fs/btrfs/relocation.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2009 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/writeback.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/rbtree.h>
  11 #include <linux/slab.h>
  12 #include "ctree.h"
  13 #include "disk-io.h"
  14 #include "transaction.h"
  15 #include "volumes.h"
  16 #include "locking.h"
  17 #include "btrfs_inode.h"
  18 #include "async-thread.h"
  19 #include "free-space-cache.h"
  20 #include "inode-map.h"
  21 #include "qgroup.h"
  22 #include "print-tree.h"
  23
  24 /*
  25  * backref_node, mapping_node and tree_block start with this
  26  */
  27 struct tree_entry {
  28         struct rb_node rb_node;
  29         u64 bytenr;
  30 };
  31
  32 /*
  33  * present a tree block in the backref cache
  34  */
  35 struct backref_node {
  36         struct rb_node rb_node;
  37         u64 bytenr;
  38
  39         u64 new_bytenr;
  40         /* objectid of tree block owner, can be not uptodate */
  41         u64 owner;
  42         /* link to pending, changed or detached list */
  43         struct list_head list;
  44         /* list of upper level blocks reference this block */
  45         struct list_head upper;
  46         /* list of child blocks in the cache */
  47         struct list_head lower;
  48         /* NULL if this node is not tree root */
  49         struct btrfs_root *root;
  50         /* extent buffer got by COW the block */
  51         struct extent_buffer *eb;
  52         /* level of tree block */
  53         unsigned int level:8;
  54         /* is the block in non-reference counted tree */
  55         unsigned int cowonly:1;
  56         /* 1 if no child node in the cache */
  57         unsigned int lowest:1;
  58         /* is the extent buffer locked */
  59         unsigned int locked:1;
  60         /* has the block been processed */
  61         unsigned int processed:1;
  62         /* have backrefs of this block been checked */
  63         unsigned int checked:1;
  64         /*
  65          * 1 if corresponding block has been cowed but some upper
  66          * level block pointers may not point to the new location
  67          */
  68         unsigned int pending:1;
  69         /*
  70          * 1 if the backref node isn't connected to any other
  71          * backref node.
  72          */
  73         unsigned int detached:1;
  74 };
  75
  76 /*
  77  * present a block pointer in the backref cache
  78  */
  79 struct backref_edge {
  80         struct list_head list[2];
  81         struct backref_node *node[2];
  82 };
  83
  84 #define LOWER   0
  85 #define UPPER   1
  86 #define RELOCATION_RESERVED_NODES       256
  87
  88 struct backref_cache {
  89         /* red black tree of all backref nodes in the cache */
  90         struct rb_root rb_root;
  91         /* for passing backref nodes to btrfs_reloc_cow_block */
  92         struct backref_node *path[BTRFS_MAX_LEVEL];
  93         /*
  94          * list of blocks that have been cowed but some block
  95          * pointers in upper level blocks may not reflect the
  96          * new location
  97          */
  98         struct list_head pending[BTRFS_MAX_LEVEL];
  99         /* list of backref nodes with no child node */
 100         struct list_head leaves;
 101         /* list of blocks that have been cowed in current transaction */
 102         struct list_head changed;
 103         /* list of detached backref node. */
 104         struct list_head detached;
 105
 106         u64 last_trans;
 107
 108         int nr_nodes;
 109         int nr_edges;
 110 };
 111
 112 /*
 113  * map address of tree root to tree
 114  */
 115 struct mapping_node {
 116         struct rb_node rb_node;
 117         u64 bytenr;
 118         void *data;
 119 };
 120
 121 struct mapping_tree {
 122         struct rb_root rb_root;
 123         spinlock_t lock;
 124 };
 125
 126 /*
 127  * present a tree block to process
 128  */
 129 struct tree_block {
 130         struct rb_node rb_node;
 131         u64 bytenr;
 132         struct btrfs_key key;
 133         unsigned int level:8;
 134         unsigned int key_ready:1;
 135 };
 136
 137 #define MAX_EXTENTS 128
 138
 139 struct file_extent_cluster {
 140         u64 start;
 141         u64 end;
 142         u64 boundary[MAX_EXTENTS];
 143         unsigned int nr;
 144 };
 145
 146 struct reloc_control {
 147         /* block group to relocate */
 148         struct btrfs_block_group_cache *block_group;
 149         /* extent tree */
 150         struct btrfs_root *extent_root;
 151         /* inode for moving data */
 152         struct inode *data_inode;
 153
 154         struct btrfs_block_rsv *block_rsv;
 155
 156         struct backref_cache backref_cache;
 157
 158         struct file_extent_cluster cluster;
 159         /* tree blocks have been processed */
 160         struct extent_io_tree processed_blocks;
 161         /* map start of tree root to corresponding reloc tree */
 162         struct mapping_tree reloc_root_tree;
 163         /* list of reloc trees */
 164         struct list_head reloc_roots;
 165         /* size of metadata reservation for merging reloc trees */
 166         u64 merging_rsv_size;
 167         /* size of relocated tree nodes */
 168         u64 nodes_relocated;
 169         /* reserved size for block group relocation*/
 170         u64 reserved_bytes;
 171
 172         u64 search_start;
 173         u64 extents_found;
 174
 175         unsigned int stage:8;
 176         unsigned int create_reloc_tree:1;
 177         unsigned int merge_reloc_tree:1;
 178         unsigned int found_file_extent:1;
 179 };
 180
 181 /* stages of data relocation */
 182 #define MOVE_DATA_EXTENTS       0
 183 #define UPDATE_DATA_PTRS        1
 184
 185 static void remove_backref_node(struct backref_cache *cache,
 186                                 struct backref_node *node);
 187 static void __mark_block_processed(struct reloc_control *rc,
 188                                    struct backref_node *node);
 189
 190 static void mapping_tree_init(struct mapping_tree *tree)
 191 {
 192         tree->rb_root = RB_ROOT;
 193         spin_lock_init(&tree->lock);
 194 }
 195
 196 static void backref_cache_init(struct backref_cache *cache)
 197 {
 198         int i;
 199         cache->rb_root = RB_ROOT;
 200         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 201                 INIT_LIST_HEAD(&cache->pending[i]);
 202         INIT_LIST_HEAD(&cache->changed);
 203         INIT_LIST_HEAD(&cache->detached);
 204         INIT_LIST_HEAD(&cache->leaves);
 205 }
 206
 207 static void backref_cache_cleanup(struct backref_cache *cache)
 208 {
 209         struct backref_node *node;
 210         int i;
 211
 212         while (!list_empty(&cache->detached)) {
 213                 node = list_entry(cache->detached.next,
 214                                   struct backref_node, list);
 215                 remove_backref_node(cache, node);
 216         }
 217
 218         while (!list_empty(&cache->leaves)) {
 219                 node = list_entry(cache->leaves.next,
 220                                   struct backref_node, lower);
 221                 remove_backref_node(cache, node);
 222         }
 223
 224         cache->last_trans = 0;
 225
 226         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 227                 ASSERT(list_empty(&cache->pending[i]));
 228         ASSERT(list_empty(&cache->changed));
 229         ASSERT(list_empty(&cache->detached));
 230         ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
 231         ASSERT(!cache->nr_nodes);
 232         ASSERT(!cache->nr_edges);
 233 }
 234
 235 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 236 {
 237         struct backref_node *node;
 238
 239         node = kzalloc(sizeof(*node), GFP_NOFS);
 240         if (node) {
 241                 INIT_LIST_HEAD(&node->list);
 242                 INIT_LIST_HEAD(&node->upper);
 243                 INIT_LIST_HEAD(&node->lower);
 244                 RB_CLEAR_NODE(&node->rb_node);
 245                 cache->nr_nodes++;
 246         }
 247         return node;
 248 }
 249
 250 static void free_backref_node(struct backref_cache *cache,
 251                               struct backref_node *node)
 252 {
 253         if (node) {
 254                 cache->nr_nodes--;
 255                 kfree(node);
 256         }
 257 }
 258
 259 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 260 {
 261         struct backref_edge *edge;
 262
 263         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 264         if (edge)
 265                 cache->nr_edges++;
 266         return edge;
 267 }
 268
 269 static void free_backref_edge(struct backref_cache *cache,
 270                               struct backref_edge *edge)
 271 {
 272         if (edge) {
 273                 cache->nr_edges--;
 274                 kfree(edge);
 275         }
 276 }
 277
 278 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 279                                    struct rb_node *node)
 280 {
 281         struct rb_node **p = &root->rb_node;
 282         struct rb_node *parent = NULL;
 283         struct tree_entry *entry;
 284
 285         while (*p) {
 286                 parent = *p;
 287                 entry = rb_entry(parent, struct tree_entry, rb_node);
 288
 289                 if (bytenr < entry->bytenr)
 290                         p = &(*p)->rb_left;
 291                 else if (bytenr > entry->bytenr)
 292                         p = &(*p)->rb_right;
 293                 else
 294                         return parent;
 295         }
 296
 297         rb_link_node(node, parent, p);
 298         rb_insert_color(node, root);
 299         return NULL;
 300 }
 301
 302 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 303 {
 304         struct rb_node *n = root->rb_node;
 305         struct tree_entry *entry;
 306
 307         while (n) {
 308                 entry = rb_entry(n, struct tree_entry, rb_node);
 309
 310                 if (bytenr < entry->bytenr)
 311                         n = n->rb_left;
 312                 else if (bytenr > entry->bytenr)
 313                         n = n->rb_right;
 314                 else
 315                         return n;
 316         }
 317         return NULL;
 318 }
 319
 320 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 321 {
 322
 323         struct btrfs_fs_info *fs_info = NULL;
 324         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 325                                               rb_node);
 326         if (bnode->root)
 327                 fs_info = bnode->root->fs_info;
 328         btrfs_panic(fs_info, errno,
 329                     "Inconsistency in backref cache found at offset %llu",
 330                     bytenr);
 331 }
 332
 333 /*
 334  * walk up backref nodes until reach node presents tree root
 335  */
 336 static struct backref_node *walk_up_backref(struct backref_node *node,
 337                                             struct backref_edge *edges[],
 338                                             int *index)
 339 {
 340         struct backref_edge *edge;
 341         int idx = *index;
 342
 343         while (!list_empty(&node->upper)) {
 344                 edge = list_entry(node->upper.next,
 345                                   struct backref_edge, list[LOWER]);
 346                 edges[idx++] = edge;
 347                 node = edge->node[UPPER];
 348         }
 349         BUG_ON(node->detached);
 350         *index = idx;
 351         return node;
 352 }
 353
 354 /*
 355  * walk down backref nodes to find start of next reference path
 356  */
 357 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 358                                               int *index)
 359 {
 360         struct backref_edge *edge;
 361         struct backref_node *lower;
 362         int idx = *index;
 363
 364         while (idx > 0) {
 365                 edge = edges[idx - 1];
 366                 lower = edge->node[LOWER];
 367                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 368                         idx--;
 369                         continue;
 370                 }
 371                 edge = list_entry(edge->list[LOWER].next,
 372                                   struct backref_edge, list[LOWER]);
 373                 edges[idx - 1] = edge;
 374                 *index = idx;
 375                 return edge->node[UPPER];
 376         }
 377         *index = 0;
 378         return NULL;
 379 }
 380
 381 static void unlock_node_buffer(struct backref_node *node)
 382 {
 383         if (node->locked) {
 384                 btrfs_tree_unlock(node->eb);
 385                 node->locked = 0;
 386         }
 387 }
 388
 389 static void drop_node_buffer(struct backref_node *node)
 390 {
 391         if (node->eb) {
 392                 unlock_node_buffer(node);
 393                 free_extent_buffer(node->eb);
 394                 node->eb = NULL;
 395         }
 396 }
 397
 398 static void drop_backref_node(struct backref_cache *tree,
 399                               struct backref_node *node)
 400 {
 401         BUG_ON(!list_empty(&node->upper));
 402
 403         drop_node_buffer(node);
 404         list_del(&node->list);
 405         list_del(&node->lower);
 406         if (!RB_EMPTY_NODE(&node->rb_node))
 407                 rb_erase(&node->rb_node, &tree->rb_root);
 408         free_backref_node(tree, node);
 409 }
 410
 411 /*
 412  * remove a backref node from the backref cache
 413  */
 414 static void remove_backref_node(struct backref_cache *cache,
 415                                 struct backref_node *node)
 416 {
 417         struct backref_node *upper;
 418         struct backref_edge *edge;
 419
 420         if (!node)
 421                 return;
 422
 423         BUG_ON(!node->lowest && !node->detached);
 424         while (!list_empty(&node->upper)) {
 425                 edge = list_entry(node->upper.next, struct backref_edge,
 426                                   list[LOWER]);
 427                 upper = edge->node[UPPER];
 428                 list_del(&edge->list[LOWER]);
 429                 list_del(&edge->list[UPPER]);
 430                 free_backref_edge(cache, edge);
 431
 432                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 433                         BUG_ON(!list_empty(&node->upper));
 434                         drop_backref_node(cache, node);
 435                         node = upper;
 436                         node->lowest = 1;
 437                         continue;
 438                 }
 439                 /*
 440                  * add the node to leaf node list if no other
 441                  * child block cached.
 442                  */
 443                 if (list_empty(&upper->lower)) {
 444                         list_add_tail(&upper->lower, &cache->leaves);
 445                         upper->lowest = 1;
 446                 }
 447         }
 448
 449         drop_backref_node(cache, node);
 450 }
 451
 452 static void update_backref_node(struct backref_cache *cache,
 453                                 struct backref_node *node, u64 bytenr)
 454 {
 455         struct rb_node *rb_node;
 456         rb_erase(&node->rb_node, &cache->rb_root);
 457         node->bytenr = bytenr;
 458         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 459         if (rb_node)
 460                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 461 }
 462
 463 /*
 464  * update backref cache after a transaction commit
 465  */
 466 static int update_backref_cache(struct btrfs_trans_handle *trans,
 467                                 struct backref_cache *cache)
 468 {
 469         struct backref_node *node;
 470         int level = 0;
 471
 472         if (cache->last_trans == 0) {
 473                 cache->last_trans = trans->transid;
 474                 return 0;
 475         }
 476
 477         if (cache->last_trans == trans->transid)
 478                 return 0;
 479
 480         /*
 481          * detached nodes are used to avoid unnecessary backref
 482          * lookup. transaction commit changes the extent tree.
 483          * so the detached nodes are no longer useful.
 484          */
 485         while (!list_empty(&cache->detached)) {
 486                 node = list_entry(cache->detached.next,
 487                                   struct backref_node, list);
 488                 remove_backref_node(cache, node);
 489         }
 490
 491         while (!list_empty(&cache->changed)) {
 492                 node = list_entry(cache->changed.next,
 493                                   struct backref_node, list);
 494                 list_del_init(&node->list);
 495                 BUG_ON(node->pending);
 496                 update_backref_node(cache, node, node->new_bytenr);
 497         }
 498
 499         /*
 500          * some nodes can be left in the pending list if there were
 501          * errors during processing the pending nodes.
 502          */
 503         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 504                 list_for_each_entry(node, &cache->pending[level], list) {
 505                         BUG_ON(!node->pending);
 506                         if (node->bytenr == node->new_bytenr)
 507                                 continue;
 508                         update_backref_node(cache, node, node->new_bytenr);
 509                 }
 510         }
 511
 512         cache->last_trans = 0;
 513         return 1;
 514 }
 515
 516
 517 static int should_ignore_root(struct btrfs_root *root)
 518 {
 519         struct btrfs_root *reloc_root;
 520
 521         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 522                 return 0;
 523
 524         reloc_root = root->reloc_root;
 525         if (!reloc_root)
 526                 return 0;
 527
 528         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 529             root->fs_info->running_transaction->transid - 1)
 530                 return 0;
 531         /*
 532          * if there is reloc tree and it was created in previous
 533          * transaction backref lookup can find the reloc tree,
 534          * so backref node for the fs tree root is useless for
 535          * relocation.
 536          */
 537         return 1;
 538 }
 539 /*
 540  * find reloc tree by address of tree root
 541  */
 542 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 543                                           u64 bytenr)
 544 {
 545         struct rb_node *rb_node;
 546         struct mapping_node *node;
 547         struct btrfs_root *root = NULL;
 548
 549         spin_lock(&rc->reloc_root_tree.lock);
 550         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 551         if (rb_node) {
 552                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 553                 root = (struct btrfs_root *)node->data;
 554         }
 555         spin_unlock(&rc->reloc_root_tree.lock);
 556         return root;
 557 }
 558
 559 static int is_cowonly_root(u64 root_objectid)
 560 {
 561         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 562             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 563             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 564             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 565             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 566             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 567             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 568             root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
 569             root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
 570                 return 1;
 571         return 0;
 572 }
 573
 574 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 575                                         u64 root_objectid)
 576 {
 577         struct btrfs_key key;
 578
 579         key.objectid = root_objectid;
 580         key.type = BTRFS_ROOT_ITEM_KEY;
 581         if (is_cowonly_root(root_objectid))
 582                 key.offset = 0;
 583         else
 584                 key.offset = (u64)-1;
 585
 586         return btrfs_get_fs_root(fs_info, &key, false);
 587 }
 588
 589 static noinline_for_stack
 590 int find_inline_backref(struct extent_buffer *leaf, int slot,
 591                         unsigned long *ptr, unsigned long *end)
 592 {
 593         struct btrfs_key key;
 594         struct btrfs_extent_item *ei;
 595         struct btrfs_tree_block_info *bi;
 596         u32 item_size;
 597
 598         btrfs_item_key_to_cpu(leaf, &key, slot);
 599
 600         item_size = btrfs_item_size_nr(leaf, slot);
 601         if (item_size < sizeof(*ei)) {
 602                 btrfs_print_v0_err(leaf->fs_info);
 603                 btrfs_handle_fs_error(leaf->fs_info, -EINVAL, NULL);
 604                 return 1;
 605         }
 606         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 607         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 608                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 609
 610         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 611             item_size <= sizeof(*ei) + sizeof(*bi)) {
 612                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 613                 return 1;
 614         }
 615         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 616             item_size <= sizeof(*ei)) {
 617                 WARN_ON(item_size < sizeof(*ei));
 618                 return 1;
 619         }
 620
 621         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 622                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 623                 *ptr = (unsigned long)(bi + 1);
 624         } else {
 625                 *ptr = (unsigned long)(ei + 1);
 626         }
 627         *end = (unsigned long)ei + item_size;
 628         return 0;
 629 }
 630
 631 /*
 632  * build backref tree for a given tree block. root of the backref tree
 633  * corresponds the tree block, leaves of the backref tree correspond
 634  * roots of b-trees that reference the tree block.
