fail in nvmecontrol(8).
While here, use consistent checks of return values from stat, open and
ioctl.
Sponsored by: Intel
Suggested by: carl
Reviewed by: carl
invoke it from nvmecontrol(8).
Controller reset will be performed in cases where I/O are repeatedly
timing out, the controller reports an unrecoverable condition, or
when explicitly requested via IOCTL or an nvme consumer. Since the
controller may be in such a state where it cannot even process queue
deletion requests, we will perform a controller reset without trying
to clean up anything on the controller first.
Sponsored by: Intel
Reviewed by: carl
