After the latest kernel update (4.1.26-21-default -> 4.1.27-24-default) I'm
unable to list directories and files in the home directory. The 'ls' command
returns "Wrong medium type" and the following stuff:
------
Error opening lower file for lower_dentry [0xffff880241e85480] and lower_mnt
[0xffff88025380af20]; rc = [-124]
ecryptfs_open: Error attempting to initialize the lower file for the dentry
with name [pulse]; rc = [-124]
------
The files can be blindly addressed if you know the correct path. After booting
to the older kernel (4.1.26-21-default) everything works correctly again.

The following link points at the same problem and contains some explanations.
https://github.com/NixOS/nixpkgs/issues/16766