fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97
  98 struct backref_cache {
  99         /* red black tree of all backref nodes in the cache */
 100         struct rb_root rb_root;
 101         /* for passing backref nodes to btrfs_reloc_cow_block */
 102         struct backref_node *path[BTRFS_MAX_LEVEL];
 103         /*
 104          * list of blocks that have been cowed but some block
 105          * pointers in upper level blocks may not reflect the
 106          * new location
 107          */
 108         struct list_head pending[BTRFS_MAX_LEVEL];
 109         /* list of backref nodes with no child node */
 110         struct list_head leaves;
 111         /* list of blocks that have been cowed in current transaction */
 112         struct list_head changed;
 113         /* list of detached backref node. */
 114         struct list_head detached;
 115
 116         u64 last_trans;
 117
 118         int nr_nodes;
 119         int nr_edges;
 120 };
 121
 122 /*
 123  * map address of tree root to tree
 124  */
 125 struct mapping_node {
 126         struct rb_node rb_node;
 127         u64 bytenr;
 128         void *data;
 129 };
 130
 131 struct mapping_tree {
 132         struct rb_root rb_root;
 133         spinlock_t lock;
 134 };
 135
 136 /*
 137  * present a tree block to process
 138  */
 139 struct tree_block {
 140         struct rb_node rb_node;
 141         u64 bytenr;
 142         struct btrfs_key key;
 143         unsigned int level:8;
 144         unsigned int key_ready:1;
 145 };
 146
 147 #define MAX_EXTENTS 128
 148
 149 struct file_extent_cluster {
 150         u64 start;
 151         u64 end;
 152         u64 boundary[MAX_EXTENTS];
 153         unsigned int nr;
 154 };
 155
 156 struct reloc_control {
 157         /* block group to relocate */
 158         struct btrfs_block_group_cache *block_group;
 159         /* extent tree */
 160         struct btrfs_root *extent_root;
 161         /* inode for moving data */
 162         struct inode *data_inode;
 163
 164         struct btrfs_block_rsv *block_rsv;
 165
 166         struct backref_cache backref_cache;
 167
 168         struct file_extent_cluster cluster;
 169         /* tree blocks have been processed */
 170         struct extent_io_tree processed_blocks;
 171         /* map start of tree root to corresponding reloc tree */
 172         struct mapping_tree reloc_root_tree;
 173         /* list of reloc trees */
 174         struct list_head reloc_roots;
 175         /* size of metadata reservation for merging reloc trees */
 176         u64 merging_rsv_size;
 177         /* size of relocated tree nodes */
 178         u64 nodes_relocated;
 179
 180         u64 search_start;
 181         u64 extents_found;
 182
 183         unsigned int stage:8;
 184         unsigned int create_reloc_tree:1;
 185         unsigned int merge_reloc_tree:1;
 186         unsigned int found_file_extent:1;
 187         unsigned int commit_transaction:1;
 188 };
 189
 190 /* stages of data relocation */
 191 #define MOVE_DATA_EXTENTS       0
 192 #define UPDATE_DATA_PTRS        1
 193
 194 static void remove_backref_node(struct backref_cache *cache,
 195                                 struct backref_node *node);
 196 static void __mark_block_processed(struct reloc_control *rc,
 197                                    struct backref_node *node);
 198
 199 static void mapping_tree_init(struct mapping_tree *tree)
 200 {
 201         tree->rb_root = RB_ROOT;
 202         spin_lock_init(&tree->lock);
 203 }
 204
 205 static void backref_cache_init(struct backref_cache *cache)
 206 {
 207         int i;
 208         cache->rb_root = RB_ROOT;
 209         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 210                 INIT_LIST_HEAD(&cache->pending[i]);
 211         INIT_LIST_HEAD(&cache->changed);
 212         INIT_LIST_HEAD(&cache->detached);
 213         INIT_LIST_HEAD(&cache->leaves);
 214 }
 215
 216 static void backref_cache_cleanup(struct backref_cache *cache)
 217 {
 218         struct backref_node *node;
 219         int i;
 220
 221         while (!list_empty(&cache->detached)) {
 222                 node = list_entry(cache->detached.next,
 223                                   struct backref_node, list);
 224                 remove_backref_node(cache, node);
 225         }
 226
 227         while (!list_empty(&cache->leaves)) {
 228                 node = list_entry(cache->leaves.next,
 229                                   struct backref_node, lower);
 230                 remove_backref_node(cache, node);
 231         }
 232
 233         cache->last_trans = 0;
 234
 235         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 236                 BUG_ON(!list_empty(&cache->pending[i]));
 237         BUG_ON(!list_empty(&cache->changed));
 238         BUG_ON(!list_empty(&cache->detached));
 239         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 240         BUG_ON(cache->nr_nodes);
 241         BUG_ON(cache->nr_edges);
 242 }
 243
 244 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 245 {
 246         struct backref_node *node;
 247
 248         node = kzalloc(sizeof(*node), GFP_NOFS);
 249         if (node) {
 250                 INIT_LIST_HEAD(&node->list);
 251                 INIT_LIST_HEAD(&node->upper);
 252                 INIT_LIST_HEAD(&node->lower);
 253                 RB_CLEAR_NODE(&node->rb_node);
 254                 cache->nr_nodes++;
 255         }
 256         return node;
 257 }
 258
 259 static void free_backref_node(struct backref_cache *cache,
 260                               struct backref_node *node)
 261 {
 262         if (node) {
 263                 cache->nr_nodes--;
 264                 kfree(node);
 265         }
 266 }
 267
 268 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 269 {
 270         struct backref_edge *edge;
 271
 272         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 273         if (edge)
 274                 cache->nr_edges++;
 275         return edge;
 276 }
 277
 278 static void free_backref_edge(struct backref_cache *cache,
 279                               struct backref_edge *edge)
 280 {
 281         if (edge) {
 282                 cache->nr_edges--;
 283                 kfree(edge);
 284         }
 285 }
 286
 287 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 288                                    struct rb_node *node)
 289 {
 290         struct rb_node **p = &root->rb_node;
 291         struct rb_node *parent = NULL;
 292         struct tree_entry *entry;
 293
 294         while (*p) {
 295                 parent = *p;
 296                 entry = rb_entry(parent, struct tree_entry, rb_node);
 297
 298                 if (bytenr < entry->bytenr)
 299                         p = &(*p)->rb_left;
 300                 else if (bytenr > entry->bytenr)
 301                         p = &(*p)->rb_right;
 302                 else
 303                         return parent;
 304         }
 305
 306         rb_link_node(node, parent, p);
 307         rb_insert_color(node, root);
 308         return NULL;
 309 }
 310
 311 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 312 {
 313         struct rb_node *n = root->rb_node;
 314         struct tree_entry *entry;
 315
 316         while (n) {
 317                 entry = rb_entry(n, struct tree_entry, rb_node);
 318
 319                 if (bytenr < entry->bytenr)
 320                         n = n->rb_left;
 321                 else if (bytenr > entry->bytenr)
 322                         n = n->rb_right;
 323                 else
 324                         return n;
 325         }
 326         return NULL;
 327 }
 328
 329 void backref_tree_panic(struct rb_node *rb_node, int errno,
 330                                           u64 bytenr)
 331 {
 332
 333         struct btrfs_fs_info *fs_info = NULL;
 334         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 335                                               rb_node);
 336         if (bnode->root)
 337                 fs_info = bnode->root->fs_info;
 338         btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 339                     "found at offset %llu\n", (unsigned long long)bytenr);
 340 }
 341
 342 /*
 343  * walk up backref nodes until reach node presents tree root
 344  */
 345 static struct backref_node *walk_up_backref(struct backref_node *node,
 346                                             struct backref_edge *edges[],
 347                                             int *index)
 348 {
 349         struct backref_edge *edge;
 350         int idx = *index;
 351
 352         while (!list_empty(&node->upper)) {
 353                 edge = list_entry(node->upper.next,
 354                                   struct backref_edge, list[LOWER]);
 355                 edges[idx++] = edge;
 356                 node = edge->node[UPPER];
 357         }
 358         BUG_ON(node->detached);
 359         *index = idx;
 360         return node;
 361 }
 362
 363 /*
 364  * walk down backref nodes to find start of next reference path
 365  */
 366 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 367                                               int *index)
 368 {
 369         struct backref_edge *edge;
 370         struct backref_node *lower;
 371         int idx = *index;
 372
 373         while (idx > 0) {
 374                 edge = edges[idx - 1];
 375                 lower = edge->node[LOWER];
 376                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 377                         idx--;
 378                         continue;
 379                 }
 380                 edge = list_entry(edge->list[LOWER].next,
 381                                   struct backref_edge, list[LOWER]);
 382                 edges[idx - 1] = edge;
 383                 *index = idx;
 384                 return edge->node[UPPER];
 385         }
 386         *index = 0;
 387         return NULL;
 388 }
 389
 390 static void unlock_node_buffer(struct backref_node *node)
 391 {
 392         if (node->locked) {
 393                 btrfs_tree_unlock(node->eb);
 394                 node->locked = 0;
 395         }
 396 }
 397
 398 static void drop_node_buffer(struct backref_node *node)
 399 {
 400         if (node->eb) {
 401                 unlock_node_buffer(node);
 402                 free_extent_buffer(node->eb);
 403                 node->eb = NULL;
 404         }
 405 }
 406
 407 static void drop_backref_node(struct backref_cache *tree,
 408                               struct backref_node *node)
 409 {
 410         BUG_ON(!list_empty(&node->upper));
 411
 412         drop_node_buffer(node);
 413         list_del(&node->list);
 414         list_del(&node->lower);
 415         if (!RB_EMPTY_NODE(&node->rb_node))
 416                 rb_erase(&node->rb_node, &tree->rb_root);
 417         free_backref_node(tree, node);
 418 }
 419
 420 /*
 421  * remove a backref node from the backref cache
 422  */
 423 static void remove_backref_node(struct backref_cache *cache,
 424                                 struct backref_node *node)
 425 {
 426         struct backref_node *upper;
 427         struct backref_edge *edge;
 428
 429         if (!node)
 430                 return;
 431
 432         BUG_ON(!node->lowest && !node->detached);
 433         while (!list_empty(&node->upper)) {
 434                 edge = list_entry(node->upper.next, struct backref_edge,
 435                                   list[LOWER]);
 436                 upper = edge->node[UPPER];
 437                 list_del(&edge->list[LOWER]);
 438                 list_del(&edge->list[UPPER]);
 439                 free_backref_edge(cache, edge);
 440
 441                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 442                         BUG_ON(!list_empty(&node->upper));
 443                         drop_backref_node(cache, node);
 444                         node = upper;
 445                         node->lowest = 1;
 446                         continue;
 447                 }
 448                 /*
 449                  * add the node to leaf node list if no other
 450                  * child block cached.
 451                  */
 452                 if (list_empty(&upper->lower)) {
 453                         list_add_tail(&upper->lower, &cache->leaves);
 454                         upper->lowest = 1;
 455                 }
 456         }
 457
 458         drop_backref_node(cache, node);
 459 }
 460
 461 static void update_backref_node(struct backref_cache *cache,
 462                                 struct backref_node *node, u64 bytenr)
 463 {
 464         struct rb_node *rb_node;
 465         rb_erase(&node->rb_node, &cache->rb_root);
 466         node->bytenr = bytenr;
 467         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 468         if (rb_node)
 469                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 470 }
 471
 472 /*
 473  * update backref cache after a transaction commit
 474  */
 475 static int update_backref_cache(struct btrfs_trans_handle *trans,
 476                                 struct backref_cache *cache)
 477 {
 478         struct backref_node *node;
 479         int level = 0;
 480
 481         if (cache->last_trans == 0) {
 482                 cache->last_trans = trans->transid;
 483                 return 0;
 484         }
 485
 486         if (cache->last_trans == trans->transid)
 487                 return 0;
 488
 489         /*
 490          * detached nodes are used to avoid unnecessary backref
 491          * lookup. transaction commit changes the extent tree.
 492          * so the detached nodes are no longer useful.
 493          */
 494         while (!list_empty(&cache->detached)) {
 495                 node = list_entry(cache->detached.next,
 496                                   struct backref_node, list);
 497                 remove_backref_node(cache, node);
 498         }
 499
 500         while (!list_empty(&cache->changed)) {
 501                 node = list_entry(cache->changed.next,
 502                                   struct backref_node, list);
 503                 list_del_init(&node->list);
 504                 BUG_ON(node->pending);
 505                 update_backref_node(cache, node, node->new_bytenr);
 506         }
 507
 508         /*
 509          * some nodes can be left in the pending list if there were
 510          * errors during processing the pending nodes.
 511          */
 512         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 513                 list_for_each_entry(node, &cache->pending[level], list) {
 514                         BUG_ON(!node->pending);
 515                         if (node->bytenr == node->new_bytenr)
 516                                 continue;
 517                         update_backref_node(cache, node, node->new_bytenr);
 518                 }
 519         }
 520
 521         cache->last_trans = 0;
 522         return 1;
 523 }
 524
 525
 526 static int should_ignore_root(struct btrfs_root *root)
 527 {
 528         struct btrfs_root *reloc_root;
 529
 530         if (!root->ref_cows)
 531                 return 0;
 532
 533         reloc_root = root->reloc_root;
 534         if (!reloc_root)
 535                 return 0;
 536
 537         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 538             root->fs_info->running_transaction->transid - 1)
 539                 return 0;
 540         /*
 541          * if there is reloc tree and it was created in previous
 542          * transaction backref lookup can find the reloc tree,
 543          * so backref node for the fs tree root is useless for
 544          * relocation.
 545          */
 546         return 1;
 547 }
 548 /*
 549  * find reloc tree by address of tree root
 550  */
 551 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 552                                           u64 bytenr)
 553 {
 554         struct rb_node *rb_node;
 555         struct mapping_node *node;
 556         struct btrfs_root *root = NULL;
 557
 558         spin_lock(&rc->reloc_root_tree.lock);
 559         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 560         if (rb_node) {
 561                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 562                 root = (struct btrfs_root *)node->data;
 563         }
 564         spin_unlock(&rc->reloc_root_tree.lock);
 565         return root;
 566 }
 567
 568 static int is_cowonly_root(u64 root_objectid)
 569 {
 570         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 571             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 572             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 573             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 574             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 575             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
 576                 return 1;
 577         return 0;
 578 }
 579
 580 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 581                                         u64 root_objectid)
 582 {
 583         struct btrfs_key key;
 584
 585         key.objectid = root_objectid;
 586         key.type = BTRFS_ROOT_ITEM_KEY;
 587         if (is_cowonly_root(root_objectid))
 588                 key.offset = 0;
 589         else
 590                 key.offset = (u64)-1;
 591
 592         return btrfs_read_fs_root_no_name(fs_info, &key);
 593 }
 594
 595 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 596 static noinline_for_stack
 597 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 598                                   struct extent_buffer *leaf,
 599                                   struct btrfs_extent_ref_v0 *ref0)
 600 {
 601         struct btrfs_root *root;
 602         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 603         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 604
 605         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 606
 607         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 608         BUG_ON(IS_ERR(root));
 609
 610         if (root->ref_cows &&
 611             generation != btrfs_root_generation(&root->root_item))
 612                 return NULL;
 613
 614         return root;
 615 }
 616 #endif
 617
 618 static noinline_for_stack
 619 int find_inline_backref(struct extent_buffer *leaf, int slot,
 620                         unsigned long *ptr, unsigned long *end)
 621 {
 622         struct btrfs_extent_item *ei;
 623         struct btrfs_tree_block_info *bi;
 624         u32 item_size;
 625
 626         item_size = btrfs_item_size_nr(leaf, slot);
 627 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 628         if (item_size < sizeof(*ei)) {
 629                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 630                 return 1;
 631         }
 632 #endif
 633         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 634         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 635                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 636
 637         if (item_size <= sizeof(*ei) + sizeof(*bi)) {
 638                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 639                 return 1;
 640         }
 641
 642         bi = (struct btrfs_tree_block_info *)(ei + 1);
 643         *ptr = (unsigned long)(bi + 1);
 644         *end = (unsigned long)ei + item_size;
 645         return 0;
 646 }
 647
 648 /*
 649  * build backref tree for a given tree block. root of the backref tree
 650  * corresponds the tree block, leaves of the backref tree correspond
 651  * roots of b-trees that reference the tree block.
