kernel/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 #define RELOCATION_RESERVED_NODES       256
  98
  99 struct backref_cache {
 100         /* red black tree of all backref nodes in the cache */
 101         struct rb_root rb_root;
 102         /* for passing backref nodes to btrfs_reloc_cow_block */
 103         struct backref_node *path[BTRFS_MAX_LEVEL];
 104         /*
 105          * list of blocks that have been cowed but some block
 106          * pointers in upper level blocks may not reflect the
 107          * new location
 108          */
 109         struct list_head pending[BTRFS_MAX_LEVEL];
 110         /* list of backref nodes with no child node */
 111         struct list_head leaves;
 112         /* list of blocks that have been cowed in current transaction */
 113         struct list_head changed;
 114         /* list of detached backref node. */
 115         struct list_head detached;
 116
 117         u64 last_trans;
 118
 119         int nr_nodes;
 120         int nr_edges;
 121 };
 122
 123 /*
 124  * map address of tree root to tree
 125  */
 126 struct mapping_node {
 127         struct rb_node rb_node;
 128         u64 bytenr;
 129         void *data;
 130 };
 131
 132 struct mapping_tree {
 133         struct rb_root rb_root;
 134         spinlock_t lock;
 135 };
 136
 137 /*
 138  * present a tree block to process
 139  */
 140 struct tree_block {
 141         struct rb_node rb_node;
 142         u64 bytenr;
 143         struct btrfs_key key;
 144         unsigned int level:8;
 145         unsigned int key_ready:1;
 146 };
 147
 148 #define MAX_EXTENTS 128
 149
 150 struct file_extent_cluster {
 151         u64 start;
 152         u64 end;
 153         u64 boundary[MAX_EXTENTS];
 154         unsigned int nr;
 155 };
 156
 157 struct reloc_control {
 158         /* block group to relocate */
 159         struct btrfs_block_group_cache *block_group;
 160         /* extent tree */
 161         struct btrfs_root *extent_root;
 162         /* inode for moving data */
 163         struct inode *data_inode;
 164
 165         struct btrfs_block_rsv *block_rsv;
 166
 167         struct backref_cache backref_cache;
 168
 169         struct file_extent_cluster cluster;
 170         /* tree blocks have been processed */
 171         struct extent_io_tree processed_blocks;
 172         /* map start of tree root to corresponding reloc tree */
 173         struct mapping_tree reloc_root_tree;
 174         /* list of reloc trees */
 175         struct list_head reloc_roots;
 176         /* size of metadata reservation for merging reloc trees */
 177         u64 merging_rsv_size;
 178         /* size of relocated tree nodes */
 179         u64 nodes_relocated;
 180         /* reserved size for block group relocation*/
 181         u64 reserved_bytes;
 182
 183         u64 search_start;
 184         u64 extents_found;
 185
 186         unsigned int stage:8;
 187         unsigned int create_reloc_tree:1;
 188         unsigned int merge_reloc_tree:1;
 189         unsigned int found_file_extent:1;
 190 };
 191
 192 /* stages of data relocation */
 193 #define MOVE_DATA_EXTENTS       0
 194 #define UPDATE_DATA_PTRS        1
 195
 196 static void remove_backref_node(struct backref_cache *cache,
 197                                 struct backref_node *node);
 198 static void __mark_block_processed(struct reloc_control *rc,
 199                                    struct backref_node *node);
 200
 201 static void mapping_tree_init(struct mapping_tree *tree)
 202 {
 203         tree->rb_root = RB_ROOT;
 204         spin_lock_init(&tree->lock);
 205 }
 206
 207 static void backref_cache_init(struct backref_cache *cache)
 208 {
 209         int i;
 210         cache->rb_root = RB_ROOT;
 211         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 212                 INIT_LIST_HEAD(&cache->pending[i]);
 213         INIT_LIST_HEAD(&cache->changed);
 214         INIT_LIST_HEAD(&cache->detached);
 215         INIT_LIST_HEAD(&cache->leaves);
 216 }
 217
 218 static void backref_cache_cleanup(struct backref_cache *cache)
 219 {
 220         struct backref_node *node;
 221         int i;
 222
 223         while (!list_empty(&cache->detached)) {
 224                 node = list_entry(cache->detached.next,
 225                                   struct backref_node, list);
 226                 remove_backref_node(cache, node);
 227         }
 228
 229         while (!list_empty(&cache->leaves)) {
 230                 node = list_entry(cache->leaves.next,
 231                                   struct backref_node, lower);
 232                 remove_backref_node(cache, node);
 233         }
 234
 235         cache->last_trans = 0;
 236
 237         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 238                 BUG_ON(!list_empty(&cache->pending[i]));
 239         BUG_ON(!list_empty(&cache->changed));
 240         BUG_ON(!list_empty(&cache->detached));
 241         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 242         BUG_ON(cache->nr_nodes);
 243         BUG_ON(cache->nr_edges);
 244 }
 245
 246 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 247 {
 248         struct backref_node *node;
 249
 250         node = kzalloc(sizeof(*node), GFP_NOFS);
 251         if (node) {
 252                 INIT_LIST_HEAD(&node->list);
 253                 INIT_LIST_HEAD(&node->upper);
 254                 INIT_LIST_HEAD(&node->lower);
 255                 RB_CLEAR_NODE(&node->rb_node);
 256                 cache->nr_nodes++;
 257         }
 258         return node;
 259 }
 260
 261 static void free_backref_node(struct backref_cache *cache,
 262                               struct backref_node *node)
 263 {
 264         if (node) {
 265                 cache->nr_nodes--;
 266                 kfree(node);
 267         }
 268 }
 269
 270 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 271 {
 272         struct backref_edge *edge;
 273
 274         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 275         if (edge)
 276                 cache->nr_edges++;
 277         return edge;
 278 }
 279
 280 static void free_backref_edge(struct backref_cache *cache,
 281                               struct backref_edge *edge)
 282 {
 283         if (edge) {
 284                 cache->nr_edges--;
 285                 kfree(edge);
 286         }
 287 }
 288
 289 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 290                                    struct rb_node *node)
 291 {
 292         struct rb_node **p = &root->rb_node;
 293         struct rb_node *parent = NULL;
 294         struct tree_entry *entry;
 295
 296         while (*p) {
 297                 parent = *p;
 298                 entry = rb_entry(parent, struct tree_entry, rb_node);
 299
 300                 if (bytenr < entry->bytenr)
 301                         p = &(*p)->rb_left;
 302                 else if (bytenr > entry->bytenr)
 303                         p = &(*p)->rb_right;
 304                 else
 305                         return parent;
 306         }
 307
 308         rb_link_node(node, parent, p);
 309         rb_insert_color(node, root);
 310         return NULL;
 311 }
 312
 313 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 314 {
 315         struct rb_node *n = root->rb_node;
 316         struct tree_entry *entry;
 317
 318         while (n) {
 319                 entry = rb_entry(n, struct tree_entry, rb_node);
 320
 321                 if (bytenr < entry->bytenr)
 322                         n = n->rb_left;
 323                 else if (bytenr > entry->bytenr)
 324                         n = n->rb_right;
 325                 else
 326                         return n;
 327         }
 328         return NULL;
 329 }
 330
 331 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 332 {
 333
 334         struct btrfs_fs_info *fs_info = NULL;
 335         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 336                                               rb_node);
 337         if (bnode->root)
 338                 fs_info = bnode->root->fs_info;
 339         btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 340                     "found at offset %llu", bytenr);
 341 }
 342
 343 /*
 344  * walk up backref nodes until reach node presents tree root
 345  */
 346 static struct backref_node *walk_up_backref(struct backref_node *node,
 347                                             struct backref_edge *edges[],
 348                                             int *index)
 349 {
 350         struct backref_edge *edge;
 351         int idx = *index;
 352
 353         while (!list_empty(&node->upper)) {
 354                 edge = list_entry(node->upper.next,
 355                                   struct backref_edge, list[LOWER]);
 356                 edges[idx++] = edge;
 357                 node = edge->node[UPPER];
 358         }
 359         BUG_ON(node->detached);
 360         *index = idx;
 361         return node;
 362 }
 363
 364 /*
 365  * walk down backref nodes to find start of next reference path
 366  */
 367 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 368                                               int *index)
 369 {
 370         struct backref_edge *edge;
 371         struct backref_node *lower;
 372         int idx = *index;
 373
 374         while (idx > 0) {
 375                 edge = edges[idx - 1];
 376                 lower = edge->node[LOWER];
 377                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 378                         idx--;
 379                         continue;
 380                 }
 381                 edge = list_entry(edge->list[LOWER].next,
 382                                   struct backref_edge, list[LOWER]);
 383                 edges[idx - 1] = edge;
 384                 *index = idx;
 385                 return edge->node[UPPER];
 386         }
 387         *index = 0;
 388         return NULL;
 389 }
 390
 391 static void unlock_node_buffer(struct backref_node *node)
 392 {
 393         if (node->locked) {
 394                 btrfs_tree_unlock(node->eb);
 395                 node->locked = 0;
 396         }
 397 }
 398
 399 static void drop_node_buffer(struct backref_node *node)
 400 {
 401         if (node->eb) {
 402                 unlock_node_buffer(node);
 403                 free_extent_buffer(node->eb);
 404                 node->eb = NULL;
 405         }
 406 }
 407
 408 static void drop_backref_node(struct backref_cache *tree,
 409                               struct backref_node *node)
 410 {
 411         BUG_ON(!list_empty(&node->upper));
 412
 413         drop_node_buffer(node);
 414         list_del(&node->list);
 415         list_del(&node->lower);
 416         if (!RB_EMPTY_NODE(&node->rb_node))
 417                 rb_erase(&node->rb_node, &tree->rb_root);
 418         free_backref_node(tree, node);
 419 }
 420
 421 /*
 422  * remove a backref node from the backref cache
 423  */
 424 static void remove_backref_node(struct backref_cache *cache,
 425                                 struct backref_node *node)
 426 {
 427         struct backref_node *upper;
 428         struct backref_edge *edge;
 429
 430         if (!node)
 431                 return;
 432
 433         BUG_ON(!node->lowest && !node->detached);
 434         while (!list_empty(&node->upper)) {
 435                 edge = list_entry(node->upper.next, struct backref_edge,
 436                                   list[LOWER]);
 437                 upper = edge->node[UPPER];
 438                 list_del(&edge->list[LOWER]);
 439                 list_del(&edge->list[UPPER]);
 440                 free_backref_edge(cache, edge);
 441
 442                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 443                         BUG_ON(!list_empty(&node->upper));
 444                         drop_backref_node(cache, node);
 445                         node = upper;
 446                         node->lowest = 1;
 447                         continue;
 448                 }
 449                 /*
 450                  * add the node to leaf node list if no other
 451                  * child block cached.
 452                  */
 453                 if (list_empty(&upper->lower)) {
 454                         list_add_tail(&upper->lower, &cache->leaves);
 455                         upper->lowest = 1;
 456                 }
 457         }
 458
 459         drop_backref_node(cache, node);
 460 }
 461
 462 static void update_backref_node(struct backref_cache *cache,
 463                                 struct backref_node *node, u64 bytenr)
 464 {
 465         struct rb_node *rb_node;
 466         rb_erase(&node->rb_node, &cache->rb_root);
 467         node->bytenr = bytenr;
 468         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 469         if (rb_node)
 470                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 471 }
 472
 473 /*
 474  * update backref cache after a transaction commit
 475  */
 476 static int update_backref_cache(struct btrfs_trans_handle *trans,
 477                                 struct backref_cache *cache)
 478 {
 479         struct backref_node *node;
 480         int level = 0;
 481
 482         if (cache->last_trans == 0) {
 483                 cache->last_trans = trans->transid;
 484                 return 0;
 485         }
 486
 487         if (cache->last_trans == trans->transid)
 488                 return 0;
 489
 490         /*
 491          * detached nodes are used to avoid unnecessary backref
 492          * lookup. transaction commit changes the extent tree.
 493          * so the detached nodes are no longer useful.
 494          */
 495         while (!list_empty(&cache->detached)) {
 496                 node = list_entry(cache->detached.next,
 497                                   struct backref_node, list);
 498                 remove_backref_node(cache, node);
 499         }
 500
 501         while (!list_empty(&cache->changed)) {
 502                 node = list_entry(cache->changed.next,
 503                                   struct backref_node, list);
 504                 list_del_init(&node->list);
 505                 BUG_ON(node->pending);
 506                 update_backref_node(cache, node, node->new_bytenr);
 507         }
 508
 509         /*
 510          * some nodes can be left in the pending list if there were
 511          * errors during processing the pending nodes.
 512          */
 513         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 514                 list_for_each_entry(node, &cache->pending[level], list) {
 515                         BUG_ON(!node->pending);
 516                         if (node->bytenr == node->new_bytenr)
 517                                 continue;
 518                         update_backref_node(cache, node, node->new_bytenr);
 519                 }
 520         }
 521
 522         cache->last_trans = 0;
 523         return 1;
 524 }
 525
 526
 527 static int should_ignore_root(struct btrfs_root *root)
 528 {
 529         struct btrfs_root *reloc_root;
 530
 531         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 532                 return 0;
 533
 534         reloc_root = root->reloc_root;
 535         if (!reloc_root)
 536                 return 0;
 537
 538         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 539             root->fs_info->running_transaction->transid - 1)
 540                 return 0;
 541         /*
 542          * if there is reloc tree and it was created in previous
 543          * transaction backref lookup can find the reloc tree,
 544          * so backref node for the fs tree root is useless for
 545          * relocation.
 546          */
 547         return 1;
 548 }
 549 /*
 550  * find reloc tree by address of tree root
 551  */
 552 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 553                                           u64 bytenr)
 554 {
 555         struct rb_node *rb_node;
 556         struct mapping_node *node;
 557         struct btrfs_root *root = NULL;
 558
 559         spin_lock(&rc->reloc_root_tree.lock);
 560         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 561         if (rb_node) {
 562                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 563                 root = (struct btrfs_root *)node->data;
 564         }
 565         spin_unlock(&rc->reloc_root_tree.lock);
 566         return root;
 567 }
 568
 569 static int is_cowonly_root(u64 root_objectid)
 570 {
 571         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 572             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 573             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 574             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 575             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 576             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 577             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 578             root_objectid == BTRFS_QUOTA_TREE_OBJECTID)
 579                 return 1;
 580         return 0;
 581 }
 582
 583 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 584                                         u64 root_objectid)
 585 {
 586         struct btrfs_key key;
 587
 588         key.objectid = root_objectid;
 589         key.type = BTRFS_ROOT_ITEM_KEY;
 590         if (is_cowonly_root(root_objectid))
 591                 key.offset = 0;
 592         else
 593                 key.offset = (u64)-1;
 594
 595         return btrfs_get_fs_root(fs_info, &key, false);
 596 }
 597
 598 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 599 static noinline_for_stack
 600 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 601                                   struct extent_buffer *leaf,
 602                                   struct btrfs_extent_ref_v0 *ref0)
 603 {
 604         struct btrfs_root *root;
 605         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 606         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 607
 608         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 609
 610         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 611         BUG_ON(IS_ERR(root));
 612
 613         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 614             generation != btrfs_root_generation(&root->root_item))
 615                 return NULL;
 616
 617         return root;
 618 }
 619 #endif
 620
 621 static noinline_for_stack
 622 int find_inline_backref(struct extent_buffer *leaf, int slot,
 623                         unsigned long *ptr, unsigned long *end)
 624 {
 625         struct btrfs_key key;
 626         struct btrfs_extent_item *ei;
 627         struct btrfs_tree_block_info *bi;
 628         u32 item_size;
 629
 630         btrfs_item_key_to_cpu(leaf, &key, slot);
 631
 632         item_size = btrfs_item_size_nr(leaf, slot);
 633 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 634         if (item_size < sizeof(*ei)) {
 635                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 636                 return 1;
 637         }
 638 #endif
 639         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 640         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 641                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 642
 643         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 644             item_size <= sizeof(*ei) + sizeof(*bi)) {
 645                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 646                 return 1;
 647         }
 648         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 649             item_size <= sizeof(*ei)) {
 650                 WARN_ON(item_size < sizeof(*ei));
 651                 return 1;
 652         }
 653
 654         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 655                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 656                 *ptr = (unsigned long)(bi + 1);
 657         } else {
 658                 *ptr = (unsigned long)(ei + 1);
 659         }
 660         *end = (unsigned long)ei + item_size;
 661         return 0;
 662 }
 663
 664 /*
 665  * build backref tree for a given tree block. root of the backref tree
 666  * corresponds the tree block, leaves of the backref tree correspond
 667  * roots of b-trees that reference the tree block.
 668  *
 669  * the basic idea of this function is check backrefs of a given block
 670  * to find upper level blocks that refernece the block, and then check
 671  * bakcrefs of these upper level blocks recursively. the recursion stop
 672  * when tree root is reached or backrefs for the block is cached.
 673  *
 674  * NOTE: if we find backrefs for a block are cached, we know backrefs
 675  * for all upper level blocks that directly/indirectly reference the
 676  * block are also cached.
