Merge branch 'master' of ssh://mason@master.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

1 files changed, 5253 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
new file mode 100644
index 000000000000..280ac1aa9b6d
--- /dev/null
+++ b/fs/btrfs/extent-tree.c
@@ -0,0 +1,5253 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+#include <linux/sched.h>
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include "hash.h"
+#include "crc32c.h"
+#include "ctree.h"
+#include "disk-io.h"
+#include "print-tree.h"
+#include "transaction.h"
+#include "volumes.h"
+#include "locking.h"
+#include "ref-cache.h"
+
+#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 parent;
+	u64 orig_parent;
+	u64 generation;
+	u64 orig_generation;
+	int level;
+};
+
+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);
+
+void maybe_lock_mutex(struct btrfs_root *root)
+{
+	if (root != root->fs_info->extent_root &&
+	    root != root->fs_info->chunk_root &&
+	    root != root->fs_info->dev_root) {
+		mutex_lock(&root->fs_info->alloc_mutex);
+	}
+}
+
+void maybe_unlock_mutex(struct btrfs_root *root)
+{
+	if (root != root->fs_info->extent_root &&
+	    root != root->fs_info->chunk_root &&
+	    root != root->fs_info->dev_root) {
+		mutex_unlock(&root->fs_info->alloc_mutex);
+	}
+}
+
+static int block_group_bits(struct btrfs_block_group_cache *cache, u64 bits)
+{
+	return (cache->flags & bits) == bits;
+}
+
+/*
+ * this adds the block group to the fs_info rb tree for the block group
+ * cache
+ */
+int btrfs_add_block_group_cache(struct btrfs_fs_info *info,
+				struct btrfs_block_group_cache *block_group)
+{
+	struct rb_node **p;
+	struct rb_node *parent = NULL;
+	struct btrfs_block_group_cache *cache;
+
+	spin_lock(&info->block_group_cache_lock);
+	p = &info->block_group_cache_tree.rb_node;
+
+	while (*p) {
+		parent = *p;
+		cache = rb_entry(parent, struct btrfs_block_group_cache,
+				 cache_node);
+		if (block_group->key.objectid < cache->key.objectid) {
+			p = &(*p)->rb_left;
+		} else if (block_group->key.objectid > cache->key.objectid) {
+			p = &(*p)->rb_right;
+		} else {
+			spin_unlock(&info->block_group_cache_lock);
+			return -EEXIST;
+		}
+	}
+
+	rb_link_node(&block_group->cache_node, parent, p);
+	rb_insert_color(&block_group->cache_node,
+			&info->block_group_cache_tree);
+	spin_unlock(&info->block_group_cache_lock);
+
+	return 0;
+}
+
+/*
+ * This will return the block group at or after bytenr if contains is 0, else
+ * it will return the block group that contains the bytenr
+ */
+static struct btrfs_block_group_cache *
+block_group_cache_tree_search(struct btrfs_fs_info *info, u64 bytenr,
+			      int contains)
+{
+	struct btrfs_block_group_cache *cache, *ret = NULL;
+	struct rb_node *n;
+	u64 end, start;
+
+	spin_lock(&info->block_group_cache_lock);
+	n = info->block_group_cache_tree.rb_node;
+
+	while (n) {
+		cache = rb_entry(n, struct btrfs_block_group_cache,
+				 cache_node);
+		end = cache->key.objectid + cache->key.offset - 1;
+		start = cache->key.objectid;
+
+		if (bytenr < start) {
+			if (!contains && (!ret || start < ret->key.objectid))
+				ret = cache;
+			n = n->rb_left;
+		} else if (bytenr > start) {
+			if (contains && bytenr <= end) {
+				ret = cache;
+				break;
+			}
+			n = n->rb_right;
+		} else {
+			ret = cache;
+			break;
+		}
+	}
+	spin_unlock(&info->block_group_cache_lock);
+
+	return ret;
+}
+
+/*
+ * this is only called by cache_block_group, since we could have freed extents
+ * we need to check the pinned_extents for any extents that can't be used yet
+ * since their free space will be released as soon as the transaction commits.
+ */
+static int add_new_free_space(struct btrfs_block_group_cache *block_group,
+			      struct btrfs_fs_info *info, u64 start, u64 end)
+{
+	u64 extent_start, extent_end, size;
+	int ret;
+
+	while (start < end) {
+		ret = find_first_extent_bit(&info->pinned_extents, start,
+					    &extent_start, &extent_end,
+					    EXTENT_DIRTY);
+		if (ret)
+			break;
+
+		if (extent_start == start) {
+			start = extent_end + 1;
+		} else if (extent_start > start && extent_start < end) {
+			size = extent_start - start;
+			ret = btrfs_add_free_space(block_group, start, size);
+			BUG_ON(ret);
+			start = extent_end + 1;
+		} else {
+			break;
+		}
+	}
+
+	if (start < end) {
+		size = end - start;
+		ret = btrfs_add_free_space(block_group, start, size);
+		BUG_ON(ret);
+	}
+
+	return 0;
+}
+
+static int cache_block_group(struct btrfs_root *root,
+			     struct btrfs_block_group_cache *block_group)
+{
+	struct btrfs_path *path;
+	int ret = 0;
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	int slot;
+	u64 last = 0;
+	u64 first_free;
+	int found = 0;
+
+	if (!block_group)
+		return 0;
+
+	root = root->fs_info->extent_root;
+
+	if (block_group->cached)
+		return 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->reada = 2;
+	/*
+	 * we get into deadlocks with paths held by callers of this function.
+	 * since the alloc_mutex is protecting things right now, just
+	 * skip the locking here
+	 */
+	path->skip_locking = 1;
+	first_free = max_t(u64, block_group->key.objectid,
+			   BTRFS_SUPER_INFO_OFFSET + BTRFS_SUPER_INFO_SIZE);
+	key.objectid = block_group->key.objectid;
+	key.offset = 0;
+	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+	if (ret < 0)
+		goto err;
+	ret = btrfs_previous_item(root, path, 0, BTRFS_EXTENT_ITEM_KEY);
+	if (ret < 0)
+		goto err;
+	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;
+	}
+	while(1) {
+		leaf = path->nodes[0];
+		slot = path->slots[0];
+		if (slot >= btrfs_header_nritems(leaf)) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto err;
+			if (ret == 0)
+				continue;
+			else
+				break;
+		}
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (key.objectid < block_group->key.objectid)
+			goto next;
+
+		if (key.objectid >= block_group->key.objectid +
+		    block_group->key.offset)
+			break;
+
+		if (btrfs_key_type(&key) == BTRFS_EXTENT_ITEM_KEY) {
+			if (!found) {
+				last = first_free;
+				found = 1;
+			}
+
+			add_new_free_space(block_group, root->fs_info, last,
+					   key.objectid);
+
+			last = key.objectid + key.offset;
+		}
+next:
+		path->slots[0]++;
+	}
+
+	if (!found)
+		last = first_free;
+
+	add_new_free_space(block_group, root->fs_info, last,
+			   block_group->key.objectid +
+			   block_group->key.offset);
+
+	block_group->cached = 1;
+	ret = 0;
+err:
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * return the block group that starts at or after bytenr
+ */
+struct btrfs_block_group_cache *btrfs_lookup_first_block_group(struct
+						       btrfs_fs_info *info,
+							 u64 bytenr)
+{
+	struct btrfs_block_group_cache *cache;
+
+	cache = block_group_cache_tree_search(info, bytenr, 0);
+
+	return cache;
+}
+
+/*
+ * return the block group that contains teh given bytenr
+ */
+struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
+							 btrfs_fs_info *info,
+							 u64 bytenr)
+{
+	struct btrfs_block_group_cache *cache;
+
+	cache = block_group_cache_tree_search(info, bytenr, 1);
+
+	return cache;
+}
+
+static int noinline find_free_space(struct btrfs_root *root,
+				    struct btrfs_block_group_cache **cache_ret,
+				    u64 *start_ret, u64 num, int data)
+{
+	int ret;
+	struct btrfs_block_group_cache *cache = *cache_ret;
+	struct btrfs_free_space *info = NULL;
+	u64 last;
+	u64 search_start = *start_ret;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	if (!cache)
+		goto out;
+
+	last = max(search_start, cache->key.objectid);
+
+again:
+	ret = cache_block_group(root, cache);
+	if (ret)
+		goto out;
+
+	if (cache->ro || !block_group_bits(cache, data))
+		goto new_group;
+
+	info = btrfs_find_free_space(cache, last, num);
+	if (info) {
+		*start_ret = info->offset;
+		return 0;
+	}
+
+new_group:
+	last = cache->key.objectid + cache->key.offset;
+
+	cache = btrfs_lookup_first_block_group(root->fs_info, last);
+	if (!cache)
+		goto out;
+
+	*cache_ret = cache;
+	goto again;
+
+out:
+	return -ENOSPC;
+}
+
+static u64 div_factor(u64 num, int factor)
+{
+	if (factor == 10)
+		return num;
+	num *= factor;
+	do_div(num, 10);
+	return num;
+}
+
+static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
+						  u64 flags)
+{
+	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;
+	}
+	return NULL;
+}
+
+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 btrfs_block_group_cache *found_group = NULL;
+	struct btrfs_fs_info *info = root->fs_info;
+	u64 used;
+	u64 last = 0;
+	u64 free_check;
+	int full_search = 0;
+	int factor = 10;
+	int wrapped = 0;
+
+	if (data & BTRFS_BLOCK_GROUP_METADATA)
+		factor = 9;
+
+	if (search_start) {
+		struct btrfs_block_group_cache *shint;
+		shint = btrfs_lookup_first_block_group(info, search_start);
+		if (shint && block_group_bits(shint, data) && !shint->ro) {
+			spin_lock(&shint->lock);
+			used = btrfs_block_group_used(&shint->item);
+			if (used + shint->pinned + shint->reserved <
+			    div_factor(shint->key.offset, factor)) {
+				spin_unlock(&shint->lock);
+				return shint;
+			}
+			spin_unlock(&shint->lock);
+		}
+	}
+	if (hint && !hint->ro && block_group_bits(hint, data)) {
+		spin_lock(&hint->lock);
+		used = btrfs_block_group_used(&hint->item);
+		if (used + hint->pinned + hint->reserved <
+		    div_factor(hint->key.offset, factor)) {
+			spin_unlock(&hint->lock);
+			return hint;
+		}
+		spin_unlock(&hint->lock);
+		last = hint->key.objectid + hint->key.offset;
+	} else {
+		if (hint)
+			last = max(hint->key.objectid, search_start);
+		else
+			last = search_start;
+	}
+again:
+	while (1) {
+		cache = btrfs_lookup_first_block_group(root->fs_info, last);
+		if (!cache)
+			break;
+
+		spin_lock(&cache->lock);
+		last = cache->key.objectid + cache->key.offset;
+		used = btrfs_block_group_used(&cache->item);
+
+		if (!cache->ro && block_group_bits(cache, data)) {
+			free_check = div_factor(cache->key.offset, factor);
+			if (used + cache->pinned + cache->reserved <
+			    free_check) {
+				found_group = cache;
+				spin_unlock(&cache->lock);
+				goto found;
+			}
+		}
+		spin_unlock(&cache->lock);
+		cond_resched();
+	}
+	if (!wrapped) {
+		last = search_start;
+		wrapped = 1;
+		goto again;
+	}
+	if (!full_search && factor < 10) {
+		last = search_start;
+		full_search = 1;
+		factor = 10;
+		goto again;
+	}
+found:
+	return found_group;
+}
+
+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 *ret;
+	ret = __btrfs_find_block_group(root, hint, search_start, data, owner);
+	return ret;
+}
+
+/* simple helper to search for an existing extent at a given offset */
+int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len)
+{
+	int ret;
+	struct btrfs_key key;
+	struct btrfs_path *path;
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+	maybe_lock_mutex(root);
+	key.objectid = start;
+	key.offset = len;
+	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+	ret = btrfs_search_slot(NULL, root->fs_info->extent_root, &key, path,
+				0, 0);
+	maybe_unlock_mutex(root);
+	btrfs_free_path(path);
+	return ret;
+}
+
+/*
+ * Back reference rules.  Back refs have three main goals:
+ *
+ * 1) differentiate between all holders of references to an extent so that
+ *    when a reference is dropped we can make sure it was a valid reference
+ *    before freeing the extent.
+ *
+ * 2) Provide enough information to quickly find the holders of an extent
+ *    if we notice a given block is corrupted or bad.
+ *
+ * 3) Make it easy to migrate blocks for FS shrinking or storage pool
+ *    maintenance.  This is actually the same as #2, but with a slightly
+ *    different use case.
+ *
+ * File extents can be referenced by:
+ *
+ * - 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 has fields for:
+ *
+ * - Objectid of the subvolume root
+ * - Generation number of the tree holding the reference
+ * - objectid of the file holding the reference
+ * - number of references holding by parent node (alway 1 for tree blocks)
+ *
+ * Btree leaf may hold multiple references to a file extent. In most cases,
+ * these references are from same file and the corresponding offsets inside
+ * the file are close together.
+ *
+ * When a file extent is allocated the fields are filled in:
+ *     (root_key.objectid, trans->transid, inode objectid, 1)
+ *
+ * When a leaf is cow'd new references are added for every file extent found
+ * in the leaf.  It looks similar to the create case, but trans->transid will
+ * be different when the block is cow'd.
+ *
+ *     (root_key.objectid, trans->transid, inode objectid,
+ *      number of references in the leaf)
+ *
+ * When a file extent is removed either during snapshot deletion or
+ * file truncation, we find the corresponding back reference and check
+ * the following fields:
+ *
+ *     (btrfs_header_owner(leaf), btrfs_header_generation(leaf),
+ *      inode objectid)
+ *
+ * Btree extents can be referenced by:
+ *
+ * - Different subvolumes
+ * - Different generations of the same subvolume
+ *
+ * When a tree block is created, back references are inserted:
+ *
+ * (root->root_key.objectid, trans->transid, level, 1)
+ *
+ * When a tree block is cow'd, new back references are added for all the
+ * blocks it points to. If the tree block isn't in reference counted root,
+ * the old back references are removed. These new back references are of
+ * the form (trans->transid will have increased since creation):
+ *
+ * (root->root_key.objectid, trans->transid, level, 1)
+ *
+ * When a backref is in deleting, the following fields are checked:
+ *
+ * if backref was for a tree root:
+ *     (btrfs_header_owner(itself), btrfs_header_generation(itself), level)
+ * else
+ *     (btrfs_header_owner(parent), btrfs_header_generation(parent), level)
+ *
+ * Back Reference Key composing:
+ *
+ * The key objectid corresponds to the first byte in the extent, the key
+ * type is set to BTRFS_EXTENT_REF_KEY, and the key offset is the first
+ * byte of parent extent. If a extent is tree root, the key offset is set
+ * to the key objectid.
