186         index = (cluster->start - offset) >> PAGE_SHIFT;
3187         last_index = (cluster->end - offset) >> PAGE_SHIFT;
3188         while (index <= last_index) {
3189                 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
3190                                 PAGE_SIZE);
3191                 if (ret)
3192                         goto out;
3193
3194                 page = find_lock_page(inode->i_mapping, index);
3195                 if (!page) {
3196                         page_cache_sync_readahead(inode->i_mapping,
3197                                                   ra, NULL, index,
3198                                                   last_index + 1 - index);
3199                         page = find_or_create_page(inode->i_mapping, index,
3200                                                    mask);
3201                         if (!page) {
3202                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3203                                                         PAGE_SIZE, true);
3204                                 btrfs_delalloc_release_extents(BTRFS_I(inode),
3205                                                         PAGE_SIZE);
3206                                 ret = -ENOMEM;
3207                                 goto out;
3208                         }
3209                 }
3210
3211                 if (PageReadahead(page)) {
3212                         page_cache_async_readahead(inode->i_mapping,
3213                                                    ra, NULL, page, index,
3214                                                    last_index + 1 - index);
3215                 }
3216
3217                 if (!PageUptodate(page)) {
3218                         btrfs_readpage(NULL, page);
3219                         lock_page(page);
3220                         if (!PageUptodate(page)) {
3221                                 unlock_page(page);
3222                                 put_page(page);
3223                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3224                                                         PAGE_SIZE, true);
3225                                 btrfs_delalloc_release_extents(BTRFS_I(inode),
3226                                                                PAGE_SIZE);
3227                                 ret = -EIO;
3228                                 goto out;
3229                         }
3230                 }
3231
3232                 page_start = page_offset(page);
3233                 page_end = page_start + PAGE_SIZE - 1;
3234
3235                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3236
3237                 set_page_extent_mapped(page);
3238
3239                 if (nr < cluster->nr &&
3240                     page_start + offset == cluster->boundary[nr]) {
3241                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3242                                         page_start, page_end,
3243                                         EXTENT_BOUNDARY);
3244                         nr++;
3245                 }
3246
3247                 ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
3248                                                 NULL, 0);
3249                 if (ret) {
3250                         unlock_page(page);
3251                         put_page(page);
3252                         btrfs_delalloc_release_metadata(BTRFS_I(inode),
3253                                                          PAGE_SIZE, true);
3254                         btrfs_delalloc_release_extents(BTRFS_I(inode),
3255                                                        PAGE_SIZE);
3256
3257                         clear_extent_bits(&BTRFS_I(inode)->io_tree,
3258                                           page_start, page_end,
3259                                           EXTENT_LOCKED | EXTENT_BOUNDARY);
3260                         goto out;
3261
3262                 }
3263                 set_page_dirty(page);
3264
3265                 unlock_extent(&BTRFS_I(inode)->io_tree,
3266                               page_start, page_end);
3267                 unlock_page(page);
3268                 put_page(page);
3269
3270                 index++;
3271                 btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
3272                 balance_dirty_pages_ratelimited(inode->i_mapping);
3273                 btrfs_throttle(fs_info);
3274         }
3275         WARN_ON(nr != cluster->nr);
3276 out:
3277         kfree(ra);
3278         return ret;
3279 }
3280
3281 static noinline_for_stack
3282 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3283                          struct file_extent_cluster *cluster)
3284 {
3285         int ret;
3286
3287         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3288                 ret = relocate_file_extent_cluster(inode, cluster);
3289                 if (ret)
3290                         return ret;
3291                 cluster->nr = 0;
3292         }
3293
3294         if (!cluster->nr)
3295                 cluster->start = extent_key->objectid;
3296         else
3297                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3298         cluster->end = extent_key->objectid + extent_key->offset - 1;
3299         cluster->boundary[cluster->nr] = extent_key->objectid;
3300         cluster->nr++;
3301
3302         if (cluster->nr >= MAX_EXTENTS) {
3303                 ret = relocate_file_extent_cluster(inode, cluster);
3304                 if (ret)
3305                         return ret;
3306                 cluster->nr = 0;
3307         }
3308         return 0;
3309 }
3310
3311 /*
3312  * helper to add a tree block to the list.
3313  * the major work is getting the generation and level of the block
3314  */
3315 static int add_tree_block(struct reloc_control *rc,
3316                           struct btrfs_key *extent_key,
3317                           struct btrfs_path *path,
3318                           struct rb_root *blocks)
3319 {
3320         struct extent_buffer *eb;
3321         struct btrfs_extent_item *ei;
3322         struct btrfs_tree_block_info *bi;
3323         struct tree_block *block;
3324         struct rb_node *rb_node;
3325         u32 item_size;
3326         int level = -1;
3327         u64 generation;
3328
3329         eb =  path->nodes[0];
3330         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3331
3332         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3333             item_size >= sizeof(*ei) + sizeof(*bi)) {
3334                 ei = btrfs_item_ptr(eb, path->slots[0],
3335                                 struct btrfs_extent_item);
3336                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3337                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3338                         level = btrfs_tree_block_level(eb, bi);
3339                 } else {
3340                         level = (int)extent_key->offset;
3341                 }
3342                 generation = btrfs_extent_generation(eb, ei);
3343         } else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
3344                 btrfs_print_v0_err(eb->fs_info);
