Use MSD to pass data from Host to Device

I’m stuck on this and while I don’t expect anyone to answer, I would greatly appreciate it.
I understand that the g_multi gadget has backing storage for the mass storage device in /var/cache/doc-beaglebone-getting-started.
I know that if I want to read from this storage, I have to do it while the storage is not in use.
I think I should be able to mount and read the backing storage before is run (this is the code which configures the gadget and enables it). However, when I do this the contents of
the backing storage disappear. What could be wrong?

For reference, this is how i’m attempting to read the storage:
I edited making usb_ms_ro=0
I pointed /var/local/bb_usb_mass_storage.img to another file: /root/data/backing_storage - a fat32 partition with 512 byte sectors starting at sector 2048

I created the following directory: /mnt/loop

losetup -o 1048576 /dev/loop0 /root/data/backing_file

mkdosfs -F 32 /dev/loop0

mount -t vfat /dev/loop0 /mnt/loop

ls /mnt/loop >> /var/log/messages

umount /dev/loop0
losetup -d /dev/loop0