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, blocksize,
1850                                              old_ptr_gen);
1851                         if (!eb || !extent_buffer_uptodate(eb)) {
1852                                 ret = (!eb) ? -ENOMEM : -EIO;
1853                                 free_extent_buffer(eb);
1854                                 break;
1855                         }
1856                         btrfs_tree_lock(eb);
1857                         if (cow) {
1858                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1859                                                       slot, &eb);
1860                                 BUG_ON(ret);
1861                         }
1862                         btrfs_set_lock_blocking(eb);
1863
1864                         btrfs_tree_unlock(parent);
1865                         free_extent_buffer(parent);
1866
1867                         parent = eb;
1868                         continue;
1869                 }
1870
1871                 if (!cow) {
1872                         btrfs_tree_unlock(parent);
1873                         free_extent_buffer(parent);
1874                         cow = 1;
1875                         goto again;
1876                 }
1877
1878                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1879                                       path->slots[level]);
1880                 btrfs_release_path(path);
1881
1882                 path->lowest_level = level;
1883                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1884                 path->lowest_level = 0;
1885                 BUG_ON(ret);
1886
1887                 /*
1888                  * swap blocks in fs tree and reloc tree.
1889                  */
1890                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1891                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1892                 btrfs_mark_buffer_dirty(parent);
1893
1894                 btrfs_set_node_blockptr(path->nodes[level],
1895                                         path->slots[level], old_bytenr);
1896                 btrfs_set_node_ptr_generation(path->nodes[level],
1897                                               path->slots[level], old_ptr_gen);
1898                 btrfs_mark_buffer_dirty(path->nodes[level]);
1899
1900                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1901                                         path->nodes[level]->start,
1902                                         src->root_key.objectid, level - 1, 0,
1903                                         1);
1904                 BUG_ON(ret);
1905                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1906                                         0, dest->root_key.objectid, level - 1,
1907                                         0, 1);
1908                 BUG_ON(ret);
1909
1910                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1911                                         path->nodes[level]->start,
1912                                         src->root_key.objectid, level - 1, 0,
1913                                         1);
1914                 BUG_ON(ret);
1915
1916                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1917                                         0, dest->root_key.objectid, level - 1,
1918                                         0, 1);
1919                 BUG_ON(ret);
1920
1921                 btrfs_unlock_up_safe(path, 0);
1922
1923                 ret = level;
1924                 break;
1925         }
1926         btrfs_tree_unlock(parent);
1927         free_extent_buffer(parent);
1928         return ret;
1929 }
1930
1931 /*
1932  * helper to find next relocated block in reloc tree
1933  */
1934 static noinline_for_stack
1935 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1936                        int *level)
1937 {
1938         struct extent_buffer *eb;
1939         int i;
1940         u64 last_snapshot;
1941         u32 nritems;
1942
1943         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1944
1945         for (i = 0; i < *level; i++) {
1946                 free_extent_buffer(path->nodes[i]);
1947                 path->nodes[i] = NULL;
1948         }
1949
1950         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1951                 eb = path->nodes[i];
1952                 nritems = btrfs_header_nritems(eb);
1953                 while (path->slots[i] + 1 < nritems) {
1954                         path->slots[i]++;
1955                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1956                             last_snapshot)
1957                                 continue;
1958
1959                         *level = i;
1960                         return 0;
1961                 }
1962                 free_extent_buffer(path->nodes[i]);
1963                 path->nodes[i] = NULL;
1964         }
1965         return 1;
1966 }
1967
1968 /*
1969  * walk down reloc tree to find relocated block of lowest level
1970  */
1971 static noinline_for_stack
1972 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1973                          int *level)
1974 {
1975         struct extent_buffer *eb = NULL;
1976         int i;
1977         u64 bytenr;
1978         u64 ptr_gen = 0;
1979         u64 last_snapshot;
1980         u32 blocksize;
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                 blocksize = root->nodesize;
2007                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
2008                 if (!eb || !extent_buffer_uptodate(eb)) {
2009                         free_extent_buffer(eb);
2010                         return -EIO;
2011                 }
2012                 BUG_ON(btrfs_header_level(eb) != i - 1);
2013                 path->nodes[i - 1] = eb;
2014                 path->slots[i - 1] = 0;
2015         }
2016         return 1;
2017 }
2018
2019 /*
2020  * invalidate extent cache for file extents whose key in range of
2021  * [min_key, max_key)
2022  */
2023 static int invalidate_extent_cache(struct btrfs_root *root,
2024                                    struct btrfs_key *min_key,
2025                                    struct btrfs_key *max_key)
2026 {
2027         struct inode *inode = NULL;
2028         u64 objectid;
2029         u64 start, end;
2030         u64 ino;
2031
2032         objectid = min_key->objectid;
2033         while (1) {
2034                 cond_resched();
2035                 iput(inode);
2036
2037                 if (objectid > max_key->objectid)
2038                         break;
2039
2040                 inode = find_next_inode(root, objectid);
2041                 if (!inode)
2042                         break;
2043                 ino = btrfs_ino(inode);
2044
2045                 if (ino > max_key->objectid) {
2046                         iput(inode);
2047                         break;
2048                 }
2049
2050                 objectid = ino + 1;
2051                 if (!S_ISREG(inode->i_mode))
2052                         continue;
2053
2054                 if (unlikely(min_key->objectid == ino)) {
2055                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2056                                 continue;
2057                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2058                                 start = 0;
2059                         else {
2060                                 start = min_key->offset;
2061                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2062                         }
2063                 } else {
2064                         start = 0;
2065                 }
2066
2067                 if (unlikely(max_key->objectid == ino)) {
2068                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2069                                 continue;
2070                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2071                                 end = (u64)-1;
2072                         } else {
2073                                 if (max_key->offset == 0)
2074                                         continue;
2075                                 end = max_key->offset;
2076                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2077                                 end--;
2078                         }
2079                 } else {
2080                         end = (u64)-1;
2081                 }
2082
2083                 /* the lock_extent waits for readpage to complete */
2084                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2085                 btrfs_drop_extent_cache(inode, start, end, 1);
2086                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2087         }
2088         return 0;
2089 }
2090
2091 static int find_next_key(struct btrfs_path *path, int level,
2092                          struct btrfs_key *key)
2093
2094 {
2095         while (level < BTRFS_MAX_LEVEL) {
2096                 if (!path->nodes[level])
2097                         break;
2098                 if (path->slots[level] + 1 <
2099                     btrfs_header_nritems(path->nodes[level])) {
2100                         btrfs_node_key_to_cpu(path->nodes[level], key,
2101                                               path->slots[level] + 1);
2102                         return 0;
2103                 }
2104                 level++;
2105         }
2106         return 1;
2107 }
2108
2109 /*
2110  * merge the relocated tree blocks in reloc tree with corresponding
2111  * fs tree.
2112  */
2113 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2114                                                struct btrfs_root *root)
2115 {
2116         LIST_HEAD(inode_list);
2117         struct btrfs_key key;
2118         struct btrfs_key next_key;
2119         struct btrfs_trans_handle *trans = NULL;
2120         struct btrfs_root *reloc_root;
2121         struct btrfs_root_item *root_item;
2122         struct btrfs_path *path;
2123         struct extent_buffer *leaf;
2124         int level;
2125         int max_level;
2126         int replaced = 0;
2127         int ret;
2128         int err = 0;
2129         u32 min_reserved;
2130
2131         path = btrfs_alloc_path();
2132         if (!path)
2133                 return -ENOMEM;
2134         path->reada = 1;
2135
2136         reloc_root = root->reloc_root;
2137         root_item = &reloc_root->root_item;
2138
2139         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2140                 level = btrfs_root_level(root_item);
2141                 extent_buffer_get(reloc_root->node);
2142                 path->nodes[level] = reloc_root->node;
2143                 path->slots[level] = 0;
2144         } else {
2145                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2146
2147                 level = root_item->drop_level;
2148                 BUG_ON(level == 0);
2149                 path->lowest_level = level;
2150                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2151                 path->lowest_level = 0;
2152                 if (ret < 0) {
2153                         btrfs_free_path(path);
2154                         return ret;
2155                 }
2156
2157                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2158                                       path->slots[level]);
2159                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2160
2161                 btrfs_unlock_up_safe(path, 0);
2162         }
2163
2164         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2165         memset(&next_key, 0, sizeof(next_key));
2166
2167         while (1) {
2168                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2169                                              BTRFS_RESERVE_FLUSH_ALL);
2170                 if (ret) {
2171                         err = ret;
2172                         goto out;
2173                 }
2174                 trans = btrfs_start_transaction(root, 0);
2175                 if (IS_ERR(trans)) {
2176                         err = PTR_ERR(trans);
2177                         trans = NULL;
2178                         goto out;
2179                 }
2180                 trans->block_rsv = rc->block_rsv;
2181
2182                 replaced = 0;
2183                 max_level = level;
2184
2185                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2186                 if (ret < 0) {
2187                         err = ret;
2188                         goto out;
2189                 }
2190                 if (ret > 0)
2191                         break;
2192
2193                 if (!find_next_key(path, level, &key) &&
2194                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2195                         ret = 0;
2196                 } else {
2197                         ret = replace_path(trans, root, reloc_root, path,
2198                                            &next_key, level, max_level);
2199                 }
2200                 if (ret < 0) {
2201                         err = ret;
2202                         goto out;
2203                 }
2204
2205                 if (ret > 0) {
2206                         level = ret;
2207                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2208                                               path->slots[level]);
2209                         replaced = 1;
2210                 }
2211
2212                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2213                 if (ret > 0)
2214                         break;
2215
2216                 BUG_ON(level == 0);
2217                 /*
2218                  * save the merging progress in the drop_progress.
2219                  * this is OK since root refs == 1 in this case.
2220                  */
2221                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2222                                path->slots[level]);
2223                 root_item->drop_level = level;
2224
2225                 btrfs_end_transaction_throttle(trans, root);
2226                 trans = NULL;
2227
2228                 btrfs_btree_balance_dirty(root);
2229
2230                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2231                         invalidate_extent_cache(root, &key, &next_key);
2232         }
2233
2234         /*
2235          * handle the case only one block in the fs tree need to be
2236          * relocated and the block is tree root.