 652  *
 653  * the basic idea of this function is check backrefs of a given block
 654  * to find upper level blocks that refernece the block, and then check
 655  * bakcrefs of these upper level blocks recursively. the recursion stop
 656  * when tree root is reached or backrefs for the block is cached.
 657  *
 658  * NOTE: if we find backrefs for a block are cached, we know backrefs
 659  * for all upper level blocks that directly/indirectly reference the
 660  * block are also cached.
 661  */
 662 static noinline_for_stack
 663 struct backref_node *build_backref_tree(struct reloc_control *rc,
 664                                         struct btrfs_key *node_key,
 665                                         int level, u64 bytenr)
 666 {
 667         struct backref_cache *cache = &rc->backref_cache;
 668         struct btrfs_path *path1;
 669         struct btrfs_path *path2;
 670         struct extent_buffer *eb;
 671         struct btrfs_root *root;
 672         struct backref_node *cur;
 673         struct backref_node *upper;
 674         struct backref_node *lower;
 675         struct backref_node *node = NULL;
 676         struct backref_node *exist = NULL;
 677         struct backref_edge *edge;
 678         struct rb_node *rb_node;
 679         struct btrfs_key key;
 680         unsigned long end;
 681         unsigned long ptr;
 682         LIST_HEAD(list);
 683         LIST_HEAD(useless);
 684         int cowonly;
 685         int ret;
 686         int err = 0;
 687
 688         path1 = btrfs_alloc_path();
 689         path2 = btrfs_alloc_path();
 690         if (!path1 || !path2) {
 691                 err = -ENOMEM;
 692                 goto out;
 693         }
 694         path1->reada = 1;
 695         path2->reada = 2;
 696
 697         node = alloc_backref_node(cache);
 698         if (!node) {
 699                 err = -ENOMEM;
 700                 goto out;
 701         }
 702
 703         node->bytenr = bytenr;
 704         node->level = level;
 705         node->lowest = 1;
 706         cur = node;
 707 again:
 708         end = 0;
 709         ptr = 0;
 710         key.objectid = cur->bytenr;
 711         key.type = BTRFS_EXTENT_ITEM_KEY;
 712         key.offset = (u64)-1;
 713
 714         path1->search_commit_root = 1;
 715         path1->skip_locking = 1;
 716         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 717                                 0, 0);
 718         if (ret < 0) {
 719                 err = ret;
 720                 goto out;
 721         }
 722         BUG_ON(!ret || !path1->slots[0]);
 723
 724         path1->slots[0]--;
 725
 726         WARN_ON(cur->checked);
 727         if (!list_empty(&cur->upper)) {
 728                 /*
 729                  * the backref was added previously when processing
 730                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 731                  */
 732                 BUG_ON(!list_is_singular(&cur->upper));
 733                 edge = list_entry(cur->upper.next, struct backref_edge,
 734                                   list[LOWER]);
 735                 BUG_ON(!list_empty(&edge->list[UPPER]));
 736                 exist = edge->node[UPPER];
 737                 /*
 738                  * add the upper level block to pending list if we need
 739                  * check its backrefs
 740                  */
 741                 if (!exist->checked)
 742                         list_add_tail(&edge->list[UPPER], &list);
 743         } else {
 744                 exist = NULL;
 745         }
 746
 747         while (1) {
 748                 cond_resched();
 749                 eb = path1->nodes[0];
 750
 751                 if (ptr >= end) {
 752                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 753                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 754                                 if (ret < 0) {
 755                                         err = ret;
 756                                         goto out;
 757                                 }
 758                                 if (ret > 0)
 759                                         break;
 760                                 eb = path1->nodes[0];
 761                         }
 762
 763                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 764                         if (key.objectid != cur->bytenr) {
 765                                 WARN_ON(exist);
 766                                 break;
 767                         }
 768
 769                         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 770                                 ret = find_inline_backref(eb, path1->slots[0],
 771                                                           &ptr, &end);
 772                                 if (ret)
 773                                         goto next;
 774                         }
 775                 }
 776
 777                 if (ptr < end) {
 778                         /* update key for inline back ref */
 779                         struct btrfs_extent_inline_ref *iref;
 780                         iref = (struct btrfs_extent_inline_ref *)ptr;
 781                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 782                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 783                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 784                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 785                 }
 786
 787                 if (exist &&
 788                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 789                       exist->owner == key.offset) ||
 790                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 791                       exist->bytenr == key.offset))) {
 792                         exist = NULL;
 793                         goto next;
 794                 }
 795
 796 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 797                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 798                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 799                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 800                                 struct btrfs_extent_ref_v0 *ref0;
 801                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 802                                                 struct btrfs_extent_ref_v0);
 803                                 if (key.objectid == key.offset) {
 804                                         root = find_tree_root(rc, eb, ref0);
 805                                         if (root && !should_ignore_root(root))
 806                                                 cur->root = root;
 807                                         else
 808                                                 list_add(&cur->list, &useless);
 809                                         break;
 810                                 }
 811                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 812                                                                       ref0)))
 813                                         cur->cowonly = 1;
 814                         }
 815 #else
 816                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 817                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 818 #endif
 819                         if (key.objectid == key.offset) {
 820                                 /*
 821                                  * only root blocks of reloc trees use
 822                                  * backref of this type.
 823                                  */
 824                                 root = find_reloc_root(rc, cur->bytenr);
 825                                 BUG_ON(!root);
 826                                 cur->root = root;
 827                                 break;
 828                         }
 829
 830                         edge = alloc_backref_edge(cache);
 831                         if (!edge) {
 832                                 err = -ENOMEM;
 833                                 goto out;
 834                         }
 835                         rb_node = tree_search(&cache->rb_root, key.offset);
 836                         if (!rb_node) {
 837                                 upper = alloc_backref_node(cache);
 838                                 if (!upper) {
 839                                         free_backref_edge(cache, edge);
 840                                         err = -ENOMEM;
 841                                         goto out;
 842                                 }
 843                                 upper->bytenr = key.offset;
 844                                 upper->level = cur->level + 1;
 845                                 /*
 846                                  *  backrefs for the upper level block isn't
 847                                  *  cached, add the block to pending list
 848                                  */
 849                                 list_add_tail(&edge->list[UPPER], &list);
 850                         } else {
 851                                 upper = rb_entry(rb_node, struct backref_node,
 852                                                  rb_node);
 853                                 BUG_ON(!upper->checked);
 854                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 855                         }
 856                         list_add_tail(&edge->list[LOWER], &cur->upper);
 857                         edge->node[LOWER] = cur;
 858                         edge->node[UPPER] = upper;
 859
 860                         goto next;
 861                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 862                         goto next;
 863                 }
 864
 865                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 866                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 867                 if (IS_ERR(root)) {
 868                         err = PTR_ERR(root);
 869                         goto out;
 870                 }
 871
 872                 if (!root->ref_cows)
 873                         cur->cowonly = 1;
 874
 875                 if (btrfs_root_level(&root->root_item) == cur->level) {
 876                         /* tree root */
 877                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 878                                cur->bytenr);
 879                         if (should_ignore_root(root))
 880                                 list_add(&cur->list, &useless);
 881                         else
 882                                 cur->root = root;
 883                         break;
 884                 }
 885
 886                 level = cur->level + 1;
 887
 888                 /*
 889                  * searching the tree to find upper level blocks
 890                  * reference the block.
 891                  */
 892                 path2->search_commit_root = 1;
 893                 path2->skip_locking = 1;
 894                 path2->lowest_level = level;
 895                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 896                 path2->lowest_level = 0;
 897                 if (ret < 0) {
 898                         err = ret;
 899                         goto out;
 900                 }
 901                 if (ret > 0 && path2->slots[level] > 0)
 902                         path2->slots[level]--;
 903
 904                 eb = path2->nodes[level];
 905                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 906                         cur->bytenr);
 907
 908                 lower = cur;
 909                 for (; level < BTRFS_MAX_LEVEL; level++) {
 910                         if (!path2->nodes[level]) {
 911                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 912                                        lower->bytenr);
 913                                 if (should_ignore_root(root))
 914                                         list_add(&lower->list, &useless);
 915                                 else
 916                                         lower->root = root;
 917                                 break;
 918                         }
 919
 920                         edge = alloc_backref_edge(cache);
 921                         if (!edge) {
 922                                 err = -ENOMEM;
 923                                 goto out;
 924                         }
 925
 926                         eb = path2->nodes[level];
 927                         rb_node = tree_search(&cache->rb_root, eb->start);
 928                         if (!rb_node) {
 929                                 upper = alloc_backref_node(cache);
 930                                 if (!upper) {
 931                                         free_backref_edge(cache, edge);
 932                                         err = -ENOMEM;
 933                                         goto out;
 934                                 }
 935                                 upper->bytenr = eb->start;
 936                                 upper->owner = btrfs_header_owner(eb);
 937                                 upper->level = lower->level + 1;
 938                                 if (!root->ref_cows)
 939                                         upper->cowonly = 1;
 940
 941                                 /*
 942                                  * if we know the block isn't shared
 943                                  * we can void checking its backrefs.
 944                                  */
 945                                 if (btrfs_block_can_be_shared(root, eb))
 946                                         upper->checked = 0;
 947                                 else
 948                                         upper->checked = 1;
 949
 950                                 /*
 951                                  * add the block to pending list if we
 952                                  * need check its backrefs. only block
 953                                  * at 'cur->level + 1' is added to the
 954                                  * tail of pending list. this guarantees
 955                                  * we check backrefs from lower level
 956                                  * blocks to upper level blocks.
 957                                  */
 958                                 if (!upper->checked &&
 959                                     level == cur->level + 1) {
 960                                         list_add_tail(&edge->list[UPPER],
 961                                                       &list);
 962                                 } else
 963                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 964                         } else {
 965                                 upper = rb_entry(rb_node, struct backref_node,
 966                                                  rb_node);
 967                                 BUG_ON(!upper->checked);
 968                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 969                                 if (!upper->owner)
 970                                         upper->owner = btrfs_header_owner(eb);
 971                         }
 972                         list_add_tail(&edge->list[LOWER], &lower->upper);
 973                         edge->node[LOWER] = lower;
 974                         edge->node[UPPER] = upper;
 975
 976                         if (rb_node)
 977                                 break;
 978                         lower = upper;
 979                         upper = NULL;
 980                 }
 981                 btrfs_release_path(path2);
 982 next:
 983                 if (ptr < end) {
 984                         ptr += btrfs_extent_inline_ref_size(key.type);
 985                         if (ptr >= end) {
 986                                 WARN_ON(ptr > end);
 987                                 ptr = 0;
 988                                 end = 0;
 989                         }
 990                 }
 991                 if (ptr >= end)
 992                         path1->slots[0]++;
 993         }
 994         btrfs_release_path(path1);
 995
 996         cur->checked = 1;
 997         WARN_ON(exist);
 998
 999         /* the pending list isn't empty, take the first block to process */
1000         if (!list_empty(&list)) {
1001                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1002                 list_del_init(&edge->list[UPPER]);
1003                 cur = edge->node[UPPER];
1004                 goto again;
1005         }
1006
1007         /*
1008          * everything goes well, connect backref nodes and insert backref nodes
1009          * into the cache.
1010          */
1011         BUG_ON(!node->checked);
1012         cowonly = node->cowonly;
1013         if (!cowonly) {
1014                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1015                                       &node->rb_node);
1016                 if (rb_node)
1017                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1018                 list_add_tail(&node->lower, &cache->leaves);
1019         }
1020
1021         list_for_each_entry(edge, &node->upper, list[LOWER])
1022                 list_add_tail(&edge->list[UPPER], &list);
1023
1024         while (!list_empty(&list)) {
1025                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1026                 list_del_init(&edge->list[UPPER]);
1027                 upper = edge->node[UPPER];
1028                 if (upper->detached) {
1029                         list_del(&edge->list[LOWER]);
1030                         lower = edge->node[LOWER];
1031                         free_backref_edge(cache, edge);
1032                         if (list_empty(&lower->upper))
1033                                 list_add(&lower->list, &useless);
1034                         continue;
1035                 }
1036
1037                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1038                         if (upper->lowest) {
1039                                 list_del_init(&upper->lower);
1040                                 upper->lowest = 0;
1041                         }
1042
1043                         list_add_tail(&edge->list[UPPER], &upper->lower);
1044                         continue;
1045                 }
1046
1047                 BUG_ON(!upper->checked);
1048                 BUG_ON(cowonly != upper->cowonly);
1049                 if (!cowonly) {
1050                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1051                                               &upper->rb_node);
1052                         if (rb_node)
1053                                 backref_tree_panic(rb_node, -EEXIST,
1054                                                    upper->bytenr);
1055                 }
1056
1057                 list_add_tail(&edge->list[UPPER], &upper->lower);
1058
1059                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1060                         list_add_tail(&edge->list[UPPER], &list);
1061         }
1062         /*
1063          * process useless backref nodes. backref nodes for tree leaves
1064          * are deleted from the cache. backref nodes for upper level
1065          * tree blocks are left in the cache to avoid unnecessary backref
1066          * lookup.
1067          */
1068         while (!list_empty(&useless)) {
1069                 upper = list_entry(useless.next, struct backref_node, list);
1070                 list_del_init(&upper->list);
1071                 BUG_ON(!list_empty(&upper->upper));
1072                 if (upper == node)
1073                         node = NULL;
1074                 if (upper->lowest) {
1075                         list_del_init(&upper->lower);
1076                         upper->lowest = 0;
1077                 }
1078                 while (!list_empty(&upper->lower)) {
1079                         edge = list_entry(upper->lower.next,
1080                                           struct backref_edge, list[UPPER]);
1081                         list_del(&edge->list[UPPER]);
1082                         list_del(&edge->list[LOWER]);
1083                         lower = edge->node[LOWER];
1084                         free_backref_edge(cache, edge);
1085
1086                         if (list_empty(&lower->upper))
1087                                 list_add(&lower->list, &useless);
1088                 }
1089                 __mark_block_processed(rc, upper);
1090                 if (upper->level > 0) {
1091                         list_add(&upper->list, &cache->detached);
1092                         upper->detached = 1;
1093                 } else {
1094                         rb_erase(&upper->rb_node, &cache->rb_root);
1095                         free_backref_node(cache, upper);
1096                 }
1097         }
1098 out:
1099         btrfs_free_path(path1);
1100         btrfs_free_path(path2);
1101         if (err) {
1102                 while (!list_empty(&useless)) {
1103                         lower = list_entry(useless.next,
1104                                            struct backref_node, upper);
1105                         list_del_init(&lower->upper);
1106                 }
1107                 upper = node;
1108                 INIT_LIST_HEAD(&list);
1109                 while (upper) {
1110                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1111                                 list_splice_tail(&upper->upper, &list);
1112                                 free_backref_node(cache, upper);
1113                         }
1114
1115                         if (list_empty(&list))
1116                                 break;
1117
1118                         edge = list_entry(list.next, struct backref_edge,
1119                                           list[LOWER]);
1120                         list_del(&edge->list[LOWER]);
1121                         upper = edge->node[UPPER];
1122                         free_backref_edge(cache, edge);
1123                 }
1124                 return ERR_PTR(err);
1125         }
1126         BUG_ON(node && node->detached);
1127         return node;
1128 }
1129
1130 /*
1131  * helper to add backref node for the newly created snapshot.
