sizeof(struct xfs_attr3_leaf_hdr) = 80
sizeof(struct xfs_attr3_leafblock) = 88
sizeof(struct xfs_attr3_rmt_hdr) = 56
+sizeof(struct xfs_attr_shortform) = 8
sizeof(struct xfs_btree_block) = 72
sizeof(struct xfs_btree_block_lhdr) = 64
sizeof(struct xfs_btree_block_shdr) = 48