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

[mike]

Heitor,

I hate an unsolved puzzle. I do remember that I thought the cause of the problem was that GRUB/LVM only handled linear LVM partitions. I spent quite some time yesterday trying to verify that. but I could find no mention of that now or in the past (luckily I can read lying down on my couch).
I ran a quick test and I found that (as I found originally) if you let the following tests run they will add an entry for a LVM thick snapshot, but the label will say it is an entry for the snapshot, but the boot command ( linux ... root=...) will reference the base partition.
In the meantime I found another weird problem. I changed the name of the base lvm (lvrename), which lvs confirmed, but when I ran update-grub the entry for the snapshot referred to the original name of the base lvm in the "linux  root=" command!?! 

this was in 1.79ubuntu2

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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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