 677  */
 678 static noinline_for_stack
 679 struct backref_node *build_backref_tree(struct reloc_control *rc,
 680                                         struct btrfs_key *node_key,
 681                                         int level, u64 bytenr)
 682 {
 683         struct backref_cache *cache = &rc->backref_cache;
 684         struct btrfs_path *path1;
 685         struct btrfs_path *path2;
 686         struct extent_buffer *eb;
 687         struct btrfs_root *root;
 688         struct backref_node *cur;
 689         struct backref_node *upper;
 690         struct backref_node *lower;
 691         struct backref_node *node = NULL;
 692         struct backref_node *exist = NULL;
 693         struct backref_edge *edge;
 694         struct rb_node *rb_node;
 695         struct btrfs_key key;
 696         unsigned long end;
 697         unsigned long ptr;
 698         LIST_HEAD(list);
 699         LIST_HEAD(useless);
 700         int cowonly;
 701         int ret;
 702         int err = 0;
 703         bool need_check = true;
 704
 705         path1 = btrfs_alloc_path();
 706         path2 = btrfs_alloc_path();
 707         if (!path1 || !path2) {
 708                 err = -ENOMEM;
 709                 goto out;
 710         }
 711         path1->reada = 1;
 712         path2->reada = 2;
 713
 714         node = alloc_backref_node(cache);
 715         if (!node) {
 716                 err = -ENOMEM;
 717                 goto out;
 718         }
 719
 720         node->bytenr = bytenr;
 721         node->level = level;
 722         node->lowest = 1;
 723         cur = node;
 724 again:
 725         end = 0;
 726         ptr = 0;
 727         key.objectid = cur->bytenr;
 728         key.type = BTRFS_METADATA_ITEM_KEY;
 729         key.offset = (u64)-1;
 730
 731         path1->search_commit_root = 1;
 732         path1->skip_locking = 1;
 733         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 734                                 0, 0);
 735         if (ret < 0) {
 736                 err = ret;
 737                 goto out;
 738         }
 739         ASSERT(ret);
 740         ASSERT(path1->slots[0]);
 741
 742         path1->slots[0]--;
 743
 744         WARN_ON(cur->checked);
 745         if (!list_empty(&cur->upper)) {
 746                 /*
 747                  * the backref was added previously when processing
 748                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 749                  */
 750                 ASSERT(list_is_singular(&cur->upper));
 751                 edge = list_entry(cur->upper.next, struct backref_edge,
 752                                   list[LOWER]);
 753                 ASSERT(list_empty(&edge->list[UPPER]));
 754                 exist = edge->node[UPPER];
 755                 /*
 756                  * add the upper level block to pending list if we need
 757                  * check its backrefs
 758                  */
 759                 if (!exist->checked)
 760                         list_add_tail(&edge->list[UPPER], &list);
 761         } else {
 762                 exist = NULL;
 763         }
 764
 765         while (1) {
 766                 cond_resched();
 767                 eb = path1->nodes[0];
 768
 769                 if (ptr >= end) {
 770                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 771                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 772                                 if (ret < 0) {
 773                                         err = ret;
 774                                         goto out;
 775                                 }
 776                                 if (ret > 0)
 777                                         break;
 778                                 eb = path1->nodes[0];
 779                         }
 780
 781                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 782                         if (key.objectid != cur->bytenr) {
 783                                 WARN_ON(exist);
 784                                 break;
 785                         }
 786
 787                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 788                             key.type == BTRFS_METADATA_ITEM_KEY) {
 789                                 ret = find_inline_backref(eb, path1->slots[0],
 790                                                           &ptr, &end);
 791                                 if (ret)
 792                                         goto next;
 793                         }
 794                 }
 795
 796                 if (ptr < end) {
 797                         /* update key for inline back ref */
 798                         struct btrfs_extent_inline_ref *iref;
 799                         iref = (struct btrfs_extent_inline_ref *)ptr;
 800                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 801                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 802                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 803                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 804                 }
 805
 806                 if (exist &&
 807                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 808                       exist->owner == key.offset) ||
 809                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 810                       exist->bytenr == key.offset))) {
 811                         exist = NULL;
 812                         goto next;
 813                 }
 814
 815 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 816                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 817                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 818                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 819                                 struct btrfs_extent_ref_v0 *ref0;
 820                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 821                                                 struct btrfs_extent_ref_v0);
 822                                 if (key.objectid == key.offset) {
 823                                         root = find_tree_root(rc, eb, ref0);
 824                                         if (root && !should_ignore_root(root))
 825                                                 cur->root = root;
 826                                         else
 827                                                 list_add(&cur->list, &useless);
 828                                         break;
 829                                 }
 830                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 831                                                                       ref0)))
 832                                         cur->cowonly = 1;
 833                         }
 834 #else
 835                 ASSERT(key.type != BTRFS_EXTENT_REF_V0_KEY);
 836                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 837 #endif
 838                         if (key.objectid == key.offset) {
 839                                 /*
 840                                  * only root blocks of reloc trees use
 841                                  * backref of this type.
 842                                  */
 843                                 root = find_reloc_root(rc, cur->bytenr);
 844                                 ASSERT(root);
 845                                 cur->root = root;
 846                                 break;
 847                         }
 848
 849                         edge = alloc_backref_edge(cache);
 850                         if (!edge) {
 851                                 err = -ENOMEM;
 852                                 goto out;
 853                         }
 854                         rb_node = tree_search(&cache->rb_root, key.offset);
 855                         if (!rb_node) {
 856                                 upper = alloc_backref_node(cache);
 857                                 if (!upper) {
 858                                         free_backref_edge(cache, edge);
 859                                         err = -ENOMEM;
 860                                         goto out;
 861                                 }
 862                                 upper->bytenr = key.offset;
 863                                 upper->level = cur->level + 1;
 864                                 /*
 865                                  *  backrefs for the upper level block isn't
 866                                  *  cached, add the block to pending list
 867                                  */
 868                                 list_add_tail(&edge->list[UPPER], &list);
 869                         } else {
 870                                 upper = rb_entry(rb_node, struct backref_node,
 871                                                  rb_node);
 872                                 ASSERT(upper->checked);
 873                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 874                         }
 875                         list_add_tail(&edge->list[LOWER], &cur->upper);
 876                         edge->node[LOWER] = cur;
 877                         edge->node[UPPER] = upper;
 878
 879                         goto next;
 880                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 881                         goto next;
 882                 }
 883
 884                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 885                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 886                 if (IS_ERR(root)) {
 887                         err = PTR_ERR(root);
 888                         goto out;
 889                 }
 890
 891                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 892                         cur->cowonly = 1;
 893
 894                 if (btrfs_root_level(&root->root_item) == cur->level) {
 895                         /* tree root */
 896                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
 897                                cur->bytenr);
 898                         if (should_ignore_root(root))
 899                                 list_add(&cur->list, &useless);
 900                         else
 901                                 cur->root = root;
 902                         break;
 903                 }
 904
 905                 level = cur->level + 1;
 906
 907                 /*
 908                  * searching the tree to find upper level blocks
 909                  * reference the block.
 910                  */
 911                 path2->search_commit_root = 1;
 912                 path2->skip_locking = 1;
 913                 path2->lowest_level = level;
 914                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 915                 path2->lowest_level = 0;
 916                 if (ret < 0) {
 917                         err = ret;
 918                         goto out;
 919                 }
 920                 if (ret > 0 && path2->slots[level] > 0)
 921                         path2->slots[level]--;
 922
 923                 eb = path2->nodes[level];
 924                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
 925                     cur->bytenr) {
 926                         btrfs_err(root->fs_info,
 927         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
 928                                   cur->bytenr, level - 1, root->objectid,
 929                                   node_key->objectid, node_key->type,
 930                                   node_key->offset);
 931                         err = -ENOENT;
 932                         goto out;
 933                 }
 934                 lower = cur;
 935                 need_check = true;
 936                 for (; level < BTRFS_MAX_LEVEL; level++) {
 937                         if (!path2->nodes[level]) {
 938                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
 939                                        lower->bytenr);
 940                                 if (should_ignore_root(root))
 941                                         list_add(&lower->list, &useless);
 942                                 else
 943                                         lower->root = root;
 944                                 break;
 945                         }
 946
 947                         edge = alloc_backref_edge(cache);
 948                         if (!edge) {
 949                                 err = -ENOMEM;
 950                                 goto out;
 951                         }
 952
 953                         eb = path2->nodes[level];
 954                         rb_node = tree_search(&cache->rb_root, eb->start);
 955                         if (!rb_node) {
 956                                 upper = alloc_backref_node(cache);
 957                                 if (!upper) {
 958                                         free_backref_edge(cache, edge);
 959                                         err = -ENOMEM;
 960                                         goto out;
 961                                 }
 962                                 upper->bytenr = eb->start;
 963                                 upper->owner = btrfs_header_owner(eb);
 964                                 upper->level = lower->level + 1;
 965                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 966                                               &root->state))
 967                                         upper->cowonly = 1;
 968
 969                                 /*
 970                                  * if we know the block isn't shared
 971                                  * we can void checking its backrefs.
 972                                  */
 973                                 if (btrfs_block_can_be_shared(root, eb))
 974                                         upper->checked = 0;
 975                                 else
 976                                         upper->checked = 1;
 977
 978                                 /*
 979                                  * add the block to pending list if we
 980                                  * need check its backrefs, we only do this once
 981                                  * while walking up a tree as we will catch
 982                                  * anything else later on.
 983                                  */
 984                                 if (!upper->checked && need_check) {
 985                                         need_check = false;
 986                                         list_add_tail(&edge->list[UPPER],
 987                                                       &list);
 988                                 } else {
 989                                         if (upper->checked)
 990                                                 need_check = true;
 991                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 992                                 }
 993                         } else {
 994                                 upper = rb_entry(rb_node, struct backref_node,
 995                                                  rb_node);
 996                                 ASSERT(upper->checked);
 997                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 998                                 if (!upper->owner)
 999                                         upper->owner = btrfs_header_owner(eb);
1000                         }
1001                         list_add_tail(&edge->list[LOWER], &lower->upper);
1002                         edge->node[LOWER] = lower;
1003                         edge->node[UPPER] = upper;
1004
1005                         if (rb_node)
1006                                 break;
1007                         lower = upper;
1008                         upper = NULL;
1009                 }
1010                 btrfs_release_path(path2);
1011 next:
1012                 if (ptr < end) {
1013                         ptr += btrfs_extent_inline_ref_size(key.type);
1014                         if (ptr >= end) {
1015                                 WARN_ON(ptr > end);
1016                                 ptr = 0;
1017                                 end = 0;
1018                         }
1019                 }
1020                 if (ptr >= end)
1021                         path1->slots[0]++;
1022         }
1023         btrfs_release_path(path1);
1024
1025         cur->checked = 1;
1026         WARN_ON(exist);
1027
1028         /* the pending list isn't empty, take the first block to process */
1029         if (!list_empty(&list)) {
1030                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1031                 list_del_init(&edge->list[UPPER]);
1032                 cur = edge->node[UPPER];
1033                 goto again;
1034         }
1035
1036         /*
1037          * everything goes well, connect backref nodes and insert backref nodes
1038          * into the cache.
1039          */
1040         ASSERT(node->checked);
1041         cowonly = node->cowonly;
1042         if (!cowonly) {
1043                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1044                                       &node->rb_node);
1045                 if (rb_node)
1046                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1047                 list_add_tail(&node->lower, &cache->leaves);
1048         }
1049
1050         list_for_each_entry(edge, &node->upper, list[LOWER])
1051                 list_add_tail(&edge->list[UPPER], &list);
1052
1053         while (!list_empty(&list)) {
1054                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1055                 list_del_init(&edge->list[UPPER]);
1056                 upper = edge->node[UPPER];
1057                 if (upper->detached) {
1058                         list_del(&edge->list[LOWER]);
1059                         lower = edge->node[LOWER];
1060                         free_backref_edge(cache, edge);
1061                         if (list_empty(&lower->upper))
1062                                 list_add(&lower->list, &useless);
1063                         continue;
1064                 }
1065
1066                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1067                         if (upper->lowest) {
1068                                 list_del_init(&upper->lower);
1069                                 upper->lowest = 0;
1070                         }
1071
1072                         list_add_tail(&edge->list[UPPER], &upper->lower);
1073                         continue;
1074                 }
1075
1076                 if (!upper->checked) {
1077                         /*
1078                          * Still want to blow up for developers since this is a
1079                          * logic bug.
1080                          */
1081                         ASSERT(0);
1082                         err = -EINVAL;
1083                         goto out;
1084                 }
1085                 if (cowonly != upper->cowonly) {
1086                         ASSERT(0);
1087                         err = -EINVAL;
1088                         goto out;
1089                 }
1090
1091                 if (!cowonly) {
1092                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1093                                               &upper->rb_node);
1094                         if (rb_node)
1095                                 backref_tree_panic(rb_node, -EEXIST,
1096                                                    upper->bytenr);
1097                 }
1098
1099                 list_add_tail(&edge->list[UPPER], &upper->lower);
1100
1101                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1102                         list_add_tail(&edge->list[UPPER], &list);
1103         }
1104         /*
1105          * process useless backref nodes. backref nodes for tree leaves
1106          * are deleted from the cache. backref nodes for upper level
1107          * tree blocks are left in the cache to avoid unnecessary backref
1108          * lookup.
1109          */
1110         while (!list_empty(&useless)) {
1111                 upper = list_entry(useless.next, struct backref_node, list);
1112                 list_del_init(&upper->list);
1113                 ASSERT(list_empty(&upper->upper));
1114                 if (upper == node)
1115                         node = NULL;
1116                 if (upper->lowest) {
1117                         list_del_init(&upper->lower);
1118                         upper->lowest = 0;
1119                 }
1120                 while (!list_empty(&upper->lower)) {
1121                         edge = list_entry(upper->lower.next,
1122                                           struct backref_edge, list[UPPER]);
1123                         list_del(&edge->list[UPPER]);
1124                         list_del(&edge->list[LOWER]);
1125                         lower = edge->node[LOWER];
1126                         free_backref_edge(cache, edge);
1127
1128                         if (list_empty(&lower->upper))
1129                                 list_add(&lower->list, &useless);
1130                 }
1131                 __mark_block_processed(rc, upper);
1132                 if (upper->level > 0) {
1133                         list_add(&upper->list, &cache->detached);
1134                         upper->detached = 1;
1135                 } else {
1136                         rb_erase(&upper->rb_node, &cache->rb_root);
1137                         free_backref_node(cache, upper);
1138                 }
1139         }
1140 out:
1141         btrfs_free_path(path1);
1142         btrfs_free_path(path2);
1143         if (err) {
1144                 while (!list_empty(&useless)) {
1145                         lower = list_entry(useless.next,
1146                                            struct backref_node, list);
1147                         list_del_init(&lower->list);
1148                 }
1149                 while (!list_empty(&list)) {
1150                         edge = list_first_entry(&list, struct backref_edge,
1151                                                 list[UPPER]);
1152                         list_del(&edge->list[UPPER]);
1153                         list_del(&edge->list[LOWER]);
1154                         lower = edge->node[LOWER];
1155                         upper = edge->node[UPPER];
1156                         free_backref_edge(cache, edge);
1157
1158                         /*
1159                          * Lower is no longer linked to any upper backref nodes
1160                          * and isn't in the cache, we can free it ourselves.
1161                          */
1162                         if (list_empty(&lower->upper) &&
1163                             RB_EMPTY_NODE(&lower->rb_node))
1164                                 list_add(&lower->list, &useless);
1165
1166                         if (!RB_EMPTY_NODE(&upper->rb_node))
1167                                 continue;
1168
1169                         /* Add this guy's upper edges to the list to proces */
1170                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1171                                 list_add_tail(&edge->list[UPPER], &list);
1172                         if (list_empty(&upper->upper))
1173                                 list_add(&upper->list, &useless);
1174                 }
1175
1176                 while (!list_empty(&useless)) {
1177                         lower = list_entry(useless.next,
1178                                            struct backref_node, list);
1179                         list_del_init(&lower->list);
1180                         free_backref_node(cache, lower);
1181                 }
1182                 return ERR_PTR(err);
1183         }
1184         ASSERT(!node || !node->detached);
1185         return node;
1186 }
1187
1188 /*
1189  * helper to add backref node for the newly created snapshot.
