fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97
  98 struct backref_cache {
  99         /* red black tree of all backref nodes in the cache */
 100         struct rb_root rb_root;
 101         /* for passing backref nodes to btrfs_reloc_cow_block */
 102         struct backref_node *path[BTRFS_MAX_LEVEL];
 103         /*
 104          * list of blocks that have been cowed but some block
 105          * pointers in upper level blocks may not reflect the
 106          * new location
 107          */
 108         struct list_head pending[BTRFS_MAX_LEVEL];
 109         /* list of backref nodes with no child node */
 110         struct list_head leaves;
 111         /* list of blocks that have been cowed in current transaction */
 112         struct list_head changed;
 113         /* list of detached backref node. */
 114         struct list_head detached;
 115
 116         u64 last_trans;
 117
 118         int nr_nodes;
 119         int nr_edges;
 120 };
 121
 122 /*
 123  * map address of tree root to tree
 124  */
 125 struct mapping_node {
 126         struct rb_node rb_node;
 127         u64 bytenr;
 128         void *data;
 129 };
 130
 131 struct mapping_tree {
 132         struct rb_root rb_root;
 133         spinlock_t lock;
 134 };
 135
 136 /*
 137  * present a tree block to process
 138  */
 139 struct tree_block {
 140         struct rb_node rb_node;
 141         u64 bytenr;
 142         struct btrfs_key key;
 143         unsigned int level:8;
 144         unsigned int key_ready:1;
 145 };
 146
 147 #define MAX_EXTENTS 128
 148
 149 struct file_extent_cluster {
 150         u64 start;
 151         u64 end;
 152         u64 boundary[MAX_EXTENTS];
 153         unsigned int nr;
 154 };
 155
 156 struct reloc_control {
 157         /* block group to relocate */
 158         struct btrfs_block_group_cache *block_group;
 159         /* extent tree */
 160         struct btrfs_root *extent_root;
 161         /* inode for moving data */
 162         struct inode *data_inode;
 163
 164         struct btrfs_block_rsv *block_rsv;
 165
 166         struct backref_cache backref_cache;
 167
 168         struct file_extent_cluster cluster;
 169         /* tree blocks have been processed */
 170         struct extent_io_tree processed_blocks;
 171         /* map start of tree root to corresponding reloc tree */
 172         struct mapping_tree reloc_root_tree;
 173         /* list of reloc trees */
 174         struct list_head reloc_roots;
 175         /* size of metadata reservation for merging reloc trees */
 176         u64 merging_rsv_size;
 177         /* size of relocated tree nodes */
 178         u64 nodes_relocated;
 179
 180         u64 search_start;
 181         u64 extents_found;
 182
 183         unsigned int stage:8;
 184         unsigned int create_reloc_tree:1;
 185         unsigned int merge_reloc_tree:1;
 186         unsigned int found_file_extent:1;
 187         unsigned int commit_transaction:1;
 188 };
 189
 190 /* stages of data relocation */
 191 #define MOVE_DATA_EXTENTS       0
 192 #define UPDATE_DATA_PTRS        1
 193
 194 static void remove_backref_node(struct backref_cache *cache,
 195                                 struct backref_node *node);
 196 static void __mark_block_processed(struct reloc_control *rc,
 197                                    struct backref_node *node);
 198
 199 static void mapping_tree_init(struct mapping_tree *tree)
 200 {
 201         tree->rb_root = RB_ROOT;
 202         spin_lock_init(&tree->lock);
 203 }
 204
 205 static void backref_cache_init(struct backref_cache *cache)
 206 {
 207         int i;
 208         cache->rb_root = RB_ROOT;
 209         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 210                 INIT_LIST_HEAD(&cache->pending[i]);
 211         INIT_LIST_HEAD(&cache->changed);
 212         INIT_LIST_HEAD(&cache->detached);
 213         INIT_LIST_HEAD(&cache->leaves);
 214 }
 215
 216 static void backref_cache_cleanup(struct backref_cache *cache)
 217 {
 218         struct backref_node *node;
 219         int i;
 220
 221         while (!list_empty(&cache->detached)) {
 222                 node = list_entry(cache->detached.next,
 223                                   struct backref_node, list);
 224                 remove_backref_node(cache, node);
 225         }
 226
 227         while (!list_empty(&cache->leaves)) {
 228                 node = list_entry(cache->leaves.next,
 229                                   struct backref_node, lower);
 230                 remove_backref_node(cache, node);
 231         }
 232
 233         cache->last_trans = 0;
 234
 235         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 236                 BUG_ON(!list_empty(&cache->pending[i]));
 237         BUG_ON(!list_empty(&cache->changed));
 238         BUG_ON(!list_empty(&cache->detached));
 239         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 240         BUG_ON(cache->nr_nodes);
 241         BUG_ON(cache->nr_edges);
 242 }
 243
 244 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 245 {
 246         struct backref_node *node;
 247
 248         node = kzalloc(sizeof(*node), GFP_NOFS);
 249         if (node) {
 250                 INIT_LIST_HEAD(&node->list);
 251                 INIT_LIST_HEAD(&node->upper);
 252                 INIT_LIST_HEAD(&node->lower);
 253                 RB_CLEAR_NODE(&node->rb_node);
 254                 cache->nr_nodes++;
 255         }
 256         return node;
 257 }
 258
 259 static void free_backref_node(struct backref_cache *cache,
 260                               struct backref_node *node)
 261 {
 262         if (node) {
 263                 cache->nr_nodes--;
 264                 kfree(node);
 265         }
 266 }
 267
 268 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 269 {
 270         struct backref_edge *edge;
 271
 272         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 273         if (edge)
 274                 cache->nr_edges++;
 275         return edge;
 276 }
 277
 278 static void free_backref_edge(struct backref_cache *cache,
 279                               struct backref_edge *edge)
 280 {
 281         if (edge) {
 282                 cache->nr_edges--;
 283                 kfree(edge);
 284         }
 285 }
 286
 287 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 288                                    struct rb_node *node)
 289 {
 290         struct rb_node **p = &root->rb_node;
 291         struct rb_node *parent = NULL;
 292         struct tree_entry *entry;
 293
 294         while (*p) {
 295                 parent = *p;
 296                 entry = rb_entry(parent, struct tree_entry, rb_node);
 297
 298                 if (bytenr < entry->bytenr)
 299                         p = &(*p)->rb_left;
 300                 else if (bytenr > entry->bytenr)
 301                         p = &(*p)->rb_right;
 302                 else
 303                         return parent;
 304         }
 305
 306         rb_link_node(node, parent, p);
 307         rb_insert_color(node, root);
 308         return NULL;
 309 }
 310
 311 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 312 {
 313         struct rb_node *n = root->rb_node;
 314         struct tree_entry *entry;
 315
 316         while (n) {
 317                 entry = rb_entry(n, struct tree_entry, rb_node);
 318
 319                 if (bytenr < entry->bytenr)
 320                         n = n->rb_left;
 321                 else if (bytenr > entry->bytenr)
 322                         n = n->rb_right;
 323                 else
 324                         return n;
 325         }
 326         return NULL;
 327 }
 328
 329 /*
 330  * walk up backref nodes until reach node presents tree root
 331  */
 332 static struct backref_node *walk_up_backref(struct backref_node *node,
 333                                             struct backref_edge *edges[],
 334                                             int *index)
 335 {
 336         struct backref_edge *edge;
 337         int idx = *index;
 338
 339         while (!list_empty(&node->upper)) {
 340                 edge = list_entry(node->upper.next,
 341                                   struct backref_edge, list[LOWER]);
 342                 edges[idx++] = edge;
 343                 node = edge->node[UPPER];
 344         }
 345         BUG_ON(node->detached);
 346         *index = idx;
 347         return node;
 348 }
 349
 350 /*
 351  * walk down backref nodes to find start of next reference path
 352  */
 353 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 354                                               int *index)
 355 {
 356         struct backref_edge *edge;
 357         struct backref_node *lower;
 358         int idx = *index;
 359
 360         while (idx > 0) {
 361                 edge = edges[idx - 1];
 362                 lower = edge->node[LOWER];
 363                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 364                         idx--;
 365                         continue;
 366                 }
 367                 edge = list_entry(edge->list[LOWER].next,
 368                                   struct backref_edge, list[LOWER]);
 369                 edges[idx - 1] = edge;
 370                 *index = idx;
 371                 return edge->node[UPPER];
 372         }
 373         *index = 0;
 374         return NULL;
 375 }
 376
 377 static void unlock_node_buffer(struct backref_node *node)
 378 {
 379         if (node->locked) {
 380                 btrfs_tree_unlock(node->eb);
 381                 node->locked = 0;
 382         }
 383 }
 384
 385 static void drop_node_buffer(struct backref_node *node)
 386 {
 387         if (node->eb) {
 388                 unlock_node_buffer(node);
 389                 free_extent_buffer(node->eb);
 390                 node->eb = NULL;
 391         }
 392 }
 393
 394 static void drop_backref_node(struct backref_cache *tree,
 395                               struct backref_node *node)
 396 {
 397         BUG_ON(!list_empty(&node->upper));
 398
 399         drop_node_buffer(node);
 400         list_del(&node->list);
 401         list_del(&node->lower);
 402         if (!RB_EMPTY_NODE(&node->rb_node))
 403                 rb_erase(&node->rb_node, &tree->rb_root);
 404         free_backref_node(tree, node);
 405 }
 406
 407 /*
 408  * remove a backref node from the backref cache
 409  */
 410 static void remove_backref_node(struct backref_cache *cache,
 411                                 struct backref_node *node)
 412 {
 413         struct backref_node *upper;
 414         struct backref_edge *edge;
 415
 416         if (!node)
 417                 return;
 418
 419         BUG_ON(!node->lowest && !node->detached);
 420         while (!list_empty(&node->upper)) {
 421                 edge = list_entry(node->upper.next, struct backref_edge,
 422                                   list[LOWER]);
 423                 upper = edge->node[UPPER];
 424                 list_del(&edge->list[LOWER]);
 425                 list_del(&edge->list[UPPER]);
 426                 free_backref_edge(cache, edge);
 427
 428                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 429                         BUG_ON(!list_empty(&node->upper));
 430                         drop_backref_node(cache, node);
 431                         node = upper;
 432                         node->lowest = 1;
 433                         continue;
 434                 }
 435                 /*
 436                  * add the node to leaf node list if no other
 437                  * child block cached.
 438                  */
 439                 if (list_empty(&upper->lower)) {
 440                         list_add_tail(&upper->lower, &cache->leaves);
 441                         upper->lowest = 1;
 442                 }
 443         }
 444
 445         drop_backref_node(cache, node);
 446 }
 447
 448 static void update_backref_node(struct backref_cache *cache,
 449                                 struct backref_node *node, u64 bytenr)
 450 {
 451         struct rb_node *rb_node;
 452         rb_erase(&node->rb_node, &cache->rb_root);
 453         node->bytenr = bytenr;
 454         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 455         BUG_ON(rb_node);
 456 }
 457
 458 /*
 459  * update backref cache after a transaction commit
 460  */
 461 static int update_backref_cache(struct btrfs_trans_handle *trans,
 462                                 struct backref_cache *cache)
 463 {
 464         struct backref_node *node;
 465         int level = 0;
 466
 467         if (cache->last_trans == 0) {
 468                 cache->last_trans = trans->transid;
 469                 return 0;
 470         }
 471
 472         if (cache->last_trans == trans->transid)
 473                 return 0;
 474
 475         /*
 476          * detached nodes are used to avoid unnecessary backref
 477          * lookup. transaction commit changes the extent tree.
 478          * so the detached nodes are no longer useful.
 479          */
 480         while (!list_empty(&cache->detached)) {
 481                 node = list_entry(cache->detached.next,
 482                                   struct backref_node, list);
 483                 remove_backref_node(cache, node);
 484         }
 485
 486         while (!list_empty(&cache->changed)) {
 487                 node = list_entry(cache->changed.next,
 488                                   struct backref_node, list);
 489                 list_del_init(&node->list);
 490                 BUG_ON(node->pending);
 491                 update_backref_node(cache, node, node->new_bytenr);
 492         }
 493
 494         /*
 495          * some nodes can be left in the pending list if there were
 496          * errors during processing the pending nodes.
 497          */
 498         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 499                 list_for_each_entry(node, &cache->pending[level], list) {
 500                         BUG_ON(!node->pending);
 501                         if (node->bytenr == node->new_bytenr)
 502                                 continue;
 503                         update_backref_node(cache, node, node->new_bytenr);
 504                 }
 505         }
 506
 507         cache->last_trans = 0;
 508         return 1;
 509 }
 510
 511
 512 static int should_ignore_root(struct btrfs_root *root)
 513 {
 514         struct btrfs_root *reloc_root;
 515
 516         if (!root->ref_cows)
 517                 return 0;
 518
 519         reloc_root = root->reloc_root;
 520         if (!reloc_root)
 521                 return 0;
 522
 523         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 524             root->fs_info->running_transaction->transid - 1)
 525                 return 0;
 526         /*
 527          * if there is reloc tree and it was created in previous
 528          * transaction backref lookup can find the reloc tree,
 529          * so backref node for the fs tree root is useless for
 530          * relocation.
 531          */
 532         return 1;
 533 }
 534 /*
 535  * find reloc tree by address of tree root
 536  */
 537 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 538                                           u64 bytenr)
 539 {
 540         struct rb_node *rb_node;
 541         struct mapping_node *node;
 542         struct btrfs_root *root = NULL;
 543
 544         spin_lock(&rc->reloc_root_tree.lock);
 545         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 546         if (rb_node) {
 547                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 548                 root = (struct btrfs_root *)node->data;
 549         }
 550         spin_unlock(&rc->reloc_root_tree.lock);
 551         return root;
 552 }
 553
 554 static int is_cowonly_root(u64 root_objectid)
 555 {
 556         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 557             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 558             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 559             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 560             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 561             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
 562                 return 1;
 563         return 0;
 564 }
 565
 566 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 567                                         u64 root_objectid)
 568 {
 569         struct btrfs_key key;
 570
 571         key.objectid = root_objectid;
 572         key.type = BTRFS_ROOT_ITEM_KEY;
 573         if (is_cowonly_root(root_objectid))
 574                 key.offset = 0;
 575         else
 576                 key.offset = (u64)-1;
 577
 578         return btrfs_read_fs_root_no_name(fs_info, &key);
 579 }
 580
 581 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 582 static noinline_for_stack
 583 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 584                                   struct extent_buffer *leaf,
 585                                   struct btrfs_extent_ref_v0 *ref0)
 586 {
 587         struct btrfs_root *root;
 588         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 589         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 590
 591         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 592
 593         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 594         BUG_ON(IS_ERR(root));
 595
 596         if (root->ref_cows &&
 597             generation != btrfs_root_generation(&root->root_item))
 598                 return NULL;
 599
 600         return root;
 601 }
 602 #endif
 603
 604 static noinline_for_stack
 605 int find_inline_backref(struct extent_buffer *leaf, int slot,
 606                         unsigned long *ptr, unsigned long *end)
 607 {
 608         struct btrfs_extent_item *ei;
 609         struct btrfs_tree_block_info *bi;
 610         u32 item_size;
 611
 612         item_size = btrfs_item_size_nr(leaf, slot);
 613 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 614         if (item_size < sizeof(*ei)) {
 615                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 616                 return 1;
 617         }
 618 #endif
 619         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 620         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 621                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 622
 623         if (item_size <= sizeof(*ei) + sizeof(*bi)) {
 624                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 625                 return 1;
 626         }
 627
 628         bi = (struct btrfs_tree_block_info *)(ei + 1);
 629         *ptr = (unsigned long)(bi + 1);
 630         *end = (unsigned long)ei + item_size;
 631         return 0;
 632 }
 633
 634 /*
 635  * build backref tree for a given tree block. root of the backref tree
 636  * corresponds the tree block, leaves of the backref tree correspond
 637  * roots of b-trees that reference the tree block.
