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

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

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@xxxxxx>
> ---
>   drivers/block/brd.c | 35 +++++++++++++----------------------
>   1 file changed, 13 insertions(+), 22 deletions(-)
LGTM

Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>

> 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);