Btrfs: pause the space balance when remounting to R/O

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/super.c

@@ -1263,6 +1263,7 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
 
 		btrfs_dev_replace_suspend_for_unmount(fs_info);
 		btrfs_scrub_cancel(fs_info);
+		btrfs_pause_balance(fs_info);
 
 		ret = btrfs_commit_super(root);
 		if (ret)