Re: [PATCH 1/5] brd; pass a bvec pointer to brd_do_bvec

Yu Kuai
2025-04-22T06:36:27Z

在 2025/04/21 15:26, Christoph Hellwig 写道:
> Pass the bvec to brd_do_bvec instead of marshalling the information into
> individual arguments.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/block/brd.c | 35 +++++++++++++----------------------
> 1 file changed, 13 insertions(+), 22 deletions(-)
>
LGTM

Reviewed-by: Yu Kuai <yukuai3@huawei.com>

> diff --git a/drivers/block/brd.c b/drivers/block/brd.c
> index 292f127cae0a..c8974bc545fb 100644
> --- a/drivers/block/brd.c
> +++ b/drivers/block/brd.c
> @@ -189,12 +189,10 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
> /*
> * Process a single bvec of a bio.
> */
> -static int brd_do_bvec(struct brd_device *brd, struct page *page,
> - unsigned int len, unsigned int off, blk_opf_t opf,
> - sector_t sector)
> +static int brd_rw_bvec(struct brd_device *brd, struct bio_vec *bv,
> + blk_opf_t opf, sector_t sector)
> {
> void *mem;
> - int err = 0;
>
> if (op_is_write(opf)) {
> /*
> @@ -202,24 +200,23 @@ static int brd_do_bvec(struct brd_device *brd, struct page *page,
> * block or filesystem layers from page reclaim.
> */
> gfp_t gfp = opf & REQ_NOWAIT ? GFP_NOWAIT : GFP_NOIO;
> + int err;
>
> - err = copy_to_brd_setup(brd, sector, len, gfp);
> + err = copy_to_brd_setup(brd, sector, bv->bv_len, gfp);
> if (err)
> - goto out;
> + return err;
> }
>
> - mem = kmap_atomic(page);
> + mem = kmap_atomic(bv->bv_page);
> if (!op_is_write(opf)) {
> - copy_from_brd(mem + off, brd, sector, len);
> - flush_dcache_page(page);
> + copy_from_brd(mem + bv->bv_offset, brd, sector, bv->bv_len);
> + flush_dcache_page(bv->bv_page);
> } else {
> - flush_dcache_page(page);
> - copy_to_brd(brd, mem + off, sector, len);
> + flush_dcache_page(bv->bv_page);
> + copy_to_brd(brd, mem + bv->bv_offset, sector, bv->bv_len);
> }
> kunmap_atomic(mem);
> -
> -out:
> - return err;
> + return 0;
> }
>
> static void brd_do_discard(struct brd_device *brd, sector_t sector, u32 size)
> @@ -255,15 +252,9 @@ static void brd_submit_bio(struct bio *bio)
> }
>
> bio_for_each_segment(bvec, bio, iter) {
> - unsigned int len = bvec.bv_len;
> int err;
>
> - /* Don't support un-aligned buffer */
> - WARN_ON_ONCE((bvec.bv_offset & (SECTOR_SIZE - 1)) ||
> - (len & (SECTOR_SIZE - 1)));
> -
> - err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
> - bio->bi_opf, sector);
> + err = brd_rw_bvec(brd, &bvec, bio->bi_opf, sector);
> if (err) {
> if (err == -ENOMEM && bio->bi_opf & REQ_NOWAIT) {
> bio_wouldblock_error(bio);
> @@ -272,7 +263,7 @@ static void brd_submit_bio(struct bio *bio)
> bio_io_error(bio);
> return;
> }
> - sector += len >> SECTOR_SHIFT;
> + sector += bvec.bv_len >> SECTOR_SHIFT;
> }
>
> bio_endio(bio);
>