Re: [PATCH V10 02/19] block: introduce bio_for_each_bvec()

Omar Sandoval
2018-11-15T18:28:59Z

On Thu, Nov 15, 2018 at 04:52:49PM +0800, Ming Lei wrote:
> This helper is used for iterating over multi-page bvec for bio
> split & merge code.
>
> Cc: Dave Chinner <dchinner@redhat.com>
> Cc: Kent Overstreet <kent.overstreet@gmail.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Cc: dm-devel@redhat.com
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: Shaohua Li <shli@kernel.org>
> Cc: linux-raid@vger.kernel.org
> Cc: linux-erofs@lists.ozlabs.org
> Cc: David Sterba <dsterba@suse.com>
> Cc: linux-btrfs@vger.kernel.org
> Cc: Darrick J. Wong <darrick.wong@oracle.com>
> Cc: linux-xfs@vger.kernel.org
> Cc: Gao Xiang <gaoxiang25@huawei.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: linux-ext4@vger.kernel.org
> Cc: Coly Li <colyli@suse.de>
> Cc: linux-bcache@vger.kernel.org
> Cc: Boaz Harrosh <ooo@electrozaur.com>
> Cc: Bob Peterson <rpeterso@redhat.com>
> Cc: cluster-devel@redhat.com

Reviewed-by: Omar Sandoval <osandov@fb.com>

One comment below.

> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> include/linux/bio.h | 34 +++++++++++++++++++++++++++++++---
> include/linux/bvec.h | 36 ++++++++++++++++++++++++++++++++----
> 2 files changed, 63 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 056fb627edb3..1f0dcf109841 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -76,6 +76,9 @@
> #define bio_data_dir(bio) \
> (op_is_write(bio_op(bio)) ? WRITE : READ)
>
> +#define bio_iter_mp_iovec(bio, iter) \
> + mp_bvec_iter_bvec((bio)->bi_io_vec, (iter))
> +
> /*
> * Check whether this bio carries any data or not. A NULL bio is allowed.
> */
> @@ -135,18 +138,33 @@ static inline bool bio_full(struct bio *bio)
> #define bio_for_each_segment_all(bvl, bio, i) \
> for (i = 0, bvl = (bio)->bi_io_vec; i < (bio)->bi_vcnt; i++, bvl++)
>
> -static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
> - unsigned bytes)
> +static inline void __bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
> + unsigned bytes, bool mp)
> {
> iter->bi_sector += bytes >> 9;
>
> if (bio_no_advance_iter(bio))
> iter->bi_size -= bytes;
> else
> - bvec_iter_advance(bio->bi_io_vec, iter, bytes);
> + if (!mp)
> + bvec_iter_advance(bio->bi_io_vec, iter, bytes);
> + else
> + mp_bvec_iter_advance(bio->bi_io_vec, iter, bytes);

if (!foo) {} else {} hurts my brain, please do

if (mp)
mp_bvec_iter_advance(bio->bi_io_vec, iter, bytes);
else
bvec_iter_advance(bio->bi_io_vec, iter, bytes);