 635  *
 636  * the basic idea of this function is check backrefs of a given block
 637  * to find upper level blocks that reference the block, and then check
 638  * backrefs of these upper level blocks recursively. the recursion stop
 639  * when tree root is reached or backrefs for the block is cached.
 640  *
 641  * NOTE: if we find backrefs for a block are cached, we know backrefs
 642  * for all upper level blocks that directly/indirectly reference the
 643  * block are also cached.
 644  */
 645 static noinline_for_stack
 646 struct backref_node *build_backref_tree(struct reloc_control *rc,
 647                                         struct btrfs_key *node_key,
 648                                         int level, u64 bytenr)
 649 {
 650         struct backref_cache *cache = &rc->backref_cache;
 651         struct btrfs_path *path1;
 652         struct btrfs_path *path2;
 653         struct extent_buffer *eb;
 654         struct btrfs_root *root;
 655         struct backref_node *cur;
 656         struct backref_node *upper;
 657         struct backref_node *lower;
 658         struct backref_node *node = NULL;
 659         struct backref_node *exist = NULL;
 660         struct backref_edge *edge;
 661         struct rb_node *rb_node;
 662         struct btrfs_key key;
 663         unsigned long end;
 664         unsigned long ptr;
 665         LIST_HEAD(list);
 666         LIST_HEAD(useless);
 667         int cowonly;
 668         int ret;
 669         int err = 0;
 670         bool need_check = true;
 671
 672         path1 = btrfs_alloc_path();
 673         path2 = btrfs_alloc_path();
 674         if (!path1 || !path2) {
 675                 err = -ENOMEM;
 676                 goto out;
 677         }
 678         path1->reada = READA_FORWARD;
 679         path2->reada = READA_FORWARD;
 680
 681         node = alloc_backref_node(cache);
 682         if (!node) {
 683                 err = -ENOMEM;
 684                 goto out;
 685         }
 686
 687         node->bytenr = bytenr;
 688         node->level = level;
 689         node->lowest = 1;
 690         cur = node;
 691 again:
 692         end = 0;
 693         ptr = 0;
 694         key.objectid = cur->bytenr;
 695         key.type = BTRFS_METADATA_ITEM_KEY;
 696         key.offset = (u64)-1;
 697
 698         path1->search_commit_root = 1;
 699         path1->skip_locking = 1;
 700         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 701                                 0, 0);
 702         if (ret < 0) {
 703                 err = ret;
 704                 goto out;
 705         }
 706         ASSERT(ret);
 707         ASSERT(path1->slots[0]);
 708
 709         path1->slots[0]--;
 710
 711         WARN_ON(cur->checked);
 712         if (!list_empty(&cur->upper)) {
 713                 /*
 714                  * the backref was added previously when processing
 715                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 716                  */
 717                 ASSERT(list_is_singular(&cur->upper));
 718                 edge = list_entry(cur->upper.next, struct backref_edge,
 719                                   list[LOWER]);
 720                 ASSERT(list_empty(&edge->list[UPPER]));
 721                 exist = edge->node[UPPER];
 722                 /*
 723                  * add the upper level block to pending list if we need
 724                  * check its backrefs
 725                  */
 726                 if (!exist->checked)
 727                         list_add_tail(&edge->list[UPPER], &list);
 728         } else {
 729                 exist = NULL;
 730         }
 731
 732         while (1) {
 733                 cond_resched();
 734                 eb = path1->nodes[0];
 735
 736                 if (ptr >= end) {
 737                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 738                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 739                                 if (ret < 0) {
 740                                         err = ret;
 741                                         goto out;
 742                                 }
 743                                 if (ret > 0)
 744                                         break;
 745                                 eb = path1->nodes[0];
 746                         }
 747
 748                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 749                         if (key.objectid != cur->bytenr) {
 750                                 WARN_ON(exist);
 751                                 break;
 752                         }
 753
 754                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 755                             key.type == BTRFS_METADATA_ITEM_KEY) {
 756                                 ret = find_inline_backref(eb, path1->slots[0],
 757                                                           &ptr, &end);
 758                                 if (ret)
 759                                         goto next;
 760                         }
 761                 }
 762
 763                 if (ptr < end) {
 764                         /* update key for inline back ref */
 765                         struct btrfs_extent_inline_ref *iref;
 766                         int type;
 767                         iref = (struct btrfs_extent_inline_ref *)ptr;
 768                         type = btrfs_get_extent_inline_ref_type(eb, iref,
 769                                                         BTRFS_REF_TYPE_BLOCK);
 770                         if (type == BTRFS_REF_TYPE_INVALID) {
 771                                 err = -EUCLEAN;
 772                                 goto out;
 773                         }
 774                         key.type = type;
 775                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 776
 777                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 778                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 779                 }
 780
 781                 if (exist &&
 782                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 783                       exist->owner == key.offset) ||
 784                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 785                       exist->bytenr == key.offset))) {
 786                         exist = NULL;
 787                         goto next;
 788                 }
 789
 790                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 791                         if (key.objectid == key.offset) {
 792                                 /*
 793                                  * only root blocks of reloc trees use
 794                                  * backref of this type.
 795                                  */
 796                                 root = find_reloc_root(rc, cur->bytenr);
 797                                 ASSERT(root);
 798                                 cur->root = root;
 799                                 break;
 800                         }
 801
 802                         edge = alloc_backref_edge(cache);
 803                         if (!edge) {
 804                                 err = -ENOMEM;
 805                                 goto out;
 806                         }
 807                         rb_node = tree_search(&cache->rb_root, key.offset);
 808                         if (!rb_node) {
 809                                 upper = alloc_backref_node(cache);
 810                                 if (!upper) {
 811                                         free_backref_edge(cache, edge);
 812                                         err = -ENOMEM;
 813                                         goto out;
 814                                 }
 815                                 upper->bytenr = key.offset;
 816                                 upper->level = cur->level + 1;
 817                                 /*
 818                                  *  backrefs for the upper level block isn't
 819                                  *  cached, add the block to pending list
 820                                  */
 821                                 list_add_tail(&edge->list[UPPER], &list);
 822                         } else {
 823                                 upper = rb_entry(rb_node, struct backref_node,
 824                                                  rb_node);
 825                                 ASSERT(upper->checked);
 826                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 827                         }
 828                         list_add_tail(&edge->list[LOWER], &cur->upper);
 829                         edge->node[LOWER] = cur;
 830                         edge->node[UPPER] = upper;
 831
 832                         goto next;
 833                 } else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 834                         err = -EINVAL;
 835                         btrfs_print_v0_err(rc->extent_root->fs_info);
 836                         btrfs_handle_fs_error(rc->extent_root->fs_info, err,
 837                                               NULL);
 838                         goto out;
 839                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 840                         goto next;
 841                 }
 842
 843                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 844                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 845                 if (IS_ERR(root)) {
 846                         err = PTR_ERR(root);
 847                         goto out;
 848                 }
 849
 850                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 851                         cur->cowonly = 1;
 852
 853                 if (btrfs_root_level(&root->root_item) == cur->level) {
 854                         /* tree root */
 855                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
 856                                cur->bytenr);
 857                         if (should_ignore_root(root))
 858                                 list_add(&cur->list, &useless);
 859                         else
 860                                 cur->root = root;
 861                         break;
 862                 }
 863
 864                 level = cur->level + 1;
 865
 866                 /*
 867                  * searching the tree to find upper level blocks
 868                  * reference the block.
 869                  */
 870                 path2->search_commit_root = 1;
 871                 path2->skip_locking = 1;
 872                 path2->lowest_level = level;
 873                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 874                 path2->lowest_level = 0;
 875                 if (ret < 0) {
 876                         err = ret;
 877                         goto out;
 878                 }
 879                 if (ret > 0 && path2->slots[level] > 0)
 880                         path2->slots[level]--;
 881
 882                 eb = path2->nodes[level];
 883                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
 884                     cur->bytenr) {
 885                         btrfs_err(root->fs_info,
 886         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
 887                                   cur->bytenr, level - 1, root->objectid,
 888                                   node_key->objectid, node_key->type,
 889                                   node_key->offset);
 890                         err = -ENOENT;
 891                         goto out;
 892                 }
 893                 lower = cur;
 894                 need_check = true;
 895                 for (; level < BTRFS_MAX_LEVEL; level++) {
 896                         if (!path2->nodes[level]) {
 897                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
 898                                        lower->bytenr);
 899                                 if (should_ignore_root(root))
 900                                         list_add(&lower->list, &useless);
 901                                 else
 902                                         lower->root = root;
 903                                 break;
 904                         }
 905
 906                         edge = alloc_backref_edge(cache);
 907                         if (!edge) {
 908                                 err = -ENOMEM;
 909                                 goto out;
 910                         }
 911
 912                         eb = path2->nodes[level];
 913                         rb_node = tree_search(&cache->rb_root, eb->start);
 914                         if (!rb_node) {
 915                                 upper = alloc_backref_node(cache);
 916                                 if (!upper) {
 917                                         free_backref_edge(cache, edge);
 918                                         err = -ENOMEM;
 919                                         goto out;
 920                                 }
 921                                 upper->bytenr = eb->start;
 922                                 upper->owner = btrfs_header_owner(eb);
 923                                 upper->level = lower->level + 1;
 924                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 925                                               &root->state))
 926                                         upper->cowonly = 1;
 927
 928                                 /*
 929                                  * if we know the block isn't shared
 930                                  * we can void checking its backrefs.
 931                                  */
 932                                 if (btrfs_block_can_be_shared(root, eb))
 933                                         upper->checked = 0;
 934                                 else
 935                                         upper->checked = 1;
 936
 937                                 /*
 938                                  * add the block to pending list if we
 939                                  * need check its backrefs, we only do this once
 940                                  * while walking up a tree as we will catch
 941                                  * anything else later on.
 942                                  */
 943                                 if (!upper->checked && need_check) {
 944                                         need_check = false;
 945                                         list_add_tail(&edge->list[UPPER],
 946                                                       &list);
 947                                 } else {
 948                                         if (upper->checked)
 949                                                 need_check = true;
 950                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 951                                 }
 952                         } else {
 953                                 upper = rb_entry(rb_node, struct backref_node,
 954                                                  rb_node);
 955                                 ASSERT(upper->checked);
 956                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 957                                 if (!upper->owner)
 958                                         upper->owner = btrfs_header_owner(eb);
 959                         }
 960                         list_add_tail(&edge->list[LOWER], &lower->upper);
 961                         edge->node[LOWER] = lower;
 962                         edge->node[UPPER] = upper;
 963
 964                         if (rb_node)
 965                                 break;
 966                         lower = upper;
 967                         upper = NULL;
 968                 }
 969                 btrfs_release_path(path2);
 970 next:
 971                 if (ptr < end) {
 972                         ptr += btrfs_extent_inline_ref_size(key.type);
 973                         if (ptr >= end) {
 974                                 WARN_ON(ptr > end);
 975                                 ptr = 0;
 976                                 end = 0;
 977                         }
 978                 }
 979                 if (ptr >= end)
 980                         path1->slots[0]++;
 981         }
 982         btrfs_release_path(path1);
 983
 984         cur->checked = 1;
 985         WARN_ON(exist);
 986
 987         /* the pending list isn't empty, take the first block to process */
 988         if (!list_empty(&list)) {
 989                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 990                 list_del_init(&edge->list[UPPER]);
 991                 cur = edge->node[UPPER];
 992                 goto again;
 993         }
 994
 995         /*
 996          * everything goes well, connect backref nodes and insert backref nodes
 997          * into the cache.
 998          */
 999         ASSERT(node->checked);
1000         cowonly = node->cowonly;
1001         if (!cowonly) {
1002                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1003                                       &node->rb_node);
1004                 if (rb_node)
1005                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1006                 list_add_tail(&node->lower, &cache->leaves);
1007         }
1008
1009         list_for_each_entry(edge, &node->upper, list[LOWER])
1010                 list_add_tail(&edge->list[UPPER], &list);
1011
1012         while (!list_empty(&list)) {
1013                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1014                 list_del_init(&edge->list[UPPER]);
1015                 upper = edge->node[UPPER];
1016                 if (upper->detached) {
1017                         list_del(&edge->list[LOWER]);
1018                         lower = edge->node[LOWER];
1019                         free_backref_edge(cache, edge);
1020                         if (list_empty(&lower->upper))
1021                                 list_add(&lower->list, &useless);
1022                         continue;
1023                 }
1024
1025                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1026                         if (upper->lowest) {
1027                                 list_del_init(&upper->lower);
1028                                 upper->lowest = 0;
1029                         }
1030
1031                         list_add_tail(&edge->list[UPPER], &upper->lower);
1032                         continue;
1033                 }
1034
1035                 if (!upper->checked) {
1036                         /*
1037                          * Still want to blow up for developers since this is a
1038                          * logic bug.
1039                          */
1040                         ASSERT(0);
1041                         err = -EINVAL;
1042                         goto out;
1043                 }
1044                 if (cowonly != upper->cowonly) {
1045                         ASSERT(0);
1046                         err = -EINVAL;
1047                         goto out;
1048                 }
1049
1050                 if (!cowonly) {
1051                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1052                                               &upper->rb_node);
1053                         if (rb_node)
1054                                 backref_tree_panic(rb_node, -EEXIST,
1055                                                    upper->bytenr);
1056                 }
1057
1058                 list_add_tail(&edge->list[UPPER], &upper->lower);
1059
1060                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1061                         list_add_tail(&edge->list[UPPER], &list);
1062         }
1063         /*
1064          * process useless backref nodes. backref nodes for tree leaves
1065          * are deleted from the cache. backref nodes for upper level
1066          * tree blocks are left in the cache to avoid unnecessary backref
1067          * lookup.
1068          */
1069         while (!list_empty(&useless)) {
1070                 upper = list_entry(useless.next, struct backref_node, list);
1071                 list_del_init(&upper->list);
1072                 ASSERT(list_empty(&upper->upper));
1073                 if (upper == node)
1074                         node = NULL;
1075                 if (upper->lowest) {
1076                         list_del_init(&upper->lower);
1077                         upper->lowest = 0;
1078                 }
1079                 while (!list_empty(&upper->lower)) {
1080                         edge = list_entry(upper->lower.next,
1081                                           struct backref_edge, list[UPPER]);
1082                         list_del(&edge->list[UPPER]);
1083                         list_del(&edge->list[LOWER]);
1084                         lower = edge->node[LOWER];
1085                         free_backref_edge(cache, edge);
1086
1087                         if (list_empty(&lower->upper))
1088                                 list_add(&lower->list, &useless);
1089                 }
1090                 __mark_block_processed(rc, upper);
1091                 if (upper->level > 0) {
1092                         list_add(&upper->list, &cache->detached);
1093                         upper->detached = 1;
1094                 } else {
1095                         rb_erase(&upper->rb_node, &cache->rb_root);
1096                         free_backref_node(cache, upper);
1097                 }
1098         }
1099 out:
1100         btrfs_free_path(path1);
1101         btrfs_free_path(path2);
1102         if (err) {
1103                 while (!list_empty(&useless)) {
1104                         lower = list_entry(useless.next,
1105                                            struct backref_node, list);
1106                         list_del_init(&lower->list);
1107                 }
1108                 while (!list_empty(&list)) {
1109                         edge = list_first_entry(&list, struct backref_edge,
1110                                                 list[UPPER]);
1111                         list_del(&edge->list[UPPER]);
1112                         list_del(&edge->list[LOWER]);
1113                         lower = edge->node[LOWER];
1114                         upper = edge->node[UPPER];
1115                         free_backref_edge(cache, edge);
1116
1117                         /*
1118                          * Lower is no longer linked to any upper backref nodes
1119                          * and isn't in the cache, we can free it ourselves.
1120                          */
1121                         if (list_empty(&lower->upper) &&
1122                             RB_EMPTY_NODE(&lower->rb_node))
1123                                 list_add(&lower->list, &useless);
1124
1125                         if (!RB_EMPTY_NODE(&upper->rb_node))
1126                                 continue;
1127
1128                         /* Add this guy's upper edges to the list to process */
1129                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1130                                 list_add_tail(&edge->list[UPPER], &list);
1131                         if (list_empty(&upper->upper))
1132                                 list_add(&upper->list, &useless);
1133                 }
1134
1135                 while (!list_empty(&useless)) {
1136                         lower = list_entry(useless.next,
1137                                            struct backref_node, list);
1138                         list_del_init(&lower->list);
1139                         if (lower == node)
1140                                 node = NULL;
1141                         free_backref_node(cache, lower);
1142                 }
1143
1144                 free_backref_node(cache, node);
1145                 return ERR_PTR(err);
1146         }
1147         ASSERT(!node || !node->detached);
1148         return node;
1149 }
1150
1151 /*
1152  * helper to add backref node for the newly created snapshot.