2237          */
2238         leaf = btrfs_lock_root_node(root);
2239         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2240         btrfs_tree_unlock(leaf);
2241         free_extent_buffer(leaf);
2242         if (ret < 0)
2243                 err = ret;
2244 out:
2245         btrfs_free_path(path);
2246
2247         if (err == 0) {
2248                 memset(&root_item->drop_progress, 0,
2249                        sizeof(root_item->drop_progress));
2250                 root_item->drop_level = 0;
2251                 btrfs_set_root_refs(root_item, 0);
2252                 btrfs_update_reloc_root(trans, root);
2253         }
2254
2255         if (trans)
2256                 btrfs_end_transaction_throttle(trans, root);
2257
2258         btrfs_btree_balance_dirty(root);
2259
2260         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2261                 invalidate_extent_cache(root, &key, &next_key);
2262
2263         return err;
2264 }
2265
2266 static noinline_for_stack
2267 int prepare_to_merge(struct reloc_control *rc, int err)
2268 {
2269         struct btrfs_root *root = rc->extent_root;
2270         struct btrfs_root *reloc_root;
2271         struct btrfs_trans_handle *trans;
2272         LIST_HEAD(reloc_roots);
2273         u64 num_bytes = 0;
2274         int ret;
2275
2276         mutex_lock(&root->fs_info->reloc_mutex);
2277         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2278         rc->merging_rsv_size += rc->nodes_relocated * 2;
2279         mutex_unlock(&root->fs_info->reloc_mutex);
2280
2281 again:
2282         if (!err) {
2283                 num_bytes = rc->merging_rsv_size;
2284                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2285                                           BTRFS_RESERVE_FLUSH_ALL);
2286                 if (ret)
2287                         err = ret;
2288         }
2289
2290         trans = btrfs_join_transaction(rc->extent_root);
2291         if (IS_ERR(trans)) {
2292                 if (!err)
2293                         btrfs_block_rsv_release(rc->extent_root,
2294                                                 rc->block_rsv, num_bytes);
2295                 return PTR_ERR(trans);
2296         }
2297
2298         if (!err) {
2299                 if (num_bytes != rc->merging_rsv_size) {
2300                         btrfs_end_transaction(trans, rc->extent_root);
2301                         btrfs_block_rsv_release(rc->extent_root,
2302                                                 rc->block_rsv, num_bytes);
2303                         goto again;
2304                 }
2305         }
2306
2307         rc->merge_reloc_tree = 1;
2308
2309         while (!list_empty(&rc->reloc_roots)) {
2310                 reloc_root = list_entry(rc->reloc_roots.next,
2311                                         struct btrfs_root, root_list);
2312                 list_del_init(&reloc_root->root_list);
2313
2314                 root = read_fs_root(reloc_root->fs_info,
2315                                     reloc_root->root_key.offset);
2316                 BUG_ON(IS_ERR(root));
2317                 BUG_ON(root->reloc_root != reloc_root);
2318
2319                 /*
2320                  * set reference count to 1, so btrfs_recover_relocation
2321                  * knows it should resumes merging
2322                  */
2323                 if (!err)
2324                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2325                 btrfs_update_reloc_root(trans, root);
2326
2327                 list_add(&reloc_root->root_list, &reloc_roots);
2328         }
2329
2330         list_splice(&reloc_roots, &rc->reloc_roots);
2331
2332         if (!err)
2333                 btrfs_commit_transaction(trans, rc->extent_root);
2334         else
2335                 btrfs_end_transaction(trans, rc->extent_root);
2336         return err;
2337 }
2338
2339 static noinline_for_stack
2340 void free_reloc_roots(struct list_head *list)
2341 {
2342         struct btrfs_root *reloc_root;
2343
2344         while (!list_empty(list)) {
2345                 reloc_root = list_entry(list->next, struct btrfs_root,
2346                                         root_list);
2347                 __del_reloc_root(reloc_root);
2348         }
2349 }
2350
2351 static noinline_for_stack
2352 void merge_reloc_roots(struct reloc_control *rc)
2353 {
2354         struct btrfs_root *root;
2355         struct btrfs_root *reloc_root;
2356         u64 last_snap;
2357         u64 otransid;
2358         u64 objectid;
2359         LIST_HEAD(reloc_roots);
2360         int found = 0;
2361         int ret = 0;
2362 again:
2363         root = rc->extent_root;
2364
2365         /*
2366          * this serializes us with btrfs_record_root_in_transaction,
2367          * we have to make sure nobody is in the middle of
2368          * adding their roots to the list while we are
2369          * doing this splice
2370          */
2371         mutex_lock(&root->fs_info->reloc_mutex);
2372         list_splice_init(&rc->reloc_roots, &reloc_roots);
2373         mutex_unlock(&root->fs_info->reloc_mutex);
2374
2375         while (!list_empty(&reloc_roots)) {
2376                 found = 1;
2377                 reloc_root = list_entry(reloc_roots.next,
2378                                         struct btrfs_root, root_list);
2379
2380                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2381                         root = read_fs_root(reloc_root->fs_info,
2382                                             reloc_root->root_key.offset);
2383                         BUG_ON(IS_ERR(root));
2384                         BUG_ON(root->reloc_root != reloc_root);
2385
2386                         ret = merge_reloc_root(rc, root);
2387                         if (ret) {
2388                                 if (list_empty(&reloc_root->root_list))
2389                                         list_add_tail(&reloc_root->root_list,
2390                                                       &reloc_roots);
2391                                 goto out;
2392                         }
2393                 } else {
2394                         list_del_init(&reloc_root->root_list);
2395                 }
2396
2397                 /*
2398                  * we keep the old last snapshod transid in rtranid when we
2399                  * created the relocation tree.
2400                  */
2401                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2402                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2403                 objectid = reloc_root->root_key.offset;
2404
2405                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2406                 if (ret < 0) {
2407                         if (list_empty(&reloc_root->root_list))
2408                                 list_add_tail(&reloc_root->root_list,
2409                                               &reloc_roots);
2410                         goto out;
2411                 }
2412         }
2413
2414         if (found) {
2415                 found = 0;
2416                 goto again;
2417         }
2418 out:
2419         if (ret) {
2420                 btrfs_std_error(root->fs_info, ret);
2421                 if (!list_empty(&reloc_roots))
2422                         free_reloc_roots(&reloc_roots);
2423
2424                 /* new reloc root may be added */
2425                 mutex_lock(&root->fs_info->reloc_mutex);
2426                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2427                 mutex_unlock(&root->fs_info->reloc_mutex);
2428                 if (!list_empty(&reloc_roots))
2429                         free_reloc_roots(&reloc_roots);
2430         }
2431
2432         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2433 }
2434
2435 static void free_block_list(struct rb_root *blocks)
2436 {
2437         struct tree_block *block;
2438         struct rb_node *rb_node;
2439         while ((rb_node = rb_first(blocks))) {
2440                 block = rb_entry(rb_node, struct tree_block, rb_node);
2441                 rb_erase(rb_node, blocks);
2442                 kfree(block);
2443         }
2444 }
2445
2446 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2447                                       struct btrfs_root *reloc_root)
2448 {
2449         struct btrfs_root *root;
2450
2451         if (reloc_root->last_trans == trans->transid)
2452                 return 0;
2453
2454         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2455         BUG_ON(IS_ERR(root));
2456         BUG_ON(root->reloc_root != reloc_root);
2457
2458         return btrfs_record_root_in_trans(trans, root);
2459 }
2460
2461 static noinline_for_stack
2462 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2463                                      struct reloc_control *rc,
2464                                      struct backref_node *node,
2465                                      struct backref_edge *edges[])
2466 {
2467         struct backref_node *next;
2468         struct btrfs_root *root;
2469         int index = 0;
2470
2471         next = node;
2472         while (1) {
2473                 cond_resched();
2474                 next = walk_up_backref(next, edges, &index);
2475                 root = next->root;
2476                 BUG_ON(!root);
2477                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2478
2479                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2480                         record_reloc_root_in_trans(trans, root);
2481                         break;
2482                 }
2483
2484                 btrfs_record_root_in_trans(trans, root);
2485                 root = root->reloc_root;
2486
2487                 if (next->new_bytenr != root->node->start) {
2488                         BUG_ON(next->new_bytenr);
2489                         BUG_ON(!list_empty(&next->list));
2490                         next->new_bytenr = root->node->start;
2491                         next->root = root;
2492                         list_add_tail(&next->list,
2493                                       &rc->backref_cache.changed);
2494                         __mark_block_processed(rc, next);
2495                         break;
2496                 }
2497
2498                 WARN_ON(1);
2499                 root = NULL;
2500                 next = walk_down_backref(edges, &index);
2501                 if (!next || next->level <= node->level)
2502                         break;
2503         }
2504         if (!root)
2505                 return NULL;
2506
2507         next = node;
2508         /* setup backref node path for btrfs_reloc_cow_block */
2509         while (1) {
2510                 rc->backref_cache.path[next->level] = next;
2511                 if (--index < 0)
2512                         break;
2513                 next = edges[index]->node[UPPER];
2514         }
2515         return root;
2516 }
2517
2518 /*
2519  * select a tree root for relocation. return NULL if the block
2520  * is reference counted. we should use do_relocation() in this
2521  * case. return a tree root pointer if the block isn't reference
2522  * counted. return -ENOENT if the block is root of reloc tree.
2523  */
2524 static noinline_for_stack
2525 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2526                                    struct backref_node *node)
2527 {
2528         struct backref_node *next;
2529         struct btrfs_root *root;
2530         struct btrfs_root *fs_root = NULL;
2531         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2532         int index = 0;
2533
2534         next = node;
2535         while (1) {
2536                 cond_resched();
2537                 next = walk_up_backref(next, edges, &index);
2538                 root = next->root;
2539                 BUG_ON(!root);
2540
2541                 /* no other choice for non-references counted tree */
2542                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2543                         return root;
2544
2545                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2546                         fs_root = root;
2547
2548                 if (next != node)
2549                         return NULL;
2550
2551                 next = walk_down_backref(edges, &index);
2552                 if (!next || next->level <= node->level)
2553                         break;
2554         }
2555
2556         if (!fs_root)
2557                 return ERR_PTR(-ENOENT);
2558         return fs_root;
2559 }
2560
2561 static noinline_for_stack
2562 u64 calcu_metadata_size(struct reloc_control *rc,
2563                         struct backref_node *node, int reserve)
2564 {
2565         struct backref_node *next = node;
2566         struct backref_edge *edge;
2567         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2568         u64 num_bytes = 0;
2569         int index = 0;
2570
2571         BUG_ON(reserve && node->processed);
2572
2573         while (next) {
2574                 cond_resched();
2575                 while (1) {
2576                         if (next->processed && (reserve || next != node))
2577                                 break;
2578
2579                         num_bytes += rc->extent_root->nodesize;
2580
2581                         if (list_empty(&next->upper))
2582                                 break;
2583
2584                         edge = list_entry(next->upper.next,
2585                                           struct backref_edge, list[LOWER]);
2586                         edges[index++] = edge;
2587                         next = edge->node[UPPER];
2588                 }
2589                 next = walk_down_backref(edges, &index);
2590         }
2591         return num_bytes;
2592 }
2593
2594 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2595                                   struct reloc_control *rc,
2596                                   struct backref_node *node)
2597 {
2598         struct btrfs_root *root = rc->extent_root;
2599         u64 num_bytes;
2600         int ret;
2601         u64 tmp;
2602
2603         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2604
2605         trans->block_rsv = rc->block_rsv;
2606         rc->reserved_bytes += num_bytes;
2607         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2608                                 BTRFS_RESERVE_FLUSH_ALL);
2609         if (ret) {
2610                 if (ret == -EAGAIN) {
2611                         tmp = rc->extent_root->nodesize *
2612                                 RELOCATION_RESERVED_NODES;
2613                         while (tmp <= rc->reserved_bytes)
2614                                 tmp <<= 1;
2615                         /*
2616                          * only one thread can access block_rsv at this point,
2617                          * so we don't need hold lock to protect block_rsv.
