[Bug 1987679] Re: os-prober leaves filesystems (lvm-thin, lvm snap) mounted

[mike]

I'm sorry, I have been responding to the mails I have received about
this, trying to clarify things, but they have not been added to the bug.

You may want to verify, but I believe that if grub-probe FAILS (returns an error) it is because the the file system is not one that grub can deal with (one case I found was a lvm snapshot which grub cannot boot from).
Contrary to Heitor's comment that "we we *do* want the script to continue in some of these cases" it is pointless to continue on and execute mounted probes and we don't want an entry in the cfg (as it will be unbootable)

simply add

    + debug "un-mountable using GRUB, bad filesystem?"
    + mount=
    + do_unmount

 The "do_unmount" is optional as it is forced at the end of the script,
the "mount=" signals not to do any more tests

cleans up the bug (leaving filesystems mounted) and "does no harm"

When I was playing around (testing) this the error messages from grub-probe were confusing/undecipherable.
Depending on the test regime and any added test cases for this problem (the other file system that caused problems was a system on a thin-lvm), I might suggest losing the error messages from grub-probe (2>/dev/null) and adding an error message "system found on an partition unbootable by GRUB" as I believe that is the root cause of this problem

Hope this helps

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Title:
  os-prober leaves filesystems (lvm-thin, lvm snap) mounted

Status in os-prober package in Ubuntu:
  In Progress
Status in os-prober source package in Focal:
  In Progress
Status in os-prober source package in Jammy:
  In Progress
Status in os-prober source package in Kinetic:
  Won't Fix
Status in os-prober source package in Noble:
  In Progress
Status in os-prober source package in Oracular:
  In Progress
Status in os-prober source package in Plucky:
  In Progress

Bug description:
  If one happens to have by accident (or on purpose) a thick LVM snapshot, or a thin-LV with a copy of a system on it, update-grub reports
  /sbin/grub-probe: error: unknown filesystem.
  Found Ubuntu 22.04.1 LTS on /dev/mapper/vgxubuntu-s22.04
  and
  /sbin/grub-probe: error: disk `lvmid/X7waXv-rMDA-5fQA-aw6l-ei1I-8Gz3-pQl3lr/k3Ze1u-Mfwc-pxUt-7fXa-FjSZ-7IkX-HAxf3b' not found.
  Found Ubuntu 22.04.1 LTS (22.04) on /dev/mapper/vgxubuntu-XR22.04.1U

  and leaves the systems mounted rw on /var/lib/os-prober/mount.
  On subsequent invocations update-grub spews out multiple
  mdir: failed to remove '/var/lib/os-prober/mount': Device or resource busy

  I'm pretty sure this also causes a new install to hang (though a
  power-reset seems to load the new system - not sure if it is complete
  or not.)

  The missing umounts should be relatively easy to fix, but the thick
  snapshot error is particularly vague as most users (I think) would
  take the "unknown filesystem" to refer to the previous entry.

  I have been playing with grub2-common-2.06-2ubuntu7 on xubuntu
  22.04.1, though I am sure this has been around a while

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