How to Identify a particular IRP from upper drivers in a filter driver

Hi,

I have a filter driver, which is layered above the
disk class driver. It filters all read and write IRPs
from the upper drivers. I have a upper driver, which
creates Read/Write IRPs and pass down to the disk
driver. My filter driver needs to identify which
read/write IRPs are from my upper driver. Please
help if you have any information on how to do this.

Thanks
Robert