Add zfs module.

modules/module-list.nix

@@ -220,6 +220,7 @@
   ./tasks/filesystems/reiserfs.nix
   ./tasks/filesystems/vfat.nix
   ./tasks/filesystems/xfs.nix
+  ./tasks/filesystems/zfs.nix
   ./tasks/kbd.nix
   ./tasks/lvm.nix
   ./tasks/network-interfaces.nix

modules/tasks/filesystems/zfs.nix

@@ -0,0 +1,40 @@
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let
+
+  inInitrd = any (fs: fs == "zfs") config.boot.initrd.supportedFilesystems;
+  kernel = config.boot.kernelPackages;
+
+in
+
+{
+  ###### implementation
+
+  config = mkIf (any (fs: fs == "zfs") config.boot.supportedFilesystems) {
+
+    boot.kernelModules = [ "spl" "zavl" "zcommon" "zfs" "zlib_deflate" "znvpair" "zunicode" ] ;
+
+    boot.initrd.kernelModules = mkIf inInitrd [ "spl" "zavl" "zcommon" "zfs" "zlib_deflate" "znvpair" "zunicode" ] ;
+
+    boot.initrd.extraUtilsCommands = mkIf inInitrd
+      ''
+        cp -v ${kernel.zfs}/sbin/zfs $out/sbin
+        cp -v ${kernel.zfs}/sbin/zdb $out/sbin
+        cp -v ${kernel.zfs}/sbin/zpool $out/sbin
+      '';
+
+    boot.initrd.postDeviceCommands = mkIf inInitrd
+      ''
+        zpool import -f -a -d /dev
+        zfs mount -a
+      '';
+
+    system.fsPackages = [ kernel.zfs ];
+
+    environment.systemPackages = [ kernel.zfs ];
+
+    services.udev.packages = [ kernel.zfs ];
+  };
+}