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 "ctree.h"
  25 #include "disk-io.h"
  26 #include "transaction.h"
  27 #include "volumes.h"
  28 #include "locking.h"
  29 #include "btrfs_inode.h"
  30 #include "async-thread.h"
  31
  32 /*
  33  * backref_node, mapping_node and tree_block start with this
  34  */
  35 struct tree_entry {
  36         struct rb_node rb_node;
  37         u64 bytenr;
  38 };
  39
  40 /*
  41  * present a tree block in the backref cache
  42  */
  43 struct backref_node {
  44         struct rb_node rb_node;
  45         u64 bytenr;
  46         /* objectid tree block owner */
  47         u64 owner;
  48         /* list of upper level blocks reference this block */
  49         struct list_head upper;
  50         /* list of child blocks in the cache */
  51         struct list_head lower;
  52         /* NULL if this node is not tree root */
  53         struct btrfs_root *root;
  54         /* extent buffer got by COW the block */
  55         struct extent_buffer *eb;
  56         /* level of tree block */
  57         unsigned int level:8;
  58         /* 1 if the block is root of old snapshot */
  59         unsigned int old_root:1;
  60         /* 1 if no child blocks in the cache */
  61         unsigned int lowest:1;
  62         /* is the extent buffer locked */
  63         unsigned int locked:1;
  64         /* has the block been processed */
  65         unsigned int processed:1;
  66         /* have backrefs of this block been checked */
  67         unsigned int checked:1;
  68 };
  69
  70 /*
  71  * present a block pointer in the backref cache
  72  */
  73 struct backref_edge {
  74         struct list_head list[2];
  75         struct backref_node *node[2];
  76         u64 blockptr;
  77 };
  78
  79 #define LOWER   0
  80 #define UPPER   1
  81
  82 struct backref_cache {
  83         /* red black tree of all backref nodes in the cache */
  84         struct rb_root rb_root;
  85         /* list of backref nodes with no child block in the cache */
  86         struct list_head pending[BTRFS_MAX_LEVEL];
  87         spinlock_t lock;
  88 };
  89
  90 /*
  91  * map address of tree root to tree
  92  */
  93 struct mapping_node {
  94         struct rb_node rb_node;
  95         u64 bytenr;
  96         void *data;
  97 };
  98
  99 struct mapping_tree {
 100         struct rb_root rb_root;
 101         spinlock_t lock;
 102 };
 103
 104 /*
 105  * present a tree block to process
 106  */
 107 struct tree_block {
 108         struct rb_node rb_node;
 109         u64 bytenr;
 110         struct btrfs_key key;
 111         unsigned int level:8;
 112         unsigned int key_ready:1;
 113 };
 114
 115 /* inode vector */
 116 #define INODEVEC_SIZE 16
 117
 118 struct inodevec {
 119         struct list_head list;
 120         struct inode *inode[INODEVEC_SIZE];
 121         int nr;
 122 };
 123
 124 struct reloc_control {
 125         /* block group to relocate */
 126         struct btrfs_block_group_cache *block_group;
 127         /* extent tree */
 128         struct btrfs_root *extent_root;
 129         /* inode for moving data */
 130         struct inode *data_inode;
 131         struct btrfs_workers workers;
 132         /* tree blocks have been processed */
 133         struct extent_io_tree processed_blocks;
 134         /* map start of tree root to corresponding reloc tree */
 135         struct mapping_tree reloc_root_tree;
 136         /* list of reloc trees */
 137         struct list_head reloc_roots;
 138         u64 search_start;
 139         u64 extents_found;
 140         u64 extents_skipped;
 141         int stage;
 142         int create_reloc_root;
 143         unsigned int found_file_extent:1;
 144         unsigned int found_old_snapshot:1;
 145 };
 146
 147 /* stages of data relocation */
 148 #define MOVE_DATA_EXTENTS       0
 149 #define UPDATE_DATA_PTRS        1
 150
 151 /*
 152  * merge reloc tree to corresponding fs tree in worker threads
 153  */
 154 struct async_merge {
 155         struct btrfs_work work;
 156         struct reloc_control *rc;
 157         struct btrfs_root *root;
 158         struct completion *done;
 159         atomic_t *num_pending;
 160 };
 161
 162 static void mapping_tree_init(struct mapping_tree *tree)
 163 {
 164         tree->rb_root.rb_node = NULL;
 165         spin_lock_init(&tree->lock);
 166 }
 167
 168 static void backref_cache_init(struct backref_cache *cache)
 169 {
 170         int i;
 171         cache->rb_root.rb_node = NULL;
 172         for (i = 0; i < BTRFS_MAX_LEVEL; i++)
 173                 INIT_LIST_HEAD(&cache->pending[i]);
 174         spin_lock_init(&cache->lock);
 175 }
 176
 177 static void backref_node_init(struct backref_node *node)
 178 {
 179         memset(node, 0, sizeof(*node));
 180         INIT_LIST_HEAD(&node->upper);
 181         INIT_LIST_HEAD(&node->lower);
 182         RB_CLEAR_NODE(&node->rb_node);
 183 }
 184
 185 static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
 186                                    struct rb_node *node)
 187 {
 188         struct rb_node **p = &root->rb_node;
 189         struct rb_node *parent = NULL;
 190         struct tree_entry *entry;
 191
 192         while (*p) {
 193                 parent = *p;
 194                 entry = rb_entry(parent, struct tree_entry, rb_node);
 195
 196                 if (bytenr < entry->bytenr)
 197                         p = &(*p)->rb_left;
 198                 else if (bytenr > entry->bytenr)
 199                         p = &(*p)->rb_right;
 200                 else
 201                         return parent;
 202         }
 203
 204         rb_link_node(node, parent, p);
 205         rb_insert_color(node, root);
 206         return NULL;
 207 }
 208
 209 static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
 210 {
 211         struct rb_node *n = root->rb_node;
 212         struct tree_entry *entry;
 213
 214         while (n) {
 215                 entry = rb_entry(n, struct tree_entry, rb_node);
 216
 217                 if (bytenr < entry->bytenr)
 218                         n = n->rb_left;
 219                 else if (bytenr > entry->bytenr)
 220                         n = n->rb_right;
 221                 else
 222                         return n;
 223         }
 224         return NULL;
 225 }
 226
 227 /*
 228  * walk up backref nodes until reach node presents tree root
 229  */
 230 static struct backref_node *walk_up_backref(struct backref_node *node,
 231                                             struct backref_edge *edges[],
 232                                             int *index)
 233 {
 234         struct backref_edge *edge;
 235         int idx = *index;
 236
 237         while (!list_empty(&node->upper)) {
 238                 edge = list_entry(node->upper.next,
 239                                   struct backref_edge, list[LOWER]);
 240                 edges[idx++] = edge;
 241                 node = edge->node[UPPER];
 242         }
 243         *index = idx;
 244         return node;
 245 }
 246
 247 /*
 248  * walk down backref nodes to find start of next reference path
 249  */
 250 static struct backref_node *walk_down_backref(struct backref_edge *edges[],
 251                                               int *index)
 252 {
 253         struct backref_edge *edge;
 254         struct backref_node *lower;
 255         int idx = *index;
 256
 257         while (idx > 0) {
 258                 edge = edges[idx - 1];
 259                 lower = edge->node[LOWER];
 260                 if (list_is_last(&edge->list[LOWER], &lower->upper)) {
 261                         idx--;
 262                         continue;
 263                 }
 264                 edge = list_entry(edge->list[LOWER].next,
 265                                   struct backref_edge, list[LOWER]);
 266                 edges[idx - 1] = edge;
 267                 *index = idx;
 268                 return edge->node[UPPER];
 269         }
 270         *index = 0;
 271         return NULL;
 272 }
 273
 274 static void drop_node_buffer(struct backref_node *node)
 275 {
 276         if (node->eb) {
 277                 if (node->locked) {
 278                         btrfs_tree_unlock(node->eb);
 279                         node->locked = 0;
 280                 }
 281                 free_extent_buffer(node->eb);
 282                 node->eb = NULL;
 283         }
 284 }
 285
 286 static void drop_backref_node(struct backref_cache *tree,
 287                               struct backref_node *node)
 288 {
 289         BUG_ON(!node->lowest);
 290         BUG_ON(!list_empty(&node->upper));
 291
 292         drop_node_buffer(node);
 293         list_del(&node->lower);
 294
 295         rb_erase(&node->rb_node, &tree->rb_root);
 296         kfree(node);
 297 }
 298
 299 /*
 300  * remove a backref node from the backref cache
 301  */
 302 static void remove_backref_node(struct backref_cache *cache,
 303                                 struct backref_node *node)
 304 {
 305         struct backref_node *upper;
 306         struct backref_edge *edge;
 307
 308         if (!node)
 309                 return;
 310
 311         BUG_ON(!node->lowest);
 312         while (!list_empty(&node->upper)) {
 313                 edge = list_entry(node->upper.next, struct backref_edge,
 314                                   list[LOWER]);
 315                 upper = edge->node[UPPER];
 316                 list_del(&edge->list[LOWER]);
 317                 list_del(&edge->list[UPPER]);
 318                 kfree(edge);
 319                 /*
 320                  * add the node to pending list if no other
 321                  * child block cached.
 322                  */
 323                 if (list_empty(&upper->lower)) {
 324                         list_add_tail(&upper->lower,
 325                                       &cache->pending[upper->level]);
 326                         upper->lowest = 1;
 327                 }
 328         }
 329         drop_backref_node(cache, node);
 330 }
 331
 332 /*
 333  * find reloc tree by address of tree root
 334  */
 335 static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
 336                                           u64 bytenr)
 337 {
 338         struct rb_node *rb_node;
 339         struct mapping_node *node;
 340         struct btrfs_root *root = NULL;
 341
 342         spin_lock(&rc->reloc_root_tree.lock);
 343         rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
 344         if (rb_node) {
 345                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 346                 root = (struct btrfs_root *)node->data;
 347         }
 348         spin_unlock(&rc->reloc_root_tree.lock);
 349         return root;
 350 }
 351
 352 static int is_cowonly_root(u64 root_objectid)
 353 {
 354         if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
 355             root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
 356             root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
 357             root_objectid == BTRFS_DEV_TREE_OBJECTID ||
 358             root_objectid == BTRFS_TREE_LOG_OBJECTID ||
 359             root_objectid == BTRFS_CSUM_TREE_OBJECTID)
 360                 return 1;
 361         return 0;
 362 }
 363
 364 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 365                                         u64 root_objectid)
 366 {
 367         struct btrfs_key key;
 368
 369         key.objectid = root_objectid;
 370         key.type = BTRFS_ROOT_ITEM_KEY;
 371         if (is_cowonly_root(root_objectid))
 372                 key.offset = 0;
 373         else
 374                 key.offset = (u64)-1;
 375
 376         return btrfs_read_fs_root_no_name(fs_info, &key);
 377 }
 378
 379 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 380 static noinline_for_stack
 381 struct btrfs_root *find_tree_root(struct reloc_control *rc,
 382                                   struct extent_buffer *leaf,
 383                                   struct btrfs_extent_ref_v0 *ref0)
 384 {
 385         struct btrfs_root *root;
 386         u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
 387         u64 generation = btrfs_ref_generation_v0(leaf, ref0);
 388
 389         BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
 390
 391         root = read_fs_root(rc->extent_root->fs_info, root_objectid);
 392         BUG_ON(IS_ERR(root));
 393
 394         if (root->ref_cows &&
 395             generation != btrfs_root_generation(&root->root_item))
 396                 return NULL;
 397
 398         return root;
 399 }
 400 #endif
 401
 402 static noinline_for_stack
 403 int find_inline_backref(struct extent_buffer *leaf, int slot,
 404                         unsigned long *ptr, unsigned long *end)
 405 {
 406         struct btrfs_extent_item *ei;
 407         struct btrfs_tree_block_info *bi;
 408         u32 item_size;
 409
 410         item_size = btrfs_item_size_nr(leaf, slot);
 411 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 412         if (item_size < sizeof(*ei)) {
 413                 WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
 414                 return 1;
 415         }
 416 #endif
 417         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 418         WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 419                   BTRFS_EXTENT_FLAG_TREE_BLOCK));
 420
 421         if (item_size <= sizeof(*ei) + sizeof(*bi)) {
 422                 WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
 423                 return 1;
 424         }
 425
 426         bi = (struct btrfs_tree_block_info *)(ei + 1);
 427         *ptr = (unsigned long)(bi + 1);
 428         *end = (unsigned long)ei + item_size;
 429         return 0;
 430 }
 431
 432 /*
 433  * build backref tree for a given tree block. root of the backref tree
 434  * corresponds the tree block, leaves of the backref tree correspond
 435  * roots of b-trees that reference the tree block.
 436  *
 437  * the basic idea of this function is check backrefs of a given block
 438  * to find upper level blocks that refernece the block, and then check
 439  * bakcrefs of these upper level blocks recursively. the recursion stop
 440  * when tree root is reached or backrefs for the block is cached.
 441  *
 442  * NOTE: if we find backrefs for a block are cached, we know backrefs
 443  * for all upper level blocks that directly/indirectly reference the
 444  * block are also cached.
