Solution for mount fails with "No such file or directory"

If you find yourself stuck in an initramfs Busybox shell, trying to manually mount the root filesystem (using a command such as mount /dev/mapper/yourrootfs /root) and getting a confusing "No such file or directory" message in response, then check whether the appropriate kernel module for your filesystem type is loaded (i.e. run "lsmod"). Something as simple as "modprobe ext2" before the mount command might be the entire solution you need (it was for me today, in context of an interrupted Debian dist-upgrade from squeeze to wheezy)!