nixos/swap: make sure all kernel modules are loaded before creating swap devices. (#239163)

          let realDevice' = escapeSystemdPath sw.realDevice;

          in nameValuePair "mkswap-${sw.deviceName}"

          { description = "Initialisation of swap device ${sw.device}";

            # The mkswap service fails for file-backed swap devices if the

            # loop module has not been loaded before the service runs.

            # We add an ordering constraint to run after systemd-modules-load to

            # avoid this race condition.

            after = [ "systemd-modules-load.service" ];

            wantedBy = [ "${realDevice'}.swap" ];

            before = [ "${realDevice'}.swap" ];

            path = [ pkgs.util-linux pkgs.e2fsprogs ]