Disk Filter Driver

NTDEV
1

I’m new to this device driving lark. I’m trying to write an upper filter
driver for a disk device. This is a WDM driver for Win 2000 / XP. For my
initial version the driver simply passes the IRP onto the next driver
(with a few exceptions). However when I attach the filter driver to the
device the volume on that disk disappears from “My Computer”. The disk
management utility shows the partition, but shows no drive letter next to
it. I can assign a drive letter via the disk management administrator tool
and explore it from there, but “My computer” still does not see it. The
log of IRPs and status responses shows no apparent problems. If I remove
the filter driver then the volume reappears. What could I possibly be
doing wrong?

2

You may not be letting certain IOCTLs through that you should. Your
filter should pass through, unchanged, any request that you explicitly
do not want to alter or complete.

xxxxx@pdmitchell.fsnet.co.uk wrote:

I’m new to this device driving lark. I’m trying to write an upper filter
driver for a disk device. This is a WDM driver for Win 2000 / XP. For my
initial version the driver simply passes the IRP onto the next driver
(with a few exceptions). However when I attach the filter driver to the
device the volume on that disk disappears from “My Computer”. The disk
management utility shows the partition, but shows no drive letter next to
it. I can assign a drive letter via the disk management administrator tool
and explore it from there, but “My computer” still does not see it. The
log of IRPs and status responses shows no apparent problems. If I remove
the filter driver then the volume reappears. What could I possibly be
doing wrong?

–
Nick Ryan (MVP for DDK)

3

I’ve checked and I am passing through all requests. Through the log file I
can see the system requesting all sorts of things including doing a read
of the boot sector and the partition table.

One thought I has was that perhaps the installation is wrong (via .INF
file). How should I be installing a filter driver if I am NOT installing a
function driver at the same time?

4

I expect you’re handling some IOCTLs incorrectly.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From:
To: “Windows System Software Developers Interest List”
Sent: Tuesday, September 02, 2003 4:27 AM
Subject: [ntdev] Disk Filter Driver

> I’m new to this device driving lark. I’m trying to write an upper filter
> driver for a disk device. This is a WDM driver for Win 2000 / XP. For my
> initial version the driver simply passes the IRP onto the next driver
> (with a few exceptions). However when I attach the filter driver to the
> device the volume on that disk disappears from “My Computer”. The disk
> management utility shows the partition, but shows no drive letter next to
> it. I can assign a drive letter via the disk management administrator tool
> and explore it from there, but “My computer” still does not see it. The
> log of IRPs and status responses shows no apparent problems. If I remove
> the filter driver then the volume reappears. What could I possibly be
> doing wrong?
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
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