Re: [PATCH] nvme: Remove namespace when nvme_identify_ns_descs() failed

Keith Busch
2024-12-05T16:15:24Z

On Thu, Dec 05, 2024 at 01:30:39PM +0100, Hannes Reinecke wrote:
> On 12/4/24 17:39, Keith Busch wrote:
> > > 1) AEN triggers a rescan
> > > 2) List of active namespace is retrieved
> > > -> NSID A gets unmapped (or moved to another node in the cluster)
> > > 3) Scan of NSID A returns an error with DNR set.
> > > Without this patch we keep the namespace around, so eventually we'll
> > > trip over the 'non-matching UUID' check once the NSID is reused.
> >
> > I'm still not sure that makes sense. The target shouldn't attach the new
> > namespace until the host acknowledges the removal of the older NSID via
> > the Namespace Change List log. Until the log is read, the inventory for
> > removed namespaces should be latched. Otherwise, timing might remove+add
> > a specific NSID before the host requests the NS Descriptor for the
> > racing removal, then it would just get the "non-matching UUID" issue
> > anyway.
>
> But we read the Namespace Change List log in step 2)
> (Not that we're doing anything with it, but that's another story...)
> Hmm?

Indeed. So maybe we should just move the log page retrevial *after* we
scan the identify active namespace list processing?