losetup mounts disk image as one device. How to loopback the partitions seperately?
Add the -P switch to losetup, like this:
losetup -Pf disk.img
This will create loop devices for each partition, like /dev/loop8p3. Note that partition scanning depends on sector sizes, which are assumed to be 512 by default. If the image was made from something which had different sector sizes, then you need to specify the --sector-size switch as well.