dbuf_free_range
dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
dbuf_free_range(dn, blkid, blkid + nblks - 1, tx);
void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,