fs/btrfs/relocation.c

   1 /*
   2  * Copyright (C) 2009 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/writeback.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/rbtree.h>
  24 #include <linux/slab.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "volumes.h"
  29 #include "locking.h"
  30 #include "btrfs_inode.h"
  31 #include "async-thread.h"
  32 #include "free-space-cache.h"
  33 #include "inode-map.h"
  34
  35 /*
  36  * backref_node, mapping_node and tree_block start with this
  37  */
  38 struct tree_entry {
  39         struct rb_node rb_node;
  40         u64 bytenr;
  41 };
  42
  43 /*
  44  * present a tree block in the backref cache
  45  */
  46 struct backref_node {
  47         struct rb_node rb_node;
  48         u64 bytenr;
  49
  50         u64 new_bytenr;
  51         /* objectid of tree block owner, can be not uptodate */
  52         u64 owner;
  53         /* link to pending, changed or detached list */
  54         struct list_head list;
  55         /* list of upper level blocks reference this block */
  56         struct list_head upper;
  57         /* list of child blocks in the cache */
  58         struct list_head lower;
  59         /* NULL if this node is not tree root */
  60         struct btrfs_root *root;
  61         /* extent buffer got by COW the block */
  62         struct extent_buffer *eb;
  63         /* level of tree block */
  64         unsigned int level:8;
  65         /* is the block in non-reference counted tree */
  66         unsigned int cowonly:1;
  67         /* 1 if no child node in the cache */
  68         unsigned int lowest:1;
  69         /* is the extent buffer locked */
  70         unsigned int locked:1;
  71         /* has the block been processed */
  72         unsigned int processed:1;
  73         /* have backrefs of this block been checked */
  74         unsigned int checked:1;
  75         /*
  76          * 1 if corresponding block has been cowed but some upper
  77          * level block pointers may not point to the new location
  78          */
  79         unsigned int pending:1;
  80         /*
  81          * 1 if the backref node isn't connected to any other
  82          * backref node.
  83          */
  84         unsigned int detached:1;
  85 };
  86
  87 /*
  88  * present a block pointer in the backref cache
  89  */
  90 struct backref_edge {
  91         struct list_head list[2];
  92         struct backref_node *node[2];
  93 };
  94
  95 #define LOWER   0
  96 #define UPPER   1
  97 #define RELOCATION_RESERVED_NODES       256
  98
  99 struct backref_cache {
 100         /* red black tree of all backref nodes in the cache */
 101         struct rb_root rb_root;
 102         /* for passing backref nodes to btrfs_reloc_cow_block */
 103         struct backref_node *path[BTRFS_MAX_LEVEL];
 104         /*
 105          * list of blocks that have been cowed but some block
 106          * pointers in upper level blocks may not reflect the
 107          * new location
 108          */
 109         struct list_head pending[BTRFS_MAX_LEVEL];
 110         /* list of backref nodes with no child node */
 111         struct list_head leaves;
 112         /* list of blocks that have been cowed in current transaction */
 113         struct list_head changed;
 114         /* list of detached backref node. */
 115         struct list_head detached;
 116
 117         u64 last_trans;
 118
 119         int nr_nodes;
 120         int nr_edges;
 121 };
 122
 123 /*
 124  * map address of tree root to tree
 125  */
 126 struct mapping_node {
 127         struct rb_node rb_node;
 128         u64 bytenr;
 129         void *data;
 130 };
 131
 132 struct mapping_tree {
 133         struct rb_root rb_root;
 134         spinlock_t lock;
 135 };
 136
 137 /*
 138  * present a tree block to process
 139  */
 140 struct tree_block {
 141         struct rb_node rb_node;
 142         u64 bytenr;
 143         struct btrfs_key key;
 144         unsigned int level:8;
 145         unsigned int key_ready:1;
 146 };
 147
 148 #define MAX_EXTENTS 128
 149
 150 struct file_extent_cluster {
 151         u64 start;
 152         u64 end;
 153         u64 boundary[MAX_EXTENTS];
 154         unsigned int nr;
 155 };
 156
 157 struct reloc_control {
 158         /* block group to relocate */
 159         struct btrfs_block_group_cache *block_group;
 160         /* extent tree */
 161         struct btrfs_root *extent_root;
 162         /* inode for moving data */
 163         struct inode *data_inode;
 164
 165         struct btrfs_block_rsv *block_rsv;
 166
 167         struct backref_cache backref_cache;
 168
 169         struct file_extent_cluster cluster;
 170         /* tree blocks have been processed */
 171         struct extent_io_tree processed_blocks;
 172         /* map start of tree root to corresponding reloc tree */
 173         struct mapping_tree reloc_root_tree;
 174         /* list of reloc trees */
 175         struct list_head reloc_roots;
 176         /* size of metadata reservation for merging reloc trees */
 177         u64 merging_rsv_size;
 178         /* size of relocated tree nodes */
 179         u64 nodes_relocated;
 180         /* reserved size for block group relocation*/
 181         u64 reserved_bytes;
 182
 183         u64 search_start;
 184         u64 extents_found;
 185
 186         unsigned int stage:8;
 187         unsigned int create_reloc_tree:1;
 188         unsigned int merge_reloc_tree:1;
 189         unsigned int found_file_extent:1;
 190 };
 191
 192 /* stages of data relocation */
 193 #define MOVE_DATA_EXTENTS       0
 194 #define UPDATE_DATA_PTRS        1
 195
 196 static void remove_backref_node(struct backref_cache *cache,
 197                                 struct backref_node *node);
 198 static void __mark_block_processed(struct reloc_control *rc,
 199                                    struct backref_node *node);
 200
 201 static void mapping_tree_init(struct mapping_tree *tree)
 202 {
 203         tree->rb_root = RB_ROOT;
 204         spin_lock_init(&tree->lock);
 205 }
 206
 207 static void backref_cache_init(struct backref_cache *cache)
 208 {
 209         int i;
 210         cache->rb_root = RB_ROOT;
 211         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 212                 INIT_LIST_HEAD(&cache->pending[i]);
 213         INIT_LIST_HEAD(&cache->changed);
 214         INIT_LIST_HEAD(&cache->detached);
 215         INIT_LIST_HEAD(&cache->leaves);
 216 }
 217
 218 static void backref_cache_cleanup(struct backref_cache *cache)
 219 {
 220         struct backref_node *node;
 221         int i;
 222
 223         while (!list_empty(&cache->detached)) {
 224                 node = list_entry(cache->detached.next,
 225                                   struct backref_node, list);
 226                 remove_backref_node(cache, node);
 227         }
 228
 229         while (!list_empty(&cache->leaves)) {
 230                 node = list_entry(cache->leaves.next,
 231                                   struct backref_node, lower);
 232                 remove_backref_node(cache, node);
 233         }
 234
 235         cache->last_trans = 0;
 236
 237         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 238                 BUG_ON(!list_empty(&cache->pending[i]));
 239         BUG_ON(!list_empty(&cache->changed));
 240         BUG_ON(!list_empty(&cache->detached));
 241         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
 242         BUG_ON(cache->nr_nodes);
 243         BUG_ON(cache->nr_edges);
 244 }
 245
 246 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 247 {
 248         struct backref_node *node;
 249
 250         node = kzalloc(sizeof(*node), GFP_NOFS);
 251         if (node) {
 252                 INIT_LIST_HEAD(&node->list);
 253                 INIT_LIST_HEAD(&node->upper);
 254                 INIT_LIST_HEAD(&node->lower);
 255                 RB_CLEAR_NODE(&node->rb_node);
 256                 cache->nr_nodes++;
 257         }
 258         return node;
 259 }
 260
 261 static void free_backref_node(struct backref_cache *cache,
 262                               struct backref_node *node)
 263 {
 264         if (node) {
 265                 cache->nr_nodes--;
 266                 kfree(node);
 267         }
 268 }
 269
 270 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 271 {
 272         struct backref_edge *edge;
 273
 274         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 275         if (edge)
 276                 cache->nr_edges++;
 277         return edge;
 278 }
 279
 280 static void free_backref_edge(struct backref_cache *cache,
 281                               struct backref_edge *edge)
 282 {
 283         if (edge) {
 284                 cache->nr_edges--;
 285                 kfree(edge);
 286         }
 287 }
 288
 289 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 290                                    struct rb_node *node)
 291 {
 292         struct rb_node **p = &root->rb_node;
 293         struct rb_node *parent = NULL;
 294         struct tree_entry *entry;
 295
 296         while (*p) {
 297                 parent = *p;
 298                 entry = rb_entry(parent, struct tree_entry, rb_node);
 299
 300                 if (bytenr < entry->bytenr)
 301                         p = &(*p)->rb_left;
 302                 else if (bytenr > entry->bytenr)
 303                         p = &(*p)->rb_right;
 304                 else
 305                         return parent;
 306         }
 307
 308         rb_link_node(node, parent, p);
 309         rb_insert_color(node, root);
 310         return NULL;
 311 }
 312
 313 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 314 {
 315         struct rb_node *n = root->rb_node;
 316         struct tree_entry *entry;
 317
 318         while (n) {
 319                 entry = rb_entry(n, struct tree_entry, rb_node);
 320
 321                 if (bytenr < entry->bytenr)
 322                         n = n->rb_left;
 323                 else if (bytenr > entry->bytenr)
 324                         n = n->rb_right;
 325                 else
 326                         return n;
 327         }
 328         return NULL;
 329 }
 330
 331 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 332 {
 333
 334         struct btrfs_fs_info *fs_info = NULL;
 335         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 336                                               rb_node);
 337         if (bnode->root)
 338                 fs_info = bnode->root->fs_info;
 339         btrfs_panic(fs_info, errno, "Inconsistency in backref cache "
 340                     "found at offset %llu", bytenr);
 341 }
 342
 343 /*
 344  * walk up backref nodes until reach node presents tree root
 345  */
 346 static struct backref_node *walk_up_backref(struct backref_node *node,
 347                                             struct backref_edge *edges[],
 348                                             int *index)
 349 {
 350         struct backref_edge *edge;
 351         int idx = *index;
 352
 353         while (!list_empty(&node->upper)) {
 354                 edge = list_entry(node->upper.next,
 355                                   struct backref_edge, list[LOWER]);
 356                 edges[idx++] = edge;
 357                 node = edge->node[UPPER];
 358         }
 359         BUG_ON(node->detached);
 360         *index = idx;
 361         return node;
 362 }
 363
 364 /*
 365  * walk down backref nodes to find start of next reference path
 366  */
 367 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 368                                               int *index)
 369 {
 370         struct backref_edge *edge;
 371         struct backref_node *lower;
 372         int idx = *index;
 373
 374         while (idx > 0) {
 375                 edge = edges[idx - 1];
 376                 lower = edge->node[LOWER];
 377                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 378                         idx--;
 379                         continue;
 380                 }
 381                 edge = list_entry(edge->list[LOWER].next,
 382                                   struct backref_edge, list[LOWER]);
 383                 edges[idx - 1] = edge;
 384                 *index = idx;
 385                 return edge->node[UPPER];
 386         }
 387         *index = 0;
 388         return NULL;
 389 }
 390
 391 static void unlock_node_buffer(struct backref_node *node)
 392 {
 393         if (node->locked) {
 394                 btrfs_tree_unlock(node->eb);
 395                 node->locked = 0;
 396         }
 397 }
 398
 399 static void drop_node_buffer(struct backref_node *node)
 400 {
 401         if (node->eb) {
 402                 unlock_node_buffer(node);
 403                 free_extent_buffer(node->eb);
 404                 node->eb = NULL;
 405         }
 406 }
 407
 408 static void drop_backref_node(struct backref_cache *tree,
 409                               struct backref_node *node)
 410 {
 411         BUG_ON(!list_empty(&node->upper));
 412
 413         drop_node_buffer(node);
 414         list_del(&node->list);
 415         list_del(&node->lower);
 416         if (!RB_EMPTY_NODE(&node->rb_node))
 417                 rb_erase(&node->rb_node, &tree->rb_root);
 418         free_backref_node(tree, node);
 419 }
 420
 421 /*
 422  * remove a backref node from the backref cache
 423  */
 424 static void remove_backref_node(struct backref_cache *cache,
 425                                 struct backref_node *node)
 426 {
 427         struct backref_node *upper;
 428         struct backref_edge *edge;
 429
 430         if (!node)
 431                 return;
 432
 433         BUG_ON(!node->lowest && !node->detached);
 434         while (!list_empty(&node->upper)) {
 435                 edge = list_entry(node->upper.next, struct backref_edge,
 436                                   list[LOWER]);
 437                 upper = edge->node[UPPER];
 438                 list_del(&edge->list[LOWER]);
 439                 list_del(&edge->list[UPPER]);
 440                 free_backref_edge(cache, edge);
 441
 442                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 443                         BUG_ON(!list_empty(&node->upper));
 444                         drop_backref_node(cache, node);
 445                         node = upper;
 446                         node->lowest = 1;
 447                         continue;
 448                 }
 449                 /*
 450                  * add the node to leaf node list if no other
 451                  * child block cached.
 452                  */
 453                 if (list_empty(&upper->lower)) {
 454                         list_add_tail(&upper->lower, &cache->leaves);
 455                         upper->lowest = 1;
 456                 }
 457         }
 458
 459         drop_backref_node(cache, node);
 460 }
 461
 462 static void update_backref_node(struct backref_cache *cache,
 463                                 struct backref_node *node, u64 bytenr)
 464 {
 465         struct rb_node *rb_node;
 466         rb_erase(&node->rb_node, &cache->rb_root);
 467         node->bytenr = bytenr;
 468         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 469         if (rb_node)
 470                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 471 }
 472
 473 /*
 474  * update backref cache after a transaction commit
 475  */
 476 static int update_backref_cache(struct btrfs_trans_handle *trans,
 477                                 struct backref_cache *cache)
 478 {
 479         struct backref_node *node;
 480         int level = 0;
 481
 482         if (cache->last_trans == 0) {
 483                 cache->last_trans = trans->transid;
 484                 return 0;
 485         }
 486
 487         if (cache->last_trans == trans->transid)
 488                 return 0;
 489
 490         /*
 491          * detached nodes are used to avoid unnecessary backref
 492          * lookup. transaction commit changes the extent tree.
 493          * so the detached nodes are no longer useful.
 494          */
 495         while (!list_empty(&cache->detached)) {
 496                 node = list_entry(cache->detached.next,
 497                                   struct backref_node, list);
 498                 remove_backref_node(cache, node);
 499         }
 500
 501         while (!list_empty(&cache->changed)) {
 502                 node = list_entry(cache->changed.next,
 503                                   struct backref_node, list);
 504                 list_del_init(&node->list);
 505                 BUG_ON(node->pending);
 506                 update_backref_node(cache, node, node->new_bytenr);
 507         }
 508
 509         /*
 510          * some nodes can be left in the pending list if there were
 511          * errors during processing the pending nodes.
 512          */
 513         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 514                 list_for_each_entry(node, &cache->pending[level], list) {
 515                         BUG_ON(!node->pending);
 516                         if (node->bytenr == node->new_bytenr)
 517                                 continue;
 518                         update_backref_node(cache, node, node->new_bytenr);
 519                 }
 520         }
 521
 522         cache->last_trans = 0;
 523         return 1;
 524 }
 525
 526
 527 static int should_ignore_root(struct btrfs_root *root)
 528 {
 529         struct btrfs_root *reloc_root;
 530
 531         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 532                 return 0;
 533
 534         reloc_root = root->reloc_root;
 535         if (!reloc_root)
 536                 return 0;
 537
 538         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 539             root->fs_info->running_transaction->transid - 1)
 540                 return 0;
 541         /*
 542          * if there is reloc tree and it was created in previous
 543          * transaction backref lookup can find the reloc tree,
 544          * so backref node for the fs tree root is useless for
 545          * relocation.
 546          */
 547         return 1;
 548 }
 549 /*
 550  * find reloc tree by address of tree root
 551  */
 552 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 553                                           u64 bytenr)
 554 {
 555         struct rb_node *rb_node;
 556         struct mapping_node *node;
 557         struct btrfs_root *root = NULL;
 558
 559         spin_lock(&rc->reloc_root_tree.lock);
 560         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 561         if (rb_node) {
 562                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 563                 root = (struct btrfs_root *)node->data;
 564         }
 565         spin_unlock(&rc->reloc_root_tree.lock);
 566         return root;
 567 }
 568
 569 static int is_cowonly_root(u64 root_objectid)
 570 {
 571         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 572             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 573             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 574             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 575             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 576             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 577             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 578             root_objectid == BTRFS_QUOTA_TREE_OBJECTID)
 579                 return 1;
 580         return 0;
 581 }
 582
 583 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 584                                         u64 root_objectid)
 585 {
 586         struct btrfs_key key;
 587
 588         key.objectid = root_objectid;
 589         key.type = BTRFS_ROOT_ITEM_KEY;
 590         if (is_cowonly_root(root_objectid))
 591                 key.offset = 0;
 592         else
 593                 key.offset = (u64)-1;
 594
 595         return btrfs_get_fs_root(fs_info, &key, false);
 596 }
 597
 598 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 599 static noinline_for_stack
 600 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 601                                   struct extent_buffer *leaf,
 602                                   struct btrfs_extent_ref_v0 *ref0)
 603 {
 604         struct btrfs_root *root;
 605         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 606         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 607
 608         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 609
 610         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 611         BUG_ON(IS_ERR(root));
 612
 613         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 614             generation != btrfs_root_generation(&root->root_item))
 615                 return NULL;
 616
 617         return root;
 618 }
 619 #endif
 620
 621 static noinline_for_stack
 622 int find_inline_backref(struct extent_buffer *leaf, int slot,
 623                         unsigned long *ptr, unsigned long *end)
 624 {
 625         struct btrfs_key key;
 626         struct btrfs_extent_item *ei;
 627         struct btrfs_tree_block_info *bi;
 628         u32 item_size;
 629
 630         btrfs_item_key_to_cpu(leaf, &key, slot);
 631
 632         item_size = btrfs_item_size_nr(leaf, slot);
 633 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 634         if (item_size < sizeof(*ei)) {
 635                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 636                 return 1;
 637         }
 638 #endif
 639         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 640         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 641                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 642
 643         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 644             item_size <= sizeof(*ei) + sizeof(*bi)) {
 645                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 646                 return 1;
 647         }
 648         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 649             item_size <= sizeof(*ei)) {
 650                 WARN_ON(item_size < sizeof(*ei));
 651                 return 1;
 652         }
 653
 654         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 655                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 656                 *ptr = (unsigned long)(bi + 1);
 657         } else {
 658                 *ptr = (unsigned long)(ei + 1);
 659         }
 660         *end = (unsigned long)ei + item_size;
 661         return 0;
 662 }
 663
 664 /*
 665  * build backref tree for a given tree block. root of the backref tree
 666  * corresponds the tree block, leaves of the backref tree correspond
 667  * roots of b-trees that reference the tree block.
