fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97
  98 struct backref_cache {
  99         /* red black tree of all backref nodes in the cache */
 100         struct rb_root rb_root;
 101         /* for passing backref nodes to btrfs_reloc_cow_block */
 102         struct backref_node *path[BTRFS_MAX_LEVEL];
 103         /*
 104          * list of blocks that have been cowed but some block
 105          * pointers in upper level blocks may not reflect the
 106          * new location
 107          */
 108         struct list_head pending[BTRFS_MAX_LEVEL];
 109         /* list of backref nodes with no child node */
 110         struct list_head leaves;
 111         /* list of blocks that have been cowed in current transaction */
 112         struct list_head changed;
 113         /* list of detached backref node. */
 114         struct list_head detached;
 115
 116         u64 last_trans;
 117
 118         int nr_nodes;
 119         int nr_edges;
 120 };
 121
 122 /*
 123  * map address of tree root to tree
 124  */
 125 struct mapping_node {
 126         struct rb_node rb_node;
 127         u64 bytenr;
 128         void *data;
 129 };
 130
 131 struct mapping_tree {
 132         struct rb_root rb_root;
 133         spinlock_t lock;
 134 };
 135
 136 /*
 137  * present a tree block to process
 138  */
 139 struct tree_block {
 140         struct rb_node rb_node;
 141         u64 bytenr;
 142         struct btrfs_key key;
 143         unsigned int level:8;
 144         unsigned int key_ready:1;
 145 };
 146
 147 #define MAX_EXTENTS 128
 148
 149 struct file_extent_cluster {
 150         u64 start;
 151         u64 end;
 152         u64 boundary[MAX_EXTENTS];
 153         unsigned int nr;
 154 };
 155
 156 struct reloc_control {
 157         /* block group to relocate */
 158         struct btrfs_block_group_cache *block_group;
 159         /* extent tree */
 160         struct btrfs_root *extent_root;
 161         /* inode for moving data */
 162         struct inode *data_inode;
 163
 164         struct btrfs_block_rsv *block_rsv;
 165
 166         struct backref_cache backref_cache;
 167
 168         struct file_extent_cluster cluster;
 169         /* tree blocks have been processed */
 170         struct extent_io_tree processed_blocks;
 171         /* map start of tree root to corresponding reloc tree */
 172         struct mapping_tree reloc_root_tree;
 173         /* list of reloc trees */
 174         struct list_head reloc_roots;
 175         /* size of metadata reservation for merging reloc trees */
 176         u64 merging_rsv_size;
 177         /* size of relocated tree nodes */
 178         u64 nodes_relocated;
 179
 180         u64 search_start;
 181         u64 extents_found;
 182
 183         unsigned int stage:8;
 184         unsigned int create_reloc_tree:1;
 185         unsigned int merge_reloc_tree:1;
 186         unsigned int found_file_extent:1;
 187         unsigned int commit_transaction:1;
 188 };
 189
 190 /* stages of data relocation */
 191 #define MOVE_DATA_EXTENTS       0
 192 #define UPDATE_DATA_PTRS        1
 193
 194 static void remove_backref_node(struct backref_cache *cache,
 195                                 struct backref_node *node);
 196 static void __mark_block_processed(struct reloc_control *rc,
 197                                    struct backref_node *node);
 198
 199 static void mapping_tree_init(struct mapping_tree *tree)
 200 {
 201         tree->rb_root = RB_ROOT;
 202         spin_lock_init(&tree->lock);
 203 }
 204
 205 static void backref_cache_init(struct backref_cache *cache)
 206 {
 207         int i;
 208         cache->rb_root = RB_ROOT;
 209         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 210                 INIT_LIST_HEAD(&cache->pending[i]);
 211         INIT_LIST_HEAD(&cache->changed);
 212         INIT_LIST_HEAD(&cache->detached);
 213         INIT_LIST_HEAD(&cache->leaves);
 214 }
 215
 216 static void backref_cache_cleanup(struct backref_cache *cache)
 217 {
 218         struct backref_node *node;
 219         int i;
 220
 221         while (!list_empty(&cache->detached)) {
 222                 node = list_entry(cache->detached.next,
 223                                   struct backref_node, list);
 224                 remove_backref_node(cache, node);
 225         }
 226
 227         while (!list_empty(&cache->leaves)) {
 228                 node = list_entry(cache->leaves.next,
 229                                   struct backref_node, lower);
 230                 remove_backref_node(cache, node);
 231         }
 232
 233         cache->last_trans = 0;
 234
 235         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 236                 BUG_ON(!list_empty(&cache->pending[i]));
 237         BUG_ON(!list_empty(&cache->changed));
 238         BUG_ON(!list_empty(&cache->detached));
 239         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 240         BUG_ON(cache->nr_nodes);
 241         BUG_ON(cache->nr_edges);
 242 }
 243
 244 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 245 {
 246         struct backref_node *node;
 247
 248         node = kzalloc(sizeof(*node), GFP_NOFS);
 249         if (node) {
 250                 INIT_LIST_HEAD(&node->list);
 251                 INIT_LIST_HEAD(&node->upper);
 252                 INIT_LIST_HEAD(&node->lower);
 253                 RB_CLEAR_NODE(&node->rb_node);
 254                 cache->nr_nodes++;
 255         }
 256         return node;
 257 }
 258
 259 static void free_backref_node(struct backref_cache *cache,
 260                               struct backref_node *node)
 261 {
 262         if (node) {
 263                 cache->nr_nodes--;
 264                 kfree(node);
 265         }
 266 }
 267
 268 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 269 {
 270         struct backref_edge *edge;
 271
 272         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 273         if (edge)
 274                 cache->nr_edges++;
 275         return edge;
 276 }
 277
 278 static void free_backref_edge(struct backref_cache *cache,
 279                               struct backref_edge *edge)
 280 {
 281         if (edge) {
 282                 cache->nr_edges--;
 283                 kfree(edge);
 284         }
 285 }
 286
 287 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 288                                    struct rb_node *node)
 289 {
 290         struct rb_node **p = &root->rb_node;
 291         struct rb_node *parent = NULL;
 292         struct tree_entry *entry;
 293
 294         while (*p) {
 295                 parent = *p;
 296                 entry = rb_entry(parent, struct tree_entry, rb_node);
 297
 298                 if (bytenr < entry->bytenr)
 299                         p = &(*p)->rb_left;
 300                 else if (bytenr > entry->bytenr)
 301                         p = &(*p)->rb_right;
 302                 else
 303                         return parent;
 304         }
 305
 306         rb_link_node(node, parent, p);
 307         rb_insert_color(node, root);
 308         return NULL;
 309 }
 310
 311 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 312 {
 313         struct rb_node *n = root->rb_node;
 314         struct tree_entry *entry;
 315
 316         while (n) {
 317                 entry = rb_entry(n, struct tree_entry, rb_node);
 318
 319                 if (bytenr < entry->bytenr)
 320                         n = n->rb_left;
 321                 else if (bytenr > entry->bytenr)
 322                         n = n->rb_right;
 323                 else
 324                         return n;
 325         }
 326         return NULL;
 327 }
 328
 329 void backref_tree_panic(struct rb_node *rb_node, int errno,
 330                                           u64 bytenr)
 331 {
 332
 333         struct btrfs_fs_info *fs_info = NULL;
 334         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 335                                               rb_node);
 336         if (bnode->root)
 337                 fs_info = bnode->root->fs_info;
 338         btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 339                     "found at offset %llu\n", (unsigned long long)bytenr);
 340 }
 341
 342 /*
 343  * walk up backref nodes until reach node presents tree root
 344  */
 345 static struct backref_node *walk_up_backref(struct backref_node *node,
 346                                             struct backref_edge *edges[],
 347                                             int *index)
 348 {
 349         struct backref_edge *edge;
 350         int idx = *index;
 351
 352         while (!list_empty(&node->upper)) {
 353                 edge = list_entry(node->upper.next,
 354                                   struct backref_edge, list[LOWER]);
 355                 edges[idx++] = edge;
 356                 node = edge->node[UPPER];
 357         }
 358         BUG_ON(node->detached);
 359         *index = idx;
 360         return node;
 361 }
 362
 363 /*
 364  * walk down backref nodes to find start of next reference path
 365  */
 366 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 367                                               int *index)
 368 {
 369         struct backref_edge *edge;
 370         struct backref_node *lower;
 371         int idx = *index;
 372
 373         while (idx > 0) {
 374                 edge = edges[idx - 1];
 375                 lower = edge->node[LOWER];
 376                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 377                         idx--;
 378                         continue;
 379                 }
 380                 edge = list_entry(edge->list[LOWER].next,
 381                                   struct backref_edge, list[LOWER]);
 382                 edges[idx - 1] = edge;
 383                 *index = idx;
 384                 return edge->node[UPPER];
 385         }
 386         *index = 0;
 387         return NULL;
 388 }
 389
 390 static void unlock_node_buffer(struct backref_node *node)
 391 {
 392         if (node->locked) {
 393                 btrfs_tree_unlock(node->eb);
 394                 node->locked = 0;
 395         }
 396 }
 397
 398 static void drop_node_buffer(struct backref_node *node)
 399 {
 400         if (node->eb) {
 401                 unlock_node_buffer(node);
 402                 free_extent_buffer(node->eb);
 403                 node->eb = NULL;
 404         }
 405 }
 406
 407 static void drop_backref_node(struct backref_cache *tree,
 408                               struct backref_node *node)
 409 {
 410         BUG_ON(!list_empty(&node->upper));
 411
 412         drop_node_buffer(node);
 413         list_del(&node->list);
 414         list_del(&node->lower);
 415         if (!RB_EMPTY_NODE(&node->rb_node))
 416                 rb_erase(&node->rb_node, &tree->rb_root);
 417         free_backref_node(tree, node);
 418 }
 419
 420 /*
 421  * remove a backref node from the backref cache
 422  */
 423 static void remove_backref_node(struct backref_cache *cache,
 424                                 struct backref_node *node)
 425 {
 426         struct backref_node *upper;
 427         struct backref_edge *edge;
 428
 429         if (!node)
 430                 return;
 431
 432         BUG_ON(!node->lowest && !node->detached);
 433         while (!list_empty(&node->upper)) {
 434                 edge = list_entry(node->upper.next, struct backref_edge,
 435                                   list[LOWER]);
 436                 upper = edge->node[UPPER];
 437                 list_del(&edge->list[LOWER]);
 438                 list_del(&edge->list[UPPER]);
 439                 free_backref_edge(cache, edge);
 440
 441                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 442                         BUG_ON(!list_empty(&node->upper));
 443                         drop_backref_node(cache, node);
 444                         node = upper;
 445                         node->lowest = 1;
 446                         continue;
 447                 }
 448                 /*
 449                  * add the node to leaf node list if no other
 450                  * child block cached.
 451                  */
 452                 if (list_empty(&upper->lower)) {
 453                         list_add_tail(&upper->lower, &cache->leaves);
 454                         upper->lowest = 1;
 455                 }
 456         }
 457
 458         drop_backref_node(cache, node);
 459 }
 460
 461 static void update_backref_node(struct backref_cache *cache,
 462                                 struct backref_node *node, u64 bytenr)
 463 {
 464         struct rb_node *rb_node;
 465         rb_erase(&node->rb_node, &cache->rb_root);
 466         node->bytenr = bytenr;
 467         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 468         if (rb_node)
 469                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 470 }
 471
 472 /*
 473  * update backref cache after a transaction commit
 474  */
 475 static int update_backref_cache(struct btrfs_trans_handle *trans,
 476                                 struct backref_cache *cache)
 477 {
 478         struct backref_node *node;
 479         int level = 0;
 480
 481         if (cache->last_trans == 0) {
 482                 cache->last_trans = trans->transid;
 483                 return 0;
 484         }
 485
 486         if (cache->last_trans == trans->transid)
 487                 return 0;
 488
 489         /*
 490          * detached nodes are used to avoid unnecessary backref
 491          * lookup. transaction commit changes the extent tree.
 492          * so the detached nodes are no longer useful.
 493          */
 494         while (!list_empty(&cache->detached)) {
 495                 node = list_entry(cache->detached.next,
 496                                   struct backref_node, list);
 497                 remove_backref_node(cache, node);
 498         }
 499
 500         while (!list_empty(&cache->changed)) {
 501                 node = list_entry(cache->changed.next,
 502                                   struct backref_node, list);
 503                 list_del_init(&node->list);
 504                 BUG_ON(node->pending);
 505                 update_backref_node(cache, node, node->new_bytenr);
 506         }
 507
 508         /*
 509          * some nodes can be left in the pending list if there were
 510          * errors during processing the pending nodes.
 511          */
 512         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 513                 list_for_each_entry(node, &cache->pending[level], list) {
 514                         BUG_ON(!node->pending);
 515                         if (node->bytenr == node->new_bytenr)
 516                                 continue;
 517                         update_backref_node(cache, node, node->new_bytenr);
 518                 }
 519         }
 520
 521         cache->last_trans = 0;
 522         return 1;
 523 }
 524
 525
 526 static int should_ignore_root(struct btrfs_root *root)
 527 {
 528         struct btrfs_root *reloc_root;
 529
 530         if (!root->ref_cows)
 531                 return 0;
 532
 533         reloc_root = root->reloc_root;
 534         if (!reloc_root)
 535                 return 0;
 536
 537         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 538             root->fs_info->running_transaction->transid - 1)
 539                 return 0;
 540         /*
 541          * if there is reloc tree and it was created in previous
 542          * transaction backref lookup can find the reloc tree,
 543          * so backref node for the fs tree root is useless for
 544          * relocation.
 545          */
 546         return 1;
 547 }
 548 /*
 549  * find reloc tree by address of tree root
 550  */
 551 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 552                                           u64 bytenr)
 553 {
 554         struct rb_node *rb_node;
 555         struct mapping_node *node;
 556         struct btrfs_root *root = NULL;
 557
 558         spin_lock(&rc->reloc_root_tree.lock);
 559         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 560         if (rb_node) {
 561                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 562                 root = (struct btrfs_root *)node->data;
 563         }
 564         spin_unlock(&rc->reloc_root_tree.lock);
 565         return root;
 566 }
 567
 568 static int is_cowonly_root(u64 root_objectid)
 569 {
 570         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 571             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 572             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 573             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 574             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 575             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
 576                 return 1;
 577         return 0;
 578 }
 579
 580 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 581                                         u64 root_objectid)
 582 {
 583         struct btrfs_key key;
 584
 585         key.objectid = root_objectid;
 586         key.type = BTRFS_ROOT_ITEM_KEY;
 587         if (is_cowonly_root(root_objectid))
 588                 key.offset = 0;
 589         else
 590                 key.offset = (u64)-1;
 591
 592         return btrfs_read_fs_root_no_name(fs_info, &key);
 593 }
 594
 595 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 596 static noinline_for_stack
 597 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 598                                   struct extent_buffer *leaf,
 599                                   struct btrfs_extent_ref_v0 *ref0)
 600 {
 601         struct btrfs_root *root;
 602         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 603         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 604
 605         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 606
 607         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 608         BUG_ON(IS_ERR(root));
 609
 610         if (root->ref_cows &&
 611             generation != btrfs_root_generation(&root->root_item))
 612                 return NULL;
 613
 614         return root;
 615 }
 616 #endif
 617
 618 static noinline_for_stack
 619 int find_inline_backref(struct extent_buffer *leaf, int slot,
 620                         unsigned long *ptr, unsigned long *end)
 621 {
 622         struct btrfs_extent_item *ei;
 623         struct btrfs_tree_block_info *bi;
 624         u32 item_size;
 625
 626         item_size = btrfs_item_size_nr(leaf, slot);
 627 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 628         if (item_size < sizeof(*ei)) {
 629                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 630                 return 1;
 631         }
 632 #endif
 633         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 634         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 635                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 636
 637         if (item_size <= sizeof(*ei) + sizeof(*bi)) {
 638                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 639                 return 1;
 640         }
 641
 642         bi = (struct btrfs_tree_block_info *)(ei + 1);
 643         *ptr = (unsigned long)(bi + 1);
 644         *end = (unsigned long)ei + item_size;
 645         return 0;
 646 }
 647
 648 /*
 649  * build backref tree for a given tree block. root of the backref tree
 650  * corresponds the tree block, leaves of the backref tree correspond
 651  * roots of b-trees that reference the tree block.