+ */
+
+static int noinline lookup_extent_backref(struct btrfs_trans_handle *trans,
+					  struct btrfs_root *root,
+					  struct btrfs_path *path,
+					  u64 bytenr, u64 parent,
+					  u64 ref_root, u64 ref_generation,
+					  u64 owner_objectid, int del)
+{
+	struct btrfs_key key;
+	struct btrfs_extent_ref *ref;
+	struct extent_buffer *leaf;
+	u64 ref_objectid;
+	int ret;
+
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_REF_KEY;
+	key.offset = parent;
+
+	ret = btrfs_search_slot(trans, root, &key, path, del ? -1 : 0, 1);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	leaf = path->nodes[0];
+	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_ref);
+	ref_objectid = btrfs_ref_objectid(leaf, ref);
+	if (btrfs_ref_root(leaf, ref) != ref_root ||
+	    btrfs_ref_generation(leaf, ref) != ref_generation ||
+	    (ref_objectid != owner_objectid &&
+	     ref_objectid != BTRFS_MULTIPLE_OBJECTIDS)) {
+		ret = -EIO;
+		WARN_ON(1);
+		goto out;
+	}
+	ret = 0;
+out:
+	return ret;
+}
+
+static int noinline insert_extent_backref(struct btrfs_trans_handle *trans,
+					  struct btrfs_root *root,
+					  struct btrfs_path *path,
+					  u64 bytenr, u64 parent,
+					  u64 ref_root, u64 ref_generation,
+					  u64 owner_objectid)
+{
+	struct btrfs_key key;
+	struct extent_buffer *leaf;
+	struct btrfs_extent_ref *ref;
+	u32 num_refs;
+	int ret;
+
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_REF_KEY;
+	key.offset = parent;
+
+	ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*ref));
+	if (ret == 0) {
+		leaf = path->nodes[0];
+		ref = btrfs_item_ptr(leaf, path->slots[0],
+				     struct btrfs_extent_ref);
+		btrfs_set_ref_root(leaf, ref, ref_root);
+		btrfs_set_ref_generation(leaf, ref, ref_generation);
+		btrfs_set_ref_objectid(leaf, ref, owner_objectid);
+		btrfs_set_ref_num_refs(leaf, ref, 1);
+	} else if (ret == -EEXIST) {
+		u64 existing_owner;
+		BUG_ON(owner_objectid < BTRFS_FIRST_FREE_OBJECTID);
+		leaf = path->nodes[0];
+		ref = btrfs_item_ptr(leaf, path->slots[0],
+				     struct btrfs_extent_ref);
+		if (btrfs_ref_root(leaf, ref) != ref_root ||
+		    btrfs_ref_generation(leaf, ref) != ref_generation) {
+			ret = -EIO;
+			WARN_ON(1);
+			goto out;
+		}
+
+		num_refs = btrfs_ref_num_refs(leaf, ref);
+		BUG_ON(num_refs == 0);
+		btrfs_set_ref_num_refs(leaf, ref, num_refs + 1);
+
+		existing_owner = btrfs_ref_objectid(leaf, ref);
+		if (existing_owner != owner_objectid &&
+		    existing_owner != BTRFS_MULTIPLE_OBJECTIDS) {
+			btrfs_set_ref_objectid(leaf, ref,
+					BTRFS_MULTIPLE_OBJECTIDS);
+		}
+		ret = 0;
+	} else {
+		goto out;
+	}
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+out:
+	btrfs_release_path(root, path);
+	return ret;
+}
+
+static int noinline remove_extent_backref(struct btrfs_trans_handle *trans,
+					  struct btrfs_root *root,
+					  struct btrfs_path *path)
+{
+	struct extent_buffer *leaf;
+	struct btrfs_extent_ref *ref;
+	u32 num_refs;
+	int ret = 0;
+
+	leaf = path->nodes[0];
+	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_ref);
+	num_refs = btrfs_ref_num_refs(leaf, ref);
+	BUG_ON(num_refs == 0);
+	num_refs -= 1;
+	if (num_refs == 0) {
+		ret = btrfs_del_item(trans, root, path);
+	} else {
+		btrfs_set_ref_num_refs(leaf, ref, num_refs);
+		btrfs_mark_buffer_dirty(leaf);
+	}
+	btrfs_release_path(root, path);
+	return ret;
+}
+
+static int __btrfs_update_extent_ref(struct btrfs_trans_handle *trans,
+				     struct btrfs_root *root, u64 bytenr,
+				     u64 orig_parent, u64 parent,
+				     u64 orig_root, u64 ref_root,
+				     u64 orig_generation, u64 ref_generation,
+				     u64 owner_objectid)
+{
+	int ret;
+	struct btrfs_root *extent_root = root->fs_info->extent_root;
+	struct btrfs_path *path;
+
+	if (root == root->fs_info->extent_root) {
+		struct pending_extent_op *extent_op;
+		u64 num_bytes;
+
+		BUG_ON(owner_objectid >= BTRFS_MAX_LEVEL);
+		num_bytes = btrfs_level_size(root, (int)owner_objectid);
+		if (test_range_bit(&root->fs_info->extent_ins, bytenr,
+				bytenr + num_bytes - 1, EXTENT_LOCKED, 0)) {
+			u64 priv;
+			ret = get_state_private(&root->fs_info->extent_ins,
+						bytenr, &priv);
+			BUG_ON(ret);
+			extent_op = (struct pending_extent_op *)
+							(unsigned long)priv;
+			BUG_ON(extent_op->parent != orig_parent);
+			BUG_ON(extent_op->generation != orig_generation);
+			extent_op->parent = parent;
+			extent_op->generation = ref_generation;
+		} else {
+			extent_op = kmalloc(sizeof(*extent_op), GFP_NOFS);
+			BUG_ON(!extent_op);
+
+			extent_op->type = PENDING_BACKREF_UPDATE;
+			extent_op->bytenr = bytenr;
+			extent_op->num_bytes = num_bytes;
+			extent_op->parent = parent;
+			extent_op->orig_parent = orig_parent;
+			extent_op->generation = ref_generation;
+			extent_op->orig_generation = orig_generation;
+			extent_op->level = (int)owner_objectid;
+
+			set_extent_bits(&root->fs_info->extent_ins,
+					bytenr, bytenr + num_bytes - 1,
+					EXTENT_LOCKED, GFP_NOFS);
+			set_state_private(&root->fs_info->extent_ins,
+					  bytenr, (unsigned long)extent_op);
+		}
+		return 0;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	ret = lookup_extent_backref(trans, extent_root, path,
+				    bytenr, orig_parent, orig_root,
+				    orig_generation, owner_objectid, 1);
+	if (ret)
+		goto out;
+	ret = remove_extent_backref(trans, extent_root, path);
+	if (ret)
+		goto out;
+	ret = insert_extent_backref(trans, extent_root, path, bytenr,
+				    parent, ref_root, ref_generation,
+				    owner_objectid);
+	BUG_ON(ret);
+	finish_current_insert(trans, extent_root);
+	del_pending_extents(trans, extent_root);
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+int btrfs_update_extent_ref(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root, u64 bytenr,
+			    u64 orig_parent, u64 parent,
+			    u64 ref_root, u64 ref_generation,
+			    u64 owner_objectid)
+{
+	int ret;
+	if (ref_root == BTRFS_TREE_LOG_OBJECTID &&
+	    owner_objectid < BTRFS_FIRST_FREE_OBJECTID)
+		return 0;
+	maybe_lock_mutex(root);
+	ret = __btrfs_update_extent_ref(trans, root, bytenr, orig_parent,
+					parent, ref_root, ref_root,
+					ref_generation, ref_generation,
+					owner_objectid);
+	maybe_unlock_mutex(root);
+	return ret;
+}
+
+static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root, u64 bytenr,
+				  u64 orig_parent, u64 parent,
+				  u64 orig_root, u64 ref_root,
+				  u64 orig_generation, u64 ref_generation,
+				  u64 owner_objectid)
+{
+	struct btrfs_path *path;
+	int ret;
+	struct btrfs_key key;
+	struct extent_buffer *l;
+	struct btrfs_extent_item *item;
+	u32 refs;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->reada = 1;
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+	key.offset = (u64)-1;
+
+	ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
+				0, 1);
+	if (ret < 0)
+		return ret;
+	BUG_ON(ret == 0 || path->slots[0] == 0);
+
+	path->slots[0]--;
+	l = path->nodes[0];
+
+	btrfs_item_key_to_cpu(l, &key, path->slots[0]);
+	BUG_ON(key.objectid != bytenr);
+	BUG_ON(key.type != BTRFS_EXTENT_ITEM_KEY);
+
+	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);
+
+	path->reada = 1;
+	ret = insert_extent_backref(trans, root->fs_info->extent_root,
+				    path, bytenr, parent,
+				    ref_root, ref_generation,
+				    owner_objectid);
+	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);
+	return 0;
+}
+
+int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+			 struct btrfs_root *root,
+			 u64 bytenr, u64 num_bytes, u64 parent,
+			 u64 ref_root, u64 ref_generation,
+			 u64 owner_objectid)
+{
+	int ret;
+	if (ref_root == BTRFS_TREE_LOG_OBJECTID &&
+	    owner_objectid < BTRFS_FIRST_FREE_OBJECTID)
+		return 0;
+	maybe_lock_mutex(root);
+	ret = __btrfs_inc_extent_ref(trans, root, bytenr, 0, parent,
+				     0, ref_root, 0, ref_generation,
+				     owner_objectid);
+	maybe_unlock_mutex(root);
+	return ret;
+}
+
+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_ref(struct btrfs_trans_handle *trans,
+			    struct btrfs_root *root, u64 bytenr,
+			    u64 num_bytes, u32 *refs)
+{
+	struct btrfs_path *path;
+	int ret;
+	struct btrfs_key key;
+	struct extent_buffer *l;
+	struct btrfs_extent_item *item;
+
+	WARN_ON(num_bytes < root->sectorsize);
+	path = btrfs_alloc_path();
+	path->reada = 1;
+	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 %Lu\n", 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 get_reference_status(struct btrfs_root *root, u64 bytenr,
+				u64 parent_gen, u64 ref_objectid,
+			        u64 *min_generation, u32 *ref_count)
+{
+	struct btrfs_root *extent_root = root->fs_info->extent_root;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_extent_ref *ref_item;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	u64 root_objectid = root->root_key.objectid;
+	u64 ref_generation;
+	u32 nritems;
+	int ret;
+
+	key.objectid = bytenr;
+	key.offset = (u64)-1;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+
+	path = btrfs_alloc_path();
+	mutex_lock(&root->fs_info->alloc_mutex);
+	ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+	BUG_ON(ret == 0);
+	if (ret < 0 || path->slots[0] == 0)
+		goto out;
+
+	path->slots[0]--;
+	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_ITEM_KEY) {
+		ret = 1;
+		goto out;
+	}
+
+	*ref_count = 0;
+	*min_generation = (u64)-1;
+
+	while (1) {
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(extent_root, path);
+			if (ret < 0)
+				goto out;
+			if (ret == 0)
+				continue;
+			break;
+		}
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.objectid != bytenr)
+			break;
+
+		if (found_key.type != BTRFS_EXTENT_REF_KEY) {
+			path->slots[0]++;
+			continue;
+		}
+
+		ref_item = btrfs_item_ptr(leaf, path->slots[0],
+					  struct btrfs_extent_ref);
+		ref_generation = btrfs_ref_generation(leaf, ref_item);
+		/*
+		 * For (parent_gen > 0 && parent_gen > ref_generation):
+		 *
+		 * we reach here through the oldest root, therefore
+		 * all other reference from same snapshot should have
+		 * a larger generation.
+		 */
+		if ((root_objectid != btrfs_ref_root(leaf, ref_item)) ||
+		    (parent_gen > 0 && parent_gen > ref_generation) ||
+		    (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID &&
+		     ref_objectid != btrfs_ref_objectid(leaf, ref_item))) {
+			*ref_count = 2;
+			break;
+		}
+
+		*ref_count = 1;
+		if (*min_generation > ref_generation)
+			*min_generation = ref_generation;
+
+		path->slots[0]++;
+	}
+	ret = 0;
+out:
+	mutex_unlock(&root->fs_info->alloc_mutex);
+	btrfs_free_path(path);
+	return ret;
+}
+
+int btrfs_cross_ref_exists(struct btrfs_trans_handle *trans,
+			   struct btrfs_root *root,
+			   struct btrfs_key *key, u64 bytenr)
+{
+	struct btrfs_root *old_root;
+	struct btrfs_path *path = NULL;
+	struct extent_buffer *eb;
+	struct btrfs_file_extent_item *item;
+	u64 ref_generation;
+	u64 min_generation;
+	u64 extent_start;
+	u32 ref_count;
+	int level;
+	int ret;
+
+	BUG_ON(trans == NULL);
+	BUG_ON(key->type != BTRFS_EXTENT_DATA_KEY);
+	ret = get_reference_status(root, bytenr, 0, key->objectid,
+				   &min_generation, &ref_count);
+	if (ret)
+		return ret;
+
+	if (ref_count != 1)
+		return 1;
+
+	old_root = root->dirty_root->root;
+	ref_generation = old_root->root_key.offset;
+
+	/* all references are created in running transaction */
+	if (min_generation > ref_generation) {
+		ret = 0;
+		goto out;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	path->skip_locking = 1;
+	/* if no item found, the extent is referenced by other snapshot */
+	ret = btrfs_search_slot(NULL, old_root, key, path, 0, 0);
+	if (ret)
+		goto out;
+
+	eb = path->nodes[0];
+	item = btrfs_item_ptr(eb, path->slots[0],
+			      struct btrfs_file_extent_item);
+	if (btrfs_file_extent_type(eb, item) != BTRFS_FILE_EXTENT_REG ||
+	    btrfs_file_extent_disk_bytenr(eb, item) != bytenr) {
+		ret = 1;
+		goto out;
+	}
+
+	for (level = BTRFS_MAX_LEVEL - 1; level >= -1; level--) {
+		if (level >= 0) {
+			eb = path->nodes[level];
+			if (!eb)
+				continue;
+			extent_start = eb->start;
+		} else
+			extent_start = bytenr;
+
+		ret = get_reference_status(root, extent_start, ref_generation,
+					   0, &min_generation, &ref_count);
+		if (ret)
+			goto out;
+
+		if (ref_count != 1) {
+			ret = 1;
+			goto out;
+		}
+		if (level >= 0)
+			ref_generation = btrfs_header_generation(eb);
+	}
+	ret = 0;
+out:
+	if (path)
+		btrfs_free_path(path);
+	return ret;
+}
+
+int btrfs_cache_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		    struct extent_buffer *buf, u32 nr_extents)
+{
+	struct btrfs_key key;
+	struct btrfs_file_extent_item *fi;
+	u64 root_gen;
+	u32 nritems;
+	int i;
+	int level;
+	int ret = 0;
+	int shared = 0;
+
+	if (!root->ref_cows)
+		return 0;
+
+	if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
+		shared = 0;
+		root_gen = root->root_key.offset;
+	} else {
+		shared = 1;
+		root_gen = trans->transid - 1;
+	}
+
+	level = btrfs_header_level(buf);
+	nritems = btrfs_header_nritems(buf);
+
+	if (level == 0) {
+		struct btrfs_leaf_ref *ref;
+		struct btrfs_extent_info *info;
+
+		ref = btrfs_alloc_leaf_ref(root, nr_extents);
+		if (!ref) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		ref->root_gen = root_gen;
+		ref->bytenr = buf->start;
+		ref->owner = btrfs_header_owner(buf);
+		ref->generation = btrfs_header_generation(buf);
+		ref->nritems = nr_extents;
+		info = ref->extents;
+
+		for (i = 0; nr_extents > 0 && i < nritems; i++) {
+			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;
+
+			info->bytenr = disk_bytenr;
+			info->num_bytes =
+				btrfs_file_extent_disk_num_bytes(buf, fi);
+			info->objectid = key.objectid;
+			info->offset = key.offset;
+			info++;
+		}
+
+		ret = btrfs_add_leaf_ref(root, ref, shared);
+		if (ret == -EEXIST && shared) {
+			struct btrfs_leaf_ref *old;
+			old = btrfs_lookup_leaf_ref(root, ref->bytenr);
+			BUG_ON(!old);
+			btrfs_remove_leaf_ref(root, old);
+			btrfs_free_leaf_ref(root, old);
+			ret = btrfs_add_leaf_ref(root, ref, shared);
+		}
+		WARN_ON(ret);
+		btrfs_free_leaf_ref(root, ref);
+	}
+out:
+	return ret;
+}
+
+int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		  struct extent_buffer *orig_buf, struct extent_buffer *buf,
+		  u32 *nr_extents)
+{
+	u64 bytenr;
+	u64 ref_root;
+	u64 orig_root;
+	u64 ref_generation;
+	u64 orig_generation;
+	u32 nritems;
+	u32 nr_file_extents = 0;
+	struct btrfs_key key;
+	struct btrfs_file_extent_item *fi;
+	int i;
+	int level;
+	int ret = 0;
+	int faili = 0;
+	int (*process_func)(struct btrfs_trans_handle *, struct btrfs_root *,
+			    u64, u64, u64, u64, u64, u64, u64, u64);
+
+	ref_root = btrfs_header_owner(buf);
+	ref_generation = btrfs_header_generation(buf);
+	orig_root = btrfs_header_owner(orig_buf);
+	orig_generation = btrfs_header_generation(orig_buf);
+
+	nritems = btrfs_header_nritems(buf);
+	level = btrfs_header_level(buf);
+
+	if (root->ref_cows) {
+		process_func = __btrfs_inc_extent_ref;
+	} else {
+		if (level == 0 &&
+		    root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID)
+			goto out;
+		if (level != 0 &&
+		    root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID)
+			goto out;
+		process_func = __btrfs_update_extent_ref;
+	}
+
+	for (i = 0; i < nritems; i++) {
+		cond_resched();
+		if (level == 0) {
+			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;
+			bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
+			if (bytenr == 0)
+				continue;
+
+			nr_file_extents++;
+
+			maybe_lock_mutex(root);
+			ret = process_func(trans, root, bytenr,
+					   orig_buf->start, buf->start,
+					   orig_root, ref_root,
+					   orig_generation, ref_generation,
+					   key.objectid);
+			maybe_unlock_mutex(root);
+
+			if (ret) {
+				faili = i;
+				WARN_ON(1);
+				goto fail;
+			}
+		} else {
+			bytenr = btrfs_node_blockptr(buf, i);
+			maybe_lock_mutex(root);
+			ret = process_func(trans, root, bytenr,
+					   orig_buf->start, buf->start,
+					   orig_root, ref_root,
+					   orig_generation, ref_generation,
+					   level - 1);
+			maybe_unlock_mutex(root);
+			if (ret) {
+				faili = i;
+				WARN_ON(1);
+				goto fail;
+			}
+		}
+	}
+out:
+	if (nr_extents) {
+		if (level == 0)
+			*nr_extents = nr_file_extents;
+		else
+			*nr_extents = nritems;
+	}
+	return 0;
+fail:
+	WARN_ON(1);
+	return ret;
+}
+
+int btrfs_update_ref(struct btrfs_trans_handle *trans,
+		     struct btrfs_root *root, struct extent_buffer *orig_buf,
+		     struct extent_buffer *buf, int start_slot, int nr)
+
+{
+	u64 bytenr;
+	u64 ref_root;
+	u64 orig_root;
+	u64 ref_generation;
+	u64 orig_generation;
+	struct btrfs_key key;
+	struct btrfs_file_extent_item *fi;
+	int i;
+	int ret;
+	int slot;
+	int level;
+
+	BUG_ON(start_slot < 0);
+	BUG_ON(start_slot + nr > btrfs_header_nritems(buf));
+
+	ref_root = btrfs_header_owner(buf);
+	ref_generation = btrfs_header_generation(buf);
+	orig_root = btrfs_header_owner(orig_buf);
+	orig_generation = btrfs_header_generation(orig_buf);
+	level = btrfs_header_level(buf);
+
+	if (!root->ref_cows) {
+		if (level == 0 &&
+		    root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID)
+			return 0;
+		if (level != 0 &&
+		    root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID)
+			return 0;
+	}
+
+	for (i = 0, slot = start_slot; i < nr; i++, slot++) {
+		cond_resched();
+		if (level == 0) {
+			btrfs_item_key_to_cpu(buf, &key, slot);
+			if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY)
+				continue;
+			fi = btrfs_item_ptr(buf, slot,
+					    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;
+			maybe_lock_mutex(root);
+			ret = __btrfs_update_extent_ref(trans, root, bytenr,
+					    orig_buf->start, buf->start,
+					    orig_root, ref_root,
+					    orig_generation, ref_generation,
+					    key.objectid);
+			maybe_unlock_mutex(root);
+			if (ret)
+				goto fail;
+		} else {
+			bytenr = btrfs_node_blockptr(buf, slot);
+			maybe_lock_mutex(root);
+			ret = __btrfs_update_extent_ref(trans, root, bytenr,
+					    orig_buf->start, buf->start,
+					    orig_root, ref_root,
