Hi,
On bugzilla there was a brief discussion on how to reduce the number of
blkid calls during udev rules processing:
https://bugzilla.redhat.com/show_bug.cgi?id=1004693
The general idea was to rely on earlier calls to blkid instead of having
later rules calling blkid themselves. Specifically for bcache this meant
relying on 13-dm-disk.rules and 60-persistent-storage-rules, which all
worked fine until...
...until I tested stacking bcache on top of raid (md).