block: mq-deadline: Handle requeued requests correctly

Start dispatching from the start of a zone instead of from the starting
position of the most recently dispatched request.

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

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230517174230.897144-11-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index 91b6892..e908798 100644 (file)
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -156,13 +156,28 @@ deadline_latter_request(struct request *rq)
        return NULL;
 }
 
-/* Return the first request for which blk_rq_pos() >= pos. */
+/*
+ * Return the first request for which blk_rq_pos() >= @pos. For zoned devices,
+ * return the first request after the start of the zone containing @pos.
+ */
 static inline struct request *deadline_from_pos(struct dd_per_prio *per_prio,
                                enum dd_data_dir data_dir, sector_t pos)
 {
        struct rb_node *node = per_prio->sort_list[data_dir].rb_node;
        struct request *rq, *res = NULL;
 
+       if (!node)
+               return NULL;
+
+       rq = rb_entry_rq(node);
+       /*
+        * A zoned write may have been requeued with a starting position that
+        * is below that of the most recently dispatched request. Hence, for
+        * zoned writes, start searching from the start of a zone.
+        */
+       if (blk_rq_is_seq_zoned_write(rq))
+               pos -= round_down(pos, rq->q->limits.chunk_sectors);
+
        while (node) {
                rq = rb_entry_rq(node);
                if (blk_rq_pos(rq) >= pos) {
@@ -806,6 +821,8 @@ 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)) {
@@ -818,7 +835,20 @@ 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];
+#ifdef CONFIG_BLK_DEV_ZONED
+               /*
+                * Insert zoned writes such that requests are sorted by
+                * position per zone.
+                */
+               if (blk_rq_is_seq_zoned_write(rq)) {
+                       struct request *rq2 = deadline_latter_request(rq);
+
+                       if (rq2 && blk_rq_zone_no(rq2) == blk_rq_zone_no(rq))
+                               insert_before = &rq2->queuelist;
+               }
+#endif
+               list_add_tail(&rq->queuelist, insert_before);
        }
 }