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", 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             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 576             root_objectid == BTRFS_QUOTA_TREE_OBJECTID)
 577                 return 1;
 578         return 0;
 579 }
 580
 581 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 582                                         u64 root_objectid)
 583 {
 584         struct btrfs_key key;
 585
 586         key.objectid = root_objectid;
 587         key.type = BTRFS_ROOT_ITEM_KEY;
 588         if (is_cowonly_root(root_objectid))
 589                 key.offset = 0;
 590         else
 591                 key.offset = (u64)-1;
 592
 593         return btrfs_get_fs_root(fs_info, &key, false);
 594 }
 595
 596 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 597 static noinline_for_stack
 598 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 599                                   struct extent_buffer *leaf,
 600                                   struct btrfs_extent_ref_v0 *ref0)
 601 {
 602         struct btrfs_root *root;
 603         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 604         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 605
 606         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 607
 608         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 609         BUG_ON(IS_ERR(root));
 610
 611         if (root->ref_cows &&
 612             generation != btrfs_root_generation(&root->root_item))
 613                 return NULL;
 614
 615         return root;
 616 }
 617 #endif
 618
 619 static noinline_for_stack
 620 int find_inline_backref(struct extent_buffer *leaf, int slot,
 621                         unsigned long *ptr, unsigned long *end)
 622 {
 623         struct btrfs_key key;
 624         struct btrfs_extent_item *ei;
 625         struct btrfs_tree_block_info *bi;
 626         u32 item_size;
 627
 628         btrfs_item_key_to_cpu(leaf, &key, slot);
 629
 630         item_size = btrfs_item_size_nr(leaf, slot);
 631 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 632         if (item_size < sizeof(*ei)) {
 633                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 634                 return 1;
 635         }
 636 #endif
 637         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 638         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 639                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 640
 641         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 642             item_size <= sizeof(*ei) + sizeof(*bi)) {
 643                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 644                 return 1;
 645         }
 646         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 647             item_size <= sizeof(*ei)) {
 648                 WARN_ON(item_size < sizeof(*ei));
 649                 return 1;
 650         }
 651
 652         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 653                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 654                 *ptr = (unsigned long)(bi + 1);
 655         } else {
 656                 *ptr = (unsigned long)(ei + 1);
 657         }
 658         *end = (unsigned long)ei + item_size;
 659         return 0;
 660 }
 661
 662 /*
 663  * build backref tree for a given tree block. root of the backref tree
 664  * corresponds the tree block, leaves of the backref tree correspond
 665  * roots of b-trees that reference the tree block.
 666  *
 667  * the basic idea of this function is check backrefs of a given block
 668  * to find upper level blocks that refernece the block, and then check
 669  * bakcrefs of these upper level blocks recursively. the recursion stop
 670  * when tree root is reached or backrefs for the block is cached.
 671  *
 672  * NOTE: if we find backrefs for a block are cached, we know backrefs
 673  * for all upper level blocks that directly/indirectly reference the
 674  * block are also cached.
 675  */
 676 static noinline_for_stack
 677 struct backref_node *build_backref_tree(struct reloc_control *rc,
 678                                         struct btrfs_key *node_key,
 679                                         int level, u64 bytenr)
 680 {
 681         struct backref_cache *cache = &rc->backref_cache;
 682         struct btrfs_path *path1;
 683         struct btrfs_path *path2;
 684         struct extent_buffer *eb;
 685         struct btrfs_root *root;
 686         struct backref_node *cur;
 687         struct backref_node *upper;
 688         struct backref_node *lower;
 689         struct backref_node *node = NULL;
 690         struct backref_node *exist = NULL;
 691         struct backref_edge *edge;
 692         struct rb_node *rb_node;
 693         struct btrfs_key key;
 694         unsigned long end;
 695         unsigned long ptr;
 696         LIST_HEAD(list);
 697         LIST_HEAD(useless);
 698         int cowonly;
 699         int ret;
 700         int err = 0;
 701         bool need_check = true;
 702
 703         path1 = btrfs_alloc_path();
 704         path2 = btrfs_alloc_path();
 705         if (!path1 || !path2) {
 706                 err = -ENOMEM;
 707                 goto out;
 708         }
 709         path1->reada = 1;
 710         path2->reada = 2;
 711
 712         node = alloc_backref_node(cache);
 713         if (!node) {
 714                 err = -ENOMEM;
 715                 goto out;
 716         }
 717
 718         node->bytenr = bytenr;
 719         node->level = level;
 720         node->lowest = 1;
 721         cur = node;
 722 again:
 723         end = 0;
 724         ptr = 0;
 725         key.objectid = cur->bytenr;
 726         key.type = BTRFS_METADATA_ITEM_KEY;
 727         key.offset = (u64)-1;
 728
 729         path1->search_commit_root = 1;
 730         path1->skip_locking = 1;
 731         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 732                                 0, 0);
 733         if (ret < 0) {
 734                 err = ret;
 735                 goto out;
 736         }
 737         BUG_ON(!ret || !path1->slots[0]);
 738
 739         path1->slots[0]--;
 740
 741         WARN_ON(cur->checked);
 742         if (!list_empty(&cur->upper)) {
 743                 /*
 744                  * the backref was added previously when processing
 745                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 746                  */
 747                 BUG_ON(!list_is_singular(&cur->upper));
 748                 edge = list_entry(cur->upper.next, struct backref_edge,
 749                                   list[LOWER]);
 750                 BUG_ON(!list_empty(&edge->list[UPPER]));
 751                 exist = edge->node[UPPER];
 752                 /*
 753                  * add the upper level block to pending list if we need
 754                  * check its backrefs
 755                  */
 756                 if (!exist->checked)
 757                         list_add_tail(&edge->list[UPPER], &list);
 758         } else {
 759                 exist = NULL;
 760         }
 761
 762         while (1) {
 763                 cond_resched();
 764                 eb = path1->nodes[0];
 765
 766                 if (ptr >= end) {
 767                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 768                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 769                                 if (ret < 0) {
 770                                         err = ret;
 771                                         goto out;
 772                                 }
 773                                 if (ret > 0)
 774                                         break;
 775                                 eb = path1->nodes[0];
 776                         }
 777
 778                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 779                         if (key.objectid != cur->bytenr) {
 780                                 WARN_ON(exist);
 781                                 break;
 782                         }
 783
 784                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 785                             key.type == BTRFS_METADATA_ITEM_KEY) {
 786                                 ret = find_inline_backref(eb, path1->slots[0],
 787                                                           &ptr, &end);
 788                                 if (ret)
 789                                         goto next;
 790                         }
 791                 }
 792
 793                 if (ptr < end) {
 794                         /* update key for inline back ref */
 795                         struct btrfs_extent_inline_ref *iref;
 796                         iref = (struct btrfs_extent_inline_ref *)ptr;
 797                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 798                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 799                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 800                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 801                 }
 802
 803                 if (exist &&
 804                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 805                       exist->owner == key.offset) ||
 806                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 807                       exist->bytenr == key.offset))) {
 808                         exist = NULL;
 809                         goto next;
 810                 }
 811
 812 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 813                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 814                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 815                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 816                                 struct btrfs_extent_ref_v0 *ref0;
 817                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 818                                                 struct btrfs_extent_ref_v0);
 819                                 if (key.objectid == key.offset) {
 820                                         root = find_tree_root(rc, eb, ref0);
 821                                         if (root && !should_ignore_root(root))
 822                                                 cur->root = root;
 823                                         else
 824                                                 list_add(&cur->list, &useless);
 825                                         break;
 826                                 }
 827                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 828                                                                       ref0)))
 829                                         cur->cowonly = 1;
 830                         }
 831 #else
 832                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 833                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 834 #endif
 835                         if (key.objectid == key.offset) {
 836                                 /*
 837                                  * only root blocks of reloc trees use
 838                                  * backref of this type.
 839                                  */
 840                                 root = find_reloc_root(rc, cur->bytenr);
 841                                 BUG_ON(!root);
 842                                 cur->root = root;
 843                                 break;
 844                         }
 845
 846                         edge = alloc_backref_edge(cache);
 847                         if (!edge) {
 848                                 err = -ENOMEM;
 849                                 goto out;
 850                         }
 851                         rb_node = tree_search(&cache->rb_root, key.offset);
 852                         if (!rb_node) {
 853                                 upper = alloc_backref_node(cache);
 854                                 if (!upper) {
 855                                         free_backref_edge(cache, edge);
 856                                         err = -ENOMEM;
 857                                         goto out;
 858                                 }
 859                                 upper->bytenr = key.offset;
 860                                 upper->level = cur->level + 1;
 861                                 /*
 862                                  *  backrefs for the upper level block isn't
 863                                  *  cached, add the block to pending list
 864                                  */
 865                                 list_add_tail(&edge->list[UPPER], &list);
 866                         } else {
 867                                 upper = rb_entry(rb_node, struct backref_node,
 868                                                  rb_node);
 869                                 BUG_ON(!upper->checked);
 870                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 871                         }
 872                         list_add_tail(&edge->list[LOWER], &cur->upper);
 873                         edge->node[LOWER] = cur;
 874                         edge->node[UPPER] = upper;
 875
 876                         goto next;
 877                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 878                         goto next;
 879                 }
 880
 881                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 882                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 883                 if (IS_ERR(root)) {
 884                         err = PTR_ERR(root);
 885                         goto out;
 886                 }
 887
 888                 if (!root->ref_cows)
 889                         cur->cowonly = 1;
 890
 891                 if (btrfs_root_level(&root->root_item) == cur->level) {
 892                         /* tree root */
 893                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 894                                cur->bytenr);
 895                         if (should_ignore_root(root))
 896                                 list_add(&cur->list, &useless);
 897                         else
 898                                 cur->root = root;
 899                         break;
 900                 }
 901
 902                 level = cur->level + 1;
 903
 904                 /*
 905                  * searching the tree to find upper level blocks
 906                  * reference the block.
 907                  */
 908                 path2->search_commit_root = 1;
 909                 path2->skip_locking = 1;
 910                 path2->lowest_level = level;
 911                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 912                 path2->lowest_level = 0;
 913                 if (ret < 0) {
 914                         err = ret;
 915                         goto out;
 916                 }
 917                 if (ret > 0 && path2->slots[level] > 0)
 918                         path2->slots[level]--;
 919
 920                 eb = path2->nodes[level];
 921                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 922                         cur->bytenr);
 923
 924                 lower = cur;
 925                 need_check = true;
 926                 for (; level < BTRFS_MAX_LEVEL; level++) {
 927                         if (!path2->nodes[level]) {
 928                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 929                                        lower->bytenr);
 930                                 if (should_ignore_root(root))
 931                                         list_add(&lower->list, &useless);
 932                                 else
 933                                         lower->root = root;
 934                                 break;
 935                         }
 936
 937                         edge = alloc_backref_edge(cache);
 938                         if (!edge) {
 939                                 err = -ENOMEM;
 940                                 goto out;
 941                         }
 942
 943                         eb = path2->nodes[level];
 944                         rb_node = tree_search(&cache->rb_root, eb->start);
 945                         if (!rb_node) {
 946                                 upper = alloc_backref_node(cache);
 947                                 if (!upper) {
 948                                         free_backref_edge(cache, edge);
 949                                         err = -ENOMEM;
 950                                         goto out;
 951                                 }
 952                                 upper->bytenr = eb->start;
 953                                 upper->owner = btrfs_header_owner(eb);
 954                                 upper->level = lower->level + 1;
 955                                 if (!root->ref_cows)
 956                                         upper->cowonly = 1;
 957
 958                                 /*
 959                                  * if we know the block isn't shared
 960                                  * we can void checking its backrefs.
 961                                  */
 962                                 if (btrfs_block_can_be_shared(root, eb))
 963                                         upper->checked = 0;
 964                                 else
 965                                         upper->checked = 1;
 966
 967                                 /*
 968                                  * add the block to pending list if we
 969                                  * need check its backrefs, we only do this once
 970                                  * while walking up a tree as we will catch
 971                                  * anything else later on.
 972                                  */
 973                                 if (!upper->checked && need_check) {
 974                                         need_check = false;
 975                                         list_add_tail(&edge->list[UPPER],
 976                                                       &list);
 977                                 } else
 978                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 979                         } else {
 980                                 upper = rb_entry(rb_node, struct backref_node,
 981                                                  rb_node);
 982                                 BUG_ON(!upper->checked);
 983                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 984                                 if (!upper->owner)
 985                                         upper->owner = btrfs_header_owner(eb);
 986                         }
 987                         list_add_tail(&edge->list[LOWER], &lower->upper);
 988                         edge->node[LOWER] = lower;
 989                         edge->node[UPPER] = upper;
 990
 991                         if (rb_node)
 992                                 break;
 993                         lower = upper;
 994                         upper = NULL;
 995                 }
 996                 btrfs_release_path(path2);
 997 next:
 998                 if (ptr < end) {
 999                         ptr += btrfs_extent_inline_ref_size(key.type);
1000                         if (ptr >= end) {
1001                                 WARN_ON(ptr > end);
1002                                 ptr = 0;
1003                                 end = 0;
1004                         }
1005                 }
1006                 if (ptr >= end)
1007                         path1->slots[0]++;
1008         }
1009         btrfs_release_path(path1);
1010
1011         cur->checked = 1;
1012         WARN_ON(exist);
1013
1014         /* the pending list isn't empty, take the first block to process */
1015         if (!list_empty(&list)) {
1016                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1017                 list_del_init(&edge->list[UPPER]);
1018                 cur = edge->node[UPPER];
1019                 goto again;
1020         }
1021
1022         /*
1023          * everything goes well, connect backref nodes and insert backref nodes
1024          * into the cache.
1025          */
1026         BUG_ON(!node->checked);
1027         cowonly = node->cowonly;
1028         if (!cowonly) {
1029                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1030                                       &node->rb_node);
1031                 if (rb_node)
1032                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1033                 list_add_tail(&node->lower, &cache->leaves);
1034         }
1035
1036         list_for_each_entry(edge, &node->upper, list[LOWER])
1037                 list_add_tail(&edge->list[UPPER], &list);
1038
1039         while (!list_empty(&list)) {
1040                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1041                 list_del_init(&edge->list[UPPER]);
1042                 upper = edge->node[UPPER];
1043                 if (upper->detached) {
1044                         list_del(&edge->list[LOWER]);
1045                         lower = edge->node[LOWER];
1046                         free_backref_edge(cache, edge);
1047                         if (list_empty(&lower->upper))
1048                                 list_add(&lower->list, &useless);
1049                         continue;
1050                 }
1051
1052                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1053                         if (upper->lowest) {
1054                                 list_del_init(&upper->lower);
1055                                 upper->lowest = 0;
1056                         }
1057
1058                         list_add_tail(&edge->list[UPPER], &upper->lower);
1059                         continue;
1060                 }
1061
1062                 BUG_ON(!upper->checked);
1063                 BUG_ON(cowonly != upper->cowonly);
1064                 if (!cowonly) {
1065                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1066                                               &upper->rb_node);
1067                         if (rb_node)
1068                                 backref_tree_panic(rb_node, -EEXIST,
1069                                                    upper->bytenr);
1070                 }
1071
1072                 list_add_tail(&edge->list[UPPER], &upper->lower);
1073
1074                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1075                         list_add_tail(&edge->list[UPPER], &list);
1076         }
1077         /*
1078          * process useless backref nodes. backref nodes for tree leaves
1079          * are deleted from the cache. backref nodes for upper level
1080          * tree blocks are left in the cache to avoid unnecessary backref
1081          * lookup.