2618                          * we expand more reservation size here to allow enough
2619                          * space for relocation and we will return eailer in
2620                          * enospc case.
2621                          */
2622                         rc->block_rsv->size = tmp + rc->extent_root->nodesize *
2623                                               RELOCATION_RESERVED_NODES;
2624                 }
2625                 return ret;
2626         }
2627
2628         return 0;
2629 }
2630
2631 /*
2632  * relocate a block tree, and then update pointers in upper level
2633  * blocks that reference the block to point to the new location.
2634  *
2635  * if called by link_to_upper, the block has already been relocated.
2636  * in that case this function just updates pointers.
2637  */
2638 static int do_relocation(struct btrfs_trans_handle *trans,
2639                          struct reloc_control *rc,
2640                          struct backref_node *node,
2641                          struct btrfs_key *key,
2642                          struct btrfs_path *path, int lowest)
2643 {
2644         struct backref_node *upper;
2645         struct backref_edge *edge;
2646         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2647         struct btrfs_root *root;
2648         struct extent_buffer *eb;
2649         u32 blocksize;
2650         u64 bytenr;
2651         u64 generation;
2652         int slot;
2653         int ret;
2654         int err = 0;
2655
2656         BUG_ON(lowest && node->eb);
2657
2658         path->lowest_level = node->level + 1;
2659         rc->backref_cache.path[node->level] = node;
2660         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2661                 cond_resched();
2662
2663                 upper = edge->node[UPPER];
2664                 root = select_reloc_root(trans, rc, upper, edges);
2665                 BUG_ON(!root);
2666
2667                 if (upper->eb && !upper->locked) {
2668                         if (!lowest) {
2669                                 ret = btrfs_bin_search(upper->eb, key,
2670                                                        upper->level, &slot);
2671                                 BUG_ON(ret);
2672                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2673                                 if (node->eb->start == bytenr)
2674                                         goto next;
2675                         }
2676                         drop_node_buffer(upper);
2677                 }
2678
2679                 if (!upper->eb) {
2680                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2681                         if (ret < 0) {
2682                                 err = ret;
2683                                 break;
2684                         }
2685                         BUG_ON(ret > 0);
2686
2687                         if (!upper->eb) {
2688                                 upper->eb = path->nodes[upper->level];
2689                                 path->nodes[upper->level] = NULL;
2690                         } else {
2691                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2692                         }
2693
2694                         upper->locked = 1;
2695                         path->locks[upper->level] = 0;
2696
2697                         slot = path->slots[upper->level];
2698                         btrfs_release_path(path);
2699                 } else {
2700                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2701                                                &slot);
2702                         BUG_ON(ret);
2703                 }
2704
2705                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2706                 if (lowest) {
2707                         BUG_ON(bytenr != node->bytenr);
2708                 } else {
2709                         if (node->eb->start == bytenr)
2710                                 goto next;
2711                 }
2712
2713                 blocksize = root->nodesize;
2714                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2715                 eb = read_tree_block(root, bytenr, blocksize, generation);
2716                 if (!eb || !extent_buffer_uptodate(eb)) {
2717                         free_extent_buffer(eb);
2718                         err = -EIO;
2719                         goto next;
2720                 }
2721                 btrfs_tree_lock(eb);
2722                 btrfs_set_lock_blocking(eb);
2723
2724                 if (!node->eb) {
2725                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2726                                               slot, &eb);
2727                         btrfs_tree_unlock(eb);
2728                         free_extent_buffer(eb);
2729                         if (ret < 0) {
2730                                 err = ret;
2731                                 goto next;
2732                         }
2733                         BUG_ON(node->eb != eb);
2734                 } else {
2735                         btrfs_set_node_blockptr(upper->eb, slot,
2736                                                 node->eb->start);
2737                         btrfs_set_node_ptr_generation(upper->eb, slot,
2738                                                       trans->transid);
2739                         btrfs_mark_buffer_dirty(upper->eb);
2740
2741                         ret = btrfs_inc_extent_ref(trans, root,
2742                                                 node->eb->start, blocksize,
2743                                                 upper->eb->start,
2744                                                 btrfs_header_owner(upper->eb),
2745                                                 node->level, 0, 1);
2746                         BUG_ON(ret);
2747
2748                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2749                         BUG_ON(ret);
2750                 }
2751 next:
2752                 if (!upper->pending)
2753                         drop_node_buffer(upper);
2754                 else
2755                         unlock_node_buffer(upper);
2756                 if (err)
2757                         break;
2758         }
2759
2760         if (!err && node->pending) {
2761                 drop_node_buffer(node);
2762                 list_move_tail(&node->list, &rc->backref_cache.changed);
2763                 node->pending = 0;
2764         }
2765
2766         path->lowest_level = 0;
2767         BUG_ON(err == -ENOSPC);
2768         return err;
2769 }
2770
2771 static int link_to_upper(struct btrfs_trans_handle *trans,
2772                          struct reloc_control *rc,
2773                          struct backref_node *node,
2774                          struct btrfs_path *path)
2775 {
2776         struct btrfs_key key;
2777
2778         btrfs_node_key_to_cpu(node->eb, &key, 0);
2779         return do_relocation(trans, rc, node, &key, path, 0);
2780 }
2781
2782 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2783                                 struct reloc_control *rc,
2784                                 struct btrfs_path *path, int err)
2785 {
2786         LIST_HEAD(list);
2787         struct backref_cache *cache = &rc->backref_cache;
2788         struct backref_node *node;
2789         int level;
2790         int ret;
2791
2792         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2793                 while (!list_empty(&cache->pending[level])) {
2794                         node = list_entry(cache->pending[level].next,
2795                                           struct backref_node, list);
2796                         list_move_tail(&node->list, &list);
2797                         BUG_ON(!node->pending);
2798
2799                         if (!err) {
2800                                 ret = link_to_upper(trans, rc, node, path);
2801                                 if (ret < 0)
2802                                         err = ret;
2803                         }
2804                 }
2805                 list_splice_init(&list, &cache->pending[level]);
2806         }
2807         return err;
2808 }
2809
2810 static void mark_block_processed(struct reloc_control *rc,
2811                                  u64 bytenr, u32 blocksize)
2812 {
2813         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2814                         EXTENT_DIRTY, GFP_NOFS);
2815 }
2816
2817 static void __mark_block_processed(struct reloc_control *rc,
2818                                    struct backref_node *node)
2819 {
2820         u32 blocksize;
2821         if (node->level == 0 ||
2822             in_block_group(node->bytenr, rc->block_group)) {
2823                 blocksize = rc->extent_root->nodesize;
2824                 mark_block_processed(rc, node->bytenr, blocksize);
2825         }
2826         node->processed = 1;
2827 }
2828
2829 /*
2830  * mark a block and all blocks directly/indirectly reference the block
2831  * as processed.
