block: move blk_get_flush_queue to blk-flush.c

blk_get_flush_queue is only used in blk-flush.c, so move it there.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211123185312.1432157-2-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-flush.c

@@ -95,6 +95,12 @@ enum {
 static void blk_kick_flush(struct request_queue *q,
 			   struct blk_flush_queue *fq, unsigned int flags);
 
+static inline struct blk_flush_queue *
+blk_get_flush_queue(struct request_queue *q, struct blk_mq_ctx *ctx)
+{
+	return blk_mq_map_queue(q, REQ_OP_FLUSH, ctx)->fq;
+}
+
 static unsigned int blk_flush_policy(unsigned long fflags, struct request *rq)
 {
 	unsigned int policy = 0;

block/blk.h

@@ -35,12 +35,6 @@ extern struct kmem_cache *blk_requestq_cachep;
 extern struct kobj_type blk_queue_ktype;
 extern struct ida blk_queue_ida;
 
-static inline struct blk_flush_queue *
-blk_get_flush_queue(struct request_queue *q, struct blk_mq_ctx *ctx)
-{
-	return blk_mq_map_queue(q, REQ_OP_FLUSH, ctx)->fq;
-}
-
 static inline void __blk_get_queue(struct request_queue *q)
 {
 	kobject_get(&q->kobj);