[PATCH-4.5-v3 2/5] NVMe: Fix namespace removal deadlock

[Christoph Hellwig]

On Wed, Feb 17, 2016 at 11:36:52AM -0700, Keith Busch wrote:
> This patch makes nvme namespace removal lockless. It is up to the caller
> to ensure no active namespace scanning is occuring.

I wonder if it wouldn't be safer in the long run if we just switch
to RCU locking - that way we don't need any locks in the readers, they
can just grab a reference under rcu_read_lock(), and we don't need to
rely in implicit serialization for the updaters.