3345                 btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3346                 return -EINVAL;
3347         } else {
3348                 BUG();
3349         }
3350
3351         btrfs_release_path(path);
3352
3353         BUG_ON(level == -1);
3354
3355         block = kmalloc(sizeof(*block), GFP_NOFS);
3356         if (!block)
3357                 return -ENOMEM;
3358
3359         block->bytenr = extent_key->objectid;
3360         block->key.objectid = rc->extent_root->fs_info->nodesize;
3361         block->key.offset = generation;
3362         block->level = level;
3363         block->key_ready = 0;
3364
3365         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3366         if (rb_node)
3367                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3368
3369         return 0;
3370 }
3371
3372 /*
3373  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3374  */
3375 static int __add_tree_block(struct reloc_control *rc,
3376                             u64 bytenr, u32 blocksize,
3377                             struct rb_root *blocks)
3378 {
3379         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3380         struct btrfs_path *path;
3381         struct btrfs_key key;
3382         int ret;
3383         bool skinny = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
3384
3385         if (tree_block_processed(bytenr, rc))
3386                 return 0;
3387
3388         if (tree_search(blocks, bytenr))
3389                 return 0;
3390
3391         path = btrfs_alloc_path();
3392         if (!path)
3393                 return -ENOMEM;
3394 again:
3395         key.objectid = bytenr;
3396         if (skinny) {
3397                 key.type = BTRFS_METADATA_ITEM_KEY;
3398                 key.offset = (u64)-1;
3399         } else {
3400                 key.type = BTRFS_EXTENT_ITEM_KEY;
3401                 key.offset = blocksize;
3402         }
3403
3404         path->search_commit_root = 1;
3405         path->skip_locking = 1;
3406         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3407         if (ret < 0)
3408                 goto out;
3409
3410         if (ret > 0 && skinny) {
3411                 if (path->slots[0]) {
3412                         path->slots[0]--;
3413                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3414                                               path->slots[0]);
3415                         if (key.objectid == bytenr &&
3416                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3417                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3418                               key.offset == blocksize)))
3419                                 ret = 0;
3420                 }
3421
3422                 if (ret) {
3423                         skinny = false;
3424                         btrfs_release_path(path);
3425                         goto again;
3426                 }
3427         }
3428         if (ret) {
3429                 ASSERT(ret == 1);
3430                 btrfs_print_leaf(path->nodes[0]);
3431                 btrfs_err(fs_info,
3432              "tree block extent item (%llu) is not found in extent tree",
3433                      bytenr);
3434                 WARN_ON(1);
3435                 ret = -EINVAL;
3436                 goto out;
3437         }
3438
3439         ret = add_tree_block(rc, &key, path, blocks);
3440 out:
3441         btrfs_free_path(path);
3442         return ret;
3443 }
3444
3445 /*
3446  * helper to check if the block use full backrefs for pointers in it
3447  */
3448 static int block_use_full_backref(struct reloc_control *rc,
3449                                   struct extent_buffer *eb)
3450 {
3451         u64 flags;
3452         int ret;
3453
3454         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3455             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3456                 return 1;
3457
3458         ret = btrfs_lookup_extent_info(NULL, rc->extent_root->fs_info,
3459                                        eb->start, btrfs_header_level(eb), 1,
3460                                        NULL, &flags);
3461         BUG_ON(ret);
3462
3463         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3464                 ret = 1;
3465         else
3466                 ret = 0;
3467         return ret;
3468 }
3469
3470 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3471                                     struct btrfs_block_group_cache *block_group,
3472                                     struct inode *inode,
3473                                     u64 ino)
3474 {
3475         struct btrfs_key key;
3476         struct btrfs_root *root = fs_info->tree_root;
3477         struct btrfs_trans_handle *trans;
3478         int ret = 0;
3479
3480         if (inode)
3481                 goto truncate;
3482
3483         key.objectid = ino;
3484         key.type = BTRFS_INODE_ITEM_KEY;
3485         key.offset = 0;
3486
3487         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3488         if (IS_ERR(inode))
3489                 return -ENOENT;
3490
3491 truncate:
3492         ret = btrfs_check_trunc_cache_free_space(fs_info,
3493                                                  &fs_info->global_block_rsv);
3494         if (ret)
3495                 goto out;
3496
3497         trans = btrfs_join_transaction(root);
3498         if (IS_ERR(trans)) {
3499                 ret = PTR_ERR(trans);
3500                 goto out;
3501         }
3502
3503         ret = btrfs_truncate_free_space_cache(trans, block_group, inode);
3504
3505         btrfs_end_transaction(trans);
3506         btrfs_btree_balance_dirty(fs_info);
3507 out:
3508         iput(inode);
3509         return ret;
3510 }
3511
3512 /*
3513  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3514  * this function scans fs tree to find blocks reference the data extent
3515  */
3516 static int find_data_references(struct reloc_control *rc,
3517                                 struct btrfs_key *extent_key,
3518                                 struct extent_buffer *leaf,
3519                                 struct btrfs_extent_data_ref *ref,
3520                                 struct rb_root *blocks)
3521 {
3522         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3523         struct btrfs_path *path;
3524         struct tree_block *block;
3525         struct btrfs_root *root;
3526         struct btrfs_file_extent_item *fi;
3527         struct rb_node *rb_node;
3528         struct btrfs_key key;
3529         u64 ref_root;
3530         u64 ref_objectid;
3531         u64 ref_offset;
3532         u32 ref_count;
3533         u32 nritems;
3534         int err = 0;
3535         int added = 0;
3536         int counted;
3537         int ret;
3538
3539         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3540         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3541         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3542         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3543
3544         /*
3545          * This is an extent belonging to the free space cache, lets just delete
3546          * it and redo the search.