 652  *
 653  * the basic idea of this function is check backrefs of a given block
 654  * to find upper level blocks that refernece the block, and then check
 655  * bakcrefs of these upper level blocks recursively. the recursion stop
 656  * when tree root is reached or backrefs for the block is cached.
 657  *
 658  * NOTE: if we find backrefs for a block are cached, we know backrefs
 659  * for all upper level blocks that directly/indirectly reference the
 660  * block are also cached.
 661  */
 662 static noinline_for_stack
 663 struct backref_node *build_backref_tree(struct reloc_control *rc,
 664                                         struct btrfs_key *node_key,
 665                                         int level, u64 bytenr)
 666 {
 667         struct backref_cache *cache = &rc->backref_cache;
 668         struct btrfs_path *path1;
 669         struct btrfs_path *path2;
 670         struct extent_buffer *eb;
 671         struct btrfs_root *root;
 672         struct backref_node *cur;
 673         struct backref_node *upper;
 674         struct backref_node *lower;
 675         struct backref_node *node = NULL;
 676         struct backref_node *exist = NULL;
 677         struct backref_edge *edge;
 678         struct rb_node *rb_node;
 679         struct btrfs_key key;
 680         unsigned long end;
 681         unsigned long ptr;
 682         LIST_HEAD(list);
 683         LIST_HEAD(useless);
 684         int cowonly;
 685         int ret;
 686         int err = 0;
 687
 688         path1 = btrfs_alloc_path();
 689         path2 = btrfs_alloc_path();
 690         if (!path1 || !path2) {
 691                 err = -ENOMEM;
 692                 goto out;
 693         }
 694         path1->reada = 1;
 695         path2->reada = 2;
 696
 697         node = alloc_backref_node(cache);
 698         if (!node) {
 699                 err = -ENOMEM;
 700                 goto out;
 701         }
 702
 703         node->bytenr = bytenr;
 704         node->level = level;
 705         node->lowest = 1;
 706         cur = node;
 707 again:
 708         end = 0;
 709         ptr = 0;
 710         key.objectid = cur->bytenr;
 711         key.type = BTRFS_EXTENT_ITEM_KEY;
 712         key.offset = (u64)-1;
 713
 714         path1->search_commit_root = 1;
 715         path1->skip_locking = 1;
 716         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 717                                 0, 0);
 718         if (ret < 0) {
 719                 err = ret;
 720                 goto out;
 721         }
 722         BUG_ON(!ret || !path1->slots[0]);
 723
 724         path1->slots[0]--;
 725
 726         WARN_ON(cur->checked);
 727         if (!list_empty(&cur->upper)) {
 728                 /*
 729                  * the backref was added previously when processing
 730                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 731                  */
 732                 BUG_ON(!list_is_singular(&cur->upper));
 733                 edge = list_entry(cur->upper.next, struct backref_edge,
 734                                   list[LOWER]);
 735                 BUG_ON(!list_empty(&edge->list[UPPER]));
 736                 exist = edge->node[UPPER];
 737                 /*
 738                  * add the upper level block to pending list if we need
 739                  * check its backrefs
 740                  */
 741                 if (!exist->checked)
 742                         list_add_tail(&edge->list[UPPER], &list);
 743         } else {
 744                 exist = NULL;
 745         }
 746
 747         while (1) {
 748                 cond_resched();
 749                 eb = path1->nodes[0];
 750
 751                 if (ptr >= end) {
 752                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 753                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 754                                 if (ret < 0) {
 755                                         err = ret;
 756                                         goto out;
 757                                 }
 758                                 if (ret > 0)
 759                                         break;
 760                                 eb = path1->nodes[0];
 761                         }
 762
 763                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 764                         if (key.objectid != cur->bytenr) {
 765                                 WARN_ON(exist);
 766                                 break;
 767                         }
 768
 769                         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 770                                 ret = find_inline_backref(eb, path1->slots[0],
 771                                                           &ptr, &end);
 772                                 if (ret)
 773                                         goto next;
 774                         }
 775                 }
 776
 777                 if (ptr < end) {
 778                         /* update key for inline back ref */
 779                         struct btrfs_extent_inline_ref *iref;
 780                         iref = (struct btrfs_extent_inline_ref *)ptr;
 781                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 782                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 783                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 784                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 785                 }
 786
 787                 if (exist &&
 788                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 789                       exist->owner == key.offset) ||
 790                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 791                       exist->bytenr == key.offset))) {
 792                         exist = NULL;
 793                         goto next;
 794                 }
 795
 796 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 797                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 798                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 799                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 800                                 struct btrfs_extent_ref_v0 *ref0;
 801                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 802                                                 struct btrfs_extent_ref_v0);
 803                                 if (key.objectid == key.offset) {
 804                                         root = find_tree_root(rc, eb, ref0);
 805                                         if (root && !should_ignore_root(root))
 806                                                 cur->root = root;
 807                                         else
 808                                                 list_add(&cur->list, &useless);
 809                                         break;
 810                                 }
 811                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 812                                                                       ref0)))
 813                                         cur->cowonly = 1;
 814                         }
 815 #else
 816                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 817                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 818 #endif
 819                         if (key.objectid == key.offset) {
 820                                 /*
 821                                  * only root blocks of reloc trees use
 822                                  * backref of this type.
 823                                  */
 824                                 root = find_reloc_root(rc, cur->bytenr);
 825                                 BUG_ON(!root);
 826                                 cur->root = root;
 827                                 break;
 828                         }
 829
 830                         edge = alloc_backref_edge(cache);
 831                         if (!edge) {
 832                                 err = -ENOMEM;
 833                                 goto out;
 834                         }
 835                         rb_node = tree_search(&cache->rb_root, key.offset);
 836                         if (!rb_node) {
 837                                 upper = alloc_backref_node(cache);
 838                                 if (!upper) {
 839                                         free_backref_edge(cache, edge);
 840                                         err = -ENOMEM;
 841                                         goto out;
 842                                 }
 843                                 upper->bytenr = key.offset;
 844                                 upper->level = cur->level + 1;
 845                                 /*
 846                                  *  backrefs for the upper level block isn't
 847                                  *  cached, add the block to pending list
 848                                  */
 849                                 list_add_tail(&edge->list[UPPER], &list);
 850                         } else {
 851                                 upper = rb_entry(rb_node, struct backref_node,
 852                                                  rb_node);
 853                                 BUG_ON(!upper->checked);
 854                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 855                         }
 856                         list_add_tail(&edge->list[LOWER], &cur->upper);
 857                         edge->node[LOWER] = cur;
 858                         edge->node[UPPER] = upper;
 859
 860                         goto next;
 861                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 862                         goto next;
 863                 }
 864
 865                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 866                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 867                 if (IS_ERR(root)) {
 868                         err = PTR_ERR(root);
 869                         goto out;
 870                 }
 871
 872                 if (!root->ref_cows)
 873                         cur->cowonly = 1;
 874
 875                 if (btrfs_root_level(&root->root_item) == cur->level) {
 876                         /* tree root */
 877                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 878                                cur->bytenr);
 879                         if (should_ignore_root(root))
 880                                 list_add(&cur->list, &useless);
 881                         else
 882                                 cur->root = root;
 883                         break;
 884                 }
 885
 886                 level = cur->level + 1;
 887
 888                 /*
 889                  * searching the tree to find upper level blocks
 890                  * reference the block.
 891                  */
 892                 path2->search_commit_root = 1;
 893                 path2->skip_locking = 1;
 894                 path2->lowest_level = level;
 895                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 896                 path2->lowest_level = 0;
 897                 if (ret < 0) {
 898                         err = ret;
 899                         goto out;
 900                 }
 901                 if (ret > 0 && path2->slots[level] > 0)
 902                         path2->slots[level]--;
 903
 904                 eb = path2->nodes[level];
 905                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 906                         cur->bytenr);
 907
 908                 lower = cur;
 909                 for (; level < BTRFS_MAX_LEVEL; level++) {
 910                         if (!path2->nodes[level]) {
 911                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 912                                        lower->bytenr);
 913                                 if (should_ignore_root(root))
 914                                         list_add(&lower->list, &useless);
 915                                 else
 916                                         lower->root = root;
 917                                 break;
 918                         }
 919
 920                         edge = alloc_backref_edge(cache);
 921                         if (!edge) {
 922                                 err = -ENOMEM;
 923                                 goto out;
 924                         }
 925
 926                         eb = path2->nodes[level];
 927                         rb_node = tree_search(&cache->rb_root, eb->start);
 928                         if (!rb_node) {
 929                                 upper = alloc_backref_node(cache);
 930                                 if (!upper) {
 931                                         free_backref_edge(cache, edge);
 932                                         err = -ENOMEM;
 933                                         goto out;
 934                                 }
 935                                 upper->bytenr = eb->start;
 936                                 upper->owner = btrfs_header_owner(eb);
 937                                 upper->level = lower->level + 1;
 938                                 if (!root->ref_cows)
 939                                         upper->cowonly = 1;
 940
 941                                 /*
 942                                  * if we know the block isn't shared
 943                                  * we can void checking its backrefs.
 944                                  */
 945                                 if (btrfs_block_can_be_shared(root, eb))
 946                                         upper->checked = 0;
 947                                 else
 948                                         upper->checked = 1;
 949
 950                                 /*
 951                                  * add the block to pending list if we
 952                                  * need check its backrefs. only block
 953                                  * at 'cur->level + 1' is added to the
 954                                  * tail of pending list. this guarantees
 955                                  * we check backrefs from lower level
 956                                  * blocks to upper level blocks.
 957                                  */
 958                                 if (!upper->checked &&
 959                                     level == cur->level + 1) {
 960                                         list_add_tail(&edge->list[UPPER],
 961                                                       &list);
 962                                 } else
 963                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 964                         } else {
 965                                 upper = rb_entry(rb_node, struct backref_node,
 966                                                  rb_node);
 967                                 BUG_ON(!upper->checked);
 968                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 969                                 if (!upper->owner)
 970                                         upper->owner = btrfs_header_owner(eb);
 971                         }
 972                         list_add_tail(&edge->list[LOWER], &lower->upper);
 973                         edge->node[LOWER] = lower;
 974                         edge->node[UPPER] = upper;
 975
 976                         if (rb_node)
 977                                 break;
 978                         lower = upper;
 979                         upper = NULL;
 980                 }
 981                 btrfs_release_path(path2);
 982 next:
 983                 if (ptr < end) {
 984                         ptr += btrfs_extent_inline_ref_size(key.type);
 985                         if (ptr >= end) {
 986                                 WARN_ON(ptr > end);
 987                                 ptr = 0;
 988                                 end = 0;
 989                         }
 990                 }
 991                 if (ptr >= end)
 992                         path1->slots[0]++;
 993         }
 994         btrfs_release_path(path1);
 995
 996         cur->checked = 1;
 997         WARN_ON(exist);
 998
 999         /* the pending list isn't empty, take the first block to process */
1000         if (!list_empty(&list)) {
1001                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1002                 list_del_init(&edge->list[UPPER]);
1003                 cur = edge->node[UPPER];
1004                 goto again;
1005         }
1006
1007         /*
1008          * everything goes well, connect backref nodes and insert backref nodes
1009          * into the cache.
1010          */
1011         BUG_ON(!node->checked);
1012         cowonly = node->cowonly;
1013         if (!cowonly) {
1014                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1015                                       &node->rb_node);
1016                 if (rb_node)
1017                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1018                 list_add_tail(&node->lower, &cache->leaves);
1019         }
1020
1021         list_for_each_entry(edge, &node->upper, list[LOWER])
1022                 list_add_tail(&edge->list[UPPER], &list);
1023
1024         while (!list_empty(&list)) {
1025                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1026                 list_del_init(&edge->list[UPPER]);
1027                 upper = edge->node[UPPER];
1028                 if (upper->detached) {
1029                         list_del(&edge->list[LOWER]);
1030                         lower = edge->node[LOWER];
1031                         free_backref_edge(cache, edge);
1032                         if (list_empty(&lower->upper))
1033                                 list_add(&lower->list, &useless);
1034                         continue;
1035                 }
1036
1037                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1038                         if (upper->lowest) {
1039                                 list_del_init(&upper->lower);
1040                                 upper->lowest = 0;
1041                         }
1042
1043                         list_add_tail(&edge->list[UPPER], &upper->lower);
1044                         continue;
1045                 }
1046
1047                 BUG_ON(!upper->checked);
1048                 BUG_ON(cowonly != upper->cowonly);
1049                 if (!cowonly) {
1050                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1051                                               &upper->rb_node);
1052                         if (rb_node)
1053                                 backref_tree_panic(rb_node, -EEXIST,
1054                                                    upper->bytenr);
1055                 }
1056
1057                 list_add_tail(&edge->list[UPPER], &upper->lower);
1058
1059                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1060                         list_add_tail(&edge->list[UPPER], &list);
1061         }
1062         /*
1063          * process useless backref nodes. backref nodes for tree leaves
1064          * are deleted from the cache. backref nodes for upper level
1065          * tree blocks are left in the cache to avoid unnecessary backref
1066          * lookup.
1067          */
1068         while (!list_empty(&useless)) {
1069                 upper = list_entry(useless.next, struct backref_node, list);
1070                 list_del_init(&upper->list);
1071                 BUG_ON(!list_empty(&upper->upper));
1072                 if (upper == node)
1073                         node = NULL;
1074                 if (upper->lowest) {
1075                         list_del_init(&upper->lower);
1076                         upper->lowest = 0;
1077                 }
1078                 while (!list_empty(&upper->lower)) {
1079                         edge = list_entry(upper->lower.next,
1080                                           struct backref_edge, list[UPPER]);
1081                         list_del(&edge->list[UPPER]);
1082                         list_del(&edge->list[LOWER]);
1083                         lower = edge->node[LOWER];
1084                         free_backref_edge(cache, edge);
1085
1086                         if (list_empty(&lower->upper))
1087                                 list_add(&lower->list, &useless);
1088                 }
1089                 __mark_block_processed(rc, upper);
1090                 if (upper->level > 0) {
1091                         list_add(&upper->list, &cache->detached);
1092                         upper->detached = 1;
1093                 } else {
1094                         rb_erase(&upper->rb_node, &cache->rb_root);
1095                         free_backref_node(cache, upper);
1096                 }
1097         }
1098 out:
1099         btrfs_free_path(path1);
1100         btrfs_free_path(path2);
1101         if (err) {
1102                 while (!list_empty(&useless)) {
1103                         lower = list_entry(useless.next,
1104                                            struct backref_node, upper);
1105                         list_del_init(&lower->upper);
1106                 }
1107                 upper = node;
1108                 INIT_LIST_HEAD(&list);
1109                 while (upper) {
1110                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1111                                 list_splice_tail(&upper->upper, &list);
1112                                 free_backref_node(cache, upper);
1113                         }
1114
1115                         if (list_empty(&list))
1116                                 break;
1117
1118                         edge = list_entry(list.next, struct backref_edge,
1119                                           list[LOWER]);
1120                         list_del(&edge->list[LOWER]);
1121                         upper = edge->node[UPPER];
1122                         free_backref_edge(cache, edge);
1123                 }
1124                 return ERR_PTR(err);
1125         }
1126         BUG_ON(node && node->detached);
1127         return node;
1128 }
1129
1130 /*
1131  * helper to add backref node for the newly created snapshot.