1190  * the backref node is created by cloning backref node that
1191  * corresponds to root of source tree
1192  */
1193 static int clone_backref_node(struct btrfs_trans_handle *trans,
1194                               struct reloc_control *rc,
1195                               struct btrfs_root *src,
1196                               struct btrfs_root *dest)
1197 {
1198         struct btrfs_root *reloc_root = src->reloc_root;
1199         struct backref_cache *cache = &rc->backref_cache;
1200         struct backref_node *node = NULL;
1201         struct backref_node *new_node;
1202         struct backref_edge *edge;
1203         struct backref_edge *new_edge;
1204         struct rb_node *rb_node;
1205
1206         if (cache->last_trans > 0)
1207                 update_backref_cache(trans, cache);
1208
1209         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1210         if (rb_node) {
1211                 node = rb_entry(rb_node, struct backref_node, rb_node);
1212                 if (node->detached)
1213                         node = NULL;
1214                 else
1215                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1216         }
1217
1218         if (!node) {
1219                 rb_node = tree_search(&cache->rb_root,
1220                                       reloc_root->commit_root->start);
1221                 if (rb_node) {
1222                         node = rb_entry(rb_node, struct backref_node,
1223                                         rb_node);
1224                         BUG_ON(node->detached);
1225                 }
1226         }
1227
1228         if (!node)
1229                 return 0;
1230
1231         new_node = alloc_backref_node(cache);
1232         if (!new_node)
1233                 return -ENOMEM;
1234
1235         new_node->bytenr = dest->node->start;
1236         new_node->level = node->level;
1237         new_node->lowest = node->lowest;
1238         new_node->checked = 1;
1239         new_node->root = dest;
1240
1241         if (!node->lowest) {
1242                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1243                         new_edge = alloc_backref_edge(cache);
1244                         if (!new_edge)
1245                                 goto fail;
1246
1247                         new_edge->node[UPPER] = new_node;
1248                         new_edge->node[LOWER] = edge->node[LOWER];
1249                         list_add_tail(&new_edge->list[UPPER],
1250                                       &new_node->lower);
1251                 }
1252         } else {
1253                 list_add_tail(&new_node->lower, &cache->leaves);
1254         }
1255
1256         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1257                               &new_node->rb_node);
1258         if (rb_node)
1259                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1260
1261         if (!new_node->lowest) {
1262                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1263                         list_add_tail(&new_edge->list[LOWER],
1264                                       &new_edge->node[LOWER]->upper);
1265                 }
1266         }
1267         return 0;
1268 fail:
1269         while (!list_empty(&new_node->lower)) {
1270                 new_edge = list_entry(new_node->lower.next,
1271                                       struct backref_edge, list[UPPER]);
1272                 list_del(&new_edge->list[UPPER]);
1273                 free_backref_edge(cache, new_edge);
1274         }
1275         free_backref_node(cache, new_node);
1276         return -ENOMEM;
1277 }
1278
1279 /*
1280  * helper to add 'address of tree root -> reloc tree' mapping
1281  */
1282 static int __must_check __add_reloc_root(struct btrfs_root *root)
1283 {
1284         struct rb_node *rb_node;
1285         struct mapping_node *node;
1286         struct reloc_control *rc = root->fs_info->reloc_ctl;
1287
1288         node = kmalloc(sizeof(*node), GFP_NOFS);
1289         if (!node)
1290                 return -ENOMEM;
1291
1292         node->bytenr = root->node->start;
1293         node->data = root;
1294
1295         spin_lock(&rc->reloc_root_tree.lock);
1296         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1297                               node->bytenr, &node->rb_node);
1298         spin_unlock(&rc->reloc_root_tree.lock);
1299         if (rb_node) {
1300                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1301                             "for start=%llu while inserting into relocation "
1302                             "tree", node->bytenr);
1303                 kfree(node);
1304                 return -EEXIST;
1305         }
1306
1307         list_add_tail(&root->root_list, &rc->reloc_roots);
1308         return 0;
1309 }
1310
1311 /*
1312  * helper to delete the 'address of tree root -> reloc tree'
1313  * mapping
1314  */
1315 static void __del_reloc_root(struct btrfs_root *root)
1316 {
1317         struct rb_node *rb_node;
1318         struct mapping_node *node = NULL;
1319         struct reloc_control *rc = root->fs_info->reloc_ctl;
1320
1321         spin_lock(&rc->reloc_root_tree.lock);
1322         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1323                               root->node->start);
1324         if (rb_node) {
1325                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1326                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1327         }
1328         spin_unlock(&rc->reloc_root_tree.lock);
1329
1330         if (!node)
1331                 return;
1332         BUG_ON((struct btrfs_root *)node->data != root);
1333
1334         spin_lock(&root->fs_info->trans_lock);
1335         list_del_init(&root->root_list);
1336         spin_unlock(&root->fs_info->trans_lock);
1337         kfree(node);
1338 }
1339
1340 /*
1341  * helper to update the 'address of tree root -> reloc tree'
1342  * mapping
1343  */
1344 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1345 {
1346         struct rb_node *rb_node;
1347         struct mapping_node *node = NULL;
1348         struct reloc_control *rc = root->fs_info->reloc_ctl;
1349
1350         spin_lock(&rc->reloc_root_tree.lock);
1351         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1352                               root->node->start);
1353         if (rb_node) {
1354                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1355                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1356         }
1357         spin_unlock(&rc->reloc_root_tree.lock);
1358
1359         if (!node)
1360                 return 0;
1361         BUG_ON((struct btrfs_root *)node->data != root);
1362
1363         spin_lock(&rc->reloc_root_tree.lock);
1364         node->bytenr = new_bytenr;
1365         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1366                               node->bytenr, &node->rb_node);
1367         spin_unlock(&rc->reloc_root_tree.lock);
1368         if (rb_node)
1369                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1370         return 0;
1371 }
1372
1373 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1374                                         struct btrfs_root *root, u64 objectid)
1375 {
1376         struct btrfs_root *reloc_root;
1377         struct extent_buffer *eb;
1378         struct btrfs_root_item *root_item;
1379         struct btrfs_key root_key;
1380         u64 last_snap = 0;
1381         int ret;
1382
1383         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1384         BUG_ON(!root_item);
1385
1386         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1387         root_key.type = BTRFS_ROOT_ITEM_KEY;
1388         root_key.offset = objectid;
1389
1390         if (root->root_key.objectid == objectid) {
1391                 /* called by btrfs_init_reloc_root */
1392                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1393                                       BTRFS_TREE_RELOC_OBJECTID);
1394                 BUG_ON(ret);
1395
1396                 last_snap = btrfs_root_last_snapshot(&root->root_item);
1397                 btrfs_set_root_last_snapshot(&root->root_item,
1398                                              trans->transid - 1);
1399         } else {
1400                 /*
1401                  * called by btrfs_reloc_post_snapshot_hook.
1402                  * the source tree is a reloc tree, all tree blocks
1403                  * modified after it was created have RELOC flag
1404                  * set in their headers. so it's OK to not update
1405                  * the 'last_snapshot'.
1406                  */
1407                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1408                                       BTRFS_TREE_RELOC_OBJECTID);
1409                 BUG_ON(ret);
1410         }
1411
1412         memcpy(root_item, &root->root_item, sizeof(*root_item));
1413         btrfs_set_root_bytenr(root_item, eb->start);
1414         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1415         btrfs_set_root_generation(root_item, trans->transid);
1416
1417         if (root->root_key.objectid == objectid) {
1418                 btrfs_set_root_refs(root_item, 0);
1419                 memset(&root_item->drop_progress, 0,
1420                        sizeof(struct btrfs_disk_key));
1421                 root_item->drop_level = 0;
1422                 /*
1423                  * abuse rtransid, it is safe because it is impossible to
1424                  * receive data into a relocation tree.
1425                  */
1426                 btrfs_set_root_rtransid(root_item, last_snap);
1427                 btrfs_set_root_otransid(root_item, trans->transid);
1428         }
1429
1430         btrfs_tree_unlock(eb);
1431         free_extent_buffer(eb);
1432
1433         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1434                                 &root_key, root_item);
1435         BUG_ON(ret);
1436         kfree(root_item);
1437
1438         reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
1439         BUG_ON(IS_ERR(reloc_root));
1440         reloc_root->last_trans = trans->transid;
1441         return reloc_root;
1442 }
1443
1444 /*
1445  * create reloc tree for a given fs tree. reloc tree is just a
1446  * snapshot of the fs tree with special root objectid.
1447  */
1448 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1449                           struct btrfs_root *root)
1450 {
1451         struct btrfs_root *reloc_root;
1452         struct reloc_control *rc = root->fs_info->reloc_ctl;
1453         struct btrfs_block_rsv *rsv;
1454         int clear_rsv = 0;
1455         int ret;
1456
1457         if (root->reloc_root) {
1458                 reloc_root = root->reloc_root;
1459                 reloc_root->last_trans = trans->transid;
1460                 return 0;
1461         }
1462
1463         if (!rc || !rc->create_reloc_tree ||
1464             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1465                 return 0;
1466
1467         if (!trans->reloc_reserved) {
1468                 rsv = trans->block_rsv;
1469                 trans->block_rsv = rc->block_rsv;
1470                 clear_rsv = 1;
1471         }
1472         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1473         if (clear_rsv)
1474                 trans->block_rsv = rsv;
1475
1476         ret = __add_reloc_root(reloc_root);
1477         BUG_ON(ret < 0);
1478         root->reloc_root = reloc_root;
1479         return 0;
1480 }
1481
1482 /*
1483  * update root item of reloc tree
1484  */
1485 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1486                             struct btrfs_root *root)
1487 {
1488         struct btrfs_root *reloc_root;
1489         struct btrfs_root_item *root_item;
1490         int ret;
1491
1492         if (!root->reloc_root)
1493                 goto out;
1494
1495         reloc_root = root->reloc_root;
1496         root_item = &reloc_root->root_item;
1497
1498         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1499             btrfs_root_refs(root_item) == 0) {
1500                 root->reloc_root = NULL;
1501                 __del_reloc_root(reloc_root);
1502         }
1503
1504         if (reloc_root->commit_root != reloc_root->node) {
1505                 btrfs_set_root_node(root_item, reloc_root->node);
1506                 free_extent_buffer(reloc_root->commit_root);
1507                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1508         }
1509
1510         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1511                                 &reloc_root->root_key, root_item);
1512         BUG_ON(ret);
1513
1514 out:
1515         return 0;
1516 }
1517
1518 /*
1519  * helper to find first cached inode with inode number >= objectid
1520  * in a subvolume
1521  */
1522 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1523 {
1524         struct rb_node *node;
1525         struct rb_node *prev;
1526         struct btrfs_inode *entry;
1527         struct inode *inode;
1528
1529         spin_lock(&root->inode_lock);
1530 again:
1531         node = root->inode_tree.rb_node;
1532         prev = NULL;
1533         while (node) {
1534                 prev = node;
1535                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1536
1537                 if (objectid < btrfs_ino(&entry->vfs_inode))
1538                         node = node->rb_left;
1539                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1540                         node = node->rb_right;
1541                 else
1542                         break;
1543         }
1544         if (!node) {
1545                 while (prev) {
1546                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1547                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1548                                 node = prev;
1549                                 break;
1550                         }
1551                         prev = rb_next(prev);
1552                 }
1553         }
1554         while (node) {
1555                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1556                 inode = igrab(&entry->vfs_inode);
1557                 if (inode) {
1558                         spin_unlock(&root->inode_lock);
1559                         return inode;
1560                 }
1561
1562                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1563                 if (cond_resched_lock(&root->inode_lock))
1564                         goto again;
1565
1566                 node = rb_next(node);
1567         }
1568         spin_unlock(&root->inode_lock);
1569         return NULL;
1570 }
1571
1572 static int in_block_group(u64 bytenr,
1573                           struct btrfs_block_group_cache *block_group)
1574 {
1575         if (bytenr >= block_group->key.objectid &&
1576             bytenr < block_group->key.objectid + block_group->key.offset)
1577                 return 1;
1578         return 0;
1579 }
1580
1581 /*
1582  * get new location of data
1583  */
1584 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1585                             u64 bytenr, u64 num_bytes)
1586 {
1587         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1588         struct btrfs_path *path;
1589         struct btrfs_file_extent_item *fi;
1590         struct extent_buffer *leaf;
1591         int ret;
1592
1593         path = btrfs_alloc_path();
1594         if (!path)
1595                 return -ENOMEM;
1596
1597         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1598         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1599                                        bytenr, 0);
1600         if (ret < 0)
1601                 goto out;
1602         if (ret > 0) {
1603                 ret = -ENOENT;
1604                 goto out;
1605         }
1606
1607         leaf = path->nodes[0];
1608         fi = btrfs_item_ptr(leaf, path->slots[0],
1609                             struct btrfs_file_extent_item);
1610
1611         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1612                btrfs_file_extent_compression(leaf, fi) ||
1613                btrfs_file_extent_encryption(leaf, fi) ||
1614                btrfs_file_extent_other_encoding(leaf, fi));
1615
1616         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1617                 ret = -EINVAL;
1618                 goto out;
1619         }
1620
1621         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1622         ret = 0;
1623 out:
1624         btrfs_free_path(path);
1625         return ret;
1626 }
1627
1628 /*
1629  * update file extent items in the tree leaf to point to
1630  * the new locations.
1631  */
1632 static noinline_for_stack
1633 int replace_file_extents(struct btrfs_trans_handle *trans,
1634                          struct reloc_control *rc,
1635                          struct btrfs_root *root,
1636                          struct extent_buffer *leaf)
1637 {
1638         struct btrfs_key key;
1639         struct btrfs_file_extent_item *fi;
1640         struct inode *inode = NULL;
1641         u64 parent;
1642         u64 bytenr;
1643         u64 new_bytenr = 0;
1644         u64 num_bytes;
1645         u64 end;
1646         u32 nritems;
1647         u32 i;
1648         int ret = 0;
1649         int first = 1;
1650         int dirty = 0;
1651
1652         if (rc->stage != UPDATE_DATA_PTRS)
1653                 return 0;
1654
1655         /* reloc trees always use full backref */
1656         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1657                 parent = leaf->start;
1658         else
1659                 parent = 0;
1660
1661         nritems = btrfs_header_nritems(leaf);
1662         for (i = 0; i < nritems; i++) {
1663                 cond_resched();
1664                 btrfs_item_key_to_cpu(leaf, &key, i);
1665                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1666                         continue;
1667                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1668                 if (btrfs_file_extent_type(leaf, fi) ==
1669                     BTRFS_FILE_EXTENT_INLINE)
1670                         continue;
1671                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1672                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1673                 if (bytenr == 0)
1674                         continue;
1675                 if (!in_block_group(bytenr, rc->block_group))
1676                         continue;
1677
1678                 /*
1679                  * if we are modifying block in fs tree, wait for readpage
1680                  * to complete and drop the extent cache
1681                  */
1682                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1683                         if (first) {
1684                                 inode = find_next_inode(root, key.objectid);
1685                                 first = 0;
1686                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1687                                 btrfs_add_delayed_iput(inode);
1688                                 inode = find_next_inode(root, key.objectid);
1689                         }
1690                         if (inode && btrfs_ino(inode) == key.objectid) {
1691                                 end = key.offset +
1692                                       btrfs_file_extent_num_bytes(leaf, fi);
1693                                 WARN_ON(!IS_ALIGNED(key.offset,
1694                                                     root->sectorsize));
1695                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1696                                 end--;
1697                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1698                                                       key.offset, end);
1699                                 if (!ret)
1700                                         continue;
1701
1702                                 btrfs_drop_extent_cache(inode, key.offset, end,
1703                                                         1);
1704                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1705                                               key.offset, end);
1706                         }
1707                 }
1708
1709                 ret = get_new_location(rc->data_inode, &new_bytenr,
1710                                        bytenr, num_bytes);
1711                 if (ret) {
1712                         /*
1713                          * Don't have to abort since we've not changed anything
1714                          * in the file extent yet.
1715                          */
1716                         break;
1717                 }
1718
1719                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1720                 dirty = 1;
1721
1722                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1723                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1724                                            num_bytes, parent,
1725                                            btrfs_header_owner(leaf),
1726                                            key.objectid, key.offset);
1727                 if (ret) {
1728                         btrfs_abort_transaction(trans, root, ret);
1729                         break;
1730                 }
1731
1732                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1733                                         parent, btrfs_header_owner(leaf),
1734                                         key.objectid, key.offset);
1735                 if (ret) {
1736                         btrfs_abort_transaction(trans, root, ret);
1737                         break;
1738                 }
1739         }
1740         if (dirty)
1741                 btrfs_mark_buffer_dirty(leaf);
1742         if (inode)
1743                 btrfs_add_delayed_iput(inode);
1744         return ret;
1745 }
1746
1747 static noinline_for_stack
1748 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1749                      struct btrfs_path *path, int level)
1750 {
1751         struct btrfs_disk_key key1;
1752         struct btrfs_disk_key key2;
1753         btrfs_node_key(eb, &key1, slot);
1754         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1755         return memcmp(&key1, &key2, sizeof(key1));
1756 }
1757
1758 /*
1759  * try to replace tree blocks in fs tree with the new blocks
1760  * in reloc tree. tree blocks haven't been modified since the
1761  * reloc tree was create can be replaced.
1762  *
1763  * if a block was replaced, level of the block + 1 is returned.
1764  * if no block got replaced, 0 is returned. if there are other
1765  * errors, a negative error number is returned.
