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
  33 /*
  34  * backref_node, mapping_node and tree_block start with this
  35  */
  36 struct tree_entry {
  37         struct rb_node rb_node;
  38         u64 bytenr;
  39 };
  40
  41 /*
  42  * present a tree block in the backref cache
  43  */
  44 struct backref_node {
  45         struct rb_node rb_node;
  46         u64 bytenr;
  47
  48         u64 new_bytenr;
  49         /* objectid of tree block owner, can be not uptodate */
  50         u64 owner;
  51         /* link to pending, changed or detached list */
  52         struct list_head list;
  53         /* list of upper level blocks reference this block */
  54         struct list_head upper;
  55         /* list of child blocks in the cache */
  56         struct list_head lower;
  57         /* NULL if this node is not tree root */
  58         struct btrfs_root *root;
  59         /* extent buffer got by COW the block */
  60         struct extent_buffer *eb;
  61         /* level of tree block */
  62         unsigned int level:8;
  63         /* is the block in non-reference counted tree */
  64         unsigned int cowonly:1;
  65         /* 1 if no child node in the cache */
  66         unsigned int lowest:1;
  67         /* is the extent buffer locked */
  68         unsigned int locked:1;
  69         /* has the block been processed */
  70         unsigned int processed:1;
  71         /* have backrefs of this block been checked */
  72         unsigned int checked:1;
  73         /*
  74          * 1 if corresponding block has been cowed but some upper
  75          * level block pointers may not point to the new location
  76          */
  77         unsigned int pending:1;
  78         /*
  79          * 1 if the backref node isn't connected to any other
  80          * backref node.
  81          */
  82         unsigned int detached:1;
  83 };
  84
  85 /*
  86  * present a block pointer in the backref cache
  87  */
  88 struct backref_edge {
  89         struct list_head list[2];
  90         struct backref_node *node[2];
  91 };
  92
  93 #define LOWER   0
  94 #define UPPER   1
  95
  96 struct backref_cache {
  97         /* red black tree of all backref nodes in the cache */
  98         struct rb_root rb_root;
  99         /* for passing backref nodes to btrfs_reloc_cow_block */
 100         struct backref_node *path[BTRFS_MAX_LEVEL];
 101         /*
 102          * list of blocks that have been cowed but some block
 103          * pointers in upper level blocks may not reflect the
 104          * new location
 105          */
 106         struct list_head pending[BTRFS_MAX_LEVEL];
 107         /* list of backref nodes with no child node */
 108         struct list_head leaves;
 109         /* list of blocks that have been cowed in current transaction */
 110         struct list_head changed;
 111         /* list of detached backref node. */
 112         struct list_head detached;
 113
 114         u64 last_trans;
 115
 116         int nr_nodes;
 117         int nr_edges;
 118 };
 119
 120 /*
 121  * map address of tree root to tree
 122  */
 123 struct mapping_node {
 124         struct rb_node rb_node;
 125         u64 bytenr;
 126         void *data;
 127 };
 128
 129 struct mapping_tree {
 130         struct rb_root rb_root;
 131         spinlock_t lock;
 132 };
 133
 134 /*
 135  * present a tree block to process
 136  */
 137 struct tree_block {
 138         struct rb_node rb_node;
 139         u64 bytenr;
 140         struct btrfs_key key;
 141         unsigned int level:8;
 142         unsigned int key_ready:1;
 143 };
 144
 145 #define MAX_EXTENTS 128
 146
 147 struct file_extent_cluster {
 148         u64 start;
 149         u64 end;
 150         u64 boundary[MAX_EXTENTS];
 151         unsigned int nr;
 152 };
 153
 154 struct reloc_control {
 155         /* block group to relocate */
 156         struct btrfs_block_group_cache *block_group;
 157         /* extent tree */
 158         struct btrfs_root *extent_root;
 159         /* inode for moving data */
 160         struct inode *data_inode;
 161
 162         struct btrfs_block_rsv *block_rsv;
 163
 164         struct backref_cache backref_cache;
 165
 166         struct file_extent_cluster cluster;
 167         /* tree blocks have been processed */
 168         struct extent_io_tree processed_blocks;
 169         /* map start of tree root to corresponding reloc tree */
 170         struct mapping_tree reloc_root_tree;
 171         /* list of reloc trees */
 172         struct list_head reloc_roots;
 173         /* size of metadata reservation for merging reloc trees */
 174         u64 merging_rsv_size;
 175         /* size of relocated tree nodes */
 176         u64 nodes_relocated;
 177
 178         u64 search_start;
 179         u64 extents_found;
 180
 181         int block_rsv_retries;
 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 static int should_ignore_root(struct btrfs_root *root)
 512 {
 513         struct btrfs_root *reloc_root;
 514
 515         if (!root->ref_cows)
 516                 return 0;
 517
 518         reloc_root = root->reloc_root;
 519         if (!reloc_root)
 520                 return 0;
 521
 522         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 523             root->fs_info->running_transaction->transid - 1)
 524                 return 0;
 525         /*
 526          * if there is reloc tree and it was created in previous
 527          * transaction backref lookup can find the reloc tree,
 528          * so backref node for the fs tree root is useless for
 529          * relocation.
 530          */
 531         return 1;
 532 }
 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
 681         node = alloc_backref_node(cache);
 682         if (!node) {
 683                 err = -ENOMEM;
 684                 goto out;
 685         }
 686
 687         node->bytenr = bytenr;
 688         node->level = level;
 689         node->lowest = 1;
 690         cur = node;
 691 again:
 692         end = 0;
 693         ptr = 0;
 694         key.objectid = cur->bytenr;
 695         key.type = BTRFS_EXTENT_ITEM_KEY;
 696         key.offset = (u64)-1;
 697
 698         path1->search_commit_root = 1;
 699         path1->skip_locking = 1;
 700         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 701                                 0, 0);
 702         if (ret < 0) {
 703                 err = ret;
 704                 goto out;
 705         }
 706         BUG_ON(!ret || !path1->slots[0]);
 707
 708         path1->slots[0]--;
 709
 710         WARN_ON(cur->checked);
 711         if (!list_empty(&cur->upper)) {
 712                 /*
 713                  * the backref was added previously when processsing
 714                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 715                  */
 716                 BUG_ON(!list_is_singular(&cur->upper));
 717                 edge = list_entry(cur->upper.next, struct backref_edge,
 718                                   list[LOWER]);
 719                 BUG_ON(!list_empty(&edge->list[UPPER]));
 720                 exist = edge->node[UPPER];
 721                 /*
 722                  * add the upper level block to pending list if we need
 723                  * check its backrefs
 724                  */
 725                 if (!exist->checked)
 726                         list_add_tail(&edge->list[UPPER], &list);
 727         } else {
 728                 exist = NULL;
 729         }
 730
 731         while (1) {
 732                 cond_resched();
 733                 eb = path1->nodes[0];
 734
 735                 if (ptr >= end) {
 736                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 737                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 738                                 if (ret < 0) {
 739                                         err = ret;
 740                                         goto out;
 741                                 }
 742                                 if (ret > 0)
 743                                         break;
 744                                 eb = path1->nodes[0];
 745                         }
 746
 747                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 748                         if (key.objectid != cur->bytenr) {
 749                                 WARN_ON(exist);
 750                                 break;
 751                         }
 752
 753                         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 754                                 ret = find_inline_backref(eb, path1->slots[0],
 755                                                           &ptr, &end);
 756                                 if (ret)
 757                                         goto next;
 758                         }
 759                 }
 760
 761                 if (ptr < end) {
 762                         /* update key for inline back ref */
 763                         struct btrfs_extent_inline_ref *iref;
 764                         iref = (struct btrfs_extent_inline_ref *)ptr;
 765                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 766                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 767                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 768                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 769                 }
 770
 771                 if (exist &&
 772                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 773                       exist->owner == key.offset) ||
 774                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 775                       exist->bytenr == key.offset))) {
 776                         exist = NULL;
 777                         goto next;
 778                 }
 779
 780 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 781                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 782                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 783                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 784                                 struct btrfs_extent_ref_v0 *ref0;
 785                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 786                                                 struct btrfs_extent_ref_v0);
 787                                 if (key.objectid == key.offset) {
 788                                         root = find_tree_root(rc, eb, ref0);
 789                                         if (root && !should_ignore_root(root))
 790                                                 cur->root = root;
 791                                         else
 792                                                 list_add(&cur->list, &useless);
 793                                         break;
 794                                 }
 795                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 796                                                                       ref0)))
 797                                         cur->cowonly = 1;
 798                         }
 799 #else
 800                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 801                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 802 #endif
 803                         if (key.objectid == key.offset) {
 804                                 /*
 805                                  * only root blocks of reloc trees use
 806                                  * backref of this type.
 807                                  */
 808                                 root = find_reloc_root(rc, cur->bytenr);
 809                                 BUG_ON(!root);
 810                                 cur->root = root;
 811                                 break;
 812                         }
 813
 814                         edge = alloc_backref_edge(cache);
 815                         if (!edge) {
 816                                 err = -ENOMEM;
 817                                 goto out;
 818                         }
 819                         rb_node = tree_search(&cache->rb_root, key.offset);
 820                         if (!rb_node) {
 821                                 upper = alloc_backref_node(cache);
 822                                 if (!upper) {
 823                                         free_backref_edge(cache, edge);
 824                                         err = -ENOMEM;
 825                                         goto out;
 826                                 }
 827                                 upper->bytenr = key.offset;
 828                                 upper->level = cur->level + 1;
 829                                 /*
 830                                  *  backrefs for the upper level block isn't
 831                                  *  cached, add the block to pending list
 832                                  */
 833                                 list_add_tail(&edge->list[UPPER], &list);
 834                         } else {
 835                                 upper = rb_entry(rb_node, struct backref_node,
 836                                                  rb_node);
 837                                 BUG_ON(!upper->checked);
 838                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 839                         }
 840                         list_add_tail(&edge->list[LOWER], &cur->upper);
 841                         edge->node[LOWER] = cur;
 842                         edge->node[UPPER] = upper;
 843
 844                         goto next;
 845                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 846                         goto next;
 847                 }
 848
 849                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 850                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 851                 if (IS_ERR(root)) {
 852                         err = PTR_ERR(root);
 853                         goto out;
 854                 }
 855
 856                 if (!root->ref_cows)
 857                         cur->cowonly = 1;
 858
 859                 if (btrfs_root_level(&root->root_item) == cur->level) {
 860                         /* tree root */
 861                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 862                                cur->bytenr);
 863                         if (should_ignore_root(root))
 864                                 list_add(&cur->list, &useless);
 865                         else
 866                                 cur->root = root;
 867                         break;
 868                 }
 869
 870                 level = cur->level + 1;
 871
 872                 /*
 873                  * searching the tree to find upper level blocks
 874                  * reference the block.
 875                  */
 876                 path2->search_commit_root = 1;
 877                 path2->skip_locking = 1;
 878                 path2->lowest_level = level;
 879                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 880                 path2->lowest_level = 0;
 881                 if (ret < 0) {
 882                         err = ret;
 883                         goto out;
 884                 }
 885                 if (ret > 0 && path2->slots[level] > 0)
 886                         path2->slots[level]--;
 887
 888                 eb = path2->nodes[level];
 889                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 890                         cur->bytenr);
 891
 892                 lower = cur;
 893                 for (; level < BTRFS_MAX_LEVEL; level++) {
 894                         if (!path2->nodes[level]) {
 895                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 896                                        lower->bytenr);
 897                                 if (should_ignore_root(root))
 898                                         list_add(&lower->list, &useless);
 899                                 else
 900                                         lower->root = root;
 901                                 break;
 902                         }
 903
 904                         edge = alloc_backref_edge(cache);
 905                         if (!edge) {
 906                                 err = -ENOMEM;
 907                                 goto out;
 908                         }
 909
 910                         eb = path2->nodes[level];
 911                         rb_node = tree_search(&cache->rb_root, eb->start);
 912                         if (!rb_node) {
 913                                 upper = alloc_backref_node(cache);
 914                                 if (!upper) {
 915                                         free_backref_edge(cache, edge);
 916                                         err = -ENOMEM;
 917                                         goto out;
 918                                 }
 919                                 upper->bytenr = eb->start;
 920                                 upper->owner = btrfs_header_owner(eb);
 921                                 upper->level = lower->level + 1;
 922                                 if (!root->ref_cows)
 923                                         upper->cowonly = 1;
 924
 925                                 /*
 926                                  * if we know the block isn't shared
 927                                  * we can void checking its backrefs.
 928                                  */
 929                                 if (btrfs_block_can_be_shared(root, eb))
 930                                         upper->checked = 0;
 931                                 else
 932                                         upper->checked = 1;
 933
 934                                 /*
 935                                  * add the block to pending list if we
 936                                  * need check its backrefs. only block
 937                                  * at 'cur->level + 1' is added to the
 938                                  * tail of pending list. this guarantees
 939                                  * we check backrefs from lower level
 940                                  * blocks to upper level blocks.
 941                                  */
 942                                 if (!upper->checked &&
 943                                     level == cur->level + 1) {
 944                                         list_add_tail(&edge->list[UPPER],
 945                                                       &list);
 946                                 } else
 947                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 948                         } else {
 949                                 upper = rb_entry(rb_node, struct backref_node,
 950                                                  rb_node);
 951                                 BUG_ON(!upper->checked);
 952                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 953                                 if (!upper->owner)
 954                                         upper->owner = btrfs_header_owner(eb);
 955                         }
 956                         list_add_tail(&edge->list[LOWER], &lower->upper);
 957                         edge->node[LOWER] = lower;
 958                         edge->node[UPPER] = upper;
 959
 960                         if (rb_node)
 961                                 break;
 962                         lower = upper;
 963                         upper = NULL;
 964                 }
 965                 btrfs_release_path(root, path2);
 966 next:
 967                 if (ptr < end) {
 968                         ptr += btrfs_extent_inline_ref_size(key.type);
 969                         if (ptr >= end) {
 970                                 WARN_ON(ptr > end);
 971                                 ptr = 0;
 972                                 end = 0;
 973                         }
 974                 }
 975                 if (ptr >= end)
 976                         path1->slots[0]++;
 977         }
 978         btrfs_release_path(rc->extent_root, path1);
 979
 980         cur->checked = 1;
 981         WARN_ON(exist);
 982
 983         /* the pending list isn't empty, take the first block to process */
 984         if (!list_empty(&list)) {
 985                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 986                 list_del_init(&edge->list[UPPER]);
 987                 cur = edge->node[UPPER];
 988                 goto again;
 989         }
 990
 991         /*
 992          * everything goes well, connect backref nodes and insert backref nodes
 993          * into the cache.
