[PATCH v2 12/12] block: mq-deadline: Handle requeued requests correctly

[Bart Van Assche <bvanassche@xxxxxxx>]

If a zoned write is requeued with an LBA that is lower than already
inserted zoned writes, make sure that it is submitted first.

Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
 block/mq-deadline.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index d49e20d3011d..c536b499a60f 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -162,8 +162,19 @@ static void
 deadline_add_rq_rb(struct dd_per_prio *per_prio, struct request *rq)
 {
 	struct rb_root *root = deadline_rb_root(per_prio, rq);
+	struct request **next_rq = &per_prio->next_rq[rq_data_dir(rq)];
 
 	elv_rb_add(root, rq);
+	if (*next_rq == NULL || !blk_queue_is_zoned(rq->q))
+		return;
+	/*
+	 * If a request got requeued or requests have been submitted out of
+	 * order, make sure that per zone the request with the lowest LBA is
+	 * submitted first.
+	 */
+	if (blk_rq_pos(rq) < blk_rq_pos(*next_rq) &&
+	    blk_rq_zone_no(rq) == blk_rq_zone_no(*next_rq))
+		*next_rq = rq;
 }
 
 static inline void
@@ -822,6 +833,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 		list_add(&rq->queuelist, &per_prio->dispatch);
 		rq->fifo_time = jiffies;
 	} else {
+		struct list_head *insert_before;
+
 		deadline_add_rq_rb(per_prio, rq);
 
 		if (rq_mergeable(rq)) {
@@ -834,7 +847,18 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 		 * set expire time and add to fifo list
 		 */
 		rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
-		list_add_tail(&rq->queuelist, &per_prio->fifo_list[data_dir]);
+		insert_before = &per_prio->fifo_list[data_dir];
+		if (blk_rq_is_seq_zoned_write(rq)) {
+			const unsigned int zno = blk_rq_zone_no(rq);
+			struct request *rq2 = rq;
+
+			while ((rq2 = deadline_earlier_request(rq2)) &&
+			       blk_rq_zone_no(rq2) == zno &&
+			       blk_rq_pos(rq2) > blk_rq_pos(rq)) {
+				insert_before = &rq2->queuelist;
+			}
+		}
+		list_add_tail(&rq->queuelist, insert_before);
 	}
 }