linux-kernel - Re: [PATCH 09/60] dm: dm.c: replace 'bio->bi_vcnt == 1' with !bio_multiple

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Date:   Tue, 1 Nov 2016 06:59:52 +0800
From:   Ming Lei <tom.leiming@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Jens Axboe <axboe@...com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>,
        "maintainer:DEVICE-MAPPER (LVM)" <dm-devel@...hat.com>,
        Shaohua Li <shli@...nel.org>,
        "open list:SOFTWARE RAID (Multiple Disks) SUPPORT" 
        <linux-raid@...r.kernel.org>
Subject: Re: [PATCH 09/60] dm: dm.c: replace 'bio->bi_vcnt == 1' with !bio_multiple_segments

On Mon, Oct 31, 2016 at 11:29 PM, Christoph Hellwig <hch@...radead.org> wrote:
> On Sat, Oct 29, 2016 at 04:08:08PM +0800, Ming Lei wrote:
>> Avoid to access .bi_vcnt directly, because it may be not what
>> the driver expected any more after supporting multipage bvec.
>>
>> Signed-off-by: Ming Lei <tom.leiming@...il.com>
>
> It would be really nice to have a comment in the code why it's
> even checking for multiple segments.
>

OK, will add comment about using !bio_multiple_segments(rq->bio)
to replace 'rq->bio->bi_vcnt == 1'.


Thanks,
Ming Lei