1766  */
1767 static noinline_for_stack
1768 int replace_path(struct btrfs_trans_handle *trans,
1769                  struct btrfs_root *dest, struct btrfs_root *src,
1770                  struct btrfs_path *path, struct btrfs_key *next_key,
1771                  int lowest_level, int max_level)
1772 {
1773         struct extent_buffer *eb;
1774         struct extent_buffer *parent;
1775         struct btrfs_key key;
1776         u64 old_bytenr;
1777         u64 new_bytenr;
1778         u64 old_ptr_gen;
1779         u64 new_ptr_gen;
1780         u64 last_snapshot;
1781         u32 blocksize;
1782         int cow = 0;
1783         int level;
1784         int ret;
1785         int slot;
1786
1787         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1788         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1789
1790         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1791 again:
1792         slot = path->slots[lowest_level];
1793         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1794
1795         eb = btrfs_lock_root_node(dest);
1796         btrfs_set_lock_blocking(eb);
1797         level = btrfs_header_level(eb);
1798
1799         if (level < lowest_level) {
1800                 btrfs_tree_unlock(eb);
1801                 free_extent_buffer(eb);
1802                 return 0;
1803         }
1804
1805         if (cow) {
1806                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1807                 BUG_ON(ret);
1808         }
1809         btrfs_set_lock_blocking(eb);
1810
1811         if (next_key) {
1812                 next_key->objectid = (u64)-1;
1813                 next_key->type = (u8)-1;
1814                 next_key->offset = (u64)-1;
1815         }
1816
1817         parent = eb;
1818         while (1) {
1819                 level = btrfs_header_level(parent);
1820                 BUG_ON(level < lowest_level);
1821
1822                 ret = btrfs_bin_search(parent, &key, level, &slot);
1823                 if (ret && slot > 0)
1824                         slot--;
1825
1826                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1827                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1828
1829                 old_bytenr = btrfs_node_blockptr(parent, slot);
1830                 blocksize = dest->nodesize;
1831                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1832
1833                 if (level <= max_level) {
1834                         eb = path->nodes[level];
1835                         new_bytenr = btrfs_node_blockptr(eb,
1836                                                         path->slots[level]);
1837                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1838                                                         path->slots[level]);
1839                 } else {
1840                         new_bytenr = 0;
1841                         new_ptr_gen = 0;
1842                 }
1843
1844                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1845                         ret = level;
1846                         break;
1847                 }
1848
1849                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1850                     memcmp_node_keys(parent, slot, path, level)) {
1851                         if (level <= lowest_level) {
1852                                 ret = 0;
1853                                 break;
1854                         }
1855
1856                         eb = read_tree_block(dest, old_bytenr, old_ptr_gen);
1857                         if (IS_ERR(eb)) {
1858                                 ret = PTR_ERR(eb);
1859                         } else if (!extent_buffer_uptodate(eb)) {
1860                                 ret = -EIO;
1861                                 free_extent_buffer(eb);
1862                                 break;
1863                         }
1864                         btrfs_tree_lock(eb);
1865                         if (cow) {
1866                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1867                                                       slot, &eb);
1868                                 BUG_ON(ret);
1869                         }
1870                         btrfs_set_lock_blocking(eb);
1871
1872                         btrfs_tree_unlock(parent);
1873                         free_extent_buffer(parent);
1874
1875                         parent = eb;
1876                         continue;
1877                 }
1878
1879                 if (!cow) {
1880                         btrfs_tree_unlock(parent);
1881                         free_extent_buffer(parent);
1882                         cow = 1;
1883                         goto again;
1884                 }
1885
1886                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1887                                       path->slots[level]);
1888                 btrfs_release_path(path);
1889
1890                 path->lowest_level = level;
1891                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1892                 path->lowest_level = 0;
1893                 BUG_ON(ret);
1894
1895                 /*
1896                  * swap blocks in fs tree and reloc tree.
1897                  */
1898                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1899                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1900                 btrfs_mark_buffer_dirty(parent);
1901
1902                 btrfs_set_node_blockptr(path->nodes[level],
1903                                         path->slots[level], old_bytenr);
1904                 btrfs_set_node_ptr_generation(path->nodes[level],
1905                                               path->slots[level], old_ptr_gen);
1906                 btrfs_mark_buffer_dirty(path->nodes[level]);
1907
1908                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1909                                         path->nodes[level]->start,
1910                                         src->root_key.objectid, level - 1, 0);
1911                 BUG_ON(ret);
1912                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1913                                         0, dest->root_key.objectid, level - 1,
1914                                         0);
1915                 BUG_ON(ret);
1916
1917                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1918                                         path->nodes[level]->start,
1919                                         src->root_key.objectid, level - 1, 0);
1920                 BUG_ON(ret);
1921
1922                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1923                                         0, dest->root_key.objectid, level - 1,
1924                                         0);
1925                 BUG_ON(ret);
1926
1927                 btrfs_unlock_up_safe(path, 0);
1928
1929                 ret = level;
1930                 break;
1931         }
1932         btrfs_tree_unlock(parent);
1933         free_extent_buffer(parent);
1934         return ret;
1935 }
1936
1937 /*
1938  * helper to find next relocated block in reloc tree
1939  */
1940 static noinline_for_stack
1941 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1942                        int *level)
1943 {
1944         struct extent_buffer *eb;
1945         int i;
1946         u64 last_snapshot;
1947         u32 nritems;
1948
1949         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1950
1951         for (i = 0; i < *level; i++) {
1952                 free_extent_buffer(path->nodes[i]);
1953                 path->nodes[i] = NULL;
1954         }
1955
1956         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1957                 eb = path->nodes[i];
1958                 nritems = btrfs_header_nritems(eb);
1959                 while (path->slots[i] + 1 < nritems) {
1960                         path->slots[i]++;
1961                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1962                             last_snapshot)
1963                                 continue;
1964
1965                         *level = i;
1966                         return 0;
1967                 }
1968                 free_extent_buffer(path->nodes[i]);
1969                 path->nodes[i] = NULL;
1970         }
1971         return 1;
1972 }
1973
1974 /*
1975  * walk down reloc tree to find relocated block of lowest level
1976  */
1977 static noinline_for_stack
1978 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1979                          int *level)
1980 {
1981         struct extent_buffer *eb = NULL;
1982         int i;
1983         u64 bytenr;
1984         u64 ptr_gen = 0;
1985         u64 last_snapshot;
1986         u32 nritems;
1987
1988         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1989
1990         for (i = *level; i > 0; i--) {
1991                 eb = path->nodes[i];
1992                 nritems = btrfs_header_nritems(eb);
1993                 while (path->slots[i] < nritems) {
1994                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1995                         if (ptr_gen > last_snapshot)
1996                                 break;
1997                         path->slots[i]++;
1998                 }
1999                 if (path->slots[i] >= nritems) {
2000                         if (i == *level)
2001                                 break;
2002                         *level = i + 1;
2003                         return 0;
2004                 }
2005                 if (i == 1) {
2006                         *level = i;
2007                         return 0;
2008                 }
2009
2010                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2011                 eb = read_tree_block(root, bytenr, ptr_gen);
2012                 if (IS_ERR(eb)) {
2013                         return PTR_ERR(eb);
2014                 } else if (!extent_buffer_uptodate(eb)) {
2015                         free_extent_buffer(eb);
2016                         return -EIO;
2017                 }
2018                 BUG_ON(btrfs_header_level(eb) != i - 1);
2019                 path->nodes[i - 1] = eb;
2020                 path->slots[i - 1] = 0;
2021         }
2022         return 1;
2023 }
2024
2025 /*
2026  * invalidate extent cache for file extents whose key in range of
2027  * [min_key, max_key)
2028  */
2029 static int invalidate_extent_cache(struct btrfs_root *root,
2030                                    struct btrfs_key *min_key,
2031                                    struct btrfs_key *max_key)
2032 {
2033         struct inode *inode = NULL;
2034         u64 objectid;
2035         u64 start, end;
2036         u64 ino;
2037
2038         objectid = min_key->objectid;
2039         while (1) {
2040                 cond_resched();
2041                 iput(inode);
2042
2043                 if (objectid > max_key->objectid)
2044                         break;
2045
2046                 inode = find_next_inode(root, objectid);
2047                 if (!inode)
2048                         break;
2049                 ino = btrfs_ino(inode);
2050
2051                 if (ino > max_key->objectid) {
2052                         iput(inode);
2053                         break;
2054                 }
2055
2056                 objectid = ino + 1;
2057                 if (!S_ISREG(inode->i_mode))
2058                         continue;
2059
2060                 if (unlikely(min_key->objectid == ino)) {
2061                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2062                                 continue;
2063                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2064                                 start = 0;
2065                         else {
2066                                 start = min_key->offset;
2067                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2068                         }
2069                 } else {
2070                         start = 0;
2071                 }
2072
2073                 if (unlikely(max_key->objectid == ino)) {
2074                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2075                                 continue;
2076                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2077                                 end = (u64)-1;
2078                         } else {
2079                                 if (max_key->offset == 0)
2080                                         continue;
2081                                 end = max_key->offset;
2082                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2083                                 end--;
2084                         }
2085                 } else {
2086                         end = (u64)-1;
2087                 }
2088
2089                 /* the lock_extent waits for readpage to complete */
2090                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2091                 btrfs_drop_extent_cache(inode, start, end, 1);
2092                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2093         }
2094         return 0;
2095 }
2096
2097 static int find_next_key(struct btrfs_path *path, int level,
2098                          struct btrfs_key *key)
2099
2100 {
2101         while (level < BTRFS_MAX_LEVEL) {
2102                 if (!path->nodes[level])
2103                         break;
2104                 if (path->slots[level] + 1 <
2105                     btrfs_header_nritems(path->nodes[level])) {
2106                         btrfs_node_key_to_cpu(path->nodes[level], key,
2107                                               path->slots[level] + 1);
2108                         return 0;
2109                 }
2110                 level++;
2111         }
2112         return 1;
2113 }
2114
2115 /*
2116  * merge the relocated tree blocks in reloc tree with corresponding
2117  * fs tree.
2118  */
2119 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2120                                                struct btrfs_root *root)
2121 {
2122         LIST_HEAD(inode_list);
2123         struct btrfs_key key;
2124         struct btrfs_key next_key;
2125         struct btrfs_trans_handle *trans = NULL;
2126         struct btrfs_root *reloc_root;
2127         struct btrfs_root_item *root_item;
2128         struct btrfs_path *path;
2129         struct extent_buffer *leaf;
2130         int level;
2131         int max_level;
2132         int replaced = 0;
2133         int ret;
2134         int err = 0;
2135         u32 min_reserved;
2136
2137         path = btrfs_alloc_path();
2138         if (!path)
2139                 return -ENOMEM;
2140         path->reada = 1;
2141
2142         reloc_root = root->reloc_root;
2143         root_item = &reloc_root->root_item;
2144
2145         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2146                 level = btrfs_root_level(root_item);
2147                 extent_buffer_get(reloc_root->node);
2148                 path->nodes[level] = reloc_root->node;
2149                 path->slots[level] = 0;
2150         } else {
2151                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2152
2153                 level = root_item->drop_level;
2154                 BUG_ON(level == 0);
2155                 path->lowest_level = level;
2156                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2157                 path->lowest_level = 0;
2158                 if (ret < 0) {
2159                         btrfs_free_path(path);
2160                         return ret;
2161                 }
2162
2163                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2164                                       path->slots[level]);
2165                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2166
2167                 btrfs_unlock_up_safe(path, 0);
2168         }
2169
2170         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2171         memset(&next_key, 0, sizeof(next_key));
2172
2173         while (1) {
2174                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2175                                              BTRFS_RESERVE_FLUSH_ALL);
2176                 if (ret) {
2177                         err = ret;
2178                         goto out;
2179                 }
2180                 trans = btrfs_start_transaction(root, 0);
2181                 if (IS_ERR(trans)) {
2182                         err = PTR_ERR(trans);
2183                         trans = NULL;
2184                         goto out;
2185                 }
2186                 trans->block_rsv = rc->block_rsv;
2187
2188                 replaced = 0;
2189                 max_level = level;
2190
2191                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2192                 if (ret < 0) {
2193                         err = ret;
2194                         goto out;
2195                 }
2196                 if (ret > 0)
2197                         break;
2198
2199                 if (!find_next_key(path, level, &key) &&
2200                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2201                         ret = 0;
2202                 } else {
2203                         ret = replace_path(trans, root, reloc_root, path,
2204                                            &next_key, level, max_level);
2205                 }
2206                 if (ret < 0) {
2207                         err = ret;
2208                         goto out;
2209                 }
2210
2211                 if (ret > 0) {
2212                         level = ret;
2213                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2214                                               path->slots[level]);
2215                         replaced = 1;
2216                 }
2217
2218                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2219                 if (ret > 0)
2220                         break;
2221
2222                 BUG_ON(level == 0);
2223                 /*
2224                  * save the merging progress in the drop_progress.
2225                  * this is OK since root refs == 1 in this case.
2226                  */
2227                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2228                                path->slots[level]);
2229                 root_item->drop_level = level;
2230
2231                 btrfs_end_transaction_throttle(trans, root);
2232                 trans = NULL;
2233
2234                 btrfs_btree_balance_dirty(root);
2235
2236                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2237                         invalidate_extent_cache(root, &key, &next_key);
2238         }
2239
2240         /*
2241          * handle the case only one block in the fs tree need to be
2242          * relocated and the block is tree root.
2243          */
2244         leaf = btrfs_lock_root_node(root);
2245         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2246         btrfs_tree_unlock(leaf);
2247         free_extent_buffer(leaf);
2248         if (ret < 0)
2249                 err = ret;
2250 out:
2251         btrfs_free_path(path);
2252
2253         if (err == 0) {
2254                 memset(&root_item->drop_progress, 0,
2255                        sizeof(root_item->drop_progress));
2256                 root_item->drop_level = 0;
2257                 btrfs_set_root_refs(root_item, 0);
2258                 btrfs_update_reloc_root(trans, root);
2259         }
2260
2261         if (trans)
2262                 btrfs_end_transaction_throttle(trans, root);
2263
2264         btrfs_btree_balance_dirty(root);
2265
2266         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2267                 invalidate_extent_cache(root, &key, &next_key);
2268
2269         return err;
2270 }
2271
2272 static noinline_for_stack
2273 int prepare_to_merge(struct reloc_control *rc, int err)
2274 {
2275         struct btrfs_root *root = rc->extent_root;
2276         struct btrfs_root *reloc_root;
2277         struct btrfs_trans_handle *trans;
2278         LIST_HEAD(reloc_roots);
2279         u64 num_bytes = 0;
2280         int ret;
2281
2282         mutex_lock(&root->fs_info->reloc_mutex);
2283         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2284         rc->merging_rsv_size += rc->nodes_relocated * 2;
2285         mutex_unlock(&root->fs_info->reloc_mutex);
2286
2287 again:
2288         if (!err) {
2289                 num_bytes = rc->merging_rsv_size;
2290                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2291                                           BTRFS_RESERVE_FLUSH_ALL);
2292                 if (ret)
2293                         err = ret;
2294         }
2295
2296         trans = btrfs_join_transaction(rc->extent_root);
2297         if (IS_ERR(trans)) {
2298                 if (!err)
2299                         btrfs_block_rsv_release(rc->extent_root,
2300                                                 rc->block_rsv, num_bytes);
2301                 return PTR_ERR(trans);
2302         }
2303
2304         if (!err) {
2305                 if (num_bytes != rc->merging_rsv_size) {
2306                         btrfs_end_transaction(trans, rc->extent_root);
2307                         btrfs_block_rsv_release(rc->extent_root,
2308                                                 rc->block_rsv, num_bytes);
2309                         goto again;
2310                 }
2311         }
2312
2313         rc->merge_reloc_tree = 1;
2314
2315         while (!list_empty(&rc->reloc_roots)) {
2316                 reloc_root = list_entry(rc->reloc_roots.next,
2317                                         struct btrfs_root, root_list);
2318                 list_del_init(&reloc_root->root_list);
2319
2320                 root = read_fs_root(reloc_root->fs_info,
2321                                     reloc_root->root_key.offset);
2322                 BUG_ON(IS_ERR(root));
2323                 BUG_ON(root->reloc_root != reloc_root);
2324
2325                 /*
2326                  * set reference count to 1, so btrfs_recover_relocation
2327                  * knows it should resumes merging
2328                  */
2329                 if (!err)
2330                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2331                 btrfs_update_reloc_root(trans, root);
2332
2333                 list_add(&reloc_root->root_list, &reloc_roots);
2334         }
2335
2336         list_splice(&reloc_roots, &rc->reloc_roots);
2337
2338         if (!err)
2339                 btrfs_commit_transaction(trans, rc->extent_root);
2340         else
2341                 btrfs_end_transaction(trans, rc->extent_root);
2342         return err;
2343 }
2344
2345 static noinline_for_stack
2346 void free_reloc_roots(struct list_head *list)
2347 {
2348         struct btrfs_root *reloc_root;
2349
2350         while (!list_empty(list)) {
2351                 reloc_root = list_entry(list->next, struct btrfs_root,
2352                                         root_list);
2353                 free_extent_buffer(reloc_root->node);
2354                 free_extent_buffer(reloc_root->commit_root);
2355                 reloc_root->node = NULL;
2356                 reloc_root->commit_root = NULL;
2357                 __del_reloc_root(reloc_root);
2358         }
2359 }
2360
2361 static noinline_for_stack
2362 void merge_reloc_roots(struct reloc_control *rc)
2363 {
2364         struct btrfs_root *root;
2365         struct btrfs_root *reloc_root;
2366         u64 last_snap;
2367         u64 otransid;
2368         u64 objectid;
2369         LIST_HEAD(reloc_roots);
2370         int found = 0;
2371         int ret = 0;
2372 again:
2373         root = rc->extent_root;
2374
2375         /*
2376          * this serializes us with btrfs_record_root_in_transaction,
2377          * we have to make sure nobody is in the middle of
2378          * adding their roots to the list while we are
2379          * doing this splice
2380          */
2381         mutex_lock(&root->fs_info->reloc_mutex);
2382         list_splice_init(&rc->reloc_roots, &reloc_roots);
2383         mutex_unlock(&root->fs_info->reloc_mutex);
2384
2385         while (!list_empty(&reloc_roots)) {
2386                 found = 1;
2387                 reloc_root = list_entry(reloc_roots.next,
2388                                         struct btrfs_root, root_list);
2389
2390                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2391                         root = read_fs_root(reloc_root->fs_info,
2392                                             reloc_root->root_key.offset);
2393                         BUG_ON(IS_ERR(root));
2394                         BUG_ON(root->reloc_root != reloc_root);
2395
2396                         ret = merge_reloc_root(rc, root);
2397                         if (ret) {
2398                                 if (list_empty(&reloc_root->root_list))
2399                                         list_add_tail(&reloc_root->root_list,
2400                                                       &reloc_roots);
2401                                 goto out;
2402                         }
2403                 } else {
2404                         list_del_init(&reloc_root->root_list);
2405                 }
2406
2407                 /*
2408                  * we keep the old last snapshod transid in rtranid when we
2409                  * created the relocation tree.
