Re: [PATCH] vmsplice: relax alignement requirements forSPLICE_F_GIFT

From: Eric Dumazet
Date: Fri Apr 20 2012 - 04:35:16 EST

On Fri, 2012-04-20 at 10:19 +0200, Jens Axboe wrote:
> On Wed, Apr 04 2012, Eric Dumazet wrote:
> > It seems there is no fundamental reason to limit vmsplice()
> > SPLICE_F_GIFT to page aligned chunks.
> >
> > All helpers are prepared to cope with offsets in page.
> >
> > This limitation makes vmsplice() API very impractical in the zero-copy
> > land.
> Sorry for the slow reply on this one. It's been a long time since I
> wrote that code... If I recall correctly, the reason it currently
> requires alignment, is that a gifted page is no longer yours, by
> definition. So the alignment check was to ensure that we gift full
> pages. But if the caller screws that up, I guess it's the callers
> problem and it's a shame to limit the API in this way.
> I will apply it for 3.5.

Thanks Jens

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