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                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
 925                     cur->bytenr) {
 926                         btrfs_err(root->fs_info,
 927         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
 928                                   cur->bytenr, level - 1, root->objectid,
 929                                   node_key->objectid, node_key->type,
 930                                   node_key->offset);
 931                         err = -ENOENT;
 932                         goto out;
 933                 }
 934                 lower = cur;
 935                 need_check = true;
 936                 for (; level < BTRFS_MAX_LEVEL; level++) {
 937                         if (!path2->nodes[level]) {
 938                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
 939                                        lower->bytenr);
 940                                 if (should_ignore_root(root))
 941                                         list_add(&lower->list, &useless);
 942                                 else
 943                                         lower->root = root;
 944                                 break;
 945                         }
 946
 947                         edge = alloc_backref_edge(cache);
 948                         if (!edge) {
 949                                 err = -ENOMEM;
 950                                 goto out;
 951                         }
 952
 953                         eb = path2->nodes[level];
 954                         rb_node = tree_search(&cache->rb_root, eb->start);
 955                         if (!rb_node) {
 956                                 upper = alloc_backref_node(cache);
 957                                 if (!upper) {
 958                                         free_backref_edge(cache, edge);
 959                                         err = -ENOMEM;
 960                                         goto out;
 961                                 }
 962                                 upper->bytenr = eb->start;
 963                                 upper->owner = btrfs_header_owner(eb);
 964                                 upper->level = lower->level + 1;
 965                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 966                                               &root->state))
 967                                         upper->cowonly = 1;
 968
 969                                 /*
 970                                  * if we know the block isn't shared
 971                                  * we can void checking its backrefs.
 972                                  */
 973                                 if (btrfs_block_can_be_shared(root, eb))
 974                                         upper->checked = 0;
 975                                 else
 976                                         upper->checked = 1;
 977
 978                                 /*
 979                                  * add the block to pending list if we
 980                                  * need check its backrefs, we only do this once
 981                                  * while walking up a tree as we will catch
 982                                  * anything else later on.
 983                                  */
 984                                 if (!upper->checked && need_check) {
 985                                         need_check = false;
 986                                         list_add_tail(&edge->list[UPPER],
 987                                                       &list);
 988                                 } else {
 989                                         if (upper->checked)
 990                                                 need_check = true;
 991                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 992                                 }
 993                         } else {
 994                                 upper = rb_entry(rb_node, struct backref_node,
 995                                                  rb_node);
 996                                 ASSERT(upper->checked);
 997                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 998                                 if (!upper->owner)
 999                                         upper->owner = btrfs_header_owner(eb);
1000                         }
1001                         list_add_tail(&edge->list[LOWER], &lower->upper);
1002                         edge->node[LOWER] = lower;
1003                         edge->node[UPPER] = upper;
1004
1005                         if (rb_node)
1006                                 break;
1007                         lower = upper;
1008                         upper = NULL;
1009                 }
1010                 btrfs_release_path(path2);
1011 next:
1012                 if (ptr < end) {
1013                         ptr += btrfs_extent_inline_ref_size(key.type);
1014                         if (ptr >= end) {
1015                                 WARN_ON(ptr > end);
1016                                 ptr = 0;
1017                                 end = 0;
1018                         }
1019                 }
1020                 if (ptr >= end)
1021                         path1->slots[0]++;
1022         }
1023         btrfs_release_path(path1);
1024
1025         cur->checked = 1;
1026         WARN_ON(exist);
1027
1028         /* the pending list isn't empty, take the first block to process */
1029         if (!list_empty(&list)) {
1030                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1031                 list_del_init(&edge->list[UPPER]);
1032                 cur = edge->node[UPPER];
1033                 goto again;
1034         }
1035
1036         /*
1037          * everything goes well, connect backref nodes and insert backref nodes
1038          * into the cache.
1039          */
1040         ASSERT(node->checked);
1041         cowonly = node->cowonly;
1042         if (!cowonly) {
1043                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1044                                       &node->rb_node);
1045                 if (rb_node)
1046                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1047                 list_add_tail(&node->lower, &cache->leaves);
1048         }
1049
1050         list_for_each_entry(edge, &node->upper, list[LOWER])
1051                 list_add_tail(&edge->list[UPPER], &list);
1052
1053         while (!list_empty(&list)) {
1054                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1055                 list_del_init(&edge->list[UPPER]);
1056                 upper = edge->node[UPPER];
1057                 if (upper->detached) {
1058                         list_del(&edge->list[LOWER]);
1059                         lower = edge->node[LOWER];
1060                         free_backref_edge(cache, edge);
1061                         if (list_empty(&lower->upper))
1062                                 list_add(&lower->list, &useless);
1063                         continue;
1064                 }
1065
1066                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1067                         if (upper->lowest) {
1068                                 list_del_init(&upper->lower);
1069                                 upper->lowest = 0;
1070                         }
1071
1072                         list_add_tail(&edge->list[UPPER], &upper->lower);
1073                         continue;
1074                 }
1075
1076                 if (!upper->checked) {
1077                         /*
1078                          * Still want to blow up for developers since this is a
1079                          * logic bug.
1080                          */
1081                         ASSERT(0);
1082                         err = -EINVAL;
1083                         goto out;
1084                 }
1085                 if (cowonly != upper->cowonly) {
1086                         ASSERT(0);
1087                         err = -EINVAL;
1088                         goto out;
1089                 }
1090
1091                 if (!cowonly) {
1092                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1093                                               &upper->rb_node);
1094                         if (rb_node)
1095                                 backref_tree_panic(rb_node, -EEXIST,
1096                                                    upper->bytenr);
1097                 }
1098
1099                 list_add_tail(&edge->list[UPPER], &upper->lower);
1100
1101                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1102                         list_add_tail(&edge->list[UPPER], &list);
1103         }
1104         /*
1105          * process useless backref nodes. backref nodes for tree leaves
1106          * are deleted from the cache. backref nodes for upper level
1107          * tree blocks are left in the cache to avoid unnecessary backref
1108          * lookup.
1109          */
1110         while (!list_empty(&useless)) {
1111                 upper = list_entry(useless.next, struct backref_node, list);
1112                 list_del_init(&upper->list);
1113                 ASSERT(list_empty(&upper->upper));
1114                 if (upper == node)
1115                         node = NULL;
1116                 if (upper->lowest) {
1117                         list_del_init(&upper->lower);
1118                         upper->lowest = 0;
1119                 }
1120                 while (!list_empty(&upper->lower)) {
1121                         edge = list_entry(upper->lower.next,
1122                                           struct backref_edge, list[UPPER]);
1123                         list_del(&edge->list[UPPER]);
1124                         list_del(&edge->list[LOWER]);
1125                         lower = edge->node[LOWER];
1126                         free_backref_edge(cache, edge);
1127
1128                         if (list_empty(&lower->upper))
1129                                 list_add(&lower->list, &useless);
1130                 }
1131                 __mark_block_processed(rc, upper);
1132                 if (upper->level > 0) {
1133                         list_add(&upper->list, &cache->detached);
1134                         upper->detached = 1;
1135                 } else {
1136                         rb_erase(&upper->rb_node, &cache->rb_root);
1137                         free_backref_node(cache, upper);
1138                 }
1139         }
1140 out:
1141         btrfs_free_path(path1);
1142         btrfs_free_path(path2);
1143         if (err) {
1144                 while (!list_empty(&useless)) {
1145                         lower = list_entry(useless.next,
1146                                            struct backref_node, list);
1147                         list_del_init(&lower->list);
1148                 }
1149                 while (!list_empty(&list)) {
1150                         edge = list_first_entry(&list, struct backref_edge,
1151                                                 list[UPPER]);
1152                         list_del(&edge->list[UPPER]);
1153                         list_del(&edge->list[LOWER]);
1154                         lower = edge->node[LOWER];
1155                         upper = edge->node[UPPER];
1156                         free_backref_edge(cache, edge);
1157
1158                         /*
1159                          * Lower is no longer linked to any upper backref nodes
1160                          * and isn't in the cache, we can free it ourselves.
1161                          */
1162                         if (list_empty(&lower->upper) &&
1163                             RB_EMPTY_NODE(&lower->rb_node))
1164                                 list_add(&lower->list, &useless);
1165
1166                         if (!RB_EMPTY_NODE(&upper->rb_node))
1167                                 continue;
1168
1169                         /* Add this guy's upper edges to the list to proces */
1170                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1171                                 list_add_tail(&edge->list[UPPER], &list);
1172                         if (list_empty(&upper->upper))
1173                                 list_add(&upper->list, &useless);
1174                 }
1175
1176                 while (!list_empty(&useless)) {
1177                         lower = list_entry(useless.next,
1178                                            struct backref_node, list);
1179                         list_del_init(&lower->list);
1180                         free_backref_node(cache, lower);
1181                 }
1182                 return ERR_PTR(err);
1183         }
1184         ASSERT(!node || !node->detached);
1185         return node;
1186 }
1187
1188 /*
1189  * helper to add backref node for the newly created snapshot.
1190  * the backref node is created by cloning backref node that
1191  * corresponds to root of source tree
1192  */
1193 static int clone_backref_node(struct btrfs_trans_handle *trans,
1194                               struct reloc_control *rc,
1195                               struct btrfs_root *src,
1196                               struct btrfs_root *dest)
1197 {
1198         struct btrfs_root *reloc_root = src->reloc_root;
1199         struct backref_cache *cache = &rc->backref_cache;
1200         struct backref_node *node = NULL;
1201         struct backref_node *new_node;
1202         struct backref_edge *edge;
1203         struct backref_edge *new_edge;
1204         struct rb_node *rb_node;
1205
1206         if (cache->last_trans > 0)
1207                 update_backref_cache(trans, cache);
1208
1209         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1210         if (rb_node) {
1211                 node = rb_entry(rb_node, struct backref_node, rb_node);
1212                 if (node->detached)
1213                         node = NULL;
1214                 else
1215                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1216         }
1217
1218         if (!node) {
1219                 rb_node = tree_search(&cache->rb_root,
1220                                       reloc_root->commit_root->start);
1221                 if (rb_node) {
1222                         node = rb_entry(rb_node, struct backref_node,
1223                                         rb_node);
1224                         BUG_ON(node->detached);
1225                 }
1226         }
1227
1228         if (!node)
1229                 return 0;
1230
1231         new_node = alloc_backref_node(cache);
1232         if (!new_node)
1233                 return -ENOMEM;
1234
1235         new_node->bytenr = dest->node->start;
1236         new_node->level = node->level;
1237         new_node->lowest = node->lowest;
1238         new_node->checked = 1;
1239         new_node->root = dest;
1240
1241         if (!node->lowest) {
1242                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1243                         new_edge = alloc_backref_edge(cache);
1244                         if (!new_edge)
1245                                 goto fail;
1246
1247                         new_edge->node[UPPER] = new_node;
1248                         new_edge->node[LOWER] = edge->node[LOWER];
1249                         list_add_tail(&new_edge->list[UPPER],
1250                                       &new_node->lower);
1251                 }
1252         } else {
1253                 list_add_tail(&new_node->lower, &cache->leaves);
1254         }
1255
1256         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1257                               &new_node->rb_node);
1258         if (rb_node)
1259                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1260
1261         if (!new_node->lowest) {
1262                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1263                         list_add_tail(&new_edge->list[LOWER],
1264                                       &new_edge->node[LOWER]->upper);
1265                 }
1266         }
1267         return 0;
1268 fail:
1269         while (!list_empty(&new_node->lower)) {
1270                 new_edge = list_entry(new_node->lower.next,
1271                                       struct backref_edge, list[UPPER]);
1272                 list_del(&new_edge->list[UPPER]);
1273                 free_backref_edge(cache, new_edge);
1274         }
1275         free_backref_node(cache, new_node);
1276         return -ENOMEM;
1277 }
1278
1279 /*
1280  * helper to add 'address of tree root -> reloc tree' mapping
1281  */
1282 static int __must_check __add_reloc_root(struct btrfs_root *root)
1283 {
1284         struct rb_node *rb_node;
1285         struct mapping_node *node;
1286         struct reloc_control *rc = root->fs_info->reloc_ctl;
1287
1288         node = kmalloc(sizeof(*node), GFP_NOFS);
1289         if (!node)
1290                 return -ENOMEM;
1291
1292         node->bytenr = root->commit_root->start;
1293         node->data = root;
1294
1295         spin_lock(&rc->reloc_root_tree.lock);
1296         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1297                               node->bytenr, &node->rb_node);
1298         spin_unlock(&rc->reloc_root_tree.lock);
1299         if (rb_node) {
1300                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1301                             "for start=%llu while inserting into relocation "
1302                             "tree", node->bytenr);
1303                 kfree(node);
1304                 return -EEXIST;
1305         }
1306
1307         list_add_tail(&root->root_list, &rc->reloc_roots);
1308         return 0;
1309 }
1310
1311 /*
1312  * helper to delete the 'address of tree root -> reloc tree'
1313  * mapping
1314  */
1315 static void __del_reloc_root(struct btrfs_root *root)
1316 {
1317         struct rb_node *rb_node;
1318         struct mapping_node *node = NULL;
1319         struct reloc_control *rc = root->fs_info->reloc_ctl;
1320
1321         if (rc && root->node) {
1322                 spin_lock(&rc->reloc_root_tree.lock);
1323                 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1324                                       root->commit_root->start);
1325                 if (rb_node) {
1326                         node = rb_entry(rb_node, struct mapping_node, rb_node);
1327                         rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1328                         RB_CLEAR_NODE(&node->rb_node);
1329                 }
1330                 spin_unlock(&rc->reloc_root_tree.lock);
1331                 ASSERT(!node || (struct btrfs_root *)node->data == root);
1332         }
1333
1334         spin_lock(&root->fs_info->trans_lock);
1335         list_del_init(&root->root_list);
1336         spin_unlock(&root->fs_info->trans_lock);
1337         kfree(node);
1338 }
1339
1340 /*
1341  * helper to update the 'address of tree root -> reloc tree'
1342  * mapping
1343  */
1344 static int __update_reloc_root(struct btrfs_root *root)
1345 {
1346         struct rb_node *rb_node;
1347         struct mapping_node *node = NULL;
1348         struct reloc_control *rc = root->fs_info->reloc_ctl;
1349
1350         spin_lock(&rc->reloc_root_tree.lock);
1351         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1352                               root->commit_root->start);
1353         if (rb_node) {
1354                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1355                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1356         }
1357         spin_unlock(&rc->reloc_root_tree.lock);
1358
1359         if (!node)
1360                 return 0;
1361         BUG_ON((struct btrfs_root *)node->data != root);
1362
1363         spin_lock(&rc->reloc_root_tree.lock);
1364         node->bytenr = root->node->start;
1365         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1366                               node->bytenr, &node->rb_node);
1367         spin_unlock(&rc->reloc_root_tree.lock);
1368         if (rb_node)
1369                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1370         return 0;
1371 }
1372
1373 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1374                                         struct btrfs_root *root, u64 objectid)
1375 {
1376         struct btrfs_root *reloc_root;
1377         struct extent_buffer *eb;
1378         struct btrfs_root_item *root_item;
1379         struct btrfs_key root_key;
1380         u64 last_snap = 0;
1381         int ret;
1382
1383         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1384         BUG_ON(!root_item);
1385
1386         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1387         root_key.type = BTRFS_ROOT_ITEM_KEY;
1388         root_key.offset = objectid;
1389
1390         if (root->root_key.objectid == objectid) {
1391                 /* called by btrfs_init_reloc_root */
1392                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1393                                       BTRFS_TREE_RELOC_OBJECTID);
1394                 BUG_ON(ret);
1395
1396                 last_snap = btrfs_root_last_snapshot(&root->root_item);
1397                 btrfs_set_root_last_snapshot(&root->root_item,
1398                                              trans->transid - 1);
1399         } else {
1400                 /*
1401                  * called by btrfs_reloc_post_snapshot_hook.