2410                  */
2411                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2412                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2413                 objectid = reloc_root->root_key.offset;
2414
2415                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2416                 if (ret < 0) {
2417                         if (list_empty(&reloc_root->root_list))
2418                                 list_add_tail(&reloc_root->root_list,
2419                                               &reloc_roots);
2420                         goto out;
2421                 }
2422         }
2423
2424         if (found) {
2425                 found = 0;
2426                 goto again;
2427         }
2428 out:
2429         if (ret) {
2430                 btrfs_std_error(root->fs_info, ret, NULL);
2431                 if (!list_empty(&reloc_roots))
2432                         free_reloc_roots(&reloc_roots);
2433
2434                 /* new reloc root may be added */
2435                 mutex_lock(&root->fs_info->reloc_mutex);
2436                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2437                 mutex_unlock(&root->fs_info->reloc_mutex);
2438                 if (!list_empty(&reloc_roots))
2439                         free_reloc_roots(&reloc_roots);
2440         }
2441
2442         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2443 }
2444
2445 static void free_block_list(struct rb_root *blocks)
2446 {
2447         struct tree_block *block;
2448         struct rb_node *rb_node;
2449         while ((rb_node = rb_first(blocks))) {
2450                 block = rb_entry(rb_node, struct tree_block, rb_node);
2451                 rb_erase(rb_node, blocks);
2452                 kfree(block);
2453         }
2454 }
2455
2456 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2457                                       struct btrfs_root *reloc_root)
2458 {
2459         struct btrfs_root *root;
2460
2461         if (reloc_root->last_trans == trans->transid)
2462                 return 0;
2463
2464         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2465         BUG_ON(IS_ERR(root));
2466         BUG_ON(root->reloc_root != reloc_root);
2467
2468         return btrfs_record_root_in_trans(trans, root);
2469 }
2470
2471 static noinline_for_stack
2472 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2473                                      struct reloc_control *rc,
2474                                      struct backref_node *node,
2475                                      struct backref_edge *edges[])
2476 {
2477         struct backref_node *next;
2478         struct btrfs_root *root;
2479         int index = 0;
2480
2481         next = node;
2482         while (1) {
2483                 cond_resched();
2484                 next = walk_up_backref(next, edges, &index);
2485                 root = next->root;
2486                 BUG_ON(!root);
2487                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2488
2489                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2490                         record_reloc_root_in_trans(trans, root);
2491                         break;
2492                 }
2493
2494                 btrfs_record_root_in_trans(trans, root);
2495                 root = root->reloc_root;
2496
2497                 if (next->new_bytenr != root->node->start) {
2498                         BUG_ON(next->new_bytenr);
2499                         BUG_ON(!list_empty(&next->list));
2500                         next->new_bytenr = root->node->start;
2501                         next->root = root;
2502                         list_add_tail(&next->list,
2503                                       &rc->backref_cache.changed);
2504                         __mark_block_processed(rc, next);
2505                         break;
2506                 }
2507
2508                 WARN_ON(1);
2509                 root = NULL;
2510                 next = walk_down_backref(edges, &index);
2511                 if (!next || next->level <= node->level)
2512                         break;
2513         }
2514         if (!root)
2515                 return NULL;
2516
2517         next = node;
2518         /* setup backref node path for btrfs_reloc_cow_block */
2519         while (1) {
2520                 rc->backref_cache.path[next->level] = next;
2521                 if (--index < 0)
2522                         break;
2523                 next = edges[index]->node[UPPER];
2524         }
2525         return root;
2526 }
2527
2528 /*
2529  * select a tree root for relocation. return NULL if the block
2530  * is reference counted. we should use do_relocation() in this
2531  * case. return a tree root pointer if the block isn't reference
2532  * counted. return -ENOENT if the block is root of reloc tree.
2533  */
2534 static noinline_for_stack
2535 struct btrfs_root *select_one_root(struct backref_node *node)
2536 {
2537         struct backref_node *next;
2538         struct btrfs_root *root;
2539         struct btrfs_root *fs_root = NULL;
2540         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2541         int index = 0;
2542
2543         next = node;
2544         while (1) {
2545                 cond_resched();
2546                 next = walk_up_backref(next, edges, &index);
2547                 root = next->root;
2548                 BUG_ON(!root);
2549
2550                 /* no other choice for non-references counted tree */
2551                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2552                         return root;
2553
2554                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2555                         fs_root = root;
2556
2557                 if (next != node)
2558                         return NULL;
2559
2560                 next = walk_down_backref(edges, &index);
2561                 if (!next || next->level <= node->level)
2562                         break;
2563         }
2564
2565         if (!fs_root)
2566                 return ERR_PTR(-ENOENT);
2567         return fs_root;
2568 }
2569
2570 static noinline_for_stack
2571 u64 calcu_metadata_size(struct reloc_control *rc,
2572                         struct backref_node *node, int reserve)
2573 {
2574         struct backref_node *next = node;
2575         struct backref_edge *edge;
2576         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2577         u64 num_bytes = 0;
2578         int index = 0;
2579
2580         BUG_ON(reserve && node->processed);
2581
2582         while (next) {
2583                 cond_resched();
2584                 while (1) {
2585                         if (next->processed && (reserve || next != node))
2586                                 break;
2587
2588                         num_bytes += rc->extent_root->nodesize;
2589
2590                         if (list_empty(&next->upper))
2591                                 break;
2592
2593                         edge = list_entry(next->upper.next,
2594                                           struct backref_edge, list[LOWER]);
2595                         edges[index++] = edge;
2596                         next = edge->node[UPPER];
2597                 }
2598                 next = walk_down_backref(edges, &index);
2599         }
2600         return num_bytes;
2601 }
2602
2603 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2604                                   struct reloc_control *rc,
2605                                   struct backref_node *node)
2606 {
2607         struct btrfs_root *root = rc->extent_root;
2608         u64 num_bytes;
2609         int ret;
2610         u64 tmp;
2611
2612         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2613
2614         trans->block_rsv = rc->block_rsv;
2615         rc->reserved_bytes += num_bytes;
2616         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2617                                 BTRFS_RESERVE_FLUSH_ALL);
2618         if (ret) {
2619                 if (ret == -EAGAIN) {
2620                         tmp = rc->extent_root->nodesize *
2621                                 RELOCATION_RESERVED_NODES;
2622                         while (tmp <= rc->reserved_bytes)
2623                                 tmp <<= 1;
2624                         /*
2625                          * only one thread can access block_rsv at this point,
2626                          * so we don't need hold lock to protect block_rsv.
2627                          * we expand more reservation size here to allow enough
2628                          * space for relocation and we will return eailer in
2629                          * enospc case.
2630                          */
2631                         rc->block_rsv->size = tmp + rc->extent_root->nodesize *
2632                                               RELOCATION_RESERVED_NODES;
2633                 }
2634                 return ret;
2635         }
2636
2637         return 0;
2638 }
2639
2640 /*
2641  * relocate a block tree, and then update pointers in upper level
2642  * blocks that reference the block to point to the new location.
2643  *
2644  * if called by link_to_upper, the block has already been relocated.
2645  * in that case this function just updates pointers.
2646  */
2647 static int do_relocation(struct btrfs_trans_handle *trans,
2648                          struct reloc_control *rc,
2649                          struct backref_node *node,
2650                          struct btrfs_key *key,
2651                          struct btrfs_path *path, int lowest)
2652 {
2653         struct backref_node *upper;
2654         struct backref_edge *edge;
2655         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2656         struct btrfs_root *root;
2657         struct extent_buffer *eb;
2658         u32 blocksize;
2659         u64 bytenr;
2660         u64 generation;
2661         int slot;
2662         int ret;
2663         int err = 0;
2664
2665         BUG_ON(lowest && node->eb);
2666
2667         path->lowest_level = node->level + 1;
2668         rc->backref_cache.path[node->level] = node;
2669         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2670                 cond_resched();
2671
2672                 upper = edge->node[UPPER];
2673                 root = select_reloc_root(trans, rc, upper, edges);
2674                 BUG_ON(!root);
2675
2676                 if (upper->eb && !upper->locked) {
2677                         if (!lowest) {
2678                                 ret = btrfs_bin_search(upper->eb, key,
2679                                                        upper->level, &slot);
2680                                 BUG_ON(ret);
2681                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2682                                 if (node->eb->start == bytenr)
2683                                         goto next;
2684                         }
2685                         drop_node_buffer(upper);
2686                 }
2687
2688                 if (!upper->eb) {
2689                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2690                         if (ret) {
2691                                 if (ret < 0)
2692                                         err = ret;
2693                                 else
2694                                         err = -ENOENT;
2695
2696                                 btrfs_release_path(path);
2697                                 break;
2698                         }
2699
2700                         if (!upper->eb) {
2701                                 upper->eb = path->nodes[upper->level];
2702                                 path->nodes[upper->level] = NULL;
2703                         } else {
2704                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2705                         }
2706
2707                         upper->locked = 1;
2708                         path->locks[upper->level] = 0;
2709
2710                         slot = path->slots[upper->level];
2711                         btrfs_release_path(path);
2712                 } else {
2713                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2714                                                &slot);
2715                         BUG_ON(ret);
2716                 }
2717
2718                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2719                 if (lowest) {
2720                         BUG_ON(bytenr != node->bytenr);
2721                 } else {
2722                         if (node->eb->start == bytenr)
2723                                 goto next;
2724                 }
2725
2726                 blocksize = root->nodesize;
2727                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2728                 eb = read_tree_block(root, bytenr, generation);
2729                 if (IS_ERR(eb)) {
2730                         err = PTR_ERR(eb);
2731                         goto next;
2732                 } else if (!extent_buffer_uptodate(eb)) {
2733                         free_extent_buffer(eb);
2734                         err = -EIO;
2735                         goto next;
2736                 }
2737                 btrfs_tree_lock(eb);
2738                 btrfs_set_lock_blocking(eb);
2739
2740                 if (!node->eb) {
2741                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2742                                               slot, &eb);
2743                         btrfs_tree_unlock(eb);
2744                         free_extent_buffer(eb);
2745                         if (ret < 0) {
2746                                 err = ret;
2747                                 goto next;
2748                         }
2749                         BUG_ON(node->eb != eb);
2750                 } else {
2751                         btrfs_set_node_blockptr(upper->eb, slot,
2752                                                 node->eb->start);
2753                         btrfs_set_node_ptr_generation(upper->eb, slot,
2754                                                       trans->transid);
2755                         btrfs_mark_buffer_dirty(upper->eb);
2756
2757                         ret = btrfs_inc_extent_ref(trans, root,
2758                                                 node->eb->start, blocksize,
2759                                                 upper->eb->start,
2760                                                 btrfs_header_owner(upper->eb),
2761                                                 node->level, 0);
2762                         BUG_ON(ret);
2763
2764                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2765                         BUG_ON(ret);
2766                 }
2767 next:
2768                 if (!upper->pending)
2769                         drop_node_buffer(upper);
2770                 else
2771                         unlock_node_buffer(upper);
2772                 if (err)
2773                         break;
2774         }
2775
2776         if (!err && node->pending) {
2777                 drop_node_buffer(node);
2778                 list_move_tail(&node->list, &rc->backref_cache.changed);
2779                 node->pending = 0;
2780         }
2781
2782         path->lowest_level = 0;
2783         BUG_ON(err == -ENOSPC);
2784         return err;
2785 }
2786
2787 static int link_to_upper(struct btrfs_trans_handle *trans,
2788                          struct reloc_control *rc,
2789                          struct backref_node *node,
2790                          struct btrfs_path *path)
2791 {
2792         struct btrfs_key key;
2793
2794         btrfs_node_key_to_cpu(node->eb, &key, 0);
2795         return do_relocation(trans, rc, node, &key, path, 0);
2796 }
2797
2798 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2799                                 struct reloc_control *rc,
2800                                 struct btrfs_path *path, int err)
2801 {
2802         LIST_HEAD(list);
2803         struct backref_cache *cache = &rc->backref_cache;
2804         struct backref_node *node;
2805         int level;
2806         int ret;
2807
2808         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2809                 while (!list_empty(&cache->pending[level])) {
2810                         node = list_entry(cache->pending[level].next,
2811                                           struct backref_node, list);
2812                         list_move_tail(&node->list, &list);
2813                         BUG_ON(!node->pending);
2814
2815                         if (!err) {
2816                                 ret = link_to_upper(trans, rc, node, path);
2817                                 if (ret < 0)
2818                                         err = ret;
2819                         }
2820                 }
2821                 list_splice_init(&list, &cache->pending[level]);
2822         }
2823         return err;
2824 }
2825
2826 static void mark_block_processed(struct reloc_control *rc,
2827                                  u64 bytenr, u32 blocksize)
2828 {
2829         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2830                         EXTENT_DIRTY, GFP_NOFS);
2831 }
2832
2833 static void __mark_block_processed(struct reloc_control *rc,
2834                                    struct backref_node *node)
2835 {
2836         u32 blocksize;
2837         if (node->level == 0 ||
2838             in_block_group(node->bytenr, rc->block_group)) {
2839                 blocksize = rc->extent_root->nodesize;
2840                 mark_block_processed(rc, node->bytenr, blocksize);
2841         }
2842         node->processed = 1;
2843 }
2844
2845 /*
2846  * mark a block and all blocks directly/indirectly reference the block
2847  * as processed.
