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Date: Mon, 10 Oct 2016 17:07:45 +1100
From: Dave Chinner <david@...morbit.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: Davidlohr Bueso <dave@...olabs.net>,
Waiman Long <Waiman.Long@....com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
x86@...nel.org, linux-alpha@...r.kernel.org,
linux-ia64@...r.kernel.org, linux-s390@...r.kernel.org,
linux-arch@...r.kernel.org, linux-doc@...r.kernel.org,
Jason Low <jason.low2@...com>,
Jonathan Corbet <corbet@....net>,
Scott J Norton <scott.norton@....com>,
Douglas Hatch <doug.hatch@....com>
Subject: Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock
ASAP
On Sun, Oct 09, 2016 at 08:17:48AM -0700, Christoph Hellwig wrote:
> On Fri, Oct 07, 2016 at 08:47:51AM +1100, Dave Chinner wrote:
> > Except that it's DAX, and in 4.7-rc1 that used shared locking at the
> > XFS level and never took exclusive locks.
> >
> > *However*, the DAX IO path locking in XFS has changed in 4.9-rc1 to
> > match the buffered IO single writer POSIX semantics - the test is a
> > bad test based on the fact it exercised a path that is under heavy
> > development and so can't be used as a regression test across
> > multiple kernels.
>
> That being said - I wonder if we should allow the shared lock on DAX
> files IFF the user is specifying O_DIRECT in the open mode..
It should do - if it doesn't then we screwed up the IO path
selection logic in XFS and we'll need to fix it.
Cheers,
Dave.
--
Dave Chinner
david@...morbit.com
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