blk-mq: make sure elevator callbacks aren't called for passthrough request
In case of q->elevator, passthrough request can still be marked as
RQF_ELV, so some elevator callbacks will be called for them.
Fix this by splitting RQF_SCHED_TAGS, which is set for all requests that
are issued on a queue that uses an I/O scheduler, and RQF_USE_SCHED for
non-flush, non-passthrough requests on such a queue.
Roughly based on two different patches from
Ming Lei <ming.lei@redhat.com>.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230518053101.760632-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7470c66..e021740 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -354,12 +354,12 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
data->rq_flags |= RQF_IO_STAT;
rq->rq_flags = data->rq_flags;
- if (!(data->rq_flags & RQF_ELV)) {
- rq->tag = tag;
- rq->internal_tag = BLK_MQ_NO_TAG;
- } else {
+ if (data->rq_flags & RQF_SCHED_TAGS) {
rq->tag = BLK_MQ_NO_TAG;
rq->internal_tag = tag;
+ } else {
+ rq->tag = tag;
+ rq->internal_tag = BLK_MQ_NO_TAG;
}
rq->timeout = 0;
@@ -386,14 +386,13 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
WRITE_ONCE(rq->deadline, 0);
req_ref_set(rq, 1);
- if (rq->rq_flags & RQF_ELV) {
+ if (rq->rq_flags & RQF_USE_SCHED) {
struct elevator_queue *e = data->q->elevator;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
- if (!op_is_flush(data->cmd_flags) &&
- e->type->ops.prepare_request)
+ if (e->type->ops.prepare_request)
e->type->ops.prepare_request(rq);
}
@@ -447,26 +446,32 @@ static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
data->flags |= BLK_MQ_REQ_NOWAIT;
if (q->elevator) {
- struct elevator_queue *e = q->elevator;
-
- data->rq_flags |= RQF_ELV;
+ /*
+ * All requests use scheduler tags when an I/O scheduler is
+ * enabled for