[PATCH review 5/6] userns: Allow the userns root to mount ramfs.

[Serge E. Hallyn]

Quoting Eric W. Biederman (ebiederm at xmission.com):
> 
> There is no backing store to ramfs and file creation
> rules are the same as for any other filesystem so
> it is semantically safe to allow unprivileged users
> to mount it.
> 
> The memory control group successfully limits how much
> memory ramfs can consume on any system that cares about
> a user namespace root using ramfs to exhaust memory
> the memory control group can be deployed.
> 
> Signed-off-by: "Eric W. Biederman" <ebiederm at xmission.com>

Acked-by: Serge Hallyn <serge.hallyn at canonical.com>

> ---
>  fs/ramfs/inode.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
> index eab8c09..c24f1e1 100644
> --- a/fs/ramfs/inode.c
> +++ b/fs/ramfs/inode.c
> @@ -260,6 +260,7 @@ static struct file_system_type ramfs_fs_type = {
>  	.name		= "ramfs",
>  	.mount		= ramfs_mount,
>  	.kill_sb	= ramfs_kill_sb,
> +	.fs_flags	= FS_USERNS_MOUNT,
>  };
>  static struct file_system_type rootfs_fs_type = {
>  	.name		= "rootfs",
> -- 
> 1.7.5.4