1153  * the backref node is created by cloning backref node that
1154  * corresponds to root of source tree
1155  */
1156 static int clone_backref_node(struct btrfs_trans_handle *trans,
1157                               struct reloc_control *rc,
1158                               struct btrfs_root *src,
1159                               struct btrfs_root *dest)
1160 {
1161         struct btrfs_root *reloc_root = src->reloc_root;
1162         struct backref_cache *cache = &rc->backref_cache;
1163         struct backref_node *node = NULL;
1164         struct backref_node *new_node;
1165         struct backref_edge *edge;
1166         struct backref_edge *new_edge;
1167         struct rb_node *rb_node;
1168
1169         if (cache->last_trans > 0)
1170                 update_backref_cache(trans, cache);
1171
1172         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1173         if (rb_node) {
1174                 node = rb_entry(rb_node, struct backref_node, rb_node);
1175                 if (node->detached)
1176                         node = NULL;
1177                 else
1178                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1179         }
1180
1181         if (!node) {
1182                 rb_node = tree_search(&cache->rb_root,
1183                                       reloc_root->commit_root->start);
1184                 if (rb_node) {
1185                         node = rb_entry(rb_node, struct backref_node,
1186                                         rb_node);
1187                         BUG_ON(node->detached);
1188                 }
1189         }
1190
1191         if (!node)
1192                 return 0;
1193
1194         new_node = alloc_backref_node(cache);
1195         if (!new_node)
1196                 return -ENOMEM;
1197
1198         new_node->bytenr = dest->node->start;
1199         new_node->level = node->level;
1200         new_node->lowest = node->lowest;
1201         new_node->checked = 1;
1202         new_node->root = dest;
1203
1204         if (!node->lowest) {
1205                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1206                         new_edge = alloc_backref_edge(cache);
1207                         if (!new_edge)
1208                                 goto fail;
1209
1210                         new_edge->node[UPPER] = new_node;
1211                         new_edge->node[LOWER] = edge->node[LOWER];
1212                         list_add_tail(&new_edge->list[UPPER],
1213                                       &new_node->lower);
1214                 }
1215         } else {
1216                 list_add_tail(&new_node->lower, &cache->leaves);
1217         }
1218
1219         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1220                               &new_node->rb_node);
1221         if (rb_node)
1222                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1223
1224         if (!new_node->lowest) {
1225                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1226                         list_add_tail(&new_edge->list[LOWER],
1227                                       &new_edge->node[LOWER]->upper);
1228                 }
1229         }
1230         return 0;
1231 fail:
1232         while (!list_empty(&new_node->lower)) {
1233                 new_edge = list_entry(new_node->lower.next,
1234                                       struct backref_edge, list[UPPER]);
1235                 list_del(&new_edge->list[UPPER]);
1236                 free_backref_edge(cache, new_edge);
1237         }
1238         free_backref_node(cache, new_node);
1239         return -ENOMEM;
1240 }
1241
1242 /*
1243  * helper to add 'address of tree root -> reloc tree' mapping
1244  */
1245 static int __must_check __add_reloc_root(struct btrfs_root *root)
1246 {
1247         struct btrfs_fs_info *fs_info = root->fs_info;
1248         struct rb_node *rb_node;
1249         struct mapping_node *node;
1250         struct reloc_control *rc = fs_info->reloc_ctl;
1251
1252         node = kmalloc(sizeof(*node), GFP_NOFS);
1253         if (!node)
1254                 return -ENOMEM;
1255
1256         node->bytenr = root->node->start;
1257         node->data = root;
1258
1259         spin_lock(&rc->reloc_root_tree.lock);
1260         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1261                               node->bytenr, &node->rb_node);
1262         spin_unlock(&rc->reloc_root_tree.lock);
1263         if (rb_node) {
1264                 btrfs_panic(fs_info, -EEXIST,
1265                             "Duplicate root found for start=%llu while inserting into relocation tree",
1266                             node->bytenr);
1267         }
1268
1269         list_add_tail(&root->root_list, &rc->reloc_roots);
1270         return 0;
1271 }
1272
1273 /*
1274  * helper to delete the 'address of tree root -> reloc tree'
1275  * mapping
1276  */
1277 static void __del_reloc_root(struct btrfs_root *root)
1278 {
1279         struct btrfs_fs_info *fs_info = root->fs_info;
1280         struct rb_node *rb_node;
1281         struct mapping_node *node = NULL;
1282         struct reloc_control *rc = fs_info->reloc_ctl;
1283
1284         spin_lock(&rc->reloc_root_tree.lock);
1285         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1286                               root->node->start);
1287         if (rb_node) {
1288                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1289                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1290         }
1291         spin_unlock(&rc->reloc_root_tree.lock);
1292
1293         if (!node)
1294                 return;
1295         BUG_ON((struct btrfs_root *)node->data != root);
1296
1297         spin_lock(&fs_info->trans_lock);
1298         list_del_init(&root->root_list);
1299         spin_unlock(&fs_info->trans_lock);
1300         kfree(node);
1301 }
1302
1303 /*
1304  * helper to update the 'address of tree root -> reloc tree'
1305  * mapping
1306  */
1307 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1308 {
1309         struct btrfs_fs_info *fs_info = root->fs_info;
1310         struct rb_node *rb_node;
1311         struct mapping_node *node = NULL;
1312         struct reloc_control *rc = fs_info->reloc_ctl;
1313
1314         spin_lock(&rc->reloc_root_tree.lock);
1315         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1316                               root->node->start);
1317         if (rb_node) {
1318                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1319                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1320         }
1321         spin_unlock(&rc->reloc_root_tree.lock);
1322
1323         if (!node)
1324                 return 0;
1325         BUG_ON((struct btrfs_root *)node->data != root);
1326
1327         spin_lock(&rc->reloc_root_tree.lock);
1328         node->bytenr = new_bytenr;
1329         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1330                               node->bytenr, &node->rb_node);
1331         spin_unlock(&rc->reloc_root_tree.lock);
1332         if (rb_node)
1333                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1334         return 0;
1335 }
1336
1337 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1338                                         struct btrfs_root *root, u64 objectid)
1339 {
1340         struct btrfs_fs_info *fs_info = root->fs_info;
1341         struct btrfs_root *reloc_root;
1342         struct extent_buffer *eb;
1343         struct btrfs_root_item *root_item;
1344         struct btrfs_key root_key;
1345         int ret;
1346
1347         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1348         BUG_ON(!root_item);
1349
1350         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1351         root_key.type = BTRFS_ROOT_ITEM_KEY;
1352         root_key.offset = objectid;
1353
1354         if (root->root_key.objectid == objectid) {
1355                 u64 commit_root_gen;
1356
1357                 /* called by btrfs_init_reloc_root */
1358                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1359                                       BTRFS_TREE_RELOC_OBJECTID);
1360                 BUG_ON(ret);
1361                 /*
1362                  * Set the last_snapshot field to the generation of the commit
1363                  * root - like this ctree.c:btrfs_block_can_be_shared() behaves
1364                  * correctly (returns true) when the relocation root is created
1365                  * either inside the critical section of a transaction commit
1366                  * (through transaction.c:qgroup_account_snapshot()) and when
1367                  * it's created before the transaction commit is started.
1368                  */
1369                 commit_root_gen = btrfs_header_generation(root->commit_root);
1370                 btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
1371         } else {
1372                 /*
1373                  * called by btrfs_reloc_post_snapshot_hook.
1374                  * the source tree is a reloc tree, all tree blocks
1375                  * modified after it was created have RELOC flag
1376                  * set in their headers. so it's OK to not update
1377                  * the 'last_snapshot'.
1378                  */
1379                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1380                                       BTRFS_TREE_RELOC_OBJECTID);
1381                 BUG_ON(ret);
1382         }
1383
1384         memcpy(root_item, &root->root_item, sizeof(*root_item));
1385         btrfs_set_root_bytenr(root_item, eb->start);
1386         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1387         btrfs_set_root_generation(root_item, trans->transid);
1388
1389         if (root->root_key.objectid == objectid) {
1390                 btrfs_set_root_refs(root_item, 0);
1391                 memset(&root_item->drop_progress, 0,
1392                        sizeof(struct btrfs_disk_key));
1393                 root_item->drop_level = 0;
1394         }
1395
1396         btrfs_tree_unlock(eb);
1397         free_extent_buffer(eb);
1398
1399         ret = btrfs_insert_root(trans, fs_info->tree_root,
1400                                 &root_key, root_item);
1401         BUG_ON(ret);
1402         kfree(root_item);
1403
1404         reloc_root = btrfs_read_fs_root(fs_info->tree_root, &root_key);
1405         BUG_ON(IS_ERR(reloc_root));
1406         reloc_root->last_trans = trans->transid;
1407         return reloc_root;
1408 }
1409
1410 /*
1411  * create reloc tree for a given fs tree. reloc tree is just a
1412  * snapshot of the fs tree with special root objectid.
1413  */
1414 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1415                           struct btrfs_root *root)
1416 {
1417         struct btrfs_fs_info *fs_info = root->fs_info;
1418         struct btrfs_root *reloc_root;
1419         struct reloc_control *rc = fs_info->reloc_ctl;
1420         struct btrfs_block_rsv *rsv;
1421         int clear_rsv = 0;
1422         int ret;
1423
1424         if (root->reloc_root) {
1425                 reloc_root = root->reloc_root;
1426                 reloc_root->last_trans = trans->transid;
1427                 return 0;
1428         }
1429
1430         if (!rc || !rc->create_reloc_tree ||
1431             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1432                 return 0;
1433
1434         if (!trans->reloc_reserved) {
1435                 rsv = trans->block_rsv;
1436                 trans->block_rsv = rc->block_rsv;
1437                 clear_rsv = 1;
1438         }
1439         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1440         if (clear_rsv)
1441                 trans->block_rsv = rsv;
1442
1443         ret = __add_reloc_root(reloc_root);
1444         BUG_ON(ret < 0);
1445         root->reloc_root = reloc_root;
1446         return 0;
1447 }
1448
1449 /*
1450  * update root item of reloc tree
1451  */
1452 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1453                             struct btrfs_root *root)
1454 {
1455         struct btrfs_fs_info *fs_info = root->fs_info;
1456         struct btrfs_root *reloc_root;
1457         struct btrfs_root_item *root_item;
1458         int ret;
1459
1460         if (!root->reloc_root)
1461                 goto out;
1462
1463         reloc_root = root->reloc_root;
1464         root_item = &reloc_root->root_item;
1465
1466         if (fs_info->reloc_ctl->merge_reloc_tree &&
1467             btrfs_root_refs(root_item) == 0) {
1468                 root->reloc_root = NULL;
1469                 __del_reloc_root(reloc_root);
1470         }
1471
1472         if (reloc_root->commit_root != reloc_root->node) {
1473                 btrfs_set_root_node(root_item, reloc_root->node);
1474                 free_extent_buffer(reloc_root->commit_root);
1475                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1476         }
1477
1478         ret = btrfs_update_root(trans, fs_info->tree_root,
1479                                 &reloc_root->root_key, root_item);
1480         BUG_ON(ret);
1481
1482 out:
1483         return 0;
1484 }
1485
1486 /*
1487  * helper to find first cached inode with inode number >= objectid
1488  * in a subvolume
1489  */
1490 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1491 {
1492         struct rb_node *node;
1493         struct rb_node *prev;
1494         struct btrfs_inode *entry;
1495         struct inode *inode;
1496
1497         spin_lock(&root->inode_lock);
1498 again:
1499         node = root->inode_tree.rb_node;
1500         prev = NULL;
1501         while (node) {
1502                 prev = node;
1503                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1504
1505                 if (objectid < btrfs_ino(entry))
1506                         node = node->rb_left;
1507                 else if (objectid > btrfs_ino(entry))
1508                         node = node->rb_right;
1509                 else
1510                         break;
1511         }
1512         if (!node) {
1513                 while (prev) {
1514                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1515                         if (objectid <= btrfs_ino(entry)) {
1516                                 node = prev;
1517                                 break;
1518                         }
1519                         prev = rb_next(prev);
1520                 }
1521         }
1522         while (node) {
1523                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1524                 inode = igrab(&entry->vfs_inode);
1525                 if (inode) {
1526                         spin_unlock(&root->inode_lock);
1527                         return inode;
1528                 }
1529
1530                 objectid = btrfs_ino(entry) + 1;
1531                 if (cond_resched_lock(&root->inode_lock))
1532                         goto again;
1533
1534                 node = rb_next(node);
1535         }
1536         spin_unlock(&root->inode_lock);
1537         return NULL;
1538 }
1539
1540 static int in_block_group(u64 bytenr,
1541                           struct btrfs_block_group_cache *block_group)
1542 {
1543         if (bytenr >= block_group->key.objectid &&
1544             bytenr < block_group->key.objectid + block_group->key.offset)
1545                 return 1;
1546         return 0;
1547 }
1548
1549 /*
1550  * get new location of data
1551  */
1552 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1553                             u64 bytenr, u64 num_bytes)
1554 {
1555         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1556         struct btrfs_path *path;
1557         struct btrfs_file_extent_item *fi;
1558         struct extent_buffer *leaf;
1559         int ret;
1560
1561         path = btrfs_alloc_path();
1562         if (!path)
1563                 return -ENOMEM;
1564
1565         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1566         ret = btrfs_lookup_file_extent(NULL, root, path,
1567                         btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);
1568         if (ret < 0)
1569                 goto out;
1570         if (ret > 0) {
1571                 ret = -ENOENT;
1572                 goto out;
1573         }
1574
1575         leaf = path->nodes[0];
1576         fi = btrfs_item_ptr(leaf, path->slots[0],
1577                             struct btrfs_file_extent_item);
1578
1579         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1580                btrfs_file_extent_compression(leaf, fi) ||
1581                btrfs_file_extent_encryption(leaf, fi) ||
1582                btrfs_file_extent_other_encoding(leaf, fi));
1583
1584         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1585                 ret = -EINVAL;
1586                 goto out;
1587         }
1588
1589         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1590         ret = 0;
1591 out:
1592         btrfs_free_path(path);
1593         return ret;
1594 }
1595
1596 /*
1597  * update file extent items in the tree leaf to point to
1598  * the new locations.
1599  */
1600 static noinline_for_stack
1601 int replace_file_extents(struct btrfs_trans_handle *trans,
1602                          struct reloc_control *rc,
1603                          struct btrfs_root *root,
1604                          struct extent_buffer *leaf)
1605 {
1606         struct btrfs_fs_info *fs_info = root->fs_info;
1607         struct btrfs_key key;
1608         struct btrfs_file_extent_item *fi;
1609         struct inode *inode = NULL;
1610         u64 parent;
1611         u64 bytenr;
1612         u64 new_bytenr = 0;
1613         u64 num_bytes;
1614         u64 end;
1615         u32 nritems;
1616         u32 i;
1617         int ret = 0;
1618         int first = 1;
1619         int dirty = 0;
1620
1621         if (rc->stage != UPDATE_DATA_PTRS)
1622                 return 0;
1623
1624         /* reloc trees always use full backref */
1625         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1626                 parent = leaf->start;
1627         else
1628                 parent = 0;
1629
1630         nritems = btrfs_header_nritems(leaf);
1631         for (i = 0; i < nritems; i++) {
1632                 cond_resched();
1633                 btrfs_item_key_to_cpu(leaf, &key, i);
1634                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1635                         continue;
1636                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1637                 if (btrfs_file_extent_type(leaf, fi) ==
1638                     BTRFS_FILE_EXTENT_INLINE)
1639                         continue;
1640                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1641                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1642                 if (bytenr == 0)
1643                         continue;
1644                 if (!in_block_group(bytenr, rc->block_group))
1645                         continue;
1646
1647                 /*
1648                  * if we are modifying block in fs tree, wait for readpage
1649                  * to complete and drop the extent cache
1650                  */
1651                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1652                         if (first) {
1653                                 inode = find_next_inode(root, key.objectid);
1654                                 first = 0;
1655                         } else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
1656                                 btrfs_add_delayed_iput(inode);
1657                                 inode = find_next_inode(root, key.objectid);
1658                         }
1659                         if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
1660                                 end = key.offset +
1661                                       btrfs_file_extent_num_bytes(leaf, fi);
1662                                 WARN_ON(!IS_ALIGNED(key.offset,
1663                                                     fs_info->sectorsize));
1664                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
1665                                 end--;
1666                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1667                                                       key.offset, end);
1668                                 if (!ret)
1669                                         continue;
1670
1671                                 btrfs_drop_extent_cache(BTRFS_I(inode),
1672                                                 key.offset,     end, 1);
1673                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1674                                               key.offset, end);
1675                         }
1676                 }
1677
1678                 ret = get_new_location(rc->data_inode, &new_bytenr,
1679                                        bytenr, num_bytes);
1680                 if (ret) {
1681                         /*
1682                          * Don't have to abort since we've not changed anything
1683                          * in the file extent yet.
1684                          */
1685                         break;
1686                 }
1687
1688                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1689                 dirty = 1;
1690
1691                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1692                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1693                                            num_bytes, parent,
1694                                            btrfs_header_owner(leaf),
1695                                            key.objectid, key.offset);
1696                 if (ret) {
1697                         btrfs_abort_transaction(trans, ret);
1698                         break;
1699                 }
1700
1701                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1702                                         parent, btrfs_header_owner(leaf),
1703                                         key.objectid, key.offset);
1704                 if (ret) {
1705                         btrfs_abort_transaction(trans, ret);
1706                         break;
1707                 }
1708         }
1709         if (dirty)
1710                 btrfs_mark_buffer_dirty(leaf);
1711         if (inode)
1712                 btrfs_add_delayed_iput(inode);
1713         return ret;
1714 }
1715
1716 static noinline_for_stack
1717 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1718                      struct btrfs_path *path, int level)
1719 {
1720         struct btrfs_disk_key key1;
1721         struct btrfs_disk_key key2;
1722         btrfs_node_key(eb, &key1, slot);
1723         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1724         return memcmp(&key1, &key2, sizeof(key1));
1725 }
1726
1727 /*
1728  * try to replace tree blocks in fs tree with the new blocks
1729  * in reloc tree. tree blocks haven't been modified since the
1730  * reloc tree was create can be replaced.
1731  *
1732  * if a block was replaced, level of the block + 1 is returned.
1733  * if no block got replaced, 0 is returned. if there are other
1734  * errors, a negative error number is returned.
