From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>, Brian Foster <bfoster@redhat.com>,
linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/3] xfs: go straight to real allocations for direct I/O COW writes
Date: Fri, 27 Jan 2017 18:48:20 +0100 [thread overview]
Message-ID: <20170127174820.GA18919@lst.de> (raw)
In-Reply-To: <20170127174447.GZ9134@birch.djwong.org>
On Fri, Jan 27, 2017 at 09:44:47AM -0800, Darrick J. Wong wrote:
> I think I came up with a better idea overnight: take advantage of the
> unwritten bit. Currently, all extents in the cow fork are either
> delalloc or normal extents. When we allocate the blocks to fill a cow
> extent, we'll flag the extent as unwritten. When we go to write the
> data to disk, we convert the unwritten extent to a real extent, and the
> post-write remap (since it only takes a file offset and length) will
> be changed to remap only real, written extents into the data fork.
That sounds like a possibility. My other idea was to force COW all
direct I/O writes, that way we can't have a mismatch between extents
in the data and the COW fork. But so far this is just an idea..
next prev parent reply other threads:[~2017-01-27 17:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-05 21:05 reflink COW improvements Christoph Hellwig
2016-12-05 21:05 ` [PATCH 1/3] xfs: reject all unaligned direct writes to reflinked files Christoph Hellwig
2016-12-07 18:59 ` Brian Foster
2016-12-05 21:05 ` [PATCH 2/3] xfs: go straight to real allocations for direct I/O COW writes Christoph Hellwig
2016-12-07 19:00 ` Brian Foster
2016-12-07 19:37 ` Christoph Hellwig
2016-12-07 19:46 ` Brian Foster
2016-12-08 4:23 ` Darrick J. Wong
2017-01-24 8:37 ` Christoph Hellwig
2017-01-24 13:50 ` Brian Foster
2017-01-24 13:59 ` Christoph Hellwig
2017-01-24 15:02 ` Brian Foster
2017-01-24 15:09 ` Christoph Hellwig
2017-01-24 16:17 ` Brian Foster
2017-01-24 16:21 ` Christoph Hellwig
2017-01-24 17:43 ` Brian Foster
2017-01-24 20:08 ` Christoph Hellwig
2017-01-24 20:10 ` Christoph Hellwig
2017-01-25 0:09 ` Darrick J. Wong
2017-01-27 17:44 ` Darrick J. Wong
2017-01-27 17:48 ` Christoph Hellwig [this message]
2016-12-05 21:05 ` [PATCH 3/3] xfs: allocate direct I/O COW blocks in iomap_begin Christoph Hellwig
2016-12-06 2:09 ` reflink COW improvements Darrick J. Wong
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