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From: Hannes Reinecke <hare@suse.de>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <keith.busch@intel.com>,
	Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme: always treat DNR status as no-retryable
Date: Tue, 26 Nov 2019 17:28:39 +0100
Message-ID: <a372f5a8-9510-bb8a-9eb4-4777e5518857@suse.de> (raw)
In-Reply-To: <20191126162206.GB7562@lst.de>

On 11/26/19 5:22 PM, Christoph Hellwig wrote:
> On Tue, Nov 26, 2019 at 02:37:49PM +0100, Hannes Reinecke wrote:
>> If the DNR bit is set in the command status we should not retry
>> the command, irrespective of what the actual status is.
>> So map it directly to BLK_STS_TARGET to inform upper layers to
>> not retry the command, not even on another path.
> 
> We've been there before, have we?  What is your use case.  I.e.
> what part of the kernel is retrying what command that you don't
> want to be retried?
> 
EG Namespace not ready.
Some NetApp arrays return "namespace not ready" for either a temporary 
issue (eg during array failover or whatnot), and then will have the DNR 
bit not set (as you can retry, and eventually the namespace will become 
ready). Or they return 'namepace not ready' for cases where the 
namespace has been unmapped, for which is retry is pointless, and hence 
have the DNR bit set.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@suse.de                              +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)

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Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-26 13:37 Hannes Reinecke
2019-11-26 16:15 ` Keith Busch
2019-11-26 16:34   ` Hannes Reinecke
2019-11-26 16:39     ` Christoph Hellwig
2019-11-26 16:22 ` Christoph Hellwig
2019-11-26 16:28   ` Hannes Reinecke [this message]

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