probe-bcache - probe a bcache device
probe-bcache [ -o udev ] device
return UUID in udev style for invocation by udev rule as IMPORT{program}
Return UUID if device identified as bcache-formatted.
Only necessary until support for the bcache superblock is included in blkid; in the meantime, provides just enough functionality for a udev script to create the /dev/disk/by-uuid symlink.