Hi All,
In my filter driver I notice an issue I don’t understand. Can anyone tell
me what I am missing?
When I am creating a file from the command line using COPY CON “filename”.
I receive the CREATE, the writes etc. But in the end I do receive a
CLEANUP but I am missing the CLOSE.
Since I maintain a per FCB database on the files being filtered and am
reference counting using the OPEN’s and CLOSES this is a problem for me.
Can someone shed some light in this matter?
Best regards,
Wim Vervoorn
xxxxx@eltan.com
Hello there!
This reminds me of a strange thing hat I have observed while trying to
create my “hello world file system driver” (no, it is still not finished,
too much more pressing work):
With certain not-quite-valid responses from my driver I got CREATE-requests
for a file that I have tried to view with “type”, but the cleanup/close
requests came only when I exited the command window. (After desperately
trying to type that file for 50 times I gave up and exited the command line
window. The next couple of minutes the debug window scrolled with
cleanup/close requests…).
(Don’t know if this helps you, though)
Cheers,
Michael
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| | “Wim Vervoorn” |
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| To: “File Systems Developers” |
| cc: |
| Subject: [ntfsd] CREATE without CLOSE |
>--------------------------------------------------------------------------------------------------------------|
Hi All,
In my filter driver I notice an issue I don’t understand. Can anyone tell
me what I am missing?
When I am creating a file from the command line using COPY CON “filename”.
I receive the CREATE, the writes etc. But in the end I do receive a
CLEANUP but I am missing the CLOSE.
Since I maintain a per FCB database on the files being filtered and am
reference counting using the OPEN’s and CLOSES this is a problem for me.
Can someone shed some light in this matter?
Best regards,
Wim Vervoorn
xxxxx@eltan.com
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Many file systems employee a so called “delayed close” strategy. Indeed in
some cases it is
more efficient to delay close operations, and perform them , batched, at a
later time.
Also, sometimes Cc manager employee a quasy-similar strategy (closely linked
to lazy
write acitivity), which results in IRP_MJ_CLOSE for certain file objects
beeing delayed
for some time.
This behaviour is really not a problem for the purpose of reference
counting. You must ensure that when you free your per context tracking
structures, not only user references are gone, but also , all Cc and Mm
references to the on disk file stream are also gone. This is
problematic , because the so called stram file objects. You can have a
reference hold
through a stream file object for which you never seen any IRP_MJ_CREATE
operation.
For NT and 2k , check NT insider they have a nice article on reference
counting. For XP+,
and file systems which supports it , there is a nice built-in reference
counting mechanism.
Ciao, Dan
“Wim Vervoorn” wrote in message news:xxxxx@ntfsd…
>
> Hi All,
>
> In my filter driver I notice an issue I don’t understand. Can anyone tell
> me what I am missing?
>
> When I am creating a file from the command line using COPY CON “filename”.
> I receive the CREATE, the writes etc. But in the end I do receive a
> CLEANUP but I am missing the CLOSE.
>
> Since I maintain a per FCB database on the files being filtered and am
> reference counting using the OPEN’s and CLOSES this is a problem for me.
> Can someone shed some light in this matter?
>
> Best regards,
>
> Wim Vervoorn
>
> xxxxx@eltan.com
>
>