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