[PATCH 2/4] blk-mq: introduce blk_mq_get_queue_depth()

Ming Lei
2017-04-28T15:16:45Z

The hardware queue depth can be resized via blk_mq_update_nr_requests(),
so introduce this helper for retrieving queue's depth easily.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq.c | 12 ++++++++++++
block/blk-mq.h | 1 +
2 files changed, 13 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e530bc54f0d9..04761fb76ab4 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2637,6 +2637,18 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
}
EXPORT_SYMBOL(blk_mq_free_tag_set);

+/*
+ * Queue depth can be changed via blk_mq_update_nr_requests(),
+ * so use this helper to retrieve queue's depth.
+ */
+int blk_mq_get_queue_depth(struct request_queue *q)
+{
+ /* All queues have same queue depth */
+ struct blk_mq_tags *tags = q->tag_set->tags[0];
+
+ return tags->bitmap_tags.sb.depth;
+}
+
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
{
struct blk_mq_tag_set *set = q->tag_set;
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 2814a14e529c..8085d5989cf5 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -166,6 +166,7 @@ void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
void blk_mq_finish_request(struct request *rq);
struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
unsigned int op);
+int blk_mq_get_queue_depth(struct request_queue *q);

static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
{
--
2.9.3