fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97 #define RELOCATION_RESERVED_NODES       256
  98
  99 struct backref_cache {
 100         /* red black tree of all backref nodes in the cache */
 101         struct rb_root rb_root;
 102         /* for passing backref nodes to btrfs_reloc_cow_block */
 103         struct backref_node *path[BTRFS_MAX_LEVEL];
 104         /*
 105          * list of blocks that have been cowed but some block
 106          * pointers in upper level blocks may not reflect the
 107          * new location
 108          */
 109         struct list_head pending[BTRFS_MAX_LEVEL];
 110         /* list of backref nodes with no child node */
 111         struct list_head leaves;
 112         /* list of blocks that have been cowed in current transaction */
 113         struct list_head changed;
 114         /* list of detached backref node. */
 115         struct list_head detached;
 116
 117         u64 last_trans;
 118
 119         int nr_nodes;
 120         int nr_edges;
 121 };
 122
 123 /*
 124  * map address of tree root to tree
 125  */
 126 struct mapping_node {
 127         struct rb_node rb_node;
 128         u64 bytenr;
 129         void *data;
 130 };
 131
 132 struct mapping_tree {
 133         struct rb_root rb_root;
 134         spinlock_t lock;
 135 };
 136
 137 /*
 138  * present a tree block to process
 139  */
 140 struct tree_block {
 141         struct rb_node rb_node;
 142         u64 bytenr;
 143         struct btrfs_key key;
 144         unsigned int level:8;
 145         unsigned int key_ready:1;
 146 };
 147
 148 #define MAX_EXTENTS 128
 149
 150 struct file_extent_cluster {
 151         u64 start;
 152         u64 end;
 153         u64 boundary[MAX_EXTENTS];
 154         unsigned int nr;
 155 };
 156
 157 struct reloc_control {
 158         /* block group to relocate */
 159         struct btrfs_block_group_cache *block_group;
 160         /* extent tree */
 161         struct btrfs_root *extent_root;
 162         /* inode for moving data */
 163         struct inode *data_inode;
 164
 165         struct btrfs_block_rsv *block_rsv;
 166
 167         struct backref_cache backref_cache;
 168
 169         struct file_extent_cluster cluster;
 170         /* tree blocks have been processed */
 171         struct extent_io_tree processed_blocks;
 172         /* map start of tree root to corresponding reloc tree */
 173         struct mapping_tree reloc_root_tree;
 174         /* list of reloc trees */
 175         struct list_head reloc_roots;
 176         /* size of metadata reservation for merging reloc trees */
 177         u64 merging_rsv_size;
 178         /* size of relocated tree nodes */
 179         u64 nodes_relocated;
 180         /* reserved size for block group relocation*/
 181         u64 reserved_bytes;
 182
 183         u64 search_start;
 184         u64 extents_found;
 185
 186         unsigned int stage:8;
 187         unsigned int create_reloc_tree:1;
 188         unsigned int merge_reloc_tree:1;
 189         unsigned int found_file_extent:1;
 190 };
 191
 192 /* stages of data relocation */
 193 #define MOVE_DATA_EXTENTS       0
 194 #define UPDATE_DATA_PTRS        1
 195
 196 static void remove_backref_node(struct backref_cache *cache,
 197                                 struct backref_node *node);
 198 static void __mark_block_processed(struct reloc_control *rc,
 199                                    struct backref_node *node);
 200
 201 static void mapping_tree_init(struct mapping_tree *tree)
 202 {
 203         tree->rb_root = RB_ROOT;
 204         spin_lock_init(&tree->lock);
 205 }
 206
 207 static void backref_cache_init(struct backref_cache *cache)
 208 {
 209         int i;
 210         cache->rb_root = RB_ROOT;
 211         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 212                 INIT_LIST_HEAD(&cache->pending[i]);
 213         INIT_LIST_HEAD(&cache->changed);
 214         INIT_LIST_HEAD(&cache->detached);
 215         INIT_LIST_HEAD(&cache->leaves);
 216 }
 217
 218 static void backref_cache_cleanup(struct backref_cache *cache)
 219 {
 220         struct backref_node *node;
 221         int i;
 222
 223         while (!list_empty(&cache->detached)) {
 224                 node = list_entry(cache->detached.next,
 225                                   struct backref_node, list);
 226                 remove_backref_node(cache, node);
 227         }
 228
 229         while (!list_empty(&cache->leaves)) {
 230                 node = list_entry(cache->leaves.next,
 231                                   struct backref_node, lower);
 232                 remove_backref_node(cache, node);
 233         }
 234
 235         cache->last_trans = 0;
 236
 237         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 238                 BUG_ON(!list_empty(&cache->pending[i]));
 239         BUG_ON(!list_empty(&cache->changed));
 240         BUG_ON(!list_empty(&cache->detached));
 241         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 242         BUG_ON(cache->nr_nodes);
 243         BUG_ON(cache->nr_edges);
 244 }
 245
 246 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 247 {
 248         struct backref_node *node;
 249
 250         node = kzalloc(sizeof(*node), GFP_NOFS);
 251         if (node) {
 252                 INIT_LIST_HEAD(&node->list);
 253                 INIT_LIST_HEAD(&node->upper);
 254                 INIT_LIST_HEAD(&node->lower);
 255                 RB_CLEAR_NODE(&node->rb_node);
 256                 cache->nr_nodes++;
 257         }
 258         return node;
 259 }
 260
 261 static void free_backref_node(struct backref_cache *cache,
 262                               struct backref_node *node)
 263 {
 264         if (node) {
 265                 cache->nr_nodes--;
 266                 kfree(node);
 267         }
 268 }
 269
 270 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 271 {
 272         struct backref_edge *edge;
 273
 274         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 275         if (edge)
 276                 cache->nr_edges++;
 277         return edge;
 278 }
 279
 280 static void free_backref_edge(struct backref_cache *cache,
 281                               struct backref_edge *edge)
 282 {
 283         if (edge) {
 284                 cache->nr_edges--;
 285                 kfree(edge);
 286         }
 287 }
 288
 289 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 290                                    struct rb_node *node)
 291 {
 292         struct rb_node **p = &root->rb_node;
 293         struct rb_node *parent = NULL;
 294         struct tree_entry *entry;
 295
 296         while (*p) {
 297                 parent = *p;
 298                 entry = rb_entry(parent, struct tree_entry, rb_node);
 299
 300                 if (bytenr < entry->bytenr)
 301                         p = &(*p)->rb_left;
 302                 else if (bytenr > entry->bytenr)
 303                         p = &(*p)->rb_right;
 304                 else
 305                         return parent;
 306         }
 307
 308         rb_link_node(node, parent, p);
 309         rb_insert_color(node, root);
 310         return NULL;
 311 }
 312
 313 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 314 {
 315         struct rb_node *n = root->rb_node;
 316         struct tree_entry *entry;
 317
 318         while (n) {
 319                 entry = rb_entry(n, struct tree_entry, rb_node);
 320
 321                 if (bytenr < entry->bytenr)
 322                         n = n->rb_left;
 323                 else if (bytenr > entry->bytenr)
 324                         n = n->rb_right;
 325                 else
 326                         return n;
 327         }
 328         return NULL;
 329 }
 330
 331 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 332 {
 333
 334         struct btrfs_fs_info *fs_info = NULL;
 335         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 336                                               rb_node);
 337         if (bnode->root)
 338                 fs_info = bnode->root->fs_info;
 339         btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 340                     "found at offset %llu", bytenr);
 341 }
 342
 343 /*
 344  * walk up backref nodes until reach node presents tree root
 345  */
 346 static struct backref_node *walk_up_backref(struct backref_node *node,
 347                                             struct backref_edge *edges[],
 348                                             int *index)
 349 {
 350         struct backref_edge *edge;
 351         int idx = *index;
 352
 353         while (!list_empty(&node->upper)) {
 354                 edge = list_entry(node->upper.next,
 355                                   struct backref_edge, list[LOWER]);
 356                 edges[idx++] = edge;
 357                 node = edge->node[UPPER];
 358         }
 359         BUG_ON(node->detached);
 360         *index = idx;
 361         return node;
 362 }
 363
 364 /*
 365  * walk down backref nodes to find start of next reference path
 366  */
 367 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 368                                               int *index)
 369 {
 370         struct backref_edge *edge;
 371         struct backref_node *lower;
 372         int idx = *index;
 373
 374         while (idx > 0) {
 375                 edge = edges[idx - 1];
 376                 lower = edge->node[LOWER];
 377                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 378                         idx--;
 379                         continue;
 380                 }
 381                 edge = list_entry(edge->list[LOWER].next,
 382                                   struct backref_edge, list[LOWER]);
 383                 edges[idx - 1] = edge;
 384                 *index = idx;
 385                 return edge->node[UPPER];
 386         }
 387         *index = 0;
 388         return NULL;
 389 }
 390
 391 static void unlock_node_buffer(struct backref_node *node)
 392 {
 393         if (node->locked) {
 394                 btrfs_tree_unlock(node->eb);
 395                 node->locked = 0;
 396         }
 397 }
 398
 399 static void drop_node_buffer(struct backref_node *node)
 400 {
 401         if (node->eb) {
 402                 unlock_node_buffer(node);
 403                 free_extent_buffer(node->eb);
 404                 node->eb = NULL;
 405         }
 406 }
 407
 408 static void drop_backref_node(struct backref_cache *tree,
 409                               struct backref_node *node)
 410 {
 411         BUG_ON(!list_empty(&node->upper));
 412
 413         drop_node_buffer(node);
 414         list_del(&node->list);
 415         list_del(&node->lower);
 416         if (!RB_EMPTY_NODE(&node->rb_node))
 417                 rb_erase(&node->rb_node, &tree->rb_root);
 418         free_backref_node(tree, node);
 419 }
 420
 421 /*
 422  * remove a backref node from the backref cache
 423  */
 424 static void remove_backref_node(struct backref_cache *cache,
 425                                 struct backref_node *node)
 426 {
 427         struct backref_node *upper;
 428         struct backref_edge *edge;
 429
 430         if (!node)
 431                 return;
 432
 433         BUG_ON(!node->lowest && !node->detached);
 434         while (!list_empty(&node->upper)) {
 435                 edge = list_entry(node->upper.next, struct backref_edge,
 436                                   list[LOWER]);
 437                 upper = edge->node[UPPER];
 438                 list_del(&edge->list[LOWER]);
 439                 list_del(&edge->list[UPPER]);
 440                 free_backref_edge(cache, edge);
 441
 442                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 443                         BUG_ON(!list_empty(&node->upper));
 444                         drop_backref_node(cache, node);
 445                         node = upper;
 446                         node->lowest = 1;
 447                         continue;
 448                 }
 449                 /*
 450                  * add the node to leaf node list if no other
 451                  * child block cached.
 452                  */
 453                 if (list_empty(&upper->lower)) {
 454                         list_add_tail(&upper->lower, &cache->leaves);
 455                         upper->lowest = 1;
 456                 }
 457         }
 458
 459         drop_backref_node(cache, node);
 460 }
 461
 462 static void update_backref_node(struct backref_cache *cache,
 463                                 struct backref_node *node, u64 bytenr)
 464 {
 465         struct rb_node *rb_node;
 466         rb_erase(&node->rb_node, &cache->rb_root);
 467         node->bytenr = bytenr;
 468         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 469         if (rb_node)
 470                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 471 }
 472
 473 /*
 474  * update backref cache after a transaction commit
 475  */
 476 static int update_backref_cache(struct btrfs_trans_handle *trans,
 477                                 struct backref_cache *cache)
 478 {
 479         struct backref_node *node;
 480         int level = 0;
 481
 482         if (cache->last_trans == 0) {
 483                 cache->last_trans = trans->transid;
 484                 return 0;
 485         }
 486
 487         if (cache->last_trans == trans->transid)
 488                 return 0;
 489
 490         /*
 491          * detached nodes are used to avoid unnecessary backref
 492          * lookup. transaction commit changes the extent tree.
 493          * so the detached nodes are no longer useful.
 494          */
 495         while (!list_empty(&cache->detached)) {
 496                 node = list_entry(cache->detached.next,
 497                                   struct backref_node, list);
 498                 remove_backref_node(cache, node);
 499         }
 500
 501         while (!list_empty(&cache->changed)) {
 502                 node = list_entry(cache->changed.next,
 503                                   struct backref_node, list);
 504                 list_del_init(&node->list);
 505                 BUG_ON(node->pending);
 506                 update_backref_node(cache, node, node->new_bytenr);
 507         }
 508
 509         /*
 510          * some nodes can be left in the pending list if there were
 511          * errors during processing the pending nodes.
 512          */
 513         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 514                 list_for_each_entry(node, &cache->pending[level], list) {
 515                         BUG_ON(!node->pending);
 516                         if (node->bytenr == node->new_bytenr)
 517                                 continue;
 518                         update_backref_node(cache, node, node->new_bytenr);
 519                 }
 520         }
 521
 522         cache->last_trans = 0;
 523         return 1;
 524 }
 525
 526
 527 static int should_ignore_root(struct btrfs_root *root)
 528 {
 529         struct btrfs_root *reloc_root;
 530
 531         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 532                 return 0;
 533
 534         reloc_root = root->reloc_root;
 535         if (!reloc_root)
 536                 return 0;
 537
 538         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 539             root->fs_info->running_transaction->transid - 1)
 540                 return 0;
 541         /*
 542          * if there is reloc tree and it was created in previous
 543          * transaction backref lookup can find the reloc tree,
 544          * so backref node for the fs tree root is useless for
 545          * relocation.
 546          */
 547         return 1;
 548 }
 549 /*
 550  * find reloc tree by address of tree root
 551  */
 552 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 553                                           u64 bytenr)
 554 {
 555         struct rb_node *rb_node;
 556         struct mapping_node *node;
 557         struct btrfs_root *root = NULL;
 558
 559         spin_lock(&rc->reloc_root_tree.lock);
 560         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 561         if (rb_node) {
 562                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 563                 root = (struct btrfs_root *)node->data;
 564         }
 565         spin_unlock(&rc->reloc_root_tree.lock);
 566         return root;
 567 }
 568
 569 static int is_cowonly_root(u64 root_objectid)
 570 {
 571         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 572             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 573             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 574             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 575             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 576             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 577             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 578             root_objectid == BTRFS_QUOTA_TREE_OBJECTID)
 579                 return 1;
 580         return 0;
 581 }
 582
 583 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 584                                         u64 root_objectid)
 585 {
 586         struct btrfs_key key;
 587
 588         key.objectid = root_objectid;
 589         key.type = BTRFS_ROOT_ITEM_KEY;
 590         if (is_cowonly_root(root_objectid))
 591                 key.offset = 0;
 592         else
 593                 key.offset = (u64)-1;
 594
 595         return btrfs_get_fs_root(fs_info, &key, false);
 596 }
 597
 598 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 599 static noinline_for_stack
 600 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 601                                   struct extent_buffer *leaf,
 602                                   struct btrfs_extent_ref_v0 *ref0)
 603 {
 604         struct btrfs_root *root;
 605         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 606         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 607
 608         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 609
 610         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 611         BUG_ON(IS_ERR(root));
 612
 613         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 614             generation != btrfs_root_generation(&root->root_item))
 615                 return NULL;
 616
 617         return root;
 618 }
 619 #endif
 620
 621 static noinline_for_stack
 622 int find_inline_backref(struct extent_buffer *leaf, int slot,
 623                         unsigned long *ptr, unsigned long *end)
 624 {
 625         struct btrfs_key key;
 626         struct btrfs_extent_item *ei;
 627         struct btrfs_tree_block_info *bi;
 628         u32 item_size;
 629
 630         btrfs_item_key_to_cpu(leaf, &key, slot);
 631
 632         item_size = btrfs_item_size_nr(leaf, slot);
 633 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 634         if (item_size < sizeof(*ei)) {
 635                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 636                 return 1;
 637         }
 638 #endif
 639         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 640         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 641                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 642
 643         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 644             item_size <= sizeof(*ei) + sizeof(*bi)) {
 645                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 646                 return 1;
 647         }
 648         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 649             item_size <= sizeof(*ei)) {
 650                 WARN_ON(item_size < sizeof(*ei));
 651                 return 1;
 652         }
 653
 654         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 655                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 656                 *ptr = (unsigned long)(bi + 1);
 657         } else {
 658                 *ptr = (unsigned long)(ei + 1);
 659         }
 660         *end = (unsigned long)ei + item_size;
 661         return 0;
 662 }
 663
 664 /*
 665  * build backref tree for a given tree block. root of the backref tree
 666  * corresponds the tree block, leaves of the backref tree correspond
 667  * roots of b-trees that reference the tree block.
 668  *
 669  * the basic idea of this function is check backrefs of a given block
 670  * to find upper level blocks that refernece the block, and then check
 671  * bakcrefs of these upper level blocks recursively. the recursion stop
 672  * when tree root is reached or backrefs for the block is cached.
 673  *
 674  * NOTE: if we find backrefs for a block are cached, we know backrefs
 675  * for all upper level blocks that directly/indirectly reference the
 676  * block are also cached.
