FileObject and IRP_MJ_CLEANUP

NTDEV
1

Hello,

Is the file object still valid when a filter driver gets an
IRP_MJ_CLEANUP?

I store the file object in a hash and when
I get IRP_MJ_CLEANUP I try to remove the FileObject from
the hash. I dont have any references to the file object.
Once in a while when I try to remove the file object from
the hash, it dumps core. Examining the fobject in windbag,
I see that it is invalid.

If I set my own reference to the Fileobject, will I get an
MJ CLEANUP before I deref the Fileobject or until the ref count goes to
zero?

Thanks.

–El Haddi

2

El Haddi

You might have done better with this question in ntfsd. However, afaik the
file object should indeed be valid when your filter driver receives
IRP_MJ_CLEANUP. Remember, it is IRP_MJ_CLOSE which hails the end of the
observabe lifecycle of the file object, and IRP_MJ_CLEANUP means that the
handle count has become zero.

Cheers
Lyndon

wrote in message news:xxxxx@ntdev…
>
>
> Hello,
>
> Is the file object still valid when a filter driver gets an
> IRP_MJ_CLEANUP?
>
> I store the file object in a hash and when
> I get IRP_MJ_CLEANUP I try to remove the FileObject from
> the hash. I dont have any references to the file object.
> Once in a while when I try to remove the file object from
> the hash, it dumps core. Examining the fobject in windbag,
> I see that it is invalid.
>
> If I set my own reference to the Fileobject, will I get an
> MJ CLEANUP before I deref the Fileobject or until the ref count goes to
> zero?
>
>
> Thanks.
>
> --El Haddi
>
>

3

xxxxx@constantdata.com wrote:

Hello,

Is the file object still valid when a filter driver gets an
IRP_MJ_CLEANUP?

Yes. It is valid until your DispatchClose routine exits.

I store the file object in a hash and when
I get IRP_MJ_CLEANUP I try to remove the FileObject from
the hash. I dont have any references to the file object.
Once in a while when I try to remove the file object from
the hash, it dumps core. Examining the fobject in windbag,
I see that it is invalid.

If I set my own reference to the Fileobject, will I get an
MJ CLEANUP before I deref the Fileobject or until the ref count goes to
zero?

Thanks.

–El Haddi

Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256

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4

> Is the file object still valid when a filter driver gets an

IRP_MJ_CLEANUP?

Yes. It is still valid in CLOSE too, and destroyed just on CLOSE completion.

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