When testing a possible boot device, detect its partition type and
skip grub, LUKS, and LVM partitions. These aren't mountable as /boot,
this silences spurious exFAT errors.
In detect_boot_device, skip testing CONFIG_BOOT_DEV a second time if it
is found as a block device. This avoids doubling any errors shown from
checking this device, no sense trying it twice.
Refactor some logic to avoid duplication - extract
device_has_partitions and use it in detect_boot_device, extract
mount_possible_boot_device and use it instead of duplicating the logic.
Move find_lvm_vg_name() to /etc/functions.
Avoid mixing up similarly-named devices like 'nvme0n1'/'nvme0n10' or
'sda'/'sdaa' - it's probably unlikely that many devices will appear,
but looking for partitions in '/sys/class/block/<device>/' instead of
'/dev/' would avoid any collisions.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
a6228b9843