 445  */
 446 static struct backref_node *build_backref_tree(struct reloc_control *rc,
 447                                                struct backref_cache *cache,
 448                                                struct btrfs_key *node_key,
 449                                                int level, u64 bytenr)
 450 {
 451         struct btrfs_path *path1;
 452         struct btrfs_path *path2;
 453         struct extent_buffer *eb;
 454         struct btrfs_root *root;
 455         struct backref_node *cur;
 456         struct backref_node *upper;
 457         struct backref_node *lower;
 458         struct backref_node *node = NULL;
 459         struct backref_node *exist = NULL;
 460         struct backref_edge *edge;
 461         struct rb_node *rb_node;
 462         struct btrfs_key key;
 463         unsigned long end;
 464         unsigned long ptr;
 465         LIST_HEAD(list);
 466         int ret;
 467         int err = 0;
 468
 469         path1 = btrfs_alloc_path();
 470         path2 = btrfs_alloc_path();
 471         if (!path1 || !path2) {
 472                 err = -ENOMEM;
 473                 goto out;
 474         }
 475
 476         node = kmalloc(sizeof(*node), GFP_NOFS);
 477         if (!node) {
 478                 err = -ENOMEM;
 479                 goto out;
 480         }
 481
 482         backref_node_init(node);
 483         node->bytenr = bytenr;
 484         node->owner = 0;
 485         node->level = level;
 486         node->lowest = 1;
 487         cur = node;
 488 again:
 489         end = 0;
 490         ptr = 0;
 491         key.objectid = cur->bytenr;
 492         key.type = BTRFS_EXTENT_ITEM_KEY;
 493         key.offset = (u64)-1;
 494
 495         path1->search_commit_root = 1;
 496         path1->skip_locking = 1;
 497         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
 498                                 0, 0);
 499         if (ret < 0) {
 500                 err = ret;
 501                 goto out;
 502         }
 503         BUG_ON(!ret || !path1->slots[0]);
 504
 505         path1->slots[0]--;
 506
 507         WARN_ON(cur->checked);
 508         if (!list_empty(&cur->upper)) {
 509                 /*
 510                  * the backref was added previously when processsing
 511                  * backref of type BTRFS_TREE_BLOCK_REF_KEY
 512                  */
 513                 BUG_ON(!list_is_singular(&cur->upper));
 514                 edge = list_entry(cur->upper.next, struct backref_edge,
 515                                   list[LOWER]);
 516                 BUG_ON(!list_empty(&edge->list[UPPER]));
 517                 exist = edge->node[UPPER];
 518                 /*
 519                  * add the upper level block to pending list if we need
 520                  * check its backrefs
 521                  */
 522                 if (!exist->checked)
 523                         list_add_tail(&edge->list[UPPER], &list);
 524         } else {
 525                 exist = NULL;
 526         }
 527
 528         while (1) {
 529                 cond_resched();
 530                 eb = path1->nodes[0];
 531
 532                 if (ptr >= end) {
 533                         if (path1->slots[0] >= btrfs_header_nritems(eb)) {
 534                                 ret = btrfs_next_leaf(rc->extent_root, path1);
 535                                 if (ret < 0) {
 536                                         err = ret;
 537                                         goto out;
 538                                 }
 539                                 if (ret > 0)
 540                                         break;
 541                                 eb = path1->nodes[0];
 542                         }
 543
 544                         btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
 545                         if (key.objectid != cur->bytenr) {
 546                                 WARN_ON(exist);
 547                                 break;
 548                         }
 549
 550                         if (key.type == BTRFS_EXTENT_ITEM_KEY) {
 551                                 ret = find_inline_backref(eb, path1->slots[0],
 552                                                           &ptr, &end);
 553                                 if (ret)
 554                                         goto next;
 555                         }
 556                 }
 557
 558                 if (ptr < end) {
 559                         /* update key for inline back ref */
 560                         struct btrfs_extent_inline_ref *iref;
 561                         iref = (struct btrfs_extent_inline_ref *)ptr;
 562                         key.type = btrfs_extent_inline_ref_type(eb, iref);
 563                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
 564                         WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
 565                                 key.type != BTRFS_SHARED_BLOCK_REF_KEY);
 566                 }
 567
 568                 if (exist &&
 569                     ((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
 570                       exist->owner == key.offset) ||
 571                      (key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
 572                       exist->bytenr == key.offset))) {
 573                         exist = NULL;
 574                         goto next;
 575                 }
 576
 577 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 578                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
 579                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
 580                         if (key.objectid == key.offset &&
 581                             key.type == BTRFS_EXTENT_REF_V0_KEY) {
 582                                 struct btrfs_extent_ref_v0 *ref0;
 583                                 ref0 = btrfs_item_ptr(eb, path1->slots[0],
 584                                                 struct btrfs_extent_ref_v0);
 585                                 root = find_tree_root(rc, eb, ref0);
 586                                 if (root)
 587                                         cur->root = root;
 588                                 else
 589                                         cur->old_root = 1;
 590                                 break;
 591                         }
 592 #else
 593                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 594                 if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
 595 #endif
 596                         if (key.objectid == key.offset) {
 597                                 /*
 598                                  * only root blocks of reloc trees use
 599                                  * backref of this type.
 600                                  */
 601                                 root = find_reloc_root(rc, cur->bytenr);
 602                                 BUG_ON(!root);
 603                                 cur->root = root;
 604                                 break;
 605                         }
 606
 607                         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 608                         if (!edge) {
 609                                 err = -ENOMEM;
 610                                 goto out;
 611                         }
 612                         rb_node = tree_search(&cache->rb_root, key.offset);
 613                         if (!rb_node) {
 614                                 upper = kmalloc(sizeof(*upper), GFP_NOFS);
 615                                 if (!upper) {
 616                                         kfree(edge);
 617                                         err = -ENOMEM;
 618                                         goto out;
 619                                 }
 620                                 backref_node_init(upper);
 621                                 upper->bytenr = key.offset;
 622                                 upper->owner = 0;
 623                                 upper->level = cur->level + 1;
 624                                 /*
 625                                  *  backrefs for the upper level block isn't
 626                                  *  cached, add the block to pending list
 627                                  */
 628                                 list_add_tail(&edge->list[UPPER], &list);
 629                         } else {
 630                                 upper = rb_entry(rb_node, struct backref_node,
 631                                                  rb_node);
 632                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 633                         }
 634                         list_add(&edge->list[LOWER], &cur->upper);
 635                         edge->node[UPPER] = upper;
 636                         edge->node[LOWER] = cur;
 637
 638                         goto next;
 639                 } else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
 640                         goto next;
 641                 }
 642
 643                 /* key.type == BTRFS_TREE_BLOCK_REF_KEY */
 644                 root = read_fs_root(rc->extent_root->fs_info, key.offset);
 645                 if (IS_ERR(root)) {
 646                         err = PTR_ERR(root);
 647                         goto out;
 648                 }
 649
 650                 if (btrfs_root_level(&root->root_item) == cur->level) {
 651                         /* tree root */
 652                         BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 653                                cur->bytenr);
 654                         cur->root = root;
 655                         break;
 656                 }
 657
 658                 level = cur->level + 1;
 659
 660                 /*
 661                  * searching the tree to find upper level blocks
 662                  * reference the block.
 663                  */
 664                 path2->search_commit_root = 1;
 665                 path2->skip_locking = 1;
 666                 path2->lowest_level = level;
 667                 ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
 668                 path2->lowest_level = 0;
 669                 if (ret < 0) {
 670                         err = ret;
 671                         goto out;
 672                 }
 673
 674                 eb = path2->nodes[level];
 675                 WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
 676                         cur->bytenr);
 677
 678                 lower = cur;
 679                 for (; level < BTRFS_MAX_LEVEL; level++) {
 680                         if (!path2->nodes[level]) {
 681                                 BUG_ON(btrfs_root_bytenr(&root->root_item) !=
 682                                        lower->bytenr);
 683                                 lower->root = root;
 684                                 break;
 685                         }
 686
 687                         edge = kzalloc(sizeof(*edge), GFP_NOFS);
 688                         if (!edge) {
 689                                 err = -ENOMEM;
 690                                 goto out;
 691                         }
 692
 693                         eb = path2->nodes[level];
 694                         rb_node = tree_search(&cache->rb_root, eb->start);
 695                         if (!rb_node) {
 696                                 upper = kmalloc(sizeof(*upper), GFP_NOFS);
 697                                 if (!upper) {
 698                                         kfree(edge);
 699                                         err = -ENOMEM;
 700                                         goto out;
 701                                 }
 702                                 backref_node_init(upper);
 703                                 upper->bytenr = eb->start;
 704                                 upper->owner = btrfs_header_owner(eb);
 705                                 upper->level = lower->level + 1;
 706
 707                                 /*
 708                                  * if we know the block isn't shared
 709                                  * we can void checking its backrefs.
 710                                  */
 711                                 if (btrfs_block_can_be_shared(root, eb))
 712                                         upper->checked = 0;
 713                                 else
 714                                         upper->checked = 1;
 715
 716                                 /*
 717                                  * add the block to pending list if we
 718                                  * need check its backrefs. only block
 719                                  * at 'cur->level + 1' is added to the
 720                                  * tail of pending list. this guarantees
 721                                  * we check backrefs from lower level
 722                                  * blocks to upper level blocks.
 723                                  */
 724                                 if (!upper->checked &&
 725                                     level == cur->level + 1) {
 726                                         list_add_tail(&edge->list[UPPER],
 727                                                       &list);
 728                                 } else
 729                                         INIT_LIST_HEAD(&edge->list[UPPER]);
 730                         } else {
 731                                 upper = rb_entry(rb_node, struct backref_node,
 732                                                  rb_node);
 733                                 BUG_ON(!upper->checked);
 734                                 INIT_LIST_HEAD(&edge->list[UPPER]);
 735                         }
 736                         list_add_tail(&edge->list[LOWER], &lower->upper);
 737                         edge->node[UPPER] = upper;
 738                         edge->node[LOWER] = lower;
 739
 740                         if (rb_node)
 741                                 break;
 742                         lower = upper;
 743                         upper = NULL;
 744                 }
 745                 btrfs_release_path(root, path2);
 746 next:
 747                 if (ptr < end) {
 748                         ptr += btrfs_extent_inline_ref_size(key.type);
 749                         if (ptr >= end) {
 750                                 WARN_ON(ptr > end);
 751                                 ptr = 0;
 752                                 end = 0;
 753                         }
 754                 }
 755                 if (ptr >= end)
 756                         path1->slots[0]++;
 757         }
 758         btrfs_release_path(rc->extent_root, path1);
 759
 760         cur->checked = 1;
 761         WARN_ON(exist);
 762
 763         /* the pending list isn't empty, take the first block to process */
 764         if (!list_empty(&list)) {
 765                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 766                 list_del_init(&edge->list[UPPER]);
 767                 cur = edge->node[UPPER];
 768                 goto again;
 769         }
 770
 771         /*
 772          * everything goes well, connect backref nodes and insert backref nodes
 773          * into the cache.
 774          */
 775         BUG_ON(!node->checked);
 776         rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
 777         BUG_ON(rb_node);
 778
 779         list_for_each_entry(edge, &node->upper, list[LOWER])
 780                 list_add_tail(&edge->list[UPPER], &list);
 781
 782         while (!list_empty(&list)) {
 783                 edge = list_entry(list.next, struct backref_edge, list[UPPER]);
 784                 list_del_init(&edge->list[UPPER]);
 785                 upper = edge->node[UPPER];
 786
 787                 if (!RB_EMPTY_NODE(&upper->rb_node)) {
 788                         if (upper->lowest) {
 789                                 list_del_init(&upper->lower);
 790                                 upper->lowest = 0;
 791                         }
 792
 793                         list_add_tail(&edge->list[UPPER], &upper->lower);
 794                         continue;
 795                 }
 796
 797                 BUG_ON(!upper->checked);
 798                 rb_node = tree_insert(&cache->rb_root, upper->bytenr,
 799                                       &upper->rb_node);
 800                 BUG_ON(rb_node);
 801
 802                 list_add_tail(&edge->list[UPPER], &upper->lower);
 803
 804                 list_for_each_entry(edge, &upper->upper, list[LOWER])
 805                         list_add_tail(&edge->list[UPPER], &list);
 806         }
 807 out:
 808         btrfs_free_path(path1);
 809         btrfs_free_path(path2);
 810         if (err) {
 811                 INIT_LIST_HEAD(&list);
 812                 upper = node;
 813                 while (upper) {
 814                         if (RB_EMPTY_NODE(&upper->rb_node)) {
 815                                 list_splice_tail(&upper->upper, &list);
 816                                 kfree(upper);
 817                         }
 818
 819                         if (list_empty(&list))
 820                                 break;
 821
 822                         edge = list_entry(list.next, struct backref_edge,
 823                                           list[LOWER]);
 824                         upper = edge->node[UPPER];
 825                         kfree(edge);
 826                 }
 827                 return ERR_PTR(err);
 828         }
 829         return node;
 830 }
 831
 832 /*
 833  * helper to add 'address of tree root -> reloc tree' mapping
 834  */
 835 static int __add_reloc_root(struct btrfs_root *root)
 836 {
 837         struct rb_node *rb_node;
 838         struct mapping_node *node;
 839         struct reloc_control *rc = root->fs_info->reloc_ctl;
 840
 841         node = kmalloc(sizeof(*node), GFP_NOFS);
 842         BUG_ON(!node);
 843
 844         node->bytenr = root->node->start;
 845         node->data = root;
 846
 847         spin_lock(&rc->reloc_root_tree.lock);
 848         rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
 849                               node->bytenr, &node->rb_node);
 850         spin_unlock(&rc->reloc_root_tree.lock);
 851         BUG_ON(rb_node);
 852
 853         list_add_tail(&root->root_list, &rc->reloc_roots);
 854         return 0;
 855 }
 856
 857 /*
 858  * helper to update/delete the 'address of tree root -> reloc tree'
 859  * mapping
 860  */
 861 static int __update_reloc_root(struct btrfs_root *root, int del)
 862 {
 863         struct rb_node *rb_node;
 864         struct mapping_node *node = NULL;
 865         struct reloc_control *rc = root->fs_info->reloc_ctl;
 866
 867         spin_lock(&rc->reloc_root_tree.lock);
 868         rb_node = tree_search(&rc->reloc_root_tree.rb_root,
 869                               root->commit_root->start);
 870         if (rb_node) {
 871                 node = rb_entry(rb_node, struct mapping_node, rb_node);
 872                 rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
 873         }
 874         spin_unlock(&rc->reloc_root_tree.lock);
 875
 876         BUG_ON((struct btrfs_root *)node->data != root);
 877
 878         if (!del) {
 879                 spin_lock(&rc->reloc_root_tree.lock);
 880                 node->bytenr = root->node->start;
 881                 rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
 882                                       node->bytenr, &node->rb_node);
 883                 spin_unlock(&rc->reloc_root_tree.lock);
 884                 BUG_ON(rb_node);
 885         } else {
 886                 list_del_init(&root->root_list);
 887                 kfree(node);
 888         }
 889         return 0;
 890 }
 891
 892 /*
 893  * create reloc tree for a given fs tree. reloc tree is just a
 894  * snapshot of the fs tree with special root objectid.
