Btrfs: fix unprotected device->bytes_used update

We should update device->bytes_used in the lock context of
chunk_mutex, or we would get wrong data.
Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NChris Mason <clm@fb.com>

fs/btrfs/volumes.c

@@ -4429,6 +4429,9 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	if (ret)
 		goto error_del_extent;
 
+	for (i = 0; i < map->num_stripes; i++)
+		map->stripes[i].dev->bytes_used += stripe_size;
+
 	free_extent_map(em);
 	check_raid56_incompat_flag(extent_root->fs_info, type);
 
@@ -4500,7 +4503,6 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
 		device = map->stripes[i].dev;
 		dev_offset = map->stripes[i].physical;
 
-		device->bytes_used += stripe_size;
 		ret = btrfs_update_device(trans, device);
 		if (ret)
 			goto out;