 677  */
 678 static noinline_for_stack
 679 struct backref_node *build_backref_tree(struct reloc_control *rc,
 680                                         struct btrfs_key *node_key,
 681                                         int level, u64 bytenr)
 682 {
 683         struct backref_cache *cache = &rc->backref_cache;
 684         struct btrfs_path *path1;
 685         struct btrfs_path *path2;
 686         struct extent_buffer *eb;
 687         struct btrfs_root *root;
 688         struct backref_node *cur;
 689         struct backref_node *upper;
 690         struct backref_node *lower;
 691         struct backref_node *node = NULL;
 692         struct backref_node *exist = NULL;
 693         struct backref_edge *edge;
 694         struct rb_node *rb_node;
 695         struct btrfs_key key;
 696         unsigned long end;
 697         unsigned long ptr;
 698         LIST_HEAD(list);
 699         LIST_HEAD(useless);
 700         int cowonly;
 701         int ret;
 702         int err = 0;
 703         bool need_check = true;
 704
 705         path1 = btrfs_alloc_path();
 706         path2 = btrfs_alloc_path();
 707         if (!path1 || !path2) {
 708                 err = -ENOMEM;
 709                 goto out;
 710         }
 711         path1->reada = 1;
 712         path2->reada = 2;
 713
 714         node = alloc_backref_node(cache);
 715         if (!node) {
 716                 err = -ENOMEM;
 717                 goto out;
 718         }
 719
 720         node->bytenr = bytenr;
 721         node->level = level;
 722         node->lowest = 1;
 723         cur = node;
 724 again:
 725         end = 0;
 726         ptr = 0;
 727         key.objectid = cur->bytenr;
 728         key.type = BTRFS_METADATA_ITEM_KEY;
 729         key.offset = (u64)-1;
 730
 731         path1->search_commit_root = 1;
 732         path1->skip_locking = 1;
 733         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 734                                 0, 0);
 735         if (ret < 0) {
 736                 err = ret;
 737                 goto out;
 738         }
 739         ASSERT(ret);
 740         ASSERT(path1->slots[0]);
 741
 742         path1->slots[0]--;
 743
 744         WARN_ON(cur->checked);
 745         if (!list_empty(&cur->upper)) {
 746                 /*
 747                  * the backref was added previously when processing
 748                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 749                  */
 750                 ASSERT(list_is_singular(&cur->upper));
 751                 edge = list_entry(cur->upper.next, struct backref_edge,
 752                                   list[LOWER]);
 753                 ASSERT(list_empty(&edge->list[UPPER]));
 754                 exist = edge->node[UPPER];
 755                 /*
 756                  * add the upper level block to pending list if we need
 757                  * check its backrefs
 758                  */
 759                 if (!exist->checked)
 760                         list_add_tail(&edge->list[UPPER], &list);
 761         } else {
 762                 exist = NULL;
 763         }
 764
 765         while (1) {
 766                 cond_resched();
 767                 eb = path1->nodes[0];
 768
 769                 if (ptr >= end) {
 770                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 771                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 772                                 if (ret < 0) {
 773                                         err = ret;
 774                                         goto out;
 775                                 }
 776                                 if (ret > 0)
 777                                         break;
 778                                 eb = path1->nodes[0];
 779                         }
 780
 781                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 782                         if (key.objectid != cur->bytenr) {
 783                                 WARN_ON(exist);
 784                                 break;
 785                         }
 786
 787                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 788                             key.type == BTRFS_METADATA_ITEM_KEY) {
 789                                 ret = find_inline_backref(eb, path1->slots[0],
 790                                                           &ptr, &end);
 791                                 if (ret)
 792                                         goto next;
 793                         }
 794                 }
 795
 796                 if (ptr < end) {
 797                         /* update key for inline back ref */
 798                         struct btrfs_extent_inline_ref *iref;
 799                         iref = (struct btrfs_extent_inline_ref *)ptr;
 800                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 801                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 802                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 803                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 804                 }
 805
 806                 if (exist &&
 807                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 808                       exist->owner == key.offset) ||
 809                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 810                       exist->bytenr == key.offset))) {
 811                         exist = NULL;
 812                         goto next;
 813                 }
 814
 815 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 816                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 817                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 818                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 819                                 struct btrfs_extent_ref_v0 *ref0;
 820                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 821                                                 struct btrfs_extent_ref_v0);
 822                                 if (key.objectid == key.offset) {
 823                                         root = find_tree_root(rc, eb, ref0);
 824                                         if (root && !should_ignore_root(root))
 825                                                 cur->root = root;
 826                                         else
 827                                                 list_add(&cur->list, &useless);
 828                                         break;
 829                                 }
 830                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 831                                                                       ref0)))
 832                                         cur->cowonly = 1;
 833                         }
 834 #else
 835                 ASSERT(key.type != BTRFS_EXTENT_REF_V0_KEY);
 836                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 837 #endif
 838                         if (key.objectid == key.offset) {
 839                                 /*
 840                                  * only root blocks of reloc trees use
 841                                  * backref of this type.
 842                                  */
 843                                 root = find_reloc_root(rc, cur->bytenr);
 844                                 ASSERT(root);
 845                                 cur->root = root;
 846                                 break;
 847                         }
 848
 849                         edge = alloc_backref_edge(cache);
 850                         if (!edge) {
 851                                 err = -ENOMEM;
 852                                 goto out;
 853                         }
 854                         rb_node = tree_search(&cache->rb_root, key.offset);
 855                         if (!rb_node) {
 856                                 upper = alloc_backref_node(cache);
 857                                 if (!upper) {
 858                                         free_backref_edge(cache, edge);
 859                                         err = -ENOMEM;
 860                                         goto out;
 861                                 }
 862                                 upper->bytenr = key.offset;
 863                                 upper->level = cur->level + 1;
 864                                 /*
 865                                  *  backrefs for the upper level block isn't
 866                                  *  cached, add the block to pending list
 867                                  */
 868                                 list_add_tail(&edge->list[UPPER], &list);
 869                         } else {
 870                                 upper = rb_entry(rb_node, struct backref_node,
 871                                                  rb_node);
 872                                 ASSERT(upper->checked);
 873                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 874                         }
 875                         list_add_tail(&edge->list[LOWER], &cur->upper);
 876                         edge->node[LOWER] = cur;
 877                         edge->node[UPPER] = upper;
 878
 879                         goto next;
 880                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 881                         goto next;
 882                 }
 883
 884                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 885                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 886                 if (IS_ERR(root)) {
 887                         err = PTR_ERR(root);
 888                         goto out;
 889                 }
 890
 891                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 892                         cur->cowonly = 1;
 893
 894                 if (btrfs_root_level(&root->root_item) == cur->level) {
 895                         /* tree root */
 896                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
 897                                cur->bytenr);
 898                         if (should_ignore_root(root))
 899                                 list_add(&cur->list, &useless);
 900                         else
 901                                 cur->root = root;
 902                         break;
 903                 }
 904
 905                 level = cur->level + 1;
 906
 907                 /*
 908                  * searching the tree to find upper level blocks
 909                  * reference the block.
 910                  */
 911                 path2->search_commit_root = 1;
 912                 path2->skip_locking = 1;
 913                 path2->lowest_level = level;
 914                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 915                 path2->lowest_level = 0;
 916                 if (ret < 0) {
 917                         err = ret;
 918                         goto out;
 919                 }
 920                 if (ret > 0 && path2->slots[level] > 0)
 921                         path2->slots[level]--;
 922
 923                 eb = path2->nodes[level];
 924                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 925                         cur->bytenr);
 926
 927                 lower = cur;
 928                 need_check = true;
 929                 for (; level < BTRFS_MAX_LEVEL; level++) {
 930                         if (!path2->nodes[level]) {
 931                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
 932                                        lower->bytenr);
 933                                 if (should_ignore_root(root))
 934                                         list_add(&lower->list, &useless);
 935                                 else
 936                                         lower->root = root;
 937                                 break;
 938                         }
 939
 940                         edge = alloc_backref_edge(cache);
 941                         if (!edge) {
 942                                 err = -ENOMEM;
 943                                 goto out;
 944                         }
 945
 946                         eb = path2->nodes[level];
 947                         rb_node = tree_search(&cache->rb_root, eb->start);
 948                         if (!rb_node) {
 949                                 upper = alloc_backref_node(cache);
 950                                 if (!upper) {
 951                                         free_backref_edge(cache, edge);
 952                                         err = -ENOMEM;
 953                                         goto out;
 954                                 }
 955                                 upper->bytenr = eb->start;
 956                                 upper->owner = btrfs_header_owner(eb);
 957                                 upper->level = lower->level + 1;
 958                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 959                                               &root->state))
 960                                         upper->cowonly = 1;
 961
 962                                 /*
 963                                  * if we know the block isn't shared
 964                                  * we can void checking its backrefs.
 965                                  */
 966                                 if (btrfs_block_can_be_shared(root, eb))
 967                                         upper->checked = 0;
 968                                 else
 969                                         upper->checked = 1;
 970
 971                                 /*
 972                                  * add the block to pending list if we
 973                                  * need check its backrefs, we only do this once
 974                                  * while walking up a tree as we will catch
 975                                  * anything else later on.
 976                                  */
 977                                 if (!upper->checked && need_check) {
 978                                         need_check = false;
 979                                         list_add_tail(&edge->list[UPPER],
 980                                                       &list);
 981                                 } else {
 982                                         if (upper->checked)
 983                                                 need_check = true;
 984                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 985                                 }
 986                         } else {
 987                                 upper = rb_entry(rb_node, struct backref_node,
 988                                                  rb_node);
 989                                 ASSERT(upper->checked);
 990                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 991                                 if (!upper->owner)
 992                                         upper->owner = btrfs_header_owner(eb);
 993                         }
 994                         list_add_tail(&edge->list[LOWER], &lower->upper);
 995                         edge->node[LOWER] = lower;
 996                         edge->node[UPPER] = upper;
 997
 998                         if (rb_node)
 999                                 break;
1000                         lower = upper;
1001                         upper = NULL;
1002                 }
1003                 btrfs_release_path(path2);
1004 next:
1005                 if (ptr < end) {
1006                         ptr += btrfs_extent_inline_ref_size(key.type);
1007                         if (ptr >= end) {
1008                                 WARN_ON(ptr > end);
1009                                 ptr = 0;
1010                                 end = 0;
1011                         }
1012                 }
1013                 if (ptr >= end)
1014                         path1->slots[0]++;
1015         }
1016         btrfs_release_path(path1);
1017
1018         cur->checked = 1;
1019         WARN_ON(exist);
1020
1021         /* the pending list isn't empty, take the first block to process */
1022         if (!list_empty(&list)) {
1023                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1024                 list_del_init(&edge->list[UPPER]);
1025                 cur = edge->node[UPPER];
1026                 goto again;
1027         }
1028
1029         /*
1030          * everything goes well, connect backref nodes and insert backref nodes
1031          * into the cache.
1032          */
1033         ASSERT(node->checked);
1034         cowonly = node->cowonly;
1035         if (!cowonly) {
1036                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1037                                       &node->rb_node);
1038                 if (rb_node)
1039                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1040                 list_add_tail(&node->lower, &cache->leaves);
1041         }
1042
1043         list_for_each_entry(edge, &node->upper, list[LOWER])
1044                 list_add_tail(&edge->list[UPPER], &list);
1045
1046         while (!list_empty(&list)) {
1047                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1048                 list_del_init(&edge->list[UPPER]);
1049                 upper = edge->node[UPPER];
1050                 if (upper->detached) {
1051                         list_del(&edge->list[LOWER]);
1052                         lower = edge->node[LOWER];
1053                         free_backref_edge(cache, edge);
1054                         if (list_empty(&lower->upper))
1055                                 list_add(&lower->list, &useless);
1056                         continue;
1057                 }
1058
1059                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1060                         if (upper->lowest) {
1061                                 list_del_init(&upper->lower);
1062                                 upper->lowest = 0;
1063                         }
1064
1065                         list_add_tail(&edge->list[UPPER], &upper->lower);
1066                         continue;
1067                 }
1068
1069                 if (!upper->checked) {
1070                         /*
1071                          * Still want to blow up for developers since this is a
1072                          * logic bug.
1073                          */
1074                         ASSERT(0);
1075                         err = -EINVAL;
1076                         goto out;
1077                 }
1078                 if (cowonly != upper->cowonly) {
1079                         ASSERT(0);
1080                         err = -EINVAL;
1081                         goto out;
1082                 }
1083
1084                 if (!cowonly) {
1085                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1086                                               &upper->rb_node);
1087                         if (rb_node)
1088                                 backref_tree_panic(rb_node, -EEXIST,
1089                                                    upper->bytenr);
1090                 }
1091
1092                 list_add_tail(&edge->list[UPPER], &upper->lower);
1093
1094                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1095                         list_add_tail(&edge->list[UPPER], &list);
1096         }
1097         /*
1098          * process useless backref nodes. backref nodes for tree leaves
1099          * are deleted from the cache. backref nodes for upper level
1100          * tree blocks are left in the cache to avoid unnecessary backref
1101          * lookup.
1102          */
1103         while (!list_empty(&useless)) {
1104                 upper = list_entry(useless.next, struct backref_node, list);
1105                 list_del_init(&upper->list);
1106                 ASSERT(list_empty(&upper->upper));
1107                 if (upper == node)
1108                         node = NULL;
1109                 if (upper->lowest) {
1110                         list_del_init(&upper->lower);
1111                         upper->lowest = 0;
1112                 }
1113                 while (!list_empty(&upper->lower)) {
1114                         edge = list_entry(upper->lower.next,
1115                                           struct backref_edge, list[UPPER]);
1116                         list_del(&edge->list[UPPER]);
1117                         list_del(&edge->list[LOWER]);
1118                         lower = edge->node[LOWER];
1119                         free_backref_edge(cache, edge);
1120
1121                         if (list_empty(&lower->upper))
1122                                 list_add(&lower->list, &useless);
1123                 }
1124                 __mark_block_processed(rc, upper);
1125                 if (upper->level > 0) {
1126                         list_add(&upper->list, &cache->detached);
1127                         upper->detached = 1;
1128                 } else {
1129                         rb_erase(&upper->rb_node, &cache->rb_root);
1130                         free_backref_node(cache, upper);
1131                 }
1132         }
1133 out:
1134         btrfs_free_path(path1);
1135         btrfs_free_path(path2);
1136         if (err) {
1137                 while (!list_empty(&useless)) {
1138                         lower = list_entry(useless.next,
1139                                            struct backref_node, list);
1140                         list_del_init(&lower->list);
1141                 }
1142                 while (!list_empty(&list)) {
1143                         edge = list_first_entry(&list, struct backref_edge,
1144                                                 list[UPPER]);
1145                         list_del(&edge->list[UPPER]);
1146                         list_del(&edge->list[LOWER]);
1147                         lower = edge->node[LOWER];
1148                         upper = edge->node[UPPER];
1149                         free_backref_edge(cache, edge);
1150
1151                         /*
1152                          * Lower is no longer linked to any upper backref nodes
1153                          * and isn't in the cache, we can free it ourselves.
1154                          */
1155                         if (list_empty(&lower->upper) &&
1156                             RB_EMPTY_NODE(&lower->rb_node))
1157                                 list_add(&lower->list, &useless);
1158
1159                         if (!RB_EMPTY_NODE(&upper->rb_node))
1160                                 continue;
1161
1162                         /* Add this guy's upper edges to the list to proces */
1163                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1164                                 list_add_tail(&edge->list[UPPER], &list);
1165                         if (list_empty(&upper->upper))
1166                                 list_add(&upper->list, &useless);
1167                 }
1168
1169                 while (!list_empty(&useless)) {
1170                         lower = list_entry(useless.next,
1171                                            struct backref_node, list);
1172                         list_del_init(&lower->list);
1173                         free_backref_node(cache, lower);
1174                 }
1175                 return ERR_PTR(err);
1176         }
1177         ASSERT(!node || !node->detached);
1178         return node;
1179 }
1180
1181 /*
1182  * helper to add backref node for the newly created snapshot.
