btrfs-progs: add OPEN_CTREE_INVALIDATE_FST flag
[platform/upstream/btrfs-progs.git] / extent-tree.c
index a7f04f4..3b1577e 100644 (file)
@@ -18,6 +18,8 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdint.h>
+#include <math.h>
 #include "kerncompat.h"
 #include "radix-tree.h"
 #include "ctree.h"
 #include "transaction.h"
 #include "crc32c.h"
 #include "volumes.h"
+#include "free-space-cache.h"
+#include "utils.h"
 
-#define BLOCK_GROUP_DATA     EXTENT_WRITEBACK
-#define BLOCK_GROUP_METADATA EXTENT_UPTODATE
-#define BLOCK_GROUP_SYSTEM   EXTENT_NEW
-
-#define BLOCK_GROUP_DIRTY EXTENT_DIRTY
+#define PENDING_EXTENT_INSERT 0
+#define PENDING_EXTENT_DELETE 1
+#define PENDING_BACKREF_UPDATE 2
 
+struct pending_extent_op {
+       int type;
+       u64 bytenr;
+       u64 num_bytes;
+       u64 flags;
+       struct btrfs_disk_key key;
+       int level;
+};
+
+static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
+                                    struct btrfs_root *root,
+                                    u64 root_objectid, u64 generation,
+                                    u64 flags, struct btrfs_disk_key *key,
+                                    int level, struct btrfs_key *ins);
+static int __free_extent(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root,
+                        u64 bytenr, u64 num_bytes, u64 parent,
+                        u64 root_objectid, u64 owner_objectid,
+                        u64 owner_offset, int refs_to_drop);
 static int finish_current_insert(struct btrfs_trans_handle *trans, struct
                                 btrfs_root *extent_root);
 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                               btrfs_root *extent_root);
+static struct btrfs_block_group_cache *
+btrfs_find_block_group(struct btrfs_root *root, struct btrfs_block_group_cache
+                      *hint, u64 search_start, int data, int owner);
+
+static int remove_sb_from_cache(struct btrfs_root *root,
+                               struct btrfs_block_group_cache *cache)
+{
+       u64 bytenr;
+       u64 *logical;
+       int stripe_len;
+       int i, nr, ret;
+       struct extent_io_tree *free_space_cache;
+
+       free_space_cache = &root->fs_info->free_space_cache;
+       for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+               bytenr = btrfs_sb_offset(i);
+               ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
+                                      cache->key.objectid, bytenr, 0,
+                                      &logical, &nr, &stripe_len);
+               BUG_ON(ret);
+               while (nr--) {
+                       clear_extent_dirty(free_space_cache, logical[nr],
+                               logical[nr] + stripe_len - 1, GFP_NOFS);
+               }
+               kfree(logical);
+       }
+       return 0;
+}
 
 static int cache_block_group(struct btrfs_root *root,
                             struct btrfs_block_group_cache *block_group)
@@ -47,10 +96,8 @@ static int cache_block_group(struct btrfs_root *root,
        struct extent_buffer *leaf;
        struct extent_io_tree *free_space_cache;
        int slot;
-       u64 last = 0;
+       u64 last;
        u64 hole_size;
-       u64 first_free;
-       int found = 0;
 
        if (!block_group)
                return 0;
@@ -66,22 +113,15 @@ static int cache_block_group(struct btrfs_root *root,
                return -ENOMEM;
 
        path->reada = 2;
-       first_free = block_group->key.objectid;
-       key.objectid = block_group->key.objectid;
+       last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
+       key.objectid = last;
        key.offset = 0;
-       btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+       key.type = 0;
+
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0)
-               return ret;
-       ret = btrfs_previous_item(root, path, 0, BTRFS_EXTENT_ITEM_KEY);
-       if (ret < 0)
-               return ret;
-       if (ret == 0) {
-               leaf = path->nodes[0];
-               btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
-               if (key.objectid + key.offset > first_free)
-                       first_free = key.objectid + key.offset;
-       }
+               goto err;
+
        while(1) {
                leaf = path->nodes[0];
                slot = path->slots[0];
@@ -104,25 +144,23 @@ static int cache_block_group(struct btrfs_root *root,
                        break;
                }
 
-               if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
-                       if (!found) {
-                               last = first_free;
-                               found = 1;
-                       }
+               if (key.type == BTRFS_EXTENT_ITEM_KEY ||
+                   key.type == BTRFS_METADATA_ITEM_KEY) {
                        if (key.objectid > last) {
                                hole_size = key.objectid - last;
                                set_extent_dirty(free_space_cache, last,
                                                 last + hole_size - 1,
                                                 GFP_NOFS);
                        }
-                       last = key.objectid + key.offset;
+                       if (key.type == BTRFS_METADATA_ITEM_KEY)
+                               last = key.objectid + root->nodesize;
+                       else
+                               last = key.objectid + key.offset;
                }
 next:
                path->slots[0]++;
        }
 
-       if (!found)
-               last = first_free;
        if (block_group->key.objectid +
            block_group->key.offset > last) {
                hole_size = block_group->key.objectid +
@@ -130,12 +168,42 @@ next:
                set_extent_dirty(free_space_cache, last,
                                 last + hole_size - 1, GFP_NOFS);
        }
+       remove_sb_from_cache(root, block_group);
        block_group->cached = 1;
 err:
        btrfs_free_path(path);
        return 0;
 }
 
+struct btrfs_block_group_cache *btrfs_lookup_first_block_group(struct
+                                                      btrfs_fs_info *info,
+                                                      u64 bytenr)
+{
+       struct extent_io_tree *block_group_cache;
+       struct btrfs_block_group_cache *block_group = NULL;
+       u64 ptr;
+       u64 start;
+       u64 end;
+       int ret;
+
+       bytenr = max_t(u64, bytenr,
+                      BTRFS_SUPER_INFO_OFFSET + BTRFS_SUPER_INFO_SIZE);
+       block_group_cache = &info->block_group_cache;
+       ret = find_first_extent_bit(block_group_cache,
+                                   bytenr, &start, &end,
+                                   BLOCK_GROUP_DATA | BLOCK_GROUP_METADATA |
+                                   BLOCK_GROUP_SYSTEM);
+       if (ret) {
+               return NULL;
+       }
+       ret = get_state_private(block_group_cache, start, &ptr);
+       if (ret)
+               return NULL;
+
+       block_group = (struct btrfs_block_group_cache *)(unsigned long)ptr;
+       return block_group;
+}
+
 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
                                                         btrfs_fs_info *info,
                                                         u64 bytenr)
@@ -177,48 +245,43 @@ static int noinline find_search_start(struct btrfs_root *root,
 {
        int ret;
        struct btrfs_block_group_cache *cache = *cache_ret;
-       u64 last;
+       u64 last = *start_ret;
        u64 start = 0;
        u64 end = 0;
-       u64 cache_miss = 0;
        u64 search_start = *start_ret;
        int wrapped = 0;
 
-       if (!cache) {
+       if (!cache)
                goto out;
-       }
 again:
        ret = cache_block_group(root, cache);
        if (ret)
                goto out;
 
        last = max(search_start, cache->key.objectid);
-       if (!block_group_bits(cache, data)) {
+       if (cache->ro || !block_group_bits(cache, data))
                goto new_group;
-       }
 
        while(1) {
                ret = find_first_extent_bit(&root->fs_info->free_space_cache,
                                            last, &start, &end, EXTENT_DIRTY);
                if (ret) {
-                       if (!cache_miss)
-                               cache_miss = last;
                        goto new_group;
                }
 
                start = max(last, start);
                last = end + 1;
                if (last - start < num) {
-                       if (last == cache->key.objectid + cache->key.offset)
-                               cache_miss = start;
                        continue;
                }
-               if (start + num > cache->key.objectid + cache->key.offset)
+               if (start + num > cache->key.objectid + cache->key.offset) {
                        goto new_group;
+               }
                *start_ret = start;
                return 0;
        }
 out:
+       *start_ret = last;
        cache = btrfs_lookup_block_group(root->fs_info, search_start);
        if (!cache) {
                printk("Unable to find block group for %llu\n",
@@ -230,9 +293,8 @@ out:
 new_group:
        last = cache->key.objectid + cache->key.offset;
 wrapped:
-       cache = btrfs_lookup_block_group(root->fs_info, last);
+       cache = btrfs_lookup_first_block_group(root->fs_info, last);
        if (!cache) {
-no_cache:
                if (!wrapped) {
                        wrapped = 1;
                        last = search_start;
@@ -240,28 +302,10 @@ no_cache:
                }
                goto out;
        }
-       if (cache_miss && !cache->cached) {
-               cache_block_group(root, cache);
-               last = cache_miss;
-               cache = btrfs_lookup_block_group(root->fs_info, last);
-       }
-       cache = btrfs_find_block_group(root, cache, last, data, 0);
-       if (!cache)
-               goto no_cache;
        *cache_ret = cache;
-       cache_miss = 0;
        goto again;
 }
 
-static u64 div_factor(u64 num, int factor)
-{
-       if (factor == 10)
-               return num;
-       num *= factor;
-       num /= 10;
-       return num;
-}
-
 static int block_group_state_bits(u64 flags)
 {
        int bits = 0;
@@ -274,10 +318,9 @@ static int block_group_state_bits(u64 flags)
        return bits;
 }
 
-struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
-                                                struct btrfs_block_group_cache
-                                                *hint, u64 search_start,
-                                                int data, int owner)
+static struct btrfs_block_group_cache *
+btrfs_find_block_group(struct btrfs_root *root, struct btrfs_block_group_cache
+                      *hint, u64 search_start, int data, int owner)
 {
        struct btrfs_block_group_cache *cache;
        struct extent_io_tree *block_group_cache;
@@ -293,19 +336,19 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
        int bit;
        int ret;
        int full_search = 0;
-       int factor = 8;
+       int factor = 10;
 
        block_group_cache = &info->block_group_cache;
 
        if (!owner)
-               factor = 8;
+               factor = 10;
 
        bit = block_group_state_bits(data);
 
        if (search_start) {
                struct btrfs_block_group_cache *shint;
                shint = btrfs_lookup_block_group(info, search_start);
-               if (shint && block_group_bits(shint, data)) {
+               if (shint && !shint->ro && block_group_bits(shint, data)) {
                        used = btrfs_block_group_used(&shint->item);
                        if (used + shint->pinned <
                            div_factor(shint->key.offset, factor)) {
@@ -313,7 +356,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
                        }
                }
        }
-       if (hint && block_group_bits(hint, data)) {
+       if (hint && !hint->ro && block_group_bits(hint, data)) {
                used = btrfs_block_group_used(&hint->item);
                if (used + hint->pinned <
                    div_factor(hint->key.offset, factor)) {
@@ -344,7 +387,7 @@ again:
                last = cache->key.objectid + cache->key.offset;
                used = btrfs_block_group_used(&cache->item);
 
-               if (block_group_bits(cache, data)) {
+               if (!cache->ro && block_group_bits(cache, data)) {
                        if (full_search)
                                free_check = cache->key.offset;
                        else
@@ -367,108 +410,6 @@ found:
        return found_group;
 }
 
-static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation,
-                          u64 owner, u64 owner_offset)
-{
-       u32 high_crc = ~(u32)0;
-       u32 low_crc = ~(u32)0;
-       __le64 lenum;
-
-       lenum = cpu_to_le64(root_objectid);
-       high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
-       lenum = cpu_to_le64(ref_generation);
-       low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
-       if (owner >= BTRFS_FIRST_FREE_OBJECTID) {
-               lenum = cpu_to_le64(owner);
-               low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
-               lenum = cpu_to_le64(owner_offset);
-               low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
-       }
-       return ((u64)high_crc << 32) | (u64)low_crc;
-}
-
-static int match_extent_ref(struct extent_buffer *leaf,
-                           struct btrfs_extent_ref *disk_ref,
-                           struct btrfs_extent_ref *cpu_ref)
-{
-       int ret;
-       int len;
-
-       if (cpu_ref->objectid)
-               len = sizeof(*cpu_ref);
-       else
-               len = 2 * sizeof(u64);
-       ret = memcmp_extent_buffer(leaf, cpu_ref, (unsigned long)disk_ref,
-                                  len);
-       return ret == 0;
-}
-
-static int noinline lookup_extent_backref(struct btrfs_trans_handle *trans,
-                                         struct btrfs_root *root,
-                                         struct btrfs_path *path, u64 bytenr,
-                                         u64 root_objectid,
-                                         u64 ref_generation, u64 owner,
-                                         u64 owner_offset, int del)
-{
-       u64 hash;
-       struct btrfs_key key;
-       struct btrfs_key found_key;
-       struct btrfs_extent_ref ref;
-       struct extent_buffer *leaf;
-       struct btrfs_extent_ref *disk_ref;
-       int ret;
-       int ret2;
-
-       btrfs_set_stack_ref_root(&ref, root_objectid);
-       btrfs_set_stack_ref_generation(&ref, ref_generation);
-       btrfs_set_stack_ref_objectid(&ref, owner);
-       btrfs_set_stack_ref_offset(&ref, owner_offset);
-
-       hash = hash_extent_ref(root_objectid, ref_generation, owner,
-                              owner_offset);
-       key.offset = hash;
-       key.objectid = bytenr;
-       key.type = BTRFS_EXTENT_REF_KEY;
-
-       while (1) {
-               ret = btrfs_search_slot(trans, root, &key, path,
-                                       del ? -1 : 0, del);
-               if (ret < 0)
-                       goto out;
-               leaf = path->nodes[0];
-               if (ret != 0) {
-                       u32 nritems = btrfs_header_nritems(leaf);
-                       if (path->slots[0] >= nritems) {
-                               ret2 = btrfs_next_leaf(root, path);
-                               if (ret2)
-                                       goto out;
-                               leaf = path->nodes[0];
-                       }
-                       btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-                       if (found_key.objectid != bytenr ||
-                           found_key.type != BTRFS_EXTENT_REF_KEY)
-                               goto out;
-                       key.offset = found_key.offset;
-                       if (del) {
-                               btrfs_release_path(root, path);
-                               continue;
-                       }
-               }
-               disk_ref = btrfs_item_ptr(path->nodes[0],
-                                         path->slots[0],
-                                         struct btrfs_extent_ref);
-               if (match_extent_ref(path->nodes[0], disk_ref, &ref)) {
-                       ret = 0;
-                       goto out;
-               }
-               btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-               key.offset = found_key.offset + 1;
-               btrfs_release_path(root, path);
-       }
-out:
-       return ret;
-}
-
 /*
  * Back reference rules.  Back refs have three main goals:
  *
@@ -483,1354 +424,2446 @@ out:
  *    maintenance.  This is actually the same as #2, but with a slightly
  *    different use case.
  *
- * File extents can be referenced by:
+ * There are two kinds of back refs. The implicit back refs is optimized
+ * for pointers in non-shared tree blocks. For a given pointer in a block,
+ * back refs of this kind provide information about the block's owner tree
+ * and the pointer's key. These information allow us to find the block by
+ * b-tree searching. The full back refs is for pointers in tree blocks not
+ * referenced by their owner trees. The location of tree block is recorded
+ * in the back refs. Actually the full back refs is generic, and can be
+ * used in all cases the implicit back refs is used. The major shortcoming
+ * of the full back refs is its overhead. Every time a tree block gets
+ * COWed, we have to update back refs entry for all pointers in it.
  *
- * - multiple snapshots, subvolumes, or different generations in one subvol
- * - different files inside a single subvolume (in theory, not implemented yet)
- * - different offsets inside a file (bookend extents in file.c)
+ * For a newly allocated tree block, we use implicit back refs for
+ * pointers in it. This means most tree related operations only involve
+ * implicit back refs. For a tree block created in old transaction, the
+ * only way to drop a reference to it is COW it. So we can detect the
+ * event that tree block loses its owner tree's reference and do the
+ * back refs conversion.
  *
- * The extent ref structure has fields for:
+ * When a tree block is COW'd through a tree, there are four cases:
  *
- * - Objectid of the subvolume root
- * - Generation number of the tree holding the reference
- * - objectid of the file holding the reference
- * - offset in the file corresponding to the key holding the reference
+ * The reference count of the block is one and the tree is the block's
+ * owner tree. Nothing to do in this case.
  *
- * When a file extent is allocated the fields are filled in:
- *     (root_key.objectid, trans->transid, inode objectid, offset in file)
+ * The reference count of the block is one and the tree is not the
+ * block's owner tree. In this case, full back refs is used for pointers
+ * in the block. Remove these full back refs, add implicit back refs for
+ * every pointers in the new block.
  *
- * When a leaf is cow'd new references are added for every file extent found
- * in the leaf.  It looks the same as the create case, but trans->transid
- * will be different when the block is cow'd.
+ * The reference count of the block is greater than one and the tree is
+ * the block's owner tree. In this case, implicit back refs is used for
+ * pointers in the block. Add full back refs for every pointers in the
+ * block, increase lower level extents' reference counts. The original
+ * implicit back refs are entailed to the new block.
  *
- *     (root_key.objectid, trans->transid, inode objectid, offset in file)
+ * The reference count of the block is greater than one and the tree is
+ * not the block's owner tree. Add implicit back refs for every pointer in
+ * the new block, increase lower level extents' reference count.
  *
- * When a file extent is removed either during snapshot deletion or file
- * truncation, the corresponding back reference is found
- * by searching for:
+ * Back Reference Key composing:
  *
- *     (btrfs_header_owner(leaf), btrfs_header_generation(leaf),
- *      inode objectid, offset in file)
+ * The key objectid corresponds to the first byte in the extent,
+ * The key type is used to differentiate between types of back refs.
+ * There are different meanings of the key offset for different types
+ * of back refs.
  *
- * Btree extents can be referenced by:
+ * File extents can be referenced by:
  *
- * - Different subvolumes
- * - Different generations of the same subvolume
+ * - multiple snapshots, subvolumes, or different generations in one subvol
+ * - different files inside a single subvolume
+ * - different offsets inside a file (bookend extents in file.c)
+ *
+ * The extent ref structure for the implicit back refs has fields for:
  *
- * Storing sufficient information for a full reverse mapping of a btree
- * block would require storing the lowest key of the block in the backref,
- * and it would require updating that lowest key either before write out or
- * every time it changed.  Instead, the objectid of the lowest key is stored
- * along with the level of the tree block.  This provides a hint
- * about where in the btree the block can be found.  Searches through the
- * btree only need to look for a pointer to that block, so they stop one
- * level higher than the level recorded in the backref.
+ * - Objectid of the subvolume root
+ * - objectid of the file holding the reference
+ * - original offset in the file
+ * - how many bookend extents
+ *
+ * The key offset for the implicit back refs is hash of the first
+ * three fields.
+ *
+ * The extent ref structure for the full back refs has field for:
  *
- * Some btrees do not do reference counting on their extents.  These
- * include the extent tree and the tree of tree roots.  Backrefs for these
- * trees always have a generation of zero.
+ * - number of pointers in the tree leaf
  *
- * When a tree block is created, back references are inserted:
+ * The key offset for the implicit back refs is the first byte of
+ * the tree leaf
  *
- * (root->root_key.objectid, trans->transid or zero, level, lowest_key_objectid)
+ * When a file extent is allocated, The implicit back refs is used.
+ * the fields are filled in:
  *
- * When a tree block is cow'd in a reference counted root,
- * new back references are added for all the blocks it points to.
- * These are of the form (trans->transid will have increased since creation):
+ *     (root_key.objectid, inode objectid, offset in file, 1)
  *
- * (root->root_key.objectid, trans->transid, level, lowest_key_objectid)
+ * When a file extent is removed file truncation, we find the
+ * corresponding implicit back refs and check the following fields:
  *
- * Because the lowest_key_objectid and the level are just hints
- * they are not used when backrefs are deleted.  When a backref is deleted:
+ *     (btrfs_header_owner(leaf), inode objectid, offset in file)
  *
- * if backref was for a tree root:
- *     root_objectid = root->root_key.objectid
- * else
- *     root_objectid = btrfs_header_owner(parent)
+ * Btree extents can be referenced by:
  *
- * (root_objectid, btrfs_header_generation(parent) or zero, 0, 0)
+ * - Different subvolumes
  *
- * Back Reference Key hashing:
+ * Both the implicit back refs and the full back refs for tree blocks
+ * only consist of key. The key offset for the implicit back refs is
+ * objectid of block's owner tree. The key offset for the full back refs
+ * is the first byte of parent block.
  *
- * Back references have four fields, each 64 bits long.  Unfortunately,
- * This is hashed into a single 64 bit number and placed into the key offset.
- * The key objectid corresponds to the first byte in the extent, and the
- * key type is set to BTRFS_EXTENT_REF_KEY
+ * When implicit back refs is used, information about the lowest key and
+ * level of the tree block are required. These information are stored in
+ * tree block info structure.
  */
-int btrfs_insert_extent_backref(struct btrfs_trans_handle *trans,
-                                struct btrfs_root *root,
-                                struct btrfs_path *path, u64 bytenr,
-                                u64 root_objectid, u64 ref_generation,
-                                u64 owner, u64 owner_offset)
+
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+static int convert_extent_item_v0(struct btrfs_trans_handle *trans,
+                                 struct btrfs_root *root,
+                                 struct btrfs_path *path,
+                                 u64 owner, u32 extra_size)
 {
-       u64 hash;
+       struct btrfs_extent_item *item;
+       struct btrfs_extent_item_v0 *ei0;
+       struct btrfs_extent_ref_v0 *ref0;
+       struct btrfs_tree_block_info *bi;
+       struct extent_buffer *leaf;
        struct btrfs_key key;
-       struct btrfs_extent_ref ref;
-       struct btrfs_extent_ref *disk_ref;
+       struct btrfs_key found_key;
+       u32 new_size = sizeof(*item);
+       u64 refs;
        int ret;
 
-       btrfs_set_stack_ref_root(&ref, root_objectid);
-       btrfs_set_stack_ref_generation(&ref, ref_generation);
-       btrfs_set_stack_ref_objectid(&ref, owner);
-       btrfs_set_stack_ref_offset(&ref, owner_offset);
-
-       hash = hash_extent_ref(root_objectid, ref_generation, owner,
-                              owner_offset);
-       key.offset = hash;
-       key.objectid = bytenr;
-       key.type = BTRFS_EXTENT_REF_KEY;
-
-       ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(ref));
-       while (ret == -EEXIST) {
-               disk_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
-                                         struct btrfs_extent_ref);
-               if (match_extent_ref(path->nodes[0], disk_ref, &ref))
-                       goto out;
-               key.offset++;
-               btrfs_release_path(root, path);
-               ret = btrfs_insert_empty_item(trans, root, path, &key,
-                                             sizeof(ref));
+       leaf = path->nodes[0];
+       BUG_ON(btrfs_item_size_nr(leaf, path->slots[0]) != sizeof(*ei0));
+
+       btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+       ei0 = btrfs_item_ptr(leaf, path->slots[0],
+                            struct btrfs_extent_item_v0);
+       refs = btrfs_extent_refs_v0(leaf, ei0);
+
+       if (owner == (u64)-1) {
+               while (1) {
+                       if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+                               ret = btrfs_next_leaf(root, path);
+                               if (ret < 0)
+                                       return ret;
+                               BUG_ON(ret > 0);
+                               leaf = path->nodes[0];
+                       }
+                       btrfs_item_key_to_cpu(leaf, &found_key,
+                                             path->slots[0]);
+                       BUG_ON(key.objectid != found_key.objectid);
+                       if (found_key.type != BTRFS_EXTENT_REF_V0_KEY) {
+                               path->slots[0]++;
+                               continue;
+                       }
+                       ref0 = btrfs_item_ptr(leaf, path->slots[0],
+                                             struct btrfs_extent_ref_v0);
+                       owner = btrfs_ref_objectid_v0(leaf, ref0);
+                       break;
+               }
        }
-       if (ret)
-               goto out;
-       disk_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
-                                 struct btrfs_extent_ref);
-       write_extent_buffer(path->nodes[0], &ref, (unsigned long)disk_ref,
-                           sizeof(ref));
-       btrfs_mark_buffer_dirty(path->nodes[0]);
-out:
-       btrfs_release_path(root, path);
-       return ret;
-}
-
-int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
-                               struct btrfs_root *root,
-                               u64 bytenr, u64 num_bytes,
-                               u64 root_objectid, u64 ref_generation,
-                               u64 owner, u64 owner_offset)
-{
-       struct btrfs_path *path;
-       int ret;
-       struct btrfs_key key;
-       struct extent_buffer *l;
-       struct btrfs_extent_item *item;
-       u32 refs;
+       btrfs_release_path(path);
 
