fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97
  98 struct backref_cache {
  99         /* red black tree of all backref nodes in the cache */
 100         struct rb_root rb_root;
 101         /* for passing backref nodes to btrfs_reloc_cow_block */
 102         struct backref_node *path[BTRFS_MAX_LEVEL];
 103         /*
 104          * list of blocks that have been cowed but some block
 105          * pointers in upper level blocks may not reflect the
 106          * new location
 107          */
 108         struct list_head pending[BTRFS_MAX_LEVEL];
 109         /* list of backref nodes with no child node */
 110         struct list_head leaves;
 111         /* list of blocks that have been cowed in current transaction */
 112         struct list_head changed;
 113         /* list of detached backref node. */
 114         struct list_head detached;
 115
 116         u64 last_trans;
 117
 118         int nr_nodes;
 119         int nr_edges;
 120 };
 121
 122 /*
 123  * map address of tree root to tree
 124  */
 125 struct mapping_node {
 126         struct rb_node rb_node;
 127         u64 bytenr;
 128         void *data;
 129 };
 130
 131 struct mapping_tree {
 132         struct rb_root rb_root;
 133         spinlock_t lock;
 134 };
 135
 136 /*
 137  * present a tree block to process
 138  */
 139 struct tree_block {
 140         struct rb_node rb_node;
 141         u64 bytenr;
 142         struct btrfs_key key;
 143         unsigned int level:8;
 144         unsigned int key_ready:1;
 145 };
 146
 147 #define MAX_EXTENTS 128
 148
 149 struct file_extent_cluster {
 150         u64 start;
 151         u64 end;
 152         u64 boundary[MAX_EXTENTS];
 153         unsigned int nr;
 154 };
 155
 156 struct reloc_control {
 157         /* block group to relocate */
 158         struct btrfs_block_group_cache *block_group;
 159         /* extent tree */
 160         struct btrfs_root *extent_root;
 161         /* inode for moving data */
 162         struct inode *data_inode;
 163
 164         struct btrfs_block_rsv *block_rsv;
 165
 166         struct backref_cache backref_cache;
 167
 168         struct file_extent_cluster cluster;
 169         /* tree blocks have been processed */
 170         struct extent_io_tree processed_blocks;
 171         /* map start of tree root to corresponding reloc tree */
 172         struct mapping_tree reloc_root_tree;
 173         /* list of reloc trees */
 174         struct list_head reloc_roots;
 175         /* size of metadata reservation for merging reloc trees */
 176         u64 merging_rsv_size;
 177         /* size of relocated tree nodes */
 178         u64 nodes_relocated;
 179
 180         u64 search_start;
 181         u64 extents_found;
 182
 183         unsigned int stage:8;
 184         unsigned int create_reloc_tree:1;
 185         unsigned int merge_reloc_tree:1;
 186         unsigned int found_file_extent:1;
 187         unsigned int commit_transaction:1;
 188 };
 189
 190 /* stages of data relocation */
 191 #define MOVE_DATA_EXTENTS       0
 192 #define UPDATE_DATA_PTRS        1
 193
 194 static void remove_backref_node(struct backref_cache *cache,
 195                                 struct backref_node *node);
 196 static void __mark_block_processed(struct reloc_control *rc,
 197                                    struct backref_node *node);
 198
 199 static void mapping_tree_init(struct mapping_tree *tree)
 200 {
 201         tree->rb_root = RB_ROOT;
 202         spin_lock_init(&tree->lock);
 203 }
 204
 205 static void backref_cache_init(struct backref_cache *cache)
 206 {
 207         int i;
 208         cache->rb_root = RB_ROOT;
 209         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 210                 INIT_LIST_HEAD(&cache->pending[i]);
 211         INIT_LIST_HEAD(&cache->changed);
 212         INIT_LIST_HEAD(&cache->detached);
 213         INIT_LIST_HEAD(&cache->leaves);
 214 }
 215
 216 static void backref_cache_cleanup(struct backref_cache *cache)
 217 {
 218         struct backref_node *node;
 219         int i;
 220
 221         while (!list_empty(&cache->detached)) {
 222                 node = list_entry(cache->detached.next,
 223                                   struct backref_node, list);
 224                 remove_backref_node(cache, node);
 225         }
 226
 227         while (!list_empty(&cache->leaves)) {
 228                 node = list_entry(cache->leaves.next,
 229                                   struct backref_node, lower);
 230                 remove_backref_node(cache, node);
 231         }
 232
 233         cache->last_trans = 0;
 234
 235         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 236                 BUG_ON(!list_empty(&cache->pending[i]));
 237         BUG_ON(!list_empty(&cache->changed));
 238         BUG_ON(!list_empty(&cache->detached));
 239         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 240         BUG_ON(cache->nr_nodes);
 241         BUG_ON(cache->nr_edges);
 242 }
 243
 244 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 245 {
 246         struct backref_node *node;
 247
 248         node = kzalloc(sizeof(*node), GFP_NOFS);
 249         if (node) {
 250                 INIT_LIST_HEAD(&node->list);
 251                 INIT_LIST_HEAD(&node->upper);
 252                 INIT_LIST_HEAD(&node->lower);
 253                 RB_CLEAR_NODE(&node->rb_node);
 254                 cache->nr_nodes++;
 255         }
 256         return node;
 257 }
 258
 259 static void free_backref_node(struct backref_cache *cache,
 260                               struct backref_node *node)
 261 {
 262         if (node) {
 263                 cache->nr_nodes--;
 264                 kfree(node);
 265         }
 266 }
 267
 268 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 269 {
 270         struct backref_edge *edge;
 271
 272         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 273         if (edge)
 274                 cache->nr_edges++;
 275         return edge;
 276 }
 277
 278 static void free_backref_edge(struct backref_cache *cache,
 279                               struct backref_edge *edge)
 280 {
 281         if (edge) {
 282                 cache->nr_edges--;
 283                 kfree(edge);
 284         }
 285 }
 286
 287 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 288                                    struct rb_node *node)
 289 {
 290         struct rb_node **p = &root->rb_node;
 291         struct rb_node *parent = NULL;
 292         struct tree_entry *entry;
 293
 294         while (*p) {
 295                 parent = *p;
 296                 entry = rb_entry(parent, struct tree_entry, rb_node);
 297
 298                 if (bytenr < entry->bytenr)
 299                         p = &(*p)->rb_left;
 300                 else if (bytenr > entry->bytenr)
 301                         p = &(*p)->rb_right;
 302                 else
 303                         return parent;
 304         }
 305
 306         rb_link_node(node, parent, p);
 307         rb_insert_color(node, root);
 308         return NULL;
 309 }
 310
 311 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 312 {
 313         struct rb_node *n = root->rb_node;
 314         struct tree_entry *entry;
 315
 316         while (n) {
 317                 entry = rb_entry(n, struct tree_entry, rb_node);
 318
 319                 if (bytenr < entry->bytenr)
 320                         n = n->rb_left;
 321                 else if (bytenr > entry->bytenr)
 322                         n = n->rb_right;
 323                 else
 324                         return n;
 325         }
 326         return NULL;
 327 }
 328
 329 /*
 330  * walk up backref nodes until reach node presents tree root
 331  */
 332 static struct backref_node *walk_up_backref(struct backref_node *node,
 333                                             struct backref_edge *edges[],
 334                                             int *index)
 335 {
 336         struct backref_edge *edge;
 337         int idx = *index;
 338
 339         while (!list_empty(&node->upper)) {
 340                 edge = list_entry(node->upper.next,
 341                                   struct backref_edge, list[LOWER]);
 342                 edges[idx++] = edge;
 343                 node = edge->node[UPPER];
 344         }
 345         BUG_ON(node->detached);
 346         *index = idx;
 347         return node;
 348 }
 349
 350 /*
 351  * walk down backref nodes to find start of next reference path
 352  */
 353 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 354                                               int *index)
 355 {
 356         struct backref_edge *edge;
 357         struct backref_node *lower;
 358         int idx = *index;
 359
 360         while (idx > 0) {
 361                 edge = edges[idx - 1];
 362                 lower = edge->node[LOWER];
 363                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 364                         idx--;
 365                         continue;
 366                 }
 367                 edge = list_entry(edge->list[LOWER].next,
 368                                   struct backref_edge, list[LOWER]);
 369                 edges[idx - 1] = edge;
 370                 *index = idx;
 371                 return edge->node[UPPER];
 372         }
 373         *index = 0;
 374         return NULL;
 375 }
 376
 377 static void unlock_node_buffer(struct backref_node *node)
 378 {
 379         if (node->locked) {
 380                 btrfs_tree_unlock(node->eb);
 381                 node->locked = 0;
 382         }
 383 }
 384
 385 static void drop_node_buffer(struct backref_node *node)
 386 {
 387         if (node->eb) {
 388                 unlock_node_buffer(node);
 389                 free_extent_buffer(node->eb);
 390                 node->eb = NULL;
 391         }
 392 }
 393
 394 static void drop_backref_node(struct backref_cache *tree,
 395                               struct backref_node *node)
 396 {
 397         BUG_ON(!list_empty(&node->upper));
 398
 399         drop_node_buffer(node);
 400         list_del(&node->list);
 401         list_del(&node->lower);
 402         if (!RB_EMPTY_NODE(&node->rb_node))
 403                 rb_erase(&node->rb_node, &tree->rb_root);
 404         free_backref_node(tree, node);
 405 }
 406
 407 /*
 408  * remove a backref node from the backref cache
 409  */
 410 static void remove_backref_node(struct backref_cache *cache,
 411                                 struct backref_node *node)
 412 {
 413         struct backref_node *upper;
 414         struct backref_edge *edge;
 415
 416         if (!node)
 417                 return;
 418
 419         BUG_ON(!node->lowest && !node->detached);
 420         while (!list_empty(&node->upper)) {
 421                 edge = list_entry(node->upper.next, struct backref_edge,
 422                                   list[LOWER]);
 423                 upper = edge->node[UPPER];
 424                 list_del(&edge->list[LOWER]);
 425                 list_del(&edge->list[UPPER]);
 426                 free_backref_edge(cache, edge);
 427
 428                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 429                         BUG_ON(!list_empty(&node->upper));
 430                         drop_backref_node(cache, node);
 431                         node = upper;
 432                         node->lowest = 1;
 433                         continue;
 434                 }
 435                 /*
 436                  * add the node to leaf node list if no other
 437                  * child block cached.
 438                  */
 439                 if (list_empty(&upper->lower)) {
 440                         list_add_tail(&upper->lower, &cache->leaves);
 441                         upper->lowest = 1;
 442                 }
 443         }
 444
 445         drop_backref_node(cache, node);
 446 }
 447
 448 static void update_backref_node(struct backref_cache *cache,
 449                                 struct backref_node *node, u64 bytenr)
 450 {
 451         struct rb_node *rb_node;
 452         rb_erase(&node->rb_node, &cache->rb_root);
 453         node->bytenr = bytenr;
 454         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 455         BUG_ON(rb_node);
 456 }
 457
 458 /*
 459  * update backref cache after a transaction commit
 460  */
 461 static int update_backref_cache(struct btrfs_trans_handle *trans,
 462                                 struct backref_cache *cache)
 463 {
 464         struct backref_node *node;
 465         int level = 0;
 466
 467         if (cache->last_trans == 0) {
 468                 cache->last_trans = trans->transid;
 469                 return 0;
 470         }
 471
 472         if (cache->last_trans == trans->transid)
 473                 return 0;
 474
 475         /*
 476          * detached nodes are used to avoid unnecessary backref
 477          * lookup. transaction commit changes the extent tree.
 478          * so the detached nodes are no longer useful.
 479          */
 480         while (!list_empty(&cache->detached)) {
 481                 node = list_entry(cache->detached.next,
 482                                   struct backref_node, list);
 483                 remove_backref_node(cache, node);
 484         }
 485
 486         while (!list_empty(&cache->changed)) {
 487                 node = list_entry(cache->changed.next,
 488                                   struct backref_node, list);
 489                 list_del_init(&node->list);
 490                 BUG_ON(node->pending);
 491                 update_backref_node(cache, node, node->new_bytenr);
 492         }
 493
 494         /*
 495          * some nodes can be left in the pending list if there were
 496          * errors during processing the pending nodes.
 497          */
 498         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 499                 list_for_each_entry(node, &cache->pending[level], list) {
 500                         BUG_ON(!node->pending);
 501                         if (node->bytenr == node->new_bytenr)
 502                                 continue;
 503                         update_backref_node(cache, node, node->new_bytenr);
 504                 }
 505         }
 506
 507         cache->last_trans = 0;
 508         return 1;
 509 }
 510
 511
 512 static int should_ignore_root(struct btrfs_root *root)
 513 {
 514         struct btrfs_root *reloc_root;
 515
 516         if (!root->ref_cows)
 517                 return 0;
 518
 519         reloc_root = root->reloc_root;
 520         if (!reloc_root)
 521                 return 0;
 522
 523         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 524             root->fs_info->running_transaction->transid - 1)
 525                 return 0;
 526         /*
 527          * if there is reloc tree and it was created in previous
 528          * transaction backref lookup can find the reloc tree,
 529          * so backref node for the fs tree root is useless for
 530          * relocation.
 531          */
 532         return 1;
 533 }
 534 /*
 535  * find reloc tree by address of tree root
 536  */
 537 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 538                                           u64 bytenr)
 539 {
 540         struct rb_node *rb_node;
 541         struct mapping_node *node;
 542         struct btrfs_root *root = NULL;
 543
 544         spin_lock(&rc->reloc_root_tree.lock);
 545         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 546         if (rb_node) {
 547                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 548                 root = (struct btrfs_root *)node->data;
 549         }
 550         spin_unlock(&rc->reloc_root_tree.lock);
 551         return root;
 552 }
 553
 554 static int is_cowonly_root(u64 root_objectid)
 555 {
 556         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 557             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 558             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 559             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 560             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 561             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
 562                 return 1;
 563         return 0;
 564 }
 565
 566 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 567                                         u64 root_objectid)
 568 {
 569         struct btrfs_key key;
 570
 571         key.objectid = root_objectid;
 572         key.type = BTRFS_ROOT_ITEM_KEY;
 573         if (is_cowonly_root(root_objectid))
 574                 key.offset = 0;
 575         else
 576                 key.offset = (u64)-1;
 577
 578         return btrfs_read_fs_root_no_name(fs_info, &key);
 579 }
 580
 581 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 582 static noinline_for_stack
 583 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 584                                   struct extent_buffer *leaf,
 585                                   struct btrfs_extent_ref_v0 *ref0)
 586 {
 587         struct btrfs_root *root;
 588         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 589         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 590
 591         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 592
 593         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 594         BUG_ON(IS_ERR(root));
 595
 596         if (root->ref_cows &&
 597             generation != btrfs_root_generation(&root->root_item))
 598                 return NULL;
 599
 600         return root;
 601 }
 602 #endif
 603
 604 static noinline_for_stack
 605 int find_inline_backref(struct extent_buffer *leaf, int slot,
 606                         unsigned long *ptr, unsigned long *end)
 607 {
 608         struct btrfs_extent_item *ei;
 609         struct btrfs_tree_block_info *bi;
 610         u32 item_size;
 611
 612         item_size = btrfs_item_size_nr(leaf, slot);
 613 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 614         if (item_size < sizeof(*ei)) {
 615                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 616                 return 1;
 617         }
 618 #endif
 619         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 620         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 621                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 622
 623         if (item_size <= sizeof(*ei) + sizeof(*bi)) {
 624                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 625                 return 1;
 626         }
 627
 628         bi = (struct btrfs_tree_block_info *)(ei + 1);
 629         *ptr = (unsigned long)(bi + 1);
 630         *end = (unsigned long)ei + item_size;
 631         return 0;
 632 }
 633
 634 /*
 635  * build backref tree for a given tree block. root of the backref tree
 636  * corresponds the tree block, leaves of the backref tree correspond
 637  * roots of b-trees that reference the tree block.
 638  *
 639  * the basic idea of this function is check backrefs of a given block
 640  * to find upper level blocks that refernece the block, and then check
 641  * bakcrefs of these upper level blocks recursively. the recursion stop
 642  * when tree root is reached or backrefs for the block is cached.