1735  */
1736 static noinline_for_stack
1737 int replace_path(struct btrfs_trans_handle *trans,
1738                  struct btrfs_root *dest, struct btrfs_root *src,
1739                  struct btrfs_path *path, struct btrfs_key *next_key,
1740                  int lowest_level, int max_level)
1741 {
1742         struct btrfs_fs_info *fs_info = dest->fs_info;
1743         struct extent_buffer *eb;
1744         struct extent_buffer *parent;
1745         struct btrfs_key key;
1746         u64 old_bytenr;
1747         u64 new_bytenr;
1748         u64 old_ptr_gen;
1749         u64 new_ptr_gen;
1750         u64 last_snapshot;
1751         u32 blocksize;
1752         int cow = 0;
1753         int level;
1754         int ret;
1755         int slot;
1756
1757         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1758         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1759
1760         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1761 again:
1762         slot = path->slots[lowest_level];
1763         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1764
1765         eb = btrfs_lock_root_node(dest);
1766         btrfs_set_lock_blocking(eb);
1767         level = btrfs_header_level(eb);
1768
1769         if (level < lowest_level) {
1770                 btrfs_tree_unlock(eb);
1771                 free_extent_buffer(eb);
1772                 return 0;
1773         }
1774
1775         if (cow) {
1776                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1777                 BUG_ON(ret);
1778         }
1779         btrfs_set_lock_blocking(eb);
1780
1781         if (next_key) {
1782                 next_key->objectid = (u64)-1;
1783                 next_key->type = (u8)-1;
1784                 next_key->offset = (u64)-1;
1785         }
1786
1787         parent = eb;
1788         while (1) {
1789                 struct btrfs_key first_key;
1790
1791                 level = btrfs_header_level(parent);
1792                 BUG_ON(level < lowest_level);
1793
1794                 ret = btrfs_bin_search(parent, &key, level, &slot);
1795                 if (ret && slot > 0)
1796                         slot--;
1797
1798                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1799                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1800
1801                 old_bytenr = btrfs_node_blockptr(parent, slot);
1802                 blocksize = fs_info->nodesize;
1803                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1804                 btrfs_node_key_to_cpu(parent, &first_key, slot);
1805
1806                 if (level <= max_level) {
1807                         eb = path->nodes[level];
1808                         new_bytenr = btrfs_node_blockptr(eb,
1809                                                         path->slots[level]);
1810                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1811                                                         path->slots[level]);
1812                 } else {
1813                         new_bytenr = 0;
1814                         new_ptr_gen = 0;
1815                 }
1816
1817                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1818                         ret = level;
1819                         break;
1820                 }
1821
1822                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1823                     memcmp_node_keys(parent, slot, path, level)) {
1824                         if (level <= lowest_level) {
1825                                 ret = 0;
1826                                 break;
1827                         }
1828
1829                         eb = read_tree_block(fs_info, old_bytenr, old_ptr_gen,
1830                                              level - 1, &first_key);
1831                         if (IS_ERR(eb)) {
1832                                 ret = PTR_ERR(eb);
1833                                 break;
1834                         } else if (!extent_buffer_uptodate(eb)) {
1835                                 ret = -EIO;
1836                                 free_extent_buffer(eb);
1837                                 break;
1838                         }
1839                         btrfs_tree_lock(eb);
1840                         if (cow) {
1841                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1842                                                       slot, &eb);
1843                                 BUG_ON(ret);
1844                         }
1845                         btrfs_set_lock_blocking(eb);
1846
1847                         btrfs_tree_unlock(parent);
1848                         free_extent_buffer(parent);
1849
1850                         parent = eb;
1851                         continue;
1852                 }
1853
1854                 if (!cow) {
1855                         btrfs_tree_unlock(parent);
1856                         free_extent_buffer(parent);
1857                         cow = 1;
1858                         goto again;
1859                 }
1860
1861                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1862                                       path->slots[level]);
1863                 btrfs_release_path(path);
1864
1865                 path->lowest_level = level;
1866                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1867                 path->lowest_level = 0;
1868                 BUG_ON(ret);
1869
1870                 /*
1871                  * Info qgroup to trace both subtrees.
1872                  *
1873                  * We must trace both trees.
1874                  * 1) Tree reloc subtree
1875                  *    If not traced, we will leak data numbers
1876                  * 2) Fs subtree
1877                  *    If not traced, we will double count old data
1878                  *    and tree block numbers, if current trans doesn't free
1879                  *    data reloc tree inode.
1880                  */
1881                 ret = btrfs_qgroup_trace_subtree(trans, src, parent,
1882                                 btrfs_header_generation(parent),
1883                                 btrfs_header_level(parent));
1884                 if (ret < 0)
1885                         break;
1886                 ret = btrfs_qgroup_trace_subtree(trans, dest,
1887                                 path->nodes[level],
1888                                 btrfs_header_generation(path->nodes[level]),
1889                                 btrfs_header_level(path->nodes[level]));
1890                 if (ret < 0)
1891                         break;
1892
1893                 /*
1894                  * swap blocks in fs tree and reloc tree.
1895                  */
1896                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1897                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1898                 btrfs_mark_buffer_dirty(parent);
1899
1900                 btrfs_set_node_blockptr(path->nodes[level],
1901                                         path->slots[level], old_bytenr);
1902                 btrfs_set_node_ptr_generation(path->nodes[level],
1903                                               path->slots[level], old_ptr_gen);
1904                 btrfs_mark_buffer_dirty(path->nodes[level]);
1905
1906                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr,
1907                                         blocksize, path->nodes[level]->start,
1908                                         src->root_key.objectid, level - 1, 0);
1909                 BUG_ON(ret);
1910                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr,
1911                                         blocksize, 0, dest->root_key.objectid,
1912                                         level - 1, 0);
1913                 BUG_ON(ret);
1914
1915                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1916                                         path->nodes[level]->start,
1917                                         src->root_key.objectid, level - 1, 0);
1918                 BUG_ON(ret);
1919
1920                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1921                                         0, dest->root_key.objectid, level - 1,
1922                                         0);
1923                 BUG_ON(ret);
1924
1925                 btrfs_unlock_up_safe(path, 0);
1926
1927                 ret = level;
1928                 break;
1929         }
1930         btrfs_tree_unlock(parent);
1931         free_extent_buffer(parent);
1932         return ret;
1933 }
1934
1935 /*
1936  * helper to find next relocated block in reloc tree
1937  */
1938 static noinline_for_stack
1939 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1940                        int *level)
1941 {
1942         struct extent_buffer *eb;
1943         int i;
1944         u64 last_snapshot;
1945         u32 nritems;
1946
1947         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1948
1949         for (i = 0; i < *level; i++) {
1950                 free_extent_buffer(path->nodes[i]);
1951                 path->nodes[i] = NULL;
1952         }
1953
1954         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1955                 eb = path->nodes[i];
1956                 nritems = btrfs_header_nritems(eb);
1957                 while (path->slots[i] + 1 < nritems) {
1958                         path->slots[i]++;
1959                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1960                             last_snapshot)
1961                                 continue;
1962
1963                         *level = i;
1964                         return 0;
1965                 }
1966                 free_extent_buffer(path->nodes[i]);
1967                 path->nodes[i] = NULL;
1968         }
1969         return 1;
1970 }
1971
1972 /*
1973  * walk down reloc tree to find relocated block of lowest level
1974  */
1975 static noinline_for_stack
1976 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1977                          int *level)
1978 {
1979         struct btrfs_fs_info *fs_info = root->fs_info;
1980         struct extent_buffer *eb = NULL;
1981         int i;
1982         u64 bytenr;
1983         u64 ptr_gen = 0;
1984         u64 last_snapshot;
1985         u32 nritems;
1986
1987         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1988
1989         for (i = *level; i > 0; i--) {
1990                 struct btrfs_key first_key;
1991
1992                 eb = path->nodes[i];
1993                 nritems = btrfs_header_nritems(eb);
1994                 while (path->slots[i] < nritems) {
1995                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1996                         if (ptr_gen > last_snapshot)
1997                                 break;
1998                         path->slots[i]++;
1999                 }
2000                 if (path->slots[i] >= nritems) {
2001                         if (i == *level)
2002                                 break;
2003                         *level = i + 1;
2004                         return 0;
2005                 }
2006                 if (i == 1) {
2007                         *level = i;
2008                         return 0;
2009                 }
2010
2011                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2012                 btrfs_node_key_to_cpu(eb, &first_key, path->slots[i]);
2013                 eb = read_tree_block(fs_info, bytenr, ptr_gen, i - 1,
2014                                      &first_key);
2015                 if (IS_ERR(eb)) {
2016                         return PTR_ERR(eb);
2017                 } else if (!extent_buffer_uptodate(eb)) {
2018                         free_extent_buffer(eb);
2019                         return -EIO;
2020                 }
2021                 BUG_ON(btrfs_header_level(eb) != i - 1);
2022                 path->nodes[i - 1] = eb;
2023                 path->slots[i - 1] = 0;
2024         }
2025         return 1;
2026 }
2027
2028 /*
2029  * invalidate extent cache for file extents whose key in range of
2030  * [min_key, max_key)
2031  */
2032 static int invalidate_extent_cache(struct btrfs_root *root,
2033                                    struct btrfs_key *min_key,
2034                                    struct btrfs_key *max_key)
2035 {
2036         struct btrfs_fs_info *fs_info = root->fs_info;
2037         struct inode *inode = NULL;
2038         u64 objectid;
2039         u64 start, end;
2040         u64 ino;
2041
2042         objectid = min_key->objectid;
2043         while (1) {
2044                 cond_resched();
2045                 iput(inode);
2046
2047                 if (objectid > max_key->objectid)
2048                         break;
2049
2050                 inode = find_next_inode(root, objectid);
2051                 if (!inode)
2052                         break;
2053                 ino = btrfs_ino(BTRFS_I(inode));
2054
2055                 if (ino > max_key->objectid) {
2056                         iput(inode);
2057                         break;
2058                 }
2059
2060                 objectid = ino + 1;
2061                 if (!S_ISREG(inode->i_mode))
2062                         continue;
2063
2064                 if (unlikely(min_key->objectid == ino)) {
2065                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2066                                 continue;
2067                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2068                                 start = 0;
2069                         else {
2070                                 start = min_key->offset;
2071                                 WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));
2072                         }
2073                 } else {
2074                         start = 0;
2075                 }
2076
2077                 if (unlikely(max_key->objectid == ino)) {
2078                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2079                                 continue;
2080                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2081                                 end = (u64)-1;
2082                         } else {
2083                                 if (max_key->offset == 0)
2084                                         continue;
2085                                 end = max_key->offset;
2086                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
2087                                 end--;
2088                         }
2089                 } else {
2090                         end = (u64)-1;
2091                 }
2092
2093                 /* the lock_extent waits for readpage to complete */
2094                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2095                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
2096                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2097         }
2098         return 0;
2099 }
2100
2101 static int find_next_key(struct btrfs_path *path, int level,
2102                          struct btrfs_key *key)
2103
2104 {
2105         while (level < BTRFS_MAX_LEVEL) {
2106                 if (!path->nodes[level])
2107                         break;
2108                 if (path->slots[level] + 1 <
2109                     btrfs_header_nritems(path->nodes[level])) {
2110                         btrfs_node_key_to_cpu(path->nodes[level], key,
2111                                               path->slots[level] + 1);
2112                         return 0;
2113                 }
2114                 level++;
2115         }
2116         return 1;
2117 }
2118
2119 /*
2120  * merge the relocated tree blocks in reloc tree with corresponding
2121  * fs tree.
2122  */
2123 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2124                                                struct btrfs_root *root)
2125 {
2126         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2127         LIST_HEAD(inode_list);
2128         struct btrfs_key key;
2129         struct btrfs_key next_key;
2130         struct btrfs_trans_handle *trans = NULL;
2131         struct btrfs_root *reloc_root;
2132         struct btrfs_root_item *root_item;
2133         struct btrfs_path *path;
2134         struct extent_buffer *leaf;
2135         int level;
2136         int max_level;
2137         int replaced = 0;
2138         int ret;
2139         int err = 0;
2140         u32 min_reserved;
2141
2142         path = btrfs_alloc_path();
2143         if (!path)
2144                 return -ENOMEM;
2145         path->reada = READA_FORWARD;
2146
2147         reloc_root = root->reloc_root;
2148         root_item = &reloc_root->root_item;
2149
2150         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2151                 level = btrfs_root_level(root_item);
2152                 extent_buffer_get(reloc_root->node);
2153                 path->nodes[level] = reloc_root->node;
2154                 path->slots[level] = 0;
2155         } else {
2156                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2157
2158                 level = root_item->drop_level;
2159                 BUG_ON(level == 0);
2160                 path->lowest_level = level;
2161                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2162                 path->lowest_level = 0;
2163                 if (ret < 0) {
2164                         btrfs_free_path(path);
2165                         return ret;
2166                 }
2167
2168                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2169                                       path->slots[level]);
2170                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2171
2172                 btrfs_unlock_up_safe(path, 0);
2173         }
2174
2175         min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2176         memset(&next_key, 0, sizeof(next_key));
2177
2178         while (1) {
2179                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2180                                              BTRFS_RESERVE_FLUSH_ALL);
2181                 if (ret) {
2182                         err = ret;
2183                         goto out;
2184                 }
2185                 trans = btrfs_start_transaction(root, 0);
2186                 if (IS_ERR(trans)) {
2187                         err = PTR_ERR(trans);
2188                         trans = NULL;
2189                         goto out;
2190                 }
2191                 trans->block_rsv = rc->block_rsv;
2192
2193                 replaced = 0;
2194                 max_level = level;
2195
2196                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2197                 if (ret < 0) {
2198                         err = ret;
2199                         goto out;
2200                 }
2201                 if (ret > 0)
2202                         break;
2203
2204                 if (!find_next_key(path, level, &key) &&
2205                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2206                         ret = 0;
2207                 } else {
2208                         ret = replace_path(trans, root, reloc_root, path,
2209                                            &next_key, level, max_level);
2210                 }
2211                 if (ret < 0) {
2212                         err = ret;
2213                         goto out;
2214                 }
2215
2216                 if (ret > 0) {
2217                         level = ret;
2218                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2219                                               path->slots[level]);
2220                         replaced = 1;
2221                 }
2222
2223                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2224                 if (ret > 0)
2225                         break;
2226
2227                 BUG_ON(level == 0);
2228                 /*
2229                  * save the merging progress in the drop_progress.
2230                  * this is OK since root refs == 1 in this case.
2231                  */
2232                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2233                                path->slots[level]);
2234                 root_item->drop_level = level;
2235
2236                 btrfs_end_transaction_throttle(trans);
2237                 trans = NULL;
2238
2239                 btrfs_btree_balance_dirty(fs_info);
2240
2241                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2242                         invalidate_extent_cache(root, &key, &next_key);
2243         }
2244
2245         /*
2246          * handle the case only one block in the fs tree need to be
2247          * relocated and the block is tree root.
