[PATCH 4/7] blk-mq: add and export helper to tell if a request is reserved

[Jens Axboe <axboe@fb.com>]

We only have an internal helper for checking a tag value. Add
an exported helper that takes a request and hardware queue,
and check against the driver tags.

Signed-off-by: Jens Axboe <axboe@fb.com>
---
 block/blk-mq-tag.c     | 6 ++++++
 include/linux/blk-mq.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index d0be72ccb091..0a04b5c14076 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -476,3 +476,9 @@ u32 blk_mq_unique_tag(struct request *rq)
 		(rq->tag & BLK_MQ_UNIQUE_TAG_MASK);
 }
 EXPORT_SYMBOL(blk_mq_unique_tag);
+
+bool blk_mq_rq_is_reserved(struct blk_mq_hw_ctx *hctx, struct request *rq)
+{
+	return blk_mq_tag_is_reserved(hctx->tags, rq->tag);
+}
+EXPORT_SYMBOL_GPL(blk_mq_rq_is_reserved);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 32bd8eb5ba67..13e51520fa27 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -224,6 +224,7 @@ static inline u16 blk_mq_unique_tag_to_tag(u32 unique_tag)
 	return unique_tag & BLK_MQ_UNIQUE_TAG_MASK;
 }
 
+bool blk_mq_rq_is_reserved(struct blk_mq_hw_ctx *hctx, struct request *rq);
 
 int blk_mq_request_started(struct request *rq);
 void blk_mq_start_request(struct request *rq);
-- 
2.7.4