1402                  * the source tree is a reloc tree, all tree blocks
1403                  * modified after it was created have RELOC flag
1404                  * set in their headers. so it's OK to not update
1405                  * the 'last_snapshot'.
1406                  */
1407                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1408                                       BTRFS_TREE_RELOC_OBJECTID);
1409                 BUG_ON(ret);
1410         }
1411
1412         memcpy(root_item, &root->root_item, sizeof(*root_item));
1413         btrfs_set_root_bytenr(root_item, eb->start);
1414         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1415         btrfs_set_root_generation(root_item, trans->transid);
1416
1417         if (root->root_key.objectid == objectid) {
1418                 btrfs_set_root_refs(root_item, 0);
1419                 memset(&root_item->drop_progress, 0,
1420                        sizeof(struct btrfs_disk_key));
1421                 root_item->drop_level = 0;
1422                 /*
1423                  * abuse rtransid, it is safe because it is impossible to
1424                  * receive data into a relocation tree.
1425                  */
1426                 btrfs_set_root_rtransid(root_item, last_snap);
1427                 btrfs_set_root_otransid(root_item, trans->transid);
1428         }
1429
1430         btrfs_tree_unlock(eb);
1431         free_extent_buffer(eb);
1432
1433         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1434                                 &root_key, root_item);
1435         BUG_ON(ret);
1436         kfree(root_item);
1437
1438         reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
1439         BUG_ON(IS_ERR(reloc_root));
1440         reloc_root->last_trans = trans->transid;
1441         return reloc_root;
1442 }
1443
1444 /*
1445  * create reloc tree for a given fs tree. reloc tree is just a
1446  * snapshot of the fs tree with special root objectid.
1447  */
1448 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1449                           struct btrfs_root *root)
1450 {
1451         struct btrfs_root *reloc_root;
1452         struct reloc_control *rc = root->fs_info->reloc_ctl;
1453         struct btrfs_block_rsv *rsv;
1454         int clear_rsv = 0;
1455         int ret;
1456
1457         if (root->reloc_root) {
1458                 reloc_root = root->reloc_root;
1459                 reloc_root->last_trans = trans->transid;
1460                 return 0;
1461         }
1462
1463         if (!rc || !rc->create_reloc_tree ||
1464             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1465                 return 0;
1466
1467         if (!trans->reloc_reserved) {
1468                 rsv = trans->block_rsv;
1469                 trans->block_rsv = rc->block_rsv;
1470                 clear_rsv = 1;
1471         }
1472         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1473         if (clear_rsv)
1474                 trans->block_rsv = rsv;
1475
1476         ret = __add_reloc_root(reloc_root);
1477         BUG_ON(ret < 0);
1478         root->reloc_root = reloc_root;
1479         return 0;
1480 }
1481
1482 /*
1483  * update root item of reloc tree
1484  */
1485 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1486                             struct btrfs_root *root)
1487 {
1488         struct btrfs_root *reloc_root;
1489         struct btrfs_root_item *root_item;
1490         int ret;
1491
1492         if (!root->reloc_root)
1493                 goto out;
1494
1495         reloc_root = root->reloc_root;
1496         root_item = &reloc_root->root_item;
1497
1498         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1499             btrfs_root_refs(root_item) == 0) {
1500                 root->reloc_root = NULL;
1501                 __del_reloc_root(reloc_root);
1502         }
1503
1504         if (reloc_root->commit_root != reloc_root->node) {
1505                 __update_reloc_root(reloc_root);
1506                 btrfs_set_root_node(root_item, reloc_root->node);
1507                 free_extent_buffer(reloc_root->commit_root);
1508                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1509         }
1510
1511         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1512                                 &reloc_root->root_key, root_item);
1513         BUG_ON(ret);
1514
1515 out:
1516         return 0;
1517 }
1518
1519 /*
1520  * helper to find first cached inode with inode number >= objectid
1521  * in a subvolume
1522  */
1523 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1524 {
1525         struct rb_node *node;
1526         struct rb_node *prev;
1527         struct btrfs_inode *entry;
1528         struct inode *inode;
1529
1530         spin_lock(&root->inode_lock);
1531 again:
1532         node = root->inode_tree.rb_node;
1533         prev = NULL;
1534         while (node) {
1535                 prev = node;
1536                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1537
1538                 if (objectid < btrfs_ino(&entry->vfs_inode))
1539                         node = node->rb_left;
1540                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1541                         node = node->rb_right;
1542                 else
1543                         break;
1544         }
1545         if (!node) {
1546                 while (prev) {
1547                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1548                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1549                                 node = prev;
1550                                 break;
1551                         }
1552                         prev = rb_next(prev);
1553                 }
1554         }
1555         while (node) {
1556                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1557                 inode = igrab(&entry->vfs_inode);
1558                 if (inode) {
1559                         spin_unlock(&root->inode_lock);
1560                         return inode;
1561                 }
1562
1563                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1564                 if (cond_resched_lock(&root->inode_lock))
1565                         goto again;
1566
1567                 node = rb_next(node);
1568         }
1569         spin_unlock(&root->inode_lock);
1570         return NULL;
1571 }
1572
1573 static int in_block_group(u64 bytenr,
1574                           struct btrfs_block_group_cache *block_group)
1575 {
1576         if (bytenr >= block_group->key.objectid &&
1577             bytenr < block_group->key.objectid + block_group->key.offset)
1578                 return 1;
1579         return 0;
1580 }
1581
1582 /*
1583  * get new location of data
1584  */
1585 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1586                             u64 bytenr, u64 num_bytes)
1587 {
1588         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1589         struct btrfs_path *path;
1590         struct btrfs_file_extent_item *fi;
1591         struct extent_buffer *leaf;
1592         int ret;
1593
1594         path = btrfs_alloc_path();
1595         if (!path)
1596                 return -ENOMEM;
1597
1598         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1599         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1600                                        bytenr, 0);
1601         if (ret < 0)
1602                 goto out;
1603         if (ret > 0) {
1604                 ret = -ENOENT;
1605                 goto out;
1606         }
1607
1608         leaf = path->nodes[0];
1609         fi = btrfs_item_ptr(leaf, path->slots[0],
1610                             struct btrfs_file_extent_item);
1611
1612         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1613                btrfs_file_extent_compression(leaf, fi) ||
1614                btrfs_file_extent_encryption(leaf, fi) ||
1615                btrfs_file_extent_other_encoding(leaf, fi));
1616
1617         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1618                 ret = -EINVAL;
1619                 goto out;
1620         }
1621
1622         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1623         ret = 0;
1624 out:
1625         btrfs_free_path(path);
1626         return ret;
1627 }
1628
1629 /*
1630  * update file extent items in the tree leaf to point to
1631  * the new locations.
1632  */
1633 static noinline_for_stack
1634 int replace_file_extents(struct btrfs_trans_handle *trans,
1635                          struct reloc_control *rc,
1636                          struct btrfs_root *root,
1637                          struct extent_buffer *leaf)
1638 {
1639         struct btrfs_key key;
1640         struct btrfs_file_extent_item *fi;
1641         struct inode *inode = NULL;
1642         u64 parent;
1643         u64 bytenr;
1644         u64 new_bytenr = 0;
1645         u64 num_bytes;
1646         u64 end;
1647         u32 nritems;
1648         u32 i;
1649         int ret = 0;
1650         int first = 1;
1651         int dirty = 0;
1652
1653         if (rc->stage != UPDATE_DATA_PTRS)
1654                 return 0;
1655
1656         /* reloc trees always use full backref */
1657         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1658                 parent = leaf->start;
1659         else
1660                 parent = 0;
1661
1662         nritems = btrfs_header_nritems(leaf);
1663         for (i = 0; i < nritems; i++) {
1664                 cond_resched();
1665                 btrfs_item_key_to_cpu(leaf, &key, i);
1666                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1667                         continue;
1668                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1669                 if (btrfs_file_extent_type(leaf, fi) ==
1670                     BTRFS_FILE_EXTENT_INLINE)
1671                         continue;
1672                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1673                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1674                 if (bytenr == 0)
1675                         continue;
1676                 if (!in_block_group(bytenr, rc->block_group))
1677                         continue;
1678
1679                 /*
1680                  * if we are modifying block in fs tree, wait for readpage
1681                  * to complete and drop the extent cache
1682                  */
1683                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1684                         if (first) {
1685                                 inode = find_next_inode(root, key.objectid);
1686                                 first = 0;
1687                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1688                                 btrfs_add_delayed_iput(inode);
1689                                 inode = find_next_inode(root, key.objectid);
1690                         }
1691                         if (inode && btrfs_ino(inode) == key.objectid) {
1692                                 end = key.offset +
1693                                       btrfs_file_extent_num_bytes(leaf, fi);
1694                                 WARN_ON(!IS_ALIGNED(key.offset,
1695                                                     root->sectorsize));
1696                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1697                                 end--;
1698                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1699                                                       key.offset, end);
1700                                 if (!ret)
1701                                         continue;
1702
1703                                 btrfs_drop_extent_cache(inode, key.offset, end,
1704                                                         1);
1705                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1706                                               key.offset, end);
1707                         }
1708                 }
1709
1710                 ret = get_new_location(rc->data_inode, &new_bytenr,
1711                                        bytenr, num_bytes);
1712                 if (ret) {
1713                         /*
1714                          * Don't have to abort since we've not changed anything
1715                          * in the file extent yet.
1716                          */
1717                         break;
1718                 }
1719
1720                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1721                 dirty = 1;
1722
1723                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1724                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1725                                            num_bytes, parent,
1726                                            btrfs_header_owner(leaf),
1727                                            key.objectid, key.offset);
1728                 if (ret) {
1729                         btrfs_abort_transaction(trans, root, ret);
1730                         break;
1731                 }
1732
1733                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1734                                         parent, btrfs_header_owner(leaf),
1735                                         key.objectid, key.offset);
1736                 if (ret) {
1737                         btrfs_abort_transaction(trans, root, ret);
1738                         break;
1739                 }
1740         }
1741         if (dirty)
1742                 btrfs_mark_buffer_dirty(leaf);
1743         if (inode)
1744                 btrfs_add_delayed_iput(inode);
1745         return ret;
1746 }
1747
1748 static noinline_for_stack
1749 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1750                      struct btrfs_path *path, int level)
1751 {
1752         struct btrfs_disk_key key1;
1753         struct btrfs_disk_key key2;
1754         btrfs_node_key(eb, &key1, slot);
1755         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1756         return memcmp(&key1, &key2, sizeof(key1));
1757 }
1758
1759 /*
1760  * try to replace tree blocks in fs tree with the new blocks
1761  * in reloc tree. tree blocks haven't been modified since the
1762  * reloc tree was create can be replaced.
1763  *
1764  * if a block was replaced, level of the block + 1 is returned.
1765  * if no block got replaced, 0 is returned. if there are other
1766  * errors, a negative error number is returned.
