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From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>
Cc: Kanchan Joshi <joshi.k@samsung.com>,
	io-uring@vger.kernel.org, linux-nvme@lists.infradead.org,
	asml.silence@gmail.com, mcgrof@kernel.org, shr@fb.com,
	joshiiitr@gmail.com, anuj20.g@samsung.com, gost.dev@samsung.com
Subject: Re: [PATCH v5 2/6] block: wire-up support for passthrough plugging
Date: Thu, 12 May 2022 06:31:18 -0600	[thread overview]
Message-ID: <74e33b5d-71ce-1309-7897-e5e8ad2ed778@kernel.dk> (raw)
In-Reply-To: <YnzI7CgI+KOHNKPb@T590>

On 5/12/22 2:44 AM, Ming Lei wrote:
> On Thu, May 12, 2022 at 10:09:12AM +0200, Christoph Hellwig wrote:
>> On Thu, May 12, 2022 at 01:25:24PM +0800, Ming Lei wrote:
>>> This way may cause nested plugging, and breaks xfstests generic/131.
>>> Also may cause io hang since request can't be polled before flushing
>>> plug in blk_execute_rq().
>>
>> Looking at this again, yes blk_mq_request_bypass_insert is probably the
>> wrong place.
>>
>>> I'd suggest to apply the plug in blk_execute_rq_nowait(), such as:
>>
>> Do we really need the use_plug parameter and the extra helper?  If
>> someone holds a plug over passthrough command submission I think
>> we can assume they actually do want to use it.  Otherwise this does
>> indeed look like the better plan.
> 
> use_plug is just for avoiding hang in blk_rq_poll_completion(), so
> I think we can bypass plug if one polled rq is executed inside
> blk_execute_rq().

Agree, and good catch. Do you want to send out a patch for this?

-- 
Jens Axboe


  reply	other threads:[~2022-05-12 12:31 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20220511055306epcas5p3bf3b4c1e32d2bb43db12785bd7caf5da@epcas5p3.samsung.com>
2022-05-11  5:47 ` [PATCH v5 0/6] io_uring passthrough for nvme Kanchan Joshi
     [not found]   ` <CGME20220511055308epcas5p3627bcb0ec10d7a2222e701898e9ad0db@epcas5p3.samsung.com>
2022-05-11  5:47     ` [PATCH v5 1/6] fs,io_uring: add infrastructure for uring-cmd Kanchan Joshi
2022-05-11 12:42       ` Christoph Hellwig
     [not found]   ` <CGME20220511055310epcas5p46650f5b6fe963279f686b8f50a98a286@epcas5p4.samsung.com>
2022-05-11  5:47     ` [PATCH v5 2/6] block: wire-up support for passthrough plugging Kanchan Joshi
2022-05-12  5:25       ` Ming Lei
2022-05-12  8:09         ` Christoph Hellwig
2022-05-12  8:44           ` Ming Lei
2022-05-12 12:31             ` Jens Axboe [this message]
2022-05-12 11:50         ` Anuj Gupta
2022-05-12 14:06           ` Ming Lei
     [not found]   ` <CGME20220511055312epcas5p3b1e9989a32cb1a79f8a941476fc433d1@epcas5p3.samsung.com>
2022-05-11  5:47     ` [PATCH v5 3/6] nvme: refactor nvme_submit_user_cmd() Kanchan Joshi
     [not found]   ` <CGME20220511055314epcas5p42ddbc17608f2677814c07b0d790e1318@epcas5p4.samsung.com>
2022-05-11  5:47     ` [PATCH v5 4/6] nvme: wire-up uring-cmd support for io-passthru on char-device Kanchan Joshi
     [not found]   ` <CGME20220511055319epcas5p1d78cb03bd1b145a6d58c8e616795af14@epcas5p1.samsung.com>
2022-05-11  5:47     ` [PATCH v5 5/6] nvme: add vectored-io support for uring-cmd Kanchan Joshi
     [not found]   ` <CGME20220511055320epcas5p2457aaf8e7405387282f60831f5a4eca9@epcas5p2.samsung.com>
2022-05-11  5:47     ` [PATCH v5 6/6] io_uring: finish IOPOLL/ioprio prep handler removal Kanchan Joshi
2022-05-11  6:54       ` Christoph Hellwig
2022-05-11 11:05         ` Kanchan Joshi
2022-05-11 12:38         ` Jens Axboe
2022-05-11 12:39   ` [PATCH v5 0/6] io_uring passthrough for nvme Jens Axboe
2022-05-11 13:14     ` Kanchan Joshi
2022-05-11 13:39       ` Jens Axboe
2022-05-11 13:48   ` Jens Axboe

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