The curious thing is that a couple of weeks ago, I used parted to resize a GPT partition under Fedora 23, then resized the LUKS device, then the PV. I didn't have to reboot. I don't seem to be able to do the same thing under CentOS 7, though that test system didn't use a LUKS encrypted partition. I don't know why this is possible in some circumstances and not others. Anyone else?