1767  */
1768 static noinline_for_stack
1769 int replace_path(struct btrfs_trans_handle *trans,
1770                  struct btrfs_root *dest, struct btrfs_root *src,
1771                  struct btrfs_path *path, struct btrfs_key *next_key,
1772                  int lowest_level, int max_level)
1773 {
1774         struct extent_buffer *eb;
1775         struct extent_buffer *parent;
1776         struct btrfs_key key;
1777         u64 old_bytenr;
1778         u64 new_bytenr;
1779         u64 old_ptr_gen;
1780         u64 new_ptr_gen;
1781         u64 last_snapshot;
1782         u32 blocksize;
1783         int cow = 0;
1784         int level;
1785         int ret;
1786         int slot;
1787
1788         ASSERT(src->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1789         ASSERT(dest->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1790
1791         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1792 again:
1793         slot = path->slots[lowest_level];
1794         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1795
1796         eb = btrfs_lock_root_node(dest);
1797         btrfs_set_lock_blocking(eb);
1798         level = btrfs_header_level(eb);
1799
1800         if (level < lowest_level) {
1801                 btrfs_tree_unlock(eb);
1802                 free_extent_buffer(eb);
1803                 return 0;
1804         }
1805
1806         if (cow) {
1807                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1808                 BUG_ON(ret);
1809         }
1810         btrfs_set_lock_blocking(eb);
1811
1812         if (next_key) {
1813                 next_key->objectid = (u64)-1;
1814                 next_key->type = (u8)-1;
1815                 next_key->offset = (u64)-1;
1816         }
1817
1818         parent = eb;
1819         while (1) {
1820                 level = btrfs_header_level(parent);
1821                 ASSERT(level >= lowest_level);
1822
1823                 ret = btrfs_bin_search(parent, &key, level, &slot);
1824                 if (ret && slot > 0)
1825                         slot--;
1826
1827                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1828                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1829
1830                 old_bytenr = btrfs_node_blockptr(parent, slot);
1831                 blocksize = dest->nodesize;
1832                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1833
1834                 if (level <= max_level) {
1835                         eb = path->nodes[level];
1836                         new_bytenr = btrfs_node_blockptr(eb,
1837                                                         path->slots[level]);
1838                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1839                                                         path->slots[level]);
1840                 } else {
1841                         new_bytenr = 0;
1842                         new_ptr_gen = 0;
1843                 }
1844
1845                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1846                         ret = level;
1847                         break;
1848                 }
1849
1850                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1851                     memcmp_node_keys(parent, slot, path, level)) {
1852                         if (level <= lowest_level) {
1853                                 ret = 0;
1854                                 break;
1855                         }
1856
1857                         eb = read_tree_block(dest, old_bytenr, old_ptr_gen);
1858                         if (IS_ERR(eb)) {
1859                                 ret = PTR_ERR(eb);
1860                         } else if (!extent_buffer_uptodate(eb)) {
1861                                 ret = -EIO;
1862                                 free_extent_buffer(eb);
1863                                 break;
1864                         }
1865                         btrfs_tree_lock(eb);
1866                         if (cow) {
1867                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1868                                                       slot, &eb);
1869                                 BUG_ON(ret);
1870                         }
1871                         btrfs_set_lock_blocking(eb);
1872
1873                         btrfs_tree_unlock(parent);
1874                         free_extent_buffer(parent);
1875
1876                         parent = eb;
1877                         continue;
1878                 }
1879
1880                 if (!cow) {
1881                         btrfs_tree_unlock(parent);
1882                         free_extent_buffer(parent);
1883                         cow = 1;
1884                         goto again;
1885                 }
1886
1887                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1888                                       path->slots[level]);
1889                 btrfs_release_path(path);
1890
1891                 path->lowest_level = level;
1892                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1893                 path->lowest_level = 0;
1894                 BUG_ON(ret);
1895
1896                 /*
1897                  * swap blocks in fs tree and reloc tree.
1898                  */
1899                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1900                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1901                 btrfs_mark_buffer_dirty(parent);
1902
1903                 btrfs_set_node_blockptr(path->nodes[level],
1904                                         path->slots[level], old_bytenr);
1905                 btrfs_set_node_ptr_generation(path->nodes[level],
1906                                               path->slots[level], old_ptr_gen);
1907                 btrfs_mark_buffer_dirty(path->nodes[level]);
1908
1909                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1910                                         path->nodes[level]->start,
1911                                         src->root_key.objectid, level - 1, 0);
1912                 BUG_ON(ret);
1913                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1914                                         0, dest->root_key.objectid, level - 1,
1915                                         0);
1916                 BUG_ON(ret);
1917
1918                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1919                                         path->nodes[level]->start,
1920                                         src->root_key.objectid, level - 1, 0);
1921                 BUG_ON(ret);
1922
1923                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1924                                         0, dest->root_key.objectid, level - 1,
1925                                         0);
1926                 BUG_ON(ret);
1927
1928                 btrfs_unlock_up_safe(path, 0);
1929
1930                 ret = level;
1931                 break;
1932         }
1933         btrfs_tree_unlock(parent);
1934         free_extent_buffer(parent);
1935         return ret;
1936 }
1937
1938 /*
1939  * helper to find next relocated block in reloc tree
1940  */
1941 static noinline_for_stack
1942 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1943                        int *level)
1944 {
1945         struct extent_buffer *eb;
1946         int i;
1947         u64 last_snapshot;
1948         u32 nritems;
1949
1950         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1951
1952         for (i = 0; i < *level; i++) {
1953                 free_extent_buffer(path->nodes[i]);
1954                 path->nodes[i] = NULL;
1955         }
1956
1957         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1958                 eb = path->nodes[i];
1959                 nritems = btrfs_header_nritems(eb);
1960                 while (path->slots[i] + 1 < nritems) {
1961                         path->slots[i]++;
1962                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1963                             last_snapshot)
1964                                 continue;
1965
1966                         *level = i;
1967                         return 0;
1968                 }
1969                 free_extent_buffer(path->nodes[i]);
1970                 path->nodes[i] = NULL;
1971         }
1972         return 1;
1973 }
1974
1975 /*
1976  * walk down reloc tree to find relocated block of lowest level
1977  */
1978 static noinline_for_stack
1979 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1980                          int *level)
1981 {
1982         struct extent_buffer *eb = NULL;
1983         int i;
1984         u64 bytenr;
1985         u64 ptr_gen = 0;
1986         u64 last_snapshot;
1987         u32 nritems;
1988
1989         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1990
1991         for (i = *level; i > 0; i--) {
1992                 eb = path->nodes[i];
1993                 nritems = btrfs_header_nritems(eb);
1994                 while (path->slots[i] < nritems) {
1995                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1996                         if (ptr_gen > last_snapshot)
1997                                 break;
1998                         path->slots[i]++;
1999                 }
2000                 if (path->slots[i] >= nritems) {
2001                         if (i == *level)
2002                                 break;
2003                         *level = i + 1;
2004                         return 0;
2005                 }
2006                 if (i == 1) {
2007                         *level = i;
2008                         return 0;
2009                 }
2010
2011                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2012                 eb = read_tree_block(root, bytenr, ptr_gen);
2013                 if (IS_ERR(eb)) {
2014                         return PTR_ERR(eb);
2015                 } else if (!extent_buffer_uptodate(eb)) {
2016                         free_extent_buffer(eb);
2017                         return -EIO;
2018                 }
2019                 BUG_ON(btrfs_header_level(eb) != i - 1);
2020                 path->nodes[i - 1] = eb;
2021                 path->slots[i - 1] = 0;
2022         }
2023         return 1;
2024 }
2025
2026 /*
2027  * invalidate extent cache for file extents whose key in range of
2028  * [min_key, max_key)
2029  */
2030 static int invalidate_extent_cache(struct btrfs_root *root,
2031                                    struct btrfs_key *min_key,
2032                                    struct btrfs_key *max_key)
2033 {
2034         struct inode *inode = NULL;
2035         u64 objectid;
2036         u64 start, end;
2037         u64 ino;
2038
2039         objectid = min_key->objectid;
2040         while (1) {
2041                 cond_resched();
2042                 iput(inode);
2043
2044                 if (objectid > max_key->objectid)
2045                         break;
2046
2047                 inode = find_next_inode(root, objectid);
2048                 if (!inode)
2049                         break;
2050                 ino = btrfs_ino(inode);
2051
2052                 if (ino > max_key->objectid) {
2053                         iput(inode);
2054                         break;
2055                 }
2056
2057                 objectid = ino + 1;
2058                 if (!S_ISREG(inode->i_mode))
2059                         continue;
2060
2061                 if (unlikely(min_key->objectid == ino)) {
2062                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2063                                 continue;
2064                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2065                                 start = 0;
2066                         else {
2067                                 start = min_key->offset;
2068                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2069                         }
2070                 } else {
2071                         start = 0;
2072                 }
2073
2074                 if (unlikely(max_key->objectid == ino)) {
2075                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2076                                 continue;
2077                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2078                                 end = (u64)-1;
2079                         } else {
2080                                 if (max_key->offset == 0)
2081                                         continue;
2082                                 end = max_key->offset;
2083                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2084                                 end--;
2085                         }
2086                 } else {
2087                         end = (u64)-1;
2088                 }
2089
2090                 /* the lock_extent waits for readpage to complete */
2091                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2092                 btrfs_drop_extent_cache(inode, start, end, 1);
2093                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2094         }
2095         return 0;
2096 }
2097
2098 static int find_next_key(struct btrfs_path *path, int level,
2099                          struct btrfs_key *key)
2100
2101 {
2102         while (level < BTRFS_MAX_LEVEL) {
2103                 if (!path->nodes[level])
2104                         break;
2105                 if (path->slots[level] + 1 <
2106                     btrfs_header_nritems(path->nodes[level])) {
2107                         btrfs_node_key_to_cpu(path->nodes[level], key,
2108                                               path->slots[level] + 1);
2109                         return 0;
2110                 }
2111                 level++;
2112         }
2113         return 1;
2114 }
2115
2116 /*
2117  * merge the relocated tree blocks in reloc tree with corresponding
2118  * fs tree.
2119  */
2120 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2121                                                struct btrfs_root *root)
2122 {
2123         LIST_HEAD(inode_list);
2124         struct btrfs_key key;
2125         struct btrfs_key next_key;
2126         struct btrfs_trans_handle *trans = NULL;
2127         struct btrfs_root *reloc_root;
2128         struct btrfs_root_item *root_item;
2129         struct btrfs_path *path;
2130         struct extent_buffer *leaf;
2131         int level;
2132         int max_level;
2133         int replaced = 0;
2134         int ret;
2135         int err = 0;
2136         u32 min_reserved;
2137
2138         path = btrfs_alloc_path();
2139         if (!path)
2140                 return -ENOMEM;
2141         path->reada = 1;
2142
2143         reloc_root = root->reloc_root;
2144         root_item = &reloc_root->root_item;
2145
2146         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2147                 level = btrfs_root_level(root_item);
2148                 extent_buffer_get(reloc_root->node);
2149                 path->nodes[level] = reloc_root->node;
2150                 path->slots[level] = 0;
2151         } else {
2152                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2153
2154                 level = root_item->drop_level;
2155                 BUG_ON(level == 0);
2156                 path->lowest_level = level;
2157                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2158                 path->lowest_level = 0;
2159                 if (ret < 0) {
2160                         btrfs_free_path(path);
2161                         return ret;
2162                 }
2163
2164                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2165                                       path->slots[level]);
2166                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2167
2168                 btrfs_unlock_up_safe(path, 0);
2169         }
2170
2171         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2172         memset(&next_key, 0, sizeof(next_key));
2173
2174         while (1) {
2175                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2176                                              BTRFS_RESERVE_FLUSH_ALL);
2177                 if (ret) {
2178                         err = ret;
2179                         goto out;
2180                 }
2181                 trans = btrfs_start_transaction(root, 0);
2182                 if (IS_ERR(trans)) {
2183                         err = PTR_ERR(trans);
2184                         trans = NULL;
2185                         goto out;
2186                 }
2187                 trans->block_rsv = rc->block_rsv;
2188
2189                 replaced = 0;
2190                 max_level = level;
2191
2192                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2193                 if (ret < 0) {
2194                         err = ret;
2195                         goto out;
2196                 }
2197                 if (ret > 0)
2198                         break;
2199
2200                 if (!find_next_key(path, level, &key) &&
2201                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2202                         ret = 0;
2203                 } else {
2204                         ret = replace_path(trans, root, reloc_root, path,
2205                                            &next_key, level, max_level);
2206                 }
2207                 if (ret < 0) {
2208                         err = ret;
2209                         goto out;
2210                 }
2211
2212                 if (ret > 0) {
2213                         level = ret;
2214                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2215                                               path->slots[level]);
2216                         replaced = 1;
2217                 }
2218
2219                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2220                 if (ret > 0)
2221                         break;
2222
2223                 BUG_ON(level == 0);
2224                 /*
2225                  * save the merging progress in the drop_progress.
2226                  * this is OK since root refs == 1 in this case.
2227                  */
2228                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2229                                path->slots[level]);
2230                 root_item->drop_level = level;
2231
2232                 btrfs_end_transaction_throttle(trans, root);
2233                 trans = NULL;
2234
2235                 btrfs_btree_balance_dirty(root);
2236
2237                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2238                         invalidate_extent_cache(root, &key, &next_key);
2239         }
2240
2241         /*
2242          * handle the case only one block in the fs tree need to be
2243          * relocated and the block is tree root.