 643  *
 644  * NOTE: if we find backrefs for a block are cached, we know backrefs
 645  * for all upper level blocks that directly/indirectly reference the
 646  * block are also cached.
 647  */
 648 static noinline_for_stack
 649 struct backref_node *build_backref_tree(struct reloc_control *rc,
 650                                         struct btrfs_key *node_key,
 651                                         int level, u64 bytenr)
 652 {
 653         struct backref_cache *cache = &rc->backref_cache;
 654         struct btrfs_path *path1;
 655         struct btrfs_path *path2;
 656         struct extent_buffer *eb;
 657         struct btrfs_root *root;
 658         struct backref_node *cur;
 659         struct backref_node *upper;
 660         struct backref_node *lower;
 661         struct backref_node *node = NULL;
 662         struct backref_node *exist = NULL;
 663         struct backref_edge *edge;
 664         struct rb_node *rb_node;
 665         struct btrfs_key key;
 666         unsigned long end;
 667         unsigned long ptr;
 668         LIST_HEAD(list);
 669         LIST_HEAD(useless);
 670         int cowonly;
 671         int ret;
 672         int err = 0;
 673
 674         path1 = btrfs_alloc_path();
 675         path2 = btrfs_alloc_path();
 676         if (!path1 || !path2) {
 677                 err = -ENOMEM;
 678                 goto out;
 679         }
 680         path1->reada = 1;
 681         path2->reada = 2;
 682
 683         node = alloc_backref_node(cache);
 684         if (!node) {
 685                 err = -ENOMEM;
 686                 goto out;
 687         }
 688
 689         node->bytenr = bytenr;
 690         node->level = level;
 691         node->lowest = 1;
 692         cur = node;
 693 again:
 694         end = 0;
 695         ptr = 0;
 696         key.objectid = cur->bytenr;
 697         key.type = BTRFS_EXTENT_ITEM_KEY;
 698         key.offset = (u64)-1;
 699
 700         path1->search_commit_root = 1;
 701         path1->skip_locking = 1;
 702         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 703                                 0, 0);
 704         if (ret < 0) {
 705                 err = ret;
 706                 goto out;
 707         }
 708         BUG_ON(!ret || !path1->slots[0]);
 709
 710         path1->slots[0]--;
 711
 712         WARN_ON(cur->checked);
 713         if (!list_empty(&cur->upper)) {
 714                 /*
 715                  * the backref was added previously when processing
 716                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 717                  */
 718                 BUG_ON(!list_is_singular(&cur->upper));
 719                 edge = list_entry(cur->upper.next, struct backref_edge,
 720                                   list[LOWER]);
 721                 BUG_ON(!list_empty(&edge->list[UPPER]));
 722                 exist = edge->node[UPPER];
 723                 /*
 724                  * add the upper level block to pending list if we need
 725                  * check its backrefs
 726                  */
 727                 if (!exist->checked)
 728                         list_add_tail(&edge->list[UPPER], &list);
 729         } else {
 730                 exist = NULL;
 731         }
 732
 733         while (1) {
 734                 cond_resched();
 735                 eb = path1->nodes[0];
 736
 737                 if (ptr >= end) {
 738                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 739                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 740                                 if (ret < 0) {
 741                                         err = ret;
 742                                         goto out;
 743                                 }
 744                                 if (ret > 0)
 745                                         break;
 746                                 eb = path1->nodes[0];
 747                         }
 748
 749                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 750                         if (key.objectid != cur->bytenr) {
 751                                 WARN_ON(exist);
 752                                 break;
 753                         }
 754
 755                         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 756                                 ret = find_inline_backref(eb, path1->slots[0],
 757                                                           &ptr, &end);
 758                                 if (ret)
 759                                         goto next;
 760                         }
 761                 }
 762
 763                 if (ptr < end) {
 764                         /* update key for inline back ref */
 765                         struct btrfs_extent_inline_ref *iref;
 766                         iref = (struct btrfs_extent_inline_ref *)ptr;
 767                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 768                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 769                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 770                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 771                 }
 772
 773                 if (exist &&
 774                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 775                       exist->owner == key.offset) ||
 776                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 777                       exist->bytenr == key.offset))) {
 778                         exist = NULL;
 779                         goto next;
 780                 }
 781
 782 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 783                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 784                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 785                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 786                                 struct btrfs_extent_ref_v0 *ref0;
 787                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 788                                                 struct btrfs_extent_ref_v0);
 789                                 if (key.objectid == key.offset) {
 790                                         root = find_tree_root(rc, eb, ref0);
 791                                         if (root && !should_ignore_root(root))
 792                                                 cur->root = root;
 793                                         else
 794                                                 list_add(&cur->list, &useless);
 795                                         break;
 796                                 }
 797                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 798                                                                       ref0)))
 799                                         cur->cowonly = 1;
 800                         }
 801 #else
 802                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 803                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 804 #endif
 805                         if (key.objectid == key.offset) {
 806                                 /*
 807                                  * only root blocks of reloc trees use
 808                                  * backref of this type.
 809                                  */
 810                                 root = find_reloc_root(rc, cur->bytenr);
 811                                 BUG_ON(!root);
 812                                 cur->root = root;
 813                                 break;
 814                         }
 815
 816                         edge = alloc_backref_edge(cache);
 817                         if (!edge) {
 818                                 err = -ENOMEM;
 819                                 goto out;
 820                         }
 821                         rb_node = tree_search(&cache->rb_root, key.offset);
 822                         if (!rb_node) {
 823                                 upper = alloc_backref_node(cache);
 824                                 if (!upper) {
 825                                         free_backref_edge(cache, edge);
 826                                         err = -ENOMEM;
 827                                         goto out;
 828                                 }
 829                                 upper->bytenr = key.offset;
 830                                 upper->level = cur->level + 1;
 831                                 /*
 832                                  *  backrefs for the upper level block isn't
 833                                  *  cached, add the block to pending list
 834                                  */
 835                                 list_add_tail(&edge->list[UPPER], &list);
 836                         } else {
 837                                 upper = rb_entry(rb_node, struct backref_node,
 838                                                  rb_node);
 839                                 BUG_ON(!upper->checked);
 840                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 841                         }
 842                         list_add_tail(&edge->list[LOWER], &cur->upper);
 843                         edge->node[LOWER] = cur;
 844                         edge->node[UPPER] = upper;
 845
 846                         goto next;
 847                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 848                         goto next;
 849                 }
 850
 851                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 852                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 853                 if (IS_ERR(root)) {
 854                         err = PTR_ERR(root);
 855                         goto out;
 856                 }
 857
 858                 if (!root->ref_cows)
 859                         cur->cowonly = 1;
 860
 861                 if (btrfs_root_level(&root->root_item) == cur->level) {
 862                         /* tree root */
 863                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 864                                cur->bytenr);
 865                         if (should_ignore_root(root))
 866                                 list_add(&cur->list, &useless);
 867                         else
 868                                 cur->root = root;
 869                         break;
 870                 }
 871
 872                 level = cur->level + 1;
 873
 874                 /*
 875                  * searching the tree to find upper level blocks
 876                  * reference the block.
 877                  */
 878                 path2->search_commit_root = 1;
 879                 path2->skip_locking = 1;
 880                 path2->lowest_level = level;
 881                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 882                 path2->lowest_level = 0;
 883                 if (ret < 0) {
 884                         err = ret;
 885                         goto out;
 886                 }
 887                 if (ret > 0 && path2->slots[level] > 0)
 888                         path2->slots[level]--;
 889
 890                 eb = path2->nodes[level];
 891                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 892                         cur->bytenr);
 893
 894                 lower = cur;
 895                 for (; level < BTRFS_MAX_LEVEL; level++) {
 896                         if (!path2->nodes[level]) {
 897                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 898                                        lower->bytenr);
 899                                 if (should_ignore_root(root))
 900                                         list_add(&lower->list, &useless);
 901                                 else
 902                                         lower->root = root;
 903                                 break;
 904                         }
 905
 906                         edge = alloc_backref_edge(cache);
 907                         if (!edge) {
 908                                 err = -ENOMEM;
 909                                 goto out;
 910                         }
 911
 912                         eb = path2->nodes[level];
 913                         rb_node = tree_search(&cache->rb_root, eb->start);
 914                         if (!rb_node) {
 915                                 upper = alloc_backref_node(cache);
 916                                 if (!upper) {
 917                                         free_backref_edge(cache, edge);
 918                                         err = -ENOMEM;
 919                                         goto out;
 920                                 }
 921                                 upper->bytenr = eb->start;
 922                                 upper->owner = btrfs_header_owner(eb);
 923                                 upper->level = lower->level + 1;
 924                                 if (!root->ref_cows)
 925                                         upper->cowonly = 1;
 926
 927                                 /*
 928                                  * if we know the block isn't shared
 929                                  * we can void checking its backrefs.
 930                                  */
 931                                 if (btrfs_block_can_be_shared(root, eb))
 932                                         upper->checked = 0;
 933                                 else
 934                                         upper->checked = 1;
 935
 936                                 /*
 937                                  * add the block to pending list if we
 938                                  * need check its backrefs. only block
 939                                  * at 'cur->level + 1' is added to the
 940                                  * tail of pending list. this guarantees
 941                                  * we check backrefs from lower level
 942                                  * blocks to upper level blocks.
 943                                  */
 944                                 if (!upper->checked &&
 945                                     level == cur->level + 1) {
 946                                         list_add_tail(&edge->list[UPPER],
 947                                                       &list);
 948                                 } else
 949                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 950                         } else {
 951                                 upper = rb_entry(rb_node, struct backref_node,
 952                                                  rb_node);
 953                                 BUG_ON(!upper->checked);
 954                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 955                                 if (!upper->owner)
 956                                         upper->owner = btrfs_header_owner(eb);
 957                         }
 958                         list_add_tail(&edge->list[LOWER], &lower->upper);
 959                         edge->node[LOWER] = lower;
 960                         edge->node[UPPER] = upper;
 961
 962                         if (rb_node)
 963                                 break;
 964                         lower = upper;
 965                         upper = NULL;
 966                 }
 967                 btrfs_release_path(path2);
 968 next:
 969                 if (ptr < end) {
 970                         ptr += btrfs_extent_inline_ref_size(key.type);
 971                         if (ptr >= end) {
 972                                 WARN_ON(ptr > end);
 973                                 ptr = 0;
 974                                 end = 0;
 975                         }
 976                 }
 977                 if (ptr >= end)
 978                         path1->slots[0]++;
 979         }
 980         btrfs_release_path(path1);
 981
 982         cur->checked = 1;
 983         WARN_ON(exist);
 984
 985         /* the pending list isn't empty, take the first block to process */
 986         if (!list_empty(&list)) {
 987                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 988                 list_del_init(&edge->list[UPPER]);
 989                 cur = edge->node[UPPER];
 990                 goto again;
 991         }
 992
 993         /*
 994          * everything goes well, connect backref nodes and insert backref nodes
 995          * into the cache.
 996          */
 997         BUG_ON(!node->checked);
 998         cowonly = node->cowonly;
 999         if (!cowonly) {
1000                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1001                                       &node->rb_node);
1002                 BUG_ON(rb_node);
1003                 list_add_tail(&node->lower, &cache->leaves);
1004         }
1005
1006         list_for_each_entry(edge, &node->upper, list[LOWER])
1007                 list_add_tail(&edge->list[UPPER], &list);
1008
1009         while (!list_empty(&list)) {
1010                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1011                 list_del_init(&edge->list[UPPER]);
1012                 upper = edge->node[UPPER];
1013                 if (upper->detached) {
1014                         list_del(&edge->list[LOWER]);
1015                         lower = edge->node[LOWER];
1016                         free_backref_edge(cache, edge);
1017                         if (list_empty(&lower->upper))
1018                                 list_add(&lower->list, &useless);
1019                         continue;
1020                 }
1021
1022                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1023                         if (upper->lowest) {
1024                                 list_del_init(&upper->lower);
1025                                 upper->lowest = 0;
1026                         }
1027
1028                         list_add_tail(&edge->list[UPPER], &upper->lower);
1029                         continue;
1030                 }
1031
1032                 BUG_ON(!upper->checked);
1033                 BUG_ON(cowonly != upper->cowonly);
1034                 if (!cowonly) {
1035                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1036                                               &upper->rb_node);
1037                         BUG_ON(rb_node);
1038                 }
1039
1040                 list_add_tail(&edge->list[UPPER], &upper->lower);
1041
1042                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1043                         list_add_tail(&edge->list[UPPER], &list);
1044         }
1045         /*
1046          * process useless backref nodes. backref nodes for tree leaves
1047          * are deleted from the cache. backref nodes for upper level
1048          * tree blocks are left in the cache to avoid unnecessary backref
1049          * lookup.
1050          */
1051         while (!list_empty(&useless)) {
1052                 upper = list_entry(useless.next, struct backref_node, list);
1053                 list_del_init(&upper->list);
1054                 BUG_ON(!list_empty(&upper->upper));
1055                 if (upper == node)
1056                         node = NULL;
1057                 if (upper->lowest) {
1058                         list_del_init(&upper->lower);
1059                         upper->lowest = 0;
1060                 }
1061                 while (!list_empty(&upper->lower)) {
1062                         edge = list_entry(upper->lower.next,
1063                                           struct backref_edge, list[UPPER]);
1064                         list_del(&edge->list[UPPER]);
1065                         list_del(&edge->list[LOWER]);
1066                         lower = edge->node[LOWER];
1067                         free_backref_edge(cache, edge);
1068
1069                         if (list_empty(&lower->upper))
1070                                 list_add(&lower->list, &useless);
1071                 }
1072                 __mark_block_processed(rc, upper);
1073                 if (upper->level > 0) {
1074                         list_add(&upper->list, &cache->detached);
1075                         upper->detached = 1;
1076                 } else {
1077                         rb_erase(&upper->rb_node, &cache->rb_root);
1078                         free_backref_node(cache, upper);
1079                 }
1080         }
1081 out:
1082         btrfs_free_path(path1);
1083         btrfs_free_path(path2);
1084         if (err) {
1085                 while (!list_empty(&useless)) {
1086                         lower = list_entry(useless.next,
1087                                            struct backref_node, upper);
1088                         list_del_init(&lower->upper);
1089                 }
1090                 upper = node;
1091                 INIT_LIST_HEAD(&list);
1092                 while (upper) {
1093                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1094                                 list_splice_tail(&upper->upper, &list);
1095                                 free_backref_node(cache, upper);
1096                         }
1097
1098                         if (list_empty(&list))
1099                                 break;
1100
1101                         edge = list_entry(list.next, struct backref_edge,
1102                                           list[LOWER]);
1103                         list_del(&edge->list[LOWER]);
1104                         upper = edge->node[UPPER];
1105                         free_backref_edge(cache, edge);
1106                 }
1107                 return ERR_PTR(err);
1108         }
1109         BUG_ON(node && node->detached);
1110         return node;
1111 }
1112
1113 /*
1114  * helper to add backref node for the newly created snapshot.
