Subject: Re: [PATCH] vmsplice: relax alignement requirements for SPLICE_F_GIFT

From: Jens Axboe <[email-masked]>
Date: Fri, 20 Apr 2012 10:19:54 +0200

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.

-- 
Jens Axboe