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Date:   Mon, 23 May 2022 17:13:19 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Gwendal Grignou <gwendal@chromium.org>
Cc:     paolo.valente@linaro.org, axboe@kernel.dk, xieyongji@bytedance.com,
        ming.lei@redhat.com, linux-block@vger.kernel.org,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
        stable@vger.kernel.org
Subject: Re: [PATCH] block: return ELEVATOR_DISCARD_MERGE if possible
Message-ID: <Youkj8RWDNlpNUnL@kroah.com>
References: <20220521185626.3333530-1-gwendal@chromium.org>
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On Sat, May 21, 2022 at 11:56:26AM -0700, Gwendal Grignou wrote:
> From: Ming Lei <ming.lei@redhat.com>
> 
> When merging one bio to request, if they are discard IO and the queue
> supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
> because both block core and related drivers(nvme, virtio-blk) doesn't
> handle mixed discard io merge(traditional IO merge together with
> discard merge) well.
> 
> Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
> so both blk-mq and drivers just need to handle multi-range discard.
> 
> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Fixes: 2705dfb20947 ("block: fix discard request merge")
> Link: https://lore.kernel.org/r/20210729034226.1591070-1-ming.lei@redhat.com
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> commit 866663b7b52d2 upstream.
> 
> Similar to commit 87aa69aa10b42 ("block: return ELEVATOR_DISCARD_MERGE if possible")
> in 5.10 kernel.
> 
> Conflicts:
>    block/blk-merge.c: function at a different place.
>    block/mq-deadline-main.c: not in 5.4, use mq-deadline.c instead.
> 
> Cc: <stable@vger.kernel.org> # 5.4.y
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>

Now queued up, thanks.

greg k-h