1115  * the backref node is created by cloning backref node that
1116  * corresponds to root of source tree
1117  */
1118 static int clone_backref_node(struct btrfs_trans_handle *trans,
1119                               struct reloc_control *rc,
1120                               struct btrfs_root *src,
1121                               struct btrfs_root *dest)
1122 {
1123         struct btrfs_root *reloc_root = src->reloc_root;
1124         struct backref_cache *cache = &rc->backref_cache;
1125         struct backref_node *node = NULL;
1126         struct backref_node *new_node;
1127         struct backref_edge *edge;
1128         struct backref_edge *new_edge;
1129         struct rb_node *rb_node;
1130
1131         if (cache->last_trans > 0)
1132                 update_backref_cache(trans, cache);
1133
1134         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1135         if (rb_node) {
1136                 node = rb_entry(rb_node, struct backref_node, rb_node);
1137                 if (node->detached)
1138                         node = NULL;
1139                 else
1140                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1141         }
1142
1143         if (!node) {
1144                 rb_node = tree_search(&cache->rb_root,
1145                                       reloc_root->commit_root->start);
1146                 if (rb_node) {
1147                         node = rb_entry(rb_node, struct backref_node,
1148                                         rb_node);
1149                         BUG_ON(node->detached);
1150                 }
1151         }
1152
1153         if (!node)
1154                 return 0;
1155
1156         new_node = alloc_backref_node(cache);
1157         if (!new_node)
1158                 return -ENOMEM;
1159
1160         new_node->bytenr = dest->node->start;
1161         new_node->level = node->level;
1162         new_node->lowest = node->lowest;
1163         new_node->checked = 1;
1164         new_node->root = dest;
1165
1166         if (!node->lowest) {
1167                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1168                         new_edge = alloc_backref_edge(cache);
1169                         if (!new_edge)
1170                                 goto fail;
1171
1172                         new_edge->node[UPPER] = new_node;
1173                         new_edge->node[LOWER] = edge->node[LOWER];
1174                         list_add_tail(&new_edge->list[UPPER],
1175                                       &new_node->lower);
1176                 }
1177         }
1178
1179         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1180                               &new_node->rb_node);
1181         BUG_ON(rb_node);
1182
1183         if (!new_node->lowest) {
1184                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1185                         list_add_tail(&new_edge->list[LOWER],
1186                                       &new_edge->node[LOWER]->upper);
1187                 }
1188         }
1189         return 0;
1190 fail:
1191         while (!list_empty(&new_node->lower)) {
1192                 new_edge = list_entry(new_node->lower.next,
1193                                       struct backref_edge, list[UPPER]);
1194                 list_del(&new_edge->list[UPPER]);
1195                 free_backref_edge(cache, new_edge);
1196         }
1197         free_backref_node(cache, new_node);
1198         return -ENOMEM;
1199 }
1200
1201 /*
1202  * helper to add 'address of tree root -> reloc tree' mapping
1203  */
1204 static int __add_reloc_root(struct btrfs_root *root)
1205 {
1206         struct rb_node *rb_node;
1207         struct mapping_node *node;
1208         struct reloc_control *rc = root->fs_info->reloc_ctl;
1209
1210         node = kmalloc(sizeof(*node), GFP_NOFS);
1211         BUG_ON(!node);
1212
1213         node->bytenr = root->node->start;
1214         node->data = root;
1215
1216         spin_lock(&rc->reloc_root_tree.lock);
1217         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1218                               node->bytenr, &node->rb_node);
1219         spin_unlock(&rc->reloc_root_tree.lock);
1220         BUG_ON(rb_node);
1221
1222         list_add_tail(&root->root_list, &rc->reloc_roots);
1223         return 0;
1224 }
1225
1226 /*
1227  * helper to update/delete the 'address of tree root -> reloc tree'
1228  * mapping
1229  */
1230 static int __update_reloc_root(struct btrfs_root *root, int del)
1231 {
1232         struct rb_node *rb_node;
1233         struct mapping_node *node = NULL;
1234         struct reloc_control *rc = root->fs_info->reloc_ctl;
1235
1236         spin_lock(&rc->reloc_root_tree.lock);
1237         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1238                               root->commit_root->start);
1239         if (rb_node) {
1240                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1241                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1242         }
1243         spin_unlock(&rc->reloc_root_tree.lock);
1244
1245         BUG_ON((struct btrfs_root *)node->data != root);
1246
1247         if (!del) {
1248                 spin_lock(&rc->reloc_root_tree.lock);
1249                 node->bytenr = root->node->start;
1250                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1251                                       node->bytenr, &node->rb_node);
1252                 spin_unlock(&rc->reloc_root_tree.lock);
1253                 BUG_ON(rb_node);
1254         } else {
1255                 list_del_init(&root->root_list);
1256                 kfree(node);
1257         }
1258         return 0;
1259 }
1260
1261 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1262                                         struct btrfs_root *root, u64 objectid)
1263 {
1264         struct btrfs_root *reloc_root;
1265         struct extent_buffer *eb;
1266         struct btrfs_root_item *root_item;
1267         struct btrfs_key root_key;
1268         int ret;
1269
1270         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1271         BUG_ON(!root_item);
1272
1273         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1274         root_key.type = BTRFS_ROOT_ITEM_KEY;
1275         root_key.offset = objectid;
1276
1277         if (root->root_key.objectid == objectid) {
1278                 /* called by btrfs_init_reloc_root */
1279                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1280                                       BTRFS_TREE_RELOC_OBJECTID);
1281                 BUG_ON(ret);
1282
1283                 btrfs_set_root_last_snapshot(&root->root_item,
1284                                              trans->transid - 1);
1285         } else {
1286                 /*
1287                  * called by btrfs_reloc_post_snapshot_hook.
1288                  * the source tree is a reloc tree, all tree blocks
1289                  * modified after it was created have RELOC flag
1290                  * set in their headers. so it's OK to not update
1291                  * the 'last_snapshot'.
1292                  */
1293                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1294                                       BTRFS_TREE_RELOC_OBJECTID);
1295                 BUG_ON(ret);
1296         }
1297
1298         memcpy(root_item, &root->root_item, sizeof(*root_item));
1299         btrfs_set_root_bytenr(root_item, eb->start);
1300         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1301         btrfs_set_root_generation(root_item, trans->transid);
1302
1303         if (root->root_key.objectid == objectid) {
1304                 btrfs_set_root_refs(root_item, 0);
1305                 memset(&root_item->drop_progress, 0,
1306                        sizeof(struct btrfs_disk_key));
1307                 root_item->drop_level = 0;
1308         }
1309
1310         btrfs_tree_unlock(eb);
1311         free_extent_buffer(eb);
1312
1313         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1314                                 &root_key, root_item);
1315         BUG_ON(ret);
1316         kfree(root_item);
1317
1318         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1319                                                  &root_key);
1320         BUG_ON(IS_ERR(reloc_root));
1321         reloc_root->last_trans = trans->transid;
1322         return reloc_root;
1323 }
1324
1325 /*
1326  * create reloc tree for a given fs tree. reloc tree is just a
1327  * snapshot of the fs tree with special root objectid.
1328  */
1329 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1330                           struct btrfs_root *root)
1331 {
1332         struct btrfs_root *reloc_root;
1333         struct reloc_control *rc = root->fs_info->reloc_ctl;
1334         int clear_rsv = 0;
1335
1336         if (root->reloc_root) {
1337                 reloc_root = root->reloc_root;
1338                 reloc_root->last_trans = trans->transid;
1339                 return 0;
1340         }
1341
1342         if (!rc || !rc->create_reloc_tree ||
1343             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1344                 return 0;
1345
1346         if (!trans->block_rsv) {
1347                 trans->block_rsv = rc->block_rsv;
1348                 clear_rsv = 1;
1349         }
1350         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1351         if (clear_rsv)
1352                 trans->block_rsv = NULL;
1353
1354         __add_reloc_root(reloc_root);
1355         root->reloc_root = reloc_root;
1356         return 0;
1357 }
1358
1359 /*
1360  * update root item of reloc tree
1361  */
1362 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1363                             struct btrfs_root *root)
1364 {
1365         struct btrfs_root *reloc_root;
1366         struct btrfs_root_item *root_item;
1367         int del = 0;
1368         int ret;
1369
1370         if (!root->reloc_root)
1371                 goto out;
1372
1373         reloc_root = root->reloc_root;
1374         root_item = &reloc_root->root_item;
1375
1376         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1377             btrfs_root_refs(root_item) == 0) {
1378                 root->reloc_root = NULL;
1379                 del = 1;
1380         }
1381
1382         __update_reloc_root(reloc_root, del);
1383
1384         if (reloc_root->commit_root != reloc_root->node) {
1385                 btrfs_set_root_node(root_item, reloc_root->node);
1386                 free_extent_buffer(reloc_root->commit_root);
1387                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1388         }
1389
1390         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1391                                 &reloc_root->root_key, root_item);
1392         BUG_ON(ret);
1393
1394 out:
1395         return 0;
1396 }
1397
1398 /*
1399  * helper to find first cached inode with inode number >= objectid
1400  * in a subvolume
1401  */
1402 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1403 {
1404         struct rb_node *node;
1405         struct rb_node *prev;
1406         struct btrfs_inode *entry;
1407         struct inode *inode;
1408
1409         spin_lock(&root->inode_lock);
1410 again:
1411         node = root->inode_tree.rb_node;
1412         prev = NULL;
1413         while (node) {
1414                 prev = node;
1415                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1416
1417                 if (objectid < btrfs_ino(&entry->vfs_inode))
1418                         node = node->rb_left;
1419                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1420                         node = node->rb_right;
1421                 else
1422                         break;
1423         }
1424         if (!node) {
1425                 while (prev) {
1426                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1427                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1428                                 node = prev;
1429                                 break;
1430                         }
1431                         prev = rb_next(prev);
1432                 }
1433         }
1434         while (node) {
1435                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1436                 inode = igrab(&entry->vfs_inode);
1437                 if (inode) {
1438                         spin_unlock(&root->inode_lock);
1439                         return inode;
1440                 }
1441
1442                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1443                 if (cond_resched_lock(&root->inode_lock))
1444                         goto again;
1445
1446                 node = rb_next(node);
1447         }
1448         spin_unlock(&root->inode_lock);
1449         return NULL;
1450 }
1451
1452 static int in_block_group(u64 bytenr,
1453                           struct btrfs_block_group_cache *block_group)
1454 {
1455         if (bytenr >= block_group->key.objectid &&
1456             bytenr < block_group->key.objectid + block_group->key.offset)
1457                 return 1;
1458         return 0;
1459 }
1460
1461 /*
1462  * get new location of data
1463  */
1464 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1465                             u64 bytenr, u64 num_bytes)
1466 {
1467         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1468         struct btrfs_path *path;
1469         struct btrfs_file_extent_item *fi;
1470         struct extent_buffer *leaf;
1471         int ret;
1472
1473         path = btrfs_alloc_path();
1474         if (!path)
1475                 return -ENOMEM;
1476
1477         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1478         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1479                                        bytenr, 0);
1480         if (ret < 0)
1481                 goto out;
1482         if (ret > 0) {
1483                 ret = -ENOENT;
1484                 goto out;
1485         }
1486
1487         leaf = path->nodes[0];
1488         fi = btrfs_item_ptr(leaf, path->slots[0],
1489                             struct btrfs_file_extent_item);
1490
1491         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1492                btrfs_file_extent_compression(leaf, fi) ||
1493                btrfs_file_extent_encryption(leaf, fi) ||
1494                btrfs_file_extent_other_encoding(leaf, fi));
1495
1496         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1497                 ret = 1;
1498                 goto out;
1499         }
1500
1501         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1502         ret = 0;
1503 out:
1504         btrfs_free_path(path);
1505         return ret;
1506 }
1507
1508 /*
1509  * update file extent items in the tree leaf to point to
1510  * the new locations.
1511  */
1512 static noinline_for_stack
1513 int replace_file_extents(struct btrfs_trans_handle *trans,
1514                          struct reloc_control *rc,
1515                          struct btrfs_root *root,
1516                          struct extent_buffer *leaf)
1517 {
1518         struct btrfs_key key;
1519         struct btrfs_file_extent_item *fi;
1520         struct inode *inode = NULL;
1521         u64 parent;
1522         u64 bytenr;
1523         u64 new_bytenr = 0;
1524         u64 num_bytes;
1525         u64 end;
1526         u32 nritems;
1527         u32 i;
1528         int ret;
1529         int first = 1;
1530         int dirty = 0;
1531
1532         if (rc->stage != UPDATE_DATA_PTRS)
1533                 return 0;
1534
1535         /* reloc trees always use full backref */
1536         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1537                 parent = leaf->start;
1538         else
1539                 parent = 0;
1540
1541         nritems = btrfs_header_nritems(leaf);
1542         for (i = 0; i < nritems; i++) {
1543                 cond_resched();
1544                 btrfs_item_key_to_cpu(leaf, &key, i);
1545                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1546                         continue;
1547                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1548                 if (btrfs_file_extent_type(leaf, fi) ==
1549                     BTRFS_FILE_EXTENT_INLINE)
1550                         continue;
1551                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1552                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1553                 if (bytenr == 0)
1554                         continue;
1555                 if (!in_block_group(bytenr, rc->block_group))
1556                         continue;
1557
1558                 /*
1559                  * if we are modifying block in fs tree, wait for readpage
1560                  * to complete and drop the extent cache
1561                  */
1562                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1563                         if (first) {
1564                                 inode = find_next_inode(root, key.objectid);
1565                                 first = 0;
1566                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1567                                 btrfs_add_delayed_iput(inode);
1568                                 inode = find_next_inode(root, key.objectid);
1569                         }
1570                         if (inode && btrfs_ino(inode) == key.objectid) {
1571                                 end = key.offset +
1572                                       btrfs_file_extent_num_bytes(leaf, fi);
1573                                 WARN_ON(!IS_ALIGNED(key.offset,
1574                                                     root->sectorsize));
1575                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1576                                 end--;
1577                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1578                                                       key.offset, end,
1579                                                       GFP_NOFS);
1580                                 if (!ret)
1581                                         continue;
1582
1583                                 btrfs_drop_extent_cache(inode, key.offset, end,
1584                                                         1);
1585                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1586                                               key.offset, end, GFP_NOFS);
1587                         }
1588                 }
1589
1590                 ret = get_new_location(rc->data_inode, &new_bytenr,
1591                                        bytenr, num_bytes);
1592                 if (ret > 0) {
1593                         WARN_ON(1);
1594                         continue;
1595                 }
1596                 BUG_ON(ret < 0);
1597
1598                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1599                 dirty = 1;
1600
1601                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1602                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1603                                            num_bytes, parent,
1604                                            btrfs_header_owner(leaf),
1605                                            key.objectid, key.offset);
1606                 BUG_ON(ret);
1607
1608                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1609                                         parent, btrfs_header_owner(leaf),
1610                                         key.objectid, key.offset);
1611                 BUG_ON(ret);
1612         }
1613         if (dirty)
1614                 btrfs_mark_buffer_dirty(leaf);
1615         if (inode)
1616                 btrfs_add_delayed_iput(inode);
1617         return 0;
1618 }
1619
1620 static noinline_for_stack
1621 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1622                      struct btrfs_path *path, int level)
1623 {
1624         struct btrfs_disk_key key1;
1625         struct btrfs_disk_key key2;
1626         btrfs_node_key(eb, &key1, slot);
1627         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1628         return memcmp(&key1, &key2, sizeof(key1));
1629 }
1630
1631 /*
1632  * try to replace tree blocks in fs tree with the new blocks
1633  * in reloc tree. tree blocks haven't been modified since the
1634  * reloc tree was create can be replaced.
1635  *
1636  * if a block was replaced, level of the block + 1 is returned.
1637  * if no block got replaced, 0 is returned. if there are other
1638  * errors, a negative error number is returned.
