nixos/cachefilesd: don't set up manually

Use our available infrastructure instead of manually handling setup.

nixos/modules/services/network-filesystems/cachefilesd.nix

@@ -43,17 +43,21 @@ in
 
   config = mkIf cfg.enable {
 
+    boot.kernelModules = [ "cachefiles" ];
+
     systemd.services.cachefilesd = {
       description = "Local network file caching management daemon";
       wantedBy = [ "multi-user.target" ];
-      path = [ pkgs.kmod pkgs.cachefilesd ];
-      script = ''
-        modprobe -qab cachefiles
-        mkdir -p ${cfg.cacheDir}
-        chmod 700 ${cfg.cacheDir}
-        exec cachefilesd -n -f ${cfgFile}
-      '';
+      serviceConfig = {
+        Type = "exec";
+        ExecStart = "${pkgs.cachefilesd}/bin/cachefilesd -n -f ${cfgFile}";
+        Restart = "on-failure";
+        PrivateTmp = true;
+      };
     };
 
+    systemd.tmpfiles.rules = [
+      "d ${cfg.cacheDir} 0700 root root - -"
+    ];
   };
 }