OC_BLOCK
if (new_net_conf->on_congestion != OC_BLOCK && new_net_conf->wire_protocol != DRBD_PROT_A)
on_congestion = nc ? nc->on_congestion : OC_BLOCK;
if (on_congestion == OC_BLOCK ||
#define DRBD_ON_CONGESTION_DEF OC_BLOCK