[PATCH v5 07/12] blk-mq: add one helper function getting hw queue

[Jeffle Xu <jefflexu@linux.alibaba.com>]

Add one helper function getting hw queue mapping to specific CPU, and of
specific type.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 block/blk-mq.c         | 10 ++++++++++
 include/linux/blk-mq.h |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6ef9f0b038c2..72390f208c82 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3902,6 +3902,16 @@ unsigned int blk_mq_rq_cpu(struct request *rq)
 }
 EXPORT_SYMBOL(blk_mq_rq_cpu);
 
+
+struct blk_mq_hw_ctx *blk_mq_get_hctx(struct request_queue *q, int cpu,
+				      unsigned int flags)
+{
+	struct blk_mq_ctx *ctx = __blk_mq_get_ctx(q, cpu);
+
+	return blk_mq_map_queue(q, flags, ctx);
+}
+EXPORT_SYMBOL(blk_mq_get_hctx);
+
 static int __init blk_mq_init(void)
 {
 	int i;
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index d22269b3dbe9..149f6a9d9aa7 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -638,5 +638,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio);
 int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin);
 void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
 		struct lock_class_key *key);
+struct blk_mq_hw_ctx *blk_mq_get_hctx(struct request_queue *q, int cpu,
+		unsigned int flags);
 
 #endif
-- 
2.27.0