1639  */
1640 static noinline_for_stack
1641 int replace_path(struct btrfs_trans_handle *trans,
1642                  struct btrfs_root *dest, struct btrfs_root *src,
1643                  struct btrfs_path *path, struct btrfs_key *next_key,
1644                  int lowest_level, int max_level)
1645 {
1646         struct extent_buffer *eb;
1647         struct extent_buffer *parent;
1648         struct btrfs_key key;
1649         u64 old_bytenr;
1650         u64 new_bytenr;
1651         u64 old_ptr_gen;
1652         u64 new_ptr_gen;
1653         u64 last_snapshot;
1654         u32 blocksize;
1655         int cow = 0;
1656         int level;
1657         int ret;
1658         int slot;
1659
1660         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1661         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1662
1663         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1664 again:
1665         slot = path->slots[lowest_level];
1666         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1667
1668         eb = btrfs_lock_root_node(dest);
1669         btrfs_set_lock_blocking(eb);
1670         level = btrfs_header_level(eb);
1671
1672         if (level < lowest_level) {
1673                 btrfs_tree_unlock(eb);
1674                 free_extent_buffer(eb);
1675                 return 0;
1676         }
1677
1678         if (cow) {
1679                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1680                 BUG_ON(ret);
1681         }
1682         btrfs_set_lock_blocking(eb);
1683
1684         if (next_key) {
1685                 next_key->objectid = (u64)-1;
1686                 next_key->type = (u8)-1;
1687                 next_key->offset = (u64)-1;
1688         }
1689
1690         parent = eb;
1691         while (1) {
1692                 level = btrfs_header_level(parent);
1693                 BUG_ON(level < lowest_level);
1694
1695                 ret = btrfs_bin_search(parent, &key, level, &slot);
1696                 if (ret && slot > 0)
1697                         slot--;
1698
1699                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1700                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1701
1702                 old_bytenr = btrfs_node_blockptr(parent, slot);
1703                 blocksize = btrfs_level_size(dest, level - 1);
1704                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1705
1706                 if (level <= max_level) {
1707                         eb = path->nodes[level];
1708                         new_bytenr = btrfs_node_blockptr(eb,
1709                                                         path->slots[level]);
1710                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1711                                                         path->slots[level]);
1712                 } else {
1713                         new_bytenr = 0;
1714                         new_ptr_gen = 0;
1715                 }
1716
1717                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1718                         WARN_ON(1);
1719                         ret = level;
1720                         break;
1721                 }
1722
1723                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1724                     memcmp_node_keys(parent, slot, path, level)) {
1725                         if (level <= lowest_level) {
1726                                 ret = 0;
1727                                 break;
1728                         }
1729
1730                         eb = read_tree_block(dest, old_bytenr, blocksize,
1731                                              old_ptr_gen);
1732                         BUG_ON(!eb);
1733                         btrfs_tree_lock(eb);
1734                         if (cow) {
1735                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1736                                                       slot, &eb);
1737                                 BUG_ON(ret);
1738                         }
1739                         btrfs_set_lock_blocking(eb);
1740
1741                         btrfs_tree_unlock(parent);
1742                         free_extent_buffer(parent);
1743
1744                         parent = eb;
1745                         continue;
1746                 }
1747
1748                 if (!cow) {
1749                         btrfs_tree_unlock(parent);
1750                         free_extent_buffer(parent);
1751                         cow = 1;
1752                         goto again;
1753                 }
1754
1755                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1756                                       path->slots[level]);
1757                 btrfs_release_path(path);
1758
1759                 path->lowest_level = level;
1760                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1761                 path->lowest_level = 0;
1762                 BUG_ON(ret);
1763
1764                 /*
1765                  * swap blocks in fs tree and reloc tree.
1766                  */
1767                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1768                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1769                 btrfs_mark_buffer_dirty(parent);
1770
1771                 btrfs_set_node_blockptr(path->nodes[level],
1772                                         path->slots[level], old_bytenr);
1773                 btrfs_set_node_ptr_generation(path->nodes[level],
1774                                               path->slots[level], old_ptr_gen);
1775                 btrfs_mark_buffer_dirty(path->nodes[level]);
1776
1777                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1778                                         path->nodes[level]->start,
1779                                         src->root_key.objectid, level - 1, 0);
1780                 BUG_ON(ret);
1781                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1782                                         0, dest->root_key.objectid, level - 1,
1783                                         0);
1784                 BUG_ON(ret);
1785
1786                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1787                                         path->nodes[level]->start,
1788                                         src->root_key.objectid, level - 1, 0);
1789                 BUG_ON(ret);
1790
1791                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1792                                         0, dest->root_key.objectid, level - 1,
1793                                         0);
1794                 BUG_ON(ret);
1795
1796                 btrfs_unlock_up_safe(path, 0);
1797
1798                 ret = level;
1799                 break;
1800         }
1801         btrfs_tree_unlock(parent);
1802         free_extent_buffer(parent);
1803         return ret;
1804 }
1805
1806 /*
1807  * helper to find next relocated block in reloc tree
1808  */
1809 static noinline_for_stack
1810 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1811                        int *level)
1812 {
1813         struct extent_buffer *eb;
1814         int i;
1815         u64 last_snapshot;
1816         u32 nritems;
1817
1818         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1819
1820         for (i = 0; i < *level; i++) {
1821                 free_extent_buffer(path->nodes[i]);
1822                 path->nodes[i] = NULL;
1823         }
1824
1825         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1826                 eb = path->nodes[i];
1827                 nritems = btrfs_header_nritems(eb);
1828                 while (path->slots[i] + 1 < nritems) {
1829                         path->slots[i]++;
1830                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1831                             last_snapshot)
1832                                 continue;
1833
1834                         *level = i;
1835                         return 0;
1836                 }
1837                 free_extent_buffer(path->nodes[i]);
1838                 path->nodes[i] = NULL;
1839         }
1840         return 1;
1841 }
1842
1843 /*
1844  * walk down reloc tree to find relocated block of lowest level
1845  */
1846 static noinline_for_stack
1847 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1848                          int *level)
1849 {
1850         struct extent_buffer *eb = NULL;
1851         int i;
1852         u64 bytenr;
1853         u64 ptr_gen = 0;
1854         u64 last_snapshot;
1855         u32 blocksize;
1856         u32 nritems;
1857
1858         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1859
1860         for (i = *level; i > 0; i--) {
1861                 eb = path->nodes[i];
1862                 nritems = btrfs_header_nritems(eb);
1863                 while (path->slots[i] < nritems) {
1864                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1865                         if (ptr_gen > last_snapshot)
1866                                 break;
1867                         path->slots[i]++;
1868                 }
1869                 if (path->slots[i] >= nritems) {
1870                         if (i == *level)
1871                                 break;
1872                         *level = i + 1;
1873                         return 0;
1874                 }
1875                 if (i == 1) {
1876                         *level = i;
1877                         return 0;
1878                 }
1879
1880                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1881                 blocksize = btrfs_level_size(root, i - 1);
1882                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1883                 BUG_ON(btrfs_header_level(eb) != i - 1);
1884                 path->nodes[i - 1] = eb;
1885                 path->slots[i - 1] = 0;
1886         }
1887         return 1;
1888 }
1889
1890 /*
1891  * invalidate extent cache for file extents whose key in range of
1892  * [min_key, max_key)
1893  */
1894 static int invalidate_extent_cache(struct btrfs_root *root,
1895                                    struct btrfs_key *min_key,
1896                                    struct btrfs_key *max_key)
1897 {
1898         struct inode *inode = NULL;
1899         u64 objectid;
1900         u64 start, end;
1901         u64 ino;
1902
1903         objectid = min_key->objectid;
1904         while (1) {
1905                 cond_resched();
1906                 iput(inode);
1907
1908                 if (objectid > max_key->objectid)
1909                         break;
1910
1911                 inode = find_next_inode(root, objectid);
1912                 if (!inode)
1913                         break;
1914                 ino = btrfs_ino(inode);
1915
1916                 if (ino > max_key->objectid) {
1917                         iput(inode);
1918                         break;
1919                 }
1920
1921                 objectid = ino + 1;
1922                 if (!S_ISREG(inode->i_mode))
1923                         continue;
1924
1925                 if (unlikely(min_key->objectid == ino)) {
1926                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1927                                 continue;
1928                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1929                                 start = 0;
1930                         else {
1931                                 start = min_key->offset;
1932                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1933                         }
1934                 } else {
1935                         start = 0;
1936                 }
1937
1938                 if (unlikely(max_key->objectid == ino)) {
1939                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1940                                 continue;
1941                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1942                                 end = (u64)-1;
1943                         } else {
1944                                 if (max_key->offset == 0)
1945                                         continue;
1946                                 end = max_key->offset;
1947                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1948                                 end--;
1949                         }
1950                 } else {
1951                         end = (u64)-1;
1952                 }
1953
1954                 /* the lock_extent waits for readpage to complete */
1955                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1956                 btrfs_drop_extent_cache(inode, start, end, 1);
1957                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1958         }
1959         return 0;
1960 }
1961
1962 static int find_next_key(struct btrfs_path *path, int level,
1963                          struct btrfs_key *key)
1964
1965 {
1966         while (level < BTRFS_MAX_LEVEL) {
1967                 if (!path->nodes[level])
1968                         break;
1969                 if (path->slots[level] + 1 <
1970                     btrfs_header_nritems(path->nodes[level])) {
1971                         btrfs_node_key_to_cpu(path->nodes[level], key,
1972                                               path->slots[level] + 1);
1973                         return 0;
1974                 }
1975                 level++;
1976         }
1977         return 1;
1978 }
1979
1980 /*
1981  * merge the relocated tree blocks in reloc tree with corresponding
1982  * fs tree.
1983  */
1984 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1985                                                struct btrfs_root *root)
1986 {
1987         LIST_HEAD(inode_list);
1988         struct btrfs_key key;
1989         struct btrfs_key next_key;
1990         struct btrfs_trans_handle *trans;
1991         struct btrfs_root *reloc_root;
1992         struct btrfs_root_item *root_item;
1993         struct btrfs_path *path;
1994         struct extent_buffer *leaf;
1995         unsigned long nr;
1996         int level;
1997         int max_level;
1998         int replaced = 0;
1999         int ret;
2000         int err = 0;
2001         u32 min_reserved;
2002
2003         path = btrfs_alloc_path();
2004         if (!path)
2005                 return -ENOMEM;
2006         path->reada = 1;
2007
2008         reloc_root = root->reloc_root;
2009         root_item = &reloc_root->root_item;
2010
2011         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2012                 level = btrfs_root_level(root_item);
2013                 extent_buffer_get(reloc_root->node);
2014                 path->nodes[level] = reloc_root->node;
2015                 path->slots[level] = 0;
2016         } else {
2017                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2018
2019                 level = root_item->drop_level;
2020                 BUG_ON(level == 0);
2021                 path->lowest_level = level;
2022                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2023                 path->lowest_level = 0;
2024                 if (ret < 0) {
2025                         btrfs_free_path(path);
2026                         return ret;
2027                 }
2028
2029                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2030                                       path->slots[level]);
2031                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2032
2033                 btrfs_unlock_up_safe(path, 0);
2034         }
2035
2036         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2037         memset(&next_key, 0, sizeof(next_key));
2038
2039         while (1) {
2040                 trans = btrfs_start_transaction(root, 0);
2041                 BUG_ON(IS_ERR(trans));
2042                 trans->block_rsv = rc->block_rsv;
2043
2044                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved);
2045                 if (ret) {
2046                         BUG_ON(ret != -EAGAIN);
2047                         ret = btrfs_commit_transaction(trans, root);
2048                         BUG_ON(ret);
2049                         continue;
2050                 }
2051
2052                 replaced = 0;
2053                 max_level = level;
2054
2055                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2056                 if (ret < 0) {
2057                         err = ret;
2058                         goto out;
2059                 }
2060                 if (ret > 0)
2061                         break;
2062
2063                 if (!find_next_key(path, level, &key) &&
2064                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2065                         ret = 0;
2066                 } else {
2067                         ret = replace_path(trans, root, reloc_root, path,
2068                                            &next_key, level, max_level);
2069                 }
2070                 if (ret < 0) {
2071                         err = ret;
2072                         goto out;
2073                 }
2074
2075                 if (ret > 0) {
2076                         level = ret;
2077                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2078                                               path->slots[level]);
2079                         replaced = 1;
2080                 }
2081
2082                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2083                 if (ret > 0)
2084                         break;
2085
2086                 BUG_ON(level == 0);
2087                 /*
2088                  * save the merging progress in the drop_progress.
2089                  * this is OK since root refs == 1 in this case.
2090                  */
2091                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2092                                path->slots[level]);
2093                 root_item->drop_level = level;
2094
2095                 nr = trans->blocks_used;
2096                 btrfs_end_transaction_throttle(trans, root);
2097
2098                 btrfs_btree_balance_dirty(root, nr);
2099
2100                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2101                         invalidate_extent_cache(root, &key, &next_key);
2102         }
2103
2104         /*
2105          * handle the case only one block in the fs tree need to be
2106          * relocated and the block is tree root.
2107          */
2108         leaf = btrfs_lock_root_node(root);
2109         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2110         btrfs_tree_unlock(leaf);
2111         free_extent_buffer(leaf);
2112         if (ret < 0)
2113                 err = ret;
2114 out:
2115         btrfs_free_path(path);
2116
2117         if (err == 0) {
2118                 memset(&root_item->drop_progress, 0,
2119                        sizeof(root_item->drop_progress));
2120                 root_item->drop_level = 0;
2121                 btrfs_set_root_refs(root_item, 0);
2122                 btrfs_update_reloc_root(trans, root);
2123         }
2124
2125         nr = trans->blocks_used;
2126         btrfs_end_transaction_throttle(trans, root);
2127
2128         btrfs_btree_balance_dirty(root, nr);
2129
2130         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2131                 invalidate_extent_cache(root, &key, &next_key);
2132
2133         return err;
2134 }
2135
2136 static noinline_for_stack
2137 int prepare_to_merge(struct reloc_control *rc, int err)
2138 {
2139         struct btrfs_root *root = rc->extent_root;
2140         struct btrfs_root *reloc_root;
2141         struct btrfs_trans_handle *trans;
2142         LIST_HEAD(reloc_roots);
2143         u64 num_bytes = 0;
2144         int ret;
2145
2146         mutex_lock(&root->fs_info->reloc_mutex);
2147         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2148         rc->merging_rsv_size += rc->nodes_relocated * 2;
2149         mutex_unlock(&root->fs_info->reloc_mutex);
2150
2151 again:
2152         if (!err) {
2153                 num_bytes = rc->merging_rsv_size;
2154                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes);
2155                 if (ret)
2156                         err = ret;
2157         }
2158
2159         trans = btrfs_join_transaction(rc->extent_root);
2160         if (IS_ERR(trans)) {
2161                 if (!err)
2162                         btrfs_block_rsv_release(rc->extent_root,
2163                                                 rc->block_rsv, num_bytes);
2164                 return PTR_ERR(trans);
2165         }
2166
2167         if (!err) {
2168                 if (num_bytes != rc->merging_rsv_size) {
2169                         btrfs_end_transaction(trans, rc->extent_root);
2170                         btrfs_block_rsv_release(rc->extent_root,
2171                                                 rc->block_rsv, num_bytes);
2172                         goto again;
2173                 }
2174         }
2175
2176         rc->merge_reloc_tree = 1;
2177
2178         while (!list_empty(&rc->reloc_roots)) {
2179                 reloc_root = list_entry(rc->reloc_roots.next,
2180                                         struct btrfs_root, root_list);
2181                 list_del_init(&reloc_root->root_list);
2182
2183                 root = read_fs_root(reloc_root->fs_info,
2184                                     reloc_root->root_key.offset);
2185                 BUG_ON(IS_ERR(root));
2186                 BUG_ON(root->reloc_root != reloc_root);
2187
2188                 /*
2189                  * set reference count to 1, so btrfs_recover_relocation
2190                  * knows it should resumes merging
2191                  */
2192                 if (!err)
2193                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2194                 btrfs_update_reloc_root(trans, root);
2195
2196                 list_add(&reloc_root->root_list, &reloc_roots);
2197         }
2198
2199         list_splice(&reloc_roots, &rc->reloc_roots);
2200
2201         if (!err)
2202                 btrfs_commit_transaction(trans, rc->extent_root);
2203         else
2204                 btrfs_end_transaction(trans, rc->extent_root);
2205         return err;
2206 }
2207
2208 static noinline_for_stack
2209 int merge_reloc_roots(struct reloc_control *rc)
2210 {
2211         struct btrfs_root *root;
2212         struct btrfs_root *reloc_root;
2213         LIST_HEAD(reloc_roots);
2214         int found = 0;
2215         int ret;
2216 again:
2217         root = rc->extent_root;
2218
2219         /*
2220          * this serializes us with btrfs_record_root_in_transaction,
2221          * we have to make sure nobody is in the middle of
2222          * adding their roots to the list while we are
2223          * doing this splice
2224          */
2225         mutex_lock(&root->fs_info->reloc_mutex);
2226         list_splice_init(&rc->reloc_roots, &reloc_roots);
2227         mutex_unlock(&root->fs_info->reloc_mutex);
2228
2229         while (!list_empty(&reloc_roots)) {
2230                 found = 1;
2231                 reloc_root = list_entry(reloc_roots.next,
2232                                         struct btrfs_root, root_list);
2233
2234                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2235                         root = read_fs_root(reloc_root->fs_info,
2236                                             reloc_root->root_key.offset);
2237                         BUG_ON(IS_ERR(root));
2238                         BUG_ON(root->reloc_root != reloc_root);
2239
2240                         ret = merge_reloc_root(rc, root);
2241                         BUG_ON(ret);
2242                 } else {
2243                         list_del_init(&reloc_root->root_list);
2244                 }
2245                 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
2246         }
2247
2248         if (found) {
2249                 found = 0;
2250                 goto again;
2251         }
2252         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2253         return 0;
2254 }
2255
2256 static void free_block_list(struct rb_root *blocks)
2257 {
2258         struct tree_block *block;
2259         struct rb_node *rb_node;
2260         while ((rb_node = rb_first(blocks))) {
2261                 block = rb_entry(rb_node, struct tree_block, rb_node);
2262                 rb_erase(rb_node, blocks);
2263                 kfree(block);
2264         }
2265 }
2266
2267 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2268                                       struct btrfs_root *reloc_root)
2269 {
2270         struct btrfs_root *root;
2271
2272         if (reloc_root->last_trans == trans->transid)
2273                 return 0;
2274
2275         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2276         BUG_ON(IS_ERR(root));
2277         BUG_ON(root->reloc_root != reloc_root);
2278
2279         return btrfs_record_root_in_trans(trans, root);
2280 }
2281
2282 static noinline_for_stack
2283 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2284                                      struct reloc_control *rc,
2285                                      struct backref_node *node,
2286                                      struct backref_edge *edges[], int *nr)
2287 {
2288         struct backref_node *next;
2289         struct btrfs_root *root;
2290         int index = 0;
2291
2292         next = node;
2293         while (1) {
2294                 cond_resched();
2295                 next = walk_up_backref(next, edges, &index);
2296                 root = next->root;
2297                 BUG_ON(!root);
2298                 BUG_ON(!root->ref_cows);
2299
2300                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2301                         record_reloc_root_in_trans(trans, root);
2302                         break;
2303                 }
2304
2305                 btrfs_record_root_in_trans(trans, root);
2306                 root = root->reloc_root;
2307
2308                 if (next->new_bytenr != root->node->start) {
2309                         BUG_ON(next->new_bytenr);
2310                         BUG_ON(!list_empty(&next->list));
2311                         next->new_bytenr = root->node->start;
2312                         next->root = root;
2313                         list_add_tail(&next->list,
2314                                       &rc->backref_cache.changed);
2315                         __mark_block_processed(rc, next);
2316                         break;
2317                 }
2318
2319                 WARN_ON(1);
2320                 root = NULL;
2321                 next = walk_down_backref(edges, &index);
2322                 if (!next || next->level <= node->level)
2323                         break;
2324         }
2325         if (!root)
2326                 return NULL;
2327
2328         *nr = index;
2329         next = node;
2330         /* setup backref node path for btrfs_reloc_cow_block */
2331         while (1) {
2332                 rc->backref_cache.path[next->level] = next;
2333                 if (--index < 0)
2334                         break;
2335                 next = edges[index]->node[UPPER];
2336         }
2337         return root;
2338 }
2339
2340 /*
2341  * select a tree root for relocation. return NULL if the block
2342  * is reference counted. we should use do_relocation() in this
2343  * case. return a tree root pointer if the block isn't reference
2344  * counted. return -ENOENT if the block is root of reloc tree.