 668  *
 669  * the basic idea of this function is check backrefs of a given block
 670  * to find upper level blocks that refernece the block, and then check
 671  * bakcrefs of these upper level blocks recursively. the recursion stop
 672  * when tree root is reached or backrefs for the block is cached.
 673  *
 674  * NOTE: if we find backrefs for a block are cached, we know backrefs
 675  * for all upper level blocks that directly/indirectly reference the
 676  * block are also cached.
 677  */
 678 static noinline_for_stack
 679 struct backref_node *build_backref_tree(struct reloc_control *rc,
 680                                         struct btrfs_key *node_key,
 681                                         int level, u64 bytenr)
 682 {
 683         struct backref_cache *cache = &rc->backref_cache;
 684         struct btrfs_path *path1;
 685         struct btrfs_path *path2;
 686         struct extent_buffer *eb;
 687         struct btrfs_root *root;
 688         struct backref_node *cur;
 689         struct backref_node *upper;
 690         struct backref_node *lower;
 691         struct backref_node *node = NULL;
 692         struct backref_node *exist = NULL;
 693         struct backref_edge *edge;
 694         struct rb_node *rb_node;
 695         struct btrfs_key key;
 696         unsigned long end;
 697         unsigned long ptr;
 698         LIST_HEAD(list);
 699         LIST_HEAD(useless);
 700         int cowonly;
 701         int ret;
 702         int err = 0;
 703         bool need_check = true;
 704
 705         path1 = btrfs_alloc_path();
 706         path2 = btrfs_alloc_path();
 707         if (!path1 || !path2) {
 708                 err = -ENOMEM;
 709                 goto out;
 710         }
 711         path1->reada = 1;
 712         path2->reada = 2;
 713
 714         node = alloc_backref_node(cache);
 715         if (!node) {
 716                 err = -ENOMEM;
 717                 goto out;
 718         }
 719
 720         node->bytenr = bytenr;
 721         node->level = level;
 722         node->lowest = 1;
 723         cur = node;
 724 again:
 725         end = 0;
 726         ptr = 0;
 727         key.objectid = cur->bytenr;
 728         key.type = BTRFS_METADATA_ITEM_KEY;
 729         key.offset = (u64)-1;
 730
 731         path1->search_commit_root = 1;
 732         path1->skip_locking = 1;
 733         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 734                                 0, 0);
 735         if (ret < 0) {
 736                 err = ret;
 737                 goto out;
 738         }
 739         BUG_ON(!ret || !path1->slots[0]);
 740
 741         path1->slots[0]--;
 742
 743         WARN_ON(cur->checked);
 744         if (!list_empty(&cur->upper)) {
 745                 /*
 746                  * the backref was added previously when processing
 747                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 748                  */
 749                 BUG_ON(!list_is_singular(&cur->upper));
 750                 edge = list_entry(cur->upper.next, struct backref_edge,
 751                                   list[LOWER]);
 752                 BUG_ON(!list_empty(&edge->list[UPPER]));
 753                 exist = edge->node[UPPER];
 754                 /*
 755                  * add the upper level block to pending list if we need
 756                  * check its backrefs
 757                  */
 758                 if (!exist->checked)
 759                         list_add_tail(&edge->list[UPPER], &list);
 760         } else {
 761                 exist = NULL;
 762         }
 763
 764         while (1) {
 765                 cond_resched();
 766                 eb = path1->nodes[0];
 767
 768                 if (ptr >= end) {
 769                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 770                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 771                                 if (ret < 0) {
 772                                         err = ret;
 773                                         goto out;
 774                                 }
 775                                 if (ret > 0)
 776                                         break;
 777                                 eb = path1->nodes[0];
 778                         }
 779
 780                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 781                         if (key.objectid != cur->bytenr) {
 782                                 WARN_ON(exist);
 783                                 break;
 784                         }
 785
 786                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 787                             key.type == BTRFS_METADATA_ITEM_KEY) {
 788                                 ret = find_inline_backref(eb, path1->slots[0],
 789                                                           &ptr, &end);
 790                                 if (ret)
 791                                         goto next;
 792                         }
 793                 }
 794
 795                 if (ptr < end) {
 796                         /* update key for inline back ref */
 797                         struct btrfs_extent_inline_ref *iref;
 798                         iref = (struct btrfs_extent_inline_ref *)ptr;
 799                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 800                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 801                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 802                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 803                 }
 804
 805                 if (exist &&
 806                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 807                       exist->owner == key.offset) ||
 808                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 809                       exist->bytenr == key.offset))) {
 810                         exist = NULL;
 811                         goto next;
 812                 }
 813
 814 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 815                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 816                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 817                         if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
 818                                 struct btrfs_extent_ref_v0 *ref0;
 819                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 820                                                 struct btrfs_extent_ref_v0);
 821                                 if (key.objectid == key.offset) {
 822                                         root = find_tree_root(rc, eb, ref0);
 823                                         if (root && !should_ignore_root(root))
 824                                                 cur->root = root;
 825                                         else
 826                                                 list_add(&cur->list, &useless);
 827                                         break;
 828                                 }
 829                                 if (is_cowonly_root(btrfs_ref_root_v0(eb,
 830                                                                       ref0)))
 831                                         cur->cowonly = 1;
 832                         }
 833 #else
 834                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 835                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 836 #endif
 837                         if (key.objectid == key.offset) {
 838                                 /*
 839                                  * only root blocks of reloc trees use
 840                                  * backref of this type.
 841                                  */
 842                                 root = find_reloc_root(rc, cur->bytenr);
 843                                 BUG_ON(!root);
 844                                 cur->root = root;
 845                                 break;
 846                         }
 847
 848                         edge = alloc_backref_edge(cache);
 849                         if (!edge) {
 850                                 err = -ENOMEM;
 851                                 goto out;
 852                         }
 853                         rb_node = tree_search(&cache->rb_root, key.offset);
 854                         if (!rb_node) {
 855                                 upper = alloc_backref_node(cache);
 856                                 if (!upper) {
 857                                         free_backref_edge(cache, edge);
 858                                         err = -ENOMEM;
 859                                         goto out;
 860                                 }
 861                                 upper->bytenr = key.offset;
 862                                 upper->level = cur->level + 1;
 863                                 /*
 864                                  *  backrefs for the upper level block isn't
 865                                  *  cached, add the block to pending list
 866                                  */
 867                                 list_add_tail(&edge->list[UPPER], &list);
 868                         } else {
 869                                 upper = rb_entry(rb_node, struct backref_node,
 870                                                  rb_node);
 871                                 BUG_ON(!upper->checked);
 872                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 873                         }
 874                         list_add_tail(&edge->list[LOWER], &cur->upper);
 875                         edge->node[LOWER] = cur;
 876                         edge->node[UPPER] = upper;
 877
 878                         goto next;
 879                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 880                         goto next;
 881                 }
 882
 883                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 884                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 885                 if (IS_ERR(root)) {
 886                         err = PTR_ERR(root);
 887                         goto out;
 888                 }
 889
 890                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 891                         cur->cowonly = 1;
 892
 893                 if (btrfs_root_level(&root->root_item) == cur->level) {
 894                         /* tree root */
 895                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 896                                cur->bytenr);
 897                         if (should_ignore_root(root))
 898                                 list_add(&cur->list, &useless);
 899                         else
 900                                 cur->root = root;
 901                         break;
 902                 }
 903
 904                 level = cur->level + 1;
 905
 906                 /*
 907                  * searching the tree to find upper level blocks
 908                  * reference the block.
 909                  */
 910                 path2->search_commit_root = 1;
 911                 path2->skip_locking = 1;
 912                 path2->lowest_level = level;
 913                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 914                 path2->lowest_level = 0;
 915                 if (ret < 0) {
 916                         err = ret;
 917                         goto out;
 918                 }
 919                 if (ret > 0 && path2->slots[level] > 0)
 920                         path2->slots[level]--;
 921
 922                 eb = path2->nodes[level];
 923                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 924                         cur->bytenr);
 925
 926                 lower = cur;
 927                 need_check = true;
 928                 for (; level < BTRFS_MAX_LEVEL; level++) {
 929                         if (!path2->nodes[level]) {
 930                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 931                                        lower->bytenr);
 932                                 if (should_ignore_root(root))
 933                                         list_add(&lower->list, &useless);
 934                                 else
 935                                         lower->root = root;
 936                                 break;
 937                         }
 938
 939                         edge = alloc_backref_edge(cache);
 940                         if (!edge) {
 941                                 err = -ENOMEM;
 942                                 goto out;
 943                         }
 944
 945                         eb = path2->nodes[level];
 946                         rb_node = tree_search(&cache->rb_root, eb->start);
 947                         if (!rb_node) {
 948                                 upper = alloc_backref_node(cache);
 949                                 if (!upper) {
 950                                         free_backref_edge(cache, edge);
 951                                         err = -ENOMEM;
 952                                         goto out;
 953                                 }
 954                                 upper->bytenr = eb->start;
 955                                 upper->owner = btrfs_header_owner(eb);
 956                                 upper->level = lower->level + 1;
 957                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 958                                               &root->state))
 959                                         upper->cowonly = 1;
 960
 961                                 /*
 962                                  * if we know the block isn't shared
 963                                  * we can void checking its backrefs.
 964                                  */
 965                                 if (btrfs_block_can_be_shared(root, eb))
 966                                         upper->checked = 0;
 967                                 else
 968                                         upper->checked = 1;
 969
 970                                 /*
 971                                  * add the block to pending list if we
 972                                  * need check its backrefs, we only do this once
 973                                  * while walking up a tree as we will catch
 974                                  * anything else later on.
 975                                  */
 976                                 if (!upper->checked && need_check) {
 977                                         need_check = false;
 978                                         list_add_tail(&edge->list[UPPER],
 979                                                       &list);
 980                                 } else
 981                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 982                         } else {
 983                                 upper = rb_entry(rb_node, struct backref_node,
 984                                                  rb_node);
 985                                 BUG_ON(!upper->checked);
 986                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 987                                 if (!upper->owner)
 988                                         upper->owner = btrfs_header_owner(eb);
 989                         }
 990                         list_add_tail(&edge->list[LOWER], &lower->upper);
 991                         edge->node[LOWER] = lower;
 992                         edge->node[UPPER] = upper;
 993
 994                         if (rb_node)
 995                                 break;
 996                         lower = upper;
 997                         upper = NULL;
 998                 }
 999                 btrfs_release_path(path2);
1000 next:
1001                 if (ptr < end) {
1002                         ptr += btrfs_extent_inline_ref_size(key.type);
1003                         if (ptr >= end) {
1004                                 WARN_ON(ptr > end);
1005                                 ptr = 0;
1006                                 end = 0;
1007                         }
1008                 }
1009                 if (ptr >= end)
1010                         path1->slots[0]++;
1011         }
1012         btrfs_release_path(path1);
1013
1014         cur->checked = 1;
1015         WARN_ON(exist);
1016
1017         /* the pending list isn't empty, take the first block to process */
1018         if (!list_empty(&list)) {
1019                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1020                 list_del_init(&edge->list[UPPER]);
1021                 cur = edge->node[UPPER];
1022                 goto again;
1023         }
1024
1025         /*
1026          * everything goes well, connect backref nodes and insert backref nodes
1027          * into the cache.
1028          */
1029         BUG_ON(!node->checked);
1030         cowonly = node->cowonly;
1031         if (!cowonly) {
1032                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1033                                       &node->rb_node);
1034                 if (rb_node)
1035                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1036                 list_add_tail(&node->lower, &cache->leaves);
1037         }
1038
1039         list_for_each_entry(edge, &node->upper, list[LOWER])
1040                 list_add_tail(&edge->list[UPPER], &list);
1041
1042         while (!list_empty(&list)) {
1043                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1044                 list_del_init(&edge->list[UPPER]);
1045                 upper = edge->node[UPPER];
1046                 if (upper->detached) {
1047                         list_del(&edge->list[LOWER]);
1048                         lower = edge->node[LOWER];
1049                         free_backref_edge(cache, edge);
1050                         if (list_empty(&lower->upper))
1051                                 list_add(&lower->list, &useless);
1052                         continue;
1053                 }
1054
1055                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1056                         if (upper->lowest) {
1057                                 list_del_init(&upper->lower);
1058                                 upper->lowest = 0;
1059                         }
1060
1061                         list_add_tail(&edge->list[UPPER], &upper->lower);
1062                         continue;
1063                 }
1064
1065                 BUG_ON(!upper->checked);
1066                 BUG_ON(cowonly != upper->cowonly);
1067                 if (!cowonly) {
1068                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1069                                               &upper->rb_node);
1070                         if (rb_node)
1071                                 backref_tree_panic(rb_node, -EEXIST,
1072                                                    upper->bytenr);
1073                 }
1074
1075                 list_add_tail(&edge->list[UPPER], &upper->lower);
1076
1077                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1078                         list_add_tail(&edge->list[UPPER], &list);
1079         }
1080         /*
1081          * process useless backref nodes. backref nodes for tree leaves
1082          * are deleted from the cache. backref nodes for upper level
1083          * tree blocks are left in the cache to avoid unnecessary backref
1084          * lookup.
1085          */
1086         while (!list_empty(&useless)) {
1087                 upper = list_entry(useless.next, struct backref_node, list);
1088                 list_del_init(&upper->list);
1089                 BUG_ON(!list_empty(&upper->upper));
1090                 if (upper == node)
1091                         node = NULL;
1092                 if (upper->lowest) {
1093                         list_del_init(&upper->lower);
1094                         upper->lowest = 0;
1095                 }
1096                 while (!list_empty(&upper->lower)) {
1097                         edge = list_entry(upper->lower.next,
1098                                           struct backref_edge, list[UPPER]);
1099                         list_del(&edge->list[UPPER]);
1100                         list_del(&edge->list[LOWER]);
1101                         lower = edge->node[LOWER];
1102                         free_backref_edge(cache, edge);
1103
1104                         if (list_empty(&lower->upper))
1105                                 list_add(&lower->list, &useless);
1106                 }
1107                 __mark_block_processed(rc, upper);
1108                 if (upper->level > 0) {
1109                         list_add(&upper->list, &cache->detached);
1110                         upper->detached = 1;
1111                 } else {
1112                         rb_erase(&upper->rb_node, &cache->rb_root);
1113                         free_backref_node(cache, upper);
1114                 }
1115         }
1116 out:
1117         btrfs_free_path(path1);
1118         btrfs_free_path(path2);
1119         if (err) {
1120                 while (!list_empty(&useless)) {
1121                         lower = list_entry(useless.next,
1122                                            struct backref_node, upper);
1123                         list_del_init(&lower->upper);
1124                 }
1125                 upper = node;
1126                 INIT_LIST_HEAD(&list);
1127                 while (upper) {
1128                         if (RB_EMPTY_NODE(&upper->rb_node)) {
1129                                 list_splice_tail(&upper->upper, &list);
1130                                 free_backref_node(cache, upper);
1131                         }
1132
1133                         if (list_empty(&list))
1134                                 break;
1135
1136                         edge = list_entry(list.next, struct backref_edge,
1137                                           list[LOWER]);
1138                         list_del(&edge->list[LOWER]);
1139                         upper = edge->node[UPPER];
1140                         free_backref_edge(cache, edge);
1141                 }
1142                 return ERR_PTR(err);
1143         }
1144         BUG_ON(node && node->detached);
1145         return node;
1146 }
1147
1148 /*
1149  * helper to add backref node for the newly created snapshot.
