Comment # 6 on bug 912170 from Jeff Mahoney

The problem that patch fixes is that btrfs caches the first name used to refer
to a device. So when systemd calls btrfs ready on the device, it caches
/dev/dm-# instead of the named LVM volume. That results in things like 'mount'
and 'df' showing the /dev/dm-# name instead of the LVM volume name. There was a
separate bug for this filed (bsc#888215)

The patch provided is just reverting that patch. So, any fix needs to also
address bsc#888215. It's probably an ordering issue that the file system mount
attempt shouldn't happen before the device mapper nodes are created.