2248          */
2249         leaf = btrfs_lock_root_node(root);
2250         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2251         btrfs_tree_unlock(leaf);
2252         free_extent_buffer(leaf);
2253         if (ret < 0)
2254                 err = ret;
2255 out:
2256         btrfs_free_path(path);
2257
2258         if (err == 0) {
2259                 memset(&root_item->drop_progress, 0,
2260                        sizeof(root_item->drop_progress));
2261                 root_item->drop_level = 0;
2262                 btrfs_set_root_refs(root_item, 0);
2263                 btrfs_update_reloc_root(trans, root);
2264         }
2265
2266         if (trans)
2267                 btrfs_end_transaction_throttle(trans);
2268
2269         btrfs_btree_balance_dirty(fs_info);
2270
2271         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2272                 invalidate_extent_cache(root, &key, &next_key);
2273
2274         return err;
2275 }
2276
2277 static noinline_for_stack
2278 int prepare_to_merge(struct reloc_control *rc, int err)
2279 {
2280         struct btrfs_root *root = rc->extent_root;
2281         struct btrfs_fs_info *fs_info = root->fs_info;
2282         struct btrfs_root *reloc_root;
2283         struct btrfs_trans_handle *trans;
2284         LIST_HEAD(reloc_roots);
2285         u64 num_bytes = 0;
2286         int ret;
2287
2288         mutex_lock(&fs_info->reloc_mutex);
2289         rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2290         rc->merging_rsv_size += rc->nodes_relocated * 2;
2291         mutex_unlock(&fs_info->reloc_mutex);
2292
2293 again:
2294         if (!err) {
2295                 num_bytes = rc->merging_rsv_size;
2296                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2297                                           BTRFS_RESERVE_FLUSH_ALL);
2298                 if (ret)
2299                         err = ret;
2300         }
2301
2302         trans = btrfs_join_transaction(rc->extent_root);
2303         if (IS_ERR(trans)) {
2304                 if (!err)
2305                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2306                                                 num_bytes);
2307                 return PTR_ERR(trans);
2308         }
2309
2310         if (!err) {
2311                 if (num_bytes != rc->merging_rsv_size) {
2312                         btrfs_end_transaction(trans);
2313                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2314                                                 num_bytes);
2315                         goto again;
2316                 }
2317         }
2318
2319         rc->merge_reloc_tree = 1;
2320
2321         while (!list_empty(&rc->reloc_roots)) {
2322                 reloc_root = list_entry(rc->reloc_roots.next,
2323                                         struct btrfs_root, root_list);
2324                 list_del_init(&reloc_root->root_list);
2325
2326                 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2327                 BUG_ON(IS_ERR(root));
2328                 BUG_ON(root->reloc_root != reloc_root);
2329
2330                 /*
2331                  * set reference count to 1, so btrfs_recover_relocation
2332                  * knows it should resumes merging
2333                  */
2334                 if (!err)
2335                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2336                 btrfs_update_reloc_root(trans, root);
2337
2338                 list_add(&reloc_root->root_list, &reloc_roots);
2339         }
2340
2341         list_splice(&reloc_roots, &rc->reloc_roots);
2342
2343         if (!err)
2344                 btrfs_commit_transaction(trans);
2345         else
2346                 btrfs_end_transaction(trans);
2347         return err;
2348 }
2349
2350 static noinline_for_stack
2351 void free_reloc_roots(struct list_head *list)
2352 {
2353         struct btrfs_root *reloc_root;
2354
2355         while (!list_empty(list)) {
2356                 reloc_root = list_entry(list->next, struct btrfs_root,
2357                                         root_list);
2358                 __del_reloc_root(reloc_root);
2359                 free_extent_buffer(reloc_root->node);
2360                 free_extent_buffer(reloc_root->commit_root);
2361                 reloc_root->node = NULL;
2362                 reloc_root->commit_root = NULL;
2363         }
2364 }
2365
2366 static noinline_for_stack
2367 void merge_reloc_roots(struct reloc_control *rc)
2368 {
2369         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2370         struct btrfs_root *root;
2371         struct btrfs_root *reloc_root;
2372         LIST_HEAD(reloc_roots);
2373         int found = 0;
2374         int ret = 0;
2375 again:
2376         root = rc->extent_root;
2377
2378         /*
2379          * this serializes us with btrfs_record_root_in_transaction,
2380          * we have to make sure nobody is in the middle of
2381          * adding their roots to the list while we are
2382          * doing this splice
2383          */
2384         mutex_lock(&fs_info->reloc_mutex);
2385         list_splice_init(&rc->reloc_roots, &reloc_roots);
2386         mutex_unlock(&fs_info->reloc_mutex);
2387
2388         while (!list_empty(&reloc_roots)) {
2389                 found = 1;
2390                 reloc_root = list_entry(reloc_roots.next,
2391                                         struct btrfs_root, root_list);
2392
2393                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2394                         root = read_fs_root(fs_info,
2395                                             reloc_root->root_key.offset);
2396                         BUG_ON(IS_ERR(root));
2397                         BUG_ON(root->reloc_root != reloc_root);
2398
2399                         ret = merge_reloc_root(rc, root);
2400                         if (ret) {
2401                                 if (list_empty(&reloc_root->root_list))
2402                                         list_add_tail(&reloc_root->root_list,
2403                                                       &reloc_roots);
2404                                 goto out;
2405                         }
2406                 } else {
2407                         list_del_init(&reloc_root->root_list);
2408                 }
2409
2410                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2411                 if (ret < 0) {
2412                         if (list_empty(&reloc_root->root_list))
2413                                 list_add_tail(&reloc_root->root_list,
2414                                               &reloc_roots);
2415                         goto out;
2416                 }
2417         }
2418
2419         if (found) {
2420                 found = 0;
2421                 goto again;
2422         }
2423 out:
2424         if (ret) {
2425                 btrfs_handle_fs_error(fs_info, ret, NULL);
2426                 if (!list_empty(&reloc_roots))
2427                         free_reloc_roots(&reloc_roots);
2428
2429                 /* new reloc root may be added */
2430                 mutex_lock(&fs_info->reloc_mutex);
2431                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2432                 mutex_unlock(&fs_info->reloc_mutex);
2433                 if (!list_empty(&reloc_roots))
2434                         free_reloc_roots(&reloc_roots);
2435         }
2436
2437         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2438 }
2439
2440 static void free_block_list(struct rb_root *blocks)
2441 {
2442         struct tree_block *block;
2443         struct rb_node *rb_node;
2444         while ((rb_node = rb_first(blocks))) {
2445                 block = rb_entry(rb_node, struct tree_block, rb_node);
2446                 rb_erase(rb_node, blocks);
2447                 kfree(block);
2448         }
2449 }
2450
2451 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2452                                       struct btrfs_root *reloc_root)
2453 {
2454         struct btrfs_fs_info *fs_info = reloc_root->fs_info;
2455         struct btrfs_root *root;
2456
2457         if (reloc_root->last_trans == trans->transid)
2458                 return 0;
2459
2460         root = read_fs_root(fs_info, reloc_root->root_key.offset);
2461         BUG_ON(IS_ERR(root));
2462         BUG_ON(root->reloc_root != reloc_root);
2463
2464         return btrfs_record_root_in_trans(trans, root);
2465 }
2466
2467 static noinline_for_stack
2468 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2469                                      struct reloc_control *rc,
2470                                      struct backref_node *node,
2471                                      struct backref_edge *edges[])
2472 {
2473         struct backref_node *next;
2474         struct btrfs_root *root;
2475         int index = 0;
2476
2477         next = node;
2478         while (1) {
2479                 cond_resched();
2480                 next = walk_up_backref(next, edges, &index);
2481                 root = next->root;
2482                 BUG_ON(!root);
2483                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2484
2485                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2486                         record_reloc_root_in_trans(trans, root);
2487                         break;
2488                 }
2489
2490                 btrfs_record_root_in_trans(trans, root);
2491                 root = root->reloc_root;
2492
2493                 if (next->new_bytenr != root->node->start) {
2494                         BUG_ON(next->new_bytenr);
2495                         BUG_ON(!list_empty(&next->list));
2496                         next->new_bytenr = root->node->start;
2497                         next->root = root;
2498                         list_add_tail(&next->list,
2499                                       &rc->backref_cache.changed);
2500                         __mark_block_processed(rc, next);
2501                         break;
2502                 }
2503
2504                 WARN_ON(1);
2505                 root = NULL;
2506                 next = walk_down_backref(edges, &index);
2507                 if (!next || next->level <= node->level)
2508                         break;
2509         }
2510         if (!root)
2511                 return NULL;
2512
2513         next = node;
2514         /* setup backref node path for btrfs_reloc_cow_block */
2515         while (1) {
2516                 rc->backref_cache.path[next->level] = next;
2517                 if (--index < 0)
2518                         break;
2519                 next = edges[index]->node[UPPER];
2520         }
2521         return root;
2522 }
2523
2524 /*
2525  * select a tree root for relocation. return NULL if the block
2526  * is reference counted. we should use do_relocation() in this
2527  * case. return a tree root pointer if the block isn't reference
2528  * counted. return -ENOENT if the block is root of reloc tree.
2529  */
2530 static noinline_for_stack
2531 struct btrfs_root *select_one_root(struct backref_node *node)
2532 {
2533         struct backref_node *next;
2534         struct btrfs_root *root;
2535         struct btrfs_root *fs_root = NULL;
2536         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2537         int index = 0;
2538
2539         next = node;
2540         while (1) {
2541                 cond_resched();
2542                 next = walk_up_backref(next, edges, &index);
2543                 root = next->root;
2544                 BUG_ON(!root);
2545
2546                 /* no other choice for non-references counted tree */
2547                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2548                         return root;
2549
2550                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2551                         fs_root = root;
2552
2553                 if (next != node)
2554                         return NULL;
2555
2556                 next = walk_down_backref(edges, &index);
2557                 if (!next || next->level <= node->level)
2558                         break;
2559         }
2560
2561         if (!fs_root)
2562                 return ERR_PTR(-ENOENT);
2563         return fs_root;
2564 }
2565
2566 static noinline_for_stack
2567 u64 calcu_metadata_size(struct reloc_control *rc,
2568                         struct backref_node *node, int reserve)
2569 {
2570         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2571         struct backref_node *next = node;
2572         struct backref_edge *edge;
2573         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2574         u64 num_bytes = 0;
2575         int index = 0;
2576
2577         BUG_ON(reserve && node->processed);
2578
2579         while (next) {
2580                 cond_resched();
2581                 while (1) {
2582                         if (next->processed && (reserve || next != node))
2583                                 break;
2584
2585                         num_bytes += fs_info->nodesize;
2586
2587                         if (list_empty(&next->upper))
2588                                 break;
2589
2590                         edge = list_entry(next->upper.next,
2591                                           struct backref_edge, list[LOWER]);
2592                         edges[index++] = edge;
2593                         next = edge->node[UPPER];
2594                 }
2595                 next = walk_down_backref(edges, &index);
2596         }
2597         return num_bytes;
2598 }
2599
2600 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2601                                   struct reloc_control *rc,
2602                                   struct backref_node *node)
2603 {
2604         struct btrfs_root *root = rc->extent_root;
2605         struct btrfs_fs_info *fs_info = root->fs_info;
2606         u64 num_bytes;
2607         int ret;
2608         u64 tmp;
2609
2610         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2611
2612         trans->block_rsv = rc->block_rsv;
2613         rc->reserved_bytes += num_bytes;
2614
2615         /*
2616          * We are under a transaction here so we can only do limited flushing.
2617          * If we get an enospc just kick back -EAGAIN so we know to drop the
2618          * transaction and try to refill when we can flush all the things.
2619          */
2620         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2621                                 BTRFS_RESERVE_FLUSH_LIMIT);
2622         if (ret) {
2623                 tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
2624                 while (tmp <= rc->reserved_bytes)
2625                         tmp <<= 1;
2626                 /*
2627                  * only one thread can access block_rsv at this point,
2628                  * so we don't need hold lock to protect block_rsv.
2629                  * we expand more reservation size here to allow enough
2630                  * space for relocation and we will return eailer in
2631                  * enospc case.
2632                  */
2633                 rc->block_rsv->size = tmp + fs_info->nodesize *
2634                                       RELOCATION_RESERVED_NODES;
2635                 return -EAGAIN;
2636         }
2637
2638         return 0;
2639 }
2640
2641 /*
2642  * relocate a block tree, and then update pointers in upper level
2643  * blocks that reference the block to point to the new location.
2644  *
2645  * if called by link_to_upper, the block has already been relocated.
2646  * in that case this function just updates pointers.
2647  */
2648 static int do_relocation(struct btrfs_trans_handle *trans,
2649                          struct reloc_control *rc,
2650                          struct backref_node *node,
2651                          struct btrfs_key *key,
2652                          struct btrfs_path *path, int lowest)
2653 {
2654         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2655         struct backref_node *upper;
2656         struct backref_edge *edge;
2657         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2658         struct btrfs_root *root;
2659         struct extent_buffer *eb;
2660         u32 blocksize;
2661         u64 bytenr;
2662         u64 generation;
2663         int slot;
2664         int ret;
2665         int err = 0;
2666
2667         BUG_ON(lowest && node->eb);
2668
2669         path->lowest_level = node->level + 1;
2670         rc->backref_cache.path[node->level] = node;
2671         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2672                 struct btrfs_key first_key;
2673
2674                 cond_resched();
2675
2676                 upper = edge->node[UPPER];
2677                 root = select_reloc_root(trans, rc, upper, edges);
2678                 BUG_ON(!root);
2679
2680                 if (upper->eb && !upper->locked) {
2681                         if (!lowest) {
2682                                 ret = btrfs_bin_search(upper->eb, key,
2683                                                        upper->level, &slot);
2684                                 BUG_ON(ret);
2685                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2686                                 if (node->eb->start == bytenr)
2687                                         goto next;
2688                         }
2689                         drop_node_buffer(upper);
2690                 }
2691
2692                 if (!upper->eb) {
2693                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2694                         if (ret) {
2695                                 if (ret < 0)
2696                                         err = ret;
2697                                 else
2698                                         err = -ENOENT;
2699
2700                                 btrfs_release_path(path);
2701                                 break;
2702                         }
2703
2704                         if (!upper->eb) {
2705                                 upper->eb = path->nodes[upper->level];
2706                                 path->nodes[upper->level] = NULL;
2707                         } else {
2708                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2709                         }
2710
2711                         upper->locked = 1;
2712                         path->locks[upper->level] = 0;
2713
2714                         slot = path->slots[upper->level];
2715                         btrfs_release_path(path);
2716                 } else {
2717                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2718                                                &slot);
2719                         BUG_ON(ret);
2720                 }
2721
2722                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2723                 if (lowest) {
2724                         if (bytenr != node->bytenr) {
2725                                 btrfs_err(root->fs_info,
2726                 "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
2727                                           bytenr, node->bytenr, slot,
2728                                           upper->eb->start);
2729                                 err = -EIO;
2730                                 goto next;
2731                         }
2732                 } else {
2733                         if (node->eb->start == bytenr)
2734                                 goto next;
2735                 }
2736
2737                 blocksize = root->fs_info->nodesize;
2738                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2739                 btrfs_node_key_to_cpu(upper->eb, &first_key, slot);
2740                 eb = read_tree_block(fs_info, bytenr, generation,
2741                                      upper->level - 1, &first_key);
2742                 if (IS_ERR(eb)) {
2743                         err = PTR_ERR(eb);
2744                         goto next;
2745                 } else if (!extent_buffer_uptodate(eb)) {
2746                         free_extent_buffer(eb);
2747                         err = -EIO;
2748                         goto next;
2749                 }
2750                 btrfs_tree_lock(eb);
2751                 btrfs_set_lock_blocking(eb);
2752
2753                 if (!node->eb) {
2754                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2755                                               slot, &eb);
2756                         btrfs_tree_unlock(eb);
2757                         free_extent_buffer(eb);
2758                         if (ret < 0) {
2759                                 err = ret;
2760                                 goto next;
2761                         }
2762                         BUG_ON(node->eb != eb);
2763                 } else {
2764                         btrfs_set_node_blockptr(upper->eb, slot,
2765                                                 node->eb->start);
2766                         btrfs_set_node_ptr_generation(upper->eb, slot,
2767                                                       trans->transid);
2768                         btrfs_mark_buffer_dirty(upper->eb);
2769
2770                         ret = btrfs_inc_extent_ref(trans, root,
2771                                                 node->eb->start, blocksize,
2772                                                 upper->eb->start,
2773                                                 btrfs_header_owner(upper->eb),
2774                                                 node->level, 0);
2775                         BUG_ON(ret);
2776
2777                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2778                         BUG_ON(ret);
2779                 }
2780 next:
2781                 if (!upper->pending)
2782                         drop_node_buffer(upper);
2783                 else
2784                         unlock_node_buffer(upper);
2785                 if (err)
2786                         break;
2787         }
2788
2789         if (!err && node->pending) {
2790                 drop_node_buffer(node);
2791                 list_move_tail(&node->list, &rc->backref_cache.changed);
2792                 node->pending = 0;
2793         }
2794
2795         path->lowest_level = 0;
2796         BUG_ON(err == -ENOSPC);
2797         return err;
2798 }
2799
2800 static int link_to_upper(struct btrfs_trans_handle *trans,
2801                          struct reloc_control *rc,
2802                          struct backref_node *node,
2803                          struct btrfs_path *path)
2804 {
2805         struct btrfs_key key;
2806
2807         btrfs_node_key_to_cpu(node->eb, &key, 0);
2808         return do_relocation(trans, rc, node, &key, path, 0);
2809 }
2810
2811 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2812                                 struct reloc_control *rc,
2813                                 struct btrfs_path *path, int err)
2814 {
2815         LIST_HEAD(list);
2816         struct backref_cache *cache = &rc->backref_cache;
2817         struct backref_node *node;
2818         int level;
2819         int ret;
2820
2821         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2822                 while (!list_empty(&cache->pending[level])) {
2823                         node = list_entry(cache->pending[level].next,
2824                                           struct backref_node, list);
2825                         list_move_tail(&node->list, &list);
2826                         BUG_ON(!node->pending);
2827
2828                         if (!err) {
2829                                 ret = link_to_upper(trans, rc, node, path);
2830                                 if (ret < 0)
2831                                         err = ret;
2832                         }
2833                 }
2834                 list_splice_init(&list, &cache->pending[level]);
2835         }
2836         return err;
2837 }
2838
2839 static void mark_block_processed(struct reloc_control *rc,
2840                                  u64 bytenr, u32 blocksize)
2841 {
2842         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2843                         EXTENT_DIRTY);
2844 }
2845
2846 static void __mark_block_processed(struct reloc_control *rc,
2847                                    struct backref_node *node)
2848 {
2849         u32 blocksize;
2850         if (node->level == 0 ||
2851             in_block_group(node->bytenr, rc->block_group)) {
2852                 blocksize = rc->extent_root->fs_info->nodesize;
2853                 mark_block_processed(rc, node->bytenr, blocksize);
2854         }
2855         node->processed = 1;
2856 }
2857
2858 /*
2859  * mark a block and all blocks directly/indirectly reference the block
2860  * as processed.
