multilist_sublist_head
hdr = multilist_sublist_head(mls);
while ((dn = multilist_sublist_head(list)) != NULL) {
ASSERT(multilist_sublist_head(list) == NULL ||
while ((dn = multilist_sublist_head(list)) != NULL) {
metaslab_t *msp = multilist_sublist_head(mls);
metaslab_t *msp = multilist_sublist_head(mls);
void *multilist_sublist_head(multilist_sublist_t *);