There was no validation for `docker run --tmpfs foo`. In this PR, only two obvious rules are implemented: - path must be absolute - path must not be "/" We should add more rules carefully. Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp> Upstream-commit: 4a8799dc0a000a74eae49a01b054ae687bc18f73 Component: engine