Bug#963573: partman-target: please add systemd hints to fstab

[Chris Hofstaedtler <zeha@debian.org>]

Source: partman-target
Version: 115

Dear Installer Team,

please consider adding words informing users they should run
"systemctl daemon-reload" after changing /etc/fstab.

With stale mount units from an older /etc/fstab, users might observe
"interesting surprises", f.e. systemd might umount newly mounted
filesystems, if the in-memory mount units conflict with info in
/etc/fstab.

Please find a potential patch attached.

Thanks,
Chris

>From 0cae8e3d5e18fae9961894336f5cd9bd0fdcc7f2 Mon Sep 17 00:00:00 2001
From: Chris Hofstaedtler <zeha@debian.org>
Date: Tue, 23 Jun 2020 23:24:33 +0200
Subject: [PATCH] create_fstab_header: add systemd hints

systemd reads /etc/fstab to generate mount units. They become stale
in-memory configuration after fstab is changed, and this can lead
to nasty surprises.

Example: systemd might unmount newly mounted filesystems, if
/etc/fstab had conflicting info previously.

Signed-off-by: Chris Hofstaedtler <zeha@debian.org>
---
 finish.d/create_fstab_header | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/finish.d/create_fstab_header b/finish.d/create_fstab_header
index e99fa5e..560087a 100755
--- a/finish.d/create_fstab_header
+++ b/finish.d/create_fstab_header
@@ -11,6 +11,9 @@ case `udpkg --print-os` in
 # device; this may be used with UUID= as a more robust way to name devices
 # that works even if disks are added and removed. See fstab(5).
 #
+# systemd generates mount units based on this file, see systemd.mount(5).
+# Please run 'systemctl daemon-reload' after making changes here.
+#
 EOF
 		printf "%-15s %-15s %-7s %-15s %-7s %s\n" '# <file system>' '<mount point>' '<type>' '<options>' '<dump>' '<pass>' >> /target/etc/fstab
 	;;
-- 
2.27.0