start or reset. Also add a notifier for NVMe consumers for controller fail
conditions and plumb this notifier for nvd(4) to destroy the associated
GEOM disks when a failure occurs.
This requires a bit of work to cover the races when a consumer is sending
I/O requests to a controller that is transitioning to the failed state. To
help cover this condition, add a task to defer completion of I/Os submitted
to a failed controller, so that the consumer will still always receive its
completions in a different context than the submission.
Sponsored by: Intel
Reviewed by: carl
232e2edb6c