-       WARN_ON(num_bytes < root->sectorsize);
-       path = btrfs_alloc_path();
-       if (!path)
-               return -ENOMEM;
+       if (owner < BTRFS_FIRST_FREE_OBJECTID)
+               new_size += sizeof(*bi);
 
-       key.objectid = bytenr;
-       btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-       key.offset = num_bytes;
-       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
-                               0, 1);
+       new_size -= sizeof(*ei0);
+       ret = btrfs_search_slot(trans, root, &key, path, new_size, 1);
        if (ret < 0)
                return ret;
-       if (ret != 0) {
-               BUG();
-       }
-       BUG_ON(ret != 0);
-       l = path->nodes[0];
-       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
-       refs = btrfs_extent_refs(l, item);
-       btrfs_set_extent_refs(l, item, refs + 1);
-       btrfs_mark_buffer_dirty(path->nodes[0]);
-
-       btrfs_release_path(root->fs_info->extent_root, path);
+       BUG_ON(ret);
 
-       ret = btrfs_insert_extent_backref(trans, root->fs_info->extent_root,
-                                         path, bytenr, root_objectid,
-                                         ref_generation, owner, owner_offset);
+       ret = btrfs_extend_item(trans, root, path, new_size);
        BUG_ON(ret);
-       finish_current_insert(trans, root->fs_info->extent_root);
-       del_pending_extents(trans, root->fs_info->extent_root);
 
-       btrfs_free_path(path);
+       leaf = path->nodes[0];
+       item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+       btrfs_set_extent_refs(leaf, item, refs);
+       /* FIXME: get real generation */
+       btrfs_set_extent_generation(leaf, item, 0);
+       if (owner < BTRFS_FIRST_FREE_OBJECTID) {
+               btrfs_set_extent_flags(leaf, item,
+                                      BTRFS_EXTENT_FLAG_TREE_BLOCK |
+                                      BTRFS_BLOCK_FLAG_FULL_BACKREF);
+               bi = (struct btrfs_tree_block_info *)(item + 1);
+               /* FIXME: get first key of the block */
+               memset_extent_buffer(leaf, 0, (unsigned long)bi, sizeof(*bi));
+               btrfs_set_tree_block_level(leaf, bi, (int)owner);
+       } else {
+               btrfs_set_extent_flags(leaf, item, BTRFS_EXTENT_FLAG_DATA);
+       }
+       btrfs_mark_buffer_dirty(leaf);
        return 0;
 }
+#endif
 
-int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
-                        struct btrfs_root *root)
+u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset)
 {
-       finish_current_insert(trans, root->fs_info->extent_root);
-       del_pending_extents(trans, root->fs_info->extent_root);
-       return 0;
+       u32 high_crc = ~(u32)0;
+       u32 low_crc = ~(u32)0;
+       __le64 lenum;
+
+       lenum = cpu_to_le64(root_objectid);
+       high_crc = btrfs_crc32c(high_crc, &lenum, sizeof(lenum));
+       lenum = cpu_to_le64(owner);
+       low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
+       lenum = cpu_to_le64(offset);
+       low_crc = btrfs_crc32c(low_crc, &lenum, sizeof(lenum));
+
+       return ((u64)high_crc << 31) ^ (u64)low_crc;
 }
 
-static int lookup_extent_ref(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root, u64 bytenr,
-                            u64 num_bytes, u32 *refs)
+static u64 hash_extent_data_ref_item(struct extent_buffer *leaf,
+                                    struct btrfs_extent_data_ref *ref)
 {
-       struct btrfs_path *path;
-       int ret;
-       struct btrfs_key key;
-       struct extent_buffer *l;
-       struct btrfs_extent_item *item;
+       return hash_extent_data_ref(btrfs_extent_data_ref_root(leaf, ref),
+                                   btrfs_extent_data_ref_objectid(leaf, ref),
+                                   btrfs_extent_data_ref_offset(leaf, ref));
+}
 
-       WARN_ON(num_bytes < root->sectorsize);
-       path = btrfs_alloc_path();
-       key.objectid = bytenr;
-       key.offset = num_bytes;
-       btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
-                               0, 0);
-       if (ret < 0)
-               goto out;
-       if (ret != 0) {
-               btrfs_print_leaf(root, path->nodes[0]);
-               printk("failed to find block number %llu\n",
-                       (unsigned long long)bytenr);
-               BUG();
-       }
-       l = path->nodes[0];
-       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
-       *refs = btrfs_extent_refs(l, item);
-out:
-       btrfs_free_path(path);
-       return 0;
+static int match_extent_data_ref(struct extent_buffer *leaf,
+                                struct btrfs_extent_data_ref *ref,
+                                u64 root_objectid, u64 owner, u64 offset)
+{
+       if (btrfs_extent_data_ref_root(leaf, ref) != root_objectid ||
+           btrfs_extent_data_ref_objectid(leaf, ref) != owner ||
+           btrfs_extent_data_ref_offset(leaf, ref) != offset)
+               return 0;
+       return 1;
 }
 
-u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
-                                 struct btrfs_path *count_path,
-                                 u64 first_extent)
+static noinline int lookup_extent_data_ref(struct btrfs_trans_handle *trans,
+                                          struct btrfs_root *root,
+                                          struct btrfs_path *path,
+                                          u64 bytenr, u64 parent,
+                                          u64 root_objectid,
+                                          u64 owner, u64 offset)
 {
-       struct btrfs_root *extent_root = root->fs_info->extent_root;
-       struct btrfs_path *path;
-       u64 bytenr;
-       u64 found_objectid;
-       u64 root_objectid = root->root_key.objectid;
-       u32 total_count = 0;
-       u32 cur_count;
-       u32 refs;
+       struct btrfs_key key;
+       struct btrfs_extent_data_ref *ref;
+       struct extent_buffer *leaf;
        u32 nritems;
        int ret;
-       struct btrfs_key key;
-       struct btrfs_key found_key;
-       struct extent_buffer *l;
-       struct btrfs_extent_item *item;
-       struct btrfs_extent_ref *ref_item;
-       int level = -1;
-
-       path = btrfs_alloc_path();
-again:
-       if (level == -1)
-               bytenr = first_extent;
-       else
-               bytenr = count_path->nodes[level]->start;
+       int recow;
+       int err = -ENOENT;
 
-       cur_count = 0;
        key.objectid = bytenr;
-       key.offset = 0;
-
-       btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-       ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
-       if (ret < 0)
-               goto out;
-       BUG_ON(ret == 0);
-
-       l = path->nodes[0];
-       btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
-
-       if (found_key.objectid != bytenr ||
-           found_key.type != BTRFS_EXTENT_ITEM_KEY) {
-               goto out;
+       if (parent) {
+               key.type = BTRFS_SHARED_DATA_REF_KEY;
+               key.offset = parent;
+       } else {
+               key.type = BTRFS_EXTENT_DATA_REF_KEY;
+               key.offset = hash_extent_data_ref(root_objectid,
+                                                 owner, offset);
+       }
+again:
+       recow = 0;
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret < 0) {
+               err = ret;
+               goto fail;
        }
 
-       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
-       refs = btrfs_extent_refs(l, item);
-       while (1) {
-               nritems = btrfs_header_nritems(l);
-               if (path->slots[0] >= nritems) {
-                       ret = btrfs_next_leaf(extent_root, path);
-                       if (ret == 0)
-                               continue;
-                       break;
-               }
-               btrfs_item_key_to_cpu(l, &found_key, path->slots[0]);
-               if (found_key.objectid != bytenr)
-                       break;
-               if (found_key.type != BTRFS_EXTENT_REF_KEY) {
-                       path->slots[0]++;
-                       continue;
+       if (parent) {
+               if (!ret)
+                       return 0;
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+               key.type = BTRFS_EXTENT_REF_V0_KEY;
+               btrfs_release_path(path);
+               ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+               if (ret < 0) {
+                       err = ret;
+                       goto fail;
                }
+               if (!ret)
+                       return 0;
+#endif
+               goto fail;
+       }
 
-               cur_count++;
-               ref_item = btrfs_item_ptr(l, path->slots[0],
-                                         struct btrfs_extent_ref);
-               found_objectid = btrfs_ref_root(l, ref_item);
+       leaf = path->nodes[0];
+       nritems = btrfs_header_nritems(leaf);
+       while (1) {
+               if (path->slots[0] >= nritems) {
+                       ret = btrfs_next_leaf(root, path);
+                       if (ret < 0)
+                               err = ret;
+                       if (ret)
+                               goto fail;
 
-               if (found_objectid != root_objectid) {
-                       total_count = 2;
-                       goto out;
+                       leaf = path->nodes[0];
+                       nritems = btrfs_header_nritems(leaf);
+                       recow = 1;
                }
-               total_count = 1;
-               path->slots[0]++;
-       }
-       if (cur_count == 0) {
-               total_count = 0;
-               goto out;
-       }
-       if (level >= 0 && root->node == count_path->nodes[level])
-               goto out;
-       level++;
-       btrfs_release_path(root, path);
-       goto again;
 
-out:
-       btrfs_free_path(path);
-       return total_count;
-}
-int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
-                      struct btrfs_root *root, u64 owner_objectid)
-{
-       u64 generation;
-       u64 key_objectid;
-       u64 level;
-       u32 nritems;
-       struct btrfs_disk_key disk_key;
-
-       level = btrfs_header_level(root->node);
-       generation = trans->transid;
-       nritems = btrfs_header_nritems(root->node);
-       if (nritems > 0) {
-               if (level == 0)
-                       btrfs_item_key(root->node, &disk_key, 0);
-               else
-                       btrfs_node_key(root->node, &disk_key, 0);
-               key_objectid = btrfs_disk_key_objectid(&disk_key);
-       } else {
-               key_objectid = 0;
+               btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+               if (key.objectid != bytenr ||
+                   key.type != BTRFS_EXTENT_DATA_REF_KEY)
+                       goto fail;
+               
+               ref = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_extent_data_ref);
+
+               if (match_extent_data_ref(leaf, ref, root_objectid,
+                                         owner, offset)) {
+                       if (recow) {
+                               btrfs_release_path(path);
+                               goto again;
+                       }
+                       err = 0;
+                       break;
+               }
+               path->slots[0]++;
        }
-       return btrfs_inc_extent_ref(trans, root, root->node->start,
-                                   root->node->len, owner_objectid,
-                                   generation, level, key_objectid);
+fail:
+       return err;
 }
 
-int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
-                 struct extent_buffer *buf)
+static noinline int insert_extent_data_ref(struct btrfs_trans_handle *trans,
+                                          struct btrfs_root *root,
+                                          struct btrfs_path *path,
+                                          u64 bytenr, u64 parent,
+                                          u64 root_objectid, u64 owner,
+                                          u64 offset, int refs_to_add)
 {
-       u64 bytenr;
-       u32 nritems;
        struct btrfs_key key;
-       struct btrfs_file_extent_item *fi;
-       int i;
-       int level;
+       struct extent_buffer *leaf;
+       u32 size;
+       u32 num_refs;
        int ret;
-       int faili;
 
-       if (!root->ref_cows)
-               return 0;
+       key.objectid = bytenr;
+       if (parent) {
+               key.type = BTRFS_SHARED_DATA_REF_KEY;
+               key.offset = parent;
+               size = sizeof(struct btrfs_shared_data_ref);
+       } else {
+               key.type = BTRFS_EXTENT_DATA_REF_KEY;
+               key.offset = hash_extent_data_ref(root_objectid,
+                                                 owner, offset);
+               size = sizeof(struct btrfs_extent_data_ref);
+       }
 
-       level = btrfs_header_level(buf);
-       nritems = btrfs_header_nritems(buf);
-       for (i = 0; i < nritems; i++) {
-               if (level == 0) {
-                       u64 disk_bytenr;
-                       btrfs_item_key_to_cpu(buf, &key, i);
-                       if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
-                               continue;
-                       fi = btrfs_item_ptr(buf, i,
-                                           struct btrfs_file_extent_item);
-                       if (btrfs_file_extent_type(buf, fi) ==
-                           BTRFS_FILE_EXTENT_INLINE)
-                               continue;
-                       disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
-                       if (disk_bytenr == 0)
-                               continue;
-                       ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
-                                   btrfs_file_extent_disk_num_bytes(buf, fi),
-                                   root->root_key.objectid, trans->transid,
-                                   key.objectid, key.offset);
-                       if (ret) {
-                               faili = i;
-                               goto fail;
-                       }
+       ret = btrfs_insert_empty_item(trans, root, path, &key, size);
+       if (ret && ret != -EEXIST)
+               goto fail;
+
+       leaf = path->nodes[0];
+       if (parent) {
+               struct btrfs_shared_data_ref *ref;
+               ref = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_shared_data_ref);
+               if (ret == 0) {
+                       btrfs_set_shared_data_ref_count(leaf, ref, refs_to_add);
                } else {
-                       bytenr = btrfs_node_blockptr(buf, i);
-                       btrfs_node_key_to_cpu(buf, &key, i);
-                       ret = btrfs_inc_extent_ref(trans, root, bytenr,
-                                          btrfs_level_size(root, level - 1),
-                                          root->root_key.objectid,
-                                          trans->transid,
-                                          level - 1, key.objectid);
-                       if (ret) {
-                               faili = i;
+                       num_refs = btrfs_shared_data_ref_count(leaf, ref);
+                       num_refs += refs_to_add;
+                       btrfs_set_shared_data_ref_count(leaf, ref, num_refs);
+               }
+       } else {
+               struct btrfs_extent_data_ref *ref;
+               while (ret == -EEXIST) {
+                       ref = btrfs_item_ptr(leaf, path->slots[0],
+                                            struct btrfs_extent_data_ref);
+                       if (match_extent_data_ref(leaf, ref, root_objectid,
+                                                 owner, offset))
+                               break;
+                       btrfs_release_path(path);
+
+                       key.offset++;
+                       ret = btrfs_insert_empty_item(trans, root, path, &key,
+                                                     size);
+                       if (ret && ret != -EEXIST)
                                goto fail;
-                       }
+
+                       leaf = path->nodes[0];
                }
-       }
-       return 0;
-fail:
-       WARN_ON(1);
-#if 0
-       for (i =0; i < faili; i++) {
-               if (level == 0) {
-                       u64 disk_bytenr;
-                       btrfs_item_key_to_cpu(buf, &key, i);
-                       if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
-                               continue;
-                       fi = btrfs_item_ptr(buf, i,
-                                           struct btrfs_file_extent_item);
-                       if (btrfs_file_extent_type(buf, fi) ==
-                           BTRFS_FILE_EXTENT_INLINE)
-                               continue;
-                       disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
-                       if (disk_bytenr == 0)
-                               continue;
-                       err = btrfs_free_extent(trans, root, disk_bytenr,
-                                   btrfs_file_extent_disk_num_bytes(buf,
-                                                                     fi), 0);
-                       BUG_ON(err);
+               ref = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_extent_data_ref);
+               if (ret == 0) {
+                       btrfs_set_extent_data_ref_root(leaf, ref,
+                                                      root_objectid);
+                       btrfs_set_extent_data_ref_objectid(leaf, ref, owner);
+                       btrfs_set_extent_data_ref_offset(leaf, ref, offset);
+                       btrfs_set_extent_data_ref_count(leaf, ref, refs_to_add);
                } else {
-                       bytenr = btrfs_node_blockptr(buf, i);
-                       err = btrfs_free_extent(trans, root, bytenr,
-                                       btrfs_level_size(root, level - 1), 0);
-                       BUG_ON(err);
+                       num_refs = btrfs_extent_data_ref_count(leaf, ref);
+                       num_refs += refs_to_add;
+                       btrfs_set_extent_data_ref_count(leaf, ref, num_refs);
                }
        }
-#endif
+       btrfs_mark_buffer_dirty(leaf);
+       ret = 0;
+fail:
+       btrfs_release_path(path);
        return ret;
 }
 
-static int write_one_cache_group(struct btrfs_trans_handle *trans,
-                                struct btrfs_root *root,
-                                struct btrfs_path *path,
-                                struct btrfs_block_group_cache *cache)
+static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
+                                          struct btrfs_root *root,
+                                          struct btrfs_path *path,
+                                          int refs_to_drop)
 {
-       int ret;
-       int pending_ret;
-       struct btrfs_root *extent_root = root->fs_info->extent_root;
-       unsigned long bi;
+       struct btrfs_key key;
+       struct btrfs_extent_data_ref *ref1 = NULL;
+       struct btrfs_shared_data_ref *ref2 = NULL;
        struct extent_buffer *leaf;
-
-       ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
-       if (ret < 0)
-               goto fail;
-       BUG_ON(ret);
+       u32 num_refs = 0;
+       int ret = 0;
 
        leaf = path->nodes[0];
-       bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
-       write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
-       btrfs_mark_buffer_dirty(leaf);
-       btrfs_release_path(extent_root, path);
-fail:
-       finish_current_insert(trans, extent_root);
-       pending_ret = del_pending_extents(trans, extent_root);
-       if (ret)
-               return ret;
-       if (pending_ret)
-               return pending_ret;
-       return 0;
+       btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+       if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
+               ref1 = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_extent_data_ref);
+               num_refs = btrfs_extent_data_ref_count(leaf, ref1);
+       } else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
+               ref2 = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_shared_data_ref);
+               num_refs = btrfs_shared_data_ref_count(leaf, ref2);
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+       } else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
+               struct btrfs_extent_ref_v0 *ref0;
+               ref0 = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_extent_ref_v0);
+               num_refs = btrfs_ref_count_v0(leaf, ref0);
+#endif
+       } else {
+               BUG();
+       }
+
+       BUG_ON(num_refs < refs_to_drop);
+       num_refs -= refs_to_drop;
 
+       if (num_refs == 0) {
+               ret = btrfs_del_item(trans, root, path);
+       } else {
+               if (key.type == BTRFS_EXTENT_DATA_REF_KEY)
+                       btrfs_set_extent_data_ref_count(leaf, ref1, num_refs);
+               else if (key.type == BTRFS_SHARED_DATA_REF_KEY)
+                       btrfs_set_shared_data_ref_count(leaf, ref2, num_refs);
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+               else {
+                       struct btrfs_extent_ref_v0 *ref0;
+                       ref0 = btrfs_item_ptr(leaf, path->slots[0],
+                                       struct btrfs_extent_ref_v0);
+                       btrfs_set_ref_count_v0(leaf, ref0, num_refs);
+               }
+#endif
+               btrfs_mark_buffer_dirty(leaf);
+       }
+       return ret;
 }
 
-int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
-                                  struct btrfs_root *root)
+static noinline u32 extent_data_ref_count(struct btrfs_root *root,
+                                         struct btrfs_path *path,
+                                         struct btrfs_extent_inline_ref *iref)
 {
-       struct extent_io_tree *block_group_cache;
-       struct btrfs_block_group_cache *cache;
-       int ret;
-       int err = 0;
-       int werr = 0;
-       struct btrfs_path *path;
-       u64 last = 0;
-       u64 start;
-       u64 end;
-       u64 ptr;
-
-       block_group_cache = &root->fs_info->block_group_cache;
-       path = btrfs_alloc_path();
-       if (!path)
-               return -ENOMEM;
-
-       while(1) {
-               ret = find_first_extent_bit(block_group_cache, last,
-                                           &start, &end, BLOCK_GROUP_DIRTY);
-               if (ret)
-                       break;
+       struct btrfs_key key;
+       struct extent_buffer *leaf;
+       struct btrfs_extent_data_ref *ref1;
+       struct btrfs_shared_data_ref *ref2;
+       u32 num_refs = 0;
 
-               last = end + 1;
-               ret = get_state_private(block_group_cache, start, &ptr);
-               if (ret)
-                       break;
-               cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
-               err = write_one_cache_group(trans, root,
-                                           path, cache);
-               /*
-                * if we fail to write the cache group, we want
-                * to keep it marked dirty in hopes that a later
-                * write will work
-                */
-               if (err) {
-                       werr = err;
-                       continue;
+       leaf = path->nodes[0];
+       btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+       if (iref) {
+               if (btrfs_extent_inline_ref_type(leaf, iref) ==
+                   BTRFS_EXTENT_DATA_REF_KEY) {
+                       ref1 = (struct btrfs_extent_data_ref *)(&iref->offset);
+                       num_refs = btrfs_extent_data_ref_count(leaf, ref1);
+               } else {
+                       ref2 = (struct btrfs_shared_data_ref *)(iref + 1);
+                       num_refs = btrfs_shared_data_ref_count(leaf, ref2);
                }
-               clear_extent_bits(block_group_cache, start, end,
-                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
+       } else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
+               ref1 = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_extent_data_ref);
+               num_refs = btrfs_extent_data_ref_count(leaf, ref1);
+       } else if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
+               ref2 = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_shared_data_ref);
+               num_refs = btrfs_shared_data_ref_count(leaf, ref2);
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+       } else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
+               struct btrfs_extent_ref_v0 *ref0;
+               ref0 = btrfs_item_ptr(leaf, path->slots[0],
+                                     struct btrfs_extent_ref_v0);
+               num_refs = btrfs_ref_count_v0(leaf, ref0);
+#endif
+       } else {
+               BUG();
        }
-       btrfs_free_path(path);
-       return werr;
+       return num_refs;
 }
 
-static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
-                                                 u64 flags)
+static noinline int lookup_tree_block_ref(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root,
+                                         struct btrfs_path *path,
+                                         u64 bytenr, u64 parent,
+                                         u64 root_objectid)
 {
-       struct list_head *head = &info->space_info;
-       struct list_head *cur;
-       struct btrfs_space_info *found;
-       list_for_each(cur, head) {
-               found = list_entry(cur, struct btrfs_space_info, list);
-               if (found->flags == flags)
-                       return found;
+       struct btrfs_key key;
+       int ret;
+
+       key.objectid = bytenr;
+       if (parent) {
+               key.type = BTRFS_SHARED_BLOCK_REF_KEY;
+               key.offset = parent;
+       } else {
+               key.type = BTRFS_TREE_BLOCK_REF_KEY;
+               key.offset = root_objectid;
        }
-       return NULL;
 
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret > 0)
+               ret = -ENOENT;
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+       if (ret == -ENOENT && parent) {
+               btrfs_release_path(path);
+               key.type = BTRFS_EXTENT_REF_V0_KEY;
+               ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+               if (ret > 0)
+                       ret = -ENOENT;
+       }
+#endif
+       return ret;
 }
 
-static int update_space_info(struct btrfs_fs_info *info, u64 flags,
-                            u64 total_bytes, u64 bytes_used,
-                            struct btrfs_space_info **space_info)
+static noinline int insert_tree_block_ref(struct btrfs_trans_handle *trans,
+                                         struct btrfs_root *root,
+                                         struct btrfs_path *path,
+                                         u64 bytenr, u64 parent,
+                                         u64 root_objectid)
 {
-       struct btrfs_space_info *found;
+       struct btrfs_key key;
+       int ret;
 
-       found = __find_space_info(info, flags);
-       if (found) {
-               found->total_bytes += total_bytes;
-               found->bytes_used += bytes_used;
-               WARN_ON(found->total_bytes < found->bytes_used);
-               *space_info = found;
-               return 0;
+       key.objectid = bytenr;
+       if (parent) {
+               key.type = BTRFS_SHARED_BLOCK_REF_KEY;
+               key.offset = parent;
+       } else {
+               key.type = BTRFS_TREE_BLOCK_REF_KEY;
+               key.offset = root_objectid;
        }
-       found = kmalloc(sizeof(*found), GFP_NOFS);
-       if (!found)
-               return -ENOMEM;
 
-       list_add(&found->list, &info->space_info);
-       found->flags = flags;
-       found->total_bytes = total_bytes;
-       found->bytes_used = bytes_used;
-       found->bytes_pinned = 0;
-       found->full = 0;
-       *space_info = found;
-       return 0;
-}
+       ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
 
+       btrfs_release_path(path);
+       return ret;
+}
 
-static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
+static inline int extent_ref_type(u64 parent, u64 owner)
 {
-       u64 extra_flags = flags & (BTRFS_BLOCK_GROUP_RAID0 |
-                                  BTRFS_BLOCK_GROUP_RAID1 |
-                                  BTRFS_BLOCK_GROUP_DUP);
-       if (extra_flags) {
-               if (flags & BTRFS_BLOCK_GROUP_DATA)
-                       fs_info->avail_data_alloc_bits |= extra_flags;
-               if (flags & BTRFS_BLOCK_GROUP_METADATA)
-                       fs_info->avail_metadata_alloc_bits |= extra_flags;
-               if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
-                       fs_info->avail_system_alloc_bits |= extra_flags;
+       int type;
+       if (owner < BTRFS_FIRST_FREE_OBJECTID) {
+               if (parent > 0)
+                       type = BTRFS_SHARED_BLOCK_REF_KEY;
+               else
+                       type = BTRFS_TREE_BLOCK_REF_KEY;
+       } else {
+               if (parent > 0)
+                       type = BTRFS_SHARED_DATA_REF_KEY;
+               else
+                       type = BTRFS_EXTENT_DATA_REF_KEY;
        }
+       return type;
 }
 
