fs/btrfs/relocation.c

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