How to find the target device for a class filter driver

I'm looking into IRP_MJ_SCSI (IRP_MJ_INTERNAL_DEVICE_CONTROL) calls
for the type of SRBs. I can see a whole bunch of SCSIOP_READ and
SCSIOP_WRITE when running the Check Disk tool on the drive that is not
the primary master.

But how can I tell which device the SRB is directed to if if it a
DiskDrive class filter driver. I have many devices that belong to the
DiskDrive class and I only want to care about SRBs directed to only
one of my hard drives.

I looked at the SRB's PathId, TargetId, and Lun and they are always
zero.
I tried getting info using IOCTL_STORAGE_GET_DEVICE_NUMBER but I get
NOT_SUPPORTED.

The ReferenceCount field in the DEVICE_OBJECT struct is always 0.

I can see under the registy that I have 3 instances of the driver
loaded.

BTW, my driver is based on DiskPerf from the 2000 DDK.

 

Great! ... So this would work if I have an upper filter class driver.
How would I do it for a lower filter driver or for a bus driver if
IOCTL_STORAGE_* are only implemented by the class drivers.

 

IOCTL_SCSI_GET_ADDRESS should be handled by the bus driver

As long as you are talking WDM, you are ok. Note this is something
that has changed and under NT 4, the class driver handled
IOCTL_SCSI_GET_ADDRESS so you would have to send this ioctl to the top
of the stack in that instance.

Not only is it "possible", it's just a simple call to
IoGetAttachedDeviceReference. I think it is a bad idea to bypass
filter drivers. When you make filters above or below you blind to
IRP's originating in your driver, the filters won't be able to achieve
what they are trying to do like performance measurements, logging,
synchronization, or any other value add. I would hope in the future
driver verifier is enhanced to fail drivers that get a private IOCTL
from a user mode app and in turn send something straight to the PDO
for instance.