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