 638  *
 639  * the basic idea of this function is check backrefs of a given block
 640  * to find upper level blocks that refernece the block, and then check
 641  * bakcrefs of these upper level blocks recursively. the recursion stop
 642  * when tree root is reached or backrefs for the block is cached.
 643  *
 644  * NOTE: if we find backrefs for a block are cached, we know backrefs
 645  * for all upper level blocks that directly/indirectly reference the
 646  * block are also cached.
 647  */
 648 static noinline_for_stack
 649 struct backref_node *build_backref_tree(struct reloc_control *rc,
 650                                         struct btrfs_key *node_key,
 651                                         int level, u64 bytenr)
 652 {
 653         struct backref_cache *cache = &rc->backref_cache;
 654         struct btrfs_path *path1;
 655         struct btrfs_path *path2;
 656         struct extent_buffer *eb;
 657         struct btrfs_root *root;
 658         struct backref_node *cur;
 659         struct backref_node *upper;
 660         struct backref_node *lower;
 661         struct backref_node *node = NULL;
 662         struct backref_node *exist = NULL;
 663         struct backref_edge *edge;
 664         struct rb_node *rb_node;
 665         struct btrfs_key key;
 666         unsigned long end;
 667         unsigned long ptr;
 668         LIST_HEAD(list);
 669         LIST_HEAD(useless);
 670         int cowonly;
 671         int ret;
 672         int err = 0;
 673
 674         path1 = btrfs_alloc_path();
 675         path2 = btrfs_alloc_path();
 676         if (!path1 || !path2) {
 677                 err = -ENOMEM;
 678                 goto out;
 679         }
 680         path1->reada = 1;
 681         path2->reada = 2;
 682
 683         node = alloc_backref_node(cache);
 684         if (!node) {
 685                 err = -ENOMEM;
 686                 goto out;
 687         }
 688
 689         node->bytenr = bytenr;
 690         node->level = level;
 691         node->lowest = 1;
 692         cur = node;
 693 again:
 694         end = 0;
 695         ptr = 0;
 696         key.objectid = cur->bytenr;
 697         key.type = BTRFS_EXTENT_ITEM_KEY;
 698         key.offset = (u64)-1;
 699
 700         path1->search_commit_root = 1;
 701         path1->skip_locking = 1;
 702         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 703                                 0, 0);
 704         if (ret < 0) {
 705                 err = ret;
 706                 goto out;
 707         }
 708         BUG_ON(!ret || !path1->slots[0]);
 709
 710         path1->slots[0]--;
 711
 712         WARN_ON(cur->checked);
 713         if (!list_empty(&cur->upper)) {
 714                 /*
 715                  * the backref was added previously when processing
 716                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 717                  */
 718                 BUG_ON(!list_is_singular(&cur->upper));
 719                 edge = list_entry(cur->upper.next, struct backref_edge,
 720                                   list[LOWER]);
 721                 BUG_ON(!list_empty(&edge->list[UPPER]));
 722                 exist = edge->node[UPPER];
 723                 /*
 724                  * add the upper level block to pending list if we need
 725                  * check its backrefs
 726                  */
 727                 if (!exist->checked)
 728                         list_add_tail(&edge->list[UPPER], &list);
 729         } else {
 730                 exist = NULL;
 731         }
 732
 733         while (1) {
 734                 cond_resched();
 735                 eb = path1->nodes[0];
 736
 737                 if (ptr >= end) {
 738                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 739                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 740                                 if (ret < 0) {
 741                                         err = ret;
 742                                         goto out;
 743                                 }
 744                                 if (ret > 0)
 745                                         break;
 746                                 eb = path1->nodes[0];
 747                         }
 748
 749                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 750                         if (key.objectid != cur->bytenr) {
 751                                 WARN_ON(exist);
 752                                 break;
 753                         }
 754
 755                         if (key.type == BTRFS_EXTENT_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                         iref = (struct btrfs_extent_inline_ref *)ptr;
 767                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 768                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 769                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 770                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 771                 }
 772
 773                 if (exist &&
 774                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 775                       exist->owner == key.offset) ||
 776                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 777                       exist->bytenr == key.offset))) {
 778                         exist = NULL;
 779                         goto next;
 780                 }
 781
 782 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 783                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 784                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 785                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 786                                 struct btrfs_extent_ref_v0 *ref0;
 787                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 788                                                 struct btrfs_extent_ref_v0);
 789                                 if (key.objectid == key.offset) {
 790                                         root = find_tree_root(rc, eb, ref0);
 791                                         if (root && !should_ignore_root(root))
 792                                                 cur->root = root;
 793                                         else
 794                                                 list_add(&cur->list, &useless);
 795                                         break;
 796                                 }
 797                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 798                                                                       ref0)))
 799                                         cur->cowonly = 1;
 800                         }
 801 #else
 802                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 803                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 804 #endif
 805                         if (key.objectid == key.offset) {
 806                                 /*
 807                                  * only root blocks of reloc trees use
 808                                  * backref of this type.
 809                                  */
 810                                 root = find_reloc_root(rc, cur->bytenr);
 811                                 BUG_ON(!root);
 812                                 cur->root = root;
 813                                 break;
 814                         }
 815
 816                         edge = alloc_backref_edge(cache);
 817                         if (!edge) {
 818                                 err = -ENOMEM;
 819                                 goto out;
 820                         }
 821                         rb_node = tree_search(&cache->rb_root, key.offset);
 822                         if (!rb_node) {
 823                                 upper = alloc_backref_node(cache);
 824                                 if (!upper) {
 825                                         free_backref_edge(cache, edge);
 826                                         err = -ENOMEM;
 827                                         goto out;
 828                                 }
 829                                 upper->bytenr = key.offset;
 830                                 upper->level = cur->level + 1;
 831                                 /*
 832                                  *  backrefs for the upper level block isn't
 833                                  *  cached, add the block to pending list
 834                                  */
 835                                 list_add_tail(&edge->list[UPPER], &list);
 836                         } else {
 837                                 upper = rb_entry(rb_node, struct backref_node,
 838                                                  rb_node);
 839                                 BUG_ON(!upper->checked);
 840                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 841                         }
 842                         list_add_tail(&edge->list[LOWER], &cur->upper);
 843                         edge->node[LOWER] = cur;
 844                         edge->node[UPPER] = upper;
 845
 846                         goto next;
 847                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 848                         goto next;
 849                 }
 850
 851                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 852                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 853                 if (IS_ERR(root)) {
 854                         err = PTR_ERR(root);
 855                         goto out;
 856                 }
 857
 858                 if (!root->ref_cows)
 859                         cur->cowonly = 1;
 860
 861                 if (btrfs_root_level(&root->root_item) == cur->level) {
 862                         /* tree root */
 863                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 864                                cur->bytenr);
 865                         if (should_ignore_root(root))
 866                                 list_add(&cur->list, &useless);
 867                         else
 868                                 cur->root = root;
 869                         break;
 870                 }
 871
 872                 level = cur->level + 1;
 873
 874                 /*
 875                  * searching the tree to find upper level blocks
 876                  * reference the block.
 877                  */
 878                 path2->search_commit_root = 1;
 879                 path2->skip_locking = 1;
 880                 path2->lowest_level = level;
 881                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 882                 path2->lowest_level = 0;
 883                 if (ret < 0) {
 884                         err = ret;
 885                         goto out;
 886                 }
 887                 if (ret > 0 && path2->slots[level] > 0)
 888                         path2->slots[level]--;
 889
 890                 eb = path2->nodes[level];
 891                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 892                         cur->bytenr);
 893
 894                 lower = cur;
 895                 for (; level < BTRFS_MAX_LEVEL; level++) {
 896                         if (!path2->nodes[level]) {
 897                                 BUG_ON(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 (!root->ref_cows)
 925                                         upper->cowonly = 1;
 926
 927                                 /*
 928                                  * if we know the block isn't shared
 929                                  * we can void checking its backrefs.
 930                                  */
 931                                 if (btrfs_block_can_be_shared(root, eb))
 932                                         upper->checked = 0;
 933                                 else
 934                                         upper->checked = 1;
 935
 936                                 /*
 937                                  * add the block to pending list if we
 938                                  * need check its backrefs. only block
 939                                  * at 'cur->level + 1' is added to the
 940                                  * tail of pending list. this guarantees
 941                                  * we check backrefs from lower level
 942                                  * blocks to upper level blocks.
 943                                  */
 944                                 if (!upper->checked &&
 945                                     level == cur->level + 1) {
 946                                         list_add_tail(&edge->list[UPPER],
 947                                                       &list);
 948                                 } else
 949                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 950                         } else {
 951                                 upper = rb_entry(rb_node, struct backref_node,
 952                                                  rb_node);
 953                                 BUG_ON(!upper->checked);
 954                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 955                                 if (!upper->owner)
 956                                         upper->owner = btrfs_header_owner(eb);
 957                         }
 958                         list_add_tail(&edge->list[LOWER], &lower->upper);
 959                         edge->node[LOWER] = lower;
 960                         edge->node[UPPER] = upper;
 961
 962                         if (rb_node)
 963                                 break;
 964                         lower = upper;
 965                         upper = NULL;
 966                 }
 967                 btrfs_release_path(path2);
 968 next:
 969                 if (ptr < end) {
 970                         ptr += btrfs_extent_inline_ref_size(key.type);
 971                         if (ptr >= end) {
 972                                 WARN_ON(ptr > end);
 973                                 ptr = 0;
 974                                 end = 0;
 975                         }
 976                 }
 977                 if (ptr >= end)
 978                         path1->slots[0]++;
 979         }
 980         btrfs_release_path(path1);
 981
 982         cur->checked = 1;
 983         WARN_ON(exist);
 984
 985         /* the pending list isn't empty, take the first block to process */
 986         if (!list_empty(&list)) {
 987                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 988                 list_del_init(&edge->list[UPPER]);
 989                 cur = edge->node[UPPER];
 990                 goto again;
 991         }
 992
 993         /*
 994          * everything goes well, connect backref nodes and insert backref nodes
 995          * into the cache.
 996          */
 997         BUG_ON(!node->checked);
 998         cowonly = node->cowonly;
 999         if (!cowonly) {
1000                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1001                                       &node->rb_node);
1002                 BUG_ON(rb_node);
1003                 list_add_tail(&node->lower, &cache->leaves);
1004         }
1005
1006         list_for_each_entry(edge, &node->upper, list[LOWER])
1007                 list_add_tail(&edge->list[UPPER], &list);
1008
1009         while (!list_empty(&list)) {
1010                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1011                 list_del_init(&edge->list[UPPER]);
1012                 upper = edge->node[UPPER];
1013                 if (upper->detached) {
1014                         list_del(&edge->list[LOWER]);
1015                         lower = edge->node[LOWER];
1016                         free_backref_edge(cache, edge);
1017                         if (list_empty(&lower->upper))
1018                                 list_add(&lower->list, &useless);
1019                         continue;
1020                 }
1021
1022                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1023                         if (upper->lowest) {
1024                                 list_del_init(&upper->lower);
1025                                 upper->lowest = 0;
1026                         }
1027
1028                         list_add_tail(&edge->list[UPPER], &upper->lower);
1029                         continue;
1030                 }
1031
1032                 BUG_ON(!upper->checked);
1033                 BUG_ON(cowonly != upper->cowonly);
1034                 if (!cowonly) {
1035                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1036                                               &upper->rb_node);
1037                         BUG_ON(rb_node);
1038                 }
1039
1040                 list_add_tail(&edge->list[UPPER], &upper->lower);
1041
1042                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1043                         list_add_tail(&edge->list[UPPER], &list);
1044         }
1045         /*
1046          * process useless backref nodes. backref nodes for tree leaves
1047          * are deleted from the cache. backref nodes for upper level
1048          * tree blocks are left in the cache to avoid unnecessary backref
1049          * lookup.
1050          */
1051         while (!list_empty(&useless)) {
1052                 upper = list_entry(useless.next, struct backref_node, list);
1053                 list_del_init(&upper->list);
1054                 BUG_ON(!list_empty(&upper->upper));
1055                 if (upper == node)
1056                         node = NULL;
1057                 if (upper->lowest) {
1058                         list_del_init(&upper->lower);
1059                         upper->lowest = 0;
1060                 }
1061                 while (!list_empty(&upper->lower)) {
1062                         edge = list_entry(upper->lower.next,
1063                                           struct backref_edge, list[UPPER]);
1064                         list_del(&edge->list[UPPER]);
1065                         list_del(&edge->list[LOWER]);
1066                         lower = edge->node[LOWER];
1067                         free_backref_edge(cache, edge);
1068
1069                         if (list_empty(&lower->upper))
1070                                 list_add(&lower->list, &useless);
1071                 }
1072                 __mark_block_processed(rc, upper);
1073                 if (upper->level > 0) {
1074                         list_add(&upper->list, &cache->detached);
1075                         upper->detached = 1;
1076                 } else {
1077                         rb_erase(&upper->rb_node, &cache->rb_root);
1078                         free_backref_node(cache, upper);
1079                 }
1080         }
1081 out:
1082         btrfs_free_path(path1);
1083         btrfs_free_path(path2);
1084         if (err) {
1085                 while (!list_empty(&useless)) {
1086                         lower = list_entry(useless.next,
1087                                            struct backref_node, upper);
1088                         list_del_init(&lower->upper);
1089                 }
1090                 upper = node;
1091                 INIT_LIST_HEAD(&list);
1092                 while (upper) {
1093                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1094                                 list_splice_tail(&upper->upper, &list);
1095                                 free_backref_node(cache, upper);
1096                         }
1097
1098                         if (list_empty(&list))
1099                                 break;
1100
1101                         edge = list_entry(list.next, struct backref_edge,
1102                                           list[LOWER]);
1103                         list_del(&edge->list[LOWER]);
1104                         upper = edge->node[UPPER];
1105                         free_backref_edge(cache, edge);
1106                 }
1107                 return ERR_PTR(err);
1108         }
1109         BUG_ON(node && node->detached);
1110         return node;
1111 }
1112
1113 /*
1114  * helper to add backref node for the newly created snapshot.
