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Date:   Thu, 26 Nov 2020 10:02:27 +0000
From:   Christoph Hellwig <hch@infradead.org>
To:     Pavel Begunkov <asml.silence@gmail.com>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Ming Lei <ming.lei@redhat.com>,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 2/2] bio: optimise bvec iteration
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On Tue, Nov 24, 2020 at 05:58:13PM +0000, Pavel Begunkov wrote:
> __bio_for_each_bvec(), __bio_for_each_segment() and bio_copy_data_iter()
> fall under conditions of bvec_iter_advance_single(), which is a faster
> and slimmer version of bvec_iter_advance(). Add
> bio_advance_iter_single() and convert them.

Are you sure about bio_advance_iter()?  That API looks like it might
not always be limited to a single segment, and might at least need a
WARN_ON_ONCE to make sure it is not abused.