Finding device name for a drive letter

Is there a simple way to go from the C:, D:, etc. to the specific device
driver name that is hosting that partition? I can do it for a disk class
driver that only exports a single partition, but I am having a problem
finding a match. I would prefer solutions for both an application and the
device driver to find what partitions and drive letters exist on that
driver’s device object. It may be getting late and I will find it tomorrow,
but any help appreciated.