+					    orig_generation, ref_generation,
+					    level - 1);
+			maybe_unlock_mutex(root);
+			if (ret)
+				goto fail;
+		}
+	}
+	return 0;
+fail:
+	WARN_ON(1);
+	return -1;
+}
+
+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;
+
+	ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1);
+	if (ret < 0)
+		goto fail;
+	BUG_ON(ret);
+
+	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;
+
+}
+
+int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
+				   struct btrfs_root *root)
+{
+	struct btrfs_block_group_cache *cache, *entry;
+	struct rb_node *n;
+	int err = 0;
+	int werr = 0;
+	struct btrfs_path *path;
+	u64 last = 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+	while(1) {
+		cache = NULL;
+		spin_lock(&root->fs_info->block_group_cache_lock);
+		for (n = rb_first(&root->fs_info->block_group_cache_tree);
+		     n; n = rb_next(n)) {
+			entry = rb_entry(n, struct btrfs_block_group_cache,
+					 cache_node);
+			if (entry->dirty) {
+				cache = entry;
+				break;
+			}
+		}
+		spin_unlock(&root->fs_info->block_group_cache_lock);
+
+		if (!cache)
+			break;
+
+		cache->dirty = 0;
+		last += cache->key.offset;
+
+		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;
+		}
+	}
+	btrfs_free_path(path);
+	mutex_unlock(&root->fs_info->alloc_mutex);
+	return werr;
+}
+
+static int update_space_info(struct btrfs_fs_info *info, u64 flags,
+			     u64 total_bytes, u64 bytes_used,
+			     struct btrfs_space_info **space_info)
+{
+	struct btrfs_space_info *found;
+
+	found = __find_space_info(info, flags);
+	if (found) {
+		found->total_bytes += total_bytes;
+		found->bytes_used += bytes_used;
+		found->full = 0;
+		*space_info = found;
+		return 0;
+	}
+	found = kmalloc(sizeof(*found), GFP_NOFS);
+	if (!found)
+		return -ENOMEM;
+
+	list_add(&found->list, &info->space_info);
+	INIT_LIST_HEAD(&found->block_groups);
+	spin_lock_init(&found->lock);
+	found->flags = flags;
+	found->total_bytes = total_bytes;
+	found->bytes_used = bytes_used;
+	found->bytes_pinned = 0;
+	found->bytes_reserved = 0;
+	found->full = 0;
+	found->force_alloc = 0;
+	*space_info = found;
+	return 0;
+}
+
+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_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;
+	}
+}
+
+static u64 reduce_alloc_profile(struct btrfs_root *root, u64 flags)
+{
+	u64 num_devices = root->fs_info->fs_devices->num_devices;
+
+	if (num_devices == 1)
+		flags &= ~(BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID0);
+	if (num_devices < 4)
+		flags &= ~BTRFS_BLOCK_GROUP_RAID10;
+
+	if ((flags & BTRFS_BLOCK_GROUP_DUP) &&
+	    (flags & (BTRFS_BLOCK_GROUP_RAID1 |
+		      BTRFS_BLOCK_GROUP_RAID10))) {
+		flags &= ~BTRFS_BLOCK_GROUP_DUP;
+	}
+
+	if ((flags & BTRFS_BLOCK_GROUP_RAID1) &&
+	    (flags & BTRFS_BLOCK_GROUP_RAID10)) {
+		flags &= ~BTRFS_BLOCK_GROUP_RAID1;
+	}
+
+	if ((flags & BTRFS_BLOCK_GROUP_RAID0) &&
+	    ((flags & BTRFS_BLOCK_GROUP_RAID1) |
+	     (flags & BTRFS_BLOCK_GROUP_RAID10) |
+	     (flags & BTRFS_BLOCK_GROUP_DUP)))
+		flags &= ~BTRFS_BLOCK_GROUP_RAID0;
+	return flags;
+}
+
+static int do_chunk_alloc(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *extent_root, u64 alloc_bytes,
+			  u64 flags, int force)
+{
+	struct btrfs_space_info *space_info;
+	u64 thresh;
+	u64 start;
+	u64 num_bytes;
+	int ret = 0, waited = 0;
+
+	flags = reduce_alloc_profile(extent_root, flags);
+
+	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);
+
+	if (space_info->force_alloc) {
+		force = 1;
+		space_info->force_alloc = 0;
+	}
+	if (space_info->full)
+		goto out;
+
+	thresh = div_factor(space_info->total_bytes, 6);
+	if (!force &&
+	   (space_info->bytes_used + space_info->bytes_pinned +
+	    space_info->bytes_reserved + alloc_bytes) < thresh)
+		goto out;
+
+	while (!mutex_trylock(&extent_root->fs_info->chunk_mutex)) {
+		if (!force)
+			goto out;
+		mutex_unlock(&extent_root->fs_info->alloc_mutex);
+		cond_resched();
+		mutex_lock(&extent_root->fs_info->alloc_mutex);
+		waited = 1;
+	}
+
+	if (waited && space_info->full)
+		goto out_unlock;
+
+	ret = btrfs_alloc_chunk(trans, extent_root, &start, &num_bytes, flags);
+	if (ret == -ENOSPC) {
+printk("space info full %Lu\n", flags);
+		space_info->full = 1;
+		goto out_unlock;
+	}
+	BUG_ON(ret);
+
+	ret = btrfs_make_block_group(trans, extent_root, 0, flags,
+		     BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes);
+	BUG_ON(ret);
+
+out_unlock:
+	mutex_unlock(&extent_root->fs_info->chunk_mutex);
+out:
+	return ret;
+}
+
+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;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	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);
+
+		spin_lock(&cache->lock);
+		cache->dirty = 1;
+		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;
+			btrfs_set_block_group_used(&cache->item, old_val);
+			spin_unlock(&cache->lock);
+		} else {
+			old_val -= num_bytes;
+			cache->space_info->bytes_used -= num_bytes;
+			btrfs_set_block_group_used(&cache->item, old_val);
+			spin_unlock(&cache->lock);
+			if (mark_free) {
+				int ret;
+				ret = btrfs_add_free_space(cache, bytenr,
+							   num_bytes);
+				if (ret)
+					return -1;
+			}
+		}
+		total -= num_bytes;
+		bytenr += num_bytes;
+	}
+	return 0;
+}
+
+static u64 first_logical_byte(struct btrfs_root *root, u64 search_start)
+{
+	struct btrfs_block_group_cache *cache;
+
+	cache = btrfs_lookup_first_block_group(root->fs_info, search_start);
+	if (!cache)
+		return 0;
+
+	return cache->key.objectid;
+}
+
+int btrfs_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;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	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);
+		BUG_ON(!cache);
+		len = min(num, cache->key.offset -
+			  (bytenr - cache->key.objectid));
+		if (pin) {
+			spin_lock(&cache->lock);
+			cache->pinned += len;
+			cache->space_info->bytes_pinned += len;
+			spin_unlock(&cache->lock);
+			fs_info->total_pinned += len;
+		} else {
+			spin_lock(&cache->lock);
+			cache->pinned -= len;
+			cache->space_info->bytes_pinned -= len;
+			spin_unlock(&cache->lock);
+			fs_info->total_pinned -= len;
+		}
+		bytenr += len;
+		num -= len;
+	}
+	return 0;
+}
+
+static int update_reserved_extents(struct btrfs_root *root,
+				   u64 bytenr, u64 num, int reserve)
+{
+	u64 len;
+	struct btrfs_block_group_cache *cache;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	while (num > 0) {
+		cache = btrfs_lookup_block_group(fs_info, bytenr);
+		BUG_ON(!cache);
+		len = min(num, cache->key.offset -
+			  (bytenr - cache->key.objectid));
+		if (reserve) {
+			spin_lock(&cache->lock);
+			cache->reserved += len;
+			cache->space_info->bytes_reserved += len;
+			spin_unlock(&cache->lock);
+		} else {
+			spin_lock(&cache->lock);
+			cache->reserved -= len;
+			cache->space_info->bytes_reserved -= len;
+			spin_unlock(&cache->lock);
+		}
+		bytenr += len;
+		num -= len;
+	}
+	return 0;
+}
+
+int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy)
+{
+	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;
+	}
+	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 btrfs_block_group_cache *cache;
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+	while(1) {
+		ret = find_first_extent_bit(unpin, 0, &start, &end,
+					    EXTENT_DIRTY);
+		if (ret)
+			break;
+		btrfs_update_pinned_extents(root, start, end + 1 - start, 0);
+		clear_extent_dirty(unpin, start, end, GFP_NOFS);
+		cache = btrfs_lookup_block_group(root->fs_info, start);
+		if (cache->cached)
+			btrfs_add_free_space(cache, start, end - start + 1);
+		if (need_resched()) {
+			mutex_unlock(&root->fs_info->alloc_mutex);
+			cond_resched();
+			mutex_lock(&root->fs_info->alloc_mutex);
+		}
+	}
+	mutex_unlock(&root->fs_info->alloc_mutex);
+	return 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 btrfs_path *path;
+	struct btrfs_extent_ref *ref;
+	struct pending_extent_op *extent_op;
+	struct btrfs_key key;
+	struct btrfs_extent_item extent_item;
+	int ret;
+	int err = 0;
+
+	WARN_ON(!mutex_is_locked(&extent_root->fs_info->alloc_mutex));
+	btrfs_set_stack_extent_refs(&extent_item, 1);
+	path = btrfs_alloc_path();
+
+	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;
+			key.offset = end + 1 - start;
+			key.type = BTRFS_EXTENT_ITEM_KEY;
+			err = btrfs_insert_item(trans, extent_root, &key,
+					&extent_item, sizeof(extent_item));
+			BUG_ON(err);
+
+			clear_extent_bits(&info->extent_ins, start, end,
+					  EXTENT_LOCKED, GFP_NOFS);
+
+			err = insert_extent_backref(trans, extent_root, path,
+						start, extent_op->parent,
+						extent_root->root_key.objectid,
+						extent_op->generation,
+						extent_op->level);
+			BUG_ON(err);
+		} else if (extent_op->type == PENDING_BACKREF_UPDATE) {
+			err = lookup_extent_backref(trans, extent_root, path,
+						start, extent_op->orig_parent,
+						extent_root->root_key.objectid,
+						extent_op->orig_generation,
+						extent_op->level, 0);
+			BUG_ON(err);
+
+			clear_extent_bits(&info->extent_ins, start, end,
+					  EXTENT_LOCKED, GFP_NOFS);
+
+			key.objectid = start;
+			key.offset = extent_op->parent;
+			key.type = BTRFS_EXTENT_REF_KEY;
+			err = btrfs_set_item_key_safe(trans, extent_root, path,
+						      &key);
+			BUG_ON(err);
+			ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
+					     struct btrfs_extent_ref);
+			btrfs_set_ref_generation(path->nodes[0], ref,
+						 extent_op->generation);
+			btrfs_mark_buffer_dirty(path->nodes[0]);
+			btrfs_release_path(extent_root, path);
+		} else {
+			BUG_ON(1);
+		}
+		kfree(extent_op);
+
+		if (need_resched()) {
+			mutex_unlock(&extent_root->fs_info->alloc_mutex);
+			cond_resched();
+			mutex_lock(&extent_root->fs_info->alloc_mutex);
+		}
+	}
+	btrfs_free_path(path);
+	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;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	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) &&
+	    btrfs_try_tree_lock(buf)) {
+		u64 header_owner = btrfs_header_owner(buf);
+		u64 header_transid = btrfs_header_generation(buf);
+		if (header_owner != BTRFS_TREE_LOG_OBJECTID &&
+		    header_owner != BTRFS_TREE_RELOC_OBJECTID &&
+		    header_transid == trans->transid &&
+		    !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
+			clean_tree_block(NULL, root, buf);
+			btrfs_tree_unlock(buf);
+			free_extent_buffer(buf);
+			return 1;
+		}
+		btrfs_tree_unlock(buf);
+	}
+	free_extent_buffer(buf);
+pinit:
+	btrfs_update_pinned_extents(root, bytenr, num_bytes, 1);
+
+	BUG_ON(err < 0);
+	return 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 ref_generation,
+			 u64 owner_objectid, int pin, int mark_free)
+{
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_root *extent_root = info->extent_root;
+	struct extent_buffer *leaf;
+	int ret;
+	int extent_slot = 0;
+	int found_extent = 0;
+	int num_to_del = 1;
+	struct btrfs_extent_item *ei;
+	u32 refs;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	key.objectid = bytenr;
+	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
+	key.offset = num_bytes;
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	path->reada = 1;
+	ret = lookup_extent_backref(trans, extent_root, path,
+				    bytenr, parent, root_objectid,
+				    ref_generation, owner_objectid, 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 = remove_extent_backref(trans, extent_root, path);
+			BUG_ON(ret);
+			btrfs_release_path(extent_root, path);
+			ret = btrfs_search_slot(trans, extent_root,
+						&key, path, -1, 1);
+			BUG_ON(ret);
+			extent_slot = path->slots[0];
+		}
+	} else {
+		btrfs_print_leaf(extent_root, path->nodes[0]);
+		WARN_ON(1);
+		printk("Unable to find ref byte nr %Lu root %Lu "
+		       "gen %Lu owner %Lu\n", bytenr,
+		       root_objectid, ref_generation, owner_objectid);
+	}
+
+	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);
+
+	btrfs_mark_buffer_dirty(leaf);
+
+	if (refs == 0 && found_extent && path->slots[0] == extent_slot + 1) {
+		struct btrfs_extent_ref *ref;
+		ref = btrfs_item_ptr(leaf, path->slots[0],
+				     struct btrfs_extent_ref);
+		BUG_ON(btrfs_ref_num_refs(leaf, ref) != 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 = remove_extent_backref(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);
+			BUG_ON(ret);
+		}
+	}
+
+	if (refs == 0) {
+		u64 super_used;
+		u64 root_used;
+#ifdef BIO_RW_DISCARD
+		u64 map_length = num_bytes;
+		struct btrfs_multi_bio *multi = NULL;
+#endif
+
+		if (pin) {
+			ret = pin_down_bytes(trans, root, bytenr, num_bytes,
+				owner_objectid >= BTRFS_FIRST_FREE_OBJECTID);
+			if (ret > 0)
+				mark_free = 1;
+			BUG_ON(ret < 0);
+		}
+
+		/* block accounting for super block */
+		spin_lock_irq(&info->delalloc_lock);
+		super_used = btrfs_super_bytes_used(&info->super_copy);
+		btrfs_set_super_bytes_used(&info->super_copy,
+					   super_used - num_bytes);
+		spin_unlock_irq(&info->delalloc_lock);
+
+		/* 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);
+		BUG_ON(ret);
+		ret = update_block_group(trans, root, bytenr, num_bytes, 0,
+					 mark_free);
+		BUG_ON(ret);
+
+#ifdef BIO_RW_DISCARD
+		/* Tell the block device(s) that the sectors can be discarded */
+		ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,
+				      bytenr, &map_length, &multi, 0);
+		if (!ret) {
+			struct btrfs_bio_stripe *stripe = multi->stripes;
+			int i;
+
+			if (map_length > num_bytes)
+				map_length = num_bytes;
+
+			for (i = 0; i < multi->num_stripes; i++, stripe++) {
+				blkdev_issue_discard(stripe->dev->bdev,
+						     stripe->physical >> 9,
+						     map_length >> 9);
+			}
+			kfree(multi);
+		}
+#endif
+	}
+	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;
+	int mark_free = 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;
+
+	WARN_ON(!mutex_is_locked(&extent_root->fs_info->alloc_mutex));
+	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);
+
+		ret = pin_down_bytes(trans, extent_root, start,
+				     end + 1 - start, 0);
+		mark_free = ret > 0;
+		if (!test_range_bit(extent_ins, start, end,
+				    EXTENT_LOCKED, 0)) {
+free_extent:
+			ret = __free_extent(trans, extent_root,
+					    start, end + 1 - start,
+					    extent_op->orig_parent,
+					    extent_root->root_key.objectid,
+					    extent_op->orig_generation,
+					    extent_op->level, 0, mark_free);
+			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)
+				goto free_extent;
+
+			ret = update_block_group(trans, extent_root, start,
+						end + 1 - start, 0, mark_free);
+			BUG_ON(ret);
+			kfree(extent_op);
+		}
+		if (ret)
+			err = ret;
+
+		if (need_resched()) {
+			mutex_unlock(&extent_root->fs_info->alloc_mutex);
+			cond_resched();
+			mutex_lock(&extent_root->fs_info->alloc_mutex);
+		}
+	}
+	return err;
+}
+
+/*
+ * remove an extent from the root, returns 0 on success
+ */
+static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root,
+			       u64 bytenr, u64 num_bytes, u64 parent,
+			       u64 root_objectid, u64 ref_generation,
+			       u64 owner_objectid, int pin)
+{
+	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->parent = parent;
+		extent_op->orig_parent = parent;
+		extent_op->generation = ref_generation;
+		extent_op->orig_generation = ref_generation;
+		extent_op->level = (int)owner_objectid;
+
+		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;
+	}
+	/* if metadata always pin */
+	if (owner_objectid < BTRFS_FIRST_FREE_OBJECTID) {
+		if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
+			struct btrfs_block_group_cache *cache;
+
+			/* btrfs_free_reserved_extent */
+			cache = btrfs_lookup_block_group(root->fs_info, bytenr);
+			BUG_ON(!cache);
+			btrfs_add_free_space(cache, bytenr, num_bytes);
+			update_reserved_extents(root, bytenr, num_bytes, 0);
+			return 0;
+		}
+		pin = 1;
+	}
+
+	/* if data pin when any transaction has committed this */
+	if (ref_generation != trans->transid)
+		pin = 1;
+
+	ret = __free_extent(trans, root, bytenr, num_bytes, parent,
+			    root_objectid, ref_generation,
+			    owner_objectid, pin, pin == 0);
+
+	finish_current_insert(trans, root->fs_info->extent_root);
+	pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
+	return ret ? ret : pending_ret;
+}
+
+int btrfs_free_extent(struct btrfs_trans_handle *trans,
+		      struct btrfs_root *root,
+		      u64 bytenr, u64 num_bytes, u64 parent,
+		      u64 root_objectid, u64 ref_generation,
+		      u64 owner_objectid, int pin)
+{
+	int ret;
+
+	maybe_lock_mutex(root);
+	ret = __btrfs_free_extent(trans, root, bytenr, num_bytes, parent,
+				  root_objectid, ref_generation,
+				  owner_objectid, pin);
+	maybe_unlock_mutex(root);
+	return 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;
+	struct btrfs_root * root = orig_root->fs_info->extent_root;
+	struct btrfs_fs_info *info = root->fs_info;
+	u64 total_needed = num_bytes;
+	u64 *last_ptr = NULL;
+	struct btrfs_block_group_cache *block_group;
+	int chunk_alloc_done = 0;
+	int empty_cluster = 2 * 1024 * 1024;
+	int allowed_chunk_alloc = 0;
+
+	WARN_ON(num_bytes < root->sectorsize);
+	btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
+
+	if (orig_root->ref_cows || empty_size)
+		allowed_chunk_alloc = 1;
+
+	if (data & BTRFS_BLOCK_GROUP_METADATA) {
+		last_ptr = &root->fs_info->last_alloc;
+		empty_cluster = 256 * 1024;
+	}
+
+	if ((data & BTRFS_BLOCK_GROUP_DATA) && btrfs_test_opt(root, SSD))
+		last_ptr = &root->fs_info->last_data_alloc;
+
+	if (last_ptr) {
+		if (*last_ptr)
+			hint_byte = *last_ptr;
+		else
+			empty_size += empty_cluster;
+	}
+
+	search_start = max(search_start, first_logical_byte(root, 0));
+	orig_search_start = search_start;
+
+	search_start = max(search_start, hint_byte);
+	total_needed += empty_size;
+
+new_group:
+	block_group = btrfs_lookup_block_group(info, search_start);
+	if (!block_group)
+		block_group = btrfs_lookup_first_block_group(info,
+							     search_start);
+
+	/*
+	 * Ok this looks a little tricky, buts its really simple.  First if we
+	 * didn't find a block group obviously we want to start over.
