staging/lustre/ldlm: Hold lock when clearing flag

This patch moves lock's skip flag clearing from lru-delete to
lru-add code to prevent clearing lock's flag without resource lock
protection.
Signed-off-by: Li Xi <lixi@ddn.com>
Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Reviewed-on: http://review.whamcloud.com/8772
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4269Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ldlm/ldlm_lock.c

@@ -232,8 +232,6 @@ int ldlm_lock_remove_from_lru_nolock(struct ldlm_lock *lock)
 
 		LASSERT(lock->l_resource->lr_type != LDLM_FLOCK);
 		list_del_init(&lock->l_lru);
-		if (lock->l_flags & LDLM_FL_SKIPPED)
-			lock->l_flags &= ~LDLM_FL_SKIPPED;
 		LASSERT(ns->ns_nr_unused > 0);
 		ns->ns_nr_unused--;
 		rc = 1;
@@ -271,6 +269,8 @@ void ldlm_lock_add_to_lru_nolock(struct ldlm_lock *lock)
 	LASSERT(list_empty(&lock->l_lru));
 	LASSERT(lock->l_resource->lr_type != LDLM_FLOCK);
 	list_add_tail(&lock->l_lru, &ns->ns_unused_list);
+	if (lock->l_flags & LDLM_FL_SKIPPED)
+		lock->l_flags &= ~LDLM_FL_SKIPPED;
 	LASSERT(ns->ns_nr_unused >= 0);
 	ns->ns_nr_unused++;
 }