fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97
  98 struct backref_cache {
  99         /* red black tree of all backref nodes in the cache */
 100         struct rb_root rb_root;
 101         /* for passing backref nodes to btrfs_reloc_cow_block */
 102         struct backref_node *path[BTRFS_MAX_LEVEL];
 103         /*
 104          * list of blocks that have been cowed but some block
 105          * pointers in upper level blocks may not reflect the
 106          * new location
 107          */
 108         struct list_head pending[BTRFS_MAX_LEVEL];
 109         /* list of backref nodes with no child node */
 110         struct list_head leaves;
 111         /* list of blocks that have been cowed in current transaction */
 112         struct list_head changed;
 113         /* list of detached backref node. */
 114         struct list_head detached;
 115
 116         u64 last_trans;
 117
 118         int nr_nodes;
 119         int nr_edges;
 120 };
 121
 122 /*
 123  * map address of tree root to tree
 124  */
 125 struct mapping_node {
 126         struct rb_node rb_node;
 127         u64 bytenr;
 128         void *data;
 129 };
 130
 131 struct mapping_tree {
 132         struct rb_root rb_root;
 133         spinlock_t lock;
 134 };
 135
 136 /*
 137  * present a tree block to process
 138  */
 139 struct tree_block {
 140         struct rb_node rb_node;
 141         u64 bytenr;
 142         struct btrfs_key key;
 143         unsigned int level:8;
 144         unsigned int key_ready:1;
 145 };
 146
 147 #define MAX_EXTENTS 128
 148
 149 struct file_extent_cluster {
 150         u64 start;
 151         u64 end;
 152         u64 boundary[MAX_EXTENTS];
 153         unsigned int nr;
 154 };
 155
 156 struct reloc_control {
 157         /* block group to relocate */
 158         struct btrfs_block_group_cache *block_group;
 159         /* extent tree */
 160         struct btrfs_root *extent_root;
 161         /* inode for moving data */
 162         struct inode *data_inode;
 163
 164         struct btrfs_block_rsv *block_rsv;
 165
 166         struct backref_cache backref_cache;
 167
 168         struct file_extent_cluster cluster;
 169         /* tree blocks have been processed */
 170         struct extent_io_tree processed_blocks;
 171         /* map start of tree root to corresponding reloc tree */
 172         struct mapping_tree reloc_root_tree;
 173         /* list of reloc trees */
 174         struct list_head reloc_roots;
 175         /* size of metadata reservation for merging reloc trees */
 176         u64 merging_rsv_size;
 177         /* size of relocated tree nodes */
 178         u64 nodes_relocated;
 179
 180         u64 search_start;
 181         u64 extents_found;
 182
 183         unsigned int stage:8;
 184         unsigned int create_reloc_tree:1;
 185         unsigned int merge_reloc_tree:1;
 186         unsigned int found_file_extent:1;
 187         unsigned int commit_transaction:1;
 188 };
 189
 190 /* stages of data relocation */
 191 #define MOVE_DATA_EXTENTS       0
 192 #define UPDATE_DATA_PTRS        1
 193
 194 static void remove_backref_node(struct backref_cache *cache,
 195                                 struct backref_node *node);
 196 static void __mark_block_processed(struct reloc_control *rc,
 197                                    struct backref_node *node);
 198
 199 static void mapping_tree_init(struct mapping_tree *tree)
 200 {
 201         tree->rb_root = RB_ROOT;
 202         spin_lock_init(&tree->lock);
 203 }
 204
 205 static void backref_cache_init(struct backref_cache *cache)
 206 {
 207         int i;
 208         cache->rb_root = RB_ROOT;
 209         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 210                 INIT_LIST_HEAD(&cache->pending[i]);
 211         INIT_LIST_HEAD(&cache->changed);
 212         INIT_LIST_HEAD(&cache->detached);
 213         INIT_LIST_HEAD(&cache->leaves);
 214 }
 215
 216 static void backref_cache_cleanup(struct backref_cache *cache)
 217 {
 218         struct backref_node *node;
 219         int i;
 220
 221         while (!list_empty(&cache->detached)) {
 222                 node = list_entry(cache->detached.next,
 223                                   struct backref_node, list);
 224                 remove_backref_node(cache, node);
 225         }
 226
 227         while (!list_empty(&cache->leaves)) {
 228                 node = list_entry(cache->leaves.next,
 229                                   struct backref_node, lower);
 230                 remove_backref_node(cache, node);
 231         }
 232
 233         cache->last_trans = 0;
 234
 235         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 236                 BUG_ON(!list_empty(&cache->pending[i]));
 237         BUG_ON(!list_empty(&cache->changed));
 238         BUG_ON(!list_empty(&cache->detached));
 239         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 240         BUG_ON(cache->nr_nodes);
 241         BUG_ON(cache->nr_edges);
 242 }
 243
 244 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 245 {
 246         struct backref_node *node;
 247
 248         node = kzalloc(sizeof(*node), GFP_NOFS);
 249         if (node) {
 250                 INIT_LIST_HEAD(&node->list);
 251                 INIT_LIST_HEAD(&node->upper);
 252                 INIT_LIST_HEAD(&node->lower);
 253                 RB_CLEAR_NODE(&node->rb_node);
 254                 cache->nr_nodes++;
 255         }
 256         return node;
 257 }
 258
 259 static void free_backref_node(struct backref_cache *cache,
 260                               struct backref_node *node)
 261 {
 262         if (node) {
 263                 cache->nr_nodes--;
 264                 kfree(node);
 265         }
 266 }
 267
 268 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 269 {
 270         struct backref_edge *edge;
 271
 272         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 273         if (edge)
 274                 cache->nr_edges++;
 275         return edge;
 276 }
 277
 278 static void free_backref_edge(struct backref_cache *cache,
 279                               struct backref_edge *edge)
 280 {
 281         if (edge) {
 282                 cache->nr_edges--;
 283                 kfree(edge);
 284         }
 285 }
 286
 287 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 288                                    struct rb_node *node)
 289 {
 290         struct rb_node **p = &root->rb_node;
 291         struct rb_node *parent = NULL;
 292         struct tree_entry *entry;
 293
 294         while (*p) {
 295                 parent = *p;
 296                 entry = rb_entry(parent, struct tree_entry, rb_node);
 297
 298                 if (bytenr < entry->bytenr)
 299                         p = &(*p)->rb_left;
 300                 else if (bytenr > entry->bytenr)
 301                         p = &(*p)->rb_right;
 302                 else
 303                         return parent;
 304         }
 305
 306         rb_link_node(node, parent, p);
 307         rb_insert_color(node, root);
 308         return NULL;
 309 }
 310
 311 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 312 {
 313         struct rb_node *n = root->rb_node;
 314         struct tree_entry *entry;
 315
 316         while (n) {
 317                 entry = rb_entry(n, struct tree_entry, rb_node);
 318
 319                 if (bytenr < entry->bytenr)
 320                         n = n->rb_left;
 321                 else if (bytenr > entry->bytenr)
 322                         n = n->rb_right;
 323                 else
 324                         return n;
 325         }
 326         return NULL;
 327 }
 328
 329 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 330 {
 331
 332         struct btrfs_fs_info *fs_info = NULL;
 333         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 334                                               rb_node);
 335         if (bnode->root)
 336                 fs_info = bnode->root->fs_info;
 337         btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 338                     "found at offset %llu\n", (unsigned long long)bytenr);
 339 }
 340
 341 /*
 342  * walk up backref nodes until reach node presents tree root
 343  */
 344 static struct backref_node *walk_up_backref(struct backref_node *node,
 345                                             struct backref_edge *edges[],
 346                                             int *index)
 347 {
 348         struct backref_edge *edge;
 349         int idx = *index;
 350
 351         while (!list_empty(&node->upper)) {
 352                 edge = list_entry(node->upper.next,
 353                                   struct backref_edge, list[LOWER]);
 354                 edges[idx++] = edge;
 355                 node = edge->node[UPPER];
 356         }
 357         BUG_ON(node->detached);
 358         *index = idx;
 359         return node;
 360 }
 361
 362 /*
 363  * walk down backref nodes to find start of next reference path
 364  */
 365 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 366                                               int *index)
 367 {
 368         struct backref_edge *edge;
 369         struct backref_node *lower;
 370         int idx = *index;
 371
 372         while (idx > 0) {
 373                 edge = edges[idx - 1];
 374                 lower = edge->node[LOWER];
 375                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 376                         idx--;
 377                         continue;
 378                 }
 379                 edge = list_entry(edge->list[LOWER].next,
 380                                   struct backref_edge, list[LOWER]);
 381                 edges[idx - 1] = edge;
 382                 *index = idx;
 383                 return edge->node[UPPER];
 384         }
 385         *index = 0;
 386         return NULL;
 387 }
 388
 389 static void unlock_node_buffer(struct backref_node *node)
 390 {
 391         if (node->locked) {
 392                 btrfs_tree_unlock(node->eb);
 393                 node->locked = 0;
 394         }
 395 }
 396
 397 static void drop_node_buffer(struct backref_node *node)
 398 {
 399         if (node->eb) {
 400                 unlock_node_buffer(node);
 401                 free_extent_buffer(node->eb);
 402                 node->eb = NULL;
 403         }
 404 }
 405
 406 static void drop_backref_node(struct backref_cache *tree,
 407                               struct backref_node *node)
 408 {
 409         BUG_ON(!list_empty(&node->upper));
 410
 411         drop_node_buffer(node);
 412         list_del(&node->list);
 413         list_del(&node->lower);
 414         if (!RB_EMPTY_NODE(&node->rb_node))
 415                 rb_erase(&node->rb_node, &tree->rb_root);
 416         free_backref_node(tree, node);
 417 }
 418
 419 /*
 420  * remove a backref node from the backref cache
 421  */
 422 static void remove_backref_node(struct backref_cache *cache,
 423                                 struct backref_node *node)
 424 {
 425         struct backref_node *upper;
 426         struct backref_edge *edge;
 427
 428         if (!node)
 429                 return;
 430
 431         BUG_ON(!node->lowest && !node->detached);
 432         while (!list_empty(&node->upper)) {
 433                 edge = list_entry(node->upper.next, struct backref_edge,
 434                                   list[LOWER]);
 435                 upper = edge->node[UPPER];
 436                 list_del(&edge->list[LOWER]);
 437                 list_del(&edge->list[UPPER]);
 438                 free_backref_edge(cache, edge);
 439
 440                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 441                         BUG_ON(!list_empty(&node->upper));
 442                         drop_backref_node(cache, node);
 443                         node = upper;
 444                         node->lowest = 1;
 445                         continue;
 446                 }
 447                 /*
 448                  * add the node to leaf node list if no other
 449                  * child block cached.
 450                  */
 451                 if (list_empty(&upper->lower)) {
 452                         list_add_tail(&upper->lower, &cache->leaves);
 453                         upper->lowest = 1;
 454                 }
 455         }
 456
 457         drop_backref_node(cache, node);
 458 }
 459
 460 static void update_backref_node(struct backref_cache *cache,
 461                                 struct backref_node *node, u64 bytenr)
 462 {
 463         struct rb_node *rb_node;
 464         rb_erase(&node->rb_node, &cache->rb_root);
 465         node->bytenr = bytenr;
 466         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 467         if (rb_node)
 468                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 469 }
 470
 471 /*
 472  * update backref cache after a transaction commit
 473  */
 474 static int update_backref_cache(struct btrfs_trans_handle *trans,
 475                                 struct backref_cache *cache)
 476 {
 477         struct backref_node *node;
 478         int level = 0;
 479
 480         if (cache->last_trans == 0) {
 481                 cache->last_trans = trans->transid;
 482                 return 0;
 483         }
 484
 485         if (cache->last_trans == trans->transid)
 486                 return 0;
 487
 488         /*
 489          * detached nodes are used to avoid unnecessary backref
 490          * lookup. transaction commit changes the extent tree.
 491          * so the detached nodes are no longer useful.
 492          */
 493         while (!list_empty(&cache->detached)) {
 494                 node = list_entry(cache->detached.next,
 495                                   struct backref_node, list);
 496                 remove_backref_node(cache, node);
 497         }
 498
 499         while (!list_empty(&cache->changed)) {
 500                 node = list_entry(cache->changed.next,
 501                                   struct backref_node, list);
 502                 list_del_init(&node->list);
 503                 BUG_ON(node->pending);
 504                 update_backref_node(cache, node, node->new_bytenr);
 505         }
 506
 507         /*
 508          * some nodes can be left in the pending list if there were
 509          * errors during processing the pending nodes.
 510          */
 511         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 512                 list_for_each_entry(node, &cache->pending[level], list) {
 513                         BUG_ON(!node->pending);
 514                         if (node->bytenr == node->new_bytenr)
 515                                 continue;
 516                         update_backref_node(cache, node, node->new_bytenr);
 517                 }
 518         }
 519
 520         cache->last_trans = 0;
 521         return 1;
 522 }
 523
 524
 525 static int should_ignore_root(struct btrfs_root *root)
 526 {
 527         struct btrfs_root *reloc_root;
 528
 529         if (!root->ref_cows)
 530                 return 0;
 531
 532         reloc_root = root->reloc_root;
 533         if (!reloc_root)
 534                 return 0;
 535
 536         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 537             root->fs_info->running_transaction->transid - 1)
 538                 return 0;
 539         /*
 540          * if there is reloc tree and it was created in previous
 541          * transaction backref lookup can find the reloc tree,
 542          * so backref node for the fs tree root is useless for
 543          * relocation.
 544          */
 545         return 1;
 546 }
 547 /*
 548  * find reloc tree by address of tree root
 549  */
 550 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 551                                           u64 bytenr)
 552 {
 553         struct rb_node *rb_node;
 554         struct mapping_node *node;
 555         struct btrfs_root *root = NULL;
 556
 557         spin_lock(&rc->reloc_root_tree.lock);
 558         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 559         if (rb_node) {
 560                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 561                 root = (struct btrfs_root *)node->data;
 562         }
 563         spin_unlock(&rc->reloc_root_tree.lock);
 564         return root;
 565 }
 566
 567 static int is_cowonly_root(u64 root_objectid)
 568 {
 569         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 570             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 571             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 572             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 573             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 574             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
 575                 return 1;
 576         return 0;
 577 }
 578
 579 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 580                                         u64 root_objectid)
 581 {
 582         struct btrfs_key key;
 583
 584         key.objectid = root_objectid;
 585         key.type = BTRFS_ROOT_ITEM_KEY;
 586         if (is_cowonly_root(root_objectid))
 587                 key.offset = 0;
 588         else
 589                 key.offset = (u64)-1;
 590
 591         return btrfs_read_fs_root_no_name(fs_info, &key);
 592 }
 593
 594 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 595 static noinline_for_stack
 596 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 597                                   struct extent_buffer *leaf,
 598                                   struct btrfs_extent_ref_v0 *ref0)
 599 {
 600         struct btrfs_root *root;
 601         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 602         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 603
 604         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 605
 606         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 607         BUG_ON(IS_ERR(root));
 608
 609         if (root->ref_cows &&
 610             generation != btrfs_root_generation(&root->root_item))
 611                 return NULL;
 612
 613         return root;
 614 }
 615 #endif
 616
 617 static noinline_for_stack
 618 int find_inline_backref(struct extent_buffer *leaf, int slot,
 619                         unsigned long *ptr, unsigned long *end)
 620 {
 621         struct btrfs_key key;
 622         struct btrfs_extent_item *ei;
 623         struct btrfs_tree_block_info *bi;
 624         u32 item_size;
 625
 626         btrfs_item_key_to_cpu(leaf, &key, slot);
 627
 628         item_size = btrfs_item_size_nr(leaf, slot);
 629 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 630         if (item_size < sizeof(*ei)) {
 631                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 632                 return 1;
 633         }
 634 #endif
 635         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 636         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 637                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 638
 639         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 640             item_size <= sizeof(*ei) + sizeof(*bi)) {
 641                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 642                 return 1;
 643         }
 644         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 645             item_size <= sizeof(*ei)) {
 646                 WARN_ON(item_size < sizeof(*ei));
 647                 return 1;
 648         }
 649
 650         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 651                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 652                 *ptr = (unsigned long)(bi + 1);
 653         } else {
 654                 *ptr = (unsigned long)(ei + 1);
 655         }
 656         *end = (unsigned long)ei + item_size;
 657         return 0;
 658 }
 659
 660 /*
 661  * build backref tree for a given tree block. root of the backref tree
 662  * corresponds the tree block, leaves of the backref tree correspond
 663  * roots of b-trees that reference the tree block.
 664  *
 665  * the basic idea of this function is check backrefs of a given block
 666  * to find upper level blocks that refernece the block, and then check
 667  * bakcrefs of these upper level blocks recursively. the recursion stop
 668  * when tree root is reached or backrefs for the block is cached.
 669  *
 670  * NOTE: if we find backrefs for a block are cached, we know backrefs
 671  * for all upper level blocks that directly/indirectly reference the
 672  * block are also cached.
