[PATCH 3/4] blk-mq: provide internal in-flight variant

Jens Axboe
2017-08-03T20:01:55Z

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.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-mq.c | 24 ++++++++++++++++++++++++
block/blk-mq.h | 2 ++
block/genhd.c | 29 +++++++++++++++++++++++++++++
include/linux/genhd.h | 25 +++----------------------
4 files changed, 58 insertions(+), 22 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 05dfa3f270ae..37035891e120 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -86,6 +86,30 @@ 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 (rq->part == mi->part)
+ mi->inflight++;
+}
+
+unsigned int blk_mq_in_flight(struct request_queue *q,
+ struct hd_struct *part)
+{
+ struct mq_inflight mi = { .part = part, .inflight = 0 };
+
+ blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
+ return mi.inflight;
+}
+
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 1a06fdf9fd4d..cade1a512a01 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -138,4 +138,6 @@ static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
return hctx->nr_ctx && hctx->tags;
}

+unsigned int blk_mq_in_flight(struct request_queue *q, struct hd_struct *part);
+
#endif
diff --git a/block/genhd.c b/block/genhd.c
index f735af67a0c9..ad5dc567d57f 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -45,6 +45,35 @@ 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]);
+}
+
+int part_in_flight(struct request_queue *q, struct hd_struct *part)
+{
+ if (q->mq_ops)
+ return blk_mq_in_flight(q, part);
+
+ return 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 7f7427e00f9c..f2c5096b3a7e 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -362,28 +362,9 @@ 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 int part_in_flight(struct request_queue *q,
- struct hd_struct *part)
-{
- return atomic_read(&part->in_flight[0]) +
- atomic_read(&part->in_flight[1]);
-}
+int part_in_flight(struct request_queue *q, struct hd_struct *part);
+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