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Date:   Wed, 18 Nov 2020 08:09:54 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Christoph Hellwig <hch@lst.de>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH RFC] iomap: only return IO error if no data has been
 transferred
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On Tue, Nov 17, 2020 at 03:17:18PM -0700, Jens Axboe wrote:
> If we've successfully transferred some data in __iomap_dio_rw(),
> don't mark an error for a latter segment in the dio.

For normal direct I/O we never return short reads/writes, and IIRC that
has been inherited from the old direct I/O code.  I think we'll need
to make this conditional on your nowait case rather than changing the
user visible behavior.