 673  */
 674 static noinline_for_stack
 675 struct backref_node *build_backref_tree(struct reloc_control *rc,
 676                                         struct btrfs_key *node_key,
 677                                         int level, u64 bytenr)
 678 {
 679         struct backref_cache *cache = &rc->backref_cache;
 680         struct btrfs_path *path1;
 681         struct btrfs_path *path2;
 682         struct extent_buffer *eb;
 683         struct btrfs_root *root;
 684         struct backref_node *cur;
 685         struct backref_node *upper;
 686         struct backref_node *lower;
 687         struct backref_node *node = NULL;
 688         struct backref_node *exist = NULL;
 689         struct backref_edge *edge;
 690         struct rb_node *rb_node;
 691         struct btrfs_key key;
 692         unsigned long end;
 693         unsigned long ptr;
 694         LIST_HEAD(list);
 695         LIST_HEAD(useless);
 696         int cowonly;
 697         int ret;
 698         int err = 0;
 699         bool need_check = true;
 700
 701         path1 = btrfs_alloc_path();
 702         path2 = btrfs_alloc_path();
 703         if (!path1 || !path2) {
 704                 err = -ENOMEM;
 705                 goto out;
 706         }
 707         path1->reada = 1;
 708         path2->reada = 2;
 709
 710         node = alloc_backref_node(cache);
 711         if (!node) {
 712                 err = -ENOMEM;
 713                 goto out;
 714         }
 715
 716         node->bytenr = bytenr;
 717         node->level = level;
 718         node->lowest = 1;
 719         cur = node;
 720 again:
 721         end = 0;
 722         ptr = 0;
 723         key.objectid = cur->bytenr;
 724         key.type = BTRFS_METADATA_ITEM_KEY;
 725         key.offset = (u64)-1;
 726
 727         path1->search_commit_root = 1;
 728         path1->skip_locking = 1;
 729         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 730                                 0, 0);
 731         if (ret < 0) {
 732                 err = ret;
 733                 goto out;
 734         }
 735         BUG_ON(!ret || !path1->slots[0]);
 736
 737         path1->slots[0]--;
 738
 739         WARN_ON(cur->checked);
 740         if (!list_empty(&cur->upper)) {
 741                 /*
 742                  * the backref was added previously when processing
 743                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 744                  */
 745                 BUG_ON(!list_is_singular(&cur->upper));
 746                 edge = list_entry(cur->upper.next, struct backref_edge,
 747                                   list[LOWER]);
 748                 BUG_ON(!list_empty(&edge->list[UPPER]));
 749                 exist = edge->node[UPPER];
 750                 /*
 751                  * add the upper level block to pending list if we need
 752                  * check its backrefs
 753                  */
 754                 if (!exist->checked)
 755                         list_add_tail(&edge->list[UPPER], &list);
 756         } else {
 757                 exist = NULL;
 758         }
 759
 760         while (1) {
 761                 cond_resched();
 762                 eb = path1->nodes[0];
 763
 764                 if (ptr >= end) {
 765                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 766                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 767                                 if (ret < 0) {
 768                                         err = ret;
 769                                         goto out;
 770                                 }
 771                                 if (ret > 0)
 772                                         break;
 773                                 eb = path1->nodes[0];
 774                         }
 775
 776                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 777                         if (key.objectid != cur->bytenr) {
 778                                 WARN_ON(exist);
 779                                 break;
 780                         }
 781
 782                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 783                             key.type == BTRFS_METADATA_ITEM_KEY) {
 784                                 ret = find_inline_backref(eb, path1->slots[0],
 785                                                           &ptr, &end);
 786                                 if (ret)
 787                                         goto next;
 788                         }
 789                 }
 790
 791                 if (ptr < end) {
 792                         /* update key for inline back ref */
 793                         struct btrfs_extent_inline_ref *iref;
 794                         iref = (struct btrfs_extent_inline_ref *)ptr;
 795                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 796                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 797                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 798                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 799                 }
 800
 801                 if (exist &&
 802                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 803                       exist->owner == key.offset) ||
 804                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 805                       exist->bytenr == key.offset))) {
 806                         exist = NULL;
 807                         goto next;
 808                 }
 809
 810 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 811                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 812                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 813                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 814                                 struct btrfs_extent_ref_v0 *ref0;
 815                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 816                                                 struct btrfs_extent_ref_v0);
 817                                 if (key.objectid == key.offset) {
 818                                         root = find_tree_root(rc, eb, ref0);
 819                                         if (root && !should_ignore_root(root))
 820                                                 cur->root = root;
 821                                         else
 822                                                 list_add(&cur->list, &useless);
 823                                         break;
 824                                 }
 825                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 826                                                                       ref0)))
 827                                         cur->cowonly = 1;
 828                         }
 829 #else
 830                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 831                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 832 #endif
 833                         if (key.objectid == key.offset) {
 834                                 /*
 835                                  * only root blocks of reloc trees use
 836                                  * backref of this type.
 837                                  */
 838                                 root = find_reloc_root(rc, cur->bytenr);
 839                                 BUG_ON(!root);
 840                                 cur->root = root;
 841                                 break;
 842                         }
 843
 844                         edge = alloc_backref_edge(cache);
 845                         if (!edge) {
 846                                 err = -ENOMEM;
 847                                 goto out;
 848                         }
 849                         rb_node = tree_search(&cache->rb_root, key.offset);
 850                         if (!rb_node) {
 851                                 upper = alloc_backref_node(cache);
 852                                 if (!upper) {
 853                                         free_backref_edge(cache, edge);
 854                                         err = -ENOMEM;
 855                                         goto out;
 856                                 }
 857                                 upper->bytenr = key.offset;
 858                                 upper->level = cur->level + 1;
 859                                 /*
 860                                  *  backrefs for the upper level block isn't
 861                                  *  cached, add the block to pending list
 862                                  */
 863                                 list_add_tail(&edge->list[UPPER], &list);
 864                         } else {
 865                                 upper = rb_entry(rb_node, struct backref_node,
 866                                                  rb_node);
 867                                 BUG_ON(!upper->checked);
 868                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 869                         }
 870                         list_add_tail(&edge->list[LOWER], &cur->upper);
 871                         edge->node[LOWER] = cur;
 872                         edge->node[UPPER] = upper;
 873
 874                         goto next;
 875                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 876                         goto next;
 877                 }
 878
 879                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 880                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 881                 if (IS_ERR(root)) {
 882                         err = PTR_ERR(root);
 883                         goto out;
 884                 }
 885
 886                 if (!root->ref_cows)
 887                         cur->cowonly = 1;
 888
 889                 if (btrfs_root_level(&root->root_item) == cur->level) {
 890                         /* tree root */
 891                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 892                                cur->bytenr);
 893                         if (should_ignore_root(root))
 894                                 list_add(&cur->list, &useless);
 895                         else
 896                                 cur->root = root;
 897                         break;
 898                 }
 899
 900                 level = cur->level + 1;
 901
 902                 /*
 903                  * searching the tree to find upper level blocks
 904                  * reference the block.
 905                  */
 906                 path2->search_commit_root = 1;
 907                 path2->skip_locking = 1;
 908                 path2->lowest_level = level;
 909                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 910                 path2->lowest_level = 0;
 911                 if (ret < 0) {
 912                         err = ret;
 913                         goto out;
 914                 }
 915                 if (ret > 0 && path2->slots[level] > 0)
 916                         path2->slots[level]--;
 917
 918                 eb = path2->nodes[level];
 919                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 920                         cur->bytenr);
 921
 922                 lower = cur;
 923                 need_check = true;
 924                 for (; level < BTRFS_MAX_LEVEL; level++) {
 925                         if (!path2->nodes[level]) {
 926                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 927                                        lower->bytenr);
 928                                 if (should_ignore_root(root))
 929                                         list_add(&lower->list, &useless);
 930                                 else
 931                                         lower->root = root;
 932                                 break;
 933                         }
 934
 935                         edge = alloc_backref_edge(cache);
 936                         if (!edge) {
 937                                 err = -ENOMEM;
 938                                 goto out;
 939                         }
 940
 941                         eb = path2->nodes[level];
 942                         rb_node = tree_search(&cache->rb_root, eb->start);
 943                         if (!rb_node) {
 944                                 upper = alloc_backref_node(cache);
 945                                 if (!upper) {
 946                                         free_backref_edge(cache, edge);
 947                                         err = -ENOMEM;
 948                                         goto out;
 949                                 }
 950                                 upper->bytenr = eb->start;
 951                                 upper->owner = btrfs_header_owner(eb);
 952                                 upper->level = lower->level + 1;
 953                                 if (!root->ref_cows)
 954                                         upper->cowonly = 1;
 955
 956                                 /*
 957                                  * if we know the block isn't shared
 958                                  * we can void checking its backrefs.
 959                                  */
 960                                 if (btrfs_block_can_be_shared(root, eb))
 961                                         upper->checked = 0;
 962                                 else
 963                                         upper->checked = 1;
 964
 965                                 /*
 966                                  * add the block to pending list if we
 967                                  * need check its backrefs, we only do this once
 968                                  * while walking up a tree as we will catch
 969                                  * anything else later on.
 970                                  */
 971                                 if (!upper->checked && need_check) {
 972                                         need_check = false;
 973                                         list_add_tail(&edge->list[UPPER],
 974                                                       &list);
 975                                 } else
 976                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 977                         } else {
 978                                 upper = rb_entry(rb_node, struct backref_node,
 979                                                  rb_node);
 980                                 BUG_ON(!upper->checked);
 981                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 982                                 if (!upper->owner)
 983                                         upper->owner = btrfs_header_owner(eb);
 984                         }
 985                         list_add_tail(&edge->list[LOWER], &lower->upper);
 986                         edge->node[LOWER] = lower;
 987                         edge->node[UPPER] = upper;
 988
 989                         if (rb_node)
 990                                 break;
 991                         lower = upper;
 992                         upper = NULL;
 993                 }
 994                 btrfs_release_path(path2);
 995 next:
 996                 if (ptr < end) {
 997                         ptr += btrfs_extent_inline_ref_size(key.type);
 998                         if (ptr >= end) {
 999                                 WARN_ON(ptr > end);
1000                                 ptr = 0;
1001                                 end = 0;
1002                         }
1003                 }
1004                 if (ptr >= end)
1005                         path1->slots[0]++;
1006         }
1007         btrfs_release_path(path1);
1008
1009         cur->checked = 1;
1010         WARN_ON(exist);
1011
1012         /* the pending list isn't empty, take the first block to process */
1013         if (!list_empty(&list)) {
1014                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1015                 list_del_init(&edge->list[UPPER]);
1016                 cur = edge->node[UPPER];
1017                 goto again;
1018         }
1019
1020         /*
1021          * everything goes well, connect backref nodes and insert backref nodes
1022          * into the cache.
1023          */
1024         BUG_ON(!node->checked);
1025         cowonly = node->cowonly;
1026         if (!cowonly) {
1027                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1028                                       &node->rb_node);
1029                 if (rb_node)
1030                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1031                 list_add_tail(&node->lower, &cache->leaves);
1032         }
1033
1034         list_for_each_entry(edge, &node->upper, list[LOWER])
1035                 list_add_tail(&edge->list[UPPER], &list);
1036
1037         while (!list_empty(&list)) {
1038                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1039                 list_del_init(&edge->list[UPPER]);
1040                 upper = edge->node[UPPER];
1041                 if (upper->detached) {
1042                         list_del(&edge->list[LOWER]);
1043                         lower = edge->node[LOWER];
1044                         free_backref_edge(cache, edge);
1045                         if (list_empty(&lower->upper))
1046                                 list_add(&lower->list, &useless);
1047                         continue;
1048                 }
1049
1050                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1051                         if (upper->lowest) {
1052                                 list_del_init(&upper->lower);
1053                                 upper->lowest = 0;
1054                         }
1055
1056                         list_add_tail(&edge->list[UPPER], &upper->lower);
1057                         continue;
1058                 }
1059
1060                 BUG_ON(!upper->checked);
1061                 BUG_ON(cowonly != upper->cowonly);
1062                 if (!cowonly) {
1063                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1064                                               &upper->rb_node);
1065                         if (rb_node)
1066                                 backref_tree_panic(rb_node, -EEXIST,
1067                                                    upper->bytenr);
1068                 }
1069
1070                 list_add_tail(&edge->list[UPPER], &upper->lower);
1071
1072                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1073                         list_add_tail(&edge->list[UPPER], &list);
1074         }
1075         /*
1076          * process useless backref nodes. backref nodes for tree leaves
1077          * are deleted from the cache. backref nodes for upper level
1078          * tree blocks are left in the cache to avoid unnecessary backref
1079          * lookup.
1080          */
1081         while (!list_empty(&useless)) {
1082                 upper = list_entry(useless.next, struct backref_node, list);
1083                 list_del_init(&upper->list);
1084                 BUG_ON(!list_empty(&upper->upper));
1085                 if (upper == node)
1086                         node = NULL;
1087                 if (upper->lowest) {
1088                         list_del_init(&upper->lower);
1089                         upper->lowest = 0;
1090                 }
1091                 while (!list_empty(&upper->lower)) {
1092                         edge = list_entry(upper->lower.next,
1093                                           struct backref_edge, list[UPPER]);
1094                         list_del(&edge->list[UPPER]);
1095                         list_del(&edge->list[LOWER]);
1096                         lower = edge->node[LOWER];
1097                         free_backref_edge(cache, edge);
1098
1099                         if (list_empty(&lower->upper))
1100                                 list_add(&lower->list, &useless);
1101                 }
1102                 __mark_block_processed(rc, upper);
1103                 if (upper->level > 0) {
1104                         list_add(&upper->list, &cache->detached);
1105                         upper->detached = 1;
1106                 } else {
1107                         rb_erase(&upper->rb_node, &cache->rb_root);
1108                         free_backref_node(cache, upper);
1109                 }
1110         }
1111 out:
1112         btrfs_free_path(path1);
1113         btrfs_free_path(path2);
1114         if (err) {
1115                 while (!list_empty(&useless)) {
1116                         lower = list_entry(useless.next,
1117                                            struct backref_node, upper);
1118                         list_del_init(&lower->upper);
1119                 }
1120                 upper = node;
1121                 INIT_LIST_HEAD(&list);
1122                 while (upper) {
1123                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1124                                 list_splice_tail(&upper->upper, &list);
1125                                 free_backref_node(cache, upper);
1126                         }
1127
1128                         if (list_empty(&list))
1129                                 break;
1130
1131                         edge = list_entry(list.next, struct backref_edge,
1132                                           list[LOWER]);
1133                         list_del(&edge->list[LOWER]);
1134                         upper = edge->node[UPPER];
1135                         free_backref_edge(cache, edge);
1136                 }
1137                 return ERR_PTR(err);
1138         }
1139         BUG_ON(node && node->detached);
1140         return node;
1141 }
1142
1143 /*
1144  * helper to add backref node for the newly created snapshot.
