[S390] dasd: add large volume support

The dasd device driver will now support ECKD devices with more then
65520 cylinders.
In the traditional ECKD adressing scheme each track is addressed
by a 16-bit cylinder and 16-bit head number. The new addressing
scheme makes use of the fact that the actual number of heads is
never larger then 15, so 12 bits of the head number can be redefined
to be part of the cylinder address.

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index 4a39084..29991a9 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/drivers/s390/block/dasd_int.h
@@ -378,7 +378,7 @@
 	struct block_device *bdev;
 	atomic_t open_count;
 
-	unsigned long blocks;	   /* size of volume in blocks */
+	unsigned long long blocks; /* size of volume in blocks */
 	unsigned int bp_block;	   /* bytes per block */
 	unsigned int s2b_shift;	   /* log2 (bp_block/512) */