2832  */
2833 static void update_processed_blocks(struct reloc_control *rc,
2834                                     struct backref_node *node)
2835 {
2836         struct backref_node *next = node;
2837         struct backref_edge *edge;
2838         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2839         int index = 0;
2840
2841         while (next) {
2842                 cond_resched();
2843                 while (1) {
2844                         if (next->processed)
2845                                 break;
2846
2847                         __mark_block_processed(rc, next);
2848
2849                         if (list_empty(&next->upper))
2850                                 break;
2851
2852                         edge = list_entry(next->upper.next,
2853                                           struct backref_edge, list[LOWER]);
2854                         edges[index++] = edge;
2855                         next = edge->node[UPPER];
2856                 }
2857                 next = walk_down_backref(edges, &index);
2858         }
2859 }
2860
2861 static int tree_block_processed(u64 bytenr, u32 blocksize,
2862                                 struct reloc_control *rc)
2863 {
2864         if (test_range_bit(&rc->processed_blocks, bytenr,
2865                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2866                 return 1;
2867         return 0;
2868 }
2869
2870 static int get_tree_block_key(struct reloc_control *rc,
2871                               struct tree_block *block)
2872 {
2873         struct extent_buffer *eb;
2874
2875         BUG_ON(block->key_ready);
2876         eb = read_tree_block(rc->extent_root, block->bytenr,
2877                              block->key.objectid, block->key.offset);
2878         if (!eb || !extent_buffer_uptodate(eb)) {
2879                 free_extent_buffer(eb);
2880                 return -EIO;
2881         }
2882         WARN_ON(btrfs_header_level(eb) != block->level);
2883         if (block->level == 0)
2884                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2885         else
2886                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2887         free_extent_buffer(eb);
2888         block->key_ready = 1;
2889         return 0;
2890 }
2891
2892 static int reada_tree_block(struct reloc_control *rc,
2893                             struct tree_block *block)
2894 {
2895         BUG_ON(block->key_ready);
2896         if (block->key.type == BTRFS_METADATA_ITEM_KEY)
2897                 readahead_tree_block(rc->extent_root, block->bytenr,
2898                                      block->key.objectid,
2899                                      rc->extent_root->nodesize);
2900         else
2901                 readahead_tree_block(rc->extent_root, block->bytenr,
2902                                      block->key.objectid, block->key.offset);
2903         return 0;
2904 }
2905
2906 /*
2907  * helper function to relocate a tree block
2908  */
2909 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2910                                 struct reloc_control *rc,
2911                                 struct backref_node *node,
2912                                 struct btrfs_key *key,
2913                                 struct btrfs_path *path)
2914 {
2915         struct btrfs_root *root;
2916         int ret = 0;
2917
2918         if (!node)
2919                 return 0;
2920
2921         BUG_ON(node->processed);
2922         root = select_one_root(trans, node);
2923         if (root == ERR_PTR(-ENOENT)) {
2924                 update_processed_blocks(rc, node);
2925                 goto out;
2926         }
2927
2928         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2929                 ret = reserve_metadata_space(trans, rc, node);
2930                 if (ret)
2931                         goto out;
2932         }
2933
2934         if (root) {
2935                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2936                         BUG_ON(node->new_bytenr);
2937                         BUG_ON(!list_empty(&node->list));
2938                         btrfs_record_root_in_trans(trans, root);
2939                         root = root->reloc_root;
2940                         node->new_bytenr = root->node->start;
2941                         node->root = root;
2942                         list_add_tail(&node->list, &rc->backref_cache.changed);
2943                 } else {
2944                         path->lowest_level = node->level;
2945                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2946                         btrfs_release_path(path);
2947                         if (ret > 0)
2948                                 ret = 0;
2949                 }
2950                 if (!ret)
2951                         update_processed_blocks(rc, node);
2952         } else {
2953                 ret = do_relocation(trans, rc, node, key, path, 1);
2954         }
2955 out:
2956         if (ret || node->level == 0 || node->cowonly)
2957                 remove_backref_node(&rc->backref_cache, node);
2958         return ret;
2959 }
2960
2961 /*
2962  * relocate a list of blocks
2963  */
2964 static noinline_for_stack
2965 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2966                          struct reloc_control *rc, struct rb_root *blocks)
2967 {
2968         struct backref_node *node;
2969         struct btrfs_path *path;
2970         struct tree_block *block;
2971         struct rb_node *rb_node;
2972         int ret;
2973         int err = 0;
2974
2975         path = btrfs_alloc_path();
2976         if (!path) {
2977                 err = -ENOMEM;
2978                 goto out_free_blocks;
2979         }
2980
2981         rb_node = rb_first(blocks);
2982         while (rb_node) {
2983                 block = rb_entry(rb_node, struct tree_block, rb_node);
2984                 if (!block->key_ready)
2985                         reada_tree_block(rc, block);
2986                 rb_node = rb_next(rb_node);
2987         }
2988
2989         rb_node = rb_first(blocks);
2990         while (rb_node) {
2991                 block = rb_entry(rb_node, struct tree_block, rb_node);
2992                 if (!block->key_ready) {
2993                         err = get_tree_block_key(rc, block);
2994                         if (err)
2995                                 goto out_free_path;
2996                 }
2997                 rb_node = rb_next(rb_node);
2998         }
2999
3000         rb_node = rb_first(blocks);
3001         while (rb_node) {
3002                 block = rb_entry(rb_node, struct tree_block, rb_node);
3003
3004                 node = build_backref_tree(rc, &block->key,
3005                                           block->level, block->bytenr);
3006                 if (IS_ERR(node)) {
3007                         err = PTR_ERR(node);
3008                         goto out;
3009                 }
3010
3011                 ret = relocate_tree_block(trans, rc, node, &block->key,
3012                                           path);
3013                 if (ret < 0) {
3014                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3015                                 err = ret;
3016                         goto out;
3017                 }
3018                 rb_node = rb_next(rb_node);
3019         }
3020 out:
3021         err = finish_pending_nodes(trans, rc, path, err);
3022
3023 out_free_path:
3024         btrfs_free_path(path);
3025 out_free_blocks:
3026         free_block_list(blocks);
3027         return err;
3028 }
3029
3030 static noinline_for_stack
3031 int prealloc_file_extent_cluster(struct inode *inode,
3032                                  struct file_extent_cluster *cluster)
3033 {
3034         u64 alloc_hint = 0;
3035         u64 start;
3036         u64 end;
3037         u64 offset = BTRFS_I(inode)->index_cnt;
3038         u64 num_bytes;
3039         int nr = 0;
3040         int ret = 0;
3041
3042         BUG_ON(cluster->start != cluster->boundary[0]);
3043         mutex_lock(&inode->i_mutex);
3044
3045         ret = btrfs_check_data_free_space(inode, cluster->end +
3046                                           1 - cluster->start);
3047         if (ret)
3048                 goto out;
3049
3050         while (nr < cluster->nr) {
3051                 start = cluster->boundary[nr] - offset;
3052                 if (nr + 1 < cluster->nr)
3053                         end = cluster->boundary[nr + 1] - 1 - offset;
3054                 else
3055                         end = cluster->end - offset;
3056
3057                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3058                 num_bytes = end + 1 - start;
3059                 ret = btrfs_prealloc_file_range(inode, 0, start,
3060                                                 num_bytes, num_bytes,
3061                                                 end + 1, &alloc_hint);
3062                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3063                 if (ret)
3064                         break;
3065                 nr++;
3066         }
3067         btrfs_free_reserved_data_space(inode, cluster->end +
3068                                        1 - cluster->start);
3069 out:
3070         mutex_unlock(&inode->i_mutex);
3071         return ret;
3072 }
3073
3074 static noinline_for_stack
3075 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3076                          u64 block_start)
3077 {
3078         struct btrfs_root *root = BTRFS_I(inode)->root;
3079         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3080         struct extent_map *em;
3081         int ret = 0;
3082
3083         em = alloc_extent_map();
3084         if (!em)
3085                 return -ENOMEM;
3086
3087         em->start = start;
3088         em->len = end + 1 - start;
3089         em->block_len = em->len;
3090         em->block_start = block_start;
3091         em->bdev = root->fs_info->fs_devices->latest_bdev;
3092         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3093
3094         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3095         while (1) {
3096                 write_lock(&em_tree->lock);
3097                 ret = add_extent_mapping(em_tree, em, 0);
3098                 write_unlock(&em_tree->lock);
3099                 if (ret != -EEXIST) {
3100                         free_extent_map(em);
3101                         break;
3102                 }
3103                 btrfs_drop_extent_cache(inode, start, end, 0);
3104         }
3105         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3106         return ret;
3107 }
3108
3109 static int relocate_file_extent_cluster(struct inode *inode,
3110                                         struct file_extent_cluster *cluster)
3111 {
3112         u64 page_start;
3113         u64 page_end;
3114         u64 offset = BTRFS_I(inode)->index_cnt;
3115         unsigned long index;
3116         unsigned long last_index;
3117         struct page *page;
3118         struct file_ra_state *ra;
3119         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3120         int nr = 0;
3121         int ret = 0;
3122
3123         if (!cluster->nr)
3124                 return 0;
3125
3126         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3127         if (!ra)
3128                 return -ENOMEM;
3129
3130         ret = prealloc_file_extent_cluster(inode, cluster);
3131         if (ret)
3132                 goto out;
3133
3134         file_ra_state_init(ra, inode->i_mapping);
3135
3136         ret = setup_extent_mapping(inode, cluster->start - offset,
3137                                    cluster->end - offset, cluster->start);
3138         if (ret)
3139                 goto out;
3140
3141         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3142         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3143         while (index <= last_index) {
3144                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3145                 if (ret)
3146                         goto out;
3147
3148                 page = find_lock_page(inode->i_mapping, index);
3149                 if (!page) {
3150                         page_cache_sync_readahead(inode->i_mapping,
3151                                                   ra, NULL, index,
3152                                                   last_index + 1 - index);
3153                         page = find_or_create_page(inode->i_mapping, index,
3154                                                    mask);
3155                         if (!page) {
3156                                 btrfs_delalloc_release_metadata(inode,
3157                                                         PAGE_CACHE_SIZE);
3158                                 ret = -ENOMEM;
3159                                 goto out;
3160                         }
3161                 }
3162
3163                 if (PageReadahead(page)) {
3164                         page_cache_async_readahead(inode->i_mapping,
3165                                                    ra, NULL, page, index,
3166                                                    last_index + 1 - index);
3167                 }
3168
3169                 if (!PageUptodate(page)) {
3170                         btrfs_readpage(NULL, page);
3171                         lock_page(page);
3172                         if (!PageUptodate(page)) {
3173                                 unlock_page(page);
3174                                 page_cache_release(page);
3175                                 btrfs_delalloc_release_metadata(inode,
3176                                                         PAGE_CACHE_SIZE);
3177                                 ret = -EIO;
3178                                 goto out;
3179                         }
3180                 }
3181
3182                 page_start = page_offset(page);
3183                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3184
3185                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3186
3187                 set_page_extent_mapped(page);
3188
3189                 if (nr < cluster->nr &&
3190                     page_start + offset == cluster->boundary[nr]) {
3191                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3192                                         page_start, page_end,
3193                                         EXTENT_BOUNDARY, GFP_NOFS);
3194                         nr++;
3195                 }
3196
3197                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3198                 set_page_dirty(page);
3199
3200                 unlock_extent(&BTRFS_I(inode)->io_tree,
3201                               page_start, page_end);
3202                 unlock_page(page);
3203                 page_cache_release(page);
3204
3205                 index++;
3206                 balance_dirty_pages_ratelimited(inode->i_mapping);
3207                 btrfs_throttle(BTRFS_I(inode)->root);
3208         }
3209         WARN_ON(nr != cluster->nr);
3210 out:
3211         kfree(ra);
3212         return ret;
3213 }
3214
3215 static noinline_for_stack
3216 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3217                          struct file_extent_cluster *cluster)
3218 {
3219         int ret;
3220
3221         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3222                 ret = relocate_file_extent_cluster(inode, cluster);
3223                 if (ret)
3224                         return ret;
3225                 cluster->nr = 0;
3226         }
3227
3228         if (!cluster->nr)
3229                 cluster->start = extent_key->objectid;
3230         else
3231                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3232         cluster->end = extent_key->objectid + extent_key->offset - 1;
3233         cluster->boundary[cluster->nr] = extent_key->objectid;
3234         cluster->nr++;
3235
3236         if (cluster->nr >= MAX_EXTENTS) {
3237                 ret = relocate_file_extent_cluster(inode, cluster);
3238                 if (ret)
3239                         return ret;
3240                 cluster->nr = 0;
3241         }
3242         return 0;
3243 }
3244
3245 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3246 static int get_ref_objectid_v0(struct reloc_control *rc,
3247                                struct btrfs_path *path,
3248                                struct btrfs_key *extent_key,
3249                                u64 *ref_objectid, int *path_change)
3250 {
3251         struct btrfs_key key;
3252         struct extent_buffer *leaf;
3253         struct btrfs_extent_ref_v0 *ref0;
3254         int ret;
3255         int slot;
3256
3257         leaf = path->nodes[0];
3258         slot = path->slots[0];
3259         while (1) {
3260                 if (slot >= btrfs_header_nritems(leaf)) {
3261                         ret = btrfs_next_leaf(rc->extent_root, path);
3262                         if (ret < 0)
3263                                 return ret;
3264                         BUG_ON(ret > 0);
3265                         leaf = path->nodes[0];
3266                         slot = path->slots[0];
3267                         if (path_change)
3268                                 *path_change = 1;
3269                 }
3270                 btrfs_item_key_to_cpu(leaf, &key, slot);
3271                 if (key.objectid != extent_key->objectid)
3272                         return -ENOENT;
3273
3274                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3275                         slot++;
3276                         continue;
3277                 }
3278                 ref0 = btrfs_item_ptr(leaf, slot,
3279                                 struct btrfs_extent_ref_v0);
3280                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3281                 break;
3282         }
3283         return 0;
3284 }
3285 #endif
3286
3287 /*
3288  * helper to add a tree block to the list.
