From: "Darrick J. Wong" <djwong@kernel.org>
To: Ruan Shiyang <ruansy.fnst@cn.fujitsu.com>
Cc: jack@suse.cz, linux-nvdimm@lists.01.org, darrick.wong@oracle.com,
david@fromorbit.com, linux-kernel@vger.kernel.org,
linux-xfs@vger.kernel.org, ocfs2-devel@oss.oracle.com,
viro@zeniv.linux.org.uk, Goldwyn Rodrigues <rgoldwyn@suse.com>,
linux-fsdevel@vger.kernel.org, dan.j.williams@intel.com,
linux-btrfs@vger.kernel.org
Subject: Re: [Ocfs2-devel] [PATCH 5/7] fsdax: Dedup file range to use a compare function
Date: Thu, 18 Feb 2021 08:20:18 -0800 [thread overview]
Message-ID: <20210218162018.GT7193@magnolia> (raw)
In-Reply-To: <b00cfda5-464c-6161-77c6-6a25b1cc7a77@cn.fujitsu.com>
On Wed, Feb 17, 2021 at 11:24:18AM +0800, Ruan Shiyang wrote:
>
>
> On 2021/2/10 下午9:19, Christoph Hellwig wrote:
> > On Tue, Feb 09, 2021 at 05:46:13PM +0800, Ruan Shiyang wrote:
> > >
> > >
> > > On 2021/2/9 下午5:34, Christoph Hellwig wrote:
> > > > On Tue, Feb 09, 2021 at 05:15:13PM +0800, Ruan Shiyang wrote:
> > > > > The dax dedupe comparison need the iomap_ops pointer as argument, so my
> > > > > understanding is that we don't modify the argument list of
> > > > > generic_remap_file_range_prep(), but move its code into
> > > > > __generic_remap_file_range_prep() whose argument list can be modified to
> > > > > accepts the iomap_ops pointer. Then it looks like this:
> > > >
> > > > I'd say just add the iomap_ops pointer to
> > > > generic_remap_file_range_prep and do away with the extra wrappers. We
> > > > only have three callers anyway.
> > >
> > > OK.
> >
> > So looking at this again I think your proposal actaully is better,
> > given that the iomap variant is still DAX specific. Sorry for
> > the noise.
> >
> > Also I think dax_file_range_compare should use iomap_apply instead
> > of open coding it.
> >
>
> There are two files, which are not reflinked, need to be direct_access()
> here. The iomap_apply() can handle one file each time. So, it seems that
> iomap_apply() is not suitable for this case...
>
>
> The pseudo code of this process is as follows:
>
> srclen = ops->begin(&srcmap)
> destlen = ops->begin(&destmap)
>
> direct_access(&srcmap, &saddr)
> direct_access(&destmap, &daddr)
>
> same = memcpy(saddr, daddr, min(srclen,destlen))
>
> ops->end(&destmap)
> ops->end(&srcmap)
>
> I think a nested call like this is necessary. That's why I use the open
> code way.
This might be a good place to implement an iomap_apply2() loop that
actually /does/ walk all the extents of file1 and file2. There's now
two users of this idiom.
(Possibly structured as a "get next mappings from both" generator
function like Matthew Wilcox keeps asking for. :))
--D
>
> --
> Thanks,
> Ruan Shiyang.
> >
>
>
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next prev parent reply other threads:[~2021-02-26 16:55 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-07 17:09 [Ocfs2-devel] [PATCH 0/7] fsdax, xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 1/7] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-02-08 15:11 ` Christoph Hellwig
2021-02-22 7:44 ` Xiaoguang Wang
2021-02-23 1:32 ` [Ocfs2-devel] 回复: " ruansy.fnst
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 2/7] fsdax: Introduce dax_copy_edges() for CoW Shiyang Ruan
2021-02-08 15:11 ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 3/7] fsdax: Copy data before write Shiyang Ruan
2021-02-08 15:14 ` Christoph Hellwig
2021-02-09 1:53 ` Ruan Shiyang
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 4/7] fsdax: Replace mmap entry in case of CoW Shiyang Ruan
2021-02-08 15:16 ` Christoph Hellwig
2021-02-16 13:11 ` David Sterba
2021-02-17 3:06 ` Ruan Shiyang
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 5/7] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-02-08 15:19 ` Christoph Hellwig
2021-02-09 9:15 ` Ruan Shiyang
2021-02-09 9:34 ` Christoph Hellwig
2021-02-09 9:46 ` Ruan Shiyang
2021-02-10 13:19 ` Christoph Hellwig
2021-02-17 3:24 ` Ruan Shiyang
2021-02-18 16:20 ` Darrick J. Wong [this message]
2021-02-25 7:35 ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 6/7] fs/xfs: Handle CoW for fsdax write() path Shiyang Ruan
2021-02-08 15:24 ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 7/7] fs/xfs: Add dedupe support for fsdax Shiyang Ruan
2021-02-08 15:39 ` [Ocfs2-devel] [PATCH 0/7] fsdax, xfs: Add reflink&dedupe " Jan Kara
2021-02-09 1:50 ` Ruan Shiyang
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