block: move __elv_next_request to blk-core.c

No need to have this helper inline in a header.  Also drop the __ prefix.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 40 insertions, 2 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 048be4aa6024..14f7674fa0b1 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2517,6 +2517,45 @@ void blk_account_io_start(struct request *rq, bool new_io)
 	part_stat_unlock();
 }
 
+static struct request *elv_next_request(struct request_queue *q)
+{
+	struct request *rq;
+	struct blk_flush_queue *fq = blk_get_flush_queue(q, NULL);
+
+	WARN_ON_ONCE(q->mq_ops);
+
+	while (1) {
+		if (!list_empty(&q->queue_head)) {
+			rq = list_entry_rq(q->queue_head.next);
+			return rq;
+		}
+
+		/*
+		 * Flush request is running and flush request isn't queueable
+		 * in the drive, we can hold the queue till flush request is
+		 * finished. Even we don't do this, driver can't dispatch next
+		 * requests and will requeue them. And this can improve
+		 * throughput too. For example, we have request flush1, write1,
+		 * flush 2. flush1 is dispatched, then queue is hold, write1
+		 * isn't inserted to queue. After flush1 is finished, flush2
+		 * will be dispatched. Since disk cache is already clean,
+		 * flush2 will be finished very soon, so looks like flush2 is
+		 * folded to flush1.
+		 * Since the queue is hold, a flag is set to indicate the queue
+		 * should be restarted later. Please see flush_end_io() for
+		 * details.
+		 */
+		if (fq->flush_pending_idx != fq->flush_running_idx &&
+				!queue_flush_queueable(q)) {
+			fq->flush_queue_delayed = 1;
+			return NULL;
+		}
+		if (unlikely(blk_queue_bypass(q)) ||
+		    !q->elevator->type->ops.sq.elevator_dispatch_fn(q, 0))
+			return NULL;
+	}
+}
+
 /**
  * blk_peek_request - peek at the top of a request queue
  * @q: request queue to peek at
@@ -2538,8 +2577,7 @@ struct request *blk_peek_request(struct request_queue *q)
 	lockdep_assert_held(q->queue_lock);
 	WARN_ON_ONCE(q->mq_ops);
 
-	while ((rq = __elv_next_request(q)) != NULL) {
-
+	while ((rq = elv_next_request(q)) != NULL) {
 		rq = blk_pm_peek_request(q, rq);
 		if (!rq)
 			break;