-static int do_chunk_alloc(struct btrfs_trans_handle *trans,
-                         struct btrfs_root *extent_root, u64 alloc_bytes,
-                         u64 flags)
+static int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                struct btrfs_extent_inline_ref **ref_ret,
+                                u64 bytenr, u64 num_bytes,
+                                u64 parent, u64 root_objectid,
+                                u64 owner, u64 offset, int insert)
 {
-       struct btrfs_space_info *space_info;
-       u64 thresh;
-       u64 start;
-       u64 num_bytes;
+       struct btrfs_key key;
+       struct extent_buffer *leaf;
+       struct btrfs_extent_item *ei;
+       struct btrfs_extent_inline_ref *iref;
+       u64 flags;
+       u32 item_size;
+       unsigned long ptr;
+       unsigned long end;
+       int extra_size;
+       int type;
+       int want;
        int ret;
+       int err = 0;
+       int skinny_metadata =
+               btrfs_fs_incompat(root->fs_info,
+                                 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);
 
-       space_info = __find_space_info(extent_root->fs_info, flags);
-       if (!space_info) {
-               ret = update_space_info(extent_root->fs_info, flags,
-                                       0, 0, &space_info);
-               BUG_ON(ret);
-       }
-       BUG_ON(!space_info);
+       key.objectid = bytenr;
+       key.type = BTRFS_EXTENT_ITEM_KEY;
+       key.offset = num_bytes;
 
-       if (space_info->full)
-               return 0;
+       want = extent_ref_type(parent, owner);
+       if (insert)
+               extra_size = btrfs_extent_inline_ref_size(want);
+       else
+               extra_size = -1;
+
+       if (owner < BTRFS_FIRST_FREE_OBJECTID && skinny_metadata) {
+               skinny_metadata = 1;
+               key.type = BTRFS_METADATA_ITEM_KEY;
+               key.offset = owner;
+       } else if (skinny_metadata) {
+               skinny_metadata = 0;
+       }
 
-       thresh = div_factor(space_info->total_bytes, 7);
-       if ((space_info->bytes_used + space_info->bytes_pinned + alloc_bytes) <
-           thresh)
-               return 0;
+again:
+       ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
+       if (ret < 0) {
+               err = ret;
+               goto out;
+       }
 
-       ret = btrfs_alloc_chunk(trans, extent_root, &start, &num_bytes, flags);
-       if (ret == -ENOSPC) {
-               space_info->full = 1;
-               return 0;
+       /*
+        * We may be a newly converted file system which still has the old fat
+        * extent entries for metadata, so try and see if we have one of those.
+        */
+       if (ret > 0 && skinny_metadata) {
+               skinny_metadata = 0;
+               if (path->slots[0]) {
+                       path->slots[0]--;
+                       btrfs_item_key_to_cpu(path->nodes[0], &key,
+                                             path->slots[0]);
+                       if (key.objectid == bytenr &&
+                           key.type == BTRFS_EXTENT_ITEM_KEY &&
+                           key.offset == num_bytes)
+                               ret = 0;
+               }
+               if (ret) {
+                       key.type = BTRFS_EXTENT_ITEM_KEY;
+                       key.offset = num_bytes;
+                       btrfs_release_path(path);
+                       goto again;
+               }
        }
 
-       BUG_ON(ret);
+       if (ret) {
+               printf("Failed to find [%llu, %u, %llu]\n", key.objectid, key.type, key.offset);
+               return -ENOENT;
+       }
 
-       ret = btrfs_make_block_group(trans, extent_root, 0, flags,
-                    BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes);
        BUG_ON(ret);
-       return 0;
-}
 
-static int update_block_group(struct btrfs_trans_handle *trans,
-                             struct btrfs_root *root,
-                             u64 bytenr, u64 num_bytes, int alloc,
-                             int mark_free)
-{
-       struct btrfs_block_group_cache *cache;
-       struct btrfs_fs_info *info = root->fs_info;
-       u64 total = num_bytes;
-       u64 old_val;
-       u64 byte_in_group;
-       u64 start;
-       u64 end;
+       leaf = path->nodes[0];
+       item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+       if (item_size < sizeof(*ei)) {
+               if (!insert) {
+                       err = -ENOENT;
+                       goto out;
+               }
+               ret = convert_extent_item_v0(trans, root, path, owner,
+                                            extra_size);
+               if (ret < 0) {
+                       err = ret;
+                       goto out;
+               }
+               leaf = path->nodes[0];
+               item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+       }
+#endif
+       if (item_size < sizeof(*ei)) {
+               printf("Size is %u, needs to be %u, slot %d\n",
+                      (unsigned)item_size,
+                      (unsigned)sizeof(*ei), path->slots[0]);
+               btrfs_print_leaf(root, leaf);
+               return -EINVAL;
+       }
+       BUG_ON(item_size < sizeof(*ei));
 
-       while(total) {
-               cache = btrfs_lookup_block_group(info, bytenr);
-               if (!cache) {
-                       return -1;
+       ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+       flags = btrfs_extent_flags(leaf, ei);
+
+       ptr = (unsigned long)(ei + 1);
+       end = (unsigned long)ei + item_size;
+
+       if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK && !skinny_metadata) {
+               ptr += sizeof(struct btrfs_tree_block_info);
+               BUG_ON(ptr > end);
+       } else if (!(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
+               if (!(flags & BTRFS_EXTENT_FLAG_DATA)) {
+                       return -EIO;
                }
-               byte_in_group = bytenr - cache->key.objectid;
-               WARN_ON(byte_in_group > cache->key.offset);
-               start = cache->key.objectid;
-               end = start + cache->key.offset - 1;
-               set_extent_bits(&info->block_group_cache, start, end,
-                               BLOCK_GROUP_DIRTY, GFP_NOFS);
+       }
 
-               old_val = btrfs_block_group_used(&cache->item);
-               num_bytes = min(total, cache->key.offset - byte_in_group);
-               if (alloc) {
-                       old_val += num_bytes;
-                       cache->space_info->bytes_used += num_bytes;
+       err = -ENOENT;
+       while (1) {
+               if (ptr >= end) {
+                       WARN_ON(ptr > end);
+                       break;
+               }
+               iref = (struct btrfs_extent_inline_ref *)ptr;
+               type = btrfs_extent_inline_ref_type(leaf, iref);
+               if (want < type)
+                       break;
+               if (want > type) {
+                       ptr += btrfs_extent_inline_ref_size(type);
+                       continue;
+               }
+
+               if (type == BTRFS_EXTENT_DATA_REF_KEY) {
+                       struct btrfs_extent_data_ref *dref;
+                       dref = (struct btrfs_extent_data_ref *)(&iref->offset);
+                       if (match_extent_data_ref(leaf, dref, root_objectid,
+                                                 owner, offset)) {
+                               err = 0;
+                               break;
+                       }
+                       if (hash_extent_data_ref_item(leaf, dref) <
+                           hash_extent_data_ref(root_objectid, owner, offset))
+                               break;
                } else {
-                       old_val -= num_bytes;
-                       cache->space_info->bytes_used -= num_bytes;
-                       if (mark_free) {
-                               set_extent_dirty(&info->free_space_cache,
-                                                bytenr, bytenr + num_bytes - 1,
-                                                GFP_NOFS);
+                       u64 ref_offset;
+                       ref_offset = btrfs_extent_inline_ref_offset(leaf, iref);
+                       if (parent > 0) {
+                               if (parent == ref_offset) {
+                                       err = 0;
+                                       break;
+                               }
+                               if (ref_offset < parent)
+                                       break;
+                       } else {
+                               if (root_objectid == ref_offset) {
+                                       err = 0;
+                                       break;
+                               }
+                               if (ref_offset < root_objectid)
+                                       break;
                        }
                }
-               btrfs_set_block_group_used(&cache->item, old_val);
-               total -= num_bytes;
-               bytenr += num_bytes;
+               ptr += btrfs_extent_inline_ref_size(type);
        }
-       return 0;
+       if (err == -ENOENT && insert) {
+               if (item_size + extra_size >=
+                   BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
+                       err = -EAGAIN;
+                       goto out;
+               }
+               /*
+                * To add new inline back ref, we have to make sure
+                * there is no corresponding back ref item.
+                * For simplicity, we just do not add new inline back
+                * ref if there is any back ref item.
+                */
+               if (find_next_key(path, &key) == 0 && key.objectid == bytenr &&
+                   key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
+                       err = -EAGAIN;
+                       goto out;
+               }
+       }
+       *ref_ret = (struct btrfs_extent_inline_ref *)ptr;
+out:
+       return err;
 }
 
-static int update_pinned_extents(struct btrfs_root *root,
-                               u64 bytenr, u64 num, int pin)
+static int setup_inline_extent_backref(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root,
+                               struct btrfs_path *path,
+                               struct btrfs_extent_inline_ref *iref,
+                               u64 parent, u64 root_objectid,
+                               u64 owner, u64 offset, int refs_to_add)
 {
-       u64 len;
-       struct btrfs_block_group_cache *cache;
-       struct btrfs_fs_info *fs_info = root->fs_info;
+       struct extent_buffer *leaf;
+       struct btrfs_extent_item *ei;
+       unsigned long ptr;
+       unsigned long end;
+       unsigned long item_offset;
+       u64 refs;
+       int size;
+       int type;
+       int ret;
 
-       if (pin) {
-               set_extent_dirty(&fs_info->pinned_extents,
-                               bytenr, bytenr + num - 1, GFP_NOFS);
+       leaf = path->nodes[0];
+       ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+       item_offset = (unsigned long)iref - (unsigned long)ei;
+
+       type = extent_ref_type(parent, owner);
+       size = btrfs_extent_inline_ref_size(type);
+
+       ret = btrfs_extend_item(trans, root, path, size);
+       BUG_ON(ret);
+
+       ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+       refs = btrfs_extent_refs(leaf, ei);
+       refs += refs_to_add;
+       btrfs_set_extent_refs(leaf, ei, refs);
+
+       ptr = (unsigned long)ei + item_offset;
+       end = (unsigned long)ei + btrfs_item_size_nr(leaf, path->slots[0]);
+       if (ptr < end - size)
+               memmove_extent_buffer(leaf, ptr + size, ptr,
+                                     end - size - ptr);
+
+       iref = (struct btrfs_extent_inline_ref *)ptr;
+       btrfs_set_extent_inline_ref_type(leaf, iref, type);
+       if (type == BTRFS_EXTENT_DATA_REF_KEY) {
+               struct btrfs_extent_data_ref *dref;
+               dref = (struct btrfs_extent_data_ref *)(&iref->offset);
+               btrfs_set_extent_data_ref_root(leaf, dref, root_objectid);
+               btrfs_set_extent_data_ref_objectid(leaf, dref, owner);
+               btrfs_set_extent_data_ref_offset(leaf, dref, offset);
+               btrfs_set_extent_data_ref_count(leaf, dref, refs_to_add);
+       } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
+               struct btrfs_shared_data_ref *sref;
+               sref = (struct btrfs_shared_data_ref *)(iref + 1);
+               btrfs_set_shared_data_ref_count(leaf, sref, refs_to_add);
+               btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
+       } else if (type == BTRFS_SHARED_BLOCK_REF_KEY) {
+               btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
        } else {
-               clear_extent_dirty(&fs_info->pinned_extents,
-                               bytenr, bytenr + num - 1, GFP_NOFS);
-       }
-       while (num > 0) {
-               cache = btrfs_lookup_block_group(fs_info, bytenr);
-               WARN_ON(!cache);
-               len = min(num, cache->key.offset -
-                         (bytenr - cache->key.objectid));
-               if (pin) {
-                       cache->pinned += len;
-                       cache->space_info->bytes_pinned += len;
-                       fs_info->total_pinned += len;
-               } else {
-                       cache->pinned -= len;
-                       cache->space_info->bytes_pinned -= len;
-                       fs_info->total_pinned -= len;
-               }
-               bytenr += len;
-               num -= len;
+               btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
        }
+       btrfs_mark_buffer_dirty(leaf);
        return 0;
 }
 
-int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy)
+static int lookup_extent_backref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                struct btrfs_extent_inline_ref **ref_ret,
+                                u64 bytenr, u64 num_bytes, u64 parent,
+                                u64 root_objectid, u64 owner, u64 offset)
 {
-       u64 last = 0;
-       u64 start;
-       u64 end;
-       struct extent_io_tree *pinned_extents = &root->fs_info->pinned_extents;
        int ret;
 
-       while(1) {
-               ret = find_first_extent_bit(pinned_extents, last,
-                                           &start, &end, EXTENT_DIRTY);
-               if (ret)
-                       break;
-               set_extent_dirty(copy, start, end, GFP_NOFS);
-               last = end + 1;
+       ret = lookup_inline_extent_backref(trans, root, path, ref_ret,
+                                          bytenr, num_bytes, parent,
+                                          root_objectid, owner, offset, 0);
+       if (ret != -ENOENT)
+               return ret;
+
+       btrfs_release_path(path);
+       *ref_ret = NULL;
+
+       if (owner < BTRFS_FIRST_FREE_OBJECTID) {
+               ret = lookup_tree_block_ref(trans, root, path, bytenr, parent,
+                                           root_objectid);
+       } else {
+               ret = lookup_extent_data_ref(trans, root, path, bytenr, parent,
+                                            root_objectid, owner, offset);
        }
-       return 0;
+       return ret;
 }
 
-int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
-                              struct btrfs_root *root,
-                              struct extent_io_tree *unpin)
+static int update_inline_extent_backref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                struct btrfs_extent_inline_ref *iref,
+                                int refs_to_mod)
 {
-       u64 start;
-       u64 end;
+       struct extent_buffer *leaf;
+       struct btrfs_extent_item *ei;
+       struct btrfs_extent_data_ref *dref = NULL;
+       struct btrfs_shared_data_ref *sref = NULL;
+       unsigned long ptr;
+       unsigned long end;
+       u32 item_size;
+       int size;
+       int type;
        int ret;
-       struct extent_io_tree *free_space_cache;
-       free_space_cache = &root->fs_info->free_space_cache;
+       u64 refs;
 
-       while(1) {
-               ret = find_first_extent_bit(unpin, 0, &start, &end,
-                                           EXTENT_DIRTY);
-               if (ret)
-                       break;
-               update_pinned_extents(root, start, end + 1 - start, 0);
-               clear_extent_dirty(unpin, start, end, GFP_NOFS);
-               set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
+       leaf = path->nodes[0];
+       ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+       refs = btrfs_extent_refs(leaf, ei);
+       WARN_ON(refs_to_mod < 0 && refs + refs_to_mod <= 0);
+       refs += refs_to_mod;
+       btrfs_set_extent_refs(leaf, ei, refs);
+
+       type = btrfs_extent_inline_ref_type(leaf, iref);
+
+       if (type == BTRFS_EXTENT_DATA_REF_KEY) {
+               dref = (struct btrfs_extent_data_ref *)(&iref->offset);
+               refs = btrfs_extent_data_ref_count(leaf, dref);
+       } else if (type == BTRFS_SHARED_DATA_REF_KEY) {
+               sref = (struct btrfs_shared_data_ref *)(iref + 1);
+               refs = btrfs_shared_data_ref_count(leaf, sref);
+       } else {
+               refs = 1;
+               BUG_ON(refs_to_mod != -1);
+       }
+
+       BUG_ON(refs_to_mod < 0 && refs < -refs_to_mod);
+       refs += refs_to_mod;
+
+       if (refs > 0) {
+               if (type == BTRFS_EXTENT_DATA_REF_KEY)
+                       btrfs_set_extent_data_ref_count(leaf, dref, refs);
+               else
+                       btrfs_set_shared_data_ref_count(leaf, sref, refs);
+       } else {
+               size =  btrfs_extent_inline_ref_size(type);
+               item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+               ptr = (unsigned long)iref;
+               end = (unsigned long)ei + item_size;
+               if (ptr + size < end)
+                       memmove_extent_buffer(leaf, ptr, ptr + size,
+                                             end - ptr - size);
+               item_size -= size;
+               ret = btrfs_truncate_item(trans, root, path, item_size, 1);
+               BUG_ON(ret);
        }
+       btrfs_mark_buffer_dirty(leaf);
        return 0;
 }
 
-static int finish_current_insert(struct btrfs_trans_handle *trans,
-                                struct btrfs_root *extent_root)
+static int insert_inline_extent_backref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                u64 bytenr, u64 num_bytes, u64 parent,
+                                u64 root_objectid, u64 owner,
+                                u64 offset, int refs_to_add)
 {
-       u64 start;
-       u64 end;
-       struct btrfs_fs_info *info = extent_root->fs_info;
-       struct extent_buffer *eb;
-       struct btrfs_path *path;
-       struct btrfs_key ins;
-       struct btrfs_disk_key first;
-       struct btrfs_extent_item extent_item;
+       struct btrfs_extent_inline_ref *iref;
        int ret;
-       int level;
-       int err = 0;
 
-       btrfs_set_stack_extent_refs(&extent_item, 1);
-       btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
-       path = btrfs_alloc_path();
+       ret = lookup_inline_extent_backref(trans, root, path, &iref,
+                                          bytenr, num_bytes, parent,
+                                          root_objectid, owner, offset, 1);
+       if (ret == 0) {
+               BUG_ON(owner < BTRFS_FIRST_FREE_OBJECTID);
+               ret = update_inline_extent_backref(trans, root, path, iref,
+                                                  refs_to_add);
+       } else if (ret == -ENOENT) {
+               ret = setup_inline_extent_backref(trans, root, path, iref,
+                                                 parent, root_objectid,
+                                                 owner, offset, refs_to_add);
+       }
+       return ret;
+}
 
-       while(1) {
-               ret = find_first_extent_bit(&info->extent_ins, 0, &start,
-                                           &end, EXTENT_LOCKED);
-               if (ret)
-                       break;
+static int insert_extent_backref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                u64 bytenr, u64 parent, u64 root_objectid,
+                                u64 owner, u64 offset, int refs_to_add)
+{
+       int ret;
 
-               ins.objectid = start;
-               ins.offset = end + 1 - start;
-               err = btrfs_insert_item(trans, extent_root, &ins,
-                                       &extent_item, sizeof(extent_item));
-               clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
-                                 GFP_NOFS);
-               eb = read_tree_block(extent_root, ins.objectid, ins.offset);
-               level = btrfs_header_level(eb);
-               if (level == 0) {
-                       btrfs_item_key(eb, &first, 0);
-               } else {
-                       btrfs_node_key(eb, &first, 0);
-               }
-               err = btrfs_insert_extent_backref(trans, extent_root, path,
-                                         start, extent_root->root_key.objectid,
-                                         0, level,
-                                         btrfs_disk_key_objectid(&first));
-               BUG_ON(err);
-               free_extent_buffer(eb);
+       if (owner >= BTRFS_FIRST_FREE_OBJECTID) {
+               ret = insert_extent_data_ref(trans, root, path, bytenr,
+                                            parent, root_objectid,
+                                            owner, offset, refs_to_add);
+       } else {
+               BUG_ON(refs_to_add != 1);
+               ret = insert_tree_block_ref(trans, root, path, bytenr,
+                                           parent, root_objectid);
        }
-       btrfs_free_path(path);
-       return 0;
+       return ret;
 }
 
-static int pin_down_bytes(struct btrfs_root *root, u64 bytenr, u32 num_bytes,
-                         int pending)
+static int remove_extent_backref(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                struct btrfs_extent_inline_ref *iref,
+                                int refs_to_drop, int is_data)
 {
-       int err = 0;
-       struct extent_buffer *buf;
+       int ret;
 
-       if (!pending) {
-               buf = btrfs_find_tree_block(root, bytenr, num_bytes);
-               if (buf) {
-                       if (btrfs_buffer_uptodate(buf)) {
-                               u64 transid =
-                                   root->fs_info->running_transaction->transid;
-                               if (btrfs_header_generation(buf) ==
-                                   transid && !btrfs_header_flag(buf,
-                                              BTRFS_HEADER_FLAG_WRITTEN)) {
-                                       free_extent_buffer(buf);
-                                       return 1;
-                               }
-                       }
-                       free_extent_buffer(buf);
-               }
-               update_pinned_extents(root, bytenr, num_bytes, 1);
+       BUG_ON(!is_data && refs_to_drop != 1);
+       if (iref) {
+               ret = update_inline_extent_backref(trans, root, path, iref,
+                                                  -refs_to_drop);
+       } else if (is_data) {
+               ret = remove_extent_data_ref(trans, root, path, refs_to_drop);
        } else {
-               set_extent_bits(&root->fs_info->pending_del,
-                               bytenr, bytenr + num_bytes - 1,
-                               EXTENT_LOCKED, GFP_NOFS);
+               ret = btrfs_del_item(trans, root, path);
        }
-       BUG_ON(err < 0);
-       return 0;
+       return ret;
 }
 
-/*
- * remove an extent from the root, returns 0 on success
- */
-static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-                        *root, u64 bytenr, u64 num_bytes,
-                        u64 root_objectid, u64 ref_generation,
-                        u64 owner_objectid, u64 owner_offset, int pin,
-                        int mark_free)
+int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root,
+                        u64 bytenr, u64 num_bytes, u64 parent,
+                        u64 root_objectid, u64 owner, u64 offset)
 {
        struct btrfs_path *path;
-       struct btrfs_key key;
-       struct btrfs_fs_info *info = root->fs_info;
-       struct btrfs_extent_ops *ops = info->extent_ops;
-       struct btrfs_root *extent_root = info->extent_root;
        struct extent_buffer *leaf;
+       struct btrfs_extent_item *item;
+       u64 refs;
        int ret;
-       int extent_slot = 0;
-       int found_extent = 0;
-       int num_to_del = 1;
-       struct btrfs_extent_item *ei;
-       u32 refs;
-
-       key.objectid = bytenr;
-       btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
-       key.offset = num_bytes;
+       int err = 0;
 
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
 
-       ret = lookup_extent_backref(trans, extent_root, path,
-                                   bytenr, root_objectid,
-                                   ref_generation,
-                                   owner_objectid, owner_offset, 1);
-       if (ret == 0) {
-               struct btrfs_key found_key;
-               extent_slot = path->slots[0];
-               while(extent_slot > 0) {
-                       extent_slot--;
-                       btrfs_item_key_to_cpu(path->nodes[0], &found_key,
-                                             extent_slot);
-                       if (found_key.objectid != bytenr)
-                               break;
-                       if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
-                           found_key.offset == num_bytes) {
-                               found_extent = 1;
-                               break;
-                       }
-                       if (path->slots[0] - extent_slot > 5)
-                               break;
-               }
-               if (!found_extent)
-                       ret = btrfs_del_item(trans, extent_root, path);
-       } else {
-               btrfs_print_leaf(extent_root, path->nodes[0]);
-               WARN_ON(1);
-               printk("Unable to find ref byte nr %llu root %llu "
-                      " gen %llu owner %llu offset %llu\n",
-                      (unsigned long long)bytenr,
-                      (unsigned long long)root_objectid,
-                      (unsigned long long)ref_generation,
-                      (unsigned long long)owner_objectid,
-                      (unsigned long long)owner_offset);
-       }
-       if (!found_extent) {
-               btrfs_release_path(extent_root, path);
-               ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
-               if (ret < 0)
-                       return ret;
-               BUG_ON(ret);
-               extent_slot = path->slots[0];
-       }
+       path->reada = 1;
 
+       ret = insert_inline_extent_backref(trans, root->fs_info->extent_root,
+                                          path, bytenr, num_bytes, parent,
+                                          root_objectid, owner, offset, 1);
+       if (ret == 0)
+               goto out;
+
+       if (ret != -EAGAIN) {
+               err = ret;
+               goto out;
+       }
+       
        leaf = path->nodes[0];
-       ei = btrfs_item_ptr(leaf, extent_slot,
-                           struct btrfs_extent_item);
-       refs = btrfs_extent_refs(leaf, ei);
-       BUG_ON(refs == 0);
-       refs -= 1;
-       btrfs_set_extent_refs(leaf, ei, refs);
+       item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+       refs = btrfs_extent_refs(leaf, item);
+       btrfs_set_extent_refs(leaf, item, refs + 1);
 
        btrfs_mark_buffer_dirty(leaf);
+       btrfs_release_path(path);
 