 994          */
 995         BUG_ON(!node->checked);
 996         cowonly = node->cowonly;
 997         if (!cowonly) {
 998                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
 999                                       &node->rb_node);
1000                 BUG_ON(rb_node);
1001                 list_add_tail(&node->lower, &cache->leaves);
1002         }
1003
1004         list_for_each_entry(edge, &node->upper, list[LOWER])
1005                 list_add_tail(&edge->list[UPPER], &list);
1006
1007         while (!list_empty(&list)) {
1008                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1009                 list_del_init(&edge->list[UPPER]);
1010                 upper = edge->node[UPPER];
1011                 if (upper->detached) {
1012                         list_del(&edge->list[LOWER]);
1013                         lower = edge->node[LOWER];
1014                         free_backref_edge(cache, edge);
1015                         if (list_empty(&lower->upper))
1016                                 list_add(&lower->list, &useless);
1017                         continue;
1018                 }
1019
1020                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1021                         if (upper->lowest) {
1022                                 list_del_init(&upper->lower);
1023                                 upper->lowest = 0;
1024                         }
1025
1026                         list_add_tail(&edge->list[UPPER], &upper->lower);
1027                         continue;
1028                 }
1029
1030                 BUG_ON(!upper->checked);
1031                 BUG_ON(cowonly != upper->cowonly);
1032                 if (!cowonly) {
1033                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1034                                               &upper->rb_node);
1035                         BUG_ON(rb_node);
1036                 }
1037
1038                 list_add_tail(&edge->list[UPPER], &upper->lower);
1039
1040                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1041                         list_add_tail(&edge->list[UPPER], &list);
1042         }
1043         /*
1044          * process useless backref nodes. backref nodes for tree leaves
1045          * are deleted from the cache. backref nodes for upper level
1046          * tree blocks are left in the cache to avoid unnecessary backref
1047          * lookup.
1048          */
1049         while (!list_empty(&useless)) {
1050                 upper = list_entry(useless.next, struct backref_node, list);
1051                 list_del_init(&upper->list);
1052                 BUG_ON(!list_empty(&upper->upper));
1053                 if (upper == node)
1054                         node = NULL;
1055                 if (upper->lowest) {
1056                         list_del_init(&upper->lower);
1057                         upper->lowest = 0;
1058                 }
1059                 while (!list_empty(&upper->lower)) {
1060                         edge = list_entry(upper->lower.next,
1061                                           struct backref_edge, list[UPPER]);
1062                         list_del(&edge->list[UPPER]);
1063                         list_del(&edge->list[LOWER]);
1064                         lower = edge->node[LOWER];
1065                         free_backref_edge(cache, edge);
1066
1067                         if (list_empty(&lower->upper))
1068                                 list_add(&lower->list, &useless);
1069                 }
1070                 __mark_block_processed(rc, upper);
1071                 if (upper->level > 0) {
1072                         list_add(&upper->list, &cache->detached);
1073                         upper->detached = 1;
1074                 } else {
1075                         rb_erase(&upper->rb_node, &cache->rb_root);
1076                         free_backref_node(cache, upper);
1077                 }
1078         }
1079 out:
1080         btrfs_free_path(path1);
1081         btrfs_free_path(path2);
1082         if (err) {
1083                 while (!list_empty(&useless)) {
1084                         lower = list_entry(useless.next,
1085                                            struct backref_node, upper);
1086                         list_del_init(&lower->upper);
1087                 }
1088                 upper = node;
1089                 INIT_LIST_HEAD(&list);
1090                 while (upper) {
1091                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1092                                 list_splice_tail(&upper->upper, &list);
1093                                 free_backref_node(cache, upper);
1094                         }
1095
1096                         if (list_empty(&list))
1097                                 break;
1098
1099                         edge = list_entry(list.next, struct backref_edge,
1100                                           list[LOWER]);
1101                         list_del(&edge->list[LOWER]);
1102                         upper = edge->node[UPPER];
1103                         free_backref_edge(cache, edge);
1104                 }
1105                 return ERR_PTR(err);
1106         }
1107         BUG_ON(node && node->detached);
1108         return node;
1109 }
1110
1111 /*
1112  * helper to add backref node for the newly created snapshot.
1113  * the backref node is created by cloning backref node that
1114  * corresponds to root of source tree
1115  */
1116 static int clone_backref_node(struct btrfs_trans_handle *trans,
1117                               struct reloc_control *rc,
1118                               struct btrfs_root *src,
1119                               struct btrfs_root *dest)
1120 {
1121         struct btrfs_root *reloc_root = src->reloc_root;
1122         struct backref_cache *cache = &rc->backref_cache;
1123         struct backref_node *node = NULL;
1124         struct backref_node *new_node;
1125         struct backref_edge *edge;
1126         struct backref_edge *new_edge;
1127         struct rb_node *rb_node;
1128
1129         if (cache->last_trans > 0)
1130                 update_backref_cache(trans, cache);
1131
1132         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1133         if (rb_node) {
1134                 node = rb_entry(rb_node, struct backref_node, rb_node);
1135                 if (node->detached)
1136                         node = NULL;
1137                 else
1138                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1139         }
1140
1141         if (!node) {
1142                 rb_node = tree_search(&cache->rb_root,
1143                                       reloc_root->commit_root->start);
1144                 if (rb_node) {
1145                         node = rb_entry(rb_node, struct backref_node,
1146                                         rb_node);
1147                         BUG_ON(node->detached);
1148                 }
1149         }
1150
1151         if (!node)
1152                 return 0;
1153
1154         new_node = alloc_backref_node(cache);
1155         if (!new_node)
1156                 return -ENOMEM;
1157
1158         new_node->bytenr = dest->node->start;
1159         new_node->level = node->level;
1160         new_node->lowest = node->lowest;
1161         new_node->root = dest;
1162
1163         if (!node->lowest) {
1164                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1165                         new_edge = alloc_backref_edge(cache);
1166                         if (!new_edge)
1167                                 goto fail;
1168
1169                         new_edge->node[UPPER] = new_node;
1170                         new_edge->node[LOWER] = edge->node[LOWER];
1171                         list_add_tail(&new_edge->list[UPPER],
1172                                       &new_node->lower);
1173                 }
1174         }
1175
1176         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1177                               &new_node->rb_node);
1178         BUG_ON(rb_node);
1179
1180         if (!new_node->lowest) {
1181                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1182                         list_add_tail(&new_edge->list[LOWER],
1183                                       &new_edge->node[LOWER]->upper);
1184                 }
1185         }
1186         return 0;
1187 fail:
1188         while (!list_empty(&new_node->lower)) {
1189                 new_edge = list_entry(new_node->lower.next,
1190                                       struct backref_edge, list[UPPER]);
1191                 list_del(&new_edge->list[UPPER]);
1192                 free_backref_edge(cache, new_edge);
1193         }
1194         free_backref_node(cache, new_node);
1195         return -ENOMEM;
1196 }
1197
1198 /*
1199  * helper to add 'address of tree root -> reloc tree' mapping
1200  */
1201 static int __add_reloc_root(struct btrfs_root *root)
1202 {
1203         struct rb_node *rb_node;
1204         struct mapping_node *node;
1205         struct reloc_control *rc = root->fs_info->reloc_ctl;
1206
1207         node = kmalloc(sizeof(*node), GFP_NOFS);
1208         BUG_ON(!node);
1209
1210         node->bytenr = root->node->start;
1211         node->data = root;
1212
1213         spin_lock(&rc->reloc_root_tree.lock);
1214         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1215                               node->bytenr, &node->rb_node);
1216         spin_unlock(&rc->reloc_root_tree.lock);
1217         BUG_ON(rb_node);
1218
1219         list_add_tail(&root->root_list, &rc->reloc_roots);
1220         return 0;
1221 }
1222
1223 /*
1224  * helper to update/delete the 'address of tree root -> reloc tree'
1225  * mapping
1226  */
1227 static int __update_reloc_root(struct btrfs_root *root, int del)
1228 {
1229         struct rb_node *rb_node;
1230         struct mapping_node *node = NULL;
1231         struct reloc_control *rc = root->fs_info->reloc_ctl;
1232
1233         spin_lock(&rc->reloc_root_tree.lock);
1234         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1235                               root->commit_root->start);
1236         if (rb_node) {
1237                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1238                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1239         }
1240         spin_unlock(&rc->reloc_root_tree.lock);
1241
1242         BUG_ON((struct btrfs_root *)node->data != root);
1243
1244         if (!del) {
1245                 spin_lock(&rc->reloc_root_tree.lock);
1246                 node->bytenr = root->node->start;
1247                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1248                                       node->bytenr, &node->rb_node);
1249                 spin_unlock(&rc->reloc_root_tree.lock);
1250                 BUG_ON(rb_node);
1251         } else {
1252                 list_del_init(&root->root_list);
1253                 kfree(node);
1254         }
1255         return 0;
1256 }
1257
1258 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1259                                         struct btrfs_root *root, u64 objectid)
1260 {
1261         struct btrfs_root *reloc_root;
1262         struct extent_buffer *eb;
1263         struct btrfs_root_item *root_item;
1264         struct btrfs_key root_key;
1265         int ret;
1266
1267         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1268         BUG_ON(!root_item);
1269
1270         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1271         root_key.type = BTRFS_ROOT_ITEM_KEY;
1272         root_key.offset = objectid;
1273
1274         if (root->root_key.objectid == objectid) {
1275                 /* called by btrfs_init_reloc_root */
1276                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1277                                       BTRFS_TREE_RELOC_OBJECTID);
1278                 BUG_ON(ret);
1279
1280                 btrfs_set_root_last_snapshot(&root->root_item,
1281                                              trans->transid - 1);
1282         } else {
1283                 /*
1284                  * called by btrfs_reloc_post_snapshot_hook.
1285                  * the source tree is a reloc tree, all tree blocks
1286                  * modified after it was created have RELOC flag
1287                  * set in their headers. so it's OK to not update
1288                  * the 'last_snapshot'.
1289                  */
1290                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1291                                       BTRFS_TREE_RELOC_OBJECTID);
1292                 BUG_ON(ret);
1293         }
1294
1295         memcpy(root_item, &root->root_item, sizeof(*root_item));
1296         btrfs_set_root_bytenr(root_item, eb->start);
1297         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1298         btrfs_set_root_generation(root_item, trans->transid);
1299
1300         if (root->root_key.objectid == objectid) {
1301                 btrfs_set_root_refs(root_item, 0);
1302                 memset(&root_item->drop_progress, 0,
1303                        sizeof(struct btrfs_disk_key));
1304                 root_item->drop_level = 0;
1305         }
1306
1307         btrfs_tree_unlock(eb);
1308         free_extent_buffer(eb);
1309
1310         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1311                                 &root_key, root_item);
1312         BUG_ON(ret);
1313         kfree(root_item);
1314
1315         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1316                                                  &root_key);
1317         BUG_ON(IS_ERR(reloc_root));
1318         reloc_root->last_trans = trans->transid;
1319         return reloc_root;
1320 }
1321
1322 /*
1323  * create reloc tree for a given fs tree. reloc tree is just a
1324  * snapshot of the fs tree with special root objectid.
1325  */
1326 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1327                           struct btrfs_root *root)
1328 {
1329         struct btrfs_root *reloc_root;
1330         struct reloc_control *rc = root->fs_info->reloc_ctl;
1331         int clear_rsv = 0;
1332
1333         if (root->reloc_root) {
1334                 reloc_root = root->reloc_root;
1335                 reloc_root->last_trans = trans->transid;
1336                 return 0;
1337         }
1338
1339         if (!rc || !rc->create_reloc_tree ||
1340             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1341                 return 0;
1342
1343         if (!trans->block_rsv) {
1344                 trans->block_rsv = rc->block_rsv;
1345                 clear_rsv = 1;
1346         }
1347         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1348         if (clear_rsv)
1349                 trans->block_rsv = NULL;
1350
1351         __add_reloc_root(reloc_root);
1352         root->reloc_root = reloc_root;
1353         return 0;
1354 }
1355
1356 /*
1357  * update root item of reloc tree
1358  */
1359 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1360                             struct btrfs_root *root)
1361 {
1362         struct btrfs_root *reloc_root;
1363         struct btrfs_root_item *root_item;
1364         int del = 0;
1365         int ret;
1366
1367         if (!root->reloc_root)
1368                 return 0;
1369
1370         reloc_root = root->reloc_root;
1371         root_item = &reloc_root->root_item;
1372
1373         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1374             btrfs_root_refs(root_item) == 0) {
1375                 root->reloc_root = NULL;
1376                 del = 1;
1377         }
1378
1379         __update_reloc_root(reloc_root, del);
1380
1381         if (reloc_root->commit_root != reloc_root->node) {
1382                 btrfs_set_root_node(root_item, reloc_root->node);
1383                 free_extent_buffer(reloc_root->commit_root);
1384                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1385         }
1386
1387         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1388                                 &reloc_root->root_key, root_item);
1389         BUG_ON(ret);
1390         return 0;
1391 }
1392
1393 /*
1394  * helper to find first cached inode with inode number >= objectid
1395  * in a subvolume
1396  */
1397 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1398 {
1399         struct rb_node *node;
1400         struct rb_node *prev;
1401         struct btrfs_inode *entry;
1402         struct inode *inode;
1403
1404         spin_lock(&root->inode_lock);
1405 again:
1406         node = root->inode_tree.rb_node;
1407         prev = NULL;
1408         while (node) {
1409                 prev = node;
1410                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1411
1412                 if (objectid < entry->vfs_inode.i_ino)
1413                         node = node->rb_left;
1414                 else if (objectid > entry->vfs_inode.i_ino)
1415                         node = node->rb_right;
1416                 else
1417                         break;
1418         }
1419         if (!node) {
1420                 while (prev) {
1421                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1422                         if (objectid <= entry->vfs_inode.i_ino) {
1423                                 node = prev;
1424                                 break;
1425                         }
1426                         prev = rb_next(prev);
1427                 }
1428         }
1429         while (node) {
1430                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1431                 inode = igrab(&entry->vfs_inode);
1432                 if (inode) {
1433                         spin_unlock(&root->inode_lock);
1434                         return inode;
1435                 }
1436
1437                 objectid = entry->vfs_inode.i_ino + 1;
1438                 if (cond_resched_lock(&root->inode_lock))
1439                         goto again;
1440
1441                 node = rb_next(node);
1442         }
1443         spin_unlock(&root->inode_lock);
1444         return NULL;
1445 }
1446
1447 static int in_block_group(u64 bytenr,
1448                           struct btrfs_block_group_cache *block_group)
1449 {
1450         if (bytenr >= block_group->key.objectid &&
1451             bytenr < block_group->key.objectid + block_group->key.offset)
1452                 return 1;
1453         return 0;
1454 }
1455
1456 /*
1457  * get new location of data
1458  */
1459 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1460                             u64 bytenr, u64 num_bytes)
1461 {
1462         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1463         struct btrfs_path *path;
1464         struct btrfs_file_extent_item *fi;
1465         struct extent_buffer *leaf;
1466         int ret;
1467
1468         path = btrfs_alloc_path();
1469         if (!path)
1470                 return -ENOMEM;
1471
1472         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1473         ret = btrfs_lookup_file_extent(NULL, root, path, reloc_inode->i_ino,
1474                                        bytenr, 0);
1475         if (ret < 0)
1476                 goto out;
1477         if (ret > 0) {
1478                 ret = -ENOENT;
1479                 goto out;
1480         }
1481
1482         leaf = path->nodes[0];
1483         fi = btrfs_item_ptr(leaf, path->slots[0],
1484                             struct btrfs_file_extent_item);
1485
1486         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1487                btrfs_file_extent_compression(leaf, fi) ||
1488                btrfs_file_extent_encryption(leaf, fi) ||
1489                btrfs_file_extent_other_encoding(leaf, fi));
1490
1491         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1492                 ret = 1;
1493                 goto out;
1494         }
1495
1496         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1497         ret = 0;
1498 out:
1499         btrfs_free_path(path);
1500         return ret;
1501 }
1502
1503 /*
1504  * update file extent items in the tree leaf to point to
1505  * the new locations.
