On Fri, Mar 22, 2019 at 9:14 PM Johannes Thumshirn <jthumshirn@xxxxxxx> wrote:
>
> From: Jens Axboe <axboe@xxxxxxxxx>
>
> Kill the BIO_SEG_VALID flag. We should just use ->bi_phys_segments to tell
> if it's valid or not.
>
> This patch uses -1 to signify it's not.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> [ jth initialize pc bios with 1 phys segment and WARN if we're submitting
> bios with -1 segments ]
> Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
> ---
> block/bio.c | 15 +++++++++------
> block/blk-core.c | 1 +
> block/blk-merge.c | 13 ++++++-------
> drivers/md/raid5.c | 2 +-
> include/linux/blk_types.h | 1 -
> 5 files changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 71a78d9fb8b7..a79b2bbcffd0 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -280,6 +280,7 @@ void bio_init(struct bio *bio, struct bio_vec *table,
> unsigned short max_vecs)
> {
> memset(bio, 0, sizeof(*bio));
> + bio->bi_phys_segments = -1;
> atomic_set(&bio->__bi_remaining, 1);
> atomic_set(&bio->__bi_cnt, 1);
>
> @@ -305,6 +306,7 @@ void bio_reset(struct bio *bio)
> bio_uninit(bio);
>
> memset(bio, 0, BIO_RESET_BYTES);
> + bio->bi_phys_segments = -1;
> bio->bi_flags = flags;
> atomic_set(&bio->__bi_remaining, 1);
> }
> @@ -573,7 +575,7 @@ EXPORT_SYMBOL(bio_put);
>
> int bio_phys_segments(struct request_queue *q, struct bio *bio)
> {
> - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
> + if (unlikely(bio->bi_phys_segments == -1))
> blk_recount_segments(q, bio);
>
> return bio->bi_phys_segments;
> @@ -712,7 +714,10 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page
> bvec->bv_len = len;
> bvec->bv_offset = offset;
> bio->bi_vcnt++;
> - bio->bi_phys_segments++;
> + if (bio->bi_phys_segments == -1)
> + bio->bi_phys_segments = 1;
> + else
> + bio->bi_phys_segments++;
> bio->bi_iter.bi_size += len;
>
> /*
> @@ -731,7 +736,7 @@ int bio_add_pc_page(struct request_queue *q, struct bio *bio, struct page
>
> /* If we may be able to merge these biovecs, force a recount */
> if (bio->bi_vcnt > 1 && biovec_phys_mergeable(q, bvec - 1, bvec))
> - bio_clear_flag(bio, BIO_SEG_VALID);
> + bio->bi_phys_segments = -1;
>
> done:
> return len;
> @@ -1913,10 +1918,8 @@ void bio_trim(struct bio *bio, int offset, int size)
> if (offset == 0 && size == bio->bi_iter.bi_size)
> return;
>
> - bio_clear_flag(bio, BIO_SEG_VALID);
> -
> + bio->bi_phys_segments = -1;
> bio_advance(bio, offset << 9);
> -
> bio->bi_iter.bi_size = size;
>
> if (bio_integrity(bio))
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 4673ebe42255..53372a16dd7c 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1514,6 +1514,7 @@ void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
> else if (bio_op(bio) == REQ_OP_DISCARD)
> rq->nr_phys_segments = 1;
>
> + WARN_ON(rq->nr_phys_segments == -1);
> rq->__data_len = bio->bi_iter.bi_size;
> rq->bio = rq->biotail = bio;
>
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 1c9d4f0f96ea..16c2ae69c46b 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -343,7 +343,6 @@ void blk_queue_split(struct request_queue *q, struct bio **bio)
> /* physical segments can be figured out during splitting */
> res = split ? split : *bio;
> res->bi_phys_segments = nsegs;
> - bio_set_flag(res, BIO_SEG_VALID);
>
> if (split) {
> /* there isn't chance to merge the splitted bio */
> @@ -440,8 +439,6 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio)
> bio->bi_next = NULL;
> bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio);
> bio->bi_next = nxt;
> -
> - bio_set_flag(bio, BIO_SEG_VALID);
> }
>
> static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
> @@ -620,6 +617,8 @@ static inline int ll_new_hw_segment(struct request_queue *q,
> {
> int nr_phys_segs = bio_phys_segments(q, bio);
>
> + if (WARN_ON(nr_phys_segs == -1))
> + nr_phys_segs = 0;
> if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q))
> goto no_merge;
>
> @@ -651,9 +650,9 @@ int ll_back_merge_fn(struct request_queue *q, struct request *req,
> req_set_nomerge(q, req);
> return 0;
> }
> - if (!bio_flagged(req->biotail, BIO_SEG_VALID))
> + if (req->biotail->bi_phys_segments == -1)
> blk_recount_segments(q, req->biotail);
> - if (!bio_flagged(bio, BIO_SEG_VALID))
> + if (bio->bi_phys_segments == -1)
> blk_recount_segments(q, bio);
>
> return ll_new_hw_segment(q, req, bio);
> @@ -673,9 +672,9 @@ int ll_front_merge_fn(struct request_queue *q, struct request *req,
> req_set_nomerge(q, req);
> return 0;
> }
> - if (!bio_flagged(bio, BIO_SEG_VALID))
> + if (bio->bi_phys_segments == -1)
> blk_recount_segments(q, bio);
> - if (!bio_flagged(req->bio, BIO_SEG_VALID))
> + if (req->bio->bi_phys_segments == -1)
> blk_recount_segments(q, req->bio);
>
> return ll_new_hw_segment(q, req, bio);
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index c033bfcb209e..79eb54dcf0f9 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -5247,7 +5247,7 @@ static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
> rcu_read_unlock();
> raid_bio->bi_next = (void*)rdev;
> bio_set_dev(align_bi, rdev->bdev);
> - bio_clear_flag(align_bi, BIO_SEG_VALID);
> + align_bi->bi_phys_segments = -1;
>
> if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
> bio_sectors(align_bi),
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index d66bf5f32610..472059e92071 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -215,7 +215,6 @@ struct bio {
> /*
> * bio flags
> */
> -#define BIO_SEG_VALID 1 /* bi_phys_segments valid */
> #define BIO_CLONED 2 /* doesn't own data */
> #define BIO_BOUNCED 3 /* bio is a bounce bio */
> #define BIO_USER_MAPPED 4 /* contains user pages */
Some drivers set max segments as USHRT_MAX, will this patch break this
kind of driver?
Thanks,
Ming Lei