 895  */
 896 int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
 897                           struct btrfs_root *root)
 898 {
 899         struct btrfs_root *reloc_root;
 900         struct extent_buffer *eb;
 901         struct btrfs_root_item *root_item;
 902         struct btrfs_key root_key;
 903         int ret;
 904
 905         if (root->reloc_root) {
 906                 reloc_root = root->reloc_root;
 907                 reloc_root->last_trans = trans->transid;
 908                 return 0;
 909         }
 910
 911         if (!root->fs_info->reloc_ctl ||
 912             !root->fs_info->reloc_ctl->create_reloc_root ||
 913             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 914                 return 0;
 915
 916         root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
 917         BUG_ON(!root_item);
 918
 919         root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
 920         root_key.type = BTRFS_ROOT_ITEM_KEY;
 921         root_key.offset = root->root_key.objectid;
 922
 923         ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
 924                               BTRFS_TREE_RELOC_OBJECTID);
 925         BUG_ON(ret);
 926
 927         btrfs_set_root_last_snapshot(&root->root_item, trans->transid - 1);
 928         memcpy(root_item, &root->root_item, sizeof(*root_item));
 929         btrfs_set_root_refs(root_item, 1);
 930         btrfs_set_root_bytenr(root_item, eb->start);
 931         btrfs_set_root_level(root_item, btrfs_header_level(eb));
 932         btrfs_set_root_generation(root_item, trans->transid);
 933         memset(&root_item->drop_progress, 0, sizeof(struct btrfs_disk_key));
 934         root_item->drop_level = 0;
 935
 936         btrfs_tree_unlock(eb);
 937         free_extent_buffer(eb);
 938
 939         ret = btrfs_insert_root(trans, root->fs_info->tree_root,
 940                                 &root_key, root_item);
 941         BUG_ON(ret);
 942         kfree(root_item);
 943
 944         reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 945                                                  &root_key);
 946         BUG_ON(IS_ERR(reloc_root));
 947         reloc_root->last_trans = trans->transid;
 948
 949         __add_reloc_root(reloc_root);
 950         root->reloc_root = reloc_root;
 951         return 0;
 952 }
 953
 954 /*
 955  * update root item of reloc tree
 956  */
 957 int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
 958                             struct btrfs_root *root)
 959 {
 960         struct btrfs_root *reloc_root;
 961         struct btrfs_root_item *root_item;
 962         int del = 0;
 963         int ret;
 964
 965         if (!root->reloc_root)
 966                 return 0;
 967
 968         reloc_root = root->reloc_root;
 969         root_item = &reloc_root->root_item;
 970
 971         if (btrfs_root_refs(root_item) == 0) {
 972                 root->reloc_root = NULL;
 973                 del = 1;
 974         }
 975
 976         __update_reloc_root(reloc_root, del);
 977
 978         if (reloc_root->commit_root != reloc_root->node) {
 979                 btrfs_set_root_node(root_item, reloc_root->node);
 980                 free_extent_buffer(reloc_root->commit_root);
 981                 reloc_root->commit_root = btrfs_root_node(reloc_root);
 982         }
 983
 984         ret = btrfs_update_root(trans, root->fs_info->tree_root,
 985                                 &reloc_root->root_key, root_item);
 986         BUG_ON(ret);
 987         return 0;
 988 }
 989
 990 /*
 991  * helper to find first cached inode with inode number >= objectid
 992  * in a subvolume
 993  */
 994 static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
 995 {
 996         struct rb_node *node;
 997         struct rb_node *prev;
 998         struct btrfs_inode *entry;
 999         struct inode *inode;
1000
1001         spin_lock(&root->inode_lock);
1002 again:
1003         node = root->inode_tree.rb_node;
1004         prev = NULL;
1005         while (node) {
1006                 prev = node;
1007                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1008
1009                 if (objectid < entry->vfs_inode.i_ino)
1010                         node = node->rb_left;
1011                 else if (objectid > entry->vfs_inode.i_ino)
1012                         node = node->rb_right;
1013                 else
1014                         break;
1015         }
1016         if (!node) {
1017                 while (prev) {
1018                         entry = rb_entry(prev, struct btrfs_inode, rb_node);
1019                         if (objectid <= entry->vfs_inode.i_ino) {
1020                                 node = prev;
1021                                 break;
1022                         }
1023                         prev = rb_next(prev);
1024                 }
1025         }
1026         while (node) {
1027                 entry = rb_entry(node, struct btrfs_inode, rb_node);
1028                 inode = igrab(&entry->vfs_inode);
1029                 if (inode) {
1030                         spin_unlock(&root->inode_lock);
1031                         return inode;
1032                 }
1033
1034                 objectid = entry->vfs_inode.i_ino + 1;
1035                 if (cond_resched_lock(&root->inode_lock))
1036                         goto again;
1037
1038                 node = rb_next(node);
1039         }
1040         spin_unlock(&root->inode_lock);
1041         return NULL;
1042 }
1043
1044 static int in_block_group(u64 bytenr,
1045                           struct btrfs_block_group_cache *block_group)
1046 {
1047         if (bytenr >= block_group->key.objectid &&
1048             bytenr < block_group->key.objectid + block_group->key.offset)
1049                 return 1;
1050         return 0;
1051 }
1052
1053 /*
1054  * get new location of data
1055  */
1056 static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
1057                             u64 bytenr, u64 num_bytes)
1058 {
1059         struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
1060         struct btrfs_path *path;
1061         struct btrfs_file_extent_item *fi;
1062         struct extent_buffer *leaf;
1063         int ret;
1064
1065         path = btrfs_alloc_path();
1066         if (!path)
1067                 return -ENOMEM;
1068
1069         bytenr -= BTRFS_I(reloc_inode)->index_cnt;
1070         ret = btrfs_lookup_file_extent(NULL, root, path, reloc_inode->i_ino,
1071                                        bytenr, 0);
1072         if (ret < 0)
1073                 goto out;
1074         if (ret > 0) {
1075                 ret = -ENOENT;
1076                 goto out;
1077         }
1078
1079         leaf = path->nodes[0];
1080         fi = btrfs_item_ptr(leaf, path->slots[0],
1081                             struct btrfs_file_extent_item);
1082
1083         BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
1084                btrfs_file_extent_compression(leaf, fi) ||
1085                btrfs_file_extent_encryption(leaf, fi) ||
1086                btrfs_file_extent_other_encoding(leaf, fi));
1087
1088         if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
1089                 ret = 1;
1090                 goto out;
1091         }
1092
1093         if (new_bytenr)
1094                 *new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1095         ret = 0;
1096 out:
1097         btrfs_free_path(path);
1098         return ret;
1099 }
1100
1101 /*
1102  * update file extent items in the tree leaf to point to
1103  * the new locations.
1104  */
1105 static int replace_file_extents(struct btrfs_trans_handle *trans,
1106                                 struct reloc_control *rc,
1107                                 struct btrfs_root *root,
1108                                 struct extent_buffer *leaf,
1109                                 struct list_head *inode_list)
1110 {
1111         struct btrfs_key key;
1112         struct btrfs_file_extent_item *fi;
1113         struct inode *inode = NULL;
1114         struct inodevec *ivec = NULL;
1115         u64 parent;
1116         u64 bytenr;
1117         u64 new_bytenr;
1118         u64 num_bytes;
1119         u64 end;
1120         u32 nritems;
1121         u32 i;
1122         int ret;
1123         int first = 1;
1124         int dirty = 0;
1125
1126         if (rc->stage != UPDATE_DATA_PTRS)
1127                 return 0;
1128
1129         /* reloc trees always use full backref */
1130         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1131                 parent = leaf->start;
1132         else
1133                 parent = 0;
1134
1135         nritems = btrfs_header_nritems(leaf);
1136         for (i = 0; i < nritems; i++) {
1137                 cond_resched();
1138                 btrfs_item_key_to_cpu(leaf, &key, i);
1139                 if (key.type != BTRFS_EXTENT_DATA_KEY)
1140                         continue;
1141                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
1142                 if (btrfs_file_extent_type(leaf, fi) ==
1143                     BTRFS_FILE_EXTENT_INLINE)
1144                         continue;
1145                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1146                 num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1147                 if (bytenr == 0)
1148                         continue;
1149                 if (!in_block_group(bytenr, rc->block_group))
1150                         continue;
1151
1152                 /*
1153                  * if we are modifying block in fs tree, wait for readpage
1154                  * to complete and drop the extent cache
1155                  */
1156                 if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
1157                         if (!ivec || ivec->nr == INODEVEC_SIZE) {
1158                                 ivec = kmalloc(sizeof(*ivec), GFP_NOFS);
1159                                 BUG_ON(!ivec);
1160                                 ivec->nr = 0;
1161                                 list_add_tail(&ivec->list, inode_list);
1162                         }
1163                         if (first) {
1164                                 inode = find_next_inode(root, key.objectid);
1165                                 if (inode)
1166                                         ivec->inode[ivec->nr++] = inode;
1167                                 first = 0;
1168                         } else if (inode && inode->i_ino < key.objectid) {
1169                                 inode = find_next_inode(root, key.objectid);
1170                                 if (inode)
1171                                         ivec->inode[ivec->nr++] = inode;
1172                         }
1173                         if (inode && inode->i_ino == key.objectid) {
1174                                 end = key.offset +
1175                                       btrfs_file_extent_num_bytes(leaf, fi);
1176                                 WARN_ON(!IS_ALIGNED(key.offset,
1177                                                     root->sectorsize));
1178                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1179                                 end--;
1180                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
1181                                                       key.offset, end,
1182                                                       GFP_NOFS);
1183                                 if (!ret)
1184                                         continue;
1185
1186                                 btrfs_drop_extent_cache(inode, key.offset, end,
1187                                                         1);
1188                                 unlock_extent(&BTRFS_I(inode)->io_tree,
1189                                               key.offset, end, GFP_NOFS);
1190                         }
1191                 }
1192
1193                 ret = get_new_location(rc->data_inode, &new_bytenr,
1194                                        bytenr, num_bytes);
1195                 if (ret > 0)
1196                         continue;
1197                 BUG_ON(ret < 0);
1198
1199                 btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
1200                 dirty = 1;
1201
1202                 key.offset -= btrfs_file_extent_offset(leaf, fi);
1203                 ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
1204                                            num_bytes, parent,
1205                                            btrfs_header_owner(leaf),
1206                                            key.objectid, key.offset);
1207                 BUG_ON(ret);
1208
1209                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1210                                         parent, btrfs_header_owner(leaf),
1211                                         key.objectid, key.offset);
1212                 BUG_ON(ret);
1213         }
1214         if (dirty)
1215                 btrfs_mark_buffer_dirty(leaf);
1216         return 0;
1217 }
1218
1219 static noinline_for_stack
1220 int memcmp_node_keys(struct extent_buffer *eb, int slot,
1221                      struct btrfs_path *path, int level)
1222 {
1223         struct btrfs_disk_key key1;
1224         struct btrfs_disk_key key2;
1225         btrfs_node_key(eb, &key1, slot);
1226         btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
1227         return memcmp(&key1, &key2, sizeof(key1));
1228 }
1229
1230 /*
1231  * try to replace tree blocks in fs tree with the new blocks
1232  * in reloc tree. tree blocks haven't been modified since the
1233  * reloc tree was create can be replaced.
1234  *
1235  * if a block was replaced, level of the block + 1 is returned.
1236  * if no block got replaced, 0 is returned. if there are other
1237  * errors, a negative error number is returned.
1238  */
1239 static int replace_path(struct btrfs_trans_handle *trans,
1240                         struct btrfs_root *dest, struct btrfs_root *src,
1241                         struct btrfs_path *path, struct btrfs_key *next_key,
1242                         struct extent_buffer **leaf,
1243                         int lowest_level, int max_level)
1244 {
1245         struct extent_buffer *eb;
1246         struct extent_buffer *parent;
1247         struct btrfs_key key;
1248         u64 old_bytenr;
1249         u64 new_bytenr;
1250         u64 old_ptr_gen;
1251         u64 new_ptr_gen;
1252         u64 last_snapshot;
1253         u32 blocksize;
1254         int level;
1255         int ret;
1256         int slot;
1257
1258         BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
1259         BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
1260         BUG_ON(lowest_level > 1 && leaf);
1261
1262         last_snapshot = btrfs_root_last_snapshot(&src->root_item);
1263
1264         slot = path->slots[lowest_level];
1265         btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
1266
1267         eb = btrfs_lock_root_node(dest);
1268         btrfs_set_lock_blocking(eb);
1269         level = btrfs_header_level(eb);
1270
1271         if (level < lowest_level) {
1272                 btrfs_tree_unlock(eb);
1273                 free_extent_buffer(eb);
1274                 return 0;
1275         }
1276
1277         ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
1278         BUG_ON(ret);
1279         btrfs_set_lock_blocking(eb);
1280
1281         if (next_key) {
1282                 next_key->objectid = (u64)-1;
1283                 next_key->type = (u8)-1;
1284                 next_key->offset = (u64)-1;
1285         }
1286
1287         parent = eb;
1288         while (1) {
1289                 level = btrfs_header_level(parent);
1290                 BUG_ON(level < lowest_level);
1291
1292                 ret = btrfs_bin_search(parent, &key, level, &slot);
1293                 if (ret && slot > 0)
1294                         slot--;
1295
1296                 if (next_key && slot + 1 < btrfs_header_nritems(parent))
1297                         btrfs_node_key_to_cpu(parent, next_key, slot + 1);
1298
1299                 old_bytenr = btrfs_node_blockptr(parent, slot);
1300                 blocksize = btrfs_level_size(dest, level - 1);
1301                 old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
1302
1303                 if (level <= max_level) {
1304                         eb = path->nodes[level];
1305                         new_bytenr = btrfs_node_blockptr(eb,
1306                                                         path->slots[level]);
1307                         new_ptr_gen = btrfs_node_ptr_generation(eb,
1308                                                         path->slots[level]);
1309                 } else {
1310                         new_bytenr = 0;
1311                         new_ptr_gen = 0;
1312                 }
1313
1314                 if (new_bytenr > 0 && new_bytenr == old_bytenr) {
1315                         WARN_ON(1);
1316                         ret = level;
1317                         break;
1318                 }
1319
1320                 if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
1321                     memcmp_node_keys(parent, slot, path, level)) {
1322                         if (level <= lowest_level && !leaf) {
1323                                 ret = 0;
1324                                 break;
1325                         }
1326
1327                         eb = read_tree_block(dest, old_bytenr, blocksize,
1328                                              old_ptr_gen);
1329                         btrfs_tree_lock(eb);
1330                         ret = btrfs_cow_block(trans, dest, eb, parent,
1331                                               slot, &eb);
1332                         BUG_ON(ret);
1333                         btrfs_set_lock_blocking(eb);
1334
1335                         if (level <= lowest_level) {
1336                                 *leaf = eb;
1337                                 ret = 0;
1338                                 break;
1339                         }
1340
1341                         btrfs_tree_unlock(parent);
1342                         free_extent_buffer(parent);
1343
1344                         parent = eb;
1345                         continue;
1346                 }
1347
1348                 btrfs_node_key_to_cpu(path->nodes[level], &key,
1349                                       path->slots[level]);
1350                 btrfs_release_path(src, path);
1351
1352                 path->lowest_level = level;
1353                 ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
1354                 path->lowest_level = 0;
1355                 BUG_ON(ret);
1356
1357                 /*
1358                  * swap blocks in fs tree and reloc tree.
