Re: [PATCH 5/8] nvme: sync the namespace scanning during ctrl start

[Christoph Hellwig <hch@lst.de>]

On Wed, Jan 31, 2024 at 02:40:07PM +0200, Sagi Grimberg wrote:
> Max, I mentioned that I don't think it is a good idea to change the
> existing behavior, because of time, because its preventing forward
> progress, because it doesn't fix an existing issue, etc.
> I also don't think its needed.
>
> I think the original intent of this as made in discussions in the past was 
> to simply fail upon PI mismatch when nvme_init_ns_head and
> nvme_validate_ns.

Yes.

>> I think that AEN and reset flows are a bit different. The controller is 
>> free to be modified at any time (even when no Admin queue is opened from 
>> the host). It may have out-of-band management interface (for example the 
>> nvmet cli) and may not have any association (AQ) to the host to notify on 
>> changes.
>
> Fundamentally things can change before the host knows about it, hence
> I don't get the claim that somehow the host violates the spec.
>
> Do others think that now namespace scanning should block
> nvme_ctrl_start ? I personally don't but I'm open to justification
> for why it is the right thing to do.

Hell no.