1115  * the backref node is created by cloning backref node that
1116  * corresponds to root of source tree
1117  */
1118 static int clone_backref_node(struct btrfs_trans_handle *trans,
1119                               struct reloc_control *rc,
1120                               struct btrfs_root *src,
1121                               struct btrfs_root *dest)
1122 {
1123         struct btrfs_root *reloc_root = src->reloc_root;
1124         struct backref_cache *cache = &rc->backref_cache;
1125         struct backref_node *node = NULL;
1126         struct backref_node *new_node;
1127         struct backref_edge *edge;
1128         struct backref_edge *new_edge;
1129         struct rb_node *rb_node;
1130
1131         if (cache->last_trans > 0)
1132                 update_backref_cache(trans, cache);
1133
1134         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1135         if (rb_node) {
1136                 node = rb_entry(rb_node, struct backref_node, rb_node);
1137                 if (node->detached)
1138                         node = NULL;
1139                 else
1140                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1141         }
1142
1143         if (!node) {
1144                 rb_node = tree_search(&cache->rb_root,
1145                                       reloc_root->commit_root->start);
1146                 if (rb_node) {
1147                         node = rb_entry(rb_node, struct backref_node,
1148                                         rb_node);
1149                         BUG_ON(node->detached);
1150                 }
1151         }
1152
1153         if (!node)
1154                 return 0;
1155
1156         new_node = alloc_backref_node(cache);
1157         if (!new_node)
1158                 return -ENOMEM;
1159
1160         new_node->bytenr = dest->node->start;
1161         new_node->level = node->level;
1162         new_node->lowest = node->lowest;
1163         new_node->checked = 1;
1164         new_node->root = dest;
1165
1166         if (!node->lowest) {
1167                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1168                         new_edge = alloc_backref_edge(cache);
1169                         if (!new_edge)
1170                                 goto fail;
1171
1172                         new_edge->node[UPPER] = new_node;
1173                         new_edge->node[LOWER] = edge->node[LOWER];
1174                         list_add_tail(&new_edge->list[UPPER],
1175                                       &new_node->lower);
1176                 }
1177         } else {
1178                 list_add_tail(&new_node->lower, &cache->leaves);
1179         }
1180
1181         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1182                               &new_node->rb_node);
1183         BUG_ON(rb_node);
1184
1185         if (!new_node->lowest) {
1186                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1187                         list_add_tail(&new_edge->list[LOWER],
1188                                       &new_edge->node[LOWER]->upper);
1189                 }
1190         }
1191         return 0;
1192 fail:
1193         while (!list_empty(&new_node->lower)) {
1194                 new_edge = list_entry(new_node->lower.next,
1195                                       struct backref_edge, list[UPPER]);
1196                 list_del(&new_edge->list[UPPER]);
1197                 free_backref_edge(cache, new_edge);
1198         }
1199         free_backref_node(cache, new_node);
1200         return -ENOMEM;
1201 }
1202
1203 /*
1204  * helper to add 'address of tree root -> reloc tree' mapping
1205  */
1206 static int __add_reloc_root(struct btrfs_root *root)
1207 {
1208         struct rb_node *rb_node;
1209         struct mapping_node *node;
1210         struct reloc_control *rc = root->fs_info->reloc_ctl;
1211
1212         node = kmalloc(sizeof(*node), GFP_NOFS);
1213         BUG_ON(!node);
1214
1215         node->bytenr = root->node->start;
1216         node->data = root;
1217
1218         spin_lock(&rc->reloc_root_tree.lock);
1219         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1220                               node->bytenr, &node->rb_node);
1221         spin_unlock(&rc->reloc_root_tree.lock);
1222         BUG_ON(rb_node);
1223
1224         list_add_tail(&root->root_list, &rc->reloc_roots);
1225         return 0;
1226 }
1227
1228 /*
1229  * helper to update/delete the 'address of tree root -> reloc tree'
1230  * mapping
1231  */
1232 static int __update_reloc_root(struct btrfs_root *root, int del)
1233 {
1234         struct rb_node *rb_node;
1235         struct mapping_node *node = NULL;
1236         struct reloc_control *rc = root->fs_info->reloc_ctl;
1237
1238         spin_lock(&rc->reloc_root_tree.lock);
1239         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1240                               root->commit_root->start);
1241         if (rb_node) {
1242                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1243                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1244         }
1245         spin_unlock(&rc->reloc_root_tree.lock);
1246
1247         BUG_ON((struct btrfs_root *)node->data != root);
1248
1249         if (!del) {
1250                 spin_lock(&rc->reloc_root_tree.lock);
1251                 node->bytenr = root->node->start;
1252                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1253                                       node->bytenr, &node->rb_node);
1254                 spin_unlock(&rc->reloc_root_tree.lock);
1255                 BUG_ON(rb_node);
1256         } else {
1257                 list_del_init(&root->root_list);
1258                 kfree(node);
1259         }
1260         return 0;
1261 }
1262
1263 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1264                                         struct btrfs_root *root, u64 objectid)
1265 {
1266         struct btrfs_root *reloc_root;
1267         struct extent_buffer *eb;
1268         struct btrfs_root_item *root_item;
1269         struct btrfs_key root_key;
1270         int ret;
1271
1272         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1273         BUG_ON(!root_item);
1274
1275         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1276         root_key.type = BTRFS_ROOT_ITEM_KEY;
1277         root_key.offset = objectid;
1278
1279         if (root->root_key.objectid == objectid) {
1280                 /* called by btrfs_init_reloc_root */
1281                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1282                                       BTRFS_TREE_RELOC_OBJECTID);
1283                 BUG_ON(ret);
1284
1285                 btrfs_set_root_last_snapshot(&root->root_item,
1286                                              trans->transid - 1);
1287         } else {
1288                 /*
1289                  * called by btrfs_reloc_post_snapshot_hook.
1290                  * the source tree is a reloc tree, all tree blocks
1291                  * modified after it was created have RELOC flag
1292                  * set in their headers. so it's OK to not update
1293                  * the 'last_snapshot'.
1294                  */
1295                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1296                                       BTRFS_TREE_RELOC_OBJECTID);
1297                 BUG_ON(ret);
1298         }
1299
1300         memcpy(root_item, &root->root_item, sizeof(*root_item));
1301         btrfs_set_root_bytenr(root_item, eb->start);
1302         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1303         btrfs_set_root_generation(root_item, trans->transid);
1304
1305         if (root->root_key.objectid == objectid) {
1306                 btrfs_set_root_refs(root_item, 0);
1307                 memset(&root_item->drop_progress, 0,
1308                        sizeof(struct btrfs_disk_key));
1309                 root_item->drop_level = 0;
1310         }
1311
1312         btrfs_tree_unlock(eb);
1313         free_extent_buffer(eb);
1314
1315         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1316                                 &root_key, root_item);
1317         BUG_ON(ret);
1318         kfree(root_item);
1319
1320         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1321                                                  &root_key);
1322         BUG_ON(IS_ERR(reloc_root));
1323         reloc_root->last_trans = trans->transid;
1324         return reloc_root;
1325 }
1326
1327 /*
1328  * create reloc tree for a given fs tree. reloc tree is just a
1329  * snapshot of the fs tree with special root objectid.
1330  */
1331 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1332                           struct btrfs_root *root)
1333 {
1334         struct btrfs_root *reloc_root;
1335         struct reloc_control *rc = root->fs_info->reloc_ctl;
1336         int clear_rsv = 0;
1337
1338         if (root->reloc_root) {
1339                 reloc_root = root->reloc_root;
1340                 reloc_root->last_trans = trans->transid;
1341                 return 0;
1342         }
1343
1344         if (!rc || !rc->create_reloc_tree ||
1345             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1346                 return 0;
1347
1348         if (!trans->block_rsv) {
1349                 trans->block_rsv = rc->block_rsv;
1350                 clear_rsv = 1;
1351         }
1352         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1353         if (clear_rsv)
1354                 trans->block_rsv = NULL;
1355
1356         __add_reloc_root(reloc_root);
1357         root->reloc_root = reloc_root;
1358         return 0;
1359 }
1360
1361 /*
1362  * update root item of reloc tree
1363  */
1364 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1365                             struct btrfs_root *root)
1366 {
1367         struct btrfs_root *reloc_root;
1368         struct btrfs_root_item *root_item;
1369         int del = 0;
1370         int ret;
1371
1372         if (!root->reloc_root)
1373                 goto out;
1374
1375         reloc_root = root->reloc_root;
1376         root_item = &reloc_root->root_item;
1377
1378         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1379             btrfs_root_refs(root_item) == 0) {
1380                 root->reloc_root = NULL;
1381                 del = 1;
1382         }
1383
1384         __update_reloc_root(reloc_root, del);
1385
1386         if (reloc_root->commit_root != reloc_root->node) {
1387                 btrfs_set_root_node(root_item, reloc_root->node);
1388                 free_extent_buffer(reloc_root->commit_root);
1389                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1390         }
1391
1392         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1393                                 &reloc_root->root_key, root_item);
1394         BUG_ON(ret);
1395
1396 out:
1397         return 0;
1398 }
1399
1400 /*
1401  * helper to find first cached inode with inode number >= objectid
1402  * in a subvolume
1403  */
1404 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1405 {
1406         struct rb_node *node;
1407         struct rb_node *prev;
1408         struct btrfs_inode *entry;
1409         struct inode *inode;
1410
1411         spin_lock(&root->inode_lock);
1412 again:
1413         node = root->inode_tree.rb_node;
1414         prev = NULL;
1415         while (node) {
1416                 prev = node;
1417                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1418
1419                 if (objectid < btrfs_ino(&entry->vfs_inode))
1420                         node = node->rb_left;
1421                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1422                         node = node->rb_right;
1423                 else
1424                         break;
1425         }
1426         if (!node) {
1427                 while (prev) {
1428                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1429                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1430                                 node = prev;
1431                                 break;
1432                         }
1433                         prev = rb_next(prev);
1434                 }
1435         }
1436         while (node) {
1437                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1438                 inode = igrab(&entry->vfs_inode);
1439                 if (inode) {
1440                         spin_unlock(&root->inode_lock);
1441                         return inode;
1442                 }
1443
1444                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1445                 if (cond_resched_lock(&root->inode_lock))
1446                         goto again;
1447
1448                 node = rb_next(node);
1449         }
1450         spin_unlock(&root->inode_lock);
1451         return NULL;
1452 }
1453
1454 static int in_block_group(u64 bytenr,
1455                           struct btrfs_block_group_cache *block_group)
1456 {
1457         if (bytenr >= block_group->key.objectid &&
1458             bytenr < block_group->key.objectid + block_group->key.offset)
1459                 return 1;
1460         return 0;
1461 }
1462
1463 /*
1464  * get new location of data
1465  */
1466 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1467                             u64 bytenr, u64 num_bytes)
1468 {
1469         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1470         struct btrfs_path *path;
1471         struct btrfs_file_extent_item *fi;
1472         struct extent_buffer *leaf;
1473         int ret;
1474
1475         path = btrfs_alloc_path();
1476         if (!path)
1477                 return -ENOMEM;
1478
1479         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1480         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1481                                        bytenr, 0);
1482         if (ret < 0)
1483                 goto out;
1484         if (ret > 0) {
1485                 ret = -ENOENT;
1486                 goto out;
1487         }
1488
1489         leaf = path->nodes[0];
1490         fi = btrfs_item_ptr(leaf, path->slots[0],
1491                             struct btrfs_file_extent_item);
1492
1493         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1494                btrfs_file_extent_compression(leaf, fi) ||
1495                btrfs_file_extent_encryption(leaf, fi) ||
1496                btrfs_file_extent_other_encoding(leaf, fi));
1497
1498         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1499                 ret = 1;
1500                 goto out;
1501         }
1502
1503         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1504         ret = 0;
1505 out:
1506         btrfs_free_path(path);
1507         return ret;
1508 }
1509
1510 /*
1511  * update file extent items in the tree leaf to point to
1512  * the new locations.
1513  */
1514 static noinline_for_stack
1515 int replace_file_extents(struct btrfs_trans_handle *trans,
1516                          struct reloc_control *rc,
1517                          struct btrfs_root *root,
1518                          struct extent_buffer *leaf)
1519 {
1520         struct btrfs_key key;
1521         struct btrfs_file_extent_item *fi;
1522         struct inode *inode = NULL;
1523         u64 parent;
1524         u64 bytenr;
1525         u64 new_bytenr = 0;
1526         u64 num_bytes;
1527         u64 end;
1528         u32 nritems;
1529         u32 i;
1530         int ret;
1531         int first = 1;
1532         int dirty = 0;
1533
1534         if (rc->stage != UPDATE_DATA_PTRS)
1535                 return 0;
1536
1537         /* reloc trees always use full backref */
1538         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1539                 parent = leaf->start;
1540         else
1541                 parent = 0;
1542
1543         nritems = btrfs_header_nritems(leaf);
1544         for (i = 0; i < nritems; i++) {
1545                 cond_resched();
1546                 btrfs_item_key_to_cpu(leaf, &key, i);
1547                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1548                         continue;
1549                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1550                 if (btrfs_file_extent_type(leaf, fi) ==
1551                     BTRFS_FILE_EXTENT_INLINE)
1552                         continue;
1553                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1554                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1555                 if (bytenr == 0)
1556                         continue;
1557                 if (!in_block_group(bytenr, rc->block_group))
1558                         continue;
1559
1560                 /*
1561                  * if we are modifying block in fs tree, wait for readpage
1562                  * to complete and drop the extent cache
1563                  */
1564                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1565                         if (first) {
1566                                 inode = find_next_inode(root, key.objectid);
1567                                 first = 0;
1568                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1569                                 btrfs_add_delayed_iput(inode);
1570                                 inode = find_next_inode(root, key.objectid);
1571                         }
1572                         if (inode && btrfs_ino(inode) == key.objectid) {
1573                                 end = key.offset +
1574                                       btrfs_file_extent_num_bytes(leaf, fi);
1575                                 WARN_ON(!IS_ALIGNED(key.offset,
1576                                                     root->sectorsize));
1577                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1578                                 end--;
1579                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1580                                                       key.offset, end,
1581                                                       GFP_NOFS);
1582                                 if (!ret)
1583                                         continue;
1584
1585                                 btrfs_drop_extent_cache(inode, key.offset, end,
1586                                                         1);
1587                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1588                                               key.offset, end, GFP_NOFS);
1589                         }
1590                 }
1591
1592                 ret = get_new_location(rc->data_inode, &new_bytenr,
1593                                        bytenr, num_bytes);
1594                 if (ret > 0) {
1595                         WARN_ON(1);
1596                         continue;
1597                 }
1598                 BUG_ON(ret < 0);
1599
1600                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1601                 dirty = 1;
1602
1603                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1604                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1605                                            num_bytes, parent,
1606                                            btrfs_header_owner(leaf),
1607                                            key.objectid, key.offset, 1);
1608                 BUG_ON(ret);
1609
1610                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1611                                         parent, btrfs_header_owner(leaf),
1612                                         key.objectid, key.offset, 1);
1613                 BUG_ON(ret);
1614         }
1615         if (dirty)
1616                 btrfs_mark_buffer_dirty(leaf);
1617         if (inode)
1618                 btrfs_add_delayed_iput(inode);
1619         return 0;
1620 }
1621
1622 static noinline_for_stack
1623 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1624                      struct btrfs_path *path, int level)
1625 {
1626         struct btrfs_disk_key key1;
1627         struct btrfs_disk_key key2;
1628         btrfs_node_key(eb, &key1, slot);
1629         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1630         return memcmp(&key1, &key2, sizeof(key1));
1631 }
1632
1633 /*
1634  * try to replace tree blocks in fs tree with the new blocks
1635  * in reloc tree. tree blocks haven't been modified since the
1636  * reloc tree was create can be replaced.
1637  *
1638  * if a block was replaced, level of the block + 1 is returned.
1639  * if no block got replaced, 0 is returned. if there are other
1640  * errors, a negative error number is returned.
1641  */
1642 static noinline_for_stack
1643 int replace_path(struct btrfs_trans_handle *trans,
1644                  struct btrfs_root *dest, struct btrfs_root *src,
1645                  struct btrfs_path *path, struct btrfs_key *next_key,
1646                  int lowest_level, int max_level)
1647 {
1648         struct extent_buffer *eb;
1649         struct extent_buffer *parent;
1650         struct btrfs_key key;
1651         u64 old_bytenr;
1652         u64 new_bytenr;
1653         u64 old_ptr_gen;
1654         u64 new_ptr_gen;
1655         u64 last_snapshot;
1656         u32 blocksize;
1657         int cow = 0;
1658         int level;
1659         int ret;
1660         int slot;
1661
1662         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1663         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1664
1665         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1666 again:
1667         slot = path->slots[lowest_level];
1668         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1669
1670         eb = btrfs_lock_root_node(dest);
1671         btrfs_set_lock_blocking(eb);
1672         level = btrfs_header_level(eb);
1673
1674         if (level < lowest_level) {
1675                 btrfs_tree_unlock(eb);
1676                 free_extent_buffer(eb);
1677                 return 0;
1678         }
1679
1680         if (cow) {
1681                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1682                 BUG_ON(ret);
1683         }
1684         btrfs_set_lock_blocking(eb);
1685
1686         if (next_key) {
1687                 next_key->objectid = (u64)-1;
1688                 next_key->type = (u8)-1;
1689                 next_key->offset = (u64)-1;
1690         }
1691
1692         parent = eb;
1693         while (1) {
1694                 level = btrfs_header_level(parent);
1695                 BUG_ON(level < lowest_level);
1696
1697                 ret = btrfs_bin_search(parent, &key, level, &slot);
1698                 if (ret && slot > 0)
1699                         slot--;
1700
1701                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1702                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1703
1704                 old_bytenr = btrfs_node_blockptr(parent, slot);
1705                 blocksize = btrfs_level_size(dest, level - 1);
1706                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1707
1708                 if (level <= max_level) {
1709                         eb = path->nodes[level];
1710                         new_bytenr = btrfs_node_blockptr(eb,
1711                                                         path->slots[level]);
1712                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1713                                                         path->slots[level]);
1714                 } else {
1715                         new_bytenr = 0;
1716                         new_ptr_gen = 0;
1717                 }
1718
1719                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1720                         WARN_ON(1);
1721                         ret = level;
1722                         break;
1723                 }
1724
1725                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1726                     memcmp_node_keys(parent, slot, path, level)) {
1727                         if (level <= lowest_level) {
1728                                 ret = 0;
1729                                 break;
1730                         }
1731
1732                         eb = read_tree_block(dest, old_bytenr, blocksize,
1733                                              old_ptr_gen);
1734                         BUG_ON(!eb);
1735                         btrfs_tree_lock(eb);
1736                         if (cow) {
1737                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1738                                                       slot, &eb);
1739                                 BUG_ON(ret);
1740                         }
1741                         btrfs_set_lock_blocking(eb);
1742
1743                         btrfs_tree_unlock(parent);
1744                         free_extent_buffer(parent);
1745
1746                         parent = eb;
1747                         continue;
1748                 }
1749
1750                 if (!cow) {
1751                         btrfs_tree_unlock(parent);
1752                         free_extent_buffer(parent);
1753                         cow = 1;
1754                         goto again;
1755                 }
1756
1757                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1758                                       path->slots[level]);
1759                 btrfs_release_path(path);
1760
1761                 path->lowest_level = level;
1762                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1763                 path->lowest_level = 0;
1764                 BUG_ON(ret);
1765
1766                 /*
1767                  * swap blocks in fs tree and reloc tree.