1132  * the backref node is created by cloning backref node that
1133  * corresponds to root of source tree
1134  */
1135 static int clone_backref_node(struct btrfs_trans_handle *trans,
1136                               struct reloc_control *rc,
1137                               struct btrfs_root *src,
1138                               struct btrfs_root *dest)
1139 {
1140         struct btrfs_root *reloc_root = src->reloc_root;
1141         struct backref_cache *cache = &rc->backref_cache;
1142         struct backref_node *node = NULL;
1143         struct backref_node *new_node;
1144         struct backref_edge *edge;
1145         struct backref_edge *new_edge;
1146         struct rb_node *rb_node;
1147
1148         if (cache->last_trans > 0)
1149                 update_backref_cache(trans, cache);
1150
1151         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1152         if (rb_node) {
1153                 node = rb_entry(rb_node, struct backref_node, rb_node);
1154                 if (node->detached)
1155                         node = NULL;
1156                 else
1157                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1158         }
1159
1160         if (!node) {
1161                 rb_node = tree_search(&cache->rb_root,
1162                                       reloc_root->commit_root->start);
1163                 if (rb_node) {
1164                         node = rb_entry(rb_node, struct backref_node,
1165                                         rb_node);
1166                         BUG_ON(node->detached);
1167                 }
1168         }
1169
1170         if (!node)
1171                 return 0;
1172
1173         new_node = alloc_backref_node(cache);
1174         if (!new_node)
1175                 return -ENOMEM;
1176
1177         new_node->bytenr = dest->node->start;
1178         new_node->level = node->level;
1179         new_node->lowest = node->lowest;
1180         new_node->checked = 1;
1181         new_node->root = dest;
1182
1183         if (!node->lowest) {
1184                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1185                         new_edge = alloc_backref_edge(cache);
1186                         if (!new_edge)
1187                                 goto fail;
1188
1189                         new_edge->node[UPPER] = new_node;
1190                         new_edge->node[LOWER] = edge->node[LOWER];
1191                         list_add_tail(&new_edge->list[UPPER],
1192                                       &new_node->lower);
1193                 }
1194         } else {
1195                 list_add_tail(&new_node->lower, &cache->leaves);
1196         }
1197
1198         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1199                               &new_node->rb_node);
1200         if (rb_node)
1201                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1202
1203         if (!new_node->lowest) {
1204                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1205                         list_add_tail(&new_edge->list[LOWER],
1206                                       &new_edge->node[LOWER]->upper);
1207                 }
1208         }
1209         return 0;
1210 fail:
1211         while (!list_empty(&new_node->lower)) {
1212                 new_edge = list_entry(new_node->lower.next,
1213                                       struct backref_edge, list[UPPER]);
1214                 list_del(&new_edge->list[UPPER]);
1215                 free_backref_edge(cache, new_edge);
1216         }
1217         free_backref_node(cache, new_node);
1218         return -ENOMEM;
1219 }
1220
1221 /*
1222  * helper to add 'address of tree root -> reloc tree' mapping
1223  */
1224 static int __must_check __add_reloc_root(struct btrfs_root *root)
1225 {
1226         struct rb_node *rb_node;
1227         struct mapping_node *node;
1228         struct reloc_control *rc = root->fs_info->reloc_ctl;
1229
1230         node = kmalloc(sizeof(*node), GFP_NOFS);
1231         if (!node)
1232                 return -ENOMEM;
1233
1234         node->bytenr = root->node->start;
1235         node->data = root;
1236
1237         spin_lock(&rc->reloc_root_tree.lock);
1238         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1239                               node->bytenr, &node->rb_node);
1240         spin_unlock(&rc->reloc_root_tree.lock);
1241         if (rb_node) {
1242                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1243                             "for start=%llu while inserting into relocation "
1244                             "tree\n", node->bytenr);
1245                 kfree(node);
1246                 return -EEXIST;
1247         }
1248
1249         list_add_tail(&root->root_list, &rc->reloc_roots);
1250         return 0;
1251 }
1252
1253 /*
1254  * helper to update/delete the 'address of tree root -> reloc tree'
1255  * mapping
1256  */
1257 static int __update_reloc_root(struct btrfs_root *root, int del)
1258 {
1259         struct rb_node *rb_node;
1260         struct mapping_node *node = NULL;
1261         struct reloc_control *rc = root->fs_info->reloc_ctl;
1262
1263         spin_lock(&rc->reloc_root_tree.lock);
1264         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1265                               root->commit_root->start);
1266         if (rb_node) {
1267                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1268                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1269         }
1270         spin_unlock(&rc->reloc_root_tree.lock);
1271
1272         BUG_ON((struct btrfs_root *)node->data != root);
1273
1274         if (!del) {
1275                 spin_lock(&rc->reloc_root_tree.lock);
1276                 node->bytenr = root->node->start;
1277                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1278                                       node->bytenr, &node->rb_node);
1279                 spin_unlock(&rc->reloc_root_tree.lock);
1280                 if (rb_node)
1281                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1282         } else {
1283                 spin_lock(&root->fs_info->trans_lock);
1284                 list_del_init(&root->root_list);
1285                 spin_unlock(&root->fs_info->trans_lock);
1286                 kfree(node);
1287         }
1288         return 0;
1289 }
1290
1291 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1292                                         struct btrfs_root *root, u64 objectid)
1293 {
1294         struct btrfs_root *reloc_root;
1295         struct extent_buffer *eb;
1296         struct btrfs_root_item *root_item;
1297         struct btrfs_key root_key;
1298         int ret;
1299
1300         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1301         BUG_ON(!root_item);
1302
1303         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1304         root_key.type = BTRFS_ROOT_ITEM_KEY;
1305         root_key.offset = objectid;
1306
1307         if (root->root_key.objectid == objectid) {
1308                 /* called by btrfs_init_reloc_root */
1309                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1310                                       BTRFS_TREE_RELOC_OBJECTID);
1311                 BUG_ON(ret);
1312
1313                 btrfs_set_root_last_snapshot(&root->root_item,
1314                                              trans->transid - 1);
1315         } else {
1316                 /*
1317                  * called by btrfs_reloc_post_snapshot_hook.
1318                  * the source tree is a reloc tree, all tree blocks
1319                  * modified after it was created have RELOC flag
1320                  * set in their headers. so it's OK to not update
1321                  * the 'last_snapshot'.
1322                  */
1323                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1324                                       BTRFS_TREE_RELOC_OBJECTID);
1325                 BUG_ON(ret);
1326         }
1327
1328         memcpy(root_item, &root->root_item, sizeof(*root_item));
1329         btrfs_set_root_bytenr(root_item, eb->start);
1330         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1331         btrfs_set_root_generation(root_item, trans->transid);
1332
1333         if (root->root_key.objectid == objectid) {
1334                 btrfs_set_root_refs(root_item, 0);
1335                 memset(&root_item->drop_progress, 0,
1336                        sizeof(struct btrfs_disk_key));
1337                 root_item->drop_level = 0;
1338         }
1339
1340         btrfs_tree_unlock(eb);
1341         free_extent_buffer(eb);
1342
1343         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1344                                 &root_key, root_item);
1345         BUG_ON(ret);
1346         kfree(root_item);
1347
1348         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1349                                                  &root_key);
1350         BUG_ON(IS_ERR(reloc_root));
1351         reloc_root->last_trans = trans->transid;
1352         return reloc_root;
1353 }
1354
1355 /*
1356  * create reloc tree for a given fs tree. reloc tree is just a
1357  * snapshot of the fs tree with special root objectid.
1358  */
1359 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1360                           struct btrfs_root *root)
1361 {
1362         struct btrfs_root *reloc_root;
1363         struct reloc_control *rc = root->fs_info->reloc_ctl;
1364         int clear_rsv = 0;
1365         int ret;
1366
1367         if (root->reloc_root) {
1368                 reloc_root = root->reloc_root;
1369                 reloc_root->last_trans = trans->transid;
1370                 return 0;
1371         }
1372
1373         if (!rc || !rc->create_reloc_tree ||
1374             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1375                 return 0;
1376
1377         if (!trans->block_rsv) {
1378                 trans->block_rsv = rc->block_rsv;
1379                 clear_rsv = 1;
1380         }
1381         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1382         if (clear_rsv)
1383                 trans->block_rsv = NULL;
1384
1385         ret = __add_reloc_root(reloc_root);
1386         BUG_ON(ret < 0);
1387         root->reloc_root = reloc_root;
1388         return 0;
1389 }
1390
1391 /*
1392  * update root item of reloc tree
1393  */
1394 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1395                             struct btrfs_root *root)
1396 {
1397         struct btrfs_root *reloc_root;
1398         struct btrfs_root_item *root_item;
1399         int del = 0;
1400         int ret;
1401
1402         if (!root->reloc_root)
1403                 goto out;
1404
1405         reloc_root = root->reloc_root;
1406         root_item = &reloc_root->root_item;
1407
1408         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1409             btrfs_root_refs(root_item) == 0) {
1410                 root->reloc_root = NULL;
1411                 del = 1;
1412         }
1413
1414         __update_reloc_root(reloc_root, del);
1415
1416         if (reloc_root->commit_root != reloc_root->node) {
1417                 btrfs_set_root_node(root_item, reloc_root->node);
1418                 free_extent_buffer(reloc_root->commit_root);
1419                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1420         }
1421
1422         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1423                                 &reloc_root->root_key, root_item);
1424         BUG_ON(ret);
1425
1426 out:
1427         return 0;
1428 }
1429
1430 /*
1431  * helper to find first cached inode with inode number >= objectid
1432  * in a subvolume
1433  */
1434 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1435 {
1436         struct rb_node *node;
1437         struct rb_node *prev;
1438         struct btrfs_inode *entry;
1439         struct inode *inode;
1440
1441         spin_lock(&root->inode_lock);
1442 again:
1443         node = root->inode_tree.rb_node;
1444         prev = NULL;
1445         while (node) {
1446                 prev = node;
1447                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1448
1449                 if (objectid < btrfs_ino(&entry->vfs_inode))
1450                         node = node->rb_left;
1451                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1452                         node = node->rb_right;
1453                 else
1454                         break;
1455         }
1456         if (!node) {
1457                 while (prev) {
1458                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1459                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1460                                 node = prev;
1461                                 break;
1462                         }
1463                         prev = rb_next(prev);
1464                 }
1465         }
1466         while (node) {
1467                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1468                 inode = igrab(&entry->vfs_inode);
1469                 if (inode) {
1470                         spin_unlock(&root->inode_lock);
1471                         return inode;
1472                 }
1473
1474                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1475                 if (cond_resched_lock(&root->inode_lock))
1476                         goto again;
1477
1478                 node = rb_next(node);
1479         }
1480         spin_unlock(&root->inode_lock);
1481         return NULL;
1482 }
1483
1484 static int in_block_group(u64 bytenr,
1485                           struct btrfs_block_group_cache *block_group)
1486 {
1487         if (bytenr >= block_group->key.objectid &&
1488             bytenr < block_group->key.objectid + block_group->key.offset)
1489                 return 1;
1490         return 0;
1491 }
1492
1493 /*
1494  * get new location of data
1495  */
1496 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1497                             u64 bytenr, u64 num_bytes)
1498 {
1499         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1500         struct btrfs_path *path;
1501         struct btrfs_file_extent_item *fi;
1502         struct extent_buffer *leaf;
1503         int ret;
1504
1505         path = btrfs_alloc_path();
1506         if (!path)
1507                 return -ENOMEM;
1508
1509         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1510         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1511                                        bytenr, 0);
1512         if (ret < 0)
1513                 goto out;
1514         if (ret > 0) {
1515                 ret = -ENOENT;
1516                 goto out;
1517         }
1518
1519         leaf = path->nodes[0];
1520         fi = btrfs_item_ptr(leaf, path->slots[0],
1521                             struct btrfs_file_extent_item);
1522
1523         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1524                btrfs_file_extent_compression(leaf, fi) ||
1525                btrfs_file_extent_encryption(leaf, fi) ||
1526                btrfs_file_extent_other_encoding(leaf, fi));
1527
1528         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1529                 ret = 1;
1530                 goto out;
1531         }
1532
1533         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1534         ret = 0;
1535 out:
1536         btrfs_free_path(path);
1537         return ret;
1538 }
1539
1540 /*
1541  * update file extent items in the tree leaf to point to
1542  * the new locations.
1543  */
1544 static noinline_for_stack
1545 int replace_file_extents(struct btrfs_trans_handle *trans,
1546                          struct reloc_control *rc,
1547                          struct btrfs_root *root,
1548                          struct extent_buffer *leaf)
1549 {
1550         struct btrfs_key key;
1551         struct btrfs_file_extent_item *fi;
1552         struct inode *inode = NULL;
1553         u64 parent;
1554         u64 bytenr;
1555         u64 new_bytenr = 0;
1556         u64 num_bytes;
1557         u64 end;
1558         u32 nritems;
1559         u32 i;
1560         int ret;
1561         int first = 1;
1562         int dirty = 0;
1563
1564         if (rc->stage != UPDATE_DATA_PTRS)
1565                 return 0;
1566
1567         /* reloc trees always use full backref */
1568         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1569                 parent = leaf->start;
1570         else
1571                 parent = 0;
1572
1573         nritems = btrfs_header_nritems(leaf);
1574         for (i = 0; i < nritems; i++) {
1575                 cond_resched();
1576                 btrfs_item_key_to_cpu(leaf, &key, i);
1577                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1578                         continue;
1579                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1580                 if (btrfs_file_extent_type(leaf, fi) ==
1581                     BTRFS_FILE_EXTENT_INLINE)
1582                         continue;
1583                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1584                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1585                 if (bytenr == 0)
1586                         continue;
1587                 if (!in_block_group(bytenr, rc->block_group))
1588                         continue;
1589
1590                 /*
1591                  * if we are modifying block in fs tree, wait for readpage
1592                  * to complete and drop the extent cache
1593                  */
1594                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1595                         if (first) {
1596                                 inode = find_next_inode(root, key.objectid);
1597                                 first = 0;
1598                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1599                                 btrfs_add_delayed_iput(inode);
1600                                 inode = find_next_inode(root, key.objectid);
1601                         }
1602                         if (inode && btrfs_ino(inode) == key.objectid) {
1603                                 end = key.offset +
1604                                       btrfs_file_extent_num_bytes(leaf, fi);
1605                                 WARN_ON(!IS_ALIGNED(key.offset,
1606                                                     root->sectorsize));
1607                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1608                                 end--;
1609                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1610                                                       key.offset, end);
1611                                 if (!ret)
1612                                         continue;
1613
1614                                 btrfs_drop_extent_cache(inode, key.offset, end,
1615                                                         1);
1616                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1617                                               key.offset, end);
1618                         }
1619                 }
1620
1621                 ret = get_new_location(rc->data_inode, &new_bytenr,
1622                                        bytenr, num_bytes);
1623                 if (ret > 0) {
1624                         WARN_ON(1);
1625                         continue;
1626                 }
1627                 BUG_ON(ret < 0);
1628
1629                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1630                 dirty = 1;
1631
1632                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1633                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1634                                            num_bytes, parent,
1635                                            btrfs_header_owner(leaf),
1636                                            key.objectid, key.offset, 1);
1637                 BUG_ON(ret);
1638
1639                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1640                                         parent, btrfs_header_owner(leaf),
1641                                         key.objectid, key.offset, 1);
1642                 BUG_ON(ret);
1643         }
1644         if (dirty)
1645                 btrfs_mark_buffer_dirty(leaf);
1646         if (inode)
1647                 btrfs_add_delayed_iput(inode);
1648         return 0;
1649 }
1650
1651 static noinline_for_stack
1652 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1653                      struct btrfs_path *path, int level)
1654 {
1655         struct btrfs_disk_key key1;
1656         struct btrfs_disk_key key2;
1657         btrfs_node_key(eb, &key1, slot);
1658         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1659         return memcmp(&key1, &key2, sizeof(key1));
1660 }
1661
1662 /*
1663  * try to replace tree blocks in fs tree with the new blocks
1664  * in reloc tree. tree blocks haven't been modified since the
1665  * reloc tree was create can be replaced.
1666  *
1667  * if a block was replaced, level of the block + 1 is returned.
1668  * if no block got replaced, 0 is returned. if there are other
1669  * errors, a negative error number is returned.
