block: mq-deadline: Fix handling of at-head zoned writes
Before dispatching a zoned write from the FIFO list, check whether there
are any zoned writes in the RB-tree with a lower LBA for the same zone.
This patch ensures that zoned writes happen in order even if at_head is
set for some writes for a zone and not for others.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230517174230.897144-12-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index e908798..6aa5daf 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -346,7 +346,7 @@ static struct request *
deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
enum dd_data_dir data_dir)
{
- struct request *rq;
+ struct request *rq, *rb_rq, *next;
unsigned long flags;
if (list_empty(&per_prio->fifo_list[data_dir]))
@@ -364,7 +364,12 @@ deadline_fifo_request(struct deadline_data *dd, struct dd_per_prio *per_prio,
* zones and these zones are unlocked.
*/
spin_lock_irqsave(&dd->zone_lock, flags);
- list_for_each_entry(rq, &per_prio->fifo_list[DD_WRITE], queuelist) {
+ list_for_each_entry_safe(rq, next, &per_prio->fifo_list[DD_WRITE],
+ queuelist) {
+ /* Check whether a prior request exists for the same zone. */
+ rb_rq = deadline_from_pos(per_prio, data_dir, blk_rq_pos(rq));
+ if (rb_rq && blk_rq_pos(rb_rq) < blk_rq_pos(rq))
+ rq = rb_rq;
if (blk_req_can_dispatch_to_zone(rq) &&
(blk_queue_nonrot(rq->q) ||
!deadline_is_seq_write(dd, rq)))
