[PATCH] nvme-core: update NS Attr Changed AEN handling for ANA group

[Keith Busch]

On Wed, Dec 09, 2020 at 08:58:06PM +0000, Knight, Frederick wrote:
> So for case 2 (the attach), there are 2 AENs for effectively the same event.  This is where we are at with the existing text.
> 
> Whether this is what the hosts want, that is a good question. What changes are desired (if any)?

Linux hosts currently want an ANA AEN anytime the host needs to refresh
the ANA log. That includes any condition that adds groups that didn't
exist from the host's previous reading.

If the Namespace Attach occurs to an ANA group the host already knows
about, then you don't need to send an ANA AEN because there's nothing
new in the log that the host requires. You just need to send the NS
Notify AEN.

But if a side effect of attaching a namespace results in a new ANA group
becoming visible to the host, then that group creation is considered a
separate event, so the host wants both AENs. I believe this is where
Christoph is trying to steer the interpretation and the text.