Deal with dmsg warning/errors

```
[ +0.002145] overlayfs: upperdir is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.
[ +0.000003] overlayfs: workdir is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.
```
(nested mounts)

`[ +0.013092] overlayfs: failed to clone lowerpath` we're catching this so it's fine with nested mounts

```
[ +0.000687] overlayfs: failed to set xattr on upper
[ +0.000001] overlayfs: try mounting with 'userxattr' option
```
fixable with `-o userxattr`