linux-kernel - Re: [PATCH V5] block: fix the DISCARD request merge

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Date:   Mon, 29 Oct 2018 09:33:19 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Jianchao Wang <jianchao.w.wang@...cle.com>
Cc:     martin.petersen@...cle.com, tom.leiming@...il.com, hch@....de,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V5] block: fix the DISCARD request merge

On 10/27/18 5:52 AM, Jianchao Wang wrote:
> There are two cases when handle DISCARD merge.
> If max_discard_segments == 1, the bios/requests need to be contiguous
> to merge. If max_discard_segments > 1, it takes every bio as a range
> and different range needn't to be contiguous.
> 
> But now, attempt_merge screws this up. It always consider contiguity
> for DISCARD for the case max_discard_segments > 1 and cannot merge
> contiguous DISCARD for the case max_discard_segments == 1, because
> rq_attempt_discard_merge always returns false in this case.
> This patch fixes both of the two cases above.

Applied, thanks.

-- 
Jens Axboe