1670  */
1671 static noinline_for_stack
1672 int replace_path(struct btrfs_trans_handle *trans,
1673                  struct btrfs_root *dest, struct btrfs_root *src,
1674                  struct btrfs_path *path, struct btrfs_key *next_key,
1675                  int lowest_level, int max_level)
1676 {
1677         struct extent_buffer *eb;
1678         struct extent_buffer *parent;
1679         struct btrfs_key key;
1680         u64 old_bytenr;
1681         u64 new_bytenr;
1682         u64 old_ptr_gen;
1683         u64 new_ptr_gen;
1684         u64 last_snapshot;
1685         u32 blocksize;
1686         int cow = 0;
1687         int level;
1688         int ret;
1689         int slot;
1690
1691         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1692         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1693
1694         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1695 again:
1696         slot = path->slots[lowest_level];
1697         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1698
1699         eb = btrfs_lock_root_node(dest);
1700         btrfs_set_lock_blocking(eb);
1701         level = btrfs_header_level(eb);
1702
1703         if (level < lowest_level) {
1704                 btrfs_tree_unlock(eb);
1705                 free_extent_buffer(eb);
1706                 return 0;
1707         }
1708
1709         if (cow) {
1710                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1711                 BUG_ON(ret);
1712         }
1713         btrfs_set_lock_blocking(eb);
1714
1715         if (next_key) {
1716                 next_key->objectid = (u64)-1;
1717                 next_key->type = (u8)-1;
1718                 next_key->offset = (u64)-1;
1719         }
1720
1721         parent = eb;
1722         while (1) {
1723                 level = btrfs_header_level(parent);
1724                 BUG_ON(level < lowest_level);
1725
1726                 ret = btrfs_bin_search(parent, &key, level, &slot);
1727                 if (ret && slot > 0)
1728                         slot--;
1729
1730                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1731                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1732
1733                 old_bytenr = btrfs_node_blockptr(parent, slot);
1734                 blocksize = btrfs_level_size(dest, level - 1);
1735                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1736
1737                 if (level <= max_level) {
1738                         eb = path->nodes[level];
1739                         new_bytenr = btrfs_node_blockptr(eb,
1740                                                         path->slots[level]);
1741                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1742                                                         path->slots[level]);
1743                 } else {
1744                         new_bytenr = 0;
1745                         new_ptr_gen = 0;
1746                 }
1747
1748                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1749                         WARN_ON(1);
1750                         ret = level;
1751                         break;
1752                 }
1753
1754                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1755                     memcmp_node_keys(parent, slot, path, level)) {
1756                         if (level <= lowest_level) {
1757                                 ret = 0;
1758                                 break;
1759                         }
1760
1761                         eb = read_tree_block(dest, old_bytenr, blocksize,
1762                                              old_ptr_gen);
1763                         BUG_ON(!eb);
1764                         btrfs_tree_lock(eb);
1765                         if (cow) {
1766                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1767                                                       slot, &eb);
1768                                 BUG_ON(ret);
1769                         }
1770                         btrfs_set_lock_blocking(eb);
1771
1772                         btrfs_tree_unlock(parent);
1773                         free_extent_buffer(parent);
1774
1775                         parent = eb;
1776                         continue;
1777                 }
1778
1779                 if (!cow) {
1780                         btrfs_tree_unlock(parent);
1781                         free_extent_buffer(parent);
1782                         cow = 1;
1783                         goto again;
1784                 }
1785
1786                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1787                                       path->slots[level]);
1788                 btrfs_release_path(path);
1789
1790                 path->lowest_level = level;
1791                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1792                 path->lowest_level = 0;
1793                 BUG_ON(ret);
1794
1795                 /*
1796                  * swap blocks in fs tree and reloc tree.
1797                  */
1798                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1799                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1800                 btrfs_mark_buffer_dirty(parent);
1801
1802                 btrfs_set_node_blockptr(path->nodes[level],
1803                                         path->slots[level], old_bytenr);
1804                 btrfs_set_node_ptr_generation(path->nodes[level],
1805                                               path->slots[level], old_ptr_gen);
1806                 btrfs_mark_buffer_dirty(path->nodes[level]);
1807
1808                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1809                                         path->nodes[level]->start,
1810                                         src->root_key.objectid, level - 1, 0,
1811                                         1);
1812                 BUG_ON(ret);
1813                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1814                                         0, dest->root_key.objectid, level - 1,
1815                                         0, 1);
1816                 BUG_ON(ret);
1817
1818                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1819                                         path->nodes[level]->start,
1820                                         src->root_key.objectid, level - 1, 0,
1821                                         1);
1822                 BUG_ON(ret);
1823
1824                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1825                                         0, dest->root_key.objectid, level - 1,
1826                                         0, 1);
1827                 BUG_ON(ret);
1828
1829                 btrfs_unlock_up_safe(path, 0);
1830
1831                 ret = level;
1832                 break;
1833         }
1834         btrfs_tree_unlock(parent);
1835         free_extent_buffer(parent);
1836         return ret;
1837 }
1838
1839 /*
1840  * helper to find next relocated block in reloc tree
1841  */
1842 static noinline_for_stack
1843 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1844                        int *level)
1845 {
1846         struct extent_buffer *eb;
1847         int i;
1848         u64 last_snapshot;
1849         u32 nritems;
1850
1851         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1852
1853         for (i = 0; i < *level; i++) {
1854                 free_extent_buffer(path->nodes[i]);
1855                 path->nodes[i] = NULL;
1856         }
1857
1858         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1859                 eb = path->nodes[i];
1860                 nritems = btrfs_header_nritems(eb);
1861                 while (path->slots[i] + 1 < nritems) {
1862                         path->slots[i]++;
1863                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1864                             last_snapshot)
1865                                 continue;
1866
1867                         *level = i;
1868                         return 0;
1869                 }
1870                 free_extent_buffer(path->nodes[i]);
1871                 path->nodes[i] = NULL;
1872         }
1873         return 1;
1874 }
1875
1876 /*
1877  * walk down reloc tree to find relocated block of lowest level
1878  */
1879 static noinline_for_stack
1880 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1881                          int *level)
1882 {
1883         struct extent_buffer *eb = NULL;
1884         int i;
1885         u64 bytenr;
1886         u64 ptr_gen = 0;
1887         u64 last_snapshot;
1888         u32 blocksize;
1889         u32 nritems;
1890
1891         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1892
1893         for (i = *level; i > 0; i--) {
1894                 eb = path->nodes[i];
1895                 nritems = btrfs_header_nritems(eb);
1896                 while (path->slots[i] < nritems) {
1897                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1898                         if (ptr_gen > last_snapshot)
1899                                 break;
1900                         path->slots[i]++;
1901                 }
1902                 if (path->slots[i] >= nritems) {
1903                         if (i == *level)
1904                                 break;
1905                         *level = i + 1;
1906                         return 0;
1907                 }
1908                 if (i == 1) {
1909                         *level = i;
1910                         return 0;
1911                 }
1912
1913                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1914                 blocksize = btrfs_level_size(root, i - 1);
1915                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1916                 BUG_ON(btrfs_header_level(eb) != i - 1);
1917                 path->nodes[i - 1] = eb;
1918                 path->slots[i - 1] = 0;
1919         }
1920         return 1;
1921 }
1922
1923 /*
1924  * invalidate extent cache for file extents whose key in range of
1925  * [min_key, max_key)
1926  */
1927 static int invalidate_extent_cache(struct btrfs_root *root,
1928                                    struct btrfs_key *min_key,
1929                                    struct btrfs_key *max_key)
1930 {
1931         struct inode *inode = NULL;
1932         u64 objectid;
1933         u64 start, end;
1934         u64 ino;
1935
1936         objectid = min_key->objectid;
1937         while (1) {
1938                 cond_resched();
1939                 iput(inode);
1940
1941                 if (objectid > max_key->objectid)
1942                         break;
1943
1944                 inode = find_next_inode(root, objectid);
1945                 if (!inode)
1946                         break;
1947                 ino = btrfs_ino(inode);
1948
1949                 if (ino > max_key->objectid) {
1950                         iput(inode);
1951                         break;
1952                 }
1953
1954                 objectid = ino + 1;
1955                 if (!S_ISREG(inode->i_mode))
1956                         continue;
1957
1958                 if (unlikely(min_key->objectid == ino)) {
1959                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1960                                 continue;
1961                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1962                                 start = 0;
1963                         else {
1964                                 start = min_key->offset;
1965                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1966                         }
1967                 } else {
1968                         start = 0;
1969                 }
1970
1971                 if (unlikely(max_key->objectid == ino)) {
1972                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1973                                 continue;
1974                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1975                                 end = (u64)-1;
1976                         } else {
1977                                 if (max_key->offset == 0)
1978                                         continue;
1979                                 end = max_key->offset;
1980                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1981                                 end--;
1982                         }
1983                 } else {
1984                         end = (u64)-1;
1985                 }
1986
1987                 /* the lock_extent waits for readpage to complete */
1988                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
1989                 btrfs_drop_extent_cache(inode, start, end, 1);
1990                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
1991         }
1992         return 0;
1993 }
1994
1995 static int find_next_key(struct btrfs_path *path, int level,
1996                          struct btrfs_key *key)
1997
1998 {
1999         while (level < BTRFS_MAX_LEVEL) {
2000                 if (!path->nodes[level])
2001                         break;
2002                 if (path->slots[level] + 1 <
2003                     btrfs_header_nritems(path->nodes[level])) {
2004                         btrfs_node_key_to_cpu(path->nodes[level], key,
2005                                               path->slots[level] + 1);
2006                         return 0;
2007                 }
2008                 level++;
2009         }
2010         return 1;
2011 }
2012
2013 /*
2014  * merge the relocated tree blocks in reloc tree with corresponding
2015  * fs tree.
2016  */
2017 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2018                                                struct btrfs_root *root)
2019 {
2020         LIST_HEAD(inode_list);
2021         struct btrfs_key key;
2022         struct btrfs_key next_key;
2023         struct btrfs_trans_handle *trans;
2024         struct btrfs_root *reloc_root;
2025         struct btrfs_root_item *root_item;
2026         struct btrfs_path *path;
2027         struct extent_buffer *leaf;
2028         int level;
2029         int max_level;
2030         int replaced = 0;
2031         int ret;
2032         int err = 0;
2033         u32 min_reserved;
2034
2035         path = btrfs_alloc_path();
2036         if (!path)
2037                 return -ENOMEM;
2038         path->reada = 1;
2039
2040         reloc_root = root->reloc_root;
2041         root_item = &reloc_root->root_item;
2042
2043         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2044                 level = btrfs_root_level(root_item);
2045                 extent_buffer_get(reloc_root->node);
2046                 path->nodes[level] = reloc_root->node;
2047                 path->slots[level] = 0;
2048         } else {
2049                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2050
2051                 level = root_item->drop_level;
2052                 BUG_ON(level == 0);
2053                 path->lowest_level = level;
2054                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2055                 path->lowest_level = 0;
2056                 if (ret < 0) {
2057                         btrfs_free_path(path);
2058                         return ret;
2059                 }
2060
2061                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2062                                       path->slots[level]);
2063                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2064
2065                 btrfs_unlock_up_safe(path, 0);
2066         }
2067
2068         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2069         memset(&next_key, 0, sizeof(next_key));
2070
2071         while (1) {
2072                 trans = btrfs_start_transaction(root, 0);
2073                 BUG_ON(IS_ERR(trans));
2074                 trans->block_rsv = rc->block_rsv;
2075
2076                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2077                                              BTRFS_RESERVE_FLUSH_ALL);
2078                 if (ret) {
2079                         BUG_ON(ret != -EAGAIN);
2080                         ret = btrfs_commit_transaction(trans, root);
2081                         BUG_ON(ret);
2082                         continue;
2083                 }
2084
2085                 replaced = 0;
2086                 max_level = level;
2087
2088                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2089                 if (ret < 0) {
2090                         err = ret;
2091                         goto out;
2092                 }
2093                 if (ret > 0)
2094                         break;
2095
2096                 if (!find_next_key(path, level, &key) &&
2097                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2098                         ret = 0;
2099                 } else {
2100                         ret = replace_path(trans, root, reloc_root, path,
2101                                            &next_key, level, max_level);
2102                 }
2103                 if (ret < 0) {
2104                         err = ret;
2105                         goto out;
2106                 }
2107
2108                 if (ret > 0) {
2109                         level = ret;
2110                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2111                                               path->slots[level]);
2112                         replaced = 1;
2113                 }
2114
2115                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2116                 if (ret > 0)
2117                         break;
2118
2119                 BUG_ON(level == 0);
2120                 /*
2121                  * save the merging progress in the drop_progress.
2122                  * this is OK since root refs == 1 in this case.
2123                  */
2124                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2125                                path->slots[level]);
2126                 root_item->drop_level = level;
2127
2128                 btrfs_end_transaction_throttle(trans, root);
2129
2130                 btrfs_btree_balance_dirty(root);
2131
2132                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2133                         invalidate_extent_cache(root, &key, &next_key);
2134         }
2135
2136         /*
2137          * handle the case only one block in the fs tree need to be
2138          * relocated and the block is tree root.
2139          */
2140         leaf = btrfs_lock_root_node(root);
2141         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2142         btrfs_tree_unlock(leaf);
2143         free_extent_buffer(leaf);
2144         if (ret < 0)
2145                 err = ret;
2146 out:
2147         btrfs_free_path(path);
2148
2149         if (err == 0) {
2150                 memset(&root_item->drop_progress, 0,
2151                        sizeof(root_item->drop_progress));
2152                 root_item->drop_level = 0;
2153                 btrfs_set_root_refs(root_item, 0);
2154                 btrfs_update_reloc_root(trans, root);
2155         }
2156
2157         btrfs_end_transaction_throttle(trans, root);
2158
2159         btrfs_btree_balance_dirty(root);
2160
2161         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2162                 invalidate_extent_cache(root, &key, &next_key);
2163
2164         return err;
2165 }
2166
2167 static noinline_for_stack
2168 int prepare_to_merge(struct reloc_control *rc, int err)
2169 {
2170         struct btrfs_root *root = rc->extent_root;
2171         struct btrfs_root *reloc_root;
2172         struct btrfs_trans_handle *trans;
2173         LIST_HEAD(reloc_roots);
2174         u64 num_bytes = 0;
2175         int ret;
2176
2177         mutex_lock(&root->fs_info->reloc_mutex);
2178         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2179         rc->merging_rsv_size += rc->nodes_relocated * 2;
2180         mutex_unlock(&root->fs_info->reloc_mutex);
2181
2182 again:
2183         if (!err) {
2184                 num_bytes = rc->merging_rsv_size;
2185                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2186                                           BTRFS_RESERVE_FLUSH_ALL);
2187                 if (ret)
2188                         err = ret;
2189         }
2190
2191         trans = btrfs_join_transaction(rc->extent_root);
2192         if (IS_ERR(trans)) {
2193                 if (!err)
2194                         btrfs_block_rsv_release(rc->extent_root,
2195                                                 rc->block_rsv, num_bytes);
2196                 return PTR_ERR(trans);
2197         }
2198
2199         if (!err) {
2200                 if (num_bytes != rc->merging_rsv_size) {
2201                         btrfs_end_transaction(trans, rc->extent_root);
2202                         btrfs_block_rsv_release(rc->extent_root,
2203                                                 rc->block_rsv, num_bytes);
2204                         goto again;
2205                 }
2206         }
2207
2208         rc->merge_reloc_tree = 1;
2209
2210         while (!list_empty(&rc->reloc_roots)) {
2211                 reloc_root = list_entry(rc->reloc_roots.next,
2212                                         struct btrfs_root, root_list);
2213                 list_del_init(&reloc_root->root_list);
2214
2215                 root = read_fs_root(reloc_root->fs_info,
2216                                     reloc_root->root_key.offset);
2217                 BUG_ON(IS_ERR(root));
2218                 BUG_ON(root->reloc_root != reloc_root);
2219
2220                 /*
2221                  * set reference count to 1, so btrfs_recover_relocation
2222                  * knows it should resumes merging
2223                  */
2224                 if (!err)
2225                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2226                 btrfs_update_reloc_root(trans, root);
2227
2228                 list_add(&reloc_root->root_list, &reloc_roots);
2229         }
2230
2231         list_splice(&reloc_roots, &rc->reloc_roots);
2232
2233         if (!err)
2234                 btrfs_commit_transaction(trans, rc->extent_root);
2235         else
2236                 btrfs_end_transaction(trans, rc->extent_root);
2237         return err;
2238 }
2239
2240 static noinline_for_stack
2241 int merge_reloc_roots(struct reloc_control *rc)
2242 {
2243         struct btrfs_root *root;
2244         struct btrfs_root *reloc_root;
2245         LIST_HEAD(reloc_roots);
2246         int found = 0;
2247         int ret;
2248 again:
2249         root = rc->extent_root;
2250
2251         /*
2252          * this serializes us with btrfs_record_root_in_transaction,
2253          * we have to make sure nobody is in the middle of
2254          * adding their roots to the list while we are
2255          * doing this splice
2256          */
2257         mutex_lock(&root->fs_info->reloc_mutex);
2258         list_splice_init(&rc->reloc_roots, &reloc_roots);
2259         mutex_unlock(&root->fs_info->reloc_mutex);
2260
2261         while (!list_empty(&reloc_roots)) {
2262                 found = 1;
2263                 reloc_root = list_entry(reloc_roots.next,
2264                                         struct btrfs_root, root_list);
2265
2266                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2267                         root = read_fs_root(reloc_root->fs_info,
2268                                             reloc_root->root_key.offset);
2269                         BUG_ON(IS_ERR(root));
2270                         BUG_ON(root->reloc_root != reloc_root);
2271
2272                         ret = merge_reloc_root(rc, root);
2273                         BUG_ON(ret);
2274                 } else {
2275                         list_del_init(&reloc_root->root_list);
2276                 }
2277                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2278                 BUG_ON(ret < 0);
2279         }
2280
2281         if (found) {
2282                 found = 0;
2283                 goto again;
2284         }
2285         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2286         return 0;
2287 }
2288
2289 static void free_block_list(struct rb_root *blocks)
2290 {
2291         struct tree_block *block;
2292         struct rb_node *rb_node;
2293         while ((rb_node = rb_first(blocks))) {
2294                 block = rb_entry(rb_node, struct tree_block, rb_node);
2295                 rb_erase(rb_node, blocks);
2296                 kfree(block);
2297         }
2298 }
2299
2300 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2301                                       struct btrfs_root *reloc_root)
2302 {
2303         struct btrfs_root *root;
2304
2305         if (reloc_root->last_trans == trans->transid)
2306                 return 0;
2307
2308         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2309         BUG_ON(IS_ERR(root));
2310         BUG_ON(root->reloc_root != reloc_root);
2311
2312         return btrfs_record_root_in_trans(trans, root);
2313 }
2314
2315 static noinline_for_stack
2316 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2317                                      struct reloc_control *rc,
2318                                      struct backref_node *node,
2319                                      struct backref_edge *edges[], int *nr)
2320 {
2321         struct backref_node *next;
2322         struct btrfs_root *root;
2323         int index = 0;
2324
2325         next = node;
2326         while (1) {
2327                 cond_resched();
2328                 next = walk_up_backref(next, edges, &index);
2329                 root = next->root;
2330                 BUG_ON(!root);
2331                 BUG_ON(!root->ref_cows);
2332
2333                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2334                         record_reloc_root_in_trans(trans, root);
2335                         break;
2336                 }
2337
2338                 btrfs_record_root_in_trans(trans, root);
2339                 root = root->reloc_root;
2340
2341                 if (next->new_bytenr != root->node->start) {
2342                         BUG_ON(next->new_bytenr);
2343                         BUG_ON(!list_empty(&next->list));
2344                         next->new_bytenr = root->node->start;
2345                         next->root = root;
2346                         list_add_tail(&next->list,
2347                                       &rc->backref_cache.changed);
2348                         __mark_block_processed(rc, next);
2349                         break;
2350                 }
2351
2352                 WARN_ON(1);
2353                 root = NULL;
2354                 next = walk_down_backref(edges, &index);
2355                 if (!next || next->level <= node->level)
2356                         break;
2357         }
2358         if (!root)
2359                 return NULL;
2360
2361         *nr = index;
2362         next = node;
2363         /* setup backref node path for btrfs_reloc_cow_block */
2364         while (1) {
2365                 rc->backref_cache.path[next->level] = next;
2366                 if (--index < 0)
2367                         break;
2368                 next = edges[index]->node[UPPER];
2369         }
2370         return root;
2371 }
2372
2373 /*
2374  * select a tree root for relocation. return NULL if the block
2375  * is reference counted. we should use do_relocation() in this
2376  * case. return a tree root pointer if the block isn't reference
2377  * counted. return -ENOENT if the block is root of reloc tree.
