[PATCHv2 1/5] block: add request polling helper

[Keith Busch]

From: Keith Busch <kbusch at kernel.org>

This will be used by drivers that allocate polling requests.

Signed-off-by: Keith Busch <kbusch at kernel.org>
---
 block/blk-mq.c         | 18 ++++++++++++++++++
 include/linux/blk-mq.h |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1b304f66f4e8e..67707a488b7e5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4737,6 +4737,24 @@ int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, struct io_comp_batch *
 	return 0;
 }
 
+int blk_rq_poll(struct request *rq, struct io_comp_batch *iob,
+		unsigned int poll_flags)
+{
+	struct request_queue *q = rq->q;
+	int ret;
+
+	if (!blk_rq_is_poll(rq))
+		return 0;
+	if (!percpu_ref_tryget(&q->q_usage_counter))
+		return 0;
+
+	ret = blk_mq_poll(q, blk_rq_to_qc(rq), iob, poll_flags);
+	blk_queue_exit(q);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blk_rq_poll);
+
 unsigned int blk_mq_rq_cpu(struct request *rq)
 {
 	return rq->mq_ctx->cpu;
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 06caacd77ed66..579818fa1f91d 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -722,6 +722,8 @@ int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
 void blk_mq_free_tag_set(struct blk_mq_tag_set *set);
 
 void blk_mq_free_request(struct request *rq);
+int blk_rq_poll(struct request *rq, struct io_comp_batch *iob,
+		unsigned int poll_flags);
 
 bool blk_mq_queue_inflight(struct request_queue *q);
 
-- 
2.34.1