2345  */
2346 static noinline_for_stack
2347 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2348                                    struct backref_node *node)
2349 {
2350         struct backref_node *next;
2351         struct btrfs_root *root;
2352         struct btrfs_root *fs_root = NULL;
2353         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2354         int index = 0;
2355
2356         next = node;
2357         while (1) {
2358                 cond_resched();
2359                 next = walk_up_backref(next, edges, &index);
2360                 root = next->root;
2361                 BUG_ON(!root);
2362
2363                 /* no other choice for non-references counted tree */
2364                 if (!root->ref_cows)
2365                         return root;
2366
2367                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2368                         fs_root = root;
2369
2370                 if (next != node)
2371                         return NULL;
2372
2373                 next = walk_down_backref(edges, &index);
2374                 if (!next || next->level <= node->level)
2375                         break;
2376         }
2377
2378         if (!fs_root)
2379                 return ERR_PTR(-ENOENT);
2380         return fs_root;
2381 }
2382
2383 static noinline_for_stack
2384 u64 calcu_metadata_size(struct reloc_control *rc,
2385                         struct backref_node *node, int reserve)
2386 {
2387         struct backref_node *next = node;
2388         struct backref_edge *edge;
2389         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2390         u64 num_bytes = 0;
2391         int index = 0;
2392
2393         BUG_ON(reserve && node->processed);
2394
2395         while (next) {
2396                 cond_resched();
2397                 while (1) {
2398                         if (next->processed && (reserve || next != node))
2399                                 break;
2400
2401                         num_bytes += btrfs_level_size(rc->extent_root,
2402                                                       next->level);
2403
2404                         if (list_empty(&next->upper))
2405                                 break;
2406
2407                         edge = list_entry(next->upper.next,
2408                                           struct backref_edge, list[LOWER]);
2409                         edges[index++] = edge;
2410                         next = edge->node[UPPER];
2411                 }
2412                 next = walk_down_backref(edges, &index);
2413         }
2414         return num_bytes;
2415 }
2416
2417 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2418                                   struct reloc_control *rc,
2419                                   struct backref_node *node)
2420 {
2421         struct btrfs_root *root = rc->extent_root;
2422         u64 num_bytes;
2423         int ret;
2424
2425         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2426
2427         trans->block_rsv = rc->block_rsv;
2428         ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes);
2429         if (ret) {
2430                 if (ret == -EAGAIN)
2431                         rc->commit_transaction = 1;
2432                 return ret;
2433         }
2434
2435         return 0;
2436 }
2437
2438 static void release_metadata_space(struct reloc_control *rc,
2439                                    struct backref_node *node)
2440 {
2441         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2442         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2443 }
2444
2445 /*
2446  * relocate a block tree, and then update pointers in upper level
2447  * blocks that reference the block to point to the new location.
2448  *
2449  * if called by link_to_upper, the block has already been relocated.
2450  * in that case this function just updates pointers.
2451  */
2452 static int do_relocation(struct btrfs_trans_handle *trans,
2453                          struct reloc_control *rc,
2454                          struct backref_node *node,
2455                          struct btrfs_key *key,
2456                          struct btrfs_path *path, int lowest)
2457 {
2458         struct backref_node *upper;
2459         struct backref_edge *edge;
2460         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2461         struct btrfs_root *root;
2462         struct extent_buffer *eb;
2463         u32 blocksize;
2464         u64 bytenr;
2465         u64 generation;
2466         int nr;
2467         int slot;
2468         int ret;
2469         int err = 0;
2470
2471         BUG_ON(lowest && node->eb);
2472
2473         path->lowest_level = node->level + 1;
2474         rc->backref_cache.path[node->level] = node;
2475         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2476                 cond_resched();
2477
2478                 upper = edge->node[UPPER];
2479                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2480                 BUG_ON(!root);
2481
2482                 if (upper->eb && !upper->locked) {
2483                         if (!lowest) {
2484                                 ret = btrfs_bin_search(upper->eb, key,
2485                                                        upper->level, &slot);
2486                                 BUG_ON(ret);
2487                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2488                                 if (node->eb->start == bytenr)
2489                                         goto next;
2490                         }
2491                         drop_node_buffer(upper);
2492                 }
2493
2494                 if (!upper->eb) {
2495                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2496                         if (ret < 0) {
2497                                 err = ret;
2498                                 break;
2499                         }
2500                         BUG_ON(ret > 0);
2501
2502                         if (!upper->eb) {
2503                                 upper->eb = path->nodes[upper->level];
2504                                 path->nodes[upper->level] = NULL;
2505                         } else {
2506                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2507                         }
2508
2509                         upper->locked = 1;
2510                         path->locks[upper->level] = 0;
2511
2512                         slot = path->slots[upper->level];
2513                         btrfs_release_path(path);
2514                 } else {
2515                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2516                                                &slot);
2517                         BUG_ON(ret);
2518                 }
2519
2520                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2521                 if (lowest) {
2522                         BUG_ON(bytenr != node->bytenr);
2523                 } else {
2524                         if (node->eb->start == bytenr)
2525                                 goto next;
2526                 }
2527
2528                 blocksize = btrfs_level_size(root, node->level);
2529                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2530                 eb = read_tree_block(root, bytenr, blocksize, generation);
2531                 if (!eb) {
2532                         err = -EIO;
2533                         goto next;
2534                 }
2535                 btrfs_tree_lock(eb);
2536                 btrfs_set_lock_blocking(eb);
2537
2538                 if (!node->eb) {
2539                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2540                                               slot, &eb);
2541                         btrfs_tree_unlock(eb);
2542                         free_extent_buffer(eb);
2543                         if (ret < 0) {
2544                                 err = ret;
2545                                 goto next;
2546                         }
2547                         BUG_ON(node->eb != eb);
2548                 } else {
2549                         btrfs_set_node_blockptr(upper->eb, slot,
2550                                                 node->eb->start);
2551                         btrfs_set_node_ptr_generation(upper->eb, slot,
2552                                                       trans->transid);
2553                         btrfs_mark_buffer_dirty(upper->eb);
2554
2555                         ret = btrfs_inc_extent_ref(trans, root,
2556                                                 node->eb->start, blocksize,
2557                                                 upper->eb->start,
2558                                                 btrfs_header_owner(upper->eb),
2559                                                 node->level, 0);
2560                         BUG_ON(ret);
2561
2562                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2563                         BUG_ON(ret);
2564                 }
2565 next:
2566                 if (!upper->pending)
2567                         drop_node_buffer(upper);
2568                 else
2569                         unlock_node_buffer(upper);
2570                 if (err)
2571                         break;
2572         }
2573
2574         if (!err && node->pending) {
2575                 drop_node_buffer(node);
2576                 list_move_tail(&node->list, &rc->backref_cache.changed);
2577                 node->pending = 0;
2578         }
2579
2580         path->lowest_level = 0;
2581         BUG_ON(err == -ENOSPC);
2582         return err;
2583 }
2584
2585 static int link_to_upper(struct btrfs_trans_handle *trans,
2586                          struct reloc_control *rc,
2587                          struct backref_node *node,
2588                          struct btrfs_path *path)
2589 {
2590         struct btrfs_key key;
2591
2592         btrfs_node_key_to_cpu(node->eb, &key, 0);
2593         return do_relocation(trans, rc, node, &key, path, 0);
2594 }
2595
2596 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2597                                 struct reloc_control *rc,
2598                                 struct btrfs_path *path, int err)
2599 {
2600         LIST_HEAD(list);
2601         struct backref_cache *cache = &rc->backref_cache;
2602         struct backref_node *node;
2603         int level;
2604         int ret;
2605
2606         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2607                 while (!list_empty(&cache->pending[level])) {
2608                         node = list_entry(cache->pending[level].next,
2609                                           struct backref_node, list);
2610                         list_move_tail(&node->list, &list);
2611                         BUG_ON(!node->pending);
2612
2613                         if (!err) {
2614                                 ret = link_to_upper(trans, rc, node, path);
2615                                 if (ret < 0)
2616                                         err = ret;
2617                         }
2618                 }
2619                 list_splice_init(&list, &cache->pending[level]);
2620         }
2621         return err;
2622 }
2623
2624 static void mark_block_processed(struct reloc_control *rc,
2625                                  u64 bytenr, u32 blocksize)
2626 {
2627         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2628                         EXTENT_DIRTY, GFP_NOFS);
2629 }
2630
2631 static void __mark_block_processed(struct reloc_control *rc,
2632                                    struct backref_node *node)
2633 {
2634         u32 blocksize;
2635         if (node->level == 0 ||
2636             in_block_group(node->bytenr, rc->block_group)) {
2637                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2638                 mark_block_processed(rc, node->bytenr, blocksize);
2639         }
2640         node->processed = 1;
2641 }
2642
2643 /*
2644  * mark a block and all blocks directly/indirectly reference the block
2645  * as processed.
