RFR 8165852: (fs) Mount point not found for a file which is present in overlayfs

[Brian Burkhalter]

The proposed fix [1] for [2] based on [3] is to check /proc/mounts entries both when a device ID boundary is reached and at the end of the file hierarchy upward traversal, i.e., when the parent is null. The change has been verified to work in an ubuntu:16.04 Docker container and does not break existing core regression tests.

Thanks,

Brian

[1] http://cr.openjdk.java.net/~bpb/8165852/webrev.00/
[2] https://bugs.openjdk.java.net/browse/JDK-8165852
[3] http://mail.openjdk.java.net/pipermail/nio-dev/2017-September/004563.html