Merge ~xnox/casper:try-fix-unmount-cdrom into casper:main

[Dimitri John Ledkov]

your welcome

[Dimitri John Ledkov (xnox)]

adding desktop people for visibility to ensure that if this lands and explodes again, at least everyone is bracing for impact =)

[Michael Hudson-Doyle (mwhudson)]

Well this does seem to help, despite all the hackery. I haven't tested a desktop image but /cdrom is mounted as expected for a server image and there are no complaints about trying to unmount it in the journal. Is there anything else I should be looking for?

[Michael Hudson-Doyle (mwhudson)]

Hmm I still get the unmount failures on reboot, did you expect/hope that this would fix those?

[Michael Hudson-Doyle (mwhudson)]

I built this into an ISO (properly, unlike my last comment) and it helps on boot but casper-stop now runs after /cdrom is unmounted and so doesn't prompt to remove media when it should. xnox thinks this can be fixed by correcting dependencies but I wonder if we should instead fix this by having the code that mounts /cdrom record in /run whether casper-stop should prompt and then deleting 90% of casper-stop. Possibly do the first for SRU and then the second for new releases?

[Michael Hudson-Doyle (mwhudson)]

My ISO is here if anyone wants to test https://people.canonical.com/~mwh/casper-cdrom.iso

diff --git a/scripts/casper-bottom/25disable_cdrom.mount b/scripts/casper-bottom/25disable_cdrom.mount
index c02f4cd..a3741df 100755
--- a/scripts/casper-bottom/25disable_cdrom.mount
+++ b/scripts/casper-bottom/25disable_cdrom.mount
@@ -15,4 +15,30 @@ prereqs)
        ;;
 esac
 
-ln -s /dev/null /root/lib/systemd/system/cdrom.mount
+# Disable bounding mount points to sr0 device
+# As there is no way to make sr0 be active&plugged on cold boot
+# Thus systemd always tries to unmount cdrom.mount even before udev
+# coldplug got processed
+sed -i '/SYSTEMD_MOUNT_DEVICE_BOUND/d' /lib/udev/rules.d/60-cdrom_id.rules /root/lib/udev/rules.d/60-cdrom_id.rules
+
+# Correct udevadm settings
+udevadm trigger /dev/sr0 || :
+
+# Make cdrom.mount not have defaultdependencies, thus it should not be
+# unmounted on shutdown. And make sure that it is ordered after
+# casper.service, to not be unmounted before casper service shows the
+# RIM & Reboot message.
+
+# And we specify BindsTo= to nothing, again, despite udev rule, as it
+# is not enough on the server iso for some reason. Weird.
+cat <<EOF >/root/lib/systemd/system/cdrom.mount
+[Unit]
+DefaultDependencies=no
+After=casper.service
+BindsTo=
+
+[Mount]
+Where=/cdrom
+What=/dev/sr0
+LazyUnmount=yes
+EOF