Btrfs: Drop dirty roots created by log replay immediately when

The log replay produces dirty roots. These dirty roots
should be dropped immediately if the fs is mounted as
ro. Otherwise they can be added to the dirty root list
again when remounting the fs as rw. Thank you,

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

fs/btrfs/disk-io.c

@@ -1757,6 +1757,11 @@ struct btrfs_root *open_ctree(struct super_block *sb,
 						      generation + 1);
 		ret = btrfs_recover_log_trees(log_tree_root);
 		BUG_ON(ret);
+
+		if (sb->s_flags & MS_RDONLY) {
+			ret =  btrfs_commit_super(tree_root);
+			BUG_ON(ret);
+		}
 	}
 
 	if (!(sb->s_flags & MS_RDONLY)) {