passing filter manager contexts

The Filter Manager developer’s guide states that contexts can’t be
retrieved at DPC so if you need one in post-op you may need to pass it
to your post-op callback. The next paragraph then says that a
mini-filter shouldn’t hold onto a context across operations. What is
meant by ‘operations’ in this case? Are we talking about system calls or
pre and post ops? If it’s the latter then the first two statements seem
contradictory.

Is it best to get the context in the pre-op and pass it using the
completion context to your post-op? You’d then have to release it in
your post-op routine - I noticed that the release routine can be called
at DPC.

Jerry

An operation is a system call, e.g., create, read, write, close, etc.

The intention is that you get the context in the pre-operation callback
and pass it to your post-operation callback, and then release the
context in your post-operation callback when you are finished with it.

Molly Brown
Microsoft Corporation

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 Kelley, Jerry
Sent: Friday, April 16, 2004 6:46 AM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] passing filter manager contexts

The Filter Manager developer’s guide states that contexts can’t be
retrieved at DPC so if you need one in post-op you may need to pass it
to your post-op callback. The next paragraph then says that a
mini-filter shouldn’t hold onto a context across operations. What is
meant by ‘operations’ in this case? Are we talking about system calls or
pre and post ops? If it’s the latter then the first two statements seem
contradictory.

Is it best to get the context in the pre-op and pass it using the
completion context to your post-op? You’d then have to release it in
your post-op routine - I noticed that the release routine can be called
at DPC.

Jerry


Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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