mkosi: Switch from btrfs to ext4

Mounting multiple btrfs filesystems with the same fsid only works
properly from kernel 6.7 onwards. Let's switch to ext4 for now which
does support this.

mkosi.conf

@@ -14,6 +14,9 @@ MinimumVersion=23~devel
 Environment=ASAN_OPTIONS=verify_asan_link_order=false
             MKOSI_ASAN_OPTIONS=strict_string_checks=1:detect_stack_use_after_return=1:check_initialization_order=1:strict_init_order=1:disable_coredump=0:use_madv_dontdump=1
             MKOSI_UBSAN_OPTIONS=print_stacktrace=1:print_summary=1:halt_on_error=1
+            # The kernel versions in CentOS Stream 9 and Ubuntu 22.04 don't support orphan_file, but later
+            # versions of mkfs.ext4 enabled it by default, so we disable it explicitly.
+            SYSTEMD_REPART_MKFS_OPTIONS_EXT4="-O ^orphan_file"
 @SELinuxRelabel=no
 BuildSourcesEphemeral=yes
 

mkosi.conf.d/10-centos.conf

@@ -8,6 +8,3 @@ Distribution=centos
 Repositories=epel
              epel-next
              hyperscale-packages-main
-
-[Content]
-Environment=SYSTEMD_REPART_MKFS_OPTIONS_EXT4="-O ^orphan_file"

mkosi.images/system/mkosi.conf.d/10-centos/mkosi.conf

@@ -3,9 +3,6 @@
 [Match]
 Distribution=centos
 
-[Output]
-RepartDirectories=mkosi.repart
-
 [Content]
 Packages=
         rpmautospec-rpm-macros

mkosi.images/system/mkosi.conf.d/10-centos/mkosi.repart/10-root.conf.d/xfs.conf

@@ -1,6 +0,0 @@
-# SPDX-License-Identifier: LGPL-2.1-or-later
-
-[Partition]
-# btrfs isn't supported on CentOS. Ideally we'd use xfs instead but we lose xattrs when doing rootless
-# population of xfs which is required for testing SELinux so let's do ext4 instead.
-Format=ext4

mkosi.images/system/mkosi.repart/10-root.conf

@@ -2,7 +2,7 @@
 
 [Partition]
 Type=root
-Format=btrfs
+Format=ext4
 CopyFiles=/
 SizeMinBytes=8G
 SizeMaxBytes=8G