Suppose that a file filter driver has an Unload routine. Assume that the filter will provide some fast i/o processing, and it might take some time to process ( not to hardware ) but some in-memory execution time.
Now how likely it is that the filter could be unloaded ( and unmapped ) while it is executing some fast i/o path ?
In other words ( while not in the IRP path ) is there any referenced mechanism that would prevent I/O Mgr from issueing Unload ? Have not seen or remember any place that mention this specific behavior.
-pro
Only FltMgr-based FS filters support unload, and I think FltMgr has ways to solve this.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: Prokash Sinha
To: Windows File Systems Devs Interest List
Sent: Sunday, March 06, 2005 4:20 AM
Subject: [ntfsd] Legacy question
Suppose that a file filter driver has an Unload routine. Assume that the filter will provide some fast i/o processing, and it might take some time to process ( not to hardware ) but some in-memory execution time.
Now how likely it is that the filter could be unloaded ( and unmapped ) while it is executing some fast i/o path ?
In other words ( while not in the IRP path ) is there any referenced mechanism that would prevent I/O Mgr from issueing Unload ? Have not seen or remember any place that mention this specific behavior.
-pro
Questions? First check the IFS FAQ at https://www.osronline.com/article.cfm?id=17
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Thanks.
-pro
----- Original Message -----
From: Maxim S. Shatskih
To: Windows File Systems Devs Interest List
Sent: Saturday, March 05, 2005 10:44 PM
Subject: Re: [ntfsd] Legacy question
Only FltMgr-based FS filters support unload, and I think FltMgr has ways to solve this.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
That is correct, legacy filters do not support being unloaded. This is because the IO Manager does not track outstanding operations and there is no synchronization to support it.
Minifilters can be unloaded because the filter manager (which itself can not be unloaded because it is a legacy filter) does the appropriate book keeping to make this safe.
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 Prokash Sinha
Sent: Sunday, March 06, 2005 7:01 AM
To: Windows File Systems Devs Interest List
Subject: Re: [ntfsd] Legacy question
Thanks.
-pro
----- Original Message -----
From: Maxim S. Shatskih
To: Windows File Systems Devs Interest List
Sent: Saturday, March 05, 2005 10:44 PM
Subject: Re: [ntfsd] Legacy question
??? Only FltMgr-based FS filters support unload, and I think FltMgr has ways to solve this.
?
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
?
?
Questions? First check the IFS FAQ at https://www.osronline.com/article.cfm?id=17
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