3289  * the major work is getting the generation and level of the block
3290  */
3291 static int add_tree_block(struct reloc_control *rc,
3292                           struct btrfs_key *extent_key,
3293                           struct btrfs_path *path,
3294                           struct rb_root *blocks)
3295 {
3296         struct extent_buffer *eb;
3297         struct btrfs_extent_item *ei;
3298         struct btrfs_tree_block_info *bi;
3299         struct tree_block *block;
3300         struct rb_node *rb_node;
3301         u32 item_size;
3302         int level = -1;
3303         u64 generation;
3304
3305         eb =  path->nodes[0];
3306         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3307
3308         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3309             item_size >= sizeof(*ei) + sizeof(*bi)) {
3310                 ei = btrfs_item_ptr(eb, path->slots[0],
3311                                 struct btrfs_extent_item);
3312                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3313                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3314                         level = btrfs_tree_block_level(eb, bi);
3315                 } else {
3316                         level = (int)extent_key->offset;
3317                 }
3318                 generation = btrfs_extent_generation(eb, ei);
3319         } else {
3320 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3321                 u64 ref_owner;
3322                 int ret;
3323
3324                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3325                 ret = get_ref_objectid_v0(rc, path, extent_key,
3326                                           &ref_owner, NULL);
3327                 if (ret < 0)
3328                         return ret;
3329                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3330                 level = (int)ref_owner;
3331                 /* FIXME: get real generation */
3332                 generation = 0;
3333 #else
3334                 BUG();
3335 #endif
3336         }
3337
3338         btrfs_release_path(path);
3339
3340         BUG_ON(level == -1);
3341
3342         block = kmalloc(sizeof(*block), GFP_NOFS);
3343         if (!block)
3344                 return -ENOMEM;
3345
3346         block->bytenr = extent_key->objectid;
3347         block->key.objectid = rc->extent_root->nodesize;
3348         block->key.offset = generation;
3349         block->level = level;
3350         block->key_ready = 0;
3351
3352         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3353         if (rb_node)
3354                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3355
3356         return 0;
3357 }
3358
3359 /*
3360  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3361  */
3362 static int __add_tree_block(struct reloc_control *rc,
3363                             u64 bytenr, u32 blocksize,
3364                             struct rb_root *blocks)
3365 {
3366         struct btrfs_path *path;
3367         struct btrfs_key key;
3368         int ret;
3369         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3370                                         SKINNY_METADATA);
3371
3372         if (tree_block_processed(bytenr, blocksize, rc))
3373                 return 0;
3374
3375         if (tree_search(blocks, bytenr))
3376                 return 0;
3377
3378         path = btrfs_alloc_path();
3379         if (!path)
3380                 return -ENOMEM;
3381 again:
3382         key.objectid = bytenr;
3383         if (skinny) {
3384                 key.type = BTRFS_METADATA_ITEM_KEY;
3385                 key.offset = (u64)-1;
3386         } else {
3387                 key.type = BTRFS_EXTENT_ITEM_KEY;
3388                 key.offset = blocksize;
3389         }
3390
3391         path->search_commit_root = 1;
3392         path->skip_locking = 1;
3393         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3394         if (ret < 0)
3395                 goto out;
3396
3397         if (ret > 0 && skinny) {
3398                 if (path->slots[0]) {
3399                         path->slots[0]--;
3400                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3401                                               path->slots[0]);
3402                         if (key.objectid == bytenr &&
3403                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3404                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3405                               key.offset == blocksize)))
3406                                 ret = 0;
3407                 }
3408
3409                 if (ret) {
3410                         skinny = false;
3411                         btrfs_release_path(path);
3412                         goto again;
3413                 }
3414         }
3415         BUG_ON(ret);
3416
3417         ret = add_tree_block(rc, &key, path, blocks);
3418 out:
3419         btrfs_free_path(path);
3420         return ret;
3421 }
3422
3423 /*
3424  * helper to check if the block use full backrefs for pointers in it
3425  */
3426 static int block_use_full_backref(struct reloc_control *rc,
3427                                   struct extent_buffer *eb)
3428 {
3429         u64 flags;
3430         int ret;
3431
3432         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3433             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3434                 return 1;
3435
3436         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3437                                        eb->start, btrfs_header_level(eb), 1,
3438                                        NULL, &flags);
3439         BUG_ON(ret);
3440
3441         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3442                 ret = 1;
3443         else
3444                 ret = 0;
3445         return ret;
3446 }
3447
3448 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3449                                     struct inode *inode, u64 ino)
3450 {
3451         struct btrfs_key key;
3452         struct btrfs_root *root = fs_info->tree_root;
3453         struct btrfs_trans_handle *trans;
3454         int ret = 0;
3455
3456         if (inode)
3457                 goto truncate;
3458
3459         key.objectid = ino;
3460         key.type = BTRFS_INODE_ITEM_KEY;
3461         key.offset = 0;
3462
3463         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3464         if (IS_ERR(inode) || is_bad_inode(inode)) {
3465                 if (!IS_ERR(inode))
3466                         iput(inode);
3467                 return -ENOENT;
3468         }
3469
3470 truncate:
3471         ret = btrfs_check_trunc_cache_free_space(root,
3472                                                  &fs_info->global_block_rsv);
3473         if (ret)
3474                 goto out;
3475
3476         trans = btrfs_join_transaction(root);
3477         if (IS_ERR(trans)) {
3478                 ret = PTR_ERR(trans);
3479                 goto out;
3480         }
3481
3482         ret = btrfs_truncate_free_space_cache(root, trans, inode);
3483
3484         btrfs_end_transaction(trans, root);
3485         btrfs_btree_balance_dirty(root);
3486 out:
3487         iput(inode);
3488         return ret;
3489 }
3490
3491 /*
3492  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3493  * this function scans fs tree to find blocks reference the data extent
3494  */
3495 static int find_data_references(struct reloc_control *rc,
3496                                 struct btrfs_key *extent_key,
3497                                 struct extent_buffer *leaf,
3498                                 struct btrfs_extent_data_ref *ref,
3499                                 struct rb_root *blocks)
3500 {
3501         struct btrfs_path *path;
3502         struct tree_block *block;
3503         struct btrfs_root *root;
3504         struct btrfs_file_extent_item *fi;
3505         struct rb_node *rb_node;
3506         struct btrfs_key key;
3507         u64 ref_root;
3508         u64 ref_objectid;
3509         u64 ref_offset;
3510         u32 ref_count;
3511         u32 nritems;
3512         int err = 0;
3513         int added = 0;
3514         int counted;
3515         int ret;
3516
3517         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3518         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3519         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3520         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3521
3522         /*
3523          * This is an extent belonging to the free space cache, lets just delete
3524          * it and redo the search.