1506  */
1507 static noinline_for_stack
1508 int replace_file_extents(struct btrfs_trans_handle *trans,
1509                          struct reloc_control *rc,
1510                          struct btrfs_root *root,
1511                          struct extent_buffer *leaf)
1512 {
1513         struct btrfs_key key;
1514         struct btrfs_file_extent_item *fi;
1515         struct inode *inode = NULL;
1516         u64 parent;
1517         u64 bytenr;
1518         u64 new_bytenr = 0;
1519         u64 num_bytes;
1520         u64 end;
1521         u32 nritems;
1522         u32 i;
1523         int ret;
1524         int first = 1;
1525         int dirty = 0;
1526
1527         if (rc->stage != UPDATE_DATA_PTRS)
1528                 return 0;
1529
1530         /* reloc trees always use full backref */
1531         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1532                 parent = leaf->start;
1533         else
1534                 parent = 0;
1535
1536         nritems = btrfs_header_nritems(leaf);
1537         for (i = 0; i < nritems; i++) {
1538                 cond_resched();
1539                 btrfs_item_key_to_cpu(leaf, &key, i);
1540                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1541                         continue;
1542                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1543                 if (btrfs_file_extent_type(leaf, fi) ==
1544                     BTRFS_FILE_EXTENT_INLINE)
1545                         continue;
1546                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1547                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1548                 if (bytenr == 0)
1549                         continue;
1550                 if (!in_block_group(bytenr, rc->block_group))
1551                         continue;
1552
1553                 /*
1554                  * if we are modifying block in fs tree, wait for readpage
1555                  * to complete and drop the extent cache
1556                  */
1557                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1558                         if (first) {
1559                                 inode = find_next_inode(root, key.objectid);
1560                                 first = 0;
1561                         } else if (inode && inode->i_ino < key.objectid) {
1562                                 btrfs_add_delayed_iput(inode);
1563                                 inode = find_next_inode(root, key.objectid);
1564                         }
1565                         if (inode && inode->i_ino == key.objectid) {
1566                                 end = key.offset +
1567                                       btrfs_file_extent_num_bytes(leaf, fi);
1568                                 WARN_ON(!IS_ALIGNED(key.offset,
1569                                                     root->sectorsize));
1570                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1571                                 end--;
1572                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1573                                                       key.offset, end,
1574                                                       GFP_NOFS);
1575                                 if (!ret)
1576                                         continue;
1577
1578                                 btrfs_drop_extent_cache(inode, key.offset, end,
1579                                                         1);
1580                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1581                                               key.offset, end, GFP_NOFS);
1582                         }
1583                 }
1584
1585                 ret = get_new_location(rc->data_inode, &new_bytenr,
1586                                        bytenr, num_bytes);
1587                 if (ret > 0) {
1588                         WARN_ON(1);
1589                         continue;
1590                 }
1591                 BUG_ON(ret < 0);
1592
1593                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1594                 dirty = 1;
1595
1596                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1597                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1598                                            num_bytes, parent,
1599                                            btrfs_header_owner(leaf),
1600                                            key.objectid, key.offset);
1601                 BUG_ON(ret);
1602
1603                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1604                                         parent, btrfs_header_owner(leaf),
1605                                         key.objectid, key.offset);
1606                 BUG_ON(ret);
1607         }
1608         if (dirty)
1609                 btrfs_mark_buffer_dirty(leaf);
1610         if (inode)
1611                 btrfs_add_delayed_iput(inode);
1612         return 0;
1613 }
1614
1615 static noinline_for_stack
1616 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1617                      struct btrfs_path *path, int level)
1618 {
1619         struct btrfs_disk_key key1;
1620         struct btrfs_disk_key key2;
1621         btrfs_node_key(eb, &key1, slot);
1622         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1623         return memcmp(&key1, &key2, sizeof(key1));
1624 }
1625
1626 /*
1627  * try to replace tree blocks in fs tree with the new blocks
1628  * in reloc tree. tree blocks haven't been modified since the
1629  * reloc tree was create can be replaced.
1630  *
1631  * if a block was replaced, level of the block + 1 is returned.
1632  * if no block got replaced, 0 is returned. if there are other
1633  * errors, a negative error number is returned.
1634  */
1635 static noinline_for_stack
1636 int replace_path(struct btrfs_trans_handle *trans,
1637                  struct btrfs_root *dest, struct btrfs_root *src,
1638                  struct btrfs_path *path, struct btrfs_key *next_key,
1639                  int lowest_level, int max_level)
1640 {
1641         struct extent_buffer *eb;
1642         struct extent_buffer *parent;
1643         struct btrfs_key key;
1644         u64 old_bytenr;
1645         u64 new_bytenr;
1646         u64 old_ptr_gen;
1647         u64 new_ptr_gen;
1648         u64 last_snapshot;
1649         u32 blocksize;
1650         int cow = 0;
1651         int level;
1652         int ret;
1653         int slot;
1654
1655         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1656         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1657
1658         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1659 again:
1660         slot = path->slots[lowest_level];
1661         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1662
1663         eb = btrfs_lock_root_node(dest);
1664         btrfs_set_lock_blocking(eb);
1665         level = btrfs_header_level(eb);
1666
1667         if (level < lowest_level) {
1668                 btrfs_tree_unlock(eb);
1669                 free_extent_buffer(eb);
1670                 return 0;
1671         }
1672
1673         if (cow) {
1674                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1675                 BUG_ON(ret);
1676         }
1677         btrfs_set_lock_blocking(eb);
1678
1679         if (next_key) {
1680                 next_key->objectid = (u64)-1;
1681                 next_key->type = (u8)-1;
1682                 next_key->offset = (u64)-1;
1683         }
1684
1685         parent = eb;
1686         while (1) {
1687                 level = btrfs_header_level(parent);
1688                 BUG_ON(level < lowest_level);
1689
1690                 ret = btrfs_bin_search(parent, &key, level, &slot);
1691                 if (ret && slot > 0)
1692                         slot--;
1693
1694                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1695                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1696
1697                 old_bytenr = btrfs_node_blockptr(parent, slot);
1698                 blocksize = btrfs_level_size(dest, level - 1);
1699                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1700
1701                 if (level <= max_level) {
1702                         eb = path->nodes[level];
1703                         new_bytenr = btrfs_node_blockptr(eb,
1704                                                         path->slots[level]);
1705                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1706                                                         path->slots[level]);
1707                 } else {
1708                         new_bytenr = 0;
1709                         new_ptr_gen = 0;
1710                 }
1711
1712                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1713                         WARN_ON(1);
1714                         ret = level;
1715                         break;
1716                 }
1717
1718                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1719                     memcmp_node_keys(parent, slot, path, level)) {
1720                         if (level <= lowest_level) {
1721                                 ret = 0;
1722                                 break;
1723                         }
1724
1725                         eb = read_tree_block(dest, old_bytenr, blocksize,
1726                                              old_ptr_gen);
1727                         btrfs_tree_lock(eb);
1728                         if (cow) {
1729                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1730                                                       slot, &eb);
1731                                 BUG_ON(ret);
1732                         }
1733                         btrfs_set_lock_blocking(eb);
1734
1735                         btrfs_tree_unlock(parent);
1736                         free_extent_buffer(parent);
1737
1738                         parent = eb;
1739                         continue;
1740                 }
1741
1742                 if (!cow) {
1743                         btrfs_tree_unlock(parent);
1744                         free_extent_buffer(parent);
1745                         cow = 1;
1746                         goto again;
1747                 }
1748
1749                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1750                                       path->slots[level]);
1751                 btrfs_release_path(src, path);
1752
1753                 path->lowest_level = level;
1754                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1755                 path->lowest_level = 0;
1756                 BUG_ON(ret);
1757
1758                 /*
1759                  * swap blocks in fs tree and reloc tree.
1760                  */
1761                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1762                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1763                 btrfs_mark_buffer_dirty(parent);
1764
1765                 btrfs_set_node_blockptr(path->nodes[level],
1766                                         path->slots[level], old_bytenr);
1767                 btrfs_set_node_ptr_generation(path->nodes[level],
1768                                               path->slots[level], old_ptr_gen);
1769                 btrfs_mark_buffer_dirty(path->nodes[level]);
1770
1771                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1772                                         path->nodes[level]->start,
1773                                         src->root_key.objectid, level - 1, 0);
1774                 BUG_ON(ret);
1775                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1776                                         0, dest->root_key.objectid, level - 1,
1777                                         0);
1778                 BUG_ON(ret);
1779
1780                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1781                                         path->nodes[level]->start,
1782                                         src->root_key.objectid, level - 1, 0);
1783                 BUG_ON(ret);
1784
1785                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1786                                         0, dest->root_key.objectid, level - 1,
1787                                         0);
1788                 BUG_ON(ret);
1789
1790                 btrfs_unlock_up_safe(path, 0);
1791
1792                 ret = level;
1793                 break;
1794         }
1795         btrfs_tree_unlock(parent);
1796         free_extent_buffer(parent);
1797         return ret;
1798 }
1799
1800 /*
1801  * helper to find next relocated block in reloc tree
1802  */
1803 static noinline_for_stack
1804 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1805                        int *level)
1806 {
1807         struct extent_buffer *eb;
1808         int i;
1809         u64 last_snapshot;
1810         u32 nritems;
1811
1812         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1813
1814         for (i = 0; i < *level; i++) {
1815                 free_extent_buffer(path->nodes[i]);
1816                 path->nodes[i] = NULL;
1817         }
1818
1819         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1820                 eb = path->nodes[i];
1821                 nritems = btrfs_header_nritems(eb);
1822                 while (path->slots[i] + 1 < nritems) {
1823                         path->slots[i]++;
1824                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1825                             last_snapshot)
1826                                 continue;
1827
1828                         *level = i;
1829                         return 0;
1830                 }
1831                 free_extent_buffer(path->nodes[i]);
1832                 path->nodes[i] = NULL;
1833         }
1834         return 1;
1835 }
1836
1837 /*
1838  * walk down reloc tree to find relocated block of lowest level
1839  */
1840 static noinline_for_stack
1841 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1842                          int *level)
1843 {
1844         struct extent_buffer *eb = NULL;
1845         int i;
1846         u64 bytenr;
1847         u64 ptr_gen = 0;
1848         u64 last_snapshot;
1849         u32 blocksize;
1850         u32 nritems;
1851
1852         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1853
1854         for (i = *level; i > 0; i--) {
1855                 eb = path->nodes[i];
1856                 nritems = btrfs_header_nritems(eb);
1857                 while (path->slots[i] < nritems) {
1858                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1859                         if (ptr_gen > last_snapshot)
1860                                 break;
1861                         path->slots[i]++;
1862                 }
1863                 if (path->slots[i] >= nritems) {
1864                         if (i == *level)
1865                                 break;
1866                         *level = i + 1;
1867                         return 0;
1868                 }
1869                 if (i == 1) {
1870                         *level = i;
1871                         return 0;
1872                 }
1873
1874                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1875                 blocksize = btrfs_level_size(root, i - 1);
1876                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1877                 BUG_ON(btrfs_header_level(eb) != i - 1);
1878                 path->nodes[i - 1] = eb;
1879                 path->slots[i - 1] = 0;
1880         }
1881         return 1;
1882 }
1883
1884 /*
1885  * invalidate extent cache for file extents whose key in range of
1886  * [min_key, max_key)
1887  */
1888 static int invalidate_extent_cache(struct btrfs_root *root,
1889                                    struct btrfs_key *min_key,
1890                                    struct btrfs_key *max_key)
1891 {
1892         struct inode *inode = NULL;
1893         u64 objectid;
1894         u64 start, end;
1895
1896         objectid = min_key->objectid;
1897         while (1) {
1898                 cond_resched();
1899                 iput(inode);
1900
1901                 if (objectid > max_key->objectid)
1902                         break;
1903
1904                 inode = find_next_inode(root, objectid);
1905                 if (!inode)
1906                         break;
1907
1908                 if (inode->i_ino > max_key->objectid) {
1909                         iput(inode);
1910                         break;
1911                 }
1912
1913                 objectid = inode->i_ino + 1;
1914                 if (!S_ISREG(inode->i_mode))
1915                         continue;
1916
1917                 if (unlikely(min_key->objectid == inode->i_ino)) {
1918                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1919                                 continue;
1920                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1921                                 start = 0;
1922                         else {
1923                                 start = min_key->offset;
1924                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1925                         }
1926                 } else {
1927                         start = 0;
1928                 }
1929
1930                 if (unlikely(max_key->objectid == inode->i_ino)) {
1931                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1932                                 continue;
1933                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1934                                 end = (u64)-1;
1935                         } else {
1936                                 if (max_key->offset == 0)
1937                                         continue;
1938                                 end = max_key->offset;
1939                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1940                                 end--;
1941                         }
1942                 } else {
1943                         end = (u64)-1;
1944                 }
1945
1946                 /* the lock_extent waits for readpage to complete */
1947                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1948                 btrfs_drop_extent_cache(inode, start, end, 1);
1949                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1950         }
1951         return 0;
1952 }
1953
1954 static int find_next_key(struct btrfs_path *path, int level,
1955                          struct btrfs_key *key)
1956
1957 {
1958         while (level < BTRFS_MAX_LEVEL) {
1959                 if (!path->nodes[level])
1960                         break;
1961                 if (path->slots[level] + 1 <
1962                     btrfs_header_nritems(path->nodes[level])) {
1963                         btrfs_node_key_to_cpu(path->nodes[level], key,
1964                                               path->slots[level] + 1);
1965                         return 0;
1966                 }
1967                 level++;
1968         }
1969         return 1;
1970 }
1971
1972 /*
1973  * merge the relocated tree blocks in reloc tree with corresponding
1974  * fs tree.