2848  */
2849 static void update_processed_blocks(struct reloc_control *rc,
2850                                     struct backref_node *node)
2851 {
2852         struct backref_node *next = node;
2853         struct backref_edge *edge;
2854         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2855         int index = 0;
2856
2857         while (next) {
2858                 cond_resched();
2859                 while (1) {
2860                         if (next->processed)
2861                                 break;
2862
2863                         __mark_block_processed(rc, next);
2864
2865                         if (list_empty(&next->upper))
2866                                 break;
2867
2868                         edge = list_entry(next->upper.next,
2869                                           struct backref_edge, list[LOWER]);
2870                         edges[index++] = edge;
2871                         next = edge->node[UPPER];
2872                 }
2873                 next = walk_down_backref(edges, &index);
2874         }
2875 }
2876
2877 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2878 {
2879         u32 blocksize = rc->extent_root->nodesize;
2880
2881         if (test_range_bit(&rc->processed_blocks, bytenr,
2882                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2883                 return 1;
2884         return 0;
2885 }
2886
2887 static int get_tree_block_key(struct reloc_control *rc,
2888                               struct tree_block *block)
2889 {
2890         struct extent_buffer *eb;
2891
2892         BUG_ON(block->key_ready);
2893         eb = read_tree_block(rc->extent_root, block->bytenr,
2894                              block->key.offset);
2895         if (IS_ERR(eb)) {
2896                 return PTR_ERR(eb);
2897         } else if (!extent_buffer_uptodate(eb)) {
2898                 free_extent_buffer(eb);
2899                 return -EIO;
2900         }
2901         WARN_ON(btrfs_header_level(eb) != block->level);
2902         if (block->level == 0)
2903                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2904         else
2905                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2906         free_extent_buffer(eb);
2907         block->key_ready = 1;
2908         return 0;
2909 }
2910
2911 /*
2912  * helper function to relocate a tree block
2913  */
2914 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2915                                 struct reloc_control *rc,
2916                                 struct backref_node *node,
2917                                 struct btrfs_key *key,
2918                                 struct btrfs_path *path)
2919 {
2920         struct btrfs_root *root;
2921         int ret = 0;
2922
2923         if (!node)
2924                 return 0;
2925
2926         BUG_ON(node->processed);
2927         root = select_one_root(node);
2928         if (root == ERR_PTR(-ENOENT)) {
2929                 update_processed_blocks(rc, node);
2930                 goto out;
2931         }
2932
2933         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2934                 ret = reserve_metadata_space(trans, rc, node);
2935                 if (ret)
2936                         goto out;
2937         }
2938
2939         if (root) {
2940                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2941                         BUG_ON(node->new_bytenr);
2942                         BUG_ON(!list_empty(&node->list));
2943                         btrfs_record_root_in_trans(trans, root);
2944                         root = root->reloc_root;
2945                         node->new_bytenr = root->node->start;
2946                         node->root = root;
2947                         list_add_tail(&node->list, &rc->backref_cache.changed);
2948                 } else {
2949                         path->lowest_level = node->level;
2950                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2951                         btrfs_release_path(path);
2952                         if (ret > 0)
2953                                 ret = 0;
2954                 }
2955                 if (!ret)
2956                         update_processed_blocks(rc, node);
2957         } else {
2958                 ret = do_relocation(trans, rc, node, key, path, 1);
2959         }
2960 out:
2961         if (ret || node->level == 0 || node->cowonly)
2962                 remove_backref_node(&rc->backref_cache, node);
2963         return ret;
2964 }
2965
2966 /*
2967  * relocate a list of blocks
2968  */
2969 static noinline_for_stack
2970 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2971                          struct reloc_control *rc, struct rb_root *blocks)
2972 {
2973         struct backref_node *node;
2974         struct btrfs_path *path;
2975         struct tree_block *block;
2976         struct rb_node *rb_node;
2977         int ret;
2978         int err = 0;
2979
2980         path = btrfs_alloc_path();
2981         if (!path) {
2982                 err = -ENOMEM;
2983                 goto out_free_blocks;
2984         }
2985
2986         rb_node = rb_first(blocks);
2987         while (rb_node) {
2988                 block = rb_entry(rb_node, struct tree_block, rb_node);
2989                 if (!block->key_ready)
2990                         readahead_tree_block(rc->extent_root, block->bytenr);
2991                 rb_node = rb_next(rb_node);
2992         }
2993
2994         rb_node = rb_first(blocks);
2995         while (rb_node) {
2996                 block = rb_entry(rb_node, struct tree_block, rb_node);
2997                 if (!block->key_ready) {
2998                         err = get_tree_block_key(rc, block);
2999                         if (err)
3000                                 goto out_free_path;
3001                 }
3002                 rb_node = rb_next(rb_node);
3003         }
3004
3005         rb_node = rb_first(blocks);
3006         while (rb_node) {
3007                 block = rb_entry(rb_node, struct tree_block, rb_node);
3008
3009                 node = build_backref_tree(rc, &block->key,
3010                                           block->level, block->bytenr);
3011                 if (IS_ERR(node)) {
3012                         err = PTR_ERR(node);
3013                         goto out;
3014                 }
3015
3016                 ret = relocate_tree_block(trans, rc, node, &block->key,
3017                                           path);
3018                 if (ret < 0) {
3019                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3020                                 err = ret;
3021                         goto out;
3022                 }
3023                 rb_node = rb_next(rb_node);
3024         }
3025 out:
3026         err = finish_pending_nodes(trans, rc, path, err);
3027
3028 out_free_path:
3029         btrfs_free_path(path);
3030 out_free_blocks:
3031         free_block_list(blocks);
3032         return err;
3033 }
3034
3035 static noinline_for_stack
3036 int prealloc_file_extent_cluster(struct inode *inode,
3037                                  struct file_extent_cluster *cluster)
3038 {
3039         u64 alloc_hint = 0;
3040         u64 start;
3041         u64 end;
3042         u64 offset = BTRFS_I(inode)->index_cnt;
3043         u64 num_bytes;
3044         int nr = 0;
3045         int ret = 0;
3046
3047         BUG_ON(cluster->start != cluster->boundary[0]);
3048         mutex_lock(&inode->i_mutex);
3049
3050         ret = btrfs_check_data_free_space(inode, cluster->start,
3051                                           cluster->end + 1 - cluster->start);
3052         if (ret)
3053                 goto out;
3054
3055         while (nr < cluster->nr) {
3056                 start = cluster->boundary[nr] - offset;
3057                 if (nr + 1 < cluster->nr)
3058                         end = cluster->boundary[nr + 1] - 1 - offset;
3059                 else
3060                         end = cluster->end - offset;
3061
3062                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3063                 num_bytes = end + 1 - start;
3064                 ret = btrfs_prealloc_file_range(inode, 0, start,
3065                                                 num_bytes, num_bytes,
3066                                                 end + 1, &alloc_hint);
3067                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3068                 if (ret)
3069                         break;
3070                 nr++;
3071         }
3072         btrfs_free_reserved_data_space(inode, cluster->start,
3073                                        cluster->end + 1 - cluster->start);
3074 out:
3075         mutex_unlock(&inode->i_mutex);
3076         return ret;
3077 }
3078
3079 static noinline_for_stack
3080 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3081                          u64 block_start)
3082 {
3083         struct btrfs_root *root = BTRFS_I(inode)->root;
3084         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3085         struct extent_map *em;
3086         int ret = 0;
3087
3088         em = alloc_extent_map();
3089         if (!em)
3090                 return -ENOMEM;
3091
3092         em->start = start;
3093         em->len = end + 1 - start;
3094         em->block_len = em->len;
3095         em->block_start = block_start;
3096         em->bdev = root->fs_info->fs_devices->latest_bdev;
3097         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3098
3099         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3100         while (1) {
3101                 write_lock(&em_tree->lock);
3102                 ret = add_extent_mapping(em_tree, em, 0);
3103                 write_unlock(&em_tree->lock);
3104                 if (ret != -EEXIST) {
3105                         free_extent_map(em);
3106                         break;
3107                 }
3108                 btrfs_drop_extent_cache(inode, start, end, 0);
3109         }
3110         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3111         return ret;
3112 }
3113
3114 static int relocate_file_extent_cluster(struct inode *inode,
3115                                         struct file_extent_cluster *cluster)
3116 {
3117         u64 page_start;
3118         u64 page_end;
3119         u64 offset = BTRFS_I(inode)->index_cnt;
3120         unsigned long index;
3121         unsigned long last_index;
3122         struct page *page;
3123         struct file_ra_state *ra;
3124         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3125         int nr = 0;
3126         int ret = 0;
3127
3128         if (!cluster->nr)
3129                 return 0;
3130
3131         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3132         if (!ra)
3133                 return -ENOMEM;
3134
3135         ret = prealloc_file_extent_cluster(inode, cluster);
3136         if (ret)
3137                 goto out;
3138
3139         file_ra_state_init(ra, inode->i_mapping);
3140
3141         ret = setup_extent_mapping(inode, cluster->start - offset,
3142                                    cluster->end - offset, cluster->start);
3143         if (ret)
3144                 goto out;
3145
3146         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3147         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3148         while (index <= last_index) {
3149                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3150                 if (ret)
3151                         goto out;
3152
3153                 page = find_lock_page(inode->i_mapping, index);
3154                 if (!page) {
3155                         page_cache_sync_readahead(inode->i_mapping,
3156                                                   ra, NULL, index,
3157                                                   last_index + 1 - index);
3158                         page = find_or_create_page(inode->i_mapping, index,
3159                                                    mask);
3160                         if (!page) {
3161                                 btrfs_delalloc_release_metadata(inode,
3162                                                         PAGE_CACHE_SIZE);
3163                                 ret = -ENOMEM;
3164                                 goto out;
3165                         }
3166                 }
3167
3168                 if (PageReadahead(page)) {
3169                         page_cache_async_readahead(inode->i_mapping,
3170                                                    ra, NULL, page, index,
3171                                                    last_index + 1 - index);
3172                 }
3173
3174                 if (!PageUptodate(page)) {
3175                         btrfs_readpage(NULL, page);
3176                         lock_page(page);
3177                         if (!PageUptodate(page)) {
3178                                 unlock_page(page);
3179                                 page_cache_release(page);
3180                                 btrfs_delalloc_release_metadata(inode,
3181                                                         PAGE_CACHE_SIZE);
3182                                 ret = -EIO;
3183                                 goto out;
3184                         }
3185                 }
3186
3187                 page_start = page_offset(page);
3188                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3189
3190                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3191
3192                 set_page_extent_mapped(page);
3193
3194                 if (nr < cluster->nr &&
3195                     page_start + offset == cluster->boundary[nr]) {
3196                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3197                                         page_start, page_end,
3198                                         EXTENT_BOUNDARY, GFP_NOFS);
3199                         nr++;
3200                 }
3201
3202                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3203                 set_page_dirty(page);
3204
3205                 unlock_extent(&BTRFS_I(inode)->io_tree,
3206                               page_start, page_end);
3207                 unlock_page(page);
3208                 page_cache_release(page);
3209
3210                 index++;
3211                 balance_dirty_pages_ratelimited(inode->i_mapping);
3212                 btrfs_throttle(BTRFS_I(inode)->root);
3213         }
3214         WARN_ON(nr != cluster->nr);
3215 out:
3216         kfree(ra);
3217         return ret;
3218 }
3219
3220 static noinline_for_stack
3221 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3222                          struct file_extent_cluster *cluster)
3223 {
3224         int ret;
3225
3226         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3227                 ret = relocate_file_extent_cluster(inode, cluster);
3228                 if (ret)
3229                         return ret;
3230                 cluster->nr = 0;
3231         }
3232
3233         if (!cluster->nr)
3234                 cluster->start = extent_key->objectid;
3235         else
3236                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3237         cluster->end = extent_key->objectid + extent_key->offset - 1;
3238         cluster->boundary[cluster->nr] = extent_key->objectid;
3239         cluster->nr++;
3240
3241         if (cluster->nr >= MAX_EXTENTS) {
3242                 ret = relocate_file_extent_cluster(inode, cluster);
3243                 if (ret)
3244                         return ret;
3245                 cluster->nr = 0;
3246         }
3247         return 0;
3248 }
3249
3250 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3251 static int get_ref_objectid_v0(struct reloc_control *rc,
3252                                struct btrfs_path *path,
3253                                struct btrfs_key *extent_key,
3254                                u64 *ref_objectid, int *path_change)
3255 {
3256         struct btrfs_key key;
3257         struct extent_buffer *leaf;
3258         struct btrfs_extent_ref_v0 *ref0;
3259         int ret;
3260         int slot;
3261
3262         leaf = path->nodes[0];
3263         slot = path->slots[0];
3264         while (1) {
3265                 if (slot >= btrfs_header_nritems(leaf)) {
3266                         ret = btrfs_next_leaf(rc->extent_root, path);
3267                         if (ret < 0)
3268                                 return ret;
3269                         BUG_ON(ret > 0);
3270                         leaf = path->nodes[0];
3271                         slot = path->slots[0];
3272                         if (path_change)
3273                                 *path_change = 1;
3274                 }
3275                 btrfs_item_key_to_cpu(leaf, &key, slot);
3276                 if (key.objectid != extent_key->objectid)
3277                         return -ENOENT;
3278
3279                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3280                         slot++;
3281                         continue;
3282                 }
3283                 ref0 = btrfs_item_ptr(leaf, slot,
3284                                 struct btrfs_extent_ref_v0);
3285                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3286                 break;
3287         }
3288         return 0;
3289 }
3290 #endif
3291
3292 /*
3293  * helper to add a tree block to the list.
3294  * the major work is getting the generation and level of the block
3295  */
3296 static int add_tree_block(struct reloc_control *rc,
3297                           struct btrfs_key *extent_key,
3298                           struct btrfs_path *path,
3299                           struct rb_root *blocks)
3300 {
3301         struct extent_buffer *eb;
3302         struct btrfs_extent_item *ei;
3303         struct btrfs_tree_block_info *bi;
3304         struct tree_block *block;
3305         struct rb_node *rb_node;
3306         u32 item_size;
3307         int level = -1;
3308         u64 generation;
3309
3310         eb =  path->nodes[0];
3311         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3312
3313         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3314             item_size >= sizeof(*ei) + sizeof(*bi)) {
3315                 ei = btrfs_item_ptr(eb, path->slots[0],
3316                                 struct btrfs_extent_item);
3317                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3318                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3319                         level = btrfs_tree_block_level(eb, bi);
3320                 } else {
3321                         level = (int)extent_key->offset;
3322                 }
3323                 generation = btrfs_extent_generation(eb, ei);
3324         } else {
3325 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3326                 u64 ref_owner;
3327                 int ret;
3328
3329                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3330                 ret = get_ref_objectid_v0(rc, path, extent_key,
3331                                           &ref_owner, NULL);
3332                 if (ret < 0)
3333                         return ret;
3334                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3335                 level = (int)ref_owner;
3336                 /* FIXME: get real generation */
3337                 generation = 0;
3338 #else
3339                 BUG();
3340 #endif
3341         }
3342
3343         btrfs_release_path(path);
3344
3345         BUG_ON(level == -1);
3346
3347         block = kmalloc(sizeof(*block), GFP_NOFS);
3348         if (!block)
3349                 return -ENOMEM;
3350
3351         block->bytenr = extent_key->objectid;
3352         block->key.objectid = rc->extent_root->nodesize;
3353         block->key.offset = generation;
3354         block->level = level;
3355         block->key_ready = 0;
3356
3357         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3358         if (rb_node)
3359                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3360
3361         return 0;
3362 }
3363
3364 /*
3365  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3366  */
3367 static int __add_tree_block(struct reloc_control *rc,
3368                             u64 bytenr, u32 blocksize,
3369                             struct rb_root *blocks)
3370 {
3371         struct btrfs_path *path;
3372         struct btrfs_key key;
3373         int ret;
3374         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3375                                         SKINNY_METADATA);
3376
3377         if (tree_block_processed(bytenr, rc))
3378                 return 0;
3379
3380         if (tree_search(blocks, bytenr))
3381                 return 0;
3382
3383         path = btrfs_alloc_path();
3384         if (!path)
3385                 return -ENOMEM;
3386 again:
3387         key.objectid = bytenr;
3388         if (skinny) {
3389                 key.type = BTRFS_METADATA_ITEM_KEY;
3390                 key.offset = (u64)-1;
3391         } else {
3392                 key.type = BTRFS_EXTENT_ITEM_KEY;
3393                 key.offset = blocksize;
3394         }
3395
3396         path->search_commit_root = 1;
3397         path->skip_locking = 1;
3398         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3399         if (ret < 0)
3400                 goto out;
3401
3402         if (ret > 0 && skinny) {
3403                 if (path->slots[0]) {
3404                         path->slots[0]--;
3405                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3406                                               path->slots[0]);
3407                         if (key.objectid == bytenr &&
3408                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3409                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3410                               key.offset == blocksize)))
3411                                 ret = 0;
3412                 }
3413
3414                 if (ret) {
3415                         skinny = false;
3416                         btrfs_release_path(path);
3417                         goto again;
3418                 }
3419         }
3420         BUG_ON(ret);
3421
3422         ret = add_tree_block(rc, &key, path, blocks);
3423 out:
3424         btrfs_free_path(path);
3425         return ret;
3426 }
3427
3428 /*
3429  * helper to check if the block use full backrefs for pointers in it
3430  */
3431 static int block_use_full_backref(struct reloc_control *rc,
3432                                   struct extent_buffer *eb)
3433 {
3434         u64 flags;
3435         int ret;
3436
3437         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3438             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3439                 return 1;
3440
3441         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3442                                        eb->start, btrfs_header_level(eb), 1,
3443                                        NULL, &flags);
3444         BUG_ON(ret);
3445
3446         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3447                 ret = 1;
3448         else
3449                 ret = 0;
3450         return ret;
3451 }
3452
3453 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3454                                     struct btrfs_block_group_cache *block_group,
3455                                     struct inode *inode,
3456                                     u64 ino)
3457 {
3458         struct btrfs_key key;
3459         struct btrfs_root *root = fs_info->tree_root;
3460         struct btrfs_trans_handle *trans;
3461         int ret = 0;
3462
3463         if (inode)
3464                 goto truncate;
3465
3466         key.objectid = ino;
3467         key.type = BTRFS_INODE_ITEM_KEY;
3468         key.offset = 0;
3469
3470         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3471         if (IS_ERR(inode) || is_bad_inode(inode)) {
3472                 if (!IS_ERR(inode))
3473                         iput(inode);
3474                 return -ENOENT;
3475         }
3476
3477 truncate:
3478         ret = btrfs_check_trunc_cache_free_space(root,
3479                                                  &fs_info->global_block_rsv);
3480         if (ret)
3481                 goto out;
3482
3483         trans = btrfs_join_transaction(root);
3484         if (IS_ERR(trans)) {
3485                 ret = PTR_ERR(trans);
3486                 goto out;
3487         }
3488
3489         ret = btrfs_truncate_free_space_cache(root, trans, block_group, inode);
3490
3491         btrfs_end_transaction(trans, root);
3492         btrfs_btree_balance_dirty(root);
3493 out:
3494         iput(inode);
3495         return ret;
3496 }
3497
3498 /*
3499  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3500  * this function scans fs tree to find blocks reference the data extent
3501  */
3502 static int find_data_references(struct reloc_control *rc,
3503                                 struct btrfs_key *extent_key,
3504                                 struct extent_buffer *leaf,
3505                                 struct btrfs_extent_data_ref *ref,
3506                                 struct rb_root *blocks)
3507 {
3508         struct btrfs_path *path;
3509         struct tree_block *block;
3510         struct btrfs_root *root;
3511         struct btrfs_file_extent_item *fi;
3512         struct rb_node *rb_node;
3513         struct btrfs_key key;
3514         u64 ref_root;
3515         u64 ref_objectid;
3516         u64 ref_offset;
3517         u32 ref_count;
3518         u32 nritems;
3519         int err = 0;
3520         int added = 0;
3521         int counted;
3522         int ret;
3523
3524         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3525         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3526         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3527         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3528
3529         /*
3530          * This is an extent belonging to the free space cache, lets just delete
3531          * it and redo the search.
