CHERRY-PICK: mount-encrypted: issue sync()s between umount stages

In an effort to reduce the chances of a kernel bug wrecking filesystems
during encrypted-stateful shutdown, add explicit sync() calls during
shutdown.

BUG=chrome-os-partner:17610
TEST=link build, shutdown with simulated panic in LOOP_CLR_FD results in
 successful journal replays
BRANCH=None

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/43736
Reviewed-by: Grant Grundler <grundler@chromium.org>

Change-Id: Ifd2a5f70c325d0a24296fed5e8f303838e25c36c
(cherry picked from ToT commit e6cf2c21a1cd6fc46b6adcaadc865e2f8bd4874e)
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/43837
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
1 file changed