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

[Daniel Wagner]

On Wed, Sep 28, 2022 at 09:55:11AM +0300, Sagi Grimberg wrote:
> 
> > In order to be able to test queue number changes we need to make sure
> > that the host reconnects.
> > 
> > The initial idea was to disable and re-enable the ports and have the
> > host to wait until the KATO timer expires and enter error
> > recovery. But in this scenario the host could see DNR for a connection
> > attempt which results in the host dropping the connection completely.
> > 
> > We can force to reconnect the host by deleting all controllers
> > connected to subsystem, which results the host observing a failing
> > command and tries to reconnect.
> 
> This looks like a change that attempts to fix a host issue from the
> target side... Why do we want to do that?

It's not a host issue at all. The scenario I'd like to test a when
target changes this property while the host is connected (e.g. software
updated -> new configuration). I haven't found a way to signal the host
to reset/reconnect from the target. Hannes suggested to delete all
controllers from the given subsystem which will trigger the recovery
process on the host on the next request. This makes this test work.

Though if you have a better idea how to signal the host to reconfigure
itself, I am glad to work on it.