1132  * the backref node is created by cloning backref node that
1133  * corresponds to root of source tree
1134  */
1135 static int clone_backref_node(struct btrfs_trans_handle *trans,
1136                               struct reloc_control *rc,
1137                               struct btrfs_root *src,
1138                               struct btrfs_root *dest)
1139 {
1140         struct btrfs_root *reloc_root = src->reloc_root;
1141         struct backref_cache *cache = &rc->backref_cache;
1142         struct backref_node *node = NULL;
1143         struct backref_node *new_node;
1144         struct backref_edge *edge;
1145         struct backref_edge *new_edge;
1146         struct rb_node *rb_node;
1147
1148         if (cache->last_trans > 0)
1149                 update_backref_cache(trans, cache);
1150
1151         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1152         if (rb_node) {
1153                 node = rb_entry(rb_node, struct backref_node, rb_node);
1154                 if (node->detached)
1155                         node = NULL;
1156                 else
1157                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1158         }
1159
1160         if (!node) {
1161                 rb_node = tree_search(&cache->rb_root,
1162                                       reloc_root->commit_root->start);
1163                 if (rb_node) {
1164                         node = rb_entry(rb_node, struct backref_node,
1165                                         rb_node);
1166                         BUG_ON(node->detached);
1167                 }
1168         }
1169
1170         if (!node)
1171                 return 0;
1172
1173         new_node = alloc_backref_node(cache);
1174         if (!new_node)
1175                 return -ENOMEM;
1176
1177         new_node->bytenr = dest->node->start;
1178         new_node->level = node->level;
1179         new_node->lowest = node->lowest;
1180         new_node->checked = 1;
1181         new_node->root = dest;
1182
1183         if (!node->lowest) {
1184                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1185                         new_edge = alloc_backref_edge(cache);
1186                         if (!new_edge)
1187                                 goto fail;
1188
1189                         new_edge->node[UPPER] = new_node;
1190                         new_edge->node[LOWER] = edge->node[LOWER];
1191                         list_add_tail(&new_edge->list[UPPER],
1192                                       &new_node->lower);
1193                 }
1194         } else {
1195                 list_add_tail(&new_node->lower, &cache->leaves);
1196         }
1197
1198         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1199                               &new_node->rb_node);
1200         if (rb_node)
1201                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1202
1203         if (!new_node->lowest) {
1204                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1205                         list_add_tail(&new_edge->list[LOWER],
1206                                       &new_edge->node[LOWER]->upper);
1207                 }
1208         }
1209         return 0;
1210 fail:
1211         while (!list_empty(&new_node->lower)) {
1212                 new_edge = list_entry(new_node->lower.next,
1213                                       struct backref_edge, list[UPPER]);
1214                 list_del(&new_edge->list[UPPER]);
1215                 free_backref_edge(cache, new_edge);
1216         }
1217         free_backref_node(cache, new_node);
1218         return -ENOMEM;
1219 }
1220
1221 /*
1222  * helper to add 'address of tree root -> reloc tree' mapping
1223  */
1224 static int __must_check __add_reloc_root(struct btrfs_root *root)
1225 {
1226         struct rb_node *rb_node;
1227         struct mapping_node *node;
1228         struct reloc_control *rc = root->fs_info->reloc_ctl;
1229
1230         node = kmalloc(sizeof(*node), GFP_NOFS);
1231         if (!node)
1232                 return -ENOMEM;
1233
1234         node->bytenr = root->node->start;
1235         node->data = root;
1236
1237         spin_lock(&rc->reloc_root_tree.lock);
1238         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1239                               node->bytenr, &node->rb_node);
1240         spin_unlock(&rc->reloc_root_tree.lock);
1241         if (rb_node) {
1242                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1243                             "for start=%llu while inserting into relocation "
1244                             "tree\n", node->bytenr);
1245                 kfree(node);
1246                 return -EEXIST;
1247         }
1248
1249         list_add_tail(&root->root_list, &rc->reloc_roots);
1250         return 0;
1251 }
1252
1253 /*
1254  * helper to update/delete the 'address of tree root -> reloc tree'
1255  * mapping
1256  */
1257 static int __update_reloc_root(struct btrfs_root *root, int del)
1258 {
1259         struct rb_node *rb_node;
1260         struct mapping_node *node = NULL;
1261         struct reloc_control *rc = root->fs_info->reloc_ctl;
1262
1263         spin_lock(&rc->reloc_root_tree.lock);
1264         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1265                               root->commit_root->start);
1266         if (rb_node) {
1267                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1268                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1269         }
1270         spin_unlock(&rc->reloc_root_tree.lock);
1271
1272         if (!node)
1273                 return 0;
1274         BUG_ON((struct btrfs_root *)node->data != root);
1275
1276         if (!del) {
1277                 spin_lock(&rc->reloc_root_tree.lock);
1278                 node->bytenr = root->node->start;
1279                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1280                                       node->bytenr, &node->rb_node);
1281                 spin_unlock(&rc->reloc_root_tree.lock);
1282                 if (rb_node)
1283                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1284         } else {
1285                 spin_lock(&root->fs_info->trans_lock);
1286                 list_del_init(&root->root_list);
1287                 spin_unlock(&root->fs_info->trans_lock);
1288                 kfree(node);
1289         }
1290         return 0;
1291 }
1292
1293 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1294                                         struct btrfs_root *root, u64 objectid)
1295 {
1296         struct btrfs_root *reloc_root;
1297         struct extent_buffer *eb;
1298         struct btrfs_root_item *root_item;
1299         struct btrfs_key root_key;
1300         int ret;
1301
1302         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1303         BUG_ON(!root_item);
1304
1305         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1306         root_key.type = BTRFS_ROOT_ITEM_KEY;
1307         root_key.offset = objectid;
1308
1309         if (root->root_key.objectid == objectid) {
1310                 /* called by btrfs_init_reloc_root */
1311                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1312                                       BTRFS_TREE_RELOC_OBJECTID);
1313                 BUG_ON(ret);
1314
1315                 btrfs_set_root_last_snapshot(&root->root_item,
1316                                              trans->transid - 1);
1317         } else {
1318                 /*
1319                  * called by btrfs_reloc_post_snapshot_hook.
1320                  * the source tree is a reloc tree, all tree blocks
1321                  * modified after it was created have RELOC flag
1322                  * set in their headers. so it's OK to not update
1323                  * the 'last_snapshot'.
1324                  */
1325                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1326                                       BTRFS_TREE_RELOC_OBJECTID);
1327                 BUG_ON(ret);
1328         }
1329
1330         memcpy(root_item, &root->root_item, sizeof(*root_item));
1331         btrfs_set_root_bytenr(root_item, eb->start);
1332         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1333         btrfs_set_root_generation(root_item, trans->transid);
1334
1335         if (root->root_key.objectid == objectid) {
1336                 btrfs_set_root_refs(root_item, 0);
1337                 memset(&root_item->drop_progress, 0,
1338                        sizeof(struct btrfs_disk_key));
1339                 root_item->drop_level = 0;
1340         }
1341
1342         btrfs_tree_unlock(eb);
1343         free_extent_buffer(eb);
1344
1345         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1346                                 &root_key, root_item);
1347         BUG_ON(ret);
1348         kfree(root_item);
1349
1350         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
1351                                                  &root_key);
1352         BUG_ON(IS_ERR(reloc_root));
1353         reloc_root->last_trans = trans->transid;
1354         return reloc_root;
1355 }
1356
1357 /*
1358  * create reloc tree for a given fs tree. reloc tree is just a
1359  * snapshot of the fs tree with special root objectid.
1360  */
1361 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1362                           struct btrfs_root *root)
1363 {
1364         struct btrfs_root *reloc_root;
1365         struct reloc_control *rc = root->fs_info->reloc_ctl;
1366         int clear_rsv = 0;
1367         int ret;
1368
1369         if (root->reloc_root) {
1370                 reloc_root = root->reloc_root;
1371                 reloc_root->last_trans = trans->transid;
1372                 return 0;
1373         }
1374
1375         if (!rc || !rc->create_reloc_tree ||
1376             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1377                 return 0;
1378
1379         if (!trans->block_rsv) {
1380                 trans->block_rsv = rc->block_rsv;
1381                 clear_rsv = 1;
1382         }
1383         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1384         if (clear_rsv)
1385                 trans->block_rsv = NULL;
1386
1387         ret = __add_reloc_root(reloc_root);
1388         BUG_ON(ret < 0);
1389         root->reloc_root = reloc_root;
1390         return 0;
1391 }
1392
1393 /*
1394  * update root item of reloc tree
1395  */
1396 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1397                             struct btrfs_root *root)
1398 {
1399         struct btrfs_root *reloc_root;
1400         struct btrfs_root_item *root_item;
1401         int del = 0;
1402         int ret;
1403
1404         if (!root->reloc_root)
1405                 goto out;
1406
1407         reloc_root = root->reloc_root;
1408         root_item = &reloc_root->root_item;
1409
1410         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1411             btrfs_root_refs(root_item) == 0) {
1412                 root->reloc_root = NULL;
1413                 del = 1;
1414         }
1415
1416         __update_reloc_root(reloc_root, del);
1417
1418         if (reloc_root->commit_root != reloc_root->node) {
1419                 btrfs_set_root_node(root_item, reloc_root->node);
1420                 free_extent_buffer(reloc_root->commit_root);
1421                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1422         }
1423
1424         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1425                                 &reloc_root->root_key, root_item);
1426         BUG_ON(ret);
1427
1428 out:
1429         return 0;
1430 }
1431
1432 /*
1433  * helper to find first cached inode with inode number >= objectid
1434  * in a subvolume
1435  */
1436 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1437 {
1438         struct rb_node *node;
1439         struct rb_node *prev;
1440         struct btrfs_inode *entry;
1441         struct inode *inode;
1442
1443         spin_lock(&root->inode_lock);
1444 again:
1445         node = root->inode_tree.rb_node;
1446         prev = NULL;
1447         while (node) {
1448                 prev = node;
1449                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1450
1451                 if (objectid < btrfs_ino(&entry->vfs_inode))
1452                         node = node->rb_left;
1453                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1454                         node = node->rb_right;
1455                 else
1456                         break;
1457         }
1458         if (!node) {
1459                 while (prev) {
1460                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1461                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1462                                 node = prev;
1463                                 break;
1464                         }
1465                         prev = rb_next(prev);
1466                 }
1467         }
1468         while (node) {
1469                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1470                 inode = igrab(&entry->vfs_inode);
1471                 if (inode) {
1472                         spin_unlock(&root->inode_lock);
1473                         return inode;
1474                 }
1475
1476                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1477                 if (cond_resched_lock(&root->inode_lock))
1478                         goto again;
1479
1480                 node = rb_next(node);
1481         }
1482         spin_unlock(&root->inode_lock);
1483         return NULL;
1484 }
1485
1486 static int in_block_group(u64 bytenr,
1487                           struct btrfs_block_group_cache *block_group)
1488 {
1489         if (bytenr >= block_group->key.objectid &&
1490             bytenr < block_group->key.objectid + block_group->key.offset)
1491                 return 1;
1492         return 0;
1493 }
1494
1495 /*
1496  * get new location of data
1497  */
1498 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1499                             u64 bytenr, u64 num_bytes)
1500 {
1501         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1502         struct btrfs_path *path;
1503         struct btrfs_file_extent_item *fi;
1504         struct extent_buffer *leaf;
1505         int ret;
1506
1507         path = btrfs_alloc_path();
1508         if (!path)
1509                 return -ENOMEM;
1510
1511         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1512         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1513                                        bytenr, 0);
1514         if (ret < 0)
1515                 goto out;
1516         if (ret > 0) {
1517                 ret = -ENOENT;
1518                 goto out;
1519         }
1520
1521         leaf = path->nodes[0];
1522         fi = btrfs_item_ptr(leaf, path->slots[0],
1523                             struct btrfs_file_extent_item);
1524
1525         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1526                btrfs_file_extent_compression(leaf, fi) ||
1527                btrfs_file_extent_encryption(leaf, fi) ||
1528                btrfs_file_extent_other_encoding(leaf, fi));
1529
1530         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1531                 ret = 1;
1532                 goto out;
1533         }
1534
1535         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1536         ret = 0;
1537 out:
1538         btrfs_free_path(path);
1539         return ret;
1540 }
1541
1542 /*
1543  * update file extent items in the tree leaf to point to
1544  * the new locations.
1545  */
1546 static noinline_for_stack
1547 int replace_file_extents(struct btrfs_trans_handle *trans,
1548                          struct reloc_control *rc,
1549                          struct btrfs_root *root,
1550                          struct extent_buffer *leaf)
1551 {
1552         struct btrfs_key key;
1553         struct btrfs_file_extent_item *fi;
1554         struct inode *inode = NULL;
1555         u64 parent;
1556         u64 bytenr;
1557         u64 new_bytenr = 0;
1558         u64 num_bytes;
1559         u64 end;
1560         u32 nritems;
1561         u32 i;
1562         int ret;
1563         int first = 1;
1564         int dirty = 0;
1565
1566         if (rc->stage != UPDATE_DATA_PTRS)
1567                 return 0;
1568
1569         /* reloc trees always use full backref */
1570         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1571                 parent = leaf->start;
1572         else
1573                 parent = 0;
1574
1575         nritems = btrfs_header_nritems(leaf);
1576         for (i = 0; i < nritems; i++) {
1577                 cond_resched();
1578                 btrfs_item_key_to_cpu(leaf, &key, i);
1579                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1580                         continue;
1581                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1582                 if (btrfs_file_extent_type(leaf, fi) ==
1583                     BTRFS_FILE_EXTENT_INLINE)
1584                         continue;
1585                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1586                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1587                 if (bytenr == 0)
1588                         continue;
1589                 if (!in_block_group(bytenr, rc->block_group))
1590                         continue;
1591
1592                 /*
1593                  * if we are modifying block in fs tree, wait for readpage
1594                  * to complete and drop the extent cache
1595                  */
1596                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1597                         if (first) {
1598                                 inode = find_next_inode(root, key.objectid);
1599                                 first = 0;
1600                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1601                                 btrfs_add_delayed_iput(inode);
1602                                 inode = find_next_inode(root, key.objectid);
1603                         }
1604                         if (inode && btrfs_ino(inode) == key.objectid) {
1605                                 end = key.offset +
1606                                       btrfs_file_extent_num_bytes(leaf, fi);
1607                                 WARN_ON(!IS_ALIGNED(key.offset,
1608                                                     root->sectorsize));
1609                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1610                                 end--;
1611                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1612                                                       key.offset, end);
1613                                 if (!ret)
1614                                         continue;
1615
1616                                 btrfs_drop_extent_cache(inode, key.offset, end,
1617                                                         1);
1618                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1619                                               key.offset, end);
1620                         }
1621                 }
1622
1623                 ret = get_new_location(rc->data_inode, &new_bytenr,
1624                                        bytenr, num_bytes);
1625                 if (ret > 0) {
1626                         WARN_ON(1);
1627                         continue;
1628                 }
1629                 BUG_ON(ret < 0);
1630
1631                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1632                 dirty = 1;
1633
1634                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1635                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1636                                            num_bytes, parent,
1637                                            btrfs_header_owner(leaf),
1638                                            key.objectid, key.offset, 1);
1639                 BUG_ON(ret);
1640
1641                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1642                                         parent, btrfs_header_owner(leaf),
1643                                         key.objectid, key.offset, 1);
1644                 BUG_ON(ret);
1645         }
1646         if (dirty)
1647                 btrfs_mark_buffer_dirty(leaf);
1648         if (inode)
1649                 btrfs_add_delayed_iput(inode);
1650         return 0;
1651 }
1652
1653 static noinline_for_stack
1654 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1655                      struct btrfs_path *path, int level)
1656 {
1657         struct btrfs_disk_key key1;
1658         struct btrfs_disk_key key2;
1659         btrfs_node_key(eb, &key1, slot);
1660         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1661         return memcmp(&key1, &key2, sizeof(key1));
1662 }
1663
1664 /*
1665  * try to replace tree blocks in fs tree with the new blocks
1666  * in reloc tree. tree blocks haven't been modified since the
1667  * reloc tree was create can be replaced.
1668  *
1669  * if a block was replaced, level of the block + 1 is returned.
1670  * if no block got replaced, 0 is returned. if there are other
1671  * errors, a negative error number is returned.