2861  */
2862 static void update_processed_blocks(struct reloc_control *rc,
2863                                     struct backref_node *node)
2864 {
2865         struct backref_node *next = node;
2866         struct backref_edge *edge;
2867         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2868         int index = 0;
2869
2870         while (next) {
2871                 cond_resched();
2872                 while (1) {
2873                         if (next->processed)
2874                                 break;
2875
2876                         __mark_block_processed(rc, next);
2877
2878                         if (list_empty(&next->upper))
2879                                 break;
2880
2881                         edge = list_entry(next->upper.next,
2882                                           struct backref_edge, list[LOWER]);
2883                         edges[index++] = edge;
2884                         next = edge->node[UPPER];
2885                 }
2886                 next = walk_down_backref(edges, &index);
2887         }
2888 }
2889
2890 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2891 {
2892         u32 blocksize = rc->extent_root->fs_info->nodesize;
2893
2894         if (test_range_bit(&rc->processed_blocks, bytenr,
2895                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2896                 return 1;
2897         return 0;
2898 }
2899
2900 static int get_tree_block_key(struct btrfs_fs_info *fs_info,
2901                               struct tree_block *block)
2902 {
2903         struct extent_buffer *eb;
2904
2905         BUG_ON(block->key_ready);
2906         eb = read_tree_block(fs_info, block->bytenr, block->key.offset,
2907                              block->level, NULL);
2908         if (IS_ERR(eb)) {
2909                 return PTR_ERR(eb);
2910         } else if (!extent_buffer_uptodate(eb)) {
2911                 free_extent_buffer(eb);
2912                 return -EIO;
2913         }
2914         WARN_ON(btrfs_header_level(eb) != block->level);
2915         if (block->level == 0)
2916                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2917         else
2918                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2919         free_extent_buffer(eb);
2920         block->key_ready = 1;
2921         return 0;
2922 }
2923
2924 /*
2925  * helper function to relocate a tree block
2926  */
2927 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2928                                 struct reloc_control *rc,
2929                                 struct backref_node *node,
2930                                 struct btrfs_key *key,
2931                                 struct btrfs_path *path)
2932 {
2933         struct btrfs_root *root;
2934         int ret = 0;
2935
2936         if (!node)
2937                 return 0;
2938
2939         BUG_ON(node->processed);
2940         root = select_one_root(node);
2941         if (root == ERR_PTR(-ENOENT)) {
2942                 update_processed_blocks(rc, node);
2943                 goto out;
2944         }
2945
2946         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2947                 ret = reserve_metadata_space(trans, rc, node);
2948                 if (ret)
2949                         goto out;
2950         }
2951
2952         if (root) {
2953                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2954                         BUG_ON(node->new_bytenr);
2955                         BUG_ON(!list_empty(&node->list));
2956                         btrfs_record_root_in_trans(trans, root);
2957                         root = root->reloc_root;
2958                         node->new_bytenr = root->node->start;
2959                         node->root = root;
2960                         list_add_tail(&node->list, &rc->backref_cache.changed);
2961                 } else {
2962                         path->lowest_level = node->level;
2963                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2964                         btrfs_release_path(path);
2965                         if (ret > 0)
2966                                 ret = 0;
2967                 }
2968                 if (!ret)
2969                         update_processed_blocks(rc, node);
2970         } else {
2971                 ret = do_relocation(trans, rc, node, key, path, 1);
2972         }
2973 out:
2974         if (ret || node->level == 0 || node->cowonly)
2975                 remove_backref_node(&rc->backref_cache, node);
2976         return ret;
2977 }
2978
2979 /*
2980  * relocate a list of blocks
2981  */
2982 static noinline_for_stack
2983 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2984                          struct reloc_control *rc, struct rb_root *blocks)
2985 {
2986         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2987         struct backref_node *node;
2988         struct btrfs_path *path;
2989         struct tree_block *block;
2990         struct rb_node *rb_node;
2991         int ret;
2992         int err = 0;
2993
2994         path = btrfs_alloc_path();
2995         if (!path) {
2996                 err = -ENOMEM;
2997                 goto out_free_blocks;
2998         }
2999
3000         rb_node = rb_first(blocks);
3001         while (rb_node) {
3002                 block = rb_entry(rb_node, struct tree_block, rb_node);
3003                 if (!block->key_ready)
3004                         readahead_tree_block(fs_info, block->bytenr);
3005                 rb_node = rb_next(rb_node);
3006         }
3007
3008         rb_node = rb_first(blocks);
3009         while (rb_node) {
3010                 block = rb_entry(rb_node, struct tree_block, rb_node);
3011                 if (!block->key_ready) {
3012                         err = get_tree_block_key(fs_info, block);
3013                         if (err)
3014                                 goto out_free_path;
3015                 }
3016                 rb_node = rb_next(rb_node);
3017         }
3018
3019         rb_node = rb_first(blocks);
3020         while (rb_node) {
3021                 block = rb_entry(rb_node, struct tree_block, rb_node);
3022
3023                 node = build_backref_tree(rc, &block->key,
3024                                           block->level, block->bytenr);
3025                 if (IS_ERR(node)) {
3026                         err = PTR_ERR(node);
3027                         goto out;
3028                 }
3029
3030                 ret = relocate_tree_block(trans, rc, node, &block->key,
3031                                           path);
3032                 if (ret < 0) {
3033                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3034                                 err = ret;
3035                         goto out;
3036                 }
3037                 rb_node = rb_next(rb_node);
3038         }
3039 out:
3040         err = finish_pending_nodes(trans, rc, path, err);
3041
3042 out_free_path:
3043         btrfs_free_path(path);
3044 out_free_blocks:
3045         free_block_list(blocks);
3046         return err;
3047 }
3048
3049 static noinline_for_stack
3050 int prealloc_file_extent_cluster(struct inode *inode,
3051                                  struct file_extent_cluster *cluster)
3052 {
3053         u64 alloc_hint = 0;
3054         u64 start;
3055         u64 end;
3056         u64 offset = BTRFS_I(inode)->index_cnt;
3057         u64 num_bytes;
3058         int nr = 0;
3059         int ret = 0;
3060         u64 prealloc_start = cluster->start - offset;
3061         u64 prealloc_end = cluster->end - offset;
3062         u64 cur_offset;
3063         struct extent_changeset *data_reserved = NULL;
3064
3065         BUG_ON(cluster->start != cluster->boundary[0]);
3066         inode_lock(inode);
3067
3068         ret = btrfs_check_data_free_space(inode, &data_reserved, prealloc_start,
3069                                           prealloc_end + 1 - prealloc_start);
3070         if (ret)
3071                 goto out;
3072
3073         cur_offset = prealloc_start;
3074         while (nr < cluster->nr) {
3075                 start = cluster->boundary[nr] - offset;
3076                 if (nr + 1 < cluster->nr)
3077                         end = cluster->boundary[nr + 1] - 1 - offset;
3078                 else
3079                         end = cluster->end - offset;
3080
3081                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3082                 num_bytes = end + 1 - start;
3083                 if (cur_offset < start)
3084                         btrfs_free_reserved_data_space(inode, data_reserved,
3085                                         cur_offset, start - cur_offset);
3086                 ret = btrfs_prealloc_file_range(inode, 0, start,
3087                                                 num_bytes, num_bytes,
3088                                                 end + 1, &alloc_hint);
3089                 cur_offset = end + 1;
3090                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3091                 if (ret)
3092                         break;
3093                 nr++;
3094         }
3095         if (cur_offset < prealloc_end)
3096                 btrfs_free_reserved_data_space(inode, data_reserved,
3097                                 cur_offset, prealloc_end + 1 - cur_offset);
3098 out:
3099         inode_unlock(inode);
3100         extent_changeset_free(data_reserved);
3101         return ret;
3102 }
3103
3104 static noinline_for_stack
3105 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3106                          u64 block_start)
3107 {
3108         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3109         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3110         struct extent_map *em;
3111         int ret = 0;
3112
3113         em = alloc_extent_map();
3114         if (!em)
3115                 return -ENOMEM;
3116
3117         em->start = start;
3118         em->len = end + 1 - start;
3119         em->block_len = em->len;
3120         em->block_start = block_start;
3121         em->bdev = fs_info->fs_devices->latest_bdev;
3122         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3123
3124         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3125         while (1) {
3126                 write_lock(&em_tree->lock);
3127                 ret = add_extent_mapping(em_tree, em, 0);
3128                 write_unlock(&em_tree->lock);
3129                 if (ret != -EEXIST) {
3130                         free_extent_map(em);
3131                         break;
3132                 }
3133                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
3134         }
3135         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3136         return ret;
3137 }
3138
3139 static int relocate_file_extent_cluster(struct inode *inode,
3140                                         struct file_extent_cluster *cluster)
3141 {
3142         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3143         u64 page_start;
3144         u64 page_end;
3145         u64 offset = BTRFS_I(inode)->index_cnt;
3146         unsigned long index;
3147         unsigned long last_index;
3148         struct page *page;
3149         struct file_ra_state *ra;
3150         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3151         int nr = 0;
3152         int ret = 0;
3153
3154         if (!cluster->nr)
3155                 return 0;
3156
3157         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3158         if (!ra)
3159                 return -ENOMEM;
3160
3161         ret = prealloc_file_extent_cluster(inode, cluster);
3162         if (ret)
3163                 goto out;
3164
3165         file_ra_state_init(ra, inode->i_mapping);
3166
3167         ret = setup_extent_mapping(inode, cluster->start - offset,
3168                                    cluster->end - offset, cluster->start);
3169         if (ret)
3170                 goto out;
3171
3172         index = (cluster->start - offset) >> PAGE_SHIFT;
3173         last_index = (cluster->end - offset) >> PAGE_SHIFT;
3174         while (index <= last_index) {
3175                 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
3176                                 PAGE_SIZE);
3177                 if (ret)
3178                         goto out;
3179
3180                 page = find_lock_page(inode->i_mapping, index);
3181                 if (!page) {
3182                         page_cache_sync_readahead(inode->i_mapping,
3183                                                   ra, NULL, index,
3184                                                   last_index + 1 - index);
3185                         page = find_or_create_page(inode->i_mapping, index,
3186                                                    mask);
3187                         if (!page) {
3188                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3189                                                         PAGE_SIZE, true);
3190                                 ret = -ENOMEM;
3191                                 goto out;
3192                         }
3193                 }
3194
3195                 if (PageReadahead(page)) {
3196                         page_cache_async_readahead(inode->i_mapping,
3197                                                    ra, NULL, page, index,
3198                                                    last_index + 1 - index);
3199                 }
3200
3201                 if (!PageUptodate(page)) {
3202                         btrfs_readpage(NULL, page);
3203                         lock_page(page);
3204                         if (!PageUptodate(page)) {
3205                                 unlock_page(page);
3206                                 put_page(page);
3207                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3208                                                         PAGE_SIZE, true);
3209                                 btrfs_delalloc_release_extents(BTRFS_I(inode),
3210                                                                PAGE_SIZE, true);
3211                                 ret = -EIO;
3212                                 goto out;
3213                         }
3214                 }
3215
3216                 page_start = page_offset(page);
3217                 page_end = page_start + PAGE_SIZE - 1;
3218
3219                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3220
3221                 set_page_extent_mapped(page);
3222
3223                 if (nr < cluster->nr &&
3224                     page_start + offset == cluster->boundary[nr]) {
3225                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3226                                         page_start, page_end,
3227                                         EXTENT_BOUNDARY);
3228                         nr++;
3229                 }
3230
3231                 ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
3232                                                 NULL, 0);
3233                 if (ret) {
3234                         unlock_page(page);
3235                         put_page(page);
3236                         btrfs_delalloc_release_metadata(BTRFS_I(inode),
3237                                                          PAGE_SIZE, true);
3238                         btrfs_delalloc_release_extents(BTRFS_I(inode),
3239                                                        PAGE_SIZE, true);
3240
3241                         clear_extent_bits(&BTRFS_I(inode)->io_tree,
3242                                           page_start, page_end,
3243                                           EXTENT_LOCKED | EXTENT_BOUNDARY);
3244                         goto out;
3245
3246                 }
3247                 set_page_dirty(page);
3248
3249                 unlock_extent(&BTRFS_I(inode)->io_tree,
3250                               page_start, page_end);
3251                 unlock_page(page);
3252                 put_page(page);
3253
3254                 index++;
3255                 btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE,
3256                                                false);
3257                 balance_dirty_pages_ratelimited(inode->i_mapping);
3258                 btrfs_throttle(fs_info);
3259         }
3260         WARN_ON(nr != cluster->nr);
3261 out:
3262         kfree(ra);
3263         return ret;
3264 }
3265
3266 static noinline_for_stack
3267 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3268                          struct file_extent_cluster *cluster)
3269 {
3270         int ret;
3271
3272         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3273                 ret = relocate_file_extent_cluster(inode, cluster);
3274                 if (ret)
3275                         return ret;
3276                 cluster->nr = 0;
3277         }
3278
3279         if (!cluster->nr)
3280                 cluster->start = extent_key->objectid;
3281         else
3282                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3283         cluster->end = extent_key->objectid + extent_key->offset - 1;
3284         cluster->boundary[cluster->nr] = extent_key->objectid;
3285         cluster->nr++;
3286
3287         if (cluster->nr >= MAX_EXTENTS) {
3288                 ret = relocate_file_extent_cluster(inode, cluster);
3289                 if (ret)
3290                         return ret;
3291                 cluster->nr = 0;
3292         }
3293         return 0;
3294 }
3295
3296 /*
3297  * helper to add a tree block to the list.
3298  * the major work is getting the generation and level of the block
3299  */
3300 static int add_tree_block(struct reloc_control *rc,
3301                           struct btrfs_key *extent_key,
3302                           struct btrfs_path *path,
3303                           struct rb_root *blocks)
3304 {
3305         struct extent_buffer *eb;
3306         struct btrfs_extent_item *ei;
3307         struct btrfs_tree_block_info *bi;
3308         struct tree_block *block;
3309         struct rb_node *rb_node;
3310         u32 item_size;
3311         int level = -1;
3312         u64 generation;
3313
3314         eb =  path->nodes[0];
3315         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3316
3317         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3318             item_size >= sizeof(*ei) + sizeof(*bi)) {
3319                 ei = btrfs_item_ptr(eb, path->slots[0],
3320                                 struct btrfs_extent_item);
3321                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3322                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3323                         level = btrfs_tree_block_level(eb, bi);
3324                 } else {
3325                         level = (int)extent_key->offset;
3326                 }
3327                 generation = btrfs_extent_generation(eb, ei);
3328         } else if (item_size == sizeof(struct btrfs_extent_item_v0)) {
3329                 btrfs_print_v0_err(eb->fs_info);
3330                 btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3331                 return -EINVAL;
3332         } else {
3333                 BUG();
3334         }
3335
3336         btrfs_release_path(path);
3337
3338         BUG_ON(level == -1);
3339
3340         block = kmalloc(sizeof(*block), GFP_NOFS);
3341         if (!block)
3342                 return -ENOMEM;
3343
3344         block->bytenr = extent_key->objectid;
3345         block->key.objectid = rc->extent_root->fs_info->nodesize;
3346         block->key.offset = generation;
3347         block->level = level;
3348         block->key_ready = 0;
3349
3350         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3351         if (rb_node)
3352                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3353
3354         return 0;
3355 }
3356
3357 /*
3358  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3359  */
3360 static int __add_tree_block(struct reloc_control *rc,
3361                             u64 bytenr, u32 blocksize,
3362                             struct rb_root *blocks)
3363 {
3364         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3365         struct btrfs_path *path;
3366         struct btrfs_key key;
3367         int ret;
3368         bool skinny = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
3369
3370         if (tree_block_processed(bytenr, rc))
3371                 return 0;
3372
3373         if (tree_search(blocks, bytenr))
3374                 return 0;
3375
3376         path = btrfs_alloc_path();
3377         if (!path)
3378                 return -ENOMEM;
3379 again:
3380         key.objectid = bytenr;
3381         if (skinny) {
3382                 key.type = BTRFS_METADATA_ITEM_KEY;
3383                 key.offset = (u64)-1;
3384         } else {
3385                 key.type = BTRFS_EXTENT_ITEM_KEY;
3386                 key.offset = blocksize;
3387         }
3388
3389         path->search_commit_root = 1;
3390         path->skip_locking = 1;
3391         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3392         if (ret < 0)
3393                 goto out;
3394
3395         if (ret > 0 && skinny) {
3396                 if (path->slots[0]) {
3397                         path->slots[0]--;
3398                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3399                                               path->slots[0]);
3400                         if (key.objectid == bytenr &&
3401                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3402                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3403                               key.offset == blocksize)))
3404                                 ret = 0;
3405                 }
3406
3407                 if (ret) {
3408                         skinny = false;
3409                         btrfs_release_path(path);
3410                         goto again;
3411                 }
3412         }
3413         if (ret) {
3414                 ASSERT(ret == 1);
3415                 btrfs_print_leaf(path->nodes[0]);
3416                 btrfs_err(fs_info,
3417              "tree block extent item (%llu) is not found in extent tree",
3418                      bytenr);
3419                 WARN_ON(1);
3420                 ret = -EINVAL;
3421                 goto out;
3422         }
3423
3424         ret = add_tree_block(rc, &key, path, blocks);
3425 out:
3426         btrfs_free_path(path);
3427         return ret;
3428 }
3429
3430 /*
3431  * helper to check if the block use full backrefs for pointers in it
3432  */
3433 static int block_use_full_backref(struct reloc_control *rc,
3434                                   struct extent_buffer *eb)
3435 {
3436         u64 flags;
3437         int ret;
3438
3439         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3440             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3441                 return 1;
3442
3443         ret = btrfs_lookup_extent_info(NULL, rc->extent_root->fs_info,
3444                                        eb->start, btrfs_header_level(eb), 1,
3445                                        NULL, &flags);
3446         BUG_ON(ret);
3447
3448         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3449                 ret = 1;
3450         else
3451                 ret = 0;
3452         return ret;
3453 }
3454
3455 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3456                                     struct btrfs_block_group_cache *block_group,
3457                                     struct inode *inode,
3458                                     u64 ino)
3459 {
3460         struct btrfs_key key;
3461         struct btrfs_root *root = fs_info->tree_root;
3462         struct btrfs_trans_handle *trans;
3463         int ret = 0;
3464
3465         if (inode)
3466                 goto truncate;
3467
3468         key.objectid = ino;
3469         key.type = BTRFS_INODE_ITEM_KEY;
3470         key.offset = 0;
3471
3472         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3473         if (IS_ERR(inode) || is_bad_inode(inode)) {
3474                 if (!IS_ERR(inode))
3475                         iput(inode);
3476                 return -ENOENT;
3477         }
3478
3479 truncate:
3480         ret = btrfs_check_trunc_cache_free_space(fs_info,
3481                                                  &fs_info->global_block_rsv);
3482         if (ret)
3483                 goto out;
3484
3485         trans = btrfs_join_transaction(root);
3486         if (IS_ERR(trans)) {
3487                 ret = PTR_ERR(trans);
3488                 goto out;
3489         }
3490
3491         ret = btrfs_truncate_free_space_cache(trans, block_group, inode);
3492
3493         btrfs_end_transaction(trans);
3494         btrfs_btree_balance_dirty(fs_info);
3495 out:
3496         iput(inode);
3497         return ret;
3498 }
3499
3500 /*
3501  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3502  * this function scans fs tree to find blocks reference the data extent
3503  */
3504 static int find_data_references(struct reloc_control *rc,
3505                                 struct btrfs_key *extent_key,
3506                                 struct extent_buffer *leaf,
3507                                 struct btrfs_extent_data_ref *ref,
3508                                 struct rb_root *blocks)
3509 {
3510         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3511         struct btrfs_path *path;
3512         struct tree_block *block;
3513         struct btrfs_root *root;
3514         struct btrfs_file_extent_item *fi;
3515         struct rb_node *rb_node;
3516         struct btrfs_key key;
3517         u64 ref_root;
3518         u64 ref_objectid;
3519         u64 ref_offset;
3520         u32 ref_count;
3521         u32 nritems;
3522         int err = 0;
3523         int added = 0;
3524         int counted;
3525         int ret;
3526
3527         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3528         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3529         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3530         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3531
3532         /*
3533          * This is an extent belonging to the free space cache, lets just delete
3534          * it and redo the search.