1183  * the backref node is created by cloning backref node that
1184  * corresponds to root of source tree
1185  */
1186 static int clone_backref_node(struct btrfs_trans_handle *trans,
1187                               struct reloc_control *rc,
1188                               struct btrfs_root *src,
1189                               struct btrfs_root *dest)
1190 {
1191         struct btrfs_root *reloc_root = src->reloc_root;
1192         struct backref_cache *cache = &rc->backref_cache;
1193         struct backref_node *node = NULL;
1194         struct backref_node *new_node;
1195         struct backref_edge *edge;
1196         struct backref_edge *new_edge;
1197         struct rb_node *rb_node;
1198
1199         if (cache->last_trans > 0)
1200                 update_backref_cache(trans, cache);
1201
1202         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1203         if (rb_node) {
1204                 node = rb_entry(rb_node, struct backref_node, rb_node);
1205                 if (node->detached)
1206                         node = NULL;
1207                 else
1208                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1209         }
1210
1211         if (!node) {
1212                 rb_node = tree_search(&cache->rb_root,
1213                                       reloc_root->commit_root->start);
1214                 if (rb_node) {
1215                         node = rb_entry(rb_node, struct backref_node,
1216                                         rb_node);
1217                         BUG_ON(node->detached);
1218                 }
1219         }
1220
1221         if (!node)
1222                 return 0;
1223
1224         new_node = alloc_backref_node(cache);
1225         if (!new_node)
1226                 return -ENOMEM;
1227
1228         new_node->bytenr = dest->node->start;
1229         new_node->level = node->level;
1230         new_node->lowest = node->lowest;
1231         new_node->checked = 1;
1232         new_node->root = dest;
1233
1234         if (!node->lowest) {
1235                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1236                         new_edge = alloc_backref_edge(cache);
1237                         if (!new_edge)
1238                                 goto fail;
1239
1240                         new_edge->node[UPPER] = new_node;
1241                         new_edge->node[LOWER] = edge->node[LOWER];
1242                         list_add_tail(&new_edge->list[UPPER],
1243                                       &new_node->lower);
1244                 }
1245         } else {
1246                 list_add_tail(&new_node->lower, &cache->leaves);
1247         }
1248
1249         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1250                               &new_node->rb_node);
1251         if (rb_node)
1252                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1253
1254         if (!new_node->lowest) {
1255                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1256                         list_add_tail(&new_edge->list[LOWER],
1257                                       &new_edge->node[LOWER]->upper);
1258                 }
1259         }
1260         return 0;
1261 fail:
1262         while (!list_empty(&new_node->lower)) {
1263                 new_edge = list_entry(new_node->lower.next,
1264                                       struct backref_edge, list[UPPER]);
1265                 list_del(&new_edge->list[UPPER]);
1266                 free_backref_edge(cache, new_edge);
1267         }
1268         free_backref_node(cache, new_node);
1269         return -ENOMEM;
1270 }
1271
1272 /*
1273  * helper to add 'address of tree root -> reloc tree' mapping
1274  */
1275 static int __must_check __add_reloc_root(struct btrfs_root *root)
1276 {
1277         struct rb_node *rb_node;
1278         struct mapping_node *node;
1279         struct reloc_control *rc = root->fs_info->reloc_ctl;
1280
1281         node = kmalloc(sizeof(*node), GFP_NOFS);
1282         if (!node)
1283                 return -ENOMEM;
1284
1285         node->bytenr = root->node->start;
1286         node->data = root;
1287
1288         spin_lock(&rc->reloc_root_tree.lock);
1289         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1290                               node->bytenr, &node->rb_node);
1291         spin_unlock(&rc->reloc_root_tree.lock);
1292         if (rb_node) {
1293                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1294                             "for start=%llu while inserting into relocation "
1295                             "tree", node->bytenr);
1296                 kfree(node);
1297                 return -EEXIST;
1298         }
1299
1300         list_add_tail(&root->root_list, &rc->reloc_roots);
1301         return 0;
1302 }
1303
1304 /*
1305  * helper to delete the 'address of tree root -> reloc tree'
1306  * mapping
1307  */
1308 static void __del_reloc_root(struct btrfs_root *root)
1309 {
1310         struct rb_node *rb_node;
1311         struct mapping_node *node = NULL;
1312         struct reloc_control *rc = root->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;
1325         BUG_ON((struct btrfs_root *)node->data != root);
1326
1327         spin_lock(&root->fs_info->trans_lock);
1328         list_del_init(&root->root_list);
1329         spin_unlock(&root->fs_info->trans_lock);
1330         kfree(node);
1331 }
1332
1333 /*
1334  * helper to update the 'address of tree root -> reloc tree'
1335  * mapping
1336  */
1337 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1338 {
1339         struct rb_node *rb_node;
1340         struct mapping_node *node = NULL;
1341         struct reloc_control *rc = root->fs_info->reloc_ctl;
1342
1343         spin_lock(&rc->reloc_root_tree.lock);
1344         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1345                               root->node->start);
1346         if (rb_node) {
1347                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1348                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1349         }
1350         spin_unlock(&rc->reloc_root_tree.lock);
1351
1352         if (!node)
1353                 return 0;
1354         BUG_ON((struct btrfs_root *)node->data != root);
1355
1356         spin_lock(&rc->reloc_root_tree.lock);
1357         node->bytenr = new_bytenr;
1358         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1359                               node->bytenr, &node->rb_node);
1360         spin_unlock(&rc->reloc_root_tree.lock);
1361         if (rb_node)
1362                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1363         return 0;
1364 }
1365
1366 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1367                                         struct btrfs_root *root, u64 objectid)
1368 {
1369         struct btrfs_root *reloc_root;
1370         struct extent_buffer *eb;
1371         struct btrfs_root_item *root_item;
1372         struct btrfs_key root_key;
1373         u64 last_snap = 0;
1374         int ret;
1375
1376         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1377         BUG_ON(!root_item);
1378
1379         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1380         root_key.type = BTRFS_ROOT_ITEM_KEY;
1381         root_key.offset = objectid;
1382
1383         if (root->root_key.objectid == objectid) {
1384                 /* called by btrfs_init_reloc_root */
1385                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1386                                       BTRFS_TREE_RELOC_OBJECTID);
1387                 BUG_ON(ret);
1388
1389                 last_snap = btrfs_root_last_snapshot(&root->root_item);
1390                 btrfs_set_root_last_snapshot(&root->root_item,
1391                                              trans->transid - 1);
1392         } else {
1393                 /*
1394                  * called by btrfs_reloc_post_snapshot_hook.
1395                  * the source tree is a reloc tree, all tree blocks
1396                  * modified after it was created have RELOC flag
1397                  * set in their headers. so it's OK to not update
1398                  * the 'last_snapshot'.
1399                  */
1400                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1401                                       BTRFS_TREE_RELOC_OBJECTID);
1402                 BUG_ON(ret);
1403         }
1404
1405         memcpy(root_item, &root->root_item, sizeof(*root_item));
1406         btrfs_set_root_bytenr(root_item, eb->start);
1407         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1408         btrfs_set_root_generation(root_item, trans->transid);
1409
1410         if (root->root_key.objectid == objectid) {
1411                 btrfs_set_root_refs(root_item, 0);
1412                 memset(&root_item->drop_progress, 0,
1413                        sizeof(struct btrfs_disk_key));
1414                 root_item->drop_level = 0;
1415                 /*
1416                  * abuse rtransid, it is safe because it is impossible to
1417                  * receive data into a relocation tree.
1418                  */
1419                 btrfs_set_root_rtransid(root_item, last_snap);
1420                 btrfs_set_root_otransid(root_item, trans->transid);
1421         }
1422
1423         btrfs_tree_unlock(eb);
1424         free_extent_buffer(eb);
1425
1426         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1427                                 &root_key, root_item);
1428         BUG_ON(ret);
1429         kfree(root_item);
1430
1431         reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
1432         BUG_ON(IS_ERR(reloc_root));
1433         reloc_root->last_trans = trans->transid;
1434         return reloc_root;
1435 }
1436
1437 /*
1438  * create reloc tree for a given fs tree. reloc tree is just a
1439  * snapshot of the fs tree with special root objectid.
1440  */
1441 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1442                           struct btrfs_root *root)
1443 {
1444         struct btrfs_root *reloc_root;
1445         struct reloc_control *rc = root->fs_info->reloc_ctl;
1446         struct btrfs_block_rsv *rsv;
1447         int clear_rsv = 0;
1448         int ret;
1449
1450         if (root->reloc_root) {
1451                 reloc_root = root->reloc_root;
1452                 reloc_root->last_trans = trans->transid;
1453                 return 0;
1454         }
1455
1456         if (!rc || !rc->create_reloc_tree ||
1457             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1458                 return 0;
1459
1460         if (!trans->reloc_reserved) {
1461                 rsv = trans->block_rsv;
1462                 trans->block_rsv = rc->block_rsv;
1463                 clear_rsv = 1;
1464         }
1465         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1466         if (clear_rsv)
1467                 trans->block_rsv = rsv;
1468
1469         ret = __add_reloc_root(reloc_root);
1470         BUG_ON(ret < 0);
1471         root->reloc_root = reloc_root;
1472         return 0;
1473 }
1474
1475 /*
1476  * update root item of reloc tree
1477  */
1478 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1479                             struct btrfs_root *root)
1480 {
1481         struct btrfs_root *reloc_root;
1482         struct btrfs_root_item *root_item;
1483         int ret;
1484
1485         if (!root->reloc_root)
1486                 goto out;
1487
1488         reloc_root = root->reloc_root;
1489         root_item = &reloc_root->root_item;
1490
1491         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1492             btrfs_root_refs(root_item) == 0) {
1493                 root->reloc_root = NULL;
1494                 __del_reloc_root(reloc_root);
1495         }
1496
1497         if (reloc_root->commit_root != reloc_root->node) {
1498                 btrfs_set_root_node(root_item, reloc_root->node);
1499                 free_extent_buffer(reloc_root->commit_root);
1500                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1501         }
1502
1503         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1504                                 &reloc_root->root_key, root_item);
1505         BUG_ON(ret);
1506
1507 out:
1508         return 0;
1509 }
1510
1511 /*
1512  * helper to find first cached inode with inode number >= objectid
1513  * in a subvolume
1514  */
1515 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1516 {
1517         struct rb_node *node;
1518         struct rb_node *prev;
1519         struct btrfs_inode *entry;
1520         struct inode *inode;
1521
1522         spin_lock(&root->inode_lock);
1523 again:
1524         node = root->inode_tree.rb_node;
1525         prev = NULL;
1526         while (node) {
1527                 prev = node;
1528                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1529
1530                 if (objectid < btrfs_ino(&entry->vfs_inode))
1531                         node = node->rb_left;
1532                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1533                         node = node->rb_right;
1534                 else
1535                         break;
1536         }
1537         if (!node) {
1538                 while (prev) {
1539                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1540                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1541                                 node = prev;
1542                                 break;
1543                         }
1544                         prev = rb_next(prev);
1545                 }
1546         }
1547         while (node) {
1548                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1549                 inode = igrab(&entry->vfs_inode);
1550                 if (inode) {
1551                         spin_unlock(&root->inode_lock);
1552                         return inode;
1553                 }
1554
1555                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1556                 if (cond_resched_lock(&root->inode_lock))
1557                         goto again;
1558
1559                 node = rb_next(node);
1560         }
1561         spin_unlock(&root->inode_lock);
1562         return NULL;
1563 }
1564
1565 static int in_block_group(u64 bytenr,
1566                           struct btrfs_block_group_cache *block_group)
1567 {
1568         if (bytenr >= block_group->key.objectid &&
1569             bytenr < block_group->key.objectid + block_group->key.offset)
1570                 return 1;
1571         return 0;
1572 }
1573
1574 /*
1575  * get new location of data
1576  */
1577 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1578                             u64 bytenr, u64 num_bytes)
1579 {
1580         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1581         struct btrfs_path *path;
1582         struct btrfs_file_extent_item *fi;
1583         struct extent_buffer *leaf;
1584         int ret;
1585
1586         path = btrfs_alloc_path();
1587         if (!path)
1588                 return -ENOMEM;
1589
1590         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1591         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1592                                        bytenr, 0);
1593         if (ret < 0)
1594                 goto out;
1595         if (ret > 0) {
1596                 ret = -ENOENT;
1597                 goto out;
1598         }
1599
1600         leaf = path->nodes[0];
1601         fi = btrfs_item_ptr(leaf, path->slots[0],
1602                             struct btrfs_file_extent_item);
1603
1604         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1605                btrfs_file_extent_compression(leaf, fi) ||
1606                btrfs_file_extent_encryption(leaf, fi) ||
1607                btrfs_file_extent_other_encoding(leaf, fi));
1608
1609         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1610                 ret = -EINVAL;
1611                 goto out;
1612         }
1613
1614         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1615         ret = 0;
1616 out:
1617         btrfs_free_path(path);
1618         return ret;
1619 }
1620
1621 /*
1622  * update file extent items in the tree leaf to point to
1623  * the new locations.
1624  */
1625 static noinline_for_stack
1626 int replace_file_extents(struct btrfs_trans_handle *trans,
1627                          struct reloc_control *rc,
1628                          struct btrfs_root *root,
1629                          struct extent_buffer *leaf)
1630 {
1631         struct btrfs_key key;
1632         struct btrfs_file_extent_item *fi;
1633         struct inode *inode = NULL;
1634         u64 parent;
1635         u64 bytenr;
1636         u64 new_bytenr = 0;
1637         u64 num_bytes;
1638         u64 end;
1639         u32 nritems;
1640         u32 i;
1641         int ret = 0;
1642         int first = 1;
1643         int dirty = 0;
1644
1645         if (rc->stage != UPDATE_DATA_PTRS)
1646                 return 0;
1647
1648         /* reloc trees always use full backref */
1649         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1650                 parent = leaf->start;
1651         else
1652                 parent = 0;
1653
1654         nritems = btrfs_header_nritems(leaf);
1655         for (i = 0; i < nritems; i++) {
1656                 cond_resched();
1657                 btrfs_item_key_to_cpu(leaf, &key, i);
1658                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1659                         continue;
1660                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1661                 if (btrfs_file_extent_type(leaf, fi) ==
1662                     BTRFS_FILE_EXTENT_INLINE)
1663                         continue;
1664                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1665                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1666                 if (bytenr == 0)
1667                         continue;
1668                 if (!in_block_group(bytenr, rc->block_group))
1669                         continue;
1670
1671                 /*
1672                  * if we are modifying block in fs tree, wait for readpage
1673                  * to complete and drop the extent cache
1674                  */
1675                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1676                         if (first) {
1677                                 inode = find_next_inode(root, key.objectid);
1678                                 first = 0;
1679                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1680                                 btrfs_add_delayed_iput(inode);
1681                                 inode = find_next_inode(root, key.objectid);
1682                         }
1683                         if (inode && btrfs_ino(inode) == key.objectid) {
1684                                 end = key.offset +
1685                                       btrfs_file_extent_num_bytes(leaf, fi);
1686                                 WARN_ON(!IS_ALIGNED(key.offset,
1687                                                     root->sectorsize));
1688                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1689                                 end--;
1690                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1691                                                       key.offset, end);
1692                                 if (!ret)
1693                                         continue;
1694
1695                                 btrfs_drop_extent_cache(inode, key.offset, end,
1696                                                         1);
1697                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1698                                               key.offset, end);
1699                         }
1700                 }
1701
1702                 ret = get_new_location(rc->data_inode, &new_bytenr,
1703                                        bytenr, num_bytes);
1704                 if (ret) {
1705                         /*
1706                          * Don't have to abort since we've not changed anything
1707                          * in the file extent yet.
1708                          */
1709                         break;
1710                 }
1711
1712                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1713                 dirty = 1;
1714
1715                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1716                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1717                                            num_bytes, parent,
1718                                            btrfs_header_owner(leaf),
1719                                            key.objectid, key.offset, 1);
1720                 if (ret) {
1721                         btrfs_abort_transaction(trans, root, ret);
1722                         break;
1723                 }
1724
1725                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1726                                         parent, btrfs_header_owner(leaf),
1727                                         key.objectid, key.offset, 1);
1728                 if (ret) {
1729                         btrfs_abort_transaction(trans, root, ret);
1730                         break;
1731                 }
1732         }
1733         if (dirty)
1734                 btrfs_mark_buffer_dirty(leaf);
1735         if (inode)
1736                 btrfs_add_delayed_iput(inode);
1737         return ret;
1738 }
1739
1740 static noinline_for_stack
1741 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1742                      struct btrfs_path *path, int level)
1743 {
1744         struct btrfs_disk_key key1;
1745         struct btrfs_disk_key key2;
1746         btrfs_node_key(eb, &key1, slot);
1747         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1748         return memcmp(&key1, &key2, sizeof(key1));
1749 }
1750
1751 /*
1752  * try to replace tree blocks in fs tree with the new blocks
1753  * in reloc tree. tree blocks haven't been modified since the
1754  * reloc tree was create can be replaced.
1755  *
1756  * if a block was replaced, level of the block + 1 is returned.
1757  * if no block got replaced, 0 is returned. if there are other
1758  * errors, a negative error number is returned.
