[RFC 1/3] block/mq: add iterator for polling hw queues

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

Add one helper function for iterating all hardware queues in polling
mode.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
 include/linux/blk-mq.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index b23eeca4d677..81c70ce97715 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -571,6 +571,12 @@ static inline void *blk_mq_rq_to_pdu(struct request *rq)
 	for ((i) = 0; (i) < (q)->nr_hw_queues &&			\
 	     ({ hctx = (q)->queue_hw_ctx[i]; 1; }); (i)++)
 
+#define queue_for_each_poll_hw_ctx(q, hctx, i)				\
+	for ((i) = 0; ((q)->tag_set->nr_maps > HCTX_TYPE_POLL) &&	\
+	     (i) < (q)->tag_set->map[HCTX_TYPE_POLL].nr_queues &&	\
+	     ({ hctx = (q)->queue_hw_ctx[((q)->tag_set->map[HCTX_TYPE_POLL].queue_offset + (i))]; 1; }); \
+	     (i)++)
+
 #define hctx_for_each_ctx(hctx, ctx, i)					\
 	for ((i) = 0; (i) < (hctx)->nr_ctx &&				\
 	     ({ ctx = (hctx)->ctxs[(i)]; 1; }); (i)++)
-- 
2.27.0