On Fri, Aug 04, 2017 at 09:04:20AM -0600, Jens Axboe wrote:
> We don't have to inc/dec some counter, since we can just
> iterate the tags. That makes inc/dec a noop, but means we
> have to iterate busy tags to get an in-flight count.
>
> Reviewed-by: Bart Van Assche <bart.vanass...@wdc.com>

Barring performance numbers that show that percpu is much better (which
I doubt),

Reviewed-by: Omar Sandoval <osan...@fb.com>
> Signed-off-by: Jens Axboe <ax...@kernel.dk>
> ---
>  block/blk-mq.c        | 31 +++++++++++++++++++++++++++++++
>  block/blk-mq.h        |  3 +++
>  block/genhd.c         | 37 +++++++++++++++++++++++++++++++++++++
>  include/linux/genhd.h | 34 ++++++----------------------------
>  4 files changed, 77 insertions(+), 28 deletions(-)
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index a5d369dc7622..fe1aa1f5f069 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -83,6 +83,37 @@ static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx 
> *hctx,
>       sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
>  }
>  
> +struct mq_inflight {
> +     struct hd_struct *part;
> +     unsigned int *inflight;
> +};
> +
> +static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
> +                               struct request *rq, void *priv,
> +                               bool reserved)
> +{
> +     struct mq_inflight *mi = priv;
> +
> +     if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
> +             return;
> +
> +     /*
> +      * Count as inflight if it either matches the partition we asked
> +      * for, or if it's the root
> +      */
> +     if (rq->part == mi->part || mi->part->partno)
> +             mi->inflight[0]++;
> +}
> +
> +void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
> +                   unsigned int inflight[2])
> +{
> +     struct mq_inflight mi = { .part = part, .inflight = inflight, };
> +
> +     inflight[0] = 0;
> +     blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
> +}
> +
>  void blk_freeze_queue_start(struct request_queue *q)
>  {
>       int freeze_depth;
> diff --git a/block/blk-mq.h b/block/blk-mq.h
> index 60b01c0309bc..98252b79b80b 100644
> --- a/block/blk-mq.h
> +++ b/block/blk-mq.h
> @@ -133,4 +133,7 @@ static inline bool blk_mq_hw_queue_mapped(struct 
> blk_mq_hw_ctx *hctx)
>       return hctx->nr_ctx && hctx->tags;
>  }
>  
> +void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
> +                     unsigned int inflight[2]);
> +
>  #endif
> diff --git a/block/genhd.c b/block/genhd.c
> index 822f65f95e2a..3dc4d115480f 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -45,6 +45,43 @@ static void disk_add_events(struct gendisk *disk);
>  static void disk_del_events(struct gendisk *disk);
>  static void disk_release_events(struct gendisk *disk);
>  
> +void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int 
> rw)
> +{
> +     if (q->mq_ops)
> +             return;
> +
> +     atomic_inc(&part->in_flight[rw]);
> +     if (part->partno)
> +             atomic_inc(&part_to_disk(part)->part0.in_flight[rw]);
> +}
> +
> +void part_dec_in_flight(struct request_queue *q, struct hd_struct *part, int 
> rw)
> +{
> +     if (q->mq_ops)
> +             return;
> +
> +     atomic_dec(&part->in_flight[rw]);
> +     if (part->partno)
> +             atomic_dec(&part_to_disk(part)->part0.in_flight[rw]);
> +}
> +
> +void part_in_flight(struct request_queue *q, struct hd_struct *part,
> +                 unsigned int inflight[2])
> +{
> +     if (q->mq_ops) {
> +             blk_mq_in_flight(q, part, inflight);
> +             return;
> +     }
> +
> +     inflight[0] = atomic_read(&part->in_flight[0]) +
> +                     atomic_read(&part->in_flight[1]);
> +     if (part->partno) {
> +             part = &part_to_disk(part)->part0;
> +             inflight[1] = atomic_read(&part->in_flight[0]) +
> +                             atomic_read(&part->in_flight[1]);
> +     }
> +}
> +
>  /**
>   * disk_get_part - get partition
>   * @disk: disk to look partition from
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index a9c8ea632fdc..ea652bfcd675 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -362,34 +362,12 @@ static inline void free_part_stats(struct hd_struct 
> *part)
>  #define part_stat_sub(cpu, gendiskp, field, subnd)                   \
>       part_stat_add(cpu, gendiskp, field, -subnd)
>  
> -static inline void part_inc_in_flight(struct request_queue *q,
> -                                   struct hd_struct *part, int rw)
> -{
> -     atomic_inc(&part->in_flight[rw]);
> -     if (part->partno)
> -             atomic_inc(&part_to_disk(part)->part0.in_flight[rw]);
> -}
> -
> -static inline void part_dec_in_flight(struct request_queue *q,
> -                                   struct hd_struct *part, int rw)
> -{
> -     atomic_dec(&part->in_flight[rw]);
> -     if (part->partno)
> -             atomic_dec(&part_to_disk(part)->part0.in_flight[rw]);
> -}
> -
> -static inline void part_in_flight(struct request_queue *q,
> -                               struct hd_struct *part,
> -                               unsigned int inflight[2])
> -{
> -     inflight[0] = atomic_read(&part->in_flight[0]) +
> -                     atomic_read(&part->in_flight[1]);
> -     if (part->partno) {
> -             part = &part_to_disk(part)->part0;
> -             inflight[1] = atomic_read(&part->in_flight[0]) +
> -                             atomic_read(&part->in_flight[1]);
> -     }
> -}
> +void part_in_flight(struct request_queue *q, struct hd_struct *part,
> +                     unsigned int inflight[2]);
> +void part_dec_in_flight(struct request_queue *q, struct hd_struct *part,
> +                     int rw);
> +void part_inc_in_flight(struct request_queue *q, struct hd_struct *part,
> +                     int rw);
>  
>  static inline struct partition_meta_info *alloc_part_info(struct gendisk 
> *disk)
>  {
> -- 
> 2.7.4
> 

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