linux-kernel - Re: [PATCH v12 11/13] dm: call dm_zone_endio after the target endio callback for zoned devices

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Message-ID: <YxFLzHoYF7damFip@redhat.com>
Date:   Thu, 1 Sep 2022 20:18:20 -0400
From:   Mike Snitzer <snitzer@...hat.com>
To:     Pankaj Raghav <p.raghav@...sung.com>
Cc:     agk@...hat.com, snitzer@...nel.org, axboe@...nel.dk,
        damien.lemoal@...nsource.wdc.com, hch@....de, bvanassche@....org,
        pankydev8@...il.com, Johannes.Thumshirn@....com,
        linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-block@...r.kernel.org, dm-devel@...hat.com,
        gost.dev@...sung.com, jaegeuk@...nel.org, matias.bjorling@....com
Subject: Re: [PATCH v12 11/13] dm: call dm_zone_endio after the target endio
 callback for zoned devices

On Tue, Aug 23 2022 at  8:18P -0400,
Pankaj Raghav <p.raghav@...sung.com> wrote:

> dm_zone_endio() updates the bi_sector of orig bio for zoned devices that
> uses either native append or append emulation, and it is called before the
> endio of the target. But target endio can still update the clone bio
> after dm_zone_endio is called, thereby, the orig bio does not contain
> the updated information anymore.
> 
> Currently, this is not a problem as the targets that support zoned devices
> such as dm-zoned, dm-linear, and dm-crypt do not have an endio function,
> and even if they do (such as dm-flakey), they don't modify the
> bio->bi_iter.bi_sector of the cloned bio that is used to update the
> orig_bio's bi_sector in dm_zone_endio function.
> 
> This is a prep patch for the new dm-po2zone target as it modifies
> bi_sector in the endio callback.
> 
> Call dm_zone_endio for zoned devices after calling the target's endio
> function.
> 
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>

Great patch header, explains the situation nicely.

Reviewed-by: Mike Snitzer <snitzer@...nel.org>