1082          */
1083         while (!list_empty(&useless)) {
1084                 upper = list_entry(useless.next, struct backref_node, list);
1085                 list_del_init(&upper->list);
1086                 BUG_ON(!list_empty(&upper->upper));
1087                 if (upper == node)
1088                         node = NULL;
1089                 if (upper->lowest) {
1090                         list_del_init(&upper->lower);
1091                         upper->lowest = 0;
1092                 }
1093                 while (!list_empty(&upper->lower)) {
1094                         edge = list_entry(upper->lower.next,
1095                                           struct backref_edge, list[UPPER]);
1096                         list_del(&edge->list[UPPER]);
1097                         list_del(&edge->list[LOWER]);
1098                         lower = edge->node[LOWER];
1099                         free_backref_edge(cache, edge);
1100
1101                         if (list_empty(&lower->upper))
1102                                 list_add(&lower->list, &useless);
1103                 }
1104                 __mark_block_processed(rc, upper);
1105                 if (upper->level > 0) {
1106                         list_add(&upper->list, &cache->detached);
1107                         upper->detached = 1;
1108                 } else {
1109                         rb_erase(&upper->rb_node, &cache->rb_root);
1110                         free_backref_node(cache, upper);
1111                 }
1112         }
1113 out:
1114         btrfs_free_path(path1);
1115         btrfs_free_path(path2);
1116         if (err) {
1117                 while (!list_empty(&useless)) {
1118                         lower = list_entry(useless.next,
1119                                            struct backref_node, upper);
1120                         list_del_init(&lower->upper);
1121                 }
1122                 upper = node;
1123                 INIT_LIST_HEAD(&list);
1124                 while (upper) {
1125                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1126                                 list_splice_tail(&upper->upper, &list);
1127                                 free_backref_node(cache, upper);
1128                         }
1129
1130                         if (list_empty(&list))
1131                                 break;
1132
1133                         edge = list_entry(list.next, struct backref_edge,
1134                                           list[LOWER]);
1135                         list_del(&edge->list[LOWER]);
1136                         upper = edge->node[UPPER];
1137                         free_backref_edge(cache, edge);
1138                 }
1139                 return ERR_PTR(err);
1140         }
1141         BUG_ON(node && node->detached);
1142         return node;
1143 }
1144
1145 /*
1146  * helper to add backref node for the newly created snapshot.
1147  * the backref node is created by cloning backref node that
1148  * corresponds to root of source tree
1149  */
1150 static int clone_backref_node(struct btrfs_trans_handle *trans,
1151                               struct reloc_control *rc,
1152                               struct btrfs_root *src,
1153                               struct btrfs_root *dest)
1154 {
1155         struct btrfs_root *reloc_root = src->reloc_root;
1156         struct backref_cache *cache = &rc->backref_cache;
1157         struct backref_node *node = NULL;
1158         struct backref_node *new_node;
1159         struct backref_edge *edge;
1160         struct backref_edge *new_edge;
1161         struct rb_node *rb_node;
1162
1163         if (cache->last_trans > 0)
1164                 update_backref_cache(trans, cache);
1165
1166         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1167         if (rb_node) {
1168                 node = rb_entry(rb_node, struct backref_node, rb_node);
1169                 if (node->detached)
1170                         node = NULL;
1171                 else
1172                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1173         }
1174
1175         if (!node) {
1176                 rb_node = tree_search(&cache->rb_root,
1177                                       reloc_root->commit_root->start);
1178                 if (rb_node) {
1179                         node = rb_entry(rb_node, struct backref_node,
1180                                         rb_node);
1181                         BUG_ON(node->detached);
1182                 }
1183         }
1184
1185         if (!node)
1186                 return 0;
1187
1188         new_node = alloc_backref_node(cache);
1189         if (!new_node)
1190                 return -ENOMEM;
1191
1192         new_node->bytenr = dest->node->start;
1193         new_node->level = node->level;
1194         new_node->lowest = node->lowest;
1195         new_node->checked = 1;
1196         new_node->root = dest;
1197
1198         if (!node->lowest) {
1199                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1200                         new_edge = alloc_backref_edge(cache);
1201                         if (!new_edge)
1202                                 goto fail;
1203
1204                         new_edge->node[UPPER] = new_node;
1205                         new_edge->node[LOWER] = edge->node[LOWER];
1206                         list_add_tail(&new_edge->list[UPPER],
1207                                       &new_node->lower);
1208                 }
1209         } else {
1210                 list_add_tail(&new_node->lower, &cache->leaves);
1211         }
1212
1213         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1214                               &new_node->rb_node);
1215         if (rb_node)
1216                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1217
1218         if (!new_node->lowest) {
1219                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1220                         list_add_tail(&new_edge->list[LOWER],
1221                                       &new_edge->node[LOWER]->upper);
1222                 }
1223         }
1224         return 0;
1225 fail:
1226         while (!list_empty(&new_node->lower)) {
1227                 new_edge = list_entry(new_node->lower.next,
1228                                       struct backref_edge, list[UPPER]);
1229                 list_del(&new_edge->list[UPPER]);
1230                 free_backref_edge(cache, new_edge);
1231         }
1232         free_backref_node(cache, new_node);
1233         return -ENOMEM;
1234 }
1235
1236 /*
1237  * helper to add 'address of tree root -> reloc tree' mapping
1238  */
1239 static int __must_check __add_reloc_root(struct btrfs_root *root)
1240 {
1241         struct rb_node *rb_node;
1242         struct mapping_node *node;
1243         struct reloc_control *rc = root->fs_info->reloc_ctl;
1244
1245         node = kmalloc(sizeof(*node), GFP_NOFS);
1246         if (!node)
1247                 return -ENOMEM;
1248
1249         node->bytenr = root->node->start;
1250         node->data = root;
1251
1252         spin_lock(&rc->reloc_root_tree.lock);
1253         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1254                               node->bytenr, &node->rb_node);
1255         spin_unlock(&rc->reloc_root_tree.lock);
1256         if (rb_node) {
1257                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1258                             "for start=%llu while inserting into relocation "
1259                             "tree\n", node->bytenr);
1260                 kfree(node);
1261                 return -EEXIST;
1262         }
1263
1264         list_add_tail(&root->root_list, &rc->reloc_roots);
1265         return 0;
1266 }
1267
1268 /*
1269  * helper to delete the 'address of tree root -> reloc tree'
1270  * mapping
1271  */
1272 static void __del_reloc_root(struct btrfs_root *root)
1273 {
1274         struct rb_node *rb_node;
1275         struct mapping_node *node = NULL;
1276         struct reloc_control *rc = root->fs_info->reloc_ctl;
1277
1278         spin_lock(&rc->reloc_root_tree.lock);
1279         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1280                               root->node->start);
1281         if (rb_node) {
1282                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1283                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1284         }
1285         spin_unlock(&rc->reloc_root_tree.lock);
1286
1287         if (!node)
1288                 return;
1289         BUG_ON((struct btrfs_root *)node->data != root);
1290
1291         spin_lock(&root->fs_info->trans_lock);
1292         list_del_init(&root->root_list);
1293         spin_unlock(&root->fs_info->trans_lock);
1294         kfree(node);
1295 }
1296
1297 /*
1298  * helper to update the 'address of tree root -> reloc tree'
1299  * mapping
1300  */
1301 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1302 {
1303         struct rb_node *rb_node;
1304         struct mapping_node *node = NULL;
1305         struct reloc_control *rc = root->fs_info->reloc_ctl;
1306
1307         spin_lock(&rc->reloc_root_tree.lock);
1308         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1309                               root->node->start);
1310         if (rb_node) {
1311                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1312                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1313         }
1314         spin_unlock(&rc->reloc_root_tree.lock);
1315
1316         if (!node)
1317                 return 0;
1318         BUG_ON((struct btrfs_root *)node->data != root);
1319
1320         spin_lock(&rc->reloc_root_tree.lock);
1321         node->bytenr = new_bytenr;
1322         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1323                               node->bytenr, &node->rb_node);
1324         spin_unlock(&rc->reloc_root_tree.lock);
1325         if (rb_node)
1326                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1327         return 0;
1328 }
1329
1330 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1331                                         struct btrfs_root *root, u64 objectid)
1332 {
1333         struct btrfs_root *reloc_root;
1334         struct extent_buffer *eb;
1335         struct btrfs_root_item *root_item;
1336         struct btrfs_key root_key;
1337         u64 last_snap = 0;
1338         int ret;
1339
1340         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1341         BUG_ON(!root_item);
1342
1343         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1344         root_key.type = BTRFS_ROOT_ITEM_KEY;
1345         root_key.offset = objectid;
1346
1347         if (root->root_key.objectid == objectid) {
1348                 /* called by btrfs_init_reloc_root */
1349                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1350                                       BTRFS_TREE_RELOC_OBJECTID);
1351                 BUG_ON(ret);
1352
1353                 last_snap = btrfs_root_last_snapshot(&root->root_item);
1354                 btrfs_set_root_last_snapshot(&root->root_item,
1355                                              trans->transid - 1);
1356         } else {
1357                 /*
1358                  * called by btrfs_reloc_post_snapshot_hook.
1359                  * the source tree is a reloc tree, all tree blocks
1360                  * modified after it was created have RELOC flag
1361                  * set in their headers. so it's OK to not update
1362                  * the 'last_snapshot'.
1363                  */
1364                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1365                                       BTRFS_TREE_RELOC_OBJECTID);
1366                 BUG_ON(ret);
1367         }
1368
1369         memcpy(root_item, &root->root_item, sizeof(*root_item));
1370         btrfs_set_root_bytenr(root_item, eb->start);
1371         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1372         btrfs_set_root_generation(root_item, trans->transid);
1373
1374         if (root->root_key.objectid == objectid) {
1375                 btrfs_set_root_refs(root_item, 0);
1376                 memset(&root_item->drop_progress, 0,
1377                        sizeof(struct btrfs_disk_key));
1378                 root_item->drop_level = 0;
1379                 /*
1380                  * abuse rtransid, it is safe because it is impossible to
1381                  * receive data into a relocation tree.
1382                  */
1383                 btrfs_set_root_rtransid(root_item, last_snap);
1384                 btrfs_set_root_otransid(root_item, trans->transid);
1385         }
1386
1387         btrfs_tree_unlock(eb);
1388         free_extent_buffer(eb);
1389
1390         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1391                                 &root_key, root_item);
1392         BUG_ON(ret);
1393         kfree(root_item);
1394
1395         reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
1396         BUG_ON(IS_ERR(reloc_root));
1397         reloc_root->last_trans = trans->transid;
1398         return reloc_root;
1399 }
1400
1401 /*
1402  * create reloc tree for a given fs tree. reloc tree is just a
1403  * snapshot of the fs tree with special root objectid.
1404  */
1405 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1406                           struct btrfs_root *root)
1407 {
1408         struct btrfs_root *reloc_root;
1409         struct reloc_control *rc = root->fs_info->reloc_ctl;
1410         struct btrfs_block_rsv *rsv;
1411         int clear_rsv = 0;
1412         int ret;
1413
1414         if (root->reloc_root) {
1415                 reloc_root = root->reloc_root;
1416                 reloc_root->last_trans = trans->transid;
1417                 return 0;
1418         }
1419
1420         if (!rc || !rc->create_reloc_tree ||
1421             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1422                 return 0;
1423
1424         if (!trans->reloc_reserved) {
1425                 rsv = trans->block_rsv;
1426                 trans->block_rsv = rc->block_rsv;
1427                 clear_rsv = 1;
1428         }
1429         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1430         if (clear_rsv)
1431                 trans->block_rsv = rsv;
1432
1433         ret = __add_reloc_root(reloc_root);
1434         BUG_ON(ret < 0);
1435         root->reloc_root = reloc_root;
1436         return 0;
1437 }
1438
1439 /*
1440  * update root item of reloc tree
1441  */
1442 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1443                             struct btrfs_root *root)
1444 {
1445         struct btrfs_root *reloc_root;
1446         struct btrfs_root_item *root_item;
1447         int ret;
1448
1449         if (!root->reloc_root)
1450                 goto out;
1451
1452         reloc_root = root->reloc_root;
1453         root_item = &reloc_root->root_item;
1454
1455         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1456             btrfs_root_refs(root_item) == 0) {
1457                 root->reloc_root = NULL;
1458                 __del_reloc_root(reloc_root);
1459         }
1460
1461         if (reloc_root->commit_root != reloc_root->node) {
1462                 btrfs_set_root_node(root_item, reloc_root->node);
1463                 free_extent_buffer(reloc_root->commit_root);
1464                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1465         }
1466
1467         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1468                                 &reloc_root->root_key, root_item);
1469         BUG_ON(ret);
1470
1471 out:
1472         return 0;
1473 }
1474
1475 /*
1476  * helper to find first cached inode with inode number >= objectid
1477  * in a subvolume
1478  */
1479 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1480 {
1481         struct rb_node *node;
1482         struct rb_node *prev;
1483         struct btrfs_inode *entry;
1484         struct inode *inode;
1485
1486         spin_lock(&root->inode_lock);
1487 again:
1488         node = root->inode_tree.rb_node;
1489         prev = NULL;
1490         while (node) {
1491                 prev = node;
1492                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1493
1494                 if (objectid < btrfs_ino(&entry->vfs_inode))
1495                         node = node->rb_left;
1496                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1497                         node = node->rb_right;
1498                 else
1499                         break;
1500         }
1501         if (!node) {
1502                 while (prev) {
1503                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1504                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1505                                 node = prev;
1506                                 break;
1507                         }
1508                         prev = rb_next(prev);
1509                 }
1510         }
1511         while (node) {
1512                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1513                 inode = igrab(&entry->vfs_inode);
1514                 if (inode) {
1515                         spin_unlock(&root->inode_lock);
1516                         return inode;
1517                 }
1518
1519                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1520                 if (cond_resched_lock(&root->inode_lock))
1521                         goto again;
1522
1523                 node = rb_next(node);
1524         }
1525         spin_unlock(&root->inode_lock);
1526         return NULL;
1527 }
1528
1529 static int in_block_group(u64 bytenr,
1530                           struct btrfs_block_group_cache *block_group)
1531 {
1532         if (bytenr >= block_group->key.objectid &&
1533             bytenr < block_group->key.objectid + block_group->key.offset)
1534                 return 1;
1535         return 0;
1536 }
1537
1538 /*
1539  * get new location of data
1540  */
1541 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1542                             u64 bytenr, u64 num_bytes)
1543 {
1544         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1545         struct btrfs_path *path;
1546         struct btrfs_file_extent_item *fi;
1547         struct extent_buffer *leaf;
1548         int ret;
1549
1550         path = btrfs_alloc_path();
1551         if (!path)
1552                 return -ENOMEM;
1553
1554         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1555         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1556                                        bytenr, 0);
1557         if (ret < 0)
1558                 goto out;
1559         if (ret > 0) {
1560                 ret = -ENOENT;
1561                 goto out;
1562         }
1563
1564         leaf = path->nodes[0];
1565         fi = btrfs_item_ptr(leaf, path->slots[0],
1566                             struct btrfs_file_extent_item);
1567
1568         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1569                btrfs_file_extent_compression(leaf, fi) ||
1570                btrfs_file_extent_encryption(leaf, fi) ||
1571                btrfs_file_extent_other_encoding(leaf, fi));
1572
1573         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1574                 ret = -EINVAL;
1575                 goto out;
1576         }
1577
1578         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1579         ret = 0;
1580 out:
1581         btrfs_free_path(path);
1582         return ret;
1583 }
1584
1585 /*
1586  * update file extent items in the tree leaf to point to
1587  * the new locations.
