How to access "upper" directory of overlayfs programatically

[Jonathan Busby <jdb2@pobox.com>]

Hello. I'm new to this list and I don't know if this is the right forum 
for my question, but, I've asked this same question on many forums and 
never received an answer -- please don't flame me.

I have a Debian based Linux live system which is running out of RAM and 
was booted without the "persistent" boot option, so the capser-rw 
filesystem was never created.

I wish to gain access to the "upper" directory of the overlayfs 
filesystem in the casper init scripts initramfs "/cow/upper" filesystem 
so that I may programatically save the filesystem, hopefully without 
having to re-implement cp.

I know how to commit the changes of a Debian based live CD session to a 
storage device, but only if the live session in question was booted with 
the "persistent" option.

I've looked at the overlayfs source code but I still can't figure out 
how to accomplish what I want.

I'm sorry if this is  stupid question -- hopefully it's not.

Thank you,

Jonathan