3547          */
3548         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3549                 ret = delete_block_group_cache(fs_info, rc->block_group,
3550                                                NULL, ref_objectid);
3551                 if (ret != -ENOENT)
3552                         return ret;
3553                 ret = 0;
3554         }
3555
3556         path = btrfs_alloc_path();
3557         if (!path)
3558                 return -ENOMEM;
3559         path->reada = READA_FORWARD;
3560
3561         root = read_fs_root(fs_info, ref_root);
3562         if (IS_ERR(root)) {
3563                 err = PTR_ERR(root);
3564                 goto out;
3565         }
3566
3567         key.objectid = ref_objectid;
3568         key.type = BTRFS_EXTENT_DATA_KEY;
3569         if (ref_offset > ((u64)-1 << 32))
3570                 key.offset = 0;
3571         else
3572                 key.offset = ref_offset;
3573
3574         path->search_commit_root = 1;
3575         path->skip_locking = 1;
3576         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3577         if (ret < 0) {
3578                 err = ret;
3579                 goto out;
3580         }
3581
3582         leaf = path->nodes[0];
3583         nritems = btrfs_header_nritems(leaf);
3584         /*
3585          * the references in tree blocks that use full backrefs
3586          * are not counted in
3587          */
3588         if (block_use_full_backref(rc, leaf))
3589                 counted = 0;
3590         else
3591                 counted = 1;
3592         rb_node = tree_search(blocks, leaf->start);
3593         if (rb_node) {
3594                 if (counted)
3595                         added = 1;
3596                 else
3597                         path->slots[0] = nritems;
3598         }
3599
3600         while (ref_count > 0) {
3601                 while (path->slots[0] >= nritems) {
3602                         ret = btrfs_next_leaf(root, path);
3603                         if (ret < 0) {
3604                                 err = ret;
3605                                 goto out;
3606                         }
3607                         if (WARN_ON(ret > 0))
3608                                 goto out;
3609
3610                         leaf = path->nodes[0];
3611                         nritems = btrfs_header_nritems(leaf);
3612                         added = 0;
3613
3614                         if (block_use_full_backref(rc, leaf))
3615                                 counted = 0;
3616                         else
3617                                 counted = 1;
3618                         rb_node = tree_search(blocks, leaf->start);
3619                         if (rb_node) {
3620                                 if (counted)
3621                                         added = 1;
3622                                 else
3623                                         path->slots[0] = nritems;
3624                         }
3625                 }
3626
3627                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3628                 if (WARN_ON(key.objectid != ref_objectid ||
3629                     key.type != BTRFS_EXTENT_DATA_KEY))
3630                         break;
3631
3632                 fi = btrfs_item_ptr(leaf, path->slots[0],
3633                                     struct btrfs_file_extent_item);
3634
3635                 if (btrfs_file_extent_type(leaf, fi) ==
3636                     BTRFS_FILE_EXTENT_INLINE)
3637                         goto next;
3638
3639                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3640                     extent_key->objectid)
3641                         goto next;
3642
3643                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3644                 if (key.offset != ref_offset)
3645                         goto next;
3646
3647                 if (counted)
3648                         ref_count--;
3649                 if (added)
3650                         goto next;
3651
3652                 if (!tree_block_processed(leaf->start, rc)) {
3653                         block = kmalloc(sizeof(*block), GFP_NOFS);
3654                         if (!block) {
3655                                 err = -ENOMEM;
3656                                 break;
3657                         }
3658                         block->bytenr = leaf->start;
3659                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3660                         block->level = 0;
3661                         block->key_ready = 1;
3662                         rb_node = tree_insert(blocks, block->bytenr,
3663                                               &block->rb_node);
3664                         if (rb_node)
3665                                 backref_tree_panic(rb_node, -EEXIST,
3666                                                    block->bytenr);
3667                 }
3668                 if (counted)
3669                         added = 1;
3670                 else
3671                         path->slots[0] = nritems;
3672 next:
3673                 path->slots[0]++;
3674
3675         }
3676 out:
3677         btrfs_free_path(path);
3678         return err;
3679 }
3680
3681 /*
3682  * helper to find all tree blocks that reference a given data extent
3683  */
3684 static noinline_for_stack
3685 int add_data_references(struct reloc_control *rc,
3686                         struct btrfs_key *extent_key,
3687                         struct btrfs_path *path,
3688                         struct rb_root *blocks)
3689 {
3690         struct btrfs_key key;
3691         struct extent_buffer *eb;
3692         struct btrfs_extent_data_ref *dref;
3693         struct btrfs_extent_inline_ref *iref;
3694         unsigned long ptr;
3695         unsigned long end;
3696         u32 blocksize = rc->extent_root->fs_info->nodesize;
3697         int ret = 0;
3698         int err = 0;
3699
3700         eb = path->nodes[0];
3701         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3702         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3703         ptr += sizeof(struct btrfs_extent_item);
3704
3705         while (ptr < end) {
3706                 iref = (struct btrfs_extent_inline_ref *)ptr;
3707                 key.type = btrfs_get_extent_inline_ref_type(eb, iref,
3708                                                         BTRFS_REF_TYPE_DATA);
3709                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3710                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3711                         ret = __add_tree_block(rc, key.offset, blocksize,
3712                                                blocks);
3713                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3714                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3715                         ret = find_data_references(rc, extent_key,
3716                                                    eb, dref, blocks);
3717                 } else {
3718                         ret = -EUCLEAN;
3719                         btrfs_err(rc->extent_root->fs_info,
3720                      "extent %llu slot %d has an invalid inline ref type",
3721                              eb->start, path->slots[0]);
3722                 }
3723                 if (ret) {
3724                         err = ret;
3725                         goto out;
3726                 }
3727                 ptr += btrfs_extent_inline_ref_size(key.type);
3728         }
3729         WARN_ON(ptr > end);
3730
3731         while (1) {
3732                 cond_resched();
3733                 eb = path->nodes[0];
3734                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3735                         ret = btrfs_next_leaf(rc->extent_root, path);
3736                         if (ret < 0) {
3737                                 err = ret;