1588  */
1589 static noinline_for_stack
1590 int replace_file_extents(struct btrfs_trans_handle *trans,
1591                          struct reloc_control *rc,
1592                          struct btrfs_root *root,
1593                          struct extent_buffer *leaf)
1594 {
1595         struct btrfs_key key;
1596         struct btrfs_file_extent_item *fi;
1597         struct inode *inode = NULL;
1598         u64 parent;
1599         u64 bytenr;
1600         u64 new_bytenr = 0;
1601         u64 num_bytes;
1602         u64 end;
1603         u32 nritems;
1604         u32 i;
1605         int ret = 0;
1606         int first = 1;
1607         int dirty = 0;
1608
1609         if (rc->stage != UPDATE_DATA_PTRS)
1610                 return 0;
1611
1612         /* reloc trees always use full backref */
1613         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1614                 parent = leaf->start;
1615         else
1616                 parent = 0;
1617
1618         nritems = btrfs_header_nritems(leaf);
1619         for (i = 0; i < nritems; i++) {
1620                 cond_resched();
1621                 btrfs_item_key_to_cpu(leaf, &key, i);
1622                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1623                         continue;
1624                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1625                 if (btrfs_file_extent_type(leaf, fi) ==
1626                     BTRFS_FILE_EXTENT_INLINE)
1627                         continue;
1628                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1629                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1630                 if (bytenr == 0)
1631                         continue;
1632                 if (!in_block_group(bytenr, rc->block_group))
1633                         continue;
1634
1635                 /*
1636                  * if we are modifying block in fs tree, wait for readpage
1637                  * to complete and drop the extent cache
1638                  */
1639                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1640                         if (first) {
1641                                 inode = find_next_inode(root, key.objectid);
1642                                 first = 0;
1643                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1644                                 btrfs_add_delayed_iput(inode);
1645                                 inode = find_next_inode(root, key.objectid);
1646                         }
1647                         if (inode && btrfs_ino(inode) == key.objectid) {
1648                                 end = key.offset +
1649                                       btrfs_file_extent_num_bytes(leaf, fi);
1650                                 WARN_ON(!IS_ALIGNED(key.offset,
1651                                                     root->sectorsize));
1652                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1653                                 end--;
1654                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1655                                                       key.offset, end);
1656                                 if (!ret)
1657                                         continue;
1658
1659                                 btrfs_drop_extent_cache(inode, key.offset, end,
1660                                                         1);
1661                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1662                                               key.offset, end);
1663                         }
1664                 }
1665
1666                 ret = get_new_location(rc->data_inode, &new_bytenr,
1667                                        bytenr, num_bytes);
1668                 if (ret) {
1669                         /*
1670                          * Don't have to abort since we've not changed anything
1671                          * in the file extent yet.
1672                          */
1673                         break;
1674                 }
1675
1676                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1677                 dirty = 1;
1678
1679                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1680                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1681                                            num_bytes, parent,
1682                                            btrfs_header_owner(leaf),
1683                                            key.objectid, key.offset, 1);
1684                 if (ret) {
1685                         btrfs_abort_transaction(trans, root, ret);
1686                         break;
1687                 }
1688
1689                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1690                                         parent, btrfs_header_owner(leaf),
1691                                         key.objectid, key.offset, 1);
1692                 if (ret) {
1693                         btrfs_abort_transaction(trans, root, ret);
1694                         break;
1695                 }
1696         }
1697         if (dirty)
1698                 btrfs_mark_buffer_dirty(leaf);
1699         if (inode)
1700                 btrfs_add_delayed_iput(inode);
1701         return ret;
1702 }
1703
1704 static noinline_for_stack
1705 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1706                      struct btrfs_path *path, int level)
1707 {
1708         struct btrfs_disk_key key1;
1709         struct btrfs_disk_key key2;
1710         btrfs_node_key(eb, &key1, slot);
1711         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1712         return memcmp(&key1, &key2, sizeof(key1));
1713 }
1714
1715 /*
1716  * try to replace tree blocks in fs tree with the new blocks
1717  * in reloc tree. tree blocks haven't been modified since the
1718  * reloc tree was create can be replaced.
1719  *
1720  * if a block was replaced, level of the block + 1 is returned.
1721  * if no block got replaced, 0 is returned. if there are other
1722  * errors, a negative error number is returned.
1723  */
1724 static noinline_for_stack
1725 int replace_path(struct btrfs_trans_handle *trans,
1726                  struct btrfs_root *dest, struct btrfs_root *src,
1727                  struct btrfs_path *path, struct btrfs_key *next_key,
1728                  int lowest_level, int max_level)
1729 {
1730         struct extent_buffer *eb;
1731         struct extent_buffer *parent;
1732         struct btrfs_key key;
1733         u64 old_bytenr;
1734         u64 new_bytenr;
1735         u64 old_ptr_gen;
1736         u64 new_ptr_gen;
1737         u64 last_snapshot;
1738         u32 blocksize;
1739         int cow = 0;
1740         int level;
1741         int ret;
1742         int slot;
1743
1744         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1745         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1746
1747         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1748 again:
1749         slot = path->slots[lowest_level];
1750         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1751
1752         eb = btrfs_lock_root_node(dest);
1753         btrfs_set_lock_blocking(eb);
1754         level = btrfs_header_level(eb);
1755
1756         if (level < lowest_level) {
1757                 btrfs_tree_unlock(eb);
1758                 free_extent_buffer(eb);
1759                 return 0;
1760         }
1761
1762         if (cow) {
1763                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1764                 BUG_ON(ret);
1765         }
1766         btrfs_set_lock_blocking(eb);
1767
1768         if (next_key) {
1769                 next_key->objectid = (u64)-1;
1770                 next_key->type = (u8)-1;
1771                 next_key->offset = (u64)-1;
1772         }
1773
1774         parent = eb;
1775         while (1) {
1776                 level = btrfs_header_level(parent);
1777                 BUG_ON(level < lowest_level);
1778
1779                 ret = btrfs_bin_search(parent, &key, level, &slot);
1780                 if (ret && slot > 0)
1781                         slot--;
1782
1783                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1784                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1785
1786                 old_bytenr = btrfs_node_blockptr(parent, slot);
1787                 blocksize = btrfs_level_size(dest, level - 1);
1788                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1789
1790                 if (level <= max_level) {
1791                         eb = path->nodes[level];
1792                         new_bytenr = btrfs_node_blockptr(eb,
1793                                                         path->slots[level]);
1794                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1795                                                         path->slots[level]);
1796                 } else {
1797                         new_bytenr = 0;
1798                         new_ptr_gen = 0;
1799                 }
1800
1801                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1802                         ret = level;
1803                         break;
1804                 }
1805
1806                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1807                     memcmp_node_keys(parent, slot, path, level)) {
1808                         if (level <= lowest_level) {
1809                                 ret = 0;
1810                                 break;
1811                         }
1812
1813                         eb = read_tree_block(dest, old_bytenr, blocksize,
1814                                              old_ptr_gen);
1815                         if (!eb || !extent_buffer_uptodate(eb)) {
1816                                 ret = (!eb) ? -ENOMEM : -EIO;
1817                                 free_extent_buffer(eb);
1818                                 break;
1819                         }
1820                         btrfs_tree_lock(eb);
1821                         if (cow) {
1822                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1823                                                       slot, &eb);
1824                                 BUG_ON(ret);
1825                         }
1826                         btrfs_set_lock_blocking(eb);
1827
1828                         btrfs_tree_unlock(parent);
1829                         free_extent_buffer(parent);
1830
1831                         parent = eb;
1832                         continue;
1833                 }
1834
1835                 if (!cow) {
1836                         btrfs_tree_unlock(parent);
1837                         free_extent_buffer(parent);
1838                         cow = 1;
1839                         goto again;
1840                 }
1841
1842                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1843                                       path->slots[level]);
1844                 btrfs_release_path(path);
1845
1846                 path->lowest_level = level;
1847                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1848                 path->lowest_level = 0;
1849                 BUG_ON(ret);
1850
1851                 /*
1852                  * swap blocks in fs tree and reloc tree.
1853                  */
1854                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1855                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1856                 btrfs_mark_buffer_dirty(parent);
1857
1858                 btrfs_set_node_blockptr(path->nodes[level],
1859                                         path->slots[level], old_bytenr);
1860                 btrfs_set_node_ptr_generation(path->nodes[level],
1861                                               path->slots[level], old_ptr_gen);
1862                 btrfs_mark_buffer_dirty(path->nodes[level]);
1863
1864                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1865                                         path->nodes[level]->start,
1866                                         src->root_key.objectid, level - 1, 0,
1867                                         1);
1868                 BUG_ON(ret);
1869                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1870                                         0, dest->root_key.objectid, level - 1,
1871                                         0, 1);
1872                 BUG_ON(ret);
1873
1874                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1875                                         path->nodes[level]->start,
1876                                         src->root_key.objectid, level - 1, 0,
1877                                         1);
1878                 BUG_ON(ret);
1879
1880                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1881                                         0, dest->root_key.objectid, level - 1,
1882                                         0, 1);
1883                 BUG_ON(ret);
1884
1885                 btrfs_unlock_up_safe(path, 0);
1886
1887                 ret = level;
1888                 break;
1889         }
1890         btrfs_tree_unlock(parent);
1891         free_extent_buffer(parent);
1892         return ret;
1893 }
1894
1895 /*
1896  * helper to find next relocated block in reloc tree
1897  */
1898 static noinline_for_stack
1899 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1900                        int *level)
1901 {
1902         struct extent_buffer *eb;
1903         int i;
1904         u64 last_snapshot;
1905         u32 nritems;
1906
1907         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1908
1909         for (i = 0; i < *level; i++) {
1910                 free_extent_buffer(path->nodes[i]);
1911                 path->nodes[i] = NULL;
1912         }
1913
1914         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1915                 eb = path->nodes[i];
1916                 nritems = btrfs_header_nritems(eb);
1917                 while (path->slots[i] + 1 < nritems) {
1918                         path->slots[i]++;
1919                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1920                             last_snapshot)
1921                                 continue;
1922
1923                         *level = i;
1924                         return 0;
1925                 }
1926                 free_extent_buffer(path->nodes[i]);
1927                 path->nodes[i] = NULL;
1928         }
1929         return 1;
1930 }
1931
1932 /*
1933  * walk down reloc tree to find relocated block of lowest level
1934  */
1935 static noinline_for_stack
1936 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1937                          int *level)
1938 {
1939         struct extent_buffer *eb = NULL;
1940         int i;
1941         u64 bytenr;
1942         u64 ptr_gen = 0;
1943         u64 last_snapshot;
1944         u32 blocksize;
1945         u32 nritems;
1946
1947         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1948
1949         for (i = *level; i > 0; i--) {
1950                 eb = path->nodes[i];
1951                 nritems = btrfs_header_nritems(eb);
1952                 while (path->slots[i] < nritems) {
1953                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1954                         if (ptr_gen > last_snapshot)
1955                                 break;
1956                         path->slots[i]++;
1957                 }
1958                 if (path->slots[i] >= nritems) {
1959                         if (i == *level)
1960                                 break;
1961                         *level = i + 1;
1962                         return 0;
1963                 }
1964                 if (i == 1) {
1965                         *level = i;
1966                         return 0;
1967                 }
1968
1969                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1970                 blocksize = btrfs_level_size(root, i - 1);
1971                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1972                 if (!eb || !extent_buffer_uptodate(eb)) {
1973                         free_extent_buffer(eb);
1974                         return -EIO;
1975                 }
1976                 BUG_ON(btrfs_header_level(eb) != i - 1);
1977                 path->nodes[i - 1] = eb;
1978                 path->slots[i - 1] = 0;
1979         }
1980         return 1;
1981 }
1982
1983 /*
1984  * invalidate extent cache for file extents whose key in range of
1985  * [min_key, max_key)
1986  */
1987 static int invalidate_extent_cache(struct btrfs_root *root,
1988                                    struct btrfs_key *min_key,
1989                                    struct btrfs_key *max_key)
1990 {
1991         struct inode *inode = NULL;
1992         u64 objectid;
1993         u64 start, end;
1994         u64 ino;
1995
1996         objectid = min_key->objectid;
1997         while (1) {
1998                 cond_resched();
1999                 iput(inode);
2000
2001                 if (objectid > max_key->objectid)
2002                         break;
2003
2004                 inode = find_next_inode(root, objectid);
2005                 if (!inode)
2006                         break;
2007                 ino = btrfs_ino(inode);
2008
2009                 if (ino > max_key->objectid) {
2010                         iput(inode);
2011                         break;
2012                 }
2013
2014                 objectid = ino + 1;
2015                 if (!S_ISREG(inode->i_mode))
2016                         continue;
2017
2018                 if (unlikely(min_key->objectid == ino)) {
2019                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2020                                 continue;
2021                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2022                                 start = 0;
2023                         else {
2024                                 start = min_key->offset;
2025                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2026                         }
2027                 } else {
2028                         start = 0;
2029                 }
2030
2031                 if (unlikely(max_key->objectid == ino)) {
2032                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2033                                 continue;
2034                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2035                                 end = (u64)-1;
2036                         } else {
2037                                 if (max_key->offset == 0)
2038                                         continue;
2039                                 end = max_key->offset;
2040                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2041                                 end--;
2042                         }
2043                 } else {
2044                         end = (u64)-1;
2045                 }
2046
2047                 /* the lock_extent waits for readpage to complete */
2048                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2049                 btrfs_drop_extent_cache(inode, start, end, 1);
2050                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2051         }
2052         return 0;
2053 }
2054
2055 static int find_next_key(struct btrfs_path *path, int level,
2056                          struct btrfs_key *key)
2057
2058 {
2059         while (level < BTRFS_MAX_LEVEL) {
2060                 if (!path->nodes[level])
2061                         break;
2062                 if (path->slots[level] + 1 <
2063                     btrfs_header_nritems(path->nodes[level])) {
2064                         btrfs_node_key_to_cpu(path->nodes[level], key,
2065                                               path->slots[level] + 1);
2066                         return 0;
2067                 }
2068                 level++;
2069         }
2070         return 1;
2071 }
2072
2073 /*
2074  * merge the relocated tree blocks in reloc tree with corresponding
2075  * fs tree.
