block: don't reorder requests in blk_add_rq_to_plug

Add requests to the tail of the list instead of the front so that they
are queued up in submission order.

Remove the re-reordering in blk_mq_dispatch_plug_list, virtio_queue_rqs
and nvme_queue_rqs now that the list is ordered as expected.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241113152050.157179-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ff0b819e35fc010b7b177cd129fcde63c5afcc82..270cfd9fc6b0c1f197cd673e29179ac4ec040c3d 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1392,7 +1392,7 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
         */
        if (!plug->has_elevator && (rq->rq_flags & RQF_SCHED_TAGS))
                plug->has_elevator = true;
-       rq_list_add_head(&plug->mq_list, rq);
+       rq_list_add_tail(&plug->mq_list, rq);
        plug->rq_count++;
 }
 
@@ -2844,7 +2844,7 @@ static void blk_mq_dispatch_plug_list(struct blk_plug *plug, bool from_sched)
                        rq_list_add_tail(&requeue_list, rq);
                        continue;
                }
-               list_add(&rq->queuelist, &list);
+               list_add_tail(&rq->queuelist, &list);
                depth++;
        } while (!rq_list_empty(&plug->mq_list));
 

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index a19f24c191408f4015a29ac8886096d82ca59972..c0cdba71f43640ccff96d83f9e63620bebdda2ab 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -514,7 +514,7 @@ static void virtio_queue_rqs(struct rq_list *rqlist)
                vq = this_vq;
 
                if (virtblk_prep_rq_batch(req))
-                       rq_list_add_head(&submit_list, req); /* reverse order */
+                       rq_list_add_tail(&submit_list, req);
                else
                        rq_list_add_tail(&requeue_list, req);
        }

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 707dbe8be6a2b47f349856b77cd2c4939beb55bb..5f2e3ad2cc521be206540ad2df0e66565a1fab9b 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -945,7 +945,7 @@ static void nvme_queue_rqs(struct rq_list *rqlist)
                nvmeq = req->mq_hctx->driver_data;
 
                if (nvme_prep_rq_batch(nvmeq, req))
-                       rq_list_add_head(&submit_list, req); /* reverse order */
+                       rq_list_add_tail(&submit_list, req);
                else
                        rq_list_add_tail(&requeue_list, req);
        }