1975  */
1976 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1977                                                struct btrfs_root *root)
1978 {
1979         LIST_HEAD(inode_list);
1980         struct btrfs_key key;
1981         struct btrfs_key next_key;
1982         struct btrfs_trans_handle *trans;
1983         struct btrfs_root *reloc_root;
1984         struct btrfs_root_item *root_item;
1985         struct btrfs_path *path;
1986         struct extent_buffer *leaf;
1987         unsigned long nr;
1988         int level;
1989         int max_level;
1990         int replaced = 0;
1991         int ret;
1992         int err = 0;
1993         u32 min_reserved;
1994
1995         path = btrfs_alloc_path();
1996         if (!path)
1997                 return -ENOMEM;
1998
1999         reloc_root = root->reloc_root;
2000         root_item = &reloc_root->root_item;
2001
2002         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2003                 level = btrfs_root_level(root_item);
2004                 extent_buffer_get(reloc_root->node);
2005                 path->nodes[level] = reloc_root->node;
2006                 path->slots[level] = 0;
2007         } else {
2008                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2009
2010                 level = root_item->drop_level;
2011                 BUG_ON(level == 0);
2012                 path->lowest_level = level;
2013                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2014                 path->lowest_level = 0;
2015                 if (ret < 0) {
2016                         btrfs_free_path(path);
2017                         return ret;
2018                 }
2019
2020                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2021                                       path->slots[level]);
2022                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2023
2024                 btrfs_unlock_up_safe(path, 0);
2025         }
2026
2027         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2028         memset(&next_key, 0, sizeof(next_key));
2029
2030         while (1) {
2031                 trans = btrfs_start_transaction(root, 0);
2032                 trans->block_rsv = rc->block_rsv;
2033
2034                 ret = btrfs_block_rsv_check(trans, root, rc->block_rsv,
2035                                             min_reserved, 0);
2036                 if (ret) {
2037                         BUG_ON(ret != -EAGAIN);
2038                         ret = btrfs_commit_transaction(trans, root);
2039                         BUG_ON(ret);
2040                         continue;
2041                 }
2042
2043                 replaced = 0;
2044                 max_level = level;
2045
2046                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2047                 if (ret < 0) {
2048                         err = ret;
2049                         goto out;
2050                 }
2051                 if (ret > 0)
2052                         break;
2053
2054                 if (!find_next_key(path, level, &key) &&
2055                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2056                         ret = 0;
2057                 } else {
2058                         ret = replace_path(trans, root, reloc_root, path,
2059                                            &next_key, level, max_level);
2060                 }
2061                 if (ret < 0) {
2062                         err = ret;
2063                         goto out;
2064                 }
2065
2066                 if (ret > 0) {
2067                         level = ret;
2068                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2069                                               path->slots[level]);
2070                         replaced = 1;
2071                 }
2072
2073                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2074                 if (ret > 0)
2075                         break;
2076
2077                 BUG_ON(level == 0);
2078                 /*
2079                  * save the merging progress in the drop_progress.
2080                  * this is OK since root refs == 1 in this case.
2081                  */
2082                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2083                                path->slots[level]);
2084                 root_item->drop_level = level;
2085
2086                 nr = trans->blocks_used;
2087                 btrfs_end_transaction_throttle(trans, root);
2088
2089                 btrfs_btree_balance_dirty(root, nr);
2090
2091                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2092                         invalidate_extent_cache(root, &key, &next_key);
2093         }
2094
2095         /*
2096          * handle the case only one block in the fs tree need to be
2097          * relocated and the block is tree root.
2098          */
2099         leaf = btrfs_lock_root_node(root);
2100         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2101         btrfs_tree_unlock(leaf);
2102         free_extent_buffer(leaf);
2103         if (ret < 0)
2104                 err = ret;
2105 out:
2106         btrfs_free_path(path);
2107
2108         if (err == 0) {
2109                 memset(&root_item->drop_progress, 0,
2110                        sizeof(root_item->drop_progress));
2111                 root_item->drop_level = 0;
2112                 btrfs_set_root_refs(root_item, 0);
2113                 btrfs_update_reloc_root(trans, root);
2114         }
2115
2116         nr = trans->blocks_used;
2117         btrfs_end_transaction_throttle(trans, root);
2118
2119         btrfs_btree_balance_dirty(root, nr);
2120
2121         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2122                 invalidate_extent_cache(root, &key, &next_key);
2123
2124         return err;
2125 }
2126
2127 static noinline_for_stack
2128 int prepare_to_merge(struct reloc_control *rc, int err)
2129 {
2130         struct btrfs_root *root = rc->extent_root;
2131         struct btrfs_root *reloc_root;
2132         struct btrfs_trans_handle *trans;
2133         LIST_HEAD(reloc_roots);
2134         u64 num_bytes = 0;
2135         int ret;
2136         int retries = 0;
2137
2138         mutex_lock(&root->fs_info->trans_mutex);
2139         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2140         rc->merging_rsv_size += rc->nodes_relocated * 2;
2141         mutex_unlock(&root->fs_info->trans_mutex);
2142 again:
2143         if (!err) {
2144                 num_bytes = rc->merging_rsv_size;
2145                 ret = btrfs_block_rsv_add(NULL, root, rc->block_rsv,
2146                                           num_bytes, &retries);
2147                 if (ret)
2148                         err = ret;
2149         }
2150
2151         trans = btrfs_join_transaction(rc->extent_root, 1);
2152
2153         if (!err) {
2154                 if (num_bytes != rc->merging_rsv_size) {
2155                         btrfs_end_transaction(trans, rc->extent_root);
2156                         btrfs_block_rsv_release(rc->extent_root,
2157                                                 rc->block_rsv, num_bytes);
2158                         retries = 0;
2159                         goto again;
2160                 }
2161         }
2162
2163         rc->merge_reloc_tree = 1;
2164
2165         while (!list_empty(&rc->reloc_roots)) {
2166                 reloc_root = list_entry(rc->reloc_roots.next,
2167                                         struct btrfs_root, root_list);
2168                 list_del_init(&reloc_root->root_list);
2169
2170                 root = read_fs_root(reloc_root->fs_info,
2171                                     reloc_root->root_key.offset);
2172                 BUG_ON(IS_ERR(root));
2173                 BUG_ON(root->reloc_root != reloc_root);
2174
2175                 /*
2176                  * set reference count to 1, so btrfs_recover_relocation
2177                  * knows it should resumes merging
2178                  */
2179                 if (!err)
2180                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2181                 btrfs_update_reloc_root(trans, root);
2182
2183                 list_add(&reloc_root->root_list, &reloc_roots);
2184         }
2185
2186         list_splice(&reloc_roots, &rc->reloc_roots);
2187
2188         if (!err)
2189                 btrfs_commit_transaction(trans, rc->extent_root);
2190         else
2191                 btrfs_end_transaction(trans, rc->extent_root);
2192         return err;
2193 }
2194
2195 static noinline_for_stack
2196 int merge_reloc_roots(struct reloc_control *rc)
2197 {
2198         struct btrfs_root *root;
2199         struct btrfs_root *reloc_root;
2200         LIST_HEAD(reloc_roots);
2201         int found = 0;
2202         int ret;
2203 again:
2204         root = rc->extent_root;
2205         mutex_lock(&root->fs_info->trans_mutex);
2206         list_splice_init(&rc->reloc_roots, &reloc_roots);
2207         mutex_unlock(&root->fs_info->trans_mutex);
2208
2209         while (!list_empty(&reloc_roots)) {
2210                 found = 1;
2211                 reloc_root = list_entry(reloc_roots.next,
2212                                         struct btrfs_root, root_list);
2213
2214                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2215                         root = read_fs_root(reloc_root->fs_info,
2216                                             reloc_root->root_key.offset);
2217                         BUG_ON(IS_ERR(root));
2218                         BUG_ON(root->reloc_root != reloc_root);
2219
2220                         ret = merge_reloc_root(rc, root);
2221                         BUG_ON(ret);
2222                 } else {
2223                         list_del_init(&reloc_root->root_list);
2224                 }
2225                 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
2226         }
2227
2228         if (found) {
2229                 found = 0;
2230                 goto again;
2231         }
2232         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2233         return 0;
2234 }
2235
2236 static void free_block_list(struct rb_root *blocks)
2237 {
2238         struct tree_block *block;
2239         struct rb_node *rb_node;
2240         while ((rb_node = rb_first(blocks))) {
2241                 block = rb_entry(rb_node, struct tree_block, rb_node);
2242                 rb_erase(rb_node, blocks);
2243                 kfree(block);
2244         }
2245 }
2246
2247 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2248                                       struct btrfs_root *reloc_root)
2249 {
2250         struct btrfs_root *root;
2251
2252         if (reloc_root->last_trans == trans->transid)
2253                 return 0;
2254
2255         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2256         BUG_ON(IS_ERR(root));
2257         BUG_ON(root->reloc_root != reloc_root);
2258
2259         return btrfs_record_root_in_trans(trans, root);
2260 }
2261
2262 static noinline_for_stack
2263 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2264                                      struct reloc_control *rc,
2265                                      struct backref_node *node,
2266                                      struct backref_edge *edges[], int *nr)
2267 {
2268         struct backref_node *next;
2269         struct btrfs_root *root;
2270         int index = 0;
2271
2272         next = node;
2273         while (1) {
2274                 cond_resched();
2275                 next = walk_up_backref(next, edges, &index);
2276                 root = next->root;
2277                 BUG_ON(!root);
2278                 BUG_ON(!root->ref_cows);
2279
2280                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2281                         record_reloc_root_in_trans(trans, root);
2282                         break;
2283                 }
2284
2285                 btrfs_record_root_in_trans(trans, root);
2286                 root = root->reloc_root;
2287
2288                 if (next->new_bytenr != root->node->start) {
2289                         BUG_ON(next->new_bytenr);
2290                         BUG_ON(!list_empty(&next->list));
2291                         next->new_bytenr = root->node->start;
2292                         next->root = root;
2293                         list_add_tail(&next->list,
2294                                       &rc->backref_cache.changed);
2295                         __mark_block_processed(rc, next);
2296                         break;
2297                 }
2298
2299                 WARN_ON(1);
2300                 root = NULL;
2301                 next = walk_down_backref(edges, &index);
2302                 if (!next || next->level <= node->level)
2303                         break;
2304         }
2305         if (!root)
2306                 return NULL;
2307
2308         *nr = index;
2309         next = node;
2310         /* setup backref node path for btrfs_reloc_cow_block */
2311         while (1) {
2312                 rc->backref_cache.path[next->level] = next;
2313                 if (--index < 0)
2314                         break;
2315                 next = edges[index]->node[UPPER];
2316         }
2317         return root;
2318 }
2319
2320 /*
2321  * select a tree root for relocation. return NULL if the block
2322  * is reference counted. we should use do_relocation() in this
2323  * case. return a tree root pointer if the block isn't reference
2324  * counted. return -ENOENT if the block is root of reloc tree.
2325  */
2326 static noinline_for_stack
2327 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2328                                    struct backref_node *node)
2329 {
2330         struct backref_node *next;
2331         struct btrfs_root *root;
2332         struct btrfs_root *fs_root = NULL;
2333         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2334         int index = 0;
2335
2336         next = node;
2337         while (1) {
2338                 cond_resched();
2339                 next = walk_up_backref(next, edges, &index);
2340                 root = next->root;
2341                 BUG_ON(!root);
2342
2343                 /* no other choice for non-refernce counted tree */
2344                 if (!root->ref_cows)
2345                         return root;
2346
2347                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2348                         fs_root = root;
2349
2350                 if (next != node)
2351                         return NULL;
2352
2353                 next = walk_down_backref(edges, &index);
2354                 if (!next || next->level <= node->level)
2355                         break;
2356         }
2357
2358         if (!fs_root)
2359                 return ERR_PTR(-ENOENT);
2360         return fs_root;
2361 }
2362
2363 static noinline_for_stack
2364 u64 calcu_metadata_size(struct reloc_control *rc,
2365                         struct backref_node *node, int reserve)
2366 {
2367         struct backref_node *next = node;
2368         struct backref_edge *edge;
2369         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2370         u64 num_bytes = 0;
2371         int index = 0;
2372
2373         BUG_ON(reserve && node->processed);
2374
2375         while (next) {
2376                 cond_resched();
2377                 while (1) {
2378                         if (next->processed && (reserve || next != node))
2379                                 break;
2380
2381                         num_bytes += btrfs_level_size(rc->extent_root,
2382                                                       next->level);
2383
2384                         if (list_empty(&next->upper))
2385                                 break;
2386
2387                         edge = list_entry(next->upper.next,
2388                                           struct backref_edge, list[LOWER]);
2389                         edges[index++] = edge;
2390                         next = edge->node[UPPER];
2391                 }
2392                 next = walk_down_backref(edges, &index);
2393         }
2394         return num_bytes;
2395 }
2396
2397 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2398                                   struct reloc_control *rc,
2399                                   struct backref_node *node)
2400 {
2401         struct btrfs_root *root = rc->extent_root;
2402         u64 num_bytes;
2403         int ret;
2404
2405         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2406
2407         trans->block_rsv = rc->block_rsv;
2408         ret = btrfs_block_rsv_add(trans, root, rc->block_rsv, num_bytes,
2409                                   &rc->block_rsv_retries);
2410         if (ret) {
2411                 if (ret == -EAGAIN)
2412                         rc->commit_transaction = 1;
2413                 return ret;
2414         }
2415
2416         rc->block_rsv_retries = 0;
2417         return 0;
2418 }
2419
2420 static void release_metadata_space(struct reloc_control *rc,
2421                                    struct backref_node *node)
2422 {
2423         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2424         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2425 }
2426
2427 /*
2428  * relocate a block tree, and then update pointers in upper level
2429  * blocks that reference the block to point to the new location.