1672  */
1673 static noinline_for_stack
1674 int replace_path(struct btrfs_trans_handle *trans,
1675                  struct btrfs_root *dest, struct btrfs_root *src,
1676                  struct btrfs_path *path, struct btrfs_key *next_key,
1677                  int lowest_level, int max_level)
1678 {
1679         struct extent_buffer *eb;
1680         struct extent_buffer *parent;
1681         struct btrfs_key key;
1682         u64 old_bytenr;
1683         u64 new_bytenr;
1684         u64 old_ptr_gen;
1685         u64 new_ptr_gen;
1686         u64 last_snapshot;
1687         u32 blocksize;
1688         int cow = 0;
1689         int level;
1690         int ret;
1691         int slot;
1692
1693         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1694         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1695
1696         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1697 again:
1698         slot = path->slots[lowest_level];
1699         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1700
1701         eb = btrfs_lock_root_node(dest);
1702         btrfs_set_lock_blocking(eb);
1703         level = btrfs_header_level(eb);
1704
1705         if (level < lowest_level) {
1706                 btrfs_tree_unlock(eb);
1707                 free_extent_buffer(eb);
1708                 return 0;
1709         }
1710
1711         if (cow) {
1712                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1713                 BUG_ON(ret);
1714         }
1715         btrfs_set_lock_blocking(eb);
1716
1717         if (next_key) {
1718                 next_key->objectid = (u64)-1;
1719                 next_key->type = (u8)-1;
1720                 next_key->offset = (u64)-1;
1721         }
1722
1723         parent = eb;
1724         while (1) {
1725                 level = btrfs_header_level(parent);
1726                 BUG_ON(level < lowest_level);
1727
1728                 ret = btrfs_bin_search(parent, &key, level, &slot);
1729                 if (ret && slot > 0)
1730                         slot--;
1731
1732                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1733                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1734
1735                 old_bytenr = btrfs_node_blockptr(parent, slot);
1736                 blocksize = btrfs_level_size(dest, level - 1);
1737                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1738
1739                 if (level <= max_level) {
1740                         eb = path->nodes[level];
1741                         new_bytenr = btrfs_node_blockptr(eb,
1742                                                         path->slots[level]);
1743                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1744                                                         path->slots[level]);
1745                 } else {
1746                         new_bytenr = 0;
1747                         new_ptr_gen = 0;
1748                 }
1749
1750                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1751                         WARN_ON(1);
1752                         ret = level;
1753                         break;
1754                 }
1755
1756                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1757                     memcmp_node_keys(parent, slot, path, level)) {
1758                         if (level <= lowest_level) {
1759                                 ret = 0;
1760                                 break;
1761                         }
1762
1763                         eb = read_tree_block(dest, old_bytenr, blocksize,
1764                                              old_ptr_gen);
1765                         BUG_ON(!eb);
1766                         btrfs_tree_lock(eb);
1767                         if (cow) {
1768                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1769                                                       slot, &eb);
1770                                 BUG_ON(ret);
1771                         }
1772                         btrfs_set_lock_blocking(eb);
1773
1774                         btrfs_tree_unlock(parent);
1775                         free_extent_buffer(parent);
1776
1777                         parent = eb;
1778                         continue;
1779                 }
1780
1781                 if (!cow) {
1782                         btrfs_tree_unlock(parent);
1783                         free_extent_buffer(parent);
1784                         cow = 1;
1785                         goto again;
1786                 }
1787
1788                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1789                                       path->slots[level]);
1790                 btrfs_release_path(path);
1791
1792                 path->lowest_level = level;
1793                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1794                 path->lowest_level = 0;
1795                 BUG_ON(ret);
1796
1797                 /*
1798                  * swap blocks in fs tree and reloc tree.
1799                  */
1800                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1801                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1802                 btrfs_mark_buffer_dirty(parent);
1803
1804                 btrfs_set_node_blockptr(path->nodes[level],
1805                                         path->slots[level], old_bytenr);
1806                 btrfs_set_node_ptr_generation(path->nodes[level],
1807                                               path->slots[level], old_ptr_gen);
1808                 btrfs_mark_buffer_dirty(path->nodes[level]);
1809
1810                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1811                                         path->nodes[level]->start,
1812                                         src->root_key.objectid, level - 1, 0,
1813                                         1);
1814                 BUG_ON(ret);
1815                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1816                                         0, dest->root_key.objectid, level - 1,
1817                                         0, 1);
1818                 BUG_ON(ret);
1819
1820                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1821                                         path->nodes[level]->start,
1822                                         src->root_key.objectid, level - 1, 0,
1823                                         1);
1824                 BUG_ON(ret);
1825
1826                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1827                                         0, dest->root_key.objectid, level - 1,
1828                                         0, 1);
1829                 BUG_ON(ret);
1830
1831                 btrfs_unlock_up_safe(path, 0);
1832
1833                 ret = level;
1834                 break;
1835         }
1836         btrfs_tree_unlock(parent);
1837         free_extent_buffer(parent);
1838         return ret;
1839 }
1840
1841 /*
1842  * helper to find next relocated block in reloc tree
1843  */
1844 static noinline_for_stack
1845 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1846                        int *level)
1847 {
1848         struct extent_buffer *eb;
1849         int i;
1850         u64 last_snapshot;
1851         u32 nritems;
1852
1853         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1854
1855         for (i = 0; i < *level; i++) {
1856                 free_extent_buffer(path->nodes[i]);
1857                 path->nodes[i] = NULL;
1858         }
1859
1860         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1861                 eb = path->nodes[i];
1862                 nritems = btrfs_header_nritems(eb);
1863                 while (path->slots[i] + 1 < nritems) {
1864                         path->slots[i]++;
1865                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1866                             last_snapshot)
1867                                 continue;
1868
1869                         *level = i;
1870                         return 0;
1871                 }
1872                 free_extent_buffer(path->nodes[i]);
1873                 path->nodes[i] = NULL;
1874         }
1875         return 1;
1876 }
1877
1878 /*
1879  * walk down reloc tree to find relocated block of lowest level
1880  */
1881 static noinline_for_stack
1882 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1883                          int *level)
1884 {
1885         struct extent_buffer *eb = NULL;
1886         int i;
1887         u64 bytenr;
1888         u64 ptr_gen = 0;
1889         u64 last_snapshot;
1890         u32 blocksize;
1891         u32 nritems;
1892
1893         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1894
1895         for (i = *level; i > 0; i--) {
1896                 eb = path->nodes[i];
1897                 nritems = btrfs_header_nritems(eb);
1898                 while (path->slots[i] < nritems) {
1899                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1900                         if (ptr_gen > last_snapshot)
1901                                 break;
1902                         path->slots[i]++;
1903                 }
1904                 if (path->slots[i] >= nritems) {
1905                         if (i == *level)
1906                                 break;
1907                         *level = i + 1;
1908                         return 0;
1909                 }
1910                 if (i == 1) {
1911                         *level = i;
1912                         return 0;
1913                 }
1914
1915                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1916                 blocksize = btrfs_level_size(root, i - 1);
1917                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1918                 BUG_ON(btrfs_header_level(eb) != i - 1);
1919                 path->nodes[i - 1] = eb;
1920                 path->slots[i - 1] = 0;
1921         }
1922         return 1;
1923 }
1924
1925 /*
1926  * invalidate extent cache for file extents whose key in range of
1927  * [min_key, max_key)
1928  */
1929 static int invalidate_extent_cache(struct btrfs_root *root,
1930                                    struct btrfs_key *min_key,
1931                                    struct btrfs_key *max_key)
1932 {
1933         struct inode *inode = NULL;
1934         u64 objectid;
1935         u64 start, end;
1936         u64 ino;
1937
1938         objectid = min_key->objectid;
1939         while (1) {
1940                 cond_resched();
1941                 iput(inode);
1942
1943                 if (objectid > max_key->objectid)
1944                         break;
1945
1946                 inode = find_next_inode(root, objectid);
1947                 if (!inode)
1948                         break;
1949                 ino = btrfs_ino(inode);
1950
1951                 if (ino > max_key->objectid) {
1952                         iput(inode);
1953                         break;
1954                 }
1955
1956                 objectid = ino + 1;
1957                 if (!S_ISREG(inode->i_mode))
1958                         continue;
1959
1960                 if (unlikely(min_key->objectid == ino)) {
1961                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1962                                 continue;
1963                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1964                                 start = 0;
1965                         else {
1966                                 start = min_key->offset;
1967                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1968                         }
1969                 } else {
1970                         start = 0;
1971                 }
1972
1973                 if (unlikely(max_key->objectid == ino)) {
1974                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1975                                 continue;
1976                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1977                                 end = (u64)-1;
1978                         } else {
1979                                 if (max_key->offset == 0)
1980                                         continue;
1981                                 end = max_key->offset;
1982                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1983                                 end--;
1984                         }
1985                 } else {
1986                         end = (u64)-1;
1987                 }
1988
1989                 /* the lock_extent waits for readpage to complete */
1990                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
1991                 btrfs_drop_extent_cache(inode, start, end, 1);
1992                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
1993         }
1994         return 0;
1995 }
1996
1997 static int find_next_key(struct btrfs_path *path, int level,
1998                          struct btrfs_key *key)
1999
2000 {
2001         while (level < BTRFS_MAX_LEVEL) {
2002                 if (!path->nodes[level])
2003                         break;
2004                 if (path->slots[level] + 1 <
2005                     btrfs_header_nritems(path->nodes[level])) {
2006                         btrfs_node_key_to_cpu(path->nodes[level], key,
2007                                               path->slots[level] + 1);
2008                         return 0;
2009                 }
2010                 level++;
2011         }
2012         return 1;
2013 }
2014
2015 /*
2016  * merge the relocated tree blocks in reloc tree with corresponding
2017  * fs tree.
2018  */
2019 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2020                                                struct btrfs_root *root)
2021 {
2022         LIST_HEAD(inode_list);
2023         struct btrfs_key key;
2024         struct btrfs_key next_key;
2025         struct btrfs_trans_handle *trans;
2026         struct btrfs_root *reloc_root;
2027         struct btrfs_root_item *root_item;
2028         struct btrfs_path *path;
2029         struct extent_buffer *leaf;
2030         int level;
2031         int max_level;
2032         int replaced = 0;
2033         int ret;
2034         int err = 0;
2035         u32 min_reserved;
2036
2037         path = btrfs_alloc_path();
2038         if (!path)
2039                 return -ENOMEM;
2040         path->reada = 1;
2041
2042         reloc_root = root->reloc_root;
2043         root_item = &reloc_root->root_item;
2044
2045         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2046                 level = btrfs_root_level(root_item);
2047                 extent_buffer_get(reloc_root->node);
2048                 path->nodes[level] = reloc_root->node;
2049                 path->slots[level] = 0;
2050         } else {
2051                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2052
2053                 level = root_item->drop_level;
2054                 BUG_ON(level == 0);
2055                 path->lowest_level = level;
2056                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2057                 path->lowest_level = 0;
2058                 if (ret < 0) {
2059                         btrfs_free_path(path);
2060                         return ret;
2061                 }
2062
2063                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2064                                       path->slots[level]);
2065                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2066
2067                 btrfs_unlock_up_safe(path, 0);
2068         }
2069
2070         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2071         memset(&next_key, 0, sizeof(next_key));
2072
2073         while (1) {
2074                 trans = btrfs_start_transaction(root, 0);
2075                 BUG_ON(IS_ERR(trans));
2076                 trans->block_rsv = rc->block_rsv;
2077
2078                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2079                                              BTRFS_RESERVE_FLUSH_ALL);
2080                 if (ret) {
2081                         BUG_ON(ret != -EAGAIN);
2082                         ret = btrfs_commit_transaction(trans, root);
2083                         BUG_ON(ret);
2084                         continue;
2085                 }
2086
2087                 replaced = 0;
2088                 max_level = level;
2089
2090                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2091                 if (ret < 0) {
2092                         err = ret;
2093                         goto out;
2094                 }
2095                 if (ret > 0)
2096                         break;
2097
2098                 if (!find_next_key(path, level, &key) &&
2099                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2100                         ret = 0;
2101                 } else {
2102                         ret = replace_path(trans, root, reloc_root, path,
2103                                            &next_key, level, max_level);
2104                 }
2105                 if (ret < 0) {
2106                         err = ret;
2107                         goto out;
2108                 }
2109
2110                 if (ret > 0) {
2111                         level = ret;
2112                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2113                                               path->slots[level]);
2114                         replaced = 1;
2115                 }
2116
2117                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2118                 if (ret > 0)
2119                         break;
2120
2121                 BUG_ON(level == 0);
2122                 /*
2123                  * save the merging progress in the drop_progress.
2124                  * this is OK since root refs == 1 in this case.
2125                  */
2126                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2127                                path->slots[level]);
2128                 root_item->drop_level = level;
2129
2130                 btrfs_end_transaction_throttle(trans, root);
2131
2132                 btrfs_btree_balance_dirty(root);
2133
2134                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2135                         invalidate_extent_cache(root, &key, &next_key);
2136         }
2137
2138         /*
2139          * handle the case only one block in the fs tree need to be
2140          * relocated and the block is tree root.
