Merge

    if (loop) {

        int file_fd, device_fd;

        int flags;

        flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR;

        // FIXME - only one loop mount supported at a time

        file_fd = open(dev, O_RDWR);

        file_fd = open(dev, flags);

        if (file_fd < -1) {

            perror("open backing file failed");

            return 1;

        }

        device_fd = open(LOOP_DEVICE, O_RDWR);

        device_fd = open(LOOP_DEVICE, flags);

        if (device_fd < -1) {

            perror("open loop device failed");

            close(file_fd);