3738                                 break;
3739                         }
3740                         if (ret > 0)
3741                                 break;
3742                         eb = path->nodes[0];
3743                 }
3744
3745                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3746                 if (key.objectid != extent_key->objectid)
3747                         break;
3748
3749                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3750                         ret = __add_tree_block(rc, key.offset, blocksize,
3751                                                blocks);
3752                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3753                         dref = btrfs_item_ptr(eb, path->slots[0],
3754                                               struct btrfs_extent_data_ref);
3755                         ret = find_data_references(rc, extent_key,
3756                                                    eb, dref, blocks);
3757                 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
3758                         btrfs_print_v0_err(eb->fs_info);
3759                         btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3760                         ret = -EINVAL;
3761                 } else {
3762                         ret = 0;
3763                 }
3764                 if (ret) {
3765                         err = ret;
3766                         break;
3767                 }
3768                 path->slots[0]++;
3769         }
3770 out:
3771         btrfs_release_path(path);
3772         if (err)
3773                 free_block_list(blocks);
3774         return err;
3775 }
3776
3777 /*
3778  * helper to find next unprocessed extent
3779  */
3780 static noinline_for_stack
3781 int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
3782                      struct btrfs_key *extent_key)
3783 {
3784         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3785         struct btrfs_key key;
3786         struct extent_buffer *leaf;
3787         u64 start, end, last;
3788         int ret;
3789
3790         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3791         while (1) {
3792                 cond_resched();
3793                 if (rc->search_start >= last) {
3794                         ret = 1;
3795                         break;
3796                 }
3797
3798                 key.objectid = rc->search_start;
3799                 key.type = BTRFS_EXTENT_ITEM_KEY;
3800                 key.offset = 0;
3801
3802                 path->search_commit_root = 1;
3803                 path->skip_locking = 1;
3804                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3805                                         0, 0);
3806                 if (ret < 0)
3807                         break;
3808 next:
3809                 leaf = path->nodes[0];
3810                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3811                         ret = btrfs_next_leaf(rc->extent_root, path);
3812                         if (ret != 0)
3813                                 break;
3814                         leaf = path->nodes[0];
3815                 }
3816
3817                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3818                 if (key.objectid >= last) {
3819                         ret = 1;
3820                         break;
3821                 }
3822
3823                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3824                     key.type != BTRFS_METADATA_ITEM_KEY) {
3825                         path->slots[0]++;
3826                         goto next;
3827                 }
3828
3829                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3830                     key.objectid + key.offset <= rc->search_start) {
3831                         path->slots[0]++;
3832                         goto next;
3833                 }
3834
3835                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3836                     key.objectid + fs_info->nodesize <=
3837                     rc->search_start) {
3838                         path->slots[0]++;
3839                         goto next;
3840                 }
3841
3842                 ret = find_first_extent_bit(&rc->processed_blocks,
3843                                             key.objectid, &start, &end,
3844                                             EXTENT_DIRTY, NULL);
3845
3846                 if (ret == 0 && start <= key.objectid) {
3847                         btrfs_release_path(path);
3848                         rc->search_start = end + 1;
3849                 } else {
3850                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3851                                 rc->search_start = key.objectid + key.offset;
3852                         else
3853                                 rc->search_start = key.objectid +
3854                                         fs_info->nodesize;
3855                         memcpy(extent_key, &key, sizeof(key));
3856                         return 0;
3857                 }
3858         }
3859         btrfs_release_path(path);
3860         return ret;
3861 }
3862
3863 static void set_reloc_control(struct reloc_control *rc)
3864 {
3865         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3866
3867         mutex_lock(&fs_info->reloc_mutex);
3868         fs_info->reloc_ctl = rc;
3869         mutex_unlock(&fs_info->reloc_mutex);
3870 }
3871
3872 static void unset_reloc_control(struct reloc_control *rc)
3873 {
3874         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3875
3876         mutex_lock(&fs_info->reloc_mutex);
3877         fs_info->reloc_ctl = NULL;
3878         mutex_unlock(&fs_info->reloc_mutex);
3879 }
3880
3881 static int check_extent_flags(u64 flags)
3882 {
3883         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3884             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3885                 return 1;
3886         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3887             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3888                 return 1;
3889         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3890             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3891                 return 1;
3892         return 0;
3893 }
3894
3895 static noinline_for_stack
3896 int prepare_to_relocate(struct reloc_control *rc)
3897 {
3898         struct btrfs_trans_handle *trans;
3899         int ret;
3900
3901         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root->fs_info,
3902                                               BTRFS_BLOCK_RSV_TEMP);
3903         if (!rc->block_rsv)
3904                 return -ENOMEM;
3905
3906         memset(&rc->cluster, 0, sizeof(rc->cluster));
3907         rc->search_start = rc->block_group->key.objectid;
3908         rc->extents_found = 0;
3909         rc->nodes_relocated = 0;
3910         rc->merging_rsv_size = 0;
3911         rc->reserved_bytes = 0;
3912         rc->block_rsv->size = rc->extent_root->fs_info->nodesize *
3913                               RELOCATION_RESERVED_NODES;
3914         ret = btrfs_block_rsv_refill(rc->extent_root,
3915                                      rc->block_rsv, rc->block_rsv->size,
3916                                      BTRFS_RESERVE_FLUSH_ALL);
3917         if (ret)
3918                 return ret;
3919
3920         rc->create_reloc_tree = 1;
3921         set_reloc_control(rc);
3922
3923         trans = btrfs_join_transaction(rc->extent_root);
3924         if (IS_ERR(trans)) {
3925                 unset_reloc_control(rc);
3926                 /*
3927                  * extent tree is not a ref_cow tree and has no reloc_root to
3928                  * cleanup.  And callers are responsible to free the above
3929                  * block rsv.
