fs/btrfs/relocation.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2009 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/pagemap.h>
   8 #include <linux/writeback.h>
   9 #include <linux/blkdev.h>
  10 #include <linux/rbtree.h>
  11 #include <linux/slab.h>
  12 #include "ctree.h"
  13 #include "disk-io.h"
  14 #include "transaction.h"
  15 #include "volumes.h"
  16 #include "locking.h"
  17 #include "btrfs_inode.h"
  18 #include "async-thread.h"
  19 #include "free-space-cache.h"
  20 #include "inode-map.h"
  21 #include "qgroup.h"
  22 #include "print-tree.h"
  23
  24 /*
  25  * backref_node, mapping_node and tree_block start with this
  26  */
  27 struct tree_entry {
  28         struct rb_node rb_node;
  29         u64 bytenr;
  30 };
  31
  32 /*
  33  * present a tree block in the backref cache
  34  */
  35 struct backref_node {
  36         struct rb_node rb_node;
  37         u64 bytenr;
  38
  39         u64 new_bytenr;
  40         /* objectid of tree block owner, can be not uptodate */
  41         u64 owner;
  42         /* link to pending, changed or detached list */
  43         struct list_head list;
  44         /* list of upper level blocks reference this block */
  45         struct list_head upper;
  46         /* list of child blocks in the cache */
  47         struct list_head lower;
  48         /* NULL if this node is not tree root */
  49         struct btrfs_root *root;
  50         /* extent buffer got by COW the block */
  51         struct extent_buffer *eb;
  52         /* level of tree block */
  53         unsigned int level:8;
  54         /* is the block in non-reference counted tree */
  55         unsigned int cowonly:1;
  56         /* 1 if no child node in the cache */
  57         unsigned int lowest:1;
  58         /* is the extent buffer locked */
  59         unsigned int locked:1;
  60         /* has the block been processed */
  61         unsigned int processed:1;
  62         /* have backrefs of this block been checked */
  63         unsigned int checked:1;
  64         /*
  65          * 1 if corresponding block has been cowed but some upper
  66          * level block pointers may not point to the new location
  67          */
  68         unsigned int pending:1;
  69         /*
  70          * 1 if the backref node isn't connected to any other
  71          * backref node.
  72          */
  73         unsigned int detached:1;
  74 };
  75
  76 /*
  77  * present a block pointer in the backref cache
  78  */
  79 struct backref_edge {
  80         struct list_head list[2];
  81         struct backref_node *node[2];
  82 };
  83
  84 #define LOWER   0
  85 #define UPPER   1
  86 #define RELOCATION_RESERVED_NODES       256
  87
  88 struct backref_cache {
  89         /* red black tree of all backref nodes in the cache */
  90         struct rb_root rb_root;
  91         /* for passing backref nodes to btrfs_reloc_cow_block */
  92         struct backref_node *path[BTRFS_MAX_LEVEL];
  93         /*
  94          * list of blocks that have been cowed but some block
  95          * pointers in upper level blocks may not reflect the
  96          * new location
  97          */
  98         struct list_head pending[BTRFS_MAX_LEVEL];
  99         /* list of backref nodes with no child node */
 100         struct list_head leaves;
 101         /* list of blocks that have been cowed in current transaction */
 102         struct list_head changed;
 103         /* list of detached backref node. */
 104         struct list_head detached;
 105
 106         u64 last_trans;
 107
 108         int nr_nodes;
 109         int nr_edges;
 110 };
 111
 112 /*
 113  * map address of tree root to tree
 114  */
 115 struct mapping_node {
 116         struct rb_node rb_node;
 117         u64 bytenr;
 118         void *data;
 119 };
 120
 121 struct mapping_tree {
 122         struct rb_root rb_root;
 123         spinlock_t lock;
 124 };
 125
 126 /*
 127  * present a tree block to process
 128  */
 129 struct tree_block {
 130         struct rb_node rb_node;
 131         u64 bytenr;
 132         struct btrfs_key key;
 133         unsigned int level:8;
 134         unsigned int key_ready:1;
 135 };
 136
 137 #define MAX_EXTENTS 128
 138
 139 struct file_extent_cluster {
 140         u64 start;
 141         u64 end;
 142         u64 boundary[MAX_EXTENTS];
 143         unsigned int nr;
 144 };
 145
 146 struct reloc_control {
 147         /* block group to relocate */
 148         struct btrfs_block_group_cache *block_group;
 149         /* extent tree */
 150         struct btrfs_root *extent_root;
 151         /* inode for moving data */
 152         struct inode *data_inode;
 153
 154         struct btrfs_block_rsv *block_rsv;
 155
 156         struct backref_cache backref_cache;
 157
 158         struct file_extent_cluster cluster;
 159         /* tree blocks have been processed */
 160         struct extent_io_tree processed_blocks;
 161         /* map start of tree root to corresponding reloc tree */
 162         struct mapping_tree reloc_root_tree;
 163         /* list of reloc trees */
 164         struct list_head reloc_roots;
 165         /* list of subvolume trees that get relocated */
 166         struct list_head dirty_subvol_roots;
 167         /* size of metadata reservation for merging reloc trees */
 168         u64 merging_rsv_size;
 169         /* size of relocated tree nodes */
 170         u64 nodes_relocated;
 171         /* reserved size for block group relocation*/
 172         u64 reserved_bytes;
 173
 174         u64 search_start;
 175         u64 extents_found;
 176
 177         unsigned int stage:8;
 178         unsigned int create_reloc_tree:1;
 179         unsigned int merge_reloc_tree:1;
 180         unsigned int found_file_extent:1;
 181 };
 182
 183 /* stages of data relocation */
 184 #define MOVE_DATA_EXTENTS       0
 185 #define UPDATE_DATA_PTRS        1
 186
 187 static void remove_backref_node(struct backref_cache *cache,
 188                                 struct backref_node *node);
 189 static void __mark_block_processed(struct reloc_control *rc,
 190                                    struct backref_node *node);
 191
 192 static void mapping_tree_init(struct mapping_tree *tree)
 193 {
 194         tree->rb_root = RB_ROOT;
 195         spin_lock_init(&tree->lock);
 196 }
 197
 198 static void backref_cache_init(struct backref_cache *cache)
 199 {
 200         int i;
 201         cache->rb_root = RB_ROOT;
 202         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 203                 INIT_LIST_HEAD(&cache->pending[i]);
 204         INIT_LIST_HEAD(&cache->changed);
 205         INIT_LIST_HEAD(&cache->detached);
 206         INIT_LIST_HEAD(&cache->leaves);
 207 }
 208
 209 static void backref_cache_cleanup(struct backref_cache *cache)
 210 {
 211         struct backref_node *node;
 212         int i;
 213
 214         while (!list_empty(&cache->detached)) {
 215                 node = list_entry(cache->detached.next,
 216                                   struct backref_node, list);
 217                 remove_backref_node(cache, node);
 218         }
 219
 220         while (!list_empty(&cache->leaves)) {
 221                 node = list_entry(cache->leaves.next,
 222                                   struct backref_node, lower);
 223                 remove_backref_node(cache, node);
 224         }
 225
 226         cache->last_trans = 0;
 227
 228         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 229                 ASSERT(list_empty(&cache->pending[i]));
 230         ASSERT(list_empty(&cache->changed));
 231         ASSERT(list_empty(&cache->detached));
 232         ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
 233         ASSERT(!cache->nr_nodes);
 234         ASSERT(!cache->nr_edges);
 235 }
 236
 237 static struct backref_node *alloc_backref_node(struct backref_cache *cache)
 238 {
 239         struct backref_node *node;
 240
 241         node = kzalloc(sizeof(*node), GFP_NOFS);
 242         if (node) {
 243                 INIT_LIST_HEAD(&node->list);
 244                 INIT_LIST_HEAD(&node->upper);
 245                 INIT_LIST_HEAD(&node->lower);
 246                 RB_CLEAR_NODE(&node->rb_node);
 247                 cache->nr_nodes++;
 248         }
 249         return node;
 250 }
 251
 252 static void free_backref_node(struct backref_cache *cache,
 253                               struct backref_node *node)
 254 {
 255         if (node) {
 256                 cache->nr_nodes--;
 257                 kfree(node);
 258         }
 259 }
 260
 261 static struct backref_edge *alloc_backref_edge(struct backref_cache *cache)
 262 {
 263         struct backref_edge *edge;
 264
 265         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 266         if (edge)
 267                 cache->nr_edges++;
 268         return edge;
 269 }
 270
 271 static void free_backref_edge(struct backref_cache *cache,
 272                               struct backref_edge *edge)
 273 {
 274         if (edge) {
 275                 cache->nr_edges--;
 276                 kfree(edge);
 277         }
 278 }
 279
 280 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 281                                    struct rb_node *node)
 282 {
 283         struct rb_node **p = &root->rb_node;
 284         struct rb_node *parent = NULL;
 285         struct tree_entry *entry;
 286
 287         while (*p) {
 288                 parent = *p;
 289                 entry = rb_entry(parent, struct tree_entry, rb_node);
 290
 291                 if (bytenr < entry->bytenr)
 292                         p = &(*p)->rb_left;
 293                 else if (bytenr > entry->bytenr)
 294                         p = &(*p)->rb_right;
 295                 else
 296                         return parent;
 297         }
 298
 299         rb_link_node(node, parent, p);
 300         rb_insert_color(node, root);
 301         return NULL;
 302 }
 303
 304 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 305 {
 306         struct rb_node *n = root->rb_node;
 307         struct tree_entry *entry;
 308
 309         while (n) {
 310                 entry = rb_entry(n, struct tree_entry, rb_node);
 311
 312                 if (bytenr < entry->bytenr)
 313                         n = n->rb_left;
 314                 else if (bytenr > entry->bytenr)
 315                         n = n->rb_right;
 316                 else
 317                         return n;
 318         }
 319         return NULL;
 320 }
 321
 322 static void backref_tree_panic(struct rb_node *rb_node, int errno, u64 bytenr)
 323 {
 324
 325         struct btrfs_fs_info *fs_info = NULL;
 326         struct backref_node *bnode = rb_entry(rb_node, struct backref_node,
 327                                               rb_node);
 328         if (bnode->root)
 329                 fs_info = bnode->root->fs_info;
 330         btrfs_panic(fs_info, errno,
 331                     "Inconsistency in backref cache found at offset %llu",
 332                     bytenr);
 333 }
 334
 335 /*
 336  * walk up backref nodes until reach node presents tree root
 337  */
 338 static struct backref_node *walk_up_backref(struct backref_node *node,
 339                                             struct backref_edge *edges[],
 340                                             int *index)
 341 {
 342         struct backref_edge *edge;
 343         int idx = *index;
 344
 345         while (!list_empty(&node->upper)) {
 346                 edge = list_entry(node->upper.next,
 347                                   struct backref_edge, list[LOWER]);
 348                 edges[idx++] = edge;
 349                 node = edge->node[UPPER];
 350         }
 351         BUG_ON(node->detached);
 352         *index = idx;
 353         return node;
 354 }
 355
 356 /*
 357  * walk down backref nodes to find start of next reference path
 358  */
 359 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 360                                               int *index)
 361 {
 362         struct backref_edge *edge;
 363         struct backref_node *lower;
 364         int idx = *index;
 365
 366         while (idx > 0) {
 367                 edge = edges[idx - 1];
 368                 lower = edge->node[LOWER];
 369                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 370                         idx--;
 371                         continue;
 372                 }
 373                 edge = list_entry(edge->list[LOWER].next,
 374                                   struct backref_edge, list[LOWER]);
 375                 edges[idx - 1] = edge;
 376                 *index = idx;
 377                 return edge->node[UPPER];
 378         }
 379         *index = 0;
 380         return NULL;
 381 }
 382
 383 static void unlock_node_buffer(struct backref_node *node)
 384 {
 385         if (node->locked) {
 386                 btrfs_tree_unlock(node->eb);
 387                 node->locked = 0;
 388         }
 389 }
 390
 391 static void drop_node_buffer(struct backref_node *node)
 392 {
 393         if (node->eb) {
 394                 unlock_node_buffer(node);
 395                 free_extent_buffer(node->eb);
 396                 node->eb = NULL;
 397         }
 398 }
 399
 400 static void drop_backref_node(struct backref_cache *tree,
 401                               struct backref_node *node)
 402 {
 403         BUG_ON(!list_empty(&node->upper));
 404
 405         drop_node_buffer(node);
 406         list_del(&node->list);
 407         list_del(&node->lower);
 408         if (!RB_EMPTY_NODE(&node->rb_node))
 409                 rb_erase(&node->rb_node, &tree->rb_root);
 410         free_backref_node(tree, node);
 411 }
 412
 413 /*
 414  * remove a backref node from the backref cache
 415  */
 416 static void remove_backref_node(struct backref_cache *cache,
 417                                 struct backref_node *node)
 418 {
 419         struct backref_node *upper;
 420         struct backref_edge *edge;
 421
 422         if (!node)
 423                 return;
 424
 425         BUG_ON(!node->lowest && !node->detached);
 426         while (!list_empty(&node->upper)) {
 427                 edge = list_entry(node->upper.next, struct backref_edge,
 428                                   list[LOWER]);
 429                 upper = edge->node[UPPER];
 430                 list_del(&edge->list[LOWER]);
 431                 list_del(&edge->list[UPPER]);
 432                 free_backref_edge(cache, edge);
 433
 434                 if (RB_EMPTY_NODE(&upper->rb_node)) {
 435                         BUG_ON(!list_empty(&node->upper));
 436                         drop_backref_node(cache, node);
 437                         node = upper;
 438                         node->lowest = 1;
 439                         continue;
 440                 }
 441                 /*
 442                  * add the node to leaf node list if no other
 443                  * child block cached.
 444                  */
 445                 if (list_empty(&upper->lower)) {
 446                         list_add_tail(&upper->lower, &cache->leaves);
 447                         upper->lowest = 1;
 448                 }
 449         }
 450
 451         drop_backref_node(cache, node);
 452 }
 453
 454 static void update_backref_node(struct backref_cache *cache,
 455                                 struct backref_node *node, u64 bytenr)
 456 {
 457         struct rb_node *rb_node;
 458         rb_erase(&node->rb_node, &cache->rb_root);
 459         node->bytenr = bytenr;
 460         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 461         if (rb_node)
 462                 backref_tree_panic(rb_node, -EEXIST, bytenr);
 463 }
 464
 465 /*
 466  * update backref cache after a transaction commit
 467  */
 468 static int update_backref_cache(struct btrfs_trans_handle *trans,
 469                                 struct backref_cache *cache)
 470 {
 471         struct backref_node *node;
 472         int level = 0;
 473
 474         if (cache->last_trans == 0) {
 475                 cache->last_trans = trans->transid;
 476                 return 0;
 477         }
 478
 479         if (cache->last_trans == trans->transid)
 480                 return 0;
 481
 482         /*
 483          * detached nodes are used to avoid unnecessary backref
 484          * lookup. transaction commit changes the extent tree.
 485          * so the detached nodes are no longer useful.
 486          */
 487         while (!list_empty(&cache->detached)) {
 488                 node = list_entry(cache->detached.next,
 489                                   struct backref_node, list);
 490                 remove_backref_node(cache, node);
 491         }
 492
 493         while (!list_empty(&cache->changed)) {
 494                 node = list_entry(cache->changed.next,
 495                                   struct backref_node, list);
 496                 list_del_init(&node->list);
 497                 BUG_ON(node->pending);
 498                 update_backref_node(cache, node, node->new_bytenr);
 499         }
 500
 501         /*
 502          * some nodes can be left in the pending list if there were
 503          * errors during processing the pending nodes.
 504          */
 505         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
 506                 list_for_each_entry(node, &cache->pending[level], list) {
 507                         BUG_ON(!node->pending);
 508                         if (node->bytenr == node->new_bytenr)
 509                                 continue;
 510                         update_backref_node(cache, node, node->new_bytenr);
 511                 }
 512         }
 513
 514         cache->last_trans = 0;
 515         return 1;
 516 }
 517
 518
 519 static int should_ignore_root(struct btrfs_root *root)
 520 {
 521         struct btrfs_root *reloc_root;
 522
 523         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 524                 return 0;
 525
 526         reloc_root = root->reloc_root;
 527         if (!reloc_root)
 528                 return 0;
 529
 530         if (btrfs_root_last_snapshot(&reloc_root->root_item) ==
 531             root->fs_info->running_transaction->transid - 1)
 532                 return 0;
 533         /*
 534          * if there is reloc tree and it was created in previous
 535          * transaction backref lookup can find the reloc tree,
 536          * so backref node for the fs tree root is useless for
 537          * relocation.
 538          */
 539         return 1;
 540 }
 541 /*
 542  * find reloc tree by address of tree root
 543  */
 544 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 545                                           u64 bytenr)
 546 {
 547         struct rb_node *rb_node;
 548         struct mapping_node *node;
 549         struct btrfs_root *root = NULL;
 550
 551         spin_lock(&rc->reloc_root_tree.lock);
 552         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 553         if (rb_node) {
 554                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 555                 root = (struct btrfs_root *)node->data;
 556         }
 557         spin_unlock(&rc->reloc_root_tree.lock);
 558         return root;
 559 }
 560
 561 static int is_cowonly_root(u64 root_objectid)
 562 {
 563         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 564             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 565             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 566             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 567             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 568             root_objectid == BTRFS_CSUM_TREE_OBJECTID ||
 569             root_objectid == BTRFS_UUID_TREE_OBJECTID ||
 570             root_objectid == BTRFS_QUOTA_TREE_OBJECTID ||
 571             root_objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
 572                 return 1;
 573         return 0;
 574 }
 575
 576 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 577                                         u64 root_objectid)
 578 {
 579         struct btrfs_key key;
 580
 581         key.objectid = root_objectid;
 582         key.type = BTRFS_ROOT_ITEM_KEY;
 583         if (is_cowonly_root(root_objectid))
 584                 key.offset = 0;
 585         else
 586                 key.offset = (u64)-1;
 587
 588         return btrfs_get_fs_root(fs_info, &key, false);
 589 }
 590
 591 static noinline_for_stack
 592 int find_inline_backref(struct extent_buffer *leaf, int slot,
 593                         unsigned long *ptr, unsigned long *end)
 594 {
 595         struct btrfs_key key;
 596         struct btrfs_extent_item *ei;
 597         struct btrfs_tree_block_info *bi;
 598         u32 item_size;
 599
 600         btrfs_item_key_to_cpu(leaf, &key, slot);
 601
 602         item_size = btrfs_item_size_nr(leaf, slot);
 603         if (item_size < sizeof(*ei)) {
 604                 btrfs_print_v0_err(leaf->fs_info);
 605                 btrfs_handle_fs_error(leaf->fs_info, -EINVAL, NULL);
 606                 return 1;
 607         }
 608         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 609         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 610                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 611
 612         if (key.type == BTRFS_EXTENT_ITEM_KEY &&
 613             item_size <= sizeof(*ei) + sizeof(*bi)) {
 614                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 615                 return 1;
 616         }
 617         if (key.type == BTRFS_METADATA_ITEM_KEY &&
 618             item_size <= sizeof(*ei)) {
 619                 WARN_ON(item_size < sizeof(*ei));
 620                 return 1;
 621         }
 622
 623         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 624                 bi = (struct btrfs_tree_block_info *)(ei + 1);
 625                 *ptr = (unsigned long)(bi + 1);
 626         } else {
 627                 *ptr = (unsigned long)(ei + 1);
 628         }
 629         *end = (unsigned long)ei + item_size;
 630         return 0;
 631 }
 632
 633 /*
 634  * build backref tree for a given tree block. root of the backref tree
 635  * corresponds the tree block, leaves of the backref tree correspond
 636  * roots of b-trees that reference the tree block.