1145  * the backref node is created by cloning backref node that
1146  * corresponds to root of source tree
1147  */
1148 static int clone_backref_node(struct btrfs_trans_handle *trans,
1149                               struct reloc_control *rc,
1150                               struct btrfs_root *src,
1151                               struct btrfs_root *dest)
1152 {
1153         struct btrfs_root *reloc_root = src->reloc_root;
1154         struct backref_cache *cache = &rc->backref_cache;
1155         struct backref_node *node = NULL;
1156         struct backref_node *new_node;
1157         struct backref_edge *edge;
1158         struct backref_edge *new_edge;
1159         struct rb_node *rb_node;
1160
1161         if (cache->last_trans > 0)
1162                 update_backref_cache(trans, cache);
1163
1164         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1165         if (rb_node) {
1166                 node = rb_entry(rb_node, struct backref_node, rb_node);
1167                 if (node->detached)
1168                         node = NULL;
1169                 else
1170                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1171         }
1172
1173         if (!node) {
1174                 rb_node = tree_search(&cache->rb_root,
1175                                       reloc_root->commit_root->start);
1176                 if (rb_node) {
1177                         node = rb_entry(rb_node, struct backref_node,
1178                                         rb_node);
1179                         BUG_ON(node->detached);
1180                 }
1181         }
1182
1183         if (!node)
1184                 return 0;
1185
1186         new_node = alloc_backref_node(cache);
1187         if (!new_node)
1188                 return -ENOMEM;
1189
1190         new_node->bytenr = dest->node->start;
1191         new_node->level = node->level;
1192         new_node->lowest = node->lowest;
1193         new_node->checked = 1;
1194         new_node->root = dest;
1195
1196         if (!node->lowest) {
1197                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1198                         new_edge = alloc_backref_edge(cache);
1199                         if (!new_edge)
1200                                 goto fail;
1201
1202                         new_edge->node[UPPER] = new_node;
1203                         new_edge->node[LOWER] = edge->node[LOWER];
1204                         list_add_tail(&new_edge->list[UPPER],
1205                                       &new_node->lower);
1206                 }
1207         } else {
1208                 list_add_tail(&new_node->lower, &cache->leaves);
1209         }
1210
1211         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1212                               &new_node->rb_node);
1213         if (rb_node)
1214                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1215
1216         if (!new_node->lowest) {
1217                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1218                         list_add_tail(&new_edge->list[LOWER],
1219                                       &new_edge->node[LOWER]->upper);
1220                 }
1221         }
1222         return 0;
1223 fail:
1224         while (!list_empty(&new_node->lower)) {
1225                 new_edge = list_entry(new_node->lower.next,
1226                                       struct backref_edge, list[UPPER]);
1227                 list_del(&new_edge->list[UPPER]);
1228                 free_backref_edge(cache, new_edge);
1229         }
1230         free_backref_node(cache, new_node);
1231         return -ENOMEM;
1232 }
1233
1234 /*
1235  * helper to add 'address of tree root -> reloc tree' mapping
1236  */
1237 static int __must_check __add_reloc_root(struct btrfs_root *root)
1238 {
1239         struct rb_node *rb_node;
1240         struct mapping_node *node;
1241         struct reloc_control *rc = root->fs_info->reloc_ctl;
1242
1243         node = kmalloc(sizeof(*node), GFP_NOFS);
1244         if (!node)
1245                 return -ENOMEM;
1246
1247         node->bytenr = root->node->start;
1248         node->data = root;
1249
1250         spin_lock(&rc->reloc_root_tree.lock);
1251         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1252                               node->bytenr, &node->rb_node);
1253         spin_unlock(&rc->reloc_root_tree.lock);
1254         if (rb_node) {
1255                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1256                             "for start=%llu while inserting into relocation "
1257                             "tree\n", node->bytenr);
1258                 kfree(node);
1259                 return -EEXIST;
1260         }
1261
1262         list_add_tail(&root->root_list, &rc->reloc_roots);
1263         return 0;
1264 }
1265
1266 /*
1267  * helper to update/delete the 'address of tree root -> reloc tree'
1268  * mapping
1269  */
1270 static int __update_reloc_root(struct btrfs_root *root, int del)
1271 {
1272         struct rb_node *rb_node;
1273         struct mapping_node *node = NULL;
1274         struct reloc_control *rc = root->fs_info->reloc_ctl;
1275
1276         spin_lock(&rc->reloc_root_tree.lock);
1277         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1278                               root->commit_root->start);
1279         if (rb_node) {
1280                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1281                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1282         }
1283         spin_unlock(&rc->reloc_root_tree.lock);
1284
1285         if (!node)
1286                 return 0;
1287         BUG_ON((struct btrfs_root *)node->data != root);
1288
1289         if (!del) {
1290                 spin_lock(&rc->reloc_root_tree.lock);
1291                 node->bytenr = root->node->start;
1292                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1293                                       node->bytenr, &node->rb_node);
1294                 spin_unlock(&rc->reloc_root_tree.lock);
1295                 if (rb_node)
1296                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1297         } else {
1298                 spin_lock(&root->fs_info->trans_lock);
1299                 list_del_init(&root->root_list);
1300                 spin_unlock(&root->fs_info->trans_lock);
1301                 kfree(node);
1302         }
1303         return 0;
1304 }
1305
1306 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1307                                         struct btrfs_root *root, u64 objectid)
1308 {
1309         struct btrfs_root *reloc_root;
1310         struct extent_buffer *eb;
1311         struct btrfs_root_item *root_item;
1312         struct btrfs_key root_key;
1313         u64 last_snap = 0;
1314         int ret;
1315
1316         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1317         BUG_ON(!root_item);
1318
1319         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1320         root_key.type = BTRFS_ROOT_ITEM_KEY;
1321         root_key.offset = objectid;
1322
1323         if (root->root_key.objectid == objectid) {
1324                 /* called by btrfs_init_reloc_root */
1325                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1326                                       BTRFS_TREE_RELOC_OBJECTID);
1327                 BUG_ON(ret);
1328
1329                 last_snap = btrfs_root_last_snapshot(&root->root_item);
1330                 btrfs_set_root_last_snapshot(&root->root_item,
1331                                              trans->transid - 1);
1332         } else {
1333                 /*
1334                  * called by btrfs_reloc_post_snapshot_hook.
1335                  * the source tree is a reloc tree, all tree blocks
1336                  * modified after it was created have RELOC flag
1337                  * set in their headers. so it's OK to not update
1338                  * the 'last_snapshot'.
1339                  */
1340                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1341                                       BTRFS_TREE_RELOC_OBJECTID);
1342                 BUG_ON(ret);
1343         }
1344
1345         memcpy(root_item, &root->root_item, sizeof(*root_item));
1346         btrfs_set_root_bytenr(root_item, eb->start);
1347         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1348         btrfs_set_root_generation(root_item, trans->transid);
1349
1350         if (root->root_key.objectid == objectid) {
1351                 btrfs_set_root_refs(root_item, 0);
1352                 memset(&root_item->drop_progress, 0,
1353                        sizeof(struct btrfs_disk_key));
1354                 root_item->drop_level = 0;
1355                 /*
1356                  * abuse rtransid, it is safe because it is impossible to
1357                  * receive data into a relocation tree.
1358                  */
1359                 btrfs_set_root_rtransid(root_item, last_snap);
1360                 btrfs_set_root_otransid(root_item, trans->transid);
1361         }
1362
1363         btrfs_tree_unlock(eb);
1364         free_extent_buffer(eb);
1365
1366         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1367                                 &root_key, root_item);
1368         BUG_ON(ret);
1369         kfree(root_item);
1370
1371         reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
1372         BUG_ON(IS_ERR(reloc_root));
1373         reloc_root->last_trans = trans->transid;
1374         return reloc_root;
1375 }
1376
1377 /*
1378  * create reloc tree for a given fs tree. reloc tree is just a
1379  * snapshot of the fs tree with special root objectid.
1380  */
1381 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1382                           struct btrfs_root *root)
1383 {
1384         struct btrfs_root *reloc_root;
1385         struct reloc_control *rc = root->fs_info->reloc_ctl;
1386         int clear_rsv = 0;
1387         int ret;
1388
1389         if (root->reloc_root) {
1390                 reloc_root = root->reloc_root;
1391                 reloc_root->last_trans = trans->transid;
1392                 return 0;
1393         }
1394
1395         if (!rc || !rc->create_reloc_tree ||
1396             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1397                 return 0;
1398
1399         if (!trans->block_rsv) {
1400                 trans->block_rsv = rc->block_rsv;
1401                 clear_rsv = 1;
1402         }
1403         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1404         if (clear_rsv)
1405                 trans->block_rsv = NULL;
1406
1407         ret = __add_reloc_root(reloc_root);
1408         BUG_ON(ret < 0);
1409         root->reloc_root = reloc_root;
1410         return 0;
1411 }
1412
1413 /*
1414  * update root item of reloc tree
1415  */
1416 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1417                             struct btrfs_root *root)
1418 {
1419         struct btrfs_root *reloc_root;
1420         struct btrfs_root_item *root_item;
1421         int del = 0;
1422         int ret;
1423
1424         if (!root->reloc_root)
1425                 goto out;
1426
1427         reloc_root = root->reloc_root;
1428         root_item = &reloc_root->root_item;
1429
1430         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1431             btrfs_root_refs(root_item) == 0) {
1432                 root->reloc_root = NULL;
1433                 del = 1;
1434         }
1435
1436         __update_reloc_root(reloc_root, del);
1437
1438         if (reloc_root->commit_root != reloc_root->node) {
1439                 btrfs_set_root_node(root_item, reloc_root->node);
1440                 free_extent_buffer(reloc_root->commit_root);
1441                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1442         }
1443
1444         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1445                                 &reloc_root->root_key, root_item);
1446         BUG_ON(ret);
1447
1448 out:
1449         return 0;
1450 }
1451
1452 /*
1453  * helper to find first cached inode with inode number >= objectid
1454  * in a subvolume
1455  */
1456 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1457 {
1458         struct rb_node *node;
1459         struct rb_node *prev;
1460         struct btrfs_inode *entry;
1461         struct inode *inode;
1462
1463         spin_lock(&root->inode_lock);
1464 again:
1465         node = root->inode_tree.rb_node;
1466         prev = NULL;
1467         while (node) {
1468                 prev = node;
1469                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1470
1471                 if (objectid < btrfs_ino(&entry->vfs_inode))
1472                         node = node->rb_left;
1473                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1474                         node = node->rb_right;
1475                 else
1476                         break;
1477         }
1478         if (!node) {
1479                 while (prev) {
1480                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1481                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1482                                 node = prev;
1483                                 break;
1484                         }
1485                         prev = rb_next(prev);
1486                 }
1487         }
1488         while (node) {
1489                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1490                 inode = igrab(&entry->vfs_inode);
1491                 if (inode) {
1492                         spin_unlock(&root->inode_lock);
1493                         return inode;
1494                 }
1495
1496                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1497                 if (cond_resched_lock(&root->inode_lock))
1498                         goto again;
1499
1500                 node = rb_next(node);
1501         }
1502         spin_unlock(&root->inode_lock);
1503         return NULL;
1504 }
1505
1506 static int in_block_group(u64 bytenr,
1507                           struct btrfs_block_group_cache *block_group)
1508 {
1509         if (bytenr >= block_group->key.objectid &&
1510             bytenr < block_group->key.objectid + block_group->key.offset)
1511                 return 1;
1512         return 0;
1513 }
1514
1515 /*
1516  * get new location of data
1517  */
1518 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1519                             u64 bytenr, u64 num_bytes)
1520 {
1521         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1522         struct btrfs_path *path;
1523         struct btrfs_file_extent_item *fi;
1524         struct extent_buffer *leaf;
1525         int ret;
1526
1527         path = btrfs_alloc_path();
1528         if (!path)
1529                 return -ENOMEM;
1530
1531         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1532         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1533                                        bytenr, 0);
1534         if (ret < 0)
1535                 goto out;
1536         if (ret > 0) {
1537                 ret = -ENOENT;
1538                 goto out;
1539         }
1540
1541         leaf = path->nodes[0];
1542         fi = btrfs_item_ptr(leaf, path->slots[0],
1543                             struct btrfs_file_extent_item);
1544
1545         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1546                btrfs_file_extent_compression(leaf, fi) ||
1547                btrfs_file_extent_encryption(leaf, fi) ||
1548                btrfs_file_extent_other_encoding(leaf, fi));
1549
1550         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1551                 ret = 1;
1552                 goto out;
1553         }
1554
1555         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1556         ret = 0;
1557 out:
1558         btrfs_free_path(path);
1559         return ret;
1560 }
1561
1562 /*
1563  * update file extent items in the tree leaf to point to
1564  * the new locations.
1565  */
1566 static noinline_for_stack
1567 int replace_file_extents(struct btrfs_trans_handle *trans,
1568                          struct reloc_control *rc,
1569                          struct btrfs_root *root,
1570                          struct extent_buffer *leaf)
1571 {
1572         struct btrfs_key key;
1573         struct btrfs_file_extent_item *fi;
1574         struct inode *inode = NULL;
1575         u64 parent;
1576         u64 bytenr;
1577         u64 new_bytenr = 0;
1578         u64 num_bytes;
1579         u64 end;
1580         u32 nritems;
1581         u32 i;
1582         int ret;
1583         int first = 1;
1584         int dirty = 0;
1585
1586         if (rc->stage != UPDATE_DATA_PTRS)
1587                 return 0;
1588
1589         /* reloc trees always use full backref */
1590         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1591                 parent = leaf->start;
1592         else
1593                 parent = 0;
1594
1595         nritems = btrfs_header_nritems(leaf);
1596         for (i = 0; i < nritems; i++) {
1597                 cond_resched();
1598                 btrfs_item_key_to_cpu(leaf, &key, i);
1599                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1600                         continue;
1601                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1602                 if (btrfs_file_extent_type(leaf, fi) ==
1603                     BTRFS_FILE_EXTENT_INLINE)
1604                         continue;
1605                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1606                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1607                 if (bytenr == 0)
1608                         continue;
1609                 if (!in_block_group(bytenr, rc->block_group))
1610                         continue;
1611
1612                 /*
1613                  * if we are modifying block in fs tree, wait for readpage
1614                  * to complete and drop the extent cache
1615                  */
1616                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1617                         if (first) {
1618                                 inode = find_next_inode(root, key.objectid);
1619                                 first = 0;
1620                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1621                                 btrfs_add_delayed_iput(inode);
1622                                 inode = find_next_inode(root, key.objectid);
1623                         }
1624                         if (inode && btrfs_ino(inode) == key.objectid) {
1625                                 end = key.offset +
1626                                       btrfs_file_extent_num_bytes(leaf, fi);
1627                                 WARN_ON(!IS_ALIGNED(key.offset,
1628                                                     root->sectorsize));
1629                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1630                                 end--;
1631                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1632                                                       key.offset, end);
1633                                 if (!ret)
1634                                         continue;
1635
1636                                 btrfs_drop_extent_cache(inode, key.offset, end,
1637                                                         1);
1638                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1639                                               key.offset, end);
1640                         }
1641                 }
1642
1643                 ret = get_new_location(rc->data_inode, &new_bytenr,
1644                                        bytenr, num_bytes);
1645                 if (ret > 0) {
1646                         WARN_ON(1);
1647                         continue;
1648                 }
1649                 BUG_ON(ret < 0);
1650
1651                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1652                 dirty = 1;
1653
1654                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1655                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1656                                            num_bytes, parent,
1657                                            btrfs_header_owner(leaf),
1658                                            key.objectid, key.offset, 1);
1659                 BUG_ON(ret);
1660
1661                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1662                                         parent, btrfs_header_owner(leaf),
1663                                         key.objectid, key.offset, 1);
1664                 BUG_ON(ret);
1665         }
1666         if (dirty)
1667                 btrfs_mark_buffer_dirty(leaf);
1668         if (inode)
1669                 btrfs_add_delayed_iput(inode);
1670         return 0;
1671 }
1672
1673 static noinline_for_stack
1674 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1675                      struct btrfs_path *path, int level)
1676 {
1677         struct btrfs_disk_key key1;
1678         struct btrfs_disk_key key2;
1679         btrfs_node_key(eb, &key1, slot);
1680         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1681         return memcmp(&key1, &key2, sizeof(key1));
1682 }
1683
1684 /*
1685  * try to replace tree blocks in fs tree with the new blocks
1686  * in reloc tree. tree blocks haven't been modified since the
1687  * reloc tree was create can be replaced.
1688  *
1689  * if a block was replaced, level of the block + 1 is returned.
1690  * if no block got replaced, 0 is returned. if there are other
1691  * errors, a negative error number is returned.
1692  */
1693 static noinline_for_stack
1694 int replace_path(struct btrfs_trans_handle *trans,
1695                  struct btrfs_root *dest, struct btrfs_root *src,
1696                  struct btrfs_path *path, struct btrfs_key *next_key,
1697                  int lowest_level, int max_level)
1698 {
1699         struct extent_buffer *eb;
1700         struct extent_buffer *parent;
1701         struct btrfs_key key;
1702         u64 old_bytenr;
1703         u64 new_bytenr;
1704         u64 old_ptr_gen;
1705         u64 new_ptr_gen;
1706         u64 last_snapshot;
1707         u32 blocksize;
1708         int cow = 0;
1709         int level;
1710         int ret;
1711         int slot;
1712
1713         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1714         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1715
1716         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1717 again:
1718         slot = path->slots[lowest_level];
1719         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1720
1721         eb = btrfs_lock_root_node(dest);
1722         btrfs_set_lock_blocking(eb);
1723         level = btrfs_header_level(eb);
1724
1725         if (level < lowest_level) {
1726                 btrfs_tree_unlock(eb);
1727                 free_extent_buffer(eb);
1728                 return 0;
1729         }
1730
1731         if (cow) {
1732                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1733                 BUG_ON(ret);
1734         }
1735         btrfs_set_lock_blocking(eb);
1736
1737         if (next_key) {
1738                 next_key->objectid = (u64)-1;
1739                 next_key->type = (u8)-1;
1740                 next_key->offset = (u64)-1;
1741         }
1742
1743         parent = eb;
1744         while (1) {
1745                 level = btrfs_header_level(parent);
1746                 BUG_ON(level < lowest_level);
1747
1748                 ret = btrfs_bin_search(parent, &key, level, &slot);
1749                 if (ret && slot > 0)
1750                         slot--;
1751
1752                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1753                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1754
1755                 old_bytenr = btrfs_node_blockptr(parent, slot);
1756                 blocksize = btrfs_level_size(dest, level - 1);
1757                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1758
1759                 if (level <= max_level) {
1760                         eb = path->nodes[level];
1761                         new_bytenr = btrfs_node_blockptr(eb,
1762                                                         path->slots[level]);
1763                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1764                                                         path->slots[level]);
1765                 } else {
1766                         new_bytenr = 0;
1767                         new_ptr_gen = 0;
1768                 }
1769
1770                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1771                         WARN_ON(1);
1772                         ret = level;
1773                         break;
1774                 }
1775
1776                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1777                     memcmp_node_keys(parent, slot, path, level)) {
1778                         if (level <= lowest_level) {
1779                                 ret = 0;
1780                                 break;
1781                         }
1782
1783                         eb = read_tree_block(dest, old_bytenr, blocksize,
1784                                              old_ptr_gen);
1785                         if (!eb || !extent_buffer_uptodate(eb)) {
1786                                 ret = (!eb) ? -ENOMEM : -EIO;
1787                                 free_extent_buffer(eb);
1788                                 break;
1789                         }
1790                         btrfs_tree_lock(eb);
1791                         if (cow) {
1792                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1793                                                       slot, &eb);
1794                                 BUG_ON(ret);
1795                         }
1796                         btrfs_set_lock_blocking(eb);
1797
1798                         btrfs_tree_unlock(parent);
1799                         free_extent_buffer(parent);
1800
1801                         parent = eb;
1802                         continue;
1803                 }
1804
1805                 if (!cow) {
1806                         btrfs_tree_unlock(parent);
1807                         free_extent_buffer(parent);
1808                         cow = 1;
1809                         goto again;
1810                 }
1811
1812                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1813                                       path->slots[level]);
1814                 btrfs_release_path(path);
1815
1816                 path->lowest_level = level;
1817                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1818                 path->lowest_level = 0;
1819                 BUG_ON(ret);
1820
1821                 /*
1822                  * swap blocks in fs tree and reloc tree.
