[PATCH-stable] nvme: protect against simultaneous shutdown invocations

[Keith Busch]

On Fri, Oct 06, 2017 at 09:05:57AM -0600, Keith Busch wrote:
> commit 77bf25ea70200cddf083f74b7f617e5f07fac8bd upstream
> 
> Back-ported to 4.4. The only difference is the file location of the
> struct definition that's adding the mutex.

Err, sorry, please disregard this one. There is a mistake in the back
port that will break. Will send out the correct version.