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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
	linux-block@vger.kernel.org,
	Wang Shanker <shankerwangmiao@gmail.com>
Subject: Re: [PATCH 2/2] block: support bio merge for multi-range discard
Date: Tue, 22 Jun 2021 08:55:11 +0200	[thread overview]
Message-ID: <20210622065511.GB29691@lst.de> (raw)
In-Reply-To: <20210609004556.46928-3-ming.lei@redhat.com>

On Wed, Jun 09, 2021 at 08:45:56AM +0800, Ming Lei wrote:
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index bcdff1879c34..65210e9a8efa 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -724,10 +724,10 @@ static inline bool blk_discard_mergable(struct request *req)
>  static enum elv_merge blk_try_req_merge(struct request *req,
>  					struct request *next)
>  {
> -	if (blk_discard_mergable(req))
> -		return ELEVATOR_DISCARD_MERGE;
> -	else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
> +	if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
>  		return ELEVATOR_BACK_MERGE;

Oh well, this breaks my previous suggestions.

> +		struct req_discard_range r;
> +
> +		rq_for_each_discard_range(r, req) {

... and I can't say I like this rather complex iterator.

What is the problem of just fixing the raid code to not submit stupidly
small discard requests instead?

  parent reply	other threads:[~2021-06-22  6:55 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-09  0:45 [PATCH 0/2] block: discard merge fix & improvement Ming Lei
2021-06-09  0:45 ` [PATCH 1/2] block: fix discard request merge Ming Lei
2021-06-22  6:53   ` Christoph Hellwig
2021-06-22  7:51     ` Ming Lei
2021-06-09  0:45 ` [PATCH 2/2] block: support bio merge for multi-range discard Ming Lei
2021-06-09  3:05   ` Wang Shanker
2021-06-09  6:12     ` Ming Lei
2021-06-09  6:57       ` Wang Shanker
2021-06-22  6:55   ` Christoph Hellwig [this message]
2021-06-22  8:35     ` Miao Wang
2021-06-14 22:00 ` [PATCH 0/2] block: discard merge fix & improvement Ming Lei
2021-06-22  3:53   ` Ming Lei

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