1759  */
1760 static noinline_for_stack
1761 int replace_path(struct btrfs_trans_handle *trans,
1762                  struct btrfs_root *dest, struct btrfs_root *src,
1763                  struct btrfs_path *path, struct btrfs_key *next_key,
1764                  int lowest_level, int max_level)
1765 {
1766         struct extent_buffer *eb;
1767         struct extent_buffer *parent;
1768         struct btrfs_key key;
1769         u64 old_bytenr;
1770         u64 new_bytenr;
1771         u64 old_ptr_gen;
1772         u64 new_ptr_gen;
1773         u64 last_snapshot;
1774         u32 blocksize;
1775         int cow = 0;
1776         int level;
1777         int ret;
1778         int slot;
1779
1780         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1781         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1782
1783         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1784 again:
1785         slot = path->slots[lowest_level];
1786         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1787
1788         eb = btrfs_lock_root_node(dest);
1789         btrfs_set_lock_blocking(eb);
1790         level = btrfs_header_level(eb);
1791
1792         if (level < lowest_level) {
1793                 btrfs_tree_unlock(eb);
1794                 free_extent_buffer(eb);
1795                 return 0;
1796         }
1797
1798         if (cow) {
1799                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1800                 BUG_ON(ret);
1801         }
1802         btrfs_set_lock_blocking(eb);
1803
1804         if (next_key) {
1805                 next_key->objectid = (u64)-1;
1806                 next_key->type = (u8)-1;
1807                 next_key->offset = (u64)-1;
1808         }
1809
1810         parent = eb;
1811         while (1) {
1812                 level = btrfs_header_level(parent);
1813                 BUG_ON(level < lowest_level);
1814
1815                 ret = btrfs_bin_search(parent, &key, level, &slot);
1816                 if (ret && slot > 0)
1817                         slot--;
1818
1819                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1820                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1821
1822                 old_bytenr = btrfs_node_blockptr(parent, slot);
1823                 blocksize = dest->nodesize;
1824                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1825
1826                 if (level <= max_level) {
1827                         eb = path->nodes[level];
1828                         new_bytenr = btrfs_node_blockptr(eb,
1829                                                         path->slots[level]);
1830                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1831                                                         path->slots[level]);
1832                 } else {
1833                         new_bytenr = 0;
1834                         new_ptr_gen = 0;
1835                 }
1836
1837                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1838                         ret = level;
1839                         break;
1840                 }
1841
1842                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1843                     memcmp_node_keys(parent, slot, path, level)) {
1844                         if (level <= lowest_level) {
1845                                 ret = 0;
1846                                 break;
1847                         }
1848
1849                         eb = read_tree_block(dest, old_bytenr, old_ptr_gen);
1850                         if (IS_ERR(eb)) {
1851                                 ret = PTR_ERR(eb);
1852                         } else if (!extent_buffer_uptodate(eb)) {
1853                                 ret = -EIO;
1854                                 free_extent_buffer(eb);
1855                                 break;
1856                         }
1857                         btrfs_tree_lock(eb);
1858                         if (cow) {
1859                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1860                                                       slot, &eb);
1861                                 BUG_ON(ret);
1862                         }
1863                         btrfs_set_lock_blocking(eb);
1864
1865                         btrfs_tree_unlock(parent);
1866                         free_extent_buffer(parent);
1867
1868                         parent = eb;
1869                         continue;
1870                 }
1871
1872                 if (!cow) {
1873                         btrfs_tree_unlock(parent);
1874                         free_extent_buffer(parent);
1875                         cow = 1;
1876                         goto again;
1877                 }
1878
1879                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1880                                       path->slots[level]);
1881                 btrfs_release_path(path);
1882
1883                 path->lowest_level = level;
1884                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1885                 path->lowest_level = 0;
1886                 BUG_ON(ret);
1887
1888                 /*
1889                  * swap blocks in fs tree and reloc tree.
1890                  */
1891                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1892                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1893                 btrfs_mark_buffer_dirty(parent);
1894
1895                 btrfs_set_node_blockptr(path->nodes[level],
1896                                         path->slots[level], old_bytenr);
1897                 btrfs_set_node_ptr_generation(path->nodes[level],
1898                                               path->slots[level], old_ptr_gen);
1899                 btrfs_mark_buffer_dirty(path->nodes[level]);
1900
1901                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1902                                         path->nodes[level]->start,
1903                                         src->root_key.objectid, level - 1, 0,
1904                                         1);
1905                 BUG_ON(ret);
1906                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1907                                         0, dest->root_key.objectid, level - 1,
1908                                         0, 1);
1909                 BUG_ON(ret);
1910
1911                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1912                                         path->nodes[level]->start,
1913                                         src->root_key.objectid, level - 1, 0,
1914                                         1);
1915                 BUG_ON(ret);
1916
1917                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1918                                         0, dest->root_key.objectid, level - 1,
1919                                         0, 1);
1920                 BUG_ON(ret);
1921
1922                 btrfs_unlock_up_safe(path, 0);
1923
1924                 ret = level;
1925                 break;
1926         }
1927         btrfs_tree_unlock(parent);
1928         free_extent_buffer(parent);
1929         return ret;
1930 }
1931
1932 /*
1933  * helper to find next relocated block in reloc tree
1934  */
1935 static noinline_for_stack
1936 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1937                        int *level)
1938 {
1939         struct extent_buffer *eb;
1940         int i;
1941         u64 last_snapshot;
1942         u32 nritems;
1943
1944         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1945
1946         for (i = 0; i < *level; i++) {
1947                 free_extent_buffer(path->nodes[i]);
1948                 path->nodes[i] = NULL;
1949         }
1950
1951         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1952                 eb = path->nodes[i];
1953                 nritems = btrfs_header_nritems(eb);
1954                 while (path->slots[i] + 1 < nritems) {
1955                         path->slots[i]++;
1956                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1957                             last_snapshot)
1958                                 continue;
1959
1960                         *level = i;
1961                         return 0;
1962                 }
1963                 free_extent_buffer(path->nodes[i]);
1964                 path->nodes[i] = NULL;
1965         }
1966         return 1;
1967 }
1968
1969 /*
1970  * walk down reloc tree to find relocated block of lowest level
1971  */
1972 static noinline_for_stack
1973 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1974                          int *level)
1975 {
1976         struct extent_buffer *eb = NULL;
1977         int i;
1978         u64 bytenr;
1979         u64 ptr_gen = 0;
1980         u64 last_snapshot;
1981         u32 nritems;
1982
1983         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1984
1985         for (i = *level; i > 0; i--) {
1986                 eb = path->nodes[i];
1987                 nritems = btrfs_header_nritems(eb);
1988                 while (path->slots[i] < nritems) {
1989                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1990                         if (ptr_gen > last_snapshot)
1991                                 break;
1992                         path->slots[i]++;
1993                 }
1994                 if (path->slots[i] >= nritems) {
1995                         if (i == *level)
1996                                 break;
1997                         *level = i + 1;
1998                         return 0;
1999                 }
2000                 if (i == 1) {
2001                         *level = i;
2002                         return 0;
2003                 }
2004
2005                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2006                 eb = read_tree_block(root, bytenr, ptr_gen);
2007                 if (IS_ERR(eb)) {
2008                         return PTR_ERR(eb);
2009                 } else if (!extent_buffer_uptodate(eb)) {
2010                         free_extent_buffer(eb);
2011                         return -EIO;
2012                 }
2013                 BUG_ON(btrfs_header_level(eb) != i - 1);
2014                 path->nodes[i - 1] = eb;
2015                 path->slots[i - 1] = 0;
2016         }
2017         return 1;
2018 }
2019
2020 /*
2021  * invalidate extent cache for file extents whose key in range of
2022  * [min_key, max_key)
2023  */
2024 static int invalidate_extent_cache(struct btrfs_root *root,
2025                                    struct btrfs_key *min_key,
2026                                    struct btrfs_key *max_key)
2027 {
2028         struct inode *inode = NULL;
2029         u64 objectid;
2030         u64 start, end;
2031         u64 ino;
2032
2033         objectid = min_key->objectid;
2034         while (1) {
2035                 cond_resched();
2036                 iput(inode);
2037
2038                 if (objectid > max_key->objectid)
2039                         break;
2040
2041                 inode = find_next_inode(root, objectid);
2042                 if (!inode)
2043                         break;
2044                 ino = btrfs_ino(inode);
2045
2046                 if (ino > max_key->objectid) {
2047                         iput(inode);
2048                         break;
2049                 }
2050
2051                 objectid = ino + 1;
2052                 if (!S_ISREG(inode->i_mode))
2053                         continue;
2054
2055                 if (unlikely(min_key->objectid == ino)) {
2056                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2057                                 continue;
2058                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2059                                 start = 0;
2060                         else {
2061                                 start = min_key->offset;
2062                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2063                         }
2064                 } else {
2065                         start = 0;
2066                 }
2067
2068                 if (unlikely(max_key->objectid == ino)) {
2069                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2070                                 continue;
2071                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2072                                 end = (u64)-1;
2073                         } else {
2074                                 if (max_key->offset == 0)
2075                                         continue;
2076                                 end = max_key->offset;
2077                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2078                                 end--;
2079                         }
2080                 } else {
2081                         end = (u64)-1;
2082                 }
2083
2084                 /* the lock_extent waits for readpage to complete */
2085                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2086                 btrfs_drop_extent_cache(inode, start, end, 1);
2087                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2088         }
2089         return 0;
2090 }
2091
2092 static int find_next_key(struct btrfs_path *path, int level,
2093                          struct btrfs_key *key)
2094
2095 {
2096         while (level < BTRFS_MAX_LEVEL) {
2097                 if (!path->nodes[level])
2098                         break;
2099                 if (path->slots[level] + 1 <
2100                     btrfs_header_nritems(path->nodes[level])) {
2101                         btrfs_node_key_to_cpu(path->nodes[level], key,
2102                                               path->slots[level] + 1);
2103                         return 0;
2104                 }
2105                 level++;
2106         }
2107         return 1;
2108 }
2109
2110 /*
2111  * merge the relocated tree blocks in reloc tree with corresponding
2112  * fs tree.
2113  */
2114 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2115                                                struct btrfs_root *root)
2116 {
2117         LIST_HEAD(inode_list);
2118         struct btrfs_key key;
2119         struct btrfs_key next_key;
2120         struct btrfs_trans_handle *trans = NULL;
2121         struct btrfs_root *reloc_root;
2122         struct btrfs_root_item *root_item;
2123         struct btrfs_path *path;
2124         struct extent_buffer *leaf;
2125         int level;
2126         int max_level;
2127         int replaced = 0;
2128         int ret;
2129         int err = 0;
2130         u32 min_reserved;
2131
2132         path = btrfs_alloc_path();
2133         if (!path)
2134                 return -ENOMEM;
2135         path->reada = 1;
2136
2137         reloc_root = root->reloc_root;
2138         root_item = &reloc_root->root_item;
2139
2140         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2141                 level = btrfs_root_level(root_item);
2142                 extent_buffer_get(reloc_root->node);
2143                 path->nodes[level] = reloc_root->node;
2144                 path->slots[level] = 0;
2145         } else {
2146                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2147
2148                 level = root_item->drop_level;
2149                 BUG_ON(level == 0);
2150                 path->lowest_level = level;
2151                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2152                 path->lowest_level = 0;
2153                 if (ret < 0) {
2154                         btrfs_free_path(path);
2155                         return ret;
2156                 }
2157
2158                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2159                                       path->slots[level]);
2160                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2161
2162                 btrfs_unlock_up_safe(path, 0);
2163         }
2164
2165         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2166         memset(&next_key, 0, sizeof(next_key));
2167
2168         while (1) {
2169                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2170                                              BTRFS_RESERVE_FLUSH_ALL);
2171                 if (ret) {
2172                         err = ret;
2173                         goto out;
2174                 }
2175                 trans = btrfs_start_transaction(root, 0);
2176                 if (IS_ERR(trans)) {
2177                         err = PTR_ERR(trans);
2178                         trans = NULL;
2179                         goto out;
2180                 }
2181                 trans->block_rsv = rc->block_rsv;
2182
2183                 replaced = 0;
2184                 max_level = level;
2185
2186                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2187                 if (ret < 0) {
2188                         err = ret;
2189                         goto out;
2190                 }
2191                 if (ret > 0)
2192                         break;
2193
2194                 if (!find_next_key(path, level, &key) &&
2195                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2196                         ret = 0;
2197                 } else {
2198                         ret = replace_path(trans, root, reloc_root, path,
2199                                            &next_key, level, max_level);
2200                 }
2201                 if (ret < 0) {
2202                         err = ret;
2203                         goto out;
2204                 }
2205
2206                 if (ret > 0) {
2207                         level = ret;
2208                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2209                                               path->slots[level]);
2210                         replaced = 1;
2211                 }
2212
2213                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2214                 if (ret > 0)
2215                         break;
2216
2217                 BUG_ON(level == 0);
2218                 /*
2219                  * save the merging progress in the drop_progress.
2220                  * this is OK since root refs == 1 in this case.
2221                  */
2222                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2223                                path->slots[level]);
2224                 root_item->drop_level = level;
2225
2226                 btrfs_end_transaction_throttle(trans, root);
2227                 trans = NULL;
2228
2229                 btrfs_btree_balance_dirty(root);
2230
2231                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2232                         invalidate_extent_cache(root, &key, &next_key);
2233         }
2234
2235         /*
2236          * handle the case only one block in the fs tree need to be
2237          * relocated and the block is tree root.
2238          */
2239         leaf = btrfs_lock_root_node(root);
2240         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2241         btrfs_tree_unlock(leaf);
2242         free_extent_buffer(leaf);
2243         if (ret < 0)
2244                 err = ret;
2245 out:
2246         btrfs_free_path(path);
2247
2248         if (err == 0) {
2249                 memset(&root_item->drop_progress, 0,
2250                        sizeof(root_item->drop_progress));
2251                 root_item->drop_level = 0;
2252                 btrfs_set_root_refs(root_item, 0);
2253                 btrfs_update_reloc_root(trans, root);
2254         }
2255
2256         if (trans)
2257                 btrfs_end_transaction_throttle(trans, root);
2258
2259         btrfs_btree_balance_dirty(root);
2260
2261         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2262                 invalidate_extent_cache(root, &key, &next_key);
2263
2264         return err;
2265 }
2266
2267 static noinline_for_stack
2268 int prepare_to_merge(struct reloc_control *rc, int err)
2269 {
2270         struct btrfs_root *root = rc->extent_root;
2271         struct btrfs_root *reloc_root;
2272         struct btrfs_trans_handle *trans;
2273         LIST_HEAD(reloc_roots);
2274         u64 num_bytes = 0;
2275         int ret;
2276
2277         mutex_lock(&root->fs_info->reloc_mutex);
2278         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2279         rc->merging_rsv_size += rc->nodes_relocated * 2;
2280         mutex_unlock(&root->fs_info->reloc_mutex);
2281
2282 again:
2283         if (!err) {
2284                 num_bytes = rc->merging_rsv_size;
2285                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2286                                           BTRFS_RESERVE_FLUSH_ALL);
2287                 if (ret)
2288                         err = ret;
2289         }
2290
2291         trans = btrfs_join_transaction(rc->extent_root);
2292         if (IS_ERR(trans)) {
2293                 if (!err)
2294                         btrfs_block_rsv_release(rc->extent_root,
2295                                                 rc->block_rsv, num_bytes);
2296                 return PTR_ERR(trans);
2297         }
2298
2299         if (!err) {
2300                 if (num_bytes != rc->merging_rsv_size) {
2301                         btrfs_end_transaction(trans, rc->extent_root);
2302                         btrfs_block_rsv_release(rc->extent_root,
2303                                                 rc->block_rsv, num_bytes);
2304                         goto again;
2305                 }
2306         }
2307
2308         rc->merge_reloc_tree = 1;
2309
2310         while (!list_empty(&rc->reloc_roots)) {
2311                 reloc_root = list_entry(rc->reloc_roots.next,
2312                                         struct btrfs_root, root_list);
2313                 list_del_init(&reloc_root->root_list);
2314
2315                 root = read_fs_root(reloc_root->fs_info,
2316                                     reloc_root->root_key.offset);
2317                 BUG_ON(IS_ERR(root));
2318                 BUG_ON(root->reloc_root != reloc_root);
2319
2320                 /*
2321                  * set reference count to 1, so btrfs_recover_relocation
2322                  * knows it should resumes merging
2323                  */
2324                 if (!err)
2325                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2326                 btrfs_update_reloc_root(trans, root);
2327
2328                 list_add(&reloc_root->root_list, &reloc_roots);
2329         }
2330
2331         list_splice(&reloc_roots, &rc->reloc_roots);
2332
2333         if (!err)
2334                 btrfs_commit_transaction(trans, rc->extent_root);
2335         else
2336                 btrfs_end_transaction(trans, rc->extent_root);
2337         return err;
2338 }
2339
2340 static noinline_for_stack
2341 void free_reloc_roots(struct list_head *list)
2342 {
2343         struct btrfs_root *reloc_root;
2344
2345         while (!list_empty(list)) {
2346                 reloc_root = list_entry(list->next, struct btrfs_root,
2347                                         root_list);
2348                 __del_reloc_root(reloc_root);
2349         }
2350 }
2351
2352 static noinline_for_stack
2353 void merge_reloc_roots(struct reloc_control *rc)
2354 {
2355         struct btrfs_root *root;
2356         struct btrfs_root *reloc_root;
2357         u64 last_snap;
2358         u64 otransid;
2359         u64 objectid;
2360         LIST_HEAD(reloc_roots);
2361         int found = 0;
2362         int ret = 0;
2363 again:
2364         root = rc->extent_root;
2365
2366         /*
2367          * this serializes us with btrfs_record_root_in_transaction,
2368          * we have to make sure nobody is in the middle of
2369          * adding their roots to the list while we are
2370          * doing this splice
2371          */
2372         mutex_lock(&root->fs_info->reloc_mutex);
2373         list_splice_init(&rc->reloc_roots, &reloc_roots);
2374         mutex_unlock(&root->fs_info->reloc_mutex);
2375
2376         while (!list_empty(&reloc_roots)) {
2377                 found = 1;
2378                 reloc_root = list_entry(reloc_roots.next,
2379                                         struct btrfs_root, root_list);
2380
2381                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2382                         root = read_fs_root(reloc_root->fs_info,
2383                                             reloc_root->root_key.offset);
2384                         BUG_ON(IS_ERR(root));
2385                         BUG_ON(root->reloc_root != reloc_root);
2386
2387                         ret = merge_reloc_root(rc, root);
2388                         if (ret) {
2389                                 if (list_empty(&reloc_root->root_list))
2390                                         list_add_tail(&reloc_root->root_list,
2391                                                       &reloc_roots);
2392                                 goto out;
2393                         }
2394                 } else {
2395                         list_del_init(&reloc_root->root_list);
2396                 }
2397
2398                 /*
2399                  * we keep the old last snapshod transid in rtranid when we
2400                  * created the relocation tree.