2244          */
2245         leaf = btrfs_lock_root_node(root);
2246         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2247         btrfs_tree_unlock(leaf);
2248         free_extent_buffer(leaf);
2249         if (ret < 0)
2250                 err = ret;
2251 out:
2252         btrfs_free_path(path);
2253
2254         if (err == 0) {
2255                 memset(&root_item->drop_progress, 0,
2256                        sizeof(root_item->drop_progress));
2257                 root_item->drop_level = 0;
2258                 btrfs_set_root_refs(root_item, 0);
2259                 btrfs_update_reloc_root(trans, root);
2260         }
2261
2262         if (trans)
2263                 btrfs_end_transaction_throttle(trans, root);
2264
2265         btrfs_btree_balance_dirty(root);
2266
2267         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2268                 invalidate_extent_cache(root, &key, &next_key);
2269
2270         return err;
2271 }
2272
2273 static noinline_for_stack
2274 int prepare_to_merge(struct reloc_control *rc, int err)
2275 {
2276         struct btrfs_root *root = rc->extent_root;
2277         struct btrfs_root *reloc_root;
2278         struct btrfs_trans_handle *trans;
2279         LIST_HEAD(reloc_roots);
2280         u64 num_bytes = 0;
2281         int ret;
2282
2283         mutex_lock(&root->fs_info->reloc_mutex);
2284         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2285         rc->merging_rsv_size += rc->nodes_relocated * 2;
2286         mutex_unlock(&root->fs_info->reloc_mutex);
2287
2288 again:
2289         if (!err) {
2290                 num_bytes = rc->merging_rsv_size;
2291                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2292                                           BTRFS_RESERVE_FLUSH_ALL);
2293                 if (ret)
2294                         err = ret;
2295         }
2296
2297         trans = btrfs_join_transaction(rc->extent_root);
2298         if (IS_ERR(trans)) {
2299                 if (!err)
2300                         btrfs_block_rsv_release(rc->extent_root,
2301                                                 rc->block_rsv, num_bytes);
2302                 return PTR_ERR(trans);
2303         }
2304
2305         if (!err) {
2306                 if (num_bytes != rc->merging_rsv_size) {
2307                         btrfs_end_transaction(trans, rc->extent_root);
2308                         btrfs_block_rsv_release(rc->extent_root,
2309                                                 rc->block_rsv, num_bytes);
2310                         goto again;
2311                 }
2312         }
2313
2314         rc->merge_reloc_tree = 1;
2315
2316         while (!list_empty(&rc->reloc_roots)) {
2317                 reloc_root = list_entry(rc->reloc_roots.next,
2318                                         struct btrfs_root, root_list);
2319                 list_del_init(&reloc_root->root_list);
2320
2321                 root = read_fs_root(reloc_root->fs_info,
2322                                     reloc_root->root_key.offset);
2323                 BUG_ON(IS_ERR(root));
2324                 BUG_ON(root->reloc_root != reloc_root);
2325
2326                 /*
2327                  * set reference count to 1, so btrfs_recover_relocation
2328                  * knows it should resumes merging
2329                  */
2330                 if (!err)
2331                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2332                 btrfs_update_reloc_root(trans, root);
2333
2334                 list_add(&reloc_root->root_list, &reloc_roots);
2335         }
2336
2337         list_splice(&reloc_roots, &rc->reloc_roots);
2338
2339         if (!err)
2340                 btrfs_commit_transaction(trans, rc->extent_root);
2341         else
2342                 btrfs_end_transaction(trans, rc->extent_root);
2343         return err;
2344 }
2345
2346 static noinline_for_stack
2347 void free_reloc_roots(struct list_head *list)
2348 {
2349         struct btrfs_root *reloc_root;
2350
2351         while (!list_empty(list)) {
2352                 reloc_root = list_entry(list->next, struct btrfs_root,
2353                                         root_list);
2354                 __del_reloc_root(reloc_root);
2355                 free_extent_buffer(reloc_root->node);
2356                 free_extent_buffer(reloc_root->commit_root);
2357                 reloc_root->node = NULL;
2358                 reloc_root->commit_root = NULL;
2359         }
2360 }
2361
2362 static noinline_for_stack
2363 void merge_reloc_roots(struct reloc_control *rc)
2364 {
2365         struct btrfs_root *root;
2366         struct btrfs_root *reloc_root;
2367         u64 last_snap;
2368         u64 otransid;
2369         u64 objectid;
2370         LIST_HEAD(reloc_roots);
2371         int found = 0;
2372         int ret = 0;
2373 again:
2374         root = rc->extent_root;
2375
2376         /*
2377          * this serializes us with btrfs_record_root_in_transaction,
2378          * we have to make sure nobody is in the middle of
2379          * adding their roots to the list while we are
2380          * doing this splice
2381          */
2382         mutex_lock(&root->fs_info->reloc_mutex);
2383         list_splice_init(&rc->reloc_roots, &reloc_roots);
2384         mutex_unlock(&root->fs_info->reloc_mutex);
2385
2386         while (!list_empty(&reloc_roots)) {
2387                 found = 1;
2388                 reloc_root = list_entry(reloc_roots.next,
2389                                         struct btrfs_root, root_list);
2390
2391                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2392                         root = read_fs_root(reloc_root->fs_info,
2393                                             reloc_root->root_key.offset);
2394                         BUG_ON(IS_ERR(root));
2395                         BUG_ON(root->reloc_root != reloc_root);
2396
2397                         ret = merge_reloc_root(rc, root);
2398                         if (ret) {
2399                                 if (list_empty(&reloc_root->root_list))
2400                                         list_add_tail(&reloc_root->root_list,
2401                                                       &reloc_roots);
2402                                 goto out;
2403                         }
2404                 } else {
2405                         list_del_init(&reloc_root->root_list);
2406                 }
2407
2408                 /*
2409                  * we keep the old last snapshod transid in rtranid when we
2410                  * created the relocation tree.
2411                  */
2412                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2413                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2414                 objectid = reloc_root->root_key.offset;
2415
2416                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2417                 if (ret < 0) {
2418                         if (list_empty(&reloc_root->root_list))
2419                                 list_add_tail(&reloc_root->root_list,
2420                                               &reloc_roots);
2421                         goto out;
2422                 }
2423         }
2424
2425         if (found) {
2426                 found = 0;
2427                 goto again;
2428         }
2429 out:
2430         if (ret) {
2431                 btrfs_std_error(root->fs_info, ret, NULL);
2432                 if (!list_empty(&reloc_roots))
2433                         free_reloc_roots(&reloc_roots);
2434
2435                 /* new reloc root may be added */
2436                 mutex_lock(&root->fs_info->reloc_mutex);
2437                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2438                 mutex_unlock(&root->fs_info->reloc_mutex);
2439                 if (!list_empty(&reloc_roots))
2440                         free_reloc_roots(&reloc_roots);
2441         }
2442
2443         /*
2444          * We used to have
2445          *
2446          * BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2447          *
2448          * here, but it's wrong.  If we fail to start the transaction in
2449          * prepare_to_merge() we will have only 0 ref reloc roots, none of which
2450          * have actually been removed from the reloc_root_tree rb tree.  This is
2451          * fine because we're bailing here, and we hold a reference on the root
2452          * for the list that holds it, so these roots will be cleaned up when we
2453          * do the reloc_dirty_list afterwards.  Meanwhile the root->reloc_root
2454          * will be cleaned up on unmount.
2455          *
2456          * The remaining nodes will be cleaned up by free_reloc_control.
2457          */
2458 }
2459
2460 static void free_block_list(struct rb_root *blocks)
2461 {
2462         struct tree_block *block;
2463         struct rb_node *rb_node;
2464         while ((rb_node = rb_first(blocks))) {
2465                 block = rb_entry(rb_node, struct tree_block, rb_node);
2466                 rb_erase(rb_node, blocks);
2467                 kfree(block);
2468         }
2469 }
2470
2471 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2472                                       struct btrfs_root *reloc_root)
2473 {
2474         struct btrfs_root *root;
2475
2476         if (reloc_root->last_trans == trans->transid)
2477                 return 0;
2478
2479         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2480         BUG_ON(IS_ERR(root));
2481         BUG_ON(root->reloc_root != reloc_root);
2482
2483         return btrfs_record_root_in_trans(trans, root);
2484 }
2485
2486 static noinline_for_stack
2487 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2488                                      struct reloc_control *rc,
2489                                      struct backref_node *node,
2490                                      struct backref_edge *edges[])
2491 {
2492         struct backref_node *next;
2493         struct btrfs_root *root;
2494         int index = 0;
2495
2496         next = node;
2497         while (1) {
2498                 cond_resched();
2499                 next = walk_up_backref(next, edges, &index);
2500                 root = next->root;
2501                 BUG_ON(!root);
2502                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2503
2504                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2505                         record_reloc_root_in_trans(trans, root);
2506                         break;
2507                 }
2508
2509                 btrfs_record_root_in_trans(trans, root);
2510                 root = root->reloc_root;
2511
2512                 if (next->new_bytenr != root->node->start) {
2513                         BUG_ON(next->new_bytenr);
2514                         BUG_ON(!list_empty(&next->list));
2515                         next->new_bytenr = root->node->start;
2516                         next->root = root;
2517                         list_add_tail(&next->list,
2518                                       &rc->backref_cache.changed);
2519                         __mark_block_processed(rc, next);
2520                         break;
2521                 }
2522
2523                 WARN_ON(1);
2524                 root = NULL;
2525                 next = walk_down_backref(edges, &index);
2526                 if (!next || next->level <= node->level)
2527                         break;
2528         }
2529         if (!root)
2530                 return NULL;
2531
2532         next = node;
2533         /* setup backref node path for btrfs_reloc_cow_block */
2534         while (1) {
2535                 rc->backref_cache.path[next->level] = next;
2536                 if (--index < 0)
2537                         break;
2538                 next = edges[index]->node[UPPER];
2539         }
2540         return root;
2541 }
2542
2543 /*
2544  * select a tree root for relocation. return NULL if the block
2545  * is reference counted. we should use do_relocation() in this
2546  * case. return a tree root pointer if the block isn't reference
2547  * counted. return -ENOENT if the block is root of reloc tree.
2548  */
2549 static noinline_for_stack
2550 struct btrfs_root *select_one_root(struct backref_node *node)
2551 {
2552         struct backref_node *next;
2553         struct btrfs_root *root;
2554         struct btrfs_root *fs_root = NULL;
2555         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2556         int index = 0;
2557
2558         next = node;
2559         while (1) {
2560                 cond_resched();
2561                 next = walk_up_backref(next, edges, &index);
2562                 root = next->root;
2563                 BUG_ON(!root);
2564
2565                 /* no other choice for non-references counted tree */
2566                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2567                         return root;
2568
2569                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2570                         fs_root = root;
2571
2572                 if (next != node)
2573                         return NULL;
2574
2575                 next = walk_down_backref(edges, &index);
2576                 if (!next || next->level <= node->level)
2577                         break;
2578         }
2579
2580         if (!fs_root)
2581                 return ERR_PTR(-ENOENT);
2582         return fs_root;
2583 }
2584
2585 static noinline_for_stack
2586 u64 calcu_metadata_size(struct reloc_control *rc,
2587                         struct backref_node *node, int reserve)
2588 {
2589         struct backref_node *next = node;
2590         struct backref_edge *edge;
2591         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2592         u64 num_bytes = 0;
2593         int index = 0;
2594
2595         BUG_ON(reserve && node->processed);
2596
2597         while (next) {
2598                 cond_resched();
2599                 while (1) {
2600                         if (next->processed && (reserve || next != node))
2601                                 break;
2602
2603                         num_bytes += rc->extent_root->nodesize;
2604
2605                         if (list_empty(&next->upper))
2606                                 break;
2607
2608                         edge = list_entry(next->upper.next,
2609                                           struct backref_edge, list[LOWER]);
2610                         edges[index++] = edge;
2611                         next = edge->node[UPPER];
2612                 }
2613                 next = walk_down_backref(edges, &index);
2614         }
2615         return num_bytes;
2616 }
2617
2618 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2619                                   struct reloc_control *rc,
2620                                   struct backref_node *node)
2621 {
2622         struct btrfs_root *root = rc->extent_root;
2623         u64 num_bytes;
2624         int ret;
2625         u64 tmp;
2626
2627         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2628
2629         trans->block_rsv = rc->block_rsv;
2630         rc->reserved_bytes += num_bytes;
2631         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2632                                 BTRFS_RESERVE_FLUSH_ALL);
2633         if (ret) {
2634                 if (ret == -EAGAIN) {
2635                         tmp = rc->extent_root->nodesize *
2636                                 RELOCATION_RESERVED_NODES;
2637                         while (tmp <= rc->reserved_bytes)
2638                                 tmp <<= 1;
2639                         /*
2640                          * only one thread can access block_rsv at this point,
2641                          * so we don't need hold lock to protect block_rsv.
2642                          * we expand more reservation size here to allow enough
2643                          * space for relocation and we will return eailer in
2644                          * enospc case.
2645                          */
2646                         rc->block_rsv->size = tmp + rc->extent_root->nodesize *
2647                                               RELOCATION_RESERVED_NODES;
2648                 }
2649                 return ret;
2650         }
2651
2652         return 0;
2653 }
2654
2655 /*
2656  * relocate a block tree, and then update pointers in upper level
2657  * blocks that reference the block to point to the new location.
2658  *
2659  * if called by link_to_upper, the block has already been relocated.
2660  * in that case this function just updates pointers.
2661  */
2662 static int do_relocation(struct btrfs_trans_handle *trans,
2663                          struct reloc_control *rc,
2664                          struct backref_node *node,
2665                          struct btrfs_key *key,
2666                          struct btrfs_path *path, int lowest)
2667 {
2668         struct backref_node *upper;
2669         struct backref_edge *edge;
2670         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2671         struct btrfs_root *root;
2672         struct extent_buffer *eb;
2673         u32 blocksize;
2674         u64 bytenr;
2675         u64 generation;
2676         int slot;
2677         int ret;
2678         int err = 0;
2679
2680         BUG_ON(lowest && node->eb);
2681
2682         path->lowest_level = node->level + 1;
2683         rc->backref_cache.path[node->level] = node;
2684         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2685                 cond_resched();
2686
2687                 upper = edge->node[UPPER];
2688                 root = select_reloc_root(trans, rc, upper, edges);
2689                 BUG_ON(!root);
2690
2691                 if (upper->eb && !upper->locked) {
2692                         if (!lowest) {
2693                                 ret = btrfs_bin_search(upper->eb, key,
2694                                                        upper->level, &slot);
2695                                 BUG_ON(ret);
2696                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2697                                 if (node->eb->start == bytenr)
2698                                         goto next;
2699                         }
2700                         drop_node_buffer(upper);
2701                 }
2702
2703                 if (!upper->eb) {
2704                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2705                         if (ret) {
2706                                 if (ret < 0)
2707                                         err = ret;
2708                                 else
2709                                         err = -ENOENT;
2710
2711                                 btrfs_release_path(path);
2712                                 break;
2713                         }
2714
2715                         if (!upper->eb) {
2716                                 upper->eb = path->nodes[upper->level];
2717                                 path->nodes[upper->level] = NULL;
2718                         } else {
2719                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2720                         }
2721
2722                         upper->locked = 1;
2723                         path->locks[upper->level] = 0;
2724
2725                         slot = path->slots[upper->level];
2726                         btrfs_release_path(path);
2727                 } else {
2728                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2729                                                &slot);
2730                         BUG_ON(ret);
2731                 }
2732
2733                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2734                 if (lowest) {
2735                         BUG_ON(bytenr != node->bytenr);
2736                 } else {
2737                         if (node->eb->start == bytenr)
2738                                 goto next;
2739                 }
2740
2741                 blocksize = root->nodesize;
2742                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2743                 eb = read_tree_block(root, bytenr, generation);
2744                 if (IS_ERR(eb)) {
2745                         err = PTR_ERR(eb);
2746                         goto next;
2747                 } else if (!extent_buffer_uptodate(eb)) {
2748                         free_extent_buffer(eb);
2749                         err = -EIO;
2750                         goto next;
2751                 }
2752                 btrfs_tree_lock(eb);
2753                 btrfs_set_lock_blocking(eb);
2754
2755                 if (!node->eb) {
2756                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2757                                               slot, &eb);
2758                         btrfs_tree_unlock(eb);
2759                         free_extent_buffer(eb);
2760                         if (ret < 0) {
2761                                 err = ret;
2762                                 goto next;
2763                         }
2764                         BUG_ON(node->eb != eb);
2765                 } else {
2766                         btrfs_set_node_blockptr(upper->eb, slot,
2767                                                 node->eb->start);
2768                         btrfs_set_node_ptr_generation(upper->eb, slot,
2769                                                       trans->transid);
2770                         btrfs_mark_buffer_dirty(upper->eb);
2771
2772                         ret = btrfs_inc_extent_ref(trans, root,
2773                                                 node->eb->start, blocksize,
2774                                                 upper->eb->start,
2775                                                 btrfs_header_owner(upper->eb),
2776                                                 node->level, 0);
2777                         BUG_ON(ret);
2778
2779                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2780                         BUG_ON(ret);
2781                 }
2782 next:
2783                 if (!upper->pending)
2784                         drop_node_buffer(upper);
2785                 else
2786                         unlock_node_buffer(upper);
2787                 if (err)
2788                         break;
2789         }
2790
2791         if (!err && node->pending) {
2792                 drop_node_buffer(node);
2793                 list_move_tail(&node->list, &rc->backref_cache.changed);
2794                 node->pending = 0;
2795         }
2796
2797         path->lowest_level = 0;
2798         BUG_ON(err == -ENOSPC);
2799         return err;
2800 }
2801
2802 static int link_to_upper(struct btrfs_trans_handle *trans,
2803                          struct reloc_control *rc,
2804                          struct backref_node *node,
2805                          struct btrfs_path *path)
2806 {
2807         struct btrfs_key key;
2808
2809         btrfs_node_key_to_cpu(node->eb, &key, 0);
2810         return do_relocation(trans, rc, node, &key, path, 0);
2811 }
2812
2813 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2814                                 struct reloc_control *rc,
2815                                 struct btrfs_path *path, int err)
2816 {
2817         LIST_HEAD(list);
2818         struct backref_cache *cache = &rc->backref_cache;
2819         struct backref_node *node;
2820         int level;
2821         int ret;
2822
2823         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2824                 while (!list_empty(&cache->pending[level])) {
2825                         node = list_entry(cache->pending[level].next,
2826                                           struct backref_node, list);
2827                         list_move_tail(&node->list, &list);
2828                         BUG_ON(!node->pending);
2829
2830                         if (!err) {
2831                                 ret = link_to_upper(trans, rc, node, path);
2832                                 if (ret < 0)
2833                                         err = ret;
2834                         }
2835                 }
2836                 list_splice_init(&list, &cache->pending[level]);
2837         }
2838         return err;
2839 }
2840
2841 static void mark_block_processed(struct reloc_control *rc,
2842                                  u64 bytenr, u32 blocksize)
2843 {
2844         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2845                         EXTENT_DIRTY, GFP_NOFS);
2846 }
2847
2848 static void __mark_block_processed(struct reloc_control *rc,
2849                                    struct backref_node *node)
2850 {
2851         u32 blocksize;
2852         if (node->level == 0 ||
2853             in_block_group(node->bytenr, rc->block_group)) {
2854                 blocksize = rc->extent_root->nodesize;
2855                 mark_block_processed(rc, node->bytenr, blocksize);
2856         }
2857         node->processed = 1;
2858 }
2859
2860 /*
2861  * mark a block and all blocks directly/indirectly reference the block
2862  * as processed.
