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From: Christoph Hellwig <hch@lst.de>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Keith Busch <kbusch@kernel.org>, Chao Leng <lengchao@huawei.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH 4/4] nvme: redirect commands on dying queue
Date: Tue, 18 Aug 2020 08:32:39 +0200	[thread overview]
Message-ID: <20200818063239.GC1754@lst.de> (raw)
In-Reply-To: <20200817152321.GD30005@redhat.com>

On Mon, Aug 17, 2020 at 11:23:22AM -0400, Mike Snitzer wrote:
> On Mon, Aug 17 2020 at  4:15am -0400,
> Christoph Hellwig <hch@lst.de> wrote:
> 
> > From: Chao Leng <lengchao@huawei.com>
> > 
> > If a command send through nvme-multipath failed on a dying queue, resend it
> > on another path.
> > 
> > Signed-off-by: Chao Leng <lengchao@huawei.com>
> > [hch: rebased on top of the completion refactoring]
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
> 
> Did we ever learn from Chao what the original issue was?  Deciding to
> failover on completion because blk_queue_dying(), without any other
> insight, is definitely new to me.

Yes.  Basically the controller is going away after returning a retryable
error.

> But this looks fine, just in general such blk_queue_dying() checks are
> pretty racey right?  Feels like this might paper over something else but
> without knowing more:

But I guess the race doesn't matter - if we lose it, ->queue_rq will
fail and the submission path will pick another path as well.

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  reply	other threads:[~2020-08-18  6:32 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-17  8:15 nvme completion handling refactor and fix v2 Christoph Hellwig
2020-08-17  8:15 ` [PATCH 1/4] nvme: rename and document nvme_end_request Christoph Hellwig
2020-08-17 14:53   ` Mike Snitzer
2020-08-17  8:15 ` [PATCH 2/4] nvme: refactor command completion Christoph Hellwig
2020-08-17 15:08   ` Mike Snitzer
2020-08-17 19:28   ` Mike Snitzer
2020-08-18  6:26     ` Christoph Hellwig
2020-08-17  8:15 ` [PATCH 3/4] nvme: just check the status code type in nvme_is_path_error Christoph Hellwig
2020-08-17 15:11   ` Mike Snitzer
2020-08-17 19:31   ` Sagi Grimberg
2020-08-18  6:31     ` Christoph Hellwig
2020-08-17  8:15 ` [PATCH 4/4] nvme: redirect commands on dying queue Christoph Hellwig
2020-08-17 15:23   ` Mike Snitzer
2020-08-18  6:32     ` Christoph Hellwig [this message]
2020-08-17 18:10 ` nvme completion handling refactor and fix v2 Sagi Grimberg
2020-08-18  6:33   ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2020-08-18  7:11 nvme completion handling refactor and fix v3 Christoph Hellwig
2020-08-18  7:11 ` [PATCH 4/4] nvme: redirect commands on dying queue Christoph Hellwig
2020-08-19 10:01   ` Chao Leng
2020-08-19 10:50     ` Christoph Hellwig

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