2401                  */
2402                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2403                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2404                 objectid = reloc_root->root_key.offset;
2405
2406                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2407                 if (ret < 0) {
2408                         if (list_empty(&reloc_root->root_list))
2409                                 list_add_tail(&reloc_root->root_list,
2410                                               &reloc_roots);
2411                         goto out;
2412                 }
2413         }
2414
2415         if (found) {
2416                 found = 0;
2417                 goto again;
2418         }
2419 out:
2420         if (ret) {
2421                 btrfs_std_error(root->fs_info, ret);
2422                 if (!list_empty(&reloc_roots))
2423                         free_reloc_roots(&reloc_roots);
2424
2425                 /* new reloc root may be added */
2426                 mutex_lock(&root->fs_info->reloc_mutex);
2427                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2428                 mutex_unlock(&root->fs_info->reloc_mutex);
2429                 if (!list_empty(&reloc_roots))
2430                         free_reloc_roots(&reloc_roots);
2431         }
2432
2433         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2434 }
2435
2436 static void free_block_list(struct rb_root *blocks)
2437 {
2438         struct tree_block *block;
2439         struct rb_node *rb_node;
2440         while ((rb_node = rb_first(blocks))) {
2441                 block = rb_entry(rb_node, struct tree_block, rb_node);
2442                 rb_erase(rb_node, blocks);
2443                 kfree(block);
2444         }
2445 }
2446
2447 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2448                                       struct btrfs_root *reloc_root)
2449 {
2450         struct btrfs_root *root;
2451
2452         if (reloc_root->last_trans == trans->transid)
2453                 return 0;
2454
2455         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2456         BUG_ON(IS_ERR(root));
2457         BUG_ON(root->reloc_root != reloc_root);
2458
2459         return btrfs_record_root_in_trans(trans, root);
2460 }
2461
2462 static noinline_for_stack
2463 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2464                                      struct reloc_control *rc,
2465                                      struct backref_node *node,
2466                                      struct backref_edge *edges[])
2467 {
2468         struct backref_node *next;
2469         struct btrfs_root *root;
2470         int index = 0;
2471
2472         next = node;
2473         while (1) {
2474                 cond_resched();
2475                 next = walk_up_backref(next, edges, &index);
2476                 root = next->root;
2477                 BUG_ON(!root);
2478                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2479
2480                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2481                         record_reloc_root_in_trans(trans, root);
2482                         break;
2483                 }
2484
2485                 btrfs_record_root_in_trans(trans, root);
2486                 root = root->reloc_root;
2487
2488                 if (next->new_bytenr != root->node->start) {
2489                         BUG_ON(next->new_bytenr);
2490                         BUG_ON(!list_empty(&next->list));
2491                         next->new_bytenr = root->node->start;
2492                         next->root = root;
2493                         list_add_tail(&next->list,
2494                                       &rc->backref_cache.changed);
2495                         __mark_block_processed(rc, next);
2496                         break;
2497                 }
2498
2499                 WARN_ON(1);
2500                 root = NULL;
2501                 next = walk_down_backref(edges, &index);
2502                 if (!next || next->level <= node->level)
2503                         break;
2504         }
2505         if (!root)
2506                 return NULL;
2507
2508         next = node;
2509         /* setup backref node path for btrfs_reloc_cow_block */
2510         while (1) {
2511                 rc->backref_cache.path[next->level] = next;
2512                 if (--index < 0)
2513                         break;
2514                 next = edges[index]->node[UPPER];
2515         }
2516         return root;
2517 }
2518
2519 /*
2520  * select a tree root for relocation. return NULL if the block
2521  * is reference counted. we should use do_relocation() in this
2522  * case. return a tree root pointer if the block isn't reference
2523  * counted. return -ENOENT if the block is root of reloc tree.
2524  */
2525 static noinline_for_stack
2526 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2527                                    struct backref_node *node)
2528 {
2529         struct backref_node *next;
2530         struct btrfs_root *root;
2531         struct btrfs_root *fs_root = NULL;
2532         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2533         int index = 0;
2534
2535         next = node;
2536         while (1) {
2537                 cond_resched();
2538                 next = walk_up_backref(next, edges, &index);
2539                 root = next->root;
2540                 BUG_ON(!root);
2541
2542                 /* no other choice for non-references counted tree */
2543                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2544                         return root;
2545
2546                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2547                         fs_root = root;
2548
2549                 if (next != node)
2550                         return NULL;
2551
2552                 next = walk_down_backref(edges, &index);
2553                 if (!next || next->level <= node->level)
2554                         break;
2555         }
2556
2557         if (!fs_root)
2558                 return ERR_PTR(-ENOENT);
2559         return fs_root;
2560 }
2561
2562 static noinline_for_stack
2563 u64 calcu_metadata_size(struct reloc_control *rc,
2564                         struct backref_node *node, int reserve)
2565 {
2566         struct backref_node *next = node;
2567         struct backref_edge *edge;
2568         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2569         u64 num_bytes = 0;
2570         int index = 0;
2571
2572         BUG_ON(reserve && node->processed);
2573
2574         while (next) {
2575                 cond_resched();
2576                 while (1) {
2577                         if (next->processed && (reserve || next != node))
2578                                 break;
2579
2580                         num_bytes += rc->extent_root->nodesize;
2581
2582                         if (list_empty(&next->upper))
2583                                 break;
2584
2585                         edge = list_entry(next->upper.next,
2586                                           struct backref_edge, list[LOWER]);
2587                         edges[index++] = edge;
2588                         next = edge->node[UPPER];
2589                 }
2590                 next = walk_down_backref(edges, &index);
2591         }
2592         return num_bytes;
2593 }
2594
2595 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2596                                   struct reloc_control *rc,
2597                                   struct backref_node *node)
2598 {
2599         struct btrfs_root *root = rc->extent_root;
2600         u64 num_bytes;
2601         int ret;
2602         u64 tmp;
2603
2604         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2605
2606         trans->block_rsv = rc->block_rsv;
2607         rc->reserved_bytes += num_bytes;
2608         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2609                                 BTRFS_RESERVE_FLUSH_ALL);
2610         if (ret) {
2611                 if (ret == -EAGAIN) {
2612                         tmp = rc->extent_root->nodesize *
2613                                 RELOCATION_RESERVED_NODES;
2614                         while (tmp <= rc->reserved_bytes)
2615                                 tmp <<= 1;
2616                         /*
2617                          * only one thread can access block_rsv at this point,
2618                          * so we don't need hold lock to protect block_rsv.
2619                          * we expand more reservation size here to allow enough
2620                          * space for relocation and we will return eailer in
2621                          * enospc case.
2622                          */
2623                         rc->block_rsv->size = tmp + rc->extent_root->nodesize *
2624                                               RELOCATION_RESERVED_NODES;
2625                 }
2626                 return ret;
2627         }
2628
2629         return 0;
2630 }
2631
2632 /*
2633  * relocate a block tree, and then update pointers in upper level
2634  * blocks that reference the block to point to the new location.
2635  *
2636  * if called by link_to_upper, the block has already been relocated.
2637  * in that case this function just updates pointers.
2638  */
2639 static int do_relocation(struct btrfs_trans_handle *trans,
2640                          struct reloc_control *rc,
2641                          struct backref_node *node,
2642                          struct btrfs_key *key,
2643                          struct btrfs_path *path, int lowest)
2644 {
2645         struct backref_node *upper;
2646         struct backref_edge *edge;
2647         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2648         struct btrfs_root *root;
2649         struct extent_buffer *eb;
2650         u32 blocksize;
2651         u64 bytenr;
2652         u64 generation;
2653         int slot;
2654         int ret;
2655         int err = 0;
2656
2657         BUG_ON(lowest && node->eb);
2658
2659         path->lowest_level = node->level + 1;
2660         rc->backref_cache.path[node->level] = node;
2661         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2662                 cond_resched();
2663
2664                 upper = edge->node[UPPER];
2665                 root = select_reloc_root(trans, rc, upper, edges);
2666                 BUG_ON(!root);
2667
2668                 if (upper->eb && !upper->locked) {
2669                         if (!lowest) {
2670                                 ret = btrfs_bin_search(upper->eb, key,
2671                                                        upper->level, &slot);
2672                                 BUG_ON(ret);
2673                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2674                                 if (node->eb->start == bytenr)
2675                                         goto next;
2676                         }
2677                         drop_node_buffer(upper);
2678                 }
2679
2680                 if (!upper->eb) {
2681                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2682                         if (ret < 0) {
2683                                 err = ret;
2684                                 break;
2685                         }
2686                         BUG_ON(ret > 0);
2687
2688                         if (!upper->eb) {
2689                                 upper->eb = path->nodes[upper->level];
2690                                 path->nodes[upper->level] = NULL;
2691                         } else {
2692                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2693                         }
2694
2695                         upper->locked = 1;
2696                         path->locks[upper->level] = 0;
2697
2698                         slot = path->slots[upper->level];
2699                         btrfs_release_path(path);
2700                 } else {
2701                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2702                                                &slot);
2703                         BUG_ON(ret);
2704                 }
2705
2706                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2707                 if (lowest) {
2708                         BUG_ON(bytenr != node->bytenr);
2709                 } else {
2710                         if (node->eb->start == bytenr)
2711                                 goto next;
2712                 }
2713
2714                 blocksize = root->nodesize;
2715                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2716                 eb = read_tree_block(root, bytenr, generation);
2717                 if (IS_ERR(eb)) {
2718                         err = PTR_ERR(eb);
2719                         goto next;
2720                 } else if (!extent_buffer_uptodate(eb)) {
2721                         free_extent_buffer(eb);
2722                         err = -EIO;
2723                         goto next;
2724                 }
2725                 btrfs_tree_lock(eb);
2726                 btrfs_set_lock_blocking(eb);
2727
2728                 if (!node->eb) {
2729                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2730                                               slot, &eb);
2731                         btrfs_tree_unlock(eb);
2732                         free_extent_buffer(eb);
2733                         if (ret < 0) {
2734                                 err = ret;
2735                                 goto next;
2736                         }
2737                         BUG_ON(node->eb != eb);
2738                 } else {
2739                         btrfs_set_node_blockptr(upper->eb, slot,
2740                                                 node->eb->start);
2741                         btrfs_set_node_ptr_generation(upper->eb, slot,
2742                                                       trans->transid);
2743                         btrfs_mark_buffer_dirty(upper->eb);
2744
2745                         ret = btrfs_inc_extent_ref(trans, root,
2746                                                 node->eb->start, blocksize,
2747                                                 upper->eb->start,
2748                                                 btrfs_header_owner(upper->eb),
2749                                                 node->level, 0, 1);
2750                         BUG_ON(ret);
2751
2752                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2753                         BUG_ON(ret);
2754                 }
2755 next:
2756                 if (!upper->pending)
2757                         drop_node_buffer(upper);
2758                 else
2759                         unlock_node_buffer(upper);
2760                 if (err)
2761                         break;
2762         }
2763
2764         if (!err && node->pending) {
2765                 drop_node_buffer(node);
2766                 list_move_tail(&node->list, &rc->backref_cache.changed);
2767                 node->pending = 0;
2768         }
2769
2770         path->lowest_level = 0;
2771         BUG_ON(err == -ENOSPC);
2772         return err;
2773 }
2774
2775 static int link_to_upper(struct btrfs_trans_handle *trans,
2776                          struct reloc_control *rc,
2777                          struct backref_node *node,
2778                          struct btrfs_path *path)
2779 {
2780         struct btrfs_key key;
2781
2782         btrfs_node_key_to_cpu(node->eb, &key, 0);
2783         return do_relocation(trans, rc, node, &key, path, 0);
2784 }
2785
2786 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2787                                 struct reloc_control *rc,
2788                                 struct btrfs_path *path, int err)
2789 {
2790         LIST_HEAD(list);
2791         struct backref_cache *cache = &rc->backref_cache;
2792         struct backref_node *node;
2793         int level;
2794         int ret;
2795
2796         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2797                 while (!list_empty(&cache->pending[level])) {
2798                         node = list_entry(cache->pending[level].next,
2799                                           struct backref_node, list);
2800                         list_move_tail(&node->list, &list);
2801                         BUG_ON(!node->pending);
2802
2803                         if (!err) {
2804                                 ret = link_to_upper(trans, rc, node, path);
2805                                 if (ret < 0)
2806                                         err = ret;
2807                         }
2808                 }
2809                 list_splice_init(&list, &cache->pending[level]);
2810         }
2811         return err;
2812 }
2813
2814 static void mark_block_processed(struct reloc_control *rc,
2815                                  u64 bytenr, u32 blocksize)
2816 {
2817         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2818                         EXTENT_DIRTY, GFP_NOFS);
2819 }
2820
2821 static void __mark_block_processed(struct reloc_control *rc,
2822                                    struct backref_node *node)
2823 {
2824         u32 blocksize;
2825         if (node->level == 0 ||
2826             in_block_group(node->bytenr, rc->block_group)) {
2827                 blocksize = rc->extent_root->nodesize;
2828                 mark_block_processed(rc, node->bytenr, blocksize);
2829         }
2830         node->processed = 1;
2831 }
2832
2833 /*
2834  * mark a block and all blocks directly/indirectly reference the block
2835  * as processed.
