zfsutils-linux breaks upgrade to 19.10?

[John Reid]

Hi all,

I have a slightly unusual setup which might have broken the upgrade process. The upgrade broke in the same way on both
my desktop and laptop which both have a similar zfs setup, but not on my htpc which doesn't have any zfs volumes on it.
The short version is that it looks like the upgrade process breaks if zfs is used for home directories :(

>From /var/log/dist-upgrade/apt-term.log:
   Setting up zfsutils-linux (0.8.1-1ubuntu14) ...
   Installing new version of config file /etc/zfs/zfs-functions ...
   zfs-import-scan.service is a disabled or a static unit not running, not starting it.
   Job for zfs-mount.service failed because the control process exited with error code.
   See "systemctl status zfs-mount.service" and "journalctl -xe" for details.
   invoke-rc.d: initscript zfs-mount, action "restart" failed.
   ● zfs-mount.service - Mount ZFS filesystems
      Loaded: loaded (/lib/systemd/system/zfs-mount.service; enabled; vendor preset: enabled)
      Active: failed (Result: exit-code) since Fri 2019-10-25 18:44:58 AEDT; 9ms ago
        Docs: man:zfs(8)
     Process: 3571 ExecStart=/sbin/zfs mount -a (code=exited, status=1/FAILURE)
    Main PID: 3571 (code=exited, status=1/FAILURE)

   Oct 25 18:44:58 episiarch systemd[1]: Starting Mount ZFS filesystems...
   Oct 25 18:44:58 episiarch zfs[3571]: cannot mount '/home': directory is not empty
   Oct 25 18:44:58 episiarch systemd[1]: zfs-mount.service: Main process exited, code=exited, status=1/FAILURE
   Oct 25 18:44:58 episiarch systemd[1]: zfs-mount.service: Failed with result 'exit-code'.
   Oct 25 18:44:58 episiarch systemd[1]: Failed to start Mount ZFS filesystems.
   dpkg: error processing package zfsutils-linux (--configure):
    installed zfsutils-linux package post-installation script subprocess returned error exit status 1

Upon reboot the zfs home directories are not mounted, and a new directory tree has been created on /home with all
directories empty and owned by root. I don't know what is doing this or at what stage in the upgrade, but I suspect this
is the cause of the problem.

Removing the /home directory and restarting the zfs-mount service seems to fix this (although prior to restarting the
service I also performed a zpool upgrade - don't know what (if any) effect this has). I can't remember for certain, but
I think the /data directories were mounted correctly:

   $ zfs list
   NAME                                   USED  AVAIL     REFER  MOUNTPOINT
   zfstank.pool1                         2.55T   875G      140K  /mnt/pool/zfs/zfstank.pool1
   zfstank.pool1/data                    2.42T   875G      221K  /data
   zfstank.pool1/data/...
   zfstank.pool1/home                     132G   875G      151K  /home
   zfstank.pool1/home/username            85.0G  875G      53.8G /home/username

Regards,
John