2430  *
2431  * if called by link_to_upper, the block has already been relocated.
2432  * in that case this function just updates pointers.
2433  */
2434 static int do_relocation(struct btrfs_trans_handle *trans,
2435                          struct reloc_control *rc,
2436                          struct backref_node *node,
2437                          struct btrfs_key *key,
2438                          struct btrfs_path *path, int lowest)
2439 {
2440         struct backref_node *upper;
2441         struct backref_edge *edge;
2442         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2443         struct btrfs_root *root;
2444         struct extent_buffer *eb;
2445         u32 blocksize;
2446         u64 bytenr;
2447         u64 generation;
2448         int nr;
2449         int slot;
2450         int ret;
2451         int err = 0;
2452
2453         BUG_ON(lowest && node->eb);
2454
2455         path->lowest_level = node->level + 1;
2456         rc->backref_cache.path[node->level] = node;
2457         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2458                 cond_resched();
2459
2460                 upper = edge->node[UPPER];
2461                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2462                 BUG_ON(!root);
2463
2464                 if (upper->eb && !upper->locked) {
2465                         if (!lowest) {
2466                                 ret = btrfs_bin_search(upper->eb, key,
2467                                                        upper->level, &slot);
2468                                 BUG_ON(ret);
2469                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2470                                 if (node->eb->start == bytenr)
2471                                         goto next;
2472                         }
2473                         drop_node_buffer(upper);
2474                 }
2475
2476                 if (!upper->eb) {
2477                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2478                         if (ret < 0) {
2479                                 err = ret;
2480                                 break;
2481                         }
2482                         BUG_ON(ret > 0);
2483
2484                         if (!upper->eb) {
2485                                 upper->eb = path->nodes[upper->level];
2486                                 path->nodes[upper->level] = NULL;
2487                         } else {
2488                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2489                         }
2490
2491                         upper->locked = 1;
2492                         path->locks[upper->level] = 0;
2493
2494                         slot = path->slots[upper->level];
2495                         btrfs_release_path(NULL, path);
2496                 } else {
2497                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2498                                                &slot);
2499                         BUG_ON(ret);
2500                 }
2501
2502                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2503                 if (lowest) {
2504                         BUG_ON(bytenr != node->bytenr);
2505                 } else {
2506                         if (node->eb->start == bytenr)
2507                                 goto next;
2508                 }
2509
2510                 blocksize = btrfs_level_size(root, node->level);
2511                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2512                 eb = read_tree_block(root, bytenr, blocksize, generation);
2513                 btrfs_tree_lock(eb);
2514                 btrfs_set_lock_blocking(eb);
2515
2516                 if (!node->eb) {
2517                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2518                                               slot, &eb);
2519                         btrfs_tree_unlock(eb);
2520                         free_extent_buffer(eb);
2521                         if (ret < 0) {
2522                                 err = ret;
2523                                 goto next;
2524                         }
2525                         BUG_ON(node->eb != eb);
2526                 } else {
2527                         btrfs_set_node_blockptr(upper->eb, slot,
2528                                                 node->eb->start);
2529                         btrfs_set_node_ptr_generation(upper->eb, slot,
2530                                                       trans->transid);
2531                         btrfs_mark_buffer_dirty(upper->eb);
2532
2533                         ret = btrfs_inc_extent_ref(trans, root,
2534                                                 node->eb->start, blocksize,
2535                                                 upper->eb->start,
2536                                                 btrfs_header_owner(upper->eb),
2537                                                 node->level, 0);
2538                         BUG_ON(ret);
2539
2540                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2541                         BUG_ON(ret);
2542                 }
2543 next:
2544                 if (!upper->pending)
2545                         drop_node_buffer(upper);
2546                 else
2547                         unlock_node_buffer(upper);
2548                 if (err)
2549                         break;
2550         }
2551
2552         if (!err && node->pending) {
2553                 drop_node_buffer(node);
2554                 list_move_tail(&node->list, &rc->backref_cache.changed);
2555                 node->pending = 0;
2556         }
2557
2558         path->lowest_level = 0;
2559         BUG_ON(err == -ENOSPC);
2560         return err;
2561 }
2562
2563 static int link_to_upper(struct btrfs_trans_handle *trans,
2564                          struct reloc_control *rc,
2565                          struct backref_node *node,
2566                          struct btrfs_path *path)
2567 {
2568         struct btrfs_key key;
2569
2570         btrfs_node_key_to_cpu(node->eb, &key, 0);
2571         return do_relocation(trans, rc, node, &key, path, 0);
2572 }
2573
2574 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2575                                 struct reloc_control *rc,
2576                                 struct btrfs_path *path, int err)
2577 {
2578         LIST_HEAD(list);
2579         struct backref_cache *cache = &rc->backref_cache;
2580         struct backref_node *node;
2581         int level;
2582         int ret;
2583
2584         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2585                 while (!list_empty(&cache->pending[level])) {
2586                         node = list_entry(cache->pending[level].next,
2587                                           struct backref_node, list);
2588                         list_move_tail(&node->list, &list);
2589                         BUG_ON(!node->pending);
2590
2591                         if (!err) {
2592                                 ret = link_to_upper(trans, rc, node, path);
2593                                 if (ret < 0)
2594                                         err = ret;
2595                         }
2596                 }
2597                 list_splice_init(&list, &cache->pending[level]);
2598         }
2599         return err;
2600 }
2601
2602 static void mark_block_processed(struct reloc_control *rc,
2603                                  u64 bytenr, u32 blocksize)
2604 {
2605         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2606                         EXTENT_DIRTY, GFP_NOFS);
2607 }
2608
2609 static void __mark_block_processed(struct reloc_control *rc,
2610                                    struct backref_node *node)
2611 {
2612         u32 blocksize;
2613         if (node->level == 0 ||
2614             in_block_group(node->bytenr, rc->block_group)) {
2615                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2616                 mark_block_processed(rc, node->bytenr, blocksize);
2617         }
2618         node->processed = 1;
2619 }
2620
2621 /*
2622  * mark a block and all blocks directly/indirectly reference the block
2623  * as processed.
2624  */
2625 static void update_processed_blocks(struct reloc_control *rc,
2626                                     struct backref_node *node)
2627 {
2628         struct backref_node *next = node;
2629         struct backref_edge *edge;
2630         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2631         int index = 0;
2632
2633         while (next) {
2634                 cond_resched();
2635                 while (1) {
2636                         if (next->processed)
2637                                 break;
2638
2639                         __mark_block_processed(rc, next);
2640
2641                         if (list_empty(&next->upper))
2642                                 break;
2643
2644                         edge = list_entry(next->upper.next,
2645                                           struct backref_edge, list[LOWER]);
2646                         edges[index++] = edge;
2647                         next = edge->node[UPPER];
2648                 }
2649                 next = walk_down_backref(edges, &index);
2650         }
2651 }
2652
2653 static int tree_block_processed(u64 bytenr, u32 blocksize,
2654                                 struct reloc_control *rc)
2655 {
2656         if (test_range_bit(&rc->processed_blocks, bytenr,
2657                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2658                 return 1;
2659         return 0;
2660 }
2661
2662 static int get_tree_block_key(struct reloc_control *rc,
2663                               struct tree_block *block)
2664 {
2665         struct extent_buffer *eb;
2666
2667         BUG_ON(block->key_ready);
2668         eb = read_tree_block(rc->extent_root, block->bytenr,
2669                              block->key.objectid, block->key.offset);
2670         WARN_ON(btrfs_header_level(eb) != block->level);
2671         if (block->level == 0)
2672                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2673         else
2674                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2675         free_extent_buffer(eb);
2676         block->key_ready = 1;
2677         return 0;
2678 }
2679
2680 static int reada_tree_block(struct reloc_control *rc,
2681                             struct tree_block *block)
2682 {
2683         BUG_ON(block->key_ready);
2684         readahead_tree_block(rc->extent_root, block->bytenr,
2685                              block->key.objectid, block->key.offset);
2686         return 0;
2687 }
2688
2689 /*
2690  * helper function to relocate a tree block
2691  */
2692 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2693                                 struct reloc_control *rc,
2694                                 struct backref_node *node,
2695                                 struct btrfs_key *key,
2696                                 struct btrfs_path *path)
2697 {
2698         struct btrfs_root *root;
2699         int release = 0;
2700         int ret = 0;
2701
2702         if (!node)
2703                 return 0;
2704
2705         BUG_ON(node->processed);
2706         root = select_one_root(trans, node);
2707         if (root == ERR_PTR(-ENOENT)) {
2708                 update_processed_blocks(rc, node);
2709                 goto out;
2710         }
2711
2712         if (!root || root->ref_cows) {
2713                 ret = reserve_metadata_space(trans, rc, node);
2714                 if (ret)
2715                         goto out;
2716                 release = 1;
2717         }
2718
2719         if (root) {
2720                 if (root->ref_cows) {
2721                         BUG_ON(node->new_bytenr);
2722                         BUG_ON(!list_empty(&node->list));
2723                         btrfs_record_root_in_trans(trans, root);
2724                         root = root->reloc_root;
2725                         node->new_bytenr = root->node->start;
2726                         node->root = root;
2727                         list_add_tail(&node->list, &rc->backref_cache.changed);
2728                 } else {
2729                         path->lowest_level = node->level;
2730                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2731                         btrfs_release_path(root, path);
2732                         if (ret > 0)
2733                                 ret = 0;
2734                 }
2735                 if (!ret)
2736                         update_processed_blocks(rc, node);
2737         } else {
2738                 ret = do_relocation(trans, rc, node, key, path, 1);
2739         }
2740 out:
2741         if (ret || node->level == 0 || node->cowonly) {
2742                 if (release)
2743                         release_metadata_space(rc, node);
2744                 remove_backref_node(&rc->backref_cache, node);
2745         }
2746         return ret;
2747 }
2748
2749 /*
2750  * relocate a list of blocks
2751  */
2752 static noinline_for_stack
2753 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2754                          struct reloc_control *rc, struct rb_root *blocks)
2755 {
2756         struct backref_node *node;
2757         struct btrfs_path *path;
2758         struct tree_block *block;
2759         struct rb_node *rb_node;
2760         int ret;
2761         int err = 0;
2762
2763         path = btrfs_alloc_path();
2764         if (!path)
2765                 return -ENOMEM;
2766
2767         rb_node = rb_first(blocks);
2768         while (rb_node) {
2769                 block = rb_entry(rb_node, struct tree_block, rb_node);
2770                 if (!block->key_ready)
2771                         reada_tree_block(rc, block);
2772                 rb_node = rb_next(rb_node);
2773         }
2774
2775         rb_node = rb_first(blocks);
2776         while (rb_node) {
2777                 block = rb_entry(rb_node, struct tree_block, rb_node);
2778                 if (!block->key_ready)
2779                         get_tree_block_key(rc, block);
2780                 rb_node = rb_next(rb_node);
2781         }
2782
2783         rb_node = rb_first(blocks);
2784         while (rb_node) {
2785                 block = rb_entry(rb_node, struct tree_block, rb_node);
2786
2787                 node = build_backref_tree(rc, &block->key,
2788                                           block->level, block->bytenr);
2789                 if (IS_ERR(node)) {
2790                         err = PTR_ERR(node);
2791                         goto out;
2792                 }
2793
2794                 ret = relocate_tree_block(trans, rc, node, &block->key,
2795                                           path);
2796                 if (ret < 0) {
2797                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2798                                 err = ret;
2799                         goto out;
2800                 }
2801                 rb_node = rb_next(rb_node);
2802         }
2803 out:
2804         free_block_list(blocks);
2805         err = finish_pending_nodes(trans, rc, path, err);
2806
2807         btrfs_free_path(path);
2808         return err;
2809 }
2810
2811 static noinline_for_stack
2812 int prealloc_file_extent_cluster(struct inode *inode,
2813                                  struct file_extent_cluster *cluster)
2814 {
2815         u64 alloc_hint = 0;
2816         u64 start;
2817         u64 end;
2818         u64 offset = BTRFS_I(inode)->index_cnt;
2819         u64 num_bytes;
2820         int nr = 0;
2821         int ret = 0;
2822
2823         BUG_ON(cluster->start != cluster->boundary[0]);
2824         mutex_lock(&inode->i_mutex);
2825
2826         ret = btrfs_check_data_free_space(inode, cluster->end +
2827                                           1 - cluster->start);
2828         if (ret)
2829                 goto out;
2830
2831         while (nr < cluster->nr) {
2832                 start = cluster->boundary[nr] - offset;
2833                 if (nr + 1 < cluster->nr)
2834                         end = cluster->boundary[nr + 1] - 1 - offset;
2835                 else
2836                         end = cluster->end - offset;
2837
2838                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2839                 num_bytes = end + 1 - start;
2840                 ret = btrfs_prealloc_file_range(inode, 0, start,
2841                                                 num_bytes, num_bytes,
2842                                                 end + 1, &alloc_hint);
2843                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2844                 if (ret)
2845                         break;
2846                 nr++;
2847         }
2848         btrfs_free_reserved_data_space(inode, cluster->end +
2849                                        1 - cluster->start);
2850 out:
2851         mutex_unlock(&inode->i_mutex);
2852         return ret;
2853 }
2854
2855 static noinline_for_stack
2856 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2857                          u64 block_start)
2858 {
2859         struct btrfs_root *root = BTRFS_I(inode)->root;
2860         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2861         struct extent_map *em;
2862         int ret = 0;
2863
2864         em = alloc_extent_map(GFP_NOFS);
2865         if (!em)
2866                 return -ENOMEM;
2867
2868         em->start = start;
2869         em->len = end + 1 - start;
2870         em->block_len = em->len;
2871         em->block_start = block_start;
2872         em->bdev = root->fs_info->fs_devices->latest_bdev;
2873         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2874
2875         lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2876         while (1) {
2877                 write_lock(&em_tree->lock);
2878                 ret = add_extent_mapping(em_tree, em);
2879                 write_unlock(&em_tree->lock);
2880                 if (ret != -EEXIST) {