 637  *
 638  * the basic idea of this function is check backrefs of a given block
 639  * to find upper level blocks that reference the block, and then check
 640  * backrefs of these upper level blocks recursively. the recursion stop
 641  * when tree root is reached or backrefs for the block is cached.
 642  *
 643  * NOTE: if we find backrefs for a block are cached, we know backrefs
 644  * for all upper level blocks that directly/indirectly reference the
 645  * block are also cached.
 646  */
 647 static noinline_for_stack
 648 struct backref_node *build_backref_tree(struct reloc_control *rc,
 649                                         struct btrfs_key *node_key,
 650                                         int level, u64 bytenr)
 651 {
 652         struct backref_cache *cache = &rc->backref_cache;
 653         struct btrfs_path *path1; /* For searching extent root */
 654         struct btrfs_path *path2; /* For searching parent of TREE_BLOCK_REF */
 655         struct extent_buffer *eb;
 656         struct btrfs_root *root;
 657         struct backref_node *cur;
 658         struct backref_node *upper;
 659         struct backref_node *lower;
 660         struct backref_node *node = NULL;
 661         struct backref_node *exist = NULL;
 662         struct backref_edge *edge;
 663         struct rb_node *rb_node;
 664         struct btrfs_key key;
 665         unsigned long end;
 666         unsigned long ptr;
 667         LIST_HEAD(list); /* Pending edge list, upper node needs to be checked */
 668         LIST_HEAD(useless);
 669         int cowonly;
 670         int ret;
 671         int err = 0;
 672         bool need_check = true;
 673
 674         path1 = btrfs_alloc_path();
 675         path2 = btrfs_alloc_path();
 676         if (!path1 || !path2) {
 677                 err = -ENOMEM;
 678                 goto out;
 679         }
 680         path1->reada = READA_FORWARD;
 681         path2->reada = READA_FORWARD;
 682
 683         node = alloc_backref_node(cache);
 684         if (!node) {
 685                 err = -ENOMEM;
 686                 goto out;
 687         }
 688
 689         node->bytenr = bytenr;
 690         node->level = level;
 691         node->lowest = 1;
 692         cur = node;
 693 again:
 694         end = 0;
 695         ptr = 0;
 696         key.objectid = cur->bytenr;
 697         key.type = BTRFS_METADATA_ITEM_KEY;
 698         key.offset = (u64)-1;
 699
 700         path1->search_commit_root = 1;
 701         path1->skip_locking = 1;
 702         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 703                                 0, 0);
 704         if (ret < 0) {
 705                 err = ret;
 706                 goto out;
 707         }
 708         ASSERT(ret);
 709         ASSERT(path1->slots[0]);
 710
 711         path1->slots[0]--;
 712
 713         WARN_ON(cur->checked);
 714         if (!list_empty(&cur->upper)) {
 715                 /*
 716                  * the backref was added previously when processing
 717                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 718                  */
 719                 ASSERT(list_is_singular(&cur->upper));
 720                 edge = list_entry(cur->upper.next, struct backref_edge,
 721                                   list[LOWER]);
 722                 ASSERT(list_empty(&edge->list[UPPER]));
 723                 exist = edge->node[UPPER];
 724                 /*
 725                  * add the upper level block to pending list if we need
 726                  * check its backrefs
 727                  */
 728                 if (!exist->checked)
 729                         list_add_tail(&edge->list[UPPER], &list);
 730         } else {
 731                 exist = NULL;
 732         }
 733
 734         while (1) {
 735                 cond_resched();
 736                 eb = path1->nodes[0];
 737
 738                 if (ptr >= end) {
 739                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 740                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 741                                 if (ret < 0) {
 742                                         err = ret;
 743                                         goto out;
 744                                 }
 745                                 if (ret > 0)
 746                                         break;
 747                                 eb = path1->nodes[0];
 748                         }
 749
 750                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 751                         if (key.objectid != cur->bytenr) {
 752                                 WARN_ON(exist);
 753                                 break;
 754                         }
 755
 756                         if (key.type == BTRFS_EXTENT_ITEM_KEY ||
 757                             key.type == BTRFS_METADATA_ITEM_KEY) {
 758                                 ret = find_inline_backref(eb, path1->slots[0],
 759                                                           &ptr, &end);
 760                                 if (ret)
 761                                         goto next;
 762                         }
 763                 }
 764
 765                 if (ptr < end) {
 766                         /* update key for inline back ref */
 767                         struct btrfs_extent_inline_ref *iref;
 768                         int type;
 769                         iref = (struct btrfs_extent_inline_ref *)ptr;
 770                         type = btrfs_get_extent_inline_ref_type(eb, iref,
 771                                                         BTRFS_REF_TYPE_BLOCK);
 772                         if (type == BTRFS_REF_TYPE_INVALID) {
 773                                 err = -EUCLEAN;
 774                                 goto out;
 775                         }
 776                         key.type = type;
 777                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 778
 779                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 780                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 781                 }
 782
 783                 /*
 784                  * Parent node found and matches current inline ref, no need to
 785                  * rebuild this node for this inline ref.
 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                 /* SHARED_BLOCK_REF means key.offset is the parent bytenr */
 797                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 798                         if (key.objectid == key.offset) {
 799                                 /*
 800                                  * Only root blocks of reloc trees use backref
 801                                  * pointing to itself.
 802                                  */
 803                                 root = find_reloc_root(rc, cur->bytenr);
 804                                 ASSERT(root);
 805                                 cur->root = root;
 806                                 break;
 807                         }
 808
 809                         edge = alloc_backref_edge(cache);
 810                         if (!edge) {
 811                                 err = -ENOMEM;
 812                                 goto out;
 813                         }
 814                         rb_node = tree_search(&cache->rb_root, key.offset);
 815                         if (!rb_node) {
 816                                 upper = alloc_backref_node(cache);
 817                                 if (!upper) {
 818                                         free_backref_edge(cache, edge);
 819                                         err = -ENOMEM;
 820                                         goto out;
 821                                 }
 822                                 upper->bytenr = key.offset;
 823                                 upper->level = cur->level + 1;
 824                                 /*
 825                                  *  backrefs for the upper level block isn't
 826                                  *  cached, add the block to pending list
 827                                  */
 828                                 list_add_tail(&edge->list[UPPER], &list);
 829                         } else {
 830                                 upper = rb_entry(rb_node, struct backref_node,
 831                                                  rb_node);
 832                                 ASSERT(upper->checked);
 833                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 834                         }
 835                         list_add_tail(&edge->list[LOWER], &cur->upper);
 836                         edge->node[LOWER] = cur;
 837                         edge->node[UPPER] = upper;
 838
 839                         goto next;
 840                 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
 841                         err = -EINVAL;
 842                         btrfs_print_v0_err(rc->extent_root->fs_info);
 843                         btrfs_handle_fs_error(rc->extent_root->fs_info, err,
 844                                               NULL);
 845                         goto out;
 846                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 847                         goto next;
 848                 }
 849
 850                 /*
 851                  * key.type == BTRFS_TREE_BLOCK_REF_KEY, inline ref offset
 852                  * means the root objectid. We need to search the tree to get
 853                  * its parent bytenr.
 854                  */
 855                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 856                 if (IS_ERR(root)) {
 857                         err = PTR_ERR(root);
 858                         goto out;
 859                 }
 860
 861                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 862                         cur->cowonly = 1;
 863
 864                 if (btrfs_root_level(&root->root_item) == cur->level) {
 865                         /* tree root */
 866                         ASSERT(btrfs_root_bytenr(&root->root_item) ==
 867                                cur->bytenr);
 868                         if (should_ignore_root(root))
 869                                 list_add(&cur->list, &useless);
 870                         else
 871                                 cur->root = root;
 872                         break;
 873                 }
 874
 875                 level = cur->level + 1;
 876
 877                 /* Search the tree to find parent blocks referring the block. */
 878                 path2->search_commit_root = 1;
 879                 path2->skip_locking = 1;
 880                 path2->lowest_level = level;
 881                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 882                 path2->lowest_level = 0;
 883                 if (ret < 0) {
 884                         err = ret;
 885                         goto out;
 886                 }
 887                 if (ret > 0 && path2->slots[level] > 0)
 888                         path2->slots[level]--;
 889
 890                 eb = path2->nodes[level];
 891                 if (btrfs_node_blockptr(eb, path2->slots[level]) !=
 892                     cur->bytenr) {
 893                         btrfs_err(root->fs_info,
 894         "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
 895                                   cur->bytenr, level - 1,
 896                                   root->root_key.objectid,
 897                                   node_key->objectid, node_key->type,
 898                                   node_key->offset);
 899                         err = -ENOENT;
 900                         goto out;
 901                 }
 902                 lower = cur;
 903                 need_check = true;
 904
 905                 /* Add all nodes and edges in the path */
 906                 for (; level < BTRFS_MAX_LEVEL; level++) {
 907                         if (!path2->nodes[level]) {
 908                                 ASSERT(btrfs_root_bytenr(&root->root_item) ==
 909                                        lower->bytenr);
 910                                 if (should_ignore_root(root))
 911                                         list_add(&lower->list, &useless);
 912                                 else
 913                                         lower->root = root;
 914                                 break;
 915                         }
 916
 917                         edge = alloc_backref_edge(cache);
 918                         if (!edge) {
 919                                 err = -ENOMEM;
 920                                 goto out;
 921                         }
 922
 923                         eb = path2->nodes[level];
 924                         rb_node = tree_search(&cache->rb_root, eb->start);
 925                         if (!rb_node) {
 926                                 upper = alloc_backref_node(cache);
 927                                 if (!upper) {
 928                                         free_backref_edge(cache, edge);
 929                                         err = -ENOMEM;
 930                                         goto out;
 931                                 }
 932                                 upper->bytenr = eb->start;
 933                                 upper->owner = btrfs_header_owner(eb);
 934                                 upper->level = lower->level + 1;
 935                                 if (!test_bit(BTRFS_ROOT_REF_COWS,
 936                                               &root->state))
 937                                         upper->cowonly = 1;
 938
 939                                 /*
 940                                  * if we know the block isn't shared
 941                                  * we can void checking its backrefs.
 942                                  */
 943                                 if (btrfs_block_can_be_shared(root, eb))
 944                                         upper->checked = 0;
 945                                 else
 946                                         upper->checked = 1;
 947
 948                                 /*
 949                                  * add the block to pending list if we
 950                                  * need check its backrefs, we only do this once
 951                                  * while walking up a tree as we will catch
 952                                  * anything else later on.
 953                                  */
 954                                 if (!upper->checked && need_check) {
 955                                         need_check = false;
 956                                         list_add_tail(&edge->list[UPPER],
 957                                                       &list);
 958                                 } else {
 959                                         if (upper->checked)
 960                                                 need_check = true;
 961                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 962                                 }
 963                         } else {
 964                                 upper = rb_entry(rb_node, struct backref_node,
 965                                                  rb_node);
 966                                 ASSERT(upper->checked);
 967                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 968                                 if (!upper->owner)
 969                                         upper->owner = btrfs_header_owner(eb);
 970                         }
 971                         list_add_tail(&edge->list[LOWER], &lower->upper);
 972                         edge->node[LOWER] = lower;
 973                         edge->node[UPPER] = upper;
 974
 975                         if (rb_node)
 976                                 break;
 977                         lower = upper;
 978                         upper = NULL;
 979                 }
 980                 btrfs_release_path(path2);
 981 next:
 982                 if (ptr < end) {
 983                         ptr += btrfs_extent_inline_ref_size(key.type);
 984                         if (ptr >= end) {
 985                                 WARN_ON(ptr > end);
 986                                 ptr = 0;
 987                                 end = 0;
 988                         }
 989                 }
 990                 if (ptr >= end)
 991                         path1->slots[0]++;
 992         }
 993         btrfs_release_path(path1);
 994
 995         cur->checked = 1;
 996         WARN_ON(exist);
 997
 998         /* the pending list isn't empty, take the first block to process */
 999         if (!list_empty(&list)) {
1000                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1001                 list_del_init(&edge->list[UPPER]);
1002                 cur = edge->node[UPPER];
1003                 goto again;
1004         }
1005
1006         /*
1007          * everything goes well, connect backref nodes and insert backref nodes
1008          * into the cache.
1009          */
1010         ASSERT(node->checked);
1011         cowonly = node->cowonly;
1012         if (!cowonly) {
1013                 rb_node = tree_insert(&cache->rb_root, node->bytenr,
1014                                       &node->rb_node);
1015                 if (rb_node)
1016                         backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1017                 list_add_tail(&node->lower, &cache->leaves);
1018         }
1019
1020         list_for_each_entry(edge, &node->upper, list[LOWER])
1021                 list_add_tail(&edge->list[UPPER], &list);
1022
1023         while (!list_empty(&list)) {
1024                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
1025                 list_del_init(&edge->list[UPPER]);
1026                 upper = edge->node[UPPER];
1027                 if (upper->detached) {
1028                         list_del(&edge->list[LOWER]);
1029                         lower = edge->node[LOWER];
1030                         free_backref_edge(cache, edge);
1031                         if (list_empty(&lower->upper))
1032                                 list_add(&lower->list, &useless);
1033                         continue;
1034                 }
1035
1036                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
1037                         if (upper->lowest) {
1038                                 list_del_init(&upper->lower);
1039                                 upper->lowest = 0;
1040                         }
1041
1042                         list_add_tail(&edge->list[UPPER], &upper->lower);
1043                         continue;
1044                 }
1045
1046                 if (!upper->checked) {
1047                         /*
1048                          * Still want to blow up for developers since this is a
1049                          * logic bug.
1050                          */
1051                         ASSERT(0);
1052                         err = -EINVAL;
1053                         goto out;
1054                 }
1055                 if (cowonly != upper->cowonly) {
1056                         ASSERT(0);
1057                         err = -EINVAL;
1058                         goto out;
1059                 }
1060
1061                 if (!cowonly) {
1062                         rb_node = tree_insert(&cache->rb_root, upper->bytenr,
1063                                               &upper->rb_node);
1064                         if (rb_node)
1065                                 backref_tree_panic(rb_node, -EEXIST,
1066                                                    upper->bytenr);
1067                 }
1068
1069                 list_add_tail(&edge->list[UPPER], &upper->lower);
1070
1071                 list_for_each_entry(edge, &upper->upper, list[LOWER])
1072                         list_add_tail(&edge->list[UPPER], &list);
1073         }
1074         /*
1075          * process useless backref nodes. backref nodes for tree leaves
1076          * are deleted from the cache. backref nodes for upper level
1077          * tree blocks are left in the cache to avoid unnecessary backref
1078          * lookup.
1079          */
1080         while (!list_empty(&useless)) {
1081                 upper = list_entry(useless.next, struct backref_node, list);
1082                 list_del_init(&upper->list);
1083                 ASSERT(list_empty(&upper->upper));
1084                 if (upper == node)
1085                         node = NULL;
1086                 if (upper->lowest) {
1087                         list_del_init(&upper->lower);
1088                         upper->lowest = 0;
1089                 }
1090                 while (!list_empty(&upper->lower)) {
1091                         edge = list_entry(upper->lower.next,
1092                                           struct backref_edge, list[UPPER]);
1093                         list_del(&edge->list[UPPER]);
1094                         list_del(&edge->list[LOWER]);
1095                         lower = edge->node[LOWER];
1096                         free_backref_edge(cache, edge);
1097
1098                         if (list_empty(&lower->upper))
1099                                 list_add(&lower->list, &useless);
1100                 }
1101                 __mark_block_processed(rc, upper);
1102                 if (upper->level > 0) {
1103                         list_add(&upper->list, &cache->detached);
1104                         upper->detached = 1;
1105                 } else {
1106                         rb_erase(&upper->rb_node, &cache->rb_root);
1107                         free_backref_node(cache, upper);
1108                 }
1109         }
1110 out:
1111         btrfs_free_path(path1);
1112         btrfs_free_path(path2);
1113         if (err) {
1114                 while (!list_empty(&useless)) {
1115                         lower = list_entry(useless.next,
1116                                            struct backref_node, list);
1117                         list_del_init(&lower->list);
1118                 }
1119                 while (!list_empty(&list)) {
1120                         edge = list_first_entry(&list, struct backref_edge,
1121                                                 list[UPPER]);
1122                         list_del(&edge->list[UPPER]);
1123                         list_del(&edge->list[LOWER]);
1124                         lower = edge->node[LOWER];
1125                         upper = edge->node[UPPER];
1126                         free_backref_edge(cache, edge);
1127
1128                         /*
1129                          * Lower is no longer linked to any upper backref nodes
1130                          * and isn't in the cache, we can free it ourselves.
1131                          */
1132                         if (list_empty(&lower->upper) &&
1133                             RB_EMPTY_NODE(&lower->rb_node))
1134                                 list_add(&lower->list, &useless);
1135
1136                         if (!RB_EMPTY_NODE(&upper->rb_node))
1137                                 continue;
1138
1139                         /* Add this guy's upper edges to the list to process */
1140                         list_for_each_entry(edge, &upper->upper, list[LOWER])
1141                                 list_add_tail(&edge->list[UPPER], &list);
1142                         if (list_empty(&upper->upper))
1143                                 list_add(&upper->list, &useless);
1144                 }
1145
1146                 while (!list_empty(&useless)) {
1147                         lower = list_entry(useless.next,
1148                                            struct backref_node, list);
1149                         list_del_init(&lower->list);
1150                         if (lower == node)
1151                                 node = NULL;
1152                         free_backref_node(cache, lower);
1153                 }
1154
1155                 free_backref_node(cache, node);
1156                 return ERR_PTR(err);
1157         }
1158         ASSERT(!node || !node->detached);
1159         return node;
1160 }
1161
1162 /*
1163  * helper to add backref node for the newly created snapshot.
