LU-3054 build: fix 'program hangs' errors

LU-3054 build: fix 'program hangs' errors

Fix 'program hangs' defects found by Coverity version 6.5.1:
Missing unlock (LOCK)
Returning without unlocking.

Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net>
Change-Id: I96c2bb05a5875ed493ebe99587e9901baea80fc8
Reviewed-on: http://review.whamcloud.com/5870
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Keith Mannthey <DELETED>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>