On Tue, Jun 08, 2021 at 06:06:01PM +0200, Christoph Hellwig wrote:
> Rewrite the actual bounce buffering loop in __blk_queue_bounce to that
> the memcpy_to_bvec helper can be used to perform the data copies.
>
> Signed-off-by: Christoph Hellwig <h...@lst.de>
> ---
> block/bounce.c | 21 +++++++--------------
> 1 file changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/block/bounce.c b/block/bounce.c
> index a2fc6326b6c9..b5ad09e07bcf 100644
> --- a/block/bounce.c
> +++ b/block/bounce.c
> @@ -243,24 +243,17 @@ void __blk_queue_bounce(struct request_queue *q, struct
> bio **bio_orig)
> * because the 'bio' is single-page bvec.
> */
> for (i = 0, to = bio->bi_io_vec; i < bio->bi_vcnt; to++, i++) {
> - struct page *page = to->bv_page;
> + struct page *bounce_page;
>
> - if (!PageHighMem(page))
> + if (!PageHighMem(to->bv_page))
> continue;
>
> - to->bv_page = mempool_alloc(&page_pool, GFP_NOIO);
> - inc_zone_page_state(to->bv_page, NR_BOUNCE);
> + bounce_page = mempool_alloc(&page_pool, GFP_NOIO);
> + inc_zone_page_state(bounce_page, NR_BOUNCE);
>
> - if (rw == WRITE) {
> - char *vto, *vfrom;
> -
> - flush_dcache_page(page);
> -
> - vto = page_address(to->bv_page) + to->bv_offset;
> - vfrom = kmap_atomic(page) + to->bv_offset;
> - memcpy(vto, vfrom, to->bv_len);
> - kunmap_atomic(vfrom);
> - }
> + if (rw == WRITE)
> + memcpy_from_bvec(page_address(bounce_page), to);
NIT: the fact that the copy is from 'to' makes my head hurt... But I don't
see a good way to change that without declaring unnecessary variables... :-(
The logic seems right.
Ira
> + to->bv_page = bounce_page;
> }
>
> trace_block_bio_bounce(*bio_orig);
> --
> 2.30.2
>