1150  * the backref node is created by cloning backref node that
1151  * corresponds to root of source tree
1152  */
1153 static int clone_backref_node(struct btrfs_trans_handle *trans,
1154                               struct reloc_control *rc,
1155                               struct btrfs_root *src,
1156                               struct btrfs_root *dest)
1157 {
1158         struct btrfs_root *reloc_root = src->reloc_root;
1159         struct backref_cache *cache = &rc->backref_cache;
1160         struct backref_node *node = NULL;
1161         struct backref_node *new_node;
1162         struct backref_edge *edge;
1163         struct backref_edge *new_edge;
1164         struct rb_node *rb_node;
1165
1166         if (cache->last_trans > 0)
1167                 update_backref_cache(trans, cache);
1168
1169         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1170         if (rb_node) {
1171                 node = rb_entry(rb_node, struct backref_node, rb_node);
1172                 if (node->detached)
1173                         node = NULL;
1174                 else
1175                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1176         }
1177
1178         if (!node) {
1179                 rb_node = tree_search(&cache->rb_root,
1180                                       reloc_root->commit_root->start);
1181                 if (rb_node) {
1182                         node = rb_entry(rb_node, struct backref_node,
1183                                         rb_node);
1184                         BUG_ON(node->detached);
1185                 }
1186         }
1187
1188         if (!node)
1189                 return 0;
1190
1191         new_node = alloc_backref_node(cache);
1192         if (!new_node)
1193                 return -ENOMEM;
1194
1195         new_node->bytenr = dest->node->start;
1196         new_node->level = node->level;
1197         new_node->lowest = node->lowest;
1198         new_node->checked = 1;
1199         new_node->root = dest;
1200
1201         if (!node->lowest) {
1202                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1203                         new_edge = alloc_backref_edge(cache);
1204                         if (!new_edge)
1205                                 goto fail;
1206
1207                         new_edge->node[UPPER] = new_node;
1208                         new_edge->node[LOWER] = edge->node[LOWER];
1209                         list_add_tail(&new_edge->list[UPPER],
1210                                       &new_node->lower);
1211                 }
1212         } else {
1213                 list_add_tail(&new_node->lower, &cache->leaves);
1214         }
1215
1216         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1217                               &new_node->rb_node);
1218         if (rb_node)
1219                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1220
1221         if (!new_node->lowest) {
1222                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1223                         list_add_tail(&new_edge->list[LOWER],
1224                                       &new_edge->node[LOWER]->upper);
1225                 }
1226         }
1227         return 0;
1228 fail:
1229         while (!list_empty(&new_node->lower)) {
1230                 new_edge = list_entry(new_node->lower.next,
1231                                       struct backref_edge, list[UPPER]);
1232                 list_del(&new_edge->list[UPPER]);
1233                 free_backref_edge(cache, new_edge);
1234         }
1235         free_backref_node(cache, new_node);
1236         return -ENOMEM;
1237 }
1238
1239 /*
1240  * helper to add 'address of tree root -> reloc tree' mapping
1241  */
1242 static int __must_check __add_reloc_root(struct btrfs_root *root)
1243 {
1244         struct rb_node *rb_node;
1245         struct mapping_node *node;
1246         struct reloc_control *rc = root->fs_info->reloc_ctl;
1247
1248         node = kmalloc(sizeof(*node), GFP_NOFS);
1249         if (!node)
1250                 return -ENOMEM;
1251
1252         node->bytenr = root->node->start;
1253         node->data = root;
1254
1255         spin_lock(&rc->reloc_root_tree.lock);
1256         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1257                               node->bytenr, &node->rb_node);
1258         spin_unlock(&rc->reloc_root_tree.lock);
1259         if (rb_node) {
1260                 btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
1261                             "for start=%llu while inserting into relocation "
1262                             "tree", node->bytenr);
1263                 kfree(node);
1264                 return -EEXIST;
1265         }
1266
1267         list_add_tail(&root->root_list, &rc->reloc_roots);
1268         return 0;
1269 }
1270
1271 /*
1272  * helper to delete the 'address of tree root -> reloc tree'
1273  * mapping
1274  */
1275 static void __del_reloc_root(struct btrfs_root *root)
1276 {
1277         struct rb_node *rb_node;
1278         struct mapping_node *node = NULL;
1279         struct reloc_control *rc = root->fs_info->reloc_ctl;
1280
1281         spin_lock(&rc->reloc_root_tree.lock);
1282         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1283                               root->node->start);
1284         if (rb_node) {
1285                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1286                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1287         }
1288         spin_unlock(&rc->reloc_root_tree.lock);
1289
1290         if (!node)
1291                 return;
1292         BUG_ON((struct btrfs_root *)node->data != root);
1293
1294         spin_lock(&root->fs_info->trans_lock);
1295         list_del_init(&root->root_list);
1296         spin_unlock(&root->fs_info->trans_lock);
1297         kfree(node);
1298 }
1299
1300 /*
1301  * helper to update the 'address of tree root -> reloc tree'
1302  * mapping
1303  */
1304 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1305 {
1306         struct rb_node *rb_node;
1307         struct mapping_node *node = NULL;
1308         struct reloc_control *rc = root->fs_info->reloc_ctl;
1309
1310         spin_lock(&rc->reloc_root_tree.lock);
1311         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1312                               root->node->start);
1313         if (rb_node) {
1314                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1315                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1316         }
1317         spin_unlock(&rc->reloc_root_tree.lock);
1318
1319         if (!node)
1320                 return 0;
1321         BUG_ON((struct btrfs_root *)node->data != root);
1322
1323         spin_lock(&rc->reloc_root_tree.lock);
1324         node->bytenr = new_bytenr;
1325         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1326                               node->bytenr, &node->rb_node);
1327         spin_unlock(&rc->reloc_root_tree.lock);
1328         if (rb_node)
1329                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1330         return 0;
1331 }
1332
1333 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1334                                         struct btrfs_root *root, u64 objectid)
1335 {
1336         struct btrfs_root *reloc_root;
1337         struct extent_buffer *eb;
1338         struct btrfs_root_item *root_item;
1339         struct btrfs_key root_key;
1340         u64 last_snap = 0;
1341         int ret;
1342
1343         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1344         BUG_ON(!root_item);
1345
1346         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1347         root_key.type = BTRFS_ROOT_ITEM_KEY;
1348         root_key.offset = objectid;
1349
1350         if (root->root_key.objectid == objectid) {
1351                 /* called by btrfs_init_reloc_root */
1352                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1353                                       BTRFS_TREE_RELOC_OBJECTID);
1354                 BUG_ON(ret);
1355
1356                 last_snap = btrfs_root_last_snapshot(&root->root_item);
1357                 btrfs_set_root_last_snapshot(&root->root_item,
1358                                              trans->transid - 1);
1359         } else {
1360                 /*
1361                  * called by btrfs_reloc_post_snapshot_hook.
1362                  * the source tree is a reloc tree, all tree blocks
1363                  * modified after it was created have RELOC flag
1364                  * set in their headers. so it's OK to not update
1365                  * the 'last_snapshot'.
1366                  */
1367                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1368                                       BTRFS_TREE_RELOC_OBJECTID);
1369                 BUG_ON(ret);
1370         }
1371
1372         memcpy(root_item, &root->root_item, sizeof(*root_item));
1373         btrfs_set_root_bytenr(root_item, eb->start);
1374         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1375         btrfs_set_root_generation(root_item, trans->transid);
1376
1377         if (root->root_key.objectid == objectid) {
1378                 btrfs_set_root_refs(root_item, 0);
1379                 memset(&root_item->drop_progress, 0,
1380                        sizeof(struct btrfs_disk_key));
1381                 root_item->drop_level = 0;
1382                 /*
1383                  * abuse rtransid, it is safe because it is impossible to
1384                  * receive data into a relocation tree.
1385                  */
1386                 btrfs_set_root_rtransid(root_item, last_snap);
1387                 btrfs_set_root_otransid(root_item, trans->transid);
1388         }
1389
1390         btrfs_tree_unlock(eb);
1391         free_extent_buffer(eb);
1392
1393         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
1394                                 &root_key, root_item);
1395         BUG_ON(ret);
1396         kfree(root_item);
1397
1398         reloc_root = btrfs_read_fs_root(root->fs_info->tree_root, &root_key);
1399         BUG_ON(IS_ERR(reloc_root));
1400         reloc_root->last_trans = trans->transid;
1401         return reloc_root;
1402 }
1403
1404 /*
1405  * create reloc tree for a given fs tree. reloc tree is just a
1406  * snapshot of the fs tree with special root objectid.
1407  */
1408 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1409                           struct btrfs_root *root)
1410 {
1411         struct btrfs_root *reloc_root;
1412         struct reloc_control *rc = root->fs_info->reloc_ctl;
1413         struct btrfs_block_rsv *rsv;
1414         int clear_rsv = 0;
1415         int ret;
1416
1417         if (root->reloc_root) {
1418                 reloc_root = root->reloc_root;
1419                 reloc_root->last_trans = trans->transid;
1420                 return 0;
1421         }
1422
1423         if (!rc || !rc->create_reloc_tree ||
1424             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1425                 return 0;
1426
1427         if (!trans->reloc_reserved) {
1428                 rsv = trans->block_rsv;
1429                 trans->block_rsv = rc->block_rsv;
1430                 clear_rsv = 1;
1431         }
1432         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1433         if (clear_rsv)
1434                 trans->block_rsv = rsv;
1435
1436         ret = __add_reloc_root(reloc_root);
1437         BUG_ON(ret < 0);
1438         root->reloc_root = reloc_root;
1439         return 0;
1440 }
1441
1442 /*
1443  * update root item of reloc tree
1444  */
1445 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1446                             struct btrfs_root *root)
1447 {
1448         struct btrfs_root *reloc_root;
1449         struct btrfs_root_item *root_item;
1450         int ret;
1451
1452         if (!root->reloc_root)
1453                 goto out;
1454
1455         reloc_root = root->reloc_root;
1456         root_item = &reloc_root->root_item;
1457
1458         if (root->fs_info->reloc_ctl->merge_reloc_tree &&
1459             btrfs_root_refs(root_item) == 0) {
1460                 root->reloc_root = NULL;
1461                 __del_reloc_root(reloc_root);
1462         }
1463
1464         if (reloc_root->commit_root != reloc_root->node) {
1465                 btrfs_set_root_node(root_item, reloc_root->node);
1466                 free_extent_buffer(reloc_root->commit_root);
1467                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1468         }
1469
1470         ret = btrfs_update_root(trans, root->fs_info->tree_root,
1471                                 &reloc_root->root_key, root_item);
1472         BUG_ON(ret);
1473
1474 out:
1475         return 0;
1476 }
1477
1478 /*
1479  * helper to find first cached inode with inode number >= objectid
1480  * in a subvolume
1481  */
1482 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1483 {
1484         struct rb_node *node;
1485         struct rb_node *prev;
1486         struct btrfs_inode *entry;
1487         struct inode *inode;
1488
1489         spin_lock(&root->inode_lock);
1490 again:
1491         node = root->inode_tree.rb_node;
1492         prev = NULL;
1493         while (node) {
1494                 prev = node;
1495                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1496
1497                 if (objectid < btrfs_ino(&entry->vfs_inode))
1498                         node = node->rb_left;
1499                 else if (objectid > btrfs_ino(&entry->vfs_inode))
1500                         node = node->rb_right;
1501                 else
1502                         break;
1503         }
1504         if (!node) {
1505                 while (prev) {
1506                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1507                         if (objectid <= btrfs_ino(&entry->vfs_inode)) {
1508                                 node = prev;
1509                                 break;
1510                         }
1511                         prev = rb_next(prev);
1512                 }
1513         }
1514         while (node) {
1515                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1516                 inode = igrab(&entry->vfs_inode);
1517                 if (inode) {
1518                         spin_unlock(&root->inode_lock);
1519                         return inode;
1520                 }
1521
1522                 objectid = btrfs_ino(&entry->vfs_inode) + 1;
1523                 if (cond_resched_lock(&root->inode_lock))
1524                         goto again;
1525
1526                 node = rb_next(node);
1527         }
1528         spin_unlock(&root->inode_lock);
1529         return NULL;
1530 }
1531
1532 static int in_block_group(u64 bytenr,
1533                           struct btrfs_block_group_cache *block_group)
1534 {
1535         if (bytenr >= block_group->key.objectid &&
1536             bytenr < block_group->key.objectid + block_group->key.offset)
1537                 return 1;
1538         return 0;
1539 }
1540
1541 /*
1542  * get new location of data
1543  */
1544 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1545                             u64 bytenr, u64 num_bytes)
1546 {
1547         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1548         struct btrfs_path *path;
1549         struct btrfs_file_extent_item *fi;
1550         struct extent_buffer *leaf;
1551         int ret;
1552
1553         path = btrfs_alloc_path();
1554         if (!path)
1555                 return -ENOMEM;
1556
1557         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1558         ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(reloc_inode),
1559                                        bytenr, 0);
1560         if (ret < 0)
1561                 goto out;
1562         if (ret > 0) {
1563                 ret = -ENOENT;
1564                 goto out;
1565         }
1566
1567         leaf = path->nodes[0];
1568         fi = btrfs_item_ptr(leaf, path->slots[0],
1569                             struct btrfs_file_extent_item);
1570
1571         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1572                btrfs_file_extent_compression(leaf, fi) ||
1573                btrfs_file_extent_encryption(leaf, fi) ||
1574                btrfs_file_extent_other_encoding(leaf, fi));
1575
1576         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1577                 ret = -EINVAL;
1578                 goto out;
1579         }
1580
1581         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1582         ret = 0;
1583 out:
1584         btrfs_free_path(path);
1585         return ret;
1586 }
1587
1588 /*
1589  * update file extent items in the tree leaf to point to
1590  * the new locations.
1591  */
1592 static noinline_for_stack
1593 int replace_file_extents(struct btrfs_trans_handle *trans,
1594                          struct reloc_control *rc,
1595                          struct btrfs_root *root,
1596                          struct extent_buffer *leaf)
1597 {
1598         struct btrfs_key key;
1599         struct btrfs_file_extent_item *fi;
1600         struct inode *inode = NULL;
1601         u64 parent;
1602         u64 bytenr;
1603         u64 new_bytenr = 0;
1604         u64 num_bytes;
1605         u64 end;
1606         u32 nritems;
1607         u32 i;
1608         int ret = 0;
1609         int first = 1;
1610         int dirty = 0;
1611
1612         if (rc->stage != UPDATE_DATA_PTRS)
1613                 return 0;
1614
1615         /* reloc trees always use full backref */
1616         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1617                 parent = leaf->start;
1618         else
1619                 parent = 0;
1620
1621         nritems = btrfs_header_nritems(leaf);
1622         for (i = 0; i < nritems; i++) {
1623                 cond_resched();
1624                 btrfs_item_key_to_cpu(leaf, &key, i);
1625                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1626                         continue;
1627                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1628                 if (btrfs_file_extent_type(leaf, fi) ==
1629                     BTRFS_FILE_EXTENT_INLINE)
1630                         continue;
1631                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1632                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1633                 if (bytenr == 0)
1634                         continue;
1635                 if (!in_block_group(bytenr, rc->block_group))
1636                         continue;
1637
1638                 /*
1639                  * if we are modifying block in fs tree, wait for readpage
1640                  * to complete and drop the extent cache
1641                  */
1642                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1643                         if (first) {
1644                                 inode = find_next_inode(root, key.objectid);
1645                                 first = 0;
1646                         } else if (inode && btrfs_ino(inode) < key.objectid) {
1647                                 btrfs_add_delayed_iput(inode);
1648                                 inode = find_next_inode(root, key.objectid);
1649                         }
1650                         if (inode && btrfs_ino(inode) == key.objectid) {
1651                                 end = key.offset +
1652                                       btrfs_file_extent_num_bytes(leaf, fi);
1653                                 WARN_ON(!IS_ALIGNED(key.offset,
1654                                                     root->sectorsize));
1655                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1656                                 end--;
1657                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1658                                                       key.offset, end);
1659                                 if (!ret)
1660                                         continue;
1661
1662                                 btrfs_drop_extent_cache(inode, key.offset, end,
1663                                                         1);
1664                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1665                                               key.offset, end);
1666                         }
1667                 }
1668
1669                 ret = get_new_location(rc->data_inode, &new_bytenr,
1670                                        bytenr, num_bytes);
1671                 if (ret) {
1672                         /*
1673                          * Don't have to abort since we've not changed anything
1674                          * in the file extent yet.
1675                          */
1676                         break;
1677                 }
1678
1679                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1680                 dirty = 1;
1681
1682                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1683                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1684                                            num_bytes, parent,
1685                                            btrfs_header_owner(leaf),
1686                                            key.objectid, key.offset, 1);
1687                 if (ret) {
1688                         btrfs_abort_transaction(trans, root, ret);
1689                         break;
1690                 }
1691
1692                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1693                                         parent, btrfs_header_owner(leaf),
1694                                         key.objectid, key.offset, 1);
1695                 if (ret) {
1696                         btrfs_abort_transaction(trans, root, ret);
1697                         break;
1698                 }
1699         }
1700         if (dirty)
1701                 btrfs_mark_buffer_dirty(leaf);
1702         if (inode)
1703                 btrfs_add_delayed_iput(inode);
1704         return ret;
1705 }
1706
1707 static noinline_for_stack
1708 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1709                      struct btrfs_path *path, int level)
1710 {
1711         struct btrfs_disk_key key1;
1712         struct btrfs_disk_key key2;
1713         btrfs_node_key(eb, &key1, slot);
1714         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1715         return memcmp(&key1, &key2, sizeof(key1));
1716 }
1717
1718 /*
1719  * try to replace tree blocks in fs tree with the new blocks
1720  * in reloc tree. tree blocks haven't been modified since the
1721  * reloc tree was create can be replaced.
1722  *
1723  * if a block was replaced, level of the block + 1 is returned.
1724  * if no block got replaced, 0 is returned. if there are other
1725  * errors, a negative error number is returned.
