Merge pull request #53 from jcumming/zfs.121204

add a zfs module

modules/module-list.nix

@@ -225,6 +225,7 @@
   ./tasks/filesystems/unionfs-fuse.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 +1,68 @@
+{ config, pkgs, ... }:
+#
+# todo:
+#   - crontab for scrubs, etc
+#   - zfs tunables
+#   - /etc/zfs/zpool.cache handling
+
+
+with pkgs.lib;
+
+let
+
+  cfgSpl = config.boot.spl;
+  inInitrd = any (fs: fs == "zfs") config.boot.initrd.supportedFilesystems;
+  inSystem = any (fs: fs == "zfs") config.boot.supportedFilesystems;
+  kernel = config.boot.kernelPackages;
+
+in
+
+{
+
+  ###### interface
+  
+  options = { 
+    boot.spl.hostid = mkOption { 
+      default = "";
+      example = "0xdeadbeef";
+      description = ''
+        ZFS uses a system's hostid to determine if a storage pool (zpool) is
+        native to this system, and should thus be imported automatically.
+        Unfortunately, this hostid can change under linux from boot to boot (by
+        changing network adapaters, for instance). Specify a unique 32 bit hostid in
+        hex here for zfs to prevent getting a random hostid between boots and having to
+        manually import pools.
+      '';
+    };
+  };
+
+  ###### implementation
+
+  config = mkIf ( inInitrd || inSystem ) {
+
+    boot = { 
+      kernelModules = [ "spl" "zfs" ] ;
+      extraModulePackages = [ kernel.zfs kernel.spl ];
+      extraModprobeConfig = mkIf (cfgSpl.hostid != "") "options spl spl_hostid=${cfgSpl.hostid}";
+    };
+
+    boot.initrd = mkIf inInitrd { 
+      kernelModules = [ "spl" "zfs" ] ;
+      extraUtilsCommands =
+        ''
+          cp -v ${kernel.zfs}/sbin/zfs $out/sbin
+          cp -v ${kernel.zfs}/sbin/zdb $out/sbin
+          cp -v ${kernel.zfs}/sbin/zpool $out/sbin
+        '';
+      postDeviceCommands =
+        ''
+          zpool import -f -a -d /dev
+          zfs mount -a
+        '';
+    };
+
+    system.fsPackages = [ kernel.zfs ];                  # XXX: needed? zfs doesn't have a fsck
+    environment.systemPackages = [ kernel.zfs ];
+    services.udev.packages = [ kernel.zfs ];             # to hook zvol naming, etc. 
+  };
+}