1823                  */
1824                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1825                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1826                 btrfs_mark_buffer_dirty(parent);
1827
1828                 btrfs_set_node_blockptr(path->nodes[level],
1829                                         path->slots[level], old_bytenr);
1830                 btrfs_set_node_ptr_generation(path->nodes[level],
1831                                               path->slots[level], old_ptr_gen);
1832                 btrfs_mark_buffer_dirty(path->nodes[level]);
1833
1834                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1835                                         path->nodes[level]->start,
1836                                         src->root_key.objectid, level - 1, 0,
1837                                         1);
1838                 BUG_ON(ret);
1839                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1840                                         0, dest->root_key.objectid, level - 1,
1841                                         0, 1);
1842                 BUG_ON(ret);
1843
1844                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1845                                         path->nodes[level]->start,
1846                                         src->root_key.objectid, level - 1, 0,
1847                                         1);
1848                 BUG_ON(ret);
1849
1850                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1851                                         0, dest->root_key.objectid, level - 1,
1852                                         0, 1);
1853                 BUG_ON(ret);
1854
1855                 btrfs_unlock_up_safe(path, 0);
1856
1857                 ret = level;
1858                 break;
1859         }
1860         btrfs_tree_unlock(parent);
1861         free_extent_buffer(parent);
1862         return ret;
1863 }
1864
1865 /*
1866  * helper to find next relocated block in reloc tree
1867  */
1868 static noinline_for_stack
1869 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1870                        int *level)
1871 {
1872         struct extent_buffer *eb;
1873         int i;
1874         u64 last_snapshot;
1875         u32 nritems;
1876
1877         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1878
1879         for (i = 0; i < *level; i++) {
1880                 free_extent_buffer(path->nodes[i]);
1881                 path->nodes[i] = NULL;
1882         }
1883
1884         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1885                 eb = path->nodes[i];
1886                 nritems = btrfs_header_nritems(eb);
1887                 while (path->slots[i] + 1 < nritems) {
1888                         path->slots[i]++;
1889                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1890                             last_snapshot)
1891                                 continue;
1892
1893                         *level = i;
1894                         return 0;
1895                 }
1896                 free_extent_buffer(path->nodes[i]);
1897                 path->nodes[i] = NULL;
1898         }
1899         return 1;
1900 }
1901
1902 /*
1903  * walk down reloc tree to find relocated block of lowest level
1904  */
1905 static noinline_for_stack
1906 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1907                          int *level)
1908 {
1909         struct extent_buffer *eb = NULL;
1910         int i;
1911         u64 bytenr;
1912         u64 ptr_gen = 0;
1913         u64 last_snapshot;
1914         u32 blocksize;
1915         u32 nritems;
1916
1917         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1918
1919         for (i = *level; i > 0; i--) {
1920                 eb = path->nodes[i];
1921                 nritems = btrfs_header_nritems(eb);
1922                 while (path->slots[i] < nritems) {
1923                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1924                         if (ptr_gen > last_snapshot)
1925                                 break;
1926                         path->slots[i]++;
1927                 }
1928                 if (path->slots[i] >= nritems) {
1929                         if (i == *level)
1930                                 break;
1931                         *level = i + 1;
1932                         return 0;
1933                 }
1934                 if (i == 1) {
1935                         *level = i;
1936                         return 0;
1937                 }
1938
1939                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1940                 blocksize = btrfs_level_size(root, i - 1);
1941                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1942                 if (!eb || !extent_buffer_uptodate(eb)) {
1943                         free_extent_buffer(eb);
1944                         return -EIO;
1945                 }
1946                 BUG_ON(btrfs_header_level(eb) != i - 1);
1947                 path->nodes[i - 1] = eb;
1948                 path->slots[i - 1] = 0;
1949         }
1950         return 1;
1951 }
1952
1953 /*
1954  * invalidate extent cache for file extents whose key in range of
1955  * [min_key, max_key)
1956  */
1957 static int invalidate_extent_cache(struct btrfs_root *root,
1958                                    struct btrfs_key *min_key,
1959                                    struct btrfs_key *max_key)
1960 {
1961         struct inode *inode = NULL;
1962         u64 objectid;
1963         u64 start, end;
1964         u64 ino;
1965
1966         objectid = min_key->objectid;
1967         while (1) {
1968                 cond_resched();
1969                 iput(inode);
1970
1971                 if (objectid > max_key->objectid)
1972                         break;
1973
1974                 inode = find_next_inode(root, objectid);
1975                 if (!inode)
1976                         break;
1977                 ino = btrfs_ino(inode);
1978
1979                 if (ino > max_key->objectid) {
1980                         iput(inode);
1981                         break;
1982                 }
1983
1984                 objectid = ino + 1;
1985                 if (!S_ISREG(inode->i_mode))
1986                         continue;
1987
1988                 if (unlikely(min_key->objectid == ino)) {
1989                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1990                                 continue;
1991                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1992                                 start = 0;
1993                         else {
1994                                 start = min_key->offset;
1995                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1996                         }
1997                 } else {
1998                         start = 0;
1999                 }
2000
2001                 if (unlikely(max_key->objectid == ino)) {
2002                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2003                                 continue;
2004                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2005                                 end = (u64)-1;
2006                         } else {
2007                                 if (max_key->offset == 0)
2008                                         continue;
2009                                 end = max_key->offset;
2010                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2011                                 end--;
2012                         }
2013                 } else {
2014                         end = (u64)-1;
2015                 }
2016
2017                 /* the lock_extent waits for readpage to complete */
2018                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2019                 btrfs_drop_extent_cache(inode, start, end, 1);
2020                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2021         }
2022         return 0;
2023 }
2024
2025 static int find_next_key(struct btrfs_path *path, int level,
2026                          struct btrfs_key *key)
2027
2028 {
2029         while (level < BTRFS_MAX_LEVEL) {
2030                 if (!path->nodes[level])
2031                         break;
2032                 if (path->slots[level] + 1 <
2033                     btrfs_header_nritems(path->nodes[level])) {
2034                         btrfs_node_key_to_cpu(path->nodes[level], key,
2035                                               path->slots[level] + 1);
2036                         return 0;
2037                 }
2038                 level++;
2039         }
2040         return 1;
2041 }
2042
2043 /*
2044  * merge the relocated tree blocks in reloc tree with corresponding
2045  * fs tree.
2046  */
2047 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2048                                                struct btrfs_root *root)
2049 {
2050         LIST_HEAD(inode_list);
2051         struct btrfs_key key;
2052         struct btrfs_key next_key;
2053         struct btrfs_trans_handle *trans;
2054         struct btrfs_root *reloc_root;
2055         struct btrfs_root_item *root_item;
2056         struct btrfs_path *path;
2057         struct extent_buffer *leaf;
2058         int level;
2059         int max_level;
2060         int replaced = 0;
2061         int ret;
2062         int err = 0;
2063         u32 min_reserved;
2064
2065         path = btrfs_alloc_path();
2066         if (!path)
2067                 return -ENOMEM;
2068         path->reada = 1;
2069
2070         reloc_root = root->reloc_root;
2071         root_item = &reloc_root->root_item;
2072
2073         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2074                 level = btrfs_root_level(root_item);
2075                 extent_buffer_get(reloc_root->node);
2076                 path->nodes[level] = reloc_root->node;
2077                 path->slots[level] = 0;
2078         } else {
2079                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2080
2081                 level = root_item->drop_level;
2082                 BUG_ON(level == 0);
2083                 path->lowest_level = level;
2084                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2085                 path->lowest_level = 0;
2086                 if (ret < 0) {
2087                         btrfs_free_path(path);
2088                         return ret;
2089                 }
2090
2091                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2092                                       path->slots[level]);
2093                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2094
2095                 btrfs_unlock_up_safe(path, 0);
2096         }
2097
2098         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2099         memset(&next_key, 0, sizeof(next_key));
2100
2101         while (1) {
2102                 trans = btrfs_start_transaction(root, 0);
2103                 BUG_ON(IS_ERR(trans));
2104                 trans->block_rsv = rc->block_rsv;
2105
2106                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2107                                              BTRFS_RESERVE_FLUSH_ALL);
2108                 if (ret) {
2109                         BUG_ON(ret != -EAGAIN);
2110                         ret = btrfs_commit_transaction(trans, root);
2111                         BUG_ON(ret);
2112                         continue;
2113                 }
2114
2115                 replaced = 0;
2116                 max_level = level;
2117
2118                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2119                 if (ret < 0) {
2120                         err = ret;
2121                         goto out;
2122                 }
2123                 if (ret > 0)
2124                         break;
2125
2126                 if (!find_next_key(path, level, &key) &&
2127                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2128                         ret = 0;
2129                 } else {
2130                         ret = replace_path(trans, root, reloc_root, path,
2131                                            &next_key, level, max_level);
2132                 }
2133                 if (ret < 0) {
2134                         err = ret;
2135                         goto out;
2136                 }
2137
2138                 if (ret > 0) {
2139                         level = ret;
2140                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2141                                               path->slots[level]);
2142                         replaced = 1;
2143                 }
2144
2145                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2146                 if (ret > 0)
2147                         break;
2148
2149                 BUG_ON(level == 0);
2150                 /*
2151                  * save the merging progress in the drop_progress.
2152                  * this is OK since root refs == 1 in this case.
2153                  */
2154                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2155                                path->slots[level]);
2156                 root_item->drop_level = level;
2157
2158                 btrfs_end_transaction_throttle(trans, root);
2159
2160                 btrfs_btree_balance_dirty(root);
2161
2162                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2163                         invalidate_extent_cache(root, &key, &next_key);
2164         }
2165
2166         /*
2167          * handle the case only one block in the fs tree need to be
2168          * relocated and the block is tree root.
2169          */
2170         leaf = btrfs_lock_root_node(root);
2171         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2172         btrfs_tree_unlock(leaf);
2173         free_extent_buffer(leaf);
2174         if (ret < 0)
2175                 err = ret;
2176 out:
2177         btrfs_free_path(path);
2178
2179         if (err == 0) {
2180                 memset(&root_item->drop_progress, 0,
2181                        sizeof(root_item->drop_progress));
2182                 root_item->drop_level = 0;
2183                 btrfs_set_root_refs(root_item, 0);
2184                 btrfs_update_reloc_root(trans, root);
2185         }
2186
2187         btrfs_end_transaction_throttle(trans, root);
2188
2189         btrfs_btree_balance_dirty(root);
2190
2191         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2192                 invalidate_extent_cache(root, &key, &next_key);
2193
2194         return err;
2195 }
2196
2197 static noinline_for_stack
2198 int prepare_to_merge(struct reloc_control *rc, int err)
2199 {
2200         struct btrfs_root *root = rc->extent_root;
2201         struct btrfs_root *reloc_root;
2202         struct btrfs_trans_handle *trans;
2203         LIST_HEAD(reloc_roots);
2204         u64 num_bytes = 0;
2205         int ret;
2206
2207         mutex_lock(&root->fs_info->reloc_mutex);
2208         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2209         rc->merging_rsv_size += rc->nodes_relocated * 2;
2210         mutex_unlock(&root->fs_info->reloc_mutex);
2211
2212 again:
2213         if (!err) {
2214                 num_bytes = rc->merging_rsv_size;
2215                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2216                                           BTRFS_RESERVE_FLUSH_ALL);
2217                 if (ret)
2218                         err = ret;
2219         }
2220
2221         trans = btrfs_join_transaction(rc->extent_root);
2222         if (IS_ERR(trans)) {
2223                 if (!err)
2224                         btrfs_block_rsv_release(rc->extent_root,
2225                                                 rc->block_rsv, num_bytes);
2226                 return PTR_ERR(trans);
2227         }
2228
2229         if (!err) {
2230                 if (num_bytes != rc->merging_rsv_size) {
2231                         btrfs_end_transaction(trans, rc->extent_root);
2232                         btrfs_block_rsv_release(rc->extent_root,
2233                                                 rc->block_rsv, num_bytes);
2234                         goto again;
2235                 }
2236         }
2237
2238         rc->merge_reloc_tree = 1;
2239
2240         while (!list_empty(&rc->reloc_roots)) {
2241                 reloc_root = list_entry(rc->reloc_roots.next,
2242                                         struct btrfs_root, root_list);
2243                 list_del_init(&reloc_root->root_list);
2244
2245                 root = read_fs_root(reloc_root->fs_info,
2246                                     reloc_root->root_key.offset);
2247                 BUG_ON(IS_ERR(root));
2248                 BUG_ON(root->reloc_root != reloc_root);
2249
2250                 /*
2251                  * set reference count to 1, so btrfs_recover_relocation
2252                  * knows it should resumes merging
2253                  */
2254                 if (!err)
2255                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2256                 btrfs_update_reloc_root(trans, root);
2257
2258                 list_add(&reloc_root->root_list, &reloc_roots);
2259         }
2260
2261         list_splice(&reloc_roots, &rc->reloc_roots);
2262
2263         if (!err)
2264                 btrfs_commit_transaction(trans, rc->extent_root);
2265         else
2266                 btrfs_end_transaction(trans, rc->extent_root);
2267         return err;
2268 }
2269
2270 static noinline_for_stack
2271 void free_reloc_roots(struct list_head *list)
2272 {
2273         struct btrfs_root *reloc_root;
2274
2275         while (!list_empty(list)) {
2276                 reloc_root = list_entry(list->next, struct btrfs_root,
2277                                         root_list);
2278                 __update_reloc_root(reloc_root, 1);
2279                 free_extent_buffer(reloc_root->node);
2280                 free_extent_buffer(reloc_root->commit_root);
2281                 kfree(reloc_root);
2282         }
2283 }
2284
2285 static noinline_for_stack
2286 int merge_reloc_roots(struct reloc_control *rc)
2287 {
2288         struct btrfs_trans_handle *trans;
2289         struct btrfs_root *root;
2290         struct btrfs_root *reloc_root;
2291         u64 last_snap;
2292         u64 otransid;
2293         u64 objectid;
2294         LIST_HEAD(reloc_roots);
2295         int found = 0;
2296         int ret = 0;
2297 again:
2298         root = rc->extent_root;
2299
2300         /*
2301          * this serializes us with btrfs_record_root_in_transaction,
2302          * we have to make sure nobody is in the middle of
2303          * adding their roots to the list while we are
2304          * doing this splice
2305          */
2306         mutex_lock(&root->fs_info->reloc_mutex);
2307         list_splice_init(&rc->reloc_roots, &reloc_roots);
2308         mutex_unlock(&root->fs_info->reloc_mutex);
2309
2310         while (!list_empty(&reloc_roots)) {
2311                 found = 1;
2312                 reloc_root = list_entry(reloc_roots.next,
2313                                         struct btrfs_root, root_list);
2314
2315                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2316                         root = read_fs_root(reloc_root->fs_info,
2317                                             reloc_root->root_key.offset);
2318                         BUG_ON(IS_ERR(root));
2319                         BUG_ON(root->reloc_root != reloc_root);
2320
2321                         ret = merge_reloc_root(rc, root);
2322                         if (ret) {
2323                                 __update_reloc_root(reloc_root, 1);
2324                                 free_extent_buffer(reloc_root->node);
2325                                 free_extent_buffer(reloc_root->commit_root);
2326                                 kfree(reloc_root);
2327                                 goto out;
2328                         }
2329                 } else {
2330                         list_del_init(&reloc_root->root_list);
2331                 }
2332
2333                 /*
2334                  * we keep the old last snapshod transid in rtranid when we
2335                  * created the relocation tree.