-       if (refs == 0 && found_extent && path->slots[0] == extent_slot + 1) {
-               /* if the back ref and the extent are next to each other
-                * they get deleted below in one shot
-                */
-               path->slots[0] = extent_slot;
-               num_to_del = 2;
-       } else if (found_extent) {
-               /* otherwise delete the extent back ref */
-               ret = btrfs_del_item(trans, extent_root, path);
-               BUG_ON(ret);
-               /* if refs are 0, we need to setup the path for deletion */
-               if (refs == 0) {
-                       btrfs_release_path(extent_root, path);
-                       ret = btrfs_search_slot(trans, extent_root, &key, path,
-                                               -1, 1);
-                       if (ret < 0)
-                               return ret;
-                       BUG_ON(ret);
-               }
+       path->reada = 1;
+
+       /* now insert the actual backref */
+       ret = insert_extent_backref(trans, root->fs_info->extent_root,
+                                   path, bytenr, parent, root_objectid,
+                                   owner, offset, 1);
+       if (ret)
+               err = ret;
+out:
+       btrfs_free_path(path);
+       finish_current_insert(trans, root->fs_info->extent_root);
+       del_pending_extents(trans, root->fs_info->extent_root);
+       BUG_ON(err);
+       return err;
+}
+
+int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root)
+{
+       finish_current_insert(trans, root->fs_info->extent_root);
+       del_pending_extents(trans, root->fs_info->extent_root);
+       return 0;
+}
+
+int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root, u64 bytenr,
+                            u64 offset, int metadata, u64 *refs, u64 *flags)
+{
+       struct btrfs_path *path;
+       int ret;
+       struct btrfs_key key;
+       struct extent_buffer *l;
+       struct btrfs_extent_item *item;
+       u32 item_size;
+       u64 num_refs;
+       u64 extent_flags;
+
+       if (metadata &&
+           !btrfs_fs_incompat(root->fs_info,
+                              BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)) {
+               offset = root->nodesize;
+               metadata = 0;
        }
 
-       if (refs == 0) {
-               u64 super_used;
-               u64 root_used;
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+       path->reada = 1;
 
-               if (pin) {
-                       ret = pin_down_bytes(root, bytenr, num_bytes, 0);
-                       if (ret > 0)
-                               mark_free = 1;
-                       BUG_ON(ret < 0);
-               }
+       key.objectid = bytenr;
+       key.offset = offset;
+       if (metadata)
+               key.type = BTRFS_METADATA_ITEM_KEY;
+       else
+               key.type = BTRFS_EXTENT_ITEM_KEY;
 
-               /* block accounting for super block */
-               super_used = btrfs_super_bytes_used(&info->super_copy);
-               btrfs_set_super_bytes_used(&info->super_copy,
-                                          super_used - num_bytes);
+again:
+       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
+                               0, 0);
+       if (ret < 0)
+               goto out;
 
-               /* block accounting for root item */
-               root_used = btrfs_root_used(&root->root_item);
-               btrfs_set_root_used(&root->root_item,
-                                          root_used - num_bytes);
-               ret = btrfs_del_items(trans, extent_root, path, path->slots[0],
-                                     num_to_del);
-               if (ret)
-                       return ret;
+       /*
+        * Deal with the fact that we may have mixed SKINNY and normal refs.  If
+        * we didn't find what we wanted check and see if we have a normal ref
+        * right next to us, or re-search if we are on the edge of the leaf just
+        * to make sure.
+        */
+       if (ret > 0 && metadata) {
+               if (path->slots[0]) {
+                       path->slots[0]--;
+                       btrfs_item_key_to_cpu(path->nodes[0], &key,
+                                             path->slots[0]);
+                       if (key.objectid == bytenr &&
+                           key.type == BTRFS_EXTENT_ITEM_KEY &&
+                           key.offset == root->nodesize)
+                               ret = 0;
+               }
 
-               if (ops && ops->free_extent)
-                       ops->free_extent(root, bytenr, num_bytes);
+               if (ret) {
+                       btrfs_release_path(path);
+                       key.type = BTRFS_EXTENT_ITEM_KEY;
+                       key.offset = root->nodesize;
+                       metadata = 0;
+                       goto again;
+               }
+       }
 
-               ret = update_block_group(trans, root, bytenr, num_bytes, 0,
-                                        mark_free);
-               BUG_ON(ret);
+       if (ret != 0) {
+               ret = -EIO;
+               goto out;
+       }
+
+       l = path->nodes[0];
+       item_size = btrfs_item_size_nr(l, path->slots[0]);
+       if (item_size >= sizeof(*item)) {
+               item = btrfs_item_ptr(l, path->slots[0],
+                                     struct btrfs_extent_item);
+               num_refs = btrfs_extent_refs(l, item);
+               extent_flags = btrfs_extent_flags(l, item);
+       } else {
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+                       struct btrfs_extent_item_v0 *ei0;
+                       BUG_ON(item_size != sizeof(*ei0));
+                       ei0 = btrfs_item_ptr(l, path->slots[0],
+                                            struct btrfs_extent_item_v0);
+                       num_refs = btrfs_extent_refs_v0(l, ei0);
+                       /* FIXME: this isn't correct for data */
+                       extent_flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
+#else
+                       BUG();
+#endif
        }
+       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
+       if (refs)
+               *refs = num_refs;
+       if (flags)
+               *flags = extent_flags;
+out:
        btrfs_free_path(path);
-       finish_current_insert(trans, extent_root);
        return ret;
 }
 
-/*
- * find all the blocks marked as pending in the radix tree and remove
- * them from the extent map
- */
-static int del_pending_extents(struct btrfs_trans_handle *trans, struct
-                              btrfs_root *extent_root)
+int btrfs_set_block_flags(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         u64 bytenr, int level, u64 flags)
 {
+       struct btrfs_path *path;
        int ret;
-       int err = 0;
-       u64 start;
-       u64 end;
-       struct extent_io_tree *pending_del;
-       struct extent_io_tree *pinned_extents;
+       struct btrfs_key key;
+       struct extent_buffer *l;
+       struct btrfs_extent_item *item;
+       u32 item_size;
+       int skinny_metadata =
+               btrfs_fs_incompat(root->fs_info,
+                                 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);
 
-       pending_del = &extent_root->fs_info->pending_del;
-       pinned_extents = &extent_root->fs_info->pinned_extents;
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+       path->reada = 1;
 
-       while(1) {
-               ret = find_first_extent_bit(pending_del, 0, &start, &end,
-                                           EXTENT_LOCKED);
-               if (ret)
-                       break;
-               update_pinned_extents(extent_root, start, end + 1 - start, 1);
-               clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
-                                 GFP_NOFS);
-               ret = __free_extent(trans, extent_root,
-                                    start, end + 1 - start,
-                                    extent_root->root_key.objectid,
-                                    0, 0, 0, 0, 0);
-               if (ret)
-                       err = ret;
+       key.objectid = bytenr;
+       if (skinny_metadata) {
+               key.offset = level;
+               key.type = BTRFS_METADATA_ITEM_KEY;
+       } else {
+               key.offset = root->nodesize;
+               key.type = BTRFS_EXTENT_ITEM_KEY;
        }
-       return err;
-}
 
-/*
- * remove an extent from the root, returns 0 on success
- */
-int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-                     *root, u64 bytenr, u64 num_bytes,
-                     u64 root_objectid, u64 ref_generation,
-                     u64 owner_objectid, u64 owner_offset, int pin)
-{
-       struct btrfs_root *extent_root = root->fs_info->extent_root;
-       int pending_ret;
-       int ret;
+again:
+       ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
+                               0, 0);
+       if (ret < 0)
+               goto out;
 
-       WARN_ON(num_bytes < root->sectorsize);
-       if (!root->ref_cows)
-               ref_generation = 0;
+       if (ret > 0 && skinny_metadata) {
+               skinny_metadata = 0;
+               if (path->slots[0]) {
+                       path->slots[0]--;
+                       btrfs_item_key_to_cpu(path->nodes[0], &key,
+                                             path->slots[0]);
+                       if (key.objectid == bytenr &&
+                           key.offset == root->nodesize &&
+                           key.type == BTRFS_EXTENT_ITEM_KEY)
+                               ret = 0;
+               }
+               if (ret) {
+                       btrfs_release_path(path);
+                       key.offset = root->nodesize;
+                       key.type = BTRFS_EXTENT_ITEM_KEY;
+                       goto again;
+               }
+       }
 
-       if (root == extent_root) {
-               pin_down_bytes(root, bytenr, num_bytes, 1);
-               return 0;
+       if (ret != 0) {
+               btrfs_print_leaf(root, path->nodes[0]);
+               printk("failed to find block number %Lu\n",
+                       (unsigned long long)bytenr);
+               BUG();
        }
-       ret = __free_extent(trans, root, bytenr, num_bytes, root_objectid,
-                           ref_generation, owner_objectid, owner_offset,
-                           pin, pin == 0);
-       pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
-       return ret ? ret : pending_ret;
-}
+       l = path->nodes[0];
+       item_size = btrfs_item_size_nr(l, path->slots[0]);
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+       if (item_size < sizeof(*item)) {
+               ret = convert_extent_item_v0(trans, root->fs_info->extent_root,
+                                            path, (u64)-1, 0);
+               if (ret < 0)
+                       goto out;
 
-static u64 stripe_align(struct btrfs_root *root, u64 val)
-{
-       u64 mask = ((u64)root->stripesize - 1);
-       u64 ret = (val + mask) & ~mask;
+               l = path->nodes[0];
+               item_size = btrfs_item_size_nr(l, path->slots[0]);
+       }
+#endif
+       BUG_ON(item_size < sizeof(*item));
+       item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
+       flags |= btrfs_extent_flags(l, item);
+       btrfs_set_extent_flags(l, item, flags);
+out:
+       btrfs_free_path(path);
+       finish_current_insert(trans, root->fs_info->extent_root);
+       del_pending_extents(trans, root->fs_info->extent_root);
        return ret;
 }
 
-/*
- * walks the btree of allocated extents and find a hole of a given size.
- * The key ins is changed to record the hole:
- * ins->objectid == block start
- * ins->flags = BTRFS_EXTENT_ITEM_KEY
- * ins->offset == number of blocks
- * Any available blocks before search_start are skipped.
- */
-static int noinline find_free_extent(struct btrfs_trans_handle *trans,
-                                    struct btrfs_root *orig_root,
-                                    u64 num_bytes, u64 empty_size,
-                                    u64 search_start, u64 search_end,
-                                    u64 hint_byte, struct btrfs_key *ins,
-                                    u64 exclude_start, u64 exclude_nr,
-                                    int data)
+static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
+                          struct btrfs_root *root,
+                          struct extent_buffer *buf,
+                          int record_parent, int inc)
 {
-       int ret;
-       u64 orig_search_start = search_start;
-       struct btrfs_root * root = orig_root->fs_info->extent_root;
-       struct btrfs_fs_info *info = root->fs_info;
-       u64 total_needed = num_bytes;
-       struct btrfs_block_group_cache *block_group;
-       int full_scan = 0;
-       int wrapped = 0;
+       u64 bytenr;
+       u64 num_bytes;
+       u64 parent;
+       u64 ref_root;
+       u32 nritems;
+       struct btrfs_key key;
+       struct btrfs_file_extent_item *fi;
+       int i;
+       int level;
+       int ret = 0;
+       int (*process_func)(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root,
+                           u64, u64, u64, u64, u64, u64);
 
-       WARN_ON(num_bytes < root->sectorsize);
-       btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
+       ref_root = btrfs_header_owner(buf);
+       nritems = btrfs_header_nritems(buf);
+       level = btrfs_header_level(buf);
 
-       if (search_end == (u64)-1)
-               search_end = btrfs_super_total_bytes(&info->super_copy);
+       if (!root->ref_cows && level == 0)
+               return 0;
 
-       if (hint_byte) {
-               block_group = btrfs_lookup_block_group(info, hint_byte);
-               if (!block_group)
-                       hint_byte = search_start;
-               block_group = btrfs_find_block_group(root, block_group,
-                                                    hint_byte, data, 1);
-       } else {
-               block_group = btrfs_find_block_group(root,
-                                                    trans->block_group,
-                                                    search_start, data, 1);
-       }
+       if (inc)
+               process_func = btrfs_inc_extent_ref;
+       else
+               process_func = btrfs_free_extent;
 
-       total_needed += empty_size;
+       if (record_parent)
+               parent = buf->start;
+       else
+               parent = 0;
 
-check_failed:
-       if (!block_group) {
-               block_group = btrfs_lookup_block_group(info, search_start);
-               if (!block_group)
-                       block_group = btrfs_lookup_block_group(info,
-                                                      orig_search_start);
+       for (i = 0; i < nritems; i++) {
+               cond_resched();
+               if (level == 0) {
+                       btrfs_item_key_to_cpu(buf, &key, i);
+                       if (key.type != BTRFS_EXTENT_DATA_KEY)
+                               continue;
+                       fi = btrfs_item_ptr(buf, i,
+                                           struct btrfs_file_extent_item);
+                       if (btrfs_file_extent_type(buf, fi) ==
+                           BTRFS_FILE_EXTENT_INLINE)
+                               continue;
+                       bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
+                       if (bytenr == 0)
+                               continue;
+                       
+                       num_bytes = btrfs_file_extent_disk_num_bytes(buf, fi);
+                       key.offset -= btrfs_file_extent_offset(buf, fi);
+                       ret = process_func(trans, root, bytenr, num_bytes,
+                                          parent, ref_root, key.objectid,
+                                          key.offset);
+                       if (ret) {
+                               WARN_ON(1);
+                               goto fail;
+                       }
+               } else {
+                       bytenr = btrfs_node_blockptr(buf, i);
+                       num_bytes = root->nodesize;
+                       ret = process_func(trans, root, bytenr, num_bytes,
+                                          parent, ref_root, level - 1, 0);
+                       if (ret) {
+                               WARN_ON(1);
+                               goto fail;
+                       }
+               }
        }
-       ret = find_search_start(root, &block_group, &search_start,
-                               total_needed, data);
-       if (ret)
-               goto error;
-
-       search_start = stripe_align(root, search_start);
-       ins->objectid = search_start;
-       ins->offset = num_bytes;
-
-       if (ins->objectid + num_bytes >= search_end)
-               goto enospc;
+       return 0;
+fail:
+       WARN_ON(1);
+       return ret;
+}
 
-       if (ins->objectid + num_bytes >
-           block_group->key.objectid + block_group->key.offset) {
-               search_start = block_group->key.objectid +
-                       block_group->key.offset;
-               goto new_group;
-       }
+int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+                 struct extent_buffer *buf, int record_parent)
+{
+       return __btrfs_mod_ref(trans, root, buf, record_parent, 1);
+}
 
-       if (test_range_bit(&info->extent_ins, ins->objectid,
-                          ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
-               search_start = ins->objectid + num_bytes;
-               goto new_group;
-       }
+int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+                 struct extent_buffer *buf, int record_parent)
+{
+       return __btrfs_mod_ref(trans, root, buf, record_parent, 0);
+}
 
-       if (test_range_bit(&info->pinned_extents, ins->objectid,
-                          ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
-               search_start = ins->objectid + num_bytes;
-               goto new_group;
-       }
+static int write_one_cache_group(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path,
+                                struct btrfs_block_group_cache *cache)
+{
+       int ret;
+       int pending_ret;
+       struct btrfs_root *extent_root = root->fs_info->extent_root;
+       unsigned long bi;
+       struct extent_buffer *leaf;
 
-       if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
-           ins->objectid < exclude_start + exclude_nr)) {
-               search_start = exclude_start + exclude_nr;
-               goto new_group;
-       }
+       ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
+       if (ret < 0)
+               goto fail;
+       BUG_ON(ret);
 
-       if (!(data & BTRFS_BLOCK_GROUP_DATA)) {
-               block_group = btrfs_lookup_block_group(info, ins->objectid);
-               if (block_group)
-                       trans->block_group = block_group;
-       }
-       ins->offset = num_bytes;
+       leaf = path->nodes[0];
+       bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
+       write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
+       btrfs_mark_buffer_dirty(leaf);
+       btrfs_release_path(path);
+fail:
+       finish_current_insert(trans, extent_root);
+       pending_ret = del_pending_extents(trans, extent_root);
+       if (ret)
+               return ret;
+       if (pending_ret)
+               return pending_ret;
        return 0;
 
-new_group:
-       if (search_start + num_bytes >= search_end) {
-enospc:
-               search_start = orig_search_start;
-               if (full_scan) {
-                       ret = -ENOSPC;
-                       goto error;
-               }
-               if (wrapped) {
-                       if (!full_scan)
-                               total_needed -= empty_size;
-                       full_scan = 1;
-               } else
-                       wrapped = 1;
-       }
-       block_group = btrfs_lookup_block_group(info, search_start);
-       cond_resched();
-       block_group = btrfs_find_block_group(root, block_group,
-                                            search_start, data, 0);
-       goto check_failed;
-
-error:
-       return ret;
 }
-/*
- * finds a free extent and does all the dirty work required for allocation
- * returns the key for the extent through ins, and a tree buffer for
- * the first block of the extent through buf.
- *
- * returns 0 if everything worked, non-zero otherwise.
- */
-int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
-                      struct btrfs_root *root,
-                      u64 num_bytes, u64 root_objectid, u64 ref_generation,
-                      u64 owner, u64 owner_offset,
-                      u64 empty_size, u64 hint_byte,
-                      u64 search_end, struct btrfs_key *ins, int data)
+
+int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
+                                  struct btrfs_root *root)
 {
+       struct extent_io_tree *block_group_cache;
+       struct btrfs_block_group_cache *cache;
        int ret;
-       int pending_ret;
-       u64 super_used, root_used;
-       u64 search_start = 0;
-       u64 alloc_profile;
-       struct btrfs_fs_info *info = root->fs_info;
-       struct btrfs_extent_ops *ops = info->extent_ops;
-       u32 sizes[2];
-       struct btrfs_root *extent_root = info->extent_root;
        struct btrfs_path *path;
-       struct btrfs_extent_item *extent_item;
-       struct btrfs_extent_ref *ref;
-       struct btrfs_key keys[2];
+       u64 last = 0;
+       u64 start;
+       u64 end;
+       u64 ptr;
 
-       if (data) {
-               alloc_profile = info->avail_data_alloc_bits &
-                               info->data_alloc_profile;
-               data = BTRFS_BLOCK_GROUP_DATA | alloc_profile;
-       } else if (root == info->chunk_root || info->force_system_allocs) {
-               alloc_profile = info->avail_system_alloc_bits &
-                               info->system_alloc_profile;
-               data = BTRFS_BLOCK_GROUP_SYSTEM | alloc_profile;
-       } else {
-               alloc_profile = info->avail_metadata_alloc_bits &
-                               info->metadata_alloc_profile;
-               data = BTRFS_BLOCK_GROUP_METADATA | alloc_profile;
-       }
+       block_group_cache = &root->fs_info->block_group_cache;
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
 
-       if (root->ref_cows) {
-               if (!(data & BTRFS_BLOCK_GROUP_METADATA)) {
-                       ret = do_chunk_alloc(trans, root->fs_info->extent_root,
-                                            num_bytes,
-                                            BTRFS_BLOCK_GROUP_METADATA);
-                       BUG_ON(ret);
+       while(1) {
+               ret = find_first_extent_bit(block_group_cache, last,
+                                           &start, &end, BLOCK_GROUP_DIRTY);
+               if (ret) {
+                       if (last == 0)
+                               break;
+                       last = 0;
+                       continue;
                }
-               ret = do_chunk_alloc(trans, root->fs_info->extent_root,
-                                    num_bytes + 2 * 1024 * 1024, data);
-               BUG_ON(ret);
-       }
-
-       WARN_ON(num_bytes < root->sectorsize);
-       if (ops && ops->alloc_extent) {
-               ret = ops->alloc_extent(root, num_bytes, hint_byte, ins);
-       } else {
-               ret = find_free_extent(trans, root, num_bytes, empty_size,
-                                       search_start, search_end, hint_byte,
-                                       ins, trans->alloc_exclude_start,
-                                       trans->alloc_exclude_nr, data);
-       }
-       BUG_ON(ret);
-       if (ret)
-               return ret;
 
-       /* block accounting for super block */
-       super_used = btrfs_super_bytes_used(&info->super_copy);
-       btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
-
-       /* block accounting for root item */
-       root_used = btrfs_root_used(&root->root_item);
-       btrfs_set_root_used(&root->root_item, root_used + num_bytes);
+               last = end + 1;
+               ret = get_state_private(block_group_cache, start, &ptr);
+               BUG_ON(ret);
 
-       clear_extent_dirty(&root->fs_info->free_space_cache,
-                          ins->objectid, ins->objectid + ins->offset - 1,
-                          GFP_NOFS);
+               clear_extent_bits(block_group_cache, start, end,
+                                 BLOCK_GROUP_DIRTY, GFP_NOFS);
 
-       if (root == extent_root) {
-               set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
-                               ins->objectid + ins->offset - 1,
-                               EXTENT_LOCKED, GFP_NOFS);
-               goto update_block;
+               cache = (struct btrfs_block_group_cache *)(unsigned long)ptr;
+               ret = write_one_cache_group(trans, root, path, cache);
        }
+       btrfs_free_path(path);
+       return 0;
+}
 
-       WARN_ON(trans->alloc_exclude_nr);
-       trans->alloc_exclude_start = ins->objectid;
-       trans->alloc_exclude_nr = ins->offset;
-
-       memcpy(&keys[0], ins, sizeof(*ins));
-       keys[1].offset = hash_extent_ref(root_objectid, ref_generation,
-                                        owner, owner_offset);
-       keys[1].objectid = ins->objectid;
-       keys[1].type = BTRFS_EXTENT_REF_KEY;
-       sizes[0] = sizeof(*extent_item);
-       sizes[1] = sizeof(*ref);
-
-       path = btrfs_alloc_path();
-       BUG_ON(!path);
-
-       ret = btrfs_insert_empty_items(trans, extent_root, path, keys,
-                                      sizes, 2);
+static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
+                                                 u64 flags)
+{
+       struct btrfs_space_info *found;
 
-       BUG_ON(ret);
-       extent_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
-                                    struct btrfs_extent_item);
-       btrfs_set_extent_refs(path->nodes[0], extent_item, 1);
-       ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,
-                            struct btrfs_extent_ref);
+       flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
 
-       btrfs_set_ref_root(path->nodes[0], ref, root_objectid);
-       btrfs_set_ref_generation(path->nodes[0], ref, ref_generation);
-       btrfs_set_ref_objectid(path->nodes[0], ref, owner);
-       btrfs_set_ref_offset(path->nodes[0], ref, owner_offset);
+       list_for_each_entry(found, &info->space_info, list) {
+               if (found->flags & flags)
+                       return found;
+       }
+       return NULL;
 
-       btrfs_mark_buffer_dirty(path->nodes[0]);
+}
 
-       trans->alloc_exclude_start = 0;
-       trans->alloc_exclude_nr = 0;
-       btrfs_free_path(path);
-       finish_current_insert(trans, extent_root);
-       pending_ret = del_pending_extents(trans, extent_root);
+static int free_space_info(struct btrfs_fs_info *fs_info, u64 flags,
+                          u64 total_bytes, u64 bytes_used,
+                          struct btrfs_space_info **space_info)
+{
+       struct btrfs_space_info *found;
 
-       if (ret) {
-               return ret;
-       }
-       if (pending_ret) {
-               return pending_ret;
-       }
+       /* only support free block group which is empty */
+       if (bytes_used)
+               return -ENOTEMPTY;
 
-update_block:
-       ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0);
-       if (ret) {
-               printk("update block group failed for %llu %llu\n",
-                      (unsigned long long)ins->objectid,
-                      (unsigned long long)ins->offset);
-               BUG();
+       found = __find_space_info(fs_info, flags);
+       if (!found)
+               return -ENOENT;
+       if (found->total_bytes < total_bytes) {
+               fprintf(stderr,
+                       "WARNING: bad space info to free %llu only have %llu\n",
+                       total_bytes, found->total_bytes);
+               return -EINVAL;
        }
+       found->total_bytes -= total_bytes;
+       if (space_info)
+               *space_info = found;
        return 0;
 }
 