1768                  */
1769                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1770                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1771                 btrfs_mark_buffer_dirty(parent);
1772
1773                 btrfs_set_node_blockptr(path->nodes[level],
1774                                         path->slots[level], old_bytenr);
1775                 btrfs_set_node_ptr_generation(path->nodes[level],
1776                                               path->slots[level], old_ptr_gen);
1777                 btrfs_mark_buffer_dirty(path->nodes[level]);
1778
1779                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1780                                         path->nodes[level]->start,
1781                                         src->root_key.objectid, level - 1, 0,
1782                                         1);
1783                 BUG_ON(ret);
1784                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1785                                         0, dest->root_key.objectid, level - 1,
1786                                         0, 1);
1787                 BUG_ON(ret);
1788
1789                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1790                                         path->nodes[level]->start,
1791                                         src->root_key.objectid, level - 1, 0,
1792                                         1);
1793                 BUG_ON(ret);
1794
1795                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1796                                         0, dest->root_key.objectid, level - 1,
1797                                         0, 1);
1798                 BUG_ON(ret);
1799
1800                 btrfs_unlock_up_safe(path, 0);
1801
1802                 ret = level;
1803                 break;
1804         }
1805         btrfs_tree_unlock(parent);
1806         free_extent_buffer(parent);
1807         return ret;
1808 }
1809
1810 /*
1811  * helper to find next relocated block in reloc tree
1812  */
1813 static noinline_for_stack
1814 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1815                        int *level)
1816 {
1817         struct extent_buffer *eb;
1818         int i;
1819         u64 last_snapshot;
1820         u32 nritems;
1821
1822         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1823
1824         for (i = 0; i < *level; i++) {
1825                 free_extent_buffer(path->nodes[i]);
1826                 path->nodes[i] = NULL;
1827         }
1828
1829         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1830                 eb = path->nodes[i];
1831                 nritems = btrfs_header_nritems(eb);
1832                 while (path->slots[i] + 1 < nritems) {
1833                         path->slots[i]++;
1834                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1835                             last_snapshot)
1836                                 continue;
1837
1838                         *level = i;
1839                         return 0;
1840                 }
1841                 free_extent_buffer(path->nodes[i]);
1842                 path->nodes[i] = NULL;
1843         }
1844         return 1;
1845 }
1846
1847 /*
1848  * walk down reloc tree to find relocated block of lowest level
1849  */
1850 static noinline_for_stack
1851 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1852                          int *level)
1853 {
1854         struct extent_buffer *eb = NULL;
1855         int i;
1856         u64 bytenr;
1857         u64 ptr_gen = 0;
1858         u64 last_snapshot;
1859         u32 blocksize;
1860         u32 nritems;
1861
1862         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1863
1864         for (i = *level; i > 0; i--) {
1865                 eb = path->nodes[i];
1866                 nritems = btrfs_header_nritems(eb);
1867                 while (path->slots[i] < nritems) {
1868                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1869                         if (ptr_gen > last_snapshot)
1870                                 break;
1871                         path->slots[i]++;
1872                 }
1873                 if (path->slots[i] >= nritems) {
1874                         if (i == *level)
1875                                 break;
1876                         *level = i + 1;
1877                         return 0;
1878                 }
1879                 if (i == 1) {
1880                         *level = i;
1881                         return 0;
1882                 }
1883
1884                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1885                 blocksize = btrfs_level_size(root, i - 1);
1886                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1887                 BUG_ON(btrfs_header_level(eb) != i - 1);
1888                 path->nodes[i - 1] = eb;
1889                 path->slots[i - 1] = 0;
1890         }
1891         return 1;
1892 }
1893
1894 /*
1895  * invalidate extent cache for file extents whose key in range of
1896  * [min_key, max_key)
1897  */
1898 static int invalidate_extent_cache(struct btrfs_root *root,
1899                                    struct btrfs_key *min_key,
1900                                    struct btrfs_key *max_key)
1901 {
1902         struct inode *inode = NULL;
1903         u64 objectid;
1904         u64 start, end;
1905         u64 ino;
1906
1907         objectid = min_key->objectid;
1908         while (1) {
1909                 cond_resched();
1910                 iput(inode);
1911
1912                 if (objectid > max_key->objectid)
1913                         break;
1914
1915                 inode = find_next_inode(root, objectid);
1916                 if (!inode)
1917                         break;
1918                 ino = btrfs_ino(inode);
1919
1920                 if (ino > max_key->objectid) {
1921                         iput(inode);
1922                         break;
1923                 }
1924
1925                 objectid = ino + 1;
1926                 if (!S_ISREG(inode->i_mode))
1927                         continue;
1928
1929                 if (unlikely(min_key->objectid == ino)) {
1930                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1931                                 continue;
1932                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1933                                 start = 0;
1934                         else {
1935                                 start = min_key->offset;
1936                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1937                         }
1938                 } else {
1939                         start = 0;
1940                 }
1941
1942                 if (unlikely(max_key->objectid == ino)) {
1943                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1944                                 continue;
1945                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1946                                 end = (u64)-1;
1947                         } else {
1948                                 if (max_key->offset == 0)
1949                                         continue;
1950                                 end = max_key->offset;
1951                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1952                                 end--;
1953                         }
1954                 } else {
1955                         end = (u64)-1;
1956                 }
1957
1958                 /* the lock_extent waits for readpage to complete */
1959                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1960                 btrfs_drop_extent_cache(inode, start, end, 1);
1961                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1962         }
1963         return 0;
1964 }
1965
1966 static int find_next_key(struct btrfs_path *path, int level,
1967                          struct btrfs_key *key)
1968
1969 {
1970         while (level < BTRFS_MAX_LEVEL) {
1971                 if (!path->nodes[level])
1972                         break;
1973                 if (path->slots[level] + 1 <
1974                     btrfs_header_nritems(path->nodes[level])) {
1975                         btrfs_node_key_to_cpu(path->nodes[level], key,
1976                                               path->slots[level] + 1);
1977                         return 0;
1978                 }
1979                 level++;
1980         }
1981         return 1;
1982 }
1983
1984 /*
1985  * merge the relocated tree blocks in reloc tree with corresponding
1986  * fs tree.
1987  */
1988 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1989                                                struct btrfs_root *root)
1990 {
1991         LIST_HEAD(inode_list);
1992         struct btrfs_key key;
1993         struct btrfs_key next_key;
1994         struct btrfs_trans_handle *trans;
1995         struct btrfs_root *reloc_root;
1996         struct btrfs_root_item *root_item;
1997         struct btrfs_path *path;
1998         struct extent_buffer *leaf;
1999         unsigned long nr;
2000         int level;
2001         int max_level;
2002         int replaced = 0;
2003         int ret;
2004         int err = 0;
2005         u32 min_reserved;
2006
2007         path = btrfs_alloc_path();
2008         if (!path)
2009                 return -ENOMEM;
2010         path->reada = 1;
2011
2012         reloc_root = root->reloc_root;
2013         root_item = &reloc_root->root_item;
2014
2015         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2016                 level = btrfs_root_level(root_item);
2017                 extent_buffer_get(reloc_root->node);
2018                 path->nodes[level] = reloc_root->node;
2019                 path->slots[level] = 0;
2020         } else {
2021                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2022
2023                 level = root_item->drop_level;
2024                 BUG_ON(level == 0);
2025                 path->lowest_level = level;
2026                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2027                 path->lowest_level = 0;
2028                 if (ret < 0) {
2029                         btrfs_free_path(path);
2030                         return ret;
2031                 }
2032
2033                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2034                                       path->slots[level]);
2035                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2036
2037                 btrfs_unlock_up_safe(path, 0);
2038         }
2039
2040         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2041         memset(&next_key, 0, sizeof(next_key));
2042
2043         while (1) {
2044                 trans = btrfs_start_transaction(root, 0);
2045                 BUG_ON(IS_ERR(trans));
2046                 trans->block_rsv = rc->block_rsv;
2047
2048                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved);
2049                 if (ret) {
2050                         BUG_ON(ret != -EAGAIN);
2051                         ret = btrfs_commit_transaction(trans, root);
2052                         BUG_ON(ret);
2053                         continue;
2054                 }
2055
2056                 replaced = 0;
2057                 max_level = level;
2058
2059                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2060                 if (ret < 0) {
2061                         err = ret;
2062                         goto out;
2063                 }
2064                 if (ret > 0)
2065                         break;
2066
2067                 if (!find_next_key(path, level, &key) &&
2068                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2069                         ret = 0;
2070                 } else {
2071                         ret = replace_path(trans, root, reloc_root, path,
2072                                            &next_key, level, max_level);
2073                 }
2074                 if (ret < 0) {
2075                         err = ret;
2076                         goto out;
2077                 }
2078
2079                 if (ret > 0) {
2080                         level = ret;
2081                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2082                                               path->slots[level]);
2083                         replaced = 1;
2084                 }
2085
2086                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2087                 if (ret > 0)
2088                         break;
2089
2090                 BUG_ON(level == 0);
2091                 /*
2092                  * save the merging progress in the drop_progress.
2093                  * this is OK since root refs == 1 in this case.
2094                  */
2095                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2096                                path->slots[level]);
2097                 root_item->drop_level = level;
2098
2099                 nr = trans->blocks_used;
2100                 btrfs_end_transaction_throttle(trans, root);
2101
2102                 btrfs_btree_balance_dirty(root, nr);
2103
2104                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2105                         invalidate_extent_cache(root, &key, &next_key);
2106         }
2107
2108         /*
2109          * handle the case only one block in the fs tree need to be
2110          * relocated and the block is tree root.
2111          */
2112         leaf = btrfs_lock_root_node(root);
2113         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2114         btrfs_tree_unlock(leaf);
2115         free_extent_buffer(leaf);
2116         if (ret < 0)
2117                 err = ret;
2118 out:
2119         btrfs_free_path(path);
2120
2121         if (err == 0) {
2122                 memset(&root_item->drop_progress, 0,
2123                        sizeof(root_item->drop_progress));
2124                 root_item->drop_level = 0;
2125                 btrfs_set_root_refs(root_item, 0);
2126                 btrfs_update_reloc_root(trans, root);
2127         }
2128
2129         nr = trans->blocks_used;
2130         btrfs_end_transaction_throttle(trans, root);
2131
2132         btrfs_btree_balance_dirty(root, nr);
2133
2134         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2135                 invalidate_extent_cache(root, &key, &next_key);
2136
2137         return err;
2138 }
2139
2140 static noinline_for_stack
2141 int prepare_to_merge(struct reloc_control *rc, int err)
2142 {
2143         struct btrfs_root *root = rc->extent_root;
2144         struct btrfs_root *reloc_root;
2145         struct btrfs_trans_handle *trans;
2146         LIST_HEAD(reloc_roots);
2147         u64 num_bytes = 0;
2148         int ret;
2149
2150         mutex_lock(&root->fs_info->reloc_mutex);
2151         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2152         rc->merging_rsv_size += rc->nodes_relocated * 2;
2153         mutex_unlock(&root->fs_info->reloc_mutex);
2154
2155 again:
2156         if (!err) {
2157                 num_bytes = rc->merging_rsv_size;
2158                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes);
2159                 if (ret)
2160                         err = ret;
2161         }
2162
2163         trans = btrfs_join_transaction(rc->extent_root);
2164         if (IS_ERR(trans)) {
2165                 if (!err)
2166                         btrfs_block_rsv_release(rc->extent_root,
2167                                                 rc->block_rsv, num_bytes);
2168                 return PTR_ERR(trans);
2169         }
2170
2171         if (!err) {
2172                 if (num_bytes != rc->merging_rsv_size) {
2173                         btrfs_end_transaction(trans, rc->extent_root);
2174                         btrfs_block_rsv_release(rc->extent_root,
2175                                                 rc->block_rsv, num_bytes);
2176                         goto again;
2177                 }
2178         }
2179
2180         rc->merge_reloc_tree = 1;
2181
2182         while (!list_empty(&rc->reloc_roots)) {
2183                 reloc_root = list_entry(rc->reloc_roots.next,
2184                                         struct btrfs_root, root_list);
2185                 list_del_init(&reloc_root->root_list);
2186
2187                 root = read_fs_root(reloc_root->fs_info,
2188                                     reloc_root->root_key.offset);
2189                 BUG_ON(IS_ERR(root));
2190                 BUG_ON(root->reloc_root != reloc_root);
2191
2192                 /*
2193                  * set reference count to 1, so btrfs_recover_relocation
2194                  * knows it should resumes merging
2195                  */
2196                 if (!err)
2197                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2198                 btrfs_update_reloc_root(trans, root);
2199
2200                 list_add(&reloc_root->root_list, &reloc_roots);
2201         }
2202
2203         list_splice(&reloc_roots, &rc->reloc_roots);
2204
2205         if (!err)
2206                 btrfs_commit_transaction(trans, rc->extent_root);
2207         else
2208                 btrfs_end_transaction(trans, rc->extent_root);
2209         return err;
2210 }
2211
2212 static noinline_for_stack
2213 int merge_reloc_roots(struct reloc_control *rc)
2214 {
2215         struct btrfs_root *root;
2216         struct btrfs_root *reloc_root;
2217         LIST_HEAD(reloc_roots);
2218         int found = 0;
2219         int ret;
2220 again:
2221         root = rc->extent_root;
2222
2223         /*
2224          * this serializes us with btrfs_record_root_in_transaction,
2225          * we have to make sure nobody is in the middle of
2226          * adding their roots to the list while we are
2227          * doing this splice
2228          */
2229         mutex_lock(&root->fs_info->reloc_mutex);
2230         list_splice_init(&rc->reloc_roots, &reloc_roots);
2231         mutex_unlock(&root->fs_info->reloc_mutex);
2232
2233         while (!list_empty(&reloc_roots)) {
2234                 found = 1;
2235                 reloc_root = list_entry(reloc_roots.next,
2236                                         struct btrfs_root, root_list);
2237
2238                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2239                         root = read_fs_root(reloc_root->fs_info,
2240                                             reloc_root->root_key.offset);
2241                         BUG_ON(IS_ERR(root));
2242                         BUG_ON(root->reloc_root != reloc_root);
2243
2244                         ret = merge_reloc_root(rc, root);
2245                         BUG_ON(ret);
2246                 } else {
2247                         list_del_init(&reloc_root->root_list);
2248                 }
2249                 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2250         }
2251
2252         if (found) {
2253                 found = 0;
2254                 goto again;
2255         }
2256         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2257         return 0;
2258 }
2259
2260 static void free_block_list(struct rb_root *blocks)
2261 {
2262         struct tree_block *block;
2263         struct rb_node *rb_node;
2264         while ((rb_node = rb_first(blocks))) {
2265                 block = rb_entry(rb_node, struct tree_block, rb_node);
2266                 rb_erase(rb_node, blocks);
2267                 kfree(block);
2268         }
2269 }
2270
2271 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2272                                       struct btrfs_root *reloc_root)
2273 {
2274         struct btrfs_root *root;
2275
2276         if (reloc_root->last_trans == trans->transid)
2277                 return 0;
2278
2279         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2280         BUG_ON(IS_ERR(root));
2281         BUG_ON(root->reloc_root != reloc_root);
2282
2283         return btrfs_record_root_in_trans(trans, root);
2284 }
2285
2286 static noinline_for_stack
2287 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2288                                      struct reloc_control *rc,
2289                                      struct backref_node *node,
2290                                      struct backref_edge *edges[], int *nr)
2291 {
2292         struct backref_node *next;
2293         struct btrfs_root *root;
2294         int index = 0;
2295
2296         next = node;
2297         while (1) {
2298                 cond_resched();
2299                 next = walk_up_backref(next, edges, &index);
2300                 root = next->root;
2301                 BUG_ON(!root);
2302                 BUG_ON(!root->ref_cows);
2303
2304                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2305                         record_reloc_root_in_trans(trans, root);
2306                         break;
2307                 }
2308
2309                 btrfs_record_root_in_trans(trans, root);
2310                 root = root->reloc_root;
2311
2312                 if (next->new_bytenr != root->node->start) {
2313                         BUG_ON(next->new_bytenr);
2314                         BUG_ON(!list_empty(&next->list));
2315                         next->new_bytenr = root->node->start;
2316                         next->root = root;
2317                         list_add_tail(&next->list,
2318                                       &rc->backref_cache.changed);
2319                         __mark_block_processed(rc, next);
2320                         break;
2321                 }
2322
2323                 WARN_ON(1);
2324                 root = NULL;
2325                 next = walk_down_backref(edges, &index);
2326                 if (!next || next->level <= node->level)
2327                         break;
2328         }
2329         if (!root)
2330                 return NULL;
2331
2332         *nr = index;
2333         next = node;
2334         /* setup backref node path for btrfs_reloc_cow_block */
2335         while (1) {
2336                 rc->backref_cache.path[next->level] = next;
2337                 if (--index < 0)
2338                         break;
2339                 next = edges[index]->node[UPPER];
2340         }
2341         return root;
2342 }
2343
2344 /*
2345  * select a tree root for relocation. return NULL if the block
2346  * is reference counted. we should use do_relocation() in this
2347  * case. return a tree root pointer if the block isn't reference
2348  * counted. return -ENOENT if the block is root of reloc tree.
