[PATCH v2] nvme: avoid race in shutdown namespace removal

[Christoph Hellwig]

On Thu, Sep 02, 2021 at 11:20:02AM +0200, Daniel Wagner wrote:
> When we remove the siblings entry, we update ns->head->list, hence we
> can't separate the removal and test for being empty. They have to be
> in the same critical section to avoid a race.
> 
> To avoid breaking the refcounting imbalance again, add a list empty
> check to nvme_find_ns_head.

Hannes, can you look over this and run your tests on it?