[ceph-users] one-liner getting block device from mounted osd

I have a optimize script that I run after the reboot of a ceph node. It sets among other things /sys/block/sdg/queue/read_ahead_kb and /sys/block/sdg/queue/nr_requests of block devices being used for osd's. Normally I am using the mount command to discover these but with the tmpfs and ceph-volume this does not work. Is anyone able to share a simple onliner getting from osd's the used block devices? Eg from both types at the same time. Or do I really need to traverse this block -> /dev/mapper/... ?