2336                  */
2337                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2338                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2339                 objectid = reloc_root->root_key.offset;
2340
2341                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2342                 if (ret < 0) {
2343                         if (list_empty(&reloc_root->root_list))
2344                                 list_add_tail(&reloc_root->root_list,
2345                                               &reloc_roots);
2346                         goto out;
2347                 } else if (!ret) {
2348                         /*
2349                          * recover the last snapshot tranid to avoid
2350                          * the space balance break NOCOW.
2351                          */
2352                         root = read_fs_root(rc->extent_root->fs_info,
2353                                             objectid);
2354                         if (IS_ERR(root))
2355                                 continue;
2356
2357                         if (btrfs_root_refs(&root->root_item) == 0)
2358                                 continue;
2359
2360                         trans = btrfs_join_transaction(root);
2361                         BUG_ON(IS_ERR(trans));
2362
2363                         /* Check if the fs/file tree was snapshoted or not. */
2364                         if (btrfs_root_last_snapshot(&root->root_item) ==
2365                             otransid - 1)
2366                                 btrfs_set_root_last_snapshot(&root->root_item,
2367                                                              last_snap);
2368
2369                         btrfs_end_transaction(trans, root);
2370                 }
2371         }
2372
2373         if (found) {
2374                 found = 0;
2375                 goto again;
2376         }
2377 out:
2378         if (ret) {
2379                 btrfs_std_error(root->fs_info, ret);
2380                 if (!list_empty(&reloc_roots))
2381                         free_reloc_roots(&reloc_roots);
2382         }
2383
2384         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2385         return ret;
2386 }
2387
2388 static void free_block_list(struct rb_root *blocks)
2389 {
2390         struct tree_block *block;
2391         struct rb_node *rb_node;
2392         while ((rb_node = rb_first(blocks))) {
2393                 block = rb_entry(rb_node, struct tree_block, rb_node);
2394                 rb_erase(rb_node, blocks);
2395                 kfree(block);
2396         }
2397 }
2398
2399 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2400                                       struct btrfs_root *reloc_root)
2401 {
2402         struct btrfs_root *root;
2403
2404         if (reloc_root->last_trans == trans->transid)
2405                 return 0;
2406
2407         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2408         BUG_ON(IS_ERR(root));
2409         BUG_ON(root->reloc_root != reloc_root);
2410
2411         return btrfs_record_root_in_trans(trans, root);
2412 }
2413
2414 static noinline_for_stack
2415 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2416                                      struct reloc_control *rc,
2417                                      struct backref_node *node,
2418                                      struct backref_edge *edges[], int *nr)
2419 {
2420         struct backref_node *next;
2421         struct btrfs_root *root;
2422         int index = 0;
2423
2424         next = node;
2425         while (1) {
2426                 cond_resched();
2427                 next = walk_up_backref(next, edges, &index);
2428                 root = next->root;
2429                 BUG_ON(!root);
2430                 BUG_ON(!root->ref_cows);
2431
2432                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2433                         record_reloc_root_in_trans(trans, root);
2434                         break;
2435                 }
2436
2437                 btrfs_record_root_in_trans(trans, root);
2438                 root = root->reloc_root;
2439
2440                 if (next->new_bytenr != root->node->start) {
2441                         BUG_ON(next->new_bytenr);
2442                         BUG_ON(!list_empty(&next->list));
2443                         next->new_bytenr = root->node->start;
2444                         next->root = root;
2445                         list_add_tail(&next->list,
2446                                       &rc->backref_cache.changed);
2447                         __mark_block_processed(rc, next);
2448                         break;
2449                 }
2450
2451                 WARN_ON(1);
2452                 root = NULL;
2453                 next = walk_down_backref(edges, &index);
2454                 if (!next || next->level <= node->level)
2455                         break;
2456         }
2457         if (!root)
2458                 return NULL;
2459
2460         *nr = index;
2461         next = node;
2462         /* setup backref node path for btrfs_reloc_cow_block */
2463         while (1) {
2464                 rc->backref_cache.path[next->level] = next;
2465                 if (--index < 0)
2466                         break;
2467                 next = edges[index]->node[UPPER];
2468         }
2469         return root;
2470 }
2471
2472 /*
2473  * select a tree root for relocation. return NULL if the block
2474  * is reference counted. we should use do_relocation() in this
2475  * case. return a tree root pointer if the block isn't reference
2476  * counted. return -ENOENT if the block is root of reloc tree.
2477  */
2478 static noinline_for_stack
2479 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2480                                    struct backref_node *node)
2481 {
2482         struct backref_node *next;
2483         struct btrfs_root *root;
2484         struct btrfs_root *fs_root = NULL;
2485         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2486         int index = 0;
2487
2488         next = node;
2489         while (1) {
2490                 cond_resched();
2491                 next = walk_up_backref(next, edges, &index);
2492                 root = next->root;
2493                 BUG_ON(!root);
2494
2495                 /* no other choice for non-references counted tree */
2496                 if (!root->ref_cows)
2497                         return root;
2498
2499                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2500                         fs_root = root;
2501
2502                 if (next != node)
2503                         return NULL;
2504
2505                 next = walk_down_backref(edges, &index);
2506                 if (!next || next->level <= node->level)
2507                         break;
2508         }
2509
2510         if (!fs_root)
2511                 return ERR_PTR(-ENOENT);
2512         return fs_root;
2513 }
2514
2515 static noinline_for_stack
2516 u64 calcu_metadata_size(struct reloc_control *rc,
2517                         struct backref_node *node, int reserve)
2518 {
2519         struct backref_node *next = node;
2520         struct backref_edge *edge;
2521         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2522         u64 num_bytes = 0;
2523         int index = 0;
2524
2525         BUG_ON(reserve && node->processed);
2526
2527         while (next) {
2528                 cond_resched();
2529                 while (1) {
2530                         if (next->processed && (reserve || next != node))
2531                                 break;
2532
2533                         num_bytes += btrfs_level_size(rc->extent_root,
2534                                                       next->level);
2535
2536                         if (list_empty(&next->upper))
2537                                 break;
2538
2539                         edge = list_entry(next->upper.next,
2540                                           struct backref_edge, list[LOWER]);
2541                         edges[index++] = edge;
2542                         next = edge->node[UPPER];
2543                 }
2544                 next = walk_down_backref(edges, &index);
2545         }
2546         return num_bytes;
2547 }
2548
2549 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2550                                   struct reloc_control *rc,
2551                                   struct backref_node *node)
2552 {
2553         struct btrfs_root *root = rc->extent_root;
2554         u64 num_bytes;
2555         int ret;
2556
2557         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2558
2559         trans->block_rsv = rc->block_rsv;
2560         ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2561                                   BTRFS_RESERVE_FLUSH_ALL);
2562         if (ret) {
2563                 if (ret == -EAGAIN)
2564                         rc->commit_transaction = 1;
2565                 return ret;
2566         }
2567
2568         return 0;
2569 }
2570
2571 static void release_metadata_space(struct reloc_control *rc,
2572                                    struct backref_node *node)
2573 {
2574         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2575         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2576 }
2577
2578 /*
2579  * relocate a block tree, and then update pointers in upper level
2580  * blocks that reference the block to point to the new location.
2581  *
2582  * if called by link_to_upper, the block has already been relocated.
2583  * in that case this function just updates pointers.
2584  */
2585 static int do_relocation(struct btrfs_trans_handle *trans,
2586                          struct reloc_control *rc,
2587                          struct backref_node *node,
2588                          struct btrfs_key *key,
2589                          struct btrfs_path *path, int lowest)
2590 {
2591         struct backref_node *upper;
2592         struct backref_edge *edge;
2593         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2594         struct btrfs_root *root;
2595         struct extent_buffer *eb;
2596         u32 blocksize;
2597         u64 bytenr;
2598         u64 generation;
2599         int nr;
2600         int slot;
2601         int ret;
2602         int err = 0;
2603
2604         BUG_ON(lowest && node->eb);
2605
2606         path->lowest_level = node->level + 1;
2607         rc->backref_cache.path[node->level] = node;
2608         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2609                 cond_resched();
2610
2611                 upper = edge->node[UPPER];
2612                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2613                 BUG_ON(!root);
2614
2615                 if (upper->eb && !upper->locked) {
2616                         if (!lowest) {
2617                                 ret = btrfs_bin_search(upper->eb, key,
2618                                                        upper->level, &slot);
2619                                 BUG_ON(ret);
2620                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2621                                 if (node->eb->start == bytenr)
2622                                         goto next;
2623                         }
2624                         drop_node_buffer(upper);
2625                 }
2626
2627                 if (!upper->eb) {
2628                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2629                         if (ret < 0) {
2630                                 err = ret;
2631                                 break;
2632                         }
2633                         BUG_ON(ret > 0);
2634
2635                         if (!upper->eb) {
2636                                 upper->eb = path->nodes[upper->level];
2637                                 path->nodes[upper->level] = NULL;
2638                         } else {
2639                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2640                         }
2641
2642                         upper->locked = 1;
2643                         path->locks[upper->level] = 0;
2644
2645                         slot = path->slots[upper->level];
2646                         btrfs_release_path(path);
2647                 } else {
2648                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2649                                                &slot);
2650                         BUG_ON(ret);
2651                 }
2652
2653                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2654                 if (lowest) {
2655                         BUG_ON(bytenr != node->bytenr);
2656                 } else {
2657                         if (node->eb->start == bytenr)
2658                                 goto next;
2659                 }
2660
2661                 blocksize = btrfs_level_size(root, node->level);
2662                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2663                 eb = read_tree_block(root, bytenr, blocksize, generation);
2664                 if (!eb || !extent_buffer_uptodate(eb)) {
2665                         free_extent_buffer(eb);
2666                         err = -EIO;
2667                         goto next;
2668                 }
2669                 btrfs_tree_lock(eb);
2670                 btrfs_set_lock_blocking(eb);
2671
2672                 if (!node->eb) {
2673                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2674                                               slot, &eb);
2675                         btrfs_tree_unlock(eb);
2676                         free_extent_buffer(eb);
2677                         if (ret < 0) {
2678                                 err = ret;
2679                                 goto next;
2680                         }
2681                         BUG_ON(node->eb != eb);
2682                 } else {
2683                         btrfs_set_node_blockptr(upper->eb, slot,
2684                                                 node->eb->start);
2685                         btrfs_set_node_ptr_generation(upper->eb, slot,
2686                                                       trans->transid);
2687                         btrfs_mark_buffer_dirty(upper->eb);
2688
2689                         ret = btrfs_inc_extent_ref(trans, root,
2690                                                 node->eb->start, blocksize,
2691                                                 upper->eb->start,
2692                                                 btrfs_header_owner(upper->eb),
2693                                                 node->level, 0, 1);
2694                         BUG_ON(ret);
2695
2696                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2697                         BUG_ON(ret);
2698                 }
2699 next:
2700                 if (!upper->pending)
2701                         drop_node_buffer(upper);
2702                 else
2703                         unlock_node_buffer(upper);
2704                 if (err)
2705                         break;
2706         }
2707
2708         if (!err && node->pending) {
2709                 drop_node_buffer(node);
2710                 list_move_tail(&node->list, &rc->backref_cache.changed);
2711                 node->pending = 0;
2712         }
2713
2714         path->lowest_level = 0;
2715         BUG_ON(err == -ENOSPC);
2716         return err;
2717 }
2718
2719 static int link_to_upper(struct btrfs_trans_handle *trans,
2720                          struct reloc_control *rc,
2721                          struct backref_node *node,
2722                          struct btrfs_path *path)
2723 {
2724         struct btrfs_key key;
2725
2726         btrfs_node_key_to_cpu(node->eb, &key, 0);
2727         return do_relocation(trans, rc, node, &key, path, 0);
2728 }
2729
2730 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2731                                 struct reloc_control *rc,
2732                                 struct btrfs_path *path, int err)
2733 {
2734         LIST_HEAD(list);
2735         struct backref_cache *cache = &rc->backref_cache;
2736         struct backref_node *node;
2737         int level;
2738         int ret;
2739
2740         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2741                 while (!list_empty(&cache->pending[level])) {
2742                         node = list_entry(cache->pending[level].next,
2743                                           struct backref_node, list);
2744                         list_move_tail(&node->list, &list);
2745                         BUG_ON(!node->pending);
2746
2747                         if (!err) {
2748                                 ret = link_to_upper(trans, rc, node, path);
2749                                 if (ret < 0)
2750                                         err = ret;
2751                         }
2752                 }
2753                 list_splice_init(&list, &cache->pending[level]);
2754         }
2755         return err;
2756 }
2757
2758 static void mark_block_processed(struct reloc_control *rc,
2759                                  u64 bytenr, u32 blocksize)
2760 {
2761         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2762                         EXTENT_DIRTY, GFP_NOFS);
2763 }
2764
2765 static void __mark_block_processed(struct reloc_control *rc,
2766                                    struct backref_node *node)
2767 {
2768         u32 blocksize;
2769         if (node->level == 0 ||
2770             in_block_group(node->bytenr, rc->block_group)) {
2771                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2772                 mark_block_processed(rc, node->bytenr, blocksize);
2773         }
2774         node->processed = 1;
2775 }
2776
2777 /*
2778  * mark a block and all blocks directly/indirectly reference the block
2779  * as processed.
