ocfs2/dlm: Use ast_lock to protect ast_list

The code was using dlm->spinlock instead of dlm->ast_lock to protect the
ast_list. This patch fixes the issue.
Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/dlm/dlmunlock.c

@@ -117,11 +117,11 @@ static enum dlm_status dlmunlock_common(struct dlm_ctxt *dlm,
 	else
 		BUG_ON(res->owner == dlm->node_num);
 
-	spin_lock(&dlm->spinlock);
+	spin_lock(&dlm->ast_lock);
 	/* We want to be sure that we're not freeing a lock
 	 * that still has AST's pending... */
 	in_use = !list_empty(&lock->ast_list);
-	spin_unlock(&dlm->spinlock);
+	spin_unlock(&dlm->ast_lock);
 	if (in_use) {
 	       mlog(ML_ERROR, "lockres %.*s: Someone is calling dlmunlock "
 		    "while waiting for an ast!", res->lockname.len,