1726  */
1727 static noinline_for_stack
1728 int replace_path(struct btrfs_trans_handle *trans,
1729                  struct btrfs_root *dest, struct btrfs_root *src,
1730                  struct btrfs_path *path, struct btrfs_key *next_key,
1731                  int lowest_level, int max_level)
1732 {
1733         struct extent_buffer *eb;
1734         struct extent_buffer *parent;
1735         struct btrfs_key key;
1736         u64 old_bytenr;
1737         u64 new_bytenr;
1738         u64 old_ptr_gen;
1739         u64 new_ptr_gen;
1740         u64 last_snapshot;
1741         u32 blocksize;
1742         int cow = 0;
1743         int level;
1744         int ret;
1745         int slot;
1746
1747         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1748         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1749
1750         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1751 again:
1752         slot = path->slots[lowest_level];
1753         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1754
1755         eb = btrfs_lock_root_node(dest);
1756         btrfs_set_lock_blocking(eb);
1757         level = btrfs_header_level(eb);
1758
1759         if (level < lowest_level) {
1760                 btrfs_tree_unlock(eb);
1761                 free_extent_buffer(eb);
1762                 return 0;
1763         }
1764
1765         if (cow) {
1766                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1767                 BUG_ON(ret);
1768         }
1769         btrfs_set_lock_blocking(eb);
1770
1771         if (next_key) {
1772                 next_key->objectid = (u64)-1;
1773                 next_key->type = (u8)-1;
1774                 next_key->offset = (u64)-1;
1775         }
1776
1777         parent = eb;
1778         while (1) {
1779                 level = btrfs_header_level(parent);
1780                 BUG_ON(level < lowest_level);
1781
1782                 ret = btrfs_bin_search(parent, &key, level, &slot);
1783                 if (ret && slot > 0)
1784                         slot--;
1785
1786                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1787                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1788
1789                 old_bytenr = btrfs_node_blockptr(parent, slot);
1790                 blocksize = btrfs_level_size(dest, level - 1);
1791                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1792
1793                 if (level <= max_level) {
1794                         eb = path->nodes[level];
1795                         new_bytenr = btrfs_node_blockptr(eb,
1796                                                         path->slots[level]);
1797                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1798                                                         path->slots[level]);
1799                 } else {
1800                         new_bytenr = 0;
1801                         new_ptr_gen = 0;
1802                 }
1803
1804                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1805                         ret = level;
1806                         break;
1807                 }
1808
1809                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1810                     memcmp_node_keys(parent, slot, path, level)) {
1811                         if (level <= lowest_level) {
1812                                 ret = 0;
1813                                 break;
1814                         }
1815
1816                         eb = read_tree_block(dest, old_bytenr, blocksize,
1817                                              old_ptr_gen);
1818                         if (!eb || !extent_buffer_uptodate(eb)) {
1819                                 ret = (!eb) ? -ENOMEM : -EIO;
1820                                 free_extent_buffer(eb);
1821                                 break;
1822                         }
1823                         btrfs_tree_lock(eb);
1824                         if (cow) {
1825                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1826                                                       slot, &eb);
1827                                 BUG_ON(ret);
1828                         }
1829                         btrfs_set_lock_blocking(eb);
1830
1831                         btrfs_tree_unlock(parent);
1832                         free_extent_buffer(parent);
1833
1834                         parent = eb;
1835                         continue;
1836                 }
1837
1838                 if (!cow) {
1839                         btrfs_tree_unlock(parent);
1840                         free_extent_buffer(parent);
1841                         cow = 1;
1842                         goto again;
1843                 }
1844
1845                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1846                                       path->slots[level]);
1847                 btrfs_release_path(path);
1848
1849                 path->lowest_level = level;
1850                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1851                 path->lowest_level = 0;
1852                 BUG_ON(ret);
1853
1854                 /*
1855                  * swap blocks in fs tree and reloc tree.
1856                  */
1857                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1858                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1859                 btrfs_mark_buffer_dirty(parent);
1860
1861                 btrfs_set_node_blockptr(path->nodes[level],
1862                                         path->slots[level], old_bytenr);
1863                 btrfs_set_node_ptr_generation(path->nodes[level],
1864                                               path->slots[level], old_ptr_gen);
1865                 btrfs_mark_buffer_dirty(path->nodes[level]);
1866
1867                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1868                                         path->nodes[level]->start,
1869                                         src->root_key.objectid, level - 1, 0,
1870                                         1);
1871                 BUG_ON(ret);
1872                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1873                                         0, dest->root_key.objectid, level - 1,
1874                                         0, 1);
1875                 BUG_ON(ret);
1876
1877                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1878                                         path->nodes[level]->start,
1879                                         src->root_key.objectid, level - 1, 0,
1880                                         1);
1881                 BUG_ON(ret);
1882
1883                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1884                                         0, dest->root_key.objectid, level - 1,
1885                                         0, 1);
1886                 BUG_ON(ret);
1887
1888                 btrfs_unlock_up_safe(path, 0);
1889
1890                 ret = level;
1891                 break;
1892         }
1893         btrfs_tree_unlock(parent);
1894         free_extent_buffer(parent);
1895         return ret;
1896 }
1897
1898 /*
1899  * helper to find next relocated block in reloc tree
1900  */
1901 static noinline_for_stack
1902 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1903                        int *level)
1904 {
1905         struct extent_buffer *eb;
1906         int i;
1907         u64 last_snapshot;
1908         u32 nritems;
1909
1910         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1911
1912         for (i = 0; i < *level; i++) {
1913                 free_extent_buffer(path->nodes[i]);
1914                 path->nodes[i] = NULL;
1915         }
1916
1917         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1918                 eb = path->nodes[i];
1919                 nritems = btrfs_header_nritems(eb);
1920                 while (path->slots[i] + 1 < nritems) {
1921                         path->slots[i]++;
1922                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1923                             last_snapshot)
1924                                 continue;
1925
1926                         *level = i;
1927                         return 0;
1928                 }
1929                 free_extent_buffer(path->nodes[i]);
1930                 path->nodes[i] = NULL;
1931         }
1932         return 1;
1933 }
1934
1935 /*
1936  * walk down reloc tree to find relocated block of lowest level
1937  */
1938 static noinline_for_stack
1939 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1940                          int *level)
1941 {
1942         struct extent_buffer *eb = NULL;
1943         int i;
1944         u64 bytenr;
1945         u64 ptr_gen = 0;
1946         u64 last_snapshot;
1947         u32 blocksize;
1948         u32 nritems;
1949
1950         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1951
1952         for (i = *level; i > 0; i--) {
1953                 eb = path->nodes[i];
1954                 nritems = btrfs_header_nritems(eb);
1955                 while (path->slots[i] < nritems) {
1956                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1957                         if (ptr_gen > last_snapshot)
1958                                 break;
1959                         path->slots[i]++;
1960                 }
1961                 if (path->slots[i] >= nritems) {
1962                         if (i == *level)
1963                                 break;
1964                         *level = i + 1;
1965                         return 0;
1966                 }
1967                 if (i == 1) {
1968                         *level = i;
1969                         return 0;
1970                 }
1971
1972                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1973                 blocksize = btrfs_level_size(root, i - 1);
1974                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1975                 if (!eb || !extent_buffer_uptodate(eb)) {
1976                         free_extent_buffer(eb);
1977                         return -EIO;
1978                 }
1979                 BUG_ON(btrfs_header_level(eb) != i - 1);
1980                 path->nodes[i - 1] = eb;
1981                 path->slots[i - 1] = 0;
1982         }
1983         return 1;
1984 }
1985
1986 /*
1987  * invalidate extent cache for file extents whose key in range of
1988  * [min_key, max_key)
1989  */
1990 static int invalidate_extent_cache(struct btrfs_root *root,
1991                                    struct btrfs_key *min_key,
1992                                    struct btrfs_key *max_key)
1993 {
1994         struct inode *inode = NULL;
1995         u64 objectid;
1996         u64 start, end;
1997         u64 ino;
1998
1999         objectid = min_key->objectid;
2000         while (1) {
2001                 cond_resched();
2002                 iput(inode);
2003
2004                 if (objectid > max_key->objectid)
2005                         break;
2006
2007                 inode = find_next_inode(root, objectid);
2008                 if (!inode)
2009                         break;
2010                 ino = btrfs_ino(inode);
2011
2012                 if (ino > max_key->objectid) {
2013                         iput(inode);
2014                         break;
2015                 }
2016
2017                 objectid = ino + 1;
2018                 if (!S_ISREG(inode->i_mode))
2019                         continue;
2020
2021                 if (unlikely(min_key->objectid == ino)) {
2022                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2023                                 continue;
2024                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2025                                 start = 0;
2026                         else {
2027                                 start = min_key->offset;
2028                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
2029                         }
2030                 } else {
2031                         start = 0;
2032                 }
2033
2034                 if (unlikely(max_key->objectid == ino)) {
2035                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2036                                 continue;
2037                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2038                                 end = (u64)-1;
2039                         } else {
2040                                 if (max_key->offset == 0)
2041                                         continue;
2042                                 end = max_key->offset;
2043                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
2044                                 end--;
2045                         }
2046                 } else {
2047                         end = (u64)-1;
2048                 }
2049
2050                 /* the lock_extent waits for readpage to complete */
2051                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2052                 btrfs_drop_extent_cache(inode, start, end, 1);
2053                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2054         }
2055         return 0;
2056 }
2057
2058 static int find_next_key(struct btrfs_path *path, int level,
2059                          struct btrfs_key *key)
2060
2061 {
2062         while (level < BTRFS_MAX_LEVEL) {
2063                 if (!path->nodes[level])
2064                         break;
2065                 if (path->slots[level] + 1 <
2066                     btrfs_header_nritems(path->nodes[level])) {
2067                         btrfs_node_key_to_cpu(path->nodes[level], key,
2068                                               path->slots[level] + 1);
2069                         return 0;
2070                 }
2071                 level++;
2072         }
2073         return 1;
2074 }
2075
2076 /*
2077  * merge the relocated tree blocks in reloc tree with corresponding
2078  * fs tree.
2079  */
2080 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2081                                                struct btrfs_root *root)
2082 {
2083         LIST_HEAD(inode_list);
2084         struct btrfs_key key;
2085         struct btrfs_key next_key;
2086         struct btrfs_trans_handle *trans = NULL;
2087         struct btrfs_root *reloc_root;
2088         struct btrfs_root_item *root_item;
2089         struct btrfs_path *path;
2090         struct extent_buffer *leaf;
2091         int level;
2092         int max_level;
2093         int replaced = 0;
2094         int ret;
2095         int err = 0;
2096         u32 min_reserved;
2097
2098         path = btrfs_alloc_path();
2099         if (!path)
2100                 return -ENOMEM;
2101         path->reada = 1;
2102
2103         reloc_root = root->reloc_root;
2104         root_item = &reloc_root->root_item;
2105
2106         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2107                 level = btrfs_root_level(root_item);
2108                 extent_buffer_get(reloc_root->node);
2109                 path->nodes[level] = reloc_root->node;
2110                 path->slots[level] = 0;
2111         } else {
2112                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2113
2114                 level = root_item->drop_level;
2115                 BUG_ON(level == 0);
2116                 path->lowest_level = level;
2117                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2118                 path->lowest_level = 0;
2119                 if (ret < 0) {
2120                         btrfs_free_path(path);
2121                         return ret;
2122                 }
2123
2124                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2125                                       path->slots[level]);
2126                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2127
2128                 btrfs_unlock_up_safe(path, 0);
2129         }
2130
2131         min_reserved = root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2132         memset(&next_key, 0, sizeof(next_key));
2133
2134         while (1) {
2135                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2136                                              BTRFS_RESERVE_FLUSH_ALL);
2137                 if (ret) {
2138                         err = ret;
2139                         goto out;
2140                 }
2141                 trans = btrfs_start_transaction(root, 0);
2142                 if (IS_ERR(trans)) {
2143                         err = PTR_ERR(trans);
2144                         trans = NULL;
2145                         goto out;
2146                 }
2147                 trans->block_rsv = rc->block_rsv;
2148
2149                 replaced = 0;
2150                 max_level = level;
2151
2152                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2153                 if (ret < 0) {
2154                         err = ret;
2155                         goto out;
2156                 }
2157                 if (ret > 0)
2158                         break;
2159
2160                 if (!find_next_key(path, level, &key) &&
2161                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2162                         ret = 0;
2163                 } else {
2164                         ret = replace_path(trans, root, reloc_root, path,
2165                                            &next_key, level, max_level);
2166                 }
2167                 if (ret < 0) {
2168                         err = ret;
2169                         goto out;
2170                 }
2171
2172                 if (ret > 0) {
2173                         level = ret;
2174                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2175                                               path->slots[level]);
2176                         replaced = 1;
2177                 }
2178
2179                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2180                 if (ret > 0)
2181                         break;
2182
2183                 BUG_ON(level == 0);
2184                 /*
2185                  * save the merging progress in the drop_progress.
2186                  * this is OK since root refs == 1 in this case.
2187                  */
2188                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2189                                path->slots[level]);
2190                 root_item->drop_level = level;
2191
2192                 btrfs_end_transaction_throttle(trans, root);
2193                 trans = NULL;
2194
2195                 btrfs_btree_balance_dirty(root);
2196
2197                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2198                         invalidate_extent_cache(root, &key, &next_key);
2199         }
2200
2201         /*
2202          * handle the case only one block in the fs tree need to be
2203          * relocated and the block is tree root.
2204          */
2205         leaf = btrfs_lock_root_node(root);
2206         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2207         btrfs_tree_unlock(leaf);
2208         free_extent_buffer(leaf);
2209         if (ret < 0)
2210                 err = ret;
2211 out:
2212         btrfs_free_path(path);
2213
2214         if (err == 0) {
2215                 memset(&root_item->drop_progress, 0,
2216                        sizeof(root_item->drop_progress));
2217                 root_item->drop_level = 0;
2218                 btrfs_set_root_refs(root_item, 0);
2219                 btrfs_update_reloc_root(trans, root);
2220         }
2221
2222         if (trans)
2223                 btrfs_end_transaction_throttle(trans, root);
2224
2225         btrfs_btree_balance_dirty(root);
2226
2227         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2228                 invalidate_extent_cache(root, &key, &next_key);
2229
2230         return err;
2231 }
2232
2233 static noinline_for_stack
2234 int prepare_to_merge(struct reloc_control *rc, int err)
2235 {
2236         struct btrfs_root *root = rc->extent_root;
2237         struct btrfs_root *reloc_root;
2238         struct btrfs_trans_handle *trans;
2239         LIST_HEAD(reloc_roots);
2240         u64 num_bytes = 0;
2241         int ret;
2242
2243         mutex_lock(&root->fs_info->reloc_mutex);
2244         rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2245         rc->merging_rsv_size += rc->nodes_relocated * 2;
2246         mutex_unlock(&root->fs_info->reloc_mutex);
2247
2248 again:
2249         if (!err) {
2250                 num_bytes = rc->merging_rsv_size;
2251                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2252                                           BTRFS_RESERVE_FLUSH_ALL);
2253                 if (ret)
2254                         err = ret;
2255         }
2256
2257         trans = btrfs_join_transaction(rc->extent_root);
2258         if (IS_ERR(trans)) {
2259                 if (!err)
2260                         btrfs_block_rsv_release(rc->extent_root,
2261                                                 rc->block_rsv, num_bytes);
2262                 return PTR_ERR(trans);
2263         }
2264
2265         if (!err) {
2266                 if (num_bytes != rc->merging_rsv_size) {
2267                         btrfs_end_transaction(trans, rc->extent_root);
2268                         btrfs_block_rsv_release(rc->extent_root,
2269                                                 rc->block_rsv, num_bytes);
2270                         goto again;
2271                 }
2272         }
2273
2274         rc->merge_reloc_tree = 1;
2275
2276         while (!list_empty(&rc->reloc_roots)) {
2277                 reloc_root = list_entry(rc->reloc_roots.next,
2278                                         struct btrfs_root, root_list);
2279                 list_del_init(&reloc_root->root_list);
2280
2281                 root = read_fs_root(reloc_root->fs_info,
2282                                     reloc_root->root_key.offset);
2283                 BUG_ON(IS_ERR(root));
2284                 BUG_ON(root->reloc_root != reloc_root);
2285
2286                 /*
2287                  * set reference count to 1, so btrfs_recover_relocation
2288                  * knows it should resumes merging
2289                  */
2290                 if (!err)
2291                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2292                 btrfs_update_reloc_root(trans, root);
2293
2294                 list_add(&reloc_root->root_list, &reloc_roots);
2295         }
2296
2297         list_splice(&reloc_roots, &rc->reloc_roots);
2298
2299         if (!err)
2300                 btrfs_commit_transaction(trans, rc->extent_root);
2301         else
2302                 btrfs_end_transaction(trans, rc->extent_root);
2303         return err;
2304 }
2305
2306 static noinline_for_stack
2307 void free_reloc_roots(struct list_head *list)
2308 {
2309         struct btrfs_root *reloc_root;
2310
2311         while (!list_empty(list)) {
2312                 reloc_root = list_entry(list->next, struct btrfs_root,
2313                                         root_list);
2314                 __del_reloc_root(reloc_root);
2315         }
2316 }
2317
2318 static noinline_for_stack
2319 int merge_reloc_roots(struct reloc_control *rc)
2320 {
2321         struct btrfs_root *root;
2322         struct btrfs_root *reloc_root;
2323         u64 last_snap;
2324         u64 otransid;
2325         u64 objectid;
2326         LIST_HEAD(reloc_roots);
2327         int found = 0;
2328         int ret = 0;
2329 again:
2330         root = rc->extent_root;
2331
2332         /*
2333          * this serializes us with btrfs_record_root_in_transaction,
2334          * we have to make sure nobody is in the middle of
2335          * adding their roots to the list while we are
2336          * doing this splice
2337          */
2338         mutex_lock(&root->fs_info->reloc_mutex);
2339         list_splice_init(&rc->reloc_roots, &reloc_roots);
2340         mutex_unlock(&root->fs_info->reloc_mutex);
2341
2342         while (!list_empty(&reloc_roots)) {
2343                 found = 1;
2344                 reloc_root = list_entry(reloc_roots.next,
2345                                         struct btrfs_root, root_list);
2346
2347                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2348                         root = read_fs_root(reloc_root->fs_info,
2349                                             reloc_root->root_key.offset);
2350                         BUG_ON(IS_ERR(root));
2351                         BUG_ON(root->reloc_root != reloc_root);
2352
2353                         ret = merge_reloc_root(rc, root);
2354                         if (ret) {
2355                                 if (list_empty(&reloc_root->root_list))
2356                                         list_add_tail(&reloc_root->root_list,
2357                                                       &reloc_roots);
2358                                 goto out;
2359                         }
2360                 } else {
2361                         list_del_init(&reloc_root->root_list);
2362                 }
2363
2364                 /*
2365                  * we keep the old last snapshod transid in rtranid when we
2366                  * created the relocation tree.
