blk-mq: remove REQ_END

Pass an explicit parameter for the last request in a batch to ->queue_rq
instead of using a request flag.  Besides being a cleaner and non-stateful
interface this is also required for the next patch, which fixes the blk-mq
I/O submission code to not start a time too early.

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

1 files changed, 5 insertions, 17 deletions

diff --git a/block/blk-mq.c b/block/blk-mq.c
index e743d28620b2..32b4797f4186 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -384,7 +384,7 @@ void blk_mq_complete_request(struct request *rq)
 }
 EXPORT_SYMBOL(blk_mq_complete_request);
 
-static void blk_mq_start_request(struct request *rq, bool last)
+static void blk_mq_start_request(struct request *rq)
 {
         struct request_queue *q = rq->q;
 
@@ -421,16 +421,6 @@ static void blk_mq_start_request(struct request *rq, bool last)
                  */
                 rq->nr_phys_segments++;
         }
-
-        /*
-         * Flag the last request in the series so that drivers know when IO
-         * should be kicked off, if they don't do it on a per-request basis.
-         *
-         * Note: the flag isn't the only condition drivers should do kick off.
-         * If drive is busy, the last request might not have the bit set.
-         */
-        if (last)
-                rq->cmd_flags |= REQ_END;
 }
 
 static void __blk_mq_requeue_request(struct request *rq)
@@ -440,8 +430,6 @@ static void __blk_mq_requeue_request(struct request *rq)
         trace_block_rq_requeue(q, rq);
         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 
-        rq->cmd_flags &= ~REQ_END;
-
         if (q->dma_drain_size && blk_rq_bytes(rq))
                 rq->nr_phys_segments--;
 }
@@ -755,9 +743,9 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
                 rq = list_first_entry(&rq_list, struct request, queuelist);
                 list_del_init(&rq->queuelist);
 
-                blk_mq_start_request(rq, list_empty(&rq_list));
+                blk_mq_start_request(rq);
 
-                ret = q->mq_ops->queue_rq(hctx, rq);
+                ret = q->mq_ops->queue_rq(hctx, rq, list_empty(&rq_list));
                 switch (ret) {
                 case BLK_MQ_RQ_QUEUE_OK:
                         queued++;
@@ -1198,14 +1186,14 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
                 int ret;
 
                 blk_mq_bio_to_request(rq, bio);
-                blk_mq_start_request(rq, true);
+                blk_mq_start_request(rq);
 
                 /*
                  * For OK queue, we are done. For error, kill it. Any other
                  * error (busy), just add it to our list as we previously
                  * would have done
                  */
-                ret = q->mq_ops->queue_rq(data.hctx, rq);
+                ret = q->mq_ops->queue_rq(data.hctx, rq, true);
                 if (ret == BLK_MQ_RQ_QUEUE_OK)
                         goto done;
                 else {