fs/btrfs/relocation.c

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