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Subject: Re: [PATCH] erofs: support direct IO for uncompressed file
To:     Christoph Hellwig <hch@infradead.org>,
        Gao Xiang <hsiangkao@redhat.com>
Cc:     guoweichao@oppo.com, linux-erofs@lists.ozlabs.org,
        zhangshiming@oppo.com, linux-kernel@vger.kernel.org
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From:   Huang Jianan <huangjianan@oppo.com>
Message-ID: <dc4452e9-83eb-90e7-f001-d39d0ecdd105@oppo.com>
Date:   Wed, 23 Dec 2020 16:48:20 +0800
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Hi Christoph,

The reason we use dio is because we need to deploy the patch on some 
early kernel versions, and we don't pay much attention to the change of 
iomap. Anyway, I will study the problem mentioned by Gao Xiang and try 
to convert the current patch to iomap.

Thanks,

Jianan

> On Wed, Dec 23, 2020 at 03:39:01AM +0800, Gao Xiang wrote:
>> Hi Christoph,
>>
>> On Tue, Dec 22, 2020 at 02:22:34PM +0000, Christoph Hellwig wrote:
>>> Please do not add new callers of __blockdev_direct_IO and use the modern
>>> iomap variant instead.
>> We've talked about this topic before. The current status is that iomap
>> doesn't support tail-packing inline data yet (Chao once sent out a version),
>> and erofs only cares about read intrastructure for now (So we don't think
>> more about how to deal with tail-packing inline write path). Plus, the
>> original patch was once lack of inline data regression test from gfs2 folks.
> So resend Chaos prep patch as part of the series switching parts of
> erofs to iomap.  We need to move things off the old infrastructure instead
> of adding more users and everyone needs to help a little.