1359                  */
1360                 btrfs_set_node_blockptr(parent, slot, new_bytenr);
1361                 btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
1362                 btrfs_mark_buffer_dirty(parent);
1363
1364                 btrfs_set_node_blockptr(path->nodes[level],
1365                                         path->slots[level], old_bytenr);
1366                 btrfs_set_node_ptr_generation(path->nodes[level],
1367                                               path->slots[level], old_ptr_gen);
1368                 btrfs_mark_buffer_dirty(path->nodes[level]);
1369
1370                 ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
1371                                         path->nodes[level]->start,
1372                                         src->root_key.objectid, level - 1, 0);
1373                 BUG_ON(ret);
1374                 ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
1375                                         0, dest->root_key.objectid, level - 1,
1376                                         0);
1377                 BUG_ON(ret);
1378
1379                 ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
1380                                         path->nodes[level]->start,
1381                                         src->root_key.objectid, level - 1, 0);
1382                 BUG_ON(ret);
1383
1384                 ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
1385                                         0, dest->root_key.objectid, level - 1,
1386                                         0);
1387                 BUG_ON(ret);
1388
1389                 btrfs_unlock_up_safe(path, 0);
1390
1391                 ret = level;
1392                 break;
1393         }
1394         btrfs_tree_unlock(parent);
1395         free_extent_buffer(parent);
1396         return ret;
1397 }
1398
1399 /*
1400  * helper to find next relocated block in reloc tree
1401  */
1402 static noinline_for_stack
1403 int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1404                        int *level)
1405 {
1406         struct extent_buffer *eb;
1407         int i;
1408         u64 last_snapshot;
1409         u32 nritems;
1410
1411         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1412
1413         for (i = 0; i < *level; i++) {
1414                 free_extent_buffer(path->nodes[i]);
1415                 path->nodes[i] = NULL;
1416         }
1417
1418         for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
1419                 eb = path->nodes[i];
1420                 nritems = btrfs_header_nritems(eb);
1421                 while (path->slots[i] + 1 < nritems) {
1422                         path->slots[i]++;
1423                         if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
1424                             last_snapshot)
1425                                 continue;
1426
1427                         *level = i;
1428                         return 0;
1429                 }
1430                 free_extent_buffer(path->nodes[i]);
1431                 path->nodes[i] = NULL;
1432         }
1433         return 1;
1434 }
1435
1436 /*
1437  * walk down reloc tree to find relocated block of lowest level
1438  */
1439 static noinline_for_stack
1440 int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
1441                          int *level)
1442 {
1443         struct extent_buffer *eb = NULL;
1444         int i;
1445         u64 bytenr;
1446         u64 ptr_gen = 0;
1447         u64 last_snapshot;
1448         u32 blocksize;
1449         u32 nritems;
1450
1451         last_snapshot = btrfs_root_last_snapshot(&root->root_item);
1452
1453         for (i = *level; i > 0; i--) {
1454                 eb = path->nodes[i];
1455                 nritems = btrfs_header_nritems(eb);
1456                 while (path->slots[i] < nritems) {
1457                         ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
1458                         if (ptr_gen > last_snapshot)
1459                                 break;
1460                         path->slots[i]++;
1461                 }
1462                 if (path->slots[i] >= nritems) {
1463                         if (i == *level)
1464                                 break;
1465                         *level = i + 1;
1466                         return 0;
1467                 }
1468                 if (i == 1) {
1469                         *level = i;
1470                         return 0;
1471                 }
1472
1473                 bytenr = btrfs_node_blockptr(eb, path->slots[i]);
1474                 blocksize = btrfs_level_size(root, i - 1);
1475                 eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
1476                 BUG_ON(btrfs_header_level(eb) != i - 1);
1477                 path->nodes[i - 1] = eb;
1478                 path->slots[i - 1] = 0;
1479         }
1480         return 1;
1481 }
1482
1483 /*
1484  * invalidate extent cache for file extents whose key in range of
1485  * [min_key, max_key)
1486  */
1487 static int invalidate_extent_cache(struct btrfs_root *root,
1488                                    struct btrfs_key *min_key,
1489                                    struct btrfs_key *max_key)
1490 {
1491         struct inode *inode = NULL;
1492         u64 objectid;
1493         u64 start, end;
1494
1495         objectid = min_key->objectid;
1496         while (1) {
1497                 cond_resched();
1498                 iput(inode);
1499
1500                 if (objectid > max_key->objectid)
1501                         break;
1502
1503                 inode = find_next_inode(root, objectid);
1504                 if (!inode)
1505                         break;
1506
1507                 if (inode->i_ino > max_key->objectid) {
1508                         iput(inode);
1509                         break;
1510                 }
1511
1512                 objectid = inode->i_ino + 1;
1513                 if (!S_ISREG(inode->i_mode))
1514                         continue;
1515
1516                 if (unlikely(min_key->objectid == inode->i_ino)) {
1517                         if (min_key->type > BTRFS_EXTENT_DATA_KEY)
1518                                 continue;
1519                         if (min_key->type < BTRFS_EXTENT_DATA_KEY)
1520                                 start = 0;
1521                         else {
1522                                 start = min_key->offset;
1523                                 WARN_ON(!IS_ALIGNED(start, root->sectorsize));
1524                         }
1525                 } else {
1526                         start = 0;
1527                 }
1528
1529                 if (unlikely(max_key->objectid == inode->i_ino)) {
1530                         if (max_key->type < BTRFS_EXTENT_DATA_KEY)
1531                                 continue;
1532                         if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
1533                                 end = (u64)-1;
1534                         } else {
1535                                 if (max_key->offset == 0)
1536                                         continue;
1537                                 end = max_key->offset;
1538                                 WARN_ON(!IS_ALIGNED(end, root->sectorsize));
1539                                 end--;
1540                         }
1541                 } else {
1542                         end = (u64)-1;
1543                 }
1544
1545                 /* the lock_extent waits for readpage to complete */
1546                 lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1547                 btrfs_drop_extent_cache(inode, start, end, 1);
1548                 unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
1549         }
1550         return 0;
1551 }
1552
1553 static int find_next_key(struct btrfs_path *path, int level,
1554                          struct btrfs_key *key)
1555
1556 {
1557         while (level < BTRFS_MAX_LEVEL) {
1558                 if (!path->nodes[level])
1559                         break;
1560                 if (path->slots[level] + 1 <
1561                     btrfs_header_nritems(path->nodes[level])) {
1562                         btrfs_node_key_to_cpu(path->nodes[level], key,
1563                                               path->slots[level] + 1);
1564                         return 0;
1565                 }
1566                 level++;
1567         }
1568         return 1;
1569 }
1570
1571 /*
1572  * merge the relocated tree blocks in reloc tree with corresponding
1573  * fs tree.
1574  */
1575 static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
1576                                                struct btrfs_root *root)
1577 {
1578         LIST_HEAD(inode_list);
1579         struct btrfs_key key;
1580         struct btrfs_key next_key;
1581         struct btrfs_trans_handle *trans;
1582         struct btrfs_root *reloc_root;
1583         struct btrfs_root_item *root_item;
1584         struct btrfs_path *path;
1585         struct extent_buffer *leaf = NULL;
1586         unsigned long nr;
1587         int level;
1588         int max_level;
1589         int replaced = 0;
1590         int ret;
1591         int err = 0;
1592
1593         path = btrfs_alloc_path();
1594         if (!path)
1595                 return -ENOMEM;
1596
1597         reloc_root = root->reloc_root;
1598         root_item = &reloc_root->root_item;
1599
1600         if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
1601                 level = btrfs_root_level(root_item);
1602                 extent_buffer_get(reloc_root->node);
1603                 path->nodes[level] = reloc_root->node;
1604                 path->slots[level] = 0;
1605         } else {
1606                 btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
1607
1608                 level = root_item->drop_level;
1609                 BUG_ON(level == 0);
1610                 path->lowest_level = level;
1611                 ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
1612                 if (ret < 0) {
1613                         btrfs_free_path(path);
1614                         return ret;
1615                 }
1616
1617                 btrfs_node_key_to_cpu(path->nodes[level], &next_key,
1618                                       path->slots[level]);
1619                 WARN_ON(memcmp(&key, &next_key, sizeof(key)));
1620
1621                 btrfs_unlock_up_safe(path, 0);
1622         }
1623
1624         if (level == 0 && rc->stage == UPDATE_DATA_PTRS) {
1625                 trans = btrfs_start_transaction(root, 1);
1626
1627                 leaf = path->nodes[0];
1628                 btrfs_item_key_to_cpu(leaf, &key, 0);
1629                 btrfs_release_path(reloc_root, path);
1630
1631                 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
1632                 if (ret < 0) {
1633                         err = ret;
1634                         goto out;
1635                 }
1636
1637                 leaf = path->nodes[0];
1638                 btrfs_unlock_up_safe(path, 1);
1639                 ret = replace_file_extents(trans, rc, root, leaf,
1640                                            &inode_list);
1641                 if (ret < 0)
1642                         err = ret;
1643                 goto out;
1644         }
1645
1646         memset(&next_key, 0, sizeof(next_key));
1647
1648         while (1) {
1649                 leaf = NULL;
1650                 replaced = 0;
1651                 trans = btrfs_start_transaction(root, 1);
1652                 max_level = level;
1653
1654                 ret = walk_down_reloc_tree(reloc_root, path, &level);
1655                 if (ret < 0) {
1656                         err = ret;
1657                         goto out;
1658                 }
1659                 if (ret > 0)
1660                         break;
1661
1662                 if (!find_next_key(path, level, &key) &&
1663                     btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
1664                         ret = 0;
1665                 } else if (level == 1 && rc->stage == UPDATE_DATA_PTRS) {
1666                         ret = replace_path(trans, root, reloc_root,
1667                                            path, &next_key, &leaf,
1668                                            level, max_level);
1669                 } else {
1670                         ret = replace_path(trans, root, reloc_root,
1671                                            path, &next_key, NULL,
1672                                            level, max_level);
1673                 }
1674                 if (ret < 0) {
1675                         err = ret;
1676                         goto out;
1677                 }
1678
1679                 if (ret > 0) {
1680                         level = ret;
1681                         btrfs_node_key_to_cpu(path->nodes[level], &key,
1682                                               path->slots[level]);
1683                         replaced = 1;
1684                 } else if (leaf) {
1685                         /*
1686                          * no block got replaced, try replacing file extents
1687                          */
1688                         btrfs_item_key_to_cpu(leaf, &key, 0);
1689                         ret = replace_file_extents(trans, rc, root, leaf,
1690                                                    &inode_list);
1691                         btrfs_tree_unlock(leaf);
1692                         free_extent_buffer(leaf);
1693                         BUG_ON(ret < 0);
1694                 }
1695
1696                 ret = walk_up_reloc_tree(reloc_root, path, &level);
1697                 if (ret > 0)
1698                         break;
1699
1700                 BUG_ON(level == 0);
1701                 /*
1702                  * save the merging progress in the drop_progress.
1703                  * this is OK since root refs == 1 in this case.
1704                  */
1705                 btrfs_node_key(path->nodes[level], &root_item->drop_progress,
1706                                path->slots[level]);
1707                 root_item->drop_level = level;
1708
1709                 nr = trans->blocks_used;
1710                 btrfs_end_transaction(trans, root);
1711
1712                 btrfs_btree_balance_dirty(root, nr);
1713
1714                 if (replaced && rc->stage == UPDATE_DATA_PTRS)
1715                         invalidate_extent_cache(root, &key, &next_key);
1716         }
1717
1718         /*
1719          * handle the case only one block in the fs tree need to be
1720          * relocated and the block is tree root.
1721          */
1722         leaf = btrfs_lock_root_node(root);
1723         ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
1724         btrfs_tree_unlock(leaf);
1725         free_extent_buffer(leaf);
1726         if (ret < 0)
1727                 err = ret;
1728 out:
1729         btrfs_free_path(path);
1730
1731         if (err == 0) {
1732                 memset(&root_item->drop_progress, 0,
1733                        sizeof(root_item->drop_progress));
1734                 root_item->drop_level = 0;
1735                 btrfs_set_root_refs(root_item, 0);
1736         }
1737
1738         nr = trans->blocks_used;
1739         btrfs_end_transaction(trans, root);
1740
1741         btrfs_btree_balance_dirty(root, nr);
1742
1743         /*
1744          * put inodes while we aren't holding the tree locks
1745          */
1746         while (!list_empty(&inode_list)) {
1747                 struct inodevec *ivec;
1748                 ivec = list_entry(inode_list.next, struct inodevec, list);
1749                 list_del(&ivec->list);
1750                 while (ivec->nr > 0) {
1751                         ivec->nr--;
1752                         iput(ivec->inode[ivec->nr]);
1753                 }
1754                 kfree(ivec);
1755         }
1756
1757         if (replaced && rc->stage == UPDATE_DATA_PTRS)
1758                 invalidate_extent_cache(root, &key, &next_key);
1759
1760         return err;
1761 }
1762
1763 /*
1764  * callback for the work threads.
1765  * this function merges reloc tree with corresponding fs tree,
1766  * and then drops the reloc tree.
1767  */
1768 static void merge_func(struct btrfs_work *work)
1769 {
1770         struct btrfs_trans_handle *trans;
1771         struct btrfs_root *root;
1772         struct btrfs_root *reloc_root;
1773         struct async_merge *async;
1774
1775         async = container_of(work, struct async_merge, work);
1776         reloc_root = async->root;
1777
1778         if (btrfs_root_refs(&reloc_root->root_item) > 0) {
1779                 root = read_fs_root(reloc_root->fs_info,
1780                                     reloc_root->root_key.offset);
1781                 BUG_ON(IS_ERR(root));
1782                 BUG_ON(root->reloc_root != reloc_root);
1783
1784                 merge_reloc_root(async->rc, root);
1785
1786                 trans = btrfs_start_transaction(root, 1);
1787                 btrfs_update_reloc_root(trans, root);
1788                 btrfs_end_transaction(trans, root);
1789         }
1790
1791         btrfs_drop_snapshot(reloc_root, 0);
1792
1793         if (atomic_dec_and_test(async->num_pending))
1794                 complete(async->done);
1795
1796         kfree(async);
1797 }
1798
1799 static int merge_reloc_roots(struct reloc_control *rc)
1800 {
1801         struct async_merge *async;
1802         struct btrfs_root *root;
1803         struct completion done;
1804         atomic_t num_pending;
1805
1806         init_completion(&done);
1807         atomic_set(&num_pending, 1);
1808
1809         while (!list_empty(&rc->reloc_roots)) {
1810                 root = list_entry(rc->reloc_roots.next,
1811                                   struct btrfs_root, root_list);
1812                 list_del_init(&root->root_list);
1813
1814                 async = kmalloc(sizeof(*async), GFP_NOFS);
1815                 BUG_ON(!async);
1816                 async->work.func = merge_func;
1817                 async->work.flags = 0;
1818                 async->rc = rc;
1819                 async->root = root;
1820                 async->done = &done;
1821                 async->num_pending = &num_pending;
1822                 atomic_inc(&num_pending);
1823                 btrfs_queue_worker(&rc->workers, &async->work);
1824         }
1825
1826         if (!atomic_dec_and_test(&num_pending))
1827                 wait_for_completion(&done);
1828
1829         BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
1830         return 0;
1831 }
1832
1833 static void free_block_list(struct rb_root *blocks)
1834 {
1835         struct tree_block *block;
1836         struct rb_node *rb_node;
1837         while ((rb_node = rb_first(blocks))) {
1838                 block = rb_entry(rb_node, struct tree_block, rb_node);
1839                 rb_erase(rb_node, blocks);
1840                 kfree(block);
1841         }
1842 }
1843
1844 static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
1845                                       struct btrfs_root *reloc_root)
1846 {
1847         struct btrfs_root *root;
1848
1849         if (reloc_root->last_trans == trans->transid)
1850                 return 0;
1851
1852         root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
1853         BUG_ON(IS_ERR(root));
1854         BUG_ON(root->reloc_root != reloc_root);
1855
1856         return btrfs_record_root_in_trans(trans, root);
1857 }
1858
1859 /*
1860  * select one tree from trees that references the block.
1861  * for blocks in refernce counted trees, we preper reloc tree.
1862  * if no reloc tree found and reloc_only is true, NULL is returned.
1863  */
1864 static struct btrfs_root *__select_one_root(struct btrfs_trans_handle *trans,
1865                                             struct backref_node *node,
1866                                             struct backref_edge *edges[],
1867                                             int *nr, int reloc_only)
1868 {
1869         struct backref_node *next;
1870         struct btrfs_root *root;
1871         int index;
1872         int loop = 0;
1873 again:
1874         index = 0;
1875         next = node;
1876         while (1) {
1877                 cond_resched();
1878                 next = walk_up_backref(next, edges, &index);
1879                 root = next->root;
1880                 if (!root) {
1881                         BUG_ON(!node->old_root);
1882                         goto skip;
1883                 }
1884
1885                 /* no other choice for non-refernce counted tree */
1886                 if (!root->ref_cows) {
1887                         BUG_ON(reloc_only);
1888                         break;
1889                 }
1890
1891                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
1892                         record_reloc_root_in_trans(trans, root);
1893                         break;
1894                 }
1895
1896                 if (loop) {
1897                         btrfs_record_root_in_trans(trans, root);
1898                         break;
1899                 }
1900
1901                 if (reloc_only || next != node) {
1902                         if (!root->reloc_root)
1903                                 btrfs_record_root_in_trans(trans, root);
1904                         root = root->reloc_root;
1905                         /*
1906                          * if the reloc tree was created in current
1907                          * transation, there is no node in backref tree
1908                          * corresponds to the root of the reloc tree.
