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From: Ming Lei <ming.lei@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>,
	Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org
Subject: Re: [PATCH 3/3] block: Specify the operation type when calling blk_mq_map_queue()
Date: Wed, 15 Jun 2022 14:24:20 +0800	[thread overview]
Message-ID: <Yql7FCHTZbVIKWQV@T590> (raw)
In-Reply-To: <20220615060851.GE22115@lst.de>

On Wed, Jun 15, 2022 at 08:08:51AM +0200, Christoph Hellwig wrote:
> On Wed, Jun 15, 2022 at 08:31:21AM +0800, Ming Lei wrote:
> > > -	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, 0, ctx);
> > > +	struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, REQ_OP_WRITE, ctx);
> > 
> > The change itself doesn't make a difference, since both results in choosing
> > HCTX_TYPE_DEFAULT, but passing REQ_OP_WRITE is a bit misleading.
> 
> Well, the argument is an operationm so we better pass in a correct
> operation (at some point we should look into a __bitwise annotation
> or similar to make it clean).  And as 0 is REQ_OP_READ, we will end
> up with the HCTX_TYPE_READ hctx IFF someone configures read queues
> and uses an sq only schedule.  Which is a completely stupid but
> possible setup.
> 

OK, looks here the hctx can be retrieved ctx->hctxs[HCTX_TYPE_DEFAULT]
directly.


Thanks,
Ming


  reply	other threads:[~2022-06-15  6:24 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-14 17:57 [PATCH 0/3] Three small block layer patches Bart Van Assche
2022-06-14 17:57 ` [PATCH 1/3] blk-iocost: Simplify ioc_rqos_done() Bart Van Assche
2022-06-14 18:26   ` Tejun Heo
2022-06-15  5:58   ` Christoph Hellwig
2022-06-14 17:57 ` [PATCH 2/3] block: Rename a blk_mq_map_queue() argument Bart Van Assche
2022-06-15  5:58   ` Christoph Hellwig
2022-06-14 17:57 ` [PATCH 3/3] block: Specify the operation type when calling blk_mq_map_queue() Bart Van Assche
2022-06-14 19:31   ` Jens Axboe
2022-06-15  0:31   ` Ming Lei
2022-06-15  6:08     ` Christoph Hellwig
2022-06-15  6:24       ` Ming Lei [this message]
2022-06-17 18:25       ` Bart Van Assche
2022-06-20  7:29         ` Christoph Hellwig

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