2367                  */
2368                 last_snap = btrfs_root_rtransid(&reloc_root->root_item);
2369                 otransid = btrfs_root_otransid(&reloc_root->root_item);
2370                 objectid = reloc_root->root_key.offset;
2371
2372                 ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
2373                 if (ret < 0) {
2374                         if (list_empty(&reloc_root->root_list))
2375                                 list_add_tail(&reloc_root->root_list,
2376                                               &reloc_roots);
2377                         goto out;
2378                 }
2379         }
2380
2381         if (found) {
2382                 found = 0;
2383                 goto again;
2384         }
2385 out:
2386         if (ret) {
2387                 btrfs_std_error(root->fs_info, ret);
2388                 if (!list_empty(&reloc_roots))
2389                         free_reloc_roots(&reloc_roots);
2390
2391                 /* new reloc root may be added */
2392                 mutex_lock(&root->fs_info->reloc_mutex);
2393                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2394                 mutex_unlock(&root->fs_info->reloc_mutex);
2395                 if (!list_empty(&reloc_roots))
2396                         free_reloc_roots(&reloc_roots);
2397         }
2398
2399         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2400         return ret;
2401 }
2402
2403 static void free_block_list(struct rb_root *blocks)
2404 {
2405         struct tree_block *block;
2406         struct rb_node *rb_node;
2407         while ((rb_node = rb_first(blocks))) {
2408                 block = rb_entry(rb_node, struct tree_block, rb_node);
2409                 rb_erase(rb_node, blocks);
2410                 kfree(block);
2411         }
2412 }
2413
2414 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2415                                       struct btrfs_root *reloc_root)
2416 {
2417         struct btrfs_root *root;
2418
2419         if (reloc_root->last_trans == trans->transid)
2420                 return 0;
2421
2422         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
2423         BUG_ON(IS_ERR(root));
2424         BUG_ON(root->reloc_root != reloc_root);
2425
2426         return btrfs_record_root_in_trans(trans, root);
2427 }
2428
2429 static noinline_for_stack
2430 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2431                                      struct reloc_control *rc,
2432                                      struct backref_node *node,
2433                                      struct backref_edge *edges[])
2434 {
2435         struct backref_node *next;
2436         struct btrfs_root *root;
2437         int index = 0;
2438
2439         next = node;
2440         while (1) {
2441                 cond_resched();
2442                 next = walk_up_backref(next, edges, &index);
2443                 root = next->root;
2444                 BUG_ON(!root);
2445                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2446
2447                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2448                         record_reloc_root_in_trans(trans, root);
2449                         break;
2450                 }
2451
2452                 btrfs_record_root_in_trans(trans, root);
2453                 root = root->reloc_root;
2454
2455                 if (next->new_bytenr != root->node->start) {
2456                         BUG_ON(next->new_bytenr);
2457                         BUG_ON(!list_empty(&next->list));
2458                         next->new_bytenr = root->node->start;
2459                         next->root = root;
2460                         list_add_tail(&next->list,
2461                                       &rc->backref_cache.changed);
2462                         __mark_block_processed(rc, next);
2463                         break;
2464                 }
2465
2466                 WARN_ON(1);
2467                 root = NULL;
2468                 next = walk_down_backref(edges, &index);
2469                 if (!next || next->level <= node->level)
2470                         break;
2471         }
2472         if (!root)
2473                 return NULL;
2474
2475         next = node;
2476         /* setup backref node path for btrfs_reloc_cow_block */
2477         while (1) {
2478                 rc->backref_cache.path[next->level] = next;
2479                 if (--index < 0)
2480                         break;
2481                 next = edges[index]->node[UPPER];
2482         }
2483         return root;
2484 }
2485
2486 /*
2487  * select a tree root for relocation. return NULL if the block
2488  * is reference counted. we should use do_relocation() in this
2489  * case. return a tree root pointer if the block isn't reference
2490  * counted. return -ENOENT if the block is root of reloc tree.
2491  */
2492 static noinline_for_stack
2493 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
2494                                    struct backref_node *node)
2495 {
2496         struct backref_node *next;
2497         struct btrfs_root *root;
2498         struct btrfs_root *fs_root = NULL;
2499         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2500         int index = 0;
2501
2502         next = node;
2503         while (1) {
2504                 cond_resched();
2505                 next = walk_up_backref(next, edges, &index);
2506                 root = next->root;
2507                 BUG_ON(!root);
2508
2509                 /* no other choice for non-references counted tree */
2510                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2511                         return root;
2512
2513                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2514                         fs_root = root;
2515
2516                 if (next != node)
2517                         return NULL;
2518
2519                 next = walk_down_backref(edges, &index);
2520                 if (!next || next->level <= node->level)
2521                         break;
2522         }
2523
2524         if (!fs_root)
2525                 return ERR_PTR(-ENOENT);
2526         return fs_root;
2527 }
2528
2529 static noinline_for_stack
2530 u64 calcu_metadata_size(struct reloc_control *rc,
2531                         struct backref_node *node, int reserve)
2532 {
2533         struct backref_node *next = node;
2534         struct backref_edge *edge;
2535         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2536         u64 num_bytes = 0;
2537         int index = 0;
2538
2539         BUG_ON(reserve && node->processed);
2540
2541         while (next) {
2542                 cond_resched();
2543                 while (1) {
2544                         if (next->processed && (reserve || next != node))
2545                                 break;
2546
2547                         num_bytes += btrfs_level_size(rc->extent_root,
2548                                                       next->level);
2549
2550                         if (list_empty(&next->upper))
2551                                 break;
2552
2553                         edge = list_entry(next->upper.next,
2554                                           struct backref_edge, list[LOWER]);
2555                         edges[index++] = edge;
2556                         next = edge->node[UPPER];
2557                 }
2558                 next = walk_down_backref(edges, &index);
2559         }
2560         return num_bytes;
2561 }
2562
2563 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2564                                   struct reloc_control *rc,
2565                                   struct backref_node *node)
2566 {
2567         struct btrfs_root *root = rc->extent_root;
2568         u64 num_bytes;
2569         int ret;
2570         u64 tmp;
2571
2572         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2573
2574         trans->block_rsv = rc->block_rsv;
2575         rc->reserved_bytes += num_bytes;
2576         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2577                                 BTRFS_RESERVE_FLUSH_ALL);
2578         if (ret) {
2579                 if (ret == -EAGAIN) {
2580                         tmp = rc->extent_root->nodesize *
2581                                 RELOCATION_RESERVED_NODES;
2582                         while (tmp <= rc->reserved_bytes)
2583                                 tmp <<= 1;
2584                         /*
2585                          * only one thread can access block_rsv at this point,
2586                          * so we don't need hold lock to protect block_rsv.
2587                          * we expand more reservation size here to allow enough
2588                          * space for relocation and we will return eailer in
2589                          * enospc case.
2590                          */
2591                         rc->block_rsv->size = tmp + rc->extent_root->nodesize *
2592                                               RELOCATION_RESERVED_NODES;
2593                 }
2594                 return ret;
2595         }
2596
2597         return 0;
2598 }
2599
2600 /*
2601  * relocate a block tree, and then update pointers in upper level
2602  * blocks that reference the block to point to the new location.
2603  *
2604  * if called by link_to_upper, the block has already been relocated.
2605  * in that case this function just updates pointers.
2606  */
2607 static int do_relocation(struct btrfs_trans_handle *trans,
2608                          struct reloc_control *rc,
2609                          struct backref_node *node,
2610                          struct btrfs_key *key,
2611                          struct btrfs_path *path, int lowest)
2612 {
2613         struct backref_node *upper;
2614         struct backref_edge *edge;
2615         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2616         struct btrfs_root *root;
2617         struct extent_buffer *eb;
2618         u32 blocksize;
2619         u64 bytenr;
2620         u64 generation;
2621         int slot;
2622         int ret;
2623         int err = 0;
2624
2625         BUG_ON(lowest && node->eb);
2626
2627         path->lowest_level = node->level + 1;
2628         rc->backref_cache.path[node->level] = node;
2629         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2630                 cond_resched();
2631
2632                 upper = edge->node[UPPER];
2633                 root = select_reloc_root(trans, rc, upper, edges);
2634                 BUG_ON(!root);
2635
2636                 if (upper->eb && !upper->locked) {
2637                         if (!lowest) {
2638                                 ret = btrfs_bin_search(upper->eb, key,
2639                                                        upper->level, &slot);
2640                                 BUG_ON(ret);
2641                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2642                                 if (node->eb->start == bytenr)
2643                                         goto next;
2644                         }
2645                         drop_node_buffer(upper);
2646                 }
2647
2648                 if (!upper->eb) {
2649                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2650                         if (ret < 0) {
2651                                 err = ret;
2652                                 break;
2653                         }
2654                         BUG_ON(ret > 0);
2655
2656                         if (!upper->eb) {
2657                                 upper->eb = path->nodes[upper->level];
2658                                 path->nodes[upper->level] = NULL;
2659                         } else {
2660                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2661                         }
2662
2663                         upper->locked = 1;
2664                         path->locks[upper->level] = 0;
2665
2666                         slot = path->slots[upper->level];
2667                         btrfs_release_path(path);
2668                 } else {
2669                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2670                                                &slot);
2671                         BUG_ON(ret);
2672                 }
2673
2674                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2675                 if (lowest) {
2676                         BUG_ON(bytenr != node->bytenr);
2677                 } else {
2678                         if (node->eb->start == bytenr)
2679                                 goto next;
2680                 }
2681
2682                 blocksize = btrfs_level_size(root, node->level);
2683                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2684                 eb = read_tree_block(root, bytenr, blocksize, generation);
2685                 if (!eb || !extent_buffer_uptodate(eb)) {
2686                         free_extent_buffer(eb);
2687                         err = -EIO;
2688                         goto next;
2689                 }
2690                 btrfs_tree_lock(eb);
2691                 btrfs_set_lock_blocking(eb);
2692
2693                 if (!node->eb) {
2694                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2695                                               slot, &eb);
2696                         btrfs_tree_unlock(eb);
2697                         free_extent_buffer(eb);
2698                         if (ret < 0) {
2699                                 err = ret;
2700                                 goto next;
2701                         }
2702                         BUG_ON(node->eb != eb);
2703                 } else {
2704                         btrfs_set_node_blockptr(upper->eb, slot,
2705                                                 node->eb->start);
2706                         btrfs_set_node_ptr_generation(upper->eb, slot,
2707                                                       trans->transid);
2708                         btrfs_mark_buffer_dirty(upper->eb);
2709
2710                         ret = btrfs_inc_extent_ref(trans, root,
2711                                                 node->eb->start, blocksize,
2712                                                 upper->eb->start,
2713                                                 btrfs_header_owner(upper->eb),
2714                                                 node->level, 0, 1);
2715                         BUG_ON(ret);
2716
2717                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2718                         BUG_ON(ret);
2719                 }
2720 next:
2721                 if (!upper->pending)
2722                         drop_node_buffer(upper);
2723                 else
2724                         unlock_node_buffer(upper);
2725                 if (err)
2726                         break;
2727         }
2728
2729         if (!err && node->pending) {
2730                 drop_node_buffer(node);
2731                 list_move_tail(&node->list, &rc->backref_cache.changed);
2732                 node->pending = 0;
2733         }
2734
2735         path->lowest_level = 0;
2736         BUG_ON(err == -ENOSPC);
2737         return err;
2738 }
2739
2740 static int link_to_upper(struct btrfs_trans_handle *trans,
2741                          struct reloc_control *rc,
2742                          struct backref_node *node,
2743                          struct btrfs_path *path)
2744 {
2745         struct btrfs_key key;
2746
2747         btrfs_node_key_to_cpu(node->eb, &key, 0);
2748         return do_relocation(trans, rc, node, &key, path, 0);
2749 }
2750
2751 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2752                                 struct reloc_control *rc,
2753                                 struct btrfs_path *path, int err)
2754 {
2755         LIST_HEAD(list);
2756         struct backref_cache *cache = &rc->backref_cache;
2757         struct backref_node *node;
2758         int level;
2759         int ret;
2760
2761         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2762                 while (!list_empty(&cache->pending[level])) {
2763                         node = list_entry(cache->pending[level].next,
2764                                           struct backref_node, list);
2765                         list_move_tail(&node->list, &list);
2766                         BUG_ON(!node->pending);
2767
2768                         if (!err) {
2769                                 ret = link_to_upper(trans, rc, node, path);
2770                                 if (ret < 0)
2771                                         err = ret;
2772                         }
2773                 }
2774                 list_splice_init(&list, &cache->pending[level]);
2775         }
2776         return err;
2777 }
2778
2779 static void mark_block_processed(struct reloc_control *rc,
2780                                  u64 bytenr, u32 blocksize)
2781 {
2782         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2783                         EXTENT_DIRTY, GFP_NOFS);
2784 }
2785
2786 static void __mark_block_processed(struct reloc_control *rc,
2787                                    struct backref_node *node)
2788 {
2789         u32 blocksize;
2790         if (node->level == 0 ||
2791             in_block_group(node->bytenr, rc->block_group)) {
2792                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2793                 mark_block_processed(rc, node->bytenr, blocksize);
2794         }
2795         node->processed = 1;
2796 }
2797
2798 /*
2799  * mark a block and all blocks directly/indirectly reference the block
2800  * as processed.
