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From: Dave Chinner <david@fromorbit.com>
To: Eric Sandeen <sandeen@sandeen.net>
Cc: Mark Tinguely <tinguely@sgi.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs_io: fix random pread/pwrite to honor offset
Date: Fri, 11 Apr 2014 14:48:44 +1000	[thread overview]
Message-ID: <20140411044844.GH15995@dastard> (raw)
In-Reply-To: <5345B3AD.5020805@sandeen.net>

On Wed, Apr 09, 2014 at 03:55:09PM -0500, Eric Sandeen wrote:
> On 4/9/14, 3:48 PM, Mark Tinguely wrote:
> > On 04/09/14 14:15, Eric Sandeen wrote:
> >> xfs_io's pread & pwrite claim to support a random IO mode
> >> where it will do random IOs between offset & offset+len.
> >>
> >> However, offset was ignored, and we did the IOs between 0
> >> and len instead.
> >>
> >> Clang caught this by pointing out that the calculated/normalized
> >> "offset" variable was never read.
> >>
> >> (NB: If the range is larger than RAND_MAX, these functions don't
> >> work, but that's always been true, so I'll leave it for another
> >> day...)
> >>
> >> Signed-off-by: Eric Sandeen<sandeen@redhat.com>
> >> ---
....
> > 
> > Looks like this was introduced in:
> > commit 8fb2237e65555ff540e8b6108ffccfffefe239ac
> > Author: Nathan Scott <nathans@sgi.com>
> > Date:   Fri Nov 11 14:25:18 2005 +0000
> > 
> > Provide further debugging options and tweaks for analysing the read/write paths.
> > Merge of master-melb:xfs-cmds:24372a by kenmcd.
> > 
> >  ---
> > 
> > If it was broken for 8.5 years, I think it could be removed.
> 
> Eh, could, or we could fix it.  :)  I suppose this means it needs a test... :/

And document it ;)

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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      reply	other threads:[~2014-04-11  4:49 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-09 19:15 [PATCH] xfs_io: fix random pread/pwrite to honor offset Eric Sandeen
2014-04-09 20:48 ` Mark Tinguely
2014-04-09 20:55   ` Eric Sandeen
2014-04-11  4:48     ` Dave Chinner [this message]

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