2646  */
2647 static void update_processed_blocks(struct reloc_control *rc,
2648                                     struct backref_node *node)
2649 {
2650         struct backref_node *next = node;
2651         struct backref_edge *edge;
2652         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2653         int index = 0;
2654
2655         while (next) {
2656                 cond_resched();
2657                 while (1) {
2658                         if (next->processed)
2659                                 break;
2660
2661                         __mark_block_processed(rc, next);
2662
2663                         if (list_empty(&next->upper))
2664                                 break;
2665
2666                         edge = list_entry(next->upper.next,
2667                                           struct backref_edge, list[LOWER]);
2668                         edges[index++] = edge;
2669                         next = edge->node[UPPER];
2670                 }
2671                 next = walk_down_backref(edges, &index);
2672         }
2673 }
2674
2675 static int tree_block_processed(u64 bytenr, u32 blocksize,
2676                                 struct reloc_control *rc)
2677 {
2678         if (test_range_bit(&rc->processed_blocks, bytenr,
2679                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2680                 return 1;
2681         return 0;
2682 }
2683
2684 static int get_tree_block_key(struct reloc_control *rc,
2685                               struct tree_block *block)
2686 {
2687         struct extent_buffer *eb;
2688
2689         BUG_ON(block->key_ready);
2690         eb = read_tree_block(rc->extent_root, block->bytenr,
2691                              block->key.objectid, block->key.offset);
2692         BUG_ON(!eb);
2693         WARN_ON(btrfs_header_level(eb) != block->level);
2694         if (block->level == 0)
2695                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2696         else
2697                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2698         free_extent_buffer(eb);
2699         block->key_ready = 1;
2700         return 0;
2701 }
2702
2703 static int reada_tree_block(struct reloc_control *rc,
2704                             struct tree_block *block)
2705 {
2706         BUG_ON(block->key_ready);
2707         readahead_tree_block(rc->extent_root, block->bytenr,
2708                              block->key.objectid, block->key.offset);
2709         return 0;
2710 }
2711
2712 /*
2713  * helper function to relocate a tree block
2714  */
2715 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2716                                 struct reloc_control *rc,
2717                                 struct backref_node *node,
2718                                 struct btrfs_key *key,
2719                                 struct btrfs_path *path)
2720 {
2721         struct btrfs_root *root;
2722         int release = 0;
2723         int ret = 0;
2724
2725         if (!node)
2726                 return 0;
2727
2728         BUG_ON(node->processed);
2729         root = select_one_root(trans, node);
2730         if (root == ERR_PTR(-ENOENT)) {
2731                 update_processed_blocks(rc, node);
2732                 goto out;
2733         }
2734
2735         if (!root || root->ref_cows) {
2736                 ret = reserve_metadata_space(trans, rc, node);
2737                 if (ret)
2738                         goto out;
2739                 release = 1;
2740         }
2741
2742         if (root) {
2743                 if (root->ref_cows) {
2744                         BUG_ON(node->new_bytenr);
2745                         BUG_ON(!list_empty(&node->list));
2746                         btrfs_record_root_in_trans(trans, root);
2747                         root = root->reloc_root;
2748                         node->new_bytenr = root->node->start;
2749                         node->root = root;
2750                         list_add_tail(&node->list, &rc->backref_cache.changed);
2751                 } else {
2752                         path->lowest_level = node->level;
2753                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2754                         btrfs_release_path(path);
2755                         if (ret > 0)
2756                                 ret = 0;
2757                 }
2758                 if (!ret)
2759                         update_processed_blocks(rc, node);
2760         } else {
2761                 ret = do_relocation(trans, rc, node, key, path, 1);
2762         }
2763 out:
2764         if (ret || node->level == 0 || node->cowonly) {
2765                 if (release)
2766                         release_metadata_space(rc, node);
2767                 remove_backref_node(&rc->backref_cache, node);
2768         }
2769         return ret;
2770 }
2771
2772 /*
2773  * relocate a list of blocks
2774  */
2775 static noinline_for_stack
2776 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2777                          struct reloc_control *rc, struct rb_root *blocks)
2778 {
2779         struct backref_node *node;
2780         struct btrfs_path *path;
2781         struct tree_block *block;
2782         struct rb_node *rb_node;
2783         int ret;
2784         int err = 0;
2785
2786         path = btrfs_alloc_path();
2787         if (!path)
2788                 return -ENOMEM;
2789
2790         rb_node = rb_first(blocks);
2791         while (rb_node) {
2792                 block = rb_entry(rb_node, struct tree_block, rb_node);
2793                 if (!block->key_ready)
2794                         reada_tree_block(rc, block);
2795                 rb_node = rb_next(rb_node);
2796         }
2797
2798         rb_node = rb_first(blocks);
2799         while (rb_node) {
2800                 block = rb_entry(rb_node, struct tree_block, rb_node);
2801                 if (!block->key_ready)
2802                         get_tree_block_key(rc, block);
2803                 rb_node = rb_next(rb_node);
2804         }
2805
2806         rb_node = rb_first(blocks);
2807         while (rb_node) {
2808                 block = rb_entry(rb_node, struct tree_block, rb_node);
2809
2810                 node = build_backref_tree(rc, &block->key,
2811                                           block->level, block->bytenr);
2812                 if (IS_ERR(node)) {
2813                         err = PTR_ERR(node);
2814                         goto out;
2815                 }
2816
2817                 ret = relocate_tree_block(trans, rc, node, &block->key,
2818                                           path);
2819                 if (ret < 0) {
2820                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2821                                 err = ret;
2822                         goto out;
2823                 }
2824                 rb_node = rb_next(rb_node);
2825         }
2826 out:
2827         free_block_list(blocks);
2828         err = finish_pending_nodes(trans, rc, path, err);
2829
2830         btrfs_free_path(path);
2831         return err;
2832 }
2833
2834 static noinline_for_stack
2835 int prealloc_file_extent_cluster(struct inode *inode,
2836                                  struct file_extent_cluster *cluster)
2837 {
2838         u64 alloc_hint = 0;
2839         u64 start;
2840         u64 end;
2841         u64 offset = BTRFS_I(inode)->index_cnt;
2842         u64 num_bytes;
2843         int nr = 0;
2844         int ret = 0;
2845
2846         BUG_ON(cluster->start != cluster->boundary[0]);
2847         mutex_lock(&inode->i_mutex);
2848
2849         ret = btrfs_check_data_free_space(inode, cluster->end +
2850                                           1 - cluster->start);
2851         if (ret)
2852                 goto out;
2853
2854         while (nr < cluster->nr) {
2855                 start = cluster->boundary[nr] - offset;
2856                 if (nr + 1 < cluster->nr)
2857                         end = cluster->boundary[nr + 1] - 1 - offset;
2858                 else
2859                         end = cluster->end - offset;
2860
2861                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2862                 num_bytes = end + 1 - start;
2863                 ret = btrfs_prealloc_file_range(inode, 0, start,
2864                                                 num_bytes, num_bytes,
2865                                                 end + 1, &alloc_hint);
2866                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2867                 if (ret)
2868                         break;
2869                 nr++;
2870         }
2871         btrfs_free_reserved_data_space(inode, cluster->end +
2872                                        1 - cluster->start);
2873 out:
2874         mutex_unlock(&inode->i_mutex);
2875         return ret;
2876 }
2877
2878 static noinline_for_stack
2879 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2880                          u64 block_start)
2881 {
2882         struct btrfs_root *root = BTRFS_I(inode)->root;
2883         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2884         struct extent_map *em;
2885         int ret = 0;
2886
2887         em = alloc_extent_map();
2888         if (!em)
2889                 return -ENOMEM;
2890
2891         em->start = start;
2892         em->len = end + 1 - start;
2893         em->block_len = em->len;
2894         em->block_start = block_start;
2895         em->bdev = root->fs_info->fs_devices->latest_bdev;
2896         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2897
2898         lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2899         while (1) {
2900                 write_lock(&em_tree->lock);
2901                 ret = add_extent_mapping(em_tree, em);
2902                 write_unlock(&em_tree->lock);
2903                 if (ret != -EEXIST) {
2904                         free_extent_map(em);
2905                         break;
2906                 }
2907                 btrfs_drop_extent_cache(inode, start, end, 0);
2908         }
2909         unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2910         return ret;
2911 }
2912
2913 static int relocate_file_extent_cluster(struct inode *inode,
2914                                         struct file_extent_cluster *cluster)
2915 {
2916         u64 page_start;
2917         u64 page_end;
2918         u64 offset = BTRFS_I(inode)->index_cnt;
2919         unsigned long index;
2920         unsigned long last_index;
2921         struct page *page;
2922         struct file_ra_state *ra;
2923         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
2924         int nr = 0;
2925         int ret = 0;
2926
2927         if (!cluster->nr)
2928                 return 0;
2929
2930         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2931         if (!ra)
2932                 return -ENOMEM;
2933
2934         ret = prealloc_file_extent_cluster(inode, cluster);
2935         if (ret)
2936                 goto out;
2937
2938         file_ra_state_init(ra, inode->i_mapping);
2939
2940         ret = setup_extent_mapping(inode, cluster->start - offset,
2941                                    cluster->end - offset, cluster->start);
2942         if (ret)
2943                 goto out;
2944
2945         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2946         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2947         while (index <= last_index) {
2948                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2949                 if (ret)
2950                         goto out;
2951
2952                 page = find_lock_page(inode->i_mapping, index);
2953                 if (!page) {
2954                         page_cache_sync_readahead(inode->i_mapping,
2955                                                   ra, NULL, index,
2956                                                   last_index + 1 - index);
2957                         page = find_or_create_page(inode->i_mapping, index,
2958                                                    mask);
2959                         if (!page) {
2960                                 btrfs_delalloc_release_metadata(inode,
2961                                                         PAGE_CACHE_SIZE);
2962                                 ret = -ENOMEM;
2963                                 goto out;
2964                         }
2965                 }
2966
2967                 if (PageReadahead(page)) {
2968                         page_cache_async_readahead(inode->i_mapping,
2969                                                    ra, NULL, page, index,
2970                                                    last_index + 1 - index);
2971                 }
2972
2973                 if (!PageUptodate(page)) {
2974                         btrfs_readpage(NULL, page);
2975                         lock_page(page);
2976                         if (!PageUptodate(page)) {
2977                                 unlock_page(page);
2978                                 page_cache_release(page);
2979                                 btrfs_delalloc_release_metadata(inode,
2980                                                         PAGE_CACHE_SIZE);
2981                                 ret = -EIO;
2982                                 goto out;
2983                         }
2984                 }
2985
2986                 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2987                 page_end = page_start + PAGE_CACHE_SIZE - 1;
2988
2989                 lock_extent(&BTRFS_I(inode)->io_tree,
2990                             page_start, page_end, GFP_NOFS);
2991
2992                 set_page_extent_mapped(page);
2993
2994                 if (nr < cluster->nr &&
2995                     page_start + offset == cluster->boundary[nr]) {
2996                         set_extent_bits(&BTRFS_I(inode)->io_tree,
2997                                         page_start, page_end,
2998                                         EXTENT_BOUNDARY, GFP_NOFS);
2999                         nr++;
3000                 }
3001
3002                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3003                 set_page_dirty(page);
3004
3005                 unlock_extent(&BTRFS_I(inode)->io_tree,
3006                               page_start, page_end, GFP_NOFS);
3007                 unlock_page(page);
3008                 page_cache_release(page);
3009
3010                 index++;
3011                 balance_dirty_pages_ratelimited(inode->i_mapping);
3012                 btrfs_throttle(BTRFS_I(inode)->root);
3013         }
3014         WARN_ON(nr != cluster->nr);
3015 out:
3016         kfree(ra);
3017         return ret;
3018 }
3019
3020 static noinline_for_stack
3021 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3022                          struct file_extent_cluster *cluster)
3023 {
3024         int ret;
3025
3026         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3027                 ret = relocate_file_extent_cluster(inode, cluster);
3028                 if (ret)
3029                         return ret;
3030                 cluster->nr = 0;
3031         }
3032
3033         if (!cluster->nr)
3034                 cluster->start = extent_key->objectid;
3035         else
3036                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3037         cluster->end = extent_key->objectid + extent_key->offset - 1;
3038         cluster->boundary[cluster->nr] = extent_key->objectid;
3039         cluster->nr++;
3040
3041         if (cluster->nr >= MAX_EXTENTS) {
3042                 ret = relocate_file_extent_cluster(inode, cluster);
3043                 if (ret)
3044                         return ret;
3045                 cluster->nr = 0;
3046         }
3047         return 0;
3048 }
3049
3050 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3051 static int get_ref_objectid_v0(struct reloc_control *rc,
3052                                struct btrfs_path *path,
3053                                struct btrfs_key *extent_key,
3054                                u64 *ref_objectid, int *path_change)
3055 {
3056         struct btrfs_key key;
3057         struct extent_buffer *leaf;
3058         struct btrfs_extent_ref_v0 *ref0;
3059         int ret;
3060         int slot;
3061
3062         leaf = path->nodes[0];
3063         slot = path->slots[0];
3064         while (1) {
3065                 if (slot >= btrfs_header_nritems(leaf)) {
3066                         ret = btrfs_next_leaf(rc->extent_root, path);
3067                         if (ret < 0)
3068                                 return ret;
3069                         BUG_ON(ret > 0);
3070                         leaf = path->nodes[0];
3071                         slot = path->slots[0];
3072                         if (path_change)
3073                                 *path_change = 1;
3074                 }
3075                 btrfs_item_key_to_cpu(leaf, &key, slot);
3076                 if (key.objectid != extent_key->objectid)
3077                         return -ENOENT;
3078
3079                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3080                         slot++;
3081                         continue;
3082                 }
3083                 ref0 = btrfs_item_ptr(leaf, slot,
3084                                 struct btrfs_extent_ref_v0);
3085                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3086                 break;
3087         }
3088         return 0;
3089 }
3090 #endif
3091
3092 /*
3093  * helper to add a tree block to the list.
3094  * the major work is getting the generation and level of the block
3095  */
3096 static int add_tree_block(struct reloc_control *rc,
3097                           struct btrfs_key *extent_key,
3098                           struct btrfs_path *path,
3099                           struct rb_root *blocks)
3100 {
3101         struct extent_buffer *eb;
3102         struct btrfs_extent_item *ei;
3103         struct btrfs_tree_block_info *bi;
3104         struct tree_block *block;
3105         struct rb_node *rb_node;
3106         u32 item_size;
3107         int level = -1;
3108         int generation;
3109
3110         eb =  path->nodes[0];
3111         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3112
3113         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3114                 ei = btrfs_item_ptr(eb, path->slots[0],
3115                                 struct btrfs_extent_item);
3116                 bi = (struct btrfs_tree_block_info *)(ei + 1);
3117                 generation = btrfs_extent_generation(eb, ei);
3118                 level = btrfs_tree_block_level(eb, bi);
3119         } else {
3120 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3121                 u64 ref_owner;
3122                 int ret;
3123
3124                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3125                 ret = get_ref_objectid_v0(rc, path, extent_key,
3126                                           &ref_owner, NULL);
3127                 if (ret < 0)
3128                         return ret;
3129                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3130                 level = (int)ref_owner;
3131                 /* FIXME: get real generation */
3132                 generation = 0;
3133 #else
3134                 BUG();
3135 #endif
3136         }
3137
3138         btrfs_release_path(path);
3139
3140         BUG_ON(level == -1);
3141
3142         block = kmalloc(sizeof(*block), GFP_NOFS);
3143         if (!block)
3144                 return -ENOMEM;
3145
3146         block->bytenr = extent_key->objectid;
3147         block->key.objectid = extent_key->offset;
3148         block->key.offset = generation;
3149         block->level = level;
3150         block->key_ready = 0;
3151
3152         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3153         BUG_ON(rb_node);
3154
3155         return 0;
3156 }
3157
3158 /*
3159  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3160  */
3161 static int __add_tree_block(struct reloc_control *rc,
3162                             u64 bytenr, u32 blocksize,
3163                             struct rb_root *blocks)
3164 {
3165         struct btrfs_path *path;
3166         struct btrfs_key key;
3167         int ret;
3168
3169         if (tree_block_processed(bytenr, blocksize, rc))
3170                 return 0;
3171
3172         if (tree_search(blocks, bytenr))
3173                 return 0;
3174
3175         path = btrfs_alloc_path();
3176         if (!path)
3177                 return -ENOMEM;
3178
3179         key.objectid = bytenr;
3180         key.type = BTRFS_EXTENT_ITEM_KEY;
3181         key.offset = blocksize;
3182
3183         path->search_commit_root = 1;
3184         path->skip_locking = 1;
3185         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3186         if (ret < 0)
3187                 goto out;
3188         BUG_ON(ret);
3189
3190         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3191         ret = add_tree_block(rc, &key, path, blocks);
3192 out:
3193         btrfs_free_path(path);
3194         return ret;
3195 }
3196
3197 /*
3198  * helper to check if the block use full backrefs for pointers in it
3199  */
3200 static int block_use_full_backref(struct reloc_control *rc,
3201                                   struct extent_buffer *eb)
3202 {
3203         u64 flags;
3204         int ret;
3205
3206         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3207             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3208                 return 1;
3209
3210         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3211                                        eb->start, eb->len, NULL, &flags);
3212         BUG_ON(ret);
3213
3214         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3215                 ret = 1;
3216         else
3217                 ret = 0;
3218         return ret;
3219 }
3220
3221 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3222                                     struct inode *inode, u64 ino)
3223 {
3224         struct btrfs_key key;
3225         struct btrfs_path *path;
3226         struct btrfs_root *root = fs_info->tree_root;
3227         struct btrfs_trans_handle *trans;
3228         unsigned long nr;
3229         int ret = 0;
3230
3231         if (inode)
3232                 goto truncate;
3233
3234         key.objectid = ino;
3235         key.type = BTRFS_INODE_ITEM_KEY;
3236         key.offset = 0;
3237
3238         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3239         if (IS_ERR_OR_NULL(inode) || is_bad_inode(inode)) {
3240                 if (inode && !IS_ERR(inode))
3241                         iput(inode);
3242                 return -ENOENT;
3243         }
3244
3245 truncate:
3246         path = btrfs_alloc_path();
3247         if (!path) {
3248                 ret = -ENOMEM;
3249                 goto out;
3250         }
3251
3252         trans = btrfs_join_transaction(root);
3253         if (IS_ERR(trans)) {
3254                 btrfs_free_path(path);
3255                 ret = PTR_ERR(trans);
3256                 goto out;
3257         }
3258
3259         ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3260
3261         btrfs_free_path(path);
3262         nr = trans->blocks_used;
3263         btrfs_end_transaction(trans, root);
3264         btrfs_btree_balance_dirty(root, nr);
3265 out:
3266         iput(inode);
3267         return ret;
3268 }
3269
3270 /*
3271  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3272  * this function scans fs tree to find blocks reference the data extent
3273  */
3274 static int find_data_references(struct reloc_control *rc,
3275                                 struct btrfs_key *extent_key,
3276                                 struct extent_buffer *leaf,
3277                                 struct btrfs_extent_data_ref *ref,
3278                                 struct rb_root *blocks)
3279 {
3280         struct btrfs_path *path;
3281         struct tree_block *block;
3282         struct btrfs_root *root;
3283         struct btrfs_file_extent_item *fi;
3284         struct rb_node *rb_node;
3285         struct btrfs_key key;
3286         u64 ref_root;
3287         u64 ref_objectid;
3288         u64 ref_offset;
3289         u32 ref_count;
3290         u32 nritems;
3291         int err = 0;
3292         int added = 0;
3293         int counted;
3294         int ret;
3295
3296         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3297         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3298         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3299         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3300
3301         /*
3302          * This is an extent belonging to the free space cache, lets just delete
3303          * it and redo the search.
