tree acba53f712c463a2bba3416145e705876a8d6c90
parent b3c6761d9b5cc82deea7416d11c2118f6380e99c
author Eric W. Biederman <ebiederm@xmission.com> 1359160330 -0800
committer Eric W. Biederman <ebiederm@xmission.com> 1359267785 -0800

userns: Allow the userns root to mount tmpfs.

There is no backing store to tmpfs and file creation rules are the
same as for any other filesystem so it is semantically safe to allow
unprivileged users to mount it.  ramfs is safe for the same reasons so
allow either flavor of tmpfs to be mounted by a user namespace root
user.

The memory control group successfully limits how much memory tmpfs can
consume on any system that cares about a user namespace root using
tmpfs to exhaust memory the memory control group can be deployed.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>