md-cluster: use DLM_LSFL_SOFTIRQ for dlm_new_lockspace()

Use the recently added DLM_LSFL_SOFTIRQ flag in dlm_new_lockspace(),
signalling the ability to handle callbacks being run from softirq
context.  The md-cluster callback functions only call complete(),
which is suitable for softirq.  This should make dlm lock request
completions more efficient by avoiding the workqueue context switch.
Acked-by: Heming Zhao <heming.zhao@suse.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

drivers/md/md-cluster.c

@@ -887,7 +887,7 @@ static int join(struct mddev *mddev, int nodes)
 	memset(str, 0, 64);
 	sprintf(str, "%pU", mddev->uuid);
 	ret = dlm_new_lockspace(str, mddev->bitmap_info.cluster_name,
-				0, LVB_SIZE, &md_ls_ops, mddev,
+				DLM_LSFL_SOFTIRQ, LVB_SIZE, &md_ls_ops, mddev,
 				&ops_rv, &cinfo->lockspace);
 	if (ret)
 		goto err;