[parted-devel] [PATCH v2] libparted: Fixed bug in initializing FBA devices

[Nageswara R Sastry]

Subject: [PATCH v2] libparted: Fixed bug in initializing FBA devices

From: Nageswara R Sastry <rnsastry at linux.vnet.ibm.com>

Fixed Block Access (FBA) DASDs are mainframe-specific disk devices
that are layed out as a sequence of 512-byte sectors. In contrast
to ECKD DASDs, these disks do not require formatting and resemble
the LBA layout of non-mainframe disks. Despite this resemblance,
the Linux kernel applies special handling during partition detection
for FBA DASDs, resulting in a single, immutable partition being
reported.
While actual FBA DASD hardware is no longer available, the z/VM
hypervisor can simulate FBA DASD disks, backed by either ECKD or
SCSI devices.

* libparted/labels/dasd.c (dasd_alloc): For FBA devices corrected the
initilization and calling dasd_read in the case of FBA devices to
set the implicit partition.


Signed-off-by: Nageswara R Sastry <rnsastry at linux.vnet.ibm.com>
---
 libparted/labels/dasd.c |   23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

--- a/libparted/labels/dasd.c
+++ b/libparted/labels/dasd.c
@@ -150,9 +150,19 @@ dasd_alloc (const PedDevice* dev)
 		return NULL;
 	}

-	/* CDL format, newer */
-	disk_specific->format_type = 2;
-	disk_specific->label_block = 2;
+	/* Correct assignment is required to pass the correct values
+	   according to the disk type. For FBA disk values are '1'
+           and for CDL formatted disk values are '2'*/
+	struct fdasd_anchor anchor;
+	fdasd_initialize_anchor(&anchor);
+	fdasd_get_geometry(disk->dev, &anchor, arch_specific->fd);
+	if (anchor.FBA_layout == 1) {
+		disk_specific->format_type = 1;
+		disk_specific->label_block = 1;
+	}else{
+		disk_specific->label_block = 2;
+		disk_specific->format_type = 2;
+	}

 	/* Setup volume label (for fresh disks) */
 	snprintf(volser, sizeof(volser), "0X%04X", arch_specific->devno);
@@ -163,6 +173,13 @@ dasd_alloc (const PedDevice* dev)
 	vtoc_set_cchhb(&disk_specific->vlabel.vtoc,
 		       VTOC_START_CC, VTOC_START_HH, 0x01);

+	/* Calling dasd_read is required for FBA disks to set
+	   the implicit partition */
+	if (anchor.FBA_layout == 1) {
+		if (!dasd_read(disk))
+			dasd_free(disk);
+	}
+
 	return disk;
 }