+	 * Secondly, if the block group we found does not match the type we
+	 * need, and we have a last_ptr and its not 0, chances are the last
+	 * allocation we made was at the end of the block group, so lets go
+	 * ahead and skip the looking through the rest of the block groups and
+	 * start at the beginning.  This helps with metadata allocations,
+	 * since you are likely to have a bunch of data block groups to search
+	 * through first before you realize that you need to start over, so go
+	 * ahead and start over and save the time.
+	 */
+	if (!block_group || (!block_group_bits(block_group, data) &&
+			     last_ptr && *last_ptr)) {
+		if (search_start != orig_search_start) {
+			if (last_ptr && *last_ptr) {
+				total_needed += empty_cluster;
+				*last_ptr = 0;
+			}
+			search_start = orig_search_start;
+			goto new_group;
+		} else if (!chunk_alloc_done && allowed_chunk_alloc) {
+			ret = do_chunk_alloc(trans, root,
+					     num_bytes + 2 * 1024 * 1024,
+					     data, 1);
+			if (ret < 0)
+				goto error;
+			BUG_ON(ret);
+			chunk_alloc_done = 1;
+			search_start = orig_search_start;
+			goto new_group;
+		} else {
+			ret = -ENOSPC;
+			goto error;
+		}
+	}
+
+	/*
+	 * this is going to seach through all of the existing block groups it
+	 * can find, so if we don't find something we need to see if we can
+	 * allocate what we need.
+	 */
+	ret = find_free_space(root, &block_group, &search_start,
+			      total_needed, data);
+	if (ret == -ENOSPC) {
+		/*
+		 * instead of allocating, start at the original search start
+		 * and see if there is something to be found, if not then we
+		 * allocate
+		 */
+		if (search_start != orig_search_start) {
+			if (last_ptr && *last_ptr) {
+				*last_ptr = 0;
+				total_needed += empty_cluster;
+			}
+			search_start = orig_search_start;
+			goto new_group;
+		}
+
+		/*
+		 * we've already allocated, we're pretty screwed
+		 */
+		if (chunk_alloc_done) {
+			goto error;
+		} else if (!allowed_chunk_alloc && block_group &&
+			   block_group_bits(block_group, data)) {
+			block_group->space_info->force_alloc = 1;
+			goto error;
+		} else if (!allowed_chunk_alloc) {
+			goto error;
+		}
+
+		ret = do_chunk_alloc(trans, root, num_bytes + 2 * 1024 * 1024,
+				     data, 1);
+		if (ret < 0)
+			goto error;
+
+		BUG_ON(ret);
+		chunk_alloc_done = 1;
+		if (block_group)
+			search_start = block_group->key.objectid +
+				block_group->key.offset;
+		else
+			search_start = orig_search_start;
+		goto new_group;
+	}
+
+	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) {
+		search_start = orig_search_start;
+		if (chunk_alloc_done) {
+			ret = -ENOSPC;
+			goto error;
+		}
+		goto new_group;
+	}
+
+	if (ins->objectid + num_bytes >
+	    block_group->key.objectid + block_group->key.offset) {
+		if (search_start == orig_search_start && chunk_alloc_done) {
+			ret = -ENOSPC;
+			goto error;
+		}
+		search_start = block_group->key.objectid +
+			block_group->key.offset;
+		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))
+		trans->block_group = block_group;
+
+	ins->offset = num_bytes;
+	if (last_ptr) {
+		*last_ptr = ins->objectid + ins->offset;
+		if (*last_ptr ==
+		    btrfs_super_total_bytes(&root->fs_info->super_copy))
+			*last_ptr = 0;
+	}
+
+	ret = 0;
+error:
+	return ret;
+}
+
+static void dump_space_info(struct btrfs_space_info *info, u64 bytes)
+{
+	struct btrfs_block_group_cache *cache;
+	struct list_head *l;
+
+	printk(KERN_INFO "space_info has %Lu free, is %sfull\n",
+	       info->total_bytes - info->bytes_used - info->bytes_pinned -
+	       info->bytes_reserved, (info->full) ? "" : "not ");
+
+	spin_lock(&info->lock);
+	list_for_each(l, &info->block_groups) {
+		cache = list_entry(l, struct btrfs_block_group_cache, list);
+		spin_lock(&cache->lock);
+		printk(KERN_INFO "block group %Lu has %Lu bytes, %Lu used "
+		       "%Lu pinned %Lu reserved\n",
+		       cache->key.objectid, cache->key.offset,
+		       btrfs_block_group_used(&cache->item),
+		       cache->pinned, cache->reserved);
+		btrfs_dump_free_space(cache, bytes);
+		spin_unlock(&cache->lock);
+	}
+	spin_unlock(&info->lock);
+}
+
+static int __btrfs_reserve_extent(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root,
+				  u64 num_bytes, u64 min_alloc_size,
+				  u64 empty_size, u64 hint_byte,
+				  u64 search_end, struct btrfs_key *ins,
+				  u64 data)
+{
+	int ret;
+	u64 search_start = 0;
+	u64 alloc_profile;
+	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_block_group_cache *cache;
+
+	if (data) {
+		alloc_profile = info->avail_data_alloc_bits &
+			        info->data_alloc_profile;
+		data = BTRFS_BLOCK_GROUP_DATA | alloc_profile;
+	} else if (root == root->fs_info->chunk_root) {
+		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;
+	}
+again:
+	data = reduce_alloc_profile(root, data);
+	/*
+	 * the only place that sets empty_size is btrfs_realloc_node, which
+	 * is not called recursively on allocations
+	 */
+	if (empty_size || root->ref_cows) {
+		if (!(data & BTRFS_BLOCK_GROUP_METADATA)) {
+			ret = do_chunk_alloc(trans, root->fs_info->extent_root,
+				     2 * 1024 * 1024,
+				     BTRFS_BLOCK_GROUP_METADATA |
+				     (info->metadata_alloc_profile &
+				      info->avail_metadata_alloc_bits), 0);
+		}
+		ret = do_chunk_alloc(trans, root->fs_info->extent_root,
+				     num_bytes + 2 * 1024 * 1024, data, 0);
+	}
+
+	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);
+
+	if (ret == -ENOSPC && num_bytes > min_alloc_size) {
+		num_bytes = num_bytes >> 1;
+		num_bytes = num_bytes & ~(root->sectorsize - 1);
+		num_bytes = max(num_bytes, min_alloc_size);
+		do_chunk_alloc(trans, root->fs_info->extent_root,
+			       num_bytes, data, 1);
+		goto again;
+	}
+	if (ret) {
+		struct btrfs_space_info *sinfo;
+
+		sinfo = __find_space_info(root->fs_info, data);
+		printk("allocation failed flags %Lu, wanted %Lu\n",
+		       data, num_bytes);
+		dump_space_info(sinfo, num_bytes);
+		BUG();
+	}
+	cache = btrfs_lookup_block_group(root->fs_info, ins->objectid);
+	if (!cache) {
+		printk(KERN_ERR "Unable to find block group for %Lu\n", ins->objectid);
+		return -ENOSPC;
+	}
+
+	ret = btrfs_remove_free_space(cache, ins->objectid, ins->offset);
+
+	return ret;
+}
+
+int btrfs_free_reserved_extent(struct btrfs_root *root, u64 start, u64 len)
+{
+	struct btrfs_block_group_cache *cache;
+
+	maybe_lock_mutex(root);
+	cache = btrfs_lookup_block_group(root->fs_info, start);
+	if (!cache) {
+		printk(KERN_ERR "Unable to find block group for %Lu\n", start);
+		maybe_unlock_mutex(root);
+		return -ENOSPC;
+	}
+	btrfs_add_free_space(cache, start, len);
+	update_reserved_extents(root, start, len, 0);
+	maybe_unlock_mutex(root);
+	return 0;
+}
+
+int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
+				  struct btrfs_root *root,
+				  u64 num_bytes, u64 min_alloc_size,
+				  u64 empty_size, u64 hint_byte,
+				  u64 search_end, struct btrfs_key *ins,
+				  u64 data)
+{
+	int ret;
+	maybe_lock_mutex(root);
+	ret = __btrfs_reserve_extent(trans, root, num_bytes, min_alloc_size,
+				     empty_size, hint_byte, search_end, ins,
+				     data);
+	update_reserved_extents(root, ins->objectid, ins->offset, 1);
+	maybe_unlock_mutex(root);
+	return ret;
+}
+
+static int __btrfs_alloc_reserved_extent(struct btrfs_trans_handle *trans,
+					 struct btrfs_root *root, u64 parent,
+					 u64 root_objectid, u64 ref_generation,
+					 u64 owner, struct btrfs_key *ins)
+{
+	int ret;
+	int pending_ret;
+	u64 super_used;
+	u64 root_used;
+	u64 num_bytes = ins->offset;
+	u32 sizes[2];
+	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_root *extent_root = info->extent_root;
+	struct btrfs_extent_item *extent_item;
+	struct btrfs_extent_ref *ref;
+	struct btrfs_path *path;
+	struct btrfs_key keys[2];
+
+	if (parent == 0)
+		parent = ins->objectid;
+
+	/* block accounting for super block */
+	spin_lock_irq(&info->delalloc_lock);
+	super_used = btrfs_super_bytes_used(&info->super_copy);
+	btrfs_set_super_bytes_used(&info->super_copy, super_used + num_bytes);
+	spin_unlock_irq(&info->delalloc_lock);
+
+	/* block accounting for root item */
+	root_used = btrfs_root_used(&root->root_item);
+	btrfs_set_root_used(&root->root_item, root_used + num_bytes);
+
+	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_INSERT;
+		extent_op->bytenr = ins->objectid;
+		extent_op->num_bytes = ins->offset;
+		extent_op->parent = parent;
+		extent_op->orig_parent = 0;
+		extent_op->generation = ref_generation;
+		extent_op->orig_generation = 0;
+		extent_op->level = (int)owner;
+
+		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);
+		goto update_block;
+	}
+
+	memcpy(&keys[0], ins, sizeof(*ins));
+	keys[1].objectid = ins->objectid;
+	keys[1].type = BTRFS_EXTENT_REF_KEY;
+	keys[1].offset = parent;
+	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);
+	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);
+
+	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_num_refs(path->nodes[0], ref, 1);
+
+	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);
+
+	if (ret)
+		goto out;
+	if (pending_ret) {
+		ret = pending_ret;
+		goto out;
+	}
+
+update_block:
+	ret = update_block_group(trans, root, ins->objectid, ins->offset, 1, 0);
+	if (ret) {
+		printk("update block group failed for %Lu %Lu\n",
+		       ins->objectid, ins->offset);
+		BUG();
+	}
+out:
+	return ret;
+}
+
+int btrfs_alloc_reserved_extent(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root, u64 parent,
+				u64 root_objectid, u64 ref_generation,
+				u64 owner, struct btrfs_key *ins)
+{
+	int ret;
+
+	if (root_objectid == BTRFS_TREE_LOG_OBJECTID)
+		return 0;
+	maybe_lock_mutex(root);
+	ret = __btrfs_alloc_reserved_extent(trans, root, parent, root_objectid,
+					    ref_generation, owner, ins);
+	update_reserved_extents(root, ins->objectid, ins->offset, 0);
+	maybe_unlock_mutex(root);
+	return ret;
+}
+
+/*
+ * this is used by the tree logging recovery code.  It records that
+ * an extent has been allocated and makes sure to clear the free
+ * space cache bits as well
+ */
+int btrfs_alloc_logged_extent(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root, u64 parent,
+				u64 root_objectid, u64 ref_generation,
+				u64 owner, struct btrfs_key *ins)
+{
+	int ret;
+	struct btrfs_block_group_cache *block_group;
+
+	maybe_lock_mutex(root);
+	block_group = btrfs_lookup_block_group(root->fs_info, ins->objectid);
+	cache_block_group(root, block_group);
+
+	ret = btrfs_remove_free_space(block_group, ins->objectid, ins->offset);
+	BUG_ON(ret);
+	ret = __btrfs_alloc_reserved_extent(trans, root, parent, root_objectid,
+					    ref_generation, owner, ins);
+	maybe_unlock_mutex(root);
+	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 parent, u64 min_alloc_size,
+		       u64 root_objectid, u64 ref_generation,
+		       u64 owner_objectid, u64 empty_size, u64 hint_byte,
+		       u64 search_end, struct btrfs_key *ins, u64 data)
+{
+	int ret;
+
+	maybe_lock_mutex(root);
+
+	ret = __btrfs_reserve_extent(trans, root, num_bytes,
+				     min_alloc_size, empty_size, hint_byte,
+				     search_end, ins, data);
+	BUG_ON(ret);
+	if (root_objectid != BTRFS_TREE_LOG_OBJECTID) {
+		ret = __btrfs_alloc_reserved_extent(trans, root, parent,
+					root_objectid, ref_generation,
+					owner_objectid, ins);
+		BUG_ON(ret);
+
+	} else {
+		update_reserved_extents(root, ins->objectid, ins->offset, 1);
+	}
+	maybe_unlock_mutex(root);
+	return ret;
+}
+
+struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans,
+					    struct btrfs_root *root,
+					    u64 bytenr, u32 blocksize)
+{
+	struct extent_buffer *buf;
+
+	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+	btrfs_set_header_generation(buf, trans->transid);
+	btrfs_tree_lock(buf);
+	clean_tree_block(trans, root, buf);
+	btrfs_set_buffer_uptodate(buf);
+	if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
+		set_extent_dirty(&root->dirty_log_pages, buf->start,
+			 buf->start + buf->len - 1, GFP_NOFS);
+	} else {
+		set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
+			 buf->start + buf->len - 1, GFP_NOFS);
+	}
+	trans->blocks_used++;
+	return buf;
+}
+
+/*
+ * 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 parent,
+					     u64 root_objectid,
+					     u64 ref_generation,
+					     int level,
+					     u64 hint,
+					     u64 empty_size)
+{
+	struct btrfs_key ins;
+	int ret;
+	struct extent_buffer *buf;
+
+	ret = btrfs_alloc_extent(trans, root, blocksize, parent, blocksize,
+				 root_objectid, ref_generation, level,
+				 empty_size, hint, (u64)-1, &ins, 0);
+	if (ret) {
+		BUG_ON(ret > 0);
+		return ERR_PTR(ret);
+	}
+
+	buf = btrfs_init_new_buffer(trans, root, ins.objectid, blocksize);
+	return buf;
+}
+
+int btrfs_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;
+		cond_resched();
+
+		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)
+			continue;
+		/*
+		 * FIXME make sure to insert a trans record that
+		 * repeats the snapshot del on crash
+		 */
+		disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+		if (disk_bytenr == 0)
+			continue;
+
+		mutex_lock(&root->fs_info->alloc_mutex);
+		ret = __btrfs_free_extent(trans, root, disk_bytenr,
+				btrfs_file_extent_disk_num_bytes(leaf, fi),
+				leaf->start, leaf_owner, leaf_generation,
+				key.objectid, 0);
+		mutex_unlock(&root->fs_info->alloc_mutex);
+		BUG_ON(ret);
+
+		atomic_inc(&root->fs_info->throttle_gen);
+		wake_up(&root->fs_info->transaction_throttle);
+		cond_resched();
+	}
+	return 0;
+}
+
+static int noinline cache_drop_leaf_ref(struct btrfs_trans_handle *trans,
+					struct btrfs_root *root,
+					struct btrfs_leaf_ref *ref)
+{
+	int i;
+	int ret;
+	struct btrfs_extent_info *info = ref->extents;
+
+	for (i = 0; i < ref->nritems; i++) {
+		mutex_lock(&root->fs_info->alloc_mutex);
+		ret = __btrfs_free_extent(trans, root, info->bytenr,
+					  info->num_bytes, ref->bytenr,
+					  ref->owner, ref->generation,
+					  info->objectid, 0);
+		mutex_unlock(&root->fs_info->alloc_mutex);
+
+		atomic_inc(&root->fs_info->throttle_gen);
+		wake_up(&root->fs_info->transaction_throttle);
+		cond_resched();
+
+		BUG_ON(ret);
+		info++;
+	}
+
+	return 0;
+}
+
+int drop_snap_lookup_refcount(struct btrfs_root *root, u64 start, u64 len,
+			      u32 *refs)
+{
+	int ret;
+
+	ret = btrfs_lookup_extent_ref(NULL, root, start, len, refs);
+	BUG_ON(ret);
+
+#if 0 // some debugging code in case we see problems here
+	/* if the refs count is one, it won't get increased again.  But
+	 * if the ref count is > 1, someone may be decreasing it at
+	 * the same time we are.
