Filter Manager Write MDL

NTFSD
1

If I set the MDL during a PRE IRP_MF_WRITE callback, will the MDL still be
set during the POST IRP_MJ_WRITE callback?

Thanks,
Ken

2

No.? In post operation callbacks you will see the same parameters you saw in the preOperation callback.? This means if you change the MDL (or anything else) in your preOperation callback you will not see it in the postOperation parameters.?

Normally it would be your responsibility to pass any changed parameters that you care about to the postOperation callback via the pre-to-post context.? In this particular case we have an API that will help you called: FltGetSwappedBufferMdlAddress(). This will return the MDL you set in the postOperation.

Remember that if you are swapping MDLs you also need to keep the buffer in sync by either setting the correct buffer address or zeroing it out.

Neal Christiansen
Microsoft File System Filter Group Lead
This posting is provided "AS IS" with no warranties, and confers no rights.

From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of Ken Galipeau
Sent: Tuesday, March 30, 2004 2:48 PM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] Filter Manager Write MDL

If I set the MDL during a PRE IRP_MF_WRITE callback, will the MDL still be set during the POST IRP_MJ_WRITE callback?
?
Thanks,
Ken

Questions? First check the IFS FAQ at The NT Insider:Windows NT Virtual Memory (Part I)

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3

In this case I'm NOT swapping the buffers. Basically I'm asking if I call
FltLockUserBuffer (or just create my own MDL and lock down the original
buffer) in the PRE Op will the MDL still be set in the Post Op.

Thanks,
Ken

-----Original Message-----
From: Neal Christiansen [mailto:xxxxx@windows.microsoft.com]
Sent: Friday, April 02, 2004 3:23 PM
To: Windows File Systems Devs Interest List
Subject: RE: [ntfsd] Filter Manager Write MDL

No.? In post operation callbacks you will see the same parameters you saw in
the preOperation callback.? This means if you change the MDL (or anything
else) in your preOperation callback you will not see it in the postOperation
parameters.?

Normally it would be your responsibility to pass any changed parameters that
you care about to the postOperation callback via the pre-to-post context.?
In this particular case we have an API that will help you called:
FltGetSwappedBufferMdlAddress(). This will return the MDL you set in the
postOperation.

Remember that if you are swapping MDLs you also need to keep the buffer in
sync by either setting the correct buffer address or zeroing it out.

Neal Christiansen
Microsoft File System Filter Group Lead
This posting is provided "AS IS" with no warranties, and confers no rights.

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Ken Galipeau
Sent: Tuesday, March 30, 2004 2:48 PM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] Filter Manager Write MDL

If I set the MDL during a PRE IRP_MF_WRITE callback, will the MDL still be
set during the POST IRP_MJ_WRITE callback?
?
Thanks,
Ken

Questions? First check the IFS FAQ at

You are currently subscribed to ntfsd as: xxxxx@windows.microsoft.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

Questions? First check the IFS FAQ at

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