2076  */
2077 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2078                                                struct btrfs_root *root)
2079 {
2080         LIST_HEAD(inode_list);
2081         struct btrfs_key key;
2082         struct btrfs_key next_key;
2083         struct btrfs_trans_handle *trans = NULL;
2084         struct btrfs_root *reloc_root;
2085         struct btrfs_root_item *root_item;
2086         struct btrfs_path *path;
2087         struct extent_buffer *leaf;
2088         int level;
2089         int max_level;
2090         int replaced = 0;
2091         int ret;
2092         int err = 0;
2093         u32 min_reserved;
2094
2095         path = btrfs_alloc_path();
2096         if (!path)
2097                 return -ENOMEM;
2098         path->reada = 1;
2099
2100         reloc_root = root->reloc_root;
2101         root_item = &reloc_root->root_item;
2102
2103         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2104                 level = btrfs_root_level(root_item);
2105                 extent_buffer_get(reloc_root->node);
2106                 path->nodes[level] = reloc_root->node;
2107                 path->slots[level] = 0;
2108         } else {
2109                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2110
2111                 level = root_item->drop_level;
2112                 BUG_ON(level == 0);
2113                 path->lowest_level = level;
2114                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2115                 path->lowest_level = 0;
2116                 if (ret < 0) {
2117                         btrfs_free_path(path);
2118                         return ret;
2119                 }
2120
2121                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2122                                       path->slots[level]);
2123                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2124
2125                 btrfs_unlock_up_safe(path, 0);
2126         }
2127
2128         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2129         memset(&next_key, 0, sizeof(next_key));
2130
2131         while (1) {
2132                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2133                                              BTRFS_RESERVE_FLUSH_ALL);
2134                 if (ret) {
2135                         err = ret;
2136                         goto out;
2137                 }
2138                 trans = btrfs_start_transaction(root, 0);
2139                 if (IS_ERR(trans)) {
2140                         err = PTR_ERR(trans);
2141                         trans = NULL;
2142                         goto out;
2143                 }
2144                 trans->block_rsv = rc->block_rsv;
2145
2146                 replaced = 0;
2147                 max_level = level;
2148
2149                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2150                 if (ret < 0) {
2151                         err = ret;
2152                         goto out;
2153                 }
2154                 if (ret > 0)
2155                         break;
2156
2157                 if (!find_next_key(path, level, &key) &&
2158                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2159                         ret = 0;
2160                 } else {
2161                         ret = replace_path(trans, root, reloc_root, path,
2162                                            &next_key, level, max_level);
2163                 }
2164                 if (ret < 0) {
2165                         err = ret;
2166                         goto out;
2167                 }
2168
2169                 if (ret > 0) {
2170                         level = ret;
2171                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2172                                               path->slots[level]);
2173                         replaced = 1;
2174                 }
2175
2176                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2177                 if (ret > 0)
2178                         break;
2179
2180                 BUG_ON(level == 0);
2181                 /*
2182                  * save the merging progress in the drop_progress.
2183                  * this is OK since root refs == 1 in this case.
2184                  */
2185                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2186                                path->slots[level]);
2187                 root_item->drop_level = level;
2188
2189                 btrfs_end_transaction_throttle(trans, root);
2190                 trans = NULL;
2191
2192                 btrfs_btree_balance_dirty(root);
2193
2194                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2195                         invalidate_extent_cache(root, &key, &next_key);
2196         }
2197
2198         /*
2199          * handle the case only one block in the fs tree need to be
2200          * relocated and the block is tree root.
2201          */
2202         leaf = btrfs_lock_root_node(root);
2203         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2204         btrfs_tree_unlock(leaf);
2205         free_extent_buffer(leaf);
2206         if (ret < 0)
2207                 err = ret;
2208 out:
2209         btrfs_free_path(path);
2210
2211         if (err == 0) {
2212                 memset(&root_item->drop_progress, 0,
2213                        sizeof(root_item->drop_progress));
2214                 root_item->drop_level = 0;
2215                 btrfs_set_root_refs(root_item, 0);
2216                 btrfs_update_reloc_root(trans, root);
2217         }
2218
2219         if (trans)
2220                 btrfs_end_transaction_throttle(trans, root);
2221
2222         btrfs_btree_balance_dirty(root);
2223
2224         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2225                 invalidate_extent_cache(root, &key, &next_key);
2226
2227         return err;
2228 }
2229
2230 static noinline_for_stack
2231 int prepare_to_merge(struct reloc_control *rc, int err)
2232 {
2233         struct btrfs_root *root = rc->extent_root;
2234         struct btrfs_root *reloc_root;
2235         struct btrfs_trans_handle *trans;
2236         LIST_HEAD(reloc_roots);
2237         u64 num_bytes = 0;
2238         int ret;
2239
2240         mutex_lock(&root->fs_info->reloc_mutex);
2241         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2242         rc->merging_rsv_size += rc->nodes_relocated * 2;
2243         mutex_unlock(&root->fs_info->reloc_mutex);
2244
2245 again:
2246         if (!err) {
2247                 num_bytes = rc->merging_rsv_size;
2248                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2249                                           BTRFS_RESERVE_FLUSH_ALL);
2250                 if (ret)
2251                         err = ret;
2252         }
2253
2254         trans = btrfs_join_transaction(rc->extent_root);
2255         if (IS_ERR(trans)) {
2256                 if (!err)
2257                         btrfs_block_rsv_release(rc->extent_root,
2258                                                 rc->block_rsv, num_bytes);
2259                 return PTR_ERR(trans);
2260         }
2261
2262         if (!err) {
2263                 if (num_bytes != rc->merging_rsv_size) {
2264                         btrfs_end_transaction(trans, rc->extent_root);
2265                         btrfs_block_rsv_release(rc->extent_root,
2266                                                 rc->block_rsv, num_bytes);
2267                         goto again;
2268                 }
2269         }
2270
2271         rc->merge_reloc_tree = 1;
2272
2273         while (!list_empty(&rc->reloc_roots)) {
2274                 reloc_root = list_entry(rc->reloc_roots.next,
2275                                         struct btrfs_root, root_list);
2276                 list_del_init(&reloc_root->root_list);
2277
2278                 root = read_fs_root(reloc_root->fs_info,
2279                                     reloc_root->root_key.offset);
2280                 BUG_ON(IS_ERR(root));
2281                 BUG_ON(root->reloc_root != reloc_root);
2282
2283                 /*
2284                  * set reference count to 1, so btrfs_recover_relocation
2285                  * knows it should resumes merging
2286                  */
2287                 if (!err)
2288                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2289                 btrfs_update_reloc_root(trans, root);
2290
2291                 list_add(&reloc_root->root_list, &reloc_roots);
2292         }
2293
2294         list_splice(&reloc_roots, &rc->reloc_roots);
2295
2296         if (!err)
2297                 btrfs_commit_transaction(trans, rc->extent_root);
2298         else
2299                 btrfs_end_transaction(trans, rc->extent_root);
2300         return err;
2301 }
2302
2303 static noinline_for_stack
2304 void free_reloc_roots(struct list_head *list)
2305 {
2306         struct btrfs_root *reloc_root;
2307
2308         while (!list_empty(list)) {
2309                 reloc_root = list_entry(list->next, struct btrfs_root,
2310                                         root_list);
2311                 __del_reloc_root(reloc_root);
2312                 free_extent_buffer(reloc_root->node);
2313                 free_extent_buffer(reloc_root->commit_root);
2314                 kfree(reloc_root);
2315         }
2316 }
2317
2318 static noinline_for_stack
2319 int merge_reloc_roots(struct reloc_control *rc)
2320 {
2321         struct btrfs_trans_handle *trans;
2322         struct btrfs_root *root;
2323         struct btrfs_root *reloc_root;
2324         u64 last_snap;
2325         u64 otransid;
2326         u64 objectid;
2327         LIST_HEAD(reloc_roots);
2328         int found = 0;
2329         int ret = 0;
2330 again:
2331         root = rc->extent_root;
2332
2333         /*
2334          * this serializes us with btrfs_record_root_in_transaction,
2335          * we have to make sure nobody is in the middle of
2336          * adding their roots to the list while we are
2337          * doing this splice
2338          */
2339         mutex_lock(&root->fs_info->reloc_mutex);
2340         list_splice_init(&rc->reloc_roots, &reloc_roots);
2341         mutex_unlock(&root->fs_info->reloc_mutex);
2342
2343         while (!list_empty(&reloc_roots)) {
2344                 found = 1;
2345                 reloc_root = list_entry(reloc_roots.next,
2346                                         struct btrfs_root, root_list);
2347
2348                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2349                         root = read_fs_root(reloc_root->fs_info,
2350                                             reloc_root->root_key.offset);
2351                         BUG_ON(IS_ERR(root));
2352                         BUG_ON(root->reloc_root != reloc_root);
2353
2354                         ret = merge_reloc_root(rc, root);
2355                         if (ret) {
2356                                 __del_reloc_root(reloc_root);
2357                                 free_extent_buffer(reloc_root->node);
2358                                 free_extent_buffer(reloc_root->commit_root);
2359                                 kfree(reloc_root);
2360                                 goto out;
2361                         }
2362                 } else {
2363                         list_del_init(&reloc_root->root_list);
2364                 }
2365
2366                 /*
2367                  * we keep the old last snapshod transid in rtranid when we
2368                  * created the relocation tree.
2369                  */
2370                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2371                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2372                 objectid = reloc_root->root_key.offset;
2373
2374                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2375                 if (ret < 0) {
2376                         if (list_empty(&reloc_root->root_list))
2377                                 list_add_tail(&reloc_root->root_list,
2378                                               &reloc_roots);
2379                         goto out;
2380                 } else if (!ret) {
2381                         /*
2382                          * recover the last snapshot tranid to avoid
2383                          * the space balance break NOCOW.
2384                          */
2385                         root = read_fs_root(rc->extent_root->fs_info,
2386                                             objectid);
2387                         if (IS_ERR(root))
2388                                 continue;
2389
2390                         trans = btrfs_join_transaction(root);
2391                         BUG_ON(IS_ERR(trans));
2392
2393                         /* Check if the fs/file tree was snapshoted or not. */
2394                         if (btrfs_root_last_snapshot(&root->root_item) ==
2395                             otransid - 1)
2396                                 btrfs_set_root_last_snapshot(&root->root_item,
2397                                                              last_snap);
2398
2399                         btrfs_end_transaction(trans, root);
2400                 }
2401         }
2402
2403         if (found) {
2404                 found = 0;
2405                 goto again;
2406         }
2407 out:
2408         if (ret) {
2409                 btrfs_std_error(root->fs_info, ret);
2410                 if (!list_empty(&reloc_roots))
2411                         free_reloc_roots(&reloc_roots);
2412
2413                 /* new reloc root may be added */
2414                 mutex_lock(&root->fs_info->reloc_mutex);
2415                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2416                 mutex_unlock(&root->fs_info->reloc_mutex);
2417                 if (!list_empty(&reloc_roots))
2418                         free_reloc_roots(&reloc_roots);
2419         }
2420
2421         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2422         return ret;
2423 }
2424
2425 static void free_block_list(struct rb_root *blocks)
2426 {
2427         struct tree_block *block;
2428         struct rb_node *rb_node;
2429         while ((rb_node = rb_first(blocks))) {
2430                 block = rb_entry(rb_node, struct tree_block, rb_node);
2431                 rb_erase(rb_node, blocks);
2432                 kfree(block);
2433         }
2434 }
2435
2436 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2437                                       struct btrfs_root *reloc_root)
2438 {
2439         struct btrfs_root *root;
2440
2441         if (reloc_root->last_trans == trans->transid)
2442                 return 0;
2443
2444         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2445         BUG_ON(IS_ERR(root));
2446         BUG_ON(root->reloc_root != reloc_root);
2447
2448         return btrfs_record_root_in_trans(trans, root);
2449 }
2450
2451 static noinline_for_stack
2452 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2453                                      struct reloc_control *rc,
2454                                      struct backref_node *node,
2455                                      struct backref_edge *edges[], int *nr)
2456 {
2457         struct backref_node *next;
2458         struct btrfs_root *root;
2459         int index = 0;
2460
2461         next = node;
2462         while (1) {
2463                 cond_resched();
2464                 next = walk_up_backref(next, edges, &index);
2465                 root = next->root;
2466                 BUG_ON(!root);
2467                 BUG_ON(!root->ref_cows);
2468
2469                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2470                         record_reloc_root_in_trans(trans, root);
2471                         break;
2472                 }
2473
2474                 btrfs_record_root_in_trans(trans, root);
2475                 root = root->reloc_root;
2476
2477                 if (next->new_bytenr != root->node->start) {
2478                         BUG_ON(next->new_bytenr);
2479                         BUG_ON(!list_empty(&next->list));
2480                         next->new_bytenr = root->node->start;
2481                         next->root = root;
2482                         list_add_tail(&next->list,
2483                                       &rc->backref_cache.changed);
2484                         __mark_block_processed(rc, next);
2485                         break;
2486                 }
2487
2488                 WARN_ON(1);
2489                 root = NULL;
2490                 next = walk_down_backref(edges, &index);
2491                 if (!next || next->level <= node->level)
2492                         break;
2493         }
2494         if (!root)
2495                 return NULL;
2496
2497         *nr = index;
2498         next = node;
2499         /* setup backref node path for btrfs_reloc_cow_block */
2500         while (1) {
2501                 rc->backref_cache.path[next->level] = next;
2502                 if (--index < 0)
2503                         break;
2504                 next = edges[index]->node[UPPER];
2505         }
2506         return root;
2507 }
2508
2509 /*
2510  * select a tree root for relocation. return NULL if the block
2511  * is reference counted. we should use do_relocation() in this
2512  * case. return a tree root pointer if the block isn't reference
2513  * counted. return -ENOENT if the block is root of reloc tree.
2514  */
2515 static noinline_for_stack
2516 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2517                                    struct backref_node *node)
2518 {
2519         struct backref_node *next;
2520         struct btrfs_root *root;
2521         struct btrfs_root *fs_root = NULL;
2522         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2523         int index = 0;
2524
2525         next = node;
2526         while (1) {
2527                 cond_resched();
2528                 next = walk_up_backref(next, edges, &index);
2529                 root = next->root;
2530                 BUG_ON(!root);
2531
2532                 /* no other choice for non-references counted tree */
2533                 if (!root->ref_cows)
2534                         return root;
2535
2536                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2537                         fs_root = root;
2538
2539                 if (next != node)
2540                         return NULL;
2541
2542                 next = walk_down_backref(edges, &index);
2543                 if (!next || next->level <= node->level)
2544                         break;
2545         }
2546
2547         if (!fs_root)
2548                 return ERR_PTR(-ENOENT);
2549         return fs_root;
2550 }
2551
2552 static noinline_for_stack
2553 u64 calcu_metadata_size(struct reloc_control *rc,
2554                         struct backref_node *node, int reserve)
2555 {
2556         struct backref_node *next = node;
2557         struct backref_edge *edge;
2558         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2559         u64 num_bytes = 0;
2560         int index = 0;
2561
2562         BUG_ON(reserve && node->processed);
2563
2564         while (next) {
2565                 cond_resched();
2566                 while (1) {
2567                         if (next->processed && (reserve || next != node))
2568                                 break;
2569
2570                         num_bytes += btrfs_level_size(rc->extent_root,
2571                                                       next->level);
2572
2573                         if (list_empty(&next->upper))
2574                                 break;
2575
2576                         edge = list_entry(next->upper.next,
2577                                           struct backref_edge, list[LOWER]);
2578                         edges[index++] = edge;
2579                         next = edge->node[UPPER];
2580                 }
2581                 next = walk_down_backref(edges, &index);
2582         }
2583         return num_bytes;
2584 }
2585
2586 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2587                                   struct reloc_control *rc,
2588                                   struct backref_node *node)
2589 {
2590         struct btrfs_root *root = rc->extent_root;
2591         u64 num_bytes;
2592         int ret;
2593
2594         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2595
2596         trans->block_rsv = rc->block_rsv;
2597         ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2598                                   BTRFS_RESERVE_FLUSH_ALL);
2599         if (ret) {
2600                 if (ret == -EAGAIN)
2601                         rc->commit_transaction = 1;
2602                 return ret;
2603         }
2604
2605         return 0;
2606 }
2607
2608 static void release_metadata_space(struct reloc_control *rc,
2609                                    struct backref_node *node)
2610 {
2611         u64 num_bytes = calcu_metadata_size(rc, node, 0) * 2;
2612         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, num_bytes);
2613 }
2614
2615 /*
2616  * relocate a block tree, and then update pointers in upper level
2617  * blocks that reference the block to point to the new location.