2349  */
2350 static noinline_for_stack
2351 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2352                                    struct backref_node *node)
2353 {
2354         struct backref_node *next;
2355         struct btrfs_root *root;
2356         struct btrfs_root *fs_root = NULL;
2357         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2358         int index = 0;
2359
2360         next = node;
2361         while (1) {
2362                 cond_resched();
2363                 next = walk_up_backref(next, edges, &index);
2364                 root = next->root;
2365                 BUG_ON(!root);
2366
2367                 /* no other choice for non-references counted tree */
2368                 if (!root->ref_cows)
2369                         return root;
2370
2371                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2372                         fs_root = root;
2373
2374                 if (next != node)
2375                         return NULL;
2376
2377                 next = walk_down_backref(edges, &index);
2378                 if (!next || next->level <= node->level)
2379                         break;
2380         }
2381
2382         if (!fs_root)
2383                 return ERR_PTR(-ENOENT);
2384         return fs_root;
2385 }
2386
2387 static noinline_for_stack
2388 u64 calcu_metadata_size(struct reloc_control *rc,
2389                         struct backref_node *node, int reserve)
2390 {
2391         struct backref_node *next = node;
2392         struct backref_edge *edge;
2393         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2394         u64 num_bytes = 0;
2395         int index = 0;
2396
2397         BUG_ON(reserve && node->processed);
2398
2399         while (next) {
2400                 cond_resched();
2401                 while (1) {
2402                         if (next->processed && (reserve || next != node))
2403                                 break;
2404
2405                         num_bytes += btrfs_level_size(rc->extent_root,
2406                                                       next->level);
2407
2408                         if (list_empty(&next->upper))
2409                                 break;
2410
2411                         edge = list_entry(next->upper.next,
2412                                           struct backref_edge, list[LOWER]);
2413                         edges[index++] = edge;
2414                         next = edge->node[UPPER];
2415                 }
2416                 next = walk_down_backref(edges, &index);
2417         }
2418         return num_bytes;
2419 }
2420
2421 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2422                                   struct reloc_control *rc,
2423                                   struct backref_node *node)
2424 {
2425         struct btrfs_root *root = rc->extent_root;
2426         u64 num_bytes;
2427         int ret;
2428
2429         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2430
2431         trans->block_rsv = rc->block_rsv;
2432         ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes);
2433         if (ret) {
2434                 if (ret == -EAGAIN)
2435                         rc->commit_transaction = 1;
2436                 return ret;
2437         }
2438
2439         return 0;
2440 }
2441
2442 static void release_metadata_space(struct reloc_control *rc,
2443                                    struct backref_node *node)
2444 {
2445         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2446         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2447 }
2448
2449 /*
2450  * relocate a block tree, and then update pointers in upper level
2451  * blocks that reference the block to point to the new location.
2452  *
2453  * if called by link_to_upper, the block has already been relocated.
2454  * in that case this function just updates pointers.
2455  */
2456 static int do_relocation(struct btrfs_trans_handle *trans,
2457                          struct reloc_control *rc,
2458                          struct backref_node *node,
2459                          struct btrfs_key *key,
2460                          struct btrfs_path *path, int lowest)
2461 {
2462         struct backref_node *upper;
2463         struct backref_edge *edge;
2464         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2465         struct btrfs_root *root;
2466         struct extent_buffer *eb;
2467         u32 blocksize;
2468         u64 bytenr;
2469         u64 generation;
2470         int nr;
2471         int slot;
2472         int ret;
2473         int err = 0;
2474
2475         BUG_ON(lowest && node->eb);
2476
2477         path->lowest_level = node->level + 1;
2478         rc->backref_cache.path[node->level] = node;
2479         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2480                 cond_resched();
2481
2482                 upper = edge->node[UPPER];
2483                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2484                 BUG_ON(!root);
2485
2486                 if (upper->eb && !upper->locked) {
2487                         if (!lowest) {
2488                                 ret = btrfs_bin_search(upper->eb, key,
2489                                                        upper->level, &slot);
2490                                 BUG_ON(ret);
2491                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2492                                 if (node->eb->start == bytenr)
2493                                         goto next;
2494                         }
2495                         drop_node_buffer(upper);
2496                 }
2497
2498                 if (!upper->eb) {
2499                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2500                         if (ret < 0) {
2501                                 err = ret;
2502                                 break;
2503                         }
2504                         BUG_ON(ret > 0);
2505
2506                         if (!upper->eb) {
2507                                 upper->eb = path->nodes[upper->level];
2508                                 path->nodes[upper->level] = NULL;
2509                         } else {
2510                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2511                         }
2512
2513                         upper->locked = 1;
2514                         path->locks[upper->level] = 0;
2515
2516                         slot = path->slots[upper->level];
2517                         btrfs_release_path(path);
2518                 } else {
2519                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2520                                                &slot);
2521                         BUG_ON(ret);
2522                 }
2523
2524                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2525                 if (lowest) {
2526                         BUG_ON(bytenr != node->bytenr);
2527                 } else {
2528                         if (node->eb->start == bytenr)
2529                                 goto next;
2530                 }
2531
2532                 blocksize = btrfs_level_size(root, node->level);
2533                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2534                 eb = read_tree_block(root, bytenr, blocksize, generation);
2535                 if (!eb) {
2536                         err = -EIO;
2537                         goto next;
2538                 }
2539                 btrfs_tree_lock(eb);
2540                 btrfs_set_lock_blocking(eb);
2541
2542                 if (!node->eb) {
2543                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2544                                               slot, &eb);
2545                         btrfs_tree_unlock(eb);
2546                         free_extent_buffer(eb);
2547                         if (ret < 0) {
2548                                 err = ret;
2549                                 goto next;
2550                         }
2551                         BUG_ON(node->eb != eb);
2552                 } else {
2553                         btrfs_set_node_blockptr(upper->eb, slot,
2554                                                 node->eb->start);
2555                         btrfs_set_node_ptr_generation(upper->eb, slot,
2556                                                       trans->transid);
2557                         btrfs_mark_buffer_dirty(upper->eb);
2558
2559                         ret = btrfs_inc_extent_ref(trans, root,
2560                                                 node->eb->start, blocksize,
2561                                                 upper->eb->start,
2562                                                 btrfs_header_owner(upper->eb),
2563                                                 node->level, 0, 1);
2564                         BUG_ON(ret);
2565
2566                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2567                         BUG_ON(ret);
2568                 }
2569 next:
2570                 if (!upper->pending)
2571                         drop_node_buffer(upper);
2572                 else
2573                         unlock_node_buffer(upper);
2574                 if (err)
2575                         break;
2576         }
2577
2578         if (!err && node->pending) {
2579                 drop_node_buffer(node);
2580                 list_move_tail(&node->list, &rc->backref_cache.changed);
2581                 node->pending = 0;
2582         }
2583
2584         path->lowest_level = 0;
2585         BUG_ON(err == -ENOSPC);
2586         return err;
2587 }
2588
2589 static int link_to_upper(struct btrfs_trans_handle *trans,
2590                          struct reloc_control *rc,
2591                          struct backref_node *node,
2592                          struct btrfs_path *path)
2593 {
2594         struct btrfs_key key;
2595
2596         btrfs_node_key_to_cpu(node->eb, &key, 0);
2597         return do_relocation(trans, rc, node, &key, path, 0);
2598 }
2599
2600 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2601                                 struct reloc_control *rc,
2602                                 struct btrfs_path *path, int err)
2603 {
2604         LIST_HEAD(list);
2605         struct backref_cache *cache = &rc->backref_cache;
2606         struct backref_node *node;
2607         int level;
2608         int ret;
2609
2610         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2611                 while (!list_empty(&cache->pending[level])) {
2612                         node = list_entry(cache->pending[level].next,
2613                                           struct backref_node, list);
2614                         list_move_tail(&node->list, &list);
2615                         BUG_ON(!node->pending);
2616
2617                         if (!err) {
2618                                 ret = link_to_upper(trans, rc, node, path);
2619                                 if (ret < 0)
2620                                         err = ret;
2621                         }
2622                 }
2623                 list_splice_init(&list, &cache->pending[level]);
2624         }
2625         return err;
2626 }
2627
2628 static void mark_block_processed(struct reloc_control *rc,
2629                                  u64 bytenr, u32 blocksize)
2630 {
2631         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2632                         EXTENT_DIRTY, GFP_NOFS);
2633 }
2634
2635 static void __mark_block_processed(struct reloc_control *rc,
2636                                    struct backref_node *node)
2637 {
2638         u32 blocksize;
2639         if (node->level == 0 ||
2640             in_block_group(node->bytenr, rc->block_group)) {
2641                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2642                 mark_block_processed(rc, node->bytenr, blocksize);
2643         }
2644         node->processed = 1;
2645 }
2646
2647 /*
2648  * mark a block and all blocks directly/indirectly reference the block
2649  * as processed.