3930                  */
3931                 return PTR_ERR(trans);
3932         }
3933         btrfs_commit_transaction(trans);
3934         return 0;
3935 }
3936
3937 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3938 {
3939         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3940         struct rb_root blocks = RB_ROOT;
3941         struct btrfs_key key;
3942         struct btrfs_trans_handle *trans = NULL;
3943         struct btrfs_path *path;
3944         struct btrfs_extent_item *ei;
3945         u64 flags;
3946         u32 item_size;
3947         int ret;
3948         int err = 0;
3949         int progress = 0;
3950
3951         path = btrfs_alloc_path();
3952         if (!path)
3953                 return -ENOMEM;
3954         path->reada = READA_FORWARD;
3955
3956         ret = prepare_to_relocate(rc);
3957         if (ret) {
3958                 err = ret;
3959                 goto out_free;
3960         }
3961
3962         while (1) {
3963                 rc->reserved_bytes = 0;
3964                 ret = btrfs_block_rsv_refill(rc->extent_root,
3965                                         rc->block_rsv, rc->block_rsv->size,
3966                                         BTRFS_RESERVE_FLUSH_ALL);
3967                 if (ret) {
3968                         err = ret;
3969                         break;
3970                 }
3971                 progress++;
3972                 trans = btrfs_start_transaction(rc->extent_root, 0);
3973                 if (IS_ERR(trans)) {
3974                         err = PTR_ERR(trans);
3975                         trans = NULL;
3976                         break;
3977                 }
3978 restart:
3979                 if (update_backref_cache(trans, &rc->backref_cache)) {
3980                         btrfs_end_transaction(trans);
3981                         trans = NULL;
3982                         continue;
3983                 }
3984
3985                 ret = find_next_extent(rc, path, &key);
3986                 if (ret < 0)
3987                         err = ret;
3988                 if (ret != 0)
3989                         break;
3990
3991                 rc->extents_found++;
3992
3993                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3994                                     struct btrfs_extent_item);
3995                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3996                 if (item_size >= sizeof(*ei)) {
3997                         flags = btrfs_extent_flags(path->nodes[0], ei);
3998                         ret = check_extent_flags(flags);
3999                         BUG_ON(ret);
4000                 } else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
4001                         err = -EINVAL;
4002                         btrfs_print_v0_err(trans->fs_info);
4003                         btrfs_abort_transaction(trans, err);
4004                         break;
4005                 } else {
4006                         BUG();
4007                 }
4008
4009                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4010                         ret = add_tree_block(rc, &key, path, &blocks);
4011                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4012                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4013                         ret = add_data_references(rc, &key, path, &blocks);
4014                 } else {
4015                         btrfs_release_path(path);
4016                         ret = 0;
4017                 }
4018                 if (ret < 0) {
4019                         err = ret;
4020                         break;
4021                 }
4022
4023                 if (!RB_EMPTY_ROOT(&blocks)) {
4024                         ret = relocate_tree_blocks(trans, rc, &blocks);
4025                         if (ret < 0) {
4026                                 /*
4027                                  * if we fail to relocate tree blocks, force to update
4028                                  * backref cache when committing transaction.
4029                                  */
4030                                 rc->backref_cache.last_trans = trans->transid - 1;
4031
4032                                 if (ret != -EAGAIN) {
4033                                         err = ret;
4034                                         break;
4035                                 }
4036                                 rc->extents_found--;
4037                                 rc->search_start = key.objectid;
4038                         }
4039                 }
4040
4041                 btrfs_end_transaction_throttle(trans);
4042                 btrfs_btree_balance_dirty(fs_info);
4043                 trans = NULL;
4044
4045                 if (rc->stage == MOVE_DATA_EXTENTS &&
4046                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4047                         rc->found_file_extent = 1;
4048                         ret = relocate_data_extent(rc->data_inode,
4049                                                    &key, &rc->cluster);
4050                         if (ret < 0) {
4051                                 err = ret;
4052                                 break;
4053                         }
4054                 }
4055         }
4056         if (trans && progress && err == -ENOSPC) {
4057                 ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);
4058                 if (ret == 1) {
4059                         err = 0;
4060                         progress = 0;
4061                         goto restart;
4062                 }
4063         }
4064
4065         btrfs_release_path(path);
4066         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY);
4067
4068         if (trans) {
4069                 btrfs_end_transaction_throttle(trans);
4070                 btrfs_btree_balance_dirty(fs_info);
4071         }
4072
4073         if (!err) {
4074                 ret = relocate_file_extent_cluster(rc->data_inode,
4075                                                    &rc->cluster);
4076                 if (ret < 0)
4077                         err = ret;
4078         }
4079
4080         rc->create_reloc_tree = 0;
4081         set_reloc_control(rc);
4082
4083         backref_cache_cleanup(&rc->backref_cache);
4084         btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4085
4086         err = prepare_to_merge(rc, err);
4087
4088         merge_reloc_roots(rc);
4089
4090         rc->merge_reloc_tree = 0;
4091         unset_reloc_control(rc);
4092         btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4093
4094         /* get rid of pinned extents */
4095         trans = btrfs_join_transaction(rc->extent_root);
4096         if (IS_ERR(trans)) {
4097                 err = PTR_ERR(trans);
4098                 goto out_free;
4099         }
4100         btrfs_commit_transaction(trans);
4101 out_free:
4102         btrfs_free_block_rsv(fs_info, rc->block_rsv);
4103         btrfs_free_path(path);
4104         return err;
4105 }
4106
4107 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4108                                  struct btrfs_root *root, u64 objectid)
4109 {
4110         struct btrfs_path *path;
4111         struct btrfs_inode_item *item;
4112         struct extent_buffer *leaf;
4113         int ret;
4114
4115         path = btrfs_alloc_path();
4116         if (!path)
4117                 return -ENOMEM;
4118
4119         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4120         if (ret)
4121                 goto out;
4122
4123         leaf = path->nodes[0];
4124         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4125         memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));
4126         btrfs_set_inode_generation(leaf, item, 1);
4127         btrfs_set_inode_size(leaf, item, 0);
4128         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4129         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4130                                           BTRFS_INODE_PREALLOC);
4131         btrfs_mark_buffer_dirty(leaf);
4132 out:
4133         btrfs_free_path(path);
4134         return ret;
4135 }
4136
4137 /*
4138  * helper to create inode for data relocation.
