[PATCH] s390: enable write barriers in the dasd driver

The DASD device driver never reorders the I/O requests and relies on the
hardware to write all data to nonvolatile storage before signaling a
successful write.  Hence, the only thing we have to do to support write
barriers is to set the queue ordered flag.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/s390/block/dasd.c

@@ -1635,6 +1635,7 @@ dasd_setup_queue(struct dasd_device * device)
 	blk_queue_max_hw_segments(device->request_queue, -1L);
 	blk_queue_max_segment_size(device->request_queue, -1L);
 	blk_queue_segment_boundary(device->request_queue, -1L);
+	blk_queue_ordered(device->request_queue, 1);
 }
 
 /*