1164  * the backref node is created by cloning backref node that
1165  * corresponds to root of source tree
1166  */
1167 static int clone_backref_node(struct btrfs_trans_handle *trans,
1168                               struct reloc_control *rc,
1169                               struct btrfs_root *src,
1170                               struct btrfs_root *dest)
1171 {
1172         struct btrfs_root *reloc_root = src->reloc_root;
1173         struct backref_cache *cache = &rc->backref_cache;
1174         struct backref_node *node = NULL;
1175         struct backref_node *new_node;
1176         struct backref_edge *edge;
1177         struct backref_edge *new_edge;
1178         struct rb_node *rb_node;
1179
1180         if (cache->last_trans > 0)
1181                 update_backref_cache(trans, cache);
1182
1183         rb_node = tree_search(&cache->rb_root, src->commit_root->start);
1184         if (rb_node) {
1185                 node = rb_entry(rb_node, struct backref_node, rb_node);
1186                 if (node->detached)
1187                         node = NULL;
1188                 else
1189                         BUG_ON(node->new_bytenr != reloc_root->node->start);
1190         }
1191
1192         if (!node) {
1193                 rb_node = tree_search(&cache->rb_root,
1194                                       reloc_root->commit_root->start);
1195                 if (rb_node) {
1196                         node = rb_entry(rb_node, struct backref_node,
1197                                         rb_node);
1198                         BUG_ON(node->detached);
1199                 }
1200         }
1201
1202         if (!node)
1203                 return 0;
1204
1205         new_node = alloc_backref_node(cache);
1206         if (!new_node)
1207                 return -ENOMEM;
1208
1209         new_node->bytenr = dest->node->start;
1210         new_node->level = node->level;
1211         new_node->lowest = node->lowest;
1212         new_node->checked = 1;
1213         new_node->root = dest;
1214
1215         if (!node->lowest) {
1216                 list_for_each_entry(edge, &node->lower, list[UPPER]) {
1217                         new_edge = alloc_backref_edge(cache);
1218                         if (!new_edge)
1219                                 goto fail;
1220
1221                         new_edge->node[UPPER] = new_node;
1222                         new_edge->node[LOWER] = edge->node[LOWER];
1223                         list_add_tail(&new_edge->list[UPPER],
1224                                       &new_node->lower);
1225                 }
1226         } else {
1227                 list_add_tail(&new_node->lower, &cache->leaves);
1228         }
1229
1230         rb_node = tree_insert(&cache->rb_root, new_node->bytenr,
1231                               &new_node->rb_node);
1232         if (rb_node)
1233                 backref_tree_panic(rb_node, -EEXIST, new_node->bytenr);
1234
1235         if (!new_node->lowest) {
1236                 list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
1237                         list_add_tail(&new_edge->list[LOWER],
1238                                       &new_edge->node[LOWER]->upper);
1239                 }
1240         }
1241         return 0;
1242 fail:
1243         while (!list_empty(&new_node->lower)) {
1244                 new_edge = list_entry(new_node->lower.next,
1245                                       struct backref_edge, list[UPPER]);
1246                 list_del(&new_edge->list[UPPER]);
1247                 free_backref_edge(cache, new_edge);
1248         }
1249         free_backref_node(cache, new_node);
1250         return -ENOMEM;
1251 }
1252
1253 /*
1254  * helper to add 'address of tree root -> reloc tree' mapping
1255  */
1256 static int __must_check __add_reloc_root(struct btrfs_root *root)
1257 {
1258         struct btrfs_fs_info *fs_info = root->fs_info;
1259         struct rb_node *rb_node;
1260         struct mapping_node *node;
1261         struct reloc_control *rc = fs_info->reloc_ctl;
1262
1263         node = kmalloc(sizeof(*node), GFP_NOFS);
1264         if (!node)
1265                 return -ENOMEM;
1266
1267         node->bytenr = root->node->start;
1268         node->data = root;
1269
1270         spin_lock(&rc->reloc_root_tree.lock);
1271         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1272                               node->bytenr, &node->rb_node);
1273         spin_unlock(&rc->reloc_root_tree.lock);
1274         if (rb_node) {
1275                 btrfs_panic(fs_info, -EEXIST,
1276                             "Duplicate root found for start=%llu while inserting into relocation tree",
1277                             node->bytenr);
1278         }
1279
1280         list_add_tail(&root->root_list, &rc->reloc_roots);
1281         return 0;
1282 }
1283
1284 /*
1285  * helper to delete the 'address of tree root -> reloc tree'
1286  * mapping
1287  */
1288 static void __del_reloc_root(struct btrfs_root *root)
1289 {
1290         struct btrfs_fs_info *fs_info = root->fs_info;
1291         struct rb_node *rb_node;
1292         struct mapping_node *node = NULL;
1293         struct reloc_control *rc = fs_info->reloc_ctl;
1294
1295         if (rc && root->node) {
1296                 spin_lock(&rc->reloc_root_tree.lock);
1297                 rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1298                                       root->node->start);
1299                 if (rb_node) {
1300                         node = rb_entry(rb_node, struct mapping_node, rb_node);
1301                         rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1302                 }
1303                 spin_unlock(&rc->reloc_root_tree.lock);
1304                 if (!node)
1305                         return;
1306                 BUG_ON((struct btrfs_root *)node->data != root);
1307         }
1308
1309         spin_lock(&fs_info->trans_lock);
1310         list_del_init(&root->root_list);
1311         spin_unlock(&fs_info->trans_lock);
1312         kfree(node);
1313 }
1314
1315 /*
1316  * helper to update the 'address of tree root -> reloc tree'
1317  * mapping
1318  */
1319 static int __update_reloc_root(struct btrfs_root *root, u64 new_bytenr)
1320 {
1321         struct btrfs_fs_info *fs_info = root->fs_info;
1322         struct rb_node *rb_node;
1323         struct mapping_node *node = NULL;
1324         struct reloc_control *rc = fs_info->reloc_ctl;
1325
1326         spin_lock(&rc->reloc_root_tree.lock);
1327         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
1328                               root->node->start);
1329         if (rb_node) {
1330                 node = rb_entry(rb_node, struct mapping_node, rb_node);
1331                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
1332         }
1333         spin_unlock(&rc->reloc_root_tree.lock);
1334
1335         if (!node)
1336                 return 0;
1337         BUG_ON((struct btrfs_root *)node->data != root);
1338
1339         spin_lock(&rc->reloc_root_tree.lock);
1340         node->bytenr = new_bytenr;
1341         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
1342                               node->bytenr, &node->rb_node);
1343         spin_unlock(&rc->reloc_root_tree.lock);
1344         if (rb_node)
1345                 backref_tree_panic(rb_node, -EEXIST, node->bytenr);
1346         return 0;
1347 }
1348
1349 static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
1350                                         struct btrfs_root *root, u64 objectid)
1351 {
1352         struct btrfs_fs_info *fs_info = root->fs_info;
1353         struct btrfs_root *reloc_root;
1354         struct extent_buffer *eb;
1355         struct btrfs_root_item *root_item;
1356         struct btrfs_key root_key;
1357         int ret;
1358
1359         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
1360         BUG_ON(!root_item);
1361
1362         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
1363         root_key.type = BTRFS_ROOT_ITEM_KEY;
1364         root_key.offset = objectid;
1365
1366         if (root->root_key.objectid == objectid) {
1367                 u64 commit_root_gen;
1368
1369                 /* called by btrfs_init_reloc_root */
1370                 ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
1371                                       BTRFS_TREE_RELOC_OBJECTID);
1372                 BUG_ON(ret);
1373                 /*
1374                  * Set the last_snapshot field to the generation of the commit
1375                  * root - like this ctree.c:btrfs_block_can_be_shared() behaves
1376                  * correctly (returns true) when the relocation root is created
1377                  * either inside the critical section of a transaction commit
1378                  * (through transaction.c:qgroup_account_snapshot()) and when
1379                  * it's created before the transaction commit is started.
1380                  */
1381                 commit_root_gen = btrfs_header_generation(root->commit_root);
1382                 btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
1383         } else {
1384                 /*
1385                  * called by btrfs_reloc_post_snapshot_hook.
1386                  * the source tree is a reloc tree, all tree blocks
1387                  * modified after it was created have RELOC flag
1388                  * set in their headers. so it's OK to not update
1389                  * the 'last_snapshot'.
1390                  */
1391                 ret = btrfs_copy_root(trans, root, root->node, &eb,
1392                                       BTRFS_TREE_RELOC_OBJECTID);
1393                 BUG_ON(ret);
1394         }
1395
1396         memcpy(root_item, &root->root_item, sizeof(*root_item));
1397         btrfs_set_root_bytenr(root_item, eb->start);
1398         btrfs_set_root_level(root_item, btrfs_header_level(eb));
1399         btrfs_set_root_generation(root_item, trans->transid);
1400
1401         if (root->root_key.objectid == objectid) {
1402                 btrfs_set_root_refs(root_item, 0);
1403                 memset(&root_item->drop_progress, 0,
1404                        sizeof(struct btrfs_disk_key));
1405                 root_item->drop_level = 0;
1406         }
1407
1408         btrfs_tree_unlock(eb);
1409         free_extent_buffer(eb);
1410
1411         ret = btrfs_insert_root(trans, fs_info->tree_root,
1412                                 &root_key, root_item);
1413         BUG_ON(ret);
1414         kfree(root_item);
1415
1416         reloc_root = btrfs_read_fs_root(fs_info->tree_root, &root_key);
1417         BUG_ON(IS_ERR(reloc_root));
1418         reloc_root->last_trans = trans->transid;
1419         return reloc_root;
1420 }
1421
1422 /*
1423  * create reloc tree for a given fs tree. reloc tree is just a
1424  * snapshot of the fs tree with special root objectid.
1425  */
1426 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
1427                           struct btrfs_root *root)
1428 {
1429         struct btrfs_fs_info *fs_info = root->fs_info;
1430         struct btrfs_root *reloc_root;
1431         struct reloc_control *rc = fs_info->reloc_ctl;
1432         struct btrfs_block_rsv *rsv;
1433         int clear_rsv = 0;
1434         int ret;
1435
1436         if (root->reloc_root) {
1437                 reloc_root = root->reloc_root;
1438                 reloc_root->last_trans = trans->transid;
1439                 return 0;
1440         }
1441
1442         if (!rc || !rc->create_reloc_tree ||
1443             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1444                 return 0;
1445
1446         if (!trans->reloc_reserved) {
1447                 rsv = trans->block_rsv;
1448                 trans->block_rsv = rc->block_rsv;
1449                 clear_rsv = 1;
1450         }
1451         reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
1452         if (clear_rsv)
1453                 trans->block_rsv = rsv;
1454
1455         ret = __add_reloc_root(reloc_root);
1456         BUG_ON(ret < 0);
1457         root->reloc_root = reloc_root;
1458         return 0;
1459 }
1460
1461 /*
1462  * update root item of reloc tree
1463  */
1464 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
1465                             struct btrfs_root *root)
1466 {
1467         struct btrfs_fs_info *fs_info = root->fs_info;
1468         struct btrfs_root *reloc_root;
1469         struct btrfs_root_item *root_item;
1470         int ret;
1471
1472         if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state) ||
1473             !root->reloc_root)
1474                 goto out;
1475
1476         reloc_root = root->reloc_root;
1477         root_item = &reloc_root->root_item;
1478
1479         /* root->reloc_root will stay until current relocation finished */
1480         if (fs_info->reloc_ctl->merge_reloc_tree &&
1481             btrfs_root_refs(root_item) == 0) {
1482                 set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
1483                 __del_reloc_root(reloc_root);
1484         }
1485
1486         if (reloc_root->commit_root != reloc_root->node) {
1487                 btrfs_set_root_node(root_item, reloc_root->node);
1488                 free_extent_buffer(reloc_root->commit_root);
1489                 reloc_root->commit_root = btrfs_root_node(reloc_root);
1490         }
1491
1492         ret = btrfs_update_root(trans, fs_info->tree_root,
1493                                 &reloc_root->root_key, root_item);
1494         BUG_ON(ret);
1495
1496 out:
1497         return 0;
1498 }
1499
1500 /*
1501  * helper to find first cached inode with inode number >= objectid
1502  * in a subvolume
1503  */
1504 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
1505 {
1506         struct rb_node *node;
1507         struct rb_node *prev;
1508         struct btrfs_inode *entry;
1509         struct inode *inode;
1510
1511         spin_lock(&root->inode_lock);
1512 again:
1513         node = root->inode_tree.rb_node;
1514         prev = NULL;
1515         while (node) {
1516                 prev = node;
1517                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1518
1519                 if (objectid < btrfs_ino(entry))
1520                         node = node->rb_left;
1521                 else if (objectid > btrfs_ino(entry))
1522                         node = node->rb_right;
1523                 else
1524                         break;
1525         }
1526         if (!node) {
1527                 while (prev) {
1528                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1529                         if (objectid <= btrfs_ino(entry)) {
1530                                 node = prev;
1531                                 break;
1532                         }
1533                         prev = rb_next(prev);
1534                 }
1535         }
1536         while (node) {
1537                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1538                 inode = igrab(&entry->vfs_inode);
1539                 if (inode) {
1540                         spin_unlock(&root->inode_lock);
1541                         return inode;
1542                 }
1543
1544                 objectid = btrfs_ino(entry) + 1;
1545                 if (cond_resched_lock(&root->inode_lock))
1546                         goto again;
1547
1548                 node = rb_next(node);
1549         }
1550         spin_unlock(&root->inode_lock);
1551         return NULL;
1552 }
1553
1554 static int in_block_group(u64 bytenr,
1555                           struct btrfs_block_group_cache *block_group)
1556 {
1557         if (bytenr >= block_group->key.objectid &&
1558             bytenr < block_group->key.objectid + block_group->key.offset)
1559                 return 1;
1560         return 0;
1561 }
1562
1563 /*
1564  * get new location of data
1565  */
1566 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1567                             u64 bytenr, u64 num_bytes)
1568 {
1569         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1570         struct btrfs_path *path;
1571         struct btrfs_file_extent_item *fi;
1572         struct extent_buffer *leaf;
1573         int ret;
1574
1575         path = btrfs_alloc_path();
1576         if (!path)
1577                 return -ENOMEM;
1578
1579         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1580         ret = btrfs_lookup_file_extent(NULL, root, path,
1581                         btrfs_ino(BTRFS_I(reloc_inode)), bytenr, 0);
1582         if (ret < 0)
1583                 goto out;
1584         if (ret > 0) {
1585                 ret = -ENOENT;
1586                 goto out;
1587         }
1588
1589         leaf = path->nodes[0];
1590         fi = btrfs_item_ptr(leaf, path->slots[0],
1591                             struct btrfs_file_extent_item);
1592
1593         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1594                btrfs_file_extent_compression(leaf, fi) ||
1595                btrfs_file_extent_encryption(leaf, fi) ||
1596                btrfs_file_extent_other_encoding(leaf, fi));
1597
1598         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1599                 ret = -EINVAL;
1600                 goto out;
1601         }
1602
1603         *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1604         ret = 0;
1605 out:
1606         btrfs_free_path(path);
1607         return ret;
1608 }
1609
1610 /*
1611  * update file extent items in the tree leaf to point to
1612  * the new locations.
1613  */
1614 static noinline_for_stack
1615 int replace_file_extents(struct btrfs_trans_handle *trans,
1616                          struct reloc_control *rc,
1617                          struct btrfs_root *root,
1618                          struct extent_buffer *leaf)
1619 {
1620         struct btrfs_fs_info *fs_info = root->fs_info;
1621         struct btrfs_key key;
1622         struct btrfs_file_extent_item *fi;
1623         struct inode *inode = NULL;
1624         u64 parent;
1625         u64 bytenr;
1626         u64 new_bytenr = 0;
1627         u64 num_bytes;
1628         u64 end;
1629         u32 nritems;
1630         u32 i;
1631         int ret = 0;
1632         int first = 1;
1633         int dirty = 0;
1634
1635         if (rc->stage != UPDATE_DATA_PTRS)
1636                 return 0;
1637
1638         /* reloc trees always use full backref */
1639         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1640                 parent = leaf->start;
1641         else
1642                 parent = 0;
1643
1644         nritems = btrfs_header_nritems(leaf);
1645         for (i = 0; i < nritems; i++) {
1646                 cond_resched();
1647                 btrfs_item_key_to_cpu(leaf, &key, i);
1648                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1649                         continue;
1650                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1651                 if (btrfs_file_extent_type(leaf, fi) ==
1652                     BTRFS_FILE_EXTENT_INLINE)
1653                         continue;
1654                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1655                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1656                 if (bytenr == 0)
1657                         continue;
1658                 if (!in_block_group(bytenr, rc->block_group))
1659                         continue;
1660
1661                 /*
1662                  * if we are modifying block in fs tree, wait for readpage
1663                  * to complete and drop the extent cache
1664                  */
1665                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1666                         if (first) {
1667                                 inode = find_next_inode(root, key.objectid);
1668                                 first = 0;
1669                         } else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
1670                                 btrfs_add_delayed_iput(inode);
1671                                 inode = find_next_inode(root, key.objectid);
1672                         }
1673                         if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
1674                                 end = key.offset +
1675                                       btrfs_file_extent_num_bytes(leaf, fi);
1676                                 WARN_ON(!IS_ALIGNED(key.offset,
1677                                                     fs_info->sectorsize));
1678                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
1679                                 end--;
1680                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1681                                                       key.offset, end);
1682                                 if (!ret)
1683                                         continue;
1684
1685                                 btrfs_drop_extent_cache(BTRFS_I(inode),
1686                                                 key.offset,     end, 1);
1687                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1688                                               key.offset, end);
1689                         }
1690                 }
1691
1692                 ret = get_new_location(rc->data_inode, &new_bytenr,
1693                                        bytenr, num_bytes);
1694                 if (ret) {
1695                         /*
1696                          * Don't have to abort since we've not changed anything
1697                          * in the file extent yet.
1698                          */
1699                         break;
1700                 }
1701
1702                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1703                 dirty = 1;
1704
1705                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1706                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1707                                            num_bytes, parent,
1708                                            btrfs_header_owner(leaf),
1709                                            key.objectid, key.offset);
1710                 if (ret) {
1711                         btrfs_abort_transaction(trans, ret);
1712                         break;
1713                 }
1714
1715                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1716                                         parent, btrfs_header_owner(leaf),
1717                                         key.objectid, key.offset);
1718                 if (ret) {
1719                         btrfs_abort_transaction(trans, ret);
1720                         break;
1721                 }
1722         }
1723         if (dirty)
1724                 btrfs_mark_buffer_dirty(leaf);
1725         if (inode)
1726                 btrfs_add_delayed_iput(inode);
1727         return ret;
1728 }
1729
1730 static noinline_for_stack
1731 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1732                      struct btrfs_path *path, int level)
1733 {
1734         struct btrfs_disk_key key1;
1735         struct btrfs_disk_key key2;
1736         btrfs_node_key(eb, &key1, slot);
1737         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1738         return memcmp(&key1, &key2, sizeof(key1));
1739 }
1740
1741 /*
1742  * try to replace tree blocks in fs tree with the new blocks
1743  * in reloc tree. tree blocks haven't been modified since the
1744  * reloc tree was create can be replaced.