3525          */
3526         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3527                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3528                                                NULL, ref_objectid);
3529                 if (ret != -ENOENT)
3530                         return ret;
3531                 ret = 0;
3532         }
3533
3534         path = btrfs_alloc_path();
3535         if (!path)
3536                 return -ENOMEM;
3537         path->reada = 1;
3538
3539         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3540         if (IS_ERR(root)) {
3541                 err = PTR_ERR(root);
3542                 goto out;
3543         }
3544
3545         key.objectid = ref_objectid;
3546         key.type = BTRFS_EXTENT_DATA_KEY;
3547         if (ref_offset > ((u64)-1 << 32))
3548                 key.offset = 0;
3549         else
3550                 key.offset = ref_offset;
3551
3552         path->search_commit_root = 1;
3553         path->skip_locking = 1;
3554         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3555         if (ret < 0) {
3556                 err = ret;
3557                 goto out;
3558         }
3559
3560         leaf = path->nodes[0];
3561         nritems = btrfs_header_nritems(leaf);
3562         /*
3563          * the references in tree blocks that use full backrefs
3564          * are not counted in
3565          */
3566         if (block_use_full_backref(rc, leaf))
3567                 counted = 0;
3568         else
3569                 counted = 1;
3570         rb_node = tree_search(blocks, leaf->start);
3571         if (rb_node) {
3572                 if (counted)
3573                         added = 1;
3574                 else
3575                         path->slots[0] = nritems;
3576         }
3577
3578         while (ref_count > 0) {
3579                 while (path->slots[0] >= nritems) {
3580                         ret = btrfs_next_leaf(root, path);
3581                         if (ret < 0) {
3582                                 err = ret;
3583                                 goto out;
3584                         }
3585                         if (WARN_ON(ret > 0))
3586                                 goto out;
3587
3588                         leaf = path->nodes[0];
3589                         nritems = btrfs_header_nritems(leaf);
3590                         added = 0;
3591
3592                         if (block_use_full_backref(rc, leaf))
3593                                 counted = 0;
3594                         else
3595                                 counted = 1;
3596                         rb_node = tree_search(blocks, leaf->start);
3597                         if (rb_node) {
3598                                 if (counted)
3599                                         added = 1;
3600                                 else
3601                                         path->slots[0] = nritems;
3602                         }
3603                 }
3604
3605                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3606                 if (WARN_ON(key.objectid != ref_objectid ||
3607                     key.type != BTRFS_EXTENT_DATA_KEY))
3608                         break;
3609
3610                 fi = btrfs_item_ptr(leaf, path->slots[0],
3611                                     struct btrfs_file_extent_item);
3612
3613                 if (btrfs_file_extent_type(leaf, fi) ==
3614                     BTRFS_FILE_EXTENT_INLINE)
3615                         goto next;
3616
3617                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3618                     extent_key->objectid)
3619                         goto next;
3620
3621                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3622                 if (key.offset != ref_offset)
3623                         goto next;
3624
3625                 if (counted)
3626                         ref_count--;
3627                 if (added)
3628                         goto next;
3629
3630                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3631                         block = kmalloc(sizeof(*block), GFP_NOFS);
3632                         if (!block) {
3633                                 err = -ENOMEM;
3634                                 break;
3635                         }
3636                         block->bytenr = leaf->start;
3637                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3638                         block->level = 0;
3639                         block->key_ready = 1;
3640                         rb_node = tree_insert(blocks, block->bytenr,
3641                                               &block->rb_node);
3642                         if (rb_node)
3643                                 backref_tree_panic(rb_node, -EEXIST,
3644                                                    block->bytenr);
3645                 }
3646                 if (counted)
3647                         added = 1;
3648                 else
3649                         path->slots[0] = nritems;
3650 next:
3651                 path->slots[0]++;
3652
3653         }
3654 out:
3655         btrfs_free_path(path);
3656         return err;
3657 }
3658
3659 /*
3660  * helper to find all tree blocks that reference a given data extent
3661  */
3662 static noinline_for_stack
3663 int add_data_references(struct reloc_control *rc,
3664                         struct btrfs_key *extent_key,
3665                         struct btrfs_path *path,
3666                         struct rb_root *blocks)
3667 {
3668         struct btrfs_key key;
3669         struct extent_buffer *eb;
3670         struct btrfs_extent_data_ref *dref;
3671         struct btrfs_extent_inline_ref *iref;
3672         unsigned long ptr;
3673         unsigned long end;
3674         u32 blocksize = rc->extent_root->nodesize;
3675         int ret = 0;
3676         int err = 0;
3677
3678         eb = path->nodes[0];
3679         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3680         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3681 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3682         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3683                 ptr = end;
3684         else
3685 #endif
3686                 ptr += sizeof(struct btrfs_extent_item);
3687
3688         while (ptr < end) {
3689                 iref = (struct btrfs_extent_inline_ref *)ptr;
3690                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3691                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3692                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3693                         ret = __add_tree_block(rc, key.offset, blocksize,
3694                                                blocks);
3695                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3696                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3697                         ret = find_data_references(rc, extent_key,
3698                                                    eb, dref, blocks);
3699                 } else {
3700                         BUG();
3701                 }
3702                 if (ret) {
3703                         err = ret;
3704                         goto out;
3705                 }
3706                 ptr += btrfs_extent_inline_ref_size(key.type);
3707         }
3708         WARN_ON(ptr > end);
3709
3710         while (1) {
3711                 cond_resched();
3712                 eb = path->nodes[0];
3713                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3714                         ret = btrfs_next_leaf(rc->extent_root, path);
3715                         if (ret < 0) {
3716                                 err = ret;
3717                                 break;
3718                         }
3719                         if (ret > 0)
3720                                 break;
3721                         eb = path->nodes[0];
3722                 }
3723
3724                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3725                 if (key.objectid != extent_key->objectid)
3726                         break;
3727
3728 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3729                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3730                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3731 #else
3732                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3733                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3734 #endif
3735                         ret = __add_tree_block(rc, key.offset, blocksize,
3736                                                blocks);
3737                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3738                         dref = btrfs_item_ptr(eb, path->slots[0],
3739                                               struct btrfs_extent_data_ref);
3740                         ret = find_data_references(rc, extent_key,
3741                                                    eb, dref, blocks);
3742                 } else {
3743                         ret = 0;
3744                 }
3745                 if (ret) {
3746                         err = ret;
3747                         break;
3748                 }
3749                 path->slots[0]++;
3750         }
3751 out:
3752         btrfs_release_path(path);
3753         if (err)
3754                 free_block_list(blocks);
3755         return err;
3756 }
3757
3758 /*
3759  * helper to find next unprocessed extent
3760  */
3761 static noinline_for_stack
3762 int find_next_extent(struct btrfs_trans_handle *trans,
3763                      struct reloc_control *rc, struct btrfs_path *path,
3764                      struct btrfs_key *extent_key)
3765 {
3766         struct btrfs_key key;
3767         struct extent_buffer *leaf;
3768         u64 start, end, last;
3769         int ret;
3770
3771         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3772         while (1) {
3773                 cond_resched();
3774                 if (rc->search_start >= last) {
3775                         ret = 1;
3776                         break;
3777                 }
3778
3779                 key.objectid = rc->search_start;
3780                 key.type = BTRFS_EXTENT_ITEM_KEY;
3781                 key.offset = 0;
3782
3783                 path->search_commit_root = 1;
3784                 path->skip_locking = 1;
3785                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3786                                         0, 0);
3787                 if (ret < 0)
3788                         break;
3789 next:
3790                 leaf = path->nodes[0];
3791                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3792                         ret = btrfs_next_leaf(rc->extent_root, path);
3793                         if (ret != 0)
3794                                 break;
3795                         leaf = path->nodes[0];
3796                 }
3797
3798                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3799                 if (key.objectid >= last) {
3800                         ret = 1;
3801                         break;
3802                 }
3803
3804                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3805                     key.type != BTRFS_METADATA_ITEM_KEY) {
3806                         path->slots[0]++;
3807                         goto next;
3808                 }
3809
3810                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3811                     key.objectid + key.offset <= rc->search_start) {
3812                         path->slots[0]++;
3813                         goto next;
3814                 }
3815
3816                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3817                     key.objectid + rc->extent_root->nodesize <=
3818                     rc->search_start) {
3819                         path->slots[0]++;
3820                         goto next;
3821                 }
3822
3823                 ret = find_first_extent_bit(&rc->processed_blocks,
3824                                             key.objectid, &start, &end,
3825                                             EXTENT_DIRTY, NULL);
3826
3827                 if (ret == 0 && start <= key.objectid) {
3828                         btrfs_release_path(path);
3829                         rc->search_start = end + 1;
3830                 } else {
3831                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3832                                 rc->search_start = key.objectid + key.offset;
3833                         else
3834                                 rc->search_start = key.objectid +
3835                                         rc->extent_root->nodesize;
3836                         memcpy(extent_key, &key, sizeof(key));
3837                         return 0;
3838                 }
3839         }
3840         btrfs_release_path(path);
3841         return ret;
3842 }
3843
3844 static void set_reloc_control(struct reloc_control *rc)
3845 {
3846         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3847
3848         mutex_lock(&fs_info->reloc_mutex);
3849         fs_info->reloc_ctl = rc;
3850         mutex_unlock(&fs_info->reloc_mutex);
3851 }
3852
3853 static void unset_reloc_control(struct reloc_control *rc)
3854 {
3855         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3856
3857         mutex_lock(&fs_info->reloc_mutex);
3858         fs_info->reloc_ctl = NULL;
3859         mutex_unlock(&fs_info->reloc_mutex);
3860 }
3861
3862 static int check_extent_flags(u64 flags)
3863 {
3864         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3865             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3866                 return 1;
3867         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3868             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3869                 return 1;
3870         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3871             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3872                 return 1;
3873         return 0;
3874 }
3875
3876 static noinline_for_stack
3877 int prepare_to_relocate(struct reloc_control *rc)
3878 {
3879         struct btrfs_trans_handle *trans;
3880
3881         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3882                                               BTRFS_BLOCK_RSV_TEMP);
3883         if (!rc->block_rsv)
3884                 return -ENOMEM;
3885
3886         memset(&rc->cluster, 0, sizeof(rc->cluster));
3887         rc->search_start = rc->block_group->key.objectid;
3888         rc->extents_found = 0;
3889         rc->nodes_relocated = 0;
3890         rc->merging_rsv_size = 0;
3891         rc->reserved_bytes = 0;
3892         rc->block_rsv->size = rc->extent_root->nodesize *
3893                               RELOCATION_RESERVED_NODES;
3894
3895         rc->create_reloc_tree = 1;
3896         set_reloc_control(rc);
3897
3898         trans = btrfs_join_transaction(rc->extent_root);
3899         if (IS_ERR(trans)) {
3900                 unset_reloc_control(rc);
3901                 /*
3902                  * extent tree is not a ref_cow tree and has no reloc_root to
3903                  * cleanup.  And callers are responsible to free the above
3904                  * block rsv.
3905                  */
3906                 return PTR_ERR(trans);
3907         }
3908         btrfs_commit_transaction(trans, rc->extent_root);
3909         return 0;
3910 }
3911
3912 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3913 {
3914         struct rb_root blocks = RB_ROOT;
3915         struct btrfs_key key;
3916         struct btrfs_trans_handle *trans = NULL;
3917         struct btrfs_path *path;
3918         struct btrfs_extent_item *ei;
3919         u64 flags;
3920         u32 item_size;
3921         int ret;
3922         int err = 0;
3923         int progress = 0;
3924
3925         path = btrfs_alloc_path();
3926         if (!path)
3927                 return -ENOMEM;
3928         path->reada = 1;
3929
3930         ret = prepare_to_relocate(rc);
3931         if (ret) {
3932                 err = ret;
3933                 goto out_free;
3934         }
3935
3936         while (1) {
3937                 rc->reserved_bytes = 0;
3938                 ret = btrfs_block_rsv_refill(rc->extent_root,
3939                                         rc->block_rsv, rc->block_rsv->size,
3940                                         BTRFS_RESERVE_FLUSH_ALL);
3941                 if (ret) {
3942                         err = ret;
3943                         break;
3944                 }
3945                 progress++;
3946                 trans = btrfs_start_transaction(rc->extent_root, 0);
3947                 if (IS_ERR(trans)) {
3948                         err = PTR_ERR(trans);
3949                         trans = NULL;
3950                         break;
3951                 }
3952 restart:
3953                 if (update_backref_cache(trans, &rc->backref_cache)) {
3954                         btrfs_end_transaction(trans, rc->extent_root);
3955                         continue;
3956                 }
3957
3958                 ret = find_next_extent(trans, rc, path, &key);
3959                 if (ret < 0)
3960                         err = ret;
3961                 if (ret != 0)
3962                         break;
3963
3964                 rc->extents_found++;
3965
3966                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3967                                     struct btrfs_extent_item);
3968                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3969                 if (item_size >= sizeof(*ei)) {
3970                         flags = btrfs_extent_flags(path->nodes[0], ei);
3971                         ret = check_extent_flags(flags);
3972                         BUG_ON(ret);
3973
3974                 } else {
3975 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3976                         u64 ref_owner;
3977                         int path_change = 0;
3978
3979                         BUG_ON(item_size !=
3980                                sizeof(struct btrfs_extent_item_v0));
3981                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3982                                                   &path_change);
3983                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3984                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3985                         else
3986                                 flags = BTRFS_EXTENT_FLAG_DATA;
3987
3988                         if (path_change) {
3989                                 btrfs_release_path(path);
3990
3991                                 path->search_commit_root = 1;
3992                                 path->skip_locking = 1;
3993                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3994                                                         &key, path, 0, 0);
3995                                 if (ret < 0) {
3996                                         err = ret;
3997                                         break;
3998                                 }
3999                                 BUG_ON(ret > 0);
4000                         }
4001 #else
4002                         BUG();
4003 #endif
4004                 }
4005
4006                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4007                         ret = add_tree_block(rc, &key, path, &blocks);
4008                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4009                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4010                         ret = add_data_references(rc, &key, path, &blocks);
4011                 } else {
4012                         btrfs_release_path(path);
4013                         ret = 0;
4014                 }
4015                 if (ret < 0) {
4016                         err = ret;
4017                         break;
4018                 }
4019
4020                 if (!RB_EMPTY_ROOT(&blocks)) {
4021                         ret = relocate_tree_blocks(trans, rc, &blocks);
4022                         if (ret < 0) {
4023                                 /*
4024                                  * if we fail to relocate tree blocks, force to update
4025                                  * backref cache when committing transaction.
