From 7aee0dac1f0995e69d8b2c38ce21b3709bf7c929 Mon Sep 17 00:00:00 2001
From: Ihor Antonov <ngortheone@users.noreply.github.com>
Date: Wed, 25 Apr 2018 17:51:53 -0400
Subject: [PATCH] Fix root volume resizing on EC2 KVM instances (M5, C5, etc)
 (#39488)

(cherry picked from commit 3a47c7e8f67c6ece266f570d6db9598856512ede)
---
 nixos/modules/virtualisation/grow-partition.nix | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/virtualisation/grow-partition.nix b/nixos/modules/virtualisation/grow-partition.nix
index 5039118d78eeeb..0255831fcf64b0 100644
--- a/nixos/modules/virtualisation/grow-partition.nix
+++ b/nixos/modules/virtualisation/grow-partition.nix
@@ -32,8 +32,15 @@ with lib;
       rootDevice="${config.fileSystems."/".device}"
       if [ -e "$rootDevice" ]; then
         rootDevice="$(readlink -f "$rootDevice")"
-        parentDevice="$(lsblk -npo PKNAME "$rootDevice")"
-        TMPDIR=/run sh $(type -P growpart) "$parentDevice" "''${rootDevice#$parentDevice}"
+        parentDevice="$rootDevice"
+        while [ "''${parentDevice%[0-9]}" != "''${parentDevice}" ]; do
+          parentDevice="''${parentDevice%[0-9]}";
+        done
+        partNum="''${rootDevice#''${parentDevice}}"
+        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
     '';