The kpartx command fails to add parition mapping to multipath devices when using partition delimiter 'p'

Issue

• Two multipath devices. The below example uses mpathd and mpathdp. These are aliases in this case but the same issue is reproducable with user friendly names.

mpathd (13ET     00013001) dm-8 IET,VIRTUAL-DISK
size=4.0G features='0' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
  |- 4:0:0:1 sde 8:64  active ready running
  |- 6:0:0:1 sdg 8:96  active ready running
  `- 5:0:0:1 sdi 8:128 active ready running
mpathdp (15ET     40010002) dm-9 IET,VIRTUAL-DISK
size=4.0G features='0' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
  |- 4:0:0:2 sdf 8:80  active ready running
  |- 5:0:0:2 sdj 8:144 active ready running
  `- 6:0:0:2 sdh 8:112 active ready running

• A look at the current mappings. Please note that mpathdp1 partitition is for mpathd, not mpathdp.

[root@rhel6a ~]# ls -l /dev/mapper/mpath*
lrwxrwxrwx 1 root root 7 Jul  1 12:08 /dev/mapper/mpathd -> ../dm-9
lrwxrwxrwx 1 root root 7 Jul  1 12:08 /dev/mapper/mpathdp -> ../dm-8
lrwxrwxrwx 1 root root 8 Jul  1 12:08 /dev/mapper/mpathdp1 -> ../dm-10        

[root@rhel6a ~]# parted /dev/mapper/mpathd print
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpathd: 4291MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      32.3kB  4285MB  4285MB  primary

[root@rhel6a ~]# parted /dev/mapper/mpathdp print
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpathdp: 4291MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start  End  Size  Type  File system  Flags

[root@rhel6a ~]# parted /dev/mapper/mpathdp print
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpathdp: 4291MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start  End  Size  Type  File system  Flags

• Add a new partition to mpathdp.

[root@rhel6a ~]# fdisk /dev/mapper/mpathdp

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-521, default 1): 
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-521, default 521): 
Using default value 521

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

• Use kpartx to add partition.

[root@rhel6a ~]# kpartx -av /dev/mapper/mpathdp
add map mpathdp1 (253:10): 0 8369802 linear /dev/mapper/mpathdp 63

[root@rhel6a ~]# ls -l /dev/mapper/mpath*
lrwxrwxrwx 1 root root 7 Jul  1 12:12 /dev/mapper/mpathd -> ../dm-9
lrwxrwxrwx 1 root root 7 Jul  1 12:14 /dev/mapper/mpathdp -> ../dm-8
lrwxrwxrwx 1 root root 8 Jul  1 12:14 /dev/mapper/mpathdp1 -> ../dm-10

• As you can see, we get an entry for mpathdp1, which is the partition for mpathd, not mpathdp. It seems we should get the device mpathdpp1. However this is not the case, when we use the kpartx command, it will not add the partition delimeter by default. For example, when we run kpartx -av on mpathx, we are telling it to make mpathx1, not mpathxp1. Note the lack of the partition delimiter. So, in our example we're trying to make a partitition mapping name that is already present.