3304          */
3305         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3306                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3307                                                NULL, ref_objectid);
3308                 if (ret != -ENOENT)
3309                         return ret;
3310                 ret = 0;
3311         }
3312
3313         path = btrfs_alloc_path();
3314         if (!path)
3315                 return -ENOMEM;
3316         path->reada = 1;
3317
3318         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3319         if (IS_ERR(root)) {
3320                 err = PTR_ERR(root);
3321                 goto out;
3322         }
3323
3324         key.objectid = ref_objectid;
3325         key.type = BTRFS_EXTENT_DATA_KEY;
3326         if (ref_offset > ((u64)-1 << 32))
3327                 key.offset = 0;
3328         else
3329                 key.offset = ref_offset;
3330
3331         path->search_commit_root = 1;
3332         path->skip_locking = 1;
3333         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3334         if (ret < 0) {
3335                 err = ret;
3336                 goto out;
3337         }
3338
3339         leaf = path->nodes[0];
3340         nritems = btrfs_header_nritems(leaf);
3341         /*
3342          * the references in tree blocks that use full backrefs
3343          * are not counted in
3344          */
3345         if (block_use_full_backref(rc, leaf))
3346                 counted = 0;
3347         else
3348                 counted = 1;
3349         rb_node = tree_search(blocks, leaf->start);
3350         if (rb_node) {
3351                 if (counted)
3352                         added = 1;
3353                 else
3354                         path->slots[0] = nritems;
3355         }
3356
3357         while (ref_count > 0) {
3358                 while (path->slots[0] >= nritems) {
3359                         ret = btrfs_next_leaf(root, path);
3360                         if (ret < 0) {
3361                                 err = ret;
3362                                 goto out;
3363                         }
3364                         if (ret > 0) {
3365                                 WARN_ON(1);
3366                                 goto out;
3367                         }
3368
3369                         leaf = path->nodes[0];
3370                         nritems = btrfs_header_nritems(leaf);
3371                         added = 0;
3372
3373                         if (block_use_full_backref(rc, leaf))
3374                                 counted = 0;
3375                         else
3376                                 counted = 1;
3377                         rb_node = tree_search(blocks, leaf->start);
3378                         if (rb_node) {
3379                                 if (counted)
3380                                         added = 1;
3381                                 else
3382                                         path->slots[0] = nritems;
3383                         }
3384                 }
3385
3386                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3387                 if (key.objectid != ref_objectid ||
3388                     key.type != BTRFS_EXTENT_DATA_KEY) {
3389                         WARN_ON(1);
3390                         break;
3391                 }
3392
3393                 fi = btrfs_item_ptr(leaf, path->slots[0],
3394                                     struct btrfs_file_extent_item);
3395
3396                 if (btrfs_file_extent_type(leaf, fi) ==
3397                     BTRFS_FILE_EXTENT_INLINE)
3398                         goto next;
3399
3400                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3401                     extent_key->objectid)
3402                         goto next;
3403
3404                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3405                 if (key.offset != ref_offset)
3406                         goto next;
3407
3408                 if (counted)
3409                         ref_count--;
3410                 if (added)
3411                         goto next;
3412
3413                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3414                         block = kmalloc(sizeof(*block), GFP_NOFS);
3415                         if (!block) {
3416                                 err = -ENOMEM;
3417                                 break;
3418                         }
3419                         block->bytenr = leaf->start;
3420                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3421                         block->level = 0;
3422                         block->key_ready = 1;
3423                         rb_node = tree_insert(blocks, block->bytenr,
3424                                               &block->rb_node);
3425                         BUG_ON(rb_node);
3426                 }
3427                 if (counted)
3428                         added = 1;
3429                 else
3430                         path->slots[0] = nritems;
3431 next:
3432                 path->slots[0]++;
3433
3434         }
3435 out:
3436         btrfs_free_path(path);
3437         return err;
3438 }
3439
3440 /*
3441  * hepler to find all tree blocks that reference a given data extent
3442  */
3443 static noinline_for_stack
3444 int add_data_references(struct reloc_control *rc,
3445                         struct btrfs_key *extent_key,
3446                         struct btrfs_path *path,
3447                         struct rb_root *blocks)
3448 {
3449         struct btrfs_key key;
3450         struct extent_buffer *eb;
3451         struct btrfs_extent_data_ref *dref;
3452         struct btrfs_extent_inline_ref *iref;
3453         unsigned long ptr;
3454         unsigned long end;
3455         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3456         int ret;
3457         int err = 0;
3458
3459         eb = path->nodes[0];
3460         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3461         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3462 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3463         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3464                 ptr = end;
3465         else
3466 #endif
3467                 ptr += sizeof(struct btrfs_extent_item);
3468
3469         while (ptr < end) {
3470                 iref = (struct btrfs_extent_inline_ref *)ptr;
3471                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3472                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3473                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3474                         ret = __add_tree_block(rc, key.offset, blocksize,
3475                                                blocks);
3476                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3477                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3478                         ret = find_data_references(rc, extent_key,
3479                                                    eb, dref, blocks);
3480                 } else {
3481                         BUG();
3482                 }
3483                 ptr += btrfs_extent_inline_ref_size(key.type);
3484         }
3485         WARN_ON(ptr > end);
3486
3487         while (1) {
3488                 cond_resched();
3489                 eb = path->nodes[0];
3490                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3491                         ret = btrfs_next_leaf(rc->extent_root, path);
3492                         if (ret < 0) {
3493                                 err = ret;
3494                                 break;
3495                         }
3496                         if (ret > 0)
3497                                 break;
3498                         eb = path->nodes[0];
3499                 }
3500
3501                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3502                 if (key.objectid != extent_key->objectid)
3503                         break;
3504
3505 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3506                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3507                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3508 #else
3509                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3510                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3511 #endif
3512                         ret = __add_tree_block(rc, key.offset, blocksize,
3513                                                blocks);
3514                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3515                         dref = btrfs_item_ptr(eb, path->slots[0],
3516                                               struct btrfs_extent_data_ref);
3517                         ret = find_data_references(rc, extent_key,
3518                                                    eb, dref, blocks);
3519                 } else {
3520                         ret = 0;
3521                 }
3522                 if (ret) {
3523                         err = ret;
3524                         break;
3525                 }
3526                 path->slots[0]++;
3527         }
3528         btrfs_release_path(path);
3529         if (err)
3530                 free_block_list(blocks);
3531         return err;
3532 }
3533
3534 /*
3535  * hepler to find next unprocessed extent
3536  */
3537 static noinline_for_stack
3538 int find_next_extent(struct btrfs_trans_handle *trans,
3539                      struct reloc_control *rc, struct btrfs_path *path,
3540                      struct btrfs_key *extent_key)
3541 {
3542         struct btrfs_key key;
3543         struct extent_buffer *leaf;
3544         u64 start, end, last;
3545         int ret;
3546
3547         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3548         while (1) {
3549                 cond_resched();
3550                 if (rc->search_start >= last) {
3551                         ret = 1;
3552                         break;
3553                 }
3554
3555                 key.objectid = rc->search_start;
3556                 key.type = BTRFS_EXTENT_ITEM_KEY;
3557                 key.offset = 0;
3558
3559                 path->search_commit_root = 1;
3560                 path->skip_locking = 1;
3561                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3562                                         0, 0);
3563                 if (ret < 0)
3564                         break;
3565 next:
3566                 leaf = path->nodes[0];
3567                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3568                         ret = btrfs_next_leaf(rc->extent_root, path);
3569                         if (ret != 0)
3570                                 break;
3571                         leaf = path->nodes[0];
3572                 }
3573
3574                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3575                 if (key.objectid >= last) {
3576                         ret = 1;
3577                         break;
3578                 }
3579
3580                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3581                     key.objectid + key.offset <= rc->search_start) {
3582                         path->slots[0]++;
3583                         goto next;
3584                 }
3585
3586                 ret = find_first_extent_bit(&rc->processed_blocks,
3587                                             key.objectid, &start, &end,
3588                                             EXTENT_DIRTY);
3589
3590                 if (ret == 0 && start <= key.objectid) {
3591                         btrfs_release_path(path);
3592                         rc->search_start = end + 1;
3593                 } else {
3594                         rc->search_start = key.objectid + key.offset;
3595                         memcpy(extent_key, &key, sizeof(key));
3596                         return 0;
3597                 }
3598         }
3599         btrfs_release_path(path);
3600         return ret;
3601 }
3602
3603 static void set_reloc_control(struct reloc_control *rc)
3604 {
3605         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3606
3607         mutex_lock(&fs_info->reloc_mutex);
3608         fs_info->reloc_ctl = rc;
3609         mutex_unlock(&fs_info->reloc_mutex);
3610 }
3611
3612 static void unset_reloc_control(struct reloc_control *rc)
3613 {
3614         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3615
3616         mutex_lock(&fs_info->reloc_mutex);
3617         fs_info->reloc_ctl = NULL;
3618         mutex_unlock(&fs_info->reloc_mutex);
3619 }
3620
3621 static int check_extent_flags(u64 flags)
3622 {
3623         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3624             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3625                 return 1;
3626         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3627             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3628                 return 1;
3629         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3630             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3631                 return 1;
3632         return 0;
3633 }
3634
3635 static noinline_for_stack
3636 int prepare_to_relocate(struct reloc_control *rc)
3637 {
3638         struct btrfs_trans_handle *trans;
3639         int ret;
3640
3641         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root);
3642         if (!rc->block_rsv)
3643                 return -ENOMEM;
3644
3645         /*
3646          * reserve some space for creating reloc trees.
3647          * btrfs_init_reloc_root will use them when there
3648          * is no reservation in transaction handle.
3649          */
3650         ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3651                                   rc->extent_root->nodesize * 256);
3652         if (ret)
3653                 return ret;
3654
3655         memset(&rc->cluster, 0, sizeof(rc->cluster));
3656         rc->search_start = rc->block_group->key.objectid;
3657         rc->extents_found = 0;
3658         rc->nodes_relocated = 0;
3659         rc->merging_rsv_size = 0;
3660
3661         rc->create_reloc_tree = 1;
3662         set_reloc_control(rc);
3663
3664         trans = btrfs_join_transaction(rc->extent_root);
3665         BUG_ON(IS_ERR(trans));
3666         btrfs_commit_transaction(trans, rc->extent_root);
3667         return 0;
3668 }
3669
3670 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3671 {
3672         struct rb_root blocks = RB_ROOT;
3673         struct btrfs_key key;
3674         struct btrfs_trans_handle *trans = NULL;
3675         struct btrfs_path *path;
3676         struct btrfs_extent_item *ei;
3677         unsigned long nr;
3678         u64 flags;
3679         u32 item_size;
3680         int ret;
3681         int err = 0;
3682         int progress = 0;
3683
3684         path = btrfs_alloc_path();
3685         if (!path)
3686                 return -ENOMEM;
3687         path->reada = 1;
3688
3689         ret = prepare_to_relocate(rc);
3690         if (ret) {
3691                 err = ret;
3692                 goto out_free;
3693         }
3694
3695         while (1) {
3696                 progress++;
3697                 trans = btrfs_start_transaction(rc->extent_root, 0);
3698                 BUG_ON(IS_ERR(trans));
3699 restart:
3700                 if (update_backref_cache(trans, &rc->backref_cache)) {
3701                         btrfs_end_transaction(trans, rc->extent_root);
3702                         continue;
3703                 }
3704
3705                 ret = find_next_extent(trans, rc, path, &key);
3706                 if (ret < 0)
3707                         err = ret;
3708                 if (ret != 0)
3709                         break;
3710
3711                 rc->extents_found++;
3712
3713                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3714                                     struct btrfs_extent_item);
3715                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3716                 if (item_size >= sizeof(*ei)) {
3717                         flags = btrfs_extent_flags(path->nodes[0], ei);
3718                         ret = check_extent_flags(flags);
3719                         BUG_ON(ret);
3720
3721                 } else {
3722 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3723                         u64 ref_owner;
3724                         int path_change = 0;
3725
3726                         BUG_ON(item_size !=
3727                                sizeof(struct btrfs_extent_item_v0));
3728                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3729                                                   &path_change);
3730                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3731                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3732                         else
3733                                 flags = BTRFS_EXTENT_FLAG_DATA;
3734
3735                         if (path_change) {
3736                                 btrfs_release_path(path);
3737
3738                                 path->search_commit_root = 1;
3739                                 path->skip_locking = 1;
3740                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3741                                                         &key, path, 0, 0);
3742                                 if (ret < 0) {
3743                                         err = ret;
3744                                         break;
3745                                 }
3746                                 BUG_ON(ret > 0);
3747                         }
3748 #else
3749                         BUG();
3750 #endif
3751                 }
3752
3753                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3754                         ret = add_tree_block(rc, &key, path, &blocks);
3755                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3756                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3757                         ret = add_data_references(rc, &key, path, &blocks);
3758                 } else {
3759                         btrfs_release_path(path);
3760                         ret = 0;
3761                 }
3762                 if (ret < 0) {
3763                         err = ret;
3764                         break;
3765                 }
3766
3767                 if (!RB_EMPTY_ROOT(&blocks)) {
3768                         ret = relocate_tree_blocks(trans, rc, &blocks);
3769                         if (ret < 0) {
3770                                 if (ret != -EAGAIN) {
3771                                         err = ret;
3772                                         break;
3773                                 }
3774                                 rc->extents_found--;
3775                                 rc->search_start = key.objectid;
3776                         }
3777                 }
3778
3779                 ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
3780                 if (ret < 0) {
3781                         if (ret != -EAGAIN) {
3782                                 err = ret;
3783                                 WARN_ON(1);
3784                                 break;
3785                         }
3786                         rc->commit_transaction = 1;
3787                 }
3788
3789                 if (rc->commit_transaction) {
3790                         rc->commit_transaction = 0;
3791                         ret = btrfs_commit_transaction(trans, rc->extent_root);
3792                         BUG_ON(ret);
3793                 } else {
3794                         nr = trans->blocks_used;
3795                         btrfs_end_transaction_throttle(trans, rc->extent_root);
3796                         btrfs_btree_balance_dirty(rc->extent_root, nr);
3797                 }
3798                 trans = NULL;
3799
3800                 if (rc->stage == MOVE_DATA_EXTENTS &&
3801                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3802                         rc->found_file_extent = 1;
3803                         ret = relocate_data_extent(rc->data_inode,
3804                                                    &key, &rc->cluster);
3805                         if (ret < 0) {
3806                                 err = ret;
3807                                 break;
3808                         }
3809                 }
3810         }
3811         if (trans && progress && err == -ENOSPC) {
3812                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
3813                                               rc->block_group->flags);
3814                 if (ret == 0) {
3815                         err = 0;
3816                         progress = 0;
3817                         goto restart;
3818                 }
3819         }
3820
3821         btrfs_release_path(path);
3822         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3823                           GFP_NOFS);
3824
3825         if (trans) {
3826                 nr = trans->blocks_used;
3827                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3828                 btrfs_btree_balance_dirty(rc->extent_root, nr);
3829         }
3830
3831         if (!err) {
3832                 ret = relocate_file_extent_cluster(rc->data_inode,
3833                                                    &rc->cluster);
3834                 if (ret < 0)
3835                         err = ret;
3836         }
3837
3838         rc->create_reloc_tree = 0;
3839         set_reloc_control(rc);
3840
3841         backref_cache_cleanup(&rc->backref_cache);
3842         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3843
3844         err = prepare_to_merge(rc, err);
3845
3846         merge_reloc_roots(rc);
3847
3848         rc->merge_reloc_tree = 0;
3849         unset_reloc_control(rc);
3850         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3851
3852         /* get rid of pinned extents */
3853         trans = btrfs_join_transaction(rc->extent_root);
3854         if (IS_ERR(trans))
3855                 err = PTR_ERR(trans);
3856         else
3857                 btrfs_commit_transaction(trans, rc->extent_root);
3858 out_free:
3859         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3860         btrfs_free_path(path);
3861         return err;
3862 }
3863
3864 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3865                                  struct btrfs_root *root, u64 objectid)
3866 {
3867         struct btrfs_path *path;
3868         struct btrfs_inode_item *item;
3869         struct extent_buffer *leaf;
3870         int ret;
3871
3872         path = btrfs_alloc_path();
3873         if (!path)
3874                 return -ENOMEM;
3875
3876         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3877         if (ret)
3878                 goto out;
3879
3880         leaf = path->nodes[0];
3881         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3882         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3883         btrfs_set_inode_generation(leaf, item, 1);
3884         btrfs_set_inode_size(leaf, item, 0);
3885         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3886         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3887                                           BTRFS_INODE_PREALLOC);
3888         btrfs_mark_buffer_dirty(leaf);
3889         btrfs_release_path(path);
3890 out:
3891         btrfs_free_path(path);
3892         return ret;
3893 }
3894
3895 /*
3896  * helper to create inode for data relocation.