2836  */
2837 static void update_processed_blocks(struct reloc_control *rc,
2838                                     struct backref_node *node)
2839 {
2840         struct backref_node *next = node;
2841         struct backref_edge *edge;
2842         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2843         int index = 0;
2844
2845         while (next) {
2846                 cond_resched();
2847                 while (1) {
2848                         if (next->processed)
2849                                 break;
2850
2851                         __mark_block_processed(rc, next);
2852
2853                         if (list_empty(&next->upper))
2854                                 break;
2855
2856                         edge = list_entry(next->upper.next,
2857                                           struct backref_edge, list[LOWER]);
2858                         edges[index++] = edge;
2859                         next = edge->node[UPPER];
2860                 }
2861                 next = walk_down_backref(edges, &index);
2862         }
2863 }
2864
2865 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2866 {
2867         u32 blocksize = rc->extent_root->nodesize;
2868
2869         if (test_range_bit(&rc->processed_blocks, bytenr,
2870                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2871                 return 1;
2872         return 0;
2873 }
2874
2875 static int get_tree_block_key(struct reloc_control *rc,
2876                               struct tree_block *block)
2877 {
2878         struct extent_buffer *eb;
2879
2880         BUG_ON(block->key_ready);
2881         eb = read_tree_block(rc->extent_root, block->bytenr,
2882                              block->key.offset);
2883         if (IS_ERR(eb)) {
2884                 return PTR_ERR(eb);
2885         } else if (!extent_buffer_uptodate(eb)) {
2886                 free_extent_buffer(eb);
2887                 return -EIO;
2888         }
2889         WARN_ON(btrfs_header_level(eb) != block->level);
2890         if (block->level == 0)
2891                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2892         else
2893                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2894         free_extent_buffer(eb);
2895         block->key_ready = 1;
2896         return 0;
2897 }
2898
2899 /*
2900  * helper function to relocate a tree block
2901  */
2902 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2903                                 struct reloc_control *rc,
2904                                 struct backref_node *node,
2905                                 struct btrfs_key *key,
2906                                 struct btrfs_path *path)
2907 {
2908         struct btrfs_root *root;
2909         int ret = 0;
2910
2911         if (!node)
2912                 return 0;
2913
2914         BUG_ON(node->processed);
2915         root = select_one_root(trans, node);
2916         if (root == ERR_PTR(-ENOENT)) {
2917                 update_processed_blocks(rc, node);
2918                 goto out;
2919         }
2920
2921         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2922                 ret = reserve_metadata_space(trans, rc, node);
2923                 if (ret)
2924                         goto out;
2925         }
2926
2927         if (root) {
2928                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2929                         BUG_ON(node->new_bytenr);
2930                         BUG_ON(!list_empty(&node->list));
2931                         btrfs_record_root_in_trans(trans, root);
2932                         root = root->reloc_root;
2933                         node->new_bytenr = root->node->start;
2934                         node->root = root;
2935                         list_add_tail(&node->list, &rc->backref_cache.changed);
2936                 } else {
2937                         path->lowest_level = node->level;
2938                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2939                         btrfs_release_path(path);
2940                         if (ret > 0)
2941                                 ret = 0;
2942                 }
2943                 if (!ret)
2944                         update_processed_blocks(rc, node);
2945         } else {
2946                 ret = do_relocation(trans, rc, node, key, path, 1);
2947         }
2948 out:
2949         if (ret || node->level == 0 || node->cowonly)
2950                 remove_backref_node(&rc->backref_cache, node);
2951         return ret;
2952 }
2953
2954 /*
2955  * relocate a list of blocks
2956  */
2957 static noinline_for_stack
2958 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2959                          struct reloc_control *rc, struct rb_root *blocks)
2960 {
2961         struct backref_node *node;
2962         struct btrfs_path *path;
2963         struct tree_block *block;
2964         struct rb_node *rb_node;
2965         int ret;
2966         int err = 0;
2967
2968         path = btrfs_alloc_path();
2969         if (!path) {
2970                 err = -ENOMEM;
2971                 goto out_free_blocks;
2972         }
2973
2974         rb_node = rb_first(blocks);
2975         while (rb_node) {
2976                 block = rb_entry(rb_node, struct tree_block, rb_node);
2977                 if (!block->key_ready)
2978                         readahead_tree_block(rc->extent_root, block->bytenr);
2979                 rb_node = rb_next(rb_node);
2980         }
2981
2982         rb_node = rb_first(blocks);
2983         while (rb_node) {
2984                 block = rb_entry(rb_node, struct tree_block, rb_node);
2985                 if (!block->key_ready) {
2986                         err = get_tree_block_key(rc, block);
2987                         if (err)
2988                                 goto out_free_path;
2989                 }
2990                 rb_node = rb_next(rb_node);
2991         }
2992
2993         rb_node = rb_first(blocks);
2994         while (rb_node) {
2995                 block = rb_entry(rb_node, struct tree_block, rb_node);
2996
2997                 node = build_backref_tree(rc, &block->key,
2998                                           block->level, block->bytenr);
2999                 if (IS_ERR(node)) {
3000                         err = PTR_ERR(node);
3001                         goto out;
3002                 }
3003
3004                 ret = relocate_tree_block(trans, rc, node, &block->key,
3005                                           path);
3006                 if (ret < 0) {
3007                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3008                                 err = ret;
3009                         goto out;
3010                 }
3011                 rb_node = rb_next(rb_node);
3012         }
3013 out:
3014         err = finish_pending_nodes(trans, rc, path, err);
3015
3016 out_free_path:
3017         btrfs_free_path(path);
3018 out_free_blocks:
3019         free_block_list(blocks);
3020         return err;
3021 }
3022
3023 static noinline_for_stack
3024 int prealloc_file_extent_cluster(struct inode *inode,
3025                                  struct file_extent_cluster *cluster)
3026 {
3027         u64 alloc_hint = 0;
3028         u64 start;
3029         u64 end;
3030         u64 offset = BTRFS_I(inode)->index_cnt;
3031         u64 num_bytes;
3032         int nr = 0;
3033         int ret = 0;
3034
3035         BUG_ON(cluster->start != cluster->boundary[0]);
3036         mutex_lock(&inode->i_mutex);
3037
3038         ret = btrfs_check_data_free_space(inode, cluster->end +
3039                                           1 - cluster->start, 0);
3040         if (ret)
3041                 goto out;
3042
3043         while (nr < cluster->nr) {
3044                 start = cluster->boundary[nr] - offset;
3045                 if (nr + 1 < cluster->nr)
3046                         end = cluster->boundary[nr + 1] - 1 - offset;
3047                 else
3048                         end = cluster->end - offset;
3049
3050                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3051                 num_bytes = end + 1 - start;
3052                 ret = btrfs_prealloc_file_range(inode, 0, start,
3053                                                 num_bytes, num_bytes,
3054                                                 end + 1, &alloc_hint);
3055                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3056                 if (ret)
3057                         break;
3058                 nr++;
3059         }
3060         btrfs_free_reserved_data_space(inode, cluster->end +
3061                                        1 - cluster->start);
3062 out:
3063         mutex_unlock(&inode->i_mutex);
3064         return ret;
3065 }
3066
3067 static noinline_for_stack
3068 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3069                          u64 block_start)
3070 {
3071         struct btrfs_root *root = BTRFS_I(inode)->root;
3072         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3073         struct extent_map *em;
3074         int ret = 0;
3075
3076         em = alloc_extent_map();
3077         if (!em)
3078                 return -ENOMEM;
3079
3080         em->start = start;
3081         em->len = end + 1 - start;
3082         em->block_len = em->len;
3083         em->block_start = block_start;
3084         em->bdev = root->fs_info->fs_devices->latest_bdev;
3085         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3086
3087         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3088         while (1) {
3089                 write_lock(&em_tree->lock);
3090                 ret = add_extent_mapping(em_tree, em, 0);
3091                 write_unlock(&em_tree->lock);
3092                 if (ret != -EEXIST) {
3093                         free_extent_map(em);
3094                         break;
3095                 }
3096                 btrfs_drop_extent_cache(inode, start, end, 0);
3097         }
3098         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3099         return ret;
3100 }
3101
3102 static int relocate_file_extent_cluster(struct inode *inode,
3103                                         struct file_extent_cluster *cluster)
3104 {
3105         u64 page_start;
3106         u64 page_end;
3107         u64 offset = BTRFS_I(inode)->index_cnt;
3108         unsigned long index;
3109         unsigned long last_index;
3110         struct page *page;
3111         struct file_ra_state *ra;
3112         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3113         int nr = 0;
3114         int ret = 0;
3115
3116         if (!cluster->nr)
3117                 return 0;
3118
3119         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3120         if (!ra)
3121                 return -ENOMEM;
3122
3123         ret = prealloc_file_extent_cluster(inode, cluster);
3124         if (ret)
3125                 goto out;
3126
3127         file_ra_state_init(ra, inode->i_mapping);
3128
3129         ret = setup_extent_mapping(inode, cluster->start - offset,
3130                                    cluster->end - offset, cluster->start);
3131         if (ret)
3132                 goto out;
3133
3134         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3135         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3136         while (index <= last_index) {
3137                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3138                 if (ret)
3139                         goto out;
3140
3141                 page = find_lock_page(inode->i_mapping, index);
3142                 if (!page) {
3143                         page_cache_sync_readahead(inode->i_mapping,
3144                                                   ra, NULL, index,
3145                                                   last_index + 1 - index);
3146                         page = find_or_create_page(inode->i_mapping, index,
3147                                                    mask);
3148                         if (!page) {
3149                                 btrfs_delalloc_release_metadata(inode,
3150                                                         PAGE_CACHE_SIZE);
3151                                 ret = -ENOMEM;
3152                                 goto out;
3153                         }
3154                 }
3155
3156                 if (PageReadahead(page)) {
3157                         page_cache_async_readahead(inode->i_mapping,
3158                                                    ra, NULL, page, index,
3159                                                    last_index + 1 - index);
3160                 }
3161
3162                 if (!PageUptodate(page)) {
3163                         btrfs_readpage(NULL, page);
3164                         lock_page(page);
3165                         if (!PageUptodate(page)) {
3166                                 unlock_page(page);
3167                                 page_cache_release(page);
3168                                 btrfs_delalloc_release_metadata(inode,
3169                                                         PAGE_CACHE_SIZE);
3170                                 ret = -EIO;
3171                                 goto out;
3172                         }
3173                 }
3174
3175                 page_start = page_offset(page);
3176                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3177
3178                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3179
3180                 set_page_extent_mapped(page);
3181
3182                 if (nr < cluster->nr &&
3183                     page_start + offset == cluster->boundary[nr]) {
3184                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3185                                         page_start, page_end,
3186                                         EXTENT_BOUNDARY, GFP_NOFS);
3187                         nr++;
3188                 }
3189
3190                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3191                 set_page_dirty(page);
3192
3193                 unlock_extent(&BTRFS_I(inode)->io_tree,
3194                               page_start, page_end);
3195                 unlock_page(page);
3196                 page_cache_release(page);
3197
3198                 index++;
3199                 balance_dirty_pages_ratelimited(inode->i_mapping);
3200                 btrfs_throttle(BTRFS_I(inode)->root);
3201         }
3202         WARN_ON(nr != cluster->nr);
3203 out:
3204         kfree(ra);
3205         return ret;
3206 }
3207
3208 static noinline_for_stack
3209 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3210                          struct file_extent_cluster *cluster)
3211 {
3212         int ret;
3213
3214         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3215                 ret = relocate_file_extent_cluster(inode, cluster);
3216                 if (ret)
3217                         return ret;
3218                 cluster->nr = 0;
3219         }
3220
3221         if (!cluster->nr)
3222                 cluster->start = extent_key->objectid;
3223         else
3224                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3225         cluster->end = extent_key->objectid + extent_key->offset - 1;
3226         cluster->boundary[cluster->nr] = extent_key->objectid;
3227         cluster->nr++;
3228
3229         if (cluster->nr >= MAX_EXTENTS) {
3230                 ret = relocate_file_extent_cluster(inode, cluster);
3231                 if (ret)
3232                         return ret;
3233                 cluster->nr = 0;
3234         }
3235         return 0;
3236 }
3237
3238 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3239 static int get_ref_objectid_v0(struct reloc_control *rc,
3240                                struct btrfs_path *path,
3241                                struct btrfs_key *extent_key,
3242                                u64 *ref_objectid, int *path_change)
3243 {
3244         struct btrfs_key key;
3245         struct extent_buffer *leaf;
3246         struct btrfs_extent_ref_v0 *ref0;
3247         int ret;
3248         int slot;
3249
3250         leaf = path->nodes[0];
3251         slot = path->slots[0];
3252         while (1) {
3253                 if (slot >= btrfs_header_nritems(leaf)) {
3254                         ret = btrfs_next_leaf(rc->extent_root, path);
3255                         if (ret < 0)
3256                                 return ret;
3257                         BUG_ON(ret > 0);
3258                         leaf = path->nodes[0];
3259                         slot = path->slots[0];
3260                         if (path_change)
3261                                 *path_change = 1;
3262                 }
3263                 btrfs_item_key_to_cpu(leaf, &key, slot);
3264                 if (key.objectid != extent_key->objectid)
3265                         return -ENOENT;
3266
3267                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3268                         slot++;
3269                         continue;
3270                 }
3271                 ref0 = btrfs_item_ptr(leaf, slot,
3272                                 struct btrfs_extent_ref_v0);
3273                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3274                 break;
3275         }
3276         return 0;
3277 }
3278 #endif
3279
3280 /*
3281  * helper to add a tree block to the list.
3282  * the major work is getting the generation and level of the block
3283  */
3284 static int add_tree_block(struct reloc_control *rc,
3285                           struct btrfs_key *extent_key,
3286                           struct btrfs_path *path,
3287                           struct rb_root *blocks)
3288 {
3289         struct extent_buffer *eb;
3290         struct btrfs_extent_item *ei;
3291         struct btrfs_tree_block_info *bi;
3292         struct tree_block *block;
3293         struct rb_node *rb_node;
3294         u32 item_size;
3295         int level = -1;
3296         u64 generation;
3297
3298         eb =  path->nodes[0];
3299         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3300
3301         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3302             item_size >= sizeof(*ei) + sizeof(*bi)) {
3303                 ei = btrfs_item_ptr(eb, path->slots[0],
3304                                 struct btrfs_extent_item);
3305                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3306                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3307                         level = btrfs_tree_block_level(eb, bi);
3308                 } else {
3309                         level = (int)extent_key->offset;
3310                 }
3311                 generation = btrfs_extent_generation(eb, ei);
3312         } else {
3313 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3314                 u64 ref_owner;
3315                 int ret;
3316
3317                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3318                 ret = get_ref_objectid_v0(rc, path, extent_key,
3319                                           &ref_owner, NULL);
3320                 if (ret < 0)
3321                         return ret;
3322                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3323                 level = (int)ref_owner;
3324                 /* FIXME: get real generation */
3325                 generation = 0;
3326 #else
3327                 BUG();
3328 #endif
3329         }
3330
3331         btrfs_release_path(path);
3332
3333         BUG_ON(level == -1);
3334
3335         block = kmalloc(sizeof(*block), GFP_NOFS);
3336         if (!block)
3337                 return -ENOMEM;
3338
3339         block->bytenr = extent_key->objectid;
3340         block->key.objectid = rc->extent_root->nodesize;
3341         block->key.offset = generation;
3342         block->level = level;
3343         block->key_ready = 0;
3344
3345         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3346         if (rb_node)
3347                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3348
3349         return 0;
3350 }
3351
3352 /*
3353  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3354  */
3355 static int __add_tree_block(struct reloc_control *rc,
3356                             u64 bytenr, u32 blocksize,
3357                             struct rb_root *blocks)
3358 {
3359         struct btrfs_path *path;
3360         struct btrfs_key key;
3361         int ret;
3362         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3363                                         SKINNY_METADATA);
3364
3365         if (tree_block_processed(bytenr, rc))
3366                 return 0;
3367
3368         if (tree_search(blocks, bytenr))
3369                 return 0;
3370
3371         path = btrfs_alloc_path();
3372         if (!path)
3373                 return -ENOMEM;
3374 again:
3375         key.objectid = bytenr;
3376         if (skinny) {
3377                 key.type = BTRFS_METADATA_ITEM_KEY;
3378                 key.offset = (u64)-1;
3379         } else {
3380                 key.type = BTRFS_EXTENT_ITEM_KEY;
3381                 key.offset = blocksize;
3382         }
3383
3384         path->search_commit_root = 1;
3385         path->skip_locking = 1;
3386         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3387         if (ret < 0)
3388                 goto out;
3389
3390         if (ret > 0 && skinny) {
3391                 if (path->slots[0]) {
3392                         path->slots[0]--;
3393                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3394                                               path->slots[0]);
3395                         if (key.objectid == bytenr &&
3396                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3397                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3398                               key.offset == blocksize)))
3399                                 ret = 0;
3400                 }
3401
3402                 if (ret) {
3403                         skinny = false;
3404                         btrfs_release_path(path);
3405                         goto again;
3406                 }
3407         }
3408         BUG_ON(ret);
3409
3410         ret = add_tree_block(rc, &key, path, blocks);
3411 out:
3412         btrfs_free_path(path);
3413         return ret;
3414 }
3415
3416 /*
3417  * helper to check if the block use full backrefs for pointers in it
3418  */
3419 static int block_use_full_backref(struct reloc_control *rc,
3420                                   struct extent_buffer *eb)
3421 {
3422         u64 flags;
3423         int ret;
3424
3425         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3426             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3427                 return 1;
3428
3429         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3430                                        eb->start, btrfs_header_level(eb), 1,
3431                                        NULL, &flags);
3432         BUG_ON(ret);
3433
3434         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3435                 ret = 1;
3436         else
3437                 ret = 0;
3438         return ret;
3439 }
3440
3441 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3442                                     struct btrfs_block_group_cache *block_group,
3443                                     struct inode *inode,
3444                                     u64 ino)
3445 {
3446         struct btrfs_key key;
3447         struct btrfs_root *root = fs_info->tree_root;
3448         struct btrfs_trans_handle *trans;
3449         int ret = 0;
3450
3451         if (inode)
3452                 goto truncate;
3453
3454         key.objectid = ino;
3455         key.type = BTRFS_INODE_ITEM_KEY;
3456         key.offset = 0;
3457
3458         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3459         if (IS_ERR(inode) || is_bad_inode(inode)) {
3460                 if (!IS_ERR(inode))
3461                         iput(inode);
3462                 return -ENOENT;
3463         }
3464
3465 truncate:
3466         ret = btrfs_check_trunc_cache_free_space(root,
3467                                                  &fs_info->global_block_rsv);
3468         if (ret)
3469                 goto out;
3470
3471         trans = btrfs_join_transaction(root);
3472         if (IS_ERR(trans)) {
3473                 ret = PTR_ERR(trans);
3474                 goto out;
3475         }
3476
3477         ret = btrfs_truncate_free_space_cache(root, trans, block_group, inode);
3478
3479         btrfs_end_transaction(trans, root);
3480         btrfs_btree_balance_dirty(root);
3481 out:
3482         iput(inode);
3483         return ret;
3484 }
3485
3486 /*
3487  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3488  * this function scans fs tree to find blocks reference the data extent
3489  */
3490 static int find_data_references(struct reloc_control *rc,
3491                                 struct btrfs_key *extent_key,
3492                                 struct extent_buffer *leaf,
3493                                 struct btrfs_extent_data_ref *ref,
3494                                 struct rb_root *blocks)
3495 {
3496         struct btrfs_path *path;
3497         struct tree_block *block;
3498         struct btrfs_root *root;
3499         struct btrfs_file_extent_item *fi;
3500         struct rb_node *rb_node;
3501         struct btrfs_key key;
3502         u64 ref_root;
3503         u64 ref_objectid;
3504         u64 ref_offset;
3505         u32 ref_count;
3506         u32 nritems;
3507         int err = 0;
3508         int added = 0;
3509         int counted;
3510         int ret;
3511
3512         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3513         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3514         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3515         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3516
3517         /*
3518          * This is an extent belonging to the free space cache, lets just delete
3519          * it and redo the search.