-/*
- * helper function to allocate a block for a given tree
- * returns the tree buffer or NULL.
- */
-struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                            struct btrfs_root *root,
-                                            u32 blocksize,
-                                            u64 root_objectid, u64 hint,
-                                            u64 empty_size)
+static int update_space_info(struct btrfs_fs_info *info, u64 flags,
+                            u64 total_bytes, u64 bytes_used,
+                            struct btrfs_space_info **space_info)
 {
-       u64 ref_generation;
-
-       if (root->ref_cows)
-               ref_generation = trans->transid;
-       else
-               ref_generation = 0;
+       struct btrfs_space_info *found;
 
+       found = __find_space_info(info, flags);
+       if (found) {
+               found->total_bytes += total_bytes;
+               found->bytes_used += bytes_used;
+               if (found->total_bytes < found->bytes_used) {
+                       fprintf(stderr, "warning, bad space info total_bytes "
+                               "%llu used %llu\n",
+                              (unsigned long long)found->total_bytes,
+                              (unsigned long long)found->bytes_used);
+               }
+               *space_info = found;
+               return 0;
+       }
+       found = kmalloc(sizeof(*found), GFP_NOFS);
+       if (!found)
+               return -ENOMEM;
 
-       return __btrfs_alloc_free_block(trans, root, blocksize, root_objectid,
-                                       ref_generation, 0, 0, hint, empty_size);
+       list_add(&found->list, &info->space_info);
+       found->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
+       found->total_bytes = total_bytes;
+       found->bytes_used = bytes_used;
+       found->bytes_pinned = 0;
+       found->full = 0;
+       *space_info = found;
+       return 0;
 }
 
-/*
- * helper function to allocate a block for a given tree
- * returns the tree buffer or NULL.
- */
-struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                            struct btrfs_root *root,
-                                            u32 blocksize,
-                                            u64 root_objectid,
-                                            u64 ref_generation,
-                                            u64 first_objectid,
-                                            int level,
-                                            u64 hint,
-                                            u64 empty_size)
-{
-       struct btrfs_key ins;
-       int ret;
-       struct extent_buffer *buf;
 
-       ret = btrfs_alloc_extent(trans, root, blocksize,
-                                root_objectid, ref_generation,
-                                level, first_objectid, empty_size, hint,
-                                (u64)-1, &ins, 0);
-       if (ret) {
-               BUG_ON(ret > 0);
-               return ERR_PTR(ret);
-       }
-       buf = btrfs_find_create_tree_block(root, ins.objectid, blocksize);
-       if (!buf) {
-               btrfs_free_extent(trans, root, ins.objectid, blocksize,
-                                 root->root_key.objectid, ref_generation,
-                                 0, 0, 0);
-               BUG_ON(1);
-               return ERR_PTR(-ENOMEM);
+static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
+{
+       u64 extra_flags = flags & (BTRFS_BLOCK_GROUP_RAID0 |
+                                  BTRFS_BLOCK_GROUP_RAID1 |
+                                  BTRFS_BLOCK_GROUP_RAID10 |
+                                  BTRFS_BLOCK_GROUP_RAID5 |
+                                  BTRFS_BLOCK_GROUP_RAID6 |
+                                  BTRFS_BLOCK_GROUP_DUP);
+       if (extra_flags) {
+               if (flags & BTRFS_BLOCK_GROUP_DATA)
+                       fs_info->avail_data_alloc_bits |= extra_flags;
+               if (flags & BTRFS_BLOCK_GROUP_METADATA)
+                       fs_info->avail_metadata_alloc_bits |= extra_flags;
+               if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
+                       fs_info->avail_system_alloc_bits |= extra_flags;
        }
-       btrfs_set_buffer_uptodate(buf);
-       trans->blocks_used++;
-       return buf;
 }
 
-static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans,
-                                 struct btrfs_root *root,
-                                 struct extent_buffer *leaf)
+static int do_chunk_alloc(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *extent_root, u64 alloc_bytes,
+                         u64 flags)
 {
-       u64 leaf_owner;
-       u64 leaf_generation;
-       struct btrfs_key key;
-       struct btrfs_file_extent_item *fi;
-       int i;
-       int nritems;
+       struct btrfs_space_info *space_info;
+       u64 thresh;
+       u64 start;
+       u64 num_bytes;
        int ret;
 
-       BUG_ON(!btrfs_is_leaf(leaf));
-       nritems = btrfs_header_nritems(leaf);
-       leaf_owner = btrfs_header_owner(leaf);
-       leaf_generation = btrfs_header_generation(leaf);
+       space_info = __find_space_info(extent_root->fs_info, flags);
+       if (!space_info) {
+               ret = update_space_info(extent_root->fs_info, flags,
+                                       0, 0, &space_info);
+               BUG_ON(ret);
+       }
+       BUG_ON(!space_info);
 
-       for (i = 0; i < nritems; i++) {
-               u64 disk_bytenr;
+       if (space_info->full)
+               return 0;
 
