HAMMER2_CHAIN_ALLOCATED
chain->flags = HAMMER2_CHAIN_ALLOCATED;
if (chain->flags & HAMMER2_CHAIN_ALLOCATED) {
atomic_clear_int(&chain->flags, HAMMER2_CHAIN_ALLOCATED);
chain->flags = HAMMER2_CHAIN_ALLOCATED;
if (chain->flags & HAMMER2_CHAIN_ALLOCATED) {
atomic_clear_int(&chain->flags, HAMMER2_CHAIN_ALLOCATED);