3520          */
3521         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3522                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3523                                                rc->block_group,
3524                                                NULL, ref_objectid);
3525                 if (ret != -ENOENT)
3526                         return ret;
3527                 ret = 0;
3528         }
3529
3530         path = btrfs_alloc_path();
3531         if (!path)
3532                 return -ENOMEM;
3533         path->reada = 1;
3534
3535         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3536         if (IS_ERR(root)) {
3537                 err = PTR_ERR(root);
3538                 goto out;
3539         }
3540
3541         key.objectid = ref_objectid;
3542         key.type = BTRFS_EXTENT_DATA_KEY;
3543         if (ref_offset > ((u64)-1 << 32))
3544                 key.offset = 0;
3545         else
3546                 key.offset = ref_offset;
3547
3548         path->search_commit_root = 1;
3549         path->skip_locking = 1;
3550         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3551         if (ret < 0) {
3552                 err = ret;
3553                 goto out;
3554         }
3555
3556         leaf = path->nodes[0];
3557         nritems = btrfs_header_nritems(leaf);
3558         /*
3559          * the references in tree blocks that use full backrefs
3560          * are not counted in
3561          */
3562         if (block_use_full_backref(rc, leaf))
3563                 counted = 0;
3564         else
3565                 counted = 1;
3566         rb_node = tree_search(blocks, leaf->start);
3567         if (rb_node) {
3568                 if (counted)
3569                         added = 1;
3570                 else
3571                         path->slots[0] = nritems;
3572         }
3573
3574         while (ref_count > 0) {
3575                 while (path->slots[0] >= nritems) {
3576                         ret = btrfs_next_leaf(root, path);
3577                         if (ret < 0) {
3578                                 err = ret;
3579                                 goto out;
3580                         }
3581                         if (WARN_ON(ret > 0))
3582                                 goto out;
3583
3584                         leaf = path->nodes[0];
3585                         nritems = btrfs_header_nritems(leaf);
3586                         added = 0;
3587
3588                         if (block_use_full_backref(rc, leaf))
3589                                 counted = 0;
3590                         else
3591                                 counted = 1;
3592                         rb_node = tree_search(blocks, leaf->start);
3593                         if (rb_node) {
3594                                 if (counted)
3595                                         added = 1;
3596                                 else
3597                                         path->slots[0] = nritems;
3598                         }
3599                 }
3600
3601                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3602                 if (WARN_ON(key.objectid != ref_objectid ||
3603                     key.type != BTRFS_EXTENT_DATA_KEY))
3604                         break;
3605
3606                 fi = btrfs_item_ptr(leaf, path->slots[0],
3607                                     struct btrfs_file_extent_item);
3608
3609                 if (btrfs_file_extent_type(leaf, fi) ==
3610                     BTRFS_FILE_EXTENT_INLINE)
3611                         goto next;
3612
3613                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3614                     extent_key->objectid)
3615                         goto next;
3616
3617                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3618                 if (key.offset != ref_offset)
3619                         goto next;
3620
3621                 if (counted)
3622                         ref_count--;
3623                 if (added)
3624                         goto next;
3625
3626                 if (!tree_block_processed(leaf->start, rc)) {
3627                         block = kmalloc(sizeof(*block), GFP_NOFS);
3628                         if (!block) {
3629                                 err = -ENOMEM;
3630                                 break;
3631                         }
3632                         block->bytenr = leaf->start;
3633                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3634                         block->level = 0;
3635                         block->key_ready = 1;
3636                         rb_node = tree_insert(blocks, block->bytenr,
3637                                               &block->rb_node);
3638                         if (rb_node)
3639                                 backref_tree_panic(rb_node, -EEXIST,
3640                                                    block->bytenr);
3641                 }
3642                 if (counted)
3643                         added = 1;
3644                 else
3645                         path->slots[0] = nritems;
3646 next:
3647                 path->slots[0]++;
3648
3649         }
3650 out:
3651         btrfs_free_path(path);
3652         return err;
3653 }
3654
3655 /*
3656  * helper to find all tree blocks that reference a given data extent
3657  */
3658 static noinline_for_stack
3659 int add_data_references(struct reloc_control *rc,
3660                         struct btrfs_key *extent_key,
3661                         struct btrfs_path *path,
3662                         struct rb_root *blocks)
3663 {
3664         struct btrfs_key key;
3665         struct extent_buffer *eb;
3666         struct btrfs_extent_data_ref *dref;
3667         struct btrfs_extent_inline_ref *iref;
3668         unsigned long ptr;
3669         unsigned long end;
3670         u32 blocksize = rc->extent_root->nodesize;
3671         int ret = 0;
3672         int err = 0;
3673
3674         eb = path->nodes[0];
3675         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3676         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3677 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3678         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3679                 ptr = end;
3680         else
3681 #endif
3682                 ptr += sizeof(struct btrfs_extent_item);
3683
3684         while (ptr < end) {
3685                 iref = (struct btrfs_extent_inline_ref *)ptr;
3686                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3687                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3688                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3689                         ret = __add_tree_block(rc, key.offset, blocksize,
3690                                                blocks);
3691                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3692                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3693                         ret = find_data_references(rc, extent_key,
3694                                                    eb, dref, blocks);
3695                 } else {
3696                         BUG();
3697                 }
3698                 if (ret) {
3699                         err = ret;
3700                         goto out;
3701                 }
3702                 ptr += btrfs_extent_inline_ref_size(key.type);
3703         }
3704         WARN_ON(ptr > end);
3705
3706         while (1) {
3707                 cond_resched();
3708                 eb = path->nodes[0];
3709                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3710                         ret = btrfs_next_leaf(rc->extent_root, path);
3711                         if (ret < 0) {
3712                                 err = ret;
3713                                 break;
3714                         }
3715                         if (ret > 0)
3716                                 break;
3717                         eb = path->nodes[0];
3718                 }
3719
3720                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3721                 if (key.objectid != extent_key->objectid)
3722                         break;
3723
3724 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3725                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3726                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3727 #else
3728                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3729                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3730 #endif
3731                         ret = __add_tree_block(rc, key.offset, blocksize,
3732                                                blocks);
3733                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3734                         dref = btrfs_item_ptr(eb, path->slots[0],
3735                                               struct btrfs_extent_data_ref);
3736                         ret = find_data_references(rc, extent_key,
3737                                                    eb, dref, blocks);
3738                 } else {
3739                         ret = 0;
3740                 }
3741                 if (ret) {
3742                         err = ret;
3743                         break;
3744                 }
3745                 path->slots[0]++;
3746         }
3747 out:
3748         btrfs_release_path(path);
3749         if (err)
3750                 free_block_list(blocks);
3751         return err;
3752 }
3753
3754 /*
3755  * helper to find next unprocessed extent
3756  */
3757 static noinline_for_stack
3758 int find_next_extent(struct btrfs_trans_handle *trans,
3759                      struct reloc_control *rc, struct btrfs_path *path,
3760                      struct btrfs_key *extent_key)
3761 {
3762         struct btrfs_key key;
3763         struct extent_buffer *leaf;
3764         u64 start, end, last;
3765         int ret;
3766
3767         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3768         while (1) {
3769                 cond_resched();
3770                 if (rc->search_start >= last) {
3771                         ret = 1;
3772                         break;
3773                 }
3774
3775                 key.objectid = rc->search_start;
3776                 key.type = BTRFS_EXTENT_ITEM_KEY;
3777                 key.offset = 0;
3778
3779                 path->search_commit_root = 1;
3780                 path->skip_locking = 1;
3781                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3782                                         0, 0);
3783                 if (ret < 0)
3784                         break;
3785 next:
3786                 leaf = path->nodes[0];
3787                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3788                         ret = btrfs_next_leaf(rc->extent_root, path);
3789                         if (ret != 0)
3790                                 break;
3791                         leaf = path->nodes[0];
3792                 }
3793
3794                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3795                 if (key.objectid >= last) {
3796                         ret = 1;
3797                         break;
3798                 }
3799
3800                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3801                     key.type != BTRFS_METADATA_ITEM_KEY) {
3802                         path->slots[0]++;
3803                         goto next;
3804                 }
3805
3806                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3807                     key.objectid + key.offset <= rc->search_start) {
3808                         path->slots[0]++;
3809                         goto next;
3810                 }
3811
3812                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3813                     key.objectid + rc->extent_root->nodesize <=
3814                     rc->search_start) {
3815                         path->slots[0]++;
3816                         goto next;
3817                 }
3818
3819                 ret = find_first_extent_bit(&rc->processed_blocks,
3820                                             key.objectid, &start, &end,
3821                                             EXTENT_DIRTY, NULL);
3822
3823                 if (ret == 0 && start <= key.objectid) {
3824                         btrfs_release_path(path);
3825                         rc->search_start = end + 1;
3826                 } else {
3827                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3828                                 rc->search_start = key.objectid + key.offset;
3829                         else
3830                                 rc->search_start = key.objectid +
3831                                         rc->extent_root->nodesize;
3832                         memcpy(extent_key, &key, sizeof(key));
3833                         return 0;
3834                 }
3835         }
3836         btrfs_release_path(path);
3837         return ret;
3838 }
3839
3840 static void set_reloc_control(struct reloc_control *rc)
3841 {
3842         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3843
3844         mutex_lock(&fs_info->reloc_mutex);
3845         fs_info->reloc_ctl = rc;
3846         mutex_unlock(&fs_info->reloc_mutex);
3847 }
3848
3849 static void unset_reloc_control(struct reloc_control *rc)
3850 {
3851         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3852
3853         mutex_lock(&fs_info->reloc_mutex);
3854         fs_info->reloc_ctl = NULL;
3855         mutex_unlock(&fs_info->reloc_mutex);
3856 }
3857
3858 static int check_extent_flags(u64 flags)
3859 {
3860         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3861             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3862                 return 1;
3863         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3864             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3865                 return 1;
3866         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3867             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3868                 return 1;
3869         return 0;
3870 }
3871
3872 static noinline_for_stack
3873 int prepare_to_relocate(struct reloc_control *rc)
3874 {
3875         struct btrfs_trans_handle *trans;
3876
3877         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3878                                               BTRFS_BLOCK_RSV_TEMP);
3879         if (!rc->block_rsv)
3880                 return -ENOMEM;
3881
3882         memset(&rc->cluster, 0, sizeof(rc->cluster));
3883         rc->search_start = rc->block_group->key.objectid;
3884         rc->extents_found = 0;
3885         rc->nodes_relocated = 0;
3886         rc->merging_rsv_size = 0;
3887         rc->reserved_bytes = 0;
3888         rc->block_rsv->size = rc->extent_root->nodesize *
3889                               RELOCATION_RESERVED_NODES;
3890
3891         rc->create_reloc_tree = 1;
3892         set_reloc_control(rc);
3893
3894         trans = btrfs_join_transaction(rc->extent_root);
3895         if (IS_ERR(trans)) {
3896                 unset_reloc_control(rc);
3897                 /*
3898                  * extent tree is not a ref_cow tree and has no reloc_root to
3899                  * cleanup.  And callers are responsible to free the above
3900                  * block rsv.
3901                  */
3902                 return PTR_ERR(trans);
3903         }
3904         btrfs_commit_transaction(trans, rc->extent_root);
3905         return 0;
3906 }
3907
3908 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3909 {
3910         struct rb_root blocks = RB_ROOT;
3911         struct btrfs_key key;
3912         struct btrfs_trans_handle *trans = NULL;
3913         struct btrfs_path *path;
3914         struct btrfs_extent_item *ei;
3915         u64 flags;
3916         u32 item_size;
3917         int ret;
3918         int err = 0;
3919         int progress = 0;
3920
3921         path = btrfs_alloc_path();
3922         if (!path)
3923                 return -ENOMEM;
3924         path->reada = 1;
3925
3926         ret = prepare_to_relocate(rc);
3927         if (ret) {
3928                 err = ret;
3929                 goto out_free;
3930         }
3931
3932         while (1) {
3933                 rc->reserved_bytes = 0;
3934                 ret = btrfs_block_rsv_refill(rc->extent_root,
3935                                         rc->block_rsv, rc->block_rsv->size,
3936                                         BTRFS_RESERVE_FLUSH_ALL);
3937                 if (ret) {
3938                         err = ret;
3939                         break;
3940                 }
3941                 progress++;
3942                 trans = btrfs_start_transaction(rc->extent_root, 0);
3943                 if (IS_ERR(trans)) {
3944                         err = PTR_ERR(trans);
3945                         trans = NULL;
3946                         break;
3947                 }
3948 restart:
3949                 if (update_backref_cache(trans, &rc->backref_cache)) {
3950                         btrfs_end_transaction(trans, rc->extent_root);
3951                         continue;
3952                 }
3953
3954                 ret = find_next_extent(trans, rc, path, &key);
3955                 if (ret < 0)
3956                         err = ret;
3957                 if (ret != 0)
3958                         break;
3959
3960                 rc->extents_found++;
3961
3962                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3963                                     struct btrfs_extent_item);
3964                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3965                 if (item_size >= sizeof(*ei)) {
3966                         flags = btrfs_extent_flags(path->nodes[0], ei);
3967                         ret = check_extent_flags(flags);
3968                         BUG_ON(ret);
3969
3970                 } else {
3971 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3972                         u64 ref_owner;
3973                         int path_change = 0;
3974
3975                         BUG_ON(item_size !=
3976                                sizeof(struct btrfs_extent_item_v0));
3977                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3978                                                   &path_change);
3979                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3980                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3981                         else
3982                                 flags = BTRFS_EXTENT_FLAG_DATA;
3983
3984                         if (path_change) {
3985                                 btrfs_release_path(path);
3986
3987                                 path->search_commit_root = 1;
3988                                 path->skip_locking = 1;
3989                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3990                                                         &key, path, 0, 0);
3991                                 if (ret < 0) {
3992                                         err = ret;
3993                                         break;
3994                                 }
3995                                 BUG_ON(ret > 0);
3996                         }
3997 #else
3998                         BUG();
3999 #endif
4000                 }
4001
4002                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4003                         ret = add_tree_block(rc, &key, path, &blocks);
4004                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4005                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4006                         ret = add_data_references(rc, &key, path, &blocks);
4007                 } else {
4008                         btrfs_release_path(path);
4009                         ret = 0;
4010                 }
4011                 if (ret < 0) {
4012                         err = ret;
4013                         break;
4014                 }
4015
4016                 if (!RB_EMPTY_ROOT(&blocks)) {
4017                         ret = relocate_tree_blocks(trans, rc, &blocks);
4018                         if (ret < 0) {
4019                                 /*
4020                                  * if we fail to relocate tree blocks, force to update
4021                                  * backref cache when committing transaction.
4022                                  */
4023                                 rc->backref_cache.last_trans = trans->transid - 1;
4024
4025                                 if (ret != -EAGAIN) {
4026                                         err = ret;
4027                                         break;
4028                                 }
4029                                 rc->extents_found--;
4030                                 rc->search_start = key.objectid;
4031                         }
4032                 }
4033
4034                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4035                 btrfs_btree_balance_dirty(rc->extent_root);
4036                 trans = NULL;
4037
4038                 if (rc->stage == MOVE_DATA_EXTENTS &&
4039                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4040                         rc->found_file_extent = 1;
4041                         ret = relocate_data_extent(rc->data_inode,
4042                                                    &key, &rc->cluster);
4043                         if (ret < 0) {
4044                                 err = ret;
4045                                 break;
4046                         }
4047                 }
4048         }
4049         if (trans && progress && err == -ENOSPC) {
4050                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4051                                               rc->block_group->flags);
4052                 if (ret == 1) {
4053                         err = 0;
4054                         progress = 0;
4055                         goto restart;
4056                 }
4057         }
4058
4059         btrfs_release_path(path);
4060         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4061                           GFP_NOFS);
4062
4063         if (trans) {
4064                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4065                 btrfs_btree_balance_dirty(rc->extent_root);
4066         }
4067
4068         if (!err) {
4069                 ret = relocate_file_extent_cluster(rc->data_inode,
4070                                                    &rc->cluster);
4071                 if (ret < 0)
4072                         err = ret;
4073         }
4074
4075         rc->create_reloc_tree = 0;
4076         set_reloc_control(rc);
4077
4078         backref_cache_cleanup(&rc->backref_cache);
4079         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4080
4081         err = prepare_to_merge(rc, err);
4082
4083         merge_reloc_roots(rc);
4084
4085         rc->merge_reloc_tree = 0;
4086         unset_reloc_control(rc);
4087         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4088
4089         /* get rid of pinned extents */
4090         trans = btrfs_join_transaction(rc->extent_root);
4091         if (IS_ERR(trans))
4092                 err = PTR_ERR(trans);
4093         else
4094                 btrfs_commit_transaction(trans, rc->extent_root);
4095 out_free:
4096         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4097         btrfs_free_path(path);
4098         return err;
4099 }
4100
4101 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4102                                  struct btrfs_root *root, u64 objectid)
4103 {
4104         struct btrfs_path *path;
4105         struct btrfs_inode_item *item;
4106         struct extent_buffer *leaf;
4107         int ret;
4108
4109         path = btrfs_alloc_path();
4110         if (!path)
4111                 return -ENOMEM;
4112
4113         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4114         if (ret)
4115                 goto out;
4116
4117         leaf = path->nodes[0];
4118         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4119         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4120         btrfs_set_inode_generation(leaf, item, 1);
4121         btrfs_set_inode_size(leaf, item, 0);
4122         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4123         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4124                                           BTRFS_INODE_PREALLOC);
4125         btrfs_mark_buffer_dirty(leaf);
4126 out:
4127         btrfs_free_path(path);
4128         return ret;
4129 }
4130
4131 /*
4132  * helper to create inode for data relocation.
