nixos/smartd: allow extra cli options for daemon

This enables further customization of smartd.

nixos/modules/services/monitoring/smartd.nix

···
        "DEVICESCAN ${notifyOpts}${cfg.defaults.autodetected}"}
   '';
 
-  smartdOpts = { name, ... }: {
+  smartdDeviceOpts = { name, ... }: {
 
     options = {
 
···
 
           Set to false to monitor the devices listed in
           <option>services.smartd.devices</option> only.
+        '';
+      };
+
+      extraOptions = mkOption {
+        default = [];
+        type = types.listOf types.str;
+        example = ["-A /var/log/smartd/" "--interval=3600"];
+        description = ''
+          Extra command-line options passed to the <literal>smartd</literal>
+          daemon on startup.
+
+          (See <literal>man 8 smartd</literal>.)
         '';
       };
 
···
       devices = mkOption {
         default = [];
         example = [ { device = "/dev/sda"; } { device = "/dev/sdb"; options = "-d sat"; } ];
-        type = with types; listOf (submodule smartdOpts);
+        type = with types; listOf (submodule smartdDeviceOpts);
         description = "List of devices to monitor.";
       };
 
···
 
       path = [ pkgs.nettools ]; # for hostname and dnsdomanname calls in smartd
 
-      serviceConfig.ExecStart = "${pkgs.smartmontools}/sbin/smartd --no-fork --configfile=${smartdConf}";
+      serviceConfig.ExecStart = "${pkgs.smartmontools}/sbin/smartd ${lib.concatStringsSep " " cfg.extraOptions} --no-fork --configfile=${smartdConf}";
     };
 
   };