+	 */
+	if (*refs != 1) {
+		struct extent_buffer *eb = NULL;
+		eb = btrfs_find_create_tree_block(root, start, len);
+		if (eb)
+			btrfs_tree_lock(eb);
+
+		mutex_lock(&root->fs_info->alloc_mutex);
+		ret = lookup_extent_ref(NULL, root, start, len, refs);
+		BUG_ON(ret);
+		mutex_unlock(&root->fs_info->alloc_mutex);
+
+		if (eb) {
+			btrfs_tree_unlock(eb);
+			free_extent_buffer(eb);
+		}
+		if (*refs == 1) {
+			printk("block %llu went down to one during drop_snap\n",
+			       (unsigned long long)start);
+		}
+
+	}
+#endif
+
+	cond_resched();
+	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)
+{
+	u64 root_owner;
+	u64 root_gen;
+	u64 bytenr;
+	u64 ptr_gen;
+	struct extent_buffer *next;
+	struct extent_buffer *cur;
+	struct extent_buffer *parent;
+	struct btrfs_leaf_ref *ref;
+	u32 blocksize;
+	int ret;
+	u32 refs;
+
+	WARN_ON(*level < 0);
+	WARN_ON(*level >= BTRFS_MAX_LEVEL);
+	ret = drop_snap_lookup_refcount(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 = btrfs_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 = drop_snap_lookup_refcount(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]++;
+
+			mutex_lock(&root->fs_info->alloc_mutex);
+			ret = __btrfs_free_extent(trans, root, bytenr,
+						blocksize, parent->start,
+						root_owner, root_gen,
+						*level - 1, 1);
+			BUG_ON(ret);
+			mutex_unlock(&root->fs_info->alloc_mutex);
+
+			atomic_inc(&root->fs_info->throttle_gen);
+			wake_up(&root->fs_info->transaction_throttle);
+			cond_resched();
+
+			continue;
+		}
+		/*
+		 * at this point, we have a single ref, and since the
+		 * only place referencing this extent is a dead root
+		 * the reference count should never go higher.
+		 * So, we don't need to check it again
+		 */
+		if (*level == 1) {
+			ref = btrfs_lookup_leaf_ref(root, bytenr);
+			if (ref && ref->generation != ptr_gen) {
+				btrfs_free_leaf_ref(root, ref);
+				ref = NULL;
+			}
+			if (ref) {
+				ret = cache_drop_leaf_ref(trans, root, ref);
+				BUG_ON(ret);
+				btrfs_remove_leaf_ref(root, ref);
+				btrfs_free_leaf_ref(root, ref);
+				*level = 0;
+				break;
+			}
+			if (printk_ratelimit()) {
+				printk("leaf ref miss for bytenr %llu\n",
+				       (unsigned long long)bytenr);
+			}
+		}
+		next = btrfs_find_tree_block(root, bytenr, blocksize);
+		if (!next || !btrfs_buffer_uptodate(next, ptr_gen)) {
+			free_extent_buffer(next);
+
+			next = read_tree_block(root, bytenr, blocksize,
+					       ptr_gen);
+			cond_resched();
+#if 0
+			/*
+			 * this is a debugging check and can go away
+			 * the ref should never go all the way down to 1
+			 * at this point
+			 */
+			ret = lookup_extent_ref(NULL, root, bytenr, blocksize,
+						&refs);
+			BUG_ON(ret);
+			WARN_ON(refs != 1);
+#endif
+		}
+		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;
+		cond_resched();
+	}
+out:
+	WARN_ON(*level < 0);
+	WARN_ON(*level >= BTRFS_MAX_LEVEL);
+
+	if (path->nodes[*level] == root->node) {
+		parent = path->nodes[*level];
+		bytenr = path->nodes[*level]->start;
+	} else {
+		parent = path->nodes[*level + 1];
+		bytenr = btrfs_node_blockptr(parent, path->slots[*level + 1]);
+	}
+
+	blocksize = btrfs_level_size(root, *level);
+	root_owner = btrfs_header_owner(parent);
+	root_gen = btrfs_header_generation(parent);
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+	ret = __btrfs_free_extent(trans, root, bytenr, blocksize,
+				  parent->start, root_owner, root_gen,
+				  *level, 1);
+	mutex_unlock(&root->fs_info->alloc_mutex);
+	free_extent_buffer(path->nodes[*level]);
+	path->nodes[*level] = NULL;
+	*level += 1;
+	BUG_ON(ret);
+
+	cond_resched();
+	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;
+}
+
+/*
+ * 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 ret = 0;
+	int wret;
+	int level;
+	struct btrfs_path *path;
+	int i;
+	int orig_level;
+	struct btrfs_root_item *root_item = &root->root_item;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->drop_mutex));
+	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)));
+		/*
+		 * unlock our path, this is safe because only this
+		 * function is allowed to delete this snapshot
+		 */
+		for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
+			if (path->nodes[i] && path->locks[i]) {
+				path->locks[i] = 0;
+				btrfs_tree_unlock(path->nodes[i]);
+			}
+		}
+	}
+	while(1) {
+		wret = walk_down_tree(trans, root, path, &level);
+		if (wret > 0)
+			break;
+		if (wret < 0)
+			ret = wret;
+
+		wret = walk_up_tree(trans, root, path, &level);
+		if (wret > 0)
+			break;
+		if (wret < 0)
+			ret = wret;
+		if (trans->transaction->in_commit) {
+			ret = -EAGAIN;
+			break;
+		}
+		atomic_inc(&root->fs_info->throttle_gen);
+		wake_up(&root->fs_info->transaction_throttle);
+	}
+	for (i = 0; i <= orig_level; i++) {
+		if (path->nodes[i]) {
+			free_extent_buffer(path->nodes[i]);
+			path->nodes[i] = NULL;
+		}
+	}
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static unsigned long calc_ra(unsigned long start, unsigned long last,
+			     unsigned long nr)
+{
+	return min(last, start + nr - 1);
+}
+
+static int noinline relocate_inode_pages(struct inode *inode, u64 start,
+					 u64 len)
+{
+	u64 page_start;
+	u64 page_end;
+	unsigned long first_index;
+	unsigned long last_index;
+	unsigned long i;
+	struct page *page;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+	struct file_ra_state *ra;
+	struct btrfs_ordered_extent *ordered;
+	unsigned int total_read = 0;
+	unsigned int total_dirty = 0;
+	int ret = 0;
+
+	ra = kzalloc(sizeof(*ra), GFP_NOFS);
+
+	mutex_lock(&inode->i_mutex);
+	first_index = start >> PAGE_CACHE_SHIFT;
+	last_index = (start + len - 1) >> PAGE_CACHE_SHIFT;
+
+	/* make sure the dirty trick played by the caller work */
+	ret = invalidate_inode_pages2_range(inode->i_mapping,
+					    first_index, last_index);
+	if (ret)
+		goto out_unlock;
+
+	file_ra_state_init(ra, inode->i_mapping);
+
+	for (i = first_index ; i <= last_index; i++) {
+		if (total_read % ra->ra_pages == 0) {
+			btrfs_force_ra(inode->i_mapping, ra, NULL, i,
+				       calc_ra(i, last_index, ra->ra_pages));
+		}
+		total_read++;
+again:
+		if (((u64)i << PAGE_CACHE_SHIFT) > i_size_read(inode))
+			BUG_ON(1);
+		page = grab_cache_page(inode->i_mapping, i);
+		if (!page) {
+			ret = -ENOMEM;
+			goto out_unlock;
+		}
+		if (!PageUptodate(page)) {
+			btrfs_readpage(NULL, page);
+			lock_page(page);
+			if (!PageUptodate(page)) {
+				unlock_page(page);
+				page_cache_release(page);
+				ret = -EIO;
+				goto out_unlock;
+			}
+		}
+		wait_on_page_writeback(page);
+
+		page_start = (u64)page->index << PAGE_CACHE_SHIFT;
+		page_end = page_start + PAGE_CACHE_SIZE - 1;
+		lock_extent(io_tree, page_start, page_end, GFP_NOFS);
+
+		ordered = btrfs_lookup_ordered_extent(inode, page_start);
+		if (ordered) {
+			unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
+			unlock_page(page);
+			page_cache_release(page);
+			btrfs_start_ordered_extent(inode, ordered, 1);
+			btrfs_put_ordered_extent(ordered);
+			goto again;
+		}
+		set_page_extent_mapped(page);
+
+		btrfs_set_extent_delalloc(inode, page_start, page_end);
+		if (i == first_index)
+			set_extent_bits(io_tree, page_start, page_end,
+					EXTENT_BOUNDARY, GFP_NOFS);
+
+		set_page_dirty(page);
+		total_dirty++;
+
+		unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
+		unlock_page(page);
+		page_cache_release(page);
+	}
+
+out_unlock:
+	kfree(ra);
+	mutex_unlock(&inode->i_mutex);
+	balance_dirty_pages_ratelimited_nr(inode->i_mapping, total_dirty);
+	return ret;
+}
+
+static int noinline relocate_data_extent(struct inode *reloc_inode,
+					 struct btrfs_key *extent_key,
+					 u64 offset)
+{
+	struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
+	struct extent_map_tree *em_tree = &BTRFS_I(reloc_inode)->extent_tree;
+	struct extent_map *em;
+
+	em = alloc_extent_map(GFP_NOFS);
+	BUG_ON(!em || IS_ERR(em));
+
+	em->start = extent_key->objectid - offset;
+	em->len = extent_key->offset;
+	em->block_start = extent_key->objectid;
+	em->bdev = root->fs_info->fs_devices->latest_bdev;
+	set_bit(EXTENT_FLAG_PINNED, &em->flags);
+
+	/* setup extent map to cheat btrfs_readpage */
+	mutex_lock(&BTRFS_I(reloc_inode)->extent_mutex);
+	while (1) {
+		int ret;
+		spin_lock(&em_tree->lock);
+		ret = add_extent_mapping(em_tree, em);
+		spin_unlock(&em_tree->lock);
+		if (ret != -EEXIST) {
+			free_extent_map(em);
+			break;
+		}
+		btrfs_drop_extent_cache(reloc_inode, em->start,
+					em->start + em->len - 1, 0);
+	}
+	mutex_unlock(&BTRFS_I(reloc_inode)->extent_mutex);
+
+	return relocate_inode_pages(reloc_inode, extent_key->objectid - offset,
+				    extent_key->offset);
+}
+
+struct btrfs_ref_path {
+	u64 extent_start;
+	u64 nodes[BTRFS_MAX_LEVEL];
+	u64 root_objectid;
+	u64 root_generation;
+	u64 owner_objectid;
+	u32 num_refs;
+	int lowest_level;
+	int current_level;
+};
+
+struct disk_extent {
+	u64 disk_bytenr;
+	u64 disk_num_bytes;
+	u64 offset;
+	u64 num_bytes;
+};
+
+static int is_cowonly_root(u64 root_objectid)
+{
+	if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
+	    root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
+	    root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
+	    root_objectid == BTRFS_DEV_TREE_OBJECTID ||
+	    root_objectid == BTRFS_TREE_LOG_OBJECTID)
+		return 1;
+	return 0;
+}
+
+static int noinline __next_ref_path(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *extent_root,
+				    struct btrfs_ref_path *ref_path,
+				    int first_time)
+{
+	struct extent_buffer *leaf;
+	struct btrfs_path *path;
+	struct btrfs_extent_ref *ref;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	u64 bytenr;
+	u32 nritems;
+	int level;
+	int ret = 1;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	mutex_lock(&extent_root->fs_info->alloc_mutex);
+
+	if (first_time) {
+		ref_path->lowest_level = -1;
+		ref_path->current_level = -1;
+		goto walk_up;
+	}
+walk_down:
+	level = ref_path->current_level - 1;
+	while (level >= -1) {
+		u64 parent;
+		if (level < ref_path->lowest_level)
+			break;
+
+		if (level >= 0) {
+			bytenr = ref_path->nodes[level];
+		} else {
+			bytenr = ref_path->extent_start;
+		}
+		BUG_ON(bytenr == 0);
+
+		parent = ref_path->nodes[level + 1];
+		ref_path->nodes[level + 1] = 0;
+		ref_path->current_level = level;
+		BUG_ON(parent == 0);
+
+		key.objectid = bytenr;
+		key.offset = parent + 1;
+		key.type = BTRFS_EXTENT_REF_KEY;
+
+		ret = btrfs_search_slot(trans, extent_root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+		BUG_ON(ret == 0);
+
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(extent_root, path);
+			if (ret < 0)
+				goto out;
+			if (ret > 0)
+				goto next;
+			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 found;
+next:
+		level--;
+		btrfs_release_path(extent_root, path);
+		if (need_resched()) {
+			mutex_unlock(&extent_root->fs_info->alloc_mutex);
+			cond_resched();
+			mutex_lock(&extent_root->fs_info->alloc_mutex);
+		}
+	}
+	/* reached lowest level */
+	ret = 1;
+	goto out;
+walk_up:
+	level = ref_path->current_level;
+	while (level < BTRFS_MAX_LEVEL - 1) {
+		u64 ref_objectid;
+		if (level >= 0) {
+			bytenr = ref_path->nodes[level];
+		} else {
+			bytenr = ref_path->extent_start;
+		}
+		BUG_ON(bytenr == 0);
+
+		key.objectid = bytenr;
+		key.offset = 0;
+		key.type = BTRFS_EXTENT_REF_KEY;
+
+		ret = btrfs_search_slot(trans, extent_root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(extent_root, path);
+			if (ret < 0)
+				goto out;
+			if (ret > 0) {
+				/* the extent was freed by someone */
+				if (ref_path->lowest_level == level)
+					goto out;
+				btrfs_release_path(extent_root, path);
+				goto walk_down;
+			}
+			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) {
+			/* the extent was freed by someone */
+			if (ref_path->lowest_level == level) {
+				ret = 1;
+				goto out;
+			}
+			btrfs_release_path(extent_root, path);
+			goto walk_down;
+		}
+found:
+		ref = btrfs_item_ptr(leaf, path->slots[0],
+				struct btrfs_extent_ref);
+		ref_objectid = btrfs_ref_objectid(leaf, ref);
+		if (ref_objectid < BTRFS_FIRST_FREE_OBJECTID) {
+			if (first_time) {
+				level = (int)ref_objectid;
+				BUG_ON(level >= BTRFS_MAX_LEVEL);
+				ref_path->lowest_level = level;
+				ref_path->current_level = level;
+				ref_path->nodes[level] = bytenr;
+			} else {
+				WARN_ON(ref_objectid != level);
+			}
+		} else {
+			WARN_ON(level != -1);
+		}
+		first_time = 0;
+
+		if (ref_path->lowest_level == level) {
+			ref_path->owner_objectid = ref_objectid;
+			ref_path->num_refs = btrfs_ref_num_refs(leaf, ref);
+		}
+
+		/*
+		 * the block is tree root or the block isn't in reference
+		 * counted tree.
+		 */
+		if (found_key.objectid == found_key.offset ||
+		    is_cowonly_root(btrfs_ref_root(leaf, ref))) {
+			ref_path->root_objectid = btrfs_ref_root(leaf, ref);
+			ref_path->root_generation =
+				btrfs_ref_generation(leaf, ref);
+			if (level < 0) {
+				/* special reference from the tree log */
+				ref_path->nodes[0] = found_key.offset;
+				ref_path->current_level = 0;
+			}
+			ret = 0;
+			goto out;
+		}
+
+		level++;
+		BUG_ON(ref_path->nodes[level] != 0);
+		ref_path->nodes[level] = found_key.offset;
+		ref_path->current_level = level;
+
+		/*
+		 * the reference was created in the running transaction,
+		 * no need to continue walking up.
