Description

Installation fails because active LVM partitions are overwritten and result in a problematic system state, which can either happen when the disk is specified explicitly or when the -s flag searches for the smallest unmounted partition but does not take LVM into account.

Impact

Either a reboot to retry installation is needed, or before running flatcar-install, a manual removal of active LVM partitions (something like lvchange -an /dev/mapper/vg*).

Environment and steps to reproduce

1. Set-up: Boot via PXE on a system that has LVM partitions on the smallest disk. Check that Flatcar already activated the LVM partitions (entries under /dev/mapper/)
2. Task: run flatcar-install -s
3. Error: installation fails

Expected behavior
The -s flag in general should become aware of active LVM partitions and filter them like mounts are filtered. However, to not offload the LVM deactivation to the user, a new flag --remove-lvm should allow to deactivate LVM all partitions before even running the -s filtering logic.

Additional information
Also partly tracked in #249 coreos/bugs#152 #120