On Wed, 2022-06-22 at 05:15 +0100, Al Viro wrote:
> do what we do for iovec/kvec; that ends up generating better code,
> AFAICS.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
> lib/iov_iter.c | 23 ++++++++++++++---------
> 1 file changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> index 8275b28e886b..93ceb13ec7b5 100644
> --- a/lib/iov_iter.c
> +++ b/lib/iov_iter.c
> @@ -870,17 +870,22 @@ static void pipe_advance(struct iov_iter *i, size_t size)
>
> static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
> {
> - struct bvec_iter bi;
> + const struct bio_vec *bvec, *end;
>
> - bi.bi_size = i->count;
> - bi.bi_bvec_done = i->iov_offset;
> - bi.bi_idx = 0;
> - bvec_iter_advance(i->bvec, &bi, size);
> + if (!i->count)
> + return;
> + i->count -= size;
> +
> + size += i->iov_offset;
>
> - i->bvec += bi.bi_idx;
> - i->nr_segs -= bi.bi_idx;
> - i->count = bi.bi_size;
> - i->iov_offset = bi.bi_bvec_done;
> + for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) {
> + if (likely(size < bvec->bv_len))
> + break;
> + size -= bvec->bv_len;
> + }
> + i->iov_offset = size;
> + i->nr_segs -= bvec - i->bvec;
> + i->bvec = bvec;
> }
>
> static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
Much simpler to follow, IMO...
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
