[S390] dasd: use correct label location for diag fba disks

Partition boundary calculation fails for DASD FBA disks under the
following conditions:
- disk is formatted with CMS FORMAT with a blocksize of more than
  512 bytes
- all of the disk is reserved to a single CMS file using CMS RESERVE
- the disk is accessed using the DIAG mode of the DASD driver

Under these circumstances, the partition detection code tries to
read the CMS label block containing partition-relevant information
from logical block offset 1, while it is in fact located at physical
block offset 1.

Fix this problem by using the correct CMS label block location
depending on the device type as determined by the DASD SENSE ID
information.
Signed-off-by: NPeter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

fs/partitions/ibm.c

@@ -74,6 +74,7 @@ int ibm_partition(struct parsed_partitions *state)
 	} *label;
 	unsigned char *data;
 	Sector sect;
+	sector_t labelsect;
 
 	res = 0;
 	blocksize = bdev_logical_block_size(bdev);
@@ -97,11 +98,20 @@ int ibm_partition(struct parsed_partitions *state)
 	    ioctl_by_bdev(bdev, HDIO_GETGEO, (unsigned long)geo) != 0)
 		goto out_freeall;
 
+	/*
+	 * Special case for FBA disks: label sector does not depend on
+	 * blocksize.
+	 */
+	if ((info->cu_type == 0x6310 && info->dev_type == 0x9336) ||
+	    (info->cu_type == 0x3880 && info->dev_type == 0x3370))
+		labelsect = info->label_block;
+	else
+		labelsect = info->label_block * (blocksize >> 9);
+
 	/*
 	 * Get volume label, extract name and type.
 	 */
-	data = read_part_sector(state, info->label_block*(blocksize/512),
-				&sect);
+	data = read_part_sector(state, labelsect, &sect);
 	if (data == NULL)
 		goto out_readerr;