fs/btrfs/relocation.c

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