def remount_with_additional_flags(mountpoint, existing_options, mountflags):
    """Remount an existing mount point with additional flags.
    @param mountpoint: the mount point as bytes
    @param existing_options: dict with current mount existing_options as bytes
    @param mountflags: int with additional mount existing_options (cf. libc.MS_* constants)
    """
    mountflags |= libc.MS_REMOUNT|libc.MS_BIND
    for option, flag in libc.MOUNT_FLAGS.items():
        if option in existing_options:
            mountflags |= flag

    libc.mount(None, mountpoint, None, mountflags, None)
Remount an existing mount point with additional flags.
    @param mountpoint: the mount point as bytes
    @param existing_options: dict with current mount existing_options as bytes
    @param mountflags: int with additional mount existing_options (cf. libc.MS_* constants)