[PATCH 10/17] nvme: switch controller refcounting to use struct device

[Christoph Hellwig]

On Thu, Oct 19, 2017 at 10:31:20AM +0300, Sagi Grimberg wrote:
> I don't think the fabrics device does not help us to keep the ctrl
> allocated until we finish removal.

All fabrics drivers grab an extra reference during ->create_ctrl,
which we will drop when releasing the file descriptor that we used
to create the device.

By the time we call ->delete_ctrl in nvmf_create_ctrl we must still
have that reference because we are still in a ->write call and thus
->release can't have been called yet.