From: Sagi Grimberg <sagi@grimberg.me>
To: Daniel Wagner <dwagner@suse.de>
Cc: "Knight, Frederick" <Frederick.Knight@netapp.com>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
"hare@suse.de" <hare@suse.de>
Subject: Re: [PATCH v2] nvmet: force reconnect when number of queue changes
Date: Thu, 6 Oct 2022 14:37:32 +0300 [thread overview]
Message-ID: <74eb192e-13aa-5043-3016-5ce0d7ca2688@grimberg.me> (raw)
In-Reply-To: <20221005181510.zu7vcwjtltcal2zi@carbon.lan>
>>> As far I can tell, what's is missing from a testing point of view is the
>>> ability to fail requests without the DNR bit set or the ability to tell
>>> the host to reconnect. Obviously, an AEN would be nice for this but I
>>> don't know if this is reason enough to extend the spec.
>>
>> Looking into the code, its the connect that fails on invalid parameter
>> with a DNR, because the host is attempting to connect to a subsystems
>> that does not exist on the port (because it was taken offline for
>> maintenance reasons).
>>
>> So I guess it is valid to allow queue change without removing it from
>> the port, but that does not change the fundamental question on DNR.
>> If the host sees a DNR error on connect, my interpretation is that the
>> host should not retry the connect command itself, but it shouldn't imply
>> anything on tearing down the controller and giving up on it completely,
>> forever.
>
> Okay, let me try to avoid the DNR discussion for now and propose
> something else? What about adding a 'enable' attribute to the subsys?
>
> The snipped below does the trick. Though There is no explicit
> synchronization between host and target, so it's possible the host
> doesn't notice that the subsystem toggled enabled and updated the number
> queues. But not sure if it's worth to address this, it feels a bit
> over-engineered.
I think that for the matter of this patch, you can keep force reconnect.
But I still think we need to be consistent with the different transports
on how we interperet controller returning DNR...
next prev parent reply other threads:[~2022-10-06 11:38 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-27 14:31 [PATCH v2] nvmet: force reconnect when number of queue changes Daniel Wagner
2022-09-27 15:01 ` Daniel Wagner
2022-09-28 6:55 ` Sagi Grimberg
2022-09-28 7:48 ` Daniel Wagner
2022-09-28 8:31 ` Sagi Grimberg
2022-09-28 9:02 ` Daniel Wagner
2022-09-28 12:39 ` Knight, Frederick
2022-09-28 13:50 ` Daniel Wagner
2022-09-28 14:23 ` Sagi Grimberg
2022-09-28 15:21 ` Hannes Reinecke
2022-09-28 16:01 ` Knight, Frederick
2022-10-05 18:15 ` Daniel Wagner
2022-10-06 11:37 ` Sagi Grimberg [this message]
2022-10-06 20:15 ` James Smart
2022-10-06 20:54 ` Knight, Frederick
2022-09-28 16:01 ` Knight, Frederick
2022-09-28 15:01 ` John Meneghini
2022-09-28 15:26 ` Daniel Wagner
2022-09-28 18:02 ` Knight, Frederick
2022-09-29 2:14 ` John Meneghini
2022-09-29 3:04 ` Knight, Frederick
2022-09-30 7:03 ` Hannes Reinecke
2022-09-30 6:32 ` Hannes Reinecke
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