2780  */
2781 static void update_processed_blocks(struct reloc_control *rc,
2782                                     struct backref_node *node)
2783 {
2784         struct backref_node *next = node;
2785         struct backref_edge *edge;
2786         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2787         int index = 0;
2788
2789         while (next) {
2790                 cond_resched();
2791                 while (1) {
2792                         if (next->processed)
2793                                 break;
2794
2795                         __mark_block_processed(rc, next);
2796
2797                         if (list_empty(&next->upper))
2798                                 break;
2799
2800                         edge = list_entry(next->upper.next,
2801                                           struct backref_edge, list[LOWER]);
2802                         edges[index++] = edge;
2803                         next = edge->node[UPPER];
2804                 }
2805                 next = walk_down_backref(edges, &index);
2806         }
2807 }
2808
2809 static int tree_block_processed(u64 bytenr, u32 blocksize,
2810                                 struct reloc_control *rc)
2811 {
2812         if (test_range_bit(&rc->processed_blocks, bytenr,
2813                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2814                 return 1;
2815         return 0;
2816 }
2817
2818 static int get_tree_block_key(struct reloc_control *rc,
2819                               struct tree_block *block)
2820 {
2821         struct extent_buffer *eb;
2822
2823         BUG_ON(block->key_ready);
2824         eb = read_tree_block(rc->extent_root, block->bytenr,
2825                              block->key.objectid, block->key.offset);
2826         if (!eb || !extent_buffer_uptodate(eb)) {
2827                 free_extent_buffer(eb);
2828                 return -EIO;
2829         }
2830         WARN_ON(btrfs_header_level(eb) != block->level);
2831         if (block->level == 0)
2832                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2833         else
2834                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2835         free_extent_buffer(eb);
2836         block->key_ready = 1;
2837         return 0;
2838 }
2839
2840 static int reada_tree_block(struct reloc_control *rc,
2841                             struct tree_block *block)
2842 {
2843         BUG_ON(block->key_ready);
2844         if (block->key.type == BTRFS_METADATA_ITEM_KEY)
2845                 readahead_tree_block(rc->extent_root, block->bytenr,
2846                                      block->key.objectid,
2847                                      rc->extent_root->leafsize);
2848         else
2849                 readahead_tree_block(rc->extent_root, block->bytenr,
2850                                      block->key.objectid, block->key.offset);
2851         return 0;
2852 }
2853
2854 /*
2855  * helper function to relocate a tree block
2856  */
2857 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2858                                 struct reloc_control *rc,
2859                                 struct backref_node *node,
2860                                 struct btrfs_key *key,
2861                                 struct btrfs_path *path)
2862 {
2863         struct btrfs_root *root;
2864         int release = 0;
2865         int ret = 0;
2866
2867         if (!node)
2868                 return 0;
2869
2870         BUG_ON(node->processed);
2871         root = select_one_root(trans, node);
2872         if (root == ERR_PTR(-ENOENT)) {
2873                 update_processed_blocks(rc, node);
2874                 goto out;
2875         }
2876
2877         if (!root || root->ref_cows) {
2878                 ret = reserve_metadata_space(trans, rc, node);
2879                 if (ret)
2880                         goto out;
2881                 release = 1;
2882         }
2883
2884         if (root) {
2885                 if (root->ref_cows) {
2886                         BUG_ON(node->new_bytenr);
2887                         BUG_ON(!list_empty(&node->list));
2888                         btrfs_record_root_in_trans(trans, root);
2889                         root = root->reloc_root;
2890                         node->new_bytenr = root->node->start;
2891                         node->root = root;
2892                         list_add_tail(&node->list, &rc->backref_cache.changed);
2893                 } else {
2894                         path->lowest_level = node->level;
2895                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2896                         btrfs_release_path(path);
2897                         if (ret > 0)
2898                                 ret = 0;
2899                 }
2900                 if (!ret)
2901                         update_processed_blocks(rc, node);
2902         } else {
2903                 ret = do_relocation(trans, rc, node, key, path, 1);
2904         }
2905 out:
2906         if (ret || node->level == 0 || node->cowonly) {
2907                 if (release)
2908                         release_metadata_space(rc, node);
2909                 remove_backref_node(&rc->backref_cache, node);
2910         }
2911         return ret;
2912 }
2913
2914 /*
2915  * relocate a list of blocks
2916  */
2917 static noinline_for_stack
2918 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2919                          struct reloc_control *rc, struct rb_root *blocks)
2920 {
2921         struct backref_node *node;
2922         struct btrfs_path *path;
2923         struct tree_block *block;
2924         struct rb_node *rb_node;
2925         int ret;
2926         int err = 0;
2927
2928         path = btrfs_alloc_path();
2929         if (!path) {
2930                 err = -ENOMEM;
2931                 goto out_free_blocks;
2932         }
2933
2934         rb_node = rb_first(blocks);
2935         while (rb_node) {
2936                 block = rb_entry(rb_node, struct tree_block, rb_node);
2937                 if (!block->key_ready)
2938                         reada_tree_block(rc, block);
2939                 rb_node = rb_next(rb_node);
2940         }
2941
2942         rb_node = rb_first(blocks);
2943         while (rb_node) {
2944                 block = rb_entry(rb_node, struct tree_block, rb_node);
2945                 if (!block->key_ready) {
2946                         err = get_tree_block_key(rc, block);
2947                         if (err)
2948                                 goto out_free_path;
2949                 }
2950                 rb_node = rb_next(rb_node);
2951         }
2952
2953         rb_node = rb_first(blocks);
2954         while (rb_node) {
2955                 block = rb_entry(rb_node, struct tree_block, rb_node);
2956
2957                 node = build_backref_tree(rc, &block->key,
2958                                           block->level, block->bytenr);
2959                 if (IS_ERR(node)) {
2960                         err = PTR_ERR(node);
2961                         goto out;
2962                 }
2963
2964                 ret = relocate_tree_block(trans, rc, node, &block->key,
2965                                           path);
2966                 if (ret < 0) {
2967                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2968                                 err = ret;
2969                         goto out;
2970                 }
2971                 rb_node = rb_next(rb_node);
2972         }
2973 out:
2974         err = finish_pending_nodes(trans, rc, path, err);
2975
2976 out_free_path:
2977         btrfs_free_path(path);
2978 out_free_blocks:
2979         free_block_list(blocks);
2980         return err;
2981 }
2982
2983 static noinline_for_stack
2984 int prealloc_file_extent_cluster(struct inode *inode,
2985                                  struct file_extent_cluster *cluster)
2986 {
2987         u64 alloc_hint = 0;
2988         u64 start;
2989         u64 end;
2990         u64 offset = BTRFS_I(inode)->index_cnt;
2991         u64 num_bytes;
2992         int nr = 0;
2993         int ret = 0;
2994
2995         BUG_ON(cluster->start != cluster->boundary[0]);
2996         mutex_lock(&inode->i_mutex);
2997
2998         ret = btrfs_check_data_free_space(inode, cluster->end +
2999                                           1 - cluster->start);
3000         if (ret)
3001                 goto out;
3002
3003         while (nr < cluster->nr) {
3004                 start = cluster->boundary[nr] - offset;
3005                 if (nr + 1 < cluster->nr)
3006                         end = cluster->boundary[nr + 1] - 1 - offset;
3007                 else
3008                         end = cluster->end - offset;
3009
3010                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3011                 num_bytes = end + 1 - start;
3012                 ret = btrfs_prealloc_file_range(inode, 0, start,
3013                                                 num_bytes, num_bytes,
3014                                                 end + 1, &alloc_hint);
3015                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3016                 if (ret)
3017                         break;
3018                 nr++;
3019         }
3020         btrfs_free_reserved_data_space(inode, cluster->end +
3021                                        1 - cluster->start);
3022 out:
3023         mutex_unlock(&inode->i_mutex);
3024         return ret;
3025 }
3026
3027 static noinline_for_stack
3028 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3029                          u64 block_start)
3030 {
3031         struct btrfs_root *root = BTRFS_I(inode)->root;
3032         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3033         struct extent_map *em;
3034         int ret = 0;
3035
3036         em = alloc_extent_map();
3037         if (!em)
3038                 return -ENOMEM;
3039
3040         em->start = start;
3041         em->len = end + 1 - start;
3042         em->block_len = em->len;
3043         em->block_start = block_start;
3044         em->bdev = root->fs_info->fs_devices->latest_bdev;
3045         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3046
3047         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3048         while (1) {
3049                 write_lock(&em_tree->lock);
3050                 ret = add_extent_mapping(em_tree, em, 0);
3051                 write_unlock(&em_tree->lock);
3052                 if (ret != -EEXIST) {
3053                         free_extent_map(em);
3054                         break;
3055                 }
3056                 btrfs_drop_extent_cache(inode, start, end, 0);
3057         }
3058         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3059         return ret;
3060 }
3061
3062 static int relocate_file_extent_cluster(struct inode *inode,
3063                                         struct file_extent_cluster *cluster)
3064 {
3065         u64 page_start;
3066         u64 page_end;
3067         u64 offset = BTRFS_I(inode)->index_cnt;
3068         unsigned long index;
3069         unsigned long last_index;
3070         struct page *page;
3071         struct file_ra_state *ra;
3072         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3073         int nr = 0;
3074         int ret = 0;
3075
3076         if (!cluster->nr)
3077                 return 0;
3078
3079         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3080         if (!ra)
3081                 return -ENOMEM;
3082
3083         ret = prealloc_file_extent_cluster(inode, cluster);
3084         if (ret)
3085                 goto out;
3086
3087         file_ra_state_init(ra, inode->i_mapping);
3088
3089         ret = setup_extent_mapping(inode, cluster->start - offset,
3090                                    cluster->end - offset, cluster->start);
3091         if (ret)
3092                 goto out;
3093
3094         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3095         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3096         while (index <= last_index) {
3097                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3098                 if (ret)
3099                         goto out;
3100
3101                 page = find_lock_page(inode->i_mapping, index);
3102                 if (!page) {
3103                         page_cache_sync_readahead(inode->i_mapping,
3104                                                   ra, NULL, index,
3105                                                   last_index + 1 - index);
3106                         page = find_or_create_page(inode->i_mapping, index,
3107                                                    mask);
3108                         if (!page) {
3109                                 btrfs_delalloc_release_metadata(inode,
3110                                                         PAGE_CACHE_SIZE);
3111                                 ret = -ENOMEM;
3112                                 goto out;
3113                         }
3114                 }
3115
3116                 if (PageReadahead(page)) {
3117                         page_cache_async_readahead(inode->i_mapping,
3118                                                    ra, NULL, page, index,
3119                                                    last_index + 1 - index);
3120                 }
3121
3122                 if (!PageUptodate(page)) {
3123                         btrfs_readpage(NULL, page);
3124                         lock_page(page);
3125                         if (!PageUptodate(page)) {
3126                                 unlock_page(page);
3127                                 page_cache_release(page);
3128                                 btrfs_delalloc_release_metadata(inode,
3129                                                         PAGE_CACHE_SIZE);
3130                                 ret = -EIO;
3131                                 goto out;
3132                         }
3133                 }
3134
3135                 page_start = page_offset(page);
3136                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3137
3138                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3139
3140                 set_page_extent_mapped(page);
3141
3142                 if (nr < cluster->nr &&
3143                     page_start + offset == cluster->boundary[nr]) {
3144                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3145                                         page_start, page_end,
3146                                         EXTENT_BOUNDARY, GFP_NOFS);
3147                         nr++;
3148                 }
3149
3150                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3151                 set_page_dirty(page);
3152
3153                 unlock_extent(&BTRFS_I(inode)->io_tree,
3154                               page_start, page_end);
3155                 unlock_page(page);
3156                 page_cache_release(page);
3157
3158                 index++;
3159                 balance_dirty_pages_ratelimited(inode->i_mapping);
3160                 btrfs_throttle(BTRFS_I(inode)->root);
3161         }
3162         WARN_ON(nr != cluster->nr);
3163 out:
3164         kfree(ra);
3165         return ret;
3166 }
3167
3168 static noinline_for_stack
3169 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3170                          struct file_extent_cluster *cluster)
3171 {
3172         int ret;
3173
3174         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3175                 ret = relocate_file_extent_cluster(inode, cluster);
3176                 if (ret)
3177                         return ret;
3178                 cluster->nr = 0;
3179         }
3180
3181         if (!cluster->nr)
3182                 cluster->start = extent_key->objectid;
3183         else
3184                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3185         cluster->end = extent_key->objectid + extent_key->offset - 1;
3186         cluster->boundary[cluster->nr] = extent_key->objectid;
3187         cluster->nr++;
3188
3189         if (cluster->nr >= MAX_EXTENTS) {
3190                 ret = relocate_file_extent_cluster(inode, cluster);
3191                 if (ret)
3192                         return ret;
3193                 cluster->nr = 0;
3194         }
3195         return 0;
3196 }
3197
3198 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3199 static int get_ref_objectid_v0(struct reloc_control *rc,
3200                                struct btrfs_path *path,
3201                                struct btrfs_key *extent_key,
3202                                u64 *ref_objectid, int *path_change)
3203 {
3204         struct btrfs_key key;
3205         struct extent_buffer *leaf;
3206         struct btrfs_extent_ref_v0 *ref0;
3207         int ret;
3208         int slot;
3209
3210         leaf = path->nodes[0];
3211         slot = path->slots[0];
3212         while (1) {
3213                 if (slot >= btrfs_header_nritems(leaf)) {
3214                         ret = btrfs_next_leaf(rc->extent_root, path);
3215                         if (ret < 0)
3216                                 return ret;
3217                         BUG_ON(ret > 0);
3218                         leaf = path->nodes[0];
3219                         slot = path->slots[0];
3220                         if (path_change)
3221                                 *path_change = 1;
3222                 }
3223                 btrfs_item_key_to_cpu(leaf, &key, slot);
3224                 if (key.objectid != extent_key->objectid)
3225                         return -ENOENT;
3226
3227                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3228                         slot++;
3229                         continue;
3230                 }
3231                 ref0 = btrfs_item_ptr(leaf, slot,
3232                                 struct btrfs_extent_ref_v0);
3233                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3234                 break;
3235         }
3236         return 0;
3237 }
3238 #endif
3239
3240 /*
3241  * helper to add a tree block to the list.
3242  * the major work is getting the generation and level of the block
3243  */
3244 static int add_tree_block(struct reloc_control *rc,
3245                           struct btrfs_key *extent_key,
3246                           struct btrfs_path *path,
3247                           struct rb_root *blocks)
3248 {
3249         struct extent_buffer *eb;
3250         struct btrfs_extent_item *ei;
3251         struct btrfs_tree_block_info *bi;
3252         struct tree_block *block;
3253         struct rb_node *rb_node;
3254         u32 item_size;
3255         int level = -1;
3256         int generation;
3257
3258         eb =  path->nodes[0];
3259         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3260
3261         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3262             item_size >= sizeof(*ei) + sizeof(*bi)) {
3263                 ei = btrfs_item_ptr(eb, path->slots[0],
3264                                 struct btrfs_extent_item);
3265                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3266                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3267                         level = btrfs_tree_block_level(eb, bi);
3268                 } else {
3269                         level = (int)extent_key->offset;
3270                 }
3271                 generation = btrfs_extent_generation(eb, ei);
3272         } else {
3273 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3274                 u64 ref_owner;
3275                 int ret;
3276
3277                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3278                 ret = get_ref_objectid_v0(rc, path, extent_key,
3279                                           &ref_owner, NULL);
3280                 if (ret < 0)
3281                         return ret;
3282                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3283                 level = (int)ref_owner;
3284                 /* FIXME: get real generation */
3285                 generation = 0;
3286 #else
3287                 BUG();
3288 #endif
3289         }
3290
3291         btrfs_release_path(path);
3292
3293         BUG_ON(level == -1);
3294
3295         block = kmalloc(sizeof(*block), GFP_NOFS);
3296         if (!block)
3297                 return -ENOMEM;
3298
3299         block->bytenr = extent_key->objectid;
3300         block->key.objectid = rc->extent_root->leafsize;
3301         block->key.offset = generation;
3302         block->level = level;
3303         block->key_ready = 0;
3304
3305         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3306         if (rb_node)
3307                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3308
3309         return 0;
3310 }
3311
3312 /*
3313  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3314  */
3315 static int __add_tree_block(struct reloc_control *rc,
3316                             u64 bytenr, u32 blocksize,
3317                             struct rb_root *blocks)
3318 {
3319         struct btrfs_path *path;
3320         struct btrfs_key key;
3321         int ret;
3322         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3323                                         SKINNY_METADATA);
3324
3325         if (tree_block_processed(bytenr, blocksize, rc))
3326                 return 0;
3327
3328         if (tree_search(blocks, bytenr))
3329                 return 0;
3330
3331         path = btrfs_alloc_path();
3332         if (!path)
3333                 return -ENOMEM;
3334 again:
3335         key.objectid = bytenr;
3336         if (skinny) {
3337                 key.type = BTRFS_METADATA_ITEM_KEY;
3338                 key.offset = (u64)-1;
3339         } else {
3340                 key.type = BTRFS_EXTENT_ITEM_KEY;
3341                 key.offset = blocksize;
3342         }
3343
3344         path->search_commit_root = 1;
3345         path->skip_locking = 1;
3346         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3347         if (ret < 0)
3348                 goto out;
3349
3350         if (ret > 0 && skinny) {
3351                 if (path->slots[0]) {
3352                         path->slots[0]--;
3353                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3354                                               path->slots[0]);
3355                         if (key.objectid == bytenr &&
3356                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3357                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3358                               key.offset == blocksize)))
3359                                 ret = 0;
3360                 }
3361
3362                 if (ret) {
3363                         skinny = false;
3364                         btrfs_release_path(path);
3365                         goto again;
3366                 }
3367         }
3368         BUG_ON(ret);
3369
3370         ret = add_tree_block(rc, &key, path, blocks);
3371 out:
3372         btrfs_free_path(path);
3373         return ret;
3374 }
3375
3376 /*
3377  * helper to check if the block use full backrefs for pointers in it
3378  */
3379 static int block_use_full_backref(struct reloc_control *rc,
3380                                   struct extent_buffer *eb)
3381 {
3382         u64 flags;
3383         int ret;
3384
3385         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3386             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3387                 return 1;
3388
3389         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3390                                        eb->start, btrfs_header_level(eb), 1,
3391                                        NULL, &flags);
3392         BUG_ON(ret);
3393
3394         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3395                 ret = 1;
3396         else
3397                 ret = 0;
3398         return ret;
3399 }
3400
3401 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3402                                     struct inode *inode, u64 ino)
3403 {
3404         struct btrfs_key key;
3405         struct btrfs_path *path;
3406         struct btrfs_root *root = fs_info->tree_root;
3407         struct btrfs_trans_handle *trans;
3408         int ret = 0;
3409
3410         if (inode)
3411                 goto truncate;
3412
3413         key.objectid = ino;
3414         key.type = BTRFS_INODE_ITEM_KEY;
3415         key.offset = 0;
3416
3417         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3418         if (IS_ERR(inode) || is_bad_inode(inode)) {
3419                 if (!IS_ERR(inode))
3420                         iput(inode);
3421                 return -ENOENT;
3422         }
3423
3424 truncate:
3425         ret = btrfs_check_trunc_cache_free_space(root,
3426                                                  &fs_info->global_block_rsv);
3427         if (ret)
3428                 goto out;
3429
3430         path = btrfs_alloc_path();
3431         if (!path) {
3432                 ret = -ENOMEM;
3433                 goto out;
3434         }
3435
3436         trans = btrfs_join_transaction(root);
3437         if (IS_ERR(trans)) {
3438                 btrfs_free_path(path);
3439                 ret = PTR_ERR(trans);
3440                 goto out;
3441         }
3442
3443         ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
3444
3445         btrfs_free_path(path);
3446         btrfs_end_transaction(trans, root);
3447         btrfs_btree_balance_dirty(root);
3448 out:
3449         iput(inode);
3450         return ret;
3451 }
3452
3453 /*
3454  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3455  * this function scans fs tree to find blocks reference the data extent
3456  */
3457 static int find_data_references(struct reloc_control *rc,
3458                                 struct btrfs_key *extent_key,
3459                                 struct extent_buffer *leaf,
3460                                 struct btrfs_extent_data_ref *ref,
3461                                 struct rb_root *blocks)
3462 {
3463         struct btrfs_path *path;
3464         struct tree_block *block;
3465         struct btrfs_root *root;
3466         struct btrfs_file_extent_item *fi;
3467         struct rb_node *rb_node;
3468         struct btrfs_key key;
3469         u64 ref_root;
3470         u64 ref_objectid;
3471         u64 ref_offset;
3472         u32 ref_count;
3473         u32 nritems;
3474         int err = 0;
3475         int added = 0;
3476         int counted;
3477         int ret;
3478
3479         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3480         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3481         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3482         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3483
3484         /*
3485          * This is an extent belonging to the free space cache, lets just delete
3486          * it and redo the search.
