From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>,
device-mapper development <dm-devel@redhat.com>,
Mike Snitzer <snitzer@redhat.com>
Subject: Re: [dm-devel] [PATCH] dm rq: clear cloned bio ->bi_bdev to fix I/O accounting
Date: Mon, 17 Jan 2022 23:00:34 -0800 [thread overview]
Message-ID: <YeZlkpvCJ97nIzOS@infradead.org> (raw)
In-Reply-To: <YeYKGPxVZFM8pneN@T590>
On Tue, Jan 18, 2022 at 08:30:16AM +0800, Ming Lei wrote:
> On Sun, Jan 16, 2022 at 11:51:17PM -0800, Christoph Hellwig wrote:
> > So I actually noticed this during code inspection a while ago, but I
> > think we need to use the actual underlying device instead of NULL here
> > to keep our block layer gurantees. See the patch in my queue below.
> >
> > ---
> > From 1e330b8e57fc0d6c6fb07c0ec2915dca5d7a585a Mon Sep 17 00:00:00 2001
> > From: Christoph Hellwig <hch@lst.de>
> > Date: Thu, 13 Jan 2022 10:53:59 +0100
> > Subject: block: assign bi_bdev for cloned bios in blk_rq_prep_clone
> >
> > The cloned bios for the cloned request in blk_rq_prep_clone currently
> > still point to the original bi_bdev. This is harmless because dm-mpath
>
> It breaks io accounting, so not harmless, but the code in this patch is
> fine:
That's what I thought at the time. Based on the patch from
Benjamin that is obviously not true, so I'll reword the commit message
and add a Fixes tag.
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prev parent reply other threads:[~2022-01-18 7:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-14 17:58 [dm-devel] [PATCH] dm rq: clear cloned bio ->bi_bdev to fix I/O accounting Benjamin Marzinski
2022-01-16 5:52 ` Ming Lei
2022-01-17 7:51 ` Christoph Hellwig
2022-01-17 16:27 ` Benjamin Marzinski
2022-01-18 0:30 ` Ming Lei
2022-01-18 7:00 ` Christoph Hellwig [this message]
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