4139  * the inode is in data relocation tree and its link count is 0
4140  */
4141 static noinline_for_stack
4142 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4143                                  struct btrfs_block_group_cache *group)
4144 {
4145         struct inode *inode = NULL;
4146         struct btrfs_trans_handle *trans;
4147         struct btrfs_root *root;
4148         struct btrfs_key key;
4149         u64 objectid;
4150         int err = 0;
4151
4152         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4153         if (IS_ERR(root))
4154                 return ERR_CAST(root);
4155
4156         trans = btrfs_start_transaction(root, 6);
4157         if (IS_ERR(trans))
4158                 return ERR_CAST(trans);
4159
4160         err = btrfs_find_free_objectid(root, &objectid);
4161         if (err)
4162                 goto out;
4163
4164         err = __insert_orphan_inode(trans, root, objectid);
4165         BUG_ON(err);
4166
4167         key.objectid = objectid;
4168         key.type = BTRFS_INODE_ITEM_KEY;
4169         key.offset = 0;
4170         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
4171         BUG_ON(IS_ERR(inode));
4172         BTRFS_I(inode)->index_cnt = group->key.objectid;
4173
4174         err = btrfs_orphan_add(trans, BTRFS_I(inode));
4175 out:
4176         btrfs_end_transaction(trans);
4177         btrfs_btree_balance_dirty(fs_info);
4178         if (err) {
4179                 if (inode)
4180                         iput(inode);
4181                 inode = ERR_PTR(err);
4182         }
4183         return inode;
4184 }
4185
4186 static struct reloc_control *alloc_reloc_control(void)
4187 {
4188         struct reloc_control *rc;
4189
4190         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4191         if (!rc)
4192                 return NULL;
4193
4194         INIT_LIST_HEAD(&rc->reloc_roots);
4195         backref_cache_init(&rc->backref_cache);
4196         mapping_tree_init(&rc->reloc_root_tree);
4197         extent_io_tree_init(&rc->processed_blocks, NULL);
4198         return rc;
4199 }
4200
4201 /*
4202  * Print the block group being relocated
4203  */
4204 static void describe_relocation(struct btrfs_fs_info *fs_info,
4205                                 struct btrfs_block_group_cache *block_group)
4206 {
4207         char buf[128];          /* prefixed by a '|' that'll be dropped */
4208         u64 flags = block_group->flags;
4209
4210         /* Shouldn't happen */
4211         if (!flags) {
4212                 strcpy(buf, "|NONE");
4213         } else {
4214                 char *bp = buf;
4215
4216 #define DESCRIBE_FLAG(f, d) \
4217                 if (flags & BTRFS_BLOCK_GROUP_##f) { \
4218                         bp += snprintf(bp, buf - bp + sizeof(buf), "|%s", d); \
4219                         flags &= ~BTRFS_BLOCK_GROUP_##f; \
4220                 }
4221                 DESCRIBE_FLAG(DATA,     "data");
4222                 DESCRIBE_FLAG(SYSTEM,   "system");
4223                 DESCRIBE_FLAG(METADATA, "metadata");
4224                 DESCRIBE_FLAG(RAID0,    "raid0");
4225                 DESCRIBE_FLAG(RAID1,    "raid1");
4226                 DESCRIBE_FLAG(DUP,      "dup");
4227                 DESCRIBE_FLAG(RAID10,   "raid10");
4228                 DESCRIBE_FLAG(RAID5,    "raid5");
4229                 DESCRIBE_FLAG(RAID6,    "raid6");
4230                 if (flags)
4231                         snprintf(bp, buf - bp + sizeof(buf), "|0x%llx", flags);
4232 #undef DESCRIBE_FLAG
4233         }
4234
4235         btrfs_info(fs_info,
4236                    "relocating block group %llu flags %s",
4237                    block_group->key.objectid, buf + 1);
4238 }
4239
4240 /*
4241  * function to relocate all extents in a block group.
4242  */
4243 int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
4244 {
4245         struct btrfs_root *extent_root = fs_info->extent_root;
4246         struct reloc_control *rc;
4247         struct inode *inode;
4248         struct btrfs_path *path;
4249         int ret;
4250         int rw = 0;
4251         int err = 0;
4252
4253         rc = alloc_reloc_control();
4254         if (!rc)
4255                 return -ENOMEM;
4256
4257         rc->extent_root = extent_root;
4258
4259         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4260         BUG_ON(!rc->block_group);
4261
4262         ret = btrfs_inc_block_group_ro(rc->block_group);
4263         if (ret) {
4264                 err = ret;
4265                 goto out;
4266         }
4267         rw = 1;
4268
4269         path = btrfs_alloc_path();
4270         if (!path) {
4271                 err = -ENOMEM;
4272                 goto out;
4273         }
4274
4275         inode = lookup_free_space_inode(fs_info, rc->block_group, path);
4276         btrfs_free_path(path);
4277
4278         if (!IS_ERR(inode))
4279                 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4280         else
4281                 ret = PTR_ERR(inode);
4282
4283         if (ret && ret != -ENOENT) {
4284                 err = ret;
4285                 goto out;
4286         }
4287
4288         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4289         if (IS_ERR(rc->data_inode)) {
4290                 err = PTR_ERR(rc->data_inode);
4291                 rc->data_inode = NULL;
4292                 goto out;
4293         }
4294
4295         describe_relocation(fs_info, rc->block_group);
4296
4297         btrfs_wait_block_group_reservations(rc->block_group);
4298         btrfs_wait_nocow_writers(rc->block_group);
4299         btrfs_wait_ordered_roots(fs_info, U64_MAX,
4300                                  rc->block_group->key.objectid,
4301                                  rc->block_group->key.offset);
4302
4303         while (1) {
4304                 mutex_lock(&fs_info->cleaner_mutex);
4305                 ret = relocate_block_group(rc);
4306                 mutex_unlock(&fs_info->cleaner_mutex);
4307                 if (ret < 0)
4308                         err = ret;
4309
4310                 /*
4311                  * We may have gotten ENOSPC after we already dirtied some
4312                  * extents.  If writeout happens while we're relocating a
4313                  * different block group we could end up hitting the
4314                  * BUG_ON(rc->stage == UPDATE_DATA_PTRS) in
4315                  * btrfs_reloc_cow_block.  Make sure we write everything out
4316                  * properly so we don't trip over this problem, and then break
4317                  * out of the loop if we hit an error.
