Enable cgroup v2

[nicholasdille]

: "${cgroup_version:=v2}"
current_cgroup_version="v1"
if test "$(stat -fc %T /sys/fs/cgroup/)" == "cgroup2fs"; then
    current_cgroup_version="v2"
fi
if type update-grub >/dev/null 2>&1 && test "${cgroup_version}" == "v2" && test "${current_cgroup_version}" == "v1"; then
    if test -n "${WSL_DISTRO_NAME}"; then
        error "Unable to enable cgroup v2 on WSL. Please refer to https://github.com/microsoft/WSL/issues/6662."
        error "        Please rerun this script with CGROUP_VERSION=v1"
        exit 1
    fi

    echo "cgroup v2"
    echo "Configure grub"
    sed -i 's/GRUB_CMDLINE_LINUX=""/GRUB_CMDLINE_LINUX="systemd.unified_cgroup_hierarchy=1"/' "${prefix}/etc/default/grub"
    echo "Update grub"
    update-grub

    if ! ${no_cgroup_reboot}; then
        read -r -p "Reboot to enable cgroup v2 (y/N)"
        if test "${REPLY,,}" == "y"; then
            reboot
            exit
        fi
    fi
fi