Query of Upper volume filter driver

NTFSD
1

Hi all,
I am writing Volume Upper Filter Driver.
I want to know that when it receives the IRP_MJ_READ the
IrpSp->Parameter.Write.StartingOffset contains what ?

whether the startingoffset above means byte offset of data to be read
relative to the start of the particular volume.

does it have any relation with the cluster number relative to volume?

I am a newbee so do reply me

Rakesh Thakur

2

> I want to know that when it receives the IRP_MJ_READ the

IrpSp->Parameter.Write.StartingOffset contains what ?
You mean IrpSp->Parameters.Read.ByteOffset.QuadPart, not …Write…, of
course?

whether the startingoffset above means byte offset of data to be read
relative to the start of the particular volume.
Yes.
Things are a bit more complicated for a disk filter, but yours is a volume
filter.

Alex Shvedov

----- Original Message -----
From: “rakesh thakur”
To: “Windows File Systems Devs Interest List”
Sent: Friday, April 29, 2005 10:53 AM
Subject: [ntfsd] Query of Upper volume filter driver

Hi all,
I am writing Volume Upper Filter Driver.
I want to know that when it receives the IRP_MJ_READ the
IrpSp->Parameter.Write.StartingOffset contains what ?

whether the startingoffset above means byte offset of data to be read
relative to the start of the particular volume.

does it have any relation with the cluster number relative to volume?

I am a newbee so do reply me

Rakesh Thakur

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https://www.osronline.com/article.cfm?id=17

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3

Hi,

For both read and write, you get the logical byte offset from start of
the volume, which should be a multiple of sector size.

thanks,
Hrishikesh.

On 4/29/05, rakesh thakur wrote:
> Hi all,
> I am writing Volume Upper Filter Driver.
> I want to know that when it receives the IRP_MJ_READ the
> IrpSp->Parameter.Write.StartingOffset contains what ?
>
> whether the startingoffset above means byte offset of data to be read
> relative to the start of the particular volume.
>
> does it have any relation with the cluster number relative to volume?
>
> I am a newbee so do reply me
>
> Rakesh Thakur
>
> —
> Questions? First check the IFS FAQ at https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

4

Thanks For UR previos reply.

What could be the Maximum Length(in bytes) for a single Read/ write
operation issued from file System to Volume Driver .

//i.e.IrpSp->Parameter.Write.Length=??(MAX_VALUE)? //

Could a single Write / Read operation start from one cluster and can
end on another cluster ?

Thanks

On 4/29/05, Hrishikesh Vidwans wrote:
> Hi,
>
> For both read and write, you get the logical byte offset from start of
> the volume, which should be a multiple of sector size.
>
> thanks,
> Hrishikesh.
>
>
> On 4/29/05, rakesh thakur wrote:
> > Hi all,
> > I am writing Volume Upper Filter Driver.
> > I want to know that when it receives the IRP_MJ_READ the
> > IrpSp->Parameter.Write.StartingOffset contains what ?
> >
> > whether the startingoffset above means byte offset of data to be read
> > relative to the start of the particular volume.
> >
> > does it have any relation with the cluster number relative to volume?
> >
> > I am a newbee so do reply me
> >
> > Rakesh Thakur
> >
> > —
> > Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
> >
> > You are currently subscribed to ntfsd as: unknown lmsubst tag argument:
> ‘’
> > To unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
> —
> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

5

Hello,
Multiple cluster read/writes are possible. I would suggest, not to constrain
your driver to any specific maximum value. Applications also can send
arbitrary large reads/writes if they are using DASD Ios. The only constrain
that you can safely assume is that the read/write request will always start
at sector (not cluster) boundary and length will be in multiples of sector
size.
Thanks
-Kiran

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of rakesh thakur
Sent: Monday, May 02, 2005 5:08 PM
To: Windows File Systems Devs Interest List
Subject: Re:[ntfsd] Query of Upper volume filter driver

Thanks For UR previos reply.

What could be the Maximum Length(in bytes) for a single Read/ write
operation issued from file System to Volume Driver .

//i.e.IrpSp->Parameter.Write.Length=??(MAX_VALUE)? //

Could a single Write / Read operation start from one cluster and can end on
another cluster ?

Thanks

On 4/29/05, Hrishikesh Vidwans wrote:
> Hi,
>
> For both read and write, you get the logical byte offset from start of
> the volume, which should be a multiple of sector size.
>
> thanks,
> Hrishikesh.
>
>
> On 4/29/05, rakesh thakur wrote:
> > Hi all,
> > I am writing Volume Upper Filter Driver.
> > I want to know that when it receives the IRP_MJ_READ the
> > IrpSp->Parameter.Write.StartingOffset contains what ?
> >
> > whether the startingoffset above means byte offset of data to be
> > read relative to the start of the particular volume.
> >
> > does it have any relation with the cluster number relative to volume?
> >
> > I am a newbee so do reply me
> >
> > Rakesh Thakur
> >
> > —
> > Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
> >
> > You are currently subscribed to ntfsd as: unknown lmsubst tag argument:
> ‘’
> > To unsubscribe send a blank email to
> > xxxxx@lists.osr.com
> >
>
> —
> Questions? First check the IFS FAQ at
> https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>

—
Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: unknown lmsubst tag argument: ‘’
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