1909                          */
1910                         if (btrfs_root_last_snapshot(&root->root_item) ==
1911                             trans->transid - 1)
1912                                 break;
1913                 }
1914 skip:
1915                 root = NULL;
1916                 next = walk_down_backref(edges, &index);
1917                 if (!next || next->level <= node->level)
1918                         break;
1919         }
1920
1921         if (!root && !loop && !reloc_only) {
1922                 loop = 1;
1923                 goto again;
1924         }
1925
1926         if (root)
1927                 *nr = index;
1928         else
1929                 *nr = 0;
1930
1931         return root;
1932 }
1933
1934 static noinline_for_stack
1935 struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
1936                                    struct backref_node *node)
1937 {
1938         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
1939         int nr;
1940         return __select_one_root(trans, node, edges, &nr, 0);
1941 }
1942
1943 static noinline_for_stack
1944 struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
1945                                      struct backref_node *node,
1946                                      struct backref_edge *edges[], int *nr)
1947 {
1948         return __select_one_root(trans, node, edges, nr, 1);
1949 }
1950
1951 static void grab_path_buffers(struct btrfs_path *path,
1952                               struct backref_node *node,
1953                               struct backref_edge *edges[], int nr)
1954 {
1955         int i = 0;
1956         while (1) {
1957                 drop_node_buffer(node);
1958                 node->eb = path->nodes[node->level];
1959                 BUG_ON(!node->eb);
1960                 if (path->locks[node->level])
1961                         node->locked = 1;
1962                 path->nodes[node->level] = NULL;
1963                 path->locks[node->level] = 0;
1964
1965                 if (i >= nr)
1966                         break;
1967
1968                 edges[i]->blockptr = node->eb->start;
1969                 node = edges[i]->node[UPPER];
1970                 i++;
1971         }
1972 }
1973
1974 /*
1975  * relocate a block tree, and then update pointers in upper level
1976  * blocks that reference the block to point to the new location.
1977  *
1978  * if called by link_to_upper, the block has already been relocated.
1979  * in that case this function just updates pointers.
1980  */
1981 static int do_relocation(struct btrfs_trans_handle *trans,
1982                          struct backref_node *node,
1983                          struct btrfs_key *key,
1984                          struct btrfs_path *path, int lowest)
1985 {
1986         struct backref_node *upper;
1987         struct backref_edge *edge;
1988         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
1989         struct btrfs_root *root;
1990         struct extent_buffer *eb;
1991         u32 blocksize;
1992         u64 bytenr;
1993         u64 generation;
1994         int nr;
1995         int slot;
1996         int ret;
1997         int err = 0;
1998
1999         BUG_ON(lowest && node->eb);
2000
2001         path->lowest_level = node->level + 1;
2002         list_for_each_entry(edge, &node->upper, list[LOWER]) {
2003                 cond_resched();
2004                 if (node->eb && node->eb->start == edge->blockptr)
2005                         continue;
2006
2007                 upper = edge->node[UPPER];
2008                 root = select_reloc_root(trans, upper, edges, &nr);
2009                 if (!root)
2010                         continue;
2011
2012                 if (upper->eb && !upper->locked)
2013                         drop_node_buffer(upper);
2014
2015                 if (!upper->eb) {
2016                         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2017                         if (ret < 0) {
2018                                 err = ret;
2019                                 break;
2020                         }
2021                         BUG_ON(ret > 0);
2022
2023                         slot = path->slots[upper->level];
2024
2025                         btrfs_unlock_up_safe(path, upper->level + 1);
2026                         grab_path_buffers(path, upper, edges, nr);
2027
2028                         btrfs_release_path(NULL, path);
2029                 } else {
2030                         ret = btrfs_bin_search(upper->eb, key, upper->level,
2031                                                &slot);
2032                         BUG_ON(ret);
2033                 }
2034
2035                 bytenr = btrfs_node_blockptr(upper->eb, slot);
2036                 if (!lowest) {
2037                         if (node->eb->start == bytenr) {
2038                                 btrfs_tree_unlock(upper->eb);
2039                                 upper->locked = 0;
2040                                 continue;
2041                         }
2042                 } else {
2043                         BUG_ON(node->bytenr != bytenr);
2044                 }
2045
2046                 blocksize = btrfs_level_size(root, node->level);
2047                 generation = btrfs_node_ptr_generation(upper->eb, slot);
2048                 eb = read_tree_block(root, bytenr, blocksize, generation);
2049                 btrfs_tree_lock(eb);
2050                 btrfs_set_lock_blocking(eb);
2051
2052                 if (!node->eb) {
2053                         ret = btrfs_cow_block(trans, root, eb, upper->eb,
2054                                               slot, &eb);
2055                         if (ret < 0) {
2056                                 err = ret;
2057                                 break;
2058                         }
2059                         btrfs_set_lock_blocking(eb);
2060                         node->eb = eb;
2061                         node->locked = 1;
2062                 } else {
2063                         btrfs_set_node_blockptr(upper->eb, slot,
2064                                                 node->eb->start);
2065                         btrfs_set_node_ptr_generation(upper->eb, slot,
2066                                                       trans->transid);
2067                         btrfs_mark_buffer_dirty(upper->eb);
2068
2069                         ret = btrfs_inc_extent_ref(trans, root,
2070                                                 node->eb->start, blocksize,
2071                                                 upper->eb->start,
2072                                                 btrfs_header_owner(upper->eb),
2073                                                 node->level, 0);
2074                         BUG_ON(ret);
2075
2076                         ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
2077                         BUG_ON(ret);
2078                 }
2079                 if (!lowest) {
2080                         btrfs_tree_unlock(upper->eb);
2081                         upper->locked = 0;
2082                 }
2083         }
2084         path->lowest_level = 0;
2085         return err;
2086 }
2087
2088 static int link_to_upper(struct btrfs_trans_handle *trans,
2089                          struct backref_node *node,
2090                          struct btrfs_path *path)
2091 {
2092         struct btrfs_key key;
2093         if (!node->eb || list_empty(&node->upper))
2094                 return 0;
2095
2096         btrfs_node_key_to_cpu(node->eb, &key, 0);
2097         return do_relocation(trans, node, &key, path, 0);
2098 }
2099
2100 static int finish_pending_nodes(struct btrfs_trans_handle *trans,
2101                                 struct backref_cache *cache,
2102                                 struct btrfs_path *path)
2103 {
2104         struct backref_node *node;
2105         int level;
2106         int ret;
2107         int err = 0;
2108
2109         for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
2110                 while (!list_empty(&cache->pending[level])) {
2111                         node = list_entry(cache->pending[level].next,
2112                                           struct backref_node, lower);
2113                         BUG_ON(node->level != level);
2114
2115                         ret = link_to_upper(trans, node, path);
2116                         if (ret < 0)
2117                                 err = ret;
2118                         /*
2119                          * this remove the node from the pending list and
2120                          * may add some other nodes to the level + 1
2121                          * pending list
2122                          */
2123                         remove_backref_node(cache, node);
2124                 }
2125         }
2126         BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
2127         return err;
2128 }
2129
2130 static void mark_block_processed(struct reloc_control *rc,
2131                                  struct backref_node *node)
2132 {
2133         u32 blocksize;
2134         if (node->level == 0 ||
2135             in_block_group(node->bytenr, rc->block_group)) {
2136                 blocksize = btrfs_level_size(rc->extent_root, node->level);
2137                 set_extent_bits(&rc->processed_blocks, node->bytenr,
2138                                 node->bytenr + blocksize - 1, EXTENT_DIRTY,
2139                                 GFP_NOFS);
2140         }
2141         node->processed = 1;
2142 }
2143
2144 /*
2145  * mark a block and all blocks directly/indirectly reference the block
2146  * as processed.
2147  */
2148 static void update_processed_blocks(struct reloc_control *rc,
2149                                     struct backref_node *node)
2150 {
2151         struct backref_node *next = node;
2152         struct backref_edge *edge;
2153         struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
2154         int index = 0;
2155
2156         while (next) {
2157                 cond_resched();
2158                 while (1) {
2159                         if (next->processed)
2160                                 break;
2161
2162                         mark_block_processed(rc, next);
2163
2164                         if (list_empty(&next->upper))
2165                                 break;
2166
2167                         edge = list_entry(next->upper.next,
2168                                           struct backref_edge, list[LOWER]);
2169                         edges[index++] = edge;
2170                         next = edge->node[UPPER];
2171                 }
2172                 next = walk_down_backref(edges, &index);
2173         }
2174 }
2175
2176 static int tree_block_processed(u64 bytenr, u32 blocksize,
2177                                 struct reloc_control *rc)
2178 {
2179         if (test_range_bit(&rc->processed_blocks, bytenr,
2180                            bytenr + blocksize - 1, EXTENT_DIRTY, 1))
2181                 return 1;
2182         return 0;
2183 }
2184
2185 /*
2186  * check if there are any file extent pointers in the leaf point to
2187  * data require processing
2188  */
2189 static int check_file_extents(struct reloc_control *rc,
2190                               u64 bytenr, u32 blocksize, u64 ptr_gen)
2191 {
2192         struct btrfs_key found_key;
2193         struct btrfs_file_extent_item *fi;
2194         struct extent_buffer *leaf;
2195         u32 nritems;
2196         int i;
2197         int ret = 0;
2198
2199         leaf = read_tree_block(rc->extent_root, bytenr, blocksize, ptr_gen);
2200
2201         nritems = btrfs_header_nritems(leaf);
2202         for (i = 0; i < nritems; i++) {
2203                 cond_resched();
2204                 btrfs_item_key_to_cpu(leaf, &found_key, i);
2205                 if (found_key.type != BTRFS_EXTENT_DATA_KEY)
2206                         continue;
2207                 fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
2208                 if (btrfs_file_extent_type(leaf, fi) ==
2209                     BTRFS_FILE_EXTENT_INLINE)
2210                         continue;
2211                 bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
2212                 if (bytenr == 0)
2213                         continue;
2214                 if (in_block_group(bytenr, rc->block_group)) {
2215                         ret = 1;
2216                         break;
2217                 }
2218         }
2219         free_extent_buffer(leaf);
2220         return ret;
2221 }
2222
2223 /*
2224  * scan child blocks of a given block to find blocks require processing
2225  */
2226 static int add_child_blocks(struct btrfs_trans_handle *trans,
2227                             struct reloc_control *rc,
2228                             struct backref_node *node,
2229                             struct rb_root *blocks)
2230 {
2231         struct tree_block *block;
2232         struct rb_node *rb_node;
2233         u64 bytenr;
2234         u64 ptr_gen;
2235         u32 blocksize;
2236         u32 nritems;
2237         int i;
2238         int err = 0;
2239
2240         nritems = btrfs_header_nritems(node->eb);
2241         blocksize = btrfs_level_size(rc->extent_root, node->level - 1);
2242         for (i = 0; i < nritems; i++) {
2243                 cond_resched();
2244                 bytenr = btrfs_node_blockptr(node->eb, i);
2245                 ptr_gen = btrfs_node_ptr_generation(node->eb, i);
2246                 if (ptr_gen == trans->transid)
2247                         continue;
2248                 if (!in_block_group(bytenr, rc->block_group) &&
2249                     (node->level > 1 || rc->stage == MOVE_DATA_EXTENTS))
2250                         continue;
2251                 if (tree_block_processed(bytenr, blocksize, rc))
2252                         continue;
2253
2254                 readahead_tree_block(rc->extent_root,
2255                                      bytenr, blocksize, ptr_gen);
2256         }
2257
2258         for (i = 0; i < nritems; i++) {
2259                 cond_resched();
2260                 bytenr = btrfs_node_blockptr(node->eb, i);
2261                 ptr_gen = btrfs_node_ptr_generation(node->eb, i);
2262                 if (ptr_gen == trans->transid)
2263                         continue;
2264                 if (!in_block_group(bytenr, rc->block_group) &&
2265                     (node->level > 1 || rc->stage == MOVE_DATA_EXTENTS))
2266                         continue;
2267                 if (tree_block_processed(bytenr, blocksize, rc))
2268                         continue;
2269                 if (!in_block_group(bytenr, rc->block_group) &&
2270                     !check_file_extents(rc, bytenr, blocksize, ptr_gen))
2271                         continue;
2272
2273                 block = kmalloc(sizeof(*block), GFP_NOFS);
2274                 if (!block) {
2275                         err = -ENOMEM;
2276                         break;
2277                 }
2278                 block->bytenr = bytenr;
2279                 btrfs_node_key_to_cpu(node->eb, &block->key, i);
2280                 block->level = node->level - 1;
2281                 block->key_ready = 1;
2282                 rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
2283                 BUG_ON(rb_node);
2284         }
2285         if (err)
2286                 free_block_list(blocks);
2287         return err;
2288 }
2289
2290 /*
2291  * find adjacent blocks require processing
2292  */
2293 static noinline_for_stack
2294 int add_adjacent_blocks(struct btrfs_trans_handle *trans,
2295                         struct reloc_control *rc,
2296                         struct backref_cache *cache,
2297                         struct rb_root *blocks, int level,
2298                         struct backref_node **upper)
2299 {
2300         struct backref_node *node;
2301         int ret = 0;
2302
2303         WARN_ON(!list_empty(&cache->pending[level]));
2304
2305         if (list_empty(&cache->pending[level + 1]))
2306                 return 1;
2307
2308         node = list_entry(cache->pending[level + 1].next,
2309                           struct backref_node, lower);
2310         if (node->eb)
2311                 ret = add_child_blocks(trans, rc, node, blocks);
2312
2313         *upper = node;
2314         return ret;
2315 }
2316
2317 static int get_tree_block_key(struct reloc_control *rc,
2318                               struct tree_block *block)
2319 {
2320         struct extent_buffer *eb;
2321
2322         BUG_ON(block->key_ready);
2323         eb = read_tree_block(rc->extent_root, block->bytenr,
2324                              block->key.objectid, block->key.offset);
2325         WARN_ON(btrfs_header_level(eb) != block->level);
2326         if (block->level == 0)
2327                 btrfs_item_key_to_cpu(eb, &block->key, 0);
2328         else
2329                 btrfs_node_key_to_cpu(eb, &block->key, 0);
2330         free_extent_buffer(eb);
2331         block->key_ready = 1;
2332         return 0;
2333 }
2334
2335 static int reada_tree_block(struct reloc_control *rc,
2336                             struct tree_block *block)
2337 {
2338         BUG_ON(block->key_ready);
2339         readahead_tree_block(rc->extent_root, block->bytenr,
2340                              block->key.objectid, block->key.offset);
2341         return 0;
2342 }
2343
2344 /*
2345  * helper function to relocate a tree block
2346  */
2347 static int relocate_tree_block(struct btrfs_trans_handle *trans,
2348                                 struct reloc_control *rc,
2349                                 struct backref_node *node,
2350                                 struct btrfs_key *key,
2351                                 struct btrfs_path *path)
2352 {
2353         struct btrfs_root *root;
2354         int ret;
2355
2356         root = select_one_root(trans, node);
2357         if (unlikely(!root)) {
2358                 rc->found_old_snapshot = 1;
2359                 update_processed_blocks(rc, node);
2360                 return 0;
2361         }
2362
2363         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
2364                 ret = do_relocation(trans, node, key, path, 1);
2365                 if (ret < 0)
2366                         goto out;
2367                 if (node->level == 0 && rc->stage == UPDATE_DATA_PTRS) {
2368                         ret = replace_file_extents(trans, rc, root,
2369                                                    node->eb, NULL);
2370                         if (ret < 0)
2371                                 goto out;
2372                 }
2373                 drop_node_buffer(node);
2374         } else if (!root->ref_cows) {
2375                 path->lowest_level = node->level;
2376                 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
2377                 btrfs_release_path(root, path);
2378                 if (ret < 0)
2379                         goto out;
2380         } else if (root != node->root) {
2381                 WARN_ON(node->level > 0 || rc->stage != UPDATE_DATA_PTRS);
2382         }
2383
2384         update_processed_blocks(rc, node);
2385         ret = 0;
2386 out:
2387         drop_node_buffer(node);
2388         return ret;
2389 }
2390
2391 /*
2392  * relocate a list of blocks
2393  */
2394 static noinline_for_stack
2395 int relocate_tree_blocks(struct btrfs_trans_handle *trans,
2396                          struct reloc_control *rc, struct rb_root *blocks)
2397 {
2398         struct backref_cache *cache;
2399         struct backref_node *node;
2400         struct btrfs_path *path;
2401         struct tree_block *block;
2402         struct rb_node *rb_node;
2403         int level = -1;
2404         int ret;
2405         int err = 0;
2406
2407         path = btrfs_alloc_path();
2408         if (!path)
2409                 return -ENOMEM;
2410
2411         cache = kmalloc(sizeof(*cache), GFP_NOFS);
2412         if (!cache) {
2413                 btrfs_free_path(path);
2414                 return -ENOMEM;
2415         }
2416
2417         backref_cache_init(cache);
2418
2419         rb_node = rb_first(blocks);
2420         while (rb_node) {
2421                 block = rb_entry(rb_node, struct tree_block, rb_node);
2422                 if (level == -1)
2423                         level = block->level;
2424                 else
2425                         BUG_ON(level != block->level);
2426                 if (!block->key_ready)
2427                         reada_tree_block(rc, block);
2428                 rb_node = rb_next(rb_node);
2429         }
2430
2431         rb_node = rb_first(blocks);
2432         while (rb_node) {
2433                 block = rb_entry(rb_node, struct tree_block, rb_node);
2434                 if (!block->key_ready)
2435                         get_tree_block_key(rc, block);
2436                 rb_node = rb_next(rb_node);
2437         }
2438
2439         rb_node = rb_first(blocks);
2440         while (rb_node) {
2441                 block = rb_entry(rb_node, struct tree_block, rb_node);
2442
2443                 node = build_backref_tree(rc, cache, &block->key,
2444                                           block->level, block->bytenr);
2445                 if (IS_ERR(node)) {
2446                         err = PTR_ERR(node);
2447                         goto out;
2448                 }
2449
2450                 ret = relocate_tree_block(trans, rc, node, &block->key,
2451                                           path);
2452                 if (ret < 0) {
2453                         err = ret;
2454                         goto out;
2455                 }
2456                 remove_backref_node(cache, node);
2457                 rb_node = rb_next(rb_node);
2458         }
2459
2460         if (level > 0)
2461                 goto out;
2462
2463         free_block_list(blocks);
2464
2465         /*
2466          * now backrefs of some upper level tree blocks have been cached,
2467          * try relocating blocks referenced by these upper level blocks.