2141          */
2142         leaf = btrfs_lock_root_node(root);
2143         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2144         btrfs_tree_unlock(leaf);
2145         free_extent_buffer(leaf);
2146         if (ret < 0)
2147                 err = ret;
2148 out:
2149         btrfs_free_path(path);
2150
2151         if (err == 0) {
2152                 memset(&root_item->drop_progress, 0,
2153                        sizeof(root_item->drop_progress));
2154                 root_item->drop_level = 0;
2155                 btrfs_set_root_refs(root_item, 0);
2156                 btrfs_update_reloc_root(trans, root);
2157         }
2158
2159         btrfs_end_transaction_throttle(trans, root);
2160
2161         btrfs_btree_balance_dirty(root);
2162
2163         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2164                 invalidate_extent_cache(root, &key, &next_key);
2165
2166         return err;
2167 }
2168
2169 static noinline_for_stack
2170 int prepare_to_merge(struct reloc_control *rc, int err)
2171 {
2172         struct btrfs_root *root = rc->extent_root;
2173         struct btrfs_root *reloc_root;
2174         struct btrfs_trans_handle *trans;
2175         LIST_HEAD(reloc_roots);
2176         u64 num_bytes = 0;
2177         int ret;
2178
2179         mutex_lock(&root->fs_info->reloc_mutex);
2180         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2181         rc->merging_rsv_size += rc->nodes_relocated * 2;
2182         mutex_unlock(&root->fs_info->reloc_mutex);
2183
2184 again:
2185         if (!err) {
2186                 num_bytes = rc->merging_rsv_size;
2187                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2188                                           BTRFS_RESERVE_FLUSH_ALL);
2189                 if (ret)
2190                         err = ret;
2191         }
2192
2193         trans = btrfs_join_transaction(rc->extent_root);
2194         if (IS_ERR(trans)) {
2195                 if (!err)
2196                         btrfs_block_rsv_release(rc->extent_root,
2197                                                 rc->block_rsv, num_bytes);
2198                 return PTR_ERR(trans);
2199         }
2200
2201         if (!err) {
2202                 if (num_bytes != rc->merging_rsv_size) {
2203                         btrfs_end_transaction(trans, rc->extent_root);
2204                         btrfs_block_rsv_release(rc->extent_root,
2205                                                 rc->block_rsv, num_bytes);
2206                         goto again;
2207                 }
2208         }
2209
2210         rc->merge_reloc_tree = 1;
2211
2212         while (!list_empty(&rc->reloc_roots)) {
2213                 reloc_root = list_entry(rc->reloc_roots.next,
2214                                         struct btrfs_root, root_list);
2215                 list_del_init(&reloc_root->root_list);
2216
2217                 root = read_fs_root(reloc_root->fs_info,
2218                                     reloc_root->root_key.offset);
2219                 BUG_ON(IS_ERR(root));
2220                 BUG_ON(root->reloc_root != reloc_root);
2221
2222                 /*
2223                  * set reference count to 1, so btrfs_recover_relocation
2224                  * knows it should resumes merging
2225                  */
2226                 if (!err)
2227                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2228                 btrfs_update_reloc_root(trans, root);
2229
2230                 list_add(&reloc_root->root_list, &reloc_roots);
2231         }
2232
2233         list_splice(&reloc_roots, &rc->reloc_roots);
2234
2235         if (!err)
2236                 btrfs_commit_transaction(trans, rc->extent_root);
2237         else
2238                 btrfs_end_transaction(trans, rc->extent_root);
2239         return err;
2240 }
2241
2242 static noinline_for_stack
2243 void free_reloc_roots(struct list_head *list)
2244 {
2245         struct btrfs_root *reloc_root;
2246
2247         while (!list_empty(list)) {
2248                 reloc_root = list_entry(list->next, struct btrfs_root,
2249                                         root_list);
2250                 __update_reloc_root(reloc_root, 1);
2251                 free_extent_buffer(reloc_root->node);
2252                 free_extent_buffer(reloc_root->commit_root);
2253                 kfree(reloc_root);
2254         }
2255 }
2256
2257 static noinline_for_stack
2258 int merge_reloc_roots(struct reloc_control *rc)
2259 {
2260         struct btrfs_root *root;
2261         struct btrfs_root *reloc_root;
2262         LIST_HEAD(reloc_roots);
2263         int found = 0;
2264         int ret = 0;
2265 again:
2266         root = rc->extent_root;
2267
2268         /*
2269          * this serializes us with btrfs_record_root_in_transaction,
2270          * we have to make sure nobody is in the middle of
2271          * adding their roots to the list while we are
2272          * doing this splice
2273          */
2274         mutex_lock(&root->fs_info->reloc_mutex);
2275         list_splice_init(&rc->reloc_roots, &reloc_roots);
2276         mutex_unlock(&root->fs_info->reloc_mutex);
2277
2278         while (!list_empty(&reloc_roots)) {
2279                 found = 1;
2280                 reloc_root = list_entry(reloc_roots.next,
2281                                         struct btrfs_root, root_list);
2282
2283                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2284                         root = read_fs_root(reloc_root->fs_info,
2285                                             reloc_root->root_key.offset);
2286                         BUG_ON(IS_ERR(root));
2287                         BUG_ON(root->reloc_root != reloc_root);
2288
2289                         ret = merge_reloc_root(rc, root);
2290                         if (ret)
2291                                 goto out;
2292                 } else {
2293                         list_del_init(&reloc_root->root_list);
2294                 }
2295                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2296                 if (ret < 0) {
2297                         if (list_empty(&reloc_root->root_list))
2298                                 list_add_tail(&reloc_root->root_list,
2299                                               &reloc_roots);
2300                         goto out;
2301                 }
2302         }
2303
2304         if (found) {
2305                 found = 0;
2306                 goto again;
2307         }
2308 out:
2309         if (ret) {
2310                 btrfs_std_error(root->fs_info, ret);
2311                 if (!list_empty(&reloc_roots))
2312                         free_reloc_roots(&reloc_roots);
2313         }
2314
2315         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2316         return ret;
2317 }
2318
2319 static void free_block_list(struct rb_root *blocks)
2320 {
2321         struct tree_block *block;
2322         struct rb_node *rb_node;
2323         while ((rb_node = rb_first(blocks))) {
2324                 block = rb_entry(rb_node, struct tree_block, rb_node);
2325                 rb_erase(rb_node, blocks);
2326                 kfree(block);
2327         }
2328 }
2329
2330 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2331                                       struct btrfs_root *reloc_root)
2332 {
2333         struct btrfs_root *root;
2334
2335         if (reloc_root->last_trans == trans->transid)
2336                 return 0;
2337
2338         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2339         BUG_ON(IS_ERR(root));
2340         BUG_ON(root->reloc_root != reloc_root);
2341
2342         return btrfs_record_root_in_trans(trans, root);
2343 }
2344
2345 static noinline_for_stack
2346 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2347                                      struct reloc_control *rc,
2348                                      struct backref_node *node,
2349                                      struct backref_edge *edges[], int *nr)
2350 {
2351         struct backref_node *next;
2352         struct btrfs_root *root;
2353         int index = 0;
2354
2355         next = node;
2356         while (1) {
2357                 cond_resched();
2358                 next = walk_up_backref(next, edges, &index);
2359                 root = next->root;
2360                 BUG_ON(!root);
2361                 BUG_ON(!root->ref_cows);
2362
2363                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2364                         record_reloc_root_in_trans(trans, root);
2365                         break;
2366                 }
2367
2368                 btrfs_record_root_in_trans(trans, root);
2369                 root = root->reloc_root;
2370
2371                 if (next->new_bytenr != root->node->start) {
2372                         BUG_ON(next->new_bytenr);
2373                         BUG_ON(!list_empty(&next->list));
2374                         next->new_bytenr = root->node->start;
2375                         next->root = root;
2376                         list_add_tail(&next->list,
2377                                       &rc->backref_cache.changed);
2378                         __mark_block_processed(rc, next);
2379                         break;
2380                 }
2381
2382                 WARN_ON(1);
2383                 root = NULL;
2384                 next = walk_down_backref(edges, &index);
2385                 if (!next || next->level <= node->level)
2386                         break;
2387         }
2388         if (!root)
2389                 return NULL;
2390
2391         *nr = index;
2392         next = node;
2393         /* setup backref node path for btrfs_reloc_cow_block */
2394         while (1) {
2395                 rc->backref_cache.path[next->level] = next;
2396                 if (--index < 0)
2397                         break;
2398                 next = edges[index]->node[UPPER];
2399         }
2400         return root;
2401 }
2402
2403 /*
2404  * select a tree root for relocation. return NULL if the block
2405  * is reference counted. we should use do_relocation() in this
2406  * case. return a tree root pointer if the block isn't reference
2407  * counted. return -ENOENT if the block is root of reloc tree.
2408  */
2409 static noinline_for_stack
2410 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2411                                    struct backref_node *node)
2412 {
2413         struct backref_node *next;
2414         struct btrfs_root *root;
2415         struct btrfs_root *fs_root = NULL;
2416         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2417         int index = 0;
2418
2419         next = node;
2420         while (1) {
2421                 cond_resched();
2422                 next = walk_up_backref(next, edges, &index);
2423                 root = next->root;
2424                 BUG_ON(!root);
2425
2426                 /* no other choice for non-references counted tree */
2427                 if (!root->ref_cows)
2428                         return root;
2429
2430                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2431                         fs_root = root;
2432
2433                 if (next != node)
2434                         return NULL;
2435
2436                 next = walk_down_backref(edges, &index);
2437                 if (!next || next->level <= node->level)
2438                         break;
2439         }
2440
2441         if (!fs_root)
2442                 return ERR_PTR(-ENOENT);
2443         return fs_root;
2444 }
2445
2446 static noinline_for_stack
2447 u64 calcu_metadata_size(struct reloc_control *rc,
2448                         struct backref_node *node, int reserve)
2449 {
2450         struct backref_node *next = node;
2451         struct backref_edge *edge;
2452         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2453         u64 num_bytes = 0;
2454         int index = 0;
2455
2456         BUG_ON(reserve && node->processed);
2457
2458         while (next) {
2459                 cond_resched();
2460                 while (1) {
2461                         if (next->processed && (reserve || next != node))
2462                                 break;
2463
2464                         num_bytes += btrfs_level_size(rc->extent_root,
2465                                                       next->level);
2466
2467                         if (list_empty(&next->upper))
2468                                 break;
2469
2470                         edge = list_entry(next->upper.next,
2471                                           struct backref_edge, list[LOWER]);
2472                         edges[index++] = edge;
2473                         next = edge->node[UPPER];
2474                 }
2475                 next = walk_down_backref(edges, &index);
2476         }
2477         return num_bytes;
2478 }
2479
2480 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2481                                   struct reloc_control *rc,
2482                                   struct backref_node *node)
2483 {
2484         struct btrfs_root *root = rc->extent_root;
2485         u64 num_bytes;
2486         int ret;
2487
2488         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2489
2490         trans->block_rsv = rc->block_rsv;
2491         ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2492                                   BTRFS_RESERVE_FLUSH_ALL);
2493         if (ret) {
2494                 if (ret == -EAGAIN)
2495                         rc->commit_transaction = 1;
2496                 return ret;
2497         }
2498
2499         return 0;
2500 }
2501
2502 static void release_metadata_space(struct reloc_control *rc,
2503                                    struct backref_node *node)
2504 {
2505         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2506         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2507 }
2508
2509 /*
2510  * relocate a block tree, and then update pointers in upper level
2511  * blocks that reference the block to point to the new location.
2512  *
2513  * if called by link_to_upper, the block has already been relocated.
2514  * in that case this function just updates pointers.
2515  */
2516 static int do_relocation(struct btrfs_trans_handle *trans,
2517                          struct reloc_control *rc,
2518                          struct backref_node *node,
2519                          struct btrfs_key *key,
2520                          struct btrfs_path *path, int lowest)
2521 {
2522         struct backref_node *upper;
2523         struct backref_edge *edge;
2524         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2525         struct btrfs_root *root;
2526         struct extent_buffer *eb;
2527         u32 blocksize;
2528         u64 bytenr;
2529         u64 generation;
2530         int nr;
2531         int slot;
2532         int ret;
2533         int err = 0;
2534
2535         BUG_ON(lowest && node->eb);
2536
2537         path->lowest_level = node->level + 1;
2538         rc->backref_cache.path[node->level] = node;
2539         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2540                 cond_resched();
2541
2542                 upper = edge->node[UPPER];
2543                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2544                 BUG_ON(!root);
2545
2546                 if (upper->eb && !upper->locked) {
2547                         if (!lowest) {
2548                                 ret = btrfs_bin_search(upper->eb, key,
2549                                                        upper->level, &slot);
2550                                 BUG_ON(ret);
2551                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2552                                 if (node->eb->start == bytenr)
2553                                         goto next;
2554                         }
2555                         drop_node_buffer(upper);
2556                 }
2557
2558                 if (!upper->eb) {
2559                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2560                         if (ret < 0) {
2561                                 err = ret;
2562                                 break;
2563                         }
2564                         BUG_ON(ret > 0);
2565
2566                         if (!upper->eb) {
2567                                 upper->eb = path->nodes[upper->level];
2568                                 path->nodes[upper->level] = NULL;
2569                         } else {
2570                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2571                         }
2572
2573                         upper->locked = 1;
2574                         path->locks[upper->level] = 0;
2575
2576                         slot = path->slots[upper->level];
2577                         btrfs_release_path(path);
2578                 } else {
2579                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2580                                                &slot);
2581                         BUG_ON(ret);
2582                 }
2583
2584                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2585                 if (lowest) {
2586                         BUG_ON(bytenr != node->bytenr);
2587                 } else {
2588                         if (node->eb->start == bytenr)
2589                                 goto next;
2590                 }
2591
2592                 blocksize = btrfs_level_size(root, node->level);
2593                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2594                 eb = read_tree_block(root, bytenr, blocksize, generation);
2595                 if (!eb) {
2596                         err = -EIO;
2597                         goto next;
2598                 }
2599                 btrfs_tree_lock(eb);
2600                 btrfs_set_lock_blocking(eb);
2601
2602                 if (!node->eb) {
2603                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2604                                               slot, &eb);
2605                         btrfs_tree_unlock(eb);
2606                         free_extent_buffer(eb);
2607                         if (ret < 0) {
2608                                 err = ret;
2609                                 goto next;
2610                         }
2611                         BUG_ON(node->eb != eb);
2612                 } else {
2613                         btrfs_set_node_blockptr(upper->eb, slot,
2614                                                 node->eb->start);
2615                         btrfs_set_node_ptr_generation(upper->eb, slot,
2616                                                       trans->transid);
2617                         btrfs_mark_buffer_dirty(upper->eb);
2618
2619                         ret = btrfs_inc_extent_ref(trans, root,
2620                                                 node->eb->start, blocksize,
2621                                                 upper->eb->start,
2622                                                 btrfs_header_owner(upper->eb),
2623                                                 node->level, 0, 1);
2624                         BUG_ON(ret);
2625
2626                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2627                         BUG_ON(ret);
2628                 }
2629 next:
2630                 if (!upper->pending)
2631                         drop_node_buffer(upper);
2632                 else
2633                         unlock_node_buffer(upper);
2634                 if (err)
2635                         break;
2636         }
2637
2638         if (!err && node->pending) {
2639                 drop_node_buffer(node);
2640                 list_move_tail(&node->list, &rc->backref_cache.changed);
2641                 node->pending = 0;
2642         }
2643
2644         path->lowest_level = 0;
2645         BUG_ON(err == -ENOSPC);
2646         return err;
2647 }
2648
2649 static int link_to_upper(struct btrfs_trans_handle *trans,
2650                          struct reloc_control *rc,
2651                          struct backref_node *node,
2652                          struct btrfs_path *path)
2653 {
2654         struct btrfs_key key;
2655
2656         btrfs_node_key_to_cpu(node->eb, &key, 0);
2657         return do_relocation(trans, rc, node, &key, path, 0);
2658 }
2659
2660 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2661                                 struct reloc_control *rc,
2662                                 struct btrfs_path *path, int err)
2663 {
2664         LIST_HEAD(list);
2665         struct backref_cache *cache = &rc->backref_cache;
2666         struct backref_node *node;
2667         int level;
2668         int ret;
2669
2670         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2671                 while (!list_empty(&cache->pending[level])) {
2672                         node = list_entry(cache->pending[level].next,
2673                                           struct backref_node, list);
2674                         list_move_tail(&node->list, &list);
2675                         BUG_ON(!node->pending);
2676
2677                         if (!err) {
2678                                 ret = link_to_upper(trans, rc, node, path);
2679                                 if (ret < 0)
2680                                         err = ret;
2681                         }
2682                 }
2683                 list_splice_init(&list, &cache->pending[level]);
2684         }
2685         return err;
2686 }
2687
2688 static void mark_block_processed(struct reloc_control *rc,
2689                                  u64 bytenr, u32 blocksize)
2690 {
2691         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2692                         EXTENT_DIRTY, GFP_NOFS);
2693 }
2694
2695 static void __mark_block_processed(struct reloc_control *rc,
2696                                    struct backref_node *node)
2697 {
2698         u32 blocksize;
2699         if (node->level == 0 ||
2700             in_block_group(node->bytenr, rc->block_group)) {
2701                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2702                 mark_block_processed(rc, node->bytenr, blocksize);
2703         }
2704         node->processed = 1;
2705 }
2706
2707 /*
2708  * mark a block and all blocks directly/indirectly reference the block
2709  * as processed.
