linux-kernel - Re: [RFC][PATCH 2/5] pagemap: use PAGE_MASK/PAGE

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Date:	Wed, 08 Aug 2007 08:11:34 -0700
From:	Dave Hansen <haveblue@...ibm.com>
To:	Christian Ehrhardt <Christian_Ehrhardt@...ua.de>
Cc:	linux-kernel@...r.kernel.org, serue@...ibm.com
Subject: Re: [RFC][PATCH 2/5] pagemap: use PAGE_MASK/PAGE_ALIGN()

On Wed, 2007-08-08 at 09:38 +0200, Christian Ehrhardt wrote:
> 
> >       ret = -ENOMEM;
> > -     uaddr = (unsigned long)buf & ~(PAGE_SIZE-1);
> > +     uaddr = (unsigned long)buf & PAGE_MASK;
> >       uend = (unsigned long)(buf + count);
> > -     pagecount = (uend - uaddr + PAGE_SIZE-1) / PAGE_SIZE;
> > +     pagecount = (uend - PAGE_ALIGN(uaddr)) / PAGE_SIZE;
> 
> Unless I'm missing something the PAGE_ALIGN as ist stands is now a NOP
> because uaddr is already page aligned. You probably wanted to
> PAGE_ALIGN(uend). However, this will likely add an additional instruction
> to the generated code. 

Yeah, I aligned the wrong thing.  I'll fix that up.

-- Dave

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