+		 */
+		if (btrfs_ref_generation(leaf, ref) == trans->transid) {
+			ref_path->root_objectid = btrfs_ref_root(leaf, ref);
+			ref_path->root_generation =
+				btrfs_ref_generation(leaf, ref);
+			ret = 0;
+			goto out;
+		}
+
+		btrfs_release_path(extent_root, path);
+		if (need_resched()) {
+			mutex_unlock(&extent_root->fs_info->alloc_mutex);
+			cond_resched();
+			mutex_lock(&extent_root->fs_info->alloc_mutex);
+		}
+	}
+	/* reached max tree level, but no tree root found. */
+	BUG();
+out:
+	mutex_unlock(&extent_root->fs_info->alloc_mutex);
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int btrfs_first_ref_path(struct btrfs_trans_handle *trans,
+				struct btrfs_root *extent_root,
+				struct btrfs_ref_path *ref_path,
+				u64 extent_start)
+{
+	memset(ref_path, 0, sizeof(*ref_path));
+	ref_path->extent_start = extent_start;
+
+	return __next_ref_path(trans, extent_root, ref_path, 1);
+}
+
+static int btrfs_next_ref_path(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *extent_root,
+			       struct btrfs_ref_path *ref_path)
+{
+	return __next_ref_path(trans, extent_root, ref_path, 0);
+}
+
+static int noinline get_new_locations(struct inode *reloc_inode,
+				      struct btrfs_key *extent_key,
+				      u64 offset, int no_fragment,
+				      struct disk_extent **extents,
+				      int *nr_extents)
+{
+	struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
+	struct btrfs_path *path;
+	struct btrfs_file_extent_item *fi;
+	struct extent_buffer *leaf;
+	struct disk_extent *exts = *extents;
+	struct btrfs_key found_key;
+	u64 cur_pos;
+	u64 last_byte;
+	u32 nritems;
+	int nr = 0;
+	int max = *nr_extents;
+	int ret;
+
+	WARN_ON(!no_fragment && *extents);
+	if (!exts) {
+		max = 1;
+		exts = kmalloc(sizeof(*exts) * max, GFP_NOFS);
+		if (!exts)
+			return -ENOMEM;
+	}
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+
+	cur_pos = extent_key->objectid - offset;
+	last_byte = extent_key->objectid + extent_key->offset;
+	ret = btrfs_lookup_file_extent(NULL, root, path, reloc_inode->i_ino,
+				       cur_pos, 0);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	while (1) {
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+		}
+
+		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+		if (found_key.offset != cur_pos ||
+		    found_key.type != BTRFS_EXTENT_DATA_KEY ||
+		    found_key.objectid != reloc_inode->i_ino)
+			break;
+
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		if (btrfs_file_extent_type(leaf, fi) !=
+		    BTRFS_FILE_EXTENT_REG ||
+		    btrfs_file_extent_disk_bytenr(leaf, fi) == 0)
+			break;
+
+		if (nr == max) {
+			struct disk_extent *old = exts;
+			max *= 2;
+			exts = kzalloc(sizeof(*exts) * max, GFP_NOFS);
+			memcpy(exts, old, sizeof(*exts) * nr);
+			if (old != *extents)
+				kfree(old);
+		}
+
+		exts[nr].disk_bytenr =
+			btrfs_file_extent_disk_bytenr(leaf, fi);
+		exts[nr].disk_num_bytes =
+			btrfs_file_extent_disk_num_bytes(leaf, fi);
+		exts[nr].offset = btrfs_file_extent_offset(leaf, fi);
+		exts[nr].num_bytes = btrfs_file_extent_num_bytes(leaf, fi);
+		WARN_ON(exts[nr].offset > 0);
+		WARN_ON(exts[nr].num_bytes != exts[nr].disk_num_bytes);
+
+		cur_pos += exts[nr].num_bytes;
+		nr++;
+
+		if (cur_pos + offset >= last_byte)
+			break;
+
+		if (no_fragment) {
+			ret = 1;
+			goto out;
+		}
+		path->slots[0]++;
+	}
+
+	WARN_ON(cur_pos + offset > last_byte);
+	if (cur_pos + offset < last_byte) {
+		ret = -ENOENT;
+		goto out;
+	}
+	ret = 0;
+out:
+	btrfs_free_path(path);
+	if (ret) {
+		if (exts != *extents)
+			kfree(exts);
+	} else {
+		*extents = exts;
+		*nr_extents = nr;
+	}
+	return ret;
+}
+
+static int noinline replace_one_extent(struct btrfs_trans_handle *trans,
+					struct btrfs_root *root,
+					struct btrfs_path *path,
+					struct btrfs_key *extent_key,
+					struct btrfs_key *leaf_key,
+					struct btrfs_ref_path *ref_path,
+					struct disk_extent *new_extents,
+					int nr_extents)
+{
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *fi;
+	struct inode *inode = NULL;
+	struct btrfs_key key;
+	u64 lock_start = 0;
+	u64 lock_end = 0;
+	u64 num_bytes;
+	u64 ext_offset;
+	u64 first_pos;
+	u32 nritems;
+	int nr_scaned = 0;
+	int extent_locked = 0;
+	int ret;
+
+	memcpy(&key, leaf_key, sizeof(key));
+	first_pos = INT_LIMIT(loff_t) - extent_key->offset;
+	if (ref_path->owner_objectid != BTRFS_MULTIPLE_OBJECTIDS) {
+		if (key.objectid < ref_path->owner_objectid ||
+		    (key.objectid == ref_path->owner_objectid &&
+		     key.type < BTRFS_EXTENT_DATA_KEY)) {
+			key.objectid = ref_path->owner_objectid;
+			key.type = BTRFS_EXTENT_DATA_KEY;
+			key.offset = 0;
+		}
+	}
+
+	while (1) {
+		ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+		if (ret < 0)
+			goto out;
+
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+next:
+		if (extent_locked && ret > 0) {
+			/*
+			 * the file extent item was modified by someone
+			 * before the extent got locked.
+			 */
+			mutex_unlock(&BTRFS_I(inode)->extent_mutex);
+			unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
+				      lock_end, GFP_NOFS);
+			extent_locked = 0;
+		}
+
+		if (path->slots[0] >= nritems) {
+			if (++nr_scaned > 2)
+				break;
+
+			BUG_ON(extent_locked);
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			if (ret > 0)
+				break;
+			leaf = path->nodes[0];
+			nritems = btrfs_header_nritems(leaf);
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+		if (ref_path->owner_objectid != BTRFS_MULTIPLE_OBJECTIDS) {
+			if ((key.objectid > ref_path->owner_objectid) ||
+			    (key.objectid == ref_path->owner_objectid &&
+			     key.type > BTRFS_EXTENT_DATA_KEY) ||
+			    (key.offset >= first_pos + extent_key->offset))
+				break;
+		}
+
+		if (inode && key.objectid != inode->i_ino) {
+			BUG_ON(extent_locked);
+			btrfs_release_path(root, path);
+			mutex_unlock(&inode->i_mutex);
+			iput(inode);
+			inode = NULL;
+			continue;
+		}
+
+		if (key.type != BTRFS_EXTENT_DATA_KEY) {
+			path->slots[0]++;
+			ret = 1;
+			goto next;
+		}
+		fi = btrfs_item_ptr(leaf, path->slots[0],
+				    struct btrfs_file_extent_item);
+		if ((btrfs_file_extent_type(leaf, fi) !=
+		     BTRFS_FILE_EXTENT_REG) ||
+		    (btrfs_file_extent_disk_bytenr(leaf, fi) !=
+		     extent_key->objectid)) {
+			path->slots[0]++;
+			ret = 1;
+			goto next;
+		}
+
+		num_bytes = btrfs_file_extent_num_bytes(leaf, fi);
+		ext_offset = btrfs_file_extent_offset(leaf, fi);
+
+		if (first_pos > key.offset - ext_offset)
+			first_pos = key.offset - ext_offset;
+
+		if (!extent_locked) {
+			lock_start = key.offset;
+			lock_end = lock_start + num_bytes - 1;
+		} else {
+			BUG_ON(lock_start != key.offset);
+			BUG_ON(lock_end - lock_start + 1 < num_bytes);
+		}
+
+		if (!inode) {
+			btrfs_release_path(root, path);
+
+			inode = btrfs_iget_locked(root->fs_info->sb,
+						  key.objectid, root);
+			if (inode->i_state & I_NEW) {
+				BTRFS_I(inode)->root = root;
+				BTRFS_I(inode)->location.objectid =
+					key.objectid;
+				BTRFS_I(inode)->location.type =
+					BTRFS_INODE_ITEM_KEY;
+				BTRFS_I(inode)->location.offset = 0;
+				btrfs_read_locked_inode(inode);
+				unlock_new_inode(inode);
+			}
+			/*
+			 * some code call btrfs_commit_transaction while
+			 * holding the i_mutex, so we can't use mutex_lock
+			 * here.
+			 */
+			if (is_bad_inode(inode) ||
+			    !mutex_trylock(&inode->i_mutex)) {
+				iput(inode);
+				inode = NULL;
+				key.offset = (u64)-1;
+				goto skip;
+			}
+		}
+
+		if (!extent_locked) {
+			struct btrfs_ordered_extent *ordered;
+
+			btrfs_release_path(root, path);
+
+			lock_extent(&BTRFS_I(inode)->io_tree, lock_start,
+				    lock_end, GFP_NOFS);
+			ordered = btrfs_lookup_first_ordered_extent(inode,
+								    lock_end);
+			if (ordered &&
+			    ordered->file_offset <= lock_end &&
+			    ordered->file_offset + ordered->len > lock_start) {
+				unlock_extent(&BTRFS_I(inode)->io_tree,
+					      lock_start, lock_end, GFP_NOFS);
+				btrfs_start_ordered_extent(inode, ordered, 1);
+				btrfs_put_ordered_extent(ordered);
+				key.offset += num_bytes;
+				goto skip;
+			}
+			if (ordered)
+				btrfs_put_ordered_extent(ordered);
+
+			mutex_lock(&BTRFS_I(inode)->extent_mutex);
+			extent_locked = 1;
+			continue;
+		}
+
+		if (nr_extents == 1) {
+			/* update extent pointer in place */
+			btrfs_set_file_extent_generation(leaf, fi,
+						trans->transid);
+			btrfs_set_file_extent_disk_bytenr(leaf, fi,
+						new_extents[0].disk_bytenr);
+			btrfs_set_file_extent_disk_num_bytes(leaf, fi,
+						new_extents[0].disk_num_bytes);
+			ext_offset += new_extents[0].offset;
+			btrfs_set_file_extent_offset(leaf, fi, ext_offset);
+			btrfs_mark_buffer_dirty(leaf);
+
+			btrfs_drop_extent_cache(inode, key.offset,
+						key.offset + num_bytes - 1, 0);
+
+			ret = btrfs_inc_extent_ref(trans, root,
+						new_extents[0].disk_bytenr,
+						new_extents[0].disk_num_bytes,
+						leaf->start,
+						root->root_key.objectid,
+						trans->transid,
+						key.objectid);
+			BUG_ON(ret);
+
+			ret = btrfs_free_extent(trans, root,
+						extent_key->objectid,
+						extent_key->offset,
+						leaf->start,
+						btrfs_header_owner(leaf),
+						btrfs_header_generation(leaf),
+						key.objectid, 0);
+			BUG_ON(ret);
+
+			btrfs_release_path(root, path);
+			key.offset += num_bytes;
+		} else {
+			u64 alloc_hint;
+			u64 extent_len;
+			int i;
+			/*
+			 * drop old extent pointer at first, then insert the
+			 * new pointers one bye one
+			 */
+			btrfs_release_path(root, path);
+			ret = btrfs_drop_extents(trans, root, inode, key.offset,
+						 key.offset + num_bytes,
+						 key.offset, &alloc_hint);
+			BUG_ON(ret);
+
+			for (i = 0; i < nr_extents; i++) {
+				if (ext_offset >= new_extents[i].num_bytes) {
+					ext_offset -= new_extents[i].num_bytes;
+					continue;
+				}
+				extent_len = min(new_extents[i].num_bytes -
+						 ext_offset, num_bytes);
+
+				ret = btrfs_insert_empty_item(trans, root,
+							      path, &key,
+							      sizeof(*fi));
+				BUG_ON(ret);
+
+				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,
+						new_extents[i].disk_bytenr);
+				btrfs_set_file_extent_disk_num_bytes(leaf, fi,
+						new_extents[i].disk_num_bytes);
+				btrfs_set_file_extent_num_bytes(leaf, fi,
+							extent_len);
+				ext_offset += new_extents[i].offset;
+				btrfs_set_file_extent_offset(leaf, fi,
+							ext_offset);
+				btrfs_mark_buffer_dirty(leaf);
+
+				btrfs_drop_extent_cache(inode, key.offset,
+						key.offset + extent_len - 1, 0);
+
+				ret = btrfs_inc_extent_ref(trans, root,
+						new_extents[i].disk_bytenr,
+						new_extents[i].disk_num_bytes,
+						leaf->start,
+						root->root_key.objectid,
+						trans->transid, key.objectid);
+				BUG_ON(ret);
+				btrfs_release_path(root, path);
+
+				inode_add_bytes(inode, extent_len);
+
+				ext_offset = 0;
+				num_bytes -= extent_len;
+				key.offset += extent_len;
+
+				if (num_bytes == 0)
+					break;
+			}
+			BUG_ON(i >= nr_extents);
+		}
+
+		if (extent_locked) {
+			mutex_unlock(&BTRFS_I(inode)->extent_mutex);
+			unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
+				      lock_end, GFP_NOFS);
+			extent_locked = 0;
+		}
+skip:
+		if (ref_path->owner_objectid != BTRFS_MULTIPLE_OBJECTIDS &&
+		    key.offset >= first_pos + extent_key->offset)
+			break;
+
+		cond_resched();
+	}
+	ret = 0;
+out:
+	btrfs_release_path(root, path);
+	if (inode) {
+		mutex_unlock(&inode->i_mutex);
+		if (extent_locked) {
+			mutex_unlock(&BTRFS_I(inode)->extent_mutex);
+			unlock_extent(&BTRFS_I(inode)->io_tree, lock_start,
+				      lock_end, GFP_NOFS);
+		}
+		iput(inode);
+	}
+	return ret;
+}
+
+int btrfs_add_reloc_mapping(struct btrfs_root *root, u64 orig_bytenr,
+			    u64 num_bytes, u64 new_bytenr)
+{
+	set_extent_bits(&root->fs_info->reloc_mapping_tree,
+			orig_bytenr, orig_bytenr + num_bytes - 1,
+			EXTENT_LOCKED, GFP_NOFS);
+	set_state_private(&root->fs_info->reloc_mapping_tree,
+			  orig_bytenr, new_bytenr);
+	return 0;
+}
+
+int btrfs_get_reloc_mapping(struct btrfs_root *root, u64 orig_bytenr,
+			    u64 num_bytes, u64 *new_bytenr)
+{
+	u64 bytenr;
+	u64 cur_bytenr = orig_bytenr;
+	u64 prev_bytenr = orig_bytenr;
+	int ret;
+
+	while (1) {
+		ret = get_state_private(&root->fs_info->reloc_mapping_tree,
+					cur_bytenr, &bytenr);
+		if (ret)
+			break;
+		prev_bytenr = cur_bytenr;
+		cur_bytenr = bytenr;
+	}
+
+	if (orig_bytenr == cur_bytenr)
+		return -ENOENT;
+
+	if (prev_bytenr != orig_bytenr) {
+		set_state_private(&root->fs_info->reloc_mapping_tree,
+				  orig_bytenr, cur_bytenr);
+	}
+	*new_bytenr = cur_bytenr;
+	return 0;
+}
+
+void btrfs_free_reloc_mappings(struct btrfs_root *root)
+{
+	clear_extent_bits(&root->fs_info->reloc_mapping_tree,
+			  0, (u64)-1, -1, GFP_NOFS);
+}
+
+int btrfs_reloc_tree_cache_ref(struct btrfs_trans_handle *trans,
+			       struct btrfs_root *root,
+			       struct extent_buffer *buf, u64 orig_start)
+{
+	int level;
+	int ret;
+
+	BUG_ON(btrfs_header_generation(buf) != trans->transid);
+	BUG_ON(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
+
+	level = btrfs_header_level(buf);
+	if (level == 0) {
+		struct btrfs_leaf_ref *ref;
+		struct btrfs_leaf_ref *orig_ref;
+
+		orig_ref = btrfs_lookup_leaf_ref(root, orig_start);
+		if (!orig_ref)
+			return -ENOENT;
+
+		ref = btrfs_alloc_leaf_ref(root, orig_ref->nritems);
+		if (!ref) {
+			btrfs_free_leaf_ref(root, orig_ref);
+			return -ENOMEM;
+		}
+
+		ref->nritems = orig_ref->nritems;
+		memcpy(ref->extents, orig_ref->extents,
+			sizeof(ref->extents[0]) * ref->nritems);
+
+		btrfs_free_leaf_ref(root, orig_ref);
+
+		ref->root_gen = trans->transid;
+		ref->bytenr = buf->start;
+		ref->owner = btrfs_header_owner(buf);
+		ref->generation = btrfs_header_generation(buf);
+		ret = btrfs_add_leaf_ref(root, ref, 0);
+		WARN_ON(ret);
+		btrfs_free_leaf_ref(root, ref);
+	}
+	return 0;
+}
+
+static int noinline invalidate_extent_cache(struct btrfs_root *root,
+					struct extent_buffer *leaf,
+					struct btrfs_block_group_cache *group,
+					struct btrfs_root *target_root)
+{
+	struct btrfs_key key;
+	struct inode *inode = NULL;
+	struct btrfs_file_extent_item *fi;
+	u64 num_bytes;
+	u64 skip_objectid = 0;
+	u32 nritems;
+	u32 i;
+
+	nritems = btrfs_header_nritems(leaf);
+	for (i = 0; i < nritems; i++) {
+		btrfs_item_key_to_cpu(leaf, &key, i);
+		if (key.objectid == skip_objectid ||
+		    key.type != 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)
+			continue;
+		if (btrfs_file_extent_disk_bytenr(leaf, fi) == 0)
+			continue;
+		if (!inode || inode->i_ino != key.objectid) {
+			iput(inode);
+			inode = btrfs_ilookup(target_root->fs_info->sb,
+					      key.objectid, target_root, 1);
+		}
+		if (!inode) {
+			skip_objectid = key.objectid;
+			continue;
+		}
+		num_bytes = btrfs_file_extent_num_bytes(leaf, fi);
+
+		lock_extent(&BTRFS_I(inode)->io_tree, key.offset,
