After setting a path to a dasd offline at the SE, I/O hangs on that
dasd for 5 minutes, then continues.
I/O for which an interrupt will not be reported after the channel
path has been disabled was not terminated by the common I/O layer,
causing the dasd MIH to hit after 5 minutes.

Be more aggressive in terminating I/O after setting a channel path
offline. Also make sure to generate a fake irb if the device
driver issues an I/O request after being notified of the killed
I/O and clear residual information from the irb before trying to
start the delayed verification.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>