Merge PR #20516 into wip-sage-testing-20180407.023003

Merge PR #20516 into wip-sage-testing-20180407.023003

* refs/pull/20516/head:
	os/filestore: advertise vdo in filestore metadata
	os/filestore: implement thin provisioning utilization stats for VDO
	os/bluestore/KernelDevice: advertise vdo and physical_size in metadata
	os/bluestore/KernelDevice: implement thin utilization stats for VDO
	os/bluestore: hook to expose utilization of thinly-provisioned device
	common/blkdev: identify VDO devices beneath LVM
	common/blkdev: implement VDO helper functions

Reviewed-by: Josh Durgin <jdurgin@redhat.com>