[PATCH V6] nvme-core: use xarray for ctrl ns tracking

[hch at lst.de]

On Wed, Jun 09, 2021 at 08:48:10PM +0000, Chaitanya Kulkarni wrote:
> 
> This is to void the another call to the synchronize_rcu(),
> 
> I'll add a second call to synchronize_rcu() and keep the original
> position.

Or document why this is changed in the commit log, that is what it is
for.