Re: [PATCH] mq-deadline: Fix request accounting
flat view
From: Bart Van Assche <bvanassche@acm.org>
Date: 2021-08-27 02:22:53
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
On 8/24/21 2:35 PM, Niklas Cassel wrote:
Reviewed-by: Niklas Cassel <redacted> Tested-by: Niklas Cassel <redacted>
Hi Niklas, Thank you for the help, that's really appreciated. Earlier today I discovered that this patch does not handle requeuing correctly so I have started testing the patch below. --- block/mq-deadline.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index dbd74bae9f11..c4c3c2e3f446 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c@@ -712,7 +712,10 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, blk_req_zone_write_unlock(rq); prio = ioprio_class_to_prio[ioprio_class]; - dd_count(dd, inserted, prio); + if (!rq->elv.priv[0]) { + dd_count(dd, inserted, prio); + rq->elv.priv[0] = (void *)(uintptr_t)1; + } if (blk_mq_sched_try_insert_merge(q, rq, &free)) { blk_mq_free_requests(&free);
@@ -761,12 +764,10 @@ static void dd_insert_requests(struct blk_mq_hw_ctx *hctx, spin_unlock(&dd->lock); } -/* - * Nothing to do here. This is defined only to ensure that .finish_request - * method is called upon request completion. - */ +/* Callback from inside blk_mq_rq_ctx_init(). */ static void dd_prepare_request(struct request *rq) { + rq->elv.priv[0] = NULL; } /*
@@ -793,6 +794,14 @@ static void dd_finish_request(struct request *rq) const enum dd_prio prio = ioprio_class_to_prio[ioprio_class]; struct dd_per_prio *per_prio = &dd->per_prio[prio]; + /* + * The block layer core may call dd_finish_request() without having + * called dd_insert_requests(). Skip requests that bypassed I/O + * scheduling. See also blk_mq_request_bypass_insert(). + */ + if (!rq->elv.priv[0]) + return; + dd_count(dd, completed, prio); if (blk_queue_is_zoned(q)) {