1745  *
1746  * if a block was replaced, level of the block + 1 is returned.
1747  * if no block got replaced, 0 is returned. if there are other
1748  * errors, a negative error number is returned.
1749  */
1750 static noinline_for_stack
1751 int replace_path(struct btrfs_trans_handle *trans, struct reloc_control *rc,
1752                  struct btrfs_root *dest, struct btrfs_root *src,
1753                  struct btrfs_path *path, struct btrfs_key *next_key,
1754                  int lowest_level, int max_level)
1755 {
1756         struct btrfs_fs_info *fs_info = dest->fs_info;
1757         struct extent_buffer *eb;
1758         struct extent_buffer *parent;
1759         struct btrfs_key key;
1760         u64 old_bytenr;
1761         u64 new_bytenr;
1762         u64 old_ptr_gen;
1763         u64 new_ptr_gen;
1764         u64 last_snapshot;
1765         u32 blocksize;
1766         int cow = 0;
1767         int level;
1768         int ret;
1769         int slot;
1770
1771         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1772         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1773
1774         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1775 again:
1776         slot = path->slots[lowest_level];
1777         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1778
1779         eb = btrfs_lock_root_node(dest);
1780         btrfs_set_lock_blocking_write(eb);
1781         level = btrfs_header_level(eb);
1782
1783         if (level < lowest_level) {
1784                 btrfs_tree_unlock(eb);
1785                 free_extent_buffer(eb);
1786                 return 0;
1787         }
1788
1789         if (cow) {
1790                 ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1791                 BUG_ON(ret);
1792         }
1793         btrfs_set_lock_blocking_write(eb);
1794
1795         if (next_key) {
1796                 next_key->objectid = (u64)-1;
1797                 next_key->type = (u8)-1;
1798                 next_key->offset = (u64)-1;
1799         }
1800
1801         parent = eb;
1802         while (1) {
1803                 struct btrfs_key first_key;
1804
1805                 level = btrfs_header_level(parent);
1806                 BUG_ON(level < lowest_level);
1807
1808                 ret = btrfs_bin_search(parent, &key, level, &slot);
1809                 if (ret < 0)
1810                         break;
1811                 if (ret && slot > 0)
1812                         slot--;
1813
1814                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1815                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1816
1817                 old_bytenr = btrfs_node_blockptr(parent, slot);
1818                 blocksize = fs_info->nodesize;
1819                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1820                 btrfs_node_key_to_cpu(parent, &first_key, slot);
1821
1822                 if (level <= max_level) {
1823                         eb = path->nodes[level];
1824                         new_bytenr = btrfs_node_blockptr(eb,
1825                                                         path->slots[level]);
1826                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1827                                                         path->slots[level]);
1828                 } else {
1829                         new_bytenr = 0;
1830                         new_ptr_gen = 0;
1831                 }
1832
1833                 if (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
1834                         ret = level;
1835                         break;
1836                 }
1837
1838                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1839                     memcmp_node_keys(parent, slot, path, level)) {
1840                         if (level <= lowest_level) {
1841                                 ret = 0;
1842                                 break;
1843                         }
1844
1845                         eb = read_tree_block(fs_info, old_bytenr, old_ptr_gen,
1846                                              level - 1, &first_key);
1847                         if (IS_ERR(eb)) {
1848                                 ret = PTR_ERR(eb);
1849                                 break;
1850                         } else if (!extent_buffer_uptodate(eb)) {
1851                                 ret = -EIO;
1852                                 free_extent_buffer(eb);
1853                                 break;
1854                         }
1855                         btrfs_tree_lock(eb);
1856                         if (cow) {
1857                                 ret = btrfs_cow_block(trans, dest, eb, parent,
1858                                                       slot, &eb);
1859                                 BUG_ON(ret);
1860                         }
1861                         btrfs_set_lock_blocking_write(eb);
1862
1863                         btrfs_tree_unlock(parent);
1864                         free_extent_buffer(parent);
1865
1866                         parent = eb;
1867                         continue;
1868                 }
1869
1870                 if (!cow) {
1871                         btrfs_tree_unlock(parent);
1872                         free_extent_buffer(parent);
1873                         cow = 1;
1874                         goto again;
1875                 }
1876
1877                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1878                                       path->slots[level]);
1879                 btrfs_release_path(path);
1880
1881                 path->lowest_level = level;
1882                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1883                 path->lowest_level = 0;
1884                 BUG_ON(ret);
1885
1886                 /*
1887                  * Info qgroup to trace both subtrees.
1888                  *
1889                  * We must trace both trees.
1890                  * 1) Tree reloc subtree
1891                  *    If not traced, we will leak data numbers
1892                  * 2) Fs subtree
1893                  *    If not traced, we will double count old data
1894                  *
1895                  * We don't scan the subtree right now, but only record
1896                  * the swapped tree blocks.
1897                  * The real subtree rescan is delayed until we have new
1898                  * CoW on the subtree root node before transaction commit.
1899                  */
1900                 ret = btrfs_qgroup_add_swapped_blocks(trans, dest,
1901                                 rc->block_group, parent, slot,
1902                                 path->nodes[level], path->slots[level],
1903                                 last_snapshot);
1904                 if (ret < 0)
1905                         break;
1906                 /*
1907                  * swap blocks in fs tree and reloc tree.
1908                  */
1909                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1910                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1911                 btrfs_mark_buffer_dirty(parent);
1912
1913                 btrfs_set_node_blockptr(path->nodes[level],
1914                                         path->slots[level], old_bytenr);
1915                 btrfs_set_node_ptr_generation(path->nodes[level],
1916                                               path->slots[level], old_ptr_gen);
1917                 btrfs_mark_buffer_dirty(path->nodes[level]);
1918
1919                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr,
1920                                         blocksize, path->nodes[level]->start,
1921                                         src->root_key.objectid, level - 1, 0);
1922                 BUG_ON(ret);
1923                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr,
1924                                         blocksize, 0, dest->root_key.objectid,
1925                                         level - 1, 0);
1926                 BUG_ON(ret);
1927
1928                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1929                                         path->nodes[level]->start,
1930                                         src->root_key.objectid, level - 1, 0);
1931                 BUG_ON(ret);
1932
1933                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1934                                         0, dest->root_key.objectid, level - 1,
1935                                         0);
1936                 BUG_ON(ret);
1937
1938                 btrfs_unlock_up_safe(path, 0);
1939
1940                 ret = level;
1941                 break;
1942         }
1943         btrfs_tree_unlock(parent);
1944         free_extent_buffer(parent);
1945         return ret;
1946 }
1947
1948 /*
1949  * helper to find next relocated block in reloc tree
1950  */
1951 static noinline_for_stack
1952 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1953                        int *level)
1954 {
1955         struct extent_buffer *eb;
1956         int i;
1957         u64 last_snapshot;
1958         u32 nritems;
1959
1960         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1961
1962         for (i = 0; i < *level; i++) {
1963                 free_extent_buffer(path->nodes[i]);
1964                 path->nodes[i] = NULL;
1965         }
1966
1967         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1968                 eb = path->nodes[i];
1969                 nritems = btrfs_header_nritems(eb);
1970                 while (path->slots[i] + 1 < nritems) {
1971                         path->slots[i]++;
1972                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1973                             last_snapshot)
1974                                 continue;
1975
1976                         *level = i;
1977                         return 0;
1978                 }
1979                 free_extent_buffer(path->nodes[i]);
1980                 path->nodes[i] = NULL;
1981         }
1982         return 1;
1983 }
1984
1985 /*
1986  * walk down reloc tree to find relocated block of lowest level
1987  */
1988 static noinline_for_stack
1989 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1990                          int *level)
1991 {
1992         struct btrfs_fs_info *fs_info = root->fs_info;
1993         struct extent_buffer *eb = NULL;
1994         int i;
1995         u64 bytenr;
1996         u64 ptr_gen = 0;
1997         u64 last_snapshot;
1998         u32 nritems;
1999
2000         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
2001
2002         for (i = *level; i > 0; i--) {
2003                 struct btrfs_key first_key;
2004
2005                 eb = path->nodes[i];
2006                 nritems = btrfs_header_nritems(eb);
2007                 while (path->slots[i] < nritems) {
2008                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
2009                         if (ptr_gen > last_snapshot)
2010                                 break;
2011                         path->slots[i]++;
2012                 }
2013                 if (path->slots[i] >= nritems) {
2014                         if (i == *level)
2015                                 break;
2016                         *level = i + 1;
2017                         return 0;
2018                 }
2019                 if (i == 1) {
2020                         *level = i;
2021                         return 0;
2022                 }
2023
2024                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
2025                 btrfs_node_key_to_cpu(eb, &first_key, path->slots[i]);
2026                 eb = read_tree_block(fs_info, bytenr, ptr_gen, i - 1,
2027                                      &first_key);
2028                 if (IS_ERR(eb)) {
2029                         return PTR_ERR(eb);
2030                 } else if (!extent_buffer_uptodate(eb)) {
2031                         free_extent_buffer(eb);
2032                         return -EIO;
2033                 }
2034                 BUG_ON(btrfs_header_level(eb) != i - 1);
2035                 path->nodes[i - 1] = eb;
2036                 path->slots[i - 1] = 0;
2037         }
2038         return 1;
2039 }
2040
2041 /*
2042  * invalidate extent cache for file extents whose key in range of
2043  * [min_key, max_key)
2044  */
2045 static int invalidate_extent_cache(struct btrfs_root *root,
2046                                    struct btrfs_key *min_key,
2047                                    struct btrfs_key *max_key)
2048 {
2049         struct btrfs_fs_info *fs_info = root->fs_info;
2050         struct inode *inode = NULL;
2051         u64 objectid;
2052         u64 start, end;
2053         u64 ino;
2054
2055         objectid = min_key->objectid;
2056         while (1) {
2057                 cond_resched();
2058                 iput(inode);
2059
2060                 if (objectid > max_key->objectid)
2061                         break;
2062
2063                 inode = find_next_inode(root, objectid);
2064                 if (!inode)
2065                         break;
2066                 ino = btrfs_ino(BTRFS_I(inode));
2067
2068                 if (ino > max_key->objectid) {
2069                         iput(inode);
2070                         break;
2071                 }
2072
2073                 objectid = ino + 1;
2074                 if (!S_ISREG(inode->i_mode))
2075                         continue;
2076
2077                 if (unlikely(min_key->objectid == ino)) {
2078                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
2079                                 continue;
2080                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
2081                                 start = 0;
2082                         else {
2083                                 start = min_key->offset;
2084                                 WARN_ON(!IS_ALIGNED(start, fs_info->sectorsize));
2085                         }
2086                 } else {
2087                         start = 0;
2088                 }
2089
2090                 if (unlikely(max_key->objectid == ino)) {
2091                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
2092                                 continue;
2093                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
2094                                 end = (u64)-1;
2095                         } else {
2096                                 if (max_key->offset == 0)
2097                                         continue;
2098                                 end = max_key->offset;
2099                                 WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
2100                                 end--;
2101                         }
2102                 } else {
2103                         end = (u64)-1;
2104                 }
2105
2106                 /* the lock_extent waits for readpage to complete */
2107                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
2108                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
2109                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
2110         }
2111         return 0;
2112 }
2113
2114 static int find_next_key(struct btrfs_path *path, int level,
2115                          struct btrfs_key *key)
2116
2117 {
2118         while (level < BTRFS_MAX_LEVEL) {
2119                 if (!path->nodes[level])
2120                         break;
2121                 if (path->slots[level] + 1 <
2122                     btrfs_header_nritems(path->nodes[level])) {
2123                         btrfs_node_key_to_cpu(path->nodes[level], key,
2124                                               path->slots[level] + 1);
2125                         return 0;
2126                 }
2127                 level++;
2128         }
2129         return 1;
2130 }
2131
2132 /*
2133  * Insert current subvolume into reloc_control::dirty_subvol_roots
2134  */
2135 static void insert_dirty_subvol(struct btrfs_trans_handle *trans,
2136                                 struct reloc_control *rc,
2137                                 struct btrfs_root *root)
2138 {
2139         struct btrfs_root *reloc_root = root->reloc_root;
2140         struct btrfs_root_item *reloc_root_item;
2141
2142         /* @root must be a subvolume tree root with a valid reloc tree */
2143         ASSERT(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
2144         ASSERT(reloc_root);
2145
2146         reloc_root_item = &reloc_root->root_item;
2147         memset(&reloc_root_item->drop_progress, 0,
2148                 sizeof(reloc_root_item->drop_progress));
2149         reloc_root_item->drop_level = 0;
2150         btrfs_set_root_refs(reloc_root_item, 0);
2151         btrfs_update_reloc_root(trans, root);
2152
2153         if (list_empty(&root->reloc_dirty_list)) {
2154                 btrfs_grab_fs_root(root);
2155                 list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots);
2156         }
2157 }
2158
2159 static int clean_dirty_subvols(struct reloc_control *rc)
2160 {
2161         struct btrfs_root *root;
2162         struct btrfs_root *next;
2163         int ret = 0;
2164
2165         list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots,
2166                                  reloc_dirty_list) {
2167                 struct btrfs_root *reloc_root = root->reloc_root;
2168
2169                 clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
2170                 list_del_init(&root->reloc_dirty_list);
2171                 root->reloc_root = NULL;
2172                 if (reloc_root) {
2173                         int ret2;
2174
2175                         ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1);
2176                         if (ret2 < 0 && !ret)
2177                                 ret = ret2;
2178                 }
2179                 btrfs_put_fs_root(root);
2180         }
2181         return ret;
2182 }
2183
2184 /*
2185  * merge the relocated tree blocks in reloc tree with corresponding
2186  * fs tree.
2187  */
2188 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
2189                                                struct btrfs_root *root)
2190 {
2191         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2192         struct btrfs_key key;
2193         struct btrfs_key next_key;
2194         struct btrfs_trans_handle *trans = NULL;
2195         struct btrfs_root *reloc_root;
2196         struct btrfs_root_item *root_item;
2197         struct btrfs_path *path;
2198         struct extent_buffer *leaf;
2199         int level;
2200         int max_level;
2201         int replaced = 0;
2202         int ret;
2203         int err = 0;
2204         u32 min_reserved;
2205
2206         path = btrfs_alloc_path();
2207         if (!path)
2208                 return -ENOMEM;
2209         path->reada = READA_FORWARD;
2210
2211         reloc_root = root->reloc_root;
2212         root_item = &reloc_root->root_item;
2213
2214         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
2215                 level = btrfs_root_level(root_item);
2216                 extent_buffer_get(reloc_root->node);
2217                 path->nodes[level] = reloc_root->node;
2218                 path->slots[level] = 0;
2219         } else {
2220                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
2221
2222                 level = root_item->drop_level;
2223                 BUG_ON(level == 0);
2224                 path->lowest_level = level;
2225                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
2226                 path->lowest_level = 0;
2227                 if (ret < 0) {
2228                         btrfs_free_path(path);
2229                         return ret;
2230                 }
2231
2232                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
2233                                       path->slots[level]);
2234                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
2235
2236                 btrfs_unlock_up_safe(path, 0);
2237         }
2238
2239         min_reserved = fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2240         memset(&next_key, 0, sizeof(next_key));
2241
2242         while (1) {
2243                 ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
2244                                              BTRFS_RESERVE_FLUSH_ALL);
2245                 if (ret) {
2246                         err = ret;
2247                         goto out;
2248                 }
2249                 trans = btrfs_start_transaction(root, 0);
2250                 if (IS_ERR(trans)) {
2251                         err = PTR_ERR(trans);
2252                         trans = NULL;
2253                         goto out;
2254                 }
2255                 trans->block_rsv = rc->block_rsv;
2256
2257                 replaced = 0;
2258                 max_level = level;
2259
2260                 ret = walk_down_reloc_tree(reloc_root, path, &level);
2261                 if (ret < 0) {
2262                         err = ret;
2263                         goto out;
2264                 }
2265                 if (ret > 0)
2266                         break;
2267
2268                 if (!find_next_key(path, level, &key) &&
2269                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
2270                         ret = 0;
2271                 } else {
2272                         ret = replace_path(trans, rc, root, reloc_root, path,
2273                                            &next_key, level, max_level);
2274                 }
2275                 if (ret < 0) {
2276                         err = ret;
2277                         goto out;
2278                 }
2279
2280                 if (ret > 0) {
2281                         level = ret;
2282                         btrfs_node_key_to_cpu(path->nodes[level], &key,
2283                                               path->slots[level]);
2284                         replaced = 1;
2285                 }
2286
2287                 ret = walk_up_reloc_tree(reloc_root, path, &level);
2288                 if (ret > 0)
2289                         break;
2290
2291                 BUG_ON(level == 0);
2292                 /*
2293                  * save the merging progress in the drop_progress.
2294                  * this is OK since root refs == 1 in this case.
2295                  */
2296                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
2297                                path->slots[level]);
2298                 root_item->drop_level = level;
2299
2300                 btrfs_end_transaction_throttle(trans);
2301                 trans = NULL;
2302
2303                 btrfs_btree_balance_dirty(fs_info);
2304
2305                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
2306                         invalidate_extent_cache(root, &key, &next_key);
2307         }
2308
2309         /*
2310          * handle the case only one block in the fs tree need to be
2311          * relocated and the block is tree root.