3532          */
3533         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3534                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3535                                                rc->block_group,
3536                                                NULL, ref_objectid);
3537                 if (ret != -ENOENT)
3538                         return ret;
3539                 ret = 0;
3540         }
3541
3542         path = btrfs_alloc_path();
3543         if (!path)
3544                 return -ENOMEM;
3545         path->reada = 1;
3546
3547         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3548         if (IS_ERR(root)) {
3549                 err = PTR_ERR(root);
3550                 goto out;
3551         }
3552
3553         key.objectid = ref_objectid;
3554         key.type = BTRFS_EXTENT_DATA_KEY;
3555         if (ref_offset > ((u64)-1 << 32))
3556                 key.offset = 0;
3557         else
3558                 key.offset = ref_offset;
3559
3560         path->search_commit_root = 1;
3561         path->skip_locking = 1;
3562         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3563         if (ret < 0) {
3564                 err = ret;
3565                 goto out;
3566         }
3567
3568         leaf = path->nodes[0];
3569         nritems = btrfs_header_nritems(leaf);
3570         /*
3571          * the references in tree blocks that use full backrefs
3572          * are not counted in
3573          */
3574         if (block_use_full_backref(rc, leaf))
3575                 counted = 0;
3576         else
3577                 counted = 1;
3578         rb_node = tree_search(blocks, leaf->start);
3579         if (rb_node) {
3580                 if (counted)
3581                         added = 1;
3582                 else
3583                         path->slots[0] = nritems;
3584         }
3585
3586         while (ref_count > 0) {
3587                 while (path->slots[0] >= nritems) {
3588                         ret = btrfs_next_leaf(root, path);
3589                         if (ret < 0) {
3590                                 err = ret;
3591                                 goto out;
3592                         }
3593                         if (WARN_ON(ret > 0))
3594                                 goto out;
3595
3596                         leaf = path->nodes[0];
3597                         nritems = btrfs_header_nritems(leaf);
3598                         added = 0;
3599
3600                         if (block_use_full_backref(rc, leaf))
3601                                 counted = 0;
3602                         else
3603                                 counted = 1;
3604                         rb_node = tree_search(blocks, leaf->start);
3605                         if (rb_node) {
3606                                 if (counted)
3607                                         added = 1;
3608                                 else
3609                                         path->slots[0] = nritems;
3610                         }
3611                 }
3612
3613                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3614                 if (WARN_ON(key.objectid != ref_objectid ||
3615                     key.type != BTRFS_EXTENT_DATA_KEY))
3616                         break;
3617
3618                 fi = btrfs_item_ptr(leaf, path->slots[0],
3619                                     struct btrfs_file_extent_item);
3620
3621                 if (btrfs_file_extent_type(leaf, fi) ==
3622                     BTRFS_FILE_EXTENT_INLINE)
3623                         goto next;
3624
3625                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3626                     extent_key->objectid)
3627                         goto next;
3628
3629                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3630                 if (key.offset != ref_offset)
3631                         goto next;
3632
3633                 if (counted)
3634                         ref_count--;
3635                 if (added)
3636                         goto next;
3637
3638                 if (!tree_block_processed(leaf->start, rc)) {
3639                         block = kmalloc(sizeof(*block), GFP_NOFS);
3640                         if (!block) {
3641                                 err = -ENOMEM;
3642                                 break;
3643                         }
3644                         block->bytenr = leaf->start;
3645                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3646                         block->level = 0;
3647                         block->key_ready = 1;
3648                         rb_node = tree_insert(blocks, block->bytenr,
3649                                               &block->rb_node);
3650                         if (rb_node)
3651                                 backref_tree_panic(rb_node, -EEXIST,
3652                                                    block->bytenr);
3653                 }
3654                 if (counted)
3655                         added = 1;
3656                 else
3657                         path->slots[0] = nritems;
3658 next:
3659                 path->slots[0]++;
3660
3661         }
3662 out:
3663         btrfs_free_path(path);
3664         return err;
3665 }
3666
3667 /*
3668  * helper to find all tree blocks that reference a given data extent
3669  */
3670 static noinline_for_stack
3671 int add_data_references(struct reloc_control *rc,
3672                         struct btrfs_key *extent_key,
3673                         struct btrfs_path *path,
3674                         struct rb_root *blocks)
3675 {
3676         struct btrfs_key key;
3677         struct extent_buffer *eb;
3678         struct btrfs_extent_data_ref *dref;
3679         struct btrfs_extent_inline_ref *iref;
3680         unsigned long ptr;
3681         unsigned long end;
3682         u32 blocksize = rc->extent_root->nodesize;
3683         int ret = 0;
3684         int err = 0;
3685
3686         eb = path->nodes[0];
3687         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3688         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3689 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3690         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3691                 ptr = end;
3692         else
3693 #endif
3694                 ptr += sizeof(struct btrfs_extent_item);
3695
3696         while (ptr < end) {
3697                 iref = (struct btrfs_extent_inline_ref *)ptr;
3698                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3699                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3700                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3701                         ret = __add_tree_block(rc, key.offset, blocksize,
3702                                                blocks);
3703                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3704                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3705                         ret = find_data_references(rc, extent_key,
3706                                                    eb, dref, blocks);
3707                 } else {
3708                         BUG();
3709                 }
3710                 if (ret) {
3711                         err = ret;
3712                         goto out;
3713                 }
3714                 ptr += btrfs_extent_inline_ref_size(key.type);
3715         }
3716         WARN_ON(ptr > end);
3717
3718         while (1) {
3719                 cond_resched();
3720                 eb = path->nodes[0];
3721                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3722                         ret = btrfs_next_leaf(rc->extent_root, path);
3723                         if (ret < 0) {
3724                                 err = ret;
3725                                 break;
3726                         }
3727                         if (ret > 0)
3728                                 break;
3729                         eb = path->nodes[0];
3730                 }
3731
3732                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3733                 if (key.objectid != extent_key->objectid)
3734                         break;
3735
3736 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3737                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3738                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3739 #else
3740                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3741                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3742 #endif
3743                         ret = __add_tree_block(rc, key.offset, blocksize,
3744                                                blocks);
3745                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3746                         dref = btrfs_item_ptr(eb, path->slots[0],
3747                                               struct btrfs_extent_data_ref);
3748                         ret = find_data_references(rc, extent_key,
3749                                                    eb, dref, blocks);
3750                 } else {
3751                         ret = 0;
3752                 }
3753                 if (ret) {
3754                         err = ret;
3755                         break;
3756                 }
3757                 path->slots[0]++;
3758         }
3759 out:
3760         btrfs_release_path(path);
3761         if (err)
3762                 free_block_list(blocks);
3763         return err;
3764 }
3765
3766 /*
3767  * helper to find next unprocessed extent
3768  */
3769 static noinline_for_stack
3770 int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
3771                      struct btrfs_key *extent_key)
3772 {
3773         struct btrfs_key key;
3774         struct extent_buffer *leaf;
3775         u64 start, end, last;
3776         int ret;
3777
3778         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3779         while (1) {
3780                 cond_resched();
3781                 if (rc->search_start >= last) {
3782                         ret = 1;
3783                         break;
3784                 }
3785
3786                 key.objectid = rc->search_start;
3787                 key.type = BTRFS_EXTENT_ITEM_KEY;
3788                 key.offset = 0;
3789
3790                 path->search_commit_root = 1;
3791                 path->skip_locking = 1;
3792                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3793                                         0, 0);
3794                 if (ret < 0)
3795                         break;
3796 next:
3797                 leaf = path->nodes[0];
3798                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3799                         ret = btrfs_next_leaf(rc->extent_root, path);
3800                         if (ret != 0)
3801                                 break;
3802                         leaf = path->nodes[0];
3803                 }
3804
3805                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3806                 if (key.objectid >= last) {
3807                         ret = 1;
3808                         break;
3809                 }
3810
3811                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3812                     key.type != BTRFS_METADATA_ITEM_KEY) {
3813                         path->slots[0]++;
3814                         goto next;
3815                 }
3816
3817                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3818                     key.objectid + key.offset <= rc->search_start) {
3819                         path->slots[0]++;
3820                         goto next;
3821                 }
3822
3823                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3824                     key.objectid + rc->extent_root->nodesize <=
3825                     rc->search_start) {
3826                         path->slots[0]++;
3827                         goto next;
3828                 }
3829
3830                 ret = find_first_extent_bit(&rc->processed_blocks,
3831                                             key.objectid, &start, &end,
3832                                             EXTENT_DIRTY, NULL);
3833
3834                 if (ret == 0 && start <= key.objectid) {
3835                         btrfs_release_path(path);
3836                         rc->search_start = end + 1;
3837                 } else {
3838                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3839                                 rc->search_start = key.objectid + key.offset;
3840                         else
3841                                 rc->search_start = key.objectid +
3842                                         rc->extent_root->nodesize;
3843                         memcpy(extent_key, &key, sizeof(key));
3844                         return 0;
3845                 }
3846         }
3847         btrfs_release_path(path);
3848         return ret;
3849 }
3850
3851 static void set_reloc_control(struct reloc_control *rc)
3852 {
3853         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3854
3855         mutex_lock(&fs_info->reloc_mutex);
3856         fs_info->reloc_ctl = rc;
3857         mutex_unlock(&fs_info->reloc_mutex);
3858 }
3859
3860 static void unset_reloc_control(struct reloc_control *rc)
3861 {
3862         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3863
3864         mutex_lock(&fs_info->reloc_mutex);
3865         fs_info->reloc_ctl = NULL;
3866         mutex_unlock(&fs_info->reloc_mutex);
3867 }
3868
3869 static int check_extent_flags(u64 flags)
3870 {
3871         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3872             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3873                 return 1;
3874         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3875             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3876                 return 1;
3877         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3878             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3879                 return 1;
3880         return 0;
3881 }
3882
3883 static noinline_for_stack
3884 int prepare_to_relocate(struct reloc_control *rc)
3885 {
3886         struct btrfs_trans_handle *trans;
3887
3888         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3889                                               BTRFS_BLOCK_RSV_TEMP);
3890         if (!rc->block_rsv)
3891                 return -ENOMEM;
3892
3893         memset(&rc->cluster, 0, sizeof(rc->cluster));
3894         rc->search_start = rc->block_group->key.objectid;
3895         rc->extents_found = 0;
3896         rc->nodes_relocated = 0;
3897         rc->merging_rsv_size = 0;
3898         rc->reserved_bytes = 0;
3899         rc->block_rsv->size = rc->extent_root->nodesize *
3900                               RELOCATION_RESERVED_NODES;
3901
3902         rc->create_reloc_tree = 1;
3903         set_reloc_control(rc);
3904
3905         trans = btrfs_join_transaction(rc->extent_root);
3906         if (IS_ERR(trans)) {
3907                 unset_reloc_control(rc);
3908                 /*
3909                  * extent tree is not a ref_cow tree and has no reloc_root to
3910                  * cleanup.  And callers are responsible to free the above
3911                  * block rsv.
3912                  */
3913                 return PTR_ERR(trans);
3914         }
3915         btrfs_commit_transaction(trans, rc->extent_root);
3916         return 0;
3917 }
3918
3919 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3920 {
3921         struct rb_root blocks = RB_ROOT;
3922         struct btrfs_key key;
3923         struct btrfs_trans_handle *trans = NULL;
3924         struct btrfs_path *path;
3925         struct btrfs_extent_item *ei;
3926         u64 flags;
3927         u32 item_size;
3928         int ret;
3929         int err = 0;
3930         int progress = 0;
3931
3932         path = btrfs_alloc_path();
3933         if (!path)
3934                 return -ENOMEM;
3935         path->reada = 1;
3936
3937         ret = prepare_to_relocate(rc);
3938         if (ret) {
3939                 err = ret;
3940                 goto out_free;
3941         }
3942
3943         while (1) {
3944                 rc->reserved_bytes = 0;
3945                 ret = btrfs_block_rsv_refill(rc->extent_root,
3946                                         rc->block_rsv, rc->block_rsv->size,
3947                                         BTRFS_RESERVE_FLUSH_ALL);
3948                 if (ret) {
3949                         err = ret;
3950                         break;
3951                 }
3952                 progress++;
3953                 trans = btrfs_start_transaction(rc->extent_root, 0);
3954                 if (IS_ERR(trans)) {
3955                         err = PTR_ERR(trans);
3956                         trans = NULL;
3957                         break;
3958                 }
3959 restart:
3960                 if (update_backref_cache(trans, &rc->backref_cache)) {
3961                         btrfs_end_transaction(trans, rc->extent_root);
3962                         continue;
3963                 }
3964
3965                 ret = find_next_extent(rc, path, &key);
3966                 if (ret < 0)
3967                         err = ret;
3968                 if (ret != 0)
3969                         break;
3970
3971                 rc->extents_found++;
3972
3973                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3974                                     struct btrfs_extent_item);
3975                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3976                 if (item_size >= sizeof(*ei)) {
3977                         flags = btrfs_extent_flags(path->nodes[0], ei);
3978                         ret = check_extent_flags(flags);
3979                         BUG_ON(ret);
3980
3981                 } else {
3982 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3983                         u64 ref_owner;
3984                         int path_change = 0;
3985
3986                         BUG_ON(item_size !=
3987                                sizeof(struct btrfs_extent_item_v0));
3988                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3989                                                   &path_change);
3990                         if (ret < 0) {
3991                                 err = ret;
3992                                 break;
3993                         }
3994                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3995                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3996                         else
3997                                 flags = BTRFS_EXTENT_FLAG_DATA;
3998
3999                         if (path_change) {
4000                                 btrfs_release_path(path);
4001
4002                                 path->search_commit_root = 1;
4003                                 path->skip_locking = 1;
4004                                 ret = btrfs_search_slot(NULL, rc->extent_root,
4005                                                         &key, path, 0, 0);
4006                                 if (ret < 0) {
4007                                         err = ret;
4008                                         break;
4009                                 }
4010                                 BUG_ON(ret > 0);
4011                         }
4012 #else
4013                         BUG();
4014 #endif
4015                 }
4016
4017                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4018                         ret = add_tree_block(rc, &key, path, &blocks);
4019                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4020                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4021                         ret = add_data_references(rc, &key, path, &blocks);
4022                 } else {
4023                         btrfs_release_path(path);
4024                         ret = 0;
4025                 }
4026                 if (ret < 0) {
4027                         err = ret;
4028                         break;
4029                 }
4030
4031                 if (!RB_EMPTY_ROOT(&blocks)) {
4032                         ret = relocate_tree_blocks(trans, rc, &blocks);
4033                         if (ret < 0) {
4034                                 /*
4035                                  * if we fail to relocate tree blocks, force to update
4036                                  * backref cache when committing transaction.
4037                                  */
4038                                 rc->backref_cache.last_trans = trans->transid - 1;
4039
4040                                 if (ret != -EAGAIN) {
4041                                         err = ret;
4042                                         break;
4043                                 }
4044                                 rc->extents_found--;
4045                                 rc->search_start = key.objectid;
4046                         }
4047                 }
4048
4049                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4050                 btrfs_btree_balance_dirty(rc->extent_root);
4051                 trans = NULL;
4052
4053                 if (rc->stage == MOVE_DATA_EXTENTS &&
4054                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4055                         rc->found_file_extent = 1;
4056                         ret = relocate_data_extent(rc->data_inode,
4057                                                    &key, &rc->cluster);
4058                         if (ret < 0) {
4059                                 err = ret;
4060                                 break;
4061                         }
4062                 }
4063         }
4064         if (trans && progress && err == -ENOSPC) {
4065                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4066                                               rc->block_group->flags);
4067                 if (ret == 1) {
4068                         err = 0;
4069                         progress = 0;
4070                         goto restart;
4071                 }
4072         }
4073
4074         btrfs_release_path(path);
4075         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4076                           GFP_NOFS);
4077
4078         if (trans) {
4079                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4080                 btrfs_btree_balance_dirty(rc->extent_root);
4081         }
4082
4083         if (!err) {
4084                 ret = relocate_file_extent_cluster(rc->data_inode,
4085                                                    &rc->cluster);
4086                 if (ret < 0)
4087                         err = ret;
4088         }
4089
4090         rc->create_reloc_tree = 0;
4091         set_reloc_control(rc);
4092
4093         backref_cache_cleanup(&rc->backref_cache);
4094         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4095
4096         err = prepare_to_merge(rc, err);
4097
4098         merge_reloc_roots(rc);
4099
4100         rc->merge_reloc_tree = 0;
4101         unset_reloc_control(rc);
4102         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4103
4104         /* get rid of pinned extents */
4105         trans = btrfs_join_transaction(rc->extent_root);
4106         if (IS_ERR(trans))
4107                 err = PTR_ERR(trans);
4108         else
4109                 btrfs_commit_transaction(trans, rc->extent_root);
4110 out_free:
4111         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4112         btrfs_free_path(path);
4113         return err;
4114 }
4115
4116 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4117                                  struct btrfs_root *root, u64 objectid)
4118 {
4119         struct btrfs_path *path;
4120         struct btrfs_inode_item *item;
4121         struct extent_buffer *leaf;
4122         int ret;
4123
4124         path = btrfs_alloc_path();
4125         if (!path)
4126                 return -ENOMEM;
4127
4128         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4129         if (ret)
4130                 goto out;
4131
4132         leaf = path->nodes[0];
4133         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4134         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4135         btrfs_set_inode_generation(leaf, item, 1);
4136         btrfs_set_inode_size(leaf, item, 0);
4137         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4138         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4139                                           BTRFS_INODE_PREALLOC);
4140         btrfs_mark_buffer_dirty(leaf);
4141 out:
4142         btrfs_free_path(path);
4143         return ret;
4144 }
4145
4146 /*
4147  * helper to create inode for data relocation.
