[Bug 1876506] Re: eoan to focal upgrade hangs when lvm snapshot is present

[Steve Langasek]

** Package changed: ubuntu-release-upgrader (Ubuntu) => grub2 (Ubuntu)

** Changed in: grub2 (Ubuntu Focal)
    Milestone: None => ubuntu-20.04.1

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https://bugs.launchpad.net/bugs/1876506

Title:
  eoan to focal upgrade hangs when lvm snapshot is present

Status in grub2 package in Ubuntu:
  New
Status in grub2 source package in Focal:
  New

Bug description:
  When upgrading from 19.10 (w/ LVM + encypted disks) to 20.04, the
  installer hangs when trying to probe an LVM snapshot volume created
  before the upgrade.

  Steps to reproduce:

  lvcreate -s -L 20G -n preupgrade /dev/vgubuntu/root 
  do-release-upgrade -d

  The installer will hang after the following message:

  /usr/sbin/grub-probe: error: unknown filesystem.
  Found Ubuntu 19.10 (19.10) on /dev/mapper/vgubuntu-preupgrade
  done

  Resolution:

  Killing the grub-mount process which is probing the LVM snapshot seems
  to unhang the installer and allow the upgrade to complete without
  issue.

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