Re: [PATCHv3 1/5] bvec: introduce multi-page bvec iterating

[Ming Lei <ming.lei@redhat.com>]

On Mon, Nov 20, 2023 at 02:40:54PM -0800, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Some bio_vec iterators can handle physically contiguous memory and have
> no need to split bvec consideration on page boundaries.

Then I am wondering why this helper is needed, and you can use each bvec
directly, which is supposed to be physically contiguous.

> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  include/linux/bvec.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/bvec.h b/include/linux/bvec.h
> index 555aae5448ae4..9364c258513e0 100644
> --- a/include/linux/bvec.h
> +++ b/include/linux/bvec.h
> @@ -184,6 +184,12 @@ static inline void bvec_iter_advance_single(const struct bio_vec *bv,
>  		((bvl = bvec_iter_bvec((bio_vec), (iter))), 1);	\
>  	     bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
>  
> +#define for_each_mp_bvec(bvl, bio_vec, iter, start)			\
> +	for (iter = (start);						\
> +	     (iter).bi_size &&						\
> +		((bvl = mp_bvec_iter_bvec((bio_vec), (iter))), 1);	\
> +	     bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
> +

We already have bio_for_each_bvec() to iterate over (multipage)bvecs
from bio.


Thanks,
Ming