2863  */
2864 static void update_processed_blocks(struct reloc_control *rc,
2865                                     struct backref_node *node)
2866 {
2867         struct backref_node *next = node;
2868         struct backref_edge *edge;
2869         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2870         int index = 0;
2871
2872         while (next) {
2873                 cond_resched();
2874                 while (1) {
2875                         if (next->processed)
2876                                 break;
2877
2878                         __mark_block_processed(rc, next);
2879
2880                         if (list_empty(&next->upper))
2881                                 break;
2882
2883                         edge = list_entry(next->upper.next,
2884                                           struct backref_edge, list[LOWER]);
2885                         edges[index++] = edge;
2886                         next = edge->node[UPPER];
2887                 }
2888                 next = walk_down_backref(edges, &index);
2889         }
2890 }
2891
2892 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2893 {
2894         u32 blocksize = rc->extent_root->nodesize;
2895
2896         if (test_range_bit(&rc->processed_blocks, bytenr,
2897                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2898                 return 1;
2899         return 0;
2900 }
2901
2902 static int get_tree_block_key(struct reloc_control *rc,
2903                               struct tree_block *block)
2904 {
2905         struct extent_buffer *eb;
2906
2907         BUG_ON(block->key_ready);
2908         eb = read_tree_block(rc->extent_root, block->bytenr,
2909                              block->key.offset);
2910         if (IS_ERR(eb)) {
2911                 return PTR_ERR(eb);
2912         } else if (!extent_buffer_uptodate(eb)) {
2913                 free_extent_buffer(eb);
2914                 return -EIO;
2915         }
2916         WARN_ON(btrfs_header_level(eb) != block->level);
2917         if (block->level == 0)
2918                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2919         else
2920                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2921         free_extent_buffer(eb);
2922         block->key_ready = 1;
2923         return 0;
2924 }
2925
2926 /*
2927  * helper function to relocate a tree block
2928  */
2929 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2930                                 struct reloc_control *rc,
2931                                 struct backref_node *node,
2932                                 struct btrfs_key *key,
2933                                 struct btrfs_path *path)
2934 {
2935         struct btrfs_root *root;
2936         int ret = 0;
2937
2938         if (!node)
2939                 return 0;
2940
2941         BUG_ON(node->processed);
2942         root = select_one_root(node);
2943         if (root == ERR_PTR(-ENOENT)) {
2944                 update_processed_blocks(rc, node);
2945                 goto out;
2946         }
2947
2948         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2949                 ret = reserve_metadata_space(trans, rc, node);
2950                 if (ret)
2951                         goto out;
2952         }
2953
2954         if (root) {
2955                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2956                         BUG_ON(node->new_bytenr);
2957                         BUG_ON(!list_empty(&node->list));
2958                         btrfs_record_root_in_trans(trans, root);
2959                         root = root->reloc_root;
2960                         node->new_bytenr = root->node->start;
2961                         node->root = root;
2962                         list_add_tail(&node->list, &rc->backref_cache.changed);
2963                 } else {
2964                         path->lowest_level = node->level;
2965                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2966                         btrfs_release_path(path);
2967                         if (ret > 0)
2968                                 ret = 0;
2969                 }
2970                 if (!ret)
2971                         update_processed_blocks(rc, node);
2972         } else {
2973                 ret = do_relocation(trans, rc, node, key, path, 1);
2974         }
2975 out:
2976         if (ret || node->level == 0 || node->cowonly)
2977                 remove_backref_node(&rc->backref_cache, node);
2978         return ret;
2979 }
2980
2981 /*
2982  * relocate a list of blocks
2983  */
2984 static noinline_for_stack
2985 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2986                          struct reloc_control *rc, struct rb_root *blocks)
2987 {
2988         struct backref_node *node;
2989         struct btrfs_path *path;
2990         struct tree_block *block;
2991         struct rb_node *rb_node;
2992         int ret;
2993         int err = 0;
2994
2995         path = btrfs_alloc_path();
2996         if (!path) {
2997                 err = -ENOMEM;
2998                 goto out_free_blocks;
2999         }
3000
3001         rb_node = rb_first(blocks);
3002         while (rb_node) {
3003                 block = rb_entry(rb_node, struct tree_block, rb_node);
3004                 if (!block->key_ready)
3005                         readahead_tree_block(rc->extent_root, block->bytenr);
3006                 rb_node = rb_next(rb_node);
3007         }
3008
3009         rb_node = rb_first(blocks);
3010         while (rb_node) {
3011                 block = rb_entry(rb_node, struct tree_block, rb_node);
3012                 if (!block->key_ready) {
3013                         err = get_tree_block_key(rc, block);
3014                         if (err)
3015                                 goto out_free_path;
3016                 }
3017                 rb_node = rb_next(rb_node);
3018         }
3019
3020         rb_node = rb_first(blocks);
3021         while (rb_node) {
3022                 block = rb_entry(rb_node, struct tree_block, rb_node);
3023
3024                 node = build_backref_tree(rc, &block->key,
3025                                           block->level, block->bytenr);
3026                 if (IS_ERR(node)) {
3027                         err = PTR_ERR(node);
3028                         goto out;
3029                 }
3030
3031                 ret = relocate_tree_block(trans, rc, node, &block->key,
3032                                           path);
3033                 if (ret < 0) {
3034                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3035                                 err = ret;
3036                         goto out;
3037                 }
3038                 rb_node = rb_next(rb_node);
3039         }
3040 out:
3041         err = finish_pending_nodes(trans, rc, path, err);
3042
3043 out_free_path:
3044         btrfs_free_path(path);
3045 out_free_blocks:
3046         free_block_list(blocks);
3047         return err;
3048 }
3049
3050 static noinline_for_stack
3051 int prealloc_file_extent_cluster(struct inode *inode,
3052                                  struct file_extent_cluster *cluster)
3053 {
3054         u64 alloc_hint = 0;
3055         u64 start;
3056         u64 end;
3057         u64 offset = BTRFS_I(inode)->index_cnt;
3058         u64 num_bytes;
3059         int nr = 0;
3060         int ret = 0;
3061
3062         BUG_ON(cluster->start != cluster->boundary[0]);
3063         mutex_lock(&inode->i_mutex);
3064
3065         ret = btrfs_check_data_free_space(inode, cluster->start,
3066                                           cluster->end + 1 - cluster->start);
3067         if (ret)
3068                 goto out;
3069
3070         while (nr < cluster->nr) {
3071                 start = cluster->boundary[nr] - offset;
3072                 if (nr + 1 < cluster->nr)
3073                         end = cluster->boundary[nr + 1] - 1 - offset;
3074                 else
3075                         end = cluster->end - offset;
3076
3077                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3078                 num_bytes = end + 1 - start;
3079                 ret = btrfs_prealloc_file_range(inode, 0, start,
3080                                                 num_bytes, num_bytes,
3081                                                 end + 1, &alloc_hint);
3082                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3083                 if (ret)
3084                         break;
3085                 nr++;
3086         }
3087         btrfs_free_reserved_data_space(inode, cluster->start,
3088                                        cluster->end + 1 - cluster->start);
3089 out:
3090         mutex_unlock(&inode->i_mutex);
3091         return ret;
3092 }
3093
3094 static noinline_for_stack
3095 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3096                          u64 block_start)
3097 {
3098         struct btrfs_root *root = BTRFS_I(inode)->root;
3099         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3100         struct extent_map *em;
3101         int ret = 0;
3102
3103         em = alloc_extent_map();
3104         if (!em)
3105                 return -ENOMEM;
3106
3107         em->start = start;
3108         em->len = end + 1 - start;
3109         em->block_len = em->len;
3110         em->block_start = block_start;
3111         em->bdev = root->fs_info->fs_devices->latest_bdev;
3112         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3113
3114         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3115         while (1) {
3116                 write_lock(&em_tree->lock);
3117                 ret = add_extent_mapping(em_tree, em, 0);
3118                 write_unlock(&em_tree->lock);
3119                 if (ret != -EEXIST) {
3120                         free_extent_map(em);
3121                         break;
3122                 }
3123                 btrfs_drop_extent_cache(inode, start, end, 0);
3124         }
3125         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3126         return ret;
3127 }
3128
3129 static int relocate_file_extent_cluster(struct inode *inode,
3130                                         struct file_extent_cluster *cluster)
3131 {
3132         u64 page_start;
3133         u64 page_end;
3134         u64 offset = BTRFS_I(inode)->index_cnt;
3135         unsigned long index;
3136         unsigned long last_index;
3137         struct page *page;
3138         struct file_ra_state *ra;
3139         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3140         int nr = 0;
3141         int ret = 0;
3142
3143         if (!cluster->nr)
3144                 return 0;
3145
3146         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3147         if (!ra)
3148                 return -ENOMEM;
3149
3150         ret = prealloc_file_extent_cluster(inode, cluster);
3151         if (ret)
3152                 goto out;
3153
3154         file_ra_state_init(ra, inode->i_mapping);
3155
3156         ret = setup_extent_mapping(inode, cluster->start - offset,
3157                                    cluster->end - offset, cluster->start);
3158         if (ret)
3159                 goto out;
3160
3161         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3162         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3163         while (index <= last_index) {
3164                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3165                 if (ret)
3166                         goto out;
3167
3168                 page = find_lock_page(inode->i_mapping, index);
3169                 if (!page) {
3170                         page_cache_sync_readahead(inode->i_mapping,
3171                                                   ra, NULL, index,
3172                                                   last_index + 1 - index);
3173                         page = find_or_create_page(inode->i_mapping, index,
3174                                                    mask);
3175                         if (!page) {
3176                                 btrfs_delalloc_release_metadata(inode,
3177                                                         PAGE_CACHE_SIZE);
3178                                 ret = -ENOMEM;
3179                                 goto out;
3180                         }
3181                 }
3182
3183                 if (PageReadahead(page)) {
3184                         page_cache_async_readahead(inode->i_mapping,
3185                                                    ra, NULL, page, index,
3186                                                    last_index + 1 - index);
3187                 }
3188
3189                 if (!PageUptodate(page)) {
3190                         btrfs_readpage(NULL, page);
3191                         lock_page(page);
3192                         if (!PageUptodate(page)) {
3193                                 unlock_page(page);
3194                                 page_cache_release(page);
3195                                 btrfs_delalloc_release_metadata(inode,
3196                                                         PAGE_CACHE_SIZE);
3197                                 ret = -EIO;
3198                                 goto out;
3199                         }
3200                 }
3201
3202                 page_start = page_offset(page);
3203                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3204
3205                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3206
3207                 set_page_extent_mapped(page);
3208
3209                 if (nr < cluster->nr &&
3210                     page_start + offset == cluster->boundary[nr]) {
3211                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3212                                         page_start, page_end,
3213                                         EXTENT_BOUNDARY, GFP_NOFS);
3214                         nr++;
3215                 }
3216
3217                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3218                 set_page_dirty(page);
3219
3220                 unlock_extent(&BTRFS_I(inode)->io_tree,
3221                               page_start, page_end);
3222                 unlock_page(page);
3223                 page_cache_release(page);
3224
3225                 index++;
3226                 balance_dirty_pages_ratelimited(inode->i_mapping);
3227                 btrfs_throttle(BTRFS_I(inode)->root);
3228         }
3229         WARN_ON(nr != cluster->nr);
3230 out:
3231         kfree(ra);
3232         return ret;
3233 }
3234
3235 static noinline_for_stack
3236 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3237                          struct file_extent_cluster *cluster)
3238 {
3239         int ret;
3240
3241         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3242                 ret = relocate_file_extent_cluster(inode, cluster);
3243                 if (ret)
3244                         return ret;
3245                 cluster->nr = 0;
3246         }
3247
3248         if (!cluster->nr)
3249                 cluster->start = extent_key->objectid;
3250         else
3251                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3252         cluster->end = extent_key->objectid + extent_key->offset - 1;
3253         cluster->boundary[cluster->nr] = extent_key->objectid;
3254         cluster->nr++;
3255
3256         if (cluster->nr >= MAX_EXTENTS) {
3257                 ret = relocate_file_extent_cluster(inode, cluster);
3258                 if (ret)
3259                         return ret;
3260                 cluster->nr = 0;
3261         }
3262         return 0;
3263 }
3264
3265 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3266 static int get_ref_objectid_v0(struct reloc_control *rc,
3267                                struct btrfs_path *path,
3268                                struct btrfs_key *extent_key,
3269                                u64 *ref_objectid, int *path_change)
3270 {
3271         struct btrfs_key key;
3272         struct extent_buffer *leaf;
3273         struct btrfs_extent_ref_v0 *ref0;
3274         int ret;
3275         int slot;
3276
3277         leaf = path->nodes[0];
3278         slot = path->slots[0];
3279         while (1) {
3280                 if (slot >= btrfs_header_nritems(leaf)) {
3281                         ret = btrfs_next_leaf(rc->extent_root, path);
3282                         if (ret < 0)
3283                                 return ret;
3284                         BUG_ON(ret > 0);
3285                         leaf = path->nodes[0];
3286                         slot = path->slots[0];
3287                         if (path_change)
3288                                 *path_change = 1;
3289                 }
3290                 btrfs_item_key_to_cpu(leaf, &key, slot);
3291                 if (key.objectid != extent_key->objectid)
3292                         return -ENOENT;
3293
3294                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3295                         slot++;
3296                         continue;
3297                 }
3298                 ref0 = btrfs_item_ptr(leaf, slot,
3299                                 struct btrfs_extent_ref_v0);
3300                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3301                 break;
3302         }
3303         return 0;
3304 }
3305 #endif
3306
3307 /*
3308  * helper to add a tree block to the list.
