fs/btrfs/relocation.c

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