kpartx bug fixes for dos extended partition [2/4]

["Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>]

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Hi Christophe,

kpartx usually doesn't create a mapping for extended partition.
However, it does if it's empty.
It's harmless but not consistent.
Attached patch makes it consistent by not creating a mapping
even when the extended partition is empty.

Please consider to apply.

If you have logical partitions in extended partition:
  # parted /dev/sdc p
  Disk geometry for /dev/sdc: 0.000-34686.000 megabytes
  Disk label type: msdos
  Minor    Start       End     Type      Filesystem  Flags
  1          7.844     31.376  extended
  5          7.875     23.532  logical

No mapping is created for extended partition:
  # dmsetup table|grep sdc|sort
  sdc5: 0 32067 linear 8:32 16128

However, if the extended partition is empty:
  # parted /dev/sdc p
  Disk geometry for /dev/sdc: 0.000-34686.000 megabytes
  Disk label type: msdos
  Minor    Start       End     Type      Filesystem  Flags
  1          7.844     31.376  extended

The following mapping is created:
  # dmsetup table|grep sdc|sort
  sdc1: 0 48195 linear 8:32 16065

Thanks,
Nick



[-- Attachment #2: 02-kpartx-avoid-mapping-empty-extended-part.patch --]
[-- Type: text/x-patch, Size: 516 bytes --]

Don't create mapping for extended partition.

--- multipath-tools.orig/kpartx/dos.c	2005-12-02 01:33:41.000000000 +0900
+++ multipath-tools/kpartx/dos.c	2005-12-02 01:33:29.000000000 +0900
@@ -99,8 +99,11 @@ read_dos_pt(int fd, struct slice all, st
 				"dos_partition: too many slices\n");
 			break;
 		}
-		if (is_extended(p.sys_type))
+		if (is_extended(p.sys_type)) {
 			n += read_extended_partition(fd, &p, sp+n, ns-n);
+			/* hide the extended partition itself */
+			sp[i].size = 0;
+		}
 	}
 	return n;
 }

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