2881                         free_extent_map(em);
2882                         break;
2883                 }
2884                 btrfs_drop_extent_cache(inode, start, end, 0);
2885         }
2886         unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2887         return ret;
2888 }
2889
2890 static int relocate_file_extent_cluster(struct inode *inode,
2891                                         struct file_extent_cluster *cluster)
2892 {
2893         u64 page_start;
2894         u64 page_end;
2895         u64 offset = BTRFS_I(inode)->index_cnt;
2896         unsigned long index;
2897         unsigned long last_index;
2898         struct page *page;
2899         struct file_ra_state *ra;
2900         int nr = 0;
2901         int ret = 0;
2902
2903         if (!cluster->nr)
2904                 return 0;
2905
2906         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2907         if (!ra)
2908                 return -ENOMEM;
2909
2910         ret = prealloc_file_extent_cluster(inode, cluster);
2911         if (ret)
2912                 goto out;
2913
2914         file_ra_state_init(ra, inode->i_mapping);
2915
2916         ret = setup_extent_mapping(inode, cluster->start - offset,
2917                                    cluster->end - offset, cluster->start);
2918         if (ret)
2919                 goto out;
2920
2921         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2922         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2923         while (index <= last_index) {
2924                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2925                 if (ret)
2926                         goto out;
2927
2928                 page = find_lock_page(inode->i_mapping, index);
2929                 if (!page) {
2930                         page_cache_sync_readahead(inode->i_mapping,
2931                                                   ra, NULL, index,
2932                                                   last_index + 1 - index);
2933                         page = grab_cache_page(inode->i_mapping, index);
2934                         if (!page) {
2935                                 btrfs_delalloc_release_metadata(inode,
2936                                                         PAGE_CACHE_SIZE);
2937                                 ret = -ENOMEM;
2938                                 goto out;
2939                         }
2940                 }
2941
2942                 if (PageReadahead(page)) {
2943                         page_cache_async_readahead(inode->i_mapping,
2944                                                    ra, NULL, page, index,
2945                                                    last_index + 1 - index);
2946                 }
2947
2948                 if (!PageUptodate(page)) {
2949                         btrfs_readpage(NULL, page);
2950                         lock_page(page);
2951                         if (!PageUptodate(page)) {
2952                                 unlock_page(page);
2953                                 page_cache_release(page);
2954                                 btrfs_delalloc_release_metadata(inode,
2955                                                         PAGE_CACHE_SIZE);
2956                                 ret = -EIO;
2957                                 goto out;
2958                         }
2959                 }
2960
2961                 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2962                 page_end = page_start + PAGE_CACHE_SIZE - 1;
2963
2964                 lock_extent(&BTRFS_I(inode)->io_tree,
2965                             page_start, page_end, GFP_NOFS);
2966
2967                 set_page_extent_mapped(page);
2968
2969                 if (nr < cluster->nr &&
2970                     page_start + offset == cluster->boundary[nr]) {
2971                         set_extent_bits(&BTRFS_I(inode)->io_tree,
2972                                         page_start, page_end,
2973                                         EXTENT_BOUNDARY, GFP_NOFS);
2974                         nr++;
2975                 }
2976
2977                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
2978                 set_page_dirty(page);
2979
2980                 unlock_extent(&BTRFS_I(inode)->io_tree,
2981                               page_start, page_end, GFP_NOFS);
2982                 unlock_page(page);
2983                 page_cache_release(page);
2984
2985                 index++;
2986                 balance_dirty_pages_ratelimited(inode->i_mapping);
2987                 btrfs_throttle(BTRFS_I(inode)->root);
2988         }
2989         WARN_ON(nr != cluster->nr);
2990 out:
2991         kfree(ra);
2992         return ret;
2993 }
2994
2995 static noinline_for_stack
2996 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
2997                          struct file_extent_cluster *cluster)
2998 {
2999         int ret;
3000
3001         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3002                 ret = relocate_file_extent_cluster(inode, cluster);
3003                 if (ret)
3004                         return ret;
3005                 cluster->nr = 0;
3006         }
3007
3008         if (!cluster->nr)
3009                 cluster->start = extent_key->objectid;
3010         else
3011                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3012         cluster->end = extent_key->objectid + extent_key->offset - 1;
3013         cluster->boundary[cluster->nr] = extent_key->objectid;
3014         cluster->nr++;
3015
3016         if (cluster->nr >= MAX_EXTENTS) {
3017                 ret = relocate_file_extent_cluster(inode, cluster);
3018                 if (ret)
3019                         return ret;
3020                 cluster->nr = 0;
3021         }
3022         return 0;
3023 }
3024
3025 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3026 static int get_ref_objectid_v0(struct reloc_control *rc,
3027                                struct btrfs_path *path,
3028                                struct btrfs_key *extent_key,
3029                                u64 *ref_objectid, int *path_change)
3030 {
3031         struct btrfs_key key;
3032         struct extent_buffer *leaf;
3033         struct btrfs_extent_ref_v0 *ref0;
3034         int ret;
3035         int slot;
3036
3037         leaf = path->nodes[0];
3038         slot = path->slots[0];
3039         while (1) {
3040                 if (slot >= btrfs_header_nritems(leaf)) {
3041                         ret = btrfs_next_leaf(rc->extent_root, path);
3042                         if (ret < 0)
3043                                 return ret;
3044                         BUG_ON(ret > 0);
3045                         leaf = path->nodes[0];
3046                         slot = path->slots[0];
3047                         if (path_change)
3048                                 *path_change = 1;
3049                 }
3050                 btrfs_item_key_to_cpu(leaf, &key, slot);
3051                 if (key.objectid != extent_key->objectid)
3052                         return -ENOENT;
3053
3054                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3055                         slot++;
3056                         continue;
3057                 }
3058                 ref0 = btrfs_item_ptr(leaf, slot,
3059                                 struct btrfs_extent_ref_v0);
3060                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3061                 break;
3062         }
3063         return 0;
3064 }
3065 #endif
3066
3067 /*
3068  * helper to add a tree block to the list.
3069  * the major work is getting the generation and level of the block
3070  */
3071 static int add_tree_block(struct reloc_control *rc,
3072                           struct btrfs_key *extent_key,
3073                           struct btrfs_path *path,
3074                           struct rb_root *blocks)
3075 {
3076         struct extent_buffer *eb;
3077         struct btrfs_extent_item *ei;
3078         struct btrfs_tree_block_info *bi;
3079         struct tree_block *block;
3080         struct rb_node *rb_node;
3081         u32 item_size;
3082         int level = -1;
3083         int generation;
3084
3085         eb =  path->nodes[0];
3086         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3087
3088         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3089                 ei = btrfs_item_ptr(eb, path->slots[0],
3090                                 struct btrfs_extent_item);
3091                 bi = (struct btrfs_tree_block_info *)(ei + 1);
3092                 generation = btrfs_extent_generation(eb, ei);
3093                 level = btrfs_tree_block_level(eb, bi);
3094         } else {
3095 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3096                 u64 ref_owner;
3097                 int ret;
3098
3099                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3100                 ret = get_ref_objectid_v0(rc, path, extent_key,
3101                                           &ref_owner, NULL);
3102                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3103                 level = (int)ref_owner;
3104                 /* FIXME: get real generation */
3105                 generation = 0;
3106 #else
3107                 BUG();
3108 #endif
3109         }
3110
3111         btrfs_release_path(rc->extent_root, path);
3112
3113         BUG_ON(level == -1);
3114
3115         block = kmalloc(sizeof(*block), GFP_NOFS);
3116         if (!block)
3117                 return -ENOMEM;
3118
3119         block->bytenr = extent_key->objectid;
3120         block->key.objectid = extent_key->offset;
3121         block->key.offset = generation;
3122         block->level = level;
3123         block->key_ready = 0;
3124
3125         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3126         BUG_ON(rb_node);
3127
3128         return 0;
3129 }
3130
3131 /*
3132  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3133  */
3134 static int __add_tree_block(struct reloc_control *rc,
3135                             u64 bytenr, u32 blocksize,
3136                             struct rb_root *blocks)
3137 {
3138         struct btrfs_path *path;
3139         struct btrfs_key key;
3140         int ret;
3141
3142         if (tree_block_processed(bytenr, blocksize, rc))
3143                 return 0;
3144
3145         if (tree_search(blocks, bytenr))
3146                 return 0;
3147
3148         path = btrfs_alloc_path();
3149         if (!path)
3150                 return -ENOMEM;
3151
3152         key.objectid = bytenr;
3153         key.type = BTRFS_EXTENT_ITEM_KEY;
3154         key.offset = blocksize;
3155
3156         path->search_commit_root = 1;
3157         path->skip_locking = 1;
3158         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3159         if (ret < 0)
3160                 goto out;
3161         BUG_ON(ret);
3162
3163         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3164         ret = add_tree_block(rc, &key, path, blocks);
3165 out:
3166         btrfs_free_path(path);
3167         return ret;
3168 }
3169
3170 /*
3171  * helper to check if the block use full backrefs for pointers in it
3172  */
3173 static int block_use_full_backref(struct reloc_control *rc,
3174                                   struct extent_buffer *eb)
3175 {
3176         u64 flags;
3177         int ret;
3178
3179         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3180             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3181                 return 1;
3182
3183         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3184                                        eb->start, eb->len, NULL, &flags);
3185         BUG_ON(ret);
3186
3187         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3188                 ret = 1;
3189         else
3190                 ret = 0;
3191         return ret;
3192 }
3193
3194 /*
3195  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3196  * this function scans fs tree to find blocks reference the data extent
3197  */
3198 static int find_data_references(struct reloc_control *rc,
3199                                 struct btrfs_key *extent_key,
3200                                 struct extent_buffer *leaf,
3201                                 struct btrfs_extent_data_ref *ref,
3202                                 struct rb_root *blocks)
3203 {
3204         struct btrfs_path *path;
3205         struct tree_block *block;
3206         struct btrfs_root *root;
3207         struct btrfs_file_extent_item *fi;
3208         struct rb_node *rb_node;
3209         struct btrfs_key key;
3210         u64 ref_root;
3211         u64 ref_objectid;
3212         u64 ref_offset;
3213         u32 ref_count;
3214         u32 nritems;
3215         int err = 0;
3216         int added = 0;
3217         int counted;
3218         int ret;
3219
3220         path = btrfs_alloc_path();
3221         if (!path)
3222                 return -ENOMEM;
3223
3224         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3225         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3226         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3227         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3228
3229         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3230         if (IS_ERR(root)) {
3231                 err = PTR_ERR(root);
3232                 goto out;
3233         }
3234
3235         key.objectid = ref_objectid;
3236         key.offset = ref_offset;
3237         key.type = BTRFS_EXTENT_DATA_KEY;
3238
3239         path->search_commit_root = 1;
3240         path->skip_locking = 1;
3241         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3242         if (ret < 0) {
3243                 err = ret;
3244                 goto out;
3245         }
3246
3247         leaf = path->nodes[0];
3248         nritems = btrfs_header_nritems(leaf);
3249         /*
3250          * the references in tree blocks that use full backrefs
3251          * are not counted in
3252          */
3253         if (block_use_full_backref(rc, leaf))
3254                 counted = 0;
3255         else
3256                 counted = 1;
3257         rb_node = tree_search(blocks, leaf->start);
3258         if (rb_node) {
3259                 if (counted)
3260                         added = 1;
3261                 else
3262                         path->slots[0] = nritems;
3263         }
3264
3265         while (ref_count > 0) {
3266                 while (path->slots[0] >= nritems) {
3267                         ret = btrfs_next_leaf(root, path);
3268                         if (ret < 0) {
3269                                 err = ret;
3270                                 goto out;
3271                         }
3272                         if (ret > 0) {
3273                                 WARN_ON(1);
3274                                 goto out;
3275                         }
3276
3277                         leaf = path->nodes[0];
3278                         nritems = btrfs_header_nritems(leaf);
3279                         added = 0;
3280
3281                         if (block_use_full_backref(rc, leaf))
3282                                 counted = 0;
3283                         else
3284                                 counted = 1;
3285                         rb_node = tree_search(blocks, leaf->start);
3286                         if (rb_node) {
3287                                 if (counted)
3288                                         added = 1;
3289                                 else
3290                                         path->slots[0] = nritems;
3291                         }
3292                 }
3293
3294                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3295                 if (key.objectid != ref_objectid ||
3296                     key.type != BTRFS_EXTENT_DATA_KEY) {
3297                         WARN_ON(1);
3298                         break;
3299                 }
3300
3301                 fi = btrfs_item_ptr(leaf, path->slots[0],
3302                                     struct btrfs_file_extent_item);
3303
3304                 if (btrfs_file_extent_type(leaf, fi) ==
3305                     BTRFS_FILE_EXTENT_INLINE)
3306                         goto next;
3307
3308                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3309                     extent_key->objectid)
3310                         goto next;
3311
3312                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3313                 if (key.offset != ref_offset)
3314                         goto next;
3315
3316                 if (counted)
3317                         ref_count--;
3318                 if (added)
3319                         goto next;
3320
3321                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3322                         block = kmalloc(sizeof(*block), GFP_NOFS);
3323                         if (!block) {
3324                                 err = -ENOMEM;
3325                                 break;
3326                         }
3327                         block->bytenr = leaf->start;
3328                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3329                         block->level = 0;
3330                         block->key_ready = 1;
3331                         rb_node = tree_insert(blocks, block->bytenr,
3332                                               &block->rb_node);
3333                         BUG_ON(rb_node);
3334                 }
3335                 if (counted)
3336                         added = 1;
3337                 else
3338                         path->slots[0] = nritems;
3339 next:
3340                 path->slots[0]++;
3341
3342         }
3343 out:
3344         btrfs_free_path(path);
3345         return err;
3346 }
3347
3348 /*
3349  * hepler to find all tree blocks that reference a given data extent
3350  */
3351 static noinline_for_stack
3352 int add_data_references(struct reloc_control *rc,
