Comment 0 for bug 22474

It seems that gparted does not like working with /dev/mapper devices. I believe
it has something to do with the fact that after updating the partition table, it
issues an ioctl to ask the kernel to re-read the partition table and fix up the
partition devices, but this operation is not supported on /dev/mapper devices.

The symtoms that I have seen so far include:

1) Attempting to resise a partition ( NTFS in this case ) simply did nothing.
When I clicked apply, it appeared to work for a few seconds, then just stopped
with no error message. No changes were made to the disk.

2) If you attempt to create a new partition and format it, the new partition
gets created, but the format fails because the ioctl fails and the new partition
device does not exist. I had to only add the partition, apply, then run the
dmraid utility to re-read the partition table and create the new partition
device, then refresh gparted and then format.