2468          */
2469         while (1) {
2470                 struct backref_node *upper = NULL;
2471                 if (trans->transaction->in_commit ||
2472                     trans->transaction->delayed_refs.flushing)
2473                         break;
2474
2475                 ret = add_adjacent_blocks(trans, rc, cache, blocks, level,
2476                                           &upper);
2477                 if (ret < 0)
2478                         err = ret;
2479                 if (ret != 0)
2480                         break;
2481
2482                 rb_node = rb_first(blocks);
2483                 while (rb_node) {
2484                         block = rb_entry(rb_node, struct tree_block, rb_node);
2485                         if (trans->transaction->in_commit ||
2486                             trans->transaction->delayed_refs.flushing)
2487                                 goto out;
2488                         BUG_ON(!block->key_ready);
2489                         node = build_backref_tree(rc, cache, &block->key,
2490                                                   level, block->bytenr);
2491                         if (IS_ERR(node)) {
2492                                 err = PTR_ERR(node);
2493                                 goto out;
2494                         }
2495
2496                         ret = relocate_tree_block(trans, rc, node,
2497                                                   &block->key, path);
2498                         if (ret < 0) {
2499                                 err = ret;
2500                                 goto out;
2501                         }
2502                         remove_backref_node(cache, node);
2503                         rb_node = rb_next(rb_node);
2504                 }
2505                 free_block_list(blocks);
2506
2507                 if (upper) {
2508                         ret = link_to_upper(trans, upper, path);
2509                         if (ret < 0) {
2510                                 err = ret;
2511                                 break;
2512                         }
2513                         remove_backref_node(cache, upper);
2514                 }
2515         }
2516 out:
2517         free_block_list(blocks);
2518
2519         ret = finish_pending_nodes(trans, cache, path);
2520         if (ret < 0)
2521                 err = ret;
2522
2523         kfree(cache);
2524         btrfs_free_path(path);
2525         return err;
2526 }
2527
2528 static noinline_for_stack
2529 int relocate_inode_pages(struct inode *inode, u64 start, u64 len)
2530 {
2531         u64 page_start;
2532         u64 page_end;
2533         unsigned long i;
2534         unsigned long first_index;
2535         unsigned long last_index;
2536         unsigned int total_read = 0;
2537         unsigned int total_dirty = 0;
2538         struct page *page;
2539         struct file_ra_state *ra;
2540         struct btrfs_ordered_extent *ordered;
2541         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
2542         int ret = 0;
2543
2544         ra = kzalloc(sizeof(*ra), GFP_NOFS);
2545         if (!ra)
2546                 return -ENOMEM;
2547
2548         mutex_lock(&inode->i_mutex);
2549         first_index = start >> PAGE_CACHE_SHIFT;
2550         last_index = (start + len - 1) >> PAGE_CACHE_SHIFT;
2551
2552         /* make sure the dirty trick played by the caller work */
2553         ret = invalidate_inode_pages2_range(inode->i_mapping,
2554                                             first_index, last_index);
2555         if (ret)
2556                 goto out_unlock;
2557
2558         file_ra_state_init(ra, inode->i_mapping);
2559
2560         for (i = first_index ; i <= last_index; i++) {
2561                 if (total_read % ra->ra_pages == 0) {
2562                         btrfs_force_ra(inode->i_mapping, ra, NULL, i,
2563                                 min(last_index, ra->ra_pages + i - 1));
2564                 }
2565                 total_read++;
2566 again:
2567                 if (((u64)i << PAGE_CACHE_SHIFT) > i_size_read(inode))
2568                         BUG_ON(1);
2569                 page = grab_cache_page(inode->i_mapping, i);
2570                 if (!page) {
2571                         ret = -ENOMEM;
2572                         goto out_unlock;
2573                 }
2574                 if (!PageUptodate(page)) {
2575                         btrfs_readpage(NULL, page);
2576                         lock_page(page);
2577                         if (!PageUptodate(page)) {
2578                                 unlock_page(page);
2579                                 page_cache_release(page);
2580                                 ret = -EIO;
2581                                 goto out_unlock;
2582                         }
2583                 }
2584                 wait_on_page_writeback(page);
2585
2586                 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
2587                 page_end = page_start + PAGE_CACHE_SIZE - 1;
2588                 lock_extent(io_tree, page_start, page_end, GFP_NOFS);
2589
2590                 ordered = btrfs_lookup_ordered_extent(inode, page_start);
2591                 if (ordered) {
2592                         unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
2593                         unlock_page(page);
2594                         page_cache_release(page);
2595                         btrfs_start_ordered_extent(inode, ordered, 1);
2596                         btrfs_put_ordered_extent(ordered);
2597                         goto again;
2598                 }
2599                 set_page_extent_mapped(page);
2600
2601                 if (i == first_index)
2602                         set_extent_bits(io_tree, page_start, page_end,
2603                                         EXTENT_BOUNDARY, GFP_NOFS);
2604                 btrfs_set_extent_delalloc(inode, page_start, page_end);
2605
2606                 set_page_dirty(page);
2607                 total_dirty++;
2608
2609                 unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
2610                 unlock_page(page);
2611                 page_cache_release(page);
2612         }
2613 out_unlock:
2614         mutex_unlock(&inode->i_mutex);
2615         kfree(ra);
2616         balance_dirty_pages_ratelimited_nr(inode->i_mapping, total_dirty);
2617         return ret;
2618 }
2619
2620 static noinline_for_stack
2621 int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key)
2622 {
2623         struct btrfs_root *root = BTRFS_I(inode)->root;
2624         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
2625         struct extent_map *em;
2626         u64 start = extent_key->objectid - BTRFS_I(inode)->index_cnt;
2627         u64 end = start + extent_key->offset - 1;
2628
2629         em = alloc_extent_map(GFP_NOFS);
2630         em->start = start;
2631         em->len = extent_key->offset;
2632         em->block_len = extent_key->offset;
2633         em->block_start = extent_key->objectid;
2634         em->bdev = root->fs_info->fs_devices->latest_bdev;
2635         set_bit(EXTENT_FLAG_PINNED, &em->flags);
2636
2637         /* setup extent map to cheat btrfs_readpage */
2638         lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2639         while (1) {
2640                 int ret;
2641                 spin_lock(&em_tree->lock);
2642                 ret = add_extent_mapping(em_tree, em);
2643                 spin_unlock(&em_tree->lock);
2644                 if (ret != -EEXIST) {
2645                         free_extent_map(em);
2646                         break;
2647                 }
2648                 btrfs_drop_extent_cache(inode, start, end, 0);
2649         }
2650         unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
2651
2652         return relocate_inode_pages(inode, start, extent_key->offset);
2653 }
2654
2655 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
2656 static int get_ref_objectid_v0(struct reloc_control *rc,
2657                                struct btrfs_path *path,
2658                                struct btrfs_key *extent_key,
2659                                u64 *ref_objectid, int *path_change)
2660 {
2661         struct btrfs_key key;
2662         struct extent_buffer *leaf;
2663         struct btrfs_extent_ref_v0 *ref0;
2664         int ret;
2665         int slot;
2666
2667         leaf = path->nodes[0];
2668         slot = path->slots[0];
2669         while (1) {
2670                 if (slot >= btrfs_header_nritems(leaf)) {
2671                         ret = btrfs_next_leaf(rc->extent_root, path);
2672                         if (ret < 0)
2673                                 return ret;
2674                         BUG_ON(ret > 0);
2675                         leaf = path->nodes[0];
2676                         slot = path->slots[0];
2677                         if (path_change)
2678                                 *path_change = 1;
2679                 }
2680                 btrfs_item_key_to_cpu(leaf, &key, slot);
2681                 if (key.objectid != extent_key->objectid)
2682                         return -ENOENT;
2683
2684                 if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
2685                         slot++;
2686                         continue;
2687                 }
2688                 ref0 = btrfs_item_ptr(leaf, slot,
2689                                 struct btrfs_extent_ref_v0);
2690                 *ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
2691                 break;
2692         }
2693         return 0;
2694 }
2695 #endif
2696
2697 /*
2698  * helper to add a tree block to the list.
