linux-kernel - Re: O_DIRECT splice from PCI-resident buffer to filesystem

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Date:	Wed, 3 Jun 2009 12:25:12 +0200
From:	Leon Woestenberg <leon.woestenberg@...il.com>
To:	Steve Rottinger <steve@...tek.com>
Cc:	linux-kernel@...r.kernel.org, leon@...ebranch.com
Subject: Re: O_DIRECT splice from PCI-resident buffer to filesystem

Steve,

On Fri, May 29, 2009 at 8:56 PM, Steve Rottinger <steve@...tek.com> wrote:
> After some work, and kernel hacking, and thanks to Jens'
> O_DIRECT/blockio splicing
> patch,  I have been successful in using splice to transfer data directly
> from a buffer
> resident on a PCI device to a raw disk partition, with zero copies. Great!
>

As we have no in-kernel character devices with splice_read/write
capability (other than /dev/null and maybe zero) *AFAIK*,
I would like to adapt my driver in staging/ to support splice_read()/write().

The difference is that my PCIe driver (altpciechdma.c) performs DMA
into a scattered set of pages. These pages are then
splice()d over.

Could you share the splice part of your driver for this purpose, so
that I can add splice_read() with less effort?

Regards,
-- 
Leon
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