3897  * the inode is in data relocation tree and its link count is 0
3898  */
3899 static noinline_for_stack
3900 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3901                                  struct btrfs_block_group_cache *group)
3902 {
3903         struct inode *inode = NULL;
3904         struct btrfs_trans_handle *trans;
3905         struct btrfs_root *root;
3906         struct btrfs_key key;
3907         unsigned long nr;
3908         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3909         int err = 0;
3910
3911         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3912         if (IS_ERR(root))
3913                 return ERR_CAST(root);
3914
3915         trans = btrfs_start_transaction(root, 6);
3916         if (IS_ERR(trans))
3917                 return ERR_CAST(trans);
3918
3919         err = btrfs_find_free_objectid(root, &objectid);
3920         if (err)
3921                 goto out;
3922
3923         err = __insert_orphan_inode(trans, root, objectid);
3924         BUG_ON(err);
3925
3926         key.objectid = objectid;
3927         key.type = BTRFS_INODE_ITEM_KEY;
3928         key.offset = 0;
3929         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3930         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3931         BTRFS_I(inode)->index_cnt = group->key.objectid;
3932
3933         err = btrfs_orphan_add(trans, inode);
3934 out:
3935         nr = trans->blocks_used;
3936         btrfs_end_transaction(trans, root);
3937         btrfs_btree_balance_dirty(root, nr);
3938         if (err) {
3939                 if (inode)
3940                         iput(inode);
3941                 inode = ERR_PTR(err);
3942         }
3943         return inode;
3944 }
3945
3946 static struct reloc_control *alloc_reloc_control(void)
3947 {
3948         struct reloc_control *rc;
3949
3950         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3951         if (!rc)
3952                 return NULL;
3953
3954         INIT_LIST_HEAD(&rc->reloc_roots);
3955         backref_cache_init(&rc->backref_cache);
3956         mapping_tree_init(&rc->reloc_root_tree);
3957         extent_io_tree_init(&rc->processed_blocks, NULL);
3958         return rc;
3959 }
3960
3961 /*
3962  * function to relocate all extents in a block group.
3963  */
3964 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3965 {
3966         struct btrfs_fs_info *fs_info = extent_root->fs_info;
3967         struct reloc_control *rc;
3968         struct inode *inode;
3969         struct btrfs_path *path;
3970         int ret;
3971         int rw = 0;
3972         int err = 0;
3973
3974         rc = alloc_reloc_control();
3975         if (!rc)
3976                 return -ENOMEM;
3977
3978         rc->extent_root = extent_root;
3979
3980         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3981         BUG_ON(!rc->block_group);
3982
3983         if (!rc->block_group->ro) {
3984                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
3985                 if (ret) {
3986                         err = ret;
3987                         goto out;
3988                 }
3989                 rw = 1;
3990         }
3991
3992         path = btrfs_alloc_path();
3993         if (!path) {
3994                 err = -ENOMEM;
3995                 goto out;
3996         }
3997
3998         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
3999                                         path);
4000         btrfs_free_path(path);
4001
4002         if (!IS_ERR(inode))
4003                 ret = delete_block_group_cache(fs_info, inode, 0);
4004         else
4005                 ret = PTR_ERR(inode);
4006
4007         if (ret && ret != -ENOENT) {
4008                 err = ret;
4009                 goto out;
4010         }
4011
4012         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4013         if (IS_ERR(rc->data_inode)) {
4014                 err = PTR_ERR(rc->data_inode);
4015                 rc->data_inode = NULL;
4016                 goto out;
4017         }
4018
4019         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4020                (unsigned long long)rc->block_group->key.objectid,
4021                (unsigned long long)rc->block_group->flags);
4022
4023         btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
4024         btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
4025
4026         while (1) {
4027                 mutex_lock(&fs_info->cleaner_mutex);
4028
4029                 btrfs_clean_old_snapshots(fs_info->tree_root);
4030                 ret = relocate_block_group(rc);
4031
4032                 mutex_unlock(&fs_info->cleaner_mutex);
4033                 if (ret < 0) {
4034                         err = ret;
4035                         goto out;
4036                 }
4037
4038                 if (rc->extents_found == 0)
4039                         break;
4040
4041                 printk(KERN_INFO "btrfs: found %llu extents\n",
4042                         (unsigned long long)rc->extents_found);
4043
4044                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4045                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4046                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4047                                                  0, -1);
4048                         rc->stage = UPDATE_DATA_PTRS;
4049                 }
4050         }
4051
4052         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4053                                      rc->block_group->key.objectid,
4054                                      rc->block_group->key.objectid +
4055                                      rc->block_group->key.offset - 1);
4056
4057         WARN_ON(rc->block_group->pinned > 0);
4058         WARN_ON(rc->block_group->reserved > 0);
4059         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4060 out:
4061         if (err && rw)
4062                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4063         iput(rc->data_inode);
4064         btrfs_put_block_group(rc->block_group);
4065         kfree(rc);
4066         return err;
4067 }
4068
4069 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4070 {
4071         struct btrfs_trans_handle *trans;
4072         int ret;
4073
4074         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4075         BUG_ON(IS_ERR(trans));
4076
4077         memset(&root->root_item.drop_progress, 0,
4078                 sizeof(root->root_item.drop_progress));
4079         root->root_item.drop_level = 0;
4080         btrfs_set_root_refs(&root->root_item, 0);
4081         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4082                                 &root->root_key, &root->root_item);
4083         BUG_ON(ret);
4084
4085         ret = btrfs_end_transaction(trans, root->fs_info->tree_root);
4086         BUG_ON(ret);
4087         return 0;
4088 }
4089
4090 /*
4091  * recover relocation interrupted by system crash.
4092  *
4093  * this function resumes merging reloc trees with corresponding fs trees.
4094  * this is important for keeping the sharing of tree blocks
4095  */
4096 int btrfs_recover_relocation(struct btrfs_root *root)
4097 {
4098         LIST_HEAD(reloc_roots);
4099         struct btrfs_key key;
4100         struct btrfs_root *fs_root;
4101         struct btrfs_root *reloc_root;
4102         struct btrfs_path *path;
4103         struct extent_buffer *leaf;
4104         struct reloc_control *rc = NULL;
4105         struct btrfs_trans_handle *trans;
4106         int ret;
4107         int err = 0;
4108
4109         path = btrfs_alloc_path();
4110         if (!path)
4111                 return -ENOMEM;
4112         path->reada = -1;
4113
4114         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4115         key.type = BTRFS_ROOT_ITEM_KEY;
4116         key.offset = (u64)-1;
4117
4118         while (1) {
4119                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4120                                         path, 0, 0);
4121                 if (ret < 0) {
4122                         err = ret;
4123                         goto out;
4124                 }
4125                 if (ret > 0) {
4126                         if (path->slots[0] == 0)
4127                                 break;
4128                         path->slots[0]--;
4129                 }
4130                 leaf = path->nodes[0];
4131                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4132                 btrfs_release_path(path);
4133
4134                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4135                     key.type != BTRFS_ROOT_ITEM_KEY)
4136                         break;
4137
4138                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4139                 if (IS_ERR(reloc_root)) {
4140                         err = PTR_ERR(reloc_root);
4141                         goto out;
4142                 }
4143
4144                 list_add(&reloc_root->root_list, &reloc_roots);
4145
4146                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4147                         fs_root = read_fs_root(root->fs_info,
4148                                                reloc_root->root_key.offset);
4149                         if (IS_ERR(fs_root)) {
4150                                 ret = PTR_ERR(fs_root);
4151                                 if (ret != -ENOENT) {
4152                                         err = ret;
4153                                         goto out;
4154                                 }
4155                                 mark_garbage_root(reloc_root);
4156                         }
4157                 }
4158
4159                 if (key.offset == 0)
4160                         break;
4161
4162                 key.offset--;
4163         }
4164         btrfs_release_path(path);
4165
4166         if (list_empty(&reloc_roots))
4167                 goto out;
4168
4169         rc = alloc_reloc_control();
4170         if (!rc) {
4171                 err = -ENOMEM;
4172                 goto out;
4173         }
4174
4175         rc->extent_root = root->fs_info->extent_root;
4176
4177         set_reloc_control(rc);
4178
4179         trans = btrfs_join_transaction(rc->extent_root);
4180         if (IS_ERR(trans)) {
4181                 unset_reloc_control(rc);
4182                 err = PTR_ERR(trans);
4183                 goto out_free;
4184         }
4185
4186         rc->merge_reloc_tree = 1;
4187
4188         while (!list_empty(&reloc_roots)) {
4189                 reloc_root = list_entry(reloc_roots.next,
4190                                         struct btrfs_root, root_list);
4191                 list_del(&reloc_root->root_list);
4192
4193                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4194                         list_add_tail(&reloc_root->root_list,
4195                                       &rc->reloc_roots);
4196                         continue;
4197                 }
4198
4199                 fs_root = read_fs_root(root->fs_info,
4200                                        reloc_root->root_key.offset);
4201                 BUG_ON(IS_ERR(fs_root));
4202
4203                 __add_reloc_root(reloc_root);
4204                 fs_root->reloc_root = reloc_root;
4205         }
4206
4207         btrfs_commit_transaction(trans, rc->extent_root);
4208
4209         merge_reloc_roots(rc);
4210
4211         unset_reloc_control(rc);
4212
4213         trans = btrfs_join_transaction(rc->extent_root);
4214         if (IS_ERR(trans))
4215                 err = PTR_ERR(trans);
4216         else
4217                 btrfs_commit_transaction(trans, rc->extent_root);
4218 out_free:
4219         kfree(rc);
4220 out:
4221         while (!list_empty(&reloc_roots)) {
4222                 reloc_root = list_entry(reloc_roots.next,
4223                                         struct btrfs_root, root_list);
4224                 list_del(&reloc_root->root_list);
4225                 free_extent_buffer(reloc_root->node);
4226                 free_extent_buffer(reloc_root->commit_root);
4227                 kfree(reloc_root);
4228         }
4229         btrfs_free_path(path);
4230
4231         if (err == 0) {
4232                 /* cleanup orphan inode in data relocation tree */
4233                 fs_root = read_fs_root(root->fs_info,
4234                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4235                 if (IS_ERR(fs_root))
4236                         err = PTR_ERR(fs_root);
4237                 else
4238                         err = btrfs_orphan_cleanup(fs_root);
4239         }
4240         return err;
4241 }
4242
4243 /*
4244  * helper to add ordered checksum for data relocation.
4245  *
4246  * cloning checksum properly handles the nodatasum extents.
4247  * it also saves CPU time to re-calculate the checksum.
4248  */
4249 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4250 {
4251         struct btrfs_ordered_sum *sums;
4252         struct btrfs_sector_sum *sector_sum;
4253         struct btrfs_ordered_extent *ordered;
4254         struct btrfs_root *root = BTRFS_I(inode)->root;
4255         size_t offset;
4256         int ret;
4257         u64 disk_bytenr;
4258         LIST_HEAD(list);
4259
4260         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4261         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4262
4263         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4264         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4265                                        disk_bytenr + len - 1, &list, 0);
4266
4267         while (!list_empty(&list)) {
4268                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4269                 list_del_init(&sums->list);
4270
4271                 sector_sum = sums->sums;
4272                 sums->bytenr = ordered->start;
4273
4274                 offset = 0;
4275                 while (offset < sums->len) {
4276                         sector_sum->bytenr += ordered->start - disk_bytenr;
4277                         sector_sum++;
4278                         offset += root->sectorsize;
4279                 }
4280
4281                 btrfs_add_ordered_sum(inode, ordered, sums);
4282         }
4283         btrfs_put_ordered_extent(ordered);
4284         return ret;
4285 }
4286
4287 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4288                            struct btrfs_root *root, struct extent_buffer *buf,
4289                            struct extent_buffer *cow)
4290 {
4291         struct reloc_control *rc;
4292         struct backref_node *node;
4293         int first_cow = 0;
4294         int level;
4295         int ret;
4296
4297         rc = root->fs_info->reloc_ctl;
4298         if (!rc)
4299                 return;
4300
4301         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4302                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4303
4304         level = btrfs_header_level(buf);
4305         if (btrfs_header_generation(buf) <=
4306             btrfs_root_last_snapshot(&root->root_item))
4307                 first_cow = 1;
4308
4309         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4310             rc->create_reloc_tree) {
4311                 WARN_ON(!first_cow && level == 0);
4312
4313                 node = rc->backref_cache.path[level];
4314                 BUG_ON(node->bytenr != buf->start &&
4315                        node->new_bytenr != buf->start);
4316
4317                 drop_node_buffer(node);
4318                 extent_buffer_get(cow);
4319                 node->eb = cow;
4320                 node->new_bytenr = cow->start;
4321
4322                 if (!node->pending) {
4323                         list_move_tail(&node->list,
4324                                        &rc->backref_cache.pending[level]);
4325                         node->pending = 1;
4326                 }
4327
4328                 if (first_cow)
4329                         __mark_block_processed(rc, node);
4330
4331                 if (first_cow && level > 0)
4332                         rc->nodes_relocated += buf->len;
4333         }
4334
4335         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4336                 ret = replace_file_extents(trans, rc, root, cow);
4337                 BUG_ON(ret);
4338         }
4339 }
4340
4341 /*
4342  * called before creating snapshot. it calculates metadata reservation
4343  * requried for relocating tree blocks in the snapshot
4344  */
4345 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4346                               struct btrfs_pending_snapshot *pending,
4347                               u64 *bytes_to_reserve)
4348 {
4349         struct btrfs_root *root;
4350         struct reloc_control *rc;
4351
4352         root = pending->root;
4353         if (!root->reloc_root)
4354                 return;
4355
4356         rc = root->fs_info->reloc_ctl;
4357         if (!rc->merge_reloc_tree)
4358                 return;
4359
4360         root = root->reloc_root;
4361         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4362         /*
4363          * relocation is in the stage of merging trees. the space
4364          * used by merging a reloc tree is twice the size of
4365          * relocated tree nodes in the worst case. half for cowing
4366          * the reloc tree, half for cowing the fs tree. the space
4367          * used by cowing the reloc tree will be freed after the
4368          * tree is dropped. if we create snapshot, cowing the fs
4369          * tree may use more space than it frees. so we need
4370          * reserve extra space.
4371          */
4372         *bytes_to_reserve += rc->nodes_relocated;
4373 }
4374
4375 /*
4376  * called after snapshot is created. migrate block reservation
4377  * and create reloc root for the newly created snapshot
4378  */
4379 void btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4380                                struct btrfs_pending_snapshot *pending)
4381 {
4382         struct btrfs_root *root = pending->root;
4383         struct btrfs_root *reloc_root;
4384         struct btrfs_root *new_root;
4385         struct reloc_control *rc;
4386         int ret;
4387
4388         if (!root->reloc_root)
4389                 return;
4390
4391         rc = root->fs_info->reloc_ctl;
4392         rc->merging_rsv_size += rc->nodes_relocated;
4393
4394         if (rc->merge_reloc_tree) {
4395                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4396                                               rc->block_rsv,
4397                                               rc->nodes_relocated);
4398                 BUG_ON(ret);
4399         }
4400
4401         new_root = pending->snap;
4402         reloc_root = create_reloc_root(trans, root->reloc_root,
4403                                        new_root->root_key.objectid);
4404
4405         __add_reloc_root(reloc_root);
4406         new_root->reloc_root = reloc_root;
4407
4408         if (rc->create_reloc_tree) {
4409                 ret = clone_backref_node(trans, rc, root, reloc_root);
4410                 BUG_ON(ret);
4411         }
4412 }