xfs
[Top] [All Lists]

Re: [PATCH] xfs_io: fix random pread/pwrite to honor offset

To: Eric Sandeen <sandeen@xxxxxxxxxxx>
Subject: Re: [PATCH] xfs_io: fix random pread/pwrite to honor offset
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 11 Apr 2014 14:48:44 +1000
Cc: Mark Tinguely <tinguely@xxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <5345B3AD.5020805@xxxxxxxxxxx>
References: <53459C4E.9030902@xxxxxxxxxxx> <5345B209.5040906@xxxxxxx> <5345B3AD.5020805@xxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
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@xxxxxxxxxx>
> >> ---
....
> > 
> > Looks like this was introduced in:
> > commit 8fb2237e65555ff540e8b6108ffccfffefe239ac
> > Author: Nathan Scott <nathans@xxxxxxx>
> > 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@xxxxxxxxxxxxx

<Prev in Thread] Current Thread [Next in Thread>