2378  */
2379 static noinline_for_stack
2380 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2381                                    struct backref_node *node)
2382 {
2383         struct backref_node *next;
2384         struct btrfs_root *root;
2385         struct btrfs_root *fs_root = NULL;
2386         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2387         int index = 0;
2388
2389         next = node;
2390         while (1) {
2391                 cond_resched();
2392                 next = walk_up_backref(next, edges, &index);
2393                 root = next->root;
2394                 BUG_ON(!root);
2395
2396                 /* no other choice for non-references counted tree */
2397                 if (!root->ref_cows)
2398                         return root;
2399
2400                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2401                         fs_root = root;
2402
2403                 if (next != node)
2404                         return NULL;
2405
2406                 next = walk_down_backref(edges, &index);
2407                 if (!next || next->level <= node->level)
2408                         break;
2409         }
2410
2411         if (!fs_root)
2412                 return ERR_PTR(-ENOENT);
2413         return fs_root;
2414 }
2415
2416 static noinline_for_stack
2417 u64 calcu_metadata_size(struct reloc_control *rc,
2418                         struct backref_node *node, int reserve)
2419 {
2420         struct backref_node *next = node;
2421         struct backref_edge *edge;
2422         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2423         u64 num_bytes = 0;
2424         int index = 0;
2425
2426         BUG_ON(reserve && node->processed);
2427
2428         while (next) {
2429                 cond_resched();
2430                 while (1) {
2431                         if (next->processed && (reserve || next != node))
2432                                 break;
2433
2434                         num_bytes += btrfs_level_size(rc->extent_root,
2435                                                       next->level);
2436
2437                         if (list_empty(&next->upper))
2438                                 break;
2439
2440                         edge = list_entry(next->upper.next,
2441                                           struct backref_edge, list[LOWER]);
2442                         edges[index++] = edge;
2443                         next = edge->node[UPPER];
2444                 }
2445                 next = walk_down_backref(edges, &index);
2446         }
2447         return num_bytes;
2448 }
2449
2450 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2451                                   struct reloc_control *rc,
2452                                   struct backref_node *node)
2453 {
2454         struct btrfs_root *root = rc->extent_root;
2455         u64 num_bytes;
2456         int ret;
2457
2458         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2459
2460         trans->block_rsv = rc->block_rsv;
2461         ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2462                                   BTRFS_RESERVE_FLUSH_ALL);
2463         if (ret) {
2464                 if (ret == -EAGAIN)
2465                         rc->commit_transaction = 1;
2466                 return ret;
2467         }
2468
2469         return 0;
2470 }
2471
2472 static void release_metadata_space(struct reloc_control *rc,
2473                                    struct backref_node *node)
2474 {
2475         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2476         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2477 }
2478
2479 /*
2480  * relocate a block tree, and then update pointers in upper level
2481  * blocks that reference the block to point to the new location.
2482  *
2483  * if called by link_to_upper, the block has already been relocated.
2484  * in that case this function just updates pointers.
2485  */
2486 static int do_relocation(struct btrfs_trans_handle *trans,
2487                          struct reloc_control *rc,
2488                          struct backref_node *node,
2489                          struct btrfs_key *key,
2490                          struct btrfs_path *path, int lowest)
2491 {
2492         struct backref_node *upper;
2493         struct backref_edge *edge;
2494         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2495         struct btrfs_root *root;
2496         struct extent_buffer *eb;
2497         u32 blocksize;
2498         u64 bytenr;
2499         u64 generation;
2500         int nr;
2501         int slot;
2502         int ret;
2503         int err = 0;
2504
2505         BUG_ON(lowest && node->eb);
2506
2507         path->lowest_level = node->level + 1;
2508         rc->backref_cache.path[node->level] = node;
2509         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2510                 cond_resched();
2511
2512                 upper = edge->node[UPPER];
2513                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2514                 BUG_ON(!root);
2515
2516                 if (upper->eb && !upper->locked) {
2517                         if (!lowest) {
2518                                 ret = btrfs_bin_search(upper->eb, key,
2519                                                        upper->level, &slot);
2520                                 BUG_ON(ret);
2521                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2522                                 if (node->eb->start == bytenr)
2523                                         goto next;
2524                         }
2525                         drop_node_buffer(upper);
2526                 }
2527
2528                 if (!upper->eb) {
2529                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2530                         if (ret < 0) {
2531                                 err = ret;
2532                                 break;
2533                         }
2534                         BUG_ON(ret > 0);
2535
2536                         if (!upper->eb) {
2537                                 upper->eb = path->nodes[upper->level];
2538                                 path->nodes[upper->level] = NULL;
2539                         } else {
2540                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2541                         }
2542
2543                         upper->locked = 1;
2544                         path->locks[upper->level] = 0;
2545
2546                         slot = path->slots[upper->level];
2547                         btrfs_release_path(path);
2548                 } else {
2549                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2550                                                &slot);
2551                         BUG_ON(ret);
2552                 }
2553
2554                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2555                 if (lowest) {
2556                         BUG_ON(bytenr != node->bytenr);
2557                 } else {
2558                         if (node->eb->start == bytenr)
2559                                 goto next;
2560                 }
2561
2562                 blocksize = btrfs_level_size(root, node->level);
2563                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2564                 eb = read_tree_block(root, bytenr, blocksize, generation);
2565                 if (!eb) {
2566                         err = -EIO;
2567                         goto next;
2568                 }
2569                 btrfs_tree_lock(eb);
2570                 btrfs_set_lock_blocking(eb);
2571
2572                 if (!node->eb) {
2573                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2574                                               slot, &eb);
2575                         btrfs_tree_unlock(eb);
2576                         free_extent_buffer(eb);
2577                         if (ret < 0) {
2578                                 err = ret;
2579                                 goto next;
2580                         }
2581                         BUG_ON(node->eb != eb);
2582                 } else {
2583                         btrfs_set_node_blockptr(upper->eb, slot,
2584                                                 node->eb->start);
2585                         btrfs_set_node_ptr_generation(upper->eb, slot,
2586                                                       trans->transid);
2587                         btrfs_mark_buffer_dirty(upper->eb);
2588
2589                         ret = btrfs_inc_extent_ref(trans, root,
2590                                                 node->eb->start, blocksize,
2591                                                 upper->eb->start,
2592                                                 btrfs_header_owner(upper->eb),
2593                                                 node->level, 0, 1);
2594                         BUG_ON(ret);
2595
2596                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2597                         BUG_ON(ret);
2598                 }
2599 next:
2600                 if (!upper->pending)
2601                         drop_node_buffer(upper);
2602                 else
2603                         unlock_node_buffer(upper);
2604                 if (err)
2605                         break;
2606         }
2607
2608         if (!err && node->pending) {
2609                 drop_node_buffer(node);
2610                 list_move_tail(&node->list, &rc->backref_cache.changed);
2611                 node->pending = 0;
2612         }
2613
2614         path->lowest_level = 0;
2615         BUG_ON(err == -ENOSPC);
2616         return err;
2617 }
2618
2619 static int link_to_upper(struct btrfs_trans_handle *trans,
2620                          struct reloc_control *rc,
2621                          struct backref_node *node,
2622                          struct btrfs_path *path)
2623 {
2624         struct btrfs_key key;
2625
2626         btrfs_node_key_to_cpu(node->eb, &key, 0);
2627         return do_relocation(trans, rc, node, &key, path, 0);
2628 }
2629
2630 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2631                                 struct reloc_control *rc,
2632                                 struct btrfs_path *path, int err)
2633 {
2634         LIST_HEAD(list);
2635         struct backref_cache *cache = &rc->backref_cache;
2636         struct backref_node *node;
2637         int level;
2638         int ret;
2639
2640         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2641                 while (!list_empty(&cache->pending[level])) {
2642                         node = list_entry(cache->pending[level].next,
2643                                           struct backref_node, list);
2644                         list_move_tail(&node->list, &list);
2645                         BUG_ON(!node->pending);
2646
2647                         if (!err) {
2648                                 ret = link_to_upper(trans, rc, node, path);
2649                                 if (ret < 0)
2650                                         err = ret;
2651                         }
2652                 }
2653                 list_splice_init(&list, &cache->pending[level]);
2654         }
2655         return err;
2656 }
2657
2658 static void mark_block_processed(struct reloc_control *rc,
2659                                  u64 bytenr, u32 blocksize)
2660 {
2661         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2662                         EXTENT_DIRTY, GFP_NOFS);
2663 }
2664
2665 static void __mark_block_processed(struct reloc_control *rc,
2666                                    struct backref_node *node)
2667 {
2668         u32 blocksize;
2669         if (node->level == 0 ||
2670             in_block_group(node->bytenr, rc->block_group)) {
2671                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2672                 mark_block_processed(rc, node->bytenr, blocksize);
2673         }
2674         node->processed = 1;
2675 }
2676
2677 /*
2678  * mark a block and all blocks directly/indirectly reference the block
2679  * as processed.
