Pull two overlayfs fixes from Miklos Szeredi:
"Overlayfs rmdir() failed to check for emptiness in one case; this was
introduced in 4.0. The other bug was there since day one: failure to
mount if upper fs is full, which bit some OpenWRT folks"
* 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: mount read-only if workdir can't be created
ovl: don't remove non-empty opaque directory