[parted-devel] [PATCH] libparted: Fixed bug in initializing and re-reading partition table of FBA devices

[Nageswara R Sastry]

Subject: [PATCH] libparted: Fixed bug in initializing and re-reading partition
table of FBA devices

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

Fixed Block Access (FBA) DASDs are mainframe-specific disk devices
that are layred 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.

This patch fixes the initialization of FBA DASD. For re-reading of FBA
partitions used the old BLKRRPART IOCTL. With the current blk_pg
IOCTL more hacking is required to re-read partitions from FBA devices.

* libparted/arch/linux.c (_disk_sync_part_table): For FBA devices
added BLKRRPART IOCTL to re-read kernel partition
* libparted/labels/dasd.c (dasd_alloc): For FBA devices corrected the
initialization.


Signed-off-by: Nageswara R Sastry <rnsastry at linux.vnet.ibm.com>
---
 libparted/arch/linux.c  |   31 +++++++++++++++++++++++++++++++
 libparted/labels/dasd.c |   16 +++++++++++++---
 2 files changed, 44 insertions(+), 3 deletions(-)

--- a/libparted/arch/linux.c
+++ b/libparted/arch/linux.c
@@ -2669,6 +2669,37 @@ _disk_sync_part_table (PedDisk* disk)
                         ret = 1;
 		free (bad_part_list);
         }
+        /* For FBA kind of devices it is required to re-read the partitions
+	   when this is not done the implicit partition is not identified by
+	   the kernel and device node is not created. */
+
+	#if defined __s390__ || defined __s390x__
+	LinuxSpecific*  arch_specific = LINUX_SPECIFIC (disk->dev);
+	int retry_count = 5;
+
+	if (disk->dev->type == PED_DEVICE_DASD  && lpn == 1) {
+		sync();
+		while (ioctl (arch_specific->fd, BLKRRPART)) {
+			retry_count--;
+			sync();
+			if (!retry_count) {
+				ped_exception_throw (
+				PED_EXCEPTION_WARNING,
+				PED_EXCEPTION_IGNORE,
+				_("WARNING: the kernel failed to re-read the "
+				"partition table on %s (%s).  As a result, it"
+				" may not reflect all of your changes until "
+				"after reboot."),
+				disk->dev->path, strerror (errno));
+				ret = 0;
+			goto cleanup;
+
+			}
+		}
+		ret = 1;
+	}
+	#endif
+
  cleanup:
         free (errnums);
         free (ok);
--- 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);