[SCSI] zfcp: Flush SCSI registration work when adding unit

When configuring a LUN for use in zfcp, flush the SCSI work to ensure
the SCSI device has been created before returning. This means that a
configuration procedure can run these commands in a script and the
SCSI device is available immediately after the unit_add:

echo 1 > /sys/bus/ccw/drivers/zfcp/0.0.181d/online
echo 0x401040C300000000 > \
        /sys/bus/ccw/drivers/zfcp/0.0.181d/0x500507630313c562/unit_add
lsscsi

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/s390/scsi/zfcp_sysfs.c

@@ -224,6 +224,7 @@ static ssize_t zfcp_sysfs_unit_add_store(struct device *dev,
 
 	zfcp_erp_unit_reopen(unit, 0, "syuas_1", NULL);
 	zfcp_erp_wait(unit->port->adapter);
+	flush_work(&unit->scsi_work);
 	zfcp_unit_put(unit);
 out:
 	mutex_unlock(&zfcp_data.config_mutex);