[PATCH 4/6] blk-mq: provide internal in-flight variant

[Jens Axboe <axboe@kernel.dk>]

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.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@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