2618  *
2619  * if called by link_to_upper, the block has already been relocated.
2620  * in that case this function just updates pointers.
2621  */
2622 static int do_relocation(struct btrfs_trans_handle *trans,
2623                          struct reloc_control *rc,
2624                          struct backref_node *node,
2625                          struct btrfs_key *key,
2626                          struct btrfs_path *path, int lowest)
2627 {
2628         struct backref_node *upper;
2629         struct backref_edge *edge;
2630         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2631         struct btrfs_root *root;
2632         struct extent_buffer *eb;
2633         u32 blocksize;
2634         u64 bytenr;
2635         u64 generation;
2636         int nr;
2637         int slot;
2638         int ret;
2639         int err = 0;
2640
2641         BUG_ON(lowest && node->eb);
2642
2643         path->lowest_level = node->level + 1;
2644         rc->backref_cache.path[node->level] = node;
2645         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2646                 cond_resched();
2647
2648                 upper = edge->node[UPPER];
2649                 root = select_reloc_root(trans, rc, upper, edges, &nr);
2650                 BUG_ON(!root);
2651
2652                 if (upper->eb && !upper->locked) {
2653                         if (!lowest) {
2654                                 ret = btrfs_bin_search(upper->eb, key,
2655                                                        upper->level, &slot);
2656                                 BUG_ON(ret);
2657                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2658                                 if (node->eb->start == bytenr)
2659                                         goto next;
2660                         }
2661                         drop_node_buffer(upper);
2662                 }
2663
2664                 if (!upper->eb) {
2665                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2666                         if (ret < 0) {
2667                                 err = ret;
2668                                 break;
2669                         }
2670                         BUG_ON(ret > 0);
2671
2672                         if (!upper->eb) {
2673                                 upper->eb = path->nodes[upper->level];
2674                                 path->nodes[upper->level] = NULL;
2675                         } else {
2676                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2677                         }
2678
2679                         upper->locked = 1;
2680                         path->locks[upper->level] = 0;
2681
2682                         slot = path->slots[upper->level];
2683                         btrfs_release_path(path);
2684                 } else {
2685                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2686                                                &slot);
2687                         BUG_ON(ret);
2688                 }
2689
2690                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2691                 if (lowest) {
2692                         BUG_ON(bytenr != node->bytenr);
2693                 } else {
2694                         if (node->eb->start == bytenr)
2695                                 goto next;
2696                 }
2697
2698                 blocksize = btrfs_level_size(root, node->level);
2699                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2700                 eb = read_tree_block(root, bytenr, blocksize, generation);
2701                 if (!eb || !extent_buffer_uptodate(eb)) {
2702                         free_extent_buffer(eb);
2703                         err = -EIO;
2704                         goto next;
2705                 }
2706                 btrfs_tree_lock(eb);
2707                 btrfs_set_lock_blocking(eb);
2708
2709                 if (!node->eb) {
2710                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2711                                               slot, &eb);
2712                         btrfs_tree_unlock(eb);
2713                         free_extent_buffer(eb);
2714                         if (ret < 0) {
2715                                 err = ret;
2716                                 goto next;
2717                         }
2718                         BUG_ON(node->eb != eb);
2719                 } else {
2720                         btrfs_set_node_blockptr(upper->eb, slot,
2721                                                 node->eb->start);
2722                         btrfs_set_node_ptr_generation(upper->eb, slot,
2723                                                       trans->transid);
2724                         btrfs_mark_buffer_dirty(upper->eb);
2725
2726                         ret = btrfs_inc_extent_ref(trans, root,
2727                                                 node->eb->start, blocksize,
2728                                                 upper->eb->start,
2729                                                 btrfs_header_owner(upper->eb),
2730                                                 node->level, 0, 1);
2731                         BUG_ON(ret);
2732
2733                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2734                         BUG_ON(ret);
2735                 }
2736 next:
2737                 if (!upper->pending)
2738                         drop_node_buffer(upper);
2739                 else
2740                         unlock_node_buffer(upper);
2741                 if (err)
2742                         break;
2743         }
2744
2745         if (!err && node->pending) {
2746                 drop_node_buffer(node);
2747                 list_move_tail(&node->list, &rc->backref_cache.changed);
2748                 node->pending = 0;
2749         }
2750
2751         path->lowest_level = 0;
2752         BUG_ON(err == -ENOSPC);
2753         return err;
2754 }
2755
2756 static int link_to_upper(struct btrfs_trans_handle *trans,
2757                          struct reloc_control *rc,
2758                          struct backref_node *node,
2759                          struct btrfs_path *path)
2760 {
2761         struct btrfs_key key;
2762
2763         btrfs_node_key_to_cpu(node->eb, &key, 0);
2764         return do_relocation(trans, rc, node, &key, path, 0);
2765 }
2766
2767 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2768                                 struct reloc_control *rc,
2769                                 struct btrfs_path *path, int err)
2770 {
2771         LIST_HEAD(list);
2772         struct backref_cache *cache = &rc->backref_cache;
2773         struct backref_node *node;
2774         int level;
2775         int ret;
2776
2777         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2778                 while (!list_empty(&cache->pending[level])) {
2779                         node = list_entry(cache->pending[level].next,
2780                                           struct backref_node, list);
2781                         list_move_tail(&node->list, &list);
2782                         BUG_ON(!node->pending);
2783
2784                         if (!err) {
2785                                 ret = link_to_upper(trans, rc, node, path);
2786                                 if (ret < 0)
2787                                         err = ret;
2788                         }
2789                 }
2790                 list_splice_init(&list, &cache->pending[level]);
2791         }
2792         return err;
2793 }
2794
2795 static void mark_block_processed(struct reloc_control *rc,
2796                                  u64 bytenr, u32 blocksize)
2797 {
2798         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2799                         EXTENT_DIRTY, GFP_NOFS);
2800 }
2801
2802 static void __mark_block_processed(struct reloc_control *rc,
2803                                    struct backref_node *node)
2804 {
2805         u32 blocksize;
2806         if (node->level == 0 ||
2807             in_block_group(node->bytenr, rc->block_group)) {
2808                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2809                 mark_block_processed(rc, node->bytenr, blocksize);
2810         }
2811         node->processed = 1;
2812 }
2813
2814 /*
2815  * mark a block and all blocks directly/indirectly reference the block
2816  * as processed.
2817  */
2818 static void update_processed_blocks(struct reloc_control *rc,
2819                                     struct backref_node *node)
2820 {
2821         struct backref_node *next = node;
2822         struct backref_edge *edge;
2823         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2824         int index = 0;
2825
2826         while (next) {
2827                 cond_resched();
2828                 while (1) {
2829                         if (next->processed)
2830                                 break;
2831
2832                         __mark_block_processed(rc, next);
2833
2834                         if (list_empty(&next->upper))
2835                                 break;
2836
2837                         edge = list_entry(next->upper.next,
2838                                           struct backref_edge, list[LOWER]);
2839                         edges[index++] = edge;
2840                         next = edge->node[UPPER];
2841                 }
2842                 next = walk_down_backref(edges, &index);
2843         }
2844 }
2845
2846 static int tree_block_processed(u64 bytenr, u32 blocksize,
2847                                 struct reloc_control *rc)
2848 {
2849         if (test_range_bit(&rc->processed_blocks, bytenr,
2850                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2851                 return 1;
2852         return 0;
2853 }
2854
2855 static int get_tree_block_key(struct reloc_control *rc,
2856                               struct tree_block *block)
2857 {
2858         struct extent_buffer *eb;
2859
2860         BUG_ON(block->key_ready);
2861         eb = read_tree_block(rc->extent_root, block->bytenr,
2862                              block->key.objectid, block->key.offset);
2863         if (!eb || !extent_buffer_uptodate(eb)) {
2864                 free_extent_buffer(eb);
2865                 return -EIO;
2866         }
2867         WARN_ON(btrfs_header_level(eb) != block->level);
2868         if (block->level == 0)
2869                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2870         else
2871                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2872         free_extent_buffer(eb);
2873         block->key_ready = 1;
2874         return 0;
2875 }
2876
2877 static int reada_tree_block(struct reloc_control *rc,
2878                             struct tree_block *block)
2879 {
2880         BUG_ON(block->key_ready);
2881         if (block->key.type == BTRFS_METADATA_ITEM_KEY)
2882                 readahead_tree_block(rc->extent_root, block->bytenr,
2883                                      block->key.objectid,
2884                                      rc->extent_root->leafsize);
2885         else
2886                 readahead_tree_block(rc->extent_root, block->bytenr,
2887                                      block->key.objectid, block->key.offset);
2888         return 0;
2889 }
2890
2891 /*
2892  * helper function to relocate a tree block
2893  */
2894 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2895                                 struct reloc_control *rc,
2896                                 struct backref_node *node,
2897                                 struct btrfs_key *key,
2898                                 struct btrfs_path *path)
2899 {
2900         struct btrfs_root *root;
2901         int release = 0;
2902         int ret = 0;
2903
2904         if (!node)
2905                 return 0;
2906
2907         BUG_ON(node->processed);
2908         root = select_one_root(trans, node);
2909         if (root == ERR_PTR(-ENOENT)) {
2910                 update_processed_blocks(rc, node);
2911                 goto out;
2912         }
2913
2914         if (!root || root->ref_cows) {
2915                 ret = reserve_metadata_space(trans, rc, node);
2916                 if (ret)
2917                         goto out;
2918                 release = 1;
2919         }
2920
2921         if (root) {
2922                 if (root->ref_cows) {
2923                         BUG_ON(node->new_bytenr);
2924                         BUG_ON(!list_empty(&node->list));
2925                         btrfs_record_root_in_trans(trans, root);
2926                         root = root->reloc_root;
2927                         node->new_bytenr = root->node->start;
2928                         node->root = root;
2929                         list_add_tail(&node->list, &rc->backref_cache.changed);
2930                 } else {
2931                         path->lowest_level = node->level;
2932                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2933                         btrfs_release_path(path);
2934                         if (ret > 0)
2935                                 ret = 0;
2936                 }
2937                 if (!ret)
2938                         update_processed_blocks(rc, node);
2939         } else {
2940                 ret = do_relocation(trans, rc, node, key, path, 1);
2941         }
2942 out:
2943         if (ret || node->level == 0 || node->cowonly) {
2944                 if (release)
2945                         release_metadata_space(rc, node);
2946                 remove_backref_node(&rc->backref_cache, node);
2947         }
2948         return ret;
2949 }
2950
2951 /*
2952  * relocate a list of blocks
2953  */
2954 static noinline_for_stack
2955 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2956                          struct reloc_control *rc, struct rb_root *blocks)
2957 {
2958         struct backref_node *node;
2959         struct btrfs_path *path;
2960         struct tree_block *block;
2961         struct rb_node *rb_node;
2962         int ret;
2963         int err = 0;
2964
2965         path = btrfs_alloc_path();
2966         if (!path) {
2967                 err = -ENOMEM;
2968                 goto out_free_blocks;
2969         }
2970
2971         rb_node = rb_first(blocks);
2972         while (rb_node) {
2973                 block = rb_entry(rb_node, struct tree_block, rb_node);
2974                 if (!block->key_ready)
2975                         reada_tree_block(rc, block);
2976                 rb_node = rb_next(rb_node);
2977         }
2978
2979         rb_node = rb_first(blocks);
2980         while (rb_node) {
2981                 block = rb_entry(rb_node, struct tree_block, rb_node);
2982                 if (!block->key_ready) {
2983                         err = get_tree_block_key(rc, block);
2984                         if (err)
2985                                 goto out_free_path;
2986                 }
2987                 rb_node = rb_next(rb_node);
2988         }
2989
2990         rb_node = rb_first(blocks);
2991         while (rb_node) {
2992                 block = rb_entry(rb_node, struct tree_block, rb_node);
2993
2994                 node = build_backref_tree(rc, &block->key,
2995                                           block->level, block->bytenr);
2996                 if (IS_ERR(node)) {
2997                         err = PTR_ERR(node);
2998                         goto out;
2999                 }
3000
3001                 ret = relocate_tree_block(trans, rc, node, &block->key,
3002                                           path);
3003                 if (ret < 0) {
3004                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
3005                                 err = ret;
3006                         goto out;
3007                 }
3008                 rb_node = rb_next(rb_node);
3009         }
3010 out:
3011         err = finish_pending_nodes(trans, rc, path, err);
3012
3013 out_free_path:
3014         btrfs_free_path(path);
3015 out_free_blocks:
3016         free_block_list(blocks);
3017         return err;
3018 }
3019
3020 static noinline_for_stack
3021 int prealloc_file_extent_cluster(struct inode *inode,
3022                                  struct file_extent_cluster *cluster)
3023 {
3024         u64 alloc_hint = 0;
3025         u64 start;
3026         u64 end;
3027         u64 offset = BTRFS_I(inode)->index_cnt;
3028         u64 num_bytes;
3029         int nr = 0;
3030         int ret = 0;
3031
3032         BUG_ON(cluster->start != cluster->boundary[0]);
3033         mutex_lock(&inode->i_mutex);
3034
3035         ret = btrfs_check_data_free_space(inode, cluster->end +
3036                                           1 - cluster->start);
3037         if (ret)
3038                 goto out;
3039
3040         while (nr < cluster->nr) {
3041                 start = cluster->boundary[nr] - offset;
3042                 if (nr + 1 < cluster->nr)
3043                         end = cluster->boundary[nr + 1] - 1 - offset;
3044                 else
3045                         end = cluster->end - offset;
3046
3047                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3048                 num_bytes = end + 1 - start;
3049                 ret = btrfs_prealloc_file_range(inode, 0, start,
3050                                                 num_bytes, num_bytes,
3051                                                 end + 1, &alloc_hint);
3052                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3053                 if (ret)