4318                  */
4319                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4320                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4321                                                        (u64)-1);
4322                         if (ret)
4323                                 err = ret;
4324                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4325                                                  0, -1);
4326                         rc->stage = UPDATE_DATA_PTRS;
4327                 }
4328
4329                 if (err < 0)
4330                         goto out;
4331
4332                 if (rc->extents_found == 0)
4333                         break;
4334
4335                 btrfs_info(fs_info, "found %llu extents", rc->extents_found);
4336
4337         }
4338
4339         WARN_ON(rc->block_group->pinned > 0);
4340         WARN_ON(rc->block_group->reserved > 0);
4341         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4342 out:
4343         if (err && rw)
4344                 btrfs_dec_block_group_ro(rc->block_group);
4345         iput(rc->data_inode);
4346         btrfs_put_block_group(rc->block_group);
4347         kfree(rc);
4348         return err;
4349 }
4350
4351 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4352 {
4353         struct btrfs_fs_info *fs_info = root->fs_info;
4354         struct btrfs_trans_handle *trans;
4355         int ret, err;
4356
4357         trans = btrfs_start_transaction(fs_info->tree_root, 0);
4358         if (IS_ERR(trans))
4359                 return PTR_ERR(trans);
4360
4361         memset(&root->root_item.drop_progress, 0,
4362                 sizeof(root->root_item.drop_progress));
4363         root->root_item.drop_level = 0;
4364         btrfs_set_root_refs(&root->root_item, 0);
4365         ret = btrfs_update_root(trans, fs_info->tree_root,
4366                                 &root->root_key, &root->root_item);
4367
4368         err = btrfs_end_transaction(trans);
4369         if (err)
4370                 return err;
4371         return ret;
4372 }
4373
4374 /*
4375  * recover relocation interrupted by system crash.
4376  *
4377  * this function resumes merging reloc trees with corresponding fs trees.
4378  * this is important for keeping the sharing of tree blocks
4379  */
4380 int btrfs_recover_relocation(struct btrfs_root *root)
4381 {
4382         struct btrfs_fs_info *fs_info = root->fs_info;
4383         LIST_HEAD(reloc_roots);
4384         struct btrfs_key key;
4385         struct btrfs_root *fs_root;
4386         struct btrfs_root *reloc_root;
4387         struct btrfs_path *path;
4388         struct extent_buffer *leaf;
4389         struct reloc_control *rc = NULL;
4390         struct btrfs_trans_handle *trans;
4391         int ret;
4392         int err = 0;
4393
4394         path = btrfs_alloc_path();
4395         if (!path)
4396                 return -ENOMEM;
4397         path->reada = READA_BACK;
4398
4399         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4400         key.type = BTRFS_ROOT_ITEM_KEY;
4401         key.offset = (u64)-1;
4402
4403         while (1) {
4404                 ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,
4405                                         path, 0, 0);
4406                 if (ret < 0) {
4407                         err = ret;
4408                         goto out;
4409                 }
4410                 if (ret > 0) {
4411                         if (path->slots[0] == 0)
4412                                 break;
4413                         path->slots[0]--;
4414                 }
4415                 leaf = path->nodes[0];
4416                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4417                 btrfs_release_path(path);
4418
4419                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4420                     key.type != BTRFS_ROOT_ITEM_KEY)
4421                         break;
4422
4423                 reloc_root = btrfs_read_fs_root(root, &key);
4424                 if (IS_ERR(reloc_root)) {
4425                         err = PTR_ERR(reloc_root);
4426                         goto out;
4427                 }
4428
4429                 list_add(&reloc_root->root_list, &reloc_roots);
4430
4431                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4432                         fs_root = read_fs_root(fs_info,
4433                                                reloc_root->root_key.offset);
4434                         if (IS_ERR(fs_root)) {
4435                                 ret = PTR_ERR(fs_root);
4436                                 if (ret != -ENOENT) {
4437                                         err = ret;
4438                                         goto out;
4439                                 }
4440                                 ret = mark_garbage_root(reloc_root);
4441                                 if (ret < 0) {
4442                                         err = ret;
4443                                         goto out;
4444                                 }
4445                         }
4446                 }
4447
4448                 if (key.offset == 0)
4449                         break;
4450
4451                 key.offset--;
4452         }
4453         btrfs_release_path(path);
4454
4455         if (list_empty(&reloc_roots))
4456                 goto out;
4457
4458         rc = alloc_reloc_control();
4459         if (!rc) {
4460                 err = -ENOMEM;
4461                 goto out;
4462         }
4463
4464         rc->extent_root = fs_info->extent_root;
4465
4466         set_reloc_control(rc);
4467
4468         trans = btrfs_join_transaction(rc->extent_root);
4469         if (IS_ERR(trans)) {
4470                 unset_reloc_control(rc);
4471                 err = PTR_ERR(trans);
4472                 goto out_free;
4473         }
4474
4475         rc->merge_reloc_tree = 1;
4476
4477         while (!list_empty(&reloc_roots)) {
4478                 reloc_root = list_entry(reloc_roots.next,
4479                                         struct btrfs_root, root_list);
4480                 list_del(&reloc_root->root_list);
4481
4482                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4483                         list_add_tail(&reloc_root->root_list,
4484                                       &rc->reloc_roots);
4485                         continue;
4486                 }
4487
4488                 fs_root = read_fs_root(fs_info, reloc_root->root_key.offset);
4489                 if (IS_ERR(fs_root)) {
4490                         err = PTR_ERR(fs_root);
4491                         list_add_tail(&reloc_root->root_list, &reloc_roots);
4492                         goto out_free;
4493                 }
4494
4495                 err = __add_reloc_root(reloc_root);
4496                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4497                 fs_root->reloc_root = reloc_root;
4498         }
4499
4500         err = btrfs_commit_transaction(trans);
4501         if (err)
4502                 goto out_free;
4503
4504         merge_reloc_roots(rc);
4505
4506         unset_reloc_control(rc);
4507
4508         trans = btrfs_join_transaction(rc->extent_root);
4509         if (IS_ERR(trans)) {
4510                 err = PTR_ERR(trans);
4511                 goto out_free;
4512         }
4513         err = btrfs_commit_transaction(trans);
4514 out_free:
4515         kfree(rc);
4516 out:
4517         if (!list_empty(&reloc_roots))
4518                 free_reloc_roots(&reloc_roots);
4519
4520         btrfs_free_path(path);
4521
4522         if (err == 0) {
4523                 /* cleanup orphan inode in data relocation tree */
4524                 fs_root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4525                 if (IS_ERR(fs_root))
4526                         err = PTR_ERR(fs_root);
4527                 else
4528                         err = btrfs_orphan_cleanup(fs_root);
4529         }
4530         return err;
4531 }
4532
4533 /*
4534  * helper to add ordered checksum for data relocation.