3309  * the major work is getting the generation and level of the block
3310  */
3311 static int add_tree_block(struct reloc_control *rc,
3312                           struct btrfs_key *extent_key,
3313                           struct btrfs_path *path,
3314                           struct rb_root *blocks)
3315 {
3316         struct extent_buffer *eb;
3317         struct btrfs_extent_item *ei;
3318         struct btrfs_tree_block_info *bi;
3319         struct tree_block *block;
3320         struct rb_node *rb_node;
3321         u32 item_size;
3322         int level = -1;
3323         u64 generation;
3324
3325         eb =  path->nodes[0];
3326         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3327
3328         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3329             item_size >= sizeof(*ei) + sizeof(*bi)) {
3330                 ei = btrfs_item_ptr(eb, path->slots[0],
3331                                 struct btrfs_extent_item);
3332                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3333                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3334                         level = btrfs_tree_block_level(eb, bi);
3335                 } else {
3336                         level = (int)extent_key->offset;
3337                 }
3338                 generation = btrfs_extent_generation(eb, ei);
3339         } else {
3340 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3341                 u64 ref_owner;
3342                 int ret;
3343
3344                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3345                 ret = get_ref_objectid_v0(rc, path, extent_key,
3346                                           &ref_owner, NULL);
3347                 if (ret < 0)
3348                         return ret;
3349                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3350                 level = (int)ref_owner;
3351                 /* FIXME: get real generation */
3352                 generation = 0;
3353 #else
3354                 BUG();
3355 #endif
3356         }
3357
3358         btrfs_release_path(path);
3359
3360         BUG_ON(level == -1);
3361
3362         block = kmalloc(sizeof(*block), GFP_NOFS);
3363         if (!block)
3364                 return -ENOMEM;
3365
3366         block->bytenr = extent_key->objectid;
3367         block->key.objectid = rc->extent_root->nodesize;
3368         block->key.offset = generation;
3369         block->level = level;
3370         block->key_ready = 0;
3371
3372         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3373         if (rb_node)
3374                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3375
3376         return 0;
3377 }
3378
3379 /*
3380  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3381  */
3382 static int __add_tree_block(struct reloc_control *rc,
3383                             u64 bytenr, u32 blocksize,
3384                             struct rb_root *blocks)
3385 {
3386         struct btrfs_path *path;
3387         struct btrfs_key key;
3388         int ret;
3389         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3390                                         SKINNY_METADATA);
3391
3392         if (tree_block_processed(bytenr, rc))
3393                 return 0;
3394
3395         if (tree_search(blocks, bytenr))
3396                 return 0;
3397
3398         path = btrfs_alloc_path();
3399         if (!path)
3400                 return -ENOMEM;
3401 again:
3402         key.objectid = bytenr;
3403         if (skinny) {
3404                 key.type = BTRFS_METADATA_ITEM_KEY;
3405                 key.offset = (u64)-1;
3406         } else {
3407                 key.type = BTRFS_EXTENT_ITEM_KEY;
3408                 key.offset = blocksize;
3409         }
3410
3411         path->search_commit_root = 1;
3412         path->skip_locking = 1;
3413         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3414         if (ret < 0)
3415                 goto out;
3416
3417         if (ret > 0 && skinny) {
3418                 if (path->slots[0]) {
3419                         path->slots[0]--;
3420                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3421                                               path->slots[0]);
3422                         if (key.objectid == bytenr &&
3423                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3424                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3425                               key.offset == blocksize)))
3426                                 ret = 0;
3427                 }
3428
3429                 if (ret) {
3430                         skinny = false;
3431                         btrfs_release_path(path);
3432                         goto again;
3433                 }
3434         }
3435         BUG_ON(ret);
3436
3437         ret = add_tree_block(rc, &key, path, blocks);
3438 out:
3439         btrfs_free_path(path);
3440         return ret;
3441 }
3442
3443 /*
3444  * helper to check if the block use full backrefs for pointers in it
3445  */
3446 static int block_use_full_backref(struct reloc_control *rc,
3447                                   struct extent_buffer *eb)
3448 {
3449         u64 flags;
3450         int ret;
3451
3452         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3453             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3454                 return 1;
3455
3456         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3457                                        eb->start, btrfs_header_level(eb), 1,
3458                                        NULL, &flags);
3459         BUG_ON(ret);
3460
3461         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3462                 ret = 1;
3463         else
3464                 ret = 0;
3465         return ret;
3466 }
3467
3468 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3469                                     struct btrfs_block_group_cache *block_group,
3470                                     struct inode *inode,
3471                                     u64 ino)
3472 {
3473         struct btrfs_key key;
3474         struct btrfs_root *root = fs_info->tree_root;
3475         struct btrfs_trans_handle *trans;
3476         int ret = 0;
3477
3478         if (inode)
3479                 goto truncate;
3480
3481         key.objectid = ino;
3482         key.type = BTRFS_INODE_ITEM_KEY;
3483         key.offset = 0;
3484
3485         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3486         if (IS_ERR(inode) || is_bad_inode(inode)) {
3487                 if (!IS_ERR(inode))
3488                         iput(inode);
3489                 return -ENOENT;
3490         }
3491
3492 truncate:
3493         ret = btrfs_check_trunc_cache_free_space(root,
3494                                                  &fs_info->global_block_rsv);
3495         if (ret)
3496                 goto out;
3497
3498         trans = btrfs_join_transaction(root);
3499         if (IS_ERR(trans)) {
3500                 ret = PTR_ERR(trans);
3501                 goto out;
3502         }
3503
3504         ret = btrfs_truncate_free_space_cache(root, trans, block_group, inode);
3505
3506         btrfs_end_transaction(trans, root);
3507         btrfs_btree_balance_dirty(root);
3508 out:
3509         iput(inode);
3510         return ret;
3511 }
3512
3513 /*
3514  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3515  * this function scans fs tree to find blocks reference the data extent
3516  */
3517 static int find_data_references(struct reloc_control *rc,
3518                                 struct btrfs_key *extent_key,
3519                                 struct extent_buffer *leaf,
3520                                 struct btrfs_extent_data_ref *ref,
3521                                 struct rb_root *blocks)
3522 {
3523         struct btrfs_path *path;
3524         struct tree_block *block;
3525         struct btrfs_root *root;
3526         struct btrfs_file_extent_item *fi;
3527         struct rb_node *rb_node;
3528         struct btrfs_key key;
3529         u64 ref_root;
3530         u64 ref_objectid;
3531         u64 ref_offset;
3532         u32 ref_count;
3533         u32 nritems;
3534         int err = 0;
3535         int added = 0;
3536         int counted;
3537         int ret;
3538
3539         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3540         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3541         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3542         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3543
3544         /*
3545          * This is an extent belonging to the free space cache, lets just delete
3546          * it and redo the search.
3547          */
3548         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3549                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3550                                                rc->block_group,
3551                                                NULL, ref_objectid);
3552                 if (ret != -ENOENT)
3553                         return ret;
3554                 ret = 0;
3555         }
3556
3557         path = btrfs_alloc_path();
3558         if (!path)
3559                 return -ENOMEM;
3560         path->reada = 1;
3561
3562         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3563         if (IS_ERR(root)) {
3564                 err = PTR_ERR(root);
3565                 goto out;
3566         }
3567
3568         key.objectid = ref_objectid;
3569         key.type = BTRFS_EXTENT_DATA_KEY;
3570         if (ref_offset > ((u64)-1 << 32))
3571                 key.offset = 0;
3572         else
3573                 key.offset = ref_offset;
3574
3575         path->search_commit_root = 1;
3576         path->skip_locking = 1;
3577         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3578         if (ret < 0) {
3579                 err = ret;
3580                 goto out;
3581         }
3582
3583         leaf = path->nodes[0];
3584         nritems = btrfs_header_nritems(leaf);
3585         /*
3586          * the references in tree blocks that use full backrefs
3587          * are not counted in
3588          */
3589         if (block_use_full_backref(rc, leaf))
3590                 counted = 0;
3591         else
3592                 counted = 1;
3593         rb_node = tree_search(blocks, leaf->start);
3594         if (rb_node) {
3595                 if (counted)
3596                         added = 1;
3597                 else
3598                         path->slots[0] = nritems;
3599         }
3600
3601         while (ref_count > 0) {
3602                 while (path->slots[0] >= nritems) {
3603                         ret = btrfs_next_leaf(root, path);
3604                         if (ret < 0) {
3605                                 err = ret;
3606                                 goto out;
3607                         }
3608                         if (WARN_ON(ret > 0))
3609                                 goto out;
3610
3611                         leaf = path->nodes[0];
3612                         nritems = btrfs_header_nritems(leaf);
3613                         added = 0;
3614
3615                         if (block_use_full_backref(rc, leaf))
3616                                 counted = 0;
3617                         else
3618                                 counted = 1;
3619                         rb_node = tree_search(blocks, leaf->start);
3620                         if (rb_node) {
3621                                 if (counted)
3622                                         added = 1;
3623                                 else
3624                                         path->slots[0] = nritems;
3625                         }
3626                 }
3627
3628                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3629                 if (WARN_ON(key.objectid != ref_objectid ||
3630                     key.type != BTRFS_EXTENT_DATA_KEY))
3631                         break;
3632
3633                 fi = btrfs_item_ptr(leaf, path->slots[0],
3634                                     struct btrfs_file_extent_item);
3635
3636                 if (btrfs_file_extent_type(leaf, fi) ==
3637                     BTRFS_FILE_EXTENT_INLINE)
3638                         goto next;
3639
3640                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3641                     extent_key->objectid)
3642                         goto next;
3643
3644                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3645                 if (key.offset != ref_offset)
3646                         goto next;
3647
3648                 if (counted)
3649                         ref_count--;
3650                 if (added)
3651                         goto next;
3652
3653                 if (!tree_block_processed(leaf->start, rc)) {
3654                         block = kmalloc(sizeof(*block), GFP_NOFS);
3655                         if (!block) {
3656                                 err = -ENOMEM;
3657                                 break;
3658                         }
3659                         block->bytenr = leaf->start;
3660                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3661                         block->level = 0;
3662                         block->key_ready = 1;
3663                         rb_node = tree_insert(blocks, block->bytenr,
3664                                               &block->rb_node);
3665                         if (rb_node)
3666                                 backref_tree_panic(rb_node, -EEXIST,
3667                                                    block->bytenr);
3668                 }
3669                 if (counted)
3670                         added = 1;
3671                 else
3672                         path->slots[0] = nritems;
3673 next:
3674                 path->slots[0]++;
3675
3676         }
3677 out:
3678         btrfs_free_path(path);
3679         return err;
3680 }
3681
3682 /*
3683  * helper to find all tree blocks that reference a given data extent
3684  */
3685 static noinline_for_stack
3686 int add_data_references(struct reloc_control *rc,
3687                         struct btrfs_key *extent_key,
3688                         struct btrfs_path *path,
3689                         struct rb_root *blocks)
3690 {
3691         struct btrfs_key key;
3692         struct extent_buffer *eb;
3693         struct btrfs_extent_data_ref *dref;
3694         struct btrfs_extent_inline_ref *iref;
3695         unsigned long ptr;
3696         unsigned long end;
3697         u32 blocksize = rc->extent_root->nodesize;
3698         int ret = 0;
3699         int err = 0;
3700
3701         eb = path->nodes[0];
3702         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3703         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3704 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3705         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3706                 ptr = end;
3707         else
3708 #endif
3709                 ptr += sizeof(struct btrfs_extent_item);
3710
3711         while (ptr < end) {
3712                 iref = (struct btrfs_extent_inline_ref *)ptr;
3713                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3714                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3715                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3716                         ret = __add_tree_block(rc, key.offset, blocksize,
3717                                                blocks);
3718                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3719                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3720                         ret = find_data_references(rc, extent_key,
3721                                                    eb, dref, blocks);
3722                 } else {
3723                         BUG();
3724                 }
3725                 if (ret) {
3726                         err = ret;
3727                         goto out;
3728                 }
3729                 ptr += btrfs_extent_inline_ref_size(key.type);
3730         }
3731         WARN_ON(ptr > end);
3732
3733         while (1) {
3734                 cond_resched();
3735                 eb = path->nodes[0];
3736                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3737                         ret = btrfs_next_leaf(rc->extent_root, path);
3738                         if (ret < 0) {
3739                                 err = ret;
3740                                 break;
3741                         }
3742                         if (ret > 0)
3743                                 break;
3744                         eb = path->nodes[0];
3745                 }
3746
3747                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3748                 if (key.objectid != extent_key->objectid)
3749                         break;
3750
3751 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3752                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3753                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3754 #else
3755                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3756                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3757 #endif
3758                         ret = __add_tree_block(rc, key.offset, blocksize,
3759                                                blocks);
3760                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3761                         dref = btrfs_item_ptr(eb, path->slots[0],
3762                                               struct btrfs_extent_data_ref);
3763                         ret = find_data_references(rc, extent_key,
3764                                                    eb, dref, blocks);
3765                 } else {
3766                         ret = 0;
3767                 }