2801  */
2802 static void update_processed_blocks(struct reloc_control *rc,
2803                                     struct backref_node *node)
2804 {
2805         struct backref_node *next = node;
2806         struct backref_edge *edge;
2807         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2808         int index = 0;
2809
2810         while (next) {
2811                 cond_resched();
2812                 while (1) {
2813                         if (next->processed)
2814                                 break;
2815
2816                         __mark_block_processed(rc, next);
2817
2818                         if (list_empty(&next->upper))
2819                                 break;
2820
2821                         edge = list_entry(next->upper.next,
2822                                           struct backref_edge, list[LOWER]);
2823                         edges[index++] = edge;
2824                         next = edge->node[UPPER];
2825                 }
2826                 next = walk_down_backref(edges, &index);
2827         }
2828 }
2829
2830 static int tree_block_processed(u64 bytenr, u32 blocksize,
2831                                 struct reloc_control *rc)
2832 {
2833         if (test_range_bit(&rc->processed_blocks, bytenr,
2834                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2835                 return 1;
2836         return 0;
2837 }
2838
2839 static int get_tree_block_key(struct reloc_control *rc,
2840                               struct tree_block *block)
2841 {
2842         struct extent_buffer *eb;
2843
2844         BUG_ON(block->key_ready);
2845         eb = read_tree_block(rc->extent_root, block->bytenr,
2846                              block->key.objectid, block->key.offset);
2847         if (!eb || !extent_buffer_uptodate(eb)) {
2848                 free_extent_buffer(eb);
2849                 return -EIO;
2850         }
2851         WARN_ON(btrfs_header_level(eb) != block->level);
2852         if (block->level == 0)
2853                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2854         else
2855                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2856         free_extent_buffer(eb);
2857         block->key_ready = 1;
2858         return 0;
2859 }
2860
2861 static int reada_tree_block(struct reloc_control *rc,
2862                             struct tree_block *block)
2863 {
2864         BUG_ON(block->key_ready);
2865         if (block->key.type == BTRFS_METADATA_ITEM_KEY)
2866                 readahead_tree_block(rc->extent_root, block->bytenr,
2867                                      block->key.objectid,
2868                                      rc->extent_root->leafsize);
2869         else
2870                 readahead_tree_block(rc->extent_root, block->bytenr,
2871                                      block->key.objectid, block->key.offset);
2872         return 0;
2873 }
2874
2875 /*
2876  * helper function to relocate a tree block
2877  */
2878 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2879                                 struct reloc_control *rc,
2880                                 struct backref_node *node,
2881                                 struct btrfs_key *key,
2882                                 struct btrfs_path *path)
2883 {
2884         struct btrfs_root *root;
2885         int ret = 0;
2886
2887         if (!node)
2888                 return 0;
2889
2890         BUG_ON(node->processed);
2891         root = select_one_root(trans, node);
2892         if (root == ERR_PTR(-ENOENT)) {
2893                 update_processed_blocks(rc, node);
2894                 goto out;
2895         }
2896
2897         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2898                 ret = reserve_metadata_space(trans, rc, node);
2899                 if (ret)
2900                         goto out;
2901         }
2902
2903         if (root) {
2904                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
2905                         BUG_ON(node->new_bytenr);
2906                         BUG_ON(!list_empty(&node->list));
2907                         btrfs_record_root_in_trans(trans, root);
2908                         root = root->reloc_root;
2909                         node->new_bytenr = root->node->start;
2910                         node->root = root;
2911                         list_add_tail(&node->list, &rc->backref_cache.changed);
2912                 } else {
2913                         path->lowest_level = node->level;
2914                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2915                         btrfs_release_path(path);
2916                         if (ret > 0)
2917                                 ret = 0;
2918                 }
2919                 if (!ret)
2920                         update_processed_blocks(rc, node);
2921         } else {
2922                 ret = do_relocation(trans, rc, node, key, path, 1);
2923         }
2924 out:
2925         if (ret || node->level == 0 || node->cowonly)
2926                 remove_backref_node(&rc->backref_cache, node);
2927         return ret;
2928 }
2929
2930 /*
2931  * relocate a list of blocks
2932  */
2933 static noinline_for_stack
2934 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2935                          struct reloc_control *rc, struct rb_root *blocks)
2936 {
2937         struct backref_node *node;
2938         struct btrfs_path *path;
2939         struct tree_block *block;
2940         struct rb_node *rb_node;
2941         int ret;
2942         int err = 0;
2943
2944         path = btrfs_alloc_path();
2945         if (!path) {
2946                 err = -ENOMEM;
2947                 goto out_free_blocks;
2948         }
2949
2950         rb_node = rb_first(blocks);
2951         while (rb_node) {
2952                 block = rb_entry(rb_node, struct tree_block, rb_node);
2953                 if (!block->key_ready)
2954                         reada_tree_block(rc, block);
2955                 rb_node = rb_next(rb_node);
2956         }
2957
2958         rb_node = rb_first(blocks);
2959         while (rb_node) {
2960                 block = rb_entry(rb_node, struct tree_block, rb_node);
2961                 if (!block->key_ready) {
2962                         err = get_tree_block_key(rc, block);
2963                         if (err)
2964                                 goto out_free_path;
2965                 }
2966                 rb_node = rb_next(rb_node);
2967         }
2968
2969         rb_node = rb_first(blocks);
2970         while (rb_node) {
2971                 block = rb_entry(rb_node, struct tree_block, rb_node);
2972
2973                 node = build_backref_tree(rc, &block->key,
2974                                           block->level, block->bytenr);
2975                 if (IS_ERR(node)) {
2976                         err = PTR_ERR(node);
2977                         goto out;
2978                 }
2979
2980                 ret = relocate_tree_block(trans, rc, node, &block->key,
2981                                           path);
2982                 if (ret < 0) {
2983                         if (ret != -EAGAIN || rb_node == rb_first(blocks))
2984                                 err = ret;
2985                         goto out;
2986                 }
2987                 rb_node = rb_next(rb_node);
2988         }
2989 out:
2990         err = finish_pending_nodes(trans, rc, path, err);
2991
2992 out_free_path:
2993         btrfs_free_path(path);
2994 out_free_blocks:
2995         free_block_list(blocks);
2996         return err;
2997 }
2998
2999 static noinline_for_stack
3000 int prealloc_file_extent_cluster(struct inode *inode,
3001                                  struct file_extent_cluster *cluster)
3002 {
3003         u64 alloc_hint = 0;
3004         u64 start;
3005         u64 end;
3006         u64 offset = BTRFS_I(inode)->index_cnt;
3007         u64 num_bytes;
3008         int nr = 0;
3009         int ret = 0;
3010
3011         BUG_ON(cluster->start != cluster->boundary[0]);
3012         mutex_lock(&inode->i_mutex);
3013
3014         ret = btrfs_check_data_free_space(inode, cluster->end +
3015                                           1 - cluster->start);
3016         if (ret)
3017                 goto out;
3018
3019         while (nr < cluster->nr) {
3020                 start = cluster->boundary[nr] - offset;
3021                 if (nr + 1 < cluster->nr)
3022                         end = cluster->boundary[nr + 1] - 1 - offset;
3023                 else
3024                         end = cluster->end - offset;
3025
3026                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3027                 num_bytes = end + 1 - start;
3028                 ret = btrfs_prealloc_file_range(inode, 0, start,
3029                                                 num_bytes, num_bytes,
3030                                                 end + 1, &alloc_hint);
3031                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3032                 if (ret)
3033                         break;
3034                 nr++;
3035         }
3036         btrfs_free_reserved_data_space(inode, cluster->end +
3037                                        1 - cluster->start);
3038 out:
3039         mutex_unlock(&inode->i_mutex);
3040         return ret;
3041 }
3042
3043 static noinline_for_stack
3044 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3045                          u64 block_start)
3046 {
3047         struct btrfs_root *root = BTRFS_I(inode)->root;
3048         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3049         struct extent_map *em;
3050         int ret = 0;
3051
3052         em = alloc_extent_map();
3053         if (!em)
3054                 return -ENOMEM;
3055
3056         em->start = start;
3057         em->len = end + 1 - start;
3058         em->block_len = em->len;
3059         em->block_start = block_start;
3060         em->bdev = root->fs_info->fs_devices->latest_bdev;
3061         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3062
3063         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3064         while (1) {
3065                 write_lock(&em_tree->lock);
3066                 ret = add_extent_mapping(em_tree, em, 0);
3067                 write_unlock(&em_tree->lock);
3068                 if (ret != -EEXIST) {
3069                         free_extent_map(em);
3070                         break;
3071                 }
3072                 btrfs_drop_extent_cache(inode, start, end, 0);
3073         }
3074         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3075         return ret;
3076 }
3077
3078 static int relocate_file_extent_cluster(struct inode *inode,
3079                                         struct file_extent_cluster *cluster)
3080 {
3081         u64 page_start;
3082         u64 page_end;
3083         u64 offset = BTRFS_I(inode)->index_cnt;
3084         unsigned long index;
3085         unsigned long last_index;
3086         struct page *page;
3087         struct file_ra_state *ra;
3088         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3089         int nr = 0;
3090         int ret = 0;
3091
3092         if (!cluster->nr)
3093                 return 0;
3094
3095         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3096         if (!ra)
3097                 return -ENOMEM;
3098
3099         ret = prealloc_file_extent_cluster(inode, cluster);
3100         if (ret)
3101                 goto out;
3102
3103         file_ra_state_init(ra, inode->i_mapping);
3104
3105         ret = setup_extent_mapping(inode, cluster->start - offset,
3106                                    cluster->end - offset, cluster->start);
3107         if (ret)
3108                 goto out;
3109
3110         index = (cluster->start - offset) >> PAGE_CACHE_SHIFT;
3111         last_index = (cluster->end - offset) >> PAGE_CACHE_SHIFT;
3112         while (index <= last_index) {
3113                 ret = btrfs_delalloc_reserve_metadata(inode, PAGE_CACHE_SIZE);
3114                 if (ret)
3115                         goto out;
3116
3117                 page = find_lock_page(inode->i_mapping, index);
3118                 if (!page) {
3119                         page_cache_sync_readahead(inode->i_mapping,
3120                                                   ra, NULL, index,
3121                                                   last_index + 1 - index);
3122                         page = find_or_create_page(inode->i_mapping, index,
3123                                                    mask);
3124                         if (!page) {
3125                                 btrfs_delalloc_release_metadata(inode,
3126                                                         PAGE_CACHE_SIZE);
3127                                 ret = -ENOMEM;
3128                                 goto out;
3129                         }
3130                 }
3131
3132                 if (PageReadahead(page)) {
3133                         page_cache_async_readahead(inode->i_mapping,
3134                                                    ra, NULL, page, index,
3135                                                    last_index + 1 - index);
3136                 }
3137
3138                 if (!PageUptodate(page)) {
3139                         btrfs_readpage(NULL, page);
3140                         lock_page(page);
3141                         if (!PageUptodate(page)) {
3142                                 unlock_page(page);
3143                                 page_cache_release(page);
3144                                 btrfs_delalloc_release_metadata(inode,
3145                                                         PAGE_CACHE_SIZE);
3146                                 ret = -EIO;
3147                                 goto out;
3148                         }
3149                 }
3150
3151                 page_start = page_offset(page);
3152                 page_end = page_start + PAGE_CACHE_SIZE - 1;
3153
3154                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3155
3156                 set_page_extent_mapped(page);
3157
3158                 if (nr < cluster->nr &&
3159                     page_start + offset == cluster->boundary[nr]) {
3160                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3161                                         page_start, page_end,
3162                                         EXTENT_BOUNDARY, GFP_NOFS);
3163                         nr++;
3164                 }
3165
3166                 btrfs_set_extent_delalloc(inode, page_start, page_end, NULL);
3167                 set_page_dirty(page);
3168
3169                 unlock_extent(&BTRFS_I(inode)->io_tree,
3170                               page_start, page_end);
3171                 unlock_page(page);
3172                 page_cache_release(page);
3173
3174                 index++;
3175                 balance_dirty_pages_ratelimited(inode->i_mapping);
3176                 btrfs_throttle(BTRFS_I(inode)->root);
3177         }
3178         WARN_ON(nr != cluster->nr);
3179 out:
3180         kfree(ra);
3181         return ret;
3182 }
3183
3184 static noinline_for_stack
3185 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3186                          struct file_extent_cluster *cluster)
3187 {
3188         int ret;
3189
3190         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3191                 ret = relocate_file_extent_cluster(inode, cluster);
3192                 if (ret)
3193                         return ret;
3194                 cluster->nr = 0;
3195         }
3196
3197         if (!cluster->nr)
3198                 cluster->start = extent_key->objectid;
3199         else
3200                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3201         cluster->end = extent_key->objectid + extent_key->offset - 1;
3202         cluster->boundary[cluster->nr] = extent_key->objectid;
3203         cluster->nr++;
3204
3205         if (cluster->nr >= MAX_EXTENTS) {
3206                 ret = relocate_file_extent_cluster(inode, cluster);
3207                 if (ret)
3208                         return ret;
3209                 cluster->nr = 0;
3210         }
3211         return 0;
3212 }
3213
3214 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3215 static int get_ref_objectid_v0(struct reloc_control *rc,
3216                                struct btrfs_path *path,
3217                                struct btrfs_key *extent_key,
3218                                u64 *ref_objectid, int *path_change)
3219 {
3220         struct btrfs_key key;
3221         struct extent_buffer *leaf;
3222         struct btrfs_extent_ref_v0 *ref0;
3223         int ret;
3224         int slot;
3225
3226         leaf = path->nodes[0];
3227         slot = path->slots[0];
3228         while (1) {
3229                 if (slot >= btrfs_header_nritems(leaf)) {
3230                         ret = btrfs_next_leaf(rc->extent_root, path);
3231                         if (ret < 0)
3232                                 return ret;
3233                         BUG_ON(ret > 0);
3234                         leaf = path->nodes[0];
3235                         slot = path->slots[0];
3236                         if (path_change)
3237                                 *path_change = 1;
3238                 }
3239                 btrfs_item_key_to_cpu(leaf, &key, slot);
3240                 if (key.objectid != extent_key->objectid)
3241                         return -ENOENT;
3242
3243                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
3244                         slot++;
3245                         continue;
3246                 }
3247                 ref0 = btrfs_item_ptr(leaf, slot,
3248                                 struct btrfs_extent_ref_v0);
3249                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
3250                 break;
3251         }
3252         return 0;
3253 }
3254 #endif
3255
3256 /*
3257  * helper to add a tree block to the list.
3258  * the major work is getting the generation and level of the block
3259  */
3260 static int add_tree_block(struct reloc_control *rc,
3261                           struct btrfs_key *extent_key,
3262                           struct btrfs_path *path,
3263                           struct rb_root *blocks)
3264 {
3265         struct extent_buffer *eb;
3266         struct btrfs_extent_item *ei;
3267         struct btrfs_tree_block_info *bi;
3268         struct tree_block *block;
3269         struct rb_node *rb_node;
3270         u32 item_size;
3271         int level = -1;
3272         u64 generation;
3273
3274         eb =  path->nodes[0];
3275         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3276
3277         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3278             item_size >= sizeof(*ei) + sizeof(*bi)) {
3279                 ei = btrfs_item_ptr(eb, path->slots[0],
3280                                 struct btrfs_extent_item);
3281                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3282                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3283                         level = btrfs_tree_block_level(eb, bi);
3284                 } else {
3285                         level = (int)extent_key->offset;
3286                 }
3287                 generation = btrfs_extent_generation(eb, ei);
3288         } else {
3289 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3290                 u64 ref_owner;
3291                 int ret;
3292
3293                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
3294                 ret = get_ref_objectid_v0(rc, path, extent_key,
3295                                           &ref_owner, NULL);
3296                 if (ret < 0)
3297                         return ret;
3298                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
3299                 level = (int)ref_owner;
3300                 /* FIXME: get real generation */
3301                 generation = 0;
3302 #else
3303                 BUG();
3304 #endif
3305         }
3306
3307         btrfs_release_path(path);
3308
3309         BUG_ON(level == -1);
3310
3311         block = kmalloc(sizeof(*block), GFP_NOFS);
3312         if (!block)
3313                 return -ENOMEM;
3314
3315         block->bytenr = extent_key->objectid;
3316         block->key.objectid = rc->extent_root->leafsize;
3317         block->key.offset = generation;
3318         block->level = level;
3319         block->key_ready = 0;
3320
3321         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3322         if (rb_node)
3323                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3324
3325         return 0;
3326 }
3327
3328 /*
3329  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3330  */
3331 static int __add_tree_block(struct reloc_control *rc,
3332                             u64 bytenr, u32 blocksize,
3333                             struct rb_root *blocks)
3334 {
3335         struct btrfs_path *path;
3336         struct btrfs_key key;
3337         int ret;
3338         bool skinny = btrfs_fs_incompat(rc->extent_root->fs_info,
3339                                         SKINNY_METADATA);
3340
3341         if (tree_block_processed(bytenr, blocksize, rc))
3342                 return 0;
3343
3344         if (tree_search(blocks, bytenr))
3345                 return 0;
3346
3347         path = btrfs_alloc_path();
3348         if (!path)
3349                 return -ENOMEM;
3350 again:
3351         key.objectid = bytenr;
3352         if (skinny) {
3353                 key.type = BTRFS_METADATA_ITEM_KEY;
3354                 key.offset = (u64)-1;
3355         } else {
3356                 key.type = BTRFS_EXTENT_ITEM_KEY;
3357                 key.offset = blocksize;
3358         }
3359
3360         path->search_commit_root = 1;
3361         path->skip_locking = 1;
3362         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3363         if (ret < 0)
3364                 goto out;
3365
3366         if (ret > 0 && skinny) {
3367                 if (path->slots[0]) {
3368                         path->slots[0]--;
3369                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3370                                               path->slots[0]);
3371                         if (key.objectid == bytenr &&
3372                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3373                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3374                               key.offset == blocksize)))
3375                                 ret = 0;
3376                 }
3377
3378                 if (ret) {
3379                         skinny = false;
3380                         btrfs_release_path(path);
3381                         goto again;
3382                 }
3383         }
3384         BUG_ON(ret);
3385
3386         ret = add_tree_block(rc, &key, path, blocks);
3387 out:
3388         btrfs_free_path(path);
3389         return ret;
3390 }
3391
3392 /*
3393  * helper to check if the block use full backrefs for pointers in it
3394  */
3395 static int block_use_full_backref(struct reloc_control *rc,
3396                                   struct extent_buffer *eb)
3397 {
3398         u64 flags;
3399         int ret;
3400
3401         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3402             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3403                 return 1;
3404
3405         ret = btrfs_lookup_extent_info(NULL, rc->extent_root,
3406                                        eb->start, btrfs_header_level(eb), 1,
3407                                        NULL, &flags);
3408         BUG_ON(ret);
3409
3410         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3411                 ret = 1;
3412         else
3413                 ret = 0;
3414         return ret;
3415 }
3416
3417 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3418                                     struct inode *inode, u64 ino)
3419 {
3420         struct btrfs_key key;
3421         struct btrfs_root *root = fs_info->tree_root;
3422         struct btrfs_trans_handle *trans;
3423         int ret = 0;
3424
3425         if (inode)
3426                 goto truncate;
3427
3428         key.objectid = ino;
3429         key.type = BTRFS_INODE_ITEM_KEY;
3430         key.offset = 0;
3431
3432         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3433         if (IS_ERR(inode) || is_bad_inode(inode)) {
3434                 if (!IS_ERR(inode))
3435                         iput(inode);
3436                 return -ENOENT;
3437         }
3438
3439 truncate:
3440         ret = btrfs_check_trunc_cache_free_space(root,
3441                                                  &fs_info->global_block_rsv);
3442         if (ret)
3443                 goto out;
3444
3445         trans = btrfs_join_transaction(root);
3446         if (IS_ERR(trans)) {
3447                 ret = PTR_ERR(trans);
3448                 goto out;
3449         }
3450
3451         ret = btrfs_truncate_free_space_cache(root, trans, inode);
3452
3453         btrfs_end_transaction(trans, root);
3454         btrfs_btree_balance_dirty(root);
3455 out:
3456         iput(inode);
3457         return ret;
3458 }
3459
3460 /*
3461  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3462  * this function scans fs tree to find blocks reference the data extent
3463  */
3464 static int find_data_references(struct reloc_control *rc,
3465                                 struct btrfs_key *extent_key,
3466                                 struct extent_buffer *leaf,
3467                                 struct btrfs_extent_data_ref *ref,
3468                                 struct rb_root *blocks)
3469 {
3470         struct btrfs_path *path;
3471         struct tree_block *block;
3472         struct btrfs_root *root;
3473         struct btrfs_file_extent_item *fi;
3474         struct rb_node *rb_node;
3475         struct btrfs_key key;
3476         u64 ref_root;
3477         u64 ref_objectid;
3478         u64 ref_offset;
3479         u32 ref_count;
3480         u32 nritems;
3481         int err = 0;
3482         int added = 0;
3483         int counted;
3484         int ret;
3485
3486         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3487         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3488         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3489         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3490
3491         /*
3492          * This is an extent belonging to the free space cache, lets just delete
3493          * it and redo the search.