3353                         struct btrfs_key *extent_key,
3354                         struct btrfs_path *path,
3355                         struct rb_root *blocks)
3356 {
3357         struct btrfs_key key;
3358         struct extent_buffer *eb;
3359         struct btrfs_extent_data_ref *dref;
3360         struct btrfs_extent_inline_ref *iref;
3361         unsigned long ptr;
3362         unsigned long end;
3363         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3364         int ret;
3365         int err = 0;
3366
3367         eb = path->nodes[0];
3368         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3369         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3370 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3371         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3372                 ptr = end;
3373         else
3374 #endif
3375                 ptr += sizeof(struct btrfs_extent_item);
3376
3377         while (ptr < end) {
3378                 iref = (struct btrfs_extent_inline_ref *)ptr;
3379                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3380                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3381                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3382                         ret = __add_tree_block(rc, key.offset, blocksize,
3383                                                blocks);
3384                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3385                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3386                         ret = find_data_references(rc, extent_key,
3387                                                    eb, dref, blocks);
3388                 } else {
3389                         BUG();
3390                 }
3391                 ptr += btrfs_extent_inline_ref_size(key.type);
3392         }
3393         WARN_ON(ptr > end);
3394
3395         while (1) {
3396                 cond_resched();
3397                 eb = path->nodes[0];
3398                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3399                         ret = btrfs_next_leaf(rc->extent_root, path);
3400                         if (ret < 0) {
3401                                 err = ret;
3402                                 break;
3403                         }
3404                         if (ret > 0)
3405                                 break;
3406                         eb = path->nodes[0];
3407                 }
3408
3409                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3410                 if (key.objectid != extent_key->objectid)
3411                         break;
3412
3413 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3414                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3415                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3416 #else
3417                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3418                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3419 #endif
3420                         ret = __add_tree_block(rc, key.offset, blocksize,
3421                                                blocks);
3422                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3423                         dref = btrfs_item_ptr(eb, path->slots[0],
3424                                               struct btrfs_extent_data_ref);
3425                         ret = find_data_references(rc, extent_key,
3426                                                    eb, dref, blocks);
3427                 } else {
3428                         ret = 0;
3429                 }
3430                 if (ret) {
3431                         err = ret;
3432                         break;
3433                 }
3434                 path->slots[0]++;
3435         }
3436         btrfs_release_path(rc->extent_root, path);
3437         if (err)
3438                 free_block_list(blocks);
3439         return err;
3440 }
3441
3442 /*
3443  * hepler to find next unprocessed extent
3444  */
3445 static noinline_for_stack
3446 int find_next_extent(struct btrfs_trans_handle *trans,
3447                      struct reloc_control *rc, struct btrfs_path *path,
3448                      struct btrfs_key *extent_key)
3449 {
3450         struct btrfs_key key;
3451         struct extent_buffer *leaf;
3452         u64 start, end, last;
3453         int ret;
3454
3455         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3456         while (1) {
3457                 cond_resched();
3458                 if (rc->search_start >= last) {
3459                         ret = 1;
3460                         break;
3461                 }
3462
3463                 key.objectid = rc->search_start;
3464                 key.type = BTRFS_EXTENT_ITEM_KEY;
3465                 key.offset = 0;
3466
3467                 path->search_commit_root = 1;
3468                 path->skip_locking = 1;
3469                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3470                                         0, 0);
3471                 if (ret < 0)
3472                         break;
3473 next:
3474                 leaf = path->nodes[0];
3475                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3476                         ret = btrfs_next_leaf(rc->extent_root, path);
3477                         if (ret != 0)
3478                                 break;
3479                         leaf = path->nodes[0];
3480                 }
3481
3482                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3483                 if (key.objectid >= last) {
3484                         ret = 1;
3485                         break;
3486                 }
3487
3488                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3489                     key.objectid + key.offset <= rc->search_start) {
3490                         path->slots[0]++;
3491                         goto next;
3492                 }
3493
3494                 ret = find_first_extent_bit(&rc->processed_blocks,
3495                                             key.objectid, &start, &end,
3496                                             EXTENT_DIRTY);
3497
3498                 if (ret == 0 && start <= key.objectid) {
3499                         btrfs_release_path(rc->extent_root, path);
3500                         rc->search_start = end + 1;
3501                 } else {
3502                         rc->search_start = key.objectid + key.offset;
3503                         memcpy(extent_key, &key, sizeof(key));
3504                         return 0;
3505                 }
3506         }
3507         btrfs_release_path(rc->extent_root, path);
3508         return ret;
3509 }
3510
3511 static void set_reloc_control(struct reloc_control *rc)
3512 {
3513         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3514         mutex_lock(&fs_info->trans_mutex);
3515         fs_info->reloc_ctl = rc;
3516         mutex_unlock(&fs_info->trans_mutex);
3517 }
3518
3519 static void unset_reloc_control(struct reloc_control *rc)
3520 {
3521         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3522         mutex_lock(&fs_info->trans_mutex);
3523         fs_info->reloc_ctl = NULL;
3524         mutex_unlock(&fs_info->trans_mutex);
3525 }
3526
3527 static int check_extent_flags(u64 flags)
3528 {
3529         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3530             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3531                 return 1;
3532         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3533             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3534                 return 1;
3535         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3536             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3537                 return 1;
3538         return 0;
3539 }
3540
3541 static noinline_for_stack
3542 int prepare_to_relocate(struct reloc_control *rc)
3543 {
3544         struct btrfs_trans_handle *trans;
3545         int ret;
3546
3547         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root);
3548         if (!rc->block_rsv)
3549                 return -ENOMEM;
3550
3551         /*
3552          * reserve some space for creating reloc trees.
3553          * btrfs_init_reloc_root will use them when there
3554          * is no reservation in transaction handle.
3555          */
3556         ret = btrfs_block_rsv_add(NULL, rc->extent_root, rc->block_rsv,
3557                                   rc->extent_root->nodesize * 256,
3558                                   &rc->block_rsv_retries);
3559         if (ret)
3560                 return ret;
3561
3562         rc->block_rsv->refill_used = 1;
3563         btrfs_add_durable_block_rsv(rc->extent_root->fs_info, rc->block_rsv);
3564
3565         memset(&rc->cluster, 0, sizeof(rc->cluster));
3566         rc->search_start = rc->block_group->key.objectid;
3567         rc->extents_found = 0;
3568         rc->nodes_relocated = 0;
3569         rc->merging_rsv_size = 0;
3570         rc->block_rsv_retries = 0;
3571
3572         rc->create_reloc_tree = 1;
3573         set_reloc_control(rc);
3574
3575         trans = btrfs_join_transaction(rc->extent_root, 1);
3576         btrfs_commit_transaction(trans, rc->extent_root);
3577         return 0;
3578 }
3579
3580 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3581 {
3582         struct rb_root blocks = RB_ROOT;
3583         struct btrfs_key key;
3584         struct btrfs_trans_handle *trans = NULL;
3585         struct btrfs_path *path;
3586         struct btrfs_extent_item *ei;
3587         unsigned long nr;
3588         u64 flags;
3589         u32 item_size;
3590         int ret;
3591         int err = 0;
3592
3593         path = btrfs_alloc_path();
3594         if (!path)
3595                 return -ENOMEM;
3596
3597         ret = prepare_to_relocate(rc);
3598         if (ret) {
3599                 err = ret;
3600                 goto out_free;
3601         }
3602
3603         while (1) {
3604                 trans = btrfs_start_transaction(rc->extent_root, 0);
3605
3606                 if (update_backref_cache(trans, &rc->backref_cache)) {
3607                         btrfs_end_transaction(trans, rc->extent_root);
3608                         continue;
3609                 }
3610
3611                 ret = find_next_extent(trans, rc, path, &key);
3612                 if (ret < 0)
3613                         err = ret;
3614                 if (ret != 0)
3615                         break;
3616
3617                 rc->extents_found++;
3618
3619                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3620                                     struct btrfs_extent_item);
3621                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3622                 if (item_size >= sizeof(*ei)) {
3623                         flags = btrfs_extent_flags(path->nodes[0], ei);
3624                         ret = check_extent_flags(flags);
3625                         BUG_ON(ret);
3626
3627                 } else {
3628 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3629                         u64 ref_owner;
3630                         int path_change = 0;
3631
3632                         BUG_ON(item_size !=
3633                                sizeof(struct btrfs_extent_item_v0));
3634                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3635                                                   &path_change);
3636                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3637                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3638                         else
3639                                 flags = BTRFS_EXTENT_FLAG_DATA;
3640
3641                         if (path_change) {
3642                                 btrfs_release_path(rc->extent_root, path);
3643
3644                                 path->search_commit_root = 1;
3645                                 path->skip_locking = 1;
3646                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3647                                                         &key, path, 0, 0);
3648                                 if (ret < 0) {
3649                                         err = ret;
3650                                         break;
3651                                 }
3652                                 BUG_ON(ret > 0);
3653                         }
3654 #else
3655                         BUG();
3656 #endif
3657                 }
3658
3659                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3660                         ret = add_tree_block(rc, &key, path, &blocks);
3661                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3662                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3663                         ret = add_data_references(rc, &key, path, &blocks);
3664                 } else {
3665                         btrfs_release_path(rc->extent_root, path);
3666                         ret = 0;
3667                 }
3668                 if (ret < 0) {
3669                         err = ret;
3670                         break;
3671                 }
3672
3673                 if (!RB_EMPTY_ROOT(&blocks)) {
3674                         ret = relocate_tree_blocks(trans, rc, &blocks);
3675                         if (ret < 0) {
3676                                 if (ret != -EAGAIN) {
3677                                         err = ret;
3678                                         break;
3679                                 }
3680                                 rc->extents_found--;
3681                                 rc->search_start = key.objectid;
3682                         }
3683                 }
3684
3685                 ret = btrfs_block_rsv_check(trans, rc->extent_root,
3686                                             rc->block_rsv, 0, 5);
3687                 if (ret < 0) {
3688                         if (ret != -EAGAIN) {
3689                                 err = ret;
3690                                 WARN_ON(1);
3691                                 break;
3692                         }
3693                         rc->commit_transaction = 1;
3694                 }
3695
3696                 if (rc->commit_transaction) {
3697                         rc->commit_transaction = 0;
3698                         ret = btrfs_commit_transaction(trans, rc->extent_root);
3699                         BUG_ON(ret);
3700                 } else {
3701                         nr = trans->blocks_used;
3702                         btrfs_end_transaction_throttle(trans, rc->extent_root);
3703                         btrfs_btree_balance_dirty(rc->extent_root, nr);
3704                 }
3705                 trans = NULL;
3706
3707                 if (rc->stage == MOVE_DATA_EXTENTS &&
3708                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3709                         rc->found_file_extent = 1;
3710                         ret = relocate_data_extent(rc->data_inode,
3711                                                    &key, &rc->cluster);
3712                         if (ret < 0) {
3713                                 err = ret;
3714                                 break;
3715                         }
3716                 }
3717         }
3718
3719         btrfs_release_path(rc->extent_root, path);
3720         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3721                           GFP_NOFS);
3722
3723         if (trans) {
3724                 nr = trans->blocks_used;
3725                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3726                 btrfs_btree_balance_dirty(rc->extent_root, nr);
3727         }
3728
3729         if (!err) {
3730                 ret = relocate_file_extent_cluster(rc->data_inode,
3731                                                    &rc->cluster);
3732                 if (ret < 0)
3733                         err = ret;
3734         }
3735
3736         rc->create_reloc_tree = 0;
3737         set_reloc_control(rc);
3738
3739         backref_cache_cleanup(&rc->backref_cache);
3740         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3741
3742         err = prepare_to_merge(rc, err);
3743
3744         merge_reloc_roots(rc);
3745
3746         rc->merge_reloc_tree = 0;
3747         unset_reloc_control(rc);
3748         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3749
3750         /* get rid of pinned extents */
3751         trans = btrfs_join_transaction(rc->extent_root, 1);
3752         btrfs_commit_transaction(trans, rc->extent_root);
3753 out_free:
3754         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3755         btrfs_free_path(path);
3756         return err;
3757 }
3758
3759 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3760                                  struct btrfs_root *root, u64 objectid)
3761 {
3762         struct btrfs_path *path;
3763         struct btrfs_inode_item *item;
3764         struct extent_buffer *leaf;
3765         int ret;
3766
3767         path = btrfs_alloc_path();
3768         if (!path)
3769                 return -ENOMEM;
3770
3771         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3772         if (ret)
3773                 goto out;
3774
3775         leaf = path->nodes[0];
3776         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3777         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3778         btrfs_set_inode_generation(leaf, item, 1);
3779         btrfs_set_inode_size(leaf, item, 0);
3780         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3781         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3782                                           BTRFS_INODE_PREALLOC);
3783         btrfs_mark_buffer_dirty(leaf);
3784         btrfs_release_path(root, path);
3785 out:
3786         btrfs_free_path(path);
3787         return ret;
3788 }
3789
3790 /*
3791  * helper to create inode for data relocation.
