runsc: Mount "mandatory" mounts right after mounting the root.

The /proc and /sys mounts are "mandatory" in the sense that they should be
mounted in the sandbox even when they are not included in the spec. Runsc
treats /tmp similarly, because it is faster to use the internal tmpfs
implementation instead of proxying to the host.

However, the spec may contain submounts of these mandatory mounts (particularly
for /tmp). In those cases, we must mount our mandatory mounts before the
submount, otherwise the submount will be masked.

Since the mandatory mounts are all top-level directories, we can mount them
right after the root.

PiperOrigin-RevId: 203145635
Change-Id: Id69bae771d32c1a5b67e08c8131b73d9b42b2fbf

0 files changed, 0 insertions, 0 deletions