For testing/development, sure you can unload - when it crashes you just reboot.
However, I can think of at least four reasons why this cannot work safely:
(1) Work queue items. You don’t know what the state of these are, they can’t be removed safely. Actually, the same thing applies to timers, but most filters don’t use them.
(2) Other filters. Once another filter loads on top of you an unload by you will leave the system in a highly unstable state.
(3) SRV. This delightful part of the OS saves copies of your fast I/O entry points in a private (per file) data structure. So even if you unload, it will send future requests to your former entry points.
(4) In-progress I/O operations. This is something people usually rectify by keeping a count, but it is another issue.
What we’ve done for years is split our filter drivers into pieces: one piece that does the filtering and the other piece (a “buddy driver”) that implements the functionality. You can load/unload the buddy driver so long as you build the filter piece to handle the various situations where the buddy driver is present, absent, loading, and unloading.
Filter Manager operates similarly to this model, and should allow you to deregister/unload.
Regards,
Tony
Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com
-----Original Message-----
From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of kedar n
Sent: Thursday, March 18, 2004 12:26 AM
To: ntfsd redirect
Subject: [ntfsd] Unloading File system filter driver
Hi All,
Is it possible for an File system filter driver to unload itself from the
file system stack.
Thanks,
Kedar.
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Questions? First check the IFS FAQ at https://www.osronline.com/article.cfm?id=17
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