6.18-stable review patch. If anyone has any objections, please let me know.
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From: Bart Van Assche bvanassche@acm.org
[ Upstream commit d60055cf52703a705b86fb25b9b7931ec7ee399c ]
Commit c807ab520fc3 ("block/mq-deadline: Add I/O priority support") modified the behavior of request flag BLK_MQ_INSERT_AT_HEAD from dispatching a request before other requests into dispatching a request before other requests with the same I/O priority. This is not correct since BLK_MQ_INSERT_AT_HEAD is used when requeuing requests and also when a flush request is inserted. Both types of requests should be dispatched as soon as possible. Hence, make the mq-deadline I/O scheduler again ignore the I/O priority for BLK_MQ_INSERT_AT_HEAD requests.
Cc: Damien Le Moal dlemoal@kernel.org Cc: Yu Kuai yukuai@kernel.org Reported-by: chengkaitao chengkaitao@kylinos.cn Closes: https://lore.kernel.org/linux-block/20251009155253.14611-1-pilgrimtao@gmail.... Fixes: c807ab520fc3 ("block/mq-deadline: Add I/O priority support") Signed-off-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Damien Le Moalv dlemoal@kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/mq-deadline.c | 107 +++++++++++++++++++------------------------- 1 file changed, 47 insertions(+), 60 deletions(-)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 647a45f6d9352..3e3719093aec7 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -71,7 +71,6 @@ struct io_stats_per_prio { * present on both sort_list[] and fifo_list[]. */ struct dd_per_prio { - struct list_head dispatch; struct rb_root sort_list[DD_DIR_COUNT]; struct list_head fifo_list[DD_DIR_COUNT]; /* Position of the most recently dispatched request. */ @@ -84,6 +83,7 @@ struct deadline_data { * run time data */
+ struct list_head dispatch; struct dd_per_prio per_prio[DD_PRIO_COUNT];
/* Data direction of latest dispatched request. */ @@ -332,16 +332,6 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd,
lockdep_assert_held(&dd->lock);
- if (!list_empty(&per_prio->dispatch)) { - rq = list_first_entry(&per_prio->dispatch, struct request, - queuelist); - if (started_after(dd, rq, latest_start)) - return NULL; - list_del_init(&rq->queuelist); - data_dir = rq_data_dir(rq); - goto done; - } - /* * batches are currently reads XOR writes */ @@ -421,7 +411,6 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd, */ dd->batching++; deadline_move_request(dd, per_prio, rq); -done: return dd_start_request(dd, data_dir, rq); }
@@ -469,6 +458,14 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) enum dd_prio prio;
spin_lock(&dd->lock); + + if (!list_empty(&dd->dispatch)) { + rq = list_first_entry(&dd->dispatch, struct request, queuelist); + list_del_init(&rq->queuelist); + dd_start_request(dd, rq_data_dir(rq), rq); + goto unlock; + } + rq = dd_dispatch_prio_aged_requests(dd, now); if (rq) goto unlock; @@ -557,10 +554,10 @@ static int dd_init_sched(struct request_queue *q, struct elevator_queue *eq)
eq->elevator_data = dd;
+ INIT_LIST_HEAD(&dd->dispatch); for (prio = 0; prio <= DD_PRIO_MAX; prio++) { struct dd_per_prio *per_prio = &dd->per_prio[prio];
- INIT_LIST_HEAD(&per_prio->dispatch); INIT_LIST_HEAD(&per_prio->fifo_list[DD_READ]); INIT_LIST_HEAD(&per_prio->fifo_list[DD_WRITE]); per_prio->sort_list[DD_READ] = RB_ROOT; @@ -664,7 +661,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, trace_block_rq_insert(rq);
if (flags & BLK_MQ_INSERT_AT_HEAD) { - list_add(&rq->queuelist, &per_prio->dispatch); + list_add(&rq->queuelist, &dd->dispatch); rq->fifo_time = jiffies; } else { deadline_add_rq_rb(per_prio, rq); @@ -731,8 +728,7 @@ static void dd_finish_request(struct request *rq)
