Re: [PATCH 03/13] block: Add bio_clone_bioset()

[Tejun Heo <tj@kernel.org>]

Hey, Kent.

On Thu, May 17, 2012 at 10:59:50PM -0400, koverstreet@google.com wrote:
> From: Kent Overstreet <koverstreet@google.com>
> 
> This consolidates some code, and will help in a later patch changing how
> bio cloning works.
> 
> Signed-off-by: Kent Overstreet <koverstreet@google.com>

I'd prefer a bit more explanation on what's going on generally and why
and how dm conversion is different.

> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 3cc2169..3e33039 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1072,26 +1072,19 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector,
>   * Creates a bio that consists of range of complete bvecs.
>   */
>  static struct bio *clone_bio(struct bio *bio, sector_t sector,
> -			     unsigned short idx, unsigned short bv_count,
> +			     unsigned short bv_count,
>  			     unsigned int len, struct bio_set *bs)
>  {
>  	struct bio *clone;
>  
> -	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
> -	__bio_clone(clone, bio);
> +	clone = bio_clone_bioset(bio, GFP_NOIO, bs);
>  	clone->bi_sector = sector;
> -	clone->bi_idx = idx;
> -	clone->bi_vcnt = idx + bv_count;
> +	clone->bi_vcnt = bv_count;
>  	clone->bi_size = to_bytes(len);
> -	clone->bi_flags &= ~(1 << BIO_SEG_VALID);

Maybe removal of @idx deserves a separate patch?

> -	if (bio_integrity(bio)) {
> -		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
> -
> -		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
> -			bio_integrity_trim(clone,
> -					   bio_sector_offset(bio, idx, 0), len);
> -	}
> +	if (bio_integrity(bio) &&
> +	    clone->bi_size < bio->bi_size)

Unnecessary line break.

Other than that, looks good to me.

Thanks.

-- 
tejun