From 80a578580fae24c59611091e45f4d04e7d626a2d Mon Sep 17 00:00:00 2001
From: Arian van Putten <arian.vanputten@gmail.com>
Date: Mon, 16 Oct 2023 11:57:34 +0000
Subject: [PATCH] nixos/grow-partition: Resize partition online instead of in
 initrd

There's no reason to do this in initrd. Partitions can be resized online.
We just have to make sure it happens before we resize the file system.

This also makes grow-partition work with systemd-initrd
---
 nixos/modules/system/boot/grow-partition.nix | 52 +++++++++-----------
 1 file changed, 24 insertions(+), 28 deletions(-)

diff --git a/nixos/modules/system/boot/grow-partition.nix b/nixos/modules/system/boot/grow-partition.nix
index a2764187a533..1ce4d5e56233 100644
--- a/nixos/modules/system/boot/grow-partition.nix
+++ b/nixos/modules/system/boot/grow-partition.nix
@@ -16,29 +16,28 @@ with lib;
   };
 
   config = mkIf config.boot.growPartition {
+    assertions = [
+      {
+        assertion = !config.boot.initrd.systemd.repart.enable && !config.systemd.repart.enable;
+        message = "systemd-repart already grows the root partition and thus you should not use boot.growPartition";
+      }
+    ];
+    systemd.services.growpart = {
+      wantedBy = [ "-.mount" ];
+      after = [ "-.mount" ];
+      before = [ "systemd-growfs-root.service" ];
+      conflicts = [ "shutdown.target" ];
+      unitConfig.DefaultDependencies = false;
+      serviceConfig = {
+        Type = "oneshot";
+        RemainAfterExit = true;
+        TimeoutSec = "infinity";
+        # growpart returns 1 if the partition is already grown
+        SuccessExitStatus = "0 1";
+      };
 
-    assertions = [{
-      assertion = !config.boot.initrd.systemd.enable;
-      message = "systemd stage 1 does not support 'boot.growPartition' yet.";
-    }];
-
-    boot.initrd.extraUtilsCommands = ''
-      copy_bin_and_libs ${pkgs.gawk}/bin/gawk
-      copy_bin_and_libs ${pkgs.gnused}/bin/sed
-      copy_bin_and_libs ${pkgs.util-linux}/sbin/sfdisk
-      copy_bin_and_libs ${pkgs.util-linux}/sbin/lsblk
-
-      substitute "${pkgs.cloud-utils.guest}/bin/.growpart-wrapped" "$out/bin/growpart" \
-        --replace "${pkgs.bash}/bin/sh" "/bin/sh" \
-        --replace "awk" "gawk" \
-        --replace "sed" "gnused"
-
-      ln -s sed $out/bin/gnused
-    '';
-
-    boot.initrd.postDeviceCommands = ''
-      rootDevice="${config.fileSystems."/".device}"
-      if waitDevice "$rootDevice"; then
+      script = ''
+        rootDevice="${config.fileSystems."/".device}"
         rootDevice="$(readlink -f "$rootDevice")"
         parentDevice="$rootDevice"
         while [ "''${parentDevice%[0-9]}" != "''${parentDevice}" ]; do
@@ -48,11 +47,8 @@ with lib;
         if [ "''${parentDevice%[0-9]p}" != "''${parentDevice}" ] && [ -b "''${parentDevice%p}" ]; then
           parentDevice="''${parentDevice%p}"
         fi
-        TMPDIR=/run sh $(type -P growpart) "$parentDevice" "$partNum"
-        udevadm settle
-      fi
-    '';
-
+        "${pkgs.cloud-utils.guest}/bin/growpart" "$parentDevice" "$partNum"
+      '';
+    };
   };
-
 }