3535          */
3536         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3537                 ret = delete_block_group_cache(fs_info, rc->block_group,
3538                                                NULL, ref_objectid);
3539                 if (ret != -ENOENT)
3540                         return ret;
3541                 ret = 0;
3542         }
3543
3544         path = btrfs_alloc_path();
3545         if (!path)
3546                 return -ENOMEM;
3547         path->reada = READA_FORWARD;
3548
3549         root = read_fs_root(fs_info, ref_root);
3550         if (IS_ERR(root)) {
3551                 err = PTR_ERR(root);
3552                 goto out;
3553         }
3554
3555         key.objectid = ref_objectid;
3556         key.type = BTRFS_EXTENT_DATA_KEY;
3557         if (ref_offset > ((u64)-1 << 32))
3558                 key.offset = 0;
3559         else
3560                 key.offset = ref_offset;
3561
3562         path->search_commit_root = 1;
3563         path->skip_locking = 1;
3564         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3565         if (ret < 0) {
3566                 err = ret;
3567                 goto out;
3568         }
3569
3570         leaf = path->nodes[0];
3571         nritems = btrfs_header_nritems(leaf);
3572         /*
3573          * the references in tree blocks that use full backrefs
3574          * are not counted in
3575          */
3576         if (block_use_full_backref(rc, leaf))
3577                 counted = 0;
3578         else
3579                 counted = 1;
3580         rb_node = tree_search(blocks, leaf->start);
3581         if (rb_node) {
3582                 if (counted)
3583                         added = 1;
3584                 else
3585                         path->slots[0] = nritems;
3586         }
3587
3588         while (ref_count > 0) {
3589                 while (path->slots[0] >= nritems) {
3590                         ret = btrfs_next_leaf(root, path);
3591                         if (ret < 0) {
3592                                 err = ret;
3593                                 goto out;
3594                         }
3595                         if (WARN_ON(ret > 0))
3596                                 goto out;
3597
3598                         leaf = path->nodes[0];
3599                         nritems = btrfs_header_nritems(leaf);
3600                         added = 0;
3601
3602                         if (block_use_full_backref(rc, leaf))
3603                                 counted = 0;
3604                         else
3605                                 counted = 1;
3606                         rb_node = tree_search(blocks, leaf->start);
3607                         if (rb_node) {
3608                                 if (counted)
3609                                         added = 1;
3610                                 else
3611                                         path->slots[0] = nritems;
3612                         }
3613                 }
3614
3615                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3616                 if (WARN_ON(key.objectid != ref_objectid ||
3617                     key.type != BTRFS_EXTENT_DATA_KEY))
3618                         break;
3619
3620                 fi = btrfs_item_ptr(leaf, path->slots[0],
3621                                     struct btrfs_file_extent_item);
3622
3623                 if (btrfs_file_extent_type(leaf, fi) ==
3624                     BTRFS_FILE_EXTENT_INLINE)
3625                         goto next;
3626
3627                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3628                     extent_key->objectid)
3629                         goto next;
3630
3631                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3632                 if (key.offset != ref_offset)
3633                         goto next;
3634
3635                 if (counted)
3636                         ref_count--;
3637                 if (added)
3638                         goto next;
3639
3640                 if (!tree_block_processed(leaf->start, rc)) {
3641                         block = kmalloc(sizeof(*block), GFP_NOFS);
3642                         if (!block) {
3643                                 err = -ENOMEM;
3644                                 break;
3645                         }
3646                         block->bytenr = leaf->start;
3647                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3648                         block->level = 0;
3649                         block->key_ready = 1;
3650                         rb_node = tree_insert(blocks, block->bytenr,
3651                                               &block->rb_node);
3652                         if (rb_node)
3653                                 backref_tree_panic(rb_node, -EEXIST,
3654                                                    block->bytenr);
3655                 }
3656                 if (counted)
3657                         added = 1;
3658                 else
3659                         path->slots[0] = nritems;
3660 next:
3661                 path->slots[0]++;
3662
3663         }
3664 out:
3665         btrfs_free_path(path);
3666         return err;
3667 }
3668
3669 /*
3670  * helper to find all tree blocks that reference a given data extent
3671  */
3672 static noinline_for_stack
3673 int add_data_references(struct reloc_control *rc,
3674                         struct btrfs_key *extent_key,
3675                         struct btrfs_path *path,
3676                         struct rb_root *blocks)
3677 {
3678         struct btrfs_key key;
3679         struct extent_buffer *eb;
3680         struct btrfs_extent_data_ref *dref;
3681         struct btrfs_extent_inline_ref *iref;
3682         unsigned long ptr;
3683         unsigned long end;
3684         u32 blocksize = rc->extent_root->fs_info->nodesize;
3685         int ret = 0;
3686         int err = 0;
3687
3688         eb = path->nodes[0];
3689         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3690         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3691         ptr += sizeof(struct btrfs_extent_item);
3692
3693         while (ptr < end) {
3694                 iref = (struct btrfs_extent_inline_ref *)ptr;
3695                 key.type = btrfs_get_extent_inline_ref_type(eb, iref,
3696                                                         BTRFS_REF_TYPE_DATA);
3697                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3698                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3699                         ret = __add_tree_block(rc, key.offset, blocksize,
3700                                                blocks);
3701                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3702                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3703                         ret = find_data_references(rc, extent_key,
3704                                                    eb, dref, blocks);
3705                 } else {
3706                         ret = -EUCLEAN;
3707                         btrfs_err(rc->extent_root->fs_info,
3708                      "extent %llu slot %d has an invalid inline ref type",
3709                              eb->start, path->slots[0]);
3710                 }
3711                 if (ret) {
3712                         err = ret;
3713                         goto out;
3714                 }
3715                 ptr += btrfs_extent_inline_ref_size(key.type);
3716         }
3717         WARN_ON(ptr > end);
3718
3719         while (1) {
3720                 cond_resched();
3721                 eb = path->nodes[0];
3722                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3723                         ret = btrfs_next_leaf(rc->extent_root, path);
3724                         if (ret < 0) {
3725                                 err = ret;
3726                                 break;
3727                         }
3728                         if (ret > 0)
3729                                 break;
3730                         eb = path->nodes[0];
3731                 }
3732
3733                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3734                 if (key.objectid != extent_key->objectid)
3735                         break;
3736
3737                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3738                         ret = __add_tree_block(rc, key.offset, blocksize,
3739                                                blocks);
3740                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3741                         dref = btrfs_item_ptr(eb, path->slots[0],
3742                                               struct btrfs_extent_data_ref);
3743                         ret = find_data_references(rc, extent_key,
3744                                                    eb, dref, blocks);
3745                 } else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
3746                         btrfs_print_v0_err(eb->fs_info);
3747                         btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3748                         ret = -EINVAL;
3749                 } else {
3750                         ret = 0;
3751                 }
3752                 if (ret) {
3753                         err = ret;
3754                         break;
3755                 }
3756                 path->slots[0]++;
3757         }
3758 out:
3759         btrfs_release_path(path);
3760         if (err)
3761                 free_block_list(blocks);
3762         return err;
3763 }
3764
3765 /*
3766  * helper to find next unprocessed extent
3767  */
3768 static noinline_for_stack
3769 int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
3770                      struct btrfs_key *extent_key)
3771 {
3772         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3773         struct btrfs_key key;
3774         struct extent_buffer *leaf;
3775         u64 start, end, last;
3776         int ret;
3777
3778         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3779         while (1) {
3780                 cond_resched();
3781                 if (rc->search_start >= last) {
3782                         ret = 1;
3783                         break;
3784                 }
3785
3786                 key.objectid = rc->search_start;
3787                 key.type = BTRFS_EXTENT_ITEM_KEY;
3788                 key.offset = 0;
3789
3790                 path->search_commit_root = 1;
3791                 path->skip_locking = 1;
3792                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3793                                         0, 0);
3794                 if (ret < 0)
3795                         break;
3796 next:
3797                 leaf = path->nodes[0];
3798                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3799                         ret = btrfs_next_leaf(rc->extent_root, path);
3800                         if (ret != 0)
3801                                 break;
3802                         leaf = path->nodes[0];
3803                 }
3804
3805                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3806                 if (key.objectid >= last) {
3807                         ret = 1;
3808                         break;
3809                 }
3810
3811                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3812                     key.type != BTRFS_METADATA_ITEM_KEY) {
3813                         path->slots[0]++;
3814                         goto next;
3815                 }
3816
3817                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3818                     key.objectid + key.offset <= rc->search_start) {
3819                         path->slots[0]++;
3820                         goto next;
3821                 }
3822
3823                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3824                     key.objectid + fs_info->nodesize <=
3825                     rc->search_start) {
3826                         path->slots[0]++;
3827                         goto next;
3828                 }
3829
3830                 ret = find_first_extent_bit(&rc->processed_blocks,
3831                                             key.objectid, &start, &end,
3832                                             EXTENT_DIRTY, NULL);
3833
3834                 if (ret == 0 && start <= key.objectid) {
3835                         btrfs_release_path(path);
3836                         rc->search_start = end + 1;
3837                 } else {
3838                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3839                                 rc->search_start = key.objectid + key.offset;
3840                         else
3841                                 rc->search_start = key.objectid +
3842                                         fs_info->nodesize;
3843                         memcpy(extent_key, &key, sizeof(key));
3844                         return 0;
3845                 }
3846         }
3847         btrfs_release_path(path);
3848         return ret;
3849 }
3850
3851 static void set_reloc_control(struct reloc_control *rc)
3852 {
3853         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3854
3855         mutex_lock(&fs_info->reloc_mutex);
3856         fs_info->reloc_ctl = rc;
3857         mutex_unlock(&fs_info->reloc_mutex);
3858 }
3859
3860 static void unset_reloc_control(struct reloc_control *rc)
3861 {
3862         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3863
3864         mutex_lock(&fs_info->reloc_mutex);
3865         fs_info->reloc_ctl = NULL;
3866         mutex_unlock(&fs_info->reloc_mutex);
3867 }
3868
3869 static int check_extent_flags(u64 flags)
3870 {
3871         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3872             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3873                 return 1;
3874         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3875             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3876                 return 1;
3877         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3878             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3879                 return 1;
3880         return 0;
3881 }
3882
3883 static noinline_for_stack
3884 int prepare_to_relocate(struct reloc_control *rc)
3885 {
3886         struct btrfs_trans_handle *trans;
3887         int ret;
3888
3889         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root->fs_info,
3890                                               BTRFS_BLOCK_RSV_TEMP);
3891         if (!rc->block_rsv)
3892                 return -ENOMEM;
3893
3894         memset(&rc->cluster, 0, sizeof(rc->cluster));
3895         rc->search_start = rc->block_group->key.objectid;
3896         rc->extents_found = 0;
3897         rc->nodes_relocated = 0;
3898         rc->merging_rsv_size = 0;
3899         rc->reserved_bytes = 0;
3900         rc->block_rsv->size = rc->extent_root->fs_info->nodesize *
3901                               RELOCATION_RESERVED_NODES;
3902         ret = btrfs_block_rsv_refill(rc->extent_root,
3903                                      rc->block_rsv, rc->block_rsv->size,
3904                                      BTRFS_RESERVE_FLUSH_ALL);
3905         if (ret)
3906                 return ret;
3907
3908         rc->create_reloc_tree = 1;
3909         set_reloc_control(rc);
3910
3911         trans = btrfs_join_transaction(rc->extent_root);
3912         if (IS_ERR(trans)) {
3913                 unset_reloc_control(rc);
3914                 /*
3915                  * extent tree is not a ref_cow tree and has no reloc_root to
3916                  * cleanup.  And callers are responsible to free the above
3917                  * block rsv.
3918                  */
3919                 return PTR_ERR(trans);
3920         }
3921         btrfs_commit_transaction(trans);
3922         return 0;
3923 }
3924
3925 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3926 {
3927         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3928         struct rb_root blocks = RB_ROOT;
3929         struct btrfs_key key;
3930         struct btrfs_trans_handle *trans = NULL;
3931         struct btrfs_path *path;
3932         struct btrfs_extent_item *ei;
3933         u64 flags;
3934         u32 item_size;
3935         int ret;
3936         int err = 0;
3937         int progress = 0;
3938
3939         path = btrfs_alloc_path();
3940         if (!path)
3941                 return -ENOMEM;
3942         path->reada = READA_FORWARD;
3943
3944         ret = prepare_to_relocate(rc);
3945         if (ret) {
3946                 err = ret;
3947                 goto out_free;
3948         }
3949
3950         while (1) {
3951                 rc->reserved_bytes = 0;
3952                 ret = btrfs_block_rsv_refill(rc->extent_root,
3953                                         rc->block_rsv, rc->block_rsv->size,
3954                                         BTRFS_RESERVE_FLUSH_ALL);
3955                 if (ret) {
3956                         err = ret;
3957                         break;
3958                 }
3959                 progress++;
3960                 trans = btrfs_start_transaction(rc->extent_root, 0);
3961                 if (IS_ERR(trans)) {
3962                         err = PTR_ERR(trans);
3963                         trans = NULL;
3964                         break;
3965                 }
3966 restart:
3967                 if (update_backref_cache(trans, &rc->backref_cache)) {
3968                         btrfs_end_transaction(trans);
3969                         continue;
3970                 }
3971
3972                 ret = find_next_extent(rc, path, &key);
3973                 if (ret < 0)
3974                         err = ret;
3975                 if (ret != 0)
3976                         break;
3977
3978                 rc->extents_found++;
3979
3980                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3981                                     struct btrfs_extent_item);
3982                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3983                 if (item_size >= sizeof(*ei)) {
3984                         flags = btrfs_extent_flags(path->nodes[0], ei);
3985                         ret = check_extent_flags(flags);
3986                         BUG_ON(ret);
3987                 } else if (item_size == sizeof(struct btrfs_extent_item_v0)) {
3988                         err = -EINVAL;
3989                         btrfs_print_v0_err(trans->fs_info);
3990                         btrfs_abort_transaction(trans, err);
3991                         break;
3992                 } else {
3993                         BUG();
3994                 }
3995
3996                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3997                         ret = add_tree_block(rc, &key, path, &blocks);
3998                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3999                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4000                         ret = add_data_references(rc, &key, path, &blocks);
4001                 } else {
4002                         btrfs_release_path(path);
4003                         ret = 0;
4004                 }
4005                 if (ret < 0) {
4006                         err = ret;
4007                         break;
4008                 }
4009
4010                 if (!RB_EMPTY_ROOT(&blocks)) {
4011                         ret = relocate_tree_blocks(trans, rc, &blocks);
4012                         if (ret < 0) {
4013                                 /*
4014                                  * if we fail to relocate tree blocks, force to update
4015                                  * backref cache when committing transaction.
4016                                  */
4017                                 rc->backref_cache.last_trans = trans->transid - 1;
4018
4019                                 if (ret != -EAGAIN) {
4020                                         err = ret;
4021                                         break;
4022                                 }
4023                                 rc->extents_found--;
4024                                 rc->search_start = key.objectid;
4025                         }
4026                 }
4027
4028                 btrfs_end_transaction_throttle(trans);
4029                 btrfs_btree_balance_dirty(fs_info);
4030                 trans = NULL;
4031
4032                 if (rc->stage == MOVE_DATA_EXTENTS &&
4033                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4034                         rc->found_file_extent = 1;
4035                         ret = relocate_data_extent(rc->data_inode,
4036                                                    &key, &rc->cluster);
4037                         if (ret < 0) {
4038                                 err = ret;
4039                                 break;
4040                         }
4041                 }
4042         }
4043         if (trans && progress && err == -ENOSPC) {
4044                 ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);
4045                 if (ret == 1) {
4046                         err = 0;
4047                         progress = 0;
4048                         goto restart;
4049                 }
4050         }
4051
4052         btrfs_release_path(path);
4053         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY);
4054
4055         if (trans) {
4056                 btrfs_end_transaction_throttle(trans);
4057                 btrfs_btree_balance_dirty(fs_info);
4058         }
4059
4060         if (!err) {
4061                 ret = relocate_file_extent_cluster(rc->data_inode,
4062                                                    &rc->cluster);
4063                 if (ret < 0)
4064                         err = ret;
4065         }
4066
4067         rc->create_reloc_tree = 0;
4068         set_reloc_control(rc);
4069
4070         backref_cache_cleanup(&rc->backref_cache);
4071         btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4072
4073         err = prepare_to_merge(rc, err);
4074
4075         merge_reloc_roots(rc);
4076
4077         rc->merge_reloc_tree = 0;
4078         unset_reloc_control(rc);
4079         btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4080
4081         /* get rid of pinned extents */
4082         trans = btrfs_join_transaction(rc->extent_root);
4083         if (IS_ERR(trans)) {
4084                 err = PTR_ERR(trans);
4085                 goto out_free;
4086         }
4087         btrfs_commit_transaction(trans);
4088 out_free:
4089         btrfs_free_block_rsv(fs_info, rc->block_rsv);
4090         btrfs_free_path(path);
4091         return err;
4092 }
4093
4094 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4095                                  struct btrfs_root *root, u64 objectid)
4096 {
4097         struct btrfs_path *path;
4098         struct btrfs_inode_item *item;
4099         struct extent_buffer *leaf;
4100         int ret;
4101
4102         path = btrfs_alloc_path();
4103         if (!path)
4104                 return -ENOMEM;
4105
4106         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4107         if (ret)
4108                 goto out;
4109
4110         leaf = path->nodes[0];
4111         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4112         memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));
4113         btrfs_set_inode_generation(leaf, item, 1);
4114         btrfs_set_inode_size(leaf, item, 0);
4115         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4116         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4117                                           BTRFS_INODE_PREALLOC);
4118         btrfs_mark_buffer_dirty(leaf);
4119 out:
4120         btrfs_free_path(path);
4121         return ret;
4122 }
4123
4124 /*
4125  * helper to create inode for data relocation.