2710  */
2711 static void update_processed_blocks(struct reloc_control *rc,
2712                                     struct backref_node *node)
2713 {
2714         struct backref_node *next = node;
2715         struct backref_edge *edge;
2716         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2717         int index = 0;
2718
2719         while (next) {
2720                 cond_resched();
2721                 while (1) {
2722                         if (next->processed)
2723                                 break;
2724
2725                         __mark_block_processed(rc, next);
2726
2727                         if (list_empty(&next->upper))
2728                                 break;
2729
2730                         edge = list_entry(next->upper.next,
2731                                           struct backref_edge, list[LOWER]);
2732                         edges[index++] = edge;
2733                         next = edge->node[UPPER];
2734                 }
2735                 next = walk_down_backref(edges, &index);
2736         }
2737 }
2738
2739 static int tree_block_processed(u64 bytenr, u32 blocksize,
2740                                 struct reloc_control *rc)
2741 {
2742         if (test_range_bit(&rc->processed_blocks, bytenr,
2743                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2744                 return 1;
2745         return 0;
2746 }
2747
2748 static int get_tree_block_key(struct reloc_control *rc,
2749                               struct tree_block *block)
2750 {
2751         struct extent_buffer *eb;
2752
2753         BUG_ON(block->key_ready);
2754         eb = read_tree_block(rc->extent_root, block->bytenr,
2755                              block->key.objectid, block->key.offset);
2756         BUG_ON(!eb);
2757         WARN_ON(btrfs_header_level(eb) != block->level);
2758         if (block->level == 0)
2759                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2760         else
2761                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2762         free_extent_buffer(eb);
2763         block->key_ready = 1;
2764         return 0;
2765 }
2766
2767 static int reada_tree_block(struct reloc_control *rc,
2768                             struct tree_block *block)
2769 {
2770         BUG_ON(block->key_ready);
2771         readahead_tree_block(rc->extent_root, block->bytenr,
2772                              block->key.objectid, block->key.offset);
2773         return 0;
2774 }
2775
2776 /*
2777  * helper function to relocate a tree block
2778  */
2779 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2780                                 struct reloc_control *rc,
2781                                 struct backref_node *node,
2782                                 struct btrfs_key *key,
2783                                 struct btrfs_path *path)
2784 {
2785         struct btrfs_root *root;
2786         int release = 0;
2787         int ret = 0;
2788
2789         if (!node)
2790                 return 0;
2791
2792         BUG_ON(node->processed);
2793         root = select_one_root(trans, node);
2794         if (root == ERR_PTR(-ENOENT)) {
2795                 update_processed_blocks(rc, node);
2796                 goto out;
2797         }
2798
2799         if (!root || root->ref_cows) {
2800                 ret = reserve_metadata_space(trans, rc, node);
2801                 if (ret)
2802                         goto out;
2803                 release = 1;
2804         }
2805
2806         if (root) {
2807                 if (root->ref_cows) {
2808                         BUG_ON(node->new_bytenr);
2809                         BUG_ON(!list_empty(&node->list));
2810                         btrfs_record_root_in_trans(trans, root);
2811                         root = root->reloc_root;
2812                         node->new_bytenr = root->node->start;
2813                         node->root = root;
2814                         list_add_tail(&node->list, &rc->backref_cache.changed);
2815                 } else {
2816                         path->lowest_level = node->level;
2817                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2818                         btrfs_release_path(path);
2819                         if (ret > 0)
2820                                 ret = 0;
2821                 }
2822                 if (!ret)
2823                         update_processed_blocks(rc, node);
2824         } else {
2825                 ret = do_relocation(trans, rc, node, key, path, 1);
2826         }
2827 out:
2828         if (ret || node->level == 0 || node->cowonly) {
2829                 if (release)
2830                         release_metadata_space(rc, node);
2831                 remove_backref_node(&rc->backref_cache, node);
2832         }
2833         return ret;
2834 }
2835
2836 /*
2837  * relocate a list of blocks
2838  */
2839 static noinline_for_stack
2840 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2841                          struct reloc_control *rc, struct rb_root *blocks)
2842 {
2843         struct backref_node *node;
2844         struct btrfs_path *path;
2845         struct tree_block *block;
2846         struct rb_node *rb_node;
2847         int ret;
2848         int err = 0;
2849
2850         path = btrfs_alloc_path();
2851         if (!path) {
2852                 err = -ENOMEM;
2853                 goto out_path;
2854         }
2855
2856         rb_node = rb_first(blocks);
2857         while (rb_node) {
2858                 block = rb_entry(rb_node, struct tree_block, rb_node);
2859                 if (!block->key_ready)
2860                         reada_tree_block(rc, block);
2861                 rb_node = rb_next(rb_node);
2862         }
2863
2864         rb_node = rb_first(blocks);
2865         while (rb_node) {
2866                 block = rb_entry(rb_node, struct tree_block, rb_node);
2867                 if (!block->key_ready)
2868                         get_tree_block_key(rc, block);
2869                 rb_node = rb_next(rb_node);
2870         }
2871
2872         rb_node = rb_first(blocks);
2873         while (rb_node) {
2874                 block = rb_entry(rb_node, struct tree_block, rb_node);
2875
2876                 node = build_backref_tree(rc, &block->key,
2877                                           block->level, block->bytenr);
2878                 if (IS_ERR(node)) {
2879                         err = PTR_ERR(node);
2880                         goto out;
2881                 }
2882
2883                 ret = relocate_tree_block(trans, rc, node, &block->key,
2884                                           path);
2885                 if (ret < 0) {
2886                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2887                                 err = ret;
2888                         goto out;
2889                 }
2890                 rb_node = rb_next(rb_node);
2891         }
2892 out:
2893         err = finish_pending_nodes(trans, rc, path, err);
2894
2895         btrfs_free_path(path);
2896 out_path:
2897         free_block_list(blocks);
2898         return err;
2899 }
2900
2901 static noinline_for_stack
2902 int prealloc_file_extent_cluster(struct inode *inode,
2903                                  struct file_extent_cluster *cluster)
2904 {
2905         u64 alloc_hint = 0;
2906         u64 start;
2907         u64 end;
2908         u64 offset = BTRFS_I(inode)->index_cnt;
2909         u64 num_bytes;
2910         int nr = 0;
2911         int ret = 0;
2912
2913         BUG_ON(cluster->start != cluster->boundary[0]);
2914         mutex_lock(&inode->i_mutex);
2915
2916         ret = btrfs_check_data_free_space(inode, cluster->end +
2917                                           1 - cluster->start);
2918         if (ret)
2919                 goto out;
2920
2921         while (nr < cluster->nr) {
2922                 start = cluster->boundary[nr] - offset;
2923                 if (nr + 1 < cluster->nr)
2924                         end = cluster->boundary[nr + 1] - 1 - offset;
2925                 else
2926                         end = cluster->end - offset;
2927
2928                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2929                 num_bytes = end + 1 - start;
2930                 ret = btrfs_prealloc_file_range(inode, 0, start,
2931                                                 num_bytes, num_bytes,
2932                                                 end + 1, &alloc_hint);
2933                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2934                 if (ret)
2935                         break;
2936                 nr++;
2937         }
2938         btrfs_free_reserved_data_space(inode, cluster->end +
2939                                        1 - cluster->start);
2940 out:
2941         mutex_unlock(&inode->i_mutex);
2942         return ret;
2943 }
2944
2945 static noinline_for_stack
2946 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
2947                          u64 block_start)
2948 {
2949         struct btrfs_root *root = BTRFS_I(inode)->root;
2950         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2951         struct extent_map *em;
2952         int ret = 0;
2953
2954         em = alloc_extent_map();
2955         if (!em)
2956                 return -ENOMEM;
2957
2958         em->start = start;
2959         em->len = end + 1 - start;
2960         em->block_len = em->len;
2961         em->block_start = block_start;
2962         em->bdev = root->fs_info->fs_devices->latest_bdev;
2963         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2964
2965         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2966         while (1) {
2967                 write_lock(&em_tree->lock);
2968                 ret = add_extent_mapping(em_tree, em);
2969                 write_unlock(&em_tree->lock);
2970                 if (ret != -EEXIST) {
2971                         free_extent_map(em);
2972                         break;
2973                 }
2974                 btrfs_drop_extent_cache(inode, start, end, 0);
2975         }
2976         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2977         return ret;
2978 }
2979
2980 static int relocate_file_extent_cluster(struct inode *inode,
2981                                         struct file_extent_cluster *cluster)
2982 {
2983         u64 page_start;
2984         u64 page_end;
2985         u64 offset = BTRFS_I(inode)->index_cnt;
2986         unsigned long index;
2987         unsigned long last_index;
2988         struct page *page;
2989         struct file_ra_state *ra;
2990         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
2991         int nr = 0;
2992         int ret = 0;
2993
2994         if (!cluster->nr)
2995                 return 0;
2996
2997         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2998         if (!ra)
2999                 return -ENOMEM;
3000
3001         ret = prealloc_file_extent_cluster(inode, cluster);
3002         if (ret)
3003                 goto out;
3004
3005         file_ra_state_init(ra, inode->i_mapping);
3006
3007         ret = setup_extent_mapping(inode, cluster->start - offset,
3008                                    cluster->end - offset, cluster->start);
3009         if (ret)
3010                 goto out;
3011
3012         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3013         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3014         while (index <= last_index) {
3015                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3016                 if (ret)
3017                         goto out;
3018
3019                 page = find_lock_page(inode->i_mapping, index);
3020                 if (!page) {
3021                         page_cache_sync_readahead(inode->i_mapping,
3022                                                   ra, NULL, index,
3023                                                   last_index + 1 - index);
3024                         page = find_or_create_page(inode->i_mapping, index,
3025                                                    mask);
3026                         if (!page) {
3027                                 btrfs_delalloc_release_metadata(inode,
3028                                                         PAGE_CACHE_SIZE);
3029                                 ret = -ENOMEM;
3030                                 goto out;
3031                         }
3032                 }
3033
3034                 if (PageReadahead(page)) {
3035                         page_cache_async_readahead(inode->i_mapping,
3036                                                    ra, NULL, page, index,
3037                                                    last_index + 1 - index);
3038                 }
3039
3040                 if (!PageUptodate(page)) {
3041                         btrfs_readpage(NULL, page);
3042                         lock_page(page);
3043                         if (!PageUptodate(page)) {
3044                                 unlock_page(page);
3045                                 page_cache_release(page);
3046                                 btrfs_delalloc_release_metadata(inode,
3047                                                         PAGE_CACHE_SIZE);
3048                                 ret = -EIO;
3049                                 goto out;
3050                         }
3051                 }
3052
3053                 page_start = page_offset(page);
3054                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3055
3056                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3057
3058                 set_page_extent_mapped(page);
3059
3060                 if (nr < cluster->nr &&
3061                     page_start + offset == cluster->boundary[nr]) {
3062                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3063                                         page_start, page_end,
3064                                         EXTENT_BOUNDARY, GFP_NOFS);
3065                         nr++;
3066                 }
3067
3068                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3069                 set_page_dirty(page);
3070
3071                 unlock_extent(&BTRFS_I(inode)->io_tree,
3072                               page_start, page_end);
3073                 unlock_page(page);
3074                 page_cache_release(page);
3075
3076                 index++;
3077                 balance_dirty_pages_ratelimited(inode->i_mapping);
3078                 btrfs_throttle(BTRFS_I(inode)->root);
3079         }
3080         WARN_ON(nr != cluster->nr);
3081 out:
3082         kfree(ra);
3083         return ret;
3084 }
3085
3086 static noinline_for_stack
3087 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3088                          struct file_extent_cluster *cluster)
3089 {
3090         int ret;
3091
3092         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3093                 ret = relocate_file_extent_cluster(inode, cluster);
3094                 if (ret)
3095                         return ret;
3096                 cluster->nr = 0;
3097         }
3098
3099         if (!cluster->nr)
3100                 cluster->start = extent_key->objectid;
3101         else
3102                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3103         cluster->end = extent_key->objectid + extent_key->offset - 1;
3104         cluster->boundary[cluster->nr] = extent_key->objectid;
3105         cluster->nr++;
3106
3107         if (cluster->nr >= MAX_EXTENTS) {
3108                 ret = relocate_file_extent_cluster(inode, cluster);
3109                 if (ret)
3110                         return ret;
3111                 cluster->nr = 0;
3112         }
3113         return 0;
3114 }
3115
3116 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3117 static int get_ref_objectid_v0(struct reloc_control *rc,
3118                                struct btrfs_path *path,
3119                                struct btrfs_key *extent_key,
3120                                u64 *ref_objectid, int *path_change)
3121 {
3122         struct btrfs_key key;
3123         struct extent_buffer *leaf;
3124         struct btrfs_extent_ref_v0 *ref0;
3125         int ret;
3126         int slot;
3127
3128         leaf = path->nodes[0];
3129         slot = path->slots[0];
3130         while (1) {
3131                 if (slot >= btrfs_header_nritems(leaf)) {
3132                         ret = btrfs_next_leaf(rc->extent_root, path);
3133                         if (ret < 0)
3134                                 return ret;
3135                         BUG_ON(ret > 0);
3136                         leaf = path->nodes[0];
3137                         slot = path->slots[0];
3138                         if (path_change)
3139                                 *path_change = 1;
3140                 }
3141                 btrfs_item_key_to_cpu(leaf, &key, slot);
3142                 if (key.objectid != extent_key->objectid)
3143                         return -ENOENT;
3144
3145                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3146                         slot++;
3147                         continue;
3148                 }
3149                 ref0 = btrfs_item_ptr(leaf, slot,
3150                                 struct btrfs_extent_ref_v0);
3151                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3152                 break;
3153         }
3154         return 0;
3155 }
3156 #endif
3157
3158 /*
3159  * helper to add a tree block to the list.
3160  * the major work is getting the generation and level of the block
3161  */
3162 static int add_tree_block(struct reloc_control *rc,
3163                           struct btrfs_key *extent_key,
3164                           struct btrfs_path *path,
3165                           struct rb_root *blocks)
3166 {
3167         struct extent_buffer *eb;
3168         struct btrfs_extent_item *ei;
3169         struct btrfs_tree_block_info *bi;
3170         struct tree_block *block;
3171         struct rb_node *rb_node;
3172         u32 item_size;
3173         int level = -1;
3174         int generation;
3175
3176         eb =  path->nodes[0];
3177         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3178
3179         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
3180                 ei = btrfs_item_ptr(eb, path->slots[0],
3181                                 struct btrfs_extent_item);
3182                 bi = (struct btrfs_tree_block_info *)(ei + 1);
3183                 generation = btrfs_extent_generation(eb, ei);
3184                 level = btrfs_tree_block_level(eb, bi);
3185         } else {
3186 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3187                 u64 ref_owner;
3188                 int ret;
3189
3190                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3191                 ret = get_ref_objectid_v0(rc, path, extent_key,
3192                                           &ref_owner, NULL);
3193                 if (ret < 0)
3194                         return ret;
3195                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3196                 level = (int)ref_owner;
3197                 /* FIXME: get real generation */
3198                 generation = 0;
3199 #else
3200                 BUG();
3201 #endif
3202         }
3203
3204         btrfs_release_path(path);
3205
3206         BUG_ON(level == -1);
3207
3208         block = kmalloc(sizeof(*block), GFP_NOFS);
3209         if (!block)
3210                 return -ENOMEM;
3211
3212         block->bytenr = extent_key->objectid;
3213         block->key.objectid = extent_key->offset;
3214         block->key.offset = generation;
3215         block->level = level;
3216         block->key_ready = 0;
3217
3218         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3219         if (rb_node)
3220                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3221
3222         return 0;
3223 }
3224
3225 /*
3226  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3227  */
3228 static int __add_tree_block(struct reloc_control *rc,
3229                             u64 bytenr, u32 blocksize,
3230                             struct rb_root *blocks)
3231 {
3232         struct btrfs_path *path;
3233         struct btrfs_key key;
3234         int ret;
3235
3236         if (tree_block_processed(bytenr, blocksize, rc))
3237                 return 0;
3238
3239         if (tree_search(blocks, bytenr))
3240                 return 0;
3241
3242         path = btrfs_alloc_path();
3243         if (!path)
3244                 return -ENOMEM;
3245
3246         key.objectid = bytenr;
3247         key.type = BTRFS_EXTENT_ITEM_KEY;
3248         key.offset = blocksize;
3249
3250         path->search_commit_root = 1;
3251         path->skip_locking = 1;
3252         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3253         if (ret < 0)
3254                 goto out;
3255         BUG_ON(ret);
3256
3257         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3258         ret = add_tree_block(rc, &key, path, blocks);
3259 out:
3260         btrfs_free_path(path);
3261         return ret;
3262 }
3263
3264 /*
3265  * helper to check if the block use full backrefs for pointers in it
3266  */
3267 static int block_use_full_backref(struct reloc_control *rc,
3268                                   struct extent_buffer *eb)
3269 {
3270         u64 flags;
3271         int ret;
3272
3273         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3274             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3275                 return 1;
3276
3277         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3278                                        eb->start, eb->len, NULL, &flags);
3279         BUG_ON(ret);
3280
3281         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3282                 ret = 1;
3283         else
3284                 ret = 0;
3285         return ret;
3286 }
3287
3288 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3289                                     struct inode *inode, u64 ino)
3290 {
3291         struct btrfs_key key;
3292         struct btrfs_path *path;
3293         struct btrfs_root *root = fs_info->tree_root;
3294         struct btrfs_trans_handle *trans;
3295         int ret = 0;
3296
3297         if (inode)
3298                 goto truncate;
3299
3300         key.objectid = ino;
3301         key.type = BTRFS_INODE_ITEM_KEY;
3302         key.offset = 0;
3303
3304         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3305         if (IS_ERR(inode) || is_bad_inode(inode)) {
3306                 if (!IS_ERR(inode))
3307                         iput(inode);
3308                 return -ENOENT;
3309         }
3310
3311 truncate:
3312         path = btrfs_alloc_path();
3313         if (!path) {
3314                 ret = -ENOMEM;
3315                 goto out;
3316         }
3317
3318         trans = btrfs_join_transaction(root);
3319         if (IS_ERR(trans)) {
3320                 btrfs_free_path(path);
3321                 ret = PTR_ERR(trans);
3322                 goto out;
3323         }
3324
3325         ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3326
3327         btrfs_free_path(path);
3328         btrfs_end_transaction(trans, root);
3329         btrfs_btree_balance_dirty(root);
3330 out:
3331         iput(inode);
3332         return ret;
3333 }
3334
3335 /*
3336  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3337  * this function scans fs tree to find blocks reference the data extent
3338  */
3339 static int find_data_references(struct reloc_control *rc,
3340                                 struct btrfs_key *extent_key,
3341                                 struct extent_buffer *leaf,
3342                                 struct btrfs_extent_data_ref *ref,
3343                                 struct rb_root *blocks)
3344 {
3345         struct btrfs_path *path;
3346         struct tree_block *block;
3347         struct btrfs_root *root;
3348         struct btrfs_file_extent_item *fi;
3349         struct rb_node *rb_node;
3350         struct btrfs_key key;
3351         u64 ref_root;
3352         u64 ref_objectid;
3353         u64 ref_offset;
3354         u32 ref_count;
3355         u32 nritems;
3356         int err = 0;
3357         int added = 0;
3358         int counted;
3359         int ret;
3360
3361         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3362         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3363         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3364         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3365
3366         /*
3367          * This is an extent belonging to the free space cache, lets just delete
3368          * it and redo the search.
