How to trap read operation during the file copy?

NTFSD
1

I am developing a minifilter driver and have met a problem.

When I am copying 512 files(the size of each file is 1 byte), I have found that the read operatiion of the original file will not cause the IRP_MJ_READ sent to the driver.

I wonder how I can trap the read operatiion of the original file in my driver.

Thanks.

2

> When I am copying 512 files(the size of each file is 1 byte), I

have found that the read operatiion of the original file will not
cause the IRP_MJ_READ sent to the driver.

If the copying application does mapping of the file
and then WriteFile on the mapped pages, you will not receive
the read request if the file is already in the cache.

This will most probably happen also when you
run Notepad on a text file twice in a row.

L.

3

Hi Zezula,

I like your “filespy” tool.

I am developing a minifilter driver. If a file is already in the cache.
it is impossible that minifilter get a IRP_MJ_READ of that file, isn’t it?

Is The behavior of “mapping of the file” or “on the mapped pages” called
Fast I/O Operation ?

On Thu, 4 Jan 2007 15:20:45 +0100
Ladislav Zezula wrote:

> > When I am copying 512 files(the size of each file is 1 byte), I
> > have found that the read operatiion of the original file will not
> > cause the IRP_MJ_READ sent to the driver.
>
> If the copying application does mapping of the file
> and then WriteFile on the mapped pages, you will not receive
> the read request if the file is already in the cache.
>
> This will most probably happen also when you
> run Notepad on a text file twice in a row.
>
> L.
>
>
>
>
> —
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