Looks fine:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Nitpick below:
> +{
> + unsigned len = bv->bv_len;
> + unsigned total_len = 0;
> + unsigned new_nsegs = 0, seg_size = 0;
> +
> + /*
> + * Multipage bvec may be too big to hold in one segment,
> + * so the current bvec has to be splitted as multiple
> + * segments.
> + */
Please use up all 80 chars in a line.