+			    key.offset + num_bytes - 1, GFP_NOFS);
+		mutex_lock(&BTRFS_I(inode)->extent_mutex);
+		btrfs_drop_extent_cache(inode, key.offset,
+					key.offset + num_bytes - 1, 1);
+		mutex_unlock(&BTRFS_I(inode)->extent_mutex);
+		unlock_extent(&BTRFS_I(inode)->io_tree, key.offset,
+			      key.offset + num_bytes - 1, GFP_NOFS);
+		cond_resched();
+	}
+	iput(inode);
+	return 0;
+}
+
+static int noinline replace_extents_in_leaf(struct btrfs_trans_handle *trans,
+					struct btrfs_root *root,
+					struct extent_buffer *leaf,
+					struct btrfs_block_group_cache *group,
+					struct inode *reloc_inode)
+{
+	struct btrfs_key key;
+	struct btrfs_key extent_key;
+	struct btrfs_file_extent_item *fi;
+	struct btrfs_leaf_ref *ref;
+	struct disk_extent *new_extent;
+	u64 bytenr;
+	u64 num_bytes;
+	u32 nritems;
+	u32 i;
+	int ext_index;
+	int nr_extent;
+	int ret;
+
+	new_extent = kmalloc(sizeof(*new_extent), GFP_NOFS);
+	BUG_ON(!new_extent);
+
+	ref = btrfs_lookup_leaf_ref(root, leaf->start);
+	BUG_ON(!ref);
+
+	ext_index = -1;
+	nritems = btrfs_header_nritems(leaf);
+	for (i = 0; i < nritems; i++) {
+		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)
+			continue;
+		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+		num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
+		if (bytenr == 0)
+			continue;
+
+		ext_index++;
+		if (bytenr >= group->key.objectid + group->key.offset ||
+		    bytenr + num_bytes <= group->key.objectid)
+			continue;
+
+		extent_key.objectid = bytenr;
+		extent_key.offset = num_bytes;
+		extent_key.type = BTRFS_EXTENT_ITEM_KEY;
+		nr_extent = 1;
+		ret = get_new_locations(reloc_inode, &extent_key,
+					group->key.objectid, 1,
+					&new_extent, &nr_extent);
+		if (ret > 0)
+			continue;
+		BUG_ON(ret < 0);
+
+		BUG_ON(ref->extents[ext_index].bytenr != bytenr);
+		BUG_ON(ref->extents[ext_index].num_bytes != num_bytes);
+		ref->extents[ext_index].bytenr = new_extent->disk_bytenr;
+		ref->extents[ext_index].num_bytes = new_extent->disk_num_bytes;
+
+		btrfs_set_file_extent_generation(leaf, fi, trans->transid);
+		btrfs_set_file_extent_disk_bytenr(leaf, fi,
+						new_extent->disk_bytenr);
+		btrfs_set_file_extent_disk_num_bytes(leaf, fi,
+						new_extent->disk_num_bytes);
+		new_extent->offset += btrfs_file_extent_offset(leaf, fi);
+		btrfs_set_file_extent_offset(leaf, fi, new_extent->offset);
+		btrfs_mark_buffer_dirty(leaf);
+
+		ret = btrfs_inc_extent_ref(trans, root,
+					new_extent->disk_bytenr,
+					new_extent->disk_num_bytes,
+					leaf->start,
+					root->root_key.objectid,
+					trans->transid, key.objectid);
+		BUG_ON(ret);
+		ret = btrfs_free_extent(trans, root,
+					bytenr, num_bytes, leaf->start,
+					btrfs_header_owner(leaf),
+					btrfs_header_generation(leaf),
+					key.objectid, 0);
+		BUG_ON(ret);
+		cond_resched();
+	}
+	kfree(new_extent);
+	BUG_ON(ext_index + 1 != ref->nritems);
+	btrfs_free_leaf_ref(root, ref);
+	return 0;
+}
+
+int btrfs_free_reloc_root(struct btrfs_root *root)
+{
+	struct btrfs_root *reloc_root;
+
+	if (root->reloc_root) {
+		reloc_root = root->reloc_root;
+		root->reloc_root = NULL;
+		list_add(&reloc_root->dead_list,
+			 &root->fs_info->dead_reloc_roots);
+	}
+	return 0;
+}
+
+int btrfs_drop_dead_reloc_roots(struct btrfs_root *root)
+{
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *reloc_root;
+	struct btrfs_root *prev_root = NULL;
+	struct list_head dead_roots;
+	int ret;
+	unsigned long nr;
+
+	INIT_LIST_HEAD(&dead_roots);
+	list_splice_init(&root->fs_info->dead_reloc_roots, &dead_roots);
+
+	while (!list_empty(&dead_roots)) {
+		reloc_root = list_entry(dead_roots.prev,
+					struct btrfs_root, dead_list);
+		list_del_init(&reloc_root->dead_list);
+
+		BUG_ON(reloc_root->commit_root != NULL);
+		while (1) {
+			trans = btrfs_join_transaction(root, 1);
+			BUG_ON(!trans);
+
+			mutex_lock(&root->fs_info->drop_mutex);
+			ret = btrfs_drop_snapshot(trans, reloc_root);
+			if (ret != -EAGAIN)
+				break;
+			mutex_unlock(&root->fs_info->drop_mutex);
+
+			nr = trans->blocks_used;
+			ret = btrfs_end_transaction(trans, root);
+			BUG_ON(ret);
+			btrfs_btree_balance_dirty(root, nr);
+		}
+
+		free_extent_buffer(reloc_root->node);
+
+		ret = btrfs_del_root(trans, root->fs_info->tree_root,
+				     &reloc_root->root_key);
+		BUG_ON(ret);
+		mutex_unlock(&root->fs_info->drop_mutex);
+
+		nr = trans->blocks_used;
+		ret = btrfs_end_transaction(trans, root);
+		BUG_ON(ret);
+		btrfs_btree_balance_dirty(root, nr);
+
+		kfree(prev_root);
+		prev_root = reloc_root;
+	}
+	if (prev_root) {
+		btrfs_remove_leaf_refs(prev_root, (u64)-1, 0);
+		kfree(prev_root);
+	}
+	return 0;
+}
+
+int btrfs_add_dead_reloc_root(struct btrfs_root *root)
+{
+	list_add(&root->dead_list, &root->fs_info->dead_reloc_roots);
+	return 0;
+}
+
+int btrfs_cleanup_reloc_trees(struct btrfs_root *root)
+{
+	struct btrfs_root *reloc_root;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_key location;
+	int found;
+	int ret;
+
+	mutex_lock(&root->fs_info->tree_reloc_mutex);
+	ret = btrfs_find_dead_roots(root, BTRFS_TREE_RELOC_OBJECTID, NULL);
+	BUG_ON(ret);
+	found = !list_empty(&root->fs_info->dead_reloc_roots);
+	mutex_unlock(&root->fs_info->tree_reloc_mutex);
+
+	if (found) {
+		trans = btrfs_start_transaction(root, 1);
+		BUG_ON(!trans);
+		ret = btrfs_commit_transaction(trans, root);
+		BUG_ON(ret);
+	}
+
+	location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
+	location.offset = (u64)-1;
+	location.type = BTRFS_ROOT_ITEM_KEY;
+
+	reloc_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
+	BUG_ON(!reloc_root);
+	btrfs_orphan_cleanup(reloc_root);
+	return 0;
+}
+
+static int noinline init_reloc_tree(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *root)
+{
+	struct btrfs_root *reloc_root;
+	struct extent_buffer *eb;
+	struct btrfs_root_item *root_item;
+	struct btrfs_key root_key;
+	int ret;
+
+	BUG_ON(!root->ref_cows);
+	if (root->reloc_root)
+		return 0;
+
+	root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
+	BUG_ON(!root_item);
+
+	ret = btrfs_copy_root(trans, root, root->commit_root,
+			      &eb, BTRFS_TREE_RELOC_OBJECTID);
+	BUG_ON(ret);
+
+	root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
+	root_key.offset = root->root_key.objectid;
+	root_key.type = BTRFS_ROOT_ITEM_KEY;
+
+	memcpy(root_item, &root->root_item, sizeof(root_item));
+	btrfs_set_root_refs(root_item, 0);
+	btrfs_set_root_bytenr(root_item, eb->start);
+	btrfs_set_root_level(root_item, btrfs_header_level(eb));
+	memset(&root_item->drop_progress, 0, sizeof(root_item->drop_progress));
+	root_item->drop_level = 0;
+
+	btrfs_tree_unlock(eb);
+	free_extent_buffer(eb);
+
+	ret = btrfs_insert_root(trans, root->fs_info->tree_root,
+				&root_key, root_item);
+	BUG_ON(ret);
+	kfree(root_item);
+
+	reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
+						 &root_key);
+	BUG_ON(!reloc_root);
+	reloc_root->last_trans = trans->transid;
+	reloc_root->commit_root = NULL;
+	reloc_root->ref_tree = &root->fs_info->reloc_ref_tree;
+
+	root->reloc_root = reloc_root;
+	return 0;
+}
+
+/*
+ * Core function of space balance.
+ *
+ * The idea is using reloc trees to relocate tree blocks in reference
+ * counted roots. There is one reloc tree for each subvol, all reloc
+ * trees share same key objectid. Reloc trees are snapshots of the
+ * latest committed roots (subvol root->commit_root). To relocate a tree
+ * block referenced by a subvol, the code COW the block through the reloc
+ * tree, then update pointer in the subvol to point to the new block.
+ * Since all reloc trees share same key objectid, we can easily do special
+ * handing to share tree blocks between reloc trees. Once a tree block has
+ * been COWed in one reloc tree, we can use the result when the same block
+ * is COWed again through other reloc trees.
+ */
+static int noinline relocate_one_path(struct btrfs_trans_handle *trans,
+				      struct btrfs_root *root,
+				      struct btrfs_path *path,
+				      struct btrfs_key *first_key,
+				      struct btrfs_ref_path *ref_path,
+				      struct btrfs_block_group_cache *group,
+				      struct inode *reloc_inode)
+{
+	struct btrfs_root *reloc_root;
+	struct extent_buffer *eb = NULL;
+	struct btrfs_key *keys;
+	u64 *nodes;
+	int level;
+	int lowest_merge;
+	int lowest_level = 0;
+	int update_refs;
+	int ret;
+
+	if (ref_path->owner_objectid < BTRFS_FIRST_FREE_OBJECTID)
+		lowest_level = ref_path->owner_objectid;
+
+	if (is_cowonly_root(ref_path->root_objectid)) {
+		path->lowest_level = lowest_level;
+		ret = btrfs_search_slot(trans, root, first_key, path, 0, 1);
+		BUG_ON(ret < 0);
+		path->lowest_level = 0;
+		btrfs_release_path(root, path);
+		return 0;
+	}
+
+	keys = kzalloc(sizeof(*keys) * BTRFS_MAX_LEVEL, GFP_NOFS);
+	BUG_ON(!keys);
+	nodes = kzalloc(sizeof(*nodes) * BTRFS_MAX_LEVEL, GFP_NOFS);
+	BUG_ON(!nodes);
+
+	mutex_lock(&root->fs_info->tree_reloc_mutex);
+	ret = init_reloc_tree(trans, root);
+	BUG_ON(ret);
+	reloc_root = root->reloc_root;
+
+	path->lowest_level = lowest_level;
+	ret = btrfs_search_slot(trans, reloc_root, first_key, path, 0, 0);
+	BUG_ON(ret);
+	/*
+	 * get relocation mapping for tree blocks in the path
+	 */
+	lowest_merge = BTRFS_MAX_LEVEL;
+	for (level = BTRFS_MAX_LEVEL - 1; level >= lowest_level; level--) {
+		u64 new_bytenr;
+		eb = path->nodes[level];
+		if (!eb || eb == reloc_root->node)
+			continue;
+		ret = btrfs_get_reloc_mapping(reloc_root, eb->start, eb->len,
+					      &new_bytenr);
+		if (ret)
+			continue;
+		if (level == 0)
+			btrfs_item_key_to_cpu(eb, &keys[level], 0);
+		else
+			btrfs_node_key_to_cpu(eb, &keys[level], 0);
+		nodes[level] = new_bytenr;
+		lowest_merge = level;
+	}
+
+	update_refs = 0;
+	if (ref_path->owner_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
+		eb = path->nodes[0];
+		if (btrfs_header_generation(eb) < trans->transid)
+			update_refs = 1;
+	}
+
+	btrfs_release_path(reloc_root, path);
+	/*
+	 * merge tree blocks that already relocated in other reloc trees
+	 */
+	if (lowest_merge != BTRFS_MAX_LEVEL) {
+		ret = btrfs_merge_path(trans, reloc_root, keys, nodes,
+				       lowest_merge);
+		BUG_ON(ret < 0);
+	}
+	/*
+	 * cow any tree blocks that still haven't been relocated
+	 */
+	ret = btrfs_search_slot(trans, reloc_root, first_key, path, 0, 1);
+	BUG_ON(ret);
+	/*
+	 * if we are relocating data block group, update extent pointers
+	 * in the newly created tree leaf.
+	 */
+	eb = path->nodes[0];
+	if (update_refs && nodes[0] != eb->start) {
+		ret = replace_extents_in_leaf(trans, reloc_root, eb, group,
+					      reloc_inode);
+		BUG_ON(ret);
+	}
+
+	memset(keys, 0, sizeof(*keys) * BTRFS_MAX_LEVEL);
+	memset(nodes, 0, sizeof(*nodes) * BTRFS_MAX_LEVEL);
+	for (level = BTRFS_MAX_LEVEL - 1; level >= lowest_level; level--) {
+		eb = path->nodes[level];
+		if (!eb || eb == reloc_root->node)
+			continue;
+		BUG_ON(btrfs_header_owner(eb) != BTRFS_TREE_RELOC_OBJECTID);
+		nodes[level] = eb->start;
+		if (level == 0)
+			btrfs_item_key_to_cpu(eb, &keys[level], 0);
+		else
+			btrfs_node_key_to_cpu(eb, &keys[level], 0);
+	}
+
+	if (ref_path->owner_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
+		eb = path->nodes[0];
+		extent_buffer_get(eb);
+	}
+	btrfs_release_path(reloc_root, path);
+	/*
+	 * replace tree blocks in the fs tree with tree blocks in
+	 * the reloc tree.
+	 */
+	ret = btrfs_merge_path(trans, root, keys, nodes, lowest_level);
+	BUG_ON(ret < 0);
+
+	if (ref_path->owner_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
+		ret = invalidate_extent_cache(reloc_root, eb, group, root);
+		BUG_ON(ret);
+		free_extent_buffer(eb);
+	}
+	mutex_unlock(&root->fs_info->tree_reloc_mutex);
+
+	path->lowest_level = 0;
+	kfree(nodes);
+	kfree(keys);
+	return 0;
+}
+
+static int noinline relocate_tree_block(struct btrfs_trans_handle *trans,
+					struct btrfs_root *root,
+					struct btrfs_path *path,
+					struct btrfs_key *first_key,
+					struct btrfs_ref_path *ref_path)
+{
+	int ret;
+	int needs_lock = 0;
+
+	if (root == root->fs_info->extent_root ||
+	    root == root->fs_info->chunk_root ||
+	    root == root->fs_info->dev_root) {
+		needs_lock = 1;
+		mutex_lock(&root->fs_info->alloc_mutex);
+	}
+
+	ret = relocate_one_path(trans, root, path, first_key,
+				ref_path, NULL, NULL);
+	BUG_ON(ret);
+
+	if (root == root->fs_info->extent_root)
+		btrfs_extent_post_op(trans, root);
+	if (needs_lock)
+		mutex_unlock(&root->fs_info->alloc_mutex);
+
+	return 0;
+}
+
+static int noinline del_extent_zero(struct btrfs_trans_handle *trans,
+				    struct btrfs_root *extent_root,
+				    struct btrfs_path *path,
+				    struct btrfs_key *extent_key)
+{
+	int ret;
+
+	mutex_lock(&extent_root->fs_info->alloc_mutex);
+	ret = btrfs_search_slot(trans, extent_root, extent_key, path, -1, 1);
+	if (ret)
+		goto out;
+	ret = btrfs_del_item(trans, extent_root, path);
+out:
+	btrfs_release_path(extent_root, path);
+	mutex_unlock(&extent_root->fs_info->alloc_mutex);
+	return ret;
+}
+
+static struct btrfs_root noinline *read_ref_root(struct btrfs_fs_info *fs_info,
+						struct btrfs_ref_path *ref_path)
+{
+	struct btrfs_key root_key;
+
+	root_key.objectid = ref_path->root_objectid;
+	root_key.type = BTRFS_ROOT_ITEM_KEY;
+	if (is_cowonly_root(ref_path->root_objectid))
+		root_key.offset = 0;
+	else
+		root_key.offset = (u64)-1;
+
+	return btrfs_read_fs_root_no_name(fs_info, &root_key);
+}
+
+static int noinline relocate_one_extent(struct btrfs_root *extent_root,
+					struct btrfs_path *path,
+					struct btrfs_key *extent_key,
+					struct btrfs_block_group_cache *group,
+					struct inode *reloc_inode, int pass)
+{
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *found_root;
+	struct btrfs_ref_path *ref_path = NULL;
+	struct disk_extent *new_extents = NULL;
+	int nr_extents = 0;
+	int loops;
+	int ret;
+	int level;
+	struct btrfs_key first_key;
+	u64 prev_block = 0;
+
+	mutex_unlock(&extent_root->fs_info->alloc_mutex);
+
+	trans = btrfs_start_transaction(extent_root, 1);
+	BUG_ON(!trans);
+
+	if (extent_key->objectid == 0) {
+		ret = del_extent_zero(trans, extent_root, path, extent_key);
+		goto out;
+	}
+
+	ref_path = kmalloc(sizeof(*ref_path), GFP_NOFS);
+	if (!ref_path) {
+	       ret = -ENOMEM;
+	       goto out;
+	}
+
+	for (loops = 0; ; loops++) {
+		if (loops == 0) {
+			ret = btrfs_first_ref_path(trans, extent_root, ref_path,
+						   extent_key->objectid);
+		} else {
+			ret = btrfs_next_ref_path(trans, extent_root, ref_path);
+		}
+		if (ret < 0)
+			goto out;
+		if (ret > 0)
+			break;
+
+		if (ref_path->root_objectid == BTRFS_TREE_LOG_OBJECTID ||
+		    ref_path->root_objectid == BTRFS_TREE_RELOC_OBJECTID)
+			continue;
+
+		found_root = read_ref_root(extent_root->fs_info, ref_path);
+		BUG_ON(!found_root);
+		/*
+		 * for reference counted tree, only process reference paths
+		 * rooted at the latest committed root.