2699  * the major work is getting the generation and level of the block
2700  */
2701 static int add_tree_block(struct reloc_control *rc,
2702                           struct btrfs_key *extent_key,
2703                           struct btrfs_path *path,
2704                           struct rb_root *blocks)
2705 {
2706         struct extent_buffer *eb;
2707         struct btrfs_extent_item *ei;
2708         struct btrfs_tree_block_info *bi;
2709         struct tree_block *block;
2710         struct rb_node *rb_node;
2711         u32 item_size;
2712         int level = -1;
2713         int generation;
2714
2715         eb =  path->nodes[0];
2716         item_size = btrfs_item_size_nr(eb, path->slots[0]);
2717
2718         if (item_size >= sizeof(*ei) + sizeof(*bi)) {
2719                 ei = btrfs_item_ptr(eb, path->slots[0],
2720                                 struct btrfs_extent_item);
2721                 bi = (struct btrfs_tree_block_info *)(ei + 1);
2722                 generation = btrfs_extent_generation(eb, ei);
2723                 level = btrfs_tree_block_level(eb, bi);
2724         } else {
2725 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
2726                 u64 ref_owner;
2727                 int ret;
2728
2729                 BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
2730                 ret = get_ref_objectid_v0(rc, path, extent_key,
2731                                           &ref_owner, NULL);
2732                 BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
2733                 level = (int)ref_owner;
2734                 /* FIXME: get real generation */
2735                 generation = 0;
2736 #else
2737                 BUG();
2738 #endif
2739         }
2740
2741         btrfs_release_path(rc->extent_root, path);
2742
2743         BUG_ON(level == -1);
2744
2745         block = kmalloc(sizeof(*block), GFP_NOFS);
2746         if (!block)
2747                 return -ENOMEM;
2748
2749         block->bytenr = extent_key->objectid;
2750         block->key.objectid = extent_key->offset;
2751         block->key.offset = generation;
2752         block->level = level;
2753         block->key_ready = 0;
2754
2755         rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
2756         BUG_ON(rb_node);
2757
2758         return 0;
2759 }
2760
2761 /*
2762  * helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
2763  */
2764 static int __add_tree_block(struct reloc_control *rc,
2765                             u64 bytenr, u32 blocksize,
2766                             struct rb_root *blocks)
2767 {
2768         struct btrfs_path *path;
2769         struct btrfs_key key;
2770         int ret;
2771
2772         if (tree_block_processed(bytenr, blocksize, rc))
2773                 return 0;
2774
2775         if (tree_search(blocks, bytenr))
2776                 return 0;
2777
2778         path = btrfs_alloc_path();
2779         if (!path)
2780                 return -ENOMEM;
2781
2782         key.objectid = bytenr;
2783         key.type = BTRFS_EXTENT_ITEM_KEY;
2784         key.offset = blocksize;
2785
2786         path->search_commit_root = 1;
2787         path->skip_locking = 1;
2788         ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
2789         if (ret < 0)
2790                 goto out;
2791         BUG_ON(ret);
2792
2793         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2794         ret = add_tree_block(rc, &key, path, blocks);
2795 out:
2796         btrfs_free_path(path);
2797         return ret;
2798 }
2799
2800 /*
2801  * helper to check if the block use full backrefs for pointers in it
2802  */
2803 static int block_use_full_backref(struct reloc_control *rc,
2804                                   struct extent_buffer *eb)
2805 {
2806         struct btrfs_path *path;
2807         struct btrfs_extent_item *ei;
2808         struct btrfs_key key;
2809         u64 flags;
2810         int ret;
2811
2812         if (btrfs_header_flag(eb, BTRFS_HEADER_FLAG_RELOC) ||
2813             btrfs_header_backref_rev(eb) < BTRFS_MIXED_BACKREF_REV)
2814                 return 1;
2815
2816         path = btrfs_alloc_path();
2817         BUG_ON(!path);
2818
2819         key.objectid = eb->start;
2820         key.type = BTRFS_EXTENT_ITEM_KEY;
2821         key.offset = eb->len;
2822
2823         path->search_commit_root = 1;
2824         path->skip_locking = 1;
2825         ret = btrfs_search_slot(NULL, rc->extent_root,
2826                                 &key, path, 0, 0);
2827         BUG_ON(ret);
2828
2829         ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
2830                             struct btrfs_extent_item);
2831         flags = btrfs_extent_flags(path->nodes[0], ei);
2832         BUG_ON(!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK));
2833         if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)
2834                 ret = 1;
2835         else
2836                 ret = 0;
2837         btrfs_free_path(path);
2838         return ret;
2839 }
2840
2841 /*
2842  * helper to add tree blocks for backref of type BTRFS_EXTENT_DATA_REF_KEY
2843  * this function scans fs tree to find blocks reference the data extent
2844  */
2845 static int find_data_references(struct reloc_control *rc,
2846                                 struct btrfs_key *extent_key,
2847                                 struct extent_buffer *leaf,
2848                                 struct btrfs_extent_data_ref *ref,
2849                                 struct rb_root *blocks)
2850 {
2851         struct btrfs_path *path;
2852         struct tree_block *block;
2853         struct btrfs_root *root;
2854         struct btrfs_file_extent_item *fi;
2855         struct rb_node *rb_node;
2856         struct btrfs_key key;
2857         u64 ref_root;
2858         u64 ref_objectid;
2859         u64 ref_offset;
2860         u32 ref_count;
2861         u32 nritems;
2862         int err = 0;
2863         int added = 0;
2864         int counted;
2865         int ret;
2866
2867         path = btrfs_alloc_path();
2868         if (!path)
2869                 return -ENOMEM;
2870
2871         ref_root = btrfs_extent_data_ref_root(leaf, ref);
2872         ref_objectid = btrfs_extent_data_ref_objectid(leaf, ref);
2873         ref_offset = btrfs_extent_data_ref_offset(leaf, ref);
2874         ref_count = btrfs_extent_data_ref_count(leaf, ref);
2875
2876         root = read_fs_root(rc->extent_root->fs_info, ref_root);
2877         if (IS_ERR(root)) {
2878                 err = PTR_ERR(root);
2879                 goto out;
2880         }
2881
2882         key.objectid = ref_objectid;
2883         key.offset = ref_offset;
2884         key.type = BTRFS_EXTENT_DATA_KEY;
2885
2886         path->search_commit_root = 1;
2887         path->skip_locking = 1;
2888         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2889         if (ret < 0) {
2890                 err = ret;
2891                 goto out;
2892         }
2893
2894         leaf = path->nodes[0];
2895         nritems = btrfs_header_nritems(leaf);
2896         /*
2897          * the references in tree blocks that use full backrefs
2898          * are not counted in
2899          */
2900         if (block_use_full_backref(rc, leaf))
2901                 counted = 0;
2902         else
2903                 counted = 1;
2904         rb_node = tree_search(blocks, leaf->start);
2905         if (rb_node) {
2906                 if (counted)
2907                         added = 1;
2908                 else
2909                         path->slots[0] = nritems;
2910         }
2911
2912         while (ref_count > 0) {
2913                 while (path->slots[0] >= nritems) {
2914                         ret = btrfs_next_leaf(root, path);
2915                         if (ret < 0) {
2916                                 err = ret;
2917                                 goto out;
2918                         }
2919                         if (ret > 0) {
2920                                 WARN_ON(1);
2921                                 goto out;
2922                         }
2923
2924                         leaf = path->nodes[0];
2925                         nritems = btrfs_header_nritems(leaf);
2926                         added = 0;
2927
2928                         if (block_use_full_backref(rc, leaf))
2929                                 counted = 0;
2930                         else
2931                                 counted = 1;
2932                         rb_node = tree_search(blocks, leaf->start);
2933                         if (rb_node) {
2934                                 if (counted)
2935                                         added = 1;
2936                                 else
2937                                         path->slots[0] = nritems;
2938                         }
2939                 }
2940
2941                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2942                 if (key.objectid != ref_objectid ||
2943                     key.type != BTRFS_EXTENT_DATA_KEY) {
2944                         WARN_ON(1);
2945                         break;
2946                 }
2947
2948                 fi = btrfs_item_ptr(leaf, path->slots[0],
2949                                     struct btrfs_file_extent_item);
2950
2951                 if (btrfs_file_extent_type(leaf, fi) ==
2952                     BTRFS_FILE_EXTENT_INLINE)
2953                         goto next;
2954
2955                 if (btrfs_file_extent_disk_bytenr(leaf, fi) !=
2956                     extent_key->objectid)
2957                         goto next;
2958
2959                 key.offset -= btrfs_file_extent_offset(leaf, fi);
2960                 if (key.offset != ref_offset)
2961                         goto next;
2962
2963                 if (counted)
2964                         ref_count--;
2965                 if (added)
2966                         goto next;
2967
2968                 if (!tree_block_processed(leaf->start, leaf->len, rc)) {
2969                         block = kmalloc(sizeof(*block), GFP_NOFS);
2970                         if (!block) {
2971                                 err = -ENOMEM;
2972                                 break;
2973                         }
2974                         block->bytenr = leaf->start;
2975                         btrfs_item_key_to_cpu(leaf, &block->key, 0);
2976                         block->level = 0;
2977                         block->key_ready = 1;
2978                         rb_node = tree_insert(blocks, block->bytenr,
2979                                               &block->rb_node);
2980                         BUG_ON(rb_node);
2981                 }
2982                 if (counted)
2983                         added = 1;
2984                 else
2985                         path->slots[0] = nritems;
2986 next:
2987                 path->slots[0]++;
2988
2989         }
2990 out:
2991         btrfs_free_path(path);
2992         return err;
2993 }
2994
2995 /*
2996  * hepler to find all tree blocks that reference a given data extent
2997  */
2998 static noinline_for_stack
2999 int add_data_references(struct reloc_control *rc,
3000                         struct btrfs_key *extent_key,
3001                         struct btrfs_path *path,
3002                         struct rb_root *blocks)
3003 {
3004         struct btrfs_key key;
3005         struct extent_buffer *eb;
3006         struct btrfs_extent_data_ref *dref;
3007         struct btrfs_extent_inline_ref *iref;
3008         unsigned long ptr;
3009         unsigned long end;
3010         u32 blocksize;
3011         int ret;
3012         int err = 0;
3013
3014         ret = get_new_location(rc->data_inode, NULL, extent_key->objectid,
3015                                extent_key->offset);
3016         BUG_ON(ret < 0);
3017         if (ret > 0) {
3018                 /* the relocated data is fragmented */
3019                 rc->extents_skipped++;
3020                 btrfs_release_path(rc->extent_root, path);
3021                 return 0;
3022         }
3023
3024         blocksize = btrfs_level_size(rc->extent_root, 0);
3025
3026         eb = path->nodes[0];
3027         ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
3028         end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
3029 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3030         if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
3031                 ptr = end;
3032         else
3033 #endif
3034                 ptr += sizeof(struct btrfs_extent_item);
3035
3036         while (ptr < end) {
3037                 iref = (struct btrfs_extent_inline_ref *)ptr;
3038                 key.type = btrfs_extent_inline_ref_type(eb, iref);
3039                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3040                         key.offset = btrfs_extent_inline_ref_offset(eb, iref);
3041                         ret = __add_tree_block(rc, key.offset, blocksize,
3042                                                blocks);
3043                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3044                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
3045                         ret = find_data_references(rc, extent_key,
3046                                                    eb, dref, blocks);
3047                 } else {
3048                         BUG();
3049                 }
3050                 ptr += btrfs_extent_inline_ref_size(key.type);
3051         }
3052         WARN_ON(ptr > end);
3053
3054         while (1) {
3055                 cond_resched();
3056                 eb = path->nodes[0];
3057                 if (path->slots[0] >= btrfs_header_nritems(eb)) {
3058                         ret = btrfs_next_leaf(rc->extent_root, path);
3059                         if (ret < 0) {
3060                                 err = ret;
3061                                 break;
3062                         }
3063                         if (ret > 0)
3064                                 break;
3065                         eb = path->nodes[0];
3066                 }
3067
3068                 btrfs_item_key_to_cpu(eb, &key, path->slots[0]);
3069                 if (key.objectid != extent_key->objectid)
3070                         break;
3071
3072 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3073                 if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
3074                     key.type == BTRFS_EXTENT_REF_V0_KEY) {
3075 #else
3076                 BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
3077                 if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
3078 #endif
3079                         ret = __add_tree_block(rc, key.offset, blocksize,
3080                                                blocks);
3081                 } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
3082                         dref = btrfs_item_ptr(eb, path->slots[0],
3083                                               struct btrfs_extent_data_ref);
3084                         ret = find_data_references(rc, extent_key,
3085                                                    eb, dref, blocks);
3086                 } else {
3087                         ret = 0;
3088                 }
3089                 if (ret) {
3090                         err = ret;
3091                         break;
3092                 }
3093                 path->slots[0]++;
3094         }
3095         btrfs_release_path(rc->extent_root, path);
3096         if (err)
3097                 free_block_list(blocks);
3098         return err;
3099 }
3100
3101 /*
3102  * hepler to find next unprocessed extent
3103  */
3104 static noinline_for_stack
3105 int find_next_extent(struct btrfs_trans_handle *trans,
3106                      struct reloc_control *rc, struct btrfs_path *path)
3107 {
3108         struct btrfs_key key;
3109         struct extent_buffer *leaf;
3110         u64 start, end, last;
3111         int ret;
3112
3113         last = rc->block_group->key.objectid + rc->block_group->key.offset;
3114         while (1) {
3115                 cond_resched();
3116                 if (rc->search_start >= last) {
3117                         ret = 1;
3118                         break;
3119                 }
3120
3121                 key.objectid = rc->search_start;
3122                 key.type = BTRFS_EXTENT_ITEM_KEY;
3123                 key.offset = 0;
3124
3125                 path->search_commit_root = 1;
3126                 path->skip_locking = 1;
3127                 ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
3128                                         0, 0);
3129                 if (ret < 0)
3130                         break;
3131 next:
3132                 leaf = path->nodes[0];
3133                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
3134                         ret = btrfs_next_leaf(rc->extent_root, path);
3135                         if (ret != 0)
3136                                 break;
3137                         leaf = path->nodes[0];
3138                 }
3139
3140                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3141                 if (key.objectid >= last) {
3142                         ret = 1;
3143                         break;
3144                 }
3145
3146                 if (key.type != BTRFS_EXTENT_ITEM_KEY ||
3147                     key.objectid + key.offset <= rc->search_start) {
3148                         path->slots[0]++;
3149                         goto next;
3150                 }
3151
3152                 ret = find_first_extent_bit(&rc->processed_blocks,
3153                                             key.objectid, &start, &end,
3154                                             EXTENT_DIRTY);
3155
3156                 if (ret == 0 && start <= key.objectid) {
3157                         btrfs_release_path(rc->extent_root, path);
3158                         rc->search_start = end + 1;
3159                 } else {
3160                         rc->search_start = key.objectid + key.offset;
3161                         return 0;
3162                 }
3163         }
3164         btrfs_release_path(rc->extent_root, path);
3165         return ret;
3166 }
3167
3168 static void set_reloc_control(struct reloc_control *rc)
3169 {
3170         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3171         mutex_lock(&fs_info->trans_mutex);
3172         fs_info->reloc_ctl = rc;
3173         mutex_unlock(&fs_info->trans_mutex);
3174 }
3175
3176 static void unset_reloc_control(struct reloc_control *rc)
3177 {
3178         struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
3179         mutex_lock(&fs_info->trans_mutex);
3180         fs_info->reloc_ctl = NULL;
3181         mutex_unlock(&fs_info->trans_mutex);
3182 }
3183
3184 static int check_extent_flags(u64 flags)
3185 {
3186         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3187             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3188                 return 1;
3189         if (!(flags & BTRFS_EXTENT_FLAG_DATA) &&
3190             !(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
3191                 return 1;
3192         if ((flags & BTRFS_EXTENT_FLAG_DATA) &&
3193             (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))
3194                 return 1;
3195         return 0;
3196 }
3197
3198 static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
3199 {
3200         struct rb_root blocks = RB_ROOT;
3201         struct btrfs_key key;
3202         struct btrfs_trans_handle *trans = NULL;
3203         struct btrfs_path *path;
3204         struct btrfs_extent_item *ei;
3205         unsigned long nr;
3206         u64 flags;
3207         u32 item_size;
3208         int ret;
3209         int err = 0;
3210
3211         path = btrfs_alloc_path();
3212         if (!path)
3213                 return -ENOMEM;
3214
3215         rc->search_start = rc->block_group->key.objectid;
3216         clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY,
3217                           GFP_NOFS);
3218
3219         rc->create_reloc_root = 1;
3220         set_reloc_control(rc);
3221
3222         trans = btrfs_start_transaction(rc->extent_root, 1);
3223         btrfs_commit_transaction(trans, rc->extent_root);
3224
3225         while (1) {
3226                 trans = btrfs_start_transaction(rc->extent_root, 1);
3227
3228                 ret = find_next_extent(trans, rc, path);
3229                 if (ret < 0)
3230                         err = ret;
3231                 if (ret != 0)
3232                         break;
3233
3234                 rc->extents_found++;
3235
3236                 ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
3237                                     struct btrfs_extent_item);
3238                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3239                 item_size = btrfs_item_size_nr(path->nodes[0],
3240                                                path->slots[0]);
3241                 if (item_size >= sizeof(*ei)) {
3242                         flags = btrfs_extent_flags(path->nodes[0], ei);
3243                         ret = check_extent_flags(flags);
3244                         BUG_ON(ret);
3245
3246                 } else {
3247 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
3248                         u64 ref_owner;
3249                         int path_change = 0;
3250
3251                         BUG_ON(item_size !=
3252                                sizeof(struct btrfs_extent_item_v0));
3253                         ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
3254                                                   &path_change);
3255                         if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
3256                                 flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
3257                         else
3258                                 flags = BTRFS_EXTENT_FLAG_DATA;
3259
3260                         if (path_change) {
3261                                 btrfs_release_path(rc->extent_root, path);
3262
3263                                 path->search_commit_root = 1;
3264                                 path->skip_locking = 1;
3265                                 ret = btrfs_search_slot(NULL, rc->extent_root,
3266                                                         &key, path, 0, 0);
3267                                 if (ret < 0) {
3268                                         err = ret;
3269                                         break;
3270                                 }
3271                                 BUG_ON(ret > 0);
3272                         }
3273 #else
3274                         BUG();
3275 #endif
3276                 }
3277
3278                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
3279                         ret = add_tree_block(rc, &key, path, &blocks);
3280                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3281                          (flags & BTRFS_EXTENT_FLAG_DATA)) {
3282                         ret = add_data_references(rc, &key, path, &blocks);
3283                 } else {
3284                         btrfs_release_path(rc->extent_root, path);
3285                         ret = 0;
3286                 }
3287                 if (ret < 0) {
3288                         err = 0;
3289                         break;
3290                 }
3291
3292                 if (!RB_EMPTY_ROOT(&blocks)) {
3293                         ret = relocate_tree_blocks(trans, rc, &blocks);
3294                         if (ret < 0) {
3295                                 err = ret;
3296                                 break;
3297                         }
3298                 }
3299
3300                 nr = trans->blocks_used;
3301                 btrfs_end_transaction_throttle(trans, rc->extent_root);
3302                 trans = NULL;
3303                 btrfs_btree_balance_dirty(rc->extent_root, nr);
3304
3305                 if (rc->stage == MOVE_DATA_EXTENTS &&
3306                     (flags & BTRFS_EXTENT_FLAG_DATA)) {
3307                         rc->found_file_extent = 1;
3308                         ret = relocate_data_extent(rc->data_inode, &key);
3309                         if (ret < 0) {
3310                                 err = ret;
3311                                 break;
3312                         }
3313                 }
3314         }
3315         btrfs_free_path(path);
3316
3317         if (trans) {
3318                 nr = trans->blocks_used;
3319                 btrfs_end_transaction(trans, rc->extent_root);
3320                 btrfs_btree_balance_dirty(rc->extent_root, nr);
3321         }
3322
3323         rc->create_reloc_root = 0;
3324         smp_mb();
3325
3326         if (rc->extents_found > 0) {
3327                 trans = btrfs_start_transaction(rc->extent_root, 1);
3328                 btrfs_commit_transaction(trans, rc->extent_root);
3329         }
3330
3331         merge_reloc_roots(rc);
3332
3333         unset_reloc_control(rc);
3334
3335         /* get rid of pinned extents */
3336         trans = btrfs_start_transaction(rc->extent_root, 1);
3337         btrfs_commit_transaction(trans, rc->extent_root);
3338
3339         return err;
3340 }
3341
3342 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
3343                                  struct btrfs_root *root,
3344                                  u64 objectid, u64 size)
3345 {
3346         struct btrfs_path *path;
3347         struct btrfs_inode_item *item;
3348         struct extent_buffer *leaf;
3349         int ret;
3350
3351         path = btrfs_alloc_path();
3352         if (!path)
3353                 return -ENOMEM;
3354
3355         ret = btrfs_insert_empty_inode(trans, root, path, objectid);
3356         if (ret)
3357                 goto out;
3358
3359         leaf = path->nodes[0];
3360         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
3361         memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
3362         btrfs_set_inode_generation(leaf, item, 1);
3363         btrfs_set_inode_size(leaf, item, size);
3364         btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
3365         btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NOCOMPRESS);
3366         btrfs_mark_buffer_dirty(leaf);
3367         btrfs_release_path(root, path);
3368 out:
3369         btrfs_free_path(path);
3370         return ret;
3371 }
3372
3373 /*
3374  * helper to create inode for data relocation.