3494          */
3495         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3496                 ret = delete_block_group_cache(rc->extent_root->fs_info,
3497                                                NULL, ref_objectid);
3498                 if (ret != -ENOENT)
3499                         return ret;
3500                 ret = 0;
3501         }
3502
3503         path = btrfs_alloc_path();
3504         if (!path)
3505                 return -ENOMEM;
3506         path->reada = 1;
3507
3508         root = read_fs_root(rc->extent_root->fs_info, ref_root);
3509         if (IS_ERR(root)) {
3510                 err = PTR_ERR(root);
3511                 goto out;
3512         }
3513
3514         key.objectid = ref_objectid;
3515         key.type = BTRFS_EXTENT_DATA_KEY;
3516         if (ref_offset > ((u64)-1 << 32))
3517                 key.offset = 0;
3518         else
3519                 key.offset = ref_offset;
3520
3521         path->search_commit_root = 1;
3522         path->skip_locking = 1;
3523         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3524         if (ret < 0) {
3525                 err = ret;
3526                 goto out;
3527         }
3528
3529         leaf = path->nodes[0];
3530         nritems = btrfs_header_nritems(leaf);
3531         /*
3532          * the references in tree blocks that use full backrefs
3533          * are not counted in
3534          */
3535         if (block_use_full_backref(rc, leaf))
3536                 counted = 0;
3537         else
3538                 counted = 1;
3539         rb_node = tree_search(blocks, leaf->start);
3540         if (rb_node) {
3541                 if (counted)
3542                         added = 1;
3543                 else
3544                         path->slots[0] = nritems;
3545         }
3546
3547         while (ref_count > 0) {
3548                 while (path->slots[0] >= nritems) {
3549                         ret = btrfs_next_leaf(root, path);
3550                         if (ret < 0) {
3551                                 err = ret;
3552                                 goto out;
3553                         }
3554                         if (WARN_ON(ret > 0))
3555                                 goto out;
3556
3557                         leaf = path->nodes[0];
3558                         nritems = btrfs_header_nritems(leaf);
3559                         added = 0;
3560
3561                         if (block_use_full_backref(rc, leaf))
3562                                 counted = 0;
3563                         else
3564                                 counted = 1;
3565                         rb_node = tree_search(blocks, leaf->start);
3566                         if (rb_node) {
3567                                 if (counted)
3568                                         added = 1;
3569                                 else
3570                                         path->slots[0] = nritems;
3571                         }
3572                 }
3573
3574                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3575                 if (WARN_ON(key.objectid != ref_objectid ||
3576                     key.type != BTRFS_EXTENT_DATA_KEY))
3577                         break;
3578
3579                 fi = btrfs_item_ptr(leaf, path->slots[0],
3580                                     struct btrfs_file_extent_item);
3581
3582                 if (btrfs_file_extent_type(leaf, fi) ==
3583                     BTRFS_FILE_EXTENT_INLINE)
3584                         goto next;
3585
3586                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3587                     extent_key->objectid)
3588                         goto next;
3589
3590                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3591                 if (key.offset != ref_offset)
3592                         goto next;
3593
3594                 if (counted)
3595                         ref_count--;
3596                 if (added)
3597                         goto next;
3598
3599                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
3600                         block = kmalloc(sizeof(*block), GFP_NOFS);
3601                         if (!block) {
3602                                 err = -ENOMEM;
3603                                 break;
3604                         }
3605                         block->bytenr = leaf->start;
3606                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3607                         block->level = 0;
3608                         block->key_ready = 1;
3609                         rb_node = tree_insert(blocks, block->bytenr,
3610                                               &block->rb_node);
3611                         if (rb_node)
3612                                 backref_tree_panic(rb_node, -EEXIST,
3613                                                    block->bytenr);
3614                 }
3615                 if (counted)
3616                         added = 1;
3617                 else
3618                         path->slots[0] = nritems;
3619 next:
3620                 path->slots[0]++;
3621
3622         }
3623 out:
3624         btrfs_free_path(path);
3625         return err;
3626 }
3627
3628 /*
3629  * helper to find all tree blocks that reference a given data extent
3630  */
3631 static noinline_for_stack
3632 int add_data_references(struct reloc_control *rc,
3633                         struct btrfs_key *extent_key,
3634                         struct btrfs_path *path,
3635                         struct rb_root *blocks)
3636 {
3637         struct btrfs_key key;
3638         struct extent_buffer *eb;
3639         struct btrfs_extent_data_ref *dref;
3640         struct btrfs_extent_inline_ref *iref;
3641         unsigned long ptr;
3642         unsigned long end;
3643         u32 blocksize = btrfs_level_size(rc->extent_root, 0);
3644         int ret = 0;
3645         int err = 0;
3646
3647         eb = path->nodes[0];
3648         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3649         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3650 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3651         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3652                 ptr = end;
3653         else
3654 #endif
3655                 ptr += sizeof(struct btrfs_extent_item);
3656
3657         while (ptr < end) {
3658                 iref = (struct btrfs_extent_inline_ref *)ptr;
3659                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3660                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3661                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3662                         ret = __add_tree_block(rc, key.offset, blocksize,
3663                                                blocks);
3664                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3665                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3666                         ret = find_data_references(rc, extent_key,
3667                                                    eb, dref, blocks);
3668                 } else {
3669                         BUG();
3670                 }
3671                 if (ret) {
3672                         err = ret;
3673                         goto out;
3674                 }
3675                 ptr += btrfs_extent_inline_ref_size(key.type);
3676         }
3677         WARN_ON(ptr > end);
3678
3679         while (1) {
3680                 cond_resched();
3681                 eb = path->nodes[0];
3682                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3683                         ret = btrfs_next_leaf(rc->extent_root, path);
3684                         if (ret < 0) {
3685                                 err = ret;
3686                                 break;
3687                         }
3688                         if (ret > 0)
3689                                 break;
3690                         eb = path->nodes[0];
3691                 }
3692
3693                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3694                 if (key.objectid != extent_key->objectid)
3695                         break;
3696
3697 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3698                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3699                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3700 #else
3701                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3702                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3703 #endif
3704                         ret = __add_tree_block(rc, key.offset, blocksize,
3705                                                blocks);
3706                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3707                         dref = btrfs_item_ptr(eb, path->slots[0],
3708                                               struct btrfs_extent_data_ref);
3709                         ret = find_data_references(rc, extent_key,
3710                                                    eb, dref, blocks);
3711                 } else {
3712                         ret = 0;
3713                 }
3714                 if (ret) {
3715                         err = ret;
3716                         break;
3717                 }
3718                 path->slots[0]++;
3719         }
3720 out:
3721         btrfs_release_path(path);
3722         if (err)
3723                 free_block_list(blocks);
3724         return err;
3725 }
3726
3727 /*
3728  * helper to find next unprocessed extent
3729  */
3730 static noinline_for_stack
3731 int find_next_extent(struct btrfs_trans_handle *trans,
3732                      struct reloc_control *rc, struct btrfs_path *path,
3733                      struct btrfs_key *extent_key)
3734 {
3735         struct btrfs_key key;
3736         struct extent_buffer *leaf;
3737         u64 start, end, last;
3738         int ret;
3739
3740         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3741         while (1) {
3742                 cond_resched();
3743                 if (rc->search_start >= last) {
3744                         ret = 1;
3745                         break;
3746                 }
3747
3748                 key.objectid = rc->search_start;
3749                 key.type = BTRFS_EXTENT_ITEM_KEY;
3750                 key.offset = 0;
3751
3752                 path->search_commit_root = 1;
3753                 path->skip_locking = 1;
3754                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3755                                         0, 0);
3756                 if (ret < 0)
3757                         break;
3758 next:
3759                 leaf = path->nodes[0];
3760                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3761                         ret = btrfs_next_leaf(rc->extent_root, path);
3762                         if (ret != 0)
3763                                 break;
3764                         leaf = path->nodes[0];
3765                 }
3766
3767                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3768                 if (key.objectid >= last) {
3769                         ret = 1;
3770                         break;
3771                 }
3772
3773                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3774                     key.type != BTRFS_METADATA_ITEM_KEY) {
3775                         path->slots[0]++;
3776                         goto next;
3777                 }
3778
3779                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3780                     key.objectid + key.offset <= rc->search_start) {
3781                         path->slots[0]++;
3782                         goto next;
3783                 }
3784
3785                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3786                     key.objectid + rc->extent_root->leafsize <=
3787                     rc->search_start) {
3788                         path->slots[0]++;
3789                         goto next;
3790                 }
3791
3792                 ret = find_first_extent_bit(&rc->processed_blocks,
3793                                             key.objectid, &start, &end,
3794                                             EXTENT_DIRTY, NULL);
3795
3796                 if (ret == 0 && start <= key.objectid) {
3797                         btrfs_release_path(path);
3798                         rc->search_start = end + 1;
3799                 } else {
3800                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3801                                 rc->search_start = key.objectid + key.offset;
3802                         else
3803                                 rc->search_start = key.objectid +
3804                                         rc->extent_root->leafsize;
3805                         memcpy(extent_key, &key, sizeof(key));
3806                         return 0;
3807                 }
3808         }
3809         btrfs_release_path(path);
3810         return ret;
3811 }
3812
3813 static void set_reloc_control(struct reloc_control *rc)
3814 {
3815         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3816
3817         mutex_lock(&fs_info->reloc_mutex);
3818         fs_info->reloc_ctl = rc;
3819         mutex_unlock(&fs_info->reloc_mutex);
3820 }
3821
3822 static void unset_reloc_control(struct reloc_control *rc)
3823 {
3824         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3825
3826         mutex_lock(&fs_info->reloc_mutex);
3827         fs_info->reloc_ctl = NULL;
3828         mutex_unlock(&fs_info->reloc_mutex);
3829 }
3830
3831 static int check_extent_flags(u64 flags)
3832 {
3833         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3834             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3835                 return 1;
3836         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3837             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3838                 return 1;
3839         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3840             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3841                 return 1;
3842         return 0;
3843 }
3844
3845 static noinline_for_stack
3846 int prepare_to_relocate(struct reloc_control *rc)
3847 {
3848         struct btrfs_trans_handle *trans;
3849
3850         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root,
3851                                               BTRFS_BLOCK_RSV_TEMP);
3852         if (!rc->block_rsv)
3853                 return -ENOMEM;
3854
3855         memset(&rc->cluster, 0, sizeof(rc->cluster));
3856         rc->search_start = rc->block_group->key.objectid;
3857         rc->extents_found = 0;
3858         rc->nodes_relocated = 0;
3859         rc->merging_rsv_size = 0;
3860         rc->reserved_bytes = 0;
3861         rc->block_rsv->size = rc->extent_root->nodesize *
3862                               RELOCATION_RESERVED_NODES;
3863
3864         rc->create_reloc_tree = 1;
3865         set_reloc_control(rc);
3866
3867         trans = btrfs_join_transaction(rc->extent_root);
3868         if (IS_ERR(trans)) {
3869                 unset_reloc_control(rc);
3870                 /*
3871                  * extent tree is not a ref_cow tree and has no reloc_root to
3872                  * cleanup.  And callers are responsible to free the above
3873                  * block rsv.
3874                  */
3875                 return PTR_ERR(trans);
3876         }
3877         btrfs_commit_transaction(trans, rc->extent_root);
3878         return 0;
3879 }
3880
3881 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3882 {
3883         struct rb_root blocks = RB_ROOT;
3884         struct btrfs_key key;
3885         struct btrfs_trans_handle *trans = NULL;
3886         struct btrfs_path *path;
3887         struct btrfs_extent_item *ei;
3888         u64 flags;
3889         u32 item_size;
3890         int ret;
3891         int err = 0;
3892         int progress = 0;
3893
3894         path = btrfs_alloc_path();
3895         if (!path)
3896                 return -ENOMEM;
3897         path->reada = 1;
3898
3899         ret = prepare_to_relocate(rc);
3900         if (ret) {
3901                 err = ret;
3902                 goto out_free;
3903         }
3904
3905         while (1) {
3906                 rc->reserved_bytes = 0;
3907                 ret = btrfs_block_rsv_refill(rc->extent_root,
3908                                         rc->block_rsv, rc->block_rsv->size,
3909                                         BTRFS_RESERVE_FLUSH_ALL);
3910                 if (ret) {
3911                         err = ret;
3912                         break;
3913                 }
3914                 progress++;
3915                 trans = btrfs_start_transaction(rc->extent_root, 0);
3916                 if (IS_ERR(trans)) {
3917                         err = PTR_ERR(trans);
3918                         trans = NULL;
3919                         break;
3920                 }
3921 restart:
3922                 if (update_backref_cache(trans, &rc->backref_cache)) {
3923                         btrfs_end_transaction(trans, rc->extent_root);
3924                         continue;
3925                 }
3926
3927                 ret = find_next_extent(trans, rc, path, &key);
3928                 if (ret < 0)
3929                         err = ret;
3930                 if (ret != 0)
3931                         break;
3932
3933                 rc->extents_found++;
3934
3935                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3936                                     struct btrfs_extent_item);
3937                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
3938                 if (item_size >= sizeof(*ei)) {
3939                         flags = btrfs_extent_flags(path->nodes[0], ei);
3940                         ret = check_extent_flags(flags);
3941                         BUG_ON(ret);
3942
3943                 } else {
3944 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3945                         u64 ref_owner;
3946                         int path_change = 0;
3947
3948                         BUG_ON(item_size !=
3949                                sizeof(struct btrfs_extent_item_v0));
3950                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3951                                                   &path_change);
3952                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3953                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3954                         else
3955                                 flags = BTRFS_EXTENT_FLAG_DATA;
3956
3957                         if (path_change) {
3958                                 btrfs_release_path(path);
3959
3960                                 path->search_commit_root = 1;
3961                                 path->skip_locking = 1;
3962                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3963                                                         &key, path, 0, 0);
3964                                 if (ret < 0) {
3965                                         err = ret;
3966                                         break;
3967                                 }
3968                                 BUG_ON(ret > 0);
3969                         }
3970 #else
3971                         BUG();
3972 #endif
3973                 }
3974
3975                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3976                         ret = add_tree_block(rc, &key, path, &blocks);
3977                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3978                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
3979                         ret = add_data_references(rc, &key, path, &blocks);
3980                 } else {
3981                         btrfs_release_path(path);
3982                         ret = 0;
3983                 }
3984                 if (ret < 0) {
3985                         err = ret;
3986                         break;
3987                 }
3988
3989                 if (!RB_EMPTY_ROOT(&blocks)) {
3990                         ret = relocate_tree_blocks(trans, rc, &blocks);
3991                         if (ret < 0) {
3992                                 /*
3993                                  * if we fail to relocate tree blocks, force to update
3994                                  * backref cache when committing transaction.
3995                                  */
3996                                 rc->backref_cache.last_trans = trans->transid - 1;
3997
3998                                 if (ret != -EAGAIN) {
3999                                         err = ret;
4000                                         break;
4001                                 }
4002                                 rc->extents_found--;
4003                                 rc->search_start = key.objectid;
4004                         }
4005                 }
4006
4007                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4008                 btrfs_btree_balance_dirty(rc->extent_root);
4009                 trans = NULL;
4010
4011                 if (rc->stage == MOVE_DATA_EXTENTS &&
4012                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4013                         rc->found_file_extent = 1;
4014                         ret = relocate_data_extent(rc->data_inode,
4015                                                    &key, &rc->cluster);
4016                         if (ret < 0) {
4017                                 err = ret;
4018                                 break;
4019                         }
4020                 }
4021         }
4022         if (trans && progress && err == -ENOSPC) {
4023                 ret = btrfs_force_chunk_alloc(trans, rc->extent_root,
4024                                               rc->block_group->flags);
4025                 if (ret == 0) {
4026                         err = 0;
4027                         progress = 0;
4028                         goto restart;
4029                 }
4030         }
4031
4032         btrfs_release_path(path);
4033         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
4034                           GFP_NOFS);
4035
4036         if (trans) {
4037                 btrfs_end_transaction_throttle(trans, rc->extent_root);
4038                 btrfs_btree_balance_dirty(rc->extent_root);
4039         }
4040
4041         if (!err) {
4042                 ret = relocate_file_extent_cluster(rc->data_inode,
4043                                                    &rc->cluster);
4044                 if (ret < 0)
4045                         err = ret;
4046         }
4047
4048         rc->create_reloc_tree = 0;
4049         set_reloc_control(rc);
4050
4051         backref_cache_cleanup(&rc->backref_cache);
4052         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4053
4054         err = prepare_to_merge(rc, err);
4055
4056         merge_reloc_roots(rc);
4057
4058         rc->merge_reloc_tree = 0;
4059         unset_reloc_control(rc);
4060         btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1);
4061
4062         /* get rid of pinned extents */
4063         trans = btrfs_join_transaction(rc->extent_root);
4064         if (IS_ERR(trans))
4065                 err = PTR_ERR(trans);
4066         else
4067                 btrfs_commit_transaction(trans, rc->extent_root);
4068 out_free:
4069         btrfs_free_block_rsv(rc->extent_root, rc->block_rsv);
4070         btrfs_free_path(path);
4071         return err;
4072 }
4073
4074 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4075                                  struct btrfs_root *root, u64 objectid)
4076 {
4077         struct btrfs_path *path;
4078         struct btrfs_inode_item *item;
4079         struct extent_buffer *leaf;
4080         int ret;
4081
4082         path = btrfs_alloc_path();
4083         if (!path)
4084                 return -ENOMEM;
4085
4086         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4087         if (ret)
4088                 goto out;
4089
4090         leaf = path->nodes[0];
4091         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4092         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
4093         btrfs_set_inode_generation(leaf, item, 1);
4094         btrfs_set_inode_size(leaf, item, 0);
4095         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4096         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4097                                           BTRFS_INODE_PREALLOC);
4098         btrfs_mark_buffer_dirty(leaf);
4099         btrfs_release_path(path);
4100 out:
4101         btrfs_free_path(path);
4102         return ret;
4103 }
4104
4105 /*
4106  * helper to create inode for data relocation.
