Chapter 11 - IoGetDeviceObjectPointer for some devices return a wrong device object?!

[subvert0r]

I am not sure what the problem is, but for volmgr devices, such as \device\harddiskvolumeX, IoGetDeviceObjectPointer returns a FltMgr device!

I know that IoGetDeviceObjectPointer returns the top most device in the stack, but FltMgr is on a whole different stack? At least based on !stack and device tree, FltMgr devices are completely on a different stack compared to the harddiskvolume devices, so is this normal or..? Any better way to do this other than using IoGetDeviceObjectPointer?