3792  * the inode is in data relocation tree and its link count is 0
3793  */
3794 static noinline_for_stack
3795 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3796                                  struct btrfs_block_group_cache *group)
3797 {
3798         struct inode *inode = NULL;
3799         struct btrfs_trans_handle *trans;
3800         struct btrfs_root *root;
3801         struct btrfs_key key;
3802         unsigned long nr;
3803         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3804         int err = 0;
3805
3806         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3807         if (IS_ERR(root))
3808                 return ERR_CAST(root);
3809
3810         trans = btrfs_start_transaction(root, 6);
3811         if (IS_ERR(trans))
3812                 return ERR_CAST(trans);
3813
3814         err = btrfs_find_free_objectid(trans, root, objectid, &objectid);
3815         if (err)
3816                 goto out;
3817
3818         err = __insert_orphan_inode(trans, root, objectid);
3819         BUG_ON(err);
3820
3821         key.objectid = objectid;
3822         key.type = BTRFS_INODE_ITEM_KEY;
3823         key.offset = 0;
3824         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3825         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3826         BTRFS_I(inode)->index_cnt = group->key.objectid;
3827
3828         err = btrfs_orphan_add(trans, inode);
3829 out:
3830         nr = trans->blocks_used;
3831         btrfs_end_transaction(trans, root);
3832         btrfs_btree_balance_dirty(root, nr);
3833         if (err) {
3834                 if (inode)
3835                         iput(inode);
3836                 inode = ERR_PTR(err);
3837         }
3838         return inode;
3839 }
3840
3841 static struct reloc_control *alloc_reloc_control(void)
3842 {
3843         struct reloc_control *rc;
3844
3845         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3846         if (!rc)
3847                 return NULL;
3848
3849         INIT_LIST_HEAD(&rc->reloc_roots);
3850         backref_cache_init(&rc->backref_cache);
3851         mapping_tree_init(&rc->reloc_root_tree);
3852         extent_io_tree_init(&rc->processed_blocks, NULL, GFP_NOFS);
3853         return rc;
3854 }
3855
3856 /*
3857  * function to relocate all extents in a block group.
3858  */
3859 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3860 {
3861         struct btrfs_fs_info *fs_info = extent_root->fs_info;
3862         struct reloc_control *rc;
3863         int ret;
3864         int rw = 0;
3865         int err = 0;
3866
3867         rc = alloc_reloc_control();
3868         if (!rc)
3869                 return -ENOMEM;
3870
3871         rc->extent_root = extent_root;
3872
3873         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3874         BUG_ON(!rc->block_group);
3875
3876         if (!rc->block_group->ro) {
3877                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
3878                 if (ret) {
3879                         err = ret;
3880                         goto out;
3881                 }
3882                 rw = 1;
3883         }
3884
3885         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
3886         if (IS_ERR(rc->data_inode)) {
3887                 err = PTR_ERR(rc->data_inode);
3888                 rc->data_inode = NULL;
3889                 goto out;
3890         }
3891
3892         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
3893                (unsigned long long)rc->block_group->key.objectid,
3894                (unsigned long long)rc->block_group->flags);
3895
3896         btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
3897         btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
3898
3899         while (1) {
3900                 mutex_lock(&fs_info->cleaner_mutex);
3901
3902                 btrfs_clean_old_snapshots(fs_info->tree_root);
3903                 ret = relocate_block_group(rc);
3904
3905                 mutex_unlock(&fs_info->cleaner_mutex);
3906                 if (ret < 0) {
3907                         err = ret;
3908                         goto out;
3909                 }
3910
3911                 if (rc->extents_found == 0)
3912                         break;
3913
3914                 printk(KERN_INFO "btrfs: found %llu extents\n",
3915                         (unsigned long long)rc->extents_found);
3916
3917                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
3918                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
3919                         invalidate_mapping_pages(rc->data_inode->i_mapping,
3920                                                  0, -1);
3921                         rc->stage = UPDATE_DATA_PTRS;
3922                 }
3923         }
3924
3925         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
3926                                      rc->block_group->key.objectid,
3927                                      rc->block_group->key.objectid +
3928                                      rc->block_group->key.offset - 1);
3929
3930         WARN_ON(rc->block_group->pinned > 0);
3931         WARN_ON(rc->block_group->reserved > 0);
3932         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
3933 out:
3934         if (err && rw)
3935                 btrfs_set_block_group_rw(extent_root, rc->block_group);
3936         iput(rc->data_inode);
3937         btrfs_put_block_group(rc->block_group);
3938         kfree(rc);
3939         return err;
3940 }
3941
3942 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
3943 {
3944         struct btrfs_trans_handle *trans;
3945         int ret;
3946
3947         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
3948
3949         memset(&root->root_item.drop_progress, 0,
3950                 sizeof(root->root_item.drop_progress));
3951         root->root_item.drop_level = 0;
3952         btrfs_set_root_refs(&root->root_item, 0);
3953         ret = btrfs_update_root(trans, root->fs_info->tree_root,
3954                                 &root->root_key, &root->root_item);
3955         BUG_ON(ret);
3956
3957         ret = btrfs_end_transaction(trans, root->fs_info->tree_root);
3958         BUG_ON(ret);
3959         return 0;
3960 }
3961
3962 /*
3963  * recover relocation interrupted by system crash.
3964  *
3965  * this function resumes merging reloc trees with corresponding fs trees.
3966  * this is important for keeping the sharing of tree blocks
3967  */
3968 int btrfs_recover_relocation(struct btrfs_root *root)
3969 {
3970         LIST_HEAD(reloc_roots);
3971         struct btrfs_key key;
3972         struct btrfs_root *fs_root;
3973         struct btrfs_root *reloc_root;
3974         struct btrfs_path *path;
3975         struct extent_buffer *leaf;
3976         struct reloc_control *rc = NULL;
3977         struct btrfs_trans_handle *trans;
3978         int ret;
3979         int err = 0;
3980
3981         path = btrfs_alloc_path();
3982         if (!path)
3983                 return -ENOMEM;
3984
3985         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
3986         key.type = BTRFS_ROOT_ITEM_KEY;
3987         key.offset = (u64)-1;
3988
3989         while (1) {
3990                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
3991                                         path, 0, 0);
3992                 if (ret < 0) {
3993                         err = ret;
3994                         goto out;
3995                 }
3996                 if (ret > 0) {
3997                         if (path->slots[0] == 0)
3998                                 break;
3999                         path->slots[0]--;
4000                 }
4001                 leaf = path->nodes[0];
4002                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4003                 btrfs_release_path(root->fs_info->tree_root, path);
4004
4005                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4006                     key.type != BTRFS_ROOT_ITEM_KEY)
4007                         break;
4008
4009                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4010                 if (IS_ERR(reloc_root)) {
4011                         err = PTR_ERR(reloc_root);
4012                         goto out;
4013                 }
4014
4015                 list_add(&reloc_root->root_list, &reloc_roots);
4016
4017                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4018                         fs_root = read_fs_root(root->fs_info,
4019                                                reloc_root->root_key.offset);
4020                         if (IS_ERR(fs_root)) {
4021                                 ret = PTR_ERR(fs_root);
4022                                 if (ret != -ENOENT) {
4023                                         err = ret;
4024                                         goto out;
4025                                 }
4026                                 mark_garbage_root(reloc_root);
4027                         }
4028                 }
4029
4030                 if (key.offset == 0)
4031                         break;
4032
4033                 key.offset--;
4034         }
4035         btrfs_release_path(root->fs_info->tree_root, path);
4036
4037         if (list_empty(&reloc_roots))
4038                 goto out;
4039
4040         rc = alloc_reloc_control();
4041         if (!rc) {
4042                 err = -ENOMEM;
4043                 goto out;
4044         }
4045
4046         rc->extent_root = root->fs_info->extent_root;
4047
4048         set_reloc_control(rc);
4049
4050         trans = btrfs_join_transaction(rc->extent_root, 1);
4051
4052         rc->merge_reloc_tree = 1;
4053
4054         while (!list_empty(&reloc_roots)) {
4055                 reloc_root = list_entry(reloc_roots.next,
4056                                         struct btrfs_root, root_list);
4057                 list_del(&reloc_root->root_list);
4058
4059                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4060                         list_add_tail(&reloc_root->root_list,
4061                                       &rc->reloc_roots);
4062                         continue;
4063                 }
4064
4065                 fs_root = read_fs_root(root->fs_info,
4066                                        reloc_root->root_key.offset);
4067                 BUG_ON(IS_ERR(fs_root));
4068
4069                 __add_reloc_root(reloc_root);
4070                 fs_root->reloc_root = reloc_root;
4071         }
4072
4073         btrfs_commit_transaction(trans, rc->extent_root);
4074
4075         merge_reloc_roots(rc);
4076
4077         unset_reloc_control(rc);
4078
4079         trans = btrfs_join_transaction(rc->extent_root, 1);
4080         btrfs_commit_transaction(trans, rc->extent_root);
4081 out:
4082         kfree(rc);
4083         while (!list_empty(&reloc_roots)) {
4084                 reloc_root = list_entry(reloc_roots.next,
4085                                         struct btrfs_root, root_list);
4086                 list_del(&reloc_root->root_list);
4087                 free_extent_buffer(reloc_root->node);
4088                 free_extent_buffer(reloc_root->commit_root);
4089                 kfree(reloc_root);
4090         }
4091         btrfs_free_path(path);
4092
4093         if (err == 0) {
4094                 /* cleanup orphan inode in data relocation tree */
4095                 fs_root = read_fs_root(root->fs_info,
4096                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4097                 if (IS_ERR(fs_root))
4098                         err = PTR_ERR(fs_root);
4099                 else
4100                         btrfs_orphan_cleanup(fs_root);
4101         }
4102         return err;
4103 }
4104
4105 /*
4106  * helper to add ordered checksum for data relocation.
4107  *
4108  * cloning checksum properly handles the nodatasum extents.
4109  * it also saves CPU time to re-calculate the checksum.
4110  */
4111 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4112 {
4113         struct btrfs_ordered_sum *sums;
4114         struct btrfs_sector_sum *sector_sum;
4115         struct btrfs_ordered_extent *ordered;
4116         struct btrfs_root *root = BTRFS_I(inode)->root;
4117         size_t offset;
4118         int ret;
4119         u64 disk_bytenr;
4120         LIST_HEAD(list);
4121
4122         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4123         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4124
4125         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4126         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4127                                        disk_bytenr + len - 1, &list);
4128
4129         while (!list_empty(&list)) {
4130                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4131                 list_del_init(&sums->list);
4132
4133                 sector_sum = sums->sums;
4134                 sums->bytenr = ordered->start;
4135
4136                 offset = 0;
4137                 while (offset < sums->len) {
4138                         sector_sum->bytenr += ordered->start - disk_bytenr;
4139                         sector_sum++;
4140                         offset += root->sectorsize;
4141                 }
4142
4143                 btrfs_add_ordered_sum(inode, ordered, sums);
4144         }
4145         btrfs_put_ordered_extent(ordered);
4146         return 0;
4147 }
4148
4149 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4150                            struct btrfs_root *root, struct extent_buffer *buf,
4151                            struct extent_buffer *cow)
4152 {
4153         struct reloc_control *rc;
4154         struct backref_node *node;
4155         int first_cow = 0;
4156         int level;
4157         int ret;
4158
4159         rc = root->fs_info->reloc_ctl;
4160         if (!rc)
4161                 return;
4162
4163         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4164                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4165
4166         level = btrfs_header_level(buf);
4167         if (btrfs_header_generation(buf) <=
4168             btrfs_root_last_snapshot(&root->root_item))
4169                 first_cow = 1;
4170
4171         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4172             rc->create_reloc_tree) {
4173                 WARN_ON(!first_cow && level == 0);
4174
4175                 node = rc->backref_cache.path[level];
4176                 BUG_ON(node->bytenr != buf->start &&
4177                        node->new_bytenr != buf->start);
4178
4179                 drop_node_buffer(node);
4180                 extent_buffer_get(cow);
4181                 node->eb = cow;
4182                 node->new_bytenr = cow->start;
4183
4184                 if (!node->pending) {
4185                         list_move_tail(&node->list,
4186                                        &rc->backref_cache.pending[level]);
4187                         node->pending = 1;
4188                 }
4189
4190                 if (first_cow)
4191                         __mark_block_processed(rc, node);
4192
4193                 if (first_cow && level > 0)
4194                         rc->nodes_relocated += buf->len;
4195         }
4196
4197         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4198                 ret = replace_file_extents(trans, rc, root, cow);
4199                 BUG_ON(ret);
4200         }
4201 }
4202
4203 /*
4204  * called before creating snapshot. it calculates metadata reservation
4205  * requried for relocating tree blocks in the snapshot
4206  */
4207 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4208                               struct btrfs_pending_snapshot *pending,
4209                               u64 *bytes_to_reserve)
4210 {
4211         struct btrfs_root *root;
4212         struct reloc_control *rc;
4213
4214         root = pending->root;
4215         if (!root->reloc_root)
4216                 return;
4217
4218         rc = root->fs_info->reloc_ctl;
4219         if (!rc->merge_reloc_tree)
4220                 return;
4221
4222         root = root->reloc_root;
4223         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4224         /*
4225          * relocation is in the stage of merging trees. the space
4226          * used by merging a reloc tree is twice the size of
4227          * relocated tree nodes in the worst case. half for cowing
4228          * the reloc tree, half for cowing the fs tree. the space
4229          * used by cowing the reloc tree will be freed after the
4230          * tree is dropped. if we create snapshot, cowing the fs
4231          * tree may use more space than it frees. so we need
4232          * reserve extra space.
4233          */
4234         *bytes_to_reserve += rc->nodes_relocated;
4235 }
4236
4237 /*
4238  * called after snapshot is created. migrate block reservation
4239  * and create reloc root for the newly created snapshot
4240  */
4241 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4242                                struct btrfs_pending_snapshot *pending)
4243 {
4244         struct btrfs_root *root = pending->root;
4245         struct btrfs_root *reloc_root;
4246         struct btrfs_root *new_root;
4247         struct reloc_control *rc;
4248         int ret;
4249
4250         if (!root->reloc_root)
4251                 return;
4252
4253         rc = root->fs_info->reloc_ctl;
4254         rc->merging_rsv_size += rc->nodes_relocated;
4255
4256         if (rc->merge_reloc_tree) {
4257                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4258                                               rc->block_rsv,
4259                                               rc->nodes_relocated);
4260                 BUG_ON(ret);
4261         }
4262
4263         new_root = pending->snap;
4264         reloc_root = create_reloc_root(trans, root->reloc_root,
4265                                        new_root->root_key.objectid);
4266
4267         __add_reloc_root(reloc_root);
4268         new_root->reloc_root = reloc_root;
4269
4270         if (rc->create_reloc_tree) {
4271                 ret = clone_backref_node(trans, rc, root, reloc_root);
4272                 BUG_ON(ret);
4273         }
4274 }