Btrfs: Insert extent record and the first backref in a single balance

	u64 root_used;

	u64 search_start = 0;

	u64 new_hint;

	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_item *extent_item;

	struct btrfs_extent_ref *ref;

	struct btrfs_path *path;

	btrfs_set_stack_extent_refs(&extent_item, 1);

	struct btrfs_key keys[2];

	new_hint = max(hint_byte, root->fs_info->alloc_start);

	if (new_hint < btrfs_super_total_bytes(&info->super_copy))

	WARN_ON(trans->alloc_exclude_nr);

	trans->alloc_exclude_start = ins->objectid;

	trans->alloc_exclude_nr = ins->offset;

	ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,

				sizeof(extent_item));

	trans->alloc_exclude_start = 0;

	trans->alloc_exclude_nr = 0;

	BUG_ON(ret);

	memcpy(&keys[0], ins, sizeof(*ins));

	keys[1].offset = hash_extent_ref(root_objectid, ref_generation,

					 owner, owner_offset);

	keys[1].objectid = ins->objectid;

	keys[1].type = BTRFS_EXTENT_REF_KEY;

	sizes[0] = sizeof(*extent_item);

	sizes[1] = sizeof(*ref);

	path = btrfs_alloc_path();

	BUG_ON(!path);

	ret = btrfs_insert_extent_backref(trans, extent_root, path,

					  ins->objectid, root_objectid,

					  ref_generation, owner, owner_offset);

	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_offset(path->nodes[0], ref, owner_offset);

	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);