2312          */
2313         leaf = btrfs_lock_root_node(root);
2314         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
2315         btrfs_tree_unlock(leaf);
2316         free_extent_buffer(leaf);
2317         if (ret < 0)
2318                 err = ret;
2319 out:
2320         btrfs_free_path(path);
2321
2322         if (err == 0)
2323                 insert_dirty_subvol(trans, rc, root);
2324
2325         if (trans)
2326                 btrfs_end_transaction_throttle(trans);
2327
2328         btrfs_btree_balance_dirty(fs_info);
2329
2330         if (replaced && rc->stage == UPDATE_DATA_PTRS)
2331                 invalidate_extent_cache(root, &key, &next_key);
2332
2333         return err;
2334 }
2335
2336 static noinline_for_stack
2337 int prepare_to_merge(struct reloc_control *rc, int err)
2338 {
2339         struct btrfs_root *root = rc->extent_root;
2340         struct btrfs_fs_info *fs_info = root->fs_info;
2341         struct btrfs_root *reloc_root;
2342         struct btrfs_trans_handle *trans;
2343         LIST_HEAD(reloc_roots);
2344         u64 num_bytes = 0;
2345         int ret;
2346
2347         mutex_lock(&fs_info->reloc_mutex);
2348         rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
2349         rc->merging_rsv_size += rc->nodes_relocated * 2;
2350         mutex_unlock(&fs_info->reloc_mutex);
2351
2352 again:
2353         if (!err) {
2354                 num_bytes = rc->merging_rsv_size;
2355                 ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
2356                                           BTRFS_RESERVE_FLUSH_ALL);
2357                 if (ret)
2358                         err = ret;
2359         }
2360
2361         trans = btrfs_join_transaction(rc->extent_root);
2362         if (IS_ERR(trans)) {
2363                 if (!err)
2364                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2365                                                 num_bytes);
2366                 return PTR_ERR(trans);
2367         }
2368
2369         if (!err) {
2370                 if (num_bytes != rc->merging_rsv_size) {
2371                         btrfs_end_transaction(trans);
2372                         btrfs_block_rsv_release(fs_info, rc->block_rsv,
2373                                                 num_bytes);
2374                         goto again;
2375                 }
2376         }
2377
2378         rc->merge_reloc_tree = 1;
2379
2380         while (!list_empty(&rc->reloc_roots)) {
2381                 reloc_root = list_entry(rc->reloc_roots.next,
2382                                         struct btrfs_root, root_list);
2383                 list_del_init(&reloc_root->root_list);
2384
2385                 root = read_fs_root(fs_info, reloc_root->root_key.offset);
2386                 BUG_ON(IS_ERR(root));
2387                 BUG_ON(root->reloc_root != reloc_root);
2388
2389                 /*
2390                  * set reference count to 1, so btrfs_recover_relocation
2391                  * knows it should resumes merging
2392                  */
2393                 if (!err)
2394                         btrfs_set_root_refs(&reloc_root->root_item, 1);
2395                 btrfs_update_reloc_root(trans, root);
2396
2397                 list_add(&reloc_root->root_list, &reloc_roots);
2398         }
2399
2400         list_splice(&reloc_roots, &rc->reloc_roots);
2401
2402         if (!err)
2403                 btrfs_commit_transaction(trans);
2404         else
2405                 btrfs_end_transaction(trans);
2406         return err;
2407 }
2408
2409 static noinline_for_stack
2410 void free_reloc_roots(struct list_head *list)
2411 {
2412         struct btrfs_root *reloc_root;
2413
2414         while (!list_empty(list)) {
2415                 reloc_root = list_entry(list->next, struct btrfs_root,
2416                                         root_list);
2417                 __del_reloc_root(reloc_root);
2418                 free_extent_buffer(reloc_root->node);
2419                 free_extent_buffer(reloc_root->commit_root);
2420                 reloc_root->node = NULL;
2421                 reloc_root->commit_root = NULL;
2422         }
2423 }
2424
2425 static noinline_for_stack
2426 void merge_reloc_roots(struct reloc_control *rc)
2427 {
2428         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2429         struct btrfs_root *root;
2430         struct btrfs_root *reloc_root;
2431         LIST_HEAD(reloc_roots);
2432         int found = 0;
2433         int ret = 0;
2434 again:
2435         root = rc->extent_root;
2436
2437         /*
2438          * this serializes us with btrfs_record_root_in_transaction,
2439          * we have to make sure nobody is in the middle of
2440          * adding their roots to the list while we are
2441          * doing this splice
2442          */
2443         mutex_lock(&fs_info->reloc_mutex);
2444         list_splice_init(&rc->reloc_roots, &reloc_roots);
2445         mutex_unlock(&fs_info->reloc_mutex);
2446
2447         while (!list_empty(&reloc_roots)) {
2448                 found = 1;
2449                 reloc_root = list_entry(reloc_roots.next,
2450                                         struct btrfs_root, root_list);
2451
2452                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
2453                         root = read_fs_root(fs_info,
2454                                             reloc_root->root_key.offset);
2455                         BUG_ON(IS_ERR(root));
2456                         BUG_ON(root->reloc_root != reloc_root);
2457
2458                         ret = merge_reloc_root(rc, root);
2459                         if (ret) {
2460                                 if (list_empty(&reloc_root->root_list))
2461                                         list_add_tail(&reloc_root->root_list,
2462                                                       &reloc_roots);
2463                                 goto out;
2464                         }
2465                 } else {
2466                         list_del_init(&reloc_root->root_list);
2467                 }
2468         }
2469
2470         if (found) {
2471                 found = 0;
2472                 goto again;
2473         }
2474 out:
2475         if (ret) {
2476                 btrfs_handle_fs_error(fs_info, ret, NULL);
2477                 if (!list_empty(&reloc_roots))
2478                         free_reloc_roots(&reloc_roots);
2479
2480                 /* new reloc root may be added */
2481                 mutex_lock(&fs_info->reloc_mutex);
2482                 list_splice_init(&rc->reloc_roots, &reloc_roots);
2483                 mutex_unlock(&fs_info->reloc_mutex);
2484                 if (!list_empty(&reloc_roots))
2485                         free_reloc_roots(&reloc_roots);
2486         }
2487
2488         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
2489 }
2490
2491 static void free_block_list(struct rb_root *blocks)
2492 {
2493         struct tree_block *block;
2494         struct rb_node *rb_node;
2495         while ((rb_node = rb_first(blocks))) {
2496                 block = rb_entry(rb_node, struct tree_block, rb_node);
2497                 rb_erase(rb_node, blocks);
2498                 kfree(block);
2499         }
2500 }
2501
2502 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
2503                                       struct btrfs_root *reloc_root)
2504 {
2505         struct btrfs_fs_info *fs_info = reloc_root->fs_info;
2506         struct btrfs_root *root;
2507
2508         if (reloc_root->last_trans == trans->transid)
2509                 return 0;
2510
2511         root = read_fs_root(fs_info, reloc_root->root_key.offset);
2512         BUG_ON(IS_ERR(root));
2513         BUG_ON(root->reloc_root != reloc_root);
2514
2515         return btrfs_record_root_in_trans(trans, root);
2516 }
2517
2518 static noinline_for_stack
2519 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
2520                                      struct reloc_control *rc,
2521                                      struct backref_node *node,
2522                                      struct backref_edge *edges[])
2523 {
2524         struct backref_node *next;
2525         struct btrfs_root *root;
2526         int index = 0;
2527
2528         next = node;
2529         while (1) {
2530                 cond_resched();
2531                 next = walk_up_backref(next, edges, &index);
2532                 root = next->root;
2533                 BUG_ON(!root);
2534                 BUG_ON(!test_bit(BTRFS_ROOT_REF_COWS, &root->state));
2535
2536                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2537                         record_reloc_root_in_trans(trans, root);
2538                         break;
2539                 }
2540
2541                 btrfs_record_root_in_trans(trans, root);
2542                 root = root->reloc_root;
2543
2544                 if (next->new_bytenr != root->node->start) {
2545                         BUG_ON(next->new_bytenr);
2546                         BUG_ON(!list_empty(&next->list));
2547                         next->new_bytenr = root->node->start;
2548                         next->root = root;
2549                         list_add_tail(&next->list,
2550                                       &rc->backref_cache.changed);
2551                         __mark_block_processed(rc, next);
2552                         break;
2553                 }
2554
2555                 WARN_ON(1);
2556                 root = NULL;
2557                 next = walk_down_backref(edges, &index);
2558                 if (!next || next->level <= node->level)
2559                         break;
2560         }
2561         if (!root)
2562                 return NULL;
2563
2564         next = node;
2565         /* setup backref node path for btrfs_reloc_cow_block */
2566         while (1) {
2567                 rc->backref_cache.path[next->level] = next;
2568                 if (--index < 0)
2569                         break;
2570                 next = edges[index]->node[UPPER];
2571         }
2572         return root;
2573 }
2574
2575 /*
2576  * select a tree root for relocation. return NULL if the block
2577  * is reference counted. we should use do_relocation() in this
2578  * case. return a tree root pointer if the block isn't reference
2579  * counted. return -ENOENT if the block is root of reloc tree.
2580  */
2581 static noinline_for_stack
2582 struct btrfs_root *select_one_root(struct backref_node *node)
2583 {
2584         struct backref_node *next;
2585         struct btrfs_root *root;
2586         struct btrfs_root *fs_root = NULL;
2587         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2588         int index = 0;
2589
2590         next = node;
2591         while (1) {
2592                 cond_resched();
2593                 next = walk_up_backref(next, edges, &index);
2594                 root = next->root;
2595                 BUG_ON(!root);
2596
2597                 /* no other choice for non-references counted tree */
2598                 if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
2599                         return root;
2600
2601                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
2602                         fs_root = root;
2603
2604                 if (next != node)
2605                         return NULL;
2606
2607                 next = walk_down_backref(edges, &index);
2608                 if (!next || next->level <= node->level)
2609                         break;
2610         }
2611
2612         if (!fs_root)
2613                 return ERR_PTR(-ENOENT);
2614         return fs_root;
2615 }
2616
2617 static noinline_for_stack
2618 u64 calcu_metadata_size(struct reloc_control *rc,
2619                         struct backref_node *node, int reserve)
2620 {
2621         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2622         struct backref_node *next = node;
2623         struct backref_edge *edge;
2624         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2625         u64 num_bytes = 0;
2626         int index = 0;
2627
2628         BUG_ON(reserve && node->processed);
2629
2630         while (next) {
2631                 cond_resched();
2632                 while (1) {
2633                         if (next->processed && (reserve || next != node))
2634                                 break;
2635
2636                         num_bytes += fs_info->nodesize;
2637
2638                         if (list_empty(&next->upper))
2639                                 break;
2640
2641                         edge = list_entry(next->upper.next,
2642                                           struct backref_edge, list[LOWER]);
2643                         edges[index++] = edge;
2644                         next = edge->node[UPPER];
2645                 }
2646                 next = walk_down_backref(edges, &index);
2647         }
2648         return num_bytes;
2649 }
2650
2651 static int reserve_metadata_space(struct btrfs_trans_handle *trans,
2652                                   struct reloc_control *rc,
2653                                   struct backref_node *node)
2654 {
2655         struct btrfs_root *root = rc->extent_root;
2656         struct btrfs_fs_info *fs_info = root->fs_info;
2657         u64 num_bytes;
2658         int ret;
2659         u64 tmp;
2660
2661         num_bytes = calcu_metadata_size(rc, node, 1) * 2;
2662
2663         trans->block_rsv = rc->block_rsv;
2664         rc->reserved_bytes += num_bytes;
2665
2666         /*
2667          * We are under a transaction here so we can only do limited flushing.
2668          * If we get an enospc just kick back -EAGAIN so we know to drop the
2669          * transaction and try to refill when we can flush all the things.
2670          */
2671         ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
2672                                 BTRFS_RESERVE_FLUSH_LIMIT);
2673         if (ret) {
2674                 tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
2675                 while (tmp <= rc->reserved_bytes)
2676                         tmp <<= 1;
2677                 /*
2678                  * only one thread can access block_rsv at this point,
2679                  * so we don't need hold lock to protect block_rsv.
2680                  * we expand more reservation size here to allow enough
2681                  * space for relocation and we will return earlier in
2682                  * enospc case.
2683                  */
2684                 rc->block_rsv->size = tmp + fs_info->nodesize *
2685                                       RELOCATION_RESERVED_NODES;
2686                 return -EAGAIN;
2687         }
2688
2689         return 0;
2690 }
2691
2692 /*
2693  * relocate a block tree, and then update pointers in upper level
2694  * blocks that reference the block to point to the new location.
2695  *
2696  * if called by link_to_upper, the block has already been relocated.
2697  * in that case this function just updates pointers.
2698  */
2699 static int do_relocation(struct btrfs_trans_handle *trans,
2700                          struct reloc_control *rc,
2701                          struct backref_node *node,
2702                          struct btrfs_key *key,
2703                          struct btrfs_path *path, int lowest)
2704 {
2705         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
2706         struct backref_node *upper;
2707         struct backref_edge *edge;
2708         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2709         struct btrfs_root *root;
2710         struct extent_buffer *eb;
2711         u32 blocksize;
2712         u64 bytenr;
2713         u64 generation;
2714         int slot;
2715         int ret;
2716         int err = 0;
2717
2718         BUG_ON(lowest && node->eb);
2719
2720         path->lowest_level = node->level + 1;
2721         rc->backref_cache.path[node->level] = node;
2722         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2723                 struct btrfs_key first_key;
2724
2725                 cond_resched();
2726
2727                 upper = edge->node[UPPER];
2728                 root = select_reloc_root(trans, rc, upper, edges);
2729                 BUG_ON(!root);
2730
2731                 if (upper->eb && !upper->locked) {
2732                         if (!lowest) {
2733                                 ret = btrfs_bin_search(upper->eb, key,
2734                                                        upper->level, &slot);
2735                                 if (ret < 0) {
2736                                         err = ret;
2737                                         goto next;
2738                                 }
2739                                 BUG_ON(ret);
2740                                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2741                                 if (node->eb->start == bytenr)
2742                                         goto next;
2743                         }
2744                         drop_node_buffer(upper);
2745                 }
2746
2747                 if (!upper->eb) {
2748                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2749                         if (ret) {
2750                                 if (ret < 0)
2751                                         err = ret;
2752                                 else
2753                                         err = -ENOENT;
2754
2755                                 btrfs_release_path(path);
2756                                 break;
2757                         }
2758
2759                         if (!upper->eb) {
2760                                 upper->eb = path->nodes[upper->level];
2761                                 path->nodes[upper->level] = NULL;
2762                         } else {
2763                                 BUG_ON(upper->eb != path->nodes[upper->level]);
2764                         }
2765
2766                         upper->locked = 1;
2767                         path->locks[upper->level] = 0;
2768
2769                         slot = path->slots[upper->level];
2770                         btrfs_release_path(path);
2771                 } else {
2772                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2773                                                &slot);
2774                         if (ret < 0) {
2775                                 err = ret;
2776                                 goto next;
2777                         }
2778                         BUG_ON(ret);
2779                 }
2780
2781                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2782                 if (lowest) {
2783                         if (bytenr != node->bytenr) {
2784                                 btrfs_err(root->fs_info,
2785                 "lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
2786                                           bytenr, node->bytenr, slot,
2787                                           upper->eb->start);
2788                                 err = -EIO;
2789                                 goto next;
2790                         }
2791                 } else {
2792                         if (node->eb->start == bytenr)
2793                                 goto next;
2794                 }
2795
2796                 blocksize = root->fs_info->nodesize;
2797                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2798                 btrfs_node_key_to_cpu(upper->eb, &first_key, slot);
2799                 eb = read_tree_block(fs_info, bytenr, generation,
2800                                      upper->level - 1, &first_key);
2801                 if (IS_ERR(eb)) {
2802                         err = PTR_ERR(eb);
2803                         goto next;
2804                 } else if (!extent_buffer_uptodate(eb)) {
2805                         free_extent_buffer(eb);
2806                         err = -EIO;
2807                         goto next;
2808                 }
2809                 btrfs_tree_lock(eb);
2810                 btrfs_set_lock_blocking_write(eb);
2811
2812                 if (!node->eb) {
2813                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2814                                               slot, &eb);
2815                         btrfs_tree_unlock(eb);
2816                         free_extent_buffer(eb);
2817                         if (ret < 0) {
2818                                 err = ret;
2819                                 goto next;
2820                         }
2821                         BUG_ON(node->eb != eb);
2822                 } else {
2823                         btrfs_set_node_blockptr(upper->eb, slot,
2824                                                 node->eb->start);
2825                         btrfs_set_node_ptr_generation(upper->eb, slot,
2826                                                       trans->transid);
2827                         btrfs_mark_buffer_dirty(upper->eb);
2828
2829                         ret = btrfs_inc_extent_ref(trans, root,
2830                                                 node->eb->start, blocksize,
2831                                                 upper->eb->start,
2832                                                 btrfs_header_owner(upper->eb),
2833                                                 node->level, 0);
2834                         BUG_ON(ret);
2835
2836                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2837                         BUG_ON(ret);
2838                 }
2839 next:
2840                 if (!upper->pending)
2841                         drop_node_buffer(upper);
2842                 else
2843                         unlock_node_buffer(upper);
2844                 if (err)
2845                         break;
2846         }
2847
2848         if (!err && node->pending) {
2849                 drop_node_buffer(node);
2850                 list_move_tail(&node->list, &rc->backref_cache.changed);
2851                 node->pending = 0;
2852         }
2853
2854         path->lowest_level = 0;
2855         BUG_ON(err == -ENOSPC);
2856         return err;
2857 }
2858
2859 static int link_to_upper(struct btrfs_trans_handle *trans,
2860                          struct reloc_control *rc,
2861                          struct backref_node *node,
2862                          struct btrfs_path *path)
2863 {
2864         struct btrfs_key key;
2865
2866         btrfs_node_key_to_cpu(node->eb, &key, 0);
2867         return do_relocation(trans, rc, node, &key, path, 0);
2868 }
2869
2870 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2871                                 struct reloc_control *rc,
2872                                 struct btrfs_path *path, int err)
2873 {
2874         LIST_HEAD(list);
2875         struct backref_cache *cache = &rc->backref_cache;
2876         struct backref_node *node;
2877         int level;
2878         int ret;
2879
2880         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2881                 while (!list_empty(&cache->pending[level])) {
2882                         node = list_entry(cache->pending[level].next,
2883                                           struct backref_node, list);
2884                         list_move_tail(&node->list, &list);
2885                         BUG_ON(!node->pending);
2886
2887                         if (!err) {
2888                                 ret = link_to_upper(trans, rc, node, path);
2889                                 if (ret < 0)
2890                                         err = ret;
2891                         }
2892                 }
2893                 list_splice_init(&list, &cache->pending[level]);
2894         }
2895         return err;
2896 }
2897
2898 static void mark_block_processed(struct reloc_control *rc,
2899                                  u64 bytenr, u32 blocksize)
2900 {
2901         set_extent_bits(&rc->processed_blocks, bytenr, bytenr + blocksize - 1,
2902                         EXTENT_DIRTY);
2903 }
2904
2905 static void __mark_block_processed(struct reloc_control *rc,
2906                                    struct backref_node *node)
2907 {
2908         u32 blocksize;
2909         if (node->level == 0 ||
2910             in_block_group(node->bytenr, rc->block_group)) {
2911                 blocksize = rc->extent_root->fs_info->nodesize;
2912                 mark_block_processed(rc, node->bytenr, blocksize);
2913         }
2914         node->processed = 1;
2915 }
2916
2917 /*
2918  * mark a block and all blocks directly/indirectly reference the block
2919  * as processed.
