linux-kernel - Re: [PATCH 3/5] pagemap: Make pagemap_read enforce reading in multiples of 8

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Message-Id: <1212682885.3953.183.camel@calx>
Date:	Thu, 05 Jun 2008 11:21:25 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Thomas Tuttle <ttuttle@...gle.com>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] pagemap: Make pagemap_read enforce reading in
	multiples of 8


On Thu, 2008-06-05 at 12:14 -0400, Thomas Tuttle wrote:
> On Thu, Jun 5, 2008 at 12:09 PM, Matt Mackall <mpm@...enic.com> wrote:
> > Yes, I got that, I'm just mathematically impaired this morning. Read
> > that as "when someone tries to do a *20* byte read, do a 16-byte read.."
> > In other words, round down to the nearest multiple of 8.
> 
> Oh.  I would seriously question doing that, because it would allow
> reads that are improperly split up to fail silently.  What happens if
> someone tries to read 40 bytes, and (for some reason) it gets split
> into two 20-byte reads?  Instead of "12345" they'll get "12.34."
> (where . is 4 zero or garbage bytes).  I'd rather they get an error.

I suppose you're right, people usually don't check those return codes.

-- 
Mathematics is the supreme nostalgia of our time.

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