LU-2744 build: fix 'data race condition' issues

LU-2744 build: fix 'data race condition' issues

Fix 'data race condition' defects found by Coverity version
6.5.0:
Data race condition (MISSING_LOCK)
Accessing variable without holding lock. Elsewhere,
this variable is accessed with lock held.

Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net>
Change-Id: I706e4facef8d29a3b072f977c7a903e6c1772b71
Reviewed-on: http://review.whamcloud.com/6568
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>