2680  */
2681 static void update_processed_blocks(struct reloc_control *rc,
2682                                     struct backref_node *node)
2683 {
2684         struct backref_node *next = node;
2685         struct backref_edge *edge;
2686         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2687         int index = 0;
2688
2689         while (next) {
2690                 cond_resched();
2691                 while (1) {
2692                         if (next->processed)
2693                                 break;
2694
2695                         __mark_block_processed(rc, next);
2696
2697                         if (list_empty(&next->upper))
2698                                 break;
2699
2700                         edge = list_entry(next->upper.next,
2701                                           struct backref_edge, list[LOWER]);
2702                         edges[index++] = edge;
2703                         next = edge->node[UPPER];
2704                 }
2705                 next = walk_down_backref(edges, &index);
2706         }
2707 }
2708
2709 static int tree_block_processed(u64 bytenr, u32 blocksize,
2710                                 struct reloc_control *rc)
2711 {
2712         if (test_range_bit(&rc->processed_blocks, bytenr,
2713                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2714                 return 1;
2715         return 0;
2716 }
2717
2718 static int get_tree_block_key(struct reloc_control *rc,
2719                               struct tree_block *block)
2720 {
2721         struct extent_buffer *eb;
2722
2723         BUG_ON(block->key_ready);
2724         eb = read_tree_block(rc->extent_root, block->bytenr,
2725                              block->key.objectid, block->key.offset);
2726         BUG_ON(!eb);
2727         WARN_ON(btrfs_header_level(eb) != block->level);
2728         if (block->level == 0)
2729                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2730         else
2731                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2732         free_extent_buffer(eb);
2733         block->key_ready = 1;
2734         return 0;
2735 }
2736
2737 static int reada_tree_block(struct reloc_control *rc,
2738                             struct tree_block *block)
2739 {
2740         BUG_ON(block->key_ready);
2741         readahead_tree_block(rc->extent_root, block->bytenr,
2742                              block->key.objectid, block->key.offset);
2743         return 0;
2744 }
2745
2746 /*
2747  * helper function to relocate a tree block
2748  */
2749 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2750                                 struct reloc_control *rc,
2751                                 struct backref_node *node,
2752                                 struct btrfs_key *key,
2753                                 struct btrfs_path *path)
2754 {
2755         struct btrfs_root *root;
2756         int release = 0;
2757         int ret = 0;
2758
2759         if (!node)
2760                 return 0;
2761
2762         BUG_ON(node->processed);
2763         root = select_one_root(trans, node);
2764         if (root == ERR_PTR(-ENOENT)) {
2765                 update_processed_blocks(rc, node);
2766                 goto out;
2767         }
2768
2769         if (!root || root->ref_cows) {
2770                 ret = reserve_metadata_space(trans, rc, node);
2771                 if (ret)
2772                         goto out;
2773                 release = 1;
2774         }
2775
2776         if (root) {
2777                 if (root->ref_cows) {
2778                         BUG_ON(node->new_bytenr);
2779                         BUG_ON(!list_empty(&node->list));
2780                         btrfs_record_root_in_trans(trans, root);
2781                         root = root->reloc_root;
2782                         node->new_bytenr = root->node->start;
2783                         node->root = root;
2784                         list_add_tail(&node->list, &rc->backref_cache.changed);
2785                 } else {
2786                         path->lowest_level = node->level;
2787                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2788                         btrfs_release_path(path);
2789                         if (ret > 0)
2790                                 ret = 0;
2791                 }
2792                 if (!ret)
2793                         update_processed_blocks(rc, node);
2794         } else {
2795                 ret = do_relocation(trans, rc, node, key, path, 1);
2796         }
2797 out:
2798         if (ret || node->level == 0 || node->cowonly) {
2799                 if (release)
2800                         release_metadata_space(rc, node);
2801                 remove_backref_node(&rc->backref_cache, node);
2802         }
2803         return ret;
2804 }
2805
2806 /*
2807  * relocate a list of blocks
2808  */
2809 static noinline_for_stack
2810 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2811                          struct reloc_control *rc, struct rb_root *blocks)
2812 {
2813         struct backref_node *node;
2814         struct btrfs_path *path;
2815         struct tree_block *block;
2816         struct rb_node *rb_node;
2817         int ret;
2818         int err = 0;
2819
2820         path = btrfs_alloc_path();
2821         if (!path)
2822                 return -ENOMEM;
2823
2824         rb_node = rb_first(blocks);
2825         while (rb_node) {
2826                 block = rb_entry(rb_node, struct tree_block, rb_node);
2827                 if (!block->key_ready)
2828                         reada_tree_block(rc, block);
2829                 rb_node = rb_next(rb_node);
2830         }
2831
2832         rb_node = rb_first(blocks);
2833         while (rb_node) {
2834                 block = rb_entry(rb_node, struct tree_block, rb_node);
2835                 if (!block->key_ready)
2836                         get_tree_block_key(rc, block);
2837                 rb_node = rb_next(rb_node);
2838         }
2839
2840         rb_node = rb_first(blocks);
2841         while (rb_node) {
2842                 block = rb_entry(rb_node, struct tree_block, rb_node);
2843
2844                 node = build_backref_tree(rc, &block->key,
2845                                           block->level, block->bytenr);
2846                 if (IS_ERR(node)) {
2847                         err = PTR_ERR(node);
2848                         goto out;
2849                 }
2850
2851                 ret = relocate_tree_block(trans, rc, node, &block->key,
2852                                           path);
2853                 if (ret < 0) {
2854                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2855                                 err = ret;
2856                         goto out;
2857                 }
2858                 rb_node = rb_next(rb_node);
2859         }
2860 out:
2861         free_block_list(blocks);
2862         err = finish_pending_nodes(trans, rc, path, err);
2863
2864         btrfs_free_path(path);
2865         return err;
2866 }
2867
2868 static noinline_for_stack
2869 int prealloc_file_extent_cluster(struct inode *inode,
2870                                  struct file_extent_cluster *cluster)
2871 {
2872         u64 alloc_hint = 0;
2873         u64 start;
2874         u64 end;
2875         u64 offset = BTRFS_I(inode)->index_cnt;
2876         u64 num_bytes;
2877         int nr = 0;
2878         int ret = 0;
2879
2880         BUG_ON(cluster->start != cluster->boundary[0]);
2881         mutex_lock(&inode->i_mutex);
2882
2883         ret = btrfs_check_data_free_space(inode, cluster->end +
2884                                           1 - cluster->start);
2885         if (ret)
2886                 goto out;
2887
2888         while (nr < cluster->nr) {
2889                 start = cluster->boundary[nr] - offset;
2890                 if (nr + 1 < cluster->nr)
2891                         end = cluster->boundary[nr + 1] - 1 - offset;
2892                 else
2893                         end = cluster->end - offset;
2894
2895                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2896                 num_bytes = end + 1 - start;
2897                 ret = btrfs_prealloc_file_range(inode, 0, start,
2898                                                 num_bytes, num_bytes,
2899                                                 end + 1, &alloc_hint);
2900                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2901                 if (ret)
2902                         break;
2903                 nr++;
2904         }
2905         btrfs_free_reserved_data_space(inode, cluster->end +
2906                                        1 - cluster->start);
2907 out:
2908         mutex_unlock(&inode->i_mutex);
2909         return ret;
2910 }
2911
2912 static noinline_for_stack
2913 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2914                          u64 block_start)
2915 {
2916         struct btrfs_root *root = BTRFS_I(inode)->root;
2917         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2918         struct extent_map *em;
2919         int ret = 0;
2920
2921         em = alloc_extent_map();
2922         if (!em)
2923                 return -ENOMEM;
2924
2925         em->start = start;
2926         em->len = end + 1 - start;
2927         em->block_len = em->len;
2928         em->block_start = block_start;
2929         em->bdev = root->fs_info->fs_devices->latest_bdev;
2930         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2931
2932         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2933         while (1) {
2934                 write_lock(&em_tree->lock);
2935                 ret = add_extent_mapping(em_tree, em);
2936                 write_unlock(&em_tree->lock);
2937                 if (ret != -EEXIST) {
2938                         free_extent_map(em);
2939                         break;
2940                 }
2941                 btrfs_drop_extent_cache(inode, start, end, 0);
2942         }
2943         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2944         return ret;
2945 }
2946
2947 static int relocate_file_extent_cluster(struct inode *inode,
2948                                         struct file_extent_cluster *cluster)
2949 {
2950         u64 page_start;
2951         u64 page_end;
2952         u64 offset = BTRFS_I(inode)->index_cnt;
2953         unsigned long index;
2954         unsigned long last_index;
2955         struct page *page;
2956         struct file_ra_state *ra;
2957         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
2958         int nr = 0;
2959         int ret = 0;
2960
2961         if (!cluster->nr)
2962                 return 0;
2963
2964         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2965         if (!ra)
2966                 return -ENOMEM;
2967
2968         ret = prealloc_file_extent_cluster(inode, cluster);
2969         if (ret)
2970                 goto out;
2971
2972         file_ra_state_init(ra, inode->i_mapping);
2973
2974         ret = setup_extent_mapping(inode, cluster->start - offset,
2975                                    cluster->end - offset, cluster->start);
2976         if (ret)
2977                 goto out;
2978
2979         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
2980         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
2981         while (index <= last_index) {
2982                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
2983                 if (ret)
2984                         goto out;
2985
2986                 page = find_lock_page(inode->i_mapping, index);
2987                 if (!page) {
2988                         page_cache_sync_readahead(inode->i_mapping,
2989                                                   ra, NULL, index,
2990                                                   last_index + 1 - index);
2991                         page = find_or_create_page(inode->i_mapping, index,
2992                                                    mask);
2993                         if (!page) {
2994                                 btrfs_delalloc_release_metadata(inode,
2995                                                         PAGE_CACHE_SIZE);
2996                                 ret = -ENOMEM;
2997                                 goto out;
2998                         }
2999                 }
3000
3001                 if (PageReadahead(page)) {
3002                         page_cache_async_readahead(inode->i_mapping,
3003                                                    ra, NULL, page, index,
3004                                                    last_index + 1 - index);
3005                 }
3006
3007                 if (!PageUptodate(page)) {
3008                         btrfs_readpage(NULL, page);
3009                         lock_page(page);
3010                         if (!PageUptodate(page)) {
3011                                 unlock_page(page);
3012                                 page_cache_release(page);
3013                                 btrfs_delalloc_release_metadata(inode,
3014                                                         PAGE_CACHE_SIZE);
3015                                 ret = -EIO;
3016                                 goto out;
3017                         }
3018                 }
3019
3020                 page_start = page_offset(page);
3021                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3022
3023                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3024
3025                 set_page_extent_mapped(page);
3026
3027                 if (nr < cluster->nr &&
3028                     page_start + offset == cluster->boundary[nr]) {
3029                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3030                                         page_start, page_end,
3031                                         EXTENT_BOUNDARY, GFP_NOFS);
3032                         nr++;
3033                 }
3034
3035                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3036                 set_page_dirty(page);
3037
3038                 unlock_extent(&BTRFS_I(inode)->io_tree,
3039                               page_start, page_end);
3040                 unlock_page(page);
3041                 page_cache_release(page);
3042
3043                 index++;
3044                 balance_dirty_pages_ratelimited(inode->i_mapping);
3045                 btrfs_throttle(BTRFS_I(inode)->root);
3046         }
3047         WARN_ON(nr != cluster->nr);
3048 out:
3049         kfree(ra);
3050         return ret;
3051 }
3052
3053 static noinline_for_stack
3054 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3055                          struct file_extent_cluster *cluster)
3056 {
3057         int ret;
3058
3059         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3060                 ret = relocate_file_extent_cluster(inode, cluster);
3061                 if (ret)
3062                         return ret;
3063                 cluster->nr = 0;
3064         }
3065
3066         if (!cluster->nr)
3067                 cluster->start = extent_key->objectid;
3068         else
3069                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3070         cluster->end = extent_key->objectid + extent_key->offset - 1;
3071         cluster->boundary[cluster->nr] = extent_key->objectid;
3072         cluster->nr++;
3073
3074         if (cluster->nr >= MAX_EXTENTS) {
3075                 ret = relocate_file_extent_cluster(inode, cluster);
3076                 if (ret)
3077                         return ret;
3078                 cluster->nr = 0;
3079         }
3080         return 0;
3081 }
3082
3083 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3084 static int get_ref_objectid_v0(struct reloc_control *rc,
3085                                struct btrfs_path *path,
3086                                struct btrfs_key *extent_key,
3087                                u64 *ref_objectid, int *path_change)
3088 {
3089         struct btrfs_key key;
3090         struct extent_buffer *leaf;
3091         struct btrfs_extent_ref_v0 *ref0;
3092         int ret;
3093         int slot;
3094
3095         leaf = path->nodes[0];
3096         slot = path->slots[0];
3097         while (1) {
3098                 if (slot >= btrfs_header_nritems(leaf)) {
3099                         ret = btrfs_next_leaf(rc->extent_root, path);
3100                         if (ret < 0)
3101                                 return ret;
3102                         BUG_ON(ret > 0);
3103                         leaf = path->nodes[0];
3104                         slot = path->slots[0];
3105                         if (path_change)
3106                                 *path_change = 1;
3107                 }
3108                 btrfs_item_key_to_cpu(leaf, &key, slot);
3109                 if (key.objectid != extent_key->objectid)
3110                         return -ENOENT;
3111
3112                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3113                         slot++;
3114                         continue;
3115                 }
3116                 ref0 = btrfs_item_ptr(leaf, slot,
3117                                 struct btrfs_extent_ref_v0);
3118                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3119                 break;
3120         }
3121         return 0;
3122 }
3123 #endif
3124
3125 /*
3126  * helper to add a tree block to the list.
3127  * the major work is getting the generation and level of the block
3128  */
3129 static int add_tree_block(struct reloc_control *rc,
3130                           struct btrfs_key *extent_key,
3131                           struct btrfs_path *path,
3132                           struct rb_root *blocks)
3133 {
3134         struct extent_buffer *eb;
3135         struct btrfs_extent_item *ei;
3136         struct btrfs_tree_block_info *bi;
3137         struct tree_block *block;
3138         struct rb_node *rb_node;
3139         u32 item_size;
3140         int level = -1;
3141         int generation;
3142
3143         eb =  path->nodes[0];
3144         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3145
3146         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3147                 ei = btrfs_item_ptr(eb, path->slots[0],
3148                                 struct btrfs_extent_item);
3149                 bi = (struct btrfs_tree_block_info *)(ei + 1);
3150                 generation = btrfs_extent_generation(eb, ei);
3151                 level = btrfs_tree_block_level(eb, bi);
3152         } else {
3153 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3154                 u64 ref_owner;
3155                 int ret;
3156
3157                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3158                 ret = get_ref_objectid_v0(rc, path, extent_key,
3159                                           &ref_owner, NULL);
3160                 if (ret < 0)
3161                         return ret;
3162                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3163                 level = (int)ref_owner;
3164                 /* FIXME: get real generation */
3165                 generation = 0;
3166 #else
3167                 BUG();
3168 #endif
3169         }
3170
3171         btrfs_release_path(path);
3172
3173         BUG_ON(level == -1);
3174
3175         block = kmalloc(sizeof(*block), GFP_NOFS);
3176         if (!block)
3177                 return -ENOMEM;
3178
3179         block->bytenr = extent_key->objectid;
3180         block->key.objectid = extent_key->offset;
3181         block->key.offset = generation;
3182         block->level = level;
3183         block->key_ready = 0;
3184
3185         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3186         if (rb_node)
3187                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3188
3189         return 0;
3190 }
3191
3192 /*
3193  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3194  */
3195 static int __add_tree_block(struct reloc_control *rc,
3196                             u64 bytenr, u32 blocksize,
3197                             struct rb_root *blocks)
3198 {
3199         struct btrfs_path *path;
3200         struct btrfs_key key;
3201         int ret;
3202
3203         if (tree_block_processed(bytenr, blocksize, rc))
3204                 return 0;
3205
3206         if (tree_search(blocks, bytenr))
3207                 return 0;
3208
3209         path = btrfs_alloc_path();
3210         if (!path)
3211                 return -ENOMEM;
3212
3213         key.objectid = bytenr;
3214         key.type = BTRFS_EXTENT_ITEM_KEY;
3215         key.offset = blocksize;
3216
3217         path->search_commit_root = 1;
3218         path->skip_locking = 1;
3219         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3220         if (ret < 0)
3221                 goto out;
3222         BUG_ON(ret);
3223
3224         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3225         ret = add_tree_block(rc, &key, path, blocks);
3226 out:
3227         btrfs_free_path(path);
3228         return ret;
3229 }
3230
3231 /*
3232  * helper to check if the block use full backrefs for pointers in it
3233  */
3234 static int block_use_full_backref(struct reloc_control *rc,
3235                                   struct extent_buffer *eb)
3236 {
3237         u64 flags;
3238         int ret;
3239
3240         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3241             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3242                 return 1;
3243
3244         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3245                                        eb->start, eb->len, NULL, &flags);
3246         BUG_ON(ret);
3247
3248         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3249                 ret = 1;
3250         else
3251                 ret = 0;
3252         return ret;
3253 }
3254
3255 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3256                                     struct inode *inode, u64 ino)
3257 {
3258         struct btrfs_key key;
3259         struct btrfs_path *path;
3260         struct btrfs_root *root = fs_info->tree_root;
3261         struct btrfs_trans_handle *trans;
3262         int ret = 0;
3263
3264         if (inode)
3265                 goto truncate;
3266
3267         key.objectid = ino;
3268         key.type = BTRFS_INODE_ITEM_KEY;
3269         key.offset = 0;
3270
3271         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3272         if (IS_ERR(inode) || is_bad_inode(inode)) {
3273                 if (!IS_ERR(inode))
3274                         iput(inode);
3275                 return -ENOENT;
3276         }
3277
3278 truncate:
3279         path = btrfs_alloc_path();
3280         if (!path) {
3281                 ret = -ENOMEM;
3282                 goto out;
3283         }
3284
3285         trans = btrfs_join_transaction(root);
3286         if (IS_ERR(trans)) {
3287                 btrfs_free_path(path);
3288                 ret = PTR_ERR(trans);
3289                 goto out;
3290         }
3291
3292         ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3293
3294         btrfs_free_path(path);
3295         btrfs_end_transaction(trans, root);
3296         btrfs_btree_balance_dirty(root);
3297 out:
3298         iput(inode);
3299         return ret;
3300 }
3301
3302 /*
3303  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3304  * this function scans fs tree to find blocks reference the data extent
3305  */
3306 static int find_data_references(struct reloc_control *rc,
3307                                 struct btrfs_key *extent_key,
3308                                 struct extent_buffer *leaf,
3309                                 struct btrfs_extent_data_ref *ref,
3310                                 struct rb_root *blocks)
3311 {
3312         struct btrfs_path *path;
3313         struct tree_block *block;
3314         struct btrfs_root *root;
3315         struct btrfs_file_extent_item *fi;
3316         struct rb_node *rb_node;
3317         struct btrfs_key key;
3318         u64 ref_root;
3319         u64 ref_objectid;
3320         u64 ref_offset;
3321         u32 ref_count;
3322         u32 nritems;
3323         int err = 0;
3324         int added = 0;
3325         int counted;
3326         int ret;
3327
3328         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3329         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3330         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3331         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3332
3333         /*
3334          * This is an extent belonging to the free space cache, lets just delete
3335          * it and redo the search.
