linux-kernel - Re: [PATCH v1 5/9] block: loop: convert to blk-mq

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Message-ID: <53EE3966.60609@kernel.dk>
Date:	Fri, 15 Aug 2014 10:46:30 -0600
From:	Jens Axboe <axboe@...nel.dk>
To:	Christoph Hellwig <hch@...radead.org>,
	Ming Lei <ming.lei@...onical.com>
CC:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Kleikamp <dave.kleikamp@...cle.com>,
	Zach Brown <zab@...bo.net>, Benjamin LaHaise <bcrl@...ck.org>,
	Kent Overstreet <kmo@...erainc.com>, linux-aio@...ck.org,
	linux-fsdevel@...r.kernel.org, Dave Chinner <david@...morbit.com>
Subject: Re: [PATCH v1 5/9] block: loop: convert to blk-mq

On 08/15/2014 10:36 AM, Jens Axboe wrote:
> On 08/15/2014 10:31 AM, Christoph Hellwig wrote:
>>> +static void loop_queue_work(struct work_struct *work)
>>
>> Offloading work straight to a workqueue dosn't make much sense
>> in the blk-mq model as we'll usually be called from one.  If you
>> need to avoid the cases where we are called directly a flag for
>> the blk-mq code to always schedule a workqueue sounds like a much
>> better plan.
> 
> That's a good point - would clean up this bit, and be pretty close to a
> one-liner to support in blk-mq for the drivers that always need blocking
> context.

Something like this should do the trick - totally untested. But with
that, loop would just need to add BLK_MQ_F_WQ_CONTEXT to it's tag set
flags and it could always do the work inline from ->queue_rq().

-- 
Jens Axboe


View attachment "blk-mq-wq.patch" of type "text/x-patch" (1231 bytes)