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From: Mike Snitzer <snitzer@redhat.com>
To: Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>
Cc: Ewan Milne <emilne@redhat.com>, Hannes Reinecke <hare@suse.de>,
	John Meneghini <johnm@netapp.com>,
	linux-block@vger.kernel.org, linux-nvme@lists.infradead.org,
	dm-devel@redhat.com
Subject: NVMe regression, NVMe no longer uses blk_path_error()
Date: Wed, 1 Jul 2020 12:39:42 -0400	[thread overview]
Message-ID: <20200701163942.GB27063@redhat.com> (raw)

IF NVMe's isn't a primary user of blk_path_error() it largely kills
the entire point of blk_path_error(). (And no the response to this must
not be: "that's fine")

This commit shows NVMe's previous continued use of blk_path_error():

  8decf5d5b9f3f7 ("nvme: remove nvme_req_needs_failover")

but then nvme_failover_req() was relatively recently refactored with:

  764e9332098c0 ("nvme-multipath: do not reset on unknown status")

NVMe should've continued to use blk_path_error().  If there was some gap
in error classification that should've been fixed in NVMe.

Instead, with commit 764e9332098c0 NVMe is no longer using retryable
error classifications commonly maintained within block core.  As such it
introduces serious potential for regression with DM multipath no longer
having a shared understanding for what _really_ constitutes a retryable
blk_status_t from NVMe.

Mike


WARNING: multiple messages have this Message-ID (diff)
From: Mike Snitzer <snitzer@redhat.com>
To: Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>
Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	dm-devel@redhat.com, Hannes Reinecke <hare@suse.de>,
	John Meneghini <johnm@netapp.com>, Ewan Milne <emilne@redhat.com>
Subject: NVMe regression, NVMe no longer uses blk_path_error()
Date: Wed, 1 Jul 2020 12:39:42 -0400	[thread overview]
Message-ID: <20200701163942.GB27063@redhat.com> (raw)

IF NVMe's isn't a primary user of blk_path_error() it largely kills
the entire point of blk_path_error(). (And no the response to this must
not be: "that's fine")

This commit shows NVMe's previous continued use of blk_path_error():

  8decf5d5b9f3f7 ("nvme: remove nvme_req_needs_failover")

but then nvme_failover_req() was relatively recently refactored with:

  764e9332098c0 ("nvme-multipath: do not reset on unknown status")

NVMe should've continued to use blk_path_error().  If there was some gap
in error classification that should've been fixed in NVMe.

Instead, with commit 764e9332098c0 NVMe is no longer using retryable
error classifications commonly maintained within block core.  As such it
introduces serious potential for regression with DM multipath no longer
having a shared understanding for what _really_ constitutes a retryable
blk_status_t from NVMe.

Mike


_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

             reply	other threads:[~2020-07-01 17:41 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-01 16:39 Mike Snitzer [this message]
2020-07-01 16:39 ` NVMe regression, NVMe no longer uses blk_path_error() Mike Snitzer

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