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From: Christoph Hellwig <hch@lst.de>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-xfs@vger.kernel.org
Subject: Re: [PATCH 6/6] xfs: avoid COW fork extent lookups in writeback if the fork didn't change
Date: Mon, 6 Aug 2018 18:45:04 +0200	[thread overview]
Message-ID: <20180806164504.GA18576@lst.de> (raw)
In-Reply-To: <20180806023738.GC7395@dastard>

On Mon, Aug 06, 2018 at 12:37:38PM +1000, Dave Chinner wrote:
> IOWs, I can't see any reliable access serialisation being provided
> by holding the ILOCK while modifying the value. Perhaps this should
> use WRITE_ONCE/READ_ONCE to ensure the correct memory barriers are
> used to serialise tthe sequence count against itself rather than the
> wider inode extent modification process?

Yes, I think we need a barrier before the later actual modification
of the extent tree and thus should use WRITE_ONCE/READ_ONCE.

I've got a patch that is undergoing testing at the moment.

  reply	other threads:[~2018-08-06 18:49 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-17 23:23 reduce lookups in the COW extent tree V3 Christoph Hellwig
2018-07-17 23:24 ` [PATCH 1/6] xfs: remove if_real_bytes Christoph Hellwig
2018-07-17 23:24 ` [PATCH 2/6] xfs: simplify xfs_idata_realloc Christoph Hellwig
2018-07-17 23:24 ` [PATCH 3/6] xfs: remove the xfs_ifork_t typedef Christoph Hellwig
2018-07-17 23:24 ` [PATCH 4/6] xfs: introduce a new xfs_inode_has_cow_data helper Christoph Hellwig
2018-07-17 23:24 ` [PATCH 5/6] xfs: maintain a sequence count for inode fork manipulations Christoph Hellwig
2018-07-18 14:40   ` Carlos Maiolino
2018-07-19 16:32     ` Christoph Hellwig
2018-07-19 18:27       ` Darrick J. Wong
2018-07-23 12:11         ` Carlos Maiolino
2018-07-17 23:24 ` [PATCH 6/6] xfs: avoid COW fork extent lookups in writeback if the fork didn't change Christoph Hellwig
2018-07-18 14:51   ` Carlos Maiolino
2018-07-21 23:23   ` Dave Chinner
2018-07-23  7:49     ` Christoph Hellwig
2018-07-24 22:35       ` Darrick J. Wong
2018-07-27 15:10         ` Christoph Hellwig
2018-08-06  2:37           ` Dave Chinner
2018-08-06 16:45             ` Christoph Hellwig [this message]
  -- strict thread matches above, loose matches on Subject: below --
2018-07-12 13:49 reduce lookups in the COW extent tree V2 Christoph Hellwig
2018-07-12 13:49 ` [PATCH 6/6] xfs: avoid COW fork extent lookups in writeback if the fork didn't change Christoph Hellwig
2018-07-13 22:51   ` Darrick J. Wong
2018-07-14  0:03   ` Dave Chinner
2018-07-17 13:37     ` Christoph Hellwig
2018-07-17 23:13       ` Dave Chinner
2018-07-10  6:05 reduce lookups in the COW extent tree Christoph Hellwig
2018-07-10  6:05 ` [PATCH 6/6] xfs: avoid COW fork extent lookups in writeback if the fork didn't change Christoph Hellwig
2018-07-11 17:15   ` Darrick J. Wong
2018-07-11 17:20     ` Christoph Hellwig
2018-07-11 17:31       ` Darrick J. Wong
2018-07-11 17:35         ` Christoph Hellwig

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