4535  *
4536  * cloning checksum properly handles the nodatasum extents.
4537  * it also saves CPU time to re-calculate the checksum.
4538  */
4539 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4540 {
4541         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4542         struct btrfs_ordered_sum *sums;
4543         struct btrfs_ordered_extent *ordered;
4544         int ret;
4545         u64 disk_bytenr;
4546         u64 new_bytenr;
4547         LIST_HEAD(list);
4548
4549         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4550         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4551
4552         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4553         ret = btrfs_lookup_csums_range(fs_info->csum_root, disk_bytenr,
4554                                        disk_bytenr + len - 1, &list, 0);
4555         if (ret)
4556                 goto out;
4557
4558         while (!list_empty(&list)) {
4559                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4560                 list_del_init(&sums->list);
4561
4562                 /*
4563                  * We need to offset the new_bytenr based on where the csum is.
4564                  * We need to do this because we will read in entire prealloc
4565                  * extents but we may have written to say the middle of the
4566                  * prealloc extent, so we need to make sure the csum goes with
4567                  * the right disk offset.
4568                  *
4569                  * We can do this because the data reloc inode refers strictly
4570                  * to the on disk bytes, so we don't have to worry about
4571                  * disk_len vs real len like with real inodes since it's all
4572                  * disk length.
4573                  */
4574                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4575                 sums->bytenr = new_bytenr;
4576
4577                 btrfs_add_ordered_sum(inode, ordered, sums);
4578         }
4579 out:
4580         btrfs_put_ordered_extent(ordered);
4581         return ret;
4582 }
4583
4584 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4585                           struct btrfs_root *root, struct extent_buffer *buf,
4586                           struct extent_buffer *cow)
4587 {
4588         struct btrfs_fs_info *fs_info = root->fs_info;
4589         struct reloc_control *rc;
4590         struct backref_node *node;
4591         int first_cow = 0;
4592         int level;
4593         int ret = 0;
4594
4595         rc = fs_info->reloc_ctl;
4596         if (!rc)
4597                 return 0;
4598
4599         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4600                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4601
4602         level = btrfs_header_level(buf);
4603         if (btrfs_header_generation(buf) <=
4604             btrfs_root_last_snapshot(&root->root_item))
4605                 first_cow = 1;
4606
4607         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4608             rc->create_reloc_tree) {
4609                 WARN_ON(!first_cow && level == 0);
4610
4611                 node = rc->backref_cache.path[level];
4612                 BUG_ON(node->bytenr != buf->start &&
4613                        node->new_bytenr != buf->start);
4614
4615                 drop_node_buffer(node);
4616                 extent_buffer_get(cow);
4617                 node->eb = cow;
4618                 node->new_bytenr = cow->start;
4619
4620                 if (!node->pending) {
4621                         list_move_tail(&node->list,
4622                                        &rc->backref_cache.pending[level]);
4623                         node->pending = 1;
4624                 }
4625
4626                 if (first_cow)
4627                         __mark_block_processed(rc, node);
4628
4629                 if (first_cow && level > 0)
4630                         rc->nodes_relocated += buf->len;
4631         }
4632
4633         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4634                 ret = replace_file_extents(trans, rc, root, cow);
4635         return ret;
4636 }
4637
4638 /*
4639  * called before creating snapshot. it calculates metadata reservation
4640  * required for relocating tree blocks in the snapshot
4641  */
4642 void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
4643                               u64 *bytes_to_reserve)
4644 {
4645         struct btrfs_root *root;
4646         struct reloc_control *rc;
4647
4648         root = pending->root;
4649         if (!root->reloc_root)
4650                 return;
4651
4652         rc = root->fs_info->reloc_ctl;
4653         if (!rc->merge_reloc_tree)
4654                 return;
4655
4656         root = root->reloc_root;
4657         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4658         /*
4659          * relocation is in the stage of merging trees. the space
4660          * used by merging a reloc tree is twice the size of
4661          * relocated tree nodes in the worst case. half for cowing
4662          * the reloc tree, half for cowing the fs tree. the space
4663          * used by cowing the reloc tree will be freed after the
4664          * tree is dropped. if we create snapshot, cowing the fs
4665          * tree may use more space than it frees. so we need
4666          * reserve extra space.
4667          */
4668         *bytes_to_reserve += rc->nodes_relocated;
4669 }
4670
4671 /*
4672  * called after snapshot is created. migrate block reservation
4673  * and create reloc root for the newly created snapshot
4674  */
4675 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4676                                struct btrfs_pending_snapshot *pending)
4677 {
4678         struct btrfs_root *root = pending->root;
4679         struct btrfs_root *reloc_root;
4680         struct btrfs_root *new_root;
4681         struct reloc_control *rc;
4682         int ret;
4683
4684         if (!root->reloc_root)
4685                 return 0;
4686
4687         rc = root->fs_info->reloc_ctl;
4688         rc->merging_rsv_size += rc->nodes_relocated;
4689
4690         if (rc->merge_reloc_tree) {
4691                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4692                                               rc->block_rsv,
4693                                               rc->nodes_relocated, 1);
4694                 if (ret)
4695                         return ret;
4696         }
4697
4698         new_root = pending->snap;
4699         reloc_root = create_reloc_root(trans, root->reloc_root,
4700                                        new_root->root_key.objectid);
4701         if (IS_ERR(reloc_root))
4702                 return PTR_ERR(reloc_root);
4703
4704         ret = __add_reloc_root(reloc_root);
4705         BUG_ON(ret < 0);
4706         new_root->reloc_root = reloc_root;
4707
4708         if (rc->create_reloc_tree)
4709                 ret = clone_backref_node(trans, rc, root, reloc_root);
4710         return ret;
4711 }