* Add a ‘size’ option to ‘swapDevices’ to create swapfiles on the fly.

svn path=/nixos/trunk/; revision=34478

modules/config/swap.nix

@@ -33,13 +33,22 @@ with pkgs.lib;
 
           device = mkOption {
             example = "/dev/sda3";
-            type = types.string;
+            type = types.uniq types.string;
             description = "Path of the device.";
           };
 
           label = mkOption {
             example = "swap";
-            type = types.string;
+            type = types.uniq types.string;
+            description = ''
+              Label of the device.  Can be used instead of <varname>device</varname>.
+            '';
+          };
+
+          size = mkOption {
+            default = null;
+            example = "swap";
+            type = types.nullOr types.int;
             description = ''
               Label of the device.  Can be used instead of <varname>device</varname>.
             '';

modules/tasks/filesystems.nix

@@ -22,7 +22,7 @@ let
 
       # Swap devices.
       ${flip concatMapStrings config.swapDevices (sw:
-           "${sw.device} none swap\n"
+          "${sw.device} none swap\n"
       )}
     '';
 
@@ -213,6 +213,17 @@ in
             ${flip concatMapStrings config.fileSystems (fs: optionalString fs.autocreate ''
               mkdir -p -m 0755 '${fs.mountPoint}'
             '')}
+
+            # Create missing swapfiles.
+            # FIXME: support changing the size of existing swapfiles.
+            ${flip concatMapStrings config.swapDevices (sw: optionalString (sw.size != null) ''
+              if [ ! -e "${sw.device}" -a -e "$(dirname "${sw.device}")" ]; then
+                # FIXME: use ‘fallocate’ on filesystems that support it.
+                dd if=/dev/zero of="${sw.device}" bs=1M count=${toString sw.size}
+                mkswap ${sw.device}
+              fi
+            '')}
+            
           '';
 
         daemonType = "daemon";