nixos/swap: add discardPolicy option

Add option for activating discards on swap partitions (none, once, pages and both).

1 files changed, 13 insertions, 0 deletions

diff --git a/nixos/modules/config/swap.nix b/nixos/modules/config/swap.nix
index 59bc9e9d11e..a37b46b8c46 100644
--- a/nixos/modules/config/swap.nix
+++ b/nixos/modules/config/swap.nix
@@ -114,6 +114,19 @@ let
         '';
       };
 
+      discardPolicy = mkOption {
+        default = null;
+        example = "once";
+        type = types.nullOr (types.enum ["once" "pages" "both" ]);
+        description = ''
+          Specify the discard policy for the swap device. If "once", then the
+          whole swap space is discarded at swapon invocation. If "pages",
+          asynchronous discard on freed pages is performed, before returning to
+          the available pages pool. With "both", both policies are activated.
+          See swapon(8) for more information.
+        '';
+      };
+
       deviceName = mkOption {
         type = types.str;
         internal = true;