On Jun 13, 2017, at 11:15 AM, Jens Axboe <axboe@xxxxxxxxx> wrote:
>
> No functional changes in this patch, but it allows each bio to
> carry a stream ID and disallows merging of bio's with different
> stream IDs.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> ---
> block/bio.c | 2 ++
> block/blk-merge.c | 14 ++++++++++++++
> include/linux/blk_types.h | 17 +++++++++++++++++
> 3 files changed, 33 insertions(+)
>
> diff --git a/block/bio.c b/block/bio.c
> index 888e7801c638..77f4be1f7428 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -595,6 +595,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
> bio->bi_opf = bio_src->bi_opf;
> bio->bi_iter = bio_src->bi_iter;
> bio->bi_io_vec = bio_src->bi_io_vec;
> + bio->bi_stream = bio_src->bi_stream;
>
> bio_clone_blkcg_association(bio, bio_src);
> }
> @@ -678,6 +679,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
> bio->bi_opf = bio_src->bi_opf;
> bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
> bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
> + bio->bi_stream = bio_src->bi_stream;
>
> switch (bio_op(bio)) {
> case REQ_OP_DISCARD:
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index 3990ae406341..28998acdd675 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -693,6 +693,13 @@ static struct request *attempt_merge(struct request_queue *q,
> return NULL;
>
> /*
> + * Don't allow merge of different streams, or for a stream with
> + * non-stream IO.
> + */
> + if (req->bio->bi_stream != next->bio->bi_stream)
> + return NULL;
> +
> + /*
> * If we are allowed to merge, then append bio list
> * from next to rq and release next. merge_requests_fn
> * will have updated segment counts, update sector
> @@ -811,6 +818,13 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
> !blk_write_same_mergeable(rq->bio, bio))
> return false;
>
> + /*
> + * Don't allow merge of different streams, or for a stream with
> + * non-stream IO.
> + */
> + if (rq->bio->bi_stream != bio->bi_stream)
> + return false;
> +
> return true;
> }
>
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 61339bc44400..1940876a7fa7 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -36,6 +36,8 @@ struct bio {
> unsigned short bi_flags; /* status, etc and bvec pool number */
> unsigned short bi_ioprio;
>
> + unsigned int bi_stream; /* write life time hint */
> +
> struct bvec_iter bi_iter;
>
> /* Number of segments in this BIO after
> @@ -312,4 +314,19 @@ struct blk_rq_stat {
> u64 batch;
> };
>
> +static inline void bio_set_streamid(struct bio *bio, unsigned int stream)
> +{
> + bio->bi_stream = stream;
> +}
> +
> +static inline bool bio_stream_valid(struct bio *bio)
> +{
> + return bio->bi_stream != 0;
> +}
> +
> +static inline unsigned int bio_stream(struct bio *bio)
> +{
> + return bio->bi_stream;
> +}
> +
> #endif /* __LINUX_BLK_TYPES_H */
> --
> 2.7.4
>
Cheers, Andreas
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