3768                 if (ret) {
3769                         err = ret;
3770                         break;
3771                 }
3772                 path->slots[0]++;
3773         }
3774 out:
3775         btrfs_release_path(path);
3776         if (err)
3777                 free_block_list(blocks);
3778         return err;
3779 }
3780
3781 /*
3782  * helper to find next unprocessed extent
3783  */
3784 static noinline_for_stack
3785 int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
3786                      struct btrfs_key *extent_key)
3787 {
3788         struct btrfs_key key;
3789         struct extent_buffer *leaf;
3790         u64 start, end, last;
3791         int ret;
3792
3793         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3794         while (1) {
3795                 cond_resched();
3796                 if (rc->search_start >= last) {
3797                         ret = 1;
3798                         break;
3799                 }
3800
3801                 key.objectid = rc->search_start;
3802                 key.type = BTRFS_EXTENT_ITEM_KEY;
3803                 key.offset = 0;
3804
3805                 path->search_commit_root = 1;
3806                 path->skip_locking = 1;
3807                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3808                                         0, 0);
3809                 if (ret < 0)
3810                         break;
3811 next:
3812                 leaf = path->nodes[0];
3813                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3814                         ret = btrfs_next_leaf(rc->extent_root, path);
3815                         if (ret != 0)
3816                                 break;
3817                         leaf = path->nodes[0];
3818                 }
3819
3820                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3821                 if (key.objectid >= last) {
3822                         ret = 1;
3823                         break;
3824                 }
3825
3826                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3827                     key.type != BTRFS_METADATA_ITEM_KEY) {
3828                         path->slots[0]++;
3829                         goto next;
3830                 }
3831
3832                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3833                     key.objectid + key.offset <= rc->search_start) {
3834                         path->slots[0]++;
3835                         goto next;
3836                 }
3837
3838                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3839                     key.objectid + rc->extent_root->nodesize <=
3840                     rc->search_start) {
3841                         path->slots[0]++;
3842                         goto next;
3843                 }
3844
3845                 ret = find_first_extent_bit(&rc->processed_blocks,
3846                                             key.objectid, &start, &end,
3847                                             EXTENT_DIRTY, NULL);
3848
3849                 if (ret == 0 && start <= key.objectid) {
3850                         btrfs_release_path(path);
3851                         rc->search_start = end + 1;
3852                 } else {
3853                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3854                                 rc->search_start = key.objectid + key.offset;
3855                         else
3856                                 rc->search_start = key.objectid +
3857                                         rc->extent_root->nodesize;
3858                         memcpy(extent_key, &key, sizeof(key));
3859                         return 0;
3860                 }
3861         }
3862         btrfs_release_path(path);
3863         return ret;
3864 }
3865
3866 static void set_reloc_control(struct reloc_control *rc)
3867 {
3868         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3869
3870         mutex_lock(&fs_info->reloc_mutex);
3871         fs_info->reloc_ctl = rc;
3872         mutex_unlock(&fs_info->reloc_mutex);
3873 }
3874
3875 static void unset_reloc_control(struct reloc_control *rc)
3876 {
3877         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3878
3879         mutex_lock(&fs_info->reloc_mutex);
3880         fs_info->reloc_ctl = NULL;
3881         mutex_unlock(&fs_info->reloc_mutex);
3882 }
3883
3884 static int check_extent_flags(u64 flags)
3885 {
3886         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3887             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3888                 return 1;
3889         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3890             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3891                 return 1;
3892         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3893             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3894                 return 1;
3895         return 0;
3896 }
3897
3898 static noinline_for_stack
3899 int prepare_to_relocate(struct reloc_control *rc)
3900 {
3901         struct btrfs_trans_handle *trans;
3902
3903         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3904                                               BTRFS_BLOCK_RSV_TEMP);
3905         if (!rc->block_rsv)
3906                 return -ENOMEM;
3907
3908         memset(&rc->cluster, 0, sizeof(rc->cluster));
3909         rc->search_start = rc->block_group->key.objectid;
3910         rc->extents_found = 0;
3911         rc->nodes_relocated = 0;
3912         rc->merging_rsv_size = 0;
3913         rc->reserved_bytes = 0;
3914         rc->block_rsv->size = rc->extent_root->nodesize *
3915                               RELOCATION_RESERVED_NODES;
3916
3917         rc->create_reloc_tree = 1;
3918         set_reloc_control(rc);
3919
3920         trans = btrfs_join_transaction(rc->extent_root);
3921         if (IS_ERR(trans)) {
3922                 unset_reloc_control(rc);
3923                 /*
3924                  * extent tree is not a ref_cow tree and has no reloc_root to
3925                  * cleanup.  And callers are responsible to free the above
3926                  * block rsv.
3927                  */
3928                 return PTR_ERR(trans);
3929         }
3930         btrfs_commit_transaction(trans, rc->extent_root);
3931         return 0;
3932 }
3933
3934 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3935 {
3936         struct rb_root blocks = RB_ROOT;
3937         struct btrfs_key key;
3938         struct btrfs_trans_handle *trans = NULL;
3939         struct btrfs_path *path;
3940         struct btrfs_extent_item *ei;
3941         u64 flags;
3942         u32 item_size;
3943         int ret;
3944         int err = 0;
3945         int progress = 0;
3946
3947         path = btrfs_alloc_path();
3948         if (!path)
3949                 return -ENOMEM;
3950         path->reada = 1;
3951
3952         ret = prepare_to_relocate(rc);
3953         if (ret) {
3954                 err = ret;
3955                 goto out_free;
3956         }
3957
3958         while (1) {
3959                 rc->reserved_bytes = 0;
3960                 ret = btrfs_block_rsv_refill(rc->extent_root,
3961                                         rc->block_rsv, rc->block_rsv->size,
3962                                         BTRFS_RESERVE_FLUSH_ALL);
3963                 if (ret) {
3964                         err = ret;
3965                         break;
3966                 }
3967                 progress++;
3968                 trans = btrfs_start_transaction(rc->extent_root, 0);
3969                 if (IS_ERR(trans)) {
3970                         err = PTR_ERR(trans);
3971                         trans = NULL;
3972                         break;
3973                 }
3974 restart:
3975                 if (update_backref_cache(trans, &rc->backref_cache)) {
3976                         btrfs_end_transaction(trans, rc->extent_root);
3977                         continue;
3978                 }
3979
3980                 ret = find_next_extent(rc, path, &key);
3981                 if (ret < 0)
3982                         err = ret;
3983                 if (ret != 0)
3984                         break;
3985
3986                 rc->extents_found++;
3987
3988                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3989                                     struct btrfs_extent_item);
3990                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3991                 if (item_size >= sizeof(*ei)) {
3992                         flags = btrfs_extent_flags(path->nodes[0], ei);
3993                         ret = check_extent_flags(flags);
3994                         BUG_ON(ret);
3995
3996                 } else {
3997 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3998                         u64 ref_owner;
3999                         int path_change = 0;
4000
4001                         BUG_ON(item_size !=
4002                                sizeof(struct btrfs_extent_item_v0));
4003                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
4004                                                   &path_change);
4005                         if (ret < 0) {
4006                                 err = ret;
4007                                 break;
4008                         }
4009                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
4010                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
4011                         else
4012                                 flags = BTRFS_EXTENT_FLAG_DATA;
4013
4014                         if (path_change) {
4015                                 btrfs_release_path(path);
4016
4017                                 path->search_commit_root = 1;
4018                                 path->skip_locking = 1;
4019                                 ret = btrfs_search_slot(NULL, rc->extent_root,
4020                                                         &key, path, 0, 0);
4021                                 if (ret < 0) {
4022                                         err = ret;
4023                                         break;
4024                                 }
4025                                 BUG_ON(ret > 0);
4026                         }
4027 #else
4028                         BUG();
4029 #endif
4030                 }
4031
4032                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4033                         ret = add_tree_block(rc, &key, path, &blocks);
4034                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4035                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4036                         ret = add_data_references(rc, &key, path, &blocks);
4037                 } else {
4038                         btrfs_release_path(path);
4039                         ret = 0;
4040                 }
4041                 if (ret < 0) {
4042                         err = ret;
4043                         break;
4044                 }
4045
4046                 if (!RB_EMPTY_ROOT(&blocks)) {
4047                         ret = relocate_tree_blocks(trans, rc, &blocks);
4048                         if (ret < 0) {
4049                                 /*
4050                                  * if we fail to relocate tree blocks, force to update
4051                                  * backref cache when committing transaction.
4052                                  */
4053                                 rc->backref_cache.last_trans = trans->transid - 1;
4054
4055                                 if (ret != -EAGAIN) {
4056                                         err = ret;
4057                                         break;
4058                                 }
4059                                 rc->extents_found--;
4060                                 rc->search_start = key.objectid;
4061                         }
4062                 }
4063
4064                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4065                 btrfs_btree_balance_dirty(rc->extent_root);
4066                 trans = NULL;
4067
4068                 if (rc->stage == MOVE_DATA_EXTENTS &&
4069                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4070                         rc->found_file_extent = 1;
4071                         ret = relocate_data_extent(rc->data_inode,
4072                                                    &key, &rc->cluster);
4073                         if (ret < 0) {
4074                                 err = ret;
4075                                 break;
4076                         }
4077                 }
4078         }
4079         if (trans && progress && err == -ENOSPC) {
4080                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4081                                               rc->block_group->flags);
4082                 if (ret == 1) {
4083                         err = 0;
4084                         progress = 0;
4085                         goto restart;
4086                 }
4087         }
4088
4089         btrfs_release_path(path);
4090         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4091                           GFP_NOFS);
4092
4093         if (trans) {
4094                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4095                 btrfs_btree_balance_dirty(rc->extent_root);
4096         }
4097
4098         if (!err) {
4099                 ret = relocate_file_extent_cluster(rc->data_inode,
4100                                                    &rc->cluster);
4101                 if (ret < 0)
4102                         err = ret;
4103         }
4104
4105         rc->create_reloc_tree = 0;
4106         set_reloc_control(rc);
4107
4108         backref_cache_cleanup(&rc->backref_cache);
4109         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4110
4111         err = prepare_to_merge(rc, err);
4112
4113         merge_reloc_roots(rc);
4114
4115         rc->merge_reloc_tree = 0;
4116         unset_reloc_control(rc);
4117         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4118
4119         /* get rid of pinned extents */
4120         trans = btrfs_join_transaction(rc->extent_root);
4121         if (IS_ERR(trans))
4122                 err = PTR_ERR(trans);
4123         else
4124                 btrfs_commit_transaction(trans, rc->extent_root);
4125 out_free:
4126         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4127         btrfs_free_path(path);
4128         return err;
4129 }
4130
4131 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4132                                  struct btrfs_root *root, u64 objectid)
4133 {
4134         struct btrfs_path *path;
4135         struct btrfs_inode_item *item;
4136         struct extent_buffer *leaf;
4137         int ret;
4138
4139         path = btrfs_alloc_path();
4140         if (!path)
4141                 return -ENOMEM;
4142
4143         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4144         if (ret)
4145                 goto out;
4146
4147         leaf = path->nodes[0];
4148         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4149         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4150         btrfs_set_inode_generation(leaf, item, 1);
4151         btrfs_set_inode_size(leaf, item, 0);
4152         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4153         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4154                                           BTRFS_INODE_PREALLOC);
4155         btrfs_mark_buffer_dirty(leaf);
4156 out:
4157         btrfs_free_path(path);
4158         return ret;
4159 }
4160
4161 /*
4162  * helper to create inode for data relocation.
4163  * the inode is in data relocation tree and its link count is 0
4164  */
4165 static noinline_for_stack
4166 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4167                                  struct btrfs_block_group_cache *group)
4168 {
4169         struct inode *inode = NULL;
4170         struct btrfs_trans_handle *trans;
4171         struct btrfs_root *root;
4172         struct btrfs_key key;
4173         u64 objectid;
4174         int err = 0;
4175
4176         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4177         if (IS_ERR(root))
4178                 return ERR_CAST(root);
4179
4180         trans = btrfs_start_transaction(root, 6);
4181         if (IS_ERR(trans))
4182                 return ERR_CAST(trans);
4183
4184         err = btrfs_find_free_objectid(root, &objectid);
4185         if (err)
4186                 goto out;
4187
4188         err = __insert_orphan_inode(trans, root, objectid);
4189         BUG_ON(err);
4190
4191         key.objectid = objectid;
4192         key.type = BTRFS_INODE_ITEM_KEY;
4193         key.offset = 0;
4194         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4195         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4196         BTRFS_I(inode)->index_cnt = group->key.objectid;
4197
4198         err = btrfs_orphan_add(trans, inode);
4199 out:
4200         btrfs_end_transaction(trans, root);
4201         btrfs_btree_balance_dirty(root);
4202         if (err) {
4203                 if (inode)
4204                         iput(inode);
4205                 inode = ERR_PTR(err);
4206         }
4207         return inode;
4208 }
4209
4210 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4211 {
4212         struct reloc_control *rc;
4213
4214         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4215         if (!rc)
4216                 return NULL;
4217
4218         INIT_LIST_HEAD(&rc->reloc_roots);
4219         backref_cache_init(&rc->backref_cache);
4220         mapping_tree_init(&rc->reloc_root_tree);
4221         extent_io_tree_init(&rc->processed_blocks,
4222                             fs_info->btree_inode->i_mapping);
4223         return rc;
4224 }
4225
4226 /*
4227  * function to relocate all extents in a block group.
