[PATCHv6 07/11] block/bounce: count bytes instead of sectors

[Bart Van Assche]

On 6/10/22 12:58, Keith Busch wrote:
> From: Keith Busch <kbusch at kernel.org>
> 
> Individual bv_len's may not be a sector size.
> 
> Signed-off-by: Keith Busch <kbusch at kernel.org>
> Reviewed-by: Damien Le Moal <damien.lemoal at opensource.wdc.com>
> Reviewed-by: Pankaj Raghav <p.raghav at samsung.com>
> ---
>   block/bounce.c | 13 ++++++++++---
>   1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/block/bounce.c b/block/bounce.c
> index 8f7b6fe3b4db..fbadf179601f 100644
> --- a/block/bounce.c
> +++ b/block/bounce.c
> @@ -205,19 +205,26 @@ 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;
>   
> +	/*
> +	 * Individual bvecs might not be logical block aligned. Round down
> +	 * the split size so that each bio is properly block size aligned,
> +	 * even if we do not use the full hardware limits.
> +	 */
> +	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);

Do I see correctly that there are two changes in this patch: counting 
bytes instead of sectors and also splitting at logical block boundaries 
instead of a 512-byte boundary? Should this patch perhaps be split?

Thanks,

Bart.