Mounting filesystem image from physical memory in C

I'm booting linux with my own init executable which is written in C. As a part of my init process, I want to mount a custom filesystem image which was preloaded to the physical memory (let's say at address 0xFFFF0000).

The type of the filesystem image can be changed to whatever will work, as far as it has POSIX (like ext4).

How can I mount the image successfully entirely from physical memory using C code?

What I've tried:

• Mounting from /dev/mem (as seen here: http://www.qnx.com/developers/docs/qnxcar2/index.jsp?topic=%2Fcom.qnx.doc.neutrino.technotes%2Ftopic%2Fmultiple_Mounting.html), it doesn't fail but I don't see the wanted files from the image in the target directory. Moreover, this method uses char device so ext4 doesn't work since it need a block device.
• Building another image file in the rootfs and filling it with the raw data from 0xFFFF0000 and mounting it. It's dumb and won't save changes to the image itself upon restarting.

Note: I've enabled loop devices for my system if needed