4026                                  */
4027                                 rc->backref_cache.last_trans = trans->transid - 1;
4028
4029                                 if (ret != -EAGAIN) {
4030                                         err = ret;
4031                                         break;
4032                                 }
4033                                 rc->extents_found--;
4034                                 rc->search_start = key.objectid;
4035                         }
4036                 }
4037
4038                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4039                 btrfs_btree_balance_dirty(rc->extent_root);
4040                 trans = NULL;
4041
4042                 if (rc->stage == MOVE_DATA_EXTENTS &&
4043                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4044                         rc->found_file_extent = 1;
4045                         ret = relocate_data_extent(rc->data_inode,
4046                                                    &key, &rc->cluster);
4047                         if (ret < 0) {
4048                                 err = ret;
4049                                 break;
4050                         }
4051                 }
4052         }
4053         if (trans && progress && err == -ENOSPC) {
4054                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4055                                               rc->block_group->flags);
4056                 if (ret == 0) {
4057                         err = 0;
4058                         progress = 0;
4059                         goto restart;
4060                 }
4061         }
4062
4063         btrfs_release_path(path);
4064         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4065                           GFP_NOFS);
4066
4067         if (trans) {
4068                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4069                 btrfs_btree_balance_dirty(rc->extent_root);
4070         }
4071
4072         if (!err) {
4073                 ret = relocate_file_extent_cluster(rc->data_inode,
4074                                                    &rc->cluster);
4075                 if (ret < 0)
4076                         err = ret;
4077         }
4078
4079         rc->create_reloc_tree = 0;
4080         set_reloc_control(rc);
4081
4082         backref_cache_cleanup(&rc->backref_cache);
4083         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4084
4085         err = prepare_to_merge(rc, err);
4086
4087         merge_reloc_roots(rc);
4088
4089         rc->merge_reloc_tree = 0;
4090         unset_reloc_control(rc);
4091         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4092
4093         /* get rid of pinned extents */
4094         trans = btrfs_join_transaction(rc->extent_root);
4095         if (IS_ERR(trans))
4096                 err = PTR_ERR(trans);
4097         else
4098                 btrfs_commit_transaction(trans, rc->extent_root);
4099 out_free:
4100         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4101         btrfs_free_path(path);
4102         return err;
4103 }
4104
4105 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4106                                  struct btrfs_root *root, u64 objectid)
4107 {
4108         struct btrfs_path *path;
4109         struct btrfs_inode_item *item;
4110         struct extent_buffer *leaf;
4111         int ret;
4112
4113         path = btrfs_alloc_path();
4114         if (!path)
4115                 return -ENOMEM;
4116
4117         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4118         if (ret)
4119                 goto out;
4120
4121         leaf = path->nodes[0];
4122         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4123         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4124         btrfs_set_inode_generation(leaf, item, 1);
4125         btrfs_set_inode_size(leaf, item, 0);
4126         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4127         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4128                                           BTRFS_INODE_PREALLOC);
4129         btrfs_mark_buffer_dirty(leaf);
4130 out:
4131         btrfs_free_path(path);
4132         return ret;
4133 }
4134
4135 /*
4136  * helper to create inode for data relocation.
4137  * the inode is in data relocation tree and its link count is 0
4138  */
4139 static noinline_for_stack
4140 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4141                                  struct btrfs_block_group_cache *group)
4142 {
4143         struct inode *inode = NULL;
4144         struct btrfs_trans_handle *trans;
4145         struct btrfs_root *root;
4146         struct btrfs_key key;
4147         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
4148         int err = 0;
4149
4150         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4151         if (IS_ERR(root))
4152                 return ERR_CAST(root);
4153
4154         trans = btrfs_start_transaction(root, 6);
4155         if (IS_ERR(trans))
4156                 return ERR_CAST(trans);
4157
4158         err = btrfs_find_free_objectid(root, &objectid);
4159         if (err)
4160                 goto out;
4161
4162         err = __insert_orphan_inode(trans, root, objectid);
4163         BUG_ON(err);
4164
4165         key.objectid = objectid;
4166         key.type = BTRFS_INODE_ITEM_KEY;
4167         key.offset = 0;
4168         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4169         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4170         BTRFS_I(inode)->index_cnt = group->key.objectid;
4171
4172         err = btrfs_orphan_add(trans, inode);
4173 out:
4174         btrfs_end_transaction(trans, root);
4175         btrfs_btree_balance_dirty(root);
4176         if (err) {
4177                 if (inode)
4178                         iput(inode);
4179                 inode = ERR_PTR(err);
4180         }
4181         return inode;
4182 }
4183
4184 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4185 {
4186         struct reloc_control *rc;
4187
4188         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4189         if (!rc)
4190                 return NULL;
4191
4192         INIT_LIST_HEAD(&rc->reloc_roots);
4193         backref_cache_init(&rc->backref_cache);
4194         mapping_tree_init(&rc->reloc_root_tree);
4195         extent_io_tree_init(&rc->processed_blocks,
4196                             fs_info->btree_inode->i_mapping);
4197         return rc;
4198 }
4199
4200 /*
4201  * function to relocate all extents in a block group.
4202  */
4203 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4204 {
4205         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4206         struct reloc_control *rc;
4207         struct inode *inode;
4208         struct btrfs_path *path;
4209         int ret;
4210         int rw = 0;
4211         int err = 0;
4212
4213         rc = alloc_reloc_control(fs_info);
4214         if (!rc)
4215                 return -ENOMEM;
4216
4217         rc->extent_root = extent_root;
4218
4219         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4220         BUG_ON(!rc->block_group);
4221
4222         if (!rc->block_group->ro) {
4223                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4224                 if (ret) {
4225                         err = ret;
4226                         goto out;
4227                 }
4228                 rw = 1;
4229         }
4230
4231         path = btrfs_alloc_path();
4232         if (!path) {
4233                 err = -ENOMEM;
4234                 goto out;
4235         }
4236
4237         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4238                                         path);
4239         btrfs_free_path(path);
4240
4241         if (!IS_ERR(inode))
4242                 ret = delete_block_group_cache(fs_info, inode, 0);
4243         else
4244                 ret = PTR_ERR(inode);
4245
4246         if (ret && ret != -ENOENT) {
4247                 err = ret;
4248                 goto out;
4249         }
4250
4251         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4252         if (IS_ERR(rc->data_inode)) {
4253                 err = PTR_ERR(rc->data_inode);
4254                 rc->data_inode = NULL;
4255                 goto out;
4256         }
4257
4258         btrfs_info(extent_root->fs_info, "relocating block group %llu flags %llu",
4259                rc->block_group->key.objectid, rc->block_group->flags);
4260
4261         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
4262         if (ret < 0) {
4263                 err = ret;
4264                 goto out;
4265         }
4266         btrfs_wait_ordered_roots(fs_info, -1);
4267
4268         while (1) {
4269                 mutex_lock(&fs_info->cleaner_mutex);
4270                 ret = relocate_block_group(rc);
4271                 mutex_unlock(&fs_info->cleaner_mutex);
4272                 if (ret < 0) {
4273                         err = ret;
4274                         goto out;
4275                 }
4276
4277                 if (rc->extents_found == 0)
4278                         break;
4279
4280                 btrfs_info(extent_root->fs_info, "found %llu extents",
4281                         rc->extents_found);
4282
4283                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4284                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4285                                                        (u64)-1);
4286                         if (ret) {
4287                                 err = ret;
4288                                 goto out;
4289                         }
4290                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4291                                                  0, -1);
4292                         rc->stage = UPDATE_DATA_PTRS;
4293                 }
4294         }
4295
4296         WARN_ON(rc->block_group->pinned > 0);
4297         WARN_ON(rc->block_group->reserved > 0);
4298         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4299 out:
4300         if (err && rw)
4301                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4302         iput(rc->data_inode);
4303         btrfs_put_block_group(rc->block_group);
4304         kfree(rc);
4305         return err;
4306 }
4307
4308 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4309 {
4310         struct btrfs_trans_handle *trans;
4311         int ret, err;
4312
4313         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4314         if (IS_ERR(trans))
4315                 return PTR_ERR(trans);
4316
4317         memset(&root->root_item.drop_progress, 0,
4318                 sizeof(root->root_item.drop_progress));
4319         root->root_item.drop_level = 0;
4320         btrfs_set_root_refs(&root->root_item, 0);
4321         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4322                                 &root->root_key, &root->root_item);
4323
4324         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4325         if (err)
4326                 return err;
4327         return ret;
4328 }
4329
4330 /*
4331  * recover relocation interrupted by system crash.
4332  *
4333  * this function resumes merging reloc trees with corresponding fs trees.