static bool dd_has_work_for_prio(struct dd_per_prio *per_prio) { - return !list_empty_careful(&per_prio->dispatch) || - !list_empty_careful(&per_prio->fifo_list[DD_READ]) || + return !list_empty_careful(&per_prio->fifo_list[DD_READ]) || !list_empty_careful(&per_prio->fifo_list[DD_WRITE]); }
@@ -741,6 +737,9 @@ static bool dd_has_work(struct blk_mq_hw_ctx *hctx) struct deadline_data *dd = hctx->queue->elevator->elevator_data; enum dd_prio prio;
+ if (!list_empty_careful(&dd->dispatch)) + return true; + for (prio = 0; prio <= DD_PRIO_MAX; prio++) if (dd_has_work_for_prio(&dd->per_prio[prio])) return true; @@ -949,49 +948,39 @@ static int dd_owned_by_driver_show(void *data, struct seq_file *m) return 0; }
-#define DEADLINE_DISPATCH_ATTR(prio) \ -static void *deadline_dispatch##prio##_start(struct seq_file *m, \ - loff_t *pos) \ - __acquires(&dd->lock) \ -{ \ - struct request_queue *q = m->private; \ - struct deadline_data *dd = q->elevator->elevator_data; \ - struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ - \ - spin_lock(&dd->lock); \ - return seq_list_start(&per_prio->dispatch, *pos); \ -} \ - \ -static void *deadline_dispatch##prio##_next(struct seq_file *m, \ - void *v, loff_t *pos) \ -{ \ - struct request_queue *q = m->private; \ - struct deadline_data *dd = q->elevator->elevator_data; \ - struct dd_per_prio *per_prio = &dd->per_prio[prio]; \ - \ - return seq_list_next(v, &per_prio->dispatch, pos); \ -} \ - \ -static void deadline_dispatch##prio##_stop(struct seq_file *m, void *v) \ - __releases(&dd->lock) \ -{ \ - struct request_queue *q = m->private; \ - struct deadline_data *dd = q->elevator->elevator_data; \ - \ - spin_unlock(&dd->lock); \ -} \ - \ -static const struct seq_operations deadline_dispatch##prio##_seq_ops = { \ - .start = deadline_dispatch##prio##_start, \ - .next = deadline_dispatch##prio##_next, \ - .stop = deadline_dispatch##prio##_stop, \ - .show = blk_mq_debugfs_rq_show, \ +static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos) + __acquires(&dd->lock) +{ + struct request_queue *q = m->private; + struct deadline_data *dd = q->elevator->elevator_data; + + spin_lock(&dd->lock); + return seq_list_start(&dd->dispatch, *pos); }
-DEADLINE_DISPATCH_ATTR(0); -DEADLINE_DISPATCH_ATTR(1); -DEADLINE_DISPATCH_ATTR(2); -#undef DEADLINE_DISPATCH_ATTR +static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos) +{ + struct request_queue *q = m->private; + struct deadline_data *dd = q->elevator->elevator_data; + + return seq_list_next(v, &dd->dispatch, pos); +} + +static void deadline_dispatch_stop(struct seq_file *m, void *v) + __releases(&dd->lock) +{ + struct request_queue *q = m->private; + struct deadline_data *dd = q->elevator->elevator_data; + + spin_unlock(&dd->lock); +} + +static const struct seq_operations deadline_dispatch_seq_ops = { + .start = deadline_dispatch_start, + .next = deadline_dispatch_next, + .stop = deadline_dispatch_stop, + .show = blk_mq_debugfs_rq_show, +};
#define DEADLINE_QUEUE_DDIR_ATTRS(name) \ {#name "_fifo_list", 0400, \ @@ -1014,9 +1003,7 @@ static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = { {"batching", 0400, deadline_batching_show}, {"starved", 0400, deadline_starved_show}, {"async_depth", 0400, dd_async_depth_show}, - {"dispatch0", 0400, .seq_ops = &deadline_dispatch0_seq_ops}, - {"dispatch1", 0400, .seq_ops = &deadline_dispatch1_seq_ops}, - {"dispatch2", 0400, .seq_ops = &deadline_dispatch2_seq_ops}, + {"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops}, {"owned_by_driver", 0400, dd_owned_by_driver_show}, {"queued", 0400, dd_queued_show}, {},