2920  */
2921 static void update_processed_blocks(struct reloc_control *rc,
2922                                     struct backref_node *node)
2923 {
2924         struct backref_node *next = node;
2925         struct backref_edge *edge;
2926         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2927         int index = 0;
2928
2929         while (next) {
2930                 cond_resched();
2931                 while (1) {
2932                         if (next->processed)
2933                                 break;
2934
2935                         __mark_block_processed(rc, next);
2936
2937                         if (list_empty(&next->upper))
2938                                 break;
2939
2940                         edge = list_entry(next->upper.next,
2941                                           struct backref_edge, list[LOWER]);
2942                         edges[index++] = edge;
2943                         next = edge->node[UPPER];
2944                 }
2945                 next = walk_down_backref(edges, &index);
2946         }
2947 }
2948
2949 static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
2950 {
2951         u32 blocksize = rc->extent_root->fs_info->nodesize;
2952
2953         if (test_range_bit(&rc->processed_blocks, bytenr,
2954                            bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
2955                 return 1;
2956         return 0;
2957 }
2958
2959 static int get_tree_block_key(struct btrfs_fs_info *fs_info,
2960                               struct tree_block *block)
2961 {
2962         struct extent_buffer *eb;
2963
2964         BUG_ON(block->key_ready);
2965         eb = read_tree_block(fs_info, block->bytenr, block->key.offset,
2966                              block->level, NULL);
2967         if (IS_ERR(eb)) {
2968                 return PTR_ERR(eb);
2969         } else if (!extent_buffer_uptodate(eb)) {
2970                 free_extent_buffer(eb);
2971                 return -EIO;
2972         }
2973         if (block->level == 0)
2974                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2975         else
2976                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2977         free_extent_buffer(eb);
2978         block->key_ready = 1;
2979         return 0;
2980 }
2981
2982 /*
2983  * helper function to relocate a tree block
2984  */
2985 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2986                                 struct reloc_control *rc,
2987                                 struct backref_node *node,
2988                                 struct btrfs_key *key,
2989                                 struct btrfs_path *path)
2990 {
2991         struct btrfs_root *root;
2992         int ret = 0;
2993
2994         if (!node)
2995                 return 0;
2996
2997         BUG_ON(node->processed);
2998         root = select_one_root(node);
2999         if (root == ERR_PTR(-ENOENT)) {
3000                 update_processed_blocks(rc, node);
3001                 goto out;
3002         }
3003
3004         if (!root || test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
3005                 ret = reserve_metadata_space(trans, rc, node);
3006                 if (ret)
3007                         goto out;
3008         }
3009
3010         if (root) {
3011                 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
3012                         BUG_ON(node->new_bytenr);
3013                         BUG_ON(!list_empty(&node->list));
3014                         btrfs_record_root_in_trans(trans, root);
3015                         root = root->reloc_root;
3016                         node->new_bytenr = root->node->start;
3017                         node->root = root;
3018                         list_add_tail(&node->list, &rc->backref_cache.changed);
3019                 } else {
3020                         path->lowest_level = node->level;
3021                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
3022                         btrfs_release_path(path);
3023                         if (ret > 0)
3024                                 ret = 0;
3025                 }
3026                 if (!ret)
3027                         update_processed_blocks(rc, node);
3028         } else {
3029                 ret = do_relocation(trans, rc, node, key, path, 1);
3030         }
3031 out:
3032         if (ret || node->level == 0 || node->cowonly)
3033                 remove_backref_node(&rc->backref_cache, node);
3034         return ret;
3035 }
3036
3037 /*
3038  * relocate a list of blocks
3039  */
3040 static noinline_for_stack
3041 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
3042                          struct reloc_control *rc, struct rb_root *blocks)
3043 {
3044         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3045         struct backref_node *node;
3046         struct btrfs_path *path;
3047         struct tree_block *block;
3048         struct tree_block *next;
3049         int ret;
3050         int err = 0;
3051
3052         path = btrfs_alloc_path();
3053         if (!path) {
3054                 err = -ENOMEM;
3055                 goto out_free_blocks;
3056         }
3057
3058         /* Kick in readahead for tree blocks with missing keys */
3059         rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3060                 if (!block->key_ready)
3061                         readahead_tree_block(fs_info, block->bytenr);
3062         }
3063
3064         /* Get first keys */
3065         rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3066                 if (!block->key_ready) {
3067                         err = get_tree_block_key(fs_info, block);
3068                         if (err)
3069                                 goto out_free_path;
3070                 }
3071         }
3072
3073         /* Do tree relocation */
3074         rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
3075                 node = build_backref_tree(rc, &block->key,
3076                                           block->level, block->bytenr);
3077                 if (IS_ERR(node)) {
3078                         err = PTR_ERR(node);
3079                         goto out;
3080                 }
3081
3082                 ret = relocate_tree_block(trans, rc, node, &block->key,
3083                                           path);
3084                 if (ret < 0) {
3085                         if (ret != -EAGAIN || &block->rb_node == rb_first(blocks))
3086                                 err = ret;
3087                         goto out;
3088                 }
3089         }
3090 out:
3091         err = finish_pending_nodes(trans, rc, path, err);
3092
3093 out_free_path:
3094         btrfs_free_path(path);
3095 out_free_blocks:
3096         free_block_list(blocks);
3097         return err;
3098 }
3099
3100 static noinline_for_stack
3101 int prealloc_file_extent_cluster(struct inode *inode,
3102                                  struct file_extent_cluster *cluster)
3103 {
3104         u64 alloc_hint = 0;
3105         u64 start;
3106         u64 end;
3107         u64 offset = BTRFS_I(inode)->index_cnt;
3108         u64 num_bytes;
3109         int nr = 0;
3110         int ret = 0;
3111         u64 prealloc_start = cluster->start - offset;
3112         u64 prealloc_end = cluster->end - offset;
3113         u64 cur_offset;
3114         struct extent_changeset *data_reserved = NULL;
3115
3116         BUG_ON(cluster->start != cluster->boundary[0]);
3117         inode_lock(inode);
3118
3119         ret = btrfs_check_data_free_space(inode, &data_reserved, prealloc_start,
3120                                           prealloc_end + 1 - prealloc_start);
3121         if (ret)
3122                 goto out;
3123
3124         cur_offset = prealloc_start;
3125         while (nr < cluster->nr) {
3126                 start = cluster->boundary[nr] - offset;
3127                 if (nr + 1 < cluster->nr)
3128                         end = cluster->boundary[nr + 1] - 1 - offset;
3129                 else
3130                         end = cluster->end - offset;
3131
3132                 lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3133                 num_bytes = end + 1 - start;
3134                 if (cur_offset < start)
3135                         btrfs_free_reserved_data_space(inode, data_reserved,
3136                                         cur_offset, start - cur_offset);
3137                 ret = btrfs_prealloc_file_range(inode, 0, start,
3138                                                 num_bytes, num_bytes,
3139                                                 end + 1, &alloc_hint);
3140                 cur_offset = end + 1;
3141                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3142                 if (ret)
3143                         break;
3144                 nr++;
3145         }
3146         if (cur_offset < prealloc_end)
3147                 btrfs_free_reserved_data_space(inode, data_reserved,
3148                                 cur_offset, prealloc_end + 1 - cur_offset);
3149 out:
3150         inode_unlock(inode);
3151         extent_changeset_free(data_reserved);
3152         return ret;
3153 }
3154
3155 static noinline_for_stack
3156 int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
3157                          u64 block_start)
3158 {
3159         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3160         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
3161         struct extent_map *em;
3162         int ret = 0;
3163
3164         em = alloc_extent_map();
3165         if (!em)
3166                 return -ENOMEM;
3167
3168         em->start = start;
3169         em->len = end + 1 - start;
3170         em->block_len = em->len;
3171         em->block_start = block_start;
3172         em->bdev = fs_info->fs_devices->latest_bdev;
3173         set_bit(EXTENT_FLAG_PINNED, &em->flags);
3174
3175         lock_extent(&BTRFS_I(inode)->io_tree, start, end);
3176         while (1) {
3177                 write_lock(&em_tree->lock);
3178                 ret = add_extent_mapping(em_tree, em, 0);
3179                 write_unlock(&em_tree->lock);
3180                 if (ret != -EEXIST) {
3181                         free_extent_map(em);
3182                         break;
3183                 }
3184                 btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
3185         }
3186         unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
3187         return ret;
3188 }
3189
3190 static int relocate_file_extent_cluster(struct inode *inode,
3191                                         struct file_extent_cluster *cluster)
3192 {
3193         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
3194         u64 page_start;
3195         u64 page_end;
3196         u64 offset = BTRFS_I(inode)->index_cnt;
3197         unsigned long index;
3198         unsigned long last_index;
3199         struct page *page;
3200         struct file_ra_state *ra;
3201         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
3202         int nr = 0;
3203         int ret = 0;
3204
3205         if (!cluster->nr)
3206                 return 0;
3207
3208         ra = kzalloc(sizeof(*ra), GFP_NOFS);
3209         if (!ra)
3210                 return -ENOMEM;
3211
3212         ret = prealloc_file_extent_cluster(inode, cluster);
3213         if (ret)
3214                 goto out;
3215
3216         file_ra_state_init(ra, inode->i_mapping);
3217
3218         ret = setup_extent_mapping(inode, cluster->start - offset,
3219                                    cluster->end - offset, cluster->start);
3220         if (ret)
3221                 goto out;
3222
3223         index = (cluster->start - offset) >> PAGE_SHIFT;
3224         last_index = (cluster->end - offset) >> PAGE_SHIFT;
3225         while (index <= last_index) {
3226                 ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
3227                                 PAGE_SIZE);
3228                 if (ret)
3229                         goto out;
3230
3231                 page = find_lock_page(inode->i_mapping, index);
3232                 if (!page) {
3233                         page_cache_sync_readahead(inode->i_mapping,
3234                                                   ra, NULL, index,
3235                                                   last_index + 1 - index);
3236                         page = find_or_create_page(inode->i_mapping, index,
3237                                                    mask);
3238                         if (!page) {
3239                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3240                                                         PAGE_SIZE, true);
3241                                 ret = -ENOMEM;
3242                                 goto out;
3243                         }
3244                 }
3245
3246                 if (PageReadahead(page)) {
3247                         page_cache_async_readahead(inode->i_mapping,
3248                                                    ra, NULL, page, index,
3249                                                    last_index + 1 - index);
3250                 }
3251
3252                 if (!PageUptodate(page)) {
3253                         btrfs_readpage(NULL, page);
3254                         lock_page(page);
3255                         if (!PageUptodate(page)) {
3256                                 unlock_page(page);
3257                                 put_page(page);
3258                                 btrfs_delalloc_release_metadata(BTRFS_I(inode),
3259                                                         PAGE_SIZE, true);
3260                                 btrfs_delalloc_release_extents(BTRFS_I(inode),
3261                                                                PAGE_SIZE, true);
3262                                 ret = -EIO;
3263                                 goto out;
3264                         }
3265                 }
3266
3267                 page_start = page_offset(page);
3268                 page_end = page_start + PAGE_SIZE - 1;
3269
3270                 lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
3271
3272                 set_page_extent_mapped(page);
3273
3274                 if (nr < cluster->nr &&
3275                     page_start + offset == cluster->boundary[nr]) {
3276                         set_extent_bits(&BTRFS_I(inode)->io_tree,
3277                                         page_start, page_end,
3278                                         EXTENT_BOUNDARY);
3279                         nr++;
3280                 }
3281
3282                 ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
3283                                                 NULL, 0);
3284                 if (ret) {
3285                         unlock_page(page);
3286                         put_page(page);
3287                         btrfs_delalloc_release_metadata(BTRFS_I(inode),
3288                                                          PAGE_SIZE, true);
3289                         btrfs_delalloc_release_extents(BTRFS_I(inode),
3290                                                        PAGE_SIZE, true);
3291
3292                         clear_extent_bits(&BTRFS_I(inode)->io_tree,
3293                                           page_start, page_end,
3294                                           EXTENT_LOCKED | EXTENT_BOUNDARY);
3295                         goto out;
3296
3297                 }
3298                 set_page_dirty(page);
3299
3300                 unlock_extent(&BTRFS_I(inode)->io_tree,
3301                               page_start, page_end);
3302                 unlock_page(page);
3303                 put_page(page);
3304
3305                 index++;
3306                 btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE,
3307                                                false);
3308                 balance_dirty_pages_ratelimited(inode->i_mapping);
3309                 btrfs_throttle(fs_info);
3310         }
3311         WARN_ON(nr != cluster->nr);
3312 out:
3313         kfree(ra);
3314         return ret;
3315 }
3316
3317 static noinline_for_stack
3318 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
3319                          struct file_extent_cluster *cluster)
3320 {
3321         int ret;
3322
3323         if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
3324                 ret = relocate_file_extent_cluster(inode, cluster);
3325                 if (ret)
3326                         return ret;
3327                 cluster->nr = 0;
3328         }
3329
3330         if (!cluster->nr)
3331                 cluster->start = extent_key->objectid;
3332         else
3333                 BUG_ON(cluster->nr >= MAX_EXTENTS);
3334         cluster->end = extent_key->objectid + extent_key->offset - 1;
3335         cluster->boundary[cluster->nr] = extent_key->objectid;
3336         cluster->nr++;
3337
3338         if (cluster->nr >= MAX_EXTENTS) {
3339                 ret = relocate_file_extent_cluster(inode, cluster);
3340                 if (ret)
3341                         return ret;
3342                 cluster->nr = 0;
3343         }
3344         return 0;
3345 }
3346
3347 /*
3348  * helper to add a tree block to the list.
3349  * the major work is getting the generation and level of the block
3350  */
3351 static int add_tree_block(struct reloc_control *rc,
3352                           struct btrfs_key *extent_key,
3353                           struct btrfs_path *path,
3354                           struct rb_root *blocks)
3355 {
3356         struct extent_buffer *eb;
3357         struct btrfs_extent_item *ei;
3358         struct btrfs_tree_block_info *bi;
3359         struct tree_block *block;
3360         struct rb_node *rb_node;
3361         u32 item_size;
3362         int level = -1;
3363         u64 generation;
3364
3365         eb =  path->nodes[0];
3366         item_size = btrfs_item_size_nr(eb, path->slots[0]);
3367
3368         if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
3369             item_size >= sizeof(*ei) + sizeof(*bi)) {
3370                 ei = btrfs_item_ptr(eb, path->slots[0],
3371                                 struct btrfs_extent_item);
3372                 if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
3373                         bi = (struct btrfs_tree_block_info *)(ei + 1);
3374                         level = btrfs_tree_block_level(eb, bi);
3375                 } else {
3376                         level = (int)extent_key->offset;
3377                 }
3378                 generation = btrfs_extent_generation(eb, ei);
3379         } else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
3380                 btrfs_print_v0_err(eb->fs_info);
3381                 btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3382                 return -EINVAL;
3383         } else {
3384                 BUG();
3385         }
3386
3387         btrfs_release_path(path);
3388
3389         BUG_ON(level == -1);
3390
3391         block = kmalloc(sizeof(*block), GFP_NOFS);
3392         if (!block)
3393                 return -ENOMEM;
3394
3395         block->bytenr = extent_key->objectid;
3396         block->key.objectid = rc->extent_root->fs_info->nodesize;
3397         block->key.offset = generation;
3398         block->level = level;
3399         block->key_ready = 0;
3400
3401         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
3402         if (rb_node)
3403                 backref_tree_panic(rb_node, -EEXIST, block->bytenr);
3404
3405         return 0;
3406 }
3407
3408 /*
3409  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
3410  */
3411 static int __add_tree_block(struct reloc_control *rc,
3412                             u64 bytenr, u32 blocksize,
3413                             struct rb_root *blocks)
3414 {
3415         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3416         struct btrfs_path *path;
3417         struct btrfs_key key;
3418         int ret;
3419         bool skinny = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
3420
3421         if (tree_block_processed(bytenr, rc))
3422                 return 0;
3423
3424         if (tree_search(blocks, bytenr))
3425                 return 0;
3426
3427         path = btrfs_alloc_path();
3428         if (!path)
3429                 return -ENOMEM;
3430 again:
3431         key.objectid = bytenr;
3432         if (skinny) {
3433                 key.type = BTRFS_METADATA_ITEM_KEY;
3434                 key.offset = (u64)-1;
3435         } else {
3436                 key.type = BTRFS_EXTENT_ITEM_KEY;
3437                 key.offset = blocksize;
3438         }
3439
3440         path->search_commit_root = 1;
3441         path->skip_locking = 1;
3442         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
3443         if (ret < 0)
3444                 goto out;
3445
3446         if (ret > 0 && skinny) {
3447                 if (path->slots[0]) {
3448                         path->slots[0]--;
3449                         btrfs_item_key_to_cpu(path->nodes[0], &key,
3450                                               path->slots[0]);
3451                         if (key.objectid == bytenr &&
3452                             (key.type == BTRFS_METADATA_ITEM_KEY ||
3453                              (key.type == BTRFS_EXTENT_ITEM_KEY &&
3454                               key.offset == blocksize)))
3455                                 ret = 0;
3456                 }
3457
3458                 if (ret) {
3459                         skinny = false;
3460                         btrfs_release_path(path);
3461                         goto again;
3462                 }
3463         }
3464         if (ret) {
3465                 ASSERT(ret == 1);
3466                 btrfs_print_leaf(path->nodes[0]);
3467                 btrfs_err(fs_info,
3468              "tree block extent item (%llu) is not found in extent tree",
3469                      bytenr);
3470                 WARN_ON(1);
3471                 ret = -EINVAL;
3472                 goto out;
3473         }
3474
3475         ret = add_tree_block(rc, &key, path, blocks);
3476 out:
3477         btrfs_free_path(path);
3478         return ret;
3479 }
3480
3481 /*
3482  * helper to check if the block use full backrefs for pointers in it
3483  */
3484 static int block_use_full_backref(struct reloc_control *rc,
3485                                   struct extent_buffer *eb)
3486 {
3487         u64 flags;
3488         int ret;
3489
3490         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
3491             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
3492                 return 1;
3493
3494         ret = btrfs_lookup_extent_info(NULL, rc->extent_root->fs_info,
3495                                        eb->start, btrfs_header_level(eb), 1,
3496                                        NULL, &flags);
3497         BUG_ON(ret);
3498
3499         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
3500                 ret = 1;
3501         else
3502                 ret = 0;
3503         return ret;
3504 }
3505
3506 static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
3507                                     struct btrfs_block_group_cache *block_group,
3508                                     struct inode *inode,
3509                                     u64 ino)
3510 {
3511         struct btrfs_key key;
3512         struct btrfs_root *root = fs_info->tree_root;
3513         struct btrfs_trans_handle *trans;
3514         int ret = 0;
3515
3516         if (inode)
3517                 goto truncate;
3518
3519         key.objectid = ino;
3520         key.type = BTRFS_INODE_ITEM_KEY;
3521         key.offset = 0;
3522
3523         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
3524         if (IS_ERR(inode))
3525                 return -ENOENT;
3526
3527 truncate:
3528         ret = btrfs_check_trunc_cache_free_space(fs_info,
3529                                                  &fs_info->global_block_rsv);
3530         if (ret)
3531                 goto out;
3532
3533         trans = btrfs_join_transaction(root);
3534         if (IS_ERR(trans)) {
3535                 ret = PTR_ERR(trans);
3536                 goto out;
3537         }
3538
3539         ret = btrfs_truncate_free_space_cache(trans, block_group, inode);
3540
3541         btrfs_end_transaction(trans);
3542         btrfs_btree_balance_dirty(fs_info);
3543 out:
3544         iput(inode);
3545         return ret;
3546 }
3547
3548 /*
3549  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
3550  * this function scans fs tree to find blocks reference the data extent
3551  */
3552 static int find_data_references(struct reloc_control *rc,
3553                                 struct btrfs_key *extent_key,
3554                                 struct extent_buffer *leaf,
3555                                 struct btrfs_extent_data_ref *ref,
3556                                 struct rb_root *blocks)
3557 {
3558         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3559         struct btrfs_path *path;
3560         struct tree_block *block;
3561         struct btrfs_root *root;
3562         struct btrfs_file_extent_item *fi;
3563         struct rb_node *rb_node;
3564         struct btrfs_key key;
3565         u64 ref_root;
3566         u64 ref_objectid;
3567         u64 ref_offset;
3568         u32 ref_count;
3569         u32 nritems;
3570         int err = 0;
3571         int added = 0;
3572         int counted;
3573         int ret;
3574
3575         ref_root = btrfs_extent_data_ref_root(leaf, ref);
3576         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
3577         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
3578         ref_count = btrfs_extent_data_ref_count(leaf, ref);
3579
3580         /*
3581          * This is an extent belonging to the free space cache, lets just delete
3582          * it and redo the search.