-               btrfs_item_key_to_cpu(leaf, &key, i);
-               if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
-                       continue;
+       thresh = div_factor(space_info->total_bytes, 7);
+       if ((space_info->bytes_used + space_info->bytes_pinned + alloc_bytes) <
+           thresh)
+               return 0;
+
+       /*
+        * Avoid allocating given chunk type
+        */
+       if (extent_root->fs_info->avoid_meta_chunk_alloc &&
+           (flags & BTRFS_BLOCK_GROUP_METADATA))
+               return 0;
+       if (extent_root->fs_info->avoid_sys_chunk_alloc &&
+           (flags & BTRFS_BLOCK_GROUP_SYSTEM))
+               return 0;
+
+       ret = btrfs_alloc_chunk(trans, extent_root, &start, &num_bytes,
+                               space_info->flags);
+       if (ret == -ENOSPC) {
+               space_info->full = 1;
+               return 0;
+       }
+
+       BUG_ON(ret);
+
+       ret = btrfs_make_block_group(trans, extent_root, 0, space_info->flags,
+                    BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes);
+       BUG_ON(ret);
+       return 0;
+}
+
+static int update_block_group(struct btrfs_trans_handle *trans,
+                             struct btrfs_root *root,
+                             u64 bytenr, u64 num_bytes, int alloc,
+                             int mark_free)
+{
+       struct btrfs_block_group_cache *cache;
+       struct btrfs_fs_info *info = root->fs_info;
+       u64 total = num_bytes;
+       u64 old_val;
+       u64 byte_in_group;
+       u64 start;
+       u64 end;
+
+       /* block accounting for super block */
+       old_val = btrfs_super_bytes_used(info->super_copy);
+       if (alloc)
+               old_val += num_bytes;
+       else
+               old_val -= num_bytes;
+       btrfs_set_super_bytes_used(info->super_copy, old_val);
+
+       /* block accounting for root item */
+       old_val = btrfs_root_used(&root->root_item);
+       if (alloc)
+               old_val += num_bytes;
+       else
+               old_val -= num_bytes;
+       btrfs_set_root_used(&root->root_item, old_val);
+
+       while(total) {
+               cache = btrfs_lookup_block_group(info, bytenr);
+               if (!cache) {
+                       return -1;
+               }
+               byte_in_group = bytenr - cache->key.objectid;
+               WARN_ON(byte_in_group > cache->key.offset);
+               start = cache->key.objectid;
+               end = start + cache->key.offset - 1;
+               set_extent_bits(&info->block_group_cache, start, end,
+                               BLOCK_GROUP_DIRTY, GFP_NOFS);
+
+               old_val = btrfs_block_group_used(&cache->item);
+               num_bytes = min(total, cache->key.offset - byte_in_group);
+
+               if (alloc) {
+                       old_val += num_bytes;
+                       cache->space_info->bytes_used += num_bytes;
+               } else {
+                       old_val -= num_bytes;
+                       cache->space_info->bytes_used -= num_bytes;
+                       if (mark_free) {
+                               set_extent_dirty(&info->free_space_cache,
+                                                bytenr, bytenr + num_bytes - 1,
+                                                GFP_NOFS);
+                       }
+               }
+               btrfs_set_block_group_used(&cache->item, old_val);
+               total -= num_bytes;
+               bytenr += num_bytes;
+       }
+       return 0;
+}
+
+static int update_pinned_extents(struct btrfs_root *root,
+                               u64 bytenr, u64 num, int pin)
+{
+       u64 len;
+       struct btrfs_block_group_cache *cache;
+       struct btrfs_fs_info *fs_info = root->fs_info;
+
+       if (pin) {
+               set_extent_dirty(&fs_info->pinned_extents,
+                               bytenr, bytenr + num - 1, GFP_NOFS);
+       } else {
+               clear_extent_dirty(&fs_info->pinned_extents,
+                               bytenr, bytenr + num - 1, GFP_NOFS);
+       }
+       while (num > 0) {
+               cache = btrfs_lookup_block_group(fs_info, bytenr);
+               if (!cache) {
+                       len = min((u64)root->sectorsize, num);
+                       goto next;
+               }
+               WARN_ON(!cache);
+               len = min(num, cache->key.offset -
+                         (bytenr - cache->key.objectid));
+               if (pin) {
+                       cache->pinned += len;
+                       cache->space_info->bytes_pinned += len;
+                       fs_info->total_pinned += len;
+               } else {
+                       cache->pinned -= len;
+                       cache->space_info->bytes_pinned -= len;
+                       fs_info->total_pinned -= len;
+               }
+next:
+               bytenr += len;
+               num -= len;
+       }
+       return 0;
+}
+
+int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root,
+                              struct extent_io_tree *unpin)
+{
+       u64 start;
+       u64 end;
+       int ret;
+       struct extent_io_tree *free_space_cache;
+       free_space_cache = &root->fs_info->free_space_cache;
+
+       while(1) {
+               ret = find_first_extent_bit(unpin, 0, &start, &end,
+                                           EXTENT_DIRTY);
+               if (ret)
+                       break;
+               update_pinned_extents(root, start, end + 1 - start, 0);
+               clear_extent_dirty(unpin, start, end, GFP_NOFS);
+               set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
+       }
+       return 0;
+}
+
+static int extent_root_pending_ops(struct btrfs_fs_info *info)
+{
+       u64 start;
+       u64 end;
+       int ret;
+
+       ret = find_first_extent_bit(&info->extent_ins, 0, &start,
+                                   &end, EXTENT_LOCKED);
+       if (!ret) {
+               ret = find_first_extent_bit(&info->pending_del, 0, &start, &end,
+                                           EXTENT_LOCKED);
+       }
+       return ret == 0;
+
+}
+static int finish_current_insert(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *extent_root)
+{
+       u64 start;
+       u64 end;
+       u64 priv;
+       struct btrfs_fs_info *info = extent_root->fs_info;
+       struct pending_extent_op *extent_op;
+       struct btrfs_key key;
+       int ret;
+       int skinny_metadata =
+               btrfs_fs_incompat(extent_root->fs_info,
+                                 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);
+
+       while(1) {
+               ret = find_first_extent_bit(&info->extent_ins, 0, &start,
+                                           &end, EXTENT_LOCKED);
+               if (ret)
+                       break;
+
+               ret = get_state_private(&info->extent_ins, start, &priv);
+               BUG_ON(ret);
+               extent_op = (struct pending_extent_op *)(unsigned long)priv;
+
+               if (extent_op->type == PENDING_EXTENT_INSERT) {
+                       key.objectid = start;
+                       if (skinny_metadata) {
+                               key.offset = extent_op->level;
+                               key.type = BTRFS_METADATA_ITEM_KEY;
+                       } else {
+                               key.offset = extent_op->num_bytes;
+                               key.type = BTRFS_EXTENT_ITEM_KEY;
+                       }
+                       ret = alloc_reserved_tree_block(trans, extent_root,
+                                               extent_root->root_key.objectid,
+                                               trans->transid,
+                                               extent_op->flags,
+                                               &extent_op->key,
+                                               extent_op->level, &key);
+                       BUG_ON(ret);
+               } else {
+                       BUG_ON(1);
+               }
+
+               clear_extent_bits(&info->extent_ins, start, end, EXTENT_LOCKED,
+                                 GFP_NOFS);
+               kfree(extent_op);
+       }
+       return 0;
+}
+
+static int pin_down_bytes(struct btrfs_trans_handle *trans,
+                         struct btrfs_root *root,
+                         u64 bytenr, u64 num_bytes, int is_data)
+{
+       int err = 0;
+       struct extent_buffer *buf;
+
+       if (is_data)
+               goto pinit;
+
+       buf = btrfs_find_tree_block(root, bytenr, num_bytes);
+       if (!buf)
+               goto pinit;
+
+       /* we can reuse a block if it hasn't been written
+        * and it is from this transaction.  We can't
+        * reuse anything from the tree log root because
+        * it has tiny sub-transactions.
+        */
+       if (btrfs_buffer_uptodate(buf, 0)) {
+               u64 header_owner = btrfs_header_owner(buf);
+               u64 header_transid = btrfs_header_generation(buf);
+               if (header_owner != BTRFS_TREE_LOG_OBJECTID &&
+                   header_transid == trans->transid &&
+                   !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
+                       clean_tree_block(NULL, root, buf);
+                       free_extent_buffer(buf);
+                       return 1;
+               }
+       }
+       free_extent_buffer(buf);
+pinit:
+       update_pinned_extents(root, bytenr, num_bytes, 1);
+
+       BUG_ON(err < 0);
+       return 0;
+}
+
+void btrfs_pin_extent(struct btrfs_fs_info *fs_info,
+                      u64 bytenr, u64 num_bytes)
+{
+       update_pinned_extents(fs_info->extent_root, bytenr, num_bytes, 1);
+}
+
+void btrfs_unpin_extent(struct btrfs_fs_info *fs_info,
+                       u64 bytenr, u64 num_bytes)
+{
+       update_pinned_extents(fs_info->extent_root, bytenr, num_bytes, 0);
+}
+
+/*
+ * remove an extent from the root, returns 0 on success
+ */
+static int __free_extent(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root,
+                        u64 bytenr, u64 num_bytes, u64 parent,
+                        u64 root_objectid, u64 owner_objectid,
+                        u64 owner_offset, int refs_to_drop)
+{
+
+       struct btrfs_key key;
+       struct btrfs_path *path;
+       struct btrfs_root *extent_root = root->fs_info->extent_root;
+       struct extent_buffer *leaf;
+       struct btrfs_extent_item *ei;
+       struct btrfs_extent_inline_ref *iref;
+       int ret;
+       int is_data;
+       int extent_slot = 0;
+       int found_extent = 0;
+       int num_to_del = 1;
+       u32 item_size;
+       u64 refs;
+       int skinny_metadata =
+               btrfs_fs_incompat(extent_root->fs_info,
+                                 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);
+
+       if (root->fs_info->free_extent_hook) {
+               root->fs_info->free_extent_hook(trans, root, bytenr, num_bytes,
+                                               parent, root_objectid, owner_objectid,
+                                               owner_offset, refs_to_drop);
+
+       }
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       path->reada = 1;
+
+       is_data = owner_objectid >= BTRFS_FIRST_FREE_OBJECTID;
+       if (is_data)
+               skinny_metadata = 0;
+       BUG_ON(!is_data && refs_to_drop != 1);
+
+       ret = lookup_extent_backref(trans, extent_root, path, &iref,
+                                   bytenr, num_bytes, parent,
+                                   root_objectid, owner_objectid,
+                                   owner_offset);
+       if (ret == 0) {
+               extent_slot = path->slots[0];
+               while (extent_slot >= 0) {
+                       btrfs_item_key_to_cpu(path->nodes[0], &key,
+                                             extent_slot);
+                       if (key.objectid != bytenr)
+                               break;
+                       if (key.type == BTRFS_EXTENT_ITEM_KEY &&
+                           key.offset == num_bytes) {
+                               found_extent = 1;
+                               break;
+                       }
+                       if (key.type == BTRFS_METADATA_ITEM_KEY &&
+                           key.offset == owner_objectid) {
+                               found_extent = 1;
+                               break;
+                       }
+                       if (path->slots[0] - extent_slot > 5)
+                               break;
+                       extent_slot--;
+               }
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+               item_size = btrfs_item_size_nr(path->nodes[0], extent_slot);
+               if (found_extent && item_size < sizeof(*ei))
+                       found_extent = 0;
+#endif
+               if (!found_extent) {
+                       BUG_ON(iref);
+                       ret = remove_extent_backref(trans, extent_root, path,
+                                                   NULL, refs_to_drop,
+                                                   is_data);
+                       BUG_ON(ret);
+                       btrfs_release_path(path);
+
+                       key.objectid = bytenr;
+
+                       if (skinny_metadata) {
+                               key.type = BTRFS_METADATA_ITEM_KEY;
+                               key.offset = owner_objectid;
+                       } else {
+                               key.type = BTRFS_EXTENT_ITEM_KEY;
+                               key.offset = num_bytes;
+                       }
+
+                       ret = btrfs_search_slot(trans, extent_root,
+                                               &key, path, -1, 1);
+                       if (ret > 0 && skinny_metadata && path->slots[0]) {
+                               path->slots[0]--;
+                               btrfs_item_key_to_cpu(path->nodes[0],
+                                                     &key,
+                                                     path->slots[0]);
+                               if (key.objectid == bytenr &&
+                                   key.type == BTRFS_EXTENT_ITEM_KEY &&
+                                   key.offset == num_bytes)
+                                       ret = 0;
+                       }
+
+                       if (ret > 0 && skinny_metadata) {
+                               skinny_metadata = 0;
+                               btrfs_release_path(path);
+                               key.type = BTRFS_EXTENT_ITEM_KEY;
+                               key.offset = num_bytes;
+                               ret = btrfs_search_slot(trans, extent_root,
+                                                       &key, path, -1, 1);
+                       }
+
+                       if (ret) {
+                               printk(KERN_ERR "umm, got %d back from search"
+                                      ", was looking for %llu\n", ret,
+                                      (unsigned long long)bytenr);
+                               btrfs_print_leaf(extent_root, path->nodes[0]);
+                       }
+                       BUG_ON(ret);
+                       extent_slot = path->slots[0];
+               }
+       } else {
+               printk(KERN_ERR "btrfs unable to find ref byte nr %llu "
+                      "parent %llu root %llu  owner %llu offset %llu\n",
+                      (unsigned long long)bytenr,
+                      (unsigned long long)parent,
+                      (unsigned long long)root_objectid,
+                      (unsigned long long)owner_objectid,
+                      (unsigned long long)owner_offset);
+               ret = -EIO;
+               goto fail;
+       }
+
+       leaf = path->nodes[0];
+       item_size = btrfs_item_size_nr(leaf, extent_slot);
+#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
+       if (item_size < sizeof(*ei)) {
+               BUG_ON(found_extent || extent_slot != path->slots[0]);
+               ret = convert_extent_item_v0(trans, extent_root, path,
+                                            owner_objectid, 0);
+               BUG_ON(ret < 0);
+
+               btrfs_release_path(path);
+
+               key.objectid = bytenr;
+               key.type = BTRFS_EXTENT_ITEM_KEY;
+               key.offset = num_bytes;
+
+               ret = btrfs_search_slot(trans, extent_root, &key, path,
+                                       -1, 1);
+               if (ret) {
+                       printk(KERN_ERR "umm, got %d back from search"
+                              ", was looking for %llu\n", ret,
+                              (unsigned long long)bytenr);
+                       btrfs_print_leaf(extent_root, path->nodes[0]);
+               }
+               BUG_ON(ret);
+               extent_slot = path->slots[0];
+               leaf = path->nodes[0];
+               item_size = btrfs_item_size_nr(leaf, extent_slot);
+       }
+#endif
+       BUG_ON(item_size < sizeof(*ei));
+       ei = btrfs_item_ptr(leaf, extent_slot,
+                           struct btrfs_extent_item);
+       if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID &&
+           key.type == BTRFS_EXTENT_ITEM_KEY) {
+               struct btrfs_tree_block_info *bi;
+               BUG_ON(item_size < sizeof(*ei) + sizeof(*bi));
+               bi = (struct btrfs_tree_block_info *)(ei + 1);
+               WARN_ON(owner_objectid != btrfs_tree_block_level(leaf, bi));
+       }
+
+       refs = btrfs_extent_refs(leaf, ei);
+       BUG_ON(refs < refs_to_drop);
+       refs -= refs_to_drop;
+
+       if (refs > 0) {
+               /*
+                * In the case of inline back ref, reference count will
+                * be updated by remove_extent_backref
+                */
+               if (iref) {
+                       BUG_ON(!found_extent);
+               } else {
+                       btrfs_set_extent_refs(leaf, ei, refs);
+                       btrfs_mark_buffer_dirty(leaf);
+               }
+               if (found_extent) {
+                       ret = remove_extent_backref(trans, extent_root, path,
+                                                   iref, refs_to_drop,
+                                                   is_data);
+                       BUG_ON(ret);
+               }
+       } else {
+               int mark_free = 0;
+               int pin = 1;
+
+               if (found_extent) {
+                       BUG_ON(is_data && refs_to_drop !=
+                              extent_data_ref_count(root, path, iref));
+                       if (iref) {
+                               BUG_ON(path->slots[0] != extent_slot);
+                       } else {
+                               BUG_ON(path->slots[0] != extent_slot + 1);
+                               path->slots[0] = extent_slot;
+                               num_to_del = 2;
+                       }
+               }
+
+               if (pin) {
+                       ret = pin_down_bytes(trans, root, bytenr, num_bytes,
+                                            is_data);
+                       if (ret > 0)
+                               mark_free = 1;
+                       BUG_ON(ret < 0);
+               }
+
+               ret = btrfs_del_items(trans, extent_root, path, path->slots[0],
+                                     num_to_del);
+               BUG_ON(ret);
+               btrfs_release_path(path);
+
+               if (is_data) {
+                       ret = btrfs_del_csums(trans, root, bytenr, num_bytes);
+                       BUG_ON(ret);
+               }
+
+               update_block_group(trans, root, bytenr, num_bytes, 0, mark_free);
+       }
+fail:
+       btrfs_free_path(path);
+       finish_current_insert(trans, extent_root);
+       return ret;
+}
+
+/*
+ * find all the blocks marked as pending in the radix tree and remove
+ * them from the extent map
+ */
+static int del_pending_extents(struct btrfs_trans_handle *trans, struct
+                              btrfs_root *extent_root)
+{
+       int ret;
+       int err = 0;
+       u64 start;
+       u64 end;
+       u64 priv;
+       struct extent_io_tree *pending_del;
+       struct extent_io_tree *extent_ins;
+       struct pending_extent_op *extent_op;
+
+       extent_ins = &extent_root->fs_info->extent_ins;
+       pending_del = &extent_root->fs_info->pending_del;
+
+       while(1) {
+               ret = find_first_extent_bit(pending_del, 0, &start, &end,
+                                           EXTENT_LOCKED);
+               if (ret)
+                       break;
+
+               ret = get_state_private(pending_del, start, &priv);
+               BUG_ON(ret);
+               extent_op = (struct pending_extent_op *)(unsigned long)priv;
+
+               clear_extent_bits(pending_del, start, end, EXTENT_LOCKED,
+                                 GFP_NOFS);
+
+               if (!test_range_bit(extent_ins, start, end,
+                                   EXTENT_LOCKED, 0)) {
+                       ret = __free_extent(trans, extent_root,
+                                           start, end + 1 - start, 0,
+                                           extent_root->root_key.objectid,
+                                           extent_op->level, 0, 1);
+                       kfree(extent_op);
+               } else {
+                       kfree(extent_op);
+                       ret = get_state_private(extent_ins, start, &priv);
+                       BUG_ON(ret);
+                       extent_op = (struct pending_extent_op *)
+                                                       (unsigned long)priv;
+
+                       clear_extent_bits(extent_ins, start, end,
+                                         EXTENT_LOCKED, GFP_NOFS);
+
+                       if (extent_op->type == PENDING_BACKREF_UPDATE)
+                               BUG_ON(1);
+
+                       kfree(extent_op);
+               }
+               if (ret)
+                       err = ret;
+       }
+       return err;
+}
+
+/*
+ * remove an extent from the root, returns 0 on success
+ */
+
+int btrfs_free_extent(struct btrfs_trans_handle *trans,
+                     struct btrfs_root *root,
+                     u64 bytenr, u64 num_bytes, u64 parent,
+                     u64 root_objectid, u64 owner, u64 offset)
+{
+       struct btrfs_root *extent_root = root->fs_info->extent_root;
+       int pending_ret;
+       int ret;
+
+       WARN_ON(num_bytes < root->sectorsize);
+       if (root == extent_root) {
+               struct pending_extent_op *extent_op;
+
+               extent_op = kmalloc(sizeof(*extent_op), GFP_NOFS);
+               BUG_ON(!extent_op);
+
+               extent_op->type = PENDING_EXTENT_DELETE;
+               extent_op->bytenr = bytenr;
+               extent_op->num_bytes = num_bytes;
+               extent_op->level = (int)owner;
+
+               set_extent_bits(&root->fs_info->pending_del,
+                               bytenr, bytenr + num_bytes - 1,
+                               EXTENT_LOCKED, GFP_NOFS);
+               set_state_private(&root->fs_info->pending_del,
+                                 bytenr, (unsigned long)extent_op);
+               return 0;
+       }
+       ret = __free_extent(trans, root, bytenr, num_bytes, parent,
+                           root_objectid, owner, offset, 1);
+       pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
+       return ret ? ret : pending_ret;
+}
+
+static u64 stripe_align(struct btrfs_root *root, u64 val)
+{
+       u64 mask = ((u64)root->stripesize - 1);
+       u64 ret = (val + mask) & ~mask;
+       return ret;
+}
+
+/*
+ * walks the btree of allocated extents and find a hole of a given size.
+ * The key ins is changed to record the hole:
+ * ins->objectid == block start
+ * ins->flags = BTRFS_EXTENT_ITEM_KEY
+ * ins->offset == number of blocks
+ * Any available blocks before search_start are skipped.
+ */
+static int noinline find_free_extent(struct btrfs_trans_handle *trans,
+                                    struct btrfs_root *orig_root,
+                                    u64 num_bytes, u64 empty_size,
+                                    u64 search_start, u64 search_end,
+                                    u64 hint_byte, struct btrfs_key *ins,
+                                    u64 exclude_start, u64 exclude_nr,
+                                    int data)
+{
+       int ret;
+       u64 orig_search_start = search_start;
+       struct btrfs_root * root = orig_root->fs_info->extent_root;
+       struct btrfs_fs_info *info = root->fs_info;
+       u64 total_needed = num_bytes;
+       struct btrfs_block_group_cache *block_group;
+       int full_scan = 0;
+       int wrapped = 0;
+
+       WARN_ON(num_bytes < root->sectorsize);
+       ins->type = BTRFS_EXTENT_ITEM_KEY;
+
+       search_start = stripe_align(root, search_start);
+
+       if (hint_byte) {
+               block_group = btrfs_lookup_first_block_group(info, hint_byte);
+               if (!block_group)
+                       hint_byte = search_start;
+               block_group = btrfs_find_block_group(root, block_group,
+                                                    hint_byte, data, 1);
+       } else {
+               block_group = btrfs_find_block_group(root,
+                                                    trans->block_group,
+                                                    search_start, data, 1);
+       }
+
+       total_needed += empty_size;
+
+check_failed:
+       search_start = stripe_align(root, search_start);
+       if (!block_group) {
+               block_group = btrfs_lookup_first_block_group(info,
+                                                            search_start);
+               if (!block_group)
+                       block_group = btrfs_lookup_first_block_group(info,
+                                                      orig_search_start);
+       }
+       ret = find_search_start(root, &block_group, &search_start,
+                               total_needed, data);
+       if (ret)
+               goto new_group;
+
+       ins->objectid = search_start;
+       ins->offset = num_bytes;
+
+       if (ins->objectid + num_bytes >
+           block_group->key.objectid + block_group->key.offset) {
+               search_start = block_group->key.objectid +
+                       block_group->key.offset;
+               goto new_group;
+       }
+
+       if (test_range_bit(&info->extent_ins, ins->objectid,
+                          ins->objectid + num_bytes -1, EXTENT_LOCKED, 0)) {
+               search_start = ins->objectid + num_bytes;
+               goto new_group;
+       }
+
+       if (test_range_bit(&info->pinned_extents, ins->objectid,
+                          ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
+               search_start = ins->objectid + num_bytes;
+               goto new_group;
+       }
+
+       if (info->excluded_extents &&
+           test_range_bit(info->excluded_extents, ins->objectid,
+                          ins->objectid + num_bytes -1, EXTENT_DIRTY, 0)) {
+               search_start = ins->objectid + num_bytes;
+               goto new_group;
+       }
+
+       if (exclude_nr > 0 && (ins->objectid + num_bytes > exclude_start &&
+           ins->objectid < exclude_start + exclude_nr)) {
+               search_start = exclude_start + exclude_nr;
+               goto new_group;
+       }
+
+       if (!(data & BTRFS_BLOCK_GROUP_DATA)) {
+               if (check_crossing_stripes(info, ins->objectid, num_bytes)) {
+                       struct btrfs_block_group_cache *bg_cache;
+                       u64 bg_offset;
+
+                       bg_cache = btrfs_lookup_block_group(info, ins->objectid);
+                       if (!bg_cache)
+                               goto no_bg_cache;
+                       bg_offset = ins->objectid - bg_cache->key.objectid;
+
+                       search_start = round_up(bg_offset + num_bytes,
+                                               BTRFS_STRIPE_LEN) + bg_offset;
+                       goto new_group;
+               }
+no_bg_cache:
+               block_group = btrfs_lookup_block_group(info, ins->objectid);
+               if (block_group)
+                       trans->block_group = block_group;
+       }
+       ins->offset = num_bytes;
+       return 0;
+
+new_group:
+       block_group = btrfs_lookup_first_block_group(info, search_start);
+       if (!block_group) {
+               search_start = orig_search_start;
+               if (full_scan) {
+                       ret = -ENOSPC;
+                       goto error;
+               }
+               if (wrapped) {
+                       if (!full_scan)
+                               total_needed -= empty_size;
+                       full_scan = 1;
+               } else
+                       wrapped = 1;
+       }
+       cond_resched();
+       block_group = btrfs_find_block_group(root, block_group,
+                                            search_start, data, 0);
+       goto check_failed;
+
+error:
+       return ret;
+}
+
+int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
+                        struct btrfs_root *root,
+                        u64 num_bytes, u64 empty_size,
+                        u64 hint_byte, u64 search_end,
+                        struct btrfs_key *ins, int data)
+{
+       int ret;
+       u64 search_start = 0;
+       u64 alloc_profile;
+       struct btrfs_fs_info *info = root->fs_info;
+
+       if (data) {
+               alloc_profile = info->avail_data_alloc_bits &
+                               info->data_alloc_profile;
+               data = BTRFS_BLOCK_GROUP_DATA | alloc_profile;
+       } else if ((info->system_allocs > 0 || root == info->chunk_root) &&
+                  info->system_allocs >= 0) {
+               alloc_profile = info->avail_system_alloc_bits &
+                               info->system_alloc_profile;
+               data = BTRFS_BLOCK_GROUP_SYSTEM | alloc_profile;
+       } else {
+               alloc_profile = info->avail_metadata_alloc_bits &
+                               info->metadata_alloc_profile;
+               data = BTRFS_BLOCK_GROUP_METADATA | alloc_profile;
+       }
+
+       if (root->ref_cows) {
+               if (!(data & BTRFS_BLOCK_GROUP_METADATA)) {
+                       ret = do_chunk_alloc(trans, root->fs_info->extent_root,
+                                            num_bytes,
+                                            BTRFS_BLOCK_GROUP_METADATA);
+                       BUG_ON(ret);
+               }
+               ret = do_chunk_alloc(trans, root->fs_info->extent_root,
+                                    num_bytes + 2 * 1024 * 1024, data);
+               BUG_ON(ret);
+       }
+
+       WARN_ON(num_bytes < root->sectorsize);
+       ret = find_free_extent(trans, root, num_bytes, empty_size,
+                              search_start, search_end, hint_byte, ins,
+                              trans->alloc_exclude_start,
+                              trans->alloc_exclude_nr, data);
+       BUG_ON(ret);
+       clear_extent_dirty(&root->fs_info->free_space_cache,
+                          ins->objectid, ins->objectid + ins->offset - 1,
+                          GFP_NOFS);
+       return ret;
+}
+
+static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
+                                    struct btrfs_root *root,
+                                    u64 root_objectid, u64 generation,
+                                    u64 flags, struct btrfs_disk_key *key,
+                                    int level, struct btrfs_key *ins)
+{
+       int ret;
+       struct btrfs_fs_info *fs_info = root->fs_info;
+       struct btrfs_extent_item *extent_item;
+       struct btrfs_tree_block_info *block_info;
+       struct btrfs_extent_inline_ref *iref;
+       struct btrfs_path *path;
+       struct extent_buffer *leaf;
+       u32 size = sizeof(*extent_item) + sizeof(*iref);
+       int skinny_metadata =
+               btrfs_fs_incompat(fs_info,
+                                 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA);
+
+       if (!skinny_metadata)
+               size += sizeof(*block_info);
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
+                                     ins, size);
+       BUG_ON(ret);
+
+       leaf = path->nodes[0];
+       extent_item = btrfs_item_ptr(leaf, path->slots[0],
+                                    struct btrfs_extent_item);
+       btrfs_set_extent_refs(leaf, extent_item, 1);
+       btrfs_set_extent_generation(leaf, extent_item, generation);
+       btrfs_set_extent_flags(leaf, extent_item,
+                              flags | BTRFS_EXTENT_FLAG_TREE_BLOCK);
+
+       if (skinny_metadata) {
+               iref = (struct btrfs_extent_inline_ref *)(extent_item + 1);
+       } else {
+               block_info = (struct btrfs_tree_block_info *)(extent_item + 1);
+               btrfs_set_tree_block_key(leaf, block_info, key);
+               btrfs_set_tree_block_level(leaf, block_info, level);
+               iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
+       }
+
+       btrfs_set_extent_inline_ref_type(leaf, iref, BTRFS_TREE_BLOCK_REF_KEY);
+       btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
+
+       btrfs_mark_buffer_dirty(leaf);
+       btrfs_free_path(path);
+
+       ret = update_block_group(trans, root, ins->objectid, root->nodesize,
+                                1, 0);
+       return ret;
+}
+
+static int alloc_tree_block(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root, u64 num_bytes,
+                           u64 root_objectid, u64 generation,
+                           u64 flags, struct btrfs_disk_key *key,
+                           int level, u64 empty_size, u64 hint_byte,
+                           u64 search_end, struct btrfs_key *ins)
+{
+       int ret;
+       ret = btrfs_reserve_extent(trans, root, num_bytes, empty_size,
+                                  hint_byte, search_end, ins, 0);
+       BUG_ON(ret);
+
+       if (root_objectid == BTRFS_EXTENT_TREE_OBJECTID) {
+               struct pending_extent_op *extent_op;
+
+               extent_op = kmalloc(sizeof(*extent_op), GFP_NOFS);
+               BUG_ON(!extent_op);
+
+               extent_op->type = PENDING_EXTENT_INSERT;
+               extent_op->bytenr = ins->objectid;
+               extent_op->num_bytes = ins->offset;
+               extent_op->level = level;
+               extent_op->flags = flags;
+               memcpy(&extent_op->key, key, sizeof(*key));
+
+               set_extent_bits(&root->fs_info->extent_ins, ins->objectid,
+                               ins->objectid + ins->offset - 1,
+                               EXTENT_LOCKED, GFP_NOFS);
+               set_state_private(&root->fs_info->extent_ins,
+                                 ins->objectid, (unsigned long)extent_op);
+       } else {
+               if (btrfs_fs_incompat(root->fs_info,
+                               BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)) {
+                       ins->offset = level;
+                       ins->type = BTRFS_METADATA_ITEM_KEY;
+               }
+               ret = alloc_reserved_tree_block(trans, root, root_objectid,
+                                               generation, flags,
+                                               key, level, ins);
+               finish_current_insert(trans, root->fs_info->extent_root);
+               del_pending_extents(trans, root->fs_info->extent_root);
+       }
+       return ret;
+}
+
+/*
+ * helper function to allocate a block for a given tree
+ * returns the tree buffer or NULL.
+ */
+struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
+                                       struct btrfs_root *root,
+                                       u32 blocksize, u64 root_objectid,
+                                       struct btrfs_disk_key *key, int level,
+                                       u64 hint, u64 empty_size)
+{
+       struct btrfs_key ins;
+       int ret;
+       struct extent_buffer *buf;
+
+       ret = alloc_tree_block(trans, root, blocksize, root_objectid,
+                              trans->transid, 0, key, level,
+                              empty_size, hint, (u64)-1, &ins);
+       if (ret) {
+               BUG_ON(ret > 0);
+               return ERR_PTR(ret);
+       }
+
+       buf = btrfs_find_create_tree_block(root->fs_info, ins.objectid,
+                                          blocksize);
+       if (!buf) {
+               btrfs_free_extent(trans, root, ins.objectid, ins.offset,
+                                 0, root->root_key.objectid, level, 0);
+               BUG_ON(1);
+               return ERR_PTR(-ENOMEM);
+       }
+       btrfs_set_buffer_uptodate(buf);
+       trans->blocks_used++;
+
+       return buf;
+}
+
+#if 0
+
+static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans,
+                                 struct btrfs_root *root,
+                                 struct extent_buffer *leaf)
+{
+       u64 leaf_owner;
+       u64 leaf_generation;
+       struct btrfs_key key;
+       struct btrfs_file_extent_item *fi;
+       int i;
+       int nritems;
+       int ret;
+
+       BUG_ON(!btrfs_is_leaf(leaf));
+       nritems = btrfs_header_nritems(leaf);
+       leaf_owner = btrfs_header_owner(leaf);
+       leaf_generation = btrfs_header_generation(leaf);
+
+       for (i = 0; i < nritems; i++) {
+               u64 disk_bytenr;
+
+               btrfs_item_key_to_cpu(leaf, &key, i);
+               if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
+                       continue;
                fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
                if (btrfs_file_extent_type(leaf, fi) ==
                    BTRFS_FILE_EXTENT_INLINE)
@@ -1844,505 +2877,1379 @@ static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans,
                        continue;
                ret = btrfs_free_extent(trans, root, disk_bytenr,
                                btrfs_file_extent_disk_num_bytes(leaf, fi),
-                               leaf_owner, leaf_generation,
-                               key.objectid, key.offset, 0);
+                               leaf->start, leaf_owner, leaf_generation,
+                               key.objectid, 0);
+               BUG_ON(ret);
+       }
+       return 0;
+}
+
+static void noinline reada_walk_down(struct btrfs_root *root,
+                                    struct extent_buffer *node,
+                                    int slot)
+{
+       u64 bytenr;
+       u64 last = 0;
+       u32 nritems;
+       u32 refs;
+       u32 blocksize;
+       int ret;
+       int i;
+       int level;
+       int skipped = 0;
+
+       nritems = btrfs_header_nritems(node);
+       level = btrfs_header_level(node);
+       if (level)
+               return;
+
+       for (i = slot; i < nritems && skipped < 32; i++) {
+               bytenr = btrfs_node_blockptr(node, i);
+               if (last && ((bytenr > last && bytenr - last > 32 * 1024) ||
+                            (last > bytenr && last - bytenr > 32 * 1024))) {
+                       skipped++;
+                       continue;
+               }
+               blocksize = btrfs_level_size(root, level - 1);
+               if (i != slot) {
+                       ret = btrfs_lookup_extent_ref(NULL, root, bytenr,
+                                                     blocksize, &refs);
+                       BUG_ON(ret);
+                       if (refs != 1) {
+                               skipped++;
+                               continue;
+                       }
+               }
+               mutex_unlock(&root->fs_info->fs_mutex);
+               ret = readahead_tree_block(root, bytenr, blocksize,
+                                          btrfs_node_ptr_generation(node, i));
+               last = bytenr + blocksize;
+               cond_resched();
+               mutex_lock(&root->fs_info->fs_mutex);
+               if (ret)
+                       break;
+       }
+}
+
+/*
+ * helper function for drop_snapshot, this walks down the tree dropping ref
+ * counts as it goes.
+ */
+static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
+                                  struct btrfs_root *root,
+                                  struct btrfs_path *path, int *level)
+{
+       u64 root_owner;
+       u64 root_gen;
+       u64 bytenr;
+       u64 ptr_gen;
+       struct extent_buffer *next;
+       struct extent_buffer *cur;
+       struct extent_buffer *parent;
+       u32 blocksize;
+       int ret;
+       u32 refs;
+
+       WARN_ON(*level < 0);
+       WARN_ON(*level >= BTRFS_MAX_LEVEL);
+       ret = btrfs_lookup_extent_ref(trans, root,
+                                     path->nodes[*level]->start,
+                                     path->nodes[*level]->len, &refs);
+       BUG_ON(ret);
+       if (refs > 1)
+               goto out;
+
+       /*
+        * walk down to the last node level and free all the leaves
+        */
+       while(*level >= 0) {
+               WARN_ON(*level < 0);
+               WARN_ON(*level >= BTRFS_MAX_LEVEL);
+               cur = path->nodes[*level];
+
+               if (btrfs_header_level(cur) != *level)
+                       WARN_ON(1);
+
+               if (path->slots[*level] >=
+                   btrfs_header_nritems(cur))
+                       break;
+               if (*level == 0) {
+                       ret = drop_leaf_ref(trans, root, cur);
+                       BUG_ON(ret);
+                       break;
+               }
+               bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
+               ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
+               blocksize = btrfs_level_size(root, *level - 1);
+               ret = btrfs_lookup_extent_ref(trans, root, bytenr, blocksize,
+                                             &refs);
+               BUG_ON(ret);
+               if (refs != 1) {
+                       parent = path->nodes[*level];
+                       root_owner = btrfs_header_owner(parent);
+                       root_gen = btrfs_header_generation(parent);
+                       path->slots[*level]++;
+                       ret = btrfs_free_extent(trans, root, bytenr, blocksize,
+                                               parent->start, root_owner,
+                                               root_gen, *level - 1, 1);
+                       BUG_ON(ret);
+                       continue;
+               }
+               next = btrfs_find_tree_block(root, bytenr, blocksize);
+               if (!next || !btrfs_buffer_uptodate(next, ptr_gen)) {
+                       free_extent_buffer(next);
+                       reada_walk_down(root, cur, path->slots[*level]);
+                       mutex_unlock(&root->fs_info->fs_mutex);
+                       next = read_tree_block(root, bytenr, blocksize,
+                                              ptr_gen);
+                       mutex_lock(&root->fs_info->fs_mutex);
+                       if (!extent_buffer_uptodate(next)) {
+                               if (IS_ERR(next))
+                                       ret = PTR_ERR(next);
+                               else
+                                       ret = -EIO;
+                               break;
+                       }
+               }
+               WARN_ON(*level <= 0);
+               if (path->nodes[*level-1])
+                       free_extent_buffer(path->nodes[*level-1]);
+               path->nodes[*level-1] = next;
+               *level = btrfs_header_level(next);
+               path->slots[*level] = 0;
+       }
+out:
+       WARN_ON(*level < 0);
+       WARN_ON(*level >= BTRFS_MAX_LEVEL);
+
+       if (path->nodes[*level] == root->node) {
+               root_owner = root->root_key.objectid;
+               parent = path->nodes[*level];
+       } else {
+               parent = path->nodes[*level + 1];
+               root_owner = btrfs_header_owner(parent);
+       }
+
+       root_gen = btrfs_header_generation(parent);
+       ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
+                               path->nodes[*level]->len, parent->start,
+                               root_owner, root_gen, *level, 1);
+       free_extent_buffer(path->nodes[*level]);
+       path->nodes[*level] = NULL;
+       *level += 1;
+       BUG_ON(ret);
+       return 0;
+}
+
+/*
+ * helper for dropping snapshots.  This walks back up the tree in the path
+ * to find the first node higher up where we haven't yet gone through
+ * all the slots
+ */
+static int noinline walk_up_tree(struct btrfs_trans_handle *trans,
+                                struct btrfs_root *root,
+                                struct btrfs_path *path, int *level)
+{
+       u64 root_owner;
+       u64 root_gen;
+       struct btrfs_root_item *root_item = &root->root_item;
+       int i;
+       int slot;
+       int ret;
+
+       for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
+               slot = path->slots[i];
+               if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
+                       struct extent_buffer *node;
+                       struct btrfs_disk_key disk_key;
+                       node = path->nodes[i];
+                       path->slots[i]++;
+                       *level = i;
+                       WARN_ON(*level == 0);
+                       btrfs_node_key(node, &disk_key, path->slots[i]);
+                       memcpy(&root_item->drop_progress,
+                              &disk_key, sizeof(disk_key));
+                       root_item->drop_level = i;
+                       return 0;
+               } else {
+                       struct extent_buffer *parent;
+                       if (path->nodes[*level] == root->node)
+                               parent = path->nodes[*level];
+                       else
+                               parent = path->nodes[*level + 1];
+
+                       root_owner = btrfs_header_owner(parent);
+                       root_gen = btrfs_header_generation(parent);
+                       ret = btrfs_free_extent(trans, root,
+                                               path->nodes[*level]->start,
+                                               path->nodes[*level]->len,
+                                               parent->start, root_owner,
+                                               root_gen, *level, 1);
+                       BUG_ON(ret);
+                       free_extent_buffer(path->nodes[*level]);
+                       path->nodes[*level] = NULL;
+                       *level = i + 1;
+               }
+       }
+       return 1;
+}
+
+#endif
+
+int btrfs_free_block_groups(struct btrfs_fs_info *info)
+{
+       struct btrfs_space_info *sinfo;
+       struct btrfs_block_group_cache *cache;
+       u64 start;
+       u64 end;
+       u64 ptr;
+       int ret;
+
+       while(1) {
+               ret = find_first_extent_bit(&info->block_group_cache, 0,
+                                           &start, &end, (unsigned int)-1);
+               if (ret)
+                       break;
+               ret = get_state_private(&info->block_group_cache, start, &ptr);
+               if (!ret) {
+                       cache = u64_to_ptr(ptr);
+                       if (cache->free_space_ctl) {
+                               btrfs_remove_free_space_cache(cache);
+                               kfree(cache->free_space_ctl);
+                       }
+                       kfree(cache);
+               }
+               clear_extent_bits(&info->block_group_cache, start,
+                                 end, (unsigned int)-1, GFP_NOFS);
+       }
+       while(1) {
+               ret = find_first_extent_bit(&info->free_space_cache, 0,
+                                           &start, &end, EXTENT_DIRTY);
+               if (ret)
+                       break;
+               clear_extent_dirty(&info->free_space_cache, start,
+                                  end, GFP_NOFS);
+       }
+
+       while (!list_empty(&info->space_info)) {
+               sinfo = list_entry(info->space_info.next,
+                                  struct btrfs_space_info, list);
+               list_del_init(&sinfo->list);
+               kfree(sinfo);
+       }
+       return 0;
+}
+
+static int find_first_block_group(struct btrfs_root *root,
+               struct btrfs_path *path, struct btrfs_key *key)
+{
+       int ret;
+       struct btrfs_key found_key;
+       struct extent_buffer *leaf;
+       int slot;
+
+       ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+       if (ret < 0)
+               return ret;
+       while(1) {
+               slot = path->slots[0];
+               leaf = path->nodes[0];
+               if (slot >= btrfs_header_nritems(leaf)) {
+                       ret = btrfs_next_leaf(root, path);
+                       if (ret == 0)
+                               continue;
+                       if (ret < 0)
+                               goto error;
+                       break;
+               }
+               btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+               if (found_key.objectid >= key->objectid &&
+                   found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY)
+                       return 0;
+               path->slots[0]++;
+       }
+       ret = -ENOENT;
+error:
+       return ret;
+}
+
+static void account_super_bytes(struct btrfs_fs_info *fs_info,
+                               struct btrfs_block_group_cache *cache)
+{
+       u64 bytenr;
+       u64 *logical;
+       int stripe_len;
+       int i, nr, ret;
+
+       if (cache->key.objectid < BTRFS_SUPER_INFO_OFFSET) {
+               stripe_len = BTRFS_SUPER_INFO_OFFSET - cache->key.objectid;
+               cache->bytes_super += stripe_len;
+       }
+
+       for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+               bytenr = btrfs_sb_offset(i);
+               ret = btrfs_rmap_block(&fs_info->mapping_tree,
+                                      cache->key.objectid, bytenr,
+                                      0, &logical, &nr, &stripe_len);
+               if (ret)
+                       return;
+
+               while (nr--) {
+                       u64 start, len;
+
+                       if (logical[nr] > cache->key.objectid +
+                           cache->key.offset)
+                               continue;
+
+                       if (logical[nr] + stripe_len <= cache->key.objectid)
+                               continue;
+
+                       start = logical[nr];
+                       if (start < cache->key.objectid) {
+                               start = cache->key.objectid;
+                               len = (logical[nr] + stripe_len) - start;
+                       } else {
+                               len = min_t(u64, stripe_len,
+                                           cache->key.objectid +
+                                           cache->key.offset - start);
+                       }
+
+                       cache->bytes_super += len;
+               }
+
+               kfree(logical);
+       }
+}
+
+int btrfs_read_block_groups(struct btrfs_root *root)
+{
+       struct btrfs_path *path;
+       int ret;
+       int bit;
+       struct btrfs_block_group_cache *cache;
+       struct btrfs_fs_info *info = root->fs_info;
+       struct btrfs_space_info *space_info;
+       struct extent_io_tree *block_group_cache;
+       struct btrfs_key key;
+       struct btrfs_key found_key;
+       struct extent_buffer *leaf;
+
+       block_group_cache = &info->block_group_cache;
+
+       root = info->extent_root;
+       key.objectid = 0;
+       key.offset = 0;
+       key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       while(1) {
+               ret = find_first_block_group(root, path, &key);
+               if (ret > 0) {
+                       ret = 0;
+                       goto error;
+               }
+               if (ret != 0) {
+                       goto error;
+               }
+               leaf = path->nodes[0];
+               btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+               cache = kzalloc(sizeof(*cache), GFP_NOFS);
+               if (!cache) {
+                       ret = -ENOMEM;
+                       goto error;
+               }
+
+               read_extent_buffer(leaf, &cache->item,
+                                  btrfs_item_ptr_offset(leaf, path->slots[0]),
+                                  sizeof(cache->item));
+               memcpy(&cache->key, &found_key, sizeof(found_key));
+               cache->cached = 0;
+               cache->pinned = 0;
+               key.objectid = found_key.objectid + found_key.offset;
+               if (found_key.offset == 0)
+                       key.objectid++;
+               btrfs_release_path(path);
+               cache->flags = btrfs_block_group_flags(&cache->item);
+               bit = 0;
+               if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
+                       bit = BLOCK_GROUP_DATA;
+               } else if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
+                       bit = BLOCK_GROUP_SYSTEM;
+               } else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
+                       bit = BLOCK_GROUP_METADATA;
+               }
+               set_avail_alloc_bits(info, cache->flags);
+               if (btrfs_chunk_readonly(root, cache->key.objectid))
+                       cache->ro = 1;
+
+               account_super_bytes(info, cache);
+
+               ret = update_space_info(info, cache->flags, found_key.offset,
+                                       btrfs_block_group_used(&cache->item),
+                                       &space_info);
+               BUG_ON(ret);
+               cache->space_info = space_info;
+
+               /* use EXTENT_LOCKED to prevent merging */
+               set_extent_bits(block_group_cache, found_key.objectid,
+                               found_key.objectid + found_key.offset - 1,
+                               bit | EXTENT_LOCKED, GFP_NOFS);
+               set_state_private(block_group_cache, found_key.objectid,
+                                 (unsigned long)cache);
+       }
+       ret = 0;
+error:
+       btrfs_free_path(path);
+       return ret;
+}
+
+struct btrfs_block_group_cache *
+btrfs_add_block_group(struct btrfs_fs_info *fs_info, u64 bytes_used, u64 type,
+                     u64 chunk_objectid, u64 chunk_offset, u64 size)
+{
+       int ret;
+       int bit = 0;
+       struct btrfs_block_group_cache *cache;
+       struct extent_io_tree *block_group_cache;
+
+       block_group_cache = &fs_info->block_group_cache;
+
+       cache = kzalloc(sizeof(*cache), GFP_NOFS);
+       BUG_ON(!cache);
+       cache->key.objectid = chunk_offset;
+       cache->key.offset = size;
+
+       cache->key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+       btrfs_set_block_group_used(&cache->item, bytes_used);
+       btrfs_set_block_group_chunk_objectid(&cache->item, chunk_objectid);
+       cache->flags = type;
+       btrfs_set_block_group_flags(&cache->item, type);
+
+       account_super_bytes(fs_info, cache);
+       ret = update_space_info(fs_info, cache->flags, size, bytes_used,
+                               &cache->space_info);
+       BUG_ON(ret);
+
+       bit = block_group_state_bits(type);
+       ret = set_extent_bits(block_group_cache, chunk_offset,
+                             chunk_offset + size - 1,
+                             bit | EXTENT_LOCKED, GFP_NOFS);
+       BUG_ON(ret);
+
+       ret = set_state_private(block_group_cache, chunk_offset,
+                               (unsigned long)cache);
+       BUG_ON(ret);
+       set_avail_alloc_bits(fs_info, type);
+
+       return cache;
+}
+
+int btrfs_make_block_group(struct btrfs_trans_handle *trans,
+                          struct btrfs_root *root, u64 bytes_used,
+                          u64 type, u64 chunk_objectid, u64 chunk_offset,
+                          u64 size)
+{
+       int ret;
+       struct btrfs_root *extent_root;
+       struct btrfs_block_group_cache *cache;
+
+       cache = btrfs_add_block_group(root->fs_info, bytes_used, type,
+                                     chunk_objectid, chunk_offset, size);
+       extent_root = root->fs_info->extent_root;
+       ret = btrfs_insert_item(trans, extent_root, &cache->key, &cache->item,
+                               sizeof(cache->item));
+       BUG_ON(ret);
+
+       ret = finish_current_insert(trans, extent_root);
+       BUG_ON(ret);
+       ret = del_pending_extents(trans, extent_root);
+       BUG_ON(ret);
+
+       return 0;
+}
+
+/*
+ * This is for converter use only.
+ *
+ * In that case, we don't know where are free blocks located.
+ * Therefore all block group cache entries must be setup properly
+ * before doing any block allocation.
+ */
+int btrfs_make_block_groups(struct btrfs_trans_handle *trans,
+                           struct btrfs_root *root)
+{
+       u64 total_bytes;
+       u64 cur_start;
+       u64 group_type;
+       u64 group_size;
+       u64 group_align;
+       u64 total_data = 0;
+       u64 total_metadata = 0;
+       u64 chunk_objectid;
+       int ret;
+       int bit;
+       struct btrfs_root *extent_root;
+       struct btrfs_block_group_cache *cache;
+       struct extent_io_tree *block_group_cache;
+
+       extent_root = root->fs_info->extent_root;
+       block_group_cache = &root->fs_info->block_group_cache;
+       chunk_objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+       total_bytes = btrfs_super_total_bytes(root->fs_info->super_copy);
+       group_align = 64 * root->sectorsize;
+
+       cur_start = 0;
+       while (cur_start < total_bytes) {
+               group_size = total_bytes / 12;
+               group_size = min_t(u64, group_size, total_bytes - cur_start);
+               if (cur_start == 0) {
+                       bit = BLOCK_GROUP_SYSTEM;
+                       group_type = BTRFS_BLOCK_GROUP_SYSTEM;
+                       group_size /= 4;
+                       group_size &= ~(group_align - 1);
+                       group_size = max_t(u64, group_size, 8 * 1024 * 1024);
+                       group_size = min_t(u64, group_size, 32 * 1024 * 1024);
+               } else {
+                       group_size &= ~(group_align - 1);
+                       if (total_data >= total_metadata * 2) {
+                               group_type = BTRFS_BLOCK_GROUP_METADATA;
+                               group_size = min_t(u64, group_size,
+                                                  1ULL * 1024 * 1024 * 1024);
+                               total_metadata += group_size;
+                       } else {
+                               group_type = BTRFS_BLOCK_GROUP_DATA;
+                               group_size = min_t(u64, group_size,
+                                                  5ULL * 1024 * 1024 * 1024);
+                               total_data += group_size;
+                       }
+                       if ((total_bytes - cur_start) * 4 < group_size * 5)
+                               group_size = total_bytes - cur_start;
+               }
+
+               cache = kzalloc(sizeof(*cache), GFP_NOFS);
+               BUG_ON(!cache);
+
+               cache->key.objectid = cur_start;
+               cache->key.offset = group_size;
+               cache->key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+
+               btrfs_set_block_group_used(&cache->item, 0);
+               btrfs_set_block_group_chunk_objectid(&cache->item,
+                                                    chunk_objectid);
+               btrfs_set_block_group_flags(&cache->item, group_type);
+
+               cache->flags = group_type;
+
+               ret = update_space_info(root->fs_info, group_type, group_size,
+                                       0, &cache->space_info);
+               BUG_ON(ret);
+               set_avail_alloc_bits(extent_root->fs_info, group_type);
+
+               set_extent_bits(block_group_cache, cur_start,
+                               cur_start + group_size - 1,
+                               bit | EXTENT_LOCKED, GFP_NOFS);
+               set_state_private(block_group_cache, cur_start,
+                                 (unsigned long)cache);
+               cur_start += group_size;
+       }
+       /* then insert all the items */
+       cur_start = 0;
+       while(cur_start < total_bytes) {
+               cache = btrfs_lookup_block_group(root->fs_info, cur_start);
+               BUG_ON(!cache);
+
+               ret = btrfs_insert_item(trans, extent_root, &cache->key, &cache->item,
+                                       sizeof(cache->item));
                BUG_ON(ret);
+
+               finish_current_insert(trans, extent_root);
+               ret = del_pending_extents(trans, extent_root);
+               BUG_ON(ret);
+
+               cur_start = cache->key.objectid + cache->key.offset;
+       }
+       return 0;
+}
+
+int btrfs_update_block_group(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root,
+                            u64 bytenr, u64 num_bytes, int alloc,
+                            int mark_free)
+{
+       return update_block_group(trans, root, bytenr, num_bytes,
+                                 alloc, mark_free);
+}
+
+/*
+ * Just remove a block group item in extent tree
+ * Caller should ensure the block group is empty and all space is pinned.
+ * Or new tree block/data may be allocated into it.
+ */
+static int free_block_group_item(struct btrfs_trans_handle *trans,
+                                struct btrfs_fs_info *fs_info,
+                                u64 bytenr, u64 len)
+{
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       struct btrfs_root *root = fs_info->extent_root;
+       int ret = 0;
+
+       key.objectid = bytenr;
+       key.offset = len;
+       key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+       if (ret < 0)
+               goto out;
+
+       ret = btrfs_del_item(trans, root, path);
+out:
+       btrfs_free_path(path);
+       return ret;
+}
+
+static int free_dev_extent_item(struct btrfs_trans_handle *trans,
+                               struct btrfs_fs_info *fs_info,
+                               u64 devid, u64 dev_offset)
+{
+       struct btrfs_root *root = fs_info->dev_root;
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       int ret;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = devid;
+       key.type = BTRFS_DEV_EXTENT_KEY;
+       key.offset = dev_offset;
+
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret < 0)
+               goto out;
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+
+       ret = btrfs_del_item(trans, root, path);
+out:
+       btrfs_free_path(path);
+       return ret;
+}
+
+static int free_chunk_dev_extent_items(struct btrfs_trans_handle *trans,
+                                      struct btrfs_fs_info *fs_info,
+                                      u64 chunk_offset)
+{
+       struct btrfs_chunk *chunk = NULL;
+       struct btrfs_root *root= fs_info->chunk_root;
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       u16 num_stripes;
+       int i;
+       int ret;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+       key.type = BTRFS_CHUNK_ITEM_KEY;
+       key.offset = chunk_offset;
+
+       ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
+       if (ret < 0)
+               goto out;
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+       chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                              struct btrfs_chunk);
+       num_stripes = btrfs_chunk_num_stripes(path->nodes[0], chunk);
+       for (i = 0; i < num_stripes; i++) {
+               ret = free_dev_extent_item(trans, fs_info,
+                       btrfs_stripe_devid_nr(path->nodes[0], chunk, i),
+                       btrfs_stripe_offset_nr(path->nodes[0], chunk, i));
+               if (ret < 0)
+                       goto out;
        }
-       return 0;
+out:
+       btrfs_free_path(path);
+       return ret;
 }
 
