KVM images (qcow, qcow2) implement methods like appliances, snapshots, copy-on-write and grow-on-demand. It is therefore not possible to directly mount such images e.g. using losetup. If you do, you will probably destroy your image. You need to use guestmount to mount the final resulting filesystem.
E.g. mount the first partition in a Windows XP virtual image read-only to /mnt:
$ guestmount -a /var/lib/libvirt/images/winxp.qcow2 -m /dev/sda1 --ro /mnt febootstrap-supermin-helper: ext2: parent directory not found: /lib: File not found by ext2_lookup libguestfs: error: external command failed, see earlier error messages
Not found? Update:
$ update-guestfs-appliance febootstrap: error: /etc/init.d/rc is a config file which is listed in two packages (openrc_0.13.1-4_amd64.deb, sysv-rc_2.88dsf-58_all.deb)
Rather cryptic, what’s actually wrong here. However, for some reason, this solves the issue:
$ apt-get install libguestfs-tools -y