4334  * this is important for keeping the sharing of tree blocks
4335  */
4336 int btrfs_recover_relocation(struct btrfs_root *root)
4337 {
4338         LIST_HEAD(reloc_roots);
4339         struct btrfs_key key;
4340         struct btrfs_root *fs_root;
4341         struct btrfs_root *reloc_root;
4342         struct btrfs_path *path;
4343         struct extent_buffer *leaf;
4344         struct reloc_control *rc = NULL;
4345         struct btrfs_trans_handle *trans;
4346         int ret;
4347         int err = 0;
4348
4349         path = btrfs_alloc_path();
4350         if (!path)
4351                 return -ENOMEM;
4352         path->reada = -1;
4353
4354         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4355         key.type = BTRFS_ROOT_ITEM_KEY;
4356         key.offset = (u64)-1;
4357
4358         while (1) {
4359                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4360                                         path, 0, 0);
4361                 if (ret < 0) {
4362                         err = ret;
4363                         goto out;
4364                 }
4365                 if (ret > 0) {
4366                         if (path->slots[0] == 0)
4367                                 break;
4368                         path->slots[0]--;
4369                 }
4370                 leaf = path->nodes[0];
4371                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4372                 btrfs_release_path(path);
4373
4374                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4375                     key.type != BTRFS_ROOT_ITEM_KEY)
4376                         break;
4377
4378                 reloc_root = btrfs_read_fs_root(root, &key);
4379                 if (IS_ERR(reloc_root)) {
4380                         err = PTR_ERR(reloc_root);
4381                         goto out;
4382                 }
4383
4384                 list_add(&reloc_root->root_list, &reloc_roots);
4385
4386                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4387                         fs_root = read_fs_root(root->fs_info,
4388                                                reloc_root->root_key.offset);
4389                         if (IS_ERR(fs_root)) {
4390                                 ret = PTR_ERR(fs_root);
4391                                 if (ret != -ENOENT) {
4392                                         err = ret;
4393                                         goto out;
4394                                 }
4395                                 ret = mark_garbage_root(reloc_root);
4396                                 if (ret < 0) {
4397                                         err = ret;
4398                                         goto out;
4399                                 }
4400                         }
4401                 }
4402
4403                 if (key.offset == 0)
4404                         break;
4405
4406                 key.offset--;
4407         }
4408         btrfs_release_path(path);
4409
4410         if (list_empty(&reloc_roots))
4411                 goto out;
4412
4413         rc = alloc_reloc_control(root->fs_info);
4414         if (!rc) {
4415                 err = -ENOMEM;
4416                 goto out;
4417         }
4418
4419         rc->extent_root = root->fs_info->extent_root;
4420
4421         set_reloc_control(rc);
4422
4423         trans = btrfs_join_transaction(rc->extent_root);
4424         if (IS_ERR(trans)) {
4425                 unset_reloc_control(rc);
4426                 err = PTR_ERR(trans);
4427                 goto out_free;
4428         }
4429
4430         rc->merge_reloc_tree = 1;
4431
4432         while (!list_empty(&reloc_roots)) {
4433                 reloc_root = list_entry(reloc_roots.next,
4434                                         struct btrfs_root, root_list);
4435                 list_del(&reloc_root->root_list);
4436
4437                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4438                         list_add_tail(&reloc_root->root_list,
4439                                       &rc->reloc_roots);
4440                         continue;
4441                 }
4442
4443                 fs_root = read_fs_root(root->fs_info,
4444                                        reloc_root->root_key.offset);
4445                 if (IS_ERR(fs_root)) {
4446                         err = PTR_ERR(fs_root);
4447                         goto out_free;
4448                 }
4449
4450                 err = __add_reloc_root(reloc_root);
4451                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4452                 fs_root->reloc_root = reloc_root;
4453         }
4454
4455         err = btrfs_commit_transaction(trans, rc->extent_root);
4456         if (err)
4457                 goto out_free;
4458
4459         merge_reloc_roots(rc);
4460
4461         unset_reloc_control(rc);
4462
4463         trans = btrfs_join_transaction(rc->extent_root);
4464         if (IS_ERR(trans))
4465                 err = PTR_ERR(trans);
4466         else
4467                 err = btrfs_commit_transaction(trans, rc->extent_root);
4468 out_free:
4469         kfree(rc);
4470 out:
4471         if (!list_empty(&reloc_roots))
4472                 free_reloc_roots(&reloc_roots);
4473
4474         btrfs_free_path(path);
4475
4476         if (err == 0) {
4477                 /* cleanup orphan inode in data relocation tree */
4478                 fs_root = read_fs_root(root->fs_info,
4479                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4480                 if (IS_ERR(fs_root))
4481                         err = PTR_ERR(fs_root);
4482                 else
4483                         err = btrfs_orphan_cleanup(fs_root);
4484         }
4485         return err;
4486 }
4487
4488 /*
4489  * helper to add ordered checksum for data relocation.
4490  *
4491  * cloning checksum properly handles the nodatasum extents.
4492  * it also saves CPU time to re-calculate the checksum.
4493  */
4494 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4495 {
4496         struct btrfs_ordered_sum *sums;
4497         struct btrfs_ordered_extent *ordered;
4498         struct btrfs_root *root = BTRFS_I(inode)->root;
4499         int ret;
4500         u64 disk_bytenr;
4501         u64 new_bytenr;
4502         LIST_HEAD(list);
4503
4504         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4505         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4506
4507         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4508         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4509                                        disk_bytenr + len - 1, &list, 0);
4510         if (ret)
4511                 goto out;
4512
4513         while (!list_empty(&list)) {
4514                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4515                 list_del_init(&sums->list);
4516
4517                 /*
4518                  * We need to offset the new_bytenr based on where the csum is.
4519                  * We need to do this because we will read in entire prealloc
4520                  * extents but we may have written to say the middle of the
4521                  * prealloc extent, so we need to make sure the csum goes with
4522                  * the right disk offset.
4523                  *
4524                  * We can do this because the data reloc inode refers strictly
4525                  * to the on disk bytes, so we don't have to worry about
4526                  * disk_len vs real len like with real inodes since it's all
4527                  * disk length.
4528                  */
4529                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4530                 sums->bytenr = new_bytenr;
4531
4532                 btrfs_add_ordered_sum(inode, ordered, sums);
4533         }
4534 out:
4535         btrfs_put_ordered_extent(ordered);
4536         return ret;
4537 }
4538
4539 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4540                           struct btrfs_root *root, struct extent_buffer *buf,
4541                           struct extent_buffer *cow)
4542 {
4543         struct reloc_control *rc;
4544         struct backref_node *node;
4545         int first_cow = 0;
4546         int level;
4547         int ret = 0;
4548
4549         rc = root->fs_info->reloc_ctl;
4550         if (!rc)
4551                 return 0;
4552
4553         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4554                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4555
4556         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4557                 if (buf == root->node)
4558                         __update_reloc_root(root, cow->start);
4559         }
4560
4561         level = btrfs_header_level(buf);
4562         if (btrfs_header_generation(buf) <=
4563             btrfs_root_last_snapshot(&root->root_item))
4564                 first_cow = 1;
4565
4566         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4567             rc->create_reloc_tree) {
4568                 WARN_ON(!first_cow && level == 0);
4569
4570                 node = rc->backref_cache.path[level];
4571                 BUG_ON(node->bytenr != buf->start &&
4572                        node->new_bytenr != buf->start);
4573
4574                 drop_node_buffer(node);
4575                 extent_buffer_get(cow);
4576                 node->eb = cow;
4577                 node->new_bytenr = cow->start;
4578
4579                 if (!node->pending) {
4580                         list_move_tail(&node->list,
4581                                        &rc->backref_cache.pending[level]);
4582                         node->pending = 1;
4583                 }
4584
4585                 if (first_cow)
4586                         __mark_block_processed(rc, node);
4587
4588                 if (first_cow && level > 0)
4589                         rc->nodes_relocated += buf->len;
4590         }
4591
4592         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4593                 ret = replace_file_extents(trans, rc, root, cow);
4594         return ret;
4595 }
4596
4597 /*
4598  * called before creating snapshot. it calculates metadata reservation
4599  * requried for relocating tree blocks in the snapshot
4600  */
4601 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4602                               struct btrfs_pending_snapshot *pending,
4603                               u64 *bytes_to_reserve)
4604 {
4605         struct btrfs_root *root;
4606         struct reloc_control *rc;
4607
4608         root = pending->root;
4609         if (!root->reloc_root)
4610                 return;
4611
4612         rc = root->fs_info->reloc_ctl;
4613         if (!rc->merge_reloc_tree)
4614                 return;
4615
4616         root = root->reloc_root;
4617         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4618         /*
4619          * relocation is in the stage of merging trees. the space
4620          * used by merging a reloc tree is twice the size of
4621          * relocated tree nodes in the worst case. half for cowing
4622          * the reloc tree, half for cowing the fs tree. the space
4623          * used by cowing the reloc tree will be freed after the
4624          * tree is dropped. if we create snapshot, cowing the fs
4625          * tree may use more space than it frees. so we need
4626          * reserve extra space.
4627          */
4628         *bytes_to_reserve += rc->nodes_relocated;
4629 }
4630
4631 /*
4632  * called after snapshot is created. migrate block reservation
4633  * and create reloc root for the newly created snapshot
4634  */
4635 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4636                                struct btrfs_pending_snapshot *pending)
4637 {
4638         struct btrfs_root *root = pending->root;
4639         struct btrfs_root *reloc_root;
4640         struct btrfs_root *new_root;
4641         struct reloc_control *rc;
4642         int ret;
4643
4644         if (!root->reloc_root)
4645                 return 0;
4646
4647         rc = root->fs_info->reloc_ctl;
4648         rc->merging_rsv_size += rc->nodes_relocated;
4649
4650         if (rc->merge_reloc_tree) {
4651                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4652                                               rc->block_rsv,
4653                                               rc->nodes_relocated);
4654                 if (ret)
4655                         return ret;
4656         }
4657
4658         new_root = pending->snap;
4659         reloc_root = create_reloc_root(trans, root->reloc_root,
4660                                        new_root->root_key.objectid);
4661         if (IS_ERR(reloc_root))
4662                 return PTR_ERR(reloc_root);
4663
4664         ret = __add_reloc_root(reloc_root);
4665         BUG_ON(ret < 0);
4666         new_root->reloc_root = reloc_root;
4667
4668         if (rc->create_reloc_tree)
4669                 ret = clone_backref_node(trans, rc, root, reloc_root);
4670         return ret;
4671 }