Re: [PATCH V3 0/3] Ensure ordered namespace registration during async scan

[Keith Busch <kbusch@kernel.org>]

On Fri, Jun 19, 2026 at 07:59:43AM +0200, Hannes Reinecke wrote:
> The problem here is namespace lifetime. The ns_ida is only ever released
> at the very last step, so the 'number' of the namespace will only be freed
> once all references to the namespace are dropped.
> So if you were trying to keep the namespace number ordered you would
> have to delay the creation of the namespace until that point, and you
> would induce a serialization between deletion and creation.

Under the proposed scheme, there is no ns_ida. You just use the NSID of
the namespace, and that's it. You have to ensure that del_gendisk
completed on all heads and paths that was using it prior to bringing up
the next one, but that's not really a problem.

The problem I recall has something to do with the nsid not being a
consistent value when migrating a namespace to another array or
something like that. Not that we currently have proper support for such
a thing...