3054                         break;
3055                 nr++;
3056         }
3057         btrfs_free_reserved_data_space(inode, cluster->end +
3058                                        1 - cluster->start);
3059 out:
3060         mutex_unlock(&inode->i_mutex);
3061         return ret;
3062 }
3063
3064 static noinline_for_stack
3065 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3066                          u64 block_start)
3067 {
3068         struct btrfs_root *root = BTRFS_I(inode)->root;
3069         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3070         struct extent_map *em;
3071         int ret = 0;
3072
3073         em = alloc_extent_map();
3074         if (!em)
3075                 return -ENOMEM;
3076
3077         em->start = start;
3078         em->len = end + 1 - start;
3079         em->block_len = em->len;
3080         em->block_start = block_start;
3081         em->bdev = root->fs_info->fs_devices->latest_bdev;
3082         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3083
3084         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3085         while (1) {
3086                 write_lock(&em_tree->lock);
3087                 ret = add_extent_mapping(em_tree, em, 0);
3088                 write_unlock(&em_tree->lock);
3089                 if (ret != -EEXIST) {
3090                         free_extent_map(em);
3091                         break;
3092                 }
3093                 btrfs_drop_extent_cache(inode, start, end, 0);
3094         }
3095         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3096         return ret;
3097 }
3098
3099 static int relocate_file_extent_cluster(struct inode *inode,
3100                                         struct file_extent_cluster *cluster)
3101 {
3102         u64 page_start;
3103         u64 page_end;
3104         u64 offset = BTRFS_I(inode)->index_cnt;
3105         unsigned long index;
3106         unsigned long last_index;
3107         struct page *page;
3108         struct file_ra_state *ra;
3109         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3110         int nr = 0;
3111         int ret = 0;
3112
3113         if (!cluster->nr)
3114                 return 0;
3115
3116         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3117         if (!ra)
3118                 return -ENOMEM;
3119
3120         ret = prealloc_file_extent_cluster(inode, cluster);
3121         if (ret)
3122                 goto out;
3123
3124         file_ra_state_init(ra, inode->i_mapping);
3125
3126         ret = setup_extent_mapping(inode, cluster->start - offset,
3127                                    cluster->end - offset, cluster->start);
3128         if (ret)
3129                 goto out;
3130
3131         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3132         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3133         while (index <= last_index) {
3134                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3135                 if (ret)
3136                         goto out;
3137
3138                 page = find_lock_page(inode->i_mapping, index);
3139                 if (!page) {
3140                         page_cache_sync_readahead(inode->i_mapping,
3141                                                   ra, NULL, index,
3142                                                   last_index + 1 - index);
3143                         page = find_or_create_page(inode->i_mapping, index,
3144                                                    mask);
3145                         if (!page) {
3146                                 btrfs_delalloc_release_metadata(inode,
3147                                                         PAGE_CACHE_SIZE);
3148                                 ret = -ENOMEM;
3149                                 goto out;
3150                         }
3151                 }
3152
3153                 if (PageReadahead(page)) {
3154                         page_cache_async_readahead(inode->i_mapping,
3155                                                    ra, NULL, page, index,
3156                                                    last_index + 1 - index);
3157                 }
3158
3159                 if (!PageUptodate(page)) {
3160                         btrfs_readpage(NULL, page);
3161                         lock_page(page);
3162                         if (!PageUptodate(page)) {
3163                                 unlock_page(page);
3164                                 page_cache_release(page);
3165                                 btrfs_delalloc_release_metadata(inode,
3166                                                         PAGE_CACHE_SIZE);
3167                                 ret = -EIO;
3168                                 goto out;
3169                         }
3170                 }
3171
3172                 page_start = page_offset(page);
3173                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3174
3175                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3176
3177                 set_page_extent_mapped(page);
3178
3179                 if (nr < cluster->nr &&
3180                     page_start + offset == cluster->boundary[nr]) {
3181                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3182                                         page_start, page_end,
3183                                         EXTENT_BOUNDARY, GFP_NOFS);
3184                         nr++;
3185                 }
3186
3187                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3188                 set_page_dirty(page);
3189
3190                 unlock_extent(&BTRFS_I(inode)->io_tree,
3191                               page_start, page_end);
3192                 unlock_page(page);
3193                 page_cache_release(page);
3194
3195                 index++;
3196                 balance_dirty_pages_ratelimited(inode->i_mapping);
3197                 btrfs_throttle(BTRFS_I(inode)->root);
3198         }
3199         WARN_ON(nr != cluster->nr);
3200 out:
3201         kfree(ra);
3202         return ret;
3203 }
3204
3205 static noinline_for_stack
3206 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3207                          struct file_extent_cluster *cluster)
3208 {
3209         int ret;
3210
3211         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3212                 ret = relocate_file_extent_cluster(inode, cluster);
3213                 if (ret)
3214                         return ret;
3215                 cluster->nr = 0;
3216         }
3217
3218         if (!cluster->nr)
3219                 cluster->start = extent_key->objectid;
3220         else
3221                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3222         cluster->end = extent_key->objectid + extent_key->offset - 1;
3223         cluster->boundary[cluster->nr] = extent_key->objectid;
3224         cluster->nr++;
3225
3226         if (cluster->nr >= MAX_EXTENTS) {
3227                 ret = relocate_file_extent_cluster(inode, cluster);
3228                 if (ret)
3229                         return ret;
3230                 cluster->nr = 0;
3231         }
3232         return 0;
3233 }
3234
3235 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3236 static int get_ref_objectid_v0(struct reloc_control *rc,
3237                                struct btrfs_path *path,
3238                                struct btrfs_key *extent_key,
3239                                u64 *ref_objectid, int *path_change)
3240 {
3241         struct btrfs_key key;
3242         struct extent_buffer *leaf;
3243         struct btrfs_extent_ref_v0 *ref0;
3244         int ret;
3245         int slot;
3246
3247         leaf = path->nodes[0];
3248         slot = path->slots[0];
3249         while (1) {
3250                 if (slot >= btrfs_header_nritems(leaf)) {
3251                         ret = btrfs_next_leaf(rc->extent_root, path);
3252                         if (ret < 0)
3253                                 return ret;
3254                         BUG_ON(ret > 0);
3255                         leaf = path->nodes[0];
3256                         slot = path->slots[0];
3257                         if (path_change)
3258                                 *path_change = 1;
3259                 }
3260                 btrfs_item_key_to_cpu(leaf, &key, slot);
3261                 if (key.objectid != extent_key->objectid)
3262                         return -ENOENT;
3263
3264                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3265                         slot++;
3266                         continue;
3267                 }
3268                 ref0 = btrfs_item_ptr(leaf, slot,
3269                                 struct btrfs_extent_ref_v0);
3270                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3271                 break;
3272         }
3273         return 0;
3274 }
3275 #endif
3276
3277 /*
3278  * helper to add a tree block to the list.
3279  * the major work is getting the generation and level of the block
3280  */
3281 static int add_tree_block(struct reloc_control *rc,
3282                           struct btrfs_key *extent_key,
3283                           struct btrfs_path *path,
3284                           struct rb_root *blocks)
3285 {
3286         struct extent_buffer *eb;
3287         struct btrfs_extent_item *ei;
3288         struct btrfs_tree_block_info *bi;
3289         struct tree_block *block;
3290         struct rb_node *rb_node;
3291         u32 item_size;
3292         int level = -1;
3293         u64 generation;
3294
3295         eb =  path->nodes[0];
3296         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3297
3298         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3299             item_size >= sizeof(*ei) + sizeof(*bi)) {
3300                 ei = btrfs_item_ptr(eb, path->slots[0],
3301                                 struct btrfs_extent_item);
3302                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3303                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3304                         level = btrfs_tree_block_level(eb, bi);
3305                 } else {
3306                         level = (int)extent_key->offset;
3307                 }
3308                 generation = btrfs_extent_generation(eb, ei);
3309         } else {
3310 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3311                 u64 ref_owner;
3312                 int ret;
3313
3314                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3315                 ret = get_ref_objectid_v0(rc, path, extent_key,
3316                                           &ref_owner, NULL);
3317                 if (ret < 0)
3318                         return ret;
3319                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3320                 level = (int)ref_owner;
3321                 /* FIXME: get real generation */
3322                 generation = 0;
3323 #else
3324                 BUG();
3325 #endif
3326         }
3327
3328         btrfs_release_path(path);
3329
3330         BUG_ON(level == -1);
3331
3332         block = kmalloc(sizeof(*block), GFP_NOFS);
3333         if (!block)
3334                 return -ENOMEM;
3335
3336         block->bytenr = extent_key->objectid;
3337         block->key.objectid = rc->extent_root->leafsize;
3338         block->key.offset = generation;
3339         block->level = level;
3340         block->key_ready = 0;
3341
3342         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3343         if (rb_node)
3344                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3345
3346         return 0;
3347 }
3348
3349 /*
3350  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3351  */
3352 static int __add_tree_block(struct reloc_control *rc,
3353                             u64 bytenr, u32 blocksize,
3354                             struct rb_root *blocks)
3355 {
3356         struct btrfs_path *path;
3357         struct btrfs_key key;
3358         int ret;
3359         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3360                                         SKINNY_METADATA);
3361
3362         if (tree_block_processed(bytenr, blocksize, rc))
3363                 return 0;
3364
3365         if (tree_search(blocks, bytenr))
3366                 return 0;
3367
3368         path = btrfs_alloc_path();
3369         if (!path)
3370                 return -ENOMEM;
3371 again:
3372         key.objectid = bytenr;
3373         if (skinny) {
3374                 key.type = BTRFS_METADATA_ITEM_KEY;
3375                 key.offset = (u64)-1;
3376         } else {
3377                 key.type = BTRFS_EXTENT_ITEM_KEY;
3378                 key.offset = blocksize;
3379         }
3380
3381         path->search_commit_root = 1;
3382         path->skip_locking = 1;
3383         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3384         if (ret < 0)
3385                 goto out;
3386
3387         if (ret > 0 && skinny) {
3388                 if (path->slots[0]) {
3389                         path->slots[0]--;
3390                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3391                                               path->slots[0]);
3392                         if (key.objectid == bytenr &&
3393                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3394                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3395                               key.offset == blocksize)))
3396                                 ret = 0;
3397                 }
3398
3399                 if (ret) {
3400                         skinny = false;
3401                         btrfs_release_path(path);
3402                         goto again;
3403                 }
3404         }
3405         BUG_ON(ret);
3406
3407         ret = add_tree_block(rc, &key, path, blocks);
3408 out:
3409         btrfs_free_path(path);
3410         return ret;
3411 }
3412
3413 /*
3414  * helper to check if the block use full backrefs for pointers in it
3415  */
3416 static int block_use_full_backref(struct reloc_control *rc,
3417                                   struct extent_buffer *eb)
3418 {
3419         u64 flags;
3420         int ret;
3421
3422         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3423             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3424                 return 1;
3425
3426         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3427                                        eb->start, btrfs_header_level(eb), 1,
3428                                        NULL, &flags);
3429         BUG_ON(ret);
3430
3431         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3432                 ret = 1;
3433         else
3434                 ret = 0;
3435         return ret;
3436 }
3437
3438 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3439                                     struct inode *inode, u64 ino)
3440 {
3441         struct btrfs_key key;
3442         struct btrfs_root *root = fs_info->tree_root;
3443         struct btrfs_trans_handle *trans;
3444         int ret = 0;
3445
3446         if (inode)
3447                 goto truncate;
3448
3449         key.objectid = ino;
3450         key.type = BTRFS_INODE_ITEM_KEY;
3451         key.offset = 0;
3452
3453         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3454         if (IS_ERR(inode) || is_bad_inode(inode)) {
3455                 if (!IS_ERR(inode))
3456                         iput(inode);
3457                 return -ENOENT;
3458         }
3459
3460 truncate:
3461         ret = btrfs_check_trunc_cache_free_space(root,
3462                                                  &fs_info->global_block_rsv);
3463         if (ret)
3464                 goto out;
3465
3466         trans = btrfs_join_transaction(root);
3467         if (IS_ERR(trans)) {
3468                 ret = PTR_ERR(trans);
3469                 goto out;
3470         }
3471
3472         ret = btrfs_truncate_free_space_cache(root, trans, inode);
3473
3474         btrfs_end_transaction(trans, root);
3475         btrfs_btree_balance_dirty(root);
3476 out:
3477         iput(inode);
3478         return ret;
3479 }
3480
3481 /*
3482  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3483  * this function scans fs tree to find blocks reference the data extent
3484  */
3485 static int find_data_references(struct reloc_control *rc,
3486                                 struct btrfs_key *extent_key,
3487                                 struct extent_buffer *leaf,
3488                                 struct btrfs_extent_data_ref *ref,
3489                                 struct rb_root *blocks)
3490 {
3491         struct btrfs_path *path;
3492         struct tree_block *block;
3493         struct btrfs_root *root;
3494         struct btrfs_file_extent_item *fi;
3495         struct rb_node *rb_node;
3496         struct btrfs_key key;
3497         u64 ref_root;
3498         u64 ref_objectid;
3499         u64 ref_offset;
3500         u32 ref_count;
3501         u32 nritems;
3502         int err = 0;
3503         int added = 0;
3504         int counted;
3505         int ret;
3506
3507         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3508         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3509         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3510         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3511
3512         /*
3513          * This is an extent belonging to the free space cache, lets just delete
3514          * it and redo the search.