3375  * the inode is in data relocation tree and its link count is 0
3376  */
3377 static struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
3378                                         struct btrfs_block_group_cache *group)
3379 {
3380         struct inode *inode = NULL;
3381         struct btrfs_trans_handle *trans;
3382         struct btrfs_root *root;
3383         struct btrfs_key key;
3384         unsigned long nr;
3385         u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
3386         int err = 0;
3387
3388         root = read_fs_root(fs_info, BTRFS_DATA_RELOC_TREE_OBJECTID);
3389         if (IS_ERR(root))
3390                 return ERR_CAST(root);
3391
3392         trans = btrfs_start_transaction(root, 1);
3393         BUG_ON(!trans);
3394
3395         err = btrfs_find_free_objectid(trans, root, objectid, &objectid);
3396         if (err)
3397                 goto out;
3398
3399         err = __insert_orphan_inode(trans, root, objectid, group->key.offset);
3400         BUG_ON(err);
3401
3402         err = btrfs_insert_file_extent(trans, root, objectid, 0, 0, 0,
3403                                        group->key.offset, 0, group->key.offset,
3404                                        0, 0, 0);
3405         BUG_ON(err);
3406
3407         key.objectid = objectid;
3408         key.type = BTRFS_INODE_ITEM_KEY;
3409         key.offset = 0;
3410         inode = btrfs_iget(root->fs_info->sb, &key, root);
3411         BUG_ON(IS_ERR(inode) || is_bad_inode(inode));
3412         BTRFS_I(inode)->index_cnt = group->key.objectid;
3413
3414         err = btrfs_orphan_add(trans, inode);
3415 out:
3416         nr = trans->blocks_used;
3417         btrfs_end_transaction(trans, root);
3418
3419         btrfs_btree_balance_dirty(root, nr);
3420         if (err) {
3421                 if (inode)
3422                         iput(inode);
3423                 inode = ERR_PTR(err);
3424         }
3425         return inode;
3426 }
3427
3428 /*
3429  * function to relocate all extents in a block group.
3430  */
3431 int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
3432 {
3433         struct btrfs_fs_info *fs_info = extent_root->fs_info;
3434         struct reloc_control *rc;
3435         int ret;
3436         int err = 0;
3437
3438         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3439         if (!rc)
3440                 return -ENOMEM;
3441
3442         mapping_tree_init(&rc->reloc_root_tree);
3443         extent_io_tree_init(&rc->processed_blocks, NULL, GFP_NOFS);
3444         INIT_LIST_HEAD(&rc->reloc_roots);
3445
3446         rc->block_group = btrfs_lookup_block_group(fs_info, group_start);
3447         BUG_ON(!rc->block_group);
3448
3449         btrfs_init_workers(&rc->workers, "relocate",
3450                            fs_info->thread_pool_size);
3451
3452         rc->extent_root = extent_root;
3453         btrfs_prepare_block_group_relocation(extent_root, rc->block_group);
3454
3455         rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
3456         if (IS_ERR(rc->data_inode)) {
3457                 err = PTR_ERR(rc->data_inode);
3458                 rc->data_inode = NULL;
3459                 goto out;
3460         }
3461
3462         printk(KERN_INFO "btrfs: relocating block group %llu flags %llu\n",
3463                (unsigned long long)rc->block_group->key.objectid,
3464                (unsigned long long)rc->block_group->flags);
3465
3466         btrfs_start_delalloc_inodes(fs_info->tree_root);
3467         btrfs_wait_ordered_extents(fs_info->tree_root, 0);
3468
3469         while (1) {
3470                 mutex_lock(&fs_info->cleaner_mutex);
3471                 btrfs_clean_old_snapshots(fs_info->tree_root);
3472                 mutex_unlock(&fs_info->cleaner_mutex);
3473
3474                 rc->extents_found = 0;
3475                 rc->extents_skipped = 0;
3476
3477                 ret = relocate_block_group(rc);
3478                 if (ret < 0) {
3479                         err = ret;
3480                         break;
3481                 }
3482
3483                 if (rc->extents_found == 0)
3484                         break;
3485
3486                 printk(KERN_INFO "btrfs: found %llu extents\n",
3487                         (unsigned long long)rc->extents_found);
3488
3489                 if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
3490                         btrfs_wait_ordered_range(rc->data_inode, 0, (u64)-1);
3491                         invalidate_mapping_pages(rc->data_inode->i_mapping,
3492                                                  0, -1);
3493                         rc->stage = UPDATE_DATA_PTRS;
3494                 } else if (rc->stage == UPDATE_DATA_PTRS &&
3495                            rc->extents_skipped >= rc->extents_found) {
3496                         iput(rc->data_inode);
3497                         rc->data_inode = create_reloc_inode(fs_info,
3498                                                             rc->block_group);
3499                         if (IS_ERR(rc->data_inode)) {
3500                                 err = PTR_ERR(rc->data_inode);
3501                                 rc->data_inode = NULL;
3502                                 break;
3503                         }
3504                         rc->stage = MOVE_DATA_EXTENTS;
3505                         rc->found_file_extent = 0;
3506                 }
3507         }
3508
3509         filemap_fdatawrite_range(fs_info->btree_inode->i_mapping,
3510                                  rc->block_group->key.objectid,
3511                                  rc->block_group->key.objectid +
3512                                  rc->block_group->key.offset - 1);
3513
3514         WARN_ON(rc->block_group->pinned > 0);
3515         WARN_ON(rc->block_group->reserved > 0);
3516         WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
3517 out:
3518         iput(rc->data_inode);
3519         btrfs_stop_workers(&rc->workers);
3520         btrfs_put_block_group(rc->block_group);
3521         kfree(rc);
3522         return err;
3523 }
3524
3525 /*
3526  * recover relocation interrupted by system crash.
3527  *
3528  * this function resumes merging reloc trees with corresponding fs trees.
3529  * this is important for keeping the sharing of tree blocks
3530  */
3531 int btrfs_recover_relocation(struct btrfs_root *root)
3532 {
3533         LIST_HEAD(reloc_roots);
3534         struct btrfs_key key;
3535         struct btrfs_root *fs_root;
3536         struct btrfs_root *reloc_root;
3537         struct btrfs_path *path;
3538         struct extent_buffer *leaf;
3539         struct reloc_control *rc = NULL;
3540         struct btrfs_trans_handle *trans;
3541         int ret;
3542         int err = 0;
3543
3544         path = btrfs_alloc_path();
3545         if (!path)
3546                 return -ENOMEM;
3547
3548         key.objectid = BTRFS_TREE_RELOC_OBJECTID;
3549         key.type = BTRFS_ROOT_ITEM_KEY;
3550         key.offset = (u64)-1;
3551
3552         while (1) {
3553                 ret = btrfs_search_slot(NULL, root->fs_info->tree_root, &key,
3554                                         path, 0, 0);
3555                 if (ret < 0) {
3556                         err = ret;
3557                         goto out;
3558                 }
3559                 if (ret > 0) {
3560                         if (path->slots[0] == 0)
3561                                 break;
3562                         path->slots[0]--;
3563                 }
3564                 leaf = path->nodes[0];
3565                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3566                 btrfs_release_path(root->fs_info->tree_root, path);
3567
3568                 if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
3569                     key.type != BTRFS_ROOT_ITEM_KEY)
3570                         break;
3571
3572                 reloc_root = btrfs_read_fs_root_no_radix(root, &key);
3573                 if (IS_ERR(reloc_root)) {
3574                         err = PTR_ERR(reloc_root);
3575                         goto out;
3576                 }
3577
3578                 list_add(&reloc_root->root_list, &reloc_roots);
3579
3580                 if (btrfs_root_refs(&reloc_root->root_item) > 0) {
3581                         fs_root = read_fs_root(root->fs_info,
3582                                                reloc_root->root_key.offset);
3583                         if (IS_ERR(fs_root)) {
3584                                 err = PTR_ERR(fs_root);
3585                                 goto out;
3586                         }
3587                 }
3588
3589                 if (key.offset == 0)
3590                         break;
3591
3592                 key.offset--;
3593         }
3594         btrfs_release_path(root->fs_info->tree_root, path);
3595
3596         if (list_empty(&reloc_roots))
3597                 goto out;
3598
3599         rc = kzalloc(sizeof(*rc), GFP_NOFS);
3600         if (!rc) {
3601                 err = -ENOMEM;
3602                 goto out;
3603         }
3604
3605         mapping_tree_init(&rc->reloc_root_tree);
3606         INIT_LIST_HEAD(&rc->reloc_roots);
3607         btrfs_init_workers(&rc->workers, "relocate",
3608                            root->fs_info->thread_pool_size);
3609         rc->extent_root = root->fs_info->extent_root;
3610
3611         set_reloc_control(rc);
3612
3613         while (!list_empty(&reloc_roots)) {
3614                 reloc_root = list_entry(reloc_roots.next,
3615                                         struct btrfs_root, root_list);
3616                 list_del(&reloc_root->root_list);
3617
3618                 if (btrfs_root_refs(&reloc_root->root_item) == 0) {
3619                         list_add_tail(&reloc_root->root_list,
3620                                       &rc->reloc_roots);
3621                         continue;
3622                 }
3623
3624                 fs_root = read_fs_root(root->fs_info,
3625                                        reloc_root->root_key.offset);
3626                 BUG_ON(IS_ERR(fs_root));
3627
3628                 __add_reloc_root(reloc_root);
3629                 fs_root->reloc_root = reloc_root;
3630         }
3631
3632         trans = btrfs_start_transaction(rc->extent_root, 1);
3633         btrfs_commit_transaction(trans, rc->extent_root);
3634
3635         merge_reloc_roots(rc);
3636
3637         unset_reloc_control(rc);
3638
3639         trans = btrfs_start_transaction(rc->extent_root, 1);
3640         btrfs_commit_transaction(trans, rc->extent_root);
3641 out:
3642         if (rc) {
3643                 btrfs_stop_workers(&rc->workers);
3644                 kfree(rc);
3645         }
3646         while (!list_empty(&reloc_roots)) {
3647                 reloc_root = list_entry(reloc_roots.next,
3648                                         struct btrfs_root, root_list);
3649                 list_del(&reloc_root->root_list);
3650                 free_extent_buffer(reloc_root->node);
3651                 free_extent_buffer(reloc_root->commit_root);
3652                 kfree(reloc_root);
3653         }
3654         btrfs_free_path(path);
3655
3656         if (err == 0) {
3657                 /* cleanup orphan inode in data relocation tree */
3658                 fs_root = read_fs_root(root->fs_info,
3659                                        BTRFS_DATA_RELOC_TREE_OBJECTID);
3660                 if (IS_ERR(fs_root))
3661                         err = PTR_ERR(fs_root);
3662         }
3663         return err;
3664 }
3665
3666 /*
3667  * helper to add ordered checksum for data relocation.
3668  *
3669  * cloning checksum properly handles the nodatasum extents.
3670  * it also saves CPU time to re-calculate the checksum.
3671  */
3672 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
3673 {
3674         struct btrfs_ordered_sum *sums;
3675         struct btrfs_sector_sum *sector_sum;
3676         struct btrfs_ordered_extent *ordered;
3677         struct btrfs_root *root = BTRFS_I(inode)->root;
3678         size_t offset;
3679         int ret;
3680         u64 disk_bytenr;
3681         LIST_HEAD(list);
3682
3683         ordered = btrfs_lookup_ordered_extent(inode, file_pos);
3684         BUG_ON(ordered->file_offset != file_pos || ordered->len != len);
3685
3686         disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
3687         ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
3688                                        disk_bytenr + len - 1, &list);
3689
3690         while (!list_empty(&list)) {
3691                 sums = list_entry(list.next, struct btrfs_ordered_sum, list);
3692                 list_del_init(&sums->list);
3693
3694                 sector_sum = sums->sums;
3695                 sums->bytenr = ordered->start;
3696
3697                 offset = 0;
3698                 while (offset < sums->len) {
3699                         sector_sum->bytenr += ordered->start - disk_bytenr;
3700                         sector_sum++;
3701                         offset += root->sectorsize;
3702                 }
3703
3704                 btrfs_add_ordered_sum(inode, ordered, sums);
3705         }
3706         btrfs_put_ordered_extent(ordered);
3707         return 0;
3708 }