-static void noinline reada_walk_down(struct btrfs_root *root,
-                                    struct extent_buffer *node,
-                                    int slot)
+static int free_system_chunk_item(struct btrfs_super_block *super,
+                                 struct btrfs_key *key)
 {
-       u64 bytenr;
-       u64 last = 0;
-       u32 nritems;
-       u32 refs;
-       u32 blocksize;
-       int ret;
-       int i;
-       int level;
-       int skipped = 0;
-
-       nritems = btrfs_header_nritems(node);
-       level = btrfs_header_level(node);
-       if (level)
-               return;
-
-       for (i = slot; i < nritems && skipped < 32; i++) {
-               bytenr = btrfs_node_blockptr(node, i);
-               if (last && ((bytenr > last && bytenr - last > 32 * 1024) ||
-                            (last > bytenr && last - bytenr > 32 * 1024))) {
-                       skipped++;
-                       continue;
+       struct btrfs_disk_key *disk_key;
+       struct btrfs_key cpu_key;
+       u32 array_size = btrfs_super_sys_array_size(super);
+       char *ptr = (char *)super->sys_chunk_array;
+       int cur = 0;
+       int ret = -ENOENT;
+
+       while (cur < btrfs_super_sys_array_size(super)) {
+               struct btrfs_chunk *chunk;
+               u32 num_stripes;
+               u32 chunk_len;
+
+               disk_key = (struct btrfs_disk_key *)(ptr + cur);
+               btrfs_disk_key_to_cpu(&cpu_key, disk_key);
+               if (cpu_key.type != BTRFS_CHUNK_ITEM_KEY) {
+                       /* just in case */
+                       ret = -EIO;
+                       goto out;
                }
-               blocksize = btrfs_level_size(root, level - 1);
-               if (i != slot) {
-                       ret = lookup_extent_ref(NULL, root, bytenr,
-                                               blocksize, &refs);
-                       BUG_ON(ret);
-                       if (refs != 1) {
-                               skipped++;
-                               continue;
-                       }
+
+               chunk = (struct btrfs_chunk *)(ptr + cur + sizeof(*disk_key));
+               num_stripes = btrfs_stack_chunk_num_stripes(chunk);
+               chunk_len = btrfs_chunk_item_size(num_stripes) +
+                           sizeof(*disk_key);
+
+               if (key->objectid == cpu_key.objectid &&
+                   key->offset == cpu_key.offset &&
+                   key->type == cpu_key.type) {
+                       memmove(ptr + cur, ptr + cur + chunk_len,
+                               array_size - cur - chunk_len);
+                       array_size -= chunk_len;
+                       btrfs_set_super_sys_array_size(super, array_size);
+                       ret = 0;
+                       goto out;
                }
-               mutex_unlock(&root->fs_info->fs_mutex);
-               ret = readahead_tree_block(root, bytenr, blocksize);
-               last = bytenr + blocksize;
-               cond_resched();
-               mutex_lock(&root->fs_info->fs_mutex);
-               if (ret)
-                       break;
+
+               cur += chunk_len;
        }
+out:
+       return ret;
 }
 
-/*
- * helper function for drop_snapshot, this walks down the tree dropping ref
- * counts as it goes.
- */
-static int noinline walk_down_tree(struct btrfs_trans_handle *trans,
-                                  struct btrfs_root *root,
-                                  struct btrfs_path *path, int *level)
+static int free_chunk_item(struct btrfs_trans_handle *trans,
+                          struct btrfs_fs_info *fs_info,
+                          u64 bytenr, u64 len)
 {
-       u64 root_owner;
-       u64 root_gen;
-       u64 bytenr;
-       struct extent_buffer *next;
-       struct extent_buffer *cur;
-       struct extent_buffer *parent;
-       u32 blocksize;
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       struct btrfs_root *root = fs_info->chunk_root;
+       struct btrfs_chunk *chunk;
+       u64 chunk_type;
        int ret;
-       u32 refs;
 
-       WARN_ON(*level < 0);
-       WARN_ON(*level >= BTRFS_MAX_LEVEL);
-       ret = lookup_extent_ref(trans, root,
-                               path->nodes[*level]->start,
-                               path->nodes[*level]->len, &refs);
-       BUG_ON(ret);
-       if (refs > 1)
-               goto out;
+       key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+       key.offset = bytenr;
+       key.type = BTRFS_CHUNK_ITEM_KEY;
 
-       /*
-        * walk down to the last node level and free all the leaves
-        */
-       while(*level >= 0) {
-               WARN_ON(*level < 0);
-               WARN_ON(*level >= BTRFS_MAX_LEVEL);
-               cur = path->nodes[*level];
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
 
-               if (btrfs_header_level(cur) != *level)
-                       WARN_ON(1);
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+       if (ret < 0)
+               goto out;
+       chunk = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                              struct btrfs_chunk);
+       chunk_type = btrfs_chunk_type(path->nodes[0], chunk);
 
-               if (path->slots[*level] >=
-                   btrfs_header_nritems(cur))
-                       break;
-               if (*level == 0) {
-                       ret = drop_leaf_ref(trans, root, cur);
-                       BUG_ON(ret);
-                       break;
-               }
-               bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
-               blocksize = btrfs_level_size(root, *level - 1);
-               ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
-               BUG_ON(ret);
-               if (refs != 1) {
-                       parent = path->nodes[*level];
-                       root_owner = btrfs_header_owner(parent);
-                       root_gen = btrfs_header_generation(parent);
-                       path->slots[*level]++;
-                       ret = btrfs_free_extent(trans, root, bytenr,
-                                               blocksize, root_owner,
-                                               root_gen, 0, 0, 1);
-                       BUG_ON(ret);
-                       continue;
-               }
-               next = btrfs_find_tree_block(root, bytenr, blocksize);
-               if (!next || !btrfs_buffer_uptodate(next)) {
-                       free_extent_buffer(next);
-                       reada_walk_down(root, cur, path->slots[*level]);
-                       mutex_unlock(&root->fs_info->fs_mutex);
-                       next = read_tree_block(root, bytenr, blocksize);
-                       mutex_lock(&root->fs_info->fs_mutex);
+       ret = btrfs_del_item(trans, root, path);
+       if (ret < 0)
+               goto out;
 
-                       /* we dropped the lock, check one more time */
-                       ret = lookup_extent_ref(trans, root, bytenr,
-                                               blocksize, &refs);
-                       BUG_ON(ret);
-                       if (refs != 1) {
-                               parent = path->nodes[*level];
-                               root_owner = btrfs_header_owner(parent);
-                               root_gen = btrfs_header_generation(parent);
-
-                               path->slots[*level]++;
-                               free_extent_buffer(next);
-                               ret = btrfs_free_extent(trans, root, bytenr,
-                                                       blocksize,
-                                                       root_owner,
-                                                       root_gen, 0, 0, 1);
-                               BUG_ON(ret);
-                               continue;
-                       }
-               }
-               WARN_ON(*level <= 0);
-               if (path->nodes[*level-1])
-                       free_extent_buffer(path->nodes[*level-1]);
-               path->nodes[*level-1] = next;
-               *level = btrfs_header_level(next);
-               path->slots[*level] = 0;
-       }
+       if (chunk_type & BTRFS_BLOCK_GROUP_SYSTEM)
+               ret = free_system_chunk_item(fs_info->super_copy, &key);
 out:
-       WARN_ON(*level < 0);
-       WARN_ON(*level >= BTRFS_MAX_LEVEL);
+       btrfs_free_path(path);
+       return ret;
+}
 
-       if (path->nodes[*level] == root->node) {
-               root_owner = root->root_key.objectid;
-               parent = path->nodes[*level];
-       } else {
-               parent = path->nodes[*level + 1];
-               root_owner = btrfs_header_owner(parent);
-       }
+static u64 get_dev_extent_len(struct map_lookup *map)
+{
+       int div;
 
-       root_gen = btrfs_header_generation(parent);
-       ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
-                               path->nodes[*level]->len,
-                               root_owner, root_gen, 0, 0, 1);
-       free_extent_buffer(path->nodes[*level]);
-       path->nodes[*level] = NULL;
-       *level += 1;
-       BUG_ON(ret);
-       return 0;
+       switch (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
+       case 0: /* Single */
+       case BTRFS_BLOCK_GROUP_DUP:
+       case BTRFS_BLOCK_GROUP_RAID1:
+               div = 1;
+               break;
+       case BTRFS_BLOCK_GROUP_RAID5:
+               div = (map->num_stripes - 1);
+               break;
+       case BTRFS_BLOCK_GROUP_RAID6:
+               div = (map->num_stripes - 2);
+               break;
+       case BTRFS_BLOCK_GROUP_RAID10:
+               div = (map->num_stripes / map->sub_stripes);
+               break;
+       default:
+               /* normally, read chunk security hook should handled it */
+               BUG_ON(1);
+       }
+       return map->ce.size / div;
 }
 
-/*
- * helper for dropping snapshots.  This walks back up the tree in the path
- * to find the first node higher up where we haven't yet gone through
- * all the slots
- */
-static int noinline walk_up_tree(struct btrfs_trans_handle *trans,
-                                struct btrfs_root *root,
-                                struct btrfs_path *path, int *level)
+/* free block group/chunk related caches */
+static int free_block_group_cache(struct btrfs_trans_handle *trans,
+                                 struct btrfs_fs_info *fs_info,
+                                 u64 bytenr, u64 len)
 {
-       u64 root_owner;
-       u64 root_gen;
-       struct btrfs_root_item *root_item = &root->root_item;
-       int i;
-       int slot;
+       struct btrfs_block_group_cache *cache;
+       struct cache_extent *ce;
+       struct map_lookup *map;
        int ret;
+       int i;
+       u64 flags;
 
-       for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
-               slot = path->slots[i];
-               if (slot < btrfs_header_nritems(path->nodes[i]) - 1) {
-                       struct extent_buffer *node;
-                       struct btrfs_disk_key disk_key;
-                       node = path->nodes[i];
-                       path->slots[i]++;
-                       *level = i;
-                       WARN_ON(*level == 0);
-                       btrfs_node_key(node, &disk_key, path->slots[i]);
-                       memcpy(&root_item->drop_progress,
-                              &disk_key, sizeof(disk_key));
-                       root_item->drop_level = i;
-                       return 0;
-               } else {
-                       if (path->nodes[*level] == root->node) {
-                               root_owner = root->root_key.objectid;
-                               root_gen =
-                                  btrfs_header_generation(path->nodes[*level]);
-                       } else {
-                               struct extent_buffer *node;
-                               node = path->nodes[*level + 1];
-                               root_owner = btrfs_header_owner(node);
-                               root_gen = btrfs_header_generation(node);
-                       }
-                       ret = btrfs_free_extent(trans, root,
-                                               path->nodes[*level]->start,
-                                               path->nodes[*level]->len,
-                                               root_owner, root_gen, 0, 0, 1);
-                       BUG_ON(ret);
-                       free_extent_buffer(path->nodes[*level]);
-                       path->nodes[*level] = NULL;
-                       *level = i + 1;
-               }
+       /* Free block group cache first */
+       cache = btrfs_lookup_block_group(fs_info, bytenr);
+       if (!cache)
+               return -ENOENT;
+       flags = cache->flags;
+       if (cache->free_space_ctl) {
+               btrfs_remove_free_space_cache(cache);
+               kfree(cache->free_space_ctl);
        }
-       return 1;
+       clear_extent_bits(&fs_info->block_group_cache, bytenr, bytenr + len,
+                         (unsigned int)-1, GFP_NOFS);
+       ret = free_space_info(fs_info, flags, len, 0, NULL);
+       if (ret < 0)
+               goto out;
+       kfree(cache);
+
+       /* Then free mapping info and dev usage info */
+       ce = search_cache_extent(&fs_info->mapping_tree.cache_tree, bytenr);
+       if (!ce || ce->start != bytenr) {
+               ret = -ENOENT;
+               goto out;
+       }
+       map = container_of(ce, struct map_lookup, ce);
+       for (i = 0; i < map->num_stripes; i++) {
+               struct btrfs_device *device;
+
+               device = map->stripes[i].dev;
+               device->bytes_used -= get_dev_extent_len(map);
+               ret = btrfs_update_device(trans, device);
+               if (ret < 0)
+                       goto out;
+       }
+       remove_cache_extent(&fs_info->mapping_tree.cache_tree, ce);
+       free(map);
+out:
+       return ret;
 }
 