4133  * the inode is in data relocation tree and its link count is 0
4134  */
4135 static noinline_for_stack
4136 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4137                                  struct btrfs_block_group_cache *group)
4138 {
4139         struct inode *inode = NULL;
4140         struct btrfs_trans_handle *trans;
4141         struct btrfs_root *root;
4142         struct btrfs_key key;
4143         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
4144         int err = 0;
4145
4146         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4147         if (IS_ERR(root))
4148                 return ERR_CAST(root);
4149
4150         trans = btrfs_start_transaction(root, 6);
4151         if (IS_ERR(trans))
4152                 return ERR_CAST(trans);
4153
4154         err = btrfs_find_free_objectid(root, &objectid);
4155         if (err)
4156                 goto out;
4157
4158         err = __insert_orphan_inode(trans, root, objectid);
4159         BUG_ON(err);
4160
4161         key.objectid = objectid;
4162         key.type = BTRFS_INODE_ITEM_KEY;
4163         key.offset = 0;
4164         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4165         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4166         BTRFS_I(inode)->index_cnt = group->key.objectid;
4167
4168         err = btrfs_orphan_add(trans, inode);
4169 out:
4170         btrfs_end_transaction(trans, root);
4171         btrfs_btree_balance_dirty(root);
4172         if (err) {
4173                 if (inode)
4174                         iput(inode);
4175                 inode = ERR_PTR(err);
4176         }
4177         return inode;
4178 }
4179
4180 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4181 {
4182         struct reloc_control *rc;
4183
4184         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4185         if (!rc)
4186                 return NULL;
4187
4188         INIT_LIST_HEAD(&rc->reloc_roots);
4189         backref_cache_init(&rc->backref_cache);
4190         mapping_tree_init(&rc->reloc_root_tree);
4191         extent_io_tree_init(&rc->processed_blocks,
4192                             fs_info->btree_inode->i_mapping);
4193         return rc;
4194 }
4195
4196 /*
4197  * function to relocate all extents in a block group.
4198  */
4199 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4200 {
4201         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4202         struct reloc_control *rc;
4203         struct inode *inode;
4204         struct btrfs_path *path;
4205         int ret;
4206         int rw = 0;
4207         int err = 0;
4208
4209         rc = alloc_reloc_control(fs_info);
4210         if (!rc)
4211                 return -ENOMEM;
4212
4213         rc->extent_root = extent_root;
4214
4215         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4216         BUG_ON(!rc->block_group);
4217
4218         if (!rc->block_group->ro) {
4219                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4220                 if (ret) {
4221                         err = ret;
4222                         goto out;
4223                 }
4224                 rw = 1;
4225         }
4226
4227         path = btrfs_alloc_path();
4228         if (!path) {
4229                 err = -ENOMEM;
4230                 goto out;
4231         }
4232
4233         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4234                                         path);
4235         btrfs_free_path(path);
4236
4237         if (!IS_ERR(inode))
4238                 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4239         else
4240                 ret = PTR_ERR(inode);
4241
4242         if (ret && ret != -ENOENT) {
4243                 err = ret;
4244                 goto out;
4245         }
4246
4247         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4248         if (IS_ERR(rc->data_inode)) {
4249                 err = PTR_ERR(rc->data_inode);
4250                 rc->data_inode = NULL;
4251                 goto out;
4252         }
4253
4254         btrfs_info(extent_root->fs_info, "relocating block group %llu flags %llu",
4255                rc->block_group->key.objectid, rc->block_group->flags);
4256
4257         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
4258         if (ret < 0) {
4259                 err = ret;
4260                 goto out;
4261         }
4262         btrfs_wait_ordered_roots(fs_info, -1);
4263
4264         while (1) {
4265                 mutex_lock(&fs_info->cleaner_mutex);
4266                 ret = relocate_block_group(rc);
4267                 mutex_unlock(&fs_info->cleaner_mutex);
4268                 if (ret < 0) {
4269                         err = ret;
4270                         goto out;
4271                 }
4272
4273                 if (rc->extents_found == 0)
4274                         break;
4275
4276                 btrfs_info(extent_root->fs_info, "found %llu extents",
4277                         rc->extents_found);
4278
4279                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4280                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4281                                                        (u64)-1);
4282                         if (ret) {
4283                                 err = ret;
4284                                 goto out;
4285                         }
4286                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4287                                                  0, -1);
4288                         rc->stage = UPDATE_DATA_PTRS;
4289                 }
4290         }
4291
4292         WARN_ON(rc->block_group->pinned > 0);
4293         WARN_ON(rc->block_group->reserved > 0);
4294         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4295 out:
4296         if (err && rw)
4297                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4298         iput(rc->data_inode);
4299         btrfs_put_block_group(rc->block_group);
4300         kfree(rc);
4301         return err;
4302 }
4303
4304 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4305 {
4306         struct btrfs_trans_handle *trans;
4307         int ret, err;
4308
4309         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4310         if (IS_ERR(trans))
4311                 return PTR_ERR(trans);
4312
4313         memset(&root->root_item.drop_progress, 0,
4314                 sizeof(root->root_item.drop_progress));
4315         root->root_item.drop_level = 0;
4316         btrfs_set_root_refs(&root->root_item, 0);
4317         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4318                                 &root->root_key, &root->root_item);
4319
4320         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4321         if (err)
4322                 return err;
4323         return ret;
4324 }
4325
4326 /*
4327  * recover relocation interrupted by system crash.
4328  *
4329  * this function resumes merging reloc trees with corresponding fs trees.
4330  * this is important for keeping the sharing of tree blocks
4331  */
4332 int btrfs_recover_relocation(struct btrfs_root *root)
4333 {
4334         LIST_HEAD(reloc_roots);
4335         struct btrfs_key key;
4336         struct btrfs_root *fs_root;
4337         struct btrfs_root *reloc_root;
4338         struct btrfs_path *path;
4339         struct extent_buffer *leaf;
4340         struct reloc_control *rc = NULL;
4341         struct btrfs_trans_handle *trans;
4342         int ret;
4343         int err = 0;
4344
4345         path = btrfs_alloc_path();
4346         if (!path)
4347                 return -ENOMEM;
4348         path->reada = -1;
4349
4350         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4351         key.type = BTRFS_ROOT_ITEM_KEY;
4352         key.offset = (u64)-1;
4353
4354         while (1) {
4355                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4356                                         path, 0, 0);
4357                 if (ret < 0) {
4358                         err = ret;
4359                         goto out;
4360                 }
4361                 if (ret > 0) {
4362                         if (path->slots[0] == 0)
4363                                 break;
4364                         path->slots[0]--;
4365                 }
4366                 leaf = path->nodes[0];
4367                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4368                 btrfs_release_path(path);
4369
4370                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4371                     key.type != BTRFS_ROOT_ITEM_KEY)
4372                         break;
4373
4374                 reloc_root = btrfs_read_fs_root(root, &key);
4375                 if (IS_ERR(reloc_root)) {
4376                         err = PTR_ERR(reloc_root);
4377                         goto out;
4378                 }
4379
4380                 list_add(&reloc_root->root_list, &reloc_roots);
4381
4382                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4383                         fs_root = read_fs_root(root->fs_info,
4384                                                reloc_root->root_key.offset);
4385                         if (IS_ERR(fs_root)) {
4386                                 ret = PTR_ERR(fs_root);
4387                                 if (ret != -ENOENT) {
4388                                         err = ret;
4389                                         goto out;
4390                                 }
4391                                 ret = mark_garbage_root(reloc_root);
4392                                 if (ret < 0) {
4393                                         err = ret;
4394                                         goto out;
4395                                 }
4396                         }
4397                 }
4398
4399                 if (key.offset == 0)
4400                         break;
4401
4402                 key.offset--;
4403         }
4404         btrfs_release_path(path);
4405
4406         if (list_empty(&reloc_roots))
4407                 goto out;
4408
4409         rc = alloc_reloc_control(root->fs_info);
4410         if (!rc) {
4411                 err = -ENOMEM;
4412                 goto out;
4413         }
4414
4415         rc->extent_root = root->fs_info->extent_root;
4416
4417         set_reloc_control(rc);
4418
4419         trans = btrfs_join_transaction(rc->extent_root);
4420         if (IS_ERR(trans)) {
4421                 unset_reloc_control(rc);
4422                 err = PTR_ERR(trans);
4423                 goto out_free;
4424         }
4425
4426         rc->merge_reloc_tree = 1;
4427
4428         while (!list_empty(&reloc_roots)) {
4429                 reloc_root = list_entry(reloc_roots.next,
4430                                         struct btrfs_root, root_list);
4431                 list_del(&reloc_root->root_list);
4432
4433                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4434                         list_add_tail(&reloc_root->root_list,
4435                                       &rc->reloc_roots);
4436                         continue;
4437                 }
4438
4439                 fs_root = read_fs_root(root->fs_info,
4440                                        reloc_root->root_key.offset);
4441                 if (IS_ERR(fs_root)) {
4442                         err = PTR_ERR(fs_root);
4443                         goto out_free;
4444                 }
4445
4446                 err = __add_reloc_root(reloc_root);
4447                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4448                 fs_root->reloc_root = reloc_root;
4449         }
4450
4451         err = btrfs_commit_transaction(trans, rc->extent_root);
4452         if (err)
4453                 goto out_free;
4454
4455         merge_reloc_roots(rc);
4456
4457         unset_reloc_control(rc);
4458
4459         trans = btrfs_join_transaction(rc->extent_root);
4460         if (IS_ERR(trans))
4461                 err = PTR_ERR(trans);
4462         else
4463                 err = btrfs_commit_transaction(trans, rc->extent_root);
4464 out_free:
4465         kfree(rc);
4466 out:
4467         if (!list_empty(&reloc_roots))
4468                 free_reloc_roots(&reloc_roots);
4469
4470         btrfs_free_path(path);
4471
4472         if (err == 0) {
4473                 /* cleanup orphan inode in data relocation tree */
4474                 fs_root = read_fs_root(root->fs_info,
4475                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4476                 if (IS_ERR(fs_root))
4477                         err = PTR_ERR(fs_root);
4478                 else
4479                         err = btrfs_orphan_cleanup(fs_root);
4480         }
4481         return err;
4482 }
4483
4484 /*
4485  * helper to add ordered checksum for data relocation.
4486  *
4487  * cloning checksum properly handles the nodatasum extents.
4488  * it also saves CPU time to re-calculate the checksum.
4489  */
4490 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4491 {
4492         struct btrfs_ordered_sum *sums;
4493         struct btrfs_ordered_extent *ordered;
4494         struct btrfs_root *root = BTRFS_I(inode)->root;
4495         int ret;
4496         u64 disk_bytenr;
4497         u64 new_bytenr;
4498         LIST_HEAD(list);
4499
4500         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4501         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4502
4503         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4504         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4505                                        disk_bytenr + len - 1, &list, 0);
4506         if (ret)
4507                 goto out;
4508
4509         while (!list_empty(&list)) {
4510                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4511                 list_del_init(&sums->list);
4512
4513                 /*
4514                  * We need to offset the new_bytenr based on where the csum is.
4515                  * We need to do this because we will read in entire prealloc
4516                  * extents but we may have written to say the middle of the
4517                  * prealloc extent, so we need to make sure the csum goes with
4518                  * the right disk offset.
4519                  *
4520                  * We can do this because the data reloc inode refers strictly
4521                  * to the on disk bytes, so we don't have to worry about
4522                  * disk_len vs real len like with real inodes since it's all
4523                  * disk length.
4524                  */
4525                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4526                 sums->bytenr = new_bytenr;
4527
4528                 btrfs_add_ordered_sum(inode, ordered, sums);
4529         }
4530 out:
4531         btrfs_put_ordered_extent(ordered);
4532         return ret;
4533 }
4534
4535 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4536                           struct btrfs_root *root, struct extent_buffer *buf,
4537                           struct extent_buffer *cow)
4538 {
4539         struct reloc_control *rc;
4540         struct backref_node *node;
4541         int first_cow = 0;
4542         int level;
4543         int ret = 0;
4544
4545         rc = root->fs_info->reloc_ctl;
4546         if (!rc)
4547                 return 0;
4548
4549         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4550                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4551
4552         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4553                 if (buf == root->node)
4554                         __update_reloc_root(root, cow->start);
4555         }
4556
4557         level = btrfs_header_level(buf);
4558         if (btrfs_header_generation(buf) <=
4559             btrfs_root_last_snapshot(&root->root_item))
4560                 first_cow = 1;
4561
4562         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4563             rc->create_reloc_tree) {
4564                 WARN_ON(!first_cow && level == 0);
4565
4566                 node = rc->backref_cache.path[level];
4567                 BUG_ON(node->bytenr != buf->start &&
4568                        node->new_bytenr != buf->start);
4569
4570                 drop_node_buffer(node);
4571                 extent_buffer_get(cow);
4572                 node->eb = cow;
4573                 node->new_bytenr = cow->start;
4574
4575                 if (!node->pending) {
4576                         list_move_tail(&node->list,
4577                                        &rc->backref_cache.pending[level]);
4578                         node->pending = 1;
4579                 }
4580
4581                 if (first_cow)
4582                         __mark_block_processed(rc, node);
4583
4584                 if (first_cow && level > 0)
4585                         rc->nodes_relocated += buf->len;
4586         }
4587
4588         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4589                 ret = replace_file_extents(trans, rc, root, cow);
4590         return ret;
4591 }
4592
4593 /*
4594  * called before creating snapshot. it calculates metadata reservation
4595  * requried for relocating tree blocks in the snapshot
4596  */
4597 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4598                               struct btrfs_pending_snapshot *pending,
4599                               u64 *bytes_to_reserve)
4600 {
4601         struct btrfs_root *root;
4602         struct reloc_control *rc;
4603
4604         root = pending->root;
4605         if (!root->reloc_root)
4606                 return;
4607
4608         rc = root->fs_info->reloc_ctl;
4609         if (!rc->merge_reloc_tree)
4610                 return;
4611
4612         root = root->reloc_root;
4613         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4614         /*
4615          * relocation is in the stage of merging trees. the space
4616          * used by merging a reloc tree is twice the size of
4617          * relocated tree nodes in the worst case. half for cowing
4618          * the reloc tree, half for cowing the fs tree. the space
4619          * used by cowing the reloc tree will be freed after the
4620          * tree is dropped. if we create snapshot, cowing the fs
4621          * tree may use more space than it frees. so we need
4622          * reserve extra space.
4623          */
4624         *bytes_to_reserve += rc->nodes_relocated;
4625 }
4626
4627 /*
4628  * called after snapshot is created. migrate block reservation
4629  * and create reloc root for the newly created snapshot
4630  */
4631 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4632                                struct btrfs_pending_snapshot *pending)
4633 {
4634         struct btrfs_root *root = pending->root;
4635         struct btrfs_root *reloc_root;
4636         struct btrfs_root *new_root;
4637         struct reloc_control *rc;
4638         int ret;
4639
4640         if (!root->reloc_root)
4641                 return 0;
4642
4643         rc = root->fs_info->reloc_ctl;
4644         rc->merging_rsv_size += rc->nodes_relocated;
4645
4646         if (rc->merge_reloc_tree) {
4647                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4648                                               rc->block_rsv,
4649                                               rc->nodes_relocated);
4650                 if (ret)
4651                         return ret;
4652         }
4653
4654         new_root = pending->snap;
4655         reloc_root = create_reloc_root(trans, root->reloc_root,
4656                                        new_root->root_key.objectid);
4657         if (IS_ERR(reloc_root))
4658                 return PTR_ERR(reloc_root);
4659
4660         ret = __add_reloc_root(reloc_root);
4661         BUG_ON(ret < 0);
4662         new_root->reloc_root = reloc_root;
4663
4664         if (rc->create_reloc_tree)
4665                 ret = clone_backref_node(trans, rc, root, reloc_root);
4666         return ret;
4667 }