4107  * the inode is in data relocation tree and its link count is 0
4108  */
4109 static noinline_for_stack
4110 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4111                                  struct btrfs_block_group_cache *group)
4112 {
4113         struct inode *inode = NULL;
4114         struct btrfs_trans_handle *trans;
4115         struct btrfs_root *root;
4116         struct btrfs_key key;
4117         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
4118         int err = 0;
4119
4120         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4121         if (IS_ERR(root))
4122                 return ERR_CAST(root);
4123
4124         trans = btrfs_start_transaction(root, 6);
4125         if (IS_ERR(trans))
4126                 return ERR_CAST(trans);
4127
4128         err = btrfs_find_free_objectid(root, &objectid);
4129         if (err)
4130                 goto out;
4131
4132         err = __insert_orphan_inode(trans, root, objectid);
4133         BUG_ON(err);
4134
4135         key.objectid = objectid;
4136         key.type = BTRFS_INODE_ITEM_KEY;
4137         key.offset = 0;
4138         inode = btrfs_iget(root->fs_info->sb, &key, root, NULL);
4139         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
4140         BTRFS_I(inode)->index_cnt = group->key.objectid;
4141
4142         err = btrfs_orphan_add(trans, inode);
4143 out:
4144         btrfs_end_transaction(trans, root);
4145         btrfs_btree_balance_dirty(root);
4146         if (err) {
4147                 if (inode)
4148                         iput(inode);
4149                 inode = ERR_PTR(err);
4150         }
4151         return inode;
4152 }
4153
4154 static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
4155 {
4156         struct reloc_control *rc;
4157
4158         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4159         if (!rc)
4160                 return NULL;
4161
4162         INIT_LIST_HEAD(&rc->reloc_roots);
4163         backref_cache_init(&rc->backref_cache);
4164         mapping_tree_init(&rc->reloc_root_tree);
4165         extent_io_tree_init(&rc->processed_blocks,
4166                             fs_info->btree_inode->i_mapping);
4167         return rc;
4168 }
4169
4170 /*
4171  * function to relocate all extents in a block group.
4172  */
4173 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
4174 {
4175         struct btrfs_fs_info *fs_info = extent_root->fs_info;
4176         struct reloc_control *rc;
4177         struct inode *inode;
4178         struct btrfs_path *path;
4179         int ret;
4180         int rw = 0;
4181         int err = 0;
4182
4183         rc = alloc_reloc_control(fs_info);
4184         if (!rc)
4185                 return -ENOMEM;
4186
4187         rc->extent_root = extent_root;
4188
4189         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
4190         BUG_ON(!rc->block_group);
4191
4192         if (!rc->block_group->ro) {
4193                 ret = btrfs_set_block_group_ro(extent_root, rc->block_group);
4194                 if (ret) {
4195                         err = ret;
4196                         goto out;
4197                 }
4198                 rw = 1;
4199         }
4200
4201         path = btrfs_alloc_path();
4202         if (!path) {
4203                 err = -ENOMEM;
4204                 goto out;
4205         }
4206
4207         inode = lookup_free_space_inode(fs_info->tree_root, rc->block_group,
4208                                         path);
4209         btrfs_free_path(path);
4210
4211         if (!IS_ERR(inode))
4212                 ret = delete_block_group_cache(fs_info, inode, 0);
4213         else
4214                 ret = PTR_ERR(inode);
4215
4216         if (ret && ret != -ENOENT) {
4217                 err = ret;
4218                 goto out;
4219         }
4220
4221         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4222         if (IS_ERR(rc->data_inode)) {
4223                 err = PTR_ERR(rc->data_inode);
4224                 rc->data_inode = NULL;
4225                 goto out;
4226         }
4227
4228         btrfs_info(extent_root->fs_info, "relocating block group %llu flags %llu",
4229                rc->block_group->key.objectid, rc->block_group->flags);
4230
4231         ret = btrfs_start_delalloc_roots(fs_info, 0, -1);
4232         if (ret < 0) {
4233                 err = ret;
4234                 goto out;
4235         }
4236         btrfs_wait_ordered_roots(fs_info, -1);
4237
4238         while (1) {
4239                 mutex_lock(&fs_info->cleaner_mutex);
4240                 ret = relocate_block_group(rc);
4241                 mutex_unlock(&fs_info->cleaner_mutex);
4242                 if (ret < 0) {
4243                         err = ret;
4244                         goto out;
4245                 }
4246
4247                 if (rc->extents_found == 0)
4248                         break;
4249
4250                 btrfs_info(extent_root->fs_info, "found %llu extents",
4251                         rc->extents_found);
4252
4253                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4254                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4255                                                        (u64)-1);
4256                         if (ret) {
4257                                 err = ret;
4258                                 goto out;
4259                         }
4260                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4261                                                  0, -1);
4262                         rc->stage = UPDATE_DATA_PTRS;
4263                 }
4264         }
4265
4266         WARN_ON(rc->block_group->pinned > 0);
4267         WARN_ON(rc->block_group->reserved > 0);
4268         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4269 out:
4270         if (err && rw)
4271                 btrfs_set_block_group_rw(extent_root, rc->block_group);
4272         iput(rc->data_inode);
4273         btrfs_put_block_group(rc->block_group);
4274         kfree(rc);
4275         return err;
4276 }
4277
4278 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4279 {
4280         struct btrfs_trans_handle *trans;
4281         int ret, err;
4282
4283         trans = btrfs_start_transaction(root->fs_info->tree_root, 0);
4284         if (IS_ERR(trans))
4285                 return PTR_ERR(trans);
4286
4287         memset(&root->root_item.drop_progress, 0,
4288                 sizeof(root->root_item.drop_progress));
4289         root->root_item.drop_level = 0;
4290         btrfs_set_root_refs(&root->root_item, 0);
4291         ret = btrfs_update_root(trans, root->fs_info->tree_root,
4292                                 &root->root_key, &root->root_item);
4293
4294         err = btrfs_end_transaction(trans, root->fs_info->tree_root);
4295         if (err)
4296                 return err;
4297         return ret;
4298 }
4299
4300 /*
4301  * recover relocation interrupted by system crash.
4302  *
4303  * this function resumes merging reloc trees with corresponding fs trees.
4304  * this is important for keeping the sharing of tree blocks
4305  */
4306 int btrfs_recover_relocation(struct btrfs_root *root)
4307 {
4308         LIST_HEAD(reloc_roots);
4309         struct btrfs_key key;
4310         struct btrfs_root *fs_root;
4311         struct btrfs_root *reloc_root;
4312         struct btrfs_path *path;
4313         struct extent_buffer *leaf;
4314         struct reloc_control *rc = NULL;
4315         struct btrfs_trans_handle *trans;
4316         int ret;
4317         int err = 0;
4318
4319         path = btrfs_alloc_path();
4320         if (!path)
4321                 return -ENOMEM;
4322         path->reada = -1;
4323
4324         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4325         key.type = BTRFS_ROOT_ITEM_KEY;
4326         key.offset = (u64)-1;
4327
4328         while (1) {
4329                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
4330                                         path, 0, 0);
4331                 if (ret < 0) {
4332                         err = ret;
4333                         goto out;
4334                 }
4335                 if (ret > 0) {
4336                         if (path->slots[0] == 0)
4337                                 break;
4338                         path->slots[0]--;
4339                 }
4340                 leaf = path->nodes[0];
4341                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4342                 btrfs_release_path(path);
4343
4344                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4345                     key.type != BTRFS_ROOT_ITEM_KEY)
4346                         break;
4347
4348                 reloc_root = btrfs_read_fs_root(root, &key);
4349                 if (IS_ERR(reloc_root)) {
4350                         err = PTR_ERR(reloc_root);
4351                         goto out;
4352                 }
4353
4354                 list_add(&reloc_root->root_list, &reloc_roots);
4355
4356                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4357                         fs_root = read_fs_root(root->fs_info,
4358                                                reloc_root->root_key.offset);
4359                         if (IS_ERR(fs_root)) {
4360                                 ret = PTR_ERR(fs_root);
4361                                 if (ret != -ENOENT) {
4362                                         err = ret;
4363                                         goto out;
4364                                 }
4365                                 ret = mark_garbage_root(reloc_root);
4366                                 if (ret < 0) {
4367                                         err = ret;
4368                                         goto out;
4369                                 }
4370                         }
4371                 }
4372
4373                 if (key.offset == 0)
4374                         break;
4375
4376                 key.offset--;
4377         }
4378         btrfs_release_path(path);
4379
4380         if (list_empty(&reloc_roots))
4381                 goto out;
4382
4383         rc = alloc_reloc_control(root->fs_info);
4384         if (!rc) {
4385                 err = -ENOMEM;
4386                 goto out;
4387         }
4388
4389         rc->extent_root = root->fs_info->extent_root;
4390
4391         set_reloc_control(rc);
4392
4393         trans = btrfs_join_transaction(rc->extent_root);
4394         if (IS_ERR(trans)) {
4395                 unset_reloc_control(rc);
4396                 err = PTR_ERR(trans);
4397                 goto out_free;
4398         }
4399
4400         rc->merge_reloc_tree = 1;
4401
4402         while (!list_empty(&reloc_roots)) {
4403                 reloc_root = list_entry(reloc_roots.next,
4404                                         struct btrfs_root, root_list);
4405                 list_del(&reloc_root->root_list);
4406
4407                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4408                         list_add_tail(&reloc_root->root_list,
4409                                       &rc->reloc_roots);
4410                         continue;
4411                 }
4412
4413                 fs_root = read_fs_root(root->fs_info,
4414                                        reloc_root->root_key.offset);
4415                 if (IS_ERR(fs_root)) {
4416                         err = PTR_ERR(fs_root);
4417                         goto out_free;
4418                 }
4419
4420                 err = __add_reloc_root(reloc_root);
4421                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4422                 fs_root->reloc_root = reloc_root;
4423         }
4424
4425         err = btrfs_commit_transaction(trans, rc->extent_root);
4426         if (err)
4427                 goto out_free;
4428
4429         merge_reloc_roots(rc);
4430
4431         unset_reloc_control(rc);
4432
4433         trans = btrfs_join_transaction(rc->extent_root);
4434         if (IS_ERR(trans))
4435                 err = PTR_ERR(trans);
4436         else
4437                 err = btrfs_commit_transaction(trans, rc->extent_root);
4438 out_free:
4439         kfree(rc);
4440 out:
4441         if (!list_empty(&reloc_roots))
4442                 free_reloc_roots(&reloc_roots);
4443
4444         btrfs_free_path(path);
4445
4446         if (err == 0) {
4447                 /* cleanup orphan inode in data relocation tree */
4448                 fs_root = read_fs_root(root->fs_info,
4449                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
4450                 if (IS_ERR(fs_root))
4451                         err = PTR_ERR(fs_root);
4452                 else
4453                         err = btrfs_orphan_cleanup(fs_root);
4454         }
4455         return err;
4456 }
4457
4458 /*
4459  * helper to add ordered checksum for data relocation.
4460  *
4461  * cloning checksum properly handles the nodatasum extents.
4462  * it also saves CPU time to re-calculate the checksum.
4463  */
4464 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4465 {
4466         struct btrfs_ordered_sum *sums;
4467         struct btrfs_ordered_extent *ordered;
4468         struct btrfs_root *root = BTRFS_I(inode)->root;
4469         int ret;
4470         u64 disk_bytenr;
4471         u64 new_bytenr;
4472         LIST_HEAD(list);
4473
4474         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4475         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4476
4477         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4478         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
4479                                        disk_bytenr + len - 1, &list, 0);
4480         if (ret)
4481                 goto out;
4482
4483         while (!list_empty(&list)) {
4484                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4485                 list_del_init(&sums->list);
4486
4487                 /*
4488                  * We need to offset the new_bytenr based on where the csum is.
4489                  * We need to do this because we will read in entire prealloc
4490                  * extents but we may have written to say the middle of the
4491                  * prealloc extent, so we need to make sure the csum goes with
4492                  * the right disk offset.
4493                  *
4494                  * We can do this because the data reloc inode refers strictly
4495                  * to the on disk bytes, so we don't have to worry about
4496                  * disk_len vs real len like with real inodes since it's all
4497                  * disk length.
4498                  */
4499                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4500                 sums->bytenr = new_bytenr;
4501
4502                 btrfs_add_ordered_sum(inode, ordered, sums);
4503         }
4504 out:
4505         btrfs_put_ordered_extent(ordered);
4506         return ret;
4507 }
4508
4509 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4510                           struct btrfs_root *root, struct extent_buffer *buf,
4511                           struct extent_buffer *cow)
4512 {
4513         struct reloc_control *rc;
4514         struct backref_node *node;
4515         int first_cow = 0;
4516         int level;
4517         int ret = 0;
4518
4519         rc = root->fs_info->reloc_ctl;
4520         if (!rc)
4521                 return 0;
4522
4523         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4524                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4525
4526         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4527                 if (buf == root->node)
4528                         __update_reloc_root(root, cow->start);
4529         }
4530
4531         level = btrfs_header_level(buf);
4532         if (btrfs_header_generation(buf) <=
4533             btrfs_root_last_snapshot(&root->root_item))
4534                 first_cow = 1;
4535
4536         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4537             rc->create_reloc_tree) {
4538                 WARN_ON(!first_cow && level == 0);
4539
4540                 node = rc->backref_cache.path[level];
4541                 BUG_ON(node->bytenr != buf->start &&
4542                        node->new_bytenr != buf->start);
4543
4544                 drop_node_buffer(node);
4545                 extent_buffer_get(cow);
4546                 node->eb = cow;
4547                 node->new_bytenr = cow->start;
4548
4549                 if (!node->pending) {
4550                         list_move_tail(&node->list,
4551                                        &rc->backref_cache.pending[level]);
4552                         node->pending = 1;
4553                 }
4554
4555                 if (first_cow)
4556                         __mark_block_processed(rc, node);
4557
4558                 if (first_cow && level > 0)
4559                         rc->nodes_relocated += buf->len;
4560         }
4561
4562         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4563                 ret = replace_file_extents(trans, rc, root, cow);
4564         return ret;
4565 }
4566
4567 /*
4568  * called before creating snapshot. it calculates metadata reservation
4569  * requried for relocating tree blocks in the snapshot
4570  */
4571 void btrfs_reloc_pre_snapshot(struct btrfs_trans_handle *trans,
4572                               struct btrfs_pending_snapshot *pending,
4573                               u64 *bytes_to_reserve)
4574 {
4575         struct btrfs_root *root;
4576         struct reloc_control *rc;
4577
4578         root = pending->root;
4579         if (!root->reloc_root)
4580                 return;
4581
4582         rc = root->fs_info->reloc_ctl;
4583         if (!rc->merge_reloc_tree)
4584                 return;
4585
4586         root = root->reloc_root;
4587         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4588         /*
4589          * relocation is in the stage of merging trees. the space
4590          * used by merging a reloc tree is twice the size of
4591          * relocated tree nodes in the worst case. half for cowing
4592          * the reloc tree, half for cowing the fs tree. the space
4593          * used by cowing the reloc tree will be freed after the
4594          * tree is dropped. if we create snapshot, cowing the fs
4595          * tree may use more space than it frees. so we need
4596          * reserve extra space.
4597          */
4598         *bytes_to_reserve += rc->nodes_relocated;
4599 }
4600
4601 /*
4602  * called after snapshot is created. migrate block reservation
4603  * and create reloc root for the newly created snapshot
4604  */
4605 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4606                                struct btrfs_pending_snapshot *pending)
4607 {
4608         struct btrfs_root *root = pending->root;
4609         struct btrfs_root *reloc_root;
4610         struct btrfs_root *new_root;
4611         struct reloc_control *rc;
4612         int ret;
4613
4614         if (!root->reloc_root)
4615                 return 0;
4616
4617         rc = root->fs_info->reloc_ctl;
4618         rc->merging_rsv_size += rc->nodes_relocated;
4619
4620         if (rc->merge_reloc_tree) {
4621                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4622                                               rc->block_rsv,
4623                                               rc->nodes_relocated);
4624                 if (ret)
4625                         return ret;
4626         }
4627
4628         new_root = pending->snap;
4629         reloc_root = create_reloc_root(trans, root->reloc_root,
4630                                        new_root->root_key.objectid);
4631         if (IS_ERR(reloc_root))
4632                 return PTR_ERR(reloc_root);
4633
4634         ret = __add_reloc_root(reloc_root);
4635         BUG_ON(ret < 0);
4636         new_root->reloc_root = reloc_root;
4637
4638         if (rc->create_reloc_tree)
4639                 ret = clone_backref_node(trans, rc, root, reloc_root);
4640         return ret;
4641 }