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Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock ASAP

From Dave Chinner <david@fromorbit.com>
Newsgroups linux.kernel
Subject Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock ASAP
Date 2016-10-10 08:10 +0200
Message-ID <sqBWF-65e-11@gated-at.bofh.it> (permalink)
References <s7Gka-6XF-49@gated-at.bofh.it> <s7HSV-892-7@gated-at.bofh.it> <splqV-4mC-23@gated-at.bofh.it> <spoI9-6CY-7@gated-at.bofh.it> <sqo3o-5Tb-15@gated-at.bofh.it>
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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@fromorbit.com

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Thread

Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Davidlohr Bueso <dave@stgolabs.net> - 2016-10-06 20:20 +0200
  Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Dave Chinner <david@fromorbit.com> - 2016-10-06 23:50 +0200
    Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Davidlohr Bueso <dave@stgolabs.net> - 2016-10-07 01:00 +0200
    Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Christoph Hellwig <hch@infradead.org> - 2016-10-09 17:20 +0200
      Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Dave Chinner <david@fromorbit.com> - 2016-10-10 08:10 +0200
        Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Christoph Hellwig <hch@infradead.org> - 2016-10-10 12:20 +0200
          Re: [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock  ASAP Dave Chinner <david@fromorbit.com> - 2016-10-11 23:10 +0200

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