2650  */
2651 static void update_processed_blocks(struct reloc_control *rc,
2652                                     struct backref_node *node)
2653 {
2654         struct backref_node *next = node;
2655         struct backref_edge *edge;
2656         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2657         int index = 0;
2658
2659         while (next) {
2660                 cond_resched();
2661                 while (1) {
2662                         if (next->processed)
2663                                 break;
2664
2665                         __mark_block_processed(rc, next);
2666
2667                         if (list_empty(&next->upper))
2668                                 break;
2669
2670                         edge = list_entry(next->upper.next,
2671                                           struct backref_edge, list[LOWER]);
2672                         edges[index++] = edge;
2673                         next = edge->node[UPPER];
2674                 }
2675                 next = walk_down_backref(edges, &index);
2676         }
2677 }
2678
2679 static int tree_block_processed(u64 bytenr, u32 blocksize,
2680                                 struct reloc_control *rc)
2681 {
2682         if (test_range_bit(&rc->processed_blocks, bytenr,
2683                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2684                 return 1;
2685         return 0;
2686 }
2687
2688 static int get_tree_block_key(struct reloc_control *rc,
2689                               struct tree_block *block)
2690 {
2691         struct extent_buffer *eb;
2692
2693         BUG_ON(block->key_ready);
2694         eb = read_tree_block(rc->extent_root, block->bytenr,
2695                              block->key.objectid, block->key.offset);
2696         BUG_ON(!eb);
2697         WARN_ON(btrfs_header_level(eb) != block->level);
2698         if (block->level == 0)
2699                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2700         else
2701                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2702         free_extent_buffer(eb);
2703         block->key_ready = 1;
2704         return 0;
2705 }
2706
2707 static int reada_tree_block(struct reloc_control *rc,
2708                             struct tree_block *block)
2709 {
2710         BUG_ON(block->key_ready);
2711         readahead_tree_block(rc->extent_root, block->bytenr,
2712                              block->key.objectid, block->key.offset);
2713         return 0;
2714 }
2715
2716 /*
2717  * helper function to relocate a tree block
2718  */
2719 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2720                                 struct reloc_control *rc,
2721                                 struct backref_node *node,
2722                                 struct btrfs_key *key,
2723                                 struct btrfs_path *path)
2724 {
2725         struct btrfs_root *root;
2726         int release = 0;
2727         int ret = 0;
2728
2729         if (!node)
2730                 return 0;
2731
2732         BUG_ON(node->processed);
2733         root = select_one_root(trans, node);
2734         if (root == ERR_PTR(-ENOENT)) {
2735                 update_processed_blocks(rc, node);
2736                 goto out;
2737         }
2738
2739         if (!root || root->ref_cows) {
2740                 ret = reserve_metadata_space(trans, rc, node);
2741                 if (ret)
2742                         goto out;
2743                 release = 1;
2744         }
2745
2746         if (root) {
2747                 if (root->ref_cows) {
2748                         BUG_ON(node->new_bytenr);
2749                         BUG_ON(!list_empty(&node->list));
2750                         btrfs_record_root_in_trans(trans, root);
2751                         root = root->reloc_root;
2752                         node->new_bytenr = root->node->start;
2753                         node->root = root;
2754                         list_add_tail(&node->list, &rc->backref_cache.changed);
2755                 } else {
2756                         path->lowest_level = node->level;
2757                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2758                         btrfs_release_path(path);
2759                         if (ret > 0)
2760                                 ret = 0;
2761                 }
2762                 if (!ret)
2763                         update_processed_blocks(rc, node);
2764         } else {
2765                 ret = do_relocation(trans, rc, node, key, path, 1);
2766         }
2767 out:
2768         if (ret || node->level == 0 || node->cowonly) {
2769                 if (release)
2770                         release_metadata_space(rc, node);
2771                 remove_backref_node(&rc->backref_cache, node);
2772         }
2773         return ret;
2774 }
2775
2776 /*
2777  * relocate a list of blocks
2778  */
2779 static noinline_for_stack
2780 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2781                          struct reloc_control *rc, struct rb_root *blocks)
2782 {
2783         struct backref_node *node;
2784         struct btrfs_path *path;
2785         struct tree_block *block;
2786         struct rb_node *rb_node;
2787         int ret;
2788         int err = 0;
2789
2790         path = btrfs_alloc_path();
2791         if (!path)
2792                 return -ENOMEM;
2793
2794         rb_node = rb_first(blocks);
2795         while (rb_node) {
2796                 block = rb_entry(rb_node, struct tree_block, rb_node);
2797                 if (!block->key_ready)
2798                         reada_tree_block(rc, block);
2799                 rb_node = rb_next(rb_node);
2800         }
2801
2802         rb_node = rb_first(blocks);
2803         while (rb_node) {
2804                 block = rb_entry(rb_node, struct tree_block, rb_node);
2805                 if (!block->key_ready)
2806                         get_tree_block_key(rc, block);
2807                 rb_node = rb_next(rb_node);
2808         }
2809
2810         rb_node = rb_first(blocks);
2811         while (rb_node) {
2812                 block = rb_entry(rb_node, struct tree_block, rb_node);
2813
2814                 node = build_backref_tree(rc, &block->key,
2815                                           block->level, block->bytenr);
2816                 if (IS_ERR(node)) {
2817                         err = PTR_ERR(node);
2818                         goto out;
2819                 }
2820
2821                 ret = relocate_tree_block(trans, rc, node, &block->key,
2822                                           path);
2823                 if (ret < 0) {
2824                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2825                                 err = ret;
2826                         goto out;
2827                 }
2828                 rb_node = rb_next(rb_node);
2829         }
2830 out:
2831         free_block_list(blocks);
2832         err = finish_pending_nodes(trans, rc, path, err);
2833
2834         btrfs_free_path(path);
2835         return err;
2836 }
2837
2838 static noinline_for_stack
2839 int prealloc_file_extent_cluster(struct inode *inode,
2840                                  struct file_extent_cluster *cluster)
2841 {
2842         u64 alloc_hint = 0;
2843         u64 start;
2844         u64 end;
2845         u64 offset = BTRFS_I(inode)->index_cnt;
2846         u64 num_bytes;
2847         int nr = 0;
2848         int ret = 0;
2849
2850         BUG_ON(cluster->start != cluster->boundary[0]);
2851         mutex_lock(&inode->i_mutex);
2852
2853         ret = btrfs_check_data_free_space(inode, cluster->end +
2854                                           1 - cluster->start);
2855         if (ret)
2856                 goto out;
2857
2858         while (nr < cluster->nr) {
2859                 start = cluster->boundary[nr] - offset;
2860                 if (nr + 1 < cluster->nr)
2861                         end = cluster->boundary[nr + 1] - 1 - offset;
2862                 else
2863                         end = cluster->end - offset;
2864
2865                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2866                 num_bytes = end + 1 - start;
2867                 ret = btrfs_prealloc_file_range(inode, 0, start,
2868                                                 num_bytes, num_bytes,
2869                                                 end + 1, &alloc_hint);
2870                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2871                 if (ret)
2872                         break;
2873                 nr++;
2874         }
2875         btrfs_free_reserved_data_space(inode, cluster->end +
2876                                        1 - cluster->start);
2877 out:
2878         mutex_unlock(&inode->i_mutex);
2879         return ret;
2880 }
2881
2882 static noinline_for_stack
2883 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2884                          u64 block_start)
2885 {
2886         struct btrfs_root *root = BTRFS_I(inode)->root;
2887         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2888         struct extent_map *em;
2889         int ret = 0;
2890
2891         em = alloc_extent_map();
2892         if (!em)
2893                 return -ENOMEM;
2894
2895         em->start = start;
2896         em->len = end + 1 - start;
2897         em->block_len = em->len;
2898         em->block_start = block_start;
2899         em->bdev = root->fs_info->fs_devices->latest_bdev;
2900         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2901
2902         lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2903         while (1) {
2904                 write_lock(&em_tree->lock);
2905                 ret = add_extent_mapping(em_tree, em);
2906                 write_unlock(&em_tree->lock);
2907                 if (ret != -EEXIST) {
2908                         free_extent_map(em);
2909                         break;
2910                 }
2911                 btrfs_drop_extent_cache(inode, start, end, 0);
2912         }
2913         unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2914         return ret;
2915 }
2916
2917 static int relocate_file_extent_cluster(struct inode *inode,
2918                                         struct file_extent_cluster *cluster)
2919 {
2920         u64 page_start;
2921         u64 page_end;
2922         u64 offset = BTRFS_I(inode)->index_cnt;
2923         unsigned long index;
2924         unsigned long last_index;
2925         struct page *page;
2926         struct file_ra_state *ra;
2927         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
2928         int nr = 0;
2929         int ret = 0;
2930
2931         if (!cluster->nr)
2932                 return 0;
2933
2934         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2935         if (!ra)
2936                 return -ENOMEM;
2937
2938         ret = prealloc_file_extent_cluster(inode, cluster);
2939         if (ret)
2940                 goto out;
2941
2942         file_ra_state_init(ra, inode->i_mapping);
2943
2944         ret = setup_extent_mapping(inode, cluster->start - offset,
2945                                    cluster->end - offset, cluster->start);
2946         if (ret)
2947                 goto out;
2948
2949         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2950         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2951         while (index <= last_index) {
2952                 mutex_lock(&inode->i_mutex);
2953                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2954                 mutex_unlock(&inode->i_mutex);
2955                 if (ret)
2956                         goto out;
2957
2958                 page = find_lock_page(inode->i_mapping, index);
2959                 if (!page) {
2960                         page_cache_sync_readahead(inode->i_mapping,
2961                                                   ra, NULL, index,
2962                                                   last_index + 1 - index);
2963                         page = find_or_create_page(inode->i_mapping, index,
2964                                                    mask);
2965                         if (!page) {
2966                                 btrfs_delalloc_release_metadata(inode,
2967                                                         PAGE_CACHE_SIZE);
2968                                 ret = -ENOMEM;
2969                                 goto out;
2970                         }
2971                 }
2972
2973                 if (PageReadahead(page)) {
2974                         page_cache_async_readahead(inode->i_mapping,
2975                                                    ra, NULL, page, index,
2976                                                    last_index + 1 - index);
2977                 }
2978
2979                 if (!PageUptodate(page)) {
2980                         btrfs_readpage(NULL, page);
2981                         lock_page(page);
2982                         if (!PageUptodate(page)) {
2983                                 unlock_page(page);
2984                                 page_cache_release(page);
2985                                 btrfs_delalloc_release_metadata(inode,
2986                                                         PAGE_CACHE_SIZE);
2987                                 ret = -EIO;
2988                                 goto out;
2989                         }
2990                 }
2991
2992                 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2993                 page_end = page_start + PAGE_CACHE_SIZE - 1;
2994
2995                 lock_extent(&BTRFS_I(inode)->io_tree,
2996                             page_start, page_end, GFP_NOFS);
2997
2998                 set_page_extent_mapped(page);
2999
3000                 if (nr < cluster->nr &&
3001                     page_start + offset == cluster->boundary[nr]) {
3002                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3003                                         page_start, page_end,
3004                                         EXTENT_BOUNDARY, GFP_NOFS);
3005                         nr++;
3006                 }
3007
3008                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3009                 set_page_dirty(page);
3010
3011                 unlock_extent(&BTRFS_I(inode)->io_tree,
3012                               page_start, page_end, GFP_NOFS);
3013                 unlock_page(page);
3014                 page_cache_release(page);
3015
3016                 index++;
3017                 balance_dirty_pages_ratelimited(inode->i_mapping);
3018                 btrfs_throttle(BTRFS_I(inode)->root);
3019         }
3020         WARN_ON(nr != cluster->nr);
3021 out:
3022         kfree(ra);
3023         return ret;
3024 }
3025
3026 static noinline_for_stack
3027 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3028                          struct file_extent_cluster *cluster)
3029 {
3030         int ret;
3031
3032         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3033                 ret = relocate_file_extent_cluster(inode, cluster);
3034                 if (ret)
3035                         return ret;
3036                 cluster->nr = 0;
3037         }
3038
3039         if (!cluster->nr)
3040                 cluster->start = extent_key->objectid;
3041         else
3042                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3043         cluster->end = extent_key->objectid + extent_key->offset - 1;
3044         cluster->boundary[cluster->nr] = extent_key->objectid;
3045         cluster->nr++;
3046
3047         if (cluster->nr >= MAX_EXTENTS) {
3048                 ret = relocate_file_extent_cluster(inode, cluster);
3049                 if (ret)
3050                         return ret;
3051                 cluster->nr = 0;
3052         }
3053         return 0;
3054 }
3055
3056 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3057 static int get_ref_objectid_v0(struct reloc_control *rc,
3058                                struct btrfs_path *path,
3059                                struct btrfs_key *extent_key,
3060                                u64 *ref_objectid, int *path_change)
3061 {
3062         struct btrfs_key key;
3063         struct extent_buffer *leaf;
3064         struct btrfs_extent_ref_v0 *ref0;
3065         int ret;
3066         int slot;
3067
3068         leaf = path->nodes[0];
3069         slot = path->slots[0];
3070         while (1) {
3071                 if (slot >= btrfs_header_nritems(leaf)) {
3072                         ret = btrfs_next_leaf(rc->extent_root, path);
3073                         if (ret < 0)
3074                                 return ret;
3075                         BUG_ON(ret > 0);
3076                         leaf = path->nodes[0];
3077                         slot = path->slots[0];
3078                         if (path_change)
3079                                 *path_change = 1;
3080                 }
3081                 btrfs_item_key_to_cpu(leaf, &key, slot);
3082                 if (key.objectid != extent_key->objectid)
3083                         return -ENOENT;
3084
3085                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3086                         slot++;
3087                         continue;
3088                 }
3089                 ref0 = btrfs_item_ptr(leaf, slot,
3090                                 struct btrfs_extent_ref_v0);
3091                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3092                 break;
3093         }
3094         return 0;
3095 }
3096 #endif
3097
3098 /*
3099  * helper to add a tree block to the list.
3100  * the major work is getting the generation and level of the block
3101  */
3102 static int add_tree_block(struct reloc_control *rc,
3103                           struct btrfs_key *extent_key,
3104                           struct btrfs_path *path,
3105                           struct rb_root *blocks)
3106 {
3107         struct extent_buffer *eb;
3108         struct btrfs_extent_item *ei;
3109         struct btrfs_tree_block_info *bi;
3110         struct tree_block *block;
3111         struct rb_node *rb_node;
3112         u32 item_size;
3113         int level = -1;
3114         int generation;
3115
3116         eb =  path->nodes[0];
3117         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3118
3119         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3120                 ei = btrfs_item_ptr(eb, path->slots[0],
3121                                 struct btrfs_extent_item);
3122                 bi = (struct btrfs_tree_block_info *)(ei + 1);
3123                 generation = btrfs_extent_generation(eb, ei);
3124                 level = btrfs_tree_block_level(eb, bi);
3125         } else {
3126 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3127                 u64 ref_owner;
3128                 int ret;
3129
3130                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3131                 ret = get_ref_objectid_v0(rc, path, extent_key,
3132                                           &ref_owner, NULL);
3133                 if (ret < 0)
3134                         return ret;
3135                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3136                 level = (int)ref_owner;
3137                 /* FIXME: get real generation */
3138                 generation = 0;
3139 #else
3140                 BUG();
3141 #endif
3142         }
3143
3144         btrfs_release_path(path);
3145
3146         BUG_ON(level == -1);
3147
3148         block = kmalloc(sizeof(*block), GFP_NOFS);
3149         if (!block)
3150                 return -ENOMEM;
3151
3152         block->bytenr = extent_key->objectid;
3153         block->key.objectid = extent_key->offset;
3154         block->key.offset = generation;
3155         block->level = level;
3156         block->key_ready = 0;
3157
3158         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3159         BUG_ON(rb_node);
3160
3161         return 0;
3162 }
3163
3164 /*
3165  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3166  */
3167 static int __add_tree_block(struct reloc_control *rc,
3168                             u64 bytenr, u32 blocksize,
3169                             struct rb_root *blocks)
3170 {
3171         struct btrfs_path *path;
3172         struct btrfs_key key;
3173         int ret;
3174
3175         if (tree_block_processed(bytenr, blocksize, rc))
3176                 return 0;
3177
3178         if (tree_search(blocks, bytenr))
3179                 return 0;
3180
3181         path = btrfs_alloc_path();
3182         if (!path)
3183                 return -ENOMEM;
3184
3185         key.objectid = bytenr;
3186         key.type = BTRFS_EXTENT_ITEM_KEY;
3187         key.offset = blocksize;
3188
3189         path->search_commit_root = 1;
3190         path->skip_locking = 1;
3191         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3192         if (ret < 0)
3193                 goto out;
3194         BUG_ON(ret);
3195
3196         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3197         ret = add_tree_block(rc, &key, path, blocks);
3198 out:
3199         btrfs_free_path(path);
3200         return ret;
3201 }
3202
3203 /*
3204  * helper to check if the block use full backrefs for pointers in it
3205  */
3206 static int block_use_full_backref(struct reloc_control *rc,
3207                                   struct extent_buffer *eb)
3208 {
3209         u64 flags;
3210         int ret;
3211
3212         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3213             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3214                 return 1;
3215
3216         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3217                                        eb->start, eb->len, NULL, &flags);
3218         BUG_ON(ret);
3219
3220         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3221                 ret = 1;
3222         else
3223                 ret = 0;
3224         return ret;
3225 }
3226
3227 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3228                                     struct inode *inode, u64 ino)
3229 {
3230         struct btrfs_key key;
3231         struct btrfs_path *path;
3232         struct btrfs_root *root = fs_info->tree_root;
3233         struct btrfs_trans_handle *trans;
3234         unsigned long nr;
3235         int ret = 0;
3236
3237         if (inode)
3238                 goto truncate;
3239
3240         key.objectid = ino;
3241         key.type = BTRFS_INODE_ITEM_KEY;
3242         key.offset = 0;
3243
3244         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3245         if (IS_ERR_OR_NULL(inode) || is_bad_inode(inode)) {
3246                 if (inode && !IS_ERR(inode))
3247                         iput(inode);
3248                 return -ENOENT;
3249         }
3250
3251 truncate:
3252         path = btrfs_alloc_path();
3253         if (!path) {
3254                 ret = -ENOMEM;
3255                 goto out;
3256         }
3257
3258         trans = btrfs_join_transaction(root);
3259         if (IS_ERR(trans)) {
3260                 btrfs_free_path(path);
3261                 ret = PTR_ERR(trans);
3262                 goto out;
3263         }
3264
3265         ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3266
3267         btrfs_free_path(path);
3268         nr = trans->blocks_used;
3269         btrfs_end_transaction(trans, root);
3270         btrfs_btree_balance_dirty(root, nr);
3271 out:
3272         iput(inode);
3273         return ret;
3274 }
3275
3276 /*
3277  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3278  * this function scans fs tree to find blocks reference the data extent
3279  */
3280 static int find_data_references(struct reloc_control *rc,
3281                                 struct btrfs_key *extent_key,
3282                                 struct extent_buffer *leaf,
3283                                 struct btrfs_extent_data_ref *ref,
3284                                 struct rb_root *blocks)
3285 {
3286         struct btrfs_path *path;
3287         struct tree_block *block;
3288         struct btrfs_root *root;
3289         struct btrfs_file_extent_item *fi;
3290         struct rb_node *rb_node;
3291         struct btrfs_key key;
3292         u64 ref_root;
3293         u64 ref_objectid;
3294         u64 ref_offset;
3295         u32 ref_count;
3296         u32 nritems;
3297         int err = 0;
3298         int added = 0;
3299         int counted;
3300         int ret;
3301
3302         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3303         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3304         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3305         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3306
3307         /*
3308          * This is an extent belonging to the free space cache, lets just delete
3309          * it and redo the search.