-/*
- * drop the reference count on the tree rooted at 'snap'.  This traverses
- * the tree freeing any blocks that have a ref count of zero after being
- * decremented.
- */
-int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
-                       *root)
+int btrfs_free_block_group(struct btrfs_trans_handle *trans,
+                          struct btrfs_fs_info *fs_info, u64 bytenr, u64 len)
 {
-       int ret = 0;
-       int wret;
-       int level;
+       struct btrfs_root *extent_root = fs_info->extent_root;
        struct btrfs_path *path;
-       int i;
-       int orig_level;
-       struct btrfs_root_item *root_item = &root->root_item;
+       struct btrfs_block_group_item *bgi;
+       struct btrfs_key key;
+       int ret = 0;
 
        path = btrfs_alloc_path();
-       BUG_ON(!path);
-
-       level = btrfs_header_level(root->node);
-       orig_level = level;
-       if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
-               path->nodes[level] = root->node;
-               extent_buffer_get(root->node);
-               path->slots[level] = 0;
-       } else {
-               struct btrfs_key key;
-               struct btrfs_disk_key found_key;
-               struct extent_buffer *node;
-
-               btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
-               level = root_item->drop_level;
-               path->lowest_level = level;
-               wret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-               if (wret < 0) {
-                       ret = wret;
-                       goto out;
-               }
-               node = path->nodes[level];
-               btrfs_node_key(node, &found_key, path->slots[level]);
-               WARN_ON(memcmp(&found_key, &root_item->drop_progress,
-                              sizeof(found_key)));
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = bytenr;
+       key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+       key.offset = len;
+
+       /* Double check the block group to ensure it's empty */
+       ret = btrfs_search_slot(trans, extent_root, &key, path, 0, 0);
+       if (ret > 0) {
+               ret = -ENONET;
+               goto out;
        }
-       while(1) {
-               wret = walk_down_tree(trans, root, path, &level);
-               if (wret < 0)
-                       ret = wret;
-               if (wret != 0)
-                       break;
+       if (ret < 0)
+               goto out;
+
+       bgi = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                            struct btrfs_block_group_item);
+       if (btrfs_disk_block_group_used(path->nodes[0], bgi)) {
+               fprintf(stderr,
+                       "WARNING: block group [%llu,%llu) is not empty\n",
+                       bytenr, bytenr + len);
+               ret = -EINVAL;
+               goto out;
+       }
+       btrfs_release_path(path);
+
+       /*
+        * Now pin all space in the block group, to prevent further transaction
+        * allocate space from it.
+        * Every operation needs a transaction must be in the range.
+        */
+       btrfs_pin_extent(fs_info, bytenr, len);
+
+       /* delete block group item and chunk item */
+       ret = free_block_group_item(trans, fs_info, bytenr, len);
+       if (ret < 0) {
+               fprintf(stderr,
+                       "failed to free block group item for [%llu,%llu)\n",
+                       bytenr, bytenr + len);
+               btrfs_unpin_extent(fs_info, bytenr, len);
+               goto out;
+       }
+
+       ret = free_chunk_dev_extent_items(trans, fs_info, bytenr);
+       if (ret < 0) {
+               fprintf(stderr,
+                       "failed to dev extents belongs to [%llu,%llu)\n",
+                       bytenr, bytenr + len);
+               btrfs_unpin_extent(fs_info, bytenr, len);
+               goto out;
+       }
+       ret = free_chunk_item(trans, fs_info, bytenr, len);
+       if (ret < 0) {
+               fprintf(stderr,
+                       "failed to free chunk for [%llu,%llu)\n",
+                       bytenr, bytenr + len);
+               btrfs_unpin_extent(fs_info, bytenr, len);
+               goto out;
+       }
+
+       /* Now release the block_group_cache */
+       ret = free_block_group_cache(trans, fs_info, bytenr, len);
+       btrfs_unpin_extent(fs_info, bytenr, len);
+
+out:
+       btrfs_free_path(path);
+       return ret;
+}
+
+/*
+ * Fixup block accounting. The initial block accounting created by
+ * make_block_groups isn't accuracy in this case.
+ */
+int btrfs_fix_block_accounting(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root)
+{
+       int ret;
+       int slot;
+       u64 start = 0;
+       u64 bytes_used = 0;
+       struct btrfs_path path;
+       struct btrfs_key key;
+       struct extent_buffer *leaf;
+       struct btrfs_block_group_cache *cache;
+       struct btrfs_fs_info *fs_info = root->fs_info;
+
+       root = root->fs_info->extent_root;
 
-               wret = walk_up_tree(trans, root, path, &level);
-               if (wret < 0)
-                       ret = wret;
-               if (wret != 0)
-                       break;
-               /*
-               ret = -EAGAIN;
-               break;
-               */
-       }
-       for (i = 0; i <= orig_level; i++) {
-               if (path->nodes[i]) {
-                       free_extent_buffer(path->nodes[i]);
-                       path->nodes[i] = NULL;
-               }
+       while(extent_root_pending_ops(fs_info)) {
+               ret = finish_current_insert(trans, root);
+               if (ret)
+                       return ret;
+               ret = del_pending_extents(trans, root);
+               if (ret)
+                       return ret;
        }
-out:
-       btrfs_free_path(path);
-       return ret;
-}
 
-int btrfs_free_block_groups(struct btrfs_fs_info *info)
-{
-       u64 start;
-       u64 end;
-       u64 ptr;
-       int ret;
        while(1) {
-               ret = find_first_extent_bit(&info->block_group_cache, 0,
-                                           &start, &end, (unsigned int)-1);
-               if (ret)
+               cache = btrfs_lookup_first_block_group(fs_info, start);
+               if (!cache)
                        break;
-               ret = get_state_private(&info->block_group_cache, start, &ptr);
-               if (!ret)
-                       kfree((void *)(unsigned long)ptr);
-               clear_extent_bits(&info->block_group_cache, start,
-                                 end, (unsigned int)-1, GFP_NOFS);
+               start = cache->key.objectid + cache->key.offset;
+               btrfs_set_block_group_used(&cache->item, 0);
+               cache->space_info->bytes_used = 0;
+               set_extent_bits(&root->fs_info->block_group_cache,
+                               cache->key.objectid,
+                               cache->key.objectid + cache->key.offset -1,
+                               BLOCK_GROUP_DIRTY, GFP_NOFS);
        }
+
+       btrfs_init_path(&path);
+       key.offset = 0;
+       key.objectid = 0;
+       key.type = BTRFS_EXTENT_ITEM_KEY;
+       ret = btrfs_search_slot(trans, root->fs_info->extent_root,
+                               &key, &path, 0, 0);
+       if (ret < 0)
+               return ret;
        while(1) {
-               ret = find_first_extent_bit(&info->free_space_cache, 0,
-                                           &start, &end, EXTENT_DIRTY);
-               if (ret)
-                       break;
-               clear_extent_dirty(&info->free_space_cache, start,
-                                  end, GFP_NOFS);
+               leaf = path.nodes[0];
+               slot = path.slots[0];
+               if (slot >= btrfs_header_nritems(leaf)) {
+                       ret = btrfs_next_leaf(root, &path);
+                       if (ret < 0)
+                               return ret;
+                       if (ret > 0)
+                               break;
+                       leaf = path.nodes[0];
+                       slot = path.slots[0];
+               }
+               btrfs_item_key_to_cpu(leaf, &key, slot);
+               if (key.type == BTRFS_EXTENT_ITEM_KEY) {
+                       bytes_used += key.offset;
+                       ret = btrfs_update_block_group(trans, root,
+                                 key.objectid, key.offset, 1, 0);
+                       BUG_ON(ret);
+               } else if (key.type == BTRFS_METADATA_ITEM_KEY) {
+                       bytes_used += root->nodesize;
+                       ret = btrfs_update_block_group(trans, root,
+                                 key.objectid, root->nodesize, 1, 0);
+                       BUG_ON(ret);
+               }
+               path.slots[0]++;
        }
+       btrfs_set_super_bytes_used(root->fs_info->super_copy, bytes_used);
+       btrfs_release_path(&path);
        return 0;
 }
 
-int find_first_block_group(struct btrfs_root *root, struct btrfs_path *path,
-                          struct btrfs_key *key)
+static void __get_extent_size(struct btrfs_root *root, struct btrfs_path *path,
+                             u64 *start, u64 *len)
+{
+       struct btrfs_key key;
+
+       btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+       BUG_ON(!(key.type == BTRFS_EXTENT_ITEM_KEY ||
+                key.type == BTRFS_METADATA_ITEM_KEY));
+       *start = key.objectid;
+       if (key.type == BTRFS_EXTENT_ITEM_KEY)
+               *len = key.offset;
+       else
+               *len = root->nodesize;
+}
+
+/*
+ * Find first overlap extent for range [bytenr, bytenr + len)
+ * Return 0 for found and point path to it.
+ * Return >0 for not found.
+ * Return <0 for err
+ */
+int btrfs_search_overlap_extent(struct btrfs_root *root,
+                               struct btrfs_path *path, u64 bytenr, u64 len)
 {
+       struct btrfs_key key;
+       u64 cur_start;
+       u64 cur_len;
        int ret;
-       struct btrfs_key found_key;
-       struct extent_buffer *leaf;
-       int slot;
 
-       ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+       key.objectid = bytenr;
+       key.type = BTRFS_EXTENT_DATA_KEY;
+       key.offset = (u64)-1;
+
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0)
                return ret;
-       while(1) {
-               slot = path->slots[0];
-               leaf = path->nodes[0];
-               if (slot >= btrfs_header_nritems(leaf)) {
-                       ret = btrfs_next_leaf(root, path);
-                       if (ret == 0)
-                               continue;
-                       if (ret < 0)
-                               goto error;
-                       break;
-               }
-               btrfs_item_key_to_cpu(leaf, &found_key, slot);
+       BUG_ON(ret == 0);
 
-               if (found_key.objectid >= key->objectid &&
-                   found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY)
-                       return 0;
-               path->slots[0]++;
-       }
-       ret = -ENOENT;
-error:
-       return ret;
+       ret = btrfs_previous_extent_item(root, path, 0);
+       if (ret < 0)
+               return ret;
+       /* no previous, check next extent */
+       if (ret > 0)
+               goto next;
+       __get_extent_size(root, path, &cur_start, &cur_len);
+       /* Tail overlap */
+       if (cur_start + cur_len > bytenr)
+               return 1;
+
+next:
+       ret = btrfs_next_extent_item(root, path, bytenr + len);
+       if (ret < 0)
+               return ret;
+       /* No next, prev already checked, no overlap */
+       if (ret > 0)
+               return 0;
+       __get_extent_size(root, path, &cur_start, &cur_len);
+       /* head overlap*/
+       if (cur_start < bytenr + len)
+               return 1;
+       return 0;
 }
 
-int btrfs_read_block_groups(struct btrfs_root *root)
+static int __btrfs_record_file_extent(struct btrfs_trans_handle *trans,
+                                     struct btrfs_root *root, u64 objectid,
+                                     struct btrfs_inode_item *inode,
+                                     u64 file_pos, u64 disk_bytenr,
+                                     u64 *ret_num_bytes)
 {
-       struct btrfs_path *path;
        int ret;
-       int bit;
-       struct btrfs_block_group_cache *cache;
        struct btrfs_fs_info *info = root->fs_info;
-       struct btrfs_space_info *space_info;
-       struct extent_io_tree *block_group_cache;
-       struct btrfs_key key;
-       struct btrfs_key found_key;
+       struct btrfs_root *extent_root = info->extent_root;
        struct extent_buffer *leaf;
+       struct btrfs_file_extent_item *fi;
+       struct btrfs_key ins_key;
+       struct btrfs_path *path;
+       struct btrfs_extent_item *ei;
+       u64 nbytes;
+       u64 extent_num_bytes;
+       u64 extent_bytenr;
+       u64 extent_offset;
+       u64 num_bytes = *ret_num_bytes;
 
-       block_group_cache = &info->block_group_cache;
+       /*
+        * All supported file system should not use its 0 extent.
+        * As it's for hole
+        *
+        * And hole extent has no size limit, no need to loop.
+        */
+       if (disk_bytenr == 0) {
+               ret = btrfs_insert_file_extent(trans, root, objectid,
+                                               file_pos, disk_bytenr,
+                                               num_bytes, num_bytes);
+               return ret;
+       }
+       num_bytes = min_t(u64, num_bytes, BTRFS_MAX_EXTENT_SIZE);
 
-       root = info->extent_root;
-       key.objectid = 0;
-       key.offset = 0;
-       btrfs_set_key_type(&key, BTRFS_BLOCK_GROUP_ITEM_KEY);
        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;
 
-       while(1) {
-               ret = find_first_block_group(root, path, &key);
-               if (ret > 0) {
-                       ret = 0;
-                       goto error;
-               }
-               if (ret != 0) {
-                       goto error;
-               }
-               leaf = path->nodes[0];
-               btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
-               cache = kmalloc(sizeof(*cache), GFP_NOFS);
-               if (!cache) {
-                       ret = -ENOMEM;
-                       break;
-               }
+       /* First to check extent overlap */
+       ret = btrfs_search_overlap_extent(extent_root, path, disk_bytenr,
+                                         num_bytes);
+       if (ret < 0)
+               goto fail;
+       if (ret > 0) {
+               /* Found overlap */
+               u64 cur_start;
+               u64 cur_len;
 
-               read_extent_buffer(leaf, &cache->item,
-                                  btrfs_item_ptr_offset(leaf, path->slots[0]),
-                                  sizeof(cache->item));
-               memcpy(&cache->key, &found_key, sizeof(found_key));
-               cache->cached = 0;
-               cache->pinned = 0;
-               key.objectid = found_key.objectid + found_key.offset;
-               btrfs_release_path(root, path);
-               cache->flags = btrfs_block_group_flags(&cache->item);
-               bit = 0;
-               if (cache->flags & BTRFS_BLOCK_GROUP_DATA) {
-                       bit = BLOCK_GROUP_DATA;
-               } else if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
-                       bit = BLOCK_GROUP_SYSTEM;
-               } else if (cache->flags & BTRFS_BLOCK_GROUP_METADATA) {
-                       bit = BLOCK_GROUP_METADATA;
+               __get_extent_size(extent_root, path, &cur_start, &cur_len);
+               /*
+                * For convert case, this extent should be a subset of
+                * existing one.
+                */
+               BUG_ON(disk_bytenr < cur_start);
+
+               extent_bytenr = cur_start;
+               extent_num_bytes = cur_len;
+               extent_offset = disk_bytenr - extent_bytenr;
+       } else {
+               /* No overlap, create new extent */
+               btrfs_release_path(path);
+               ins_key.objectid = disk_bytenr;
+               ins_key.offset = num_bytes;
+               ins_key.type = BTRFS_EXTENT_ITEM_KEY;
+
+               ret = btrfs_insert_empty_item(trans, extent_root, path,
+                                             &ins_key, sizeof(*ei));
+               if (ret == 0) {
+                       leaf = path->nodes[0];
+                       ei = btrfs_item_ptr(leaf, path->slots[0],
+                                           struct btrfs_extent_item);
+
+                       btrfs_set_extent_refs(leaf, ei, 0);
+                       btrfs_set_extent_generation(leaf, ei, 0);
+                       btrfs_set_extent_flags(leaf, ei,
+                                              BTRFS_EXTENT_FLAG_DATA);
+                       btrfs_mark_buffer_dirty(leaf);
+
+                       ret = btrfs_update_block_group(trans, root, disk_bytenr,
+                                                      num_bytes, 1, 0);
+                       if (ret)
+                               goto fail;
+               } else if (ret != -EEXIST) {
+                       goto fail;
                }
-               set_avail_alloc_bits(info, cache->flags);
+               btrfs_extent_post_op(trans, extent_root);
+               extent_bytenr = disk_bytenr;
+               extent_num_bytes = num_bytes;
+               extent_offset = 0;
+       }
+       btrfs_release_path(path);
+       ins_key.objectid = objectid;
+       ins_key.offset = file_pos;
+       ins_key.type = BTRFS_EXTENT_DATA_KEY;
+       ret = btrfs_insert_empty_item(trans, root, path, &ins_key,
+                                     sizeof(*fi));
+       if (ret)
+               goto fail;
+       leaf = path->nodes[0];
+       fi = btrfs_item_ptr(leaf, path->slots[0],
+                           struct btrfs_file_extent_item);
+       btrfs_set_file_extent_generation(leaf, fi, trans->transid);
+       btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
+       btrfs_set_file_extent_disk_bytenr(leaf, fi, extent_bytenr);
+       btrfs_set_file_extent_disk_num_bytes(leaf, fi, extent_num_bytes);
+       btrfs_set_file_extent_offset(leaf, fi, extent_offset);
+       btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
+       btrfs_set_file_extent_ram_bytes(leaf, fi, extent_num_bytes);
+       btrfs_set_file_extent_compression(leaf, fi, 0);
+       btrfs_set_file_extent_encryption(leaf, fi, 0);
+       btrfs_set_file_extent_other_encoding(leaf, fi, 0);
+       btrfs_mark_buffer_dirty(leaf);
 
-               ret = update_space_info(info, cache->flags, found_key.offset,
-                                       btrfs_block_group_used(&cache->item),
-                                       &space_info);
-               BUG_ON(ret);
-               cache->space_info = space_info;
+       nbytes = btrfs_stack_inode_nbytes(inode) + num_bytes;
+       btrfs_set_stack_inode_nbytes(inode, nbytes);
+       btrfs_release_path(path);
 
-               /* use EXTENT_LOCKED to prevent merging */
-               set_extent_bits(block_group_cache, found_key.objectid,
-                               found_key.objectid + found_key.offset - 1,
-                               bit | EXTENT_LOCKED, GFP_NOFS);
-               set_state_private(block_group_cache, found_key.objectid,
-                                 (unsigned long)cache);
+       ret = btrfs_inc_extent_ref(trans, root, extent_bytenr, extent_num_bytes,
+                                  0, root->root_key.objectid, objectid,
+                                  file_pos - extent_offset);
+       if (ret)
+               goto fail;
+       ret = 0;
+       *ret_num_bytes = min(extent_num_bytes - extent_offset, num_bytes);
+fail:
+       btrfs_free_path(path);
+       return ret;
+}
+
+/*
+ * Record a file extent. Do all the required works, such as inserting
+ * file extent item, inserting extent item and backref item into extent
+ * tree and updating block accounting.
+ */
+int btrfs_record_file_extent(struct btrfs_trans_handle *trans,
+                             struct btrfs_root *root, u64 objectid,
+                             struct btrfs_inode_item *inode,
+                             u64 file_pos, u64 disk_bytenr,
+                             u64 num_bytes)
+{
+       u64 cur_disk_bytenr = disk_bytenr;
+       u64 cur_file_pos = file_pos;
+       u64 cur_num_bytes = num_bytes;
+       int ret = 0;
 
-               if (key.objectid >=
-                   btrfs_super_total_bytes(&info->super_copy))
+       while (num_bytes > 0) {
+               ret = __btrfs_record_file_extent(trans, root, objectid,
+                                                inode, cur_file_pos,
+                                                cur_disk_bytenr,
+                                                &cur_num_bytes);
+               if (ret < 0)
                        break;
+               cur_disk_bytenr += cur_num_bytes;
+               cur_file_pos += cur_num_bytes;
+               num_bytes -= cur_num_bytes;
        }
-       ret = 0;
-error:
-       btrfs_free_path(path);
        return ret;
 }
 
-int btrfs_make_block_group(struct btrfs_trans_handle *trans,
-                          struct btrfs_root *root, u64 bytes_used,
-                          u64 type, u64 chunk_objectid, u64 chunk_offset,
-                          u64 size)
+
+static int add_excluded_extent(struct btrfs_root *root,
+                              u64 start, u64 num_bytes)
 {
-       int ret;
-       int bit = 0;
-       struct btrfs_root *extent_root;
-       struct btrfs_block_group_cache *cache;
-       struct extent_io_tree *block_group_cache;
+       u64 end = start + num_bytes - 1;
+       set_extent_bits(&root->fs_info->pinned_extents,
+                       start, end, EXTENT_UPTODATE, GFP_NOFS);
+       return 0;
+}
 
-       extent_root = root->fs_info->extent_root;
-       block_group_cache = &root->fs_info->block_group_cache;
+void free_excluded_extents(struct btrfs_root *root,
+                          struct btrfs_block_group_cache *cache)
+{
+       u64 start, end;
 
-       cache = kzalloc(sizeof(*cache), GFP_NOFS);
-       BUG_ON(!cache);
-       cache->key.objectid = chunk_offset;
-       cache->key.offset = size;
+       start = cache->key.objectid;
+       end = start + cache->key.offset - 1;
 
-       btrfs_set_key_type(&cache->key, BTRFS_BLOCK_GROUP_ITEM_KEY);
-       btrfs_set_block_group_used(&cache->item, bytes_used);
-       btrfs_set_block_group_chunk_objectid(&cache->item, chunk_objectid);
-       cache->flags = type;
-       btrfs_set_block_group_flags(&cache->item, type);
+       clear_extent_bits(&root->fs_info->pinned_extents,
+                         start, end, EXTENT_UPTODATE, GFP_NOFS);
+}
 
-       ret = update_space_info(root->fs_info, cache->flags, size, bytes_used,
-                               &cache->space_info);
-       BUG_ON(ret);
+int exclude_super_stripes(struct btrfs_root *root,
+                         struct btrfs_block_group_cache *cache)
+{
+       u64 bytenr;
+       u64 *logical;
+       int stripe_len;
+       int i, nr, ret;
+
+       if (cache->key.objectid < BTRFS_SUPER_INFO_OFFSET) {
+               stripe_len = BTRFS_SUPER_INFO_OFFSET - cache->key.objectid;
+               cache->bytes_super += stripe_len;
+               ret = add_excluded_extent(root, cache->key.objectid,
+                                         stripe_len);
+               if (ret)
+                       return ret;
+       }
 
-       bit = block_group_state_bits(type);
-       set_extent_bits(block_group_cache, chunk_offset,
-                       chunk_offset + size - 1,
-                       bit | EXTENT_LOCKED, GFP_NOFS);
+       for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+               bytenr = btrfs_sb_offset(i);
+               ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
+                                      cache->key.objectid, bytenr,
+                                      0, &logical, &nr, &stripe_len);
+               if (ret)
+                       return ret;
 
-       set_state_private(block_group_cache, chunk_offset,
-                         (unsigned long)cache);
-       ret = btrfs_insert_item(trans, extent_root, &cache->key, &cache->item,
-                               sizeof(cache->item));
-       BUG_ON(ret);
+               while (nr--) {
+                       u64 start, len;
 
-       finish_current_insert(trans, extent_root);
-       ret = del_pending_extents(trans, extent_root);
-       BUG_ON(ret);
-       set_avail_alloc_bits(extent_root->fs_info, type);
+                       if (logical[nr] > cache->key.objectid +
+                           cache->key.offset)
+                               continue;
+
+                       if (logical[nr] + stripe_len <= cache->key.objectid)
+                               continue;
+
+                       start = logical[nr];
+                       if (start < cache->key.objectid) {
+                               start = cache->key.objectid;
+                               len = (logical[nr] + stripe_len) - start;
+                       } else {
+                               len = min_t(u64, stripe_len,
+                                           cache->key.objectid +
+                                           cache->key.offset - start);
+                       }
+
+                       cache->bytes_super += len;
+                       ret = add_excluded_extent(root, start, len);
+                       if (ret) {
+                               kfree(logical);
+                               return ret;
+                       }
+               }
+
+               kfree(logical);
+       }
        return 0;
 }
 
-u64 btrfs_hash_extent_ref(u64 root_objectid, u64 ref_generation,
-                         u64 owner, u64 owner_offset)
+u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
+                      struct btrfs_fs_info *info, u64 start, u64 end)
 {
-       return hash_extent_ref(root_objectid, ref_generation,
-                              owner, owner_offset);
-}
+       u64 extent_start, extent_end, size, total_added = 0;
+       int ret;
 
-int btrfs_update_block_group(struct btrfs_trans_handle *trans,
-                            struct btrfs_root *root,
-                            u64 bytenr, u64 num_bytes, int alloc,
-                            int mark_free)
-{
-       return update_block_group(trans, root, bytenr, num_bytes,
-                                 alloc, mark_free);
+       while (start < end) {
+               ret = find_first_extent_bit(&info->pinned_extents, start,
+                                           &extent_start, &extent_end,
+                                           EXTENT_DIRTY | EXTENT_UPTODATE);
+               if (ret)
+                       break;
+
+               if (extent_start <= start) {
+                       start = extent_end + 1;
+               } else if (extent_start > start && extent_start < end) {
+                       size = extent_start - start;
+                       total_added += size;
+                       ret = btrfs_add_free_space(block_group->free_space_ctl,
+                                                  start, size);
+                       BUG_ON(ret); /* -ENOMEM or logic error */
+                       start = extent_end + 1;
+               } else {
+                       break;
+               }
+       }
+
+       if (start < end) {
+               size = end - start;
+               total_added += size;
+               ret = btrfs_add_free_space(block_group->free_space_ctl, start,
+                                          size);
+               BUG_ON(ret); /* -ENOMEM or logic error */
+       }
+
+       return total_added;
 }