Bug#970534: systemd: `busctl introspect org.freedesktop.login1 /org/freedesktop/login1` fails

[Ansgar]

Michael Biebl writes:
> Am 18.09.20 um 09:07 schrieb Ansgar:
>> The following command fails (as a regular user):
>> 
>> +---
>> | $ busctl introspect org.freedesktop.login1 /org/freedesktop/login1
>> | Failed to get all properties on interface org.freedesktop.login1.Manager: Input/output error
>> +---
>
> Hm, interesting. The exact same command works for me.
> Has this system been rebooted after the 246.5 update? We don't restart
> logind as part of the upgrade process.

Yes, it also happened after a restart.

I assumed it was a permission problem (and `busctl` should show the
remaining information), but now looked into systemd-logind's journal and
see the following message whenever I try:

+---
| systemd-logind[1850]: Failed to probe partition scheme of "/dev/block/9:1": Input/output error
+---

/dev/block/9:1 is /dev/md1 which directly contains the /boot filesystem
and no partitions (I was also too lazy to properly set it up, so it is a
failed raid1 with only 1 device...).  `lsblk` shows:

+---
| ├─sde1               8:65   0   121M  0 part  /boot/efi
| ├─sde2               8:66   0   390M  0 part
| │ └─md1              9:1    0 389.7M  0 raid1 /boot
+---

So the `BootLoaderEntries` property which was the problem causes logind
to scan disks and give an error when it is unhappy with one of them.
That might be an additional bug, but `busctl` shouldn't give up and show
nothing either way.

Ansgar