3310          */
3311         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3312                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3313                                                NULL, ref_objectid);
3314                 if (ret != -ENOENT)
3315                         return ret;
3316                 ret = 0;
3317         }
3318
3319         path = btrfs_alloc_path();
3320         if (!path)
3321                 return -ENOMEM;
3322         path->reada = 1;
3323
3324         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3325         if (IS_ERR(root)) {
3326                 err = PTR_ERR(root);
3327                 goto out;
3328         }
3329
3330         key.objectid = ref_objectid;
3331         key.type = BTRFS_EXTENT_DATA_KEY;
3332         if (ref_offset > ((u64)-1 << 32))
3333                 key.offset = 0;
3334         else
3335                 key.offset = ref_offset;
3336
3337         path->search_commit_root = 1;
3338         path->skip_locking = 1;
3339         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3340         if (ret < 0) {
3341                 err = ret;
3342                 goto out;
3343         }
3344
3345         leaf = path->nodes[0];
3346         nritems = btrfs_header_nritems(leaf);
3347         /*
3348          * the references in tree blocks that use full backrefs
3349          * are not counted in
3350          */
3351         if (block_use_full_backref(rc, leaf))
3352                 counted = 0;
3353         else
3354                 counted = 1;
3355         rb_node = tree_search(blocks, leaf->start);
3356         if (rb_node) {
3357                 if (counted)
3358                         added = 1;
3359                 else
3360                         path->slots[0] = nritems;
3361         }
3362
3363         while (ref_count > 0) {
3364                 while (path->slots[0] >= nritems) {
3365                         ret = btrfs_next_leaf(root, path);
3366                         if (ret < 0) {
3367                                 err = ret;
3368                                 goto out;
3369                         }
3370                         if (ret > 0) {
3371                                 WARN_ON(1);
3372                                 goto out;
3373                         }
3374
3375                         leaf = path->nodes[0];
3376                         nritems = btrfs_header_nritems(leaf);
3377                         added = 0;
3378
3379                         if (block_use_full_backref(rc, leaf))
3380                                 counted = 0;
3381                         else
3382                                 counted = 1;
3383                         rb_node = tree_search(blocks, leaf->start);
3384                         if (rb_node) {
3385                                 if (counted)
3386                                         added = 1;
3387                                 else
3388                                         path->slots[0] = nritems;
3389                         }
3390                 }
3391
3392                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3393                 if (key.objectid != ref_objectid ||
3394                     key.type != BTRFS_EXTENT_DATA_KEY) {
3395                         WARN_ON(1);
3396                         break;
3397                 }
3398
3399                 fi = btrfs_item_ptr(leaf, path->slots[0],
3400                                     struct btrfs_file_extent_item);
3401
3402                 if (btrfs_file_extent_type(leaf, fi) ==
3403                     BTRFS_FILE_EXTENT_INLINE)
3404                         goto next;
3405
3406                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3407                     extent_key->objectid)
3408                         goto next;
3409
3410                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3411                 if (key.offset != ref_offset)
3412                         goto next;
3413
3414                 if (counted)
3415                         ref_count--;
3416                 if (added)
3417                         goto next;
3418
3419                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3420                         block = kmalloc(sizeof(*block), GFP_NOFS);
3421                         if (!block) {
3422                                 err = -ENOMEM;
3423                                 break;
3424                         }
3425                         block->bytenr = leaf->start;
3426                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3427                         block->level = 0;
3428                         block->key_ready = 1;
3429                         rb_node = tree_insert(blocks, block->bytenr,
3430                                               &block->rb_node);
3431                         BUG_ON(rb_node);
3432                 }
3433                 if (counted)
3434                         added = 1;
3435                 else
3436                         path->slots[0] = nritems;
3437 next:
3438                 path->slots[0]++;
3439
3440         }
3441 out:
3442         btrfs_free_path(path);
3443         return err;
3444 }
3445
3446 /*
3447  * hepler to find all tree blocks that reference a given data extent
3448  */
3449 static noinline_for_stack
3450 int add_data_references(struct reloc_control *rc,
3451                         struct btrfs_key *extent_key,
3452                         struct btrfs_path *path,
3453                         struct rb_root *blocks)
3454 {
3455         struct btrfs_key key;
3456         struct extent_buffer *eb;
3457         struct btrfs_extent_data_ref *dref;
3458         struct btrfs_extent_inline_ref *iref;
3459         unsigned long ptr;
3460         unsigned long end;
3461         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3462         int ret;
3463         int err = 0;
3464
3465         eb = path->nodes[0];
3466         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3467         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3468 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3469         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3470                 ptr = end;
3471         else
3472 #endif
3473                 ptr += sizeof(struct btrfs_extent_item);
3474
3475         while (ptr < end) {
3476                 iref = (struct btrfs_extent_inline_ref *)ptr;
3477                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3478                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3479                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3480                         ret = __add_tree_block(rc, key.offset, blocksize,
3481                                                blocks);
3482                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3483                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3484                         ret = find_data_references(rc, extent_key,
3485                                                    eb, dref, blocks);
3486                 } else {
3487                         BUG();
3488                 }
3489                 ptr += btrfs_extent_inline_ref_size(key.type);
3490         }
3491         WARN_ON(ptr > end);
3492
3493         while (1) {
3494                 cond_resched();
3495                 eb = path->nodes[0];
3496                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3497                         ret = btrfs_next_leaf(rc->extent_root, path);
3498                         if (ret < 0) {
3499                                 err = ret;
3500                                 break;
3501                         }
3502                         if (ret > 0)
3503                                 break;
3504                         eb = path->nodes[0];
3505                 }
3506
3507                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3508                 if (key.objectid != extent_key->objectid)
3509                         break;
3510
3511 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3512                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3513                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3514 #else
3515                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3516                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3517 #endif
3518                         ret = __add_tree_block(rc, key.offset, blocksize,
3519                                                blocks);
3520                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3521                         dref = btrfs_item_ptr(eb, path->slots[0],
3522                                               struct btrfs_extent_data_ref);
3523                         ret = find_data_references(rc, extent_key,
3524                                                    eb, dref, blocks);
3525                 } else {
3526                         ret = 0;
3527                 }
3528                 if (ret) {
3529                         err = ret;
3530                         break;
3531                 }
3532                 path->slots[0]++;
3533         }
3534         btrfs_release_path(path);
3535         if (err)
3536                 free_block_list(blocks);
3537         return err;
3538 }
3539
3540 /*
3541  * hepler to find next unprocessed extent
3542  */
3543 static noinline_for_stack
3544 int find_next_extent(struct btrfs_trans_handle *trans,
3545                      struct reloc_control *rc, struct btrfs_path *path,
3546                      struct btrfs_key *extent_key)
3547 {
3548         struct btrfs_key key;
3549         struct extent_buffer *leaf;
3550         u64 start, end, last;
3551         int ret;
3552
3553         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3554         while (1) {
3555                 cond_resched();
3556                 if (rc->search_start >= last) {
3557                         ret = 1;
3558                         break;
3559                 }
3560
3561                 key.objectid = rc->search_start;
3562                 key.type = BTRFS_EXTENT_ITEM_KEY;
3563                 key.offset = 0;
3564
3565                 path->search_commit_root = 1;
3566                 path->skip_locking = 1;
3567                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3568                                         0, 0);
3569                 if (ret < 0)
3570                         break;
3571 next:
3572                 leaf = path->nodes[0];
3573                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3574                         ret = btrfs_next_leaf(rc->extent_root, path);
3575                         if (ret != 0)
3576                                 break;
3577                         leaf = path->nodes[0];
3578                 }
3579
3580                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3581                 if (key.objectid >= last) {
3582                         ret = 1;
3583                         break;
3584                 }
3585
3586                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3587                     key.objectid + key.offset <= rc->search_start) {
3588                         path->slots[0]++;
3589                         goto next;
3590                 }
3591
3592                 ret = find_first_extent_bit(&rc->processed_blocks,
3593                                             key.objectid, &start, &end,
3594                                             EXTENT_DIRTY);
3595
3596                 if (ret == 0 && start <= key.objectid) {
3597                         btrfs_release_path(path);
3598                         rc->search_start = end + 1;
3599                 } else {
3600                         rc->search_start = key.objectid + key.offset;
3601                         memcpy(extent_key, &key, sizeof(key));
3602                         return 0;
3603                 }
3604         }
3605         btrfs_release_path(path);
3606         return ret;
3607 }
3608
3609 static void set_reloc_control(struct reloc_control *rc)
3610 {
3611         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3612
3613         mutex_lock(&fs_info->reloc_mutex);
3614         fs_info->reloc_ctl = rc;
3615         mutex_unlock(&fs_info->reloc_mutex);
3616 }
3617
3618 static void unset_reloc_control(struct reloc_control *rc)
3619 {
3620         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3621
3622         mutex_lock(&fs_info->reloc_mutex);
3623         fs_info->reloc_ctl = NULL;
3624         mutex_unlock(&fs_info->reloc_mutex);
3625 }
3626
3627 static int check_extent_flags(u64 flags)
3628 {
3629         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3630             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3631                 return 1;
3632         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3633             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3634                 return 1;
3635         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3636             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3637                 return 1;
3638         return 0;
3639 }
3640
3641 static noinline_for_stack
3642 int prepare_to_relocate(struct reloc_control *rc)
3643 {
3644         struct btrfs_trans_handle *trans;
3645         int ret;
3646
3647         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root);
3648         if (!rc->block_rsv)
3649                 return -ENOMEM;
3650
3651         /*
3652          * reserve some space for creating reloc trees.
3653          * btrfs_init_reloc_root will use them when there
3654          * is no reservation in transaction handle.
3655          */
3656         ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3657                                   rc->extent_root->nodesize * 256);
3658         if (ret)
3659                 return ret;
3660
3661         memset(&rc->cluster, 0, sizeof(rc->cluster));
3662         rc->search_start = rc->block_group->key.objectid;
3663         rc->extents_found = 0;
3664         rc->nodes_relocated = 0;
3665         rc->merging_rsv_size = 0;
3666
3667         rc->create_reloc_tree = 1;
3668         set_reloc_control(rc);
3669
3670         trans = btrfs_join_transaction(rc->extent_root);
3671         BUG_ON(IS_ERR(trans));
3672         btrfs_commit_transaction(trans, rc->extent_root);
3673         return 0;
3674 }
3675
3676 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3677 {
3678         struct rb_root blocks = RB_ROOT;
3679         struct btrfs_key key;
3680         struct btrfs_trans_handle *trans = NULL;
3681         struct btrfs_path *path;
3682         struct btrfs_extent_item *ei;
3683         unsigned long nr;
3684         u64 flags;
3685         u32 item_size;
3686         int ret;
3687         int err = 0;
3688         int progress = 0;
3689
3690         path = btrfs_alloc_path();
3691         if (!path)
3692                 return -ENOMEM;
3693         path->reada = 1;
3694
3695         ret = prepare_to_relocate(rc);
3696         if (ret) {
3697                 err = ret;
3698                 goto out_free;
3699         }
3700
3701         while (1) {
3702                 progress++;
3703                 trans = btrfs_start_transaction(rc->extent_root, 0);
3704                 BUG_ON(IS_ERR(trans));
3705 restart:
3706                 if (update_backref_cache(trans, &rc->backref_cache)) {
3707                         btrfs_end_transaction(trans, rc->extent_root);
3708                         continue;
3709                 }
3710
3711                 ret = find_next_extent(trans, rc, path, &key);
3712                 if (ret < 0)
3713                         err = ret;
3714                 if (ret != 0)
3715                         break;
3716
3717                 rc->extents_found++;
3718
3719                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3720                                     struct btrfs_extent_item);
3721                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3722                 if (item_size >= sizeof(*ei)) {
3723                         flags = btrfs_extent_flags(path->nodes[0], ei);
3724                         ret = check_extent_flags(flags);
3725                         BUG_ON(ret);
3726
3727                 } else {
3728 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3729                         u64 ref_owner;
3730                         int path_change = 0;
3731
3732                         BUG_ON(item_size !=
3733                                sizeof(struct btrfs_extent_item_v0));
3734                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3735                                                   &path_change);
3736                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3737                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3738                         else
3739                                 flags = BTRFS_EXTENT_FLAG_DATA;
3740
3741                         if (path_change) {
3742                                 btrfs_release_path(path);
3743
3744                                 path->search_commit_root = 1;
3745                                 path->skip_locking = 1;
3746                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3747                                                         &key, path, 0, 0);
3748                                 if (ret < 0) {
3749                                         err = ret;
3750                                         break;
3751                                 }
3752                                 BUG_ON(ret > 0);
3753                         }
3754 #else
3755                         BUG();
3756 #endif
3757                 }
3758
3759                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3760                         ret = add_tree_block(rc, &key, path, &blocks);
3761                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3762                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3763                         ret = add_data_references(rc, &key, path, &blocks);
3764                 } else {
3765                         btrfs_release_path(path);
3766                         ret = 0;
3767                 }
3768                 if (ret < 0) {
3769                         err = ret;
3770                         break;
3771                 }
3772
3773                 if (!RB_EMPTY_ROOT(&blocks)) {
3774                         ret = relocate_tree_blocks(trans, rc, &blocks);
3775                         if (ret < 0) {
3776                                 if (ret != -EAGAIN) {
3777                                         err = ret;
3778                                         break;
3779                                 }
3780                                 rc->extents_found--;
3781                                 rc->search_start = key.objectid;
3782                         }
3783                 }
3784
3785                 ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
3786                 if (ret < 0) {
3787                         if (ret != -EAGAIN) {
3788                                 err = ret;
3789                                 WARN_ON(1);
3790                                 break;
3791                         }
3792                         rc->commit_transaction = 1;
3793                 }
3794
3795                 if (rc->commit_transaction) {
3796                         rc->commit_transaction = 0;
3797                         ret = btrfs_commit_transaction(trans, rc->extent_root);
3798                         BUG_ON(ret);
3799                 } else {
3800                         nr = trans->blocks_used;
3801                         btrfs_end_transaction_throttle(trans, rc->extent_root);
3802                         btrfs_btree_balance_dirty(rc->extent_root, nr);
3803                 }
3804                 trans = NULL;
3805
3806                 if (rc->stage == MOVE_DATA_EXTENTS &&
3807                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3808                         rc->found_file_extent = 1;
3809                         ret = relocate_data_extent(rc->data_inode,
3810                                                    &key, &rc->cluster);
3811                         if (ret < 0) {
3812                                 err = ret;
3813                                 break;
3814                         }
3815                 }
3816         }
3817         if (trans && progress && err == -ENOSPC) {
3818                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
3819                                               rc->block_group->flags);
3820                 if (ret == 0) {
3821                         err = 0;
3822                         progress = 0;
3823                         goto restart;
3824                 }
3825         }
3826
3827         btrfs_release_path(path);
3828         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3829                           GFP_NOFS);
3830
3831         if (trans) {
3832                 nr = trans->blocks_used;
3833                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3834                 btrfs_btree_balance_dirty(rc->extent_root, nr);
3835         }
3836
3837         if (!err) {
3838                 ret = relocate_file_extent_cluster(rc->data_inode,
3839                                                    &rc->cluster);
3840                 if (ret < 0)
3841                         err = ret;
3842         }
3843
3844         rc->create_reloc_tree = 0;
3845         set_reloc_control(rc);
3846
3847         backref_cache_cleanup(&rc->backref_cache);
3848         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3849
3850         err = prepare_to_merge(rc, err);
3851
3852         merge_reloc_roots(rc);
3853
3854         rc->merge_reloc_tree = 0;
3855         unset_reloc_control(rc);
3856         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3857
3858         /* get rid of pinned extents */
3859         trans = btrfs_join_transaction(rc->extent_root);
3860         if (IS_ERR(trans))
3861                 err = PTR_ERR(trans);
3862         else
3863                 btrfs_commit_transaction(trans, rc->extent_root);
3864 out_free:
3865         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3866         btrfs_free_path(path);
3867         return err;
3868 }
3869
3870 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3871                                  struct btrfs_root *root, u64 objectid)
3872 {
3873         struct btrfs_path *path;
3874         struct btrfs_inode_item *item;
3875         struct extent_buffer *leaf;
3876         int ret;
3877
3878         path = btrfs_alloc_path();
3879         if (!path)
3880                 return -ENOMEM;
3881
3882         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3883         if (ret)
3884                 goto out;
3885
3886         leaf = path->nodes[0];
3887         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3888         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3889         btrfs_set_inode_generation(leaf, item, 1);
3890         btrfs_set_inode_size(leaf, item, 0);
3891         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3892         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3893                                           BTRFS_INODE_PREALLOC);
3894         btrfs_mark_buffer_dirty(leaf);
3895         btrfs_release_path(path);
3896 out:
3897         btrfs_free_path(path);
3898         return ret;
3899 }
3900
3901 /*
3902  * helper to create inode for data relocation.
