libparted: add support for implicit FBA DASD partitions

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

This patch adds support for recognizing FBA DASD partitions
to parted.

Signed-off-by: Nageswara R Sastry <rnsastry@linux.vnet.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>

3 files changed, 61 insertions, 9 deletions

diff --git a/include/parted/fdasd.in.h b/include/parted/fdasd.in.h
index ac30134..a755246 100644
--- a/include/parted/fdasd.in.h
+++ b/include/parted/fdasd.in.h
@@ -194,6 +194,8 @@ typedef struct fdasd_anchor {
 	volume_label_t   *vlabel;
 	config_data_t confdata[USABLE_PARTITIONS];
 	struct fdasd_hd_geometry geo;
+	unsigned int label_block;
+	unsigned int FBA_layout;
 } fdasd_anchor_t;
 
 enum offset {lower, upper};
diff --git a/libparted/labels/dasd.c b/libparted/labels/dasd.c
index a769866..b4e80b1 100644
--- a/libparted/labels/dasd.c
+++ b/libparted/labels/dasd.c
@@ -71,6 +71,7 @@ typedef struct {
 
 typedef struct {
 	unsigned int format_type;
+	unsigned int label_block;
 	volume_label_t vlabel;
 } DasdDiskSpecific;
 
@@ -151,6 +152,7 @@ dasd_alloc (const PedDevice* dev)
 
 	/* CDL format, newer */
 	disk_specific->format_type = 2;
+	disk_specific->label_block = 2;
 
 	/* Setup volume label (for fresh disks) */
 	snprintf(volser, sizeof(volser), "0X%04X", arch_specific->devno);
@@ -226,7 +228,9 @@ dasd_probe (const PedDevice *dev)
 
 	fdasd_check_api_version(&anchor, arch_specific->fd);
 
-	if (fdasd_check_volume(&anchor, arch_specific->fd))
+	/* Labels are required on CDL formatted DASDs. */
+	if (fdasd_check_volume(&anchor, arch_specific->fd) &&
+	    anchor.FBA_layout == 0)
 		goto error_cleanup;
 
 	fdasd_cleanup(&anchor);
@@ -273,17 +277,53 @@ dasd_read (PedDisk* disk)
 	fdasd_initialize_anchor(&anchor);
 
 	fdasd_get_geometry(disk->dev, &anchor, arch_specific->fd);
+	disk_specific->label_block = anchor.label_block;
+
+	if ((anchor.geo.cylinders * anchor.geo.heads) > BIG_DISK_SIZE)
+		anchor.big_disk++;
 
 	/* check dasd for labels and vtoc */
-	if (fdasd_check_volume(&anchor, arch_specific->fd))
-		goto error_close_dev;
+	if (fdasd_check_volume(&anchor, arch_specific->fd)) {
+		DasdPartitionData* dasd_data;
+
+		/* Kernel partitioning code will report 'implicit' partitions
+		 * for non-CDL format DASDs even when there is no
+		 * label/VTOC.  */
+		if (anchor.FBA_layout == 0)
+			goto error_close_dev;
+
+		disk_specific->format_type = 1;
+
+		/* Register implicit partition */
+		ped_disk_delete_all (disk);
+
+		start = (PedSector) arch_specific->real_sector_size /
+			(PedSector) disk->dev->sector_size *
+			(PedSector) (anchor.label_block + 1);
+		end = disk->dev->length - 1;
+		part = ped_partition_new (disk, PED_PARTITION_NORMAL, NULL,
+					  start, end);
+		if (!part)
+			goto error_close_dev;
+
+		part->num = 1;
+		part->fs_type = ped_file_system_probe (&part->geom);
+		dasd_data = part->disk_specific;
+		dasd_data->raid = 0;
+		dasd_data->lvm = 0;
+		dasd_data->type = 0;
+
+		if (!ped_disk_add_partition (disk, part, NULL))
+			goto error_close_dev;
+
+		fdasd_cleanup(&anchor);
+
+		return 1;
+	}
 
 	/* Save volume label (read by fdasd_check_volume) for writing */
 	memcpy(&disk_specific->vlabel, anchor.vlabel, sizeof(volume_label_t));
 
-	if ((anchor.geo.cylinders * anchor.geo.heads) > BIG_DISK_SIZE)
-		anchor.big_disk++;
-
 	ped_disk_delete_all (disk);
 
 	bool is_ldl = strncmp(anchor.vlabel->volkey,
@@ -348,7 +388,7 @@ dasd_read (PedDisk* disk)
 			    / (long long) disk->dev->sector_size
 			    * (long long) (cms_ptr->block_count - 1) - 1;
 
-		part = ped_partition_new (disk, PED_PARTITION_PROTECTED, NULL, start, end);
+		part = ped_partition_new (disk, PED_PARTITION_NORMAL, NULL, start, end);
 		if (!part)
 			goto error_close_dev;
 
@@ -923,7 +963,12 @@ dasd_alloc_metadata (PedDisk* disk)
 	   the start of the first partition */
 	if (disk_specific->format_type == 1) {
 	        part = ped_disk_get_partition(disk, 1);
-		vtoc_end = part->geom.start - 1;
+		if (part)
+			vtoc_end = part->geom.start - 1;
+		else
+			vtoc_end = (PedSector) arch_specific->real_sector_size /
+				   (PedSector) disk->dev->sector_size *
+				   (PedSector) disk_specific->label_block;
 	}
 	else {
                 if (disk->dev->type == PED_DEVICE_FILE)
@@ -943,7 +988,7 @@ dasd_alloc_metadata (PedDisk* disk)
 		goto error;
 	}
 
-	if (disk_specific->format_type == 1) {
+	if (disk_specific->format_type == 1 && part) {
 	   /*
 	      For LDL or CMS there may be trailing metadata as well.
 	      For example: the last block of a CMS reserved file,
diff --git a/libparted/labels/fdasd.c b/libparted/labels/fdasd.c
index e235dd3..f92065f 100644
--- a/libparted/labels/fdasd.c
+++ b/libparted/labels/fdasd.c
@@ -721,6 +721,7 @@ fdasd_check_volume (fdasd_anchor_t *anc, int fd)
 	unsigned long b = -1;
 	char str[LINE_LENGTH];
 
+	memset(v, 0, sizeof(volume_label_t));
 	vtoc_read_volume_label (fd, anc->label_pos, v);
 
 	if (strncmp(v->vollbl, vtoc_ebcdic_enc ("VOL1", str, 4), 4) == 0) {
@@ -800,6 +801,8 @@ fdasd_get_geometry (const PedDevice *dev, fdasd_anchor_t *anc, int f)
 	    dasd_info.dev_type = 13200;
 	    dasd_info.label_block = 2;
 	    dasd_info.devno = 513;
+	    dasd_info.label_block = 2;
+	    dasd_info.FBA_layout = 0;
 	} else {
 		if (ioctl(f, HDIO_GETGEO, &anc->geo) != 0)
 			fdasd_error(anc, unable_to_ioctl,
@@ -820,6 +823,8 @@ fdasd_get_geometry (const PedDevice *dev, fdasd_anchor_t *anc, int f)
 	anc->label_pos  = dasd_info.label_block * blksize;
 	anc->devno      = dasd_info.devno;
 	anc->fspace_trk = anc->geo.cylinders * anc->geo.heads - FIRST_USABLE_TRK;
+	anc->label_block = dasd_info.label_block;
+	anc->FBA_layout = dasd_info.FBA_layout;
 }
 
 /*