[PATCH 03/12] xfs: introduce a compound buffer construct

[Christoph Hellwig]

> +struct xfs_buf_vec {
> +	xfs_daddr_t		bv_bn;	/* block number for I/O */
> +	size_t			bv_len;	/* size of I/O */
> +};
> +#define XB_VECS		2

Why do we embedd to of these by default?  In general we'd either have
one or a number much bigger than two here.