3487          */
3488         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3489                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3490                                                NULL, ref_objectid);
3491                 if (ret != -ENOENT)
3492                         return ret;
3493                 ret = 0;
3494         }
3495
3496         path = btrfs_alloc_path();
3497         if (!path)
3498                 return -ENOMEM;
3499         path->reada = 1;
3500
3501         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3502         if (IS_ERR(root)) {
3503                 err = PTR_ERR(root);
3504                 goto out;
3505         }
3506
3507         key.objectid = ref_objectid;
3508         key.type = BTRFS_EXTENT_DATA_KEY;
3509         if (ref_offset > ((u64)-1 << 32))
3510                 key.offset = 0;
3511         else
3512                 key.offset = ref_offset;
3513
3514         path->search_commit_root = 1;
3515         path->skip_locking = 1;
3516         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3517         if (ret < 0) {
3518                 err = ret;
3519                 goto out;
3520         }
3521
3522         leaf = path->nodes[0];
3523         nritems = btrfs_header_nritems(leaf);
3524         /*
3525          * the references in tree blocks that use full backrefs
3526          * are not counted in
3527          */
3528         if (block_use_full_backref(rc, leaf))
3529                 counted = 0;
3530         else
3531                 counted = 1;
3532         rb_node = tree_search(blocks, leaf->start);
3533         if (rb_node) {
3534                 if (counted)
3535                         added = 1;
3536                 else
3537                         path->slots[0] = nritems;
3538         }
3539
3540         while (ref_count > 0) {
3541                 while (path->slots[0] >= nritems) {
3542                         ret = btrfs_next_leaf(root, path);
3543                         if (ret < 0) {
3544                                 err = ret;
3545                                 goto out;
3546                         }
3547                         if (ret > 0) {
3548                                 WARN_ON(1);
3549                                 goto out;
3550                         }
3551
3552                         leaf = path->nodes[0];
3553                         nritems = btrfs_header_nritems(leaf);
3554                         added = 0;
3555
3556                         if (block_use_full_backref(rc, leaf))
3557                                 counted = 0;
3558                         else
3559                                 counted = 1;
3560                         rb_node = tree_search(blocks, leaf->start);
3561                         if (rb_node) {
3562                                 if (counted)
3563                                         added = 1;
3564                                 else
3565                                         path->slots[0] = nritems;
3566                         }
3567                 }
3568
3569                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3570                 if (key.objectid != ref_objectid ||
3571                     key.type != BTRFS_EXTENT_DATA_KEY) {
3572                         WARN_ON(1);
3573                         break;
3574                 }
3575
3576                 fi = btrfs_item_ptr(leaf, path->slots[0],
3577                                     struct btrfs_file_extent_item);
3578
3579                 if (btrfs_file_extent_type(leaf, fi) ==
3580                     BTRFS_FILE_EXTENT_INLINE)
3581                         goto next;
3582
3583                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3584                     extent_key->objectid)
3585                         goto next;
3586
3587                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3588                 if (key.offset != ref_offset)
3589                         goto next;
3590
3591                 if (counted)
3592                         ref_count--;
3593                 if (added)
3594                         goto next;
3595
3596                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3597                         block = kmalloc(sizeof(*block), GFP_NOFS);
3598                         if (!block) {
3599                                 err = -ENOMEM;
3600                                 break;
3601                         }
3602                         block->bytenr = leaf->start;
3603                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3604                         block->level = 0;
3605                         block->key_ready = 1;
3606                         rb_node = tree_insert(blocks, block->bytenr,
3607                                               &block->rb_node);
3608                         if (rb_node)
3609                                 backref_tree_panic(rb_node, -EEXIST,
3610                                                    block->bytenr);
3611                 }
3612                 if (counted)
3613                         added = 1;
3614                 else
3615                         path->slots[0] = nritems;
3616 next:
3617                 path->slots[0]++;
3618
3619         }
3620 out:
3621         btrfs_free_path(path);
3622         return err;
3623 }
3624
3625 /*
3626  * helper to find all tree blocks that reference a given data extent
3627  */
3628 static noinline_for_stack
3629 int add_data_references(struct reloc_control *rc,
3630                         struct btrfs_key *extent_key,
3631                         struct btrfs_path *path,
3632                         struct rb_root *blocks)
3633 {
3634         struct btrfs_key key;
3635         struct extent_buffer *eb;
3636         struct btrfs_extent_data_ref *dref;
3637         struct btrfs_extent_inline_ref *iref;
3638         unsigned long ptr;
3639         unsigned long end;
3640         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3641         int ret = 0;
3642         int err = 0;
3643
3644         eb = path->nodes[0];
3645         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3646         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3647 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3648         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3649                 ptr = end;
3650         else
3651 #endif
3652                 ptr += sizeof(struct btrfs_extent_item);
3653
3654         while (ptr < end) {
3655                 iref = (struct btrfs_extent_inline_ref *)ptr;
3656                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3657                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3658                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3659                         ret = __add_tree_block(rc, key.offset, blocksize,
3660                                                blocks);
3661                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3662                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3663                         ret = find_data_references(rc, extent_key,
3664                                                    eb, dref, blocks);
3665                 } else {
3666                         BUG();
3667                 }
3668                 if (ret) {
3669                         err = ret;
3670                         goto out;
3671                 }
3672                 ptr += btrfs_extent_inline_ref_size(key.type);
3673         }
3674         WARN_ON(ptr > end);
3675
3676         while (1) {
3677                 cond_resched();
3678                 eb = path->nodes[0];
3679                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3680                         ret = btrfs_next_leaf(rc->extent_root, path);
3681                         if (ret < 0) {
3682                                 err = ret;
3683                                 break;
3684                         }
3685                         if (ret > 0)
3686                                 break;
3687                         eb = path->nodes[0];
3688                 }
3689
3690                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3691                 if (key.objectid != extent_key->objectid)
3692                         break;
3693
3694 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3695                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3696                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3697 #else
3698                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3699                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3700 #endif
3701                         ret = __add_tree_block(rc, key.offset, blocksize,
3702                                                blocks);
3703                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3704                         dref = btrfs_item_ptr(eb, path->slots[0],
3705                                               struct btrfs_extent_data_ref);
3706                         ret = find_data_references(rc, extent_key,
3707                                                    eb, dref, blocks);
3708                 } else {
3709                         ret = 0;
3710                 }
3711                 if (ret) {
3712                         err = ret;
3713                         break;
3714                 }
3715                 path->slots[0]++;
3716         }
3717 out:
3718         btrfs_release_path(path);
3719         if (err)
3720                 free_block_list(blocks);
3721         return err;
3722 }
3723
3724 /*
3725  * helper to find next unprocessed extent
3726  */
3727 static noinline_for_stack
3728 int find_next_extent(struct btrfs_trans_handle *trans,
3729                      struct reloc_control *rc, struct btrfs_path *path,
3730                      struct btrfs_key *extent_key)
3731 {
3732         struct btrfs_key key;
3733         struct extent_buffer *leaf;
3734         u64 start, end, last;
3735         int ret;
3736
3737         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3738         while (1) {
3739                 cond_resched();
3740                 if (rc->search_start >= last) {
3741                         ret = 1;
3742                         break;
3743                 }
3744
3745                 key.objectid = rc->search_start;
3746                 key.type = BTRFS_EXTENT_ITEM_KEY;
3747                 key.offset = 0;
3748
3749                 path->search_commit_root = 1;
3750                 path->skip_locking = 1;
3751                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3752                                         0, 0);
3753                 if (ret < 0)
3754                         break;
3755 next:
3756                 leaf = path->nodes[0];
3757                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3758                         ret = btrfs_next_leaf(rc->extent_root, path);
3759                         if (ret != 0)
3760                                 break;
3761                         leaf = path->nodes[0];
3762                 }
3763
3764                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3765                 if (key.objectid >= last) {
3766                         ret = 1;
3767                         break;
3768                 }
3769
3770                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3771                     key.type != BTRFS_METADATA_ITEM_KEY) {
3772                         path->slots[0]++;
3773                         goto next;
3774                 }
3775
3776                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3777                     key.objectid + key.offset <= rc->search_start) {
3778                         path->slots[0]++;
3779                         goto next;
3780                 }
3781
3782                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3783                     key.objectid + rc->extent_root->leafsize <=
3784                     rc->search_start) {
3785                         path->slots[0]++;
3786                         goto next;
3787                 }
3788
3789                 ret = find_first_extent_bit(&rc->processed_blocks,
3790                                             key.objectid, &start, &end,
3791                                             EXTENT_DIRTY, NULL);
3792
3793                 if (ret == 0 && start <= key.objectid) {
3794                         btrfs_release_path(path);
3795                         rc->search_start = end + 1;
3796                 } else {
3797                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3798                                 rc->search_start = key.objectid + key.offset;
3799                         else
3800                                 rc->search_start = key.objectid +
3801                                         rc->extent_root->leafsize;
3802                         memcpy(extent_key, &key, sizeof(key));
3803                         return 0;
3804                 }
3805         }
3806         btrfs_release_path(path);
3807         return ret;
3808 }
3809
3810 static void set_reloc_control(struct reloc_control *rc)
3811 {
3812         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3813
3814         mutex_lock(&fs_info->reloc_mutex);
3815         fs_info->reloc_ctl = rc;
3816         mutex_unlock(&fs_info->reloc_mutex);
3817 }
3818
3819 static void unset_reloc_control(struct reloc_control *rc)
3820 {
3821         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3822
3823         mutex_lock(&fs_info->reloc_mutex);
3824         fs_info->reloc_ctl = NULL;
3825         mutex_unlock(&fs_info->reloc_mutex);
3826 }
3827
3828 static int check_extent_flags(u64 flags)
3829 {
3830         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3831             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3832                 return 1;
3833         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3834             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3835                 return 1;
3836         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3837             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3838                 return 1;
3839         return 0;
3840 }
3841
3842 static noinline_for_stack
3843 int prepare_to_relocate(struct reloc_control *rc)
3844 {
3845         struct btrfs_trans_handle *trans;
3846         int ret;
3847
3848         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3849                                               BTRFS_BLOCK_RSV_TEMP);
3850         if (!rc->block_rsv)
3851                 return -ENOMEM;
3852
3853         /*
3854          * reserve some space for creating reloc trees.
3855          * btrfs_init_reloc_root will use them when there
3856          * is no reservation in transaction handle.
3857          */
3858         ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3859                                   rc->extent_root->nodesize * 256,
3860                                   BTRFS_RESERVE_FLUSH_ALL);
3861         if (ret)
3862                 return ret;
3863
3864         memset(&rc->cluster, 0, sizeof(rc->cluster));
3865         rc->search_start = rc->block_group->key.objectid;
3866         rc->extents_found = 0;
3867         rc->nodes_relocated = 0;
3868         rc->merging_rsv_size = 0;
3869
3870         rc->create_reloc_tree = 1;
3871         set_reloc_control(rc);
3872
3873         trans = btrfs_join_transaction(rc->extent_root);
3874         if (IS_ERR(trans)) {
3875                 unset_reloc_control(rc);
3876                 /*
3877                  * extent tree is not a ref_cow tree and has no reloc_root to
3878                  * cleanup.  And callers are responsible to free the above
3879                  * block rsv.
3880                  */
3881                 return PTR_ERR(trans);
3882         }
3883         btrfs_commit_transaction(trans, rc->extent_root);
3884         return 0;
3885 }
3886
3887 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3888 {
3889         struct rb_root blocks = RB_ROOT;
3890         struct btrfs_key key;
3891         struct btrfs_trans_handle *trans = NULL;
3892         struct btrfs_path *path;
3893         struct btrfs_extent_item *ei;
3894         u64 flags;
3895         u32 item_size;
3896         int ret;
3897         int err = 0;
3898         int progress = 0;
3899
3900         path = btrfs_alloc_path();
3901         if (!path)
3902                 return -ENOMEM;
3903         path->reada = 1;
3904
3905         ret = prepare_to_relocate(rc);
3906         if (ret) {
3907                 err = ret;
3908                 goto out_free;
3909         }
3910
3911         while (1) {
3912                 progress++;
3913                 trans = btrfs_start_transaction(rc->extent_root, 0);
3914                 if (IS_ERR(trans)) {
3915                         err = PTR_ERR(trans);
3916                         trans = NULL;
3917                         break;
3918                 }
3919 restart:
3920                 if (update_backref_cache(trans, &rc->backref_cache)) {
3921                         btrfs_end_transaction(trans, rc->extent_root);
3922                         continue;
3923                 }
3924
3925                 ret = find_next_extent(trans, rc, path, &key);
3926                 if (ret < 0)
3927                         err = ret;
3928                 if (ret != 0)
3929                         break;
3930
3931                 rc->extents_found++;
3932
3933                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3934                                     struct btrfs_extent_item);
3935                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3936                 if (item_size >= sizeof(*ei)) {
3937                         flags = btrfs_extent_flags(path->nodes[0], ei);
3938                         ret = check_extent_flags(flags);
3939                         BUG_ON(ret);
3940
3941                 } else {
3942 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3943                         u64 ref_owner;
3944                         int path_change = 0;
3945
3946                         BUG_ON(item_size !=
3947                                sizeof(struct btrfs_extent_item_v0));
3948                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3949                                                   &path_change);
3950                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3951                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3952                         else
3953                                 flags = BTRFS_EXTENT_FLAG_DATA;
3954
3955                         if (path_change) {
3956                                 btrfs_release_path(path);
3957
3958                                 path->search_commit_root = 1;
3959                                 path->skip_locking = 1;
3960                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3961                                                         &key, path, 0, 0);
3962                                 if (ret < 0) {
3963                                         err = ret;
3964                                         break;
3965                                 }
3966                                 BUG_ON(ret > 0);
3967                         }
3968 #else
3969                         BUG();
3970 #endif
3971                 }
3972
3973                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3974                         ret = add_tree_block(rc, &key, path, &blocks);
3975                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3976                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3977                         ret = add_data_references(rc, &key, path, &blocks);
3978                 } else {
3979                         btrfs_release_path(path);
3980                         ret = 0;
3981                 }
3982                 if (ret < 0) {
3983                         err = ret;
3984                         break;
3985                 }
3986
3987                 if (!RB_EMPTY_ROOT(&blocks)) {
3988                         ret = relocate_tree_blocks(trans, rc, &blocks);
3989                         if (ret < 0) {
3990                                 if (ret != -EAGAIN) {
3991                                         err = ret;
3992                                         break;
3993                                 }
3994                                 rc->extents_found--;
3995                                 rc->search_start = key.objectid;
3996                         }
3997                 }
3998
3999                 ret = btrfs_block_rsv_check(rc->extent_root, rc->block_rsv, 5);
4000                 if (ret < 0) {
4001                         if (ret != -ENOSPC) {
4002                                 err = ret;
4003                                 WARN_ON(1);
4004                                 break;
4005                         }
4006                         rc->commit_transaction = 1;
4007                 }
4008
4009                 if (rc->commit_transaction) {
4010                         rc->commit_transaction = 0;
4011                         ret = btrfs_commit_transaction(trans, rc->extent_root);
4012                         BUG_ON(ret);
4013                 } else {
4014                         btrfs_end_transaction_throttle(trans, rc->extent_root);
4015                         btrfs_btree_balance_dirty(rc->extent_root);
4016                 }
4017                 trans = NULL;
4018
4019                 if (rc->stage == MOVE_DATA_EXTENTS &&
4020                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4021                         rc->found_file_extent = 1;
4022                         ret = relocate_data_extent(rc->data_inode,
4023                                                    &key, &rc->cluster);
4024                         if (ret < 0) {
4025                                 err = ret;
4026                                 break;
4027                         }
4028                 }
4029         }
4030         if (trans && progress && err == -ENOSPC) {
4031                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4032                                               rc->block_group->flags);
4033                 if (ret == 0) {
4034                         err = 0;
4035                         progress = 0;
4036                         goto restart;
4037                 }
4038         }
4039
4040         btrfs_release_path(path);
4041         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4042                           GFP_NOFS);
4043
4044         if (trans) {
4045                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4046                 btrfs_btree_balance_dirty(rc->extent_root);
4047         }
4048
4049         if (!err) {
4050                 ret = relocate_file_extent_cluster(rc->data_inode,
4051                                                    &rc->cluster);
4052                 if (ret < 0)
4053                         err = ret;
4054         }
4055
4056         rc->create_reloc_tree = 0;
4057         set_reloc_control(rc);
4058
4059         backref_cache_cleanup(&rc->backref_cache);
4060         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4061
4062         err = prepare_to_merge(rc, err);
4063
4064         merge_reloc_roots(rc);
4065
4066         rc->merge_reloc_tree = 0;
4067         unset_reloc_control(rc);
4068         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4069
4070         /* get rid of pinned extents */
4071         trans = btrfs_join_transaction(rc->extent_root);
4072         if (IS_ERR(trans))
4073                 err = PTR_ERR(trans);
4074         else
4075                 btrfs_commit_transaction(trans, rc->extent_root);
4076 out_free:
4077         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4078         btrfs_free_path(path);
4079         return err;
4080 }
4081
4082 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4083                                  struct btrfs_root *root, u64 objectid)
4084 {
4085         struct btrfs_path *path;
4086         struct btrfs_inode_item *item;
4087         struct extent_buffer *leaf;
4088         int ret;
4089
4090         path = btrfs_alloc_path();
4091         if (!path)
4092                 return -ENOMEM;
4093
4094         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4095         if (ret)
4096                 goto out;
4097
4098         leaf = path->nodes[0];
4099         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4100         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4101         btrfs_set_inode_generation(leaf, item, 1);
4102         btrfs_set_inode_size(leaf, item, 0);
4103         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4104         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4105                                           BTRFS_INODE_PREALLOC);
4106         btrfs_mark_buffer_dirty(leaf);
4107         btrfs_release_path(path);
4108 out:
4109         btrfs_free_path(path);
4110         return ret;
4111 }
4112
4113 /*
4114  * helper to create inode for data relocation.