4228  */
4229 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4230 {
4231         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4232         struct reloc_control *rc;
4233         struct inode *inode;
4234         struct btrfs_path *path;
4235         int ret;
4236         int rw = 0;
4237         int err = 0;
4238
4239         rc = alloc_reloc_control(fs_info);
4240         if (!rc)
4241                 return -ENOMEM;
4242
4243         rc->extent_root = extent_root;
4244
4245         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4246         BUG_ON(!rc->block_group);
4247
4248         ret = btrfs_inc_block_group_ro(extent_root, rc->block_group);
4249         if (ret) {
4250                 err = ret;
4251                 goto out;
4252         }
4253         rw = 1;
4254
4255         path = btrfs_alloc_path();
4256         if (!path) {
4257                 err = -ENOMEM;
4258                 goto out;
4259         }
4260
4261         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4262                                         path);
4263         btrfs_free_path(path);
4264
4265         if (!IS_ERR(inode))
4266                 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4267         else
4268                 ret = PTR_ERR(inode);
4269
4270         if (ret && ret != -ENOENT) {
4271                 err = ret;
4272                 goto out;
4273         }
4274
4275         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4276         if (IS_ERR(rc->data_inode)) {
4277                 err = PTR_ERR(rc->data_inode);
4278                 rc->data_inode = NULL;
4279                 goto out;
4280         }
4281
4282         btrfs_info(extent_root->fs_info, "relocating block group %llu flags %llu",
4283                rc->block_group->key.objectid, rc->block_group->flags);
4284
4285         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
4286         if (ret < 0) {
4287                 err = ret;
4288                 goto out;
4289         }
4290         btrfs_wait_ordered_roots(fs_info, -1);
4291
4292         while (1) {
4293                 mutex_lock(&fs_info->cleaner_mutex);
4294                 ret = relocate_block_group(rc);
4295                 mutex_unlock(&fs_info->cleaner_mutex);
4296                 if (ret < 0) {
4297                         err = ret;
4298                         goto out;
4299                 }
4300
4301                 if (rc->extents_found == 0)
4302                         break;
4303
4304                 btrfs_info(extent_root->fs_info, "found %llu extents",
4305                         rc->extents_found);
4306
4307                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4308                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4309                                                        (u64)-1);
4310                         if (ret) {
4311                                 err = ret;
4312                                 goto out;
4313                         }
4314                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4315                                                  0, -1);
4316                         rc->stage = UPDATE_DATA_PTRS;
4317                 }
4318         }
4319
4320         WARN_ON(rc->block_group->pinned > 0);
4321         WARN_ON(rc->block_group->reserved > 0);
4322         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4323 out:
4324         if (err && rw)
4325                 btrfs_dec_block_group_ro(extent_root, rc->block_group);
4326         iput(rc->data_inode);
4327         btrfs_put_block_group(rc->block_group);
4328         kfree(rc);
4329         return err;
4330 }
4331
4332 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4333 {
4334         struct btrfs_trans_handle *trans;
4335         int ret, err;
4336
4337         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4338         if (IS_ERR(trans))
4339                 return PTR_ERR(trans);
4340
4341         memset(&root->root_item.drop_progress, 0,
4342                 sizeof(root->root_item.drop_progress));
4343         root->root_item.drop_level = 0;
4344         btrfs_set_root_refs(&root->root_item, 0);
4345         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4346                                 &root->root_key, &root->root_item);
4347
4348         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4349         if (err)
4350                 return err;
4351         return ret;
4352 }
4353
4354 /*
4355  * recover relocation interrupted by system crash.
4356  *
4357  * this function resumes merging reloc trees with corresponding fs trees.
4358  * this is important for keeping the sharing of tree blocks
4359  */
4360 int btrfs_recover_relocation(struct btrfs_root *root)
4361 {
4362         LIST_HEAD(reloc_roots);
4363         struct btrfs_key key;
4364         struct btrfs_root *fs_root;
4365         struct btrfs_root *reloc_root;
4366         struct btrfs_path *path;
4367         struct extent_buffer *leaf;
4368         struct reloc_control *rc = NULL;
4369         struct btrfs_trans_handle *trans;
4370         int ret;
4371         int err = 0;
4372
4373         path = btrfs_alloc_path();
4374         if (!path)
4375                 return -ENOMEM;
4376         path->reada = -1;
4377
4378         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4379         key.type = BTRFS_ROOT_ITEM_KEY;
4380         key.offset = (u64)-1;
4381
4382         while (1) {
4383                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4384                                         path, 0, 0);
4385                 if (ret < 0) {
4386                         err = ret;
4387                         goto out;
4388                 }
4389                 if (ret > 0) {
4390                         if (path->slots[0] == 0)
4391                                 break;
4392                         path->slots[0]--;
4393                 }
4394                 leaf = path->nodes[0];
4395                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4396                 btrfs_release_path(path);
4397
4398                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4399                     key.type != BTRFS_ROOT_ITEM_KEY)
4400                         break;
4401
4402                 reloc_root = btrfs_read_fs_root(root, &key);
4403                 if (IS_ERR(reloc_root)) {
4404                         err = PTR_ERR(reloc_root);
4405                         goto out;
4406                 }
4407
4408                 list_add(&reloc_root->root_list, &reloc_roots);
4409
4410                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4411                         fs_root = read_fs_root(root->fs_info,
4412                                                reloc_root->root_key.offset);
4413                         if (IS_ERR(fs_root)) {
4414                                 ret = PTR_ERR(fs_root);
4415                                 if (ret != -ENOENT) {
4416                                         err = ret;
4417                                         goto out;
4418                                 }
4419                                 ret = mark_garbage_root(reloc_root);
4420                                 if (ret < 0) {
4421                                         err = ret;
4422                                         goto out;
4423                                 }
4424                         }
4425                 }
4426
4427                 if (key.offset == 0)
4428                         break;
4429
4430                 key.offset--;
4431         }
4432         btrfs_release_path(path);
4433
4434         if (list_empty(&reloc_roots))
4435                 goto out;
4436
4437         rc = alloc_reloc_control(root->fs_info);
4438         if (!rc) {
4439                 err = -ENOMEM;
4440                 goto out;
4441         }
4442
4443         rc->extent_root = root->fs_info->extent_root;
4444
4445         set_reloc_control(rc);
4446
4447         trans = btrfs_join_transaction(rc->extent_root);
4448         if (IS_ERR(trans)) {
4449                 unset_reloc_control(rc);
4450                 err = PTR_ERR(trans);
4451                 goto out_free;
4452         }
4453
4454         rc->merge_reloc_tree = 1;
4455
4456         while (!list_empty(&reloc_roots)) {
4457                 reloc_root = list_entry(reloc_roots.next,
4458                                         struct btrfs_root, root_list);
4459                 list_del(&reloc_root->root_list);
4460
4461                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4462                         list_add_tail(&reloc_root->root_list,
4463                                       &rc->reloc_roots);
4464                         continue;
4465                 }
4466
4467                 fs_root = read_fs_root(root->fs_info,
4468                                        reloc_root->root_key.offset);
4469                 if (IS_ERR(fs_root)) {
4470                         err = PTR_ERR(fs_root);
4471                         list_add_tail(&reloc_root->root_list, &reloc_roots);
4472                         goto out_free;
4473                 }
4474
4475                 err = __add_reloc_root(reloc_root);
4476                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4477                 fs_root->reloc_root = reloc_root;
4478         }
4479
4480         err = btrfs_commit_transaction(trans, rc->extent_root);
4481         if (err)
4482                 goto out_free;
4483
4484         merge_reloc_roots(rc);
4485
4486         unset_reloc_control(rc);
4487
4488         trans = btrfs_join_transaction(rc->extent_root);
4489         if (IS_ERR(trans))
4490                 err = PTR_ERR(trans);
4491         else
4492                 err = btrfs_commit_transaction(trans, rc->extent_root);
4493 out_free:
4494         kfree(rc);
4495 out:
4496         if (!list_empty(&reloc_roots))
4497                 free_reloc_roots(&reloc_roots);
4498
4499         btrfs_free_path(path);
4500
4501         if (err == 0) {
4502                 /* cleanup orphan inode in data relocation tree */
4503                 fs_root = read_fs_root(root->fs_info,
4504                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4505                 if (IS_ERR(fs_root))
4506                         err = PTR_ERR(fs_root);
4507                 else
4508                         err = btrfs_orphan_cleanup(fs_root);
4509         }
4510         return err;
4511 }
4512
4513 /*
4514  * helper to add ordered checksum for data relocation.
4515  *
4516  * cloning checksum properly handles the nodatasum extents.
4517  * it also saves CPU time to re-calculate the checksum.
4518  */
4519 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4520 {
4521         struct btrfs_ordered_sum *sums;
4522         struct btrfs_ordered_extent *ordered;
4523         struct btrfs_root *root = BTRFS_I(inode)->root;
4524         int ret;
4525         u64 disk_bytenr;
4526         u64 new_bytenr;
4527         LIST_HEAD(list);
4528
4529         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4530         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4531
4532         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4533         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4534                                        disk_bytenr + len - 1, &list, 0);
4535         if (ret)
4536                 goto out;
4537
4538         while (!list_empty(&list)) {
4539                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4540                 list_del_init(&sums->list);
4541
4542                 /*
4543                  * We need to offset the new_bytenr based on where the csum is.
4544                  * We need to do this because we will read in entire prealloc
4545                  * extents but we may have written to say the middle of the
4546                  * prealloc extent, so we need to make sure the csum goes with
4547                  * the right disk offset.
4548                  *
4549                  * We can do this because the data reloc inode refers strictly
4550                  * to the on disk bytes, so we don't have to worry about
4551                  * disk_len vs real len like with real inodes since it's all
4552                  * disk length.
4553                  */
4554                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4555                 sums->bytenr = new_bytenr;
4556
4557                 btrfs_add_ordered_sum(inode, ordered, sums);
4558         }
4559 out:
4560         btrfs_put_ordered_extent(ordered);
4561         return ret;
4562 }
4563
4564 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4565                           struct btrfs_root *root, struct extent_buffer *buf,
4566                           struct extent_buffer *cow)
4567 {
4568         struct reloc_control *rc;
4569         struct backref_node *node;
4570         int first_cow = 0;
4571         int level;
4572         int ret = 0;
4573
4574         rc = root->fs_info->reloc_ctl;
4575         if (!rc)
4576                 return 0;
4577
4578         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4579                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4580
4581         level = btrfs_header_level(buf);
4582         if (btrfs_header_generation(buf) <=
4583             btrfs_root_last_snapshot(&root->root_item))
4584                 first_cow = 1;
4585
4586         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4587             rc->create_reloc_tree) {
4588                 WARN_ON(!first_cow && level == 0);
4589
4590                 node = rc->backref_cache.path[level];
4591                 BUG_ON(node->bytenr != buf->start &&
4592                        node->new_bytenr != buf->start);
4593
4594                 drop_node_buffer(node);
4595                 extent_buffer_get(cow);
4596                 node->eb = cow;
4597                 node->new_bytenr = cow->start;
4598
4599                 if (!node->pending) {
4600                         list_move_tail(&node->list,
4601                                        &rc->backref_cache.pending[level]);
4602                         node->pending = 1;
4603                 }
4604
4605                 if (first_cow)
4606                         __mark_block_processed(rc, node);
4607
4608                 if (first_cow && level > 0)
4609                         rc->nodes_relocated += buf->len;
4610         }
4611
4612         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4613                 ret = replace_file_extents(trans, rc, root, cow);
4614         return ret;
4615 }
4616
4617 /*
4618  * called before creating snapshot. it calculates metadata reservation
4619  * requried for relocating tree blocks in the snapshot
4620  */
4621 void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
4622                               u64 *bytes_to_reserve)
4623 {
4624         struct btrfs_root *root;
4625         struct reloc_control *rc;
4626
4627         root = pending->root;
4628         if (!root->reloc_root)
4629                 return;
4630
4631         rc = root->fs_info->reloc_ctl;
4632         if (!rc->merge_reloc_tree)
4633                 return;
4634
4635         root = root->reloc_root;
4636         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4637         /*
4638          * relocation is in the stage of merging trees. the space
4639          * used by merging a reloc tree is twice the size of
4640          * relocated tree nodes in the worst case. half for cowing
4641          * the reloc tree, half for cowing the fs tree. the space
4642          * used by cowing the reloc tree will be freed after the
4643          * tree is dropped. if we create snapshot, cowing the fs
4644          * tree may use more space than it frees. so we need
4645          * reserve extra space.
4646          */
4647         *bytes_to_reserve += rc->nodes_relocated;
4648 }
4649
4650 /*
4651  * called after snapshot is created. migrate block reservation
4652  * and create reloc root for the newly created snapshot
4653  */
4654 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4655                                struct btrfs_pending_snapshot *pending)
4656 {
4657         struct btrfs_root *root = pending->root;
4658         struct btrfs_root *reloc_root;
4659         struct btrfs_root *new_root;
4660         struct reloc_control *rc;
4661         int ret;
4662
4663         if (!root->reloc_root)
4664                 return 0;
4665
4666         rc = root->fs_info->reloc_ctl;
4667         rc->merging_rsv_size += rc->nodes_relocated;
4668
4669         if (rc->merge_reloc_tree) {
4670                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4671                                               rc->block_rsv,
4672                                               rc->nodes_relocated);
4673                 if (ret)
4674                         return ret;
4675         }
4676
4677         new_root = pending->snap;
4678         reloc_root = create_reloc_root(trans, root->reloc_root,
4679                                        new_root->root_key.objectid);
4680         if (IS_ERR(reloc_root))
4681                 return PTR_ERR(reloc_root);
4682
4683         ret = __add_reloc_root(reloc_root);
4684         BUG_ON(ret < 0);
4685         new_root->reloc_root = reloc_root;
4686
4687         if (rc->create_reloc_tree)
4688                 ret = clone_backref_node(trans, rc, root, reloc_root);
4689         return ret;
4690 }