nixos-server: fix mounting race condition

hosts/vergil/configuration.nix

@@ -11,5 +11,24 @@ in
     ../shared/nixos-server.nix
   ];
 
+  systemd.services.mount-vm-disk = {
+    description = "Mount Proxmox VM disk via kpartx";
+    after = [ "storage-vm--100--disk--0.device" ];
+    wants = [ "storage-vm--100--disk--0.device" ];
+
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+      ExecStart = "${pkgs.multipath-tools}/sbin/kpartx -av /dev/storage/vm-100-disk-0";
+      ExecStop = "${pkgs.multipath-tools}/sbin/kpartx -dv /dev/storage/vm-100-disk-0";
+    };
+
+    wantedBy = [ "multi-user.target" ];
+  };
+
+  environment.systemPackages = with pkgs; [
+    multipath-tools
+  ];
+
   networking.hostName = "vergil";
 }

hosts/vergil/hardware.nix

@@ -55,6 +55,16 @@
         "dmask=0077"
       ];
     };
+
+    "/mnt" = {
+      device = "/dev/disk/by-uuid/1432aeae-71e9-4f34-97dc-cf0fe74a4e00";
+      fsType = "xfs";
+      options = [ 
+        "noauto"
+        "x-systemd.automount"
+        "x-systemd.after=mount-vm-disk.service"
+      ];
+    };
   };
 
   swapDevices = [ ];