3583          */
3584         if (ref_root == BTRFS_ROOT_TREE_OBJECTID) {
3585                 ret = delete_block_group_cache(fs_info, rc->block_group,
3586                                                NULL, ref_objectid);
3587                 if (ret != -ENOENT)
3588                         return ret;
3589                 ret = 0;
3590         }
3591
3592         path = btrfs_alloc_path();
3593         if (!path)
3594                 return -ENOMEM;
3595         path->reada = READA_FORWARD;
3596
3597         root = read_fs_root(fs_info, ref_root);
3598         if (IS_ERR(root)) {
3599                 err = PTR_ERR(root);
3600                 goto out;
3601         }
3602
3603         key.objectid = ref_objectid;
3604         key.type = BTRFS_EXTENT_DATA_KEY;
3605         if (ref_offset > ((u64)-1 << 32))
3606                 key.offset = 0;
3607         else
3608                 key.offset = ref_offset;
3609
3610         path->search_commit_root = 1;
3611         path->skip_locking = 1;
3612         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3613         if (ret < 0) {
3614                 err = ret;
3615                 goto out;
3616         }
3617
3618         leaf = path->nodes[0];
3619         nritems = btrfs_header_nritems(leaf);
3620         /*
3621          * the references in tree blocks that use full backrefs
3622          * are not counted in
3623          */
3624         if (block_use_full_backref(rc, leaf))
3625                 counted = 0;
3626         else
3627                 counted = 1;
3628         rb_node = tree_search(blocks, leaf->start);
3629         if (rb_node) {
3630                 if (counted)
3631                         added = 1;
3632                 else
3633                         path->slots[0] = nritems;
3634         }
3635
3636         while (ref_count > 0) {
3637                 while (path->slots[0] >= nritems) {
3638                         ret = btrfs_next_leaf(root, path);
3639                         if (ret < 0) {
3640                                 err = ret;
3641                                 goto out;
3642                         }
3643                         if (WARN_ON(ret > 0))
3644                                 goto out;
3645
3646                         leaf = path->nodes[0];
3647                         nritems = btrfs_header_nritems(leaf);
3648                         added = 0;
3649
3650                         if (block_use_full_backref(rc, leaf))
3651                                 counted = 0;
3652                         else
3653                                 counted = 1;
3654                         rb_node = tree_search(blocks, leaf->start);
3655                         if (rb_node) {
3656                                 if (counted)
3657                                         added = 1;
3658                                 else
3659                                         path->slots[0] = nritems;
3660                         }
3661                 }
3662
3663                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3664                 if (WARN_ON(key.objectid != ref_objectid ||
3665                     key.type != BTRFS_EXTENT_DATA_KEY))
3666                         break;
3667
3668                 fi = btrfs_item_ptr(leaf, path->slots[0],
3669                                     struct btrfs_file_extent_item);
3670
3671                 if (btrfs_file_extent_type(leaf, fi) ==
3672                     BTRFS_FILE_EXTENT_INLINE)
3673                         goto next;
3674
3675                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
3676                     extent_key->objectid)
3677                         goto next;
3678
3679                 key.offset -= btrfs_file_extent_offset(leaf, fi);
3680                 if (key.offset != ref_offset)
3681                         goto next;
3682
3683                 if (counted)
3684                         ref_count--;
3685                 if (added)
3686                         goto next;
3687
3688                 if (!tree_block_processed(leaf->start, rc)) {
3689                         block = kmalloc(sizeof(*block), GFP_NOFS);
3690                         if (!block) {
3691                                 err = -ENOMEM;
3692                                 break;
3693                         }
3694                         block->bytenr = leaf->start;
3695                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
3696                         block->level = 0;
3697                         block->key_ready = 1;
3698                         rb_node = tree_insert(blocks, block->bytenr,
3699                                               &block->rb_node);
3700                         if (rb_node)
3701                                 backref_tree_panic(rb_node, -EEXIST,
3702                                                    block->bytenr);
3703                 }
3704                 if (counted)
3705                         added = 1;
3706                 else
3707                         path->slots[0] = nritems;
3708 next:
3709                 path->slots[0]++;
3710
3711         }
3712 out:
3713         btrfs_free_path(path);
3714         return err;
3715 }
3716
3717 /*
3718  * helper to find all tree blocks that reference a given data extent
3719  */
3720 static noinline_for_stack
3721 int add_data_references(struct reloc_control *rc,
3722                         struct btrfs_key *extent_key,
3723                         struct btrfs_path *path,
3724                         struct rb_root *blocks)
3725 {
3726         struct btrfs_key key;
3727         struct extent_buffer *eb;
3728         struct btrfs_extent_data_ref *dref;
3729         struct btrfs_extent_inline_ref *iref;
3730         unsigned long ptr;
3731         unsigned long end;
3732         u32 blocksize = rc->extent_root->fs_info->nodesize;
3733         int ret = 0;
3734         int err = 0;
3735
3736         eb = path->nodes[0];
3737         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3738         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3739         ptr += sizeof(struct btrfs_extent_item);
3740
3741         while (ptr < end) {
3742                 iref = (struct btrfs_extent_inline_ref *)ptr;
3743                 key.type = btrfs_get_extent_inline_ref_type(eb, iref,
3744                                                         BTRFS_REF_TYPE_DATA);
3745                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3746                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3747                         ret = __add_tree_block(rc, key.offset, blocksize,
3748                                                blocks);
3749                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3750                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3751                         ret = find_data_references(rc, extent_key,
3752                                                    eb, dref, blocks);
3753                 } else {
3754                         ret = -EUCLEAN;
3755                         btrfs_err(rc->extent_root->fs_info,
3756                      "extent %llu slot %d has an invalid inline ref type",
3757                              eb->start, path->slots[0]);
3758                 }
3759                 if (ret) {
3760                         err = ret;
3761                         goto out;
3762                 }
3763                 ptr += btrfs_extent_inline_ref_size(key.type);
3764         }
3765         WARN_ON(ptr > end);
3766
3767         while (1) {
3768                 cond_resched();
3769                 eb = path->nodes[0];
3770                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3771                         ret = btrfs_next_leaf(rc->extent_root, path);
3772                         if (ret < 0) {
3773                                 err = ret;
3774                                 break;
3775                         }
3776                         if (ret > 0)
3777                                 break;
3778                         eb = path->nodes[0];
3779                 }
3780
3781                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3782                 if (key.objectid != extent_key->objectid)
3783                         break;
3784
3785                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3786                         ret = __add_tree_block(rc, key.offset, blocksize,
3787                                                blocks);
3788                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3789                         dref = btrfs_item_ptr(eb, path->slots[0],
3790                                               struct btrfs_extent_data_ref);
3791                         ret = find_data_references(rc, extent_key,
3792                                                    eb, dref, blocks);
3793                 } else if (unlikely(key.type == BTRFS_EXTENT_REF_V0_KEY)) {
3794                         btrfs_print_v0_err(eb->fs_info);
3795                         btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
3796                         ret = -EINVAL;
3797                 } else {
3798                         ret = 0;
3799                 }
3800                 if (ret) {
3801                         err = ret;
3802                         break;
3803                 }
3804                 path->slots[0]++;
3805         }
3806 out:
3807         btrfs_release_path(path);
3808         if (err)
3809                 free_block_list(blocks);
3810         return err;
3811 }
3812
3813 /*
3814  * helper to find next unprocessed extent
3815  */
3816 static noinline_for_stack
3817 int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
3818                      struct btrfs_key *extent_key)
3819 {
3820         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3821         struct btrfs_key key;
3822         struct extent_buffer *leaf;
3823         u64 start, end, last;
3824         int ret;
3825
3826         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3827         while (1) {
3828                 cond_resched();
3829                 if (rc->search_start >= last) {
3830                         ret = 1;
3831                         break;
3832                 }
3833
3834                 key.objectid = rc->search_start;
3835                 key.type = BTRFS_EXTENT_ITEM_KEY;
3836                 key.offset = 0;
3837
3838                 path->search_commit_root = 1;
3839                 path->skip_locking = 1;
3840                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3841                                         0, 0);
3842                 if (ret < 0)
3843                         break;
3844 next:
3845                 leaf = path->nodes[0];
3846                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3847                         ret = btrfs_next_leaf(rc->extent_root, path);
3848                         if (ret != 0)
3849                                 break;
3850                         leaf = path->nodes[0];
3851                 }
3852
3853                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3854                 if (key.objectid >= last) {
3855                         ret = 1;
3856                         break;
3857                 }
3858
3859                 if (key.type != BTRFS_EXTENT_ITEM_KEY &&
3860                     key.type != BTRFS_METADATA_ITEM_KEY) {
3861                         path->slots[0]++;
3862                         goto next;
3863                 }
3864
3865                 if (key.type == BTRFS_EXTENT_ITEM_KEY &&
3866                     key.objectid + key.offset <= rc->search_start) {
3867                         path->slots[0]++;
3868                         goto next;
3869                 }
3870
3871                 if (key.type == BTRFS_METADATA_ITEM_KEY &&
3872                     key.objectid + fs_info->nodesize <=
3873                     rc->search_start) {
3874                         path->slots[0]++;
3875                         goto next;
3876                 }
3877
3878                 ret = find_first_extent_bit(&rc->processed_blocks,
3879                                             key.objectid, &start, &end,
3880                                             EXTENT_DIRTY, NULL);
3881
3882                 if (ret == 0 && start <= key.objectid) {
3883                         btrfs_release_path(path);
3884                         rc->search_start = end + 1;
3885                 } else {
3886                         if (key.type == BTRFS_EXTENT_ITEM_KEY)
3887                                 rc->search_start = key.objectid + key.offset;
3888                         else
3889                                 rc->search_start = key.objectid +
3890                                         fs_info->nodesize;
3891                         memcpy(extent_key, &key, sizeof(key));
3892                         return 0;
3893                 }
3894         }
3895         btrfs_release_path(path);
3896         return ret;
3897 }
3898
3899 static void set_reloc_control(struct reloc_control *rc)
3900 {
3901         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3902
3903         mutex_lock(&fs_info->reloc_mutex);
3904         fs_info->reloc_ctl = rc;
3905         mutex_unlock(&fs_info->reloc_mutex);
3906 }
3907
3908 static void unset_reloc_control(struct reloc_control *rc)
3909 {
3910         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3911
3912         mutex_lock(&fs_info->reloc_mutex);
3913         fs_info->reloc_ctl = NULL;
3914         mutex_unlock(&fs_info->reloc_mutex);
3915 }
3916
3917 static int check_extent_flags(u64 flags)
3918 {
3919         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3920             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3921                 return 1;
3922         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3923             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3924                 return 1;
3925         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3926             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3927                 return 1;
3928         return 0;
3929 }
3930
3931 static noinline_for_stack
3932 int prepare_to_relocate(struct reloc_control *rc)
3933 {
3934         struct btrfs_trans_handle *trans;
3935         int ret;
3936
3937         rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root->fs_info,
3938                                               BTRFS_BLOCK_RSV_TEMP);
3939         if (!rc->block_rsv)
3940                 return -ENOMEM;
3941
3942         memset(&rc->cluster, 0, sizeof(rc->cluster));
3943         rc->search_start = rc->block_group->key.objectid;
3944         rc->extents_found = 0;
3945         rc->nodes_relocated = 0;
3946         rc->merging_rsv_size = 0;
3947         rc->reserved_bytes = 0;
3948         rc->block_rsv->size = rc->extent_root->fs_info->nodesize *
3949                               RELOCATION_RESERVED_NODES;
3950         ret = btrfs_block_rsv_refill(rc->extent_root,
3951                                      rc->block_rsv, rc->block_rsv->size,
3952                                      BTRFS_RESERVE_FLUSH_ALL);
3953         if (ret)
3954                 return ret;
3955
3956         rc->create_reloc_tree = 1;
3957         set_reloc_control(rc);
3958
3959         trans = btrfs_join_transaction(rc->extent_root);
3960         if (IS_ERR(trans)) {
3961                 unset_reloc_control(rc);
3962                 /*
3963                  * extent tree is not a ref_cow tree and has no reloc_root to
3964                  * cleanup.  And callers are responsible to free the above
3965                  * block rsv.
3966                  */
3967                 return PTR_ERR(trans);
3968         }
3969         btrfs_commit_transaction(trans);
3970         return 0;
3971 }
3972
3973 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3974 {
3975         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3976         struct rb_root blocks = RB_ROOT;
3977         struct btrfs_key key;
3978         struct btrfs_trans_handle *trans = NULL;
3979         struct btrfs_path *path;
3980         struct btrfs_extent_item *ei;
3981         u64 flags;
3982         u32 item_size;
3983         int ret;
3984         int err = 0;
3985         int progress = 0;
3986
3987         path = btrfs_alloc_path();
3988         if (!path)
3989                 return -ENOMEM;
3990         path->reada = READA_FORWARD;
3991
3992         ret = prepare_to_relocate(rc);
3993         if (ret) {
3994                 err = ret;
3995                 goto out_free;
3996         }
3997
3998         while (1) {
3999                 rc->reserved_bytes = 0;
4000                 ret = btrfs_block_rsv_refill(rc->extent_root,
4001                                         rc->block_rsv, rc->block_rsv->size,
4002                                         BTRFS_RESERVE_FLUSH_ALL);
4003                 if (ret) {
4004                         err = ret;
4005                         break;
4006                 }
4007                 progress++;
4008                 trans = btrfs_start_transaction(rc->extent_root, 0);
4009                 if (IS_ERR(trans)) {
4010                         err = PTR_ERR(trans);
4011                         trans = NULL;
4012                         break;
4013                 }
4014 restart:
4015                 if (update_backref_cache(trans, &rc->backref_cache)) {
4016                         btrfs_end_transaction(trans);
4017                         trans = NULL;
4018                         continue;
4019                 }
4020
4021                 ret = find_next_extent(rc, path, &key);
4022                 if (ret < 0)
4023                         err = ret;
4024                 if (ret != 0)
4025                         break;
4026
4027                 rc->extents_found++;
4028
4029                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
4030                                     struct btrfs_extent_item);
4031                 item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
4032                 if (item_size >= sizeof(*ei)) {
4033                         flags = btrfs_extent_flags(path->nodes[0], ei);
4034                         ret = check_extent_flags(flags);
4035                         BUG_ON(ret);
4036                 } else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
4037                         err = -EINVAL;
4038                         btrfs_print_v0_err(trans->fs_info);
4039                         btrfs_abort_transaction(trans, err);
4040                         break;
4041                 } else {
4042                         BUG();
4043                 }
4044
4045                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
4046                         ret = add_tree_block(rc, &key, path, &blocks);
4047                 } else if (rc->stage == UPDATE_DATA_PTRS &&
4048                            (flags & BTRFS_EXTENT_FLAG_DATA)) {
4049                         ret = add_data_references(rc, &key, path, &blocks);
4050                 } else {
4051                         btrfs_release_path(path);
4052                         ret = 0;
4053                 }
4054                 if (ret < 0) {
4055                         err = ret;
4056                         break;
4057                 }
4058
4059                 if (!RB_EMPTY_ROOT(&blocks)) {
4060                         ret = relocate_tree_blocks(trans, rc, &blocks);
4061                         if (ret < 0) {
4062                                 /*
4063                                  * if we fail to relocate tree blocks, force to update
4064                                  * backref cache when committing transaction.
4065                                  */
4066                                 rc->backref_cache.last_trans = trans->transid - 1;
4067
4068                                 if (ret != -EAGAIN) {
4069                                         err = ret;
4070                                         break;
4071                                 }
4072                                 rc->extents_found--;
4073                                 rc->search_start = key.objectid;
4074                         }
4075                 }
4076
4077                 btrfs_end_transaction_throttle(trans);
4078                 btrfs_btree_balance_dirty(fs_info);
4079                 trans = NULL;
4080
4081                 if (rc->stage == MOVE_DATA_EXTENTS &&
4082                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
4083                         rc->found_file_extent = 1;
4084                         ret = relocate_data_extent(rc->data_inode,
4085                                                    &key, &rc->cluster);
4086                         if (ret < 0) {
4087                                 err = ret;
4088                                 break;
4089                         }
4090                 }
4091         }
4092         if (trans && progress && err == -ENOSPC) {
4093                 ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);
4094                 if (ret == 1) {
4095                         err = 0;
4096                         progress = 0;
4097                         goto restart;
4098                 }
4099         }
4100
4101         btrfs_release_path(path);
4102         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY);
4103
4104         if (trans) {
4105                 btrfs_end_transaction_throttle(trans);
4106                 btrfs_btree_balance_dirty(fs_info);
4107         }
4108
4109         if (!err) {
4110                 ret = relocate_file_extent_cluster(rc->data_inode,
4111                                                    &rc->cluster);
4112                 if (ret < 0)
4113                         err = ret;
4114         }
4115
4116         rc->create_reloc_tree = 0;
4117         set_reloc_control(rc);
4118
4119         backref_cache_cleanup(&rc->backref_cache);
4120         btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4121
4122         err = prepare_to_merge(rc, err);
4123
4124         merge_reloc_roots(rc);
4125
4126         rc->merge_reloc_tree = 0;
4127         unset_reloc_control(rc);
4128         btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
4129
4130         /* get rid of pinned extents */
4131         trans = btrfs_join_transaction(rc->extent_root);
4132         if (IS_ERR(trans)) {
4133                 err = PTR_ERR(trans);
4134                 goto out_free;
4135         }
4136         btrfs_commit_transaction(trans);
4137         ret = clean_dirty_subvols(rc);
4138         if (ret < 0 && !err)
4139                 err = ret;
4140 out_free:
4141         btrfs_free_block_rsv(fs_info, rc->block_rsv);
4142         btrfs_free_path(path);
4143         return err;
4144 }
4145
4146 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
4147                                  struct btrfs_root *root, u64 objectid)
4148 {
4149         struct btrfs_path *path;
4150         struct btrfs_inode_item *item;
4151         struct extent_buffer *leaf;
4152         int ret;
4153
4154         path = btrfs_alloc_path();
4155         if (!path)
4156                 return -ENOMEM;
4157
4158         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
4159         if (ret)
4160                 goto out;
4161
4162         leaf = path->nodes[0];
4163         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
4164         memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));
4165         btrfs_set_inode_generation(leaf, item, 1);
4166         btrfs_set_inode_size(leaf, item, 0);
4167         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
4168         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS |
4169                                           BTRFS_INODE_PREALLOC);
4170         btrfs_mark_buffer_dirty(leaf);
4171 out:
4172         btrfs_free_path(path);
4173         return ret;
4174 }
4175
4176 /*
4177  * helper to create inode for data relocation.
