From 9e0b115e0cfcbd0fe97df40dddc11b0946a1d93b Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 8 Oct 2021 12:39:40 +0200
Subject: [PATCH] mkosi: discard partition block devices before writing into
 them with dd's 'sparse' option

Otherwise there might be the GPT footer lingering in the partition.
---
 mkosi/__init__.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mkosi/__init__.py b/mkosi/__init__.py
index 5b8bb7dfb..fb30e7bef 100644
--- a/mkosi/__init__.py
+++ b/mkosi/__init__.py
@@ -3551,6 +3551,9 @@ def insert_partition(
 
         with cm as dev:
             path = dev if dev is not None else part.blockdev(loopdev)
+            # Let's discard the partition block device first, to ensure the GPT partition table footer that
+            # likely is stored in it is flushed out. After all we want to write with dd's sparse option.
+            run(["blkdiscard", path])
             run(["dd", f"if={blob.name}", f"of={path}", "conv=nocreat,sparse"])
 
     return blob_size
-- 
2.47.3