LU-903 ldlm: inode references moved to resource

LU-903 ldlm: inode references moved to resource

There is a race condition while get_attr after cancel_lru_locks
and sysctl drop_caches. ll_clear_inode clears l_ast_data for
ldlm lock and this lock can't be canceled because "inode == NULL".
ll_mdc_blocking_ast finds such lock. As result DCACHE_LUSTRE_INVALID
is not set and lookup returns wrong inode.

This patch moves inode structure reference to
"ldlm_lock::l_resource::lr_lvb_inode". This prevents from different
inode references for same resource's lock.

Xyratex-bug-id: MRP-338
Reviewed-by: Vitaly Fertman <vitaly_fertman@xyratex.com>
Reviewed-by: Alexey Lyashkov <alexey_lyashkov@xyratex.com>
Signed-off-by: Artem Blagodarenko <artem_blagodarenko@xyratex.com>
Change-Id: I4105b2aec38c90d3f5a20d1498a563192a74de55
Reviewed-on: http://review.whamcloud.com/2627
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>