[PATCH 1/3] block: introduce blk_queue_nr_active()

["Ewan D. Milne" <emilne@redhat.com>]

Returns a count of the total number of active requests
in a queue.  For non-shared tags (the usual case) this is
the sum of nr_active from all of the hctxs.

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
---
 block/blk-mq.h         |  5 -----
 include/linux/blk-mq.h | 33 ++++++++++++++++++++++++++-------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/block/blk-mq.h b/block/blk-mq.h
index 1743857e0b01..fbc65eefa017 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -214,11 +214,6 @@ static inline bool blk_mq_tag_is_reserved(struct blk_mq_tags *tags,
 	return tag < tags->nr_reserved_tags;
 }
 
-static inline bool blk_mq_is_shared_tags(unsigned int flags)
-{
-	return flags & BLK_MQ_F_TAG_HCTX_SHARED;
-}
-
 static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)
 {
 	if (data->rq_flags & RQF_SCHED_TAGS)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 01e8c31db665..c921ae5236ab 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -716,6 +716,32 @@ int blk_rq_poll(struct request *rq, struct io_comp_batch *iob,
 
 bool blk_mq_queue_inflight(struct request_queue *q);
 
+#define queue_for_each_hw_ctx(q, hctx, i)				\
+	xa_for_each(&(q)->hctx_table, (i), (hctx))
+
+#define hctx_for_each_ctx(hctx, ctx, i)					\
+	for ((i) = 0; (i) < (hctx)->nr_ctx &&				\
+	     ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++)
+
+static inline bool blk_mq_is_shared_tags(unsigned int flags)
+{
+	return flags & BLK_MQ_F_TAG_HCTX_SHARED;
+}
+
+static inline unsigned int blk_mq_queue_nr_active(struct request_queue *q)
+{
+	unsigned int nr_active = 0;
+	struct blk_mq_hw_ctx *hctx;
+	unsigned long i;
+
+	queue_for_each_hw_ctx(q, hctx, i) {
+		if (unlikely(blk_mq_is_shared_tags(hctx->flags)))
+			return atomic_read(&q->nr_active_requests_shared_tags);
+		nr_active += atomic_read(&hctx->nr_active);
+	}
+	return nr_active;
+}
+
 enum {
 	/* return when out of requests */
 	BLK_MQ_REQ_NOWAIT	= (__force blk_mq_req_flags_t)(1 << 0),
@@ -941,13 +967,6 @@ static inline void *blk_mq_rq_to_pdu(struct request *rq)
 	return rq + 1;
 }
 
-#define queue_for_each_hw_ctx(q, hctx, i)				\
-	xa_for_each(&(q)->hctx_table, (i), (hctx))
-
-#define hctx_for_each_ctx(hctx, ctx, i)					\
-	for ((i) = 0; (i) < (hctx)->nr_ctx &&				\
-	     ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++)
-
 static inline void blk_mq_cleanup_rq(struct request *rq)
 {
 	if (rq->q->mq_ops->cleanup_rq)
-- 
2.20.1