Re: [PATCH V10 09/19] block: introduce bio_bvecs()

[Omar Sandoval]

On Thu, Nov 15, 2018 at 04:52:56PM +0800, Ming Lei wrote:
> There are still cases in which we need to use bio_bvecs() for get the
> number of multi-page segment, so introduce it.
> 
> Cc: Dave Chinner <dchinner@xxxxxxxxxx>
> Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
> Cc: dm-devel@xxxxxxxxxx
> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Cc: Shaohua Li <shli@xxxxxxxxxx>
> Cc: linux-raid@xxxxxxxxxxxxxxx
> Cc: linux-erofs@xxxxxxxxxxxxxxxx
> Cc: David Sterba <dsterba@xxxxxxxx>
> Cc: linux-btrfs@xxxxxxxxxxxxxxx
> Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Cc: linux-xfs@xxxxxxxxxxxxxxx
> Cc: Gao Xiang <gaoxiang25@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Theodore Ts'o <tytso@xxxxxxx>
> Cc: linux-ext4@xxxxxxxxxxxxxxx
> Cc: Coly Li <colyli@xxxxxxx>
> Cc: linux-bcache@xxxxxxxxxxxxxxx
> Cc: Boaz Harrosh <ooo@xxxxxxxxxxxxxxx>
> Cc: Bob Peterson <rpeterso@xxxxxxxxxx>
> Cc: cluster-devel@xxxxxxxxxx

Reviewed-by: Omar Sandoval <osandov@xxxxxx>

> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
>  include/linux/bio.h | 30 +++++++++++++++++++++++++-----
>  1 file changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 1f0dcf109841..3496c816946e 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -196,7 +196,6 @@ static inline unsigned bio_segments(struct bio *bio)
>  	 * We special case discard/write same/write zeroes, because they
>  	 * interpret bi_size differently:
>  	 */
> -
>  	switch (bio_op(bio)) {
>  	case REQ_OP_DISCARD:
>  	case REQ_OP_SECURE_ERASE:
> @@ -205,13 +204,34 @@ static inline unsigned bio_segments(struct bio *bio)
>  	case REQ_OP_WRITE_SAME:
>  		return 1;
>  	default:
> -		break;
> +		bio_for_each_segment(bv, bio, iter)
> +			segs++;
> +		return segs;
>  	}
> +}
>  
> -	bio_for_each_segment(bv, bio, iter)
> -		segs++;
> +static inline unsigned bio_bvecs(struct bio *bio)
> +{
> +	unsigned bvecs = 0;
> +	struct bio_vec bv;
> +	struct bvec_iter iter;
>  
> -	return segs;
> +	/*
> +	 * We special case discard/write same/write zeroes, because they
> +	 * interpret bi_size differently:
> +	 */
> +	switch (bio_op(bio)) {
> +	case REQ_OP_DISCARD:
> +	case REQ_OP_SECURE_ERASE:
> +	case REQ_OP_WRITE_ZEROES:
> +		return 0;
> +	case REQ_OP_WRITE_SAME:
> +		return 1;
> +	default:
> +		bio_for_each_bvec(bv, bio, iter)
> +			bvecs++;
> +		return bvecs;
> +	}
>  }
>  
>  /*
> -- 
> 2.9.5
>