4115  * the inode is in data relocation tree and its link count is 0
4116  */
4117 static noinline_for_stack
4118 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4119                                  struct btrfs_block_group_cache *group)
4120 {
4121         struct inode *inode = NULL;
4122         struct btrfs_trans_handle *trans;
4123         struct btrfs_root *root;
4124         struct btrfs_key key;
4125         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
4126         int err = 0;
4127
4128         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4129         if (IS_ERR(root))
4130                 return ERR_CAST(root);
4131
4132         trans = btrfs_start_transaction(root, 6);
4133         if (IS_ERR(trans))
4134                 return ERR_CAST(trans);
4135
4136         err = btrfs_find_free_objectid(root, &objectid);
4137         if (err)
4138                 goto out;
4139
4140         err = __insert_orphan_inode(trans, root, objectid);
4141         BUG_ON(err);
4142
4143         key.objectid = objectid;
4144         key.type = BTRFS_INODE_ITEM_KEY;
4145         key.offset = 0;
4146         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4147         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4148         BTRFS_I(inode)->index_cnt = group->key.objectid;
4149
4150         err = btrfs_orphan_add(trans, inode);
4151 out:
4152         btrfs_end_transaction(trans, root);
4153         btrfs_btree_balance_dirty(root);
4154         if (err) {
4155                 if (inode)
4156                         iput(inode);
4157                 inode = ERR_PTR(err);
4158         }
4159         return inode;
4160 }
4161
4162 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4163 {
4164         struct reloc_control *rc;
4165
4166         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4167         if (!rc)
4168                 return NULL;
4169
4170         INIT_LIST_HEAD(&rc->reloc_roots);
4171         backref_cache_init(&rc->backref_cache);
4172         mapping_tree_init(&rc->reloc_root_tree);
4173         extent_io_tree_init(&rc->processed_blocks,
4174                             fs_info->btree_inode->i_mapping);
4175         return rc;
4176 }
4177
4178 /*
4179  * function to relocate all extents in a block group.
4180  */
4181 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4182 {
4183         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4184         struct reloc_control *rc;
4185         struct inode *inode;
4186         struct btrfs_path *path;
4187         int ret;
4188         int rw = 0;
4189         int err = 0;
4190
4191         rc = alloc_reloc_control(fs_info);
4192         if (!rc)
4193                 return -ENOMEM;
4194
4195         rc->extent_root = extent_root;
4196
4197         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4198         BUG_ON(!rc->block_group);
4199
4200         if (!rc->block_group->ro) {
4201                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4202                 if (ret) {
4203                         err = ret;
4204                         goto out;
4205                 }
4206                 rw = 1;
4207         }
4208
4209         path = btrfs_alloc_path();
4210         if (!path) {
4211                 err = -ENOMEM;
4212                 goto out;
4213         }
4214
4215         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4216                                         path);
4217         btrfs_free_path(path);
4218
4219         if (!IS_ERR(inode))
4220                 ret = delete_block_group_cache(fs_info, inode, 0);
4221         else
4222                 ret = PTR_ERR(inode);
4223
4224         if (ret && ret != -ENOENT) {
4225                 err = ret;
4226                 goto out;
4227         }
4228
4229         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4230         if (IS_ERR(rc->data_inode)) {
4231                 err = PTR_ERR(rc->data_inode);
4232                 rc->data_inode = NULL;
4233                 goto out;
4234         }
4235
4236         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4237                (unsigned long long)rc->block_group->key.objectid,
4238                (unsigned long long)rc->block_group->flags);
4239
4240         ret = btrfs_start_all_delalloc_inodes(fs_info, 0);
4241         if (ret < 0) {
4242                 err = ret;
4243                 goto out;
4244         }
4245         btrfs_wait_all_ordered_extents(fs_info, 0);
4246
4247         while (1) {
4248                 mutex_lock(&fs_info->cleaner_mutex);
4249                 ret = relocate_block_group(rc);
4250                 mutex_unlock(&fs_info->cleaner_mutex);
4251                 if (ret < 0) {
4252                         err = ret;
4253                         goto out;
4254                 }
4255
4256                 if (rc->extents_found == 0)
4257                         break;
4258
4259                 printk(KERN_INFO "btrfs: found %llu extents\n",
4260                         (unsigned long long)rc->extents_found);
4261
4262                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4263                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
4264                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4265                                                  0, -1);
4266                         rc->stage = UPDATE_DATA_PTRS;
4267                 }
4268         }
4269
4270         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4271                                      rc->block_group->key.objectid,
4272                                      rc->block_group->key.objectid +
4273                                      rc->block_group->key.offset - 1);
4274
4275         WARN_ON(rc->block_group->pinned > 0);
4276         WARN_ON(rc->block_group->reserved > 0);
4277         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4278 out:
4279         if (err && rw)
4280                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4281         iput(rc->data_inode);
4282         btrfs_put_block_group(rc->block_group);
4283         kfree(rc);
4284         return err;
4285 }
4286
4287 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4288 {
4289         struct btrfs_trans_handle *trans;
4290         int ret, err;
4291
4292         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4293         if (IS_ERR(trans))
4294                 return PTR_ERR(trans);
4295
4296         memset(&root->root_item.drop_progress, 0,
4297                 sizeof(root->root_item.drop_progress));
4298         root->root_item.drop_level = 0;
4299         btrfs_set_root_refs(&root->root_item, 0);
4300         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4301                                 &root->root_key, &root->root_item);
4302
4303         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4304         if (err)
4305                 return err;
4306         return ret;
4307 }
4308
4309 /*
4310  * recover relocation interrupted by system crash.
4311  *
4312  * this function resumes merging reloc trees with corresponding fs trees.
4313  * this is important for keeping the sharing of tree blocks
4314  */
4315 int btrfs_recover_relocation(struct btrfs_root *root)
4316 {
4317         LIST_HEAD(reloc_roots);
4318         struct btrfs_key key;
4319         struct btrfs_root *fs_root;
4320         struct btrfs_root *reloc_root;
4321         struct btrfs_path *path;
4322         struct extent_buffer *leaf;
4323         struct reloc_control *rc = NULL;
4324         struct btrfs_trans_handle *trans;
4325         int ret;
4326         int err = 0;
4327
4328         path = btrfs_alloc_path();
4329         if (!path)
4330                 return -ENOMEM;
4331         path->reada = -1;
4332
4333         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4334         key.type = BTRFS_ROOT_ITEM_KEY;
4335         key.offset = (u64)-1;
4336
4337         while (1) {
4338                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4339                                         path, 0, 0);
4340                 if (ret < 0) {
4341                         err = ret;
4342                         goto out;
4343                 }
4344                 if (ret > 0) {
4345                         if (path->slots[0] == 0)
4346                                 break;
4347                         path->slots[0]--;
4348                 }
4349                 leaf = path->nodes[0];
4350                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4351                 btrfs_release_path(path);
4352
4353                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4354                     key.type != BTRFS_ROOT_ITEM_KEY)
4355                         break;
4356
4357                 reloc_root = btrfs_read_fs_root(root, &key);
4358                 if (IS_ERR(reloc_root)) {
4359                         err = PTR_ERR(reloc_root);
4360                         goto out;
4361                 }
4362
4363                 list_add(&reloc_root->root_list, &reloc_roots);
4364
4365                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4366                         fs_root = read_fs_root(root->fs_info,
4367                                                reloc_root->root_key.offset);
4368                         if (IS_ERR(fs_root)) {
4369                                 ret = PTR_ERR(fs_root);
4370                                 if (ret != -ENOENT) {
4371                                         err = ret;
4372                                         goto out;
4373                                 }
4374                                 ret = mark_garbage_root(reloc_root);
4375                                 if (ret < 0) {
4376                                         err = ret;
4377                                         goto out;
4378                                 }
4379                         }
4380                 }
4381
4382                 if (key.offset == 0)
4383                         break;
4384
4385                 key.offset--;
4386         }
4387         btrfs_release_path(path);
4388
4389         if (list_empty(&reloc_roots))
4390                 goto out;
4391
4392         rc = alloc_reloc_control(root->fs_info);
4393         if (!rc) {
4394                 err = -ENOMEM;
4395                 goto out;
4396         }
4397
4398         rc->extent_root = root->fs_info->extent_root;
4399
4400         set_reloc_control(rc);
4401
4402         trans = btrfs_join_transaction(rc->extent_root);
4403         if (IS_ERR(trans)) {
4404                 unset_reloc_control(rc);
4405                 err = PTR_ERR(trans);
4406                 goto out_free;
4407         }
4408
4409         rc->merge_reloc_tree = 1;
4410
4411         while (!list_empty(&reloc_roots)) {
4412                 reloc_root = list_entry(reloc_roots.next,
4413                                         struct btrfs_root, root_list);
4414                 list_del(&reloc_root->root_list);
4415
4416                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4417                         list_add_tail(&reloc_root->root_list,
4418                                       &rc->reloc_roots);
4419                         continue;
4420                 }
4421
4422                 fs_root = read_fs_root(root->fs_info,
4423                                        reloc_root->root_key.offset);
4424                 if (IS_ERR(fs_root)) {
4425                         err = PTR_ERR(fs_root);
4426                         goto out_free;
4427                 }
4428
4429                 err = __add_reloc_root(reloc_root);
4430                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4431                 fs_root->reloc_root = reloc_root;
4432         }
4433
4434         err = btrfs_commit_transaction(trans, rc->extent_root);
4435         if (err)
4436                 goto out_free;
4437
4438         merge_reloc_roots(rc);
4439
4440         unset_reloc_control(rc);
4441
4442         trans = btrfs_join_transaction(rc->extent_root);
4443         if (IS_ERR(trans))
4444                 err = PTR_ERR(trans);
4445         else
4446                 err = btrfs_commit_transaction(trans, rc->extent_root);
4447 out_free:
4448         kfree(rc);
4449 out:
4450         if (!list_empty(&reloc_roots))
4451                 free_reloc_roots(&reloc_roots);
4452
4453         btrfs_free_path(path);
4454
4455         if (err == 0) {
4456                 /* cleanup orphan inode in data relocation tree */
4457                 fs_root = read_fs_root(root->fs_info,
4458                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4459                 if (IS_ERR(fs_root))
4460                         err = PTR_ERR(fs_root);
4461                 else
4462                         err = btrfs_orphan_cleanup(fs_root);
4463         }
4464         return err;
4465 }
4466
4467 /*
4468  * helper to add ordered checksum for data relocation.
4469  *
4470  * cloning checksum properly handles the nodatasum extents.
4471  * it also saves CPU time to re-calculate the checksum.
4472  */
4473 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4474 {
4475         struct btrfs_ordered_sum *sums;
4476         struct btrfs_ordered_extent *ordered;
4477         struct btrfs_root *root = BTRFS_I(inode)->root;
4478         int ret;
4479         u64 disk_bytenr;
4480         LIST_HEAD(list);
4481
4482         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4483         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4484
4485         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4486         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4487                                        disk_bytenr + len - 1, &list, 0);
4488         if (ret)
4489                 goto out;
4490
4491         disk_bytenr = ordered->start;
4492         while (!list_empty(&list)) {
4493                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4494                 list_del_init(&sums->list);
4495
4496                 sums->bytenr = disk_bytenr;
4497                 disk_bytenr += sums->len;
4498
4499                 btrfs_add_ordered_sum(inode, ordered, sums);
4500         }
4501 out:
4502         btrfs_put_ordered_extent(ordered);
4503         return ret;
4504 }
4505
4506 void btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4507                            struct btrfs_root *root, struct extent_buffer *buf,
4508                            struct extent_buffer *cow)
4509 {
4510         struct reloc_control *rc;
4511         struct backref_node *node;
4512         int first_cow = 0;
4513         int level;
4514         int ret;
4515
4516         rc = root->fs_info->reloc_ctl;
4517         if (!rc)
4518                 return;
4519
4520         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4521                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4522
4523         level = btrfs_header_level(buf);
4524         if (btrfs_header_generation(buf) <=
4525             btrfs_root_last_snapshot(&root->root_item))
4526                 first_cow = 1;
4527
4528         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4529             rc->create_reloc_tree) {
4530                 WARN_ON(!first_cow && level == 0);
4531
4532                 node = rc->backref_cache.path[level];
4533                 BUG_ON(node->bytenr != buf->start &&
4534                        node->new_bytenr != buf->start);
4535
4536                 drop_node_buffer(node);
4537                 extent_buffer_get(cow);
4538                 node->eb = cow;
4539                 node->new_bytenr = cow->start;
4540
4541                 if (!node->pending) {
4542                         list_move_tail(&node->list,
4543                                        &rc->backref_cache.pending[level]);
4544                         node->pending = 1;
4545                 }
4546
4547                 if (first_cow)
4548                         __mark_block_processed(rc, node);
4549
4550                 if (first_cow && level > 0)
4551                         rc->nodes_relocated += buf->len;
4552         }
4553
4554         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS) {
4555                 ret = replace_file_extents(trans, rc, root, cow);
4556                 BUG_ON(ret);
4557         }
4558 }
4559
4560 /*
4561  * called before creating snapshot. it calculates metadata reservation
4562  * requried for relocating tree blocks in the snapshot
4563  */
4564 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4565                               struct btrfs_pending_snapshot *pending,
4566                               u64 *bytes_to_reserve)
4567 {
4568         struct btrfs_root *root;
4569         struct reloc_control *rc;
4570
4571         root = pending->root;
4572         if (!root->reloc_root)
4573                 return;
4574
4575         rc = root->fs_info->reloc_ctl;
4576         if (!rc->merge_reloc_tree)
4577                 return;
4578
4579         root = root->reloc_root;
4580         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4581         /*
4582          * relocation is in the stage of merging trees. the space
4583          * used by merging a reloc tree is twice the size of
4584          * relocated tree nodes in the worst case. half for cowing
4585          * the reloc tree, half for cowing the fs tree. the space
4586          * used by cowing the reloc tree will be freed after the
4587          * tree is dropped. if we create snapshot, cowing the fs
4588          * tree may use more space than it frees. so we need
4589          * reserve extra space.
4590          */
4591         *bytes_to_reserve += rc->nodes_relocated;
4592 }
4593
4594 /*
4595  * called after snapshot is created. migrate block reservation
4596  * and create reloc root for the newly created snapshot
4597  */
4598 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4599                                struct btrfs_pending_snapshot *pending)
4600 {
4601         struct btrfs_root *root = pending->root;
4602         struct btrfs_root *reloc_root;
4603         struct btrfs_root *new_root;
4604         struct reloc_control *rc;
4605         int ret;
4606
4607         if (!root->reloc_root)
4608                 return 0;
4609
4610         rc = root->fs_info->reloc_ctl;
4611         rc->merging_rsv_size += rc->nodes_relocated;
4612
4613         if (rc->merge_reloc_tree) {
4614                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4615                                               rc->block_rsv,
4616                                               rc->nodes_relocated);
4617                 if (ret)
4618                         return ret;
4619         }
4620
4621         new_root = pending->snap;
4622         reloc_root = create_reloc_root(trans, root->reloc_root,
4623                                        new_root->root_key.objectid);
4624         if (IS_ERR(reloc_root))
4625                 return PTR_ERR(reloc_root);
4626
4627         ret = __add_reloc_root(reloc_root);
4628         BUG_ON(ret < 0);
4629         new_root->reloc_root = reloc_root;
4630
4631         if (rc->create_reloc_tree)
4632                 ret = clone_backref_node(trans, rc, root, reloc_root);
4633         return ret;
4634 }