4178  * the inode is in data relocation tree and its link count is 0
4179  */
4180 static noinline_for_stack
4181 struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
4182                                  struct btrfs_block_group_cache *group)
4183 {
4184         struct inode *inode = NULL;
4185         struct btrfs_trans_handle *trans;
4186         struct btrfs_root *root;
4187         struct btrfs_key key;
4188         u64 objectid;
4189         int err = 0;
4190
4191         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4192         if (IS_ERR(root))
4193                 return ERR_CAST(root);
4194
4195         trans = btrfs_start_transaction(root, 6);
4196         if (IS_ERR(trans))
4197                 return ERR_CAST(trans);
4198
4199         err = btrfs_find_free_objectid(root, &objectid);
4200         if (err)
4201                 goto out;
4202
4203         err = __insert_orphan_inode(trans, root, objectid);
4204         BUG_ON(err);
4205
4206         key.objectid = objectid;
4207         key.type = BTRFS_INODE_ITEM_KEY;
4208         key.offset = 0;
4209         inode = btrfs_iget(fs_info->sb, &key, root, NULL);
4210         BUG_ON(IS_ERR(inode));
4211         BTRFS_I(inode)->index_cnt = group->key.objectid;
4212
4213         err = btrfs_orphan_add(trans, BTRFS_I(inode));
4214 out:
4215         btrfs_end_transaction(trans);
4216         btrfs_btree_balance_dirty(fs_info);
4217         if (err) {
4218                 if (inode)
4219                         iput(inode);
4220                 inode = ERR_PTR(err);
4221         }
4222         return inode;
4223 }
4224
4225 static struct reloc_control *alloc_reloc_control(void)
4226 {
4227         struct reloc_control *rc;
4228
4229         rc = kzalloc(sizeof(*rc), GFP_NOFS);
4230         if (!rc)
4231                 return NULL;
4232
4233         INIT_LIST_HEAD(&rc->reloc_roots);
4234         INIT_LIST_HEAD(&rc->dirty_subvol_roots);
4235         backref_cache_init(&rc->backref_cache);
4236         mapping_tree_init(&rc->reloc_root_tree);
4237         extent_io_tree_init(&rc->processed_blocks, NULL);
4238         return rc;
4239 }
4240
4241 /*
4242  * Print the block group being relocated
4243  */
4244 static void describe_relocation(struct btrfs_fs_info *fs_info,
4245                                 struct btrfs_block_group_cache *block_group)
4246 {
4247         char buf[128] = {'\0'};
4248
4249         btrfs_describe_block_groups(block_group->flags, buf, sizeof(buf));
4250
4251         btrfs_info(fs_info,
4252                    "relocating block group %llu flags %s",
4253                    block_group->key.objectid, buf);
4254 }
4255
4256 /*
4257  * function to relocate all extents in a block group.
4258  */
4259 int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
4260 {
4261         struct btrfs_block_group_cache *bg;
4262         struct btrfs_root *extent_root = fs_info->extent_root;
4263         struct reloc_control *rc;
4264         struct inode *inode;
4265         struct btrfs_path *path;
4266         int ret;
4267         int rw = 0;
4268         int err = 0;
4269
4270         bg = btrfs_lookup_block_group(fs_info, group_start);
4271         if (!bg)
4272                 return -ENOENT;
4273
4274         if (btrfs_pinned_by_swapfile(fs_info, bg)) {
4275                 btrfs_put_block_group(bg);
4276                 return -ETXTBSY;
4277         }
4278
4279         rc = alloc_reloc_control();
4280         if (!rc) {
4281                 btrfs_put_block_group(bg);
4282                 return -ENOMEM;
4283         }
4284
4285         rc->extent_root = extent_root;
4286         rc->block_group = bg;
4287
4288         ret = btrfs_inc_block_group_ro(rc->block_group);
4289         if (ret) {
4290                 err = ret;
4291                 goto out;
4292         }
4293         rw = 1;
4294
4295         path = btrfs_alloc_path();
4296         if (!path) {
4297                 err = -ENOMEM;
4298                 goto out;
4299         }
4300
4301         inode = lookup_free_space_inode(fs_info, rc->block_group, path);
4302         btrfs_free_path(path);
4303
4304         if (!IS_ERR(inode))
4305                 ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
4306         else
4307                 ret = PTR_ERR(inode);
4308
4309         if (ret && ret != -ENOENT) {
4310                 err = ret;
4311                 goto out;
4312         }
4313
4314         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
4315         if (IS_ERR(rc->data_inode)) {
4316                 err = PTR_ERR(rc->data_inode);
4317                 rc->data_inode = NULL;
4318                 goto out;
4319         }
4320
4321         describe_relocation(fs_info, rc->block_group);
4322
4323         btrfs_wait_block_group_reservations(rc->block_group);
4324         btrfs_wait_nocow_writers(rc->block_group);
4325         btrfs_wait_ordered_roots(fs_info, U64_MAX,
4326                                  rc->block_group->key.objectid,
4327                                  rc->block_group->key.offset);
4328
4329         while (1) {
4330                 mutex_lock(&fs_info->cleaner_mutex);
4331                 ret = relocate_block_group(rc);
4332                 mutex_unlock(&fs_info->cleaner_mutex);
4333                 if (ret < 0) {
4334                         err = ret;
4335                         goto out;
4336                 }
4337
4338                 if (rc->extents_found == 0)
4339                         break;
4340
4341                 btrfs_info(fs_info, "found %llu extents", rc->extents_found);
4342
4343                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
4344                         ret = btrfs_wait_ordered_range(rc->data_inode, 0,
4345                                                        (u64)-1);
4346                         if (ret) {
4347                                 err = ret;
4348                                 goto out;
4349                         }
4350                         invalidate_mapping_pages(rc->data_inode->i_mapping,
4351                                                  0, -1);
4352                         rc->stage = UPDATE_DATA_PTRS;
4353                 }
4354         }
4355
4356         WARN_ON(rc->block_group->pinned > 0);
4357         WARN_ON(rc->block_group->reserved > 0);
4358         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
4359 out:
4360         if (err && rw)
4361                 btrfs_dec_block_group_ro(rc->block_group);
4362         iput(rc->data_inode);
4363         btrfs_put_block_group(rc->block_group);
4364         kfree(rc);
4365         return err;
4366 }
4367
4368 static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
4369 {
4370         struct btrfs_fs_info *fs_info = root->fs_info;
4371         struct btrfs_trans_handle *trans;
4372         int ret, err;
4373
4374         trans = btrfs_start_transaction(fs_info->tree_root, 0);
4375         if (IS_ERR(trans))
4376                 return PTR_ERR(trans);
4377
4378         memset(&root->root_item.drop_progress, 0,
4379                 sizeof(root->root_item.drop_progress));
4380         root->root_item.drop_level = 0;
4381         btrfs_set_root_refs(&root->root_item, 0);
4382         ret = btrfs_update_root(trans, fs_info->tree_root,
4383                                 &root->root_key, &root->root_item);
4384
4385         err = btrfs_end_transaction(trans);
4386         if (err)
4387                 return err;
4388         return ret;
4389 }
4390
4391 /*
4392  * recover relocation interrupted by system crash.
4393  *
4394  * this function resumes merging reloc trees with corresponding fs trees.
4395  * this is important for keeping the sharing of tree blocks
4396  */
4397 int btrfs_recover_relocation(struct btrfs_root *root)
4398 {
4399         struct btrfs_fs_info *fs_info = root->fs_info;
4400         LIST_HEAD(reloc_roots);
4401         struct btrfs_key key;
4402         struct btrfs_root *fs_root;
4403         struct btrfs_root *reloc_root;
4404         struct btrfs_path *path;
4405         struct extent_buffer *leaf;
4406         struct reloc_control *rc = NULL;
4407         struct btrfs_trans_handle *trans;
4408         int ret;
4409         int err = 0;
4410
4411         path = btrfs_alloc_path();
4412         if (!path)
4413                 return -ENOMEM;
4414         path->reada = READA_BACK;
4415
4416         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
4417         key.type = BTRFS_ROOT_ITEM_KEY;
4418         key.offset = (u64)-1;
4419
4420         while (1) {
4421                 ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,
4422                                         path, 0, 0);
4423                 if (ret < 0) {
4424                         err = ret;
4425                         goto out;
4426                 }
4427                 if (ret > 0) {
4428                         if (path->slots[0] == 0)
4429                                 break;
4430                         path->slots[0]--;
4431                 }
4432                 leaf = path->nodes[0];
4433                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4434                 btrfs_release_path(path);
4435
4436                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
4437                     key.type != BTRFS_ROOT_ITEM_KEY)
4438                         break;
4439
4440                 reloc_root = btrfs_read_fs_root(root, &key);
4441                 if (IS_ERR(reloc_root)) {
4442                         err = PTR_ERR(reloc_root);
4443                         goto out;
4444                 }
4445
4446                 list_add(&reloc_root->root_list, &reloc_roots);
4447
4448                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
4449                         fs_root = read_fs_root(fs_info,
4450                                                reloc_root->root_key.offset);
4451                         if (IS_ERR(fs_root)) {
4452                                 ret = PTR_ERR(fs_root);
4453                                 if (ret != -ENOENT) {
4454                                         err = ret;
4455                                         goto out;
4456                                 }
4457                                 ret = mark_garbage_root(reloc_root);
4458                                 if (ret < 0) {
4459                                         err = ret;
4460                                         goto out;
4461                                 }
4462                         }
4463                 }
4464
4465                 if (key.offset == 0)
4466                         break;
4467
4468                 key.offset--;
4469         }
4470         btrfs_release_path(path);
4471
4472         if (list_empty(&reloc_roots))
4473                 goto out;
4474
4475         rc = alloc_reloc_control();
4476         if (!rc) {
4477                 err = -ENOMEM;
4478                 goto out;
4479         }
4480
4481         rc->extent_root = fs_info->extent_root;
4482
4483         set_reloc_control(rc);
4484
4485         trans = btrfs_join_transaction(rc->extent_root);
4486         if (IS_ERR(trans)) {
4487                 unset_reloc_control(rc);
4488                 err = PTR_ERR(trans);
4489                 goto out_free;
4490         }
4491
4492         rc->merge_reloc_tree = 1;
4493
4494         while (!list_empty(&reloc_roots)) {
4495                 reloc_root = list_entry(reloc_roots.next,
4496                                         struct btrfs_root, root_list);
4497                 list_del(&reloc_root->root_list);
4498
4499                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
4500                         list_add_tail(&reloc_root->root_list,
4501                                       &rc->reloc_roots);
4502                         continue;
4503                 }
4504
4505                 fs_root = read_fs_root(fs_info, reloc_root->root_key.offset);
4506                 if (IS_ERR(fs_root)) {
4507                         err = PTR_ERR(fs_root);
4508                         goto out_free;
4509                 }
4510
4511                 err = __add_reloc_root(reloc_root);
4512                 BUG_ON(err < 0); /* -ENOMEM or logic error */
4513                 fs_root->reloc_root = reloc_root;
4514         }
4515
4516         err = btrfs_commit_transaction(trans);
4517         if (err)
4518                 goto out_free;
4519
4520         merge_reloc_roots(rc);
4521
4522         unset_reloc_control(rc);
4523
4524         trans = btrfs_join_transaction(rc->extent_root);
4525         if (IS_ERR(trans)) {
4526                 err = PTR_ERR(trans);
4527                 goto out_free;
4528         }
4529         err = btrfs_commit_transaction(trans);
4530
4531         ret = clean_dirty_subvols(rc);
4532         if (ret < 0 && !err)
4533                 err = ret;
4534 out_free:
4535         kfree(rc);
4536 out:
4537         if (!list_empty(&reloc_roots))
4538                 free_reloc_roots(&reloc_roots);
4539
4540         btrfs_free_path(path);
4541
4542         if (err == 0) {
4543                 /* cleanup orphan inode in data relocation tree */
4544                 fs_root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
4545                 if (IS_ERR(fs_root))
4546                         err = PTR_ERR(fs_root);
4547                 else
4548                         err = btrfs_orphan_cleanup(fs_root);
4549         }
4550         return err;
4551 }
4552
4553 /*
4554  * helper to add ordered checksum for data relocation.
4555  *
4556  * cloning checksum properly handles the nodatasum extents.
4557  * it also saves CPU time to re-calculate the checksum.
4558  */
4559 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
4560 {
4561         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
4562         struct btrfs_ordered_sum *sums;
4563         struct btrfs_ordered_extent *ordered;
4564         int ret;
4565         u64 disk_bytenr;
4566         u64 new_bytenr;
4567         LIST_HEAD(list);
4568
4569         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
4570         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
4571
4572         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
4573         ret = btrfs_lookup_csums_range(fs_info->csum_root, disk_bytenr,
4574                                        disk_bytenr + len - 1, &list, 0);
4575         if (ret)
4576                 goto out;
4577
4578         while (!list_empty(&list)) {
4579                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
4580                 list_del_init(&sums->list);
4581
4582                 /*
4583                  * We need to offset the new_bytenr based on where the csum is.
4584                  * We need to do this because we will read in entire prealloc
4585                  * extents but we may have written to say the middle of the
4586                  * prealloc extent, so we need to make sure the csum goes with
4587                  * the right disk offset.
4588                  *
4589                  * We can do this because the data reloc inode refers strictly
4590                  * to the on disk bytes, so we don't have to worry about
4591                  * disk_len vs real len like with real inodes since it's all
4592                  * disk length.
4593                  */
4594                 new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
4595                 sums->bytenr = new_bytenr;
4596
4597                 btrfs_add_ordered_sum(inode, ordered, sums);
4598         }
4599 out:
4600         btrfs_put_ordered_extent(ordered);
4601         return ret;
4602 }
4603
4604 int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
4605                           struct btrfs_root *root, struct extent_buffer *buf,
4606                           struct extent_buffer *cow)
4607 {
4608         struct btrfs_fs_info *fs_info = root->fs_info;
4609         struct reloc_control *rc;
4610         struct backref_node *node;
4611         int first_cow = 0;
4612         int level;
4613         int ret = 0;
4614
4615         rc = fs_info->reloc_ctl;
4616         if (!rc)
4617                 return 0;
4618
4619         BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
4620                root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
4621
4622         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
4623                 if (buf == root->node)
4624                         __update_reloc_root(root, cow->start);
4625         }
4626
4627         level = btrfs_header_level(buf);
4628         if (btrfs_header_generation(buf) <=
4629             btrfs_root_last_snapshot(&root->root_item))
4630                 first_cow = 1;
4631
4632         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
4633             rc->create_reloc_tree) {
4634                 WARN_ON(!first_cow && level == 0);
4635
4636                 node = rc->backref_cache.path[level];
4637                 BUG_ON(node->bytenr != buf->start &&
4638                        node->new_bytenr != buf->start);
4639
4640                 drop_node_buffer(node);
4641                 extent_buffer_get(cow);
4642                 node->eb = cow;
4643                 node->new_bytenr = cow->start;
4644
4645                 if (!node->pending) {
4646                         list_move_tail(&node->list,
4647                                        &rc->backref_cache.pending[level]);
4648                         node->pending = 1;
4649                 }
4650
4651                 if (first_cow)
4652                         __mark_block_processed(rc, node);
4653
4654                 if (first_cow && level > 0)
4655                         rc->nodes_relocated += buf->len;
4656         }
4657
4658         if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
4659                 ret = replace_file_extents(trans, rc, root, cow);
4660         return ret;
4661 }
4662
4663 /*
4664  * called before creating snapshot. it calculates metadata reservation
4665  * required for relocating tree blocks in the snapshot
4666  */
4667 void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
4668                               u64 *bytes_to_reserve)
4669 {
4670         struct btrfs_root *root;
4671         struct reloc_control *rc;
4672
4673         root = pending->root;
4674         if (!root->reloc_root)
4675                 return;
4676
4677         rc = root->fs_info->reloc_ctl;
4678         if (!rc->merge_reloc_tree)
4679                 return;
4680
4681         root = root->reloc_root;
4682         BUG_ON(btrfs_root_refs(&root->root_item) == 0);
4683         /*
4684          * relocation is in the stage of merging trees. the space
4685          * used by merging a reloc tree is twice the size of
4686          * relocated tree nodes in the worst case. half for cowing
4687          * the reloc tree, half for cowing the fs tree. the space
4688          * used by cowing the reloc tree will be freed after the
4689          * tree is dropped. if we create snapshot, cowing the fs
4690          * tree may use more space than it frees. so we need
4691          * reserve extra space.
4692          */
4693         *bytes_to_reserve += rc->nodes_relocated;
4694 }
4695
4696 /*
4697  * called after snapshot is created. migrate block reservation
4698  * and create reloc root for the newly created snapshot
4699  */
4700 int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
4701                                struct btrfs_pending_snapshot *pending)
4702 {
4703         struct btrfs_root *root = pending->root;
4704         struct btrfs_root *reloc_root;
4705         struct btrfs_root *new_root;
4706         struct reloc_control *rc;
4707         int ret;
4708
4709         if (!root->reloc_root)
4710                 return 0;
4711
4712         rc = root->fs_info->reloc_ctl;
4713         rc->merging_rsv_size += rc->nodes_relocated;
4714
4715         if (rc->merge_reloc_tree) {
4716                 ret = btrfs_block_rsv_migrate(&pending->block_rsv,
4717                                               rc->block_rsv,
4718                                               rc->nodes_relocated, true);
4719                 if (ret)
4720                         return ret;
4721         }
4722
4723         new_root = pending->snap;
4724         reloc_root = create_reloc_root(trans, root->reloc_root,
4725                                        new_root->root_key.objectid);
4726         if (IS_ERR(reloc_root))
4727                 return PTR_ERR(reloc_root);
4728
4729         ret = __add_reloc_root(reloc_root);
4730         BUG_ON(ret < 0);
4731         new_root->reloc_root = reloc_root;
4732
4733         if (rc->create_reloc_tree)
4734                 ret = clone_backref_node(trans, rc, root, reloc_root);
4735         return ret;
4736 }