3336          */
3337         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3338                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3339                                                NULL, ref_objectid);
3340                 if (ret != -ENOENT)
3341                         return ret;
3342                 ret = 0;
3343         }
3344
3345         path = btrfs_alloc_path();
3346         if (!path)
3347                 return -ENOMEM;
3348         path->reada = 1;
3349
3350         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3351         if (IS_ERR(root)) {
3352                 err = PTR_ERR(root);
3353                 goto out;
3354         }
3355
3356         key.objectid = ref_objectid;
3357         key.type = BTRFS_EXTENT_DATA_KEY;
3358         if (ref_offset > ((u64)-1 << 32))
3359                 key.offset = 0;
3360         else
3361                 key.offset = ref_offset;
3362
3363         path->search_commit_root = 1;
3364         path->skip_locking = 1;
3365         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3366         if (ret < 0) {
3367                 err = ret;
3368                 goto out;
3369         }
3370
3371         leaf = path->nodes[0];
3372         nritems = btrfs_header_nritems(leaf);
3373         /*
3374          * the references in tree blocks that use full backrefs
3375          * are not counted in
3376          */
3377         if (block_use_full_backref(rc, leaf))
3378                 counted = 0;
3379         else
3380                 counted = 1;
3381         rb_node = tree_search(blocks, leaf->start);
3382         if (rb_node) {
3383                 if (counted)
3384                         added = 1;
3385                 else
3386                         path->slots[0] = nritems;
3387         }
3388
3389         while (ref_count > 0) {
3390                 while (path->slots[0] >= nritems) {
3391                         ret = btrfs_next_leaf(root, path);
3392                         if (ret < 0) {
3393                                 err = ret;
3394                                 goto out;
3395                         }
3396                         if (ret > 0) {
3397                                 WARN_ON(1);
3398                                 goto out;
3399                         }
3400
3401                         leaf = path->nodes[0];
3402                         nritems = btrfs_header_nritems(leaf);
3403                         added = 0;
3404
3405                         if (block_use_full_backref(rc, leaf))
3406                                 counted = 0;
3407                         else
3408                                 counted = 1;
3409                         rb_node = tree_search(blocks, leaf->start);
3410                         if (rb_node) {
3411                                 if (counted)
3412                                         added = 1;
3413                                 else
3414                                         path->slots[0] = nritems;
3415                         }
3416                 }
3417
3418                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3419                 if (key.objectid != ref_objectid ||
3420                     key.type != BTRFS_EXTENT_DATA_KEY) {
3421                         WARN_ON(1);
3422                         break;
3423                 }
3424
3425                 fi = btrfs_item_ptr(leaf, path->slots[0],
3426                                     struct btrfs_file_extent_item);
3427
3428                 if (btrfs_file_extent_type(leaf, fi) ==
3429                     BTRFS_FILE_EXTENT_INLINE)
3430                         goto next;
3431
3432                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3433                     extent_key->objectid)
3434                         goto next;
3435
3436                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3437                 if (key.offset != ref_offset)
3438                         goto next;
3439
3440                 if (counted)
3441                         ref_count--;
3442                 if (added)
3443                         goto next;
3444
3445                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3446                         block = kmalloc(sizeof(*block), GFP_NOFS);
3447                         if (!block) {
3448                                 err = -ENOMEM;
3449                                 break;
3450                         }
3451                         block->bytenr = leaf->start;
3452                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3453                         block->level = 0;
3454                         block->key_ready = 1;
3455                         rb_node = tree_insert(blocks, block->bytenr,
3456                                               &block->rb_node);
3457                         if (rb_node)
3458                                 backref_tree_panic(rb_node, -EEXIST,
3459                                                    block->bytenr);
3460                 }
3461                 if (counted)
3462                         added = 1;
3463                 else
3464                         path->slots[0] = nritems;
3465 next:
3466                 path->slots[0]++;
3467
3468         }
3469 out:
3470         btrfs_free_path(path);
3471         return err;
3472 }
3473
3474 /*
3475  * helper to find all tree blocks that reference a given data extent
3476  */
3477 static noinline_for_stack
3478 int add_data_references(struct reloc_control *rc,
3479                         struct btrfs_key *extent_key,
3480                         struct btrfs_path *path,
3481                         struct rb_root *blocks)
3482 {
3483         struct btrfs_key key;
3484         struct extent_buffer *eb;
3485         struct btrfs_extent_data_ref *dref;
3486         struct btrfs_extent_inline_ref *iref;
3487         unsigned long ptr;
3488         unsigned long end;
3489         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3490         int ret;
3491         int err = 0;
3492
3493         eb = path->nodes[0];
3494         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3495         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3496 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3497         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3498                 ptr = end;
3499         else
3500 #endif
3501                 ptr += sizeof(struct btrfs_extent_item);
3502
3503         while (ptr < end) {
3504                 iref = (struct btrfs_extent_inline_ref *)ptr;
3505                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3506                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3507                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3508                         ret = __add_tree_block(rc, key.offset, blocksize,
3509                                                blocks);
3510                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3511                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3512                         ret = find_data_references(rc, extent_key,
3513                                                    eb, dref, blocks);
3514                 } else {
3515                         BUG();
3516                 }
3517                 ptr += btrfs_extent_inline_ref_size(key.type);
3518         }
3519         WARN_ON(ptr > end);
3520
3521         while (1) {
3522                 cond_resched();
3523                 eb = path->nodes[0];
3524                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3525                         ret = btrfs_next_leaf(rc->extent_root, path);
3526                         if (ret < 0) {
3527                                 err = ret;
3528                                 break;
3529                         }
3530                         if (ret > 0)
3531                                 break;
3532                         eb = path->nodes[0];
3533                 }
3534
3535                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3536                 if (key.objectid != extent_key->objectid)
3537                         break;
3538
3539 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3540                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3541                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3542 #else
3543                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3544                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3545 #endif
3546                         ret = __add_tree_block(rc, key.offset, blocksize,
3547                                                blocks);
3548                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3549                         dref = btrfs_item_ptr(eb, path->slots[0],
3550                                               struct btrfs_extent_data_ref);
3551                         ret = find_data_references(rc, extent_key,
3552                                                    eb, dref, blocks);
3553                 } else {
3554                         ret = 0;
3555                 }
3556                 if (ret) {
3557                         err = ret;
3558                         break;
3559                 }
3560                 path->slots[0]++;
3561         }
3562         btrfs_release_path(path);
3563         if (err)
3564                 free_block_list(blocks);
3565         return err;
3566 }
3567
3568 /*
3569  * helper to find next unprocessed extent
3570  */
3571 static noinline_for_stack
3572 int find_next_extent(struct btrfs_trans_handle *trans,
3573                      struct reloc_control *rc, struct btrfs_path *path,
3574                      struct btrfs_key *extent_key)
3575 {
3576         struct btrfs_key key;
3577         struct extent_buffer *leaf;
3578         u64 start, end, last;
3579         int ret;
3580
3581         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3582         while (1) {
3583                 cond_resched();
3584                 if (rc->search_start >= last) {
3585                         ret = 1;
3586                         break;
3587                 }
3588
3589                 key.objectid = rc->search_start;
3590                 key.type = BTRFS_EXTENT_ITEM_KEY;
3591                 key.offset = 0;
3592
3593                 path->search_commit_root = 1;
3594                 path->skip_locking = 1;
3595                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3596                                         0, 0);
3597                 if (ret < 0)
3598                         break;
3599 next:
3600                 leaf = path->nodes[0];
3601                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3602                         ret = btrfs_next_leaf(rc->extent_root, path);
3603                         if (ret != 0)
3604                                 break;
3605                         leaf = path->nodes[0];
3606                 }
3607
3608                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3609                 if (key.objectid >= last) {
3610                         ret = 1;
3611                         break;
3612                 }
3613
3614                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3615                     key.objectid + key.offset <= rc->search_start) {
3616                         path->slots[0]++;
3617                         goto next;
3618                 }
3619
3620                 ret = find_first_extent_bit(&rc->processed_blocks,
3621                                             key.objectid, &start, &end,
3622                                             EXTENT_DIRTY, NULL);
3623
3624                 if (ret == 0 && start <= key.objectid) {
3625                         btrfs_release_path(path);
3626                         rc->search_start = end + 1;
3627                 } else {
3628                         rc->search_start = key.objectid + key.offset;
3629                         memcpy(extent_key, &key, sizeof(key));
3630                         return 0;
3631                 }
3632         }
3633         btrfs_release_path(path);
3634         return ret;
3635 }
3636
3637 static void set_reloc_control(struct reloc_control *rc)
3638 {
3639         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3640
3641         mutex_lock(&fs_info->reloc_mutex);
3642         fs_info->reloc_ctl = rc;
3643         mutex_unlock(&fs_info->reloc_mutex);
3644 }
3645
3646 static void unset_reloc_control(struct reloc_control *rc)
3647 {
3648         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3649
3650         mutex_lock(&fs_info->reloc_mutex);
3651         fs_info->reloc_ctl = NULL;
3652         mutex_unlock(&fs_info->reloc_mutex);
3653 }
3654
3655 static int check_extent_flags(u64 flags)
3656 {
3657         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3658             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3659                 return 1;
3660         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3661             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3662                 return 1;
3663         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3664             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3665                 return 1;
3666         return 0;
3667 }
3668
3669 static noinline_for_stack
3670 int prepare_to_relocate(struct reloc_control *rc)
3671 {
3672         struct btrfs_trans_handle *trans;
3673         int ret;
3674
3675         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3676                                               BTRFS_BLOCK_RSV_TEMP);
3677         if (!rc->block_rsv)
3678                 return -ENOMEM;
3679
3680         /*
3681          * reserve some space for creating reloc trees.
3682          * btrfs_init_reloc_root will use them when there
3683          * is no reservation in transaction handle.
3684          */
3685         ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3686                                   rc->extent_root->nodesize * 256,
3687                                   BTRFS_RESERVE_FLUSH_ALL);
3688         if (ret)
3689                 return ret;
3690
3691         memset(&rc->cluster, 0, sizeof(rc->cluster));
3692         rc->search_start = rc->block_group->key.objectid;
3693         rc->extents_found = 0;
3694         rc->nodes_relocated = 0;
3695         rc->merging_rsv_size = 0;
3696
3697         rc->create_reloc_tree = 1;
3698         set_reloc_control(rc);
3699
3700         trans = btrfs_join_transaction(rc->extent_root);
3701         BUG_ON(IS_ERR(trans));
3702         btrfs_commit_transaction(trans, rc->extent_root);
3703         return 0;
3704 }
3705
3706 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3707 {
3708         struct rb_root blocks = RB_ROOT;
3709         struct btrfs_key key;
3710         struct btrfs_trans_handle *trans = NULL;
3711         struct btrfs_path *path;
3712         struct btrfs_extent_item *ei;
3713         u64 flags;
3714         u32 item_size;
3715         int ret;
3716         int err = 0;
3717         int progress = 0;
3718
3719         path = btrfs_alloc_path();
3720         if (!path)
3721                 return -ENOMEM;
3722         path->reada = 1;
3723
3724         ret = prepare_to_relocate(rc);
3725         if (ret) {
3726                 err = ret;
3727                 goto out_free;
3728         }
3729
3730         while (1) {
3731                 progress++;
3732                 trans = btrfs_start_transaction(rc->extent_root, 0);
3733                 BUG_ON(IS_ERR(trans));
3734 restart:
3735                 if (update_backref_cache(trans, &rc->backref_cache)) {
3736                         btrfs_end_transaction(trans, rc->extent_root);
3737                         continue;
3738                 }
3739
3740                 ret = find_next_extent(trans, rc, path, &key);
3741                 if (ret < 0)
3742                         err = ret;
3743                 if (ret != 0)
3744                         break;
3745
3746                 rc->extents_found++;
3747
3748                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3749                                     struct btrfs_extent_item);
3750                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3751                 if (item_size >= sizeof(*ei)) {
3752                         flags = btrfs_extent_flags(path->nodes[0], ei);
3753                         ret = check_extent_flags(flags);
3754                         BUG_ON(ret);
3755
3756                 } else {
3757 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3758                         u64 ref_owner;
3759                         int path_change = 0;
3760
3761                         BUG_ON(item_size !=
3762                                sizeof(struct btrfs_extent_item_v0));
3763                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3764                                                   &path_change);
3765                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3766                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3767                         else
3768                                 flags = BTRFS_EXTENT_FLAG_DATA;
3769
3770                         if (path_change) {
3771                                 btrfs_release_path(path);
3772
3773                                 path->search_commit_root = 1;
3774                                 path->skip_locking = 1;
3775                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3776                                                         &key, path, 0, 0);
3777                                 if (ret < 0) {
3778                                         err = ret;
3779                                         break;
3780                                 }
3781                                 BUG_ON(ret > 0);
3782                         }
3783 #else
3784                         BUG();
3785 #endif
3786                 }
3787
3788                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3789                         ret = add_tree_block(rc, &key, path, &blocks);
3790                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3791                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3792                         ret = add_data_references(rc, &key, path, &blocks);
3793                 } else {
3794                         btrfs_release_path(path);
3795                         ret = 0;
3796                 }
3797                 if (ret < 0) {
3798                         err = ret;
3799                         break;
3800                 }
3801
3802                 if (!RB_EMPTY_ROOT(&blocks)) {
3803                         ret = relocate_tree_blocks(trans, rc, &blocks);
3804                         if (ret < 0) {
3805                                 if (ret != -EAGAIN) {
3806                                         err = ret;
3807                                         break;
3808                                 }
3809                                 rc->extents_found--;
3810                                 rc->search_start = key.objectid;
3811                         }
3812                 }
3813
3814                 ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
3815                 if (ret < 0) {
3816                         if (ret != -ENOSPC) {
3817                                 err = ret;
3818                                 WARN_ON(1);
3819                                 break;
3820                         }
3821                         rc->commit_transaction = 1;
3822                 }
3823
3824                 if (rc->commit_transaction) {
3825                         rc->commit_transaction = 0;
3826                         ret = btrfs_commit_transaction(trans, rc->extent_root);
3827                         BUG_ON(ret);
3828                 } else {
3829                         btrfs_end_transaction_throttle(trans, rc->extent_root);
3830                         btrfs_btree_balance_dirty(rc->extent_root);
3831                 }
3832                 trans = NULL;
3833
3834                 if (rc->stage == MOVE_DATA_EXTENTS &&
3835                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3836                         rc->found_file_extent = 1;
3837                         ret = relocate_data_extent(rc->data_inode,
3838                                                    &key, &rc->cluster);
3839                         if (ret < 0) {
3840                                 err = ret;
3841                                 break;
3842                         }
3843                 }
3844         }
3845         if (trans && progress && err == -ENOSPC) {
3846                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
3847                                               rc->block_group->flags);
3848                 if (ret == 0) {
3849                         err = 0;
3850                         progress = 0;
3851                         goto restart;
3852                 }
3853         }
3854
3855         btrfs_release_path(path);
3856         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3857                           GFP_NOFS);
3858
3859         if (trans) {
3860                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3861                 btrfs_btree_balance_dirty(rc->extent_root);
3862         }
3863
3864         if (!err) {
3865                 ret = relocate_file_extent_cluster(rc->data_inode,
3866                                                    &rc->cluster);
3867                 if (ret < 0)
3868                         err = ret;
3869         }
3870
3871         rc->create_reloc_tree = 0;
3872         set_reloc_control(rc);
3873
3874         backref_cache_cleanup(&rc->backref_cache);
3875         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3876
3877         err = prepare_to_merge(rc, err);
3878
3879         merge_reloc_roots(rc);
3880
3881         rc->merge_reloc_tree = 0;
3882         unset_reloc_control(rc);
3883         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3884
3885         /* get rid of pinned extents */
3886         trans = btrfs_join_transaction(rc->extent_root);
3887         if (IS_ERR(trans))
3888                 err = PTR_ERR(trans);
3889         else
3890                 btrfs_commit_transaction(trans, rc->extent_root);
3891 out_free:
3892         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3893         btrfs_free_path(path);
3894         return err;
3895 }
3896
3897 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3898                                  struct btrfs_root *root, u64 objectid)
3899 {
3900         struct btrfs_path *path;
3901         struct btrfs_inode_item *item;
3902         struct extent_buffer *leaf;
3903         int ret;
3904
3905         path = btrfs_alloc_path();
3906         if (!path)
3907                 return -ENOMEM;
3908
3909         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3910         if (ret)
3911                 goto out;
3912
3913         leaf = path->nodes[0];
3914         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3915         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3916         btrfs_set_inode_generation(leaf, item, 1);
3917         btrfs_set_inode_size(leaf, item, 0);
3918         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3919         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3920                                           BTRFS_INODE_PREALLOC);
3921         btrfs_mark_buffer_dirty(leaf);
3922         btrfs_release_path(path);
3923 out:
3924         btrfs_free_path(path);
3925         return ret;
3926 }
3927
3928 /*
3929  * helper to create inode for data relocation.