4126  * the inode is in data relocation tree and its link count is 0
4127  */
4128 static noinline_for_stack
4129 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4130                                  struct btrfs_block_group_cache *group)
4131 {
4132         struct inode *inode = NULL;
4133         struct btrfs_trans_handle *trans;
4134         struct btrfs_root *root;
4135         struct btrfs_key key;
4136         u64 objectid;
4137         int err = 0;
4138
4139         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4140         if (IS_ERR(root))
4141                 return ERR_CAST(root);
4142
4143         trans = btrfs_start_transaction(root, 6);
4144         if (IS_ERR(trans))
4145                 return ERR_CAST(trans);
4146
4147         err = btrfs_find_free_objectid(root, &objectid);
4148         if (err)
4149                 goto out;
4150
4151         err = __insert_orphan_inode(trans, root, objectid);
4152         BUG_ON(err);
4153
4154         key.objectid = objectid;
4155         key.type = BTRFS_INODE_ITEM_KEY;
4156         key.offset = 0;
4157         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
4158         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4159         BTRFS_I(inode)->index_cnt = group->key.objectid;
4160
4161         err = btrfs_orphan_add(trans, BTRFS_I(inode));
4162 out:
4163         btrfs_end_transaction(trans);
4164         btrfs_btree_balance_dirty(fs_info);
4165         if (err) {
4166                 if (inode)
4167                         iput(inode);
4168                 inode = ERR_PTR(err);
4169         }
4170         return inode;
4171 }
4172
4173 static struct reloc_control *alloc_reloc_control(void)
4174 {
4175         struct reloc_control *rc;
4176
4177         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4178         if (!rc)
4179                 return NULL;
4180
4181         INIT_LIST_HEAD(&rc->reloc_roots);
4182         backref_cache_init(&rc->backref_cache);
4183         mapping_tree_init(&rc->reloc_root_tree);
4184         extent_io_tree_init(&rc->processed_blocks, NULL);
4185         return rc;
4186 }
4187
4188 /*
4189  * Print the block group being relocated
4190  */
4191 static void describe_relocation(struct btrfs_fs_info *fs_info,
4192                                 struct btrfs_block_group_cache *block_group)
4193 {
4194         char buf[128];          /* prefixed by a '|' that'll be dropped */
4195         u64 flags = block_group->flags;
4196
4197         /* Shouldn't happen */
4198         if (!flags) {
4199                 strcpy(buf, "|NONE");
4200         } else {
4201                 char *bp = buf;
4202
4203 #define DESCRIBE_FLAG(f, d) \
4204                 if (flags & BTRFS_BLOCK_GROUP_##f) { \
4205                         bp += snprintf(bp, buf - bp + sizeof(buf), "|%s", d); \
4206                         flags &= ~BTRFS_BLOCK_GROUP_##f; \
4207                 }
4208                 DESCRIBE_FLAG(DATA,     "data");
4209                 DESCRIBE_FLAG(SYSTEM,   "system");
4210                 DESCRIBE_FLAG(METADATA, "metadata");
4211                 DESCRIBE_FLAG(RAID0,    "raid0");
4212                 DESCRIBE_FLAG(RAID1,    "raid1");
4213                 DESCRIBE_FLAG(DUP,      "dup");
4214                 DESCRIBE_FLAG(RAID10,   "raid10");
4215                 DESCRIBE_FLAG(RAID5,    "raid5");
4216                 DESCRIBE_FLAG(RAID6,    "raid6");
4217                 if (flags)
4218                         snprintf(bp, buf - bp + sizeof(buf), "|0x%llx", flags);
4219 #undef DESCRIBE_FLAG
4220         }
4221
4222         btrfs_info(fs_info,
4223                    "relocating block group %llu flags %s",
4224                    block_group->key.objectid, buf + 1);
4225 }
4226
4227 /*
4228  * function to relocate all extents in a block group.
4229  */
4230 int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
4231 {
4232         struct btrfs_root *extent_root = fs_info->extent_root;
4233         struct reloc_control *rc;
4234         struct inode *inode;
4235         struct btrfs_path *path;
4236         int ret;
4237         int rw = 0;
4238         int err = 0;
4239
4240         rc = alloc_reloc_control();
4241         if (!rc)
4242                 return -ENOMEM;
4243
4244         rc->extent_root = extent_root;
4245
4246         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4247         BUG_ON(!rc->block_group);
4248
4249         ret = btrfs_inc_block_group_ro(rc->block_group);
4250         if (ret) {
4251                 err = ret;
4252                 goto out;
4253         }
4254         rw = 1;
4255
4256         path = btrfs_alloc_path();
4257         if (!path) {
4258                 err = -ENOMEM;
4259                 goto out;
4260         }
4261
4262         inode = lookup_free_space_inode(fs_info, rc->block_group, path);
4263         btrfs_free_path(path);
4264
4265         if (!IS_ERR(inode))
4266                 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4267         else
4268                 ret = PTR_ERR(inode);
4269
4270         if (ret && ret != -ENOENT) {
4271                 err = ret;
4272                 goto out;
4273         }
4274
4275         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4276         if (IS_ERR(rc->data_inode)) {
4277                 err = PTR_ERR(rc->data_inode);
4278                 rc->data_inode = NULL;
4279                 goto out;
4280         }
4281
4282         describe_relocation(fs_info, rc->block_group);
4283
4284         btrfs_wait_block_group_reservations(rc->block_group);
4285         btrfs_wait_nocow_writers(rc->block_group);
4286         btrfs_wait_ordered_roots(fs_info, U64_MAX,
4287                                  rc->block_group->key.objectid,
4288                                  rc->block_group->key.offset);
4289
4290         while (1) {
4291                 mutex_lock(&fs_info->cleaner_mutex);
4292                 ret = relocate_block_group(rc);
4293                 mutex_unlock(&fs_info->cleaner_mutex);
4294                 if (ret < 0) {
4295                         err = ret;
4296                         goto out;
4297                 }
4298
4299                 if (rc->extents_found == 0)
4300                         break;
4301
4302                 btrfs_info(fs_info, "found %llu extents", rc->extents_found);
4303
4304                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4305                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4306                                                        (u64)-1);
4307                         if (ret) {
4308                                 err = ret;
4309                                 goto out;
4310                         }
4311                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4312                                                  0, -1);
4313                         rc->stage = UPDATE_DATA_PTRS;
4314                 }
4315         }
4316
4317         WARN_ON(rc->block_group->pinned > 0);
4318         WARN_ON(rc->block_group->reserved > 0);
4319         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4320 out:
4321         if (err && rw)
4322                 btrfs_dec_block_group_ro(rc->block_group);
4323         iput(rc->data_inode);
4324         btrfs_put_block_group(rc->block_group);
4325         kfree(rc);
4326         return err;
4327 }
4328
4329 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4330 {
4331         struct btrfs_fs_info *fs_info = root->fs_info;
4332         struct btrfs_trans_handle *trans;
4333         int ret, err;
4334
4335         trans = btrfs_start_transaction(fs_info->tree_root, 0);
4336         if (IS_ERR(trans))
4337                 return PTR_ERR(trans);
4338
4339         memset(&root->root_item.drop_progress, 0,
4340                 sizeof(root->root_item.drop_progress));
4341         root->root_item.drop_level = 0;
4342         btrfs_set_root_refs(&root->root_item, 0);
4343         ret = btrfs_update_root(trans, fs_info->tree_root,
4344                                 &root->root_key, &root->root_item);
4345
4346         err = btrfs_end_transaction(trans);
4347         if (err)
4348                 return err;
4349         return ret;
4350 }
4351
4352 /*
4353  * recover relocation interrupted by system crash.
4354  *
4355  * this function resumes merging reloc trees with corresponding fs trees.
4356  * this is important for keeping the sharing of tree blocks
4357  */
4358 int btrfs_recover_relocation(struct btrfs_root *root)
4359 {
4360         struct btrfs_fs_info *fs_info = root->fs_info;
4361         LIST_HEAD(reloc_roots);
4362         struct btrfs_key key;
4363         struct btrfs_root *fs_root;
4364         struct btrfs_root *reloc_root;
4365         struct btrfs_path *path;
4366         struct extent_buffer *leaf;
4367         struct reloc_control *rc = NULL;
4368         struct btrfs_trans_handle *trans;
4369         int ret;
4370         int err = 0;
4371
4372         path = btrfs_alloc_path();
4373         if (!path)
4374                 return -ENOMEM;
4375         path->reada = READA_BACK;
4376
4377         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4378         key.type = BTRFS_ROOT_ITEM_KEY;
4379         key.offset = (u64)-1;
4380
4381         while (1) {
4382                 ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,
4383                                         path, 0, 0);
4384                 if (ret < 0) {
4385                         err = ret;
4386                         goto out;
4387                 }
4388                 if (ret > 0) {
4389                         if (path->slots[0] == 0)
4390                                 break;
4391                         path->slots[0]--;
4392                 }
4393                 leaf = path->nodes[0];
4394                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4395                 btrfs_release_path(path);
4396
4397                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4398                     key.type != BTRFS_ROOT_ITEM_KEY)
4399                         break;
4400
4401                 reloc_root = btrfs_read_fs_root(root, &key);
4402                 if (IS_ERR(reloc_root)) {
4403                         err = PTR_ERR(reloc_root);
4404                         goto out;
4405                 }
4406
4407                 list_add(&reloc_root->root_list, &reloc_roots);
4408
4409                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4410                         fs_root = read_fs_root(fs_info,
4411                                                reloc_root->root_key.offset);
4412                         if (IS_ERR(fs_root)) {
4413                                 ret = PTR_ERR(fs_root);
4414                                 if (ret != -ENOENT) {
4415                                         err = ret;
4416                                         goto out;
4417                                 }
4418                                 ret = mark_garbage_root(reloc_root);
4419                                 if (ret < 0) {
4420                                         err = ret;
4421                                         goto out;
4422                                 }
4423                         }
4424                 }
4425
4426                 if (key.offset == 0)
4427                         break;
4428
4429                 key.offset--;
4430         }
4431         btrfs_release_path(path);
4432
4433         if (list_empty(&reloc_roots))
4434                 goto out;
4435
4436         rc = alloc_reloc_control();
4437         if (!rc) {
4438                 err = -ENOMEM;
4439                 goto out;
4440         }
4441
4442         rc->extent_root = fs_info->extent_root;
4443
4444         set_reloc_control(rc);
4445
4446         trans = btrfs_join_transaction(rc->extent_root);
4447         if (IS_ERR(trans)) {
4448                 unset_reloc_control(rc);
4449                 err = PTR_ERR(trans);
4450                 goto out_free;
4451         }
4452
4453         rc->merge_reloc_tree = 1;
4454
4455         while (!list_empty(&reloc_roots)) {
4456                 reloc_root = list_entry(reloc_roots.next,
4457                                         struct btrfs_root, root_list);
4458                 list_del(&reloc_root->root_list);
4459
4460                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4461                         list_add_tail(&reloc_root->root_list,
4462                                       &rc->reloc_roots);
4463                         continue;
4464                 }
4465
4466                 fs_root = read_fs_root(fs_info, reloc_root->root_key.offset);
4467                 if (IS_ERR(fs_root)) {
4468                         err = PTR_ERR(fs_root);
4469                         goto out_free;
4470                 }
4471
4472                 err = __add_reloc_root(reloc_root);
4473                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4474                 fs_root->reloc_root = reloc_root;
4475         }
4476
4477         err = btrfs_commit_transaction(trans);
4478         if (err)
4479                 goto out_free;
4480
4481         merge_reloc_roots(rc);
4482
4483         unset_reloc_control(rc);
4484
4485         trans = btrfs_join_transaction(rc->extent_root);
4486         if (IS_ERR(trans)) {
4487                 err = PTR_ERR(trans);
4488                 goto out_free;
4489         }
4490         err = btrfs_commit_transaction(trans);
4491 out_free:
4492         kfree(rc);
4493 out:
4494         if (!list_empty(&reloc_roots))
4495                 free_reloc_roots(&reloc_roots);
4496
4497         btrfs_free_path(path);
4498
4499         if (err == 0) {
4500                 /* cleanup orphan inode in data relocation tree */
4501                 fs_root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4502                 if (IS_ERR(fs_root))
4503                         err = PTR_ERR(fs_root);
4504                 else
4505                         err = btrfs_orphan_cleanup(fs_root);
4506         }
4507         return err;
4508 }
4509
4510 /*
4511  * helper to add ordered checksum for data relocation.
4512  *
4513  * cloning checksum properly handles the nodatasum extents.
4514  * it also saves CPU time to re-calculate the checksum.
4515  */
4516 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4517 {
4518         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4519         struct btrfs_ordered_sum *sums;
4520         struct btrfs_ordered_extent *ordered;
4521         int ret;
4522         u64 disk_bytenr;
4523         u64 new_bytenr;
4524         LIST_HEAD(list);
4525
4526         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4527         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4528
4529         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4530         ret = btrfs_lookup_csums_range(fs_info->csum_root, disk_bytenr,
4531                                        disk_bytenr + len - 1, &list, 0);
4532         if (ret)
4533                 goto out;
4534
4535         while (!list_empty(&list)) {
4536                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4537                 list_del_init(&sums->list);
4538
4539                 /*
4540                  * We need to offset the new_bytenr based on where the csum is.
4541                  * We need to do this because we will read in entire prealloc
4542                  * extents but we may have written to say the middle of the
4543                  * prealloc extent, so we need to make sure the csum goes with
4544                  * the right disk offset.
4545                  *
4546                  * We can do this because the data reloc inode refers strictly
4547                  * to the on disk bytes, so we don't have to worry about
4548                  * disk_len vs real len like with real inodes since it's all
4549                  * disk length.
4550                  */
4551                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4552                 sums->bytenr = new_bytenr;
4553
4554                 btrfs_add_ordered_sum(inode, ordered, sums);
4555         }
4556 out:
4557         btrfs_put_ordered_extent(ordered);
4558         return ret;
4559 }
4560
4561 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4562                           struct btrfs_root *root, struct extent_buffer *buf,
4563                           struct extent_buffer *cow)
4564 {
4565         struct btrfs_fs_info *fs_info = root->fs_info;
4566         struct reloc_control *rc;
4567         struct backref_node *node;
4568         int first_cow = 0;
4569         int level;
4570         int ret = 0;
4571
4572         rc = fs_info->reloc_ctl;
4573         if (!rc)
4574                 return 0;
4575
4576         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4577                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4578
4579         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4580                 if (buf == root->node)
4581                         __update_reloc_root(root, cow->start);
4582         }
4583
4584         level = btrfs_header_level(buf);
4585         if (btrfs_header_generation(buf) <=
4586             btrfs_root_last_snapshot(&root->root_item))
4587                 first_cow = 1;
4588
4589         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4590             rc->create_reloc_tree) {
4591                 WARN_ON(!first_cow && level == 0);
4592
4593                 node = rc->backref_cache.path[level];
4594                 BUG_ON(node->bytenr != buf->start &&
4595                        node->new_bytenr != buf->start);
4596
4597                 drop_node_buffer(node);
4598                 extent_buffer_get(cow);
4599                 node->eb = cow;
4600                 node->new_bytenr = cow->start;
4601
4602                 if (!node->pending) {
4603                         list_move_tail(&node->list,
4604                                        &rc->backref_cache.pending[level]);
4605                         node->pending = 1;
4606                 }
4607
4608                 if (first_cow)
4609                         __mark_block_processed(rc, node);
4610
4611                 if (first_cow && level > 0)
4612                         rc->nodes_relocated += buf->len;
4613         }
4614
4615         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4616                 ret = replace_file_extents(trans, rc, root, cow);
4617         return ret;
4618 }
4619
4620 /*
4621  * called before creating snapshot. it calculates metadata reservation
4622  * required for relocating tree blocks in the snapshot
4623  */
4624 void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
4625                               u64 *bytes_to_reserve)
4626 {
4627         struct btrfs_root *root;
4628         struct reloc_control *rc;
4629
4630         root = pending->root;
4631         if (!root->reloc_root)
4632                 return;
4633
4634         rc = root->fs_info->reloc_ctl;
4635         if (!rc->merge_reloc_tree)
4636                 return;
4637
4638         root = root->reloc_root;
4639         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4640         /*
4641          * relocation is in the stage of merging trees. the space
4642          * used by merging a reloc tree is twice the size of
4643          * relocated tree nodes in the worst case. half for cowing
4644          * the reloc tree, half for cowing the fs tree. the space
4645          * used by cowing the reloc tree will be freed after the
4646          * tree is dropped. if we create snapshot, cowing the fs
4647          * tree may use more space than it frees. so we need
4648          * reserve extra space.
4649          */
4650         *bytes_to_reserve += rc->nodes_relocated;
4651 }
4652
4653 /*
4654  * called after snapshot is created. migrate block reservation
4655  * and create reloc root for the newly created snapshot
4656  */
4657 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4658                                struct btrfs_pending_snapshot *pending)
4659 {
4660         struct btrfs_root *root = pending->root;
4661         struct btrfs_root *reloc_root;
4662         struct btrfs_root *new_root;
4663         struct reloc_control *rc;
4664         int ret;
4665
4666         if (!root->reloc_root)
4667                 return 0;
4668
4669         rc = root->fs_info->reloc_ctl;
4670         rc->merging_rsv_size += rc->nodes_relocated;
4671
4672         if (rc->merge_reloc_tree) {
4673                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4674                                               rc->block_rsv,
4675                                               rc->nodes_relocated, 1);
4676                 if (ret)
4677                         return ret;
4678         }
4679
4680         new_root = pending->snap;
4681         reloc_root = create_reloc_root(trans, root->reloc_root,
4682                                        new_root->root_key.objectid);
4683         if (IS_ERR(reloc_root))
4684                 return PTR_ERR(reloc_root);
4685
4686         ret = __add_reloc_root(reloc_root);
4687         BUG_ON(ret < 0);
4688         new_root->reloc_root = reloc_root;
4689
4690         if (rc->create_reloc_tree)
4691                 ret = clone_backref_node(trans, rc, root, reloc_root);
4692         return ret;
4693 }