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Date:   Wed, 10 Feb 2021 14:19:28 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Ruan Shiyang <ruansy.fnst@cn.fujitsu.com>
Cc:     Christoph Hellwig <hch@lst.de>, linux-kernel@vger.kernel.org,
        linux-xfs@vger.kernel.org, linux-nvdimm@lists.01.org,
        linux-fsdevel@vger.kernel.org, darrick.wong@oracle.com,
        dan.j.williams@intel.com, willy@infradead.org, jack@suse.cz,
        viro@zeniv.linux.org.uk, linux-btrfs@vger.kernel.org,
        ocfs2-devel@oss.oracle.com, david@fromorbit.com, rgoldwyn@suse.de,
        Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 5/7] fsdax: Dedup file range to use a compare function
Message-ID: <20210210131928.GA30109@lst.de>
References: <20210207170924.2933035-1-ruansy.fnst@cn.fujitsu.com> <20210207170924.2933035-6-ruansy.fnst@cn.fujitsu.com> <20210208151920.GE12872@lst.de> <9193e305-22a1-3928-0675-af1cecd28942@cn.fujitsu.com> <20210209093438.GA630@lst.de> <79b0d65c-95dd-4821-e412-ab27c8cb6942@cn.fujitsu.com>
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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.