Re: [PATCH v2] nvmet: force reconnect when number of queue changes

[Hannes Reinecke <hare@suse.de>]

On 9/28/22 20:02, Knight, Frederick wrote:
> Reset and Disconnect are different.
> 
> Reset uses registers (and therefore Get Property and Set Property commands) over a valid connection.
> 
> Disconnect causes a reset (you have to reconnect to the reset controller)
> Reset does not cause an immediate disconnect.
> 
This probably is a confusion with how the linux implementation works.
For linux NVMe-oF a reset is equivalent to a reconnect (ie disconnect 
followed by a reconnect), as for linux _any_ error will be escalated to 
be equivalent to a connection error.
Hence a pure 'reset' using Get/Set Property is never attempted.

Cheers,

Hannes

>> -----Original Message-----
>> From: Daniel Wagner <dwagner@suse.de>
>> Sent: Wednesday, September 28, 2022 11:26 AM
>> To: John Meneghini <jmeneghi@redhat.com>
>> Cc: Knight, Frederick <Frederick.Knight@netapp.com>; Sagi Grimberg
>> <sagi@grimberg.me>; linux-nvme@lists.infradead.org; Shinichiro Kawasaki
>> <shinichiro.kawasaki@wdc.com>; hare@suse.de
>> Subject: Re: [PATCH v2] nvmet: force reconnect when number of queue
>> changes
>>
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>>
>> On Wed, Sep 28, 2022 at 11:01:00AM -0400, John Meneghini wrote:
>>> So this is one place where I think we conflate NVMe-oF with NVMe in
>>> the specification.  If "reset" == "disconnect", then Daniel's patches
>>> just implemented support for something which is forbidden by the spec
>>> - a controller that changes the number of IOQs between resets.
>>
>> FWIW, the scenario I described is from a real world experience. So even if it
>> is forbidden by the spec, it exists.

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