3515          */
3516         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3517                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3518                                                NULL, ref_objectid);
3519                 if (ret != -ENOENT)
3520                         return ret;
3521                 ret = 0;
3522         }
3523
3524         path = btrfs_alloc_path();
3525         if (!path)
3526                 return -ENOMEM;
3527         path->reada = 1;
3528
3529         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3530         if (IS_ERR(root)) {
3531                 err = PTR_ERR(root);
3532                 goto out;
3533         }
3534
3535         key.objectid = ref_objectid;
3536         key.type = BTRFS_EXTENT_DATA_KEY;
3537         if (ref_offset > ((u64)-1 << 32))
3538                 key.offset = 0;
3539         else
3540                 key.offset = ref_offset;
3541
3542         path->search_commit_root = 1;
3543         path->skip_locking = 1;
3544         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3545         if (ret < 0) {
3546                 err = ret;
3547                 goto out;
3548         }
3549
3550         leaf = path->nodes[0];
3551         nritems = btrfs_header_nritems(leaf);
3552         /*
3553          * the references in tree blocks that use full backrefs
3554          * are not counted in
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         while (ref_count > 0) {
3569                 while (path->slots[0] >= nritems) {
3570                         ret = btrfs_next_leaf(root, path);
3571                         if (ret < 0) {
3572                                 err = ret;
3573                                 goto out;
3574                         }
3575                         if (WARN_ON(ret > 0))
3576                                 goto out;
3577
3578                         leaf = path->nodes[0];
3579                         nritems = btrfs_header_nritems(leaf);
3580                         added = 0;
3581
3582                         if (block_use_full_backref(rc, leaf))
3583                                 counted = 0;
3584                         else
3585                                 counted = 1;
3586                         rb_node = tree_search(blocks, leaf->start);
3587                         if (rb_node) {
3588                                 if (counted)
3589                                         added = 1;
3590                                 else
3591                                         path->slots[0] = nritems;
3592                         }
3593                 }
3594
3595                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3596                 if (WARN_ON(key.objectid != ref_objectid ||
3597                     key.type != BTRFS_EXTENT_DATA_KEY))
3598                         break;
3599
3600                 fi = btrfs_item_ptr(leaf, path->slots[0],
3601                                     struct btrfs_file_extent_item);
3602
3603                 if (btrfs_file_extent_type(leaf, fi) ==
3604                     BTRFS_FILE_EXTENT_INLINE)
3605                         goto next;
3606
3607                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3608                     extent_key->objectid)
3609                         goto next;
3610
3611                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3612                 if (key.offset != ref_offset)
3613                         goto next;
3614
3615                 if (counted)
3616                         ref_count--;
3617                 if (added)
3618                         goto next;
3619
3620                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3621                         block = kmalloc(sizeof(*block), GFP_NOFS);
3622                         if (!block) {
3623                                 err = -ENOMEM;
3624                                 break;
3625                         }
3626                         block->bytenr = leaf->start;
3627                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3628                         block->level = 0;
3629                         block->key_ready = 1;
3630                         rb_node = tree_insert(blocks, block->bytenr,
3631                                               &block->rb_node);
3632                         if (rb_node)
3633                                 backref_tree_panic(rb_node, -EEXIST,
3634                                                    block->bytenr);
3635                 }
3636                 if (counted)
3637                         added = 1;
3638                 else
3639                         path->slots[0] = nritems;
3640 next:
3641                 path->slots[0]++;
3642
3643         }
3644 out:
3645         btrfs_free_path(path);
3646         return err;
3647 }
3648
3649 /*
3650  * helper to find all tree blocks that reference a given data extent
3651  */
3652 static noinline_for_stack
3653 int add_data_references(struct reloc_control *rc,
3654                         struct btrfs_key *extent_key,
3655                         struct btrfs_path *path,
3656                         struct rb_root *blocks)
3657 {
3658         struct btrfs_key key;
3659         struct extent_buffer *eb;
3660         struct btrfs_extent_data_ref *dref;
3661         struct btrfs_extent_inline_ref *iref;
3662         unsigned long ptr;
3663         unsigned long end;
3664         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3665         int ret = 0;
3666         int err = 0;
3667
3668         eb = path->nodes[0];
3669         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3670         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3671 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3672         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3673                 ptr = end;
3674         else
3675 #endif
3676                 ptr += sizeof(struct btrfs_extent_item);
3677
3678         while (ptr < end) {
3679                 iref = (struct btrfs_extent_inline_ref *)ptr;
3680                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3681                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3682                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3683                         ret = __add_tree_block(rc, key.offset, blocksize,
3684                                                blocks);
3685                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3686                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3687                         ret = find_data_references(rc, extent_key,
3688                                                    eb, dref, blocks);
3689                 } else {
3690                         BUG();
3691                 }
3692                 if (ret) {
3693                         err = ret;
3694                         goto out;
3695                 }
3696                 ptr += btrfs_extent_inline_ref_size(key.type);
3697         }
3698         WARN_ON(ptr > end);
3699
3700         while (1) {
3701                 cond_resched();
3702                 eb = path->nodes[0];
3703                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3704                         ret = btrfs_next_leaf(rc->extent_root, path);
3705                         if (ret < 0) {
3706                                 err = ret;
3707                                 break;
3708                         }
3709                         if (ret > 0)
3710                                 break;
3711                         eb = path->nodes[0];
3712                 }
3713
3714                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3715                 if (key.objectid != extent_key->objectid)
3716                         break;
3717
3718 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3719                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3720                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3721 #else
3722                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3723                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3724 #endif
3725                         ret = __add_tree_block(rc, key.offset, blocksize,
3726                                                blocks);
3727                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3728                         dref = btrfs_item_ptr(eb, path->slots[0],
3729                                               struct btrfs_extent_data_ref);
3730                         ret = find_data_references(rc, extent_key,
3731                                                    eb, dref, blocks);
3732                 } else {
3733                         ret = 0;
3734                 }
3735                 if (ret) {
3736                         err = ret;
3737                         break;
3738                 }
3739                 path->slots[0]++;
3740         }
3741 out:
3742         btrfs_release_path(path);
3743         if (err)
3744                 free_block_list(blocks);
3745         return err;
3746 }
3747
3748 /*
3749  * helper to find next unprocessed extent
3750  */
3751 static noinline_for_stack
3752 int find_next_extent(struct btrfs_trans_handle *trans,
3753                      struct reloc_control *rc, struct btrfs_path *path,
3754                      struct btrfs_key *extent_key)
3755 {
3756         struct btrfs_key key;
3757         struct extent_buffer *leaf;
3758         u64 start, end, last;
3759         int ret;
3760
3761         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3762         while (1) {
3763                 cond_resched();
3764                 if (rc->search_start >= last) {
3765                         ret = 1;
3766                         break;
3767                 }
3768
3769                 key.objectid = rc->search_start;
3770                 key.type = BTRFS_EXTENT_ITEM_KEY;
3771                 key.offset = 0;
3772
3773                 path->search_commit_root = 1;
3774                 path->skip_locking = 1;
3775                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3776                                         0, 0);
3777                 if (ret < 0)
3778                         break;
3779 next:
3780                 leaf = path->nodes[0];
3781                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3782                         ret = btrfs_next_leaf(rc->extent_root, path);
3783                         if (ret != 0)
3784                                 break;
3785                         leaf = path->nodes[0];
3786                 }
3787
3788                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3789                 if (key.objectid >= last) {
3790                         ret = 1;
3791                         break;
3792                 }
3793
3794                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3795                     key.type != BTRFS_METADATA_ITEM_KEY) {
3796                         path->slots[0]++;
3797                         goto next;
3798                 }
3799
3800                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3801                     key.objectid + key.offset <= rc->search_start) {
3802                         path->slots[0]++;
3803                         goto next;
3804                 }
3805
3806                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3807                     key.objectid + rc->extent_root->leafsize <=
3808                     rc->search_start) {
3809                         path->slots[0]++;
3810                         goto next;
3811                 }
3812
3813                 ret = find_first_extent_bit(&rc->processed_blocks,
3814                                             key.objectid, &start, &end,
3815                                             EXTENT_DIRTY, NULL);
3816
3817                 if (ret == 0 && start <= key.objectid) {
3818                         btrfs_release_path(path);
3819                         rc->search_start = end + 1;
3820                 } else {
3821                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3822                                 rc->search_start = key.objectid + key.offset;
3823                         else
3824                                 rc->search_start = key.objectid +
3825                                         rc->extent_root->leafsize;
3826                         memcpy(extent_key, &key, sizeof(key));
3827                         return 0;
3828                 }
3829         }
3830         btrfs_release_path(path);
3831         return ret;
3832 }
3833
3834 static void set_reloc_control(struct reloc_control *rc)
3835 {
3836         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3837
3838         mutex_lock(&fs_info->reloc_mutex);
3839         fs_info->reloc_ctl = rc;
3840         mutex_unlock(&fs_info->reloc_mutex);
3841 }
3842
3843 static void unset_reloc_control(struct reloc_control *rc)
3844 {
3845         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3846
3847         mutex_lock(&fs_info->reloc_mutex);
3848         fs_info->reloc_ctl = NULL;
3849         mutex_unlock(&fs_info->reloc_mutex);
3850 }
3851
3852 static int check_extent_flags(u64 flags)
3853 {
3854         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3855             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3856                 return 1;
3857         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3858             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3859                 return 1;
3860         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3861             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3862                 return 1;
3863         return 0;
3864 }
3865
3866 static noinline_for_stack
3867 int prepare_to_relocate(struct reloc_control *rc)
3868 {
3869         struct btrfs_trans_handle *trans;
3870         int ret;
3871
3872         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3873                                               BTRFS_BLOCK_RSV_TEMP);
3874         if (!rc->block_rsv)
3875                 return -ENOMEM;
3876
3877         /*
3878          * reserve some space for creating reloc trees.
3879          * btrfs_init_reloc_root will use them when there
3880          * is no reservation in transaction handle.
3881          */
3882         ret = btrfs_block_rsv_add(rc->extent_root, rc->block_rsv,
3883                                   rc->extent_root->nodesize * 256,
3884                                   BTRFS_RESERVE_FLUSH_ALL);
3885         if (ret)
3886                 return ret;
3887
3888         memset(&rc->cluster, 0, sizeof(rc->cluster));
3889         rc->search_start = rc->block_group->key.objectid;
3890         rc->extents_found = 0;
3891         rc->nodes_relocated = 0;
3892         rc->merging_rsv_size = 0;
3893
3894         rc->create_reloc_tree = 1;
3895         set_reloc_control(rc);
3896
3897         trans = btrfs_join_transaction(rc->extent_root);
3898         if (IS_ERR(trans)) {
3899                 unset_reloc_control(rc);
3900                 /*
3901                  * extent tree is not a ref_cow tree and has no reloc_root to
3902                  * cleanup.  And callers are responsible to free the above
3903                  * block rsv.
3904                  */
3905                 return PTR_ERR(trans);
3906         }
3907         btrfs_commit_transaction(trans, rc->extent_root);
3908         return 0;
3909 }
3910
3911 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3912 {
3913         struct rb_root blocks = RB_ROOT;
3914         struct btrfs_key key;
3915         struct btrfs_trans_handle *trans = NULL;
3916         struct btrfs_path *path;
3917         struct btrfs_extent_item *ei;
3918         u64 flags;
3919         u32 item_size;
3920         int ret;
3921         int err = 0;
3922         int progress = 0;
3923
3924         path = btrfs_alloc_path();
3925         if (!path)
3926                 return -ENOMEM;
3927         path->reada = 1;
3928
3929         ret = prepare_to_relocate(rc);
3930         if (ret) {
3931                 err = ret;
3932                 goto out_free;
3933         }
3934
3935         while (1) {
3936                 progress++;
3937                 trans = btrfs_start_transaction(rc->extent_root, 0);
3938                 if (IS_ERR(trans)) {
3939                         err = PTR_ERR(trans);
3940                         trans = NULL;
3941                         break;
3942                 }
3943 restart:
3944                 if (update_backref_cache(trans, &rc->backref_cache)) {
3945                         btrfs_end_transaction(trans, rc->extent_root);
3946                         continue;
3947                 }
3948
3949                 ret = find_next_extent(trans, rc, path, &key);
3950                 if (ret < 0)
3951                         err = ret;
3952                 if (ret != 0)
3953                         break;
3954
3955                 rc->extents_found++;
3956
3957                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3958                                     struct btrfs_extent_item);
3959                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3960                 if (item_size >= sizeof(*ei)) {
3961                         flags = btrfs_extent_flags(path->nodes[0], ei);
3962                         ret = check_extent_flags(flags);
3963                         BUG_ON(ret);
3964
3965                 } else {
3966 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3967                         u64 ref_owner;
3968                         int path_change = 0;
3969
3970                         BUG_ON(item_size !=
3971                                sizeof(struct btrfs_extent_item_v0));
3972                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3973                                                   &path_change);
3974                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3975                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3976                         else
3977                                 flags = BTRFS_EXTENT_FLAG_DATA;
3978
3979                         if (path_change) {
3980                                 btrfs_release_path(path);
3981
3982                                 path->search_commit_root = 1;
3983                                 path->skip_locking = 1;
3984                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3985                                                         &key, path, 0, 0);
3986                                 if (ret < 0) {
3987                                         err = ret;
3988                                         break;
3989                                 }
3990                                 BUG_ON(ret > 0);
3991                         }
3992 #else
3993                         BUG();
3994 #endif
3995                 }
3996
3997                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3998                         ret = add_tree_block(rc, &key, path, &blocks);
3999                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4000                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4001                         ret = add_data_references(rc, &key, path, &blocks);
4002                 } else {
4003                         btrfs_release_path(path);
4004                         ret = 0;
4005                 }
4006                 if (ret < 0) {
4007                         err = ret;
4008                         break;
4009                 }
4010
4011                 if (!RB_EMPTY_ROOT(&blocks)) {
4012                         ret = relocate_tree_blocks(trans, rc, &blocks);
4013                         if (ret < 0) {
4014                                 if (ret != -EAGAIN) {
4015                                         err = ret;
4016                                         break;
4017                                 }
4018                                 rc->extents_found--;
4019                                 rc->search_start = key.objectid;
4020                         }
4021                 }
4022
4023                 if (rc->commit_transaction) {
4024                         rc->commit_transaction = 0;
4025                         ret = btrfs_commit_transaction(trans, rc->extent_root);
4026                         BUG_ON(ret);
4027                 } else {
4028                         btrfs_end_transaction_throttle(trans, rc->extent_root);
4029                         btrfs_btree_balance_dirty(rc->extent_root);
4030                 }
4031                 trans = NULL;
4032
4033                 if (rc->stage == MOVE_DATA_EXTENTS &&
4034                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4035                         rc->found_file_extent = 1;
4036                         ret = relocate_data_extent(rc->data_inode,
4037                                                    &key, &rc->cluster);
4038                         if (ret < 0) {
4039                                 err = ret;
4040                                 break;
4041                         }
4042                 }
4043         }
4044         if (trans && progress && err == -ENOSPC) {
4045                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4046                                               rc->block_group->flags);
4047                 if (ret == 0) {
4048                         err = 0;
4049                         progress = 0;
4050                         goto restart;
4051                 }
4052         }
4053
4054         btrfs_release_path(path);
4055         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4056                           GFP_NOFS);
4057
4058         if (trans) {
4059                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4060                 btrfs_btree_balance_dirty(rc->extent_root);
4061         }
4062
4063         if (!err) {
4064                 ret = relocate_file_extent_cluster(rc->data_inode,
4065                                                    &rc->cluster);
4066                 if (ret < 0)
4067                         err = ret;
4068         }
4069
4070         rc->create_reloc_tree = 0;
4071         set_reloc_control(rc);
4072
4073         backref_cache_cleanup(&rc->backref_cache);
4074         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4075
4076         err = prepare_to_merge(rc, err);
4077
4078         merge_reloc_roots(rc);
4079
4080         rc->merge_reloc_tree = 0;
4081         unset_reloc_control(rc);
4082         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4083
4084         /* get rid of pinned extents */
4085         trans = btrfs_join_transaction(rc->extent_root);
4086         if (IS_ERR(trans))
4087                 err = PTR_ERR(trans);
4088         else
4089                 btrfs_commit_transaction(trans, rc->extent_root);
4090 out_free:
4091         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4092         btrfs_free_path(path);
4093         return err;
4094 }
4095
4096 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4097                                  struct btrfs_root *root, u64 objectid)
4098 {
4099         struct btrfs_path *path;
4100         struct btrfs_inode_item *item;
4101         struct extent_buffer *leaf;
4102         int ret;
4103
4104         path = btrfs_alloc_path();
4105         if (!path)
4106                 return -ENOMEM;
4107
4108         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4109         if (ret)
4110                 goto out;
4111
4112         leaf = path->nodes[0];
4113         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4114         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4115         btrfs_set_inode_generation(leaf, item, 1);
4116         btrfs_set_inode_size(leaf, item, 0);
4117         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4118         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4119                                           BTRFS_INODE_PREALLOC);
4120         btrfs_mark_buffer_dirty(leaf);
4121         btrfs_release_path(path);
4122 out:
4123         btrfs_free_path(path);
4124         return ret;
4125 }
4126
4127 /*
4128  * helper to create inode for data relocation.
