[PATCH] erofs: support direct IO for uncompressed file

[Huang Jianan]

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.