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