4148  * the inode is in data relocation tree and its link count is 0
4149  */
4150 static noinline_for_stack
4151 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4152                                  struct btrfs_block_group_cache *group)
4153 {
4154         struct inode *inode = NULL;
4155         struct btrfs_trans_handle *trans;
4156         struct btrfs_root *root;
4157         struct btrfs_key key;
4158         u64 objectid;
4159         int err = 0;
4160
4161         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4162         if (IS_ERR(root))
4163                 return ERR_CAST(root);
4164
4165         trans = btrfs_start_transaction(root, 6);
4166         if (IS_ERR(trans))
4167                 return ERR_CAST(trans);
4168
4169         err = btrfs_find_free_objectid(root, &objectid);
4170         if (err)
4171                 goto out;
4172
4173         err = __insert_orphan_inode(trans, root, objectid);
4174         BUG_ON(err);
4175
4176         key.objectid = objectid;
4177         key.type = BTRFS_INODE_ITEM_KEY;
4178         key.offset = 0;
4179         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4180         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4181         BTRFS_I(inode)->index_cnt = group->key.objectid;
4182
4183         err = btrfs_orphan_add(trans, inode);
4184 out:
4185         btrfs_end_transaction(trans, root);
4186         btrfs_btree_balance_dirty(root);
4187         if (err) {
4188                 if (inode)
4189                         iput(inode);
4190                 inode = ERR_PTR(err);
4191         }
4192         return inode;
4193 }
4194
4195 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4196 {
4197         struct reloc_control *rc;
4198
4199         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4200         if (!rc)
4201                 return NULL;
4202
4203         INIT_LIST_HEAD(&rc->reloc_roots);
4204         backref_cache_init(&rc->backref_cache);
4205         mapping_tree_init(&rc->reloc_root_tree);
4206         extent_io_tree_init(&rc->processed_blocks,
4207                             fs_info->btree_inode->i_mapping);
4208         return rc;
4209 }
4210
4211 /*
4212  * function to relocate all extents in a block group.
4213  */
4214 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4215 {
4216         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4217         struct reloc_control *rc;
4218         struct inode *inode;
4219         struct btrfs_path *path;
4220         int ret;
4221         int rw = 0;
4222         int err = 0;
4223
4224         rc = alloc_reloc_control(fs_info);
4225         if (!rc)
4226                 return -ENOMEM;
4227
4228         rc->extent_root = extent_root;
4229
4230         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4231         BUG_ON(!rc->block_group);
4232
4233         ret = btrfs_inc_block_group_ro(extent_root, rc->block_group);
4234         if (ret) {
4235                 err = ret;
4236                 goto out;
4237         }
4238         rw = 1;
4239
4240         path = btrfs_alloc_path();
4241         if (!path) {
4242                 err = -ENOMEM;
4243                 goto out;
4244         }
4245
4246         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4247                                         path);
4248         btrfs_free_path(path);
4249
4250         if (!IS_ERR(inode))
4251                 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4252         else
4253                 ret = PTR_ERR(inode);
4254
4255         if (ret && ret != -ENOENT) {
4256                 err = ret;
4257                 goto out;
4258         }
4259
4260         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4261         if (IS_ERR(rc->data_inode)) {
4262                 err = PTR_ERR(rc->data_inode);
4263                 rc->data_inode = NULL;
4264                 goto out;
4265         }
4266
4267         btrfs_info(extent_root->fs_info, "relocating block group %llu flags %llu",
4268                rc->block_group->key.objectid, rc->block_group->flags);
4269
4270         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
4271         if (ret < 0) {
4272                 err = ret;
4273                 goto out;
4274         }
4275         btrfs_wait_ordered_roots(fs_info, -1);
4276
4277         while (1) {
4278                 mutex_lock(&fs_info->cleaner_mutex);
4279                 ret = relocate_block_group(rc);
4280                 mutex_unlock(&fs_info->cleaner_mutex);
4281                 if (ret < 0) {
4282                         err = ret;
4283                         goto out;
4284                 }
4285
4286                 if (rc->extents_found == 0)
4287                         break;
4288
4289                 btrfs_info(extent_root->fs_info, "found %llu extents",
4290                         rc->extents_found);
4291
4292                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4293                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4294                                                        (u64)-1);
4295                         if (ret) {
4296                                 err = ret;
4297                                 goto out;
4298                         }
4299                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4300                                                  0, -1);
4301                         rc->stage = UPDATE_DATA_PTRS;
4302                 }
4303         }
4304
4305         WARN_ON(rc->block_group->pinned > 0);
4306         WARN_ON(rc->block_group->reserved > 0);
4307         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4308 out:
4309         if (err && rw)
4310                 btrfs_dec_block_group_ro(extent_root, rc->block_group);
4311         iput(rc->data_inode);
4312         btrfs_put_block_group(rc->block_group);
4313         kfree(rc);
4314         return err;
4315 }
4316
4317 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4318 {
4319         struct btrfs_trans_handle *trans;
4320         int ret, err;
4321
4322         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4323         if (IS_ERR(trans))
4324                 return PTR_ERR(trans);
4325
4326         memset(&root->root_item.drop_progress, 0,
4327                 sizeof(root->root_item.drop_progress));
4328         root->root_item.drop_level = 0;
4329         btrfs_set_root_refs(&root->root_item, 0);
4330         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4331                                 &root->root_key, &root->root_item);
4332
4333         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4334         if (err)
4335                 return err;
4336         return ret;
4337 }
4338
4339 /*
4340  * recover relocation interrupted by system crash.
4341  *
4342  * this function resumes merging reloc trees with corresponding fs trees.
4343  * this is important for keeping the sharing of tree blocks
4344  */
4345 int btrfs_recover_relocation(struct btrfs_root *root)
4346 {
4347         LIST_HEAD(reloc_roots);
4348         struct btrfs_key key;
4349         struct btrfs_root *fs_root;
4350         struct btrfs_root *reloc_root;
4351         struct btrfs_path *path;
4352         struct extent_buffer *leaf;
4353         struct reloc_control *rc = NULL;
4354         struct btrfs_trans_handle *trans;
4355         int ret;
4356         int err = 0;
4357
4358         path = btrfs_alloc_path();
4359         if (!path)
4360                 return -ENOMEM;
4361         path->reada = -1;
4362
4363         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4364         key.type = BTRFS_ROOT_ITEM_KEY;
4365         key.offset = (u64)-1;
4366
4367         while (1) {
4368                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4369                                         path, 0, 0);
4370                 if (ret < 0) {
4371                         err = ret;
4372                         goto out;
4373                 }
4374                 if (ret > 0) {
4375                         if (path->slots[0] == 0)
4376                                 break;
4377                         path->slots[0]--;
4378                 }
4379                 leaf = path->nodes[0];
4380                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4381                 btrfs_release_path(path);
4382
4383                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4384                     key.type != BTRFS_ROOT_ITEM_KEY)
4385                         break;
4386
4387                 reloc_root = btrfs_read_fs_root(root, &key);
4388                 if (IS_ERR(reloc_root)) {
4389                         err = PTR_ERR(reloc_root);
4390                         goto out;
4391                 }
4392
4393                 list_add(&reloc_root->root_list, &reloc_roots);
4394
4395                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4396                         fs_root = read_fs_root(root->fs_info,
4397                                                reloc_root->root_key.offset);
4398                         if (IS_ERR(fs_root)) {
4399                                 ret = PTR_ERR(fs_root);
4400                                 if (ret != -ENOENT) {
4401                                         err = ret;
4402                                         goto out;
4403                                 }
4404                                 ret = mark_garbage_root(reloc_root);
4405                                 if (ret < 0) {
4406                                         err = ret;
4407                                         goto out;
4408                                 }
4409                         }
4410                 }
4411
4412                 if (key.offset == 0)
4413                         break;
4414
4415                 key.offset--;
4416         }
4417         btrfs_release_path(path);
4418
4419         if (list_empty(&reloc_roots))
4420                 goto out;
4421
4422         rc = alloc_reloc_control(root->fs_info);
4423         if (!rc) {
4424                 err = -ENOMEM;
4425                 goto out;
4426         }
4427
4428         rc->extent_root = root->fs_info->extent_root;
4429
4430         set_reloc_control(rc);
4431
4432         trans = btrfs_join_transaction(rc->extent_root);
4433         if (IS_ERR(trans)) {
4434                 unset_reloc_control(rc);
4435                 err = PTR_ERR(trans);
4436                 goto out_free;
4437         }
4438
4439         rc->merge_reloc_tree = 1;
4440
4441         while (!list_empty(&reloc_roots)) {
4442                 reloc_root = list_entry(reloc_roots.next,
4443                                         struct btrfs_root, root_list);
4444                 list_del(&reloc_root->root_list);
4445
4446                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4447                         list_add_tail(&reloc_root->root_list,
4448                                       &rc->reloc_roots);
4449                         continue;
4450                 }
4451
4452                 fs_root = read_fs_root(root->fs_info,
4453                                        reloc_root->root_key.offset);
4454                 if (IS_ERR(fs_root)) {
4455                         err = PTR_ERR(fs_root);
4456                         goto out_free;
4457                 }
4458
4459                 err = __add_reloc_root(reloc_root);
4460                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4461                 fs_root->reloc_root = reloc_root;
4462         }
4463
4464         err = btrfs_commit_transaction(trans, rc->extent_root);
4465         if (err)
4466                 goto out_free;
4467
4468         merge_reloc_roots(rc);
4469
4470         unset_reloc_control(rc);
4471
4472         trans = btrfs_join_transaction(rc->extent_root);
4473         if (IS_ERR(trans))
4474                 err = PTR_ERR(trans);
4475         else
4476                 err = btrfs_commit_transaction(trans, rc->extent_root);
4477 out_free:
4478         kfree(rc);
4479 out:
4480         if (!list_empty(&reloc_roots))
4481                 free_reloc_roots(&reloc_roots);
4482
4483         btrfs_free_path(path);
4484
4485         if (err == 0) {
4486                 /* cleanup orphan inode in data relocation tree */
4487                 fs_root = read_fs_root(root->fs_info,
4488                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4489                 if (IS_ERR(fs_root))
4490                         err = PTR_ERR(fs_root);
4491                 else
4492                         err = btrfs_orphan_cleanup(fs_root);
4493         }
4494         return err;
4495 }
4496
4497 /*
4498  * helper to add ordered checksum for data relocation.
4499  *
4500  * cloning checksum properly handles the nodatasum extents.
4501  * it also saves CPU time to re-calculate the checksum.
4502  */
4503 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4504 {
4505         struct btrfs_ordered_sum *sums;
4506         struct btrfs_ordered_extent *ordered;
4507         struct btrfs_root *root = BTRFS_I(inode)->root;
4508         int ret;
4509         u64 disk_bytenr;
4510         u64 new_bytenr;
4511         LIST_HEAD(list);
4512
4513         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4514         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4515
4516         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4517         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4518                                        disk_bytenr + len - 1, &list, 0);
4519         if (ret)
4520                 goto out;
4521
4522         while (!list_empty(&list)) {
4523                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4524                 list_del_init(&sums->list);
4525
4526                 /*
4527                  * We need to offset the new_bytenr based on where the csum is.
4528                  * We need to do this because we will read in entire prealloc
4529                  * extents but we may have written to say the middle of the
4530                  * prealloc extent, so we need to make sure the csum goes with
4531                  * the right disk offset.
4532                  *
4533                  * We can do this because the data reloc inode refers strictly
4534                  * to the on disk bytes, so we don't have to worry about
4535                  * disk_len vs real len like with real inodes since it's all
4536                  * disk length.
4537                  */
4538                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4539                 sums->bytenr = new_bytenr;
4540
4541                 btrfs_add_ordered_sum(inode, ordered, sums);
4542         }
4543 out:
4544         btrfs_put_ordered_extent(ordered);
4545         return ret;
4546 }
4547
4548 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4549                           struct btrfs_root *root, struct extent_buffer *buf,
4550                           struct extent_buffer *cow)
4551 {
4552         struct reloc_control *rc;
4553         struct backref_node *node;
4554         int first_cow = 0;
4555         int level;
4556         int ret = 0;
4557
4558         rc = root->fs_info->reloc_ctl;
4559         if (!rc)
4560                 return 0;
4561
4562         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4563                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4564
4565         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4566                 if (buf == root->node)
4567                         __update_reloc_root(root, cow->start);
4568         }
4569
4570         level = btrfs_header_level(buf);
4571         if (btrfs_header_generation(buf) <=
4572             btrfs_root_last_snapshot(&root->root_item))
4573                 first_cow = 1;
4574
4575         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4576             rc->create_reloc_tree) {
4577                 WARN_ON(!first_cow && level == 0);
4578
4579                 node = rc->backref_cache.path[level];
4580                 BUG_ON(node->bytenr != buf->start &&
4581                        node->new_bytenr != buf->start);
4582
4583                 drop_node_buffer(node);
4584                 extent_buffer_get(cow);
4585                 node->eb = cow;
4586                 node->new_bytenr = cow->start;
4587
4588                 if (!node->pending) {
4589                         list_move_tail(&node->list,
4590                                        &rc->backref_cache.pending[level]);
4591                         node->pending = 1;
4592                 }
4593
4594                 if (first_cow)
4595                         __mark_block_processed(rc, node);
4596
4597                 if (first_cow && level > 0)
4598                         rc->nodes_relocated += buf->len;
4599         }
4600
4601         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4602                 ret = replace_file_extents(trans, rc, root, cow);
4603         return ret;
4604 }
4605
4606 /*
4607  * called before creating snapshot. it calculates metadata reservation
4608  * requried for relocating tree blocks in the snapshot
4609  */
4610 void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
4611                               u64 *bytes_to_reserve)
4612 {
4613         struct btrfs_root *root;
4614         struct reloc_control *rc;
4615
4616         root = pending->root;
4617         if (!root->reloc_root)
4618                 return;
4619
4620         rc = root->fs_info->reloc_ctl;
4621         if (!rc->merge_reloc_tree)
4622                 return;
4623
4624         root = root->reloc_root;
4625         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4626         /*
4627          * relocation is in the stage of merging trees. the space
4628          * used by merging a reloc tree is twice the size of
4629          * relocated tree nodes in the worst case. half for cowing
4630          * the reloc tree, half for cowing the fs tree. the space
4631          * used by cowing the reloc tree will be freed after the
4632          * tree is dropped. if we create snapshot, cowing the fs
4633          * tree may use more space than it frees. so we need
4634          * reserve extra space.
4635          */
4636         *bytes_to_reserve += rc->nodes_relocated;
4637 }
4638
4639 /*
4640  * called after snapshot is created. migrate block reservation
4641  * and create reloc root for the newly created snapshot
4642  */
4643 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4644                                struct btrfs_pending_snapshot *pending)
4645 {
4646         struct btrfs_root *root = pending->root;
4647         struct btrfs_root *reloc_root;
4648         struct btrfs_root *new_root;
4649         struct reloc_control *rc;
4650         int ret;
4651
4652         if (!root->reloc_root)
4653                 return 0;
4654
4655         rc = root->fs_info->reloc_ctl;
4656         rc->merging_rsv_size += rc->nodes_relocated;
4657
4658         if (rc->merge_reloc_tree) {
4659                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4660                                               rc->block_rsv,
4661                                               rc->nodes_relocated);
4662                 if (ret)
4663                         return ret;
4664         }
4665
4666         new_root = pending->snap;
4667         reloc_root = create_reloc_root(trans, root->reloc_root,
4668                                        new_root->root_key.objectid);
4669         if (IS_ERR(reloc_root))
4670                 return PTR_ERR(reloc_root);
4671
4672         ret = __add_reloc_root(reloc_root);
4673         BUG_ON(ret < 0);
4674         new_root->reloc_root = reloc_root;
4675
4676         if (rc->create_reloc_tree)
4677                 ret = clone_backref_node(trans, rc, root, reloc_root);
4678         return ret;
4679 }