3903  * the inode is in data relocation tree and its link count is 0
3904  */
3905 static noinline_for_stack
3906 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3907                                  struct btrfs_block_group_cache *group)
3908 {
3909         struct inode *inode = NULL;
3910         struct btrfs_trans_handle *trans;
3911         struct btrfs_root *root;
3912         struct btrfs_key key;
3913         unsigned long nr;
3914         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3915         int err = 0;
3916
3917         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3918         if (IS_ERR(root))
3919                 return ERR_CAST(root);
3920
3921         trans = btrfs_start_transaction(root, 6);
3922         if (IS_ERR(trans))
3923                 return ERR_CAST(trans);
3924
3925         err = btrfs_find_free_objectid(root, &objectid);
3926         if (err)
3927                 goto out;
3928
3929         err = __insert_orphan_inode(trans, root, objectid);
3930         BUG_ON(err);
3931
3932         key.objectid = objectid;
3933         key.type = BTRFS_INODE_ITEM_KEY;
3934         key.offset = 0;
3935         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3936         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3937         BTRFS_I(inode)->index_cnt = group->key.objectid;
3938
3939         err = btrfs_orphan_add(trans, inode);
3940 out:
3941         nr = trans->blocks_used;
3942         btrfs_end_transaction(trans, root);
3943         btrfs_btree_balance_dirty(root, nr);
3944         if (err) {
3945                 if (inode)
3946                         iput(inode);
3947                 inode = ERR_PTR(err);
3948         }
3949         return inode;
3950 }
3951
3952 static struct reloc_control *alloc_reloc_control(void)
3953 {
3954         struct reloc_control *rc;
3955
3956         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3957         if (!rc)
3958                 return NULL;
3959
3960         INIT_LIST_HEAD(&rc->reloc_roots);
3961         backref_cache_init(&rc->backref_cache);
3962         mapping_tree_init(&rc->reloc_root_tree);
3963         extent_io_tree_init(&rc->processed_blocks, NULL);
3964         return rc;
3965 }
3966
3967 /*
3968  * function to relocate all extents in a block group.
3969  */
3970 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3971 {
3972         struct btrfs_fs_info *fs_info = extent_root->fs_info;
3973         struct reloc_control *rc;
3974         struct inode *inode;
3975         struct btrfs_path *path;
3976         int ret;
3977         int rw = 0;
3978         int err = 0;
3979
3980         rc = alloc_reloc_control();
3981         if (!rc)
3982                 return -ENOMEM;
3983
3984         rc->extent_root = extent_root;
3985
3986         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3987         BUG_ON(!rc->block_group);
3988
3989         if (!rc->block_group->ro) {
3990                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
3991                 if (ret) {
3992                         err = ret;
3993                         goto out;
3994                 }
3995                 rw = 1;
3996         }
3997
3998         path = btrfs_alloc_path();
3999         if (!path) {
4000                 err = -ENOMEM;
4001                 goto out;
4002         }
4003
4004         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4005                                         path);
4006         btrfs_free_path(path);
4007
4008         if (!IS_ERR(inode))
4009                 ret = delete_block_group_cache(fs_info, inode, 0);
4010         else
4011                 ret = PTR_ERR(inode);
4012
4013         if (ret && ret != -ENOENT) {
4014                 err = ret;
4015                 goto out;
4016         }
4017
4018         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4019         if (IS_ERR(rc->data_inode)) {
4020                 err = PTR_ERR(rc->data_inode);
4021                 rc->data_inode = NULL;
4022                 goto out;
4023         }
4024
4025         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4026                (unsigned long long)rc->block_group->key.objectid,
4027                (unsigned long long)rc->block_group->flags);
4028
4029         btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
4030         btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
4031
4032         while (1) {
4033                 mutex_lock(&fs_info->cleaner_mutex);
4034
4035                 btrfs_clean_old_snapshots(fs_info->tree_root);
4036                 ret = relocate_block_group(rc);
4037
4038                 mutex_unlock(&fs_info->cleaner_mutex);
4039                 if (ret < 0) {
4040                         err = ret;
4041                         goto out;
4042                 }
4043
4044                 if (rc->extents_found == 0)
4045                         break;
4046
4047                 printk(KERN_INFO "btrfs: found %llu extents\n",
4048                         (unsigned long long)rc->extents_found);
4049
4050                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4051                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4052                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4053                                                  0, -1);
4054                         rc->stage = UPDATE_DATA_PTRS;
4055                 }
4056         }
4057
4058         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4059                                      rc->block_group->key.objectid,
4060                                      rc->block_group->key.objectid +
4061                                      rc->block_group->key.offset - 1);
4062
4063         WARN_ON(rc->block_group->pinned > 0);
4064         WARN_ON(rc->block_group->reserved > 0);
4065         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4066 out:
4067         if (err && rw)
4068                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4069         iput(rc->data_inode);
4070         btrfs_put_block_group(rc->block_group);
4071         kfree(rc);
4072         return err;
4073 }
4074
4075 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4076 {
4077         struct btrfs_trans_handle *trans;
4078         int ret;
4079
4080         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4081         BUG_ON(IS_ERR(trans));
4082
4083         memset(&root->root_item.drop_progress, 0,
4084                 sizeof(root->root_item.drop_progress));
4085         root->root_item.drop_level = 0;
4086         btrfs_set_root_refs(&root->root_item, 0);
4087         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4088                                 &root->root_key, &root->root_item);
4089         BUG_ON(ret);
4090
4091         ret = btrfs_end_transaction(trans, root->fs_info->tree_root);
4092         BUG_ON(ret);
4093         return 0;
4094 }
4095
4096 /*
4097  * recover relocation interrupted by system crash.
4098  *
4099  * this function resumes merging reloc trees with corresponding fs trees.
4100  * this is important for keeping the sharing of tree blocks
4101  */
4102 int btrfs_recover_relocation(struct btrfs_root *root)
4103 {
4104         LIST_HEAD(reloc_roots);
4105         struct btrfs_key key;
4106         struct btrfs_root *fs_root;
4107         struct btrfs_root *reloc_root;
4108         struct btrfs_path *path;
4109         struct extent_buffer *leaf;
4110         struct reloc_control *rc = NULL;
4111         struct btrfs_trans_handle *trans;
4112         int ret;
4113         int err = 0;
4114
4115         path = btrfs_alloc_path();
4116         if (!path)
4117                 return -ENOMEM;
4118         path->reada = -1;
4119
4120         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4121         key.type = BTRFS_ROOT_ITEM_KEY;
4122         key.offset = (u64)-1;
4123
4124         while (1) {
4125                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4126                                         path, 0, 0);
4127                 if (ret < 0) {
4128                         err = ret;
4129                         goto out;
4130                 }
4131                 if (ret > 0) {
4132                         if (path->slots[0] == 0)
4133                                 break;
4134                         path->slots[0]--;
4135                 }
4136                 leaf = path->nodes[0];
4137                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4138                 btrfs_release_path(path);
4139
4140                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4141                     key.type != BTRFS_ROOT_ITEM_KEY)
4142                         break;
4143
4144                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4145                 if (IS_ERR(reloc_root)) {
4146                         err = PTR_ERR(reloc_root);
4147                         goto out;
4148                 }
4149
4150                 list_add(&reloc_root->root_list, &reloc_roots);
4151
4152                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4153                         fs_root = read_fs_root(root->fs_info,
4154                                                reloc_root->root_key.offset);
4155                         if (IS_ERR(fs_root)) {
4156                                 ret = PTR_ERR(fs_root);
4157                                 if (ret != -ENOENT) {
4158                                         err = ret;
4159                                         goto out;
4160                                 }
4161                                 mark_garbage_root(reloc_root);
4162                         }
4163                 }
4164
4165                 if (key.offset == 0)
4166                         break;
4167
4168                 key.offset--;
4169         }
4170         btrfs_release_path(path);
4171
4172         if (list_empty(&reloc_roots))
4173                 goto out;
4174
4175         rc = alloc_reloc_control();
4176         if (!rc) {
4177                 err = -ENOMEM;
4178                 goto out;
4179         }
4180
4181         rc->extent_root = root->fs_info->extent_root;
4182
4183         set_reloc_control(rc);
4184
4185         trans = btrfs_join_transaction(rc->extent_root);
4186         if (IS_ERR(trans)) {
4187                 unset_reloc_control(rc);
4188                 err = PTR_ERR(trans);
4189                 goto out_free;
4190         }
4191
4192         rc->merge_reloc_tree = 1;
4193
4194         while (!list_empty(&reloc_roots)) {
4195                 reloc_root = list_entry(reloc_roots.next,
4196                                         struct btrfs_root, root_list);
4197                 list_del(&reloc_root->root_list);
4198
4199                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4200                         list_add_tail(&reloc_root->root_list,
4201                                       &rc->reloc_roots);
4202                         continue;
4203                 }
4204
4205                 fs_root = read_fs_root(root->fs_info,
4206                                        reloc_root->root_key.offset);
4207                 BUG_ON(IS_ERR(fs_root));
4208
4209                 __add_reloc_root(reloc_root);
4210                 fs_root->reloc_root = reloc_root;
4211         }
4212
4213         btrfs_commit_transaction(trans, rc->extent_root);
4214
4215         merge_reloc_roots(rc);
4216
4217         unset_reloc_control(rc);
4218
4219         trans = btrfs_join_transaction(rc->extent_root);
4220         if (IS_ERR(trans))
4221                 err = PTR_ERR(trans);
4222         else
4223                 btrfs_commit_transaction(trans, rc->extent_root);
4224 out_free:
4225         kfree(rc);
4226 out:
4227         while (!list_empty(&reloc_roots)) {
4228                 reloc_root = list_entry(reloc_roots.next,
4229                                         struct btrfs_root, root_list);
4230                 list_del(&reloc_root->root_list);
4231                 free_extent_buffer(reloc_root->node);
4232                 free_extent_buffer(reloc_root->commit_root);
4233                 kfree(reloc_root);
4234         }
4235         btrfs_free_path(path);
4236
4237         if (err == 0) {
4238                 /* cleanup orphan inode in data relocation tree */
4239                 fs_root = read_fs_root(root->fs_info,
4240                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4241                 if (IS_ERR(fs_root))
4242                         err = PTR_ERR(fs_root);
4243                 else
4244                         err = btrfs_orphan_cleanup(fs_root);
4245         }
4246         return err;
4247 }
4248
4249 /*
4250  * helper to add ordered checksum for data relocation.
4251  *
4252  * cloning checksum properly handles the nodatasum extents.
4253  * it also saves CPU time to re-calculate the checksum.
4254  */
4255 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4256 {
4257         struct btrfs_ordered_sum *sums;
4258         struct btrfs_sector_sum *sector_sum;
4259         struct btrfs_ordered_extent *ordered;
4260         struct btrfs_root *root = BTRFS_I(inode)->root;
4261         size_t offset;
4262         int ret;
4263         u64 disk_bytenr;
4264         LIST_HEAD(list);
4265
4266         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4267         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4268
4269         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4270         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4271                                        disk_bytenr + len - 1, &list, 0);
4272
4273         while (!list_empty(&list)) {
4274                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4275                 list_del_init(&sums->list);
4276
4277                 sector_sum = sums->sums;
4278                 sums->bytenr = ordered->start;
4279
4280                 offset = 0;
4281                 while (offset < sums->len) {
4282                         sector_sum->bytenr += ordered->start - disk_bytenr;
4283                         sector_sum++;
4284                         offset += root->sectorsize;
4285                 }
4286
4287                 btrfs_add_ordered_sum(inode, ordered, sums);
4288         }
4289         btrfs_put_ordered_extent(ordered);
4290         return ret;
4291 }
4292
4293 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4294                            struct btrfs_root *root, struct extent_buffer *buf,
4295                            struct extent_buffer *cow)
4296 {
4297         struct reloc_control *rc;
4298         struct backref_node *node;
4299         int first_cow = 0;
4300         int level;
4301         int ret;
4302
4303         rc = root->fs_info->reloc_ctl;
4304         if (!rc)
4305                 return;
4306
4307         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4308                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4309
4310         level = btrfs_header_level(buf);
4311         if (btrfs_header_generation(buf) <=
4312             btrfs_root_last_snapshot(&root->root_item))
4313                 first_cow = 1;
4314
4315         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4316             rc->create_reloc_tree) {
4317                 WARN_ON(!first_cow && level == 0);
4318
4319                 node = rc->backref_cache.path[level];
4320                 BUG_ON(node->bytenr != buf->start &&
4321                        node->new_bytenr != buf->start);
4322
4323                 drop_node_buffer(node);
4324                 extent_buffer_get(cow);
4325                 node->eb = cow;
4326                 node->new_bytenr = cow->start;
4327
4328                 if (!node->pending) {
4329                         list_move_tail(&node->list,
4330                                        &rc->backref_cache.pending[level]);
4331                         node->pending = 1;
4332                 }
4333
4334                 if (first_cow)
4335                         __mark_block_processed(rc, node);
4336
4337                 if (first_cow && level > 0)
4338                         rc->nodes_relocated += buf->len;
4339         }
4340
4341         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4342                 ret = replace_file_extents(trans, rc, root, cow);
4343                 BUG_ON(ret);
4344         }
4345 }
4346
4347 /*
4348  * called before creating snapshot. it calculates metadata reservation
4349  * requried for relocating tree blocks in the snapshot
4350  */
4351 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4352                               struct btrfs_pending_snapshot *pending,
4353                               u64 *bytes_to_reserve)
4354 {
4355         struct btrfs_root *root;
4356         struct reloc_control *rc;
4357
4358         root = pending->root;
4359         if (!root->reloc_root)
4360                 return;
4361
4362         rc = root->fs_info->reloc_ctl;
4363         if (!rc->merge_reloc_tree)
4364                 return;
4365
4366         root = root->reloc_root;
4367         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4368         /*
4369          * relocation is in the stage of merging trees. the space
4370          * used by merging a reloc tree is twice the size of
4371          * relocated tree nodes in the worst case. half for cowing
4372          * the reloc tree, half for cowing the fs tree. the space
4373          * used by cowing the reloc tree will be freed after the
4374          * tree is dropped. if we create snapshot, cowing the fs
4375          * tree may use more space than it frees. so we need
4376          * reserve extra space.
4377          */
4378         *bytes_to_reserve += rc->nodes_relocated;
4379 }
4380
4381 /*
4382  * called after snapshot is created. migrate block reservation
4383  * and create reloc root for the newly created snapshot
4384  */
4385 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4386                                struct btrfs_pending_snapshot *pending)
4387 {
4388         struct btrfs_root *root = pending->root;
4389         struct btrfs_root *reloc_root;
4390         struct btrfs_root *new_root;
4391         struct reloc_control *rc;
4392         int ret;
4393
4394         if (!root->reloc_root)
4395                 return;
4396
4397         rc = root->fs_info->reloc_ctl;
4398         rc->merging_rsv_size += rc->nodes_relocated;
4399
4400         if (rc->merge_reloc_tree) {
4401                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4402                                               rc->block_rsv,
4403                                               rc->nodes_relocated);
4404                 BUG_ON(ret);
4405         }
4406
4407         new_root = pending->snap;
4408         reloc_root = create_reloc_root(trans, root->reloc_root,
4409                                        new_root->root_key.objectid);
4410
4411         __add_reloc_root(reloc_root);
4412         new_root->reloc_root = reloc_root;
4413
4414         if (rc->create_reloc_tree) {
4415                 ret = clone_backref_node(trans, rc, root, reloc_root);
4416                 BUG_ON(ret);
4417         }
4418 }