Function dbuf_prefetch_indirect_done

freebsd/contrib/openzfs/module/zfs/dbuf.c:3129–3215

* Called when an indirect block above our prefetch target is read in. This * will either read in the next indirect block down the tree or issue the actual * prefetch if the next block down is our target. */

 * prefetch if the next block down is our target.
 */
static void
dbuf_prefetch_indirect_done(zio_t *zio, const zbookmark_phys_t *zb,
    const blkptr_t *iobp, arc_buf_t *abuf, void *private)
{
	dbuf_prefetch_arg_t *dpa = private;

	ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel);
	ASSERT3S(dpa->dpa_curlevel, >, 0);

	if (abuf == NULL) {
		ASSERT(zio == NULL || zio->io_error != 0);
		return (dbuf_prefetch_fini(dpa, B_TRUE));
	}
	ASSERT(zio == NULL || zio->io_error == 0);

	/*
	 * The dpa_dnode is only valid if we are called with a NULL
	 * zio. This indicates that the arc_read() returned without
	 * first calling zio_read() to issue a physical read. Once
	 * a physical read is made the dpa_dnode must be invalidated
	 * as the locks guarding it may have been dropped. If the
	 * dpa_dnode is still valid, then we want to add it to the dbuf
	 * cache. To do so, we must hold the dbuf associated with the block
	 * we just prefetched, read its contents so that we associate it
	 * with an arc_buf_t, and then release it.
	 */
	if (zio != NULL) {
		ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel);
		if (zio->io_flags & ZIO_FLAG_RAW_COMPRESS) {
			ASSERT3U(BP_GET_PSIZE(zio->io_bp), ==, zio->io_size);
		} else {
			ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
		}
		ASSERT3P(zio->io_spa, ==, dpa->dpa_spa);

		dpa->dpa_dnode = NULL;
	} else if (dpa->dpa_dnode != NULL) {
		uint64_t curblkid = dpa->dpa_zb.zb_blkid >>
		    (dpa->dpa_epbs * (dpa->dpa_curlevel -
		    dpa->dpa_zb.zb_level));
		dmu_buf_impl_t *db = dbuf_hold_level(dpa->dpa_dnode,
		    dpa->dpa_curlevel, curblkid, FTAG);
		if (db == NULL) {
			arc_buf_destroy(abuf, private);
			return (dbuf_prefetch_fini(dpa, B_TRUE));
		}
		(void) dbuf_read(db, NULL,
		    DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH | DB_RF_HAVESTRUCT);
		dbuf_rele(db, FTAG);
	}

	dpa->dpa_curlevel--;
	uint64_t nextblkid = dpa->dpa_zb.zb_blkid >>
	    (dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level));
	blkptr_t *bp = ((blkptr_t *)abuf->b_data) +
	    P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs);

	ASSERT(!BP_IS_REDACTED(bp) ||