Function zap_open_leaf

freebsd/contrib/openzfs/module/zfs/zap.c:471–515

}

static zap_leaf_t *
zap_open_leaf(uint64_t blkid, dmu_buf_t *db)
{
	ASSERT(blkid != 0);

	zap_leaf_t *l = kmem_zalloc(sizeof (zap_leaf_t), KM_SLEEP);
	rw_init(&l->l_rwlock, NULL, RW_DEFAULT, NULL);
	rw_enter(&l->l_rwlock, RW_WRITER);
	l->l_blkid = blkid;
	l->l_bs = highbit64(db->db_size) - 1;
	l->l_dbuf = db;

	dmu_buf_init_user(&l->l_dbu, zap_leaf_evict_sync, NULL, &l->l_dbuf);
	zap_leaf_t *winner = dmu_buf_set_user(db, &l->l_dbu);

	rw_exit(&l->l_rwlock);
	if (winner != NULL) {
		/* someone else set it first */
		zap_leaf_evict_sync(&l->l_dbu);
		l = winner;
	}

	/*
	 * lhr_pad was previously used for the next leaf in the leaf
	 * chain.  There should be no chained leafs (as we have removed
	 * support for them).
	 */
	ASSERT0(zap_leaf_phys(l)->l_hdr.lh_pad1);

	/*
	 * There should be more hash entries than there can be
	 * chunks to put in the hash table
	 */
	ASSERT3U(ZAP_LEAF_HASH_NUMENTRIES(l), >, ZAP_LEAF_NUMCHUNKS(l) / 3);

	/* The chunks should begin at the end of the hash table */
	ASSERT3P(&ZAP_LEAF_CHUNK(l, 0), ==, (zap_leaf_chunk_t *)
	    &zap_leaf_phys(l)->l_hash[ZAP_LEAF_HASH_NUMENTRIES(l)]);

	/* The chunks should end at the end of the block */
	ASSERT3U((uintptr_t)&ZAP_LEAF_CHUNK(l, ZAP_LEAF_NUMCHUNKS(l)) -
	    (uintptr_t)zap_leaf_phys(l), ==, l->l_dbuf->db_size);

	return (l);
}

static int
zap_get_leaf_byblk(zap_t *zap, uint64_t blkid, dmu_tx_t *tx, krw_t lt,