Re: [PATCHv4 7/9] block/bounce: count bytes instead of sectors

Pankaj Raghav
2022-05-30T15:49:19Z

On Wed, May 25, 2022 at 06:06:11PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
>
> Individual bv_len's may not be a sector size.
>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
> v3->v4:
>
> Use sector shift
>
> Add comment explaing the ALIGN_DOWN
>
> Use unsigned int type for counting bytes
>
> block/bounce.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/block/bounce.c b/block/bounce.c
> index 8f7b6fe3b4db..f6ae21ec2a70 100644
> --- a/block/bounce.c
> +++ b/block/bounce.c
> @@ -205,19 +205,25 @@ void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
> int rw = bio_data_dir(*bio_orig);
> struct bio_vec *to, from;
> struct bvec_iter iter;
> - unsigned i = 0;
> + unsigned i = 0, bytes = 0;
> bool bounce = false;
> - int sectors = 0;
> + int sectors;
>
> bio_for_each_segment(from, *bio_orig, iter) {
> if (i++ < BIO_MAX_VECS)
> - sectors += from.bv_len >> 9;
> + bytes += from.bv_len;
> if (PageHighMem(from.bv_page))
> bounce = true;
> }
> if (!bounce)
> return;
>
> + /*
> + * If the original has more than BIO_MAX_VECS biovecs, the total bytes
> + * may not be block size aligned. Align down to ensure both sides of
> + * the split bio are appropriately sized.
> + */
> + sectors = ALIGN_DOWN(bytes, queue_logical_block_size(q)) >> SECTOR_SHIFT;
> if (sectors < bio_sectors(*bio_orig)) {
> bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split);
> bio_chain(bio, *bio_orig);
> --
> 2.30.2
>

Looks good,
Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
--
Pankaj Raghav