Smoke Barrier Door
Awl flyer,
The Smoke Barrier Door between the main deck and upper deck won't do much to stop smoke migrating upward, in my opinion.
The curtain, weather open or closed, won't stop smoke.
Plus, if a fire burns underneath the upper deck (from what I read in this thread the fire could have started in front of the wing), it could burn through the floor and allow smoke on the upper deck. Plus there are many pressure relieve panels between Main and Upper deck, allowing smoke to move up.
Slightly over pressurizing the Cockpit might help keeping smoke out. But in that case some kind of door would have to be installed.
A complication would be relieving pressure between Cockpit and Upper & Main deck in case of decompression.
I think the consensus here is that you cannot 100% prevent undeclared DG in freight. Fact of life.
And fighting a fire on the freight deck of an aircraft, between pallets, is a lost battle, unless you get there at the very beginning. Even if you do have supernumerary crew for it.
So the main thing you need to do is get on the surface, ASAP. 10-15 minutes are the numbers I hear.
And then prepare for the case where you won't be able to see anything.
PF; Prepare the nav set up immediately, while you can still see. Closest airport with an ILS, set it up in the FMS and select direct, engage LNAV. Dial in IAA and set up a descent to it. Let the A/P do the work.
PM; do as much from the QRH while you still can.
And switch to guard, because every tower and center has it and perhaps you won't be able to switch frequencies later on.
Plan an auto land with max auto brakes. Configure in time, if you suspect you will lose systems.
Visualise your escape route from the Cockpit beforehand.
If you think you won't make it to an airport and you are over water; a slow descent for the last 500' for a ditching, and lots of luck.