3930  * the inode is in data relocation tree and its link count is 0
3931  */
3932 static noinline_for_stack
3933 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3934                                  struct btrfs_block_group_cache *group)
3935 {
3936         struct inode *inode = NULL;
3937         struct btrfs_trans_handle *trans;
3938         struct btrfs_root *root;
3939         struct btrfs_key key;
3940         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3941         int err = 0;
3942
3943         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3944         if (IS_ERR(root))
3945                 return ERR_CAST(root);
3946
3947         trans = btrfs_start_transaction(root, 6);
3948         if (IS_ERR(trans))
3949                 return ERR_CAST(trans);
3950
3951         err = btrfs_find_free_objectid(root, &objectid);
3952         if (err)
3953                 goto out;
3954
3955         err = __insert_orphan_inode(trans, root, objectid);
3956         BUG_ON(err);
3957
3958         key.objectid = objectid;
3959         key.type = BTRFS_INODE_ITEM_KEY;
3960         key.offset = 0;
3961         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3962         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3963         BTRFS_I(inode)->index_cnt = group->key.objectid;
3964
3965         err = btrfs_orphan_add(trans, inode);
3966 out:
3967         btrfs_end_transaction(trans, root);
3968         btrfs_btree_balance_dirty(root);
3969         if (err) {
3970                 if (inode)
3971                         iput(inode);
3972                 inode = ERR_PTR(err);
3973         }
3974         return inode;
3975 }
3976
3977 static struct reloc_control *alloc_reloc_control(void)
3978 {
3979         struct reloc_control *rc;
3980
3981         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3982         if (!rc)
3983                 return NULL;
3984
3985         INIT_LIST_HEAD(&rc->reloc_roots);
3986         backref_cache_init(&rc->backref_cache);
3987         mapping_tree_init(&rc->reloc_root_tree);
3988         extent_io_tree_init(&rc->processed_blocks, NULL);
3989         return rc;
3990 }
3991
3992 /*
3993  * function to relocate all extents in a block group.
3994  */
3995 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3996 {
3997         struct btrfs_fs_info *fs_info = extent_root->fs_info;
3998         struct reloc_control *rc;
3999         struct inode *inode;
4000         struct btrfs_path *path;
4001         int ret;
4002         int rw = 0;
4003         int err = 0;
4004
4005         rc = alloc_reloc_control();
4006         if (!rc)
4007                 return -ENOMEM;
4008
4009         rc->extent_root = extent_root;
4010
4011         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4012         BUG_ON(!rc->block_group);
4013
4014         if (!rc->block_group->ro) {
4015                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4016                 if (ret) {
4017                         err = ret;
4018                         goto out;
4019                 }
4020                 rw = 1;
4021         }
4022
4023         path = btrfs_alloc_path();
4024         if (!path) {
4025                 err = -ENOMEM;
4026                 goto out;
4027         }
4028
4029         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4030                                         path);
4031         btrfs_free_path(path);
4032
4033         if (!IS_ERR(inode))
4034                 ret = delete_block_group_cache(fs_info, inode, 0);
4035         else
4036                 ret = PTR_ERR(inode);
4037
4038         if (ret && ret != -ENOENT) {
4039                 err = ret;
4040                 goto out;
4041         }
4042
4043         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4044         if (IS_ERR(rc->data_inode)) {
4045                 err = PTR_ERR(rc->data_inode);
4046                 rc->data_inode = NULL;
4047                 goto out;
4048         }
4049
4050         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4051                (unsigned long long)rc->block_group->key.objectid,
4052                (unsigned long long)rc->block_group->flags);
4053
4054         ret = btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
4055         if (ret < 0) {
4056                 err = ret;
4057                 goto out;
4058         }
4059         btrfs_wait_ordered_extents(fs_info->tree_root, 0);
4060
4061         while (1) {
4062                 mutex_lock(&fs_info->cleaner_mutex);
4063
4064                 btrfs_clean_old_snapshots(fs_info->tree_root);
4065                 ret = relocate_block_group(rc);
4066
4067                 mutex_unlock(&fs_info->cleaner_mutex);
4068                 if (ret < 0) {
4069                         err = ret;
4070                         goto out;
4071                 }
4072
4073                 if (rc->extents_found == 0)
4074                         break;
4075
4076                 printk(KERN_INFO "btrfs: found %llu extents\n",
4077                         (unsigned long long)rc->extents_found);
4078
4079                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4080                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4081                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4082                                                  0, -1);
4083                         rc->stage = UPDATE_DATA_PTRS;
4084                 }
4085         }
4086
4087         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4088                                      rc->block_group->key.objectid,
4089                                      rc->block_group->key.objectid +
4090                                      rc->block_group->key.offset - 1);
4091
4092         WARN_ON(rc->block_group->pinned > 0);
4093         WARN_ON(rc->block_group->reserved > 0);
4094         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4095 out:
4096         if (err && rw)
4097                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4098         iput(rc->data_inode);
4099         btrfs_put_block_group(rc->block_group);
4100         kfree(rc);
4101         return err;
4102 }
4103
4104 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4105 {
4106         struct btrfs_trans_handle *trans;
4107         int ret, err;
4108
4109         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4110         if (IS_ERR(trans))
4111                 return PTR_ERR(trans);
4112
4113         memset(&root->root_item.drop_progress, 0,
4114                 sizeof(root->root_item.drop_progress));
4115         root->root_item.drop_level = 0;
4116         btrfs_set_root_refs(&root->root_item, 0);
4117         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4118                                 &root->root_key, &root->root_item);
4119
4120         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4121         if (err)
4122                 return err;
4123         return ret;
4124 }
4125
4126 /*
4127  * recover relocation interrupted by system crash.
4128  *
4129  * this function resumes merging reloc trees with corresponding fs trees.
4130  * this is important for keeping the sharing of tree blocks
4131  */
4132 int btrfs_recover_relocation(struct btrfs_root *root)
4133 {
4134         LIST_HEAD(reloc_roots);
4135         struct btrfs_key key;
4136         struct btrfs_root *fs_root;
4137         struct btrfs_root *reloc_root;
4138         struct btrfs_path *path;
4139         struct extent_buffer *leaf;
4140         struct reloc_control *rc = NULL;
4141         struct btrfs_trans_handle *trans;
4142         int ret;
4143         int err = 0;
4144
4145         path = btrfs_alloc_path();
4146         if (!path)
4147                 return -ENOMEM;
4148         path->reada = -1;
4149
4150         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4151         key.type = BTRFS_ROOT_ITEM_KEY;
4152         key.offset = (u64)-1;
4153
4154         while (1) {
4155                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4156                                         path, 0, 0);
4157                 if (ret < 0) {
4158                         err = ret;
4159                         goto out;
4160                 }
4161                 if (ret > 0) {
4162                         if (path->slots[0] == 0)
4163                                 break;
4164                         path->slots[0]--;
4165                 }
4166                 leaf = path->nodes[0];
4167                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4168                 btrfs_release_path(path);
4169
4170                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4171                     key.type != BTRFS_ROOT_ITEM_KEY)
4172                         break;
4173
4174                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4175                 if (IS_ERR(reloc_root)) {
4176                         err = PTR_ERR(reloc_root);
4177                         goto out;
4178                 }
4179
4180                 list_add(&reloc_root->root_list, &reloc_roots);
4181
4182                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4183                         fs_root = read_fs_root(root->fs_info,
4184                                                reloc_root->root_key.offset);
4185                         if (IS_ERR(fs_root)) {
4186                                 ret = PTR_ERR(fs_root);
4187                                 if (ret != -ENOENT) {
4188                                         err = ret;
4189                                         goto out;
4190                                 }
4191                                 ret = mark_garbage_root(reloc_root);
4192                                 if (ret < 0) {
4193                                         err = ret;
4194                                         goto out;
4195                                 }
4196                         }
4197                 }
4198
4199                 if (key.offset == 0)
4200                         break;
4201
4202                 key.offset--;
4203         }
4204         btrfs_release_path(path);
4205
4206         if (list_empty(&reloc_roots))
4207                 goto out;
4208
4209         rc = alloc_reloc_control();
4210         if (!rc) {
4211                 err = -ENOMEM;
4212                 goto out;
4213         }
4214
4215         rc->extent_root = root->fs_info->extent_root;
4216
4217         set_reloc_control(rc);
4218
4219         trans = btrfs_join_transaction(rc->extent_root);
4220         if (IS_ERR(trans)) {
4221                 unset_reloc_control(rc);
4222                 err = PTR_ERR(trans);
4223                 goto out_free;
4224         }
4225
4226         rc->merge_reloc_tree = 1;
4227
4228         while (!list_empty(&reloc_roots)) {
4229                 reloc_root = list_entry(reloc_roots.next,
4230                                         struct btrfs_root, root_list);
4231                 list_del(&reloc_root->root_list);
4232
4233                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4234                         list_add_tail(&reloc_root->root_list,
4235                                       &rc->reloc_roots);
4236                         continue;
4237                 }
4238
4239                 fs_root = read_fs_root(root->fs_info,
4240                                        reloc_root->root_key.offset);
4241                 if (IS_ERR(fs_root)) {
4242                         err = PTR_ERR(fs_root);
4243                         goto out_free;
4244                 }
4245
4246                 err = __add_reloc_root(reloc_root);
4247                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4248                 fs_root->reloc_root = reloc_root;
4249         }
4250
4251         err = btrfs_commit_transaction(trans, rc->extent_root);
4252         if (err)
4253                 goto out_free;
4254
4255         merge_reloc_roots(rc);
4256
4257         unset_reloc_control(rc);
4258
4259         trans = btrfs_join_transaction(rc->extent_root);
4260         if (IS_ERR(trans))
4261                 err = PTR_ERR(trans);
4262         else
4263                 err = btrfs_commit_transaction(trans, rc->extent_root);
4264 out_free:
4265         kfree(rc);
4266 out:
4267         while (!list_empty(&reloc_roots)) {
4268                 reloc_root = list_entry(reloc_roots.next,
4269                                         struct btrfs_root, root_list);
4270                 list_del(&reloc_root->root_list);
4271                 free_extent_buffer(reloc_root->node);
4272                 free_extent_buffer(reloc_root->commit_root);
4273                 kfree(reloc_root);
4274         }
4275         btrfs_free_path(path);
4276
4277         if (err == 0) {
4278                 /* cleanup orphan inode in data relocation tree */
4279                 fs_root = read_fs_root(root->fs_info,
4280                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4281                 if (IS_ERR(fs_root))
4282                         err = PTR_ERR(fs_root);
4283                 else
4284                         err = btrfs_orphan_cleanup(fs_root);
4285         }
4286         return err;
4287 }
4288
4289 /*
4290  * helper to add ordered checksum for data relocation.
4291  *
4292  * cloning checksum properly handles the nodatasum extents.
4293  * it also saves CPU time to re-calculate the checksum.
4294  */
4295 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4296 {
4297         struct btrfs_ordered_sum *sums;
4298         struct btrfs_sector_sum *sector_sum;
4299         struct btrfs_ordered_extent *ordered;
4300         struct btrfs_root *root = BTRFS_I(inode)->root;
4301         size_t offset;
4302         int ret;
4303         u64 disk_bytenr;
4304         LIST_HEAD(list);
4305
4306         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4307         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4308
4309         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4310         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4311                                        disk_bytenr + len - 1, &list, 0);
4312         if (ret)
4313                 goto out;
4314
4315         while (!list_empty(&list)) {
4316                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4317                 list_del_init(&sums->list);
4318
4319                 sector_sum = sums->sums;
4320                 sums->bytenr = ordered->start;
4321
4322                 offset = 0;
4323                 while (offset < sums->len) {
4324                         sector_sum->bytenr += ordered->start - disk_bytenr;
4325                         sector_sum++;
4326                         offset += root->sectorsize;
4327                 }
4328
4329                 btrfs_add_ordered_sum(inode, ordered, sums);
4330         }
4331 out:
4332         btrfs_put_ordered_extent(ordered);
4333         return ret;
4334 }
4335
4336 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4337                            struct btrfs_root *root, struct extent_buffer *buf,
4338                            struct extent_buffer *cow)
4339 {
4340         struct reloc_control *rc;
4341         struct backref_node *node;
4342         int first_cow = 0;
4343         int level;
4344         int ret;
4345
4346         rc = root->fs_info->reloc_ctl;
4347         if (!rc)
4348                 return;
4349
4350         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4351                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4352
4353         level = btrfs_header_level(buf);
4354         if (btrfs_header_generation(buf) <=
4355             btrfs_root_last_snapshot(&root->root_item))
4356                 first_cow = 1;
4357
4358         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4359             rc->create_reloc_tree) {
4360                 WARN_ON(!first_cow && level == 0);
4361
4362                 node = rc->backref_cache.path[level];
4363                 BUG_ON(node->bytenr != buf->start &&
4364                        node->new_bytenr != buf->start);
4365
4366                 drop_node_buffer(node);
4367                 extent_buffer_get(cow);
4368                 node->eb = cow;
4369                 node->new_bytenr = cow->start;
4370
4371                 if (!node->pending) {
4372                         list_move_tail(&node->list,
4373                                        &rc->backref_cache.pending[level]);
4374                         node->pending = 1;
4375                 }
4376
4377                 if (first_cow)
4378                         __mark_block_processed(rc, node);
4379
4380                 if (first_cow && level > 0)
4381                         rc->nodes_relocated += buf->len;
4382         }
4383
4384         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4385                 ret = replace_file_extents(trans, rc, root, cow);
4386                 BUG_ON(ret);
4387         }
4388 }
4389
4390 /*
4391  * called before creating snapshot. it calculates metadata reservation
4392  * requried for relocating tree blocks in the snapshot
4393  */
4394 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4395                               struct btrfs_pending_snapshot *pending,
4396                               u64 *bytes_to_reserve)
4397 {
4398         struct btrfs_root *root;
4399         struct reloc_control *rc;
4400
4401         root = pending->root;
4402         if (!root->reloc_root)
4403                 return;
4404
4405         rc = root->fs_info->reloc_ctl;
4406         if (!rc->merge_reloc_tree)
4407                 return;
4408
4409         root = root->reloc_root;
4410         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4411         /*
4412          * relocation is in the stage of merging trees. the space
4413          * used by merging a reloc tree is twice the size of
4414          * relocated tree nodes in the worst case. half for cowing
4415          * the reloc tree, half for cowing the fs tree. the space
4416          * used by cowing the reloc tree will be freed after the
4417          * tree is dropped. if we create snapshot, cowing the fs
4418          * tree may use more space than it frees. so we need
4419          * reserve extra space.
4420          */
4421         *bytes_to_reserve += rc->nodes_relocated;
4422 }
4423
4424 /*
4425  * called after snapshot is created. migrate block reservation
4426  * and create reloc root for the newly created snapshot
4427  */
4428 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4429                                struct btrfs_pending_snapshot *pending)
4430 {
4431         struct btrfs_root *root = pending->root;
4432         struct btrfs_root *reloc_root;
4433         struct btrfs_root *new_root;
4434         struct reloc_control *rc;
4435         int ret;
4436
4437         if (!root->reloc_root)
4438                 return 0;
4439
4440         rc = root->fs_info->reloc_ctl;
4441         rc->merging_rsv_size += rc->nodes_relocated;
4442
4443         if (rc->merge_reloc_tree) {
4444                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4445                                               rc->block_rsv,
4446                                               rc->nodes_relocated);
4447                 if (ret)
4448                         return ret;
4449         }
4450
4451         new_root = pending->snap;
4452         reloc_root = create_reloc_root(trans, root->reloc_root,
4453                                        new_root->root_key.objectid);
4454         if (IS_ERR(reloc_root))
4455                 return PTR_ERR(reloc_root);
4456
4457         ret = __add_reloc_root(reloc_root);
4458         BUG_ON(ret < 0);
4459         new_root->reloc_root = reloc_root;
4460
4461         if (rc->create_reloc_tree)
4462                 ret = clone_backref_node(trans, rc, root, reloc_root);
4463         return ret;
4464 }