blist_free
blist_free(bl, 0, size);
blist_free(bl, da, count);
blist_free(newbl, count, newbl->bl_blocks - count);
blist_free(dest, blk, count);
blist_free(dest, blk + i, 1);
void blist_free(blist_t blist, daddr_t blkno, daddr_t count);
blist_free(sp->sw_blist, blk - sp->sw_first,
blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE),