dbuf_prefetch_impl
return (dbuf_prefetch_impl(dn, level, blkid, prio, aflags, NULL, NULL));
issued += dbuf_prefetch_impl(zf->zf_dnode, 0, pf_start + i,
issued += dbuf_prefetch_impl(zf->zf_dnode, 1, iblk,
int dbuf_prefetch_impl(struct dnode *dn, int64_t level, uint64_t blkid,