+		 */
+		if (found_root->ref_cows &&
+		    ref_path->root_generation != found_root->root_key.offset)
+			continue;
+
+		if (ref_path->owner_objectid >= BTRFS_FIRST_FREE_OBJECTID) {
+			if (pass == 0) {
+				/*
+				 * copy data extents to new locations
+				 */
+				u64 group_start = group->key.objectid;
+				ret = relocate_data_extent(reloc_inode,
+							   extent_key,
+							   group_start);
+				if (ret < 0)
+					goto out;
+				break;
+			}
+			level = 0;
+		} else {
+			level = ref_path->owner_objectid;
+		}
+
+		if (prev_block != ref_path->nodes[level]) {
+			struct extent_buffer *eb;
+			u64 block_start = ref_path->nodes[level];
+			u64 block_size = btrfs_level_size(found_root, level);
+
+			eb = read_tree_block(found_root, block_start,
+					     block_size, 0);
+			btrfs_tree_lock(eb);
+			BUG_ON(level != btrfs_header_level(eb));
+
+			if (level == 0)
+				btrfs_item_key_to_cpu(eb, &first_key, 0);
+			else
+				btrfs_node_key_to_cpu(eb, &first_key, 0);
+
+			btrfs_tree_unlock(eb);
+			free_extent_buffer(eb);
+			prev_block = block_start;
+		}
+
+		if (ref_path->owner_objectid >= BTRFS_FIRST_FREE_OBJECTID &&
+		    pass >= 2) {
+			/*
+			 * use fallback method to process the remaining
+			 * references.
+			 */
+			if (!new_extents) {
+				u64 group_start = group->key.objectid;
+				ret = get_new_locations(reloc_inode,
+							extent_key,
+							group_start, 0,
+							&new_extents,
+							&nr_extents);
+				if (ret < 0)
+					goto out;
+			}
+			btrfs_record_root_in_trans(found_root);
+			ret = replace_one_extent(trans, found_root,
+						path, extent_key,
+						&first_key, ref_path,
+						new_extents, nr_extents);
+			if (ret < 0)
+				goto out;
+			continue;
+		}
+
+		btrfs_record_root_in_trans(found_root);
+		if (ref_path->owner_objectid < BTRFS_FIRST_FREE_OBJECTID) {
+			ret = relocate_tree_block(trans, found_root, path,
+						  &first_key, ref_path);
+		} else {
+			/*
+			 * try to update data extent references while
+			 * keeping metadata shared between snapshots.
+			 */
+			ret = relocate_one_path(trans, found_root, path,
+						&first_key, ref_path,
+						group, reloc_inode);
+		}
+		if (ret < 0)
+			goto out;
+	}
+	ret = 0;
+out:
+	btrfs_end_transaction(trans, extent_root);
+	kfree(new_extents);
+	kfree(ref_path);
+	mutex_lock(&extent_root->fs_info->alloc_mutex);
+	return ret;
+}
+
+static u64 update_block_group_flags(struct btrfs_root *root, u64 flags)
+{
+	u64 num_devices;
+	u64 stripped = BTRFS_BLOCK_GROUP_RAID0 |
+		BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_RAID10;
+
+	num_devices = root->fs_info->fs_devices->num_devices;
+	if (num_devices == 1) {
+		stripped |= BTRFS_BLOCK_GROUP_DUP;
+		stripped = flags & ~stripped;
+
+		/* turn raid0 into single device chunks */
+		if (flags & BTRFS_BLOCK_GROUP_RAID0)
+			return stripped;
+
+		/* turn mirroring into duplication */
+		if (flags & (BTRFS_BLOCK_GROUP_RAID1 |
+			     BTRFS_BLOCK_GROUP_RAID10))
+			return stripped | BTRFS_BLOCK_GROUP_DUP;
+		return flags;
+	} else {
+		/* they already had raid on here, just return */
+		if (flags & stripped)
+			return flags;
+
+		stripped |= BTRFS_BLOCK_GROUP_DUP;
+		stripped = flags & ~stripped;
+
+		/* switch duplicated blocks with raid1 */
+		if (flags & BTRFS_BLOCK_GROUP_DUP)
+			return stripped | BTRFS_BLOCK_GROUP_RAID1;
+
+		/* turn single device chunks into raid0 */
+		return stripped | BTRFS_BLOCK_GROUP_RAID0;
+	}
+	return flags;
+}
+
+int __alloc_chunk_for_shrink(struct btrfs_root *root,
+		     struct btrfs_block_group_cache *shrink_block_group,
+		     int force)
+{
+	struct btrfs_trans_handle *trans;
+	u64 new_alloc_flags;
+	u64 calc;
+
+	spin_lock(&shrink_block_group->lock);
+	if (btrfs_block_group_used(&shrink_block_group->item) > 0) {
+		spin_unlock(&shrink_block_group->lock);
+		mutex_unlock(&root->fs_info->alloc_mutex);
+
+		trans = btrfs_start_transaction(root, 1);
+		mutex_lock(&root->fs_info->alloc_mutex);
+		spin_lock(&shrink_block_group->lock);
+
+		new_alloc_flags = update_block_group_flags(root,
+						   shrink_block_group->flags);
+		if (new_alloc_flags != shrink_block_group->flags) {
+			calc =
+			     btrfs_block_group_used(&shrink_block_group->item);
+		} else {
+			calc = shrink_block_group->key.offset;
+		}
+		spin_unlock(&shrink_block_group->lock);
+
+		do_chunk_alloc(trans, root->fs_info->extent_root,
+			       calc + 2 * 1024 * 1024, new_alloc_flags, force);
+
+		mutex_unlock(&root->fs_info->alloc_mutex);
+		btrfs_end_transaction(trans, root);
+		mutex_lock(&root->fs_info->alloc_mutex);
+	} else
+		spin_unlock(&shrink_block_group->lock);
+	return 0;
+}
+
+static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
+				 struct btrfs_root *root,
+				 u64 objectid, u64 size)
+{
+	struct btrfs_path *path;
+	struct btrfs_inode_item *item;
+	struct extent_buffer *leaf;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_insert_empty_inode(trans, root, path, objectid);
+	if (ret)
+		goto out;
+
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
+	memset_extent_buffer(leaf, 0, (unsigned long)item, sizeof(*item));
+	btrfs_set_inode_generation(leaf, item, 1);
+	btrfs_set_inode_size(leaf, item, size);
+	btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
+	btrfs_set_inode_flags(leaf, item, BTRFS_INODE_NODATASUM);
+	btrfs_mark_buffer_dirty(leaf);
+	btrfs_release_path(root, path);
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
+static struct inode noinline *create_reloc_inode(struct btrfs_fs_info *fs_info,
+					struct btrfs_block_group_cache *group)
+{
+	struct inode *inode = NULL;
+	struct btrfs_trans_handle *trans;
+	struct btrfs_root *root;
+	struct btrfs_key root_key;
+	u64 objectid = BTRFS_FIRST_FREE_OBJECTID;
+	int err = 0;
+
+	root_key.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
+	root_key.type = BTRFS_ROOT_ITEM_KEY;
+	root_key.offset = (u64)-1;
+	root = btrfs_read_fs_root_no_name(fs_info, &root_key);
+	if (IS_ERR(root))
+		return ERR_CAST(root);
+
+	trans = btrfs_start_transaction(root, 1);
+	BUG_ON(!trans);
+
+	err = btrfs_find_free_objectid(trans, root, objectid, &objectid);
+	if (err)
+		goto out;
+
+	err = __insert_orphan_inode(trans, root, objectid, group->key.offset);
+	BUG_ON(err);
+
+	err = btrfs_insert_file_extent(trans, root, objectid, 0, 0, 0,
+				       group->key.offset, 0);
+	BUG_ON(err);
+
+	inode = btrfs_iget_locked(root->fs_info->sb, objectid, root);
+	if (inode->i_state & I_NEW) {
+		BTRFS_I(inode)->root = root;
+		BTRFS_I(inode)->location.objectid = objectid;
+		BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY;
+		BTRFS_I(inode)->location.offset = 0;
+		btrfs_read_locked_inode(inode);
+		unlock_new_inode(inode);
+		BUG_ON(is_bad_inode(inode));
+	} else {
+		BUG_ON(1);
+	}
+
+	err = btrfs_orphan_add(trans, inode);
+out:
+	btrfs_end_transaction(trans, root);
+	if (err) {
+		if (inode)
+			iput(inode);
+		inode = ERR_PTR(err);
+	}
+	return inode;
+}
+
+int btrfs_relocate_block_group(struct btrfs_root *root, u64 group_start)
+{
+	struct btrfs_trans_handle *trans;
+	struct btrfs_path *path;
+	struct btrfs_fs_info *info = root->fs_info;
+	struct extent_buffer *leaf;
+	struct inode *reloc_inode;
+	struct btrfs_block_group_cache *block_group;
+	struct btrfs_key key;
+	u64 cur_byte;
+	u64 total_found;
+	u32 nritems;
+	int ret;
+	int progress;
+	int pass = 0;
+
+	root = root->fs_info->extent_root;
+
+	block_group = btrfs_lookup_block_group(info, group_start);
+	BUG_ON(!block_group);
+
+	printk("btrfs relocating block group %llu flags %llu\n",
+	       (unsigned long long)block_group->key.objectid,
+	       (unsigned long long)block_group->flags);
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+
+	reloc_inode = create_reloc_inode(info, block_group);
+	BUG_ON(IS_ERR(reloc_inode));
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+
+	__alloc_chunk_for_shrink(root, block_group, 1);
+	block_group->ro = 1;
+	block_group->space_info->total_bytes -= block_group->key.offset;
+
+	mutex_unlock(&root->fs_info->alloc_mutex);
+
+	btrfs_start_delalloc_inodes(info->tree_root);
+	btrfs_wait_ordered_extents(info->tree_root, 0);
+again:
+	total_found = 0;
+	progress = 0;
+	key.objectid = block_group->key.objectid;
+	key.offset = 0;
+	key.type = 0;
+	cur_byte = key.objectid;
+
+	trans = btrfs_start_transaction(info->tree_root, 1);
+	btrfs_commit_transaction(trans, info->tree_root);
+
+	mutex_lock(&root->fs_info->cleaner_mutex);
+	btrfs_clean_old_snapshots(info->tree_root);
+	btrfs_remove_leaf_refs(info->tree_root, (u64)-1, 1);
+	mutex_unlock(&root->fs_info->cleaner_mutex);
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+
+	while(1) {
+		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+		if (ret < 0)
+			goto out;
+next:
+		leaf = path->nodes[0];
+		nritems = btrfs_header_nritems(leaf);
+		if (path->slots[0] >= nritems) {
+			ret = btrfs_next_leaf(root, path);
+			if (ret < 0)
+				goto out;
+			if (ret == 1) {
+				ret = 0;
+				break;
+			}
+			leaf = path->nodes[0];
+			nritems = btrfs_header_nritems(leaf);
+		}
+
+		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+
+		if (key.objectid >= block_group->key.objectid +
+		    block_group->key.offset)
+			break;
+
+		if (progress && need_resched()) {
+			btrfs_release_path(root, path);
+			mutex_unlock(&root->fs_info->alloc_mutex);
+			cond_resched();
+			mutex_lock(&root->fs_info->alloc_mutex);
+			progress = 0;
+			continue;
+		}
+		progress = 1;
+
+		if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY ||
+		    key.objectid + key.offset <= cur_byte) {
+			path->slots[0]++;
+			goto next;
+		}
+
+		total_found++;
+		cur_byte = key.objectid + key.offset;
+		btrfs_release_path(root, path);
+
+		__alloc_chunk_for_shrink(root, block_group, 0);
+		ret = relocate_one_extent(root, path, &key, block_group,
+					  reloc_inode, pass);
+		BUG_ON(ret < 0);
+
+		key.objectid = cur_byte;
+		key.type = 0;
+		key.offset = 0;
+	}
+
+	btrfs_release_path(root, path);
+	mutex_unlock(&root->fs_info->alloc_mutex);
+
+	if (pass == 0) {
+		btrfs_wait_ordered_range(reloc_inode, 0, (u64)-1);
+		invalidate_mapping_pages(reloc_inode->i_mapping, 0, -1);
+		WARN_ON(reloc_inode->i_mapping->nrpages);
+	}
+
+	if (total_found > 0) {
+		printk("btrfs found %llu extents in pass %d\n",
+		       (unsigned long long)total_found, pass);
+		pass++;
+		goto again;
+	}
+
+	/* delete reloc_inode */
+	iput(reloc_inode);
+
+	/* unpin extents in this range */
+	trans = btrfs_start_transaction(info->tree_root, 1);
+	btrfs_commit_transaction(trans, info->tree_root);
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+
+	spin_lock(&block_group->lock);
+	WARN_ON(block_group->pinned > 0);
+	WARN_ON(block_group->reserved > 0);
+	WARN_ON(btrfs_block_group_used(&block_group->item) > 0);
+	spin_unlock(&block_group->lock);
+	ret = 0;
+out:
+	mutex_unlock(&root->fs_info->alloc_mutex);
+	btrfs_free_path(path);
+	return ret;
+}
+
+int find_first_block_group(struct btrfs_root *root, struct btrfs_path *path,
+			   struct btrfs_key *key)
+{
+	int ret = 0;
+	struct btrfs_key found_key;
+	struct extent_buffer *leaf;
+	int slot;
+
+	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
+	if (ret < 0)
+		goto out;
+
+	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 out;
+			break;
+		}
+		btrfs_item_key_to_cpu(leaf, &found_key, slot);
+
+		if (found_key.objectid >= key->objectid &&
+		    found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
+			ret = 0;
+			goto out;
+		}
+		path->slots[0]++;
+	}
+	ret = -ENOENT;
+out:
+	return ret;
+}
+
+int btrfs_free_block_groups(struct btrfs_fs_info *info)
+{
+	struct btrfs_block_group_cache *block_group;
+	struct rb_node *n;
+
+	mutex_lock(&info->alloc_mutex);
+	spin_lock(&info->block_group_cache_lock);
+	while ((n = rb_last(&info->block_group_cache_tree)) != NULL) {
+		block_group = rb_entry(n, struct btrfs_block_group_cache,
+				       cache_node);
+
+		spin_unlock(&info->block_group_cache_lock);
+		btrfs_remove_free_space_cache(block_group);
+		spin_lock(&info->block_group_cache_lock);
+
+		rb_erase(&block_group->cache_node,
+			 &info->block_group_cache_tree);
+		spin_lock(&block_group->space_info->lock);
+		list_del(&block_group->list);
+		spin_unlock(&block_group->space_info->lock);
+		kfree(block_group);
+	}
+	spin_unlock(&info->block_group_cache_lock);
+	mutex_unlock(&info->alloc_mutex);
+	return 0;
+}
+
+int btrfs_read_block_groups(struct btrfs_root *root)
+{
+	struct btrfs_path *path;
+	int ret;
+	struct btrfs_block_group_cache *cache;
+	struct btrfs_fs_info *info = root->fs_info;
+	struct btrfs_space_info *space_info;
+	struct btrfs_key key;
+	struct btrfs_key found_key;
+	struct extent_buffer *leaf;
+
+	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;
+
+	mutex_lock(&root->fs_info->alloc_mutex);
+	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;
+			break;
+		}
+
+		spin_lock_init(&cache->lock);
+		INIT_LIST_HEAD(&cache->list);
+		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));
+
+		key.objectid = found_key.objectid + found_key.offset;
+		btrfs_release_path(root, path);
+		cache->flags = btrfs_block_group_flags(&cache->item);
+
+		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;
+		spin_lock(&space_info->lock);
+		list_add(&cache->list, &space_info->block_groups);
+		spin_unlock(&space_info->lock);
+
+		ret = btrfs_add_block_group_cache(root->fs_info, cache);
+		BUG_ON(ret);
+
+		set_avail_alloc_bits(root->fs_info, cache->flags);
+	}
+	ret = 0;
+error:
+	btrfs_free_path(path);
+	mutex_unlock(&root->fs_info->alloc_mutex);
+	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)
+{
+	int ret;
+	struct btrfs_root *extent_root;
+	struct btrfs_block_group_cache *cache;
+
+	WARN_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	extent_root = root->fs_info->extent_root;
+
+	root->fs_info->last_trans_new_blockgroup = trans->transid;
+
+	cache = kzalloc(sizeof(*cache), GFP_NOFS);
+	if (!cache)
+		return -ENOMEM;
+
+	cache->key.objectid = chunk_offset;
+	cache->key.offset = size;
+	spin_lock_init(&cache->lock);
+	INIT_LIST_HEAD(&cache->list);
+	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);
+
+	ret = update_space_info(root->fs_info, cache->flags, size, bytes_used,
+				&cache->space_info);
+	BUG_ON(ret);
+	spin_lock(&cache->space_info->lock);
+	list_add(&cache->list, &cache->space_info->block_groups);
+	spin_unlock(&cache->space_info->lock);
+
+	ret = btrfs_add_block_group_cache(root->fs_info, cache);
+	BUG_ON(ret);
+
+	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);
+	set_avail_alloc_bits(extent_root->fs_info, type);
+
+	return 0;
+}
+
+int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *root, u64 group_start)
+{
+	struct btrfs_path *path;
+	struct btrfs_block_group_cache *block_group;
+	struct btrfs_key key;
+	int ret;
+
+	BUG_ON(!mutex_is_locked(&root->fs_info->alloc_mutex));
+	root = root->fs_info->extent_root;
+
+	block_group = btrfs_lookup_block_group(root->fs_info, group_start);
+	BUG_ON(!block_group);
+
+	memcpy(&key, &block_group->key, sizeof(key));
+
+	path = btrfs_alloc_path();
+	BUG_ON(!path);
+
+	btrfs_remove_free_space_cache(block_group);
+	rb_erase(&block_group->cache_node,
+		 &root->fs_info->block_group_cache_tree);
+	spin_lock(&block_group->space_info->lock);
+	list_del(&block_group->list);
+	spin_unlock(&block_group->space_info->lock);
+
+	/*
+	memset(shrink_block_group, 0, sizeof(*shrink_block_group));
+	kfree(shrink_block_group);
+	*/
+
+	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+	if (ret > 0)
+		ret = -EIO;
+	if (ret < 0)
+		goto out;
+
+	ret = btrfs_del_item(trans, root, path);
+out:
+	btrfs_free_path(path);
+	return ret;
+}