4129  * the inode is in data relocation tree and its link count is 0
4130  */
4131 static noinline_for_stack
4132 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4133                                  struct btrfs_block_group_cache *group)
4134 {
4135         struct inode *inode = NULL;
4136         struct btrfs_trans_handle *trans;
4137         struct btrfs_root *root;
4138         struct btrfs_key key;
4139         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
4140         int err = 0;
4141
4142         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4143         if (IS_ERR(root))
4144                 return ERR_CAST(root);
4145
4146         trans = btrfs_start_transaction(root, 6);
4147         if (IS_ERR(trans))
4148                 return ERR_CAST(trans);
4149
4150         err = btrfs_find_free_objectid(root, &objectid);
4151         if (err)
4152                 goto out;
4153
4154         err = __insert_orphan_inode(trans, root, objectid);
4155         BUG_ON(err);
4156
4157         key.objectid = objectid;
4158         key.type = BTRFS_INODE_ITEM_KEY;
4159         key.offset = 0;
4160         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4161         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4162         BTRFS_I(inode)->index_cnt = group->key.objectid;
4163
4164         err = btrfs_orphan_add(trans, inode);
4165 out:
4166         btrfs_end_transaction(trans, root);
4167         btrfs_btree_balance_dirty(root);
4168         if (err) {
4169                 if (inode)
4170                         iput(inode);
4171                 inode = ERR_PTR(err);
4172         }
4173         return inode;
4174 }
4175
4176 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4177 {
4178         struct reloc_control *rc;
4179
4180         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4181         if (!rc)
4182                 return NULL;
4183
4184         INIT_LIST_HEAD(&rc->reloc_roots);
4185         backref_cache_init(&rc->backref_cache);
4186         mapping_tree_init(&rc->reloc_root_tree);
4187         extent_io_tree_init(&rc->processed_blocks,
4188                             fs_info->btree_inode->i_mapping);
4189         return rc;
4190 }
4191
4192 /*
4193  * function to relocate all extents in a block group.
4194  */
4195 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4196 {
4197         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4198         struct reloc_control *rc;
4199         struct inode *inode;
4200         struct btrfs_path *path;
4201         int ret;
4202         int rw = 0;
4203         int err = 0;
4204
4205         rc = alloc_reloc_control(fs_info);
4206         if (!rc)
4207                 return -ENOMEM;
4208
4209         rc->extent_root = extent_root;
4210
4211         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4212         BUG_ON(!rc->block_group);
4213
4214         if (!rc->block_group->ro) {
4215                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4216                 if (ret) {
4217                         err = ret;
4218                         goto out;
4219                 }
4220                 rw = 1;
4221         }
4222
4223         path = btrfs_alloc_path();
4224         if (!path) {
4225                 err = -ENOMEM;
4226                 goto out;
4227         }
4228
4229         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4230                                         path);
4231         btrfs_free_path(path);
4232
4233         if (!IS_ERR(inode))
4234                 ret = delete_block_group_cache(fs_info, inode, 0);
4235         else
4236                 ret = PTR_ERR(inode);
4237
4238         if (ret && ret != -ENOENT) {
4239                 err = ret;
4240                 goto out;
4241         }
4242
4243         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4244         if (IS_ERR(rc->data_inode)) {
4245                 err = PTR_ERR(rc->data_inode);
4246                 rc->data_inode = NULL;
4247                 goto out;
4248         }
4249
4250         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
4251                rc->block_group->key.objectid, rc->block_group->flags);
4252
4253         ret = btrfs_start_delalloc_roots(fs_info, 0);
4254         if (ret < 0) {
4255                 err = ret;
4256                 goto out;
4257         }
4258         btrfs_wait_ordered_roots(fs_info, -1);
4259
4260         while (1) {
4261                 mutex_lock(&fs_info->cleaner_mutex);
4262                 ret = relocate_block_group(rc);
4263                 mutex_unlock(&fs_info->cleaner_mutex);
4264                 if (ret < 0) {
4265                         err = ret;
4266                         goto out;
4267                 }
4268
4269                 if (rc->extents_found == 0)
4270                         break;
4271
4272                 printk(KERN_INFO "btrfs: found %llu extents\n",
4273                         rc->extents_found);
4274
4275                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4276                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4277                                                        (u64)-1);
4278                         if (ret) {
4279                                 err = ret;
4280                                 goto out;
4281                         }
4282                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4283                                                  0, -1);
4284                         rc->stage = UPDATE_DATA_PTRS;
4285                 }
4286         }
4287
4288         filemap_write_and_wait_range(fs_info->btree_inode->i_mapping,
4289                                      rc->block_group->key.objectid,
4290                                      rc->block_group->key.objectid +
4291                                      rc->block_group->key.offset - 1);
4292
4293         WARN_ON(rc->block_group->pinned > 0);
4294         WARN_ON(rc->block_group->reserved > 0);
4295         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4296 out:
4297         if (err && rw)
4298                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4299         iput(rc->data_inode);
4300         btrfs_put_block_group(rc->block_group);
4301         kfree(rc);
4302         return err;
4303 }
4304
4305 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4306 {
4307         struct btrfs_trans_handle *trans;
4308         int ret, err;
4309
4310         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4311         if (IS_ERR(trans))
4312                 return PTR_ERR(trans);
4313
4314         memset(&root->root_item.drop_progress, 0,
4315                 sizeof(root->root_item.drop_progress));
4316         root->root_item.drop_level = 0;
4317         btrfs_set_root_refs(&root->root_item, 0);
4318         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4319                                 &root->root_key, &root->root_item);
4320
4321         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4322         if (err)
4323                 return err;
4324         return ret;
4325 }
4326
4327 /*
4328  * recover relocation interrupted by system crash.
4329  *
4330  * this function resumes merging reloc trees with corresponding fs trees.
4331  * this is important for keeping the sharing of tree blocks
4332  */
4333 int btrfs_recover_relocation(struct btrfs_root *root)
4334 {
4335         LIST_HEAD(reloc_roots);
4336         struct btrfs_key key;
4337         struct btrfs_root *fs_root;
4338         struct btrfs_root *reloc_root;
4339         struct btrfs_path *path;
4340         struct extent_buffer *leaf;
4341         struct reloc_control *rc = NULL;
4342         struct btrfs_trans_handle *trans;
4343         int ret;
4344         int err = 0;
4345
4346         path = btrfs_alloc_path();
4347         if (!path)
4348                 return -ENOMEM;
4349         path->reada = -1;
4350
4351         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4352         key.type = BTRFS_ROOT_ITEM_KEY;
4353         key.offset = (u64)-1;
4354
4355         while (1) {
4356                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4357                                         path, 0, 0);
4358                 if (ret < 0) {
4359                         err = ret;
4360                         goto out;
4361                 }
4362                 if (ret > 0) {
4363                         if (path->slots[0] == 0)
4364                                 break;
4365                         path->slots[0]--;
4366                 }
4367                 leaf = path->nodes[0];
4368                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4369                 btrfs_release_path(path);
4370
4371                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4372                     key.type != BTRFS_ROOT_ITEM_KEY)
4373                         break;
4374
4375                 reloc_root = btrfs_read_fs_root(root, &key);
4376                 if (IS_ERR(reloc_root)) {
4377                         err = PTR_ERR(reloc_root);
4378                         goto out;
4379                 }
4380
4381                 list_add(&reloc_root->root_list, &reloc_roots);
4382
4383                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4384                         fs_root = read_fs_root(root->fs_info,
4385                                                reloc_root->root_key.offset);
4386                         if (IS_ERR(fs_root)) {
4387                                 ret = PTR_ERR(fs_root);
4388                                 if (ret != -ENOENT) {
4389                                         err = ret;
4390                                         goto out;
4391                                 }
4392                                 ret = mark_garbage_root(reloc_root);
4393                                 if (ret < 0) {
4394                                         err = ret;
4395                                         goto out;
4396                                 }
4397                         }
4398                 }
4399
4400                 if (key.offset == 0)
4401                         break;
4402
4403                 key.offset--;
4404         }
4405         btrfs_release_path(path);
4406
4407         if (list_empty(&reloc_roots))
4408                 goto out;
4409
4410         rc = alloc_reloc_control(root->fs_info);
4411         if (!rc) {
4412                 err = -ENOMEM;
4413                 goto out;
4414         }
4415
4416         rc->extent_root = root->fs_info->extent_root;
4417
4418         set_reloc_control(rc);
4419
4420         trans = btrfs_join_transaction(rc->extent_root);
4421         if (IS_ERR(trans)) {
4422                 unset_reloc_control(rc);
4423                 err = PTR_ERR(trans);
4424                 goto out_free;
4425         }
4426
4427         rc->merge_reloc_tree = 1;
4428
4429         while (!list_empty(&reloc_roots)) {
4430                 reloc_root = list_entry(reloc_roots.next,
4431                                         struct btrfs_root, root_list);
4432                 list_del(&reloc_root->root_list);
4433
4434                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4435                         list_add_tail(&reloc_root->root_list,
4436                                       &rc->reloc_roots);
4437                         continue;
4438                 }
4439
4440                 fs_root = read_fs_root(root->fs_info,
4441                                        reloc_root->root_key.offset);
4442                 if (IS_ERR(fs_root)) {
4443                         err = PTR_ERR(fs_root);
4444                         goto out_free;
4445                 }
4446
4447                 err = __add_reloc_root(reloc_root);
4448                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4449                 fs_root->reloc_root = reloc_root;
4450         }
4451
4452         err = btrfs_commit_transaction(trans, rc->extent_root);
4453         if (err)
4454                 goto out_free;
4455
4456         merge_reloc_roots(rc);
4457
4458         unset_reloc_control(rc);
4459
4460         trans = btrfs_join_transaction(rc->extent_root);
4461         if (IS_ERR(trans))
4462                 err = PTR_ERR(trans);
4463         else
4464                 err = btrfs_commit_transaction(trans, rc->extent_root);
4465 out_free:
4466         kfree(rc);
4467 out:
4468         if (!list_empty(&reloc_roots))
4469                 free_reloc_roots(&reloc_roots);
4470
4471         btrfs_free_path(path);
4472
4473         if (err == 0) {
4474                 /* cleanup orphan inode in data relocation tree */
4475                 fs_root = read_fs_root(root->fs_info,
4476                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4477                 if (IS_ERR(fs_root))
4478                         err = PTR_ERR(fs_root);
4479                 else
4480                         err = btrfs_orphan_cleanup(fs_root);
4481         }
4482         return err;
4483 }
4484
4485 /*
4486  * helper to add ordered checksum for data relocation.
4487  *
4488  * cloning checksum properly handles the nodatasum extents.
4489  * it also saves CPU time to re-calculate the checksum.
4490  */
4491 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4492 {
4493         struct btrfs_ordered_sum *sums;
4494         struct btrfs_ordered_extent *ordered;
4495         struct btrfs_root *root = BTRFS_I(inode)->root;
4496         int ret;
4497         u64 disk_bytenr;
4498         u64 new_bytenr;
4499         LIST_HEAD(list);
4500
4501         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4502         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4503
4504         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4505         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4506                                        disk_bytenr + len - 1, &list, 0);
4507         if (ret)
4508                 goto out;
4509
4510         while (!list_empty(&list)) {
4511                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4512                 list_del_init(&sums->list);
4513
4514                 /*
4515                  * We need to offset the new_bytenr based on where the csum is.
4516                  * We need to do this because we will read in entire prealloc
4517                  * extents but we may have written to say the middle of the
4518                  * prealloc extent, so we need to make sure the csum goes with
4519                  * the right disk offset.
4520                  *
4521                  * We can do this because the data reloc inode refers strictly
4522                  * to the on disk bytes, so we don't have to worry about
4523                  * disk_len vs real len like with real inodes since it's all
4524                  * disk length.
4525                  */
4526                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4527                 sums->bytenr = new_bytenr;
4528
4529                 btrfs_add_ordered_sum(inode, ordered, sums);
4530         }
4531 out:
4532         btrfs_put_ordered_extent(ordered);
4533         return ret;
4534 }
4535
4536 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4537                           struct btrfs_root *root, struct extent_buffer *buf,
4538                           struct extent_buffer *cow)
4539 {
4540         struct reloc_control *rc;
4541         struct backref_node *node;
4542         int first_cow = 0;
4543         int level;
4544         int ret = 0;
4545
4546         rc = root->fs_info->reloc_ctl;
4547         if (!rc)
4548                 return 0;
4549
4550         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4551                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4552
4553         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4554                 if (buf == root->node)
4555                         __update_reloc_root(root, cow->start);
4556         }
4557
4558         level = btrfs_header_level(buf);
4559         if (btrfs_header_generation(buf) <=
4560             btrfs_root_last_snapshot(&root->root_item))
4561                 first_cow = 1;
4562
4563         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4564             rc->create_reloc_tree) {
4565                 WARN_ON(!first_cow && level == 0);
4566
4567                 node = rc->backref_cache.path[level];
4568                 BUG_ON(node->bytenr != buf->start &&
4569                        node->new_bytenr != buf->start);
4570
4571                 drop_node_buffer(node);
4572                 extent_buffer_get(cow);
4573                 node->eb = cow;
4574                 node->new_bytenr = cow->start;
4575
4576                 if (!node->pending) {
4577                         list_move_tail(&node->list,
4578                                        &rc->backref_cache.pending[level]);
4579                         node->pending = 1;
4580                 }
4581
4582                 if (first_cow)
4583                         __mark_block_processed(rc, node);
4584
4585                 if (first_cow && level > 0)
4586                         rc->nodes_relocated += buf->len;
4587         }
4588
4589         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4590                 ret = replace_file_extents(trans, rc, root, cow);
4591         return ret;
4592 }
4593
4594 /*
4595  * called before creating snapshot. it calculates metadata reservation
4596  * requried for relocating tree blocks in the snapshot
4597  */
4598 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4599                               struct btrfs_pending_snapshot *pending,
4600                               u64 *bytes_to_reserve)
4601 {
4602         struct btrfs_root *root;
4603         struct reloc_control *rc;
4604
4605         root = pending->root;
4606         if (!root->reloc_root)
4607                 return;
4608
4609         rc = root->fs_info->reloc_ctl;
4610         if (!rc->merge_reloc_tree)
4611                 return;
4612
4613         root = root->reloc_root;
4614         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4615         /*
4616          * relocation is in the stage of merging trees. the space
4617          * used by merging a reloc tree is twice the size of
4618          * relocated tree nodes in the worst case. half for cowing
4619          * the reloc tree, half for cowing the fs tree. the space
4620          * used by cowing the reloc tree will be freed after the
4621          * tree is dropped. if we create snapshot, cowing the fs
4622          * tree may use more space than it frees. so we need
4623          * reserve extra space.
4624          */
4625         *bytes_to_reserve += rc->nodes_relocated;
4626 }
4627
4628 /*
4629  * called after snapshot is created. migrate block reservation
4630  * and create reloc root for the newly created snapshot
4631  */
4632 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4633                                struct btrfs_pending_snapshot *pending)
4634 {
4635         struct btrfs_root *root = pending->root;
4636         struct btrfs_root *reloc_root;
4637         struct btrfs_root *new_root;
4638         struct reloc_control *rc;
4639         int ret;
4640
4641         if (!root->reloc_root)
4642                 return 0;
4643
4644         rc = root->fs_info->reloc_ctl;
4645         rc->merging_rsv_size += rc->nodes_relocated;
4646
4647         if (rc->merge_reloc_tree) {
4648                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4649                                               rc->block_rsv,
4650                                               rc->nodes_relocated);
4651                 if (ret)
4652                         return ret;
4653         }
4654
4655         new_root = pending->snap;
4656         reloc_root = create_reloc_root(trans, root->reloc_root,
4657                                        new_root->root_key.objectid);
4658         if (IS_ERR(reloc_root))
4659                 return PTR_ERR(reloc_root);
4660
4661         ret = __add_reloc_root(reloc_root);
4662         BUG_ON(ret < 0);
4663         new_root->reloc_root = reloc_root;
4664
4665         if (rc->create_reloc_tree)
4666                 ret = clone_backref_node(trans, rc, root, reloc_root);
4667         return ret;
4668 }