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Date: Thu, 28 Mar 2024 05:54:30 +0100
From: Christoph Hellwig <hch@lst.de>
To: Damien Le Moal <dlemoal@kernel.org>
Cc: linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	linux-scsi@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	dm-devel@lists.linux.dev, Mike Snitzer <snitzer@redhat.com>,
	linux-nvme@lists.infradead.org, Keith Busch <kbusch@kernel.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3 30/30] block: Do not special-case plugging of zone
 write operations
Message-ID: <20240328045430.GN14113@lst.de>
References: <20240328004409.594888-1-dlemoal@kernel.org> <20240328004409.594888-31-dlemoal@kernel.org>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, Mar 28, 2024 at 09:44:09AM +0900, Damien Le Moal wrote:
> With the block layer zone write plugging being automatically done for
> any write operation to a zone of a zoned block device, a regular request
> plugging handled through current->plug can only ever see at most a
> single write request per zone. In such case, any potential reordering
> of the plugged requests will be harmless. We can thus remove the special
> casing for write operations to zones and have these requests plugged as
> well. This allows removing the function blk_mq_plug and instead directly
> using current->plug where needed.

This looks good in general:

Reviewed-by: Christoph Hellwig <hch@lst.de>

But IIRC we recently had a report that plus reorder I/Os, which would
be grave for the extent layout if we haven't fixed that yet, so we
should probably look into it first.