3369          */
3370         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3371                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3372                                                NULL, ref_objectid);
3373                 if (ret != -ENOENT)
3374                         return ret;
3375                 ret = 0;
3376         }
3377
3378         path = btrfs_alloc_path();
3379         if (!path)
3380                 return -ENOMEM;
3381         path->reada = 1;
3382
3383         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3384         if (IS_ERR(root)) {
3385                 err = PTR_ERR(root);
3386                 goto out;
3387         }
3388
3389         key.objectid = ref_objectid;
3390         key.type = BTRFS_EXTENT_DATA_KEY;
3391         if (ref_offset > ((u64)-1 << 32))
3392                 key.offset = 0;
3393         else
3394                 key.offset = ref_offset;
3395
3396         path->search_commit_root = 1;
3397         path->skip_locking = 1;
3398         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3399         if (ret < 0) {
3400                 err = ret;
3401                 goto out;
3402         }
3403
3404         leaf = path->nodes[0];
3405         nritems = btrfs_header_nritems(leaf);
3406         /*
3407          * the references in tree blocks that use full backrefs
3408          * are not counted in
3409          */
3410         if (block_use_full_backref(rc, leaf))
3411                 counted = 0;
3412         else
3413                 counted = 1;
3414         rb_node = tree_search(blocks, leaf->start);
3415         if (rb_node) {
3416                 if (counted)
3417                         added = 1;
3418                 else
3419                         path->slots[0] = nritems;
3420         }
3421
3422         while (ref_count > 0) {
3423                 while (path->slots[0] >= nritems) {
3424                         ret = btrfs_next_leaf(root, path);
3425                         if (ret < 0) {
3426                                 err = ret;
3427                                 goto out;
3428                         }
3429                         if (ret > 0) {
3430                                 WARN_ON(1);
3431                                 goto out;
3432                         }
3433
3434                         leaf = path->nodes[0];
3435                         nritems = btrfs_header_nritems(leaf);
3436                         added = 0;
3437
3438                         if (block_use_full_backref(rc, leaf))
3439                                 counted = 0;
3440                         else
3441                                 counted = 1;
3442                         rb_node = tree_search(blocks, leaf->start);
3443                         if (rb_node) {
3444                                 if (counted)
3445                                         added = 1;
3446                                 else
3447                                         path->slots[0] = nritems;
3448                         }
3449                 }
3450
3451                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3452                 if (key.objectid != ref_objectid ||
3453                     key.type != BTRFS_EXTENT_DATA_KEY) {
3454                         WARN_ON(1);
3455                         break;
3456                 }
3457
3458                 fi = btrfs_item_ptr(leaf, path->slots[0],
3459                                     struct btrfs_file_extent_item);
3460
3461                 if (btrfs_file_extent_type(leaf, fi) ==
3462                     BTRFS_FILE_EXTENT_INLINE)
3463                         goto next;
3464
3465                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3466                     extent_key->objectid)
3467                         goto next;
3468
3469                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3470                 if (key.offset != ref_offset)
3471                         goto next;
3472
3473                 if (counted)
3474                         ref_count--;
3475                 if (added)
3476                         goto next;
3477
3478                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3479                         block = kmalloc(sizeof(*block), GFP_NOFS);
3480                         if (!block) {
3481                                 err = -ENOMEM;
3482                                 break;
3483                         }
3484                         block->bytenr = leaf->start;
3485                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3486                         block->level = 0;
3487                         block->key_ready = 1;
3488                         rb_node = tree_insert(blocks, block->bytenr,
3489                                               &block->rb_node);
3490                         if (rb_node)
3491                                 backref_tree_panic(rb_node, -EEXIST,
3492                                                    block->bytenr);
3493                 }
3494                 if (counted)
3495                         added = 1;
3496                 else
3497                         path->slots[0] = nritems;
3498 next:
3499                 path->slots[0]++;
3500
3501         }
3502 out:
3503         btrfs_free_path(path);
3504         return err;
3505 }
3506
3507 /*
3508  * hepler to find all tree blocks that reference a given data extent
3509  */
3510 static noinline_for_stack
3511 int add_data_references(struct reloc_control *rc,
3512                         struct btrfs_key *extent_key,
3513                         struct btrfs_path *path,
3514                         struct rb_root *blocks)
3515 {
3516         struct btrfs_key key;
3517         struct extent_buffer *eb;
3518         struct btrfs_extent_data_ref *dref;
3519         struct btrfs_extent_inline_ref *iref;
3520         unsigned long ptr;
3521         unsigned long end;
3522         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3523         int ret;
3524         int err = 0;
3525
3526         eb = path->nodes[0];
3527         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3528         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3529 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3530         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3531                 ptr = end;
3532         else
3533 #endif
3534                 ptr += sizeof(struct btrfs_extent_item);
3535
3536         while (ptr < end) {
3537                 iref = (struct btrfs_extent_inline_ref *)ptr;
3538                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3539                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3540                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3541                         ret = __add_tree_block(rc, key.offset, blocksize,
3542                                                blocks);
3543                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3544                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3545                         ret = find_data_references(rc, extent_key,
3546                                                    eb, dref, blocks);
3547                 } else {
3548                         BUG();
3549                 }
3550                 ptr += btrfs_extent_inline_ref_size(key.type);
3551         }
3552         WARN_ON(ptr > end);
3553
3554         while (1) {
3555                 cond_resched();
3556                 eb = path->nodes[0];
3557                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3558                         ret = btrfs_next_leaf(rc->extent_root, path);
3559                         if (ret < 0) {
3560                                 err = ret;
3561                                 break;
3562                         }
3563                         if (ret > 0)
3564                                 break;
3565                         eb = path->nodes[0];
3566                 }
3567
3568                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3569                 if (key.objectid != extent_key->objectid)
3570                         break;
3571
3572 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3573                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3574                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3575 #else
3576                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3577                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3578 #endif
3579                         ret = __add_tree_block(rc, key.offset, blocksize,
3580                                                blocks);
3581                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3582                         dref = btrfs_item_ptr(eb, path->slots[0],
3583                                               struct btrfs_extent_data_ref);
3584                         ret = find_data_references(rc, extent_key,
3585                                                    eb, dref, blocks);
3586                 } else {
3587                         ret = 0;
3588                 }
3589                 if (ret) {
3590                         err = ret;
3591                         break;
3592                 }
3593                 path->slots[0]++;
3594         }
3595         btrfs_release_path(path);
3596         if (err)
3597                 free_block_list(blocks);
3598         return err;
3599 }
3600
3601 /*
3602  * hepler to find next unprocessed extent
3603  */
3604 static noinline_for_stack
3605 int find_next_extent(struct btrfs_trans_handle *trans,
3606                      struct reloc_control *rc, struct btrfs_path *path,
3607                      struct btrfs_key *extent_key)
3608 {
3609         struct btrfs_key key;
3610         struct extent_buffer *leaf;
3611         u64 start, end, last;
3612         int ret;
3613
3614         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3615         while (1) {
3616                 cond_resched();
3617                 if (rc->search_start >= last) {
3618                         ret = 1;
3619                         break;
3620                 }
3621
3622                 key.objectid = rc->search_start;
3623                 key.type = BTRFS_EXTENT_ITEM_KEY;
3624                 key.offset = 0;
3625
3626                 path->search_commit_root = 1;
3627                 path->skip_locking = 1;
3628                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3629                                         0, 0);
3630                 if (ret < 0)
3631                         break;
3632 next:
3633                 leaf = path->nodes[0];
3634                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3635                         ret = btrfs_next_leaf(rc->extent_root, path);
3636                         if (ret != 0)
3637                                 break;
3638                         leaf = path->nodes[0];
3639                 }
3640
3641                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3642                 if (key.objectid >= last) {
3643                         ret = 1;
3644                         break;
3645                 }
3646
3647                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3648                     key.objectid + key.offset <= rc->search_start) {
3649                         path->slots[0]++;
3650                         goto next;
3651                 }
3652
3653                 ret = find_first_extent_bit(&rc->processed_blocks,
3654                                             key.objectid, &start, &end,
3655                                             EXTENT_DIRTY, NULL);
3656
3657                 if (ret == 0 && start <= key.objectid) {
3658                         btrfs_release_path(path);
3659                         rc->search_start = end + 1;
3660                 } else {
3661                         rc->search_start = key.objectid + key.offset;
3662                         memcpy(extent_key, &key, sizeof(key));
3663                         return 0;
3664                 }
3665         }
3666         btrfs_release_path(path);
3667         return ret;
3668 }
3669
3670 static void set_reloc_control(struct reloc_control *rc)
3671 {
3672         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3673
3674         mutex_lock(&fs_info->reloc_mutex);
3675         fs_info->reloc_ctl = rc;
3676         mutex_unlock(&fs_info->reloc_mutex);
3677 }
3678
3679 static void unset_reloc_control(struct reloc_control *rc)
3680 {
3681         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3682
3683         mutex_lock(&fs_info->reloc_mutex);
3684         fs_info->reloc_ctl = NULL;
3685         mutex_unlock(&fs_info->reloc_mutex);
3686 }
3687
3688 static int check_extent_flags(u64 flags)
3689 {
3690         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3691             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3692                 return 1;
3693         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3694             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3695                 return 1;
3696         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3697             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3698                 return 1;
3699         return 0;
3700 }
3701
3702 static noinline_for_stack
3703 int prepare_to_relocate(struct reloc_control *rc)
3704 {
3705         struct btrfs_trans_handle *trans;
3706         int ret;
3707
3708         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3709                                               BTRFS_BLOCK_RSV_TEMP);
3710         if (!rc->block_rsv)
3711                 return -ENOMEM;
3712
3713         /*
3714          * reserve some space for creating reloc trees.
3715          * btrfs_init_reloc_root will use them when there
3716          * is no reservation in transaction handle.
3717          */
3718         ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3719                                   rc->extent_root->nodesize * 256,
3720                                   BTRFS_RESERVE_FLUSH_ALL);
3721         if (ret)
3722                 return ret;
3723
3724         memset(&rc->cluster, 0, sizeof(rc->cluster));
3725         rc->search_start = rc->block_group->key.objectid;
3726         rc->extents_found = 0;
3727         rc->nodes_relocated = 0;
3728         rc->merging_rsv_size = 0;
3729
3730         rc->create_reloc_tree = 1;
3731         set_reloc_control(rc);
3732
3733         trans = btrfs_join_transaction(rc->extent_root);
3734         BUG_ON(IS_ERR(trans));
3735         btrfs_commit_transaction(trans, rc->extent_root);
3736         return 0;
3737 }
3738
3739 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3740 {
3741         struct rb_root blocks = RB_ROOT;
3742         struct btrfs_key key;
3743         struct btrfs_trans_handle *trans = NULL;
3744         struct btrfs_path *path;
3745         struct btrfs_extent_item *ei;
3746         u64 flags;
3747         u32 item_size;
3748         int ret;
3749         int err = 0;
3750         int progress = 0;
3751
3752         path = btrfs_alloc_path();
3753         if (!path)
3754                 return -ENOMEM;
3755         path->reada = 1;
3756
3757         ret = prepare_to_relocate(rc);
3758         if (ret) {
3759                 err = ret;
3760                 goto out_free;
3761         }
3762
3763         while (1) {
3764                 progress++;
3765                 trans = btrfs_start_transaction(rc->extent_root, 0);
3766                 BUG_ON(IS_ERR(trans));
3767 restart:
3768                 if (update_backref_cache(trans, &rc->backref_cache)) {
3769                         btrfs_end_transaction(trans, rc->extent_root);
3770                         continue;
3771                 }
3772
3773                 ret = find_next_extent(trans, rc, path, &key);
3774                 if (ret < 0)
3775                         err = ret;
3776                 if (ret != 0)
3777                         break;
3778
3779                 rc->extents_found++;
3780
3781                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3782                                     struct btrfs_extent_item);
3783                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3784                 if (item_size >= sizeof(*ei)) {
3785                         flags = btrfs_extent_flags(path->nodes[0], ei);
3786                         ret = check_extent_flags(flags);
3787                         BUG_ON(ret);
3788
3789                 } else {
3790 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3791                         u64 ref_owner;
3792                         int path_change = 0;
3793
3794                         BUG_ON(item_size !=
3795                                sizeof(struct btrfs_extent_item_v0));
3796                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3797                                                   &path_change);
3798                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3799                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3800                         else
3801                                 flags = BTRFS_EXTENT_FLAG_DATA;
3802
3803                         if (path_change) {
3804                                 btrfs_release_path(path);
3805
3806                                 path->search_commit_root = 1;
3807                                 path->skip_locking = 1;
3808                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3809                                                         &key, path, 0, 0);
3810                                 if (ret < 0) {
3811                                         err = ret;
3812                                         break;
3813                                 }
3814                                 BUG_ON(ret > 0);
3815                         }
3816 #else
3817                         BUG();
3818 #endif
3819                 }
3820
3821                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3822                         ret = add_tree_block(rc, &key, path, &blocks);
3823                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3824                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3825                         ret = add_data_references(rc, &key, path, &blocks);
3826                 } else {
3827                         btrfs_release_path(path);
3828                         ret = 0;
3829                 }
3830                 if (ret < 0) {
3831                         err = ret;
3832                         break;
3833                 }
3834
3835                 if (!RB_EMPTY_ROOT(&blocks)) {
3836                         ret = relocate_tree_blocks(trans, rc, &blocks);
3837                         if (ret < 0) {
3838                                 if (ret != -EAGAIN) {
3839                                         err = ret;
3840                                         break;
3841                                 }
3842                                 rc->extents_found--;
3843                                 rc->search_start = key.objectid;
3844                         }
3845                 }
3846
3847                 ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
3848                 if (ret < 0) {
3849                         if (ret != -ENOSPC) {
3850                                 err = ret;
3851                                 WARN_ON(1);
3852                                 break;
3853                         }
3854                         rc->commit_transaction = 1;
3855                 }
3856
3857                 if (rc->commit_transaction) {
3858                         rc->commit_transaction = 0;
3859                         ret = btrfs_commit_transaction(trans, rc->extent_root);
3860                         BUG_ON(ret);
3861                 } else {
3862                         btrfs_end_transaction_throttle(trans, rc->extent_root);
3863                         btrfs_btree_balance_dirty(rc->extent_root);
3864                 }
3865                 trans = NULL;
3866
3867                 if (rc->stage == MOVE_DATA_EXTENTS &&
3868                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3869                         rc->found_file_extent = 1;
3870                         ret = relocate_data_extent(rc->data_inode,
3871                                                    &key, &rc->cluster);
3872                         if (ret < 0) {
3873                                 err = ret;
3874                                 break;
3875                         }
3876                 }
3877         }
3878         if (trans && progress && err == -ENOSPC) {
3879                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
3880                                               rc->block_group->flags);
3881                 if (ret == 0) {
3882                         err = 0;
3883                         progress = 0;
3884                         goto restart;
3885                 }
3886         }
3887
3888         btrfs_release_path(path);
3889         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3890                           GFP_NOFS);
3891
3892         if (trans) {
3893                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3894                 btrfs_btree_balance_dirty(rc->extent_root);
3895         }
3896
3897         if (!err) {
3898                 ret = relocate_file_extent_cluster(rc->data_inode,
3899                                                    &rc->cluster);
3900                 if (ret < 0)
3901                         err = ret;
3902         }
3903
3904         rc->create_reloc_tree = 0;
3905         set_reloc_control(rc);
3906
3907         backref_cache_cleanup(&rc->backref_cache);
3908         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3909
3910         err = prepare_to_merge(rc, err);
3911
3912         merge_reloc_roots(rc);
3913
3914         rc->merge_reloc_tree = 0;
3915         unset_reloc_control(rc);
3916         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
3917
3918         /* get rid of pinned extents */
3919         trans = btrfs_join_transaction(rc->extent_root);
3920         if (IS_ERR(trans))
3921                 err = PTR_ERR(trans);
3922         else
3923                 btrfs_commit_transaction(trans, rc->extent_root);
3924 out_free:
3925         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
3926         btrfs_free_path(path);
3927         return err;
3928 }
3929
3930 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3931                                  struct btrfs_root *root, u64 objectid)
3932 {
3933         struct btrfs_path *path;
3934         struct btrfs_inode_item *item;
3935         struct extent_buffer *leaf;
3936         int ret;
3937
3938         path = btrfs_alloc_path();
3939         if (!path)
3940                 return -ENOMEM;
3941
3942         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3943         if (ret)
3944                 goto out;
3945
3946         leaf = path->nodes[0];
3947         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3948         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3949         btrfs_set_inode_generation(leaf, item, 1);
3950         btrfs_set_inode_size(leaf, item, 0);
3951         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3952         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
3953                                           BTRFS_INODE_PREALLOC);
3954         btrfs_mark_buffer_dirty(leaf);
3955         btrfs_release_path(path);
3956 out:
3957         btrfs_free_path(path);
3958         return ret;
3959 }
3960
3961 /*
3962  * helper to create inode for data relocation.
3963  * the inode is in data relocation tree and its link count is 0
3964  */
3965 static noinline_for_stack
3966 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3967                                  struct btrfs_block_group_cache *group)
3968 {
3969         struct inode *inode = NULL;
3970         struct btrfs_trans_handle *trans;
3971         struct btrfs_root *root;
3972         struct btrfs_key key;
3973         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3974         int err = 0;
3975
3976         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3977         if (IS_ERR(root))
3978                 return ERR_CAST(root);
3979
3980         trans = btrfs_start_transaction(root, 6);
3981         if (IS_ERR(trans))
3982                 return ERR_CAST(trans);
3983
3984         err = btrfs_find_free_objectid(root, &objectid);
3985         if (err)
3986                 goto out;
3987
3988         err = __insert_orphan_inode(trans, root, objectid);
3989         BUG_ON(err);
3990
3991         key.objectid = objectid;
3992         key.type = BTRFS_INODE_ITEM_KEY;
3993         key.offset = 0;
3994         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
3995         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3996         BTRFS_I(inode)->index_cnt = group->key.objectid;
3997
3998         err = btrfs_orphan_add(trans, inode);
3999 out:
4000         btrfs_end_transaction(trans, root);
4001         btrfs_btree_balance_dirty(root);
4002         if (err) {
4003                 if (inode)
4004                         iput(inode);
4005                 inode = ERR_PTR(err);
4006         }
4007         return inode;
4008 }
4009
4010 static struct reloc_control *alloc_reloc_control(void)
4011 {
4012         struct reloc_control *rc;
4013
4014         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4015         if (!rc)
4016                 return NULL;
4017
4018         INIT_LIST_HEAD(&rc->reloc_roots);
4019         backref_cache_init(&rc->backref_cache);
4020         mapping_tree_init(&rc->reloc_root_tree);
4021         extent_io_tree_init(&rc->processed_blocks, NULL);
4022         return rc;
4023 }
4024
4025 /*
4026  * function to relocate all extents in a block group.
4027  */
4028 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4029 {
4030         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4031         struct reloc_control *rc;
4032         struct inode *inode;
4033         struct btrfs_path *path;
4034         int ret;
4035         int rw = 0;
4036         int err = 0;
4037
4038         rc = alloc_reloc_control();
4039         if (!rc)
4040                 return -ENOMEM;
4041
4042         rc->extent_root = extent_root;
4043
4044         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4045         BUG_ON(!rc->block_group);
4046
4047         if (!rc->block_group->ro) {
4048                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4049                 if (ret) {
4050                         err = ret;
4051                         goto out;
4052                 }
4053                 rw = 1;
4054         }
4055
4056         path = btrfs_alloc_path();
4057         if (!path) {
4058                 err = -ENOMEM;
4059                 goto out;
4060         }
4061
4062         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4063                                         path);
4064         btrfs_free_path(path);
4065
4066         if (!IS_ERR(inode))
4067                 ret = delete_block_group_cache(fs_info, inode, 0);
4068         else
4069                 ret = PTR_ERR(inode);
4070
4071         if (ret && ret != -ENOENT) {
4072                 err = ret;
4073                 goto out;
4074         }
4075
4076         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4077         if (IS_ERR(rc->data_inode)) {
4078                 err = PTR_ERR(rc->data_inode);
4079                 rc->data_inode = NULL;
4080                 goto out;
4081         }
4082
4083         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4084                (unsigned long long)rc->block_group->key.objectid,
4085                (unsigned long long)rc->block_group->flags);
4086
4087         ret = btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
4088         if (ret < 0) {
4089                 err = ret;
4090                 goto out;
4091         }
4092         btrfs_wait_ordered_extents(fs_info->tree_root, 0);
4093
4094         while (1) {
4095                 mutex_lock(&fs_info->cleaner_mutex);
4096
4097                 btrfs_clean_old_snapshots(fs_info->tree_root);
4098                 ret = relocate_block_group(rc);
4099
4100                 mutex_unlock(&fs_info->cleaner_mutex);
4101                 if (ret < 0) {
4102                         err = ret;
4103                         goto out;
4104                 }
4105
4106                 if (rc->extents_found == 0)
4107                         break;
4108
4109                 printk(KERN_INFO "btrfs: found %llu extents\n",
4110                         (unsigned long long)rc->extents_found);
4111
4112                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4113                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4114                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4115                                                  0, -1);
4116                         rc->stage = UPDATE_DATA_PTRS;
4117                 }
4118         }
4119
4120         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4121                                      rc->block_group->key.objectid,
4122                                      rc->block_group->key.objectid +
4123                                      rc->block_group->key.offset - 1);
4124
4125         WARN_ON(rc->block_group->pinned > 0);
4126         WARN_ON(rc->block_group->reserved > 0);
4127         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4128 out:
4129         if (err && rw)
4130                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4131         iput(rc->data_inode);
4132         btrfs_put_block_group(rc->block_group);
4133         kfree(rc);
4134         return err;
4135 }
4136
4137 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4138 {
4139         struct btrfs_trans_handle *trans;
4140         int ret, err;
4141
4142         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4143         if (IS_ERR(trans))
4144                 return PTR_ERR(trans);
4145
4146         memset(&root->root_item.drop_progress, 0,
4147                 sizeof(root->root_item.drop_progress));
4148         root->root_item.drop_level = 0;
4149         btrfs_set_root_refs(&root->root_item, 0);
4150         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4151                                 &root->root_key, &root->root_item);
4152
4153         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4154         if (err)
4155                 return err;
4156         return ret;
4157 }
4158
4159 /*
4160  * recover relocation interrupted by system crash.
4161  *
4162  * this function resumes merging reloc trees with corresponding fs trees.
4163  * this is important for keeping the sharing of tree blocks
4164  */
4165 int btrfs_recover_relocation(struct btrfs_root *root)
4166 {
4167         LIST_HEAD(reloc_roots);
4168         struct btrfs_key key;
4169         struct btrfs_root *fs_root;
4170         struct btrfs_root *reloc_root;
4171         struct btrfs_path *path;
4172         struct extent_buffer *leaf;
4173         struct reloc_control *rc = NULL;
4174         struct btrfs_trans_handle *trans;
4175         int ret;
4176         int err = 0;
4177
4178         path = btrfs_alloc_path();
4179         if (!path)
4180                 return -ENOMEM;
4181         path->reada = -1;
4182
4183         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4184         key.type = BTRFS_ROOT_ITEM_KEY;
4185         key.offset = (u64)-1;
4186
4187         while (1) {
4188                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4189                                         path, 0, 0);
4190                 if (ret < 0) {
4191                         err = ret;
4192                         goto out;
4193                 }
4194                 if (ret > 0) {
4195                         if (path->slots[0] == 0)
4196                                 break;
4197                         path->slots[0]--;
4198                 }
4199                 leaf = path->nodes[0];
4200                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4201                 btrfs_release_path(path);
4202
4203                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4204                     key.type != BTRFS_ROOT_ITEM_KEY)
4205                         break;
4206
4207                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
4208                 if (IS_ERR(reloc_root)) {
4209                         err = PTR_ERR(reloc_root);
4210                         goto out;
4211                 }
4212
4213                 list_add(&reloc_root->root_list, &reloc_roots);
4214
4215                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4216                         fs_root = read_fs_root(root->fs_info,
4217                                                reloc_root->root_key.offset);
4218                         if (IS_ERR(fs_root)) {
4219                                 ret = PTR_ERR(fs_root);
4220                                 if (ret != -ENOENT) {
4221                                         err = ret;
4222                                         goto out;
4223                                 }
4224                                 ret = mark_garbage_root(reloc_root);
4225                                 if (ret < 0) {
4226                                         err = ret;
4227                                         goto out;
4228                                 }
4229                         }
4230                 }
4231
4232                 if (key.offset == 0)
4233                         break;
4234
4235                 key.offset--;
4236         }
4237         btrfs_release_path(path);
4238
4239         if (list_empty(&reloc_roots))
4240                 goto out;
4241
4242         rc = alloc_reloc_control();
4243         if (!rc) {
4244                 err = -ENOMEM;
4245                 goto out;
4246         }
4247
4248         rc->extent_root = root->fs_info->extent_root;
4249
4250         set_reloc_control(rc);
4251
4252         trans = btrfs_join_transaction(rc->extent_root);
4253         if (IS_ERR(trans)) {
4254                 unset_reloc_control(rc);
4255                 err = PTR_ERR(trans);
4256                 goto out_free;
4257         }
4258
4259         rc->merge_reloc_tree = 1;
4260
4261         while (!list_empty(&reloc_roots)) {
4262                 reloc_root = list_entry(reloc_roots.next,
4263                                         struct btrfs_root, root_list);
4264                 list_del(&reloc_root->root_list);
4265
4266                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4267                         list_add_tail(&reloc_root->root_list,
4268                                       &rc->reloc_roots);
4269                         continue;
4270                 }
4271
4272                 fs_root = read_fs_root(root->fs_info,
4273                                        reloc_root->root_key.offset);
4274                 if (IS_ERR(fs_root)) {
4275                         err = PTR_ERR(fs_root);
4276                         goto out_free;
4277                 }
4278
4279                 err = __add_reloc_root(reloc_root);
4280                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4281                 fs_root->reloc_root = reloc_root;
4282         }
4283
4284         err = btrfs_commit_transaction(trans, rc->extent_root);
4285         if (err)
4286                 goto out_free;
4287
4288         merge_reloc_roots(rc);
4289
4290         unset_reloc_control(rc);
4291
4292         trans = btrfs_join_transaction(rc->extent_root);
4293         if (IS_ERR(trans))
4294                 err = PTR_ERR(trans);
4295         else
4296                 err = btrfs_commit_transaction(trans, rc->extent_root);
4297 out_free:
4298         kfree(rc);
4299 out:
4300         if (!list_empty(&reloc_roots))
4301                 free_reloc_roots(&reloc_roots);
4302
4303         btrfs_free_path(path);
4304
4305         if (err == 0) {
4306                 /* cleanup orphan inode in data relocation tree */
4307                 fs_root = read_fs_root(root->fs_info,
4308                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4309                 if (IS_ERR(fs_root))
4310                         err = PTR_ERR(fs_root);
4311                 else
4312                         err = btrfs_orphan_cleanup(fs_root);
4313         }
4314         return err;
4315 }
4316
4317 /*
4318  * helper to add ordered checksum for data relocation.
4319  *
4320  * cloning checksum properly handles the nodatasum extents.
4321  * it also saves CPU time to re-calculate the checksum.
4322  */
4323 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4324 {
4325         struct btrfs_ordered_sum *sums;
4326         struct btrfs_sector_sum *sector_sum;
4327         struct btrfs_ordered_extent *ordered;
4328         struct btrfs_root *root = BTRFS_I(inode)->root;
4329         size_t offset;
4330         int ret;
4331         u64 disk_bytenr;
4332         LIST_HEAD(list);
4333
4334         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4335         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4336
4337         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4338         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4339                                        disk_bytenr + len - 1, &list, 0);
4340         if (ret)
4341                 goto out;
4342
4343         while (!list_empty(&list)) {
4344                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4345                 list_del_init(&sums->list);
4346
4347                 sector_sum = sums->sums;
4348                 sums->bytenr = ordered->start;
4349
4350                 offset = 0;
4351                 while (offset < sums->len) {
4352                         sector_sum->bytenr += ordered->start - disk_bytenr;
4353                         sector_sum++;
4354                         offset += root->sectorsize;
4355                 }
4356
4357                 btrfs_add_ordered_sum(inode, ordered, sums);
4358         }
4359 out:
4360         btrfs_put_ordered_extent(ordered);
4361         return ret;
4362 }
4363
4364 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4365                            struct btrfs_root *root, struct extent_buffer *buf,
4366                            struct extent_buffer *cow)
4367 {
4368         struct reloc_control *rc;
4369         struct backref_node *node;
4370         int first_cow = 0;
4371         int level;
4372         int ret;
4373
4374         rc = root->fs_info->reloc_ctl;
4375         if (!rc)
4376                 return;
4377
4378         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4379                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4380
4381         level = btrfs_header_level(buf);
4382         if (btrfs_header_generation(buf) <=
4383             btrfs_root_last_snapshot(&root->root_item))
4384                 first_cow = 1;
4385
4386         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4387             rc->create_reloc_tree) {
4388                 WARN_ON(!first_cow && level == 0);
4389
4390                 node = rc->backref_cache.path[level];
4391                 BUG_ON(node->bytenr != buf->start &&
4392                        node->new_bytenr != buf->start);
4393
4394                 drop_node_buffer(node);
4395                 extent_buffer_get(cow);
4396                 node->eb = cow;
4397                 node->new_bytenr = cow->start;
4398
4399                 if (!node->pending) {
4400                         list_move_tail(&node->list,
4401                                        &rc->backref_cache.pending[level]);
4402                         node->pending = 1;
4403                 }
4404
4405                 if (first_cow)
4406                         __mark_block_processed(rc, node);
4407
4408                 if (first_cow && level > 0)
4409                         rc->nodes_relocated += buf->len;
4410         }
4411
4412         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4413                 ret = replace_file_extents(trans, rc, root, cow);
4414                 BUG_ON(ret);
4415         }
4416 }
4417
4418 /*
4419  * called before creating snapshot. it calculates metadata reservation
4420  * requried for relocating tree blocks in the snapshot
4421  */
4422 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4423                               struct btrfs_pending_snapshot *pending,
4424                               u64 *bytes_to_reserve)
4425 {
4426         struct btrfs_root *root;
4427         struct reloc_control *rc;
4428
4429         root = pending->root;
4430         if (!root->reloc_root)
4431                 return;
4432
4433         rc = root->fs_info->reloc_ctl;
4434         if (!rc->merge_reloc_tree)
4435                 return;
4436
4437         root = root->reloc_root;
4438         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4439         /*
4440          * relocation is in the stage of merging trees. the space
4441          * used by merging a reloc tree is twice the size of
4442          * relocated tree nodes in the worst case. half for cowing
4443          * the reloc tree, half for cowing the fs tree. the space
4444          * used by cowing the reloc tree will be freed after the
4445          * tree is dropped. if we create snapshot, cowing the fs
4446          * tree may use more space than it frees. so we need
4447          * reserve extra space.
4448          */
4449         *bytes_to_reserve += rc->nodes_relocated;
4450 }
4451
4452 /*
4453  * called after snapshot is created. migrate block reservation
4454  * and create reloc root for the newly created snapshot
4455  */
4456 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4457                                struct btrfs_pending_snapshot *pending)
4458 {
4459         struct btrfs_root *root = pending->root;
4460         struct btrfs_root *reloc_root;
4461         struct btrfs_root *new_root;
4462         struct reloc_control *rc;
4463         int ret;
4464
4465         if (!root->reloc_root)
4466                 return 0;
4467
4468         rc = root->fs_info->reloc_ctl;
4469         rc->merging_rsv_size += rc->nodes_relocated;
4470
4471         if (rc->merge_reloc_tree) {
4472                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4473                                               rc->block_rsv,
4474                                               rc->nodes_relocated);
4475                 if (ret)
4476                         return ret;
4477         }
4478
4479         new_root = pending->snap;
4480         reloc_root = create_reloc_root(trans, root->reloc_root,
4481                                        new_root->root_key.objectid);
4482         if (IS_ERR(reloc_root))
4483                 return PTR_ERR(reloc_root);
4484
4485         ret = __add_reloc_root(reloc_root);
4486         BUG_ON(ret < 0);
4487         new_root->reloc_root = reloc_root;
4488
4489         if (rc->create_reloc_tree)
4490                 ret = clone_backref_node(trans, rc, root, reloc_root);
4491         return ret;
4492 }