fs-core-modules-4.4.0-21-power software package provides Base filesystem modules, you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install fs-core-modules-4.4.0-21-power
fs-core-modules-4.4.0-21-power is installed in your system.
Make ensure the fs-core-modules-4.4.0-21-power package were installed using the commands given below,
$ sudo dpkg-query -l | grep fs-core-modules-4.4.0-21-power*
You will get with fs-core-modules-4.4.0-21-power package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | debian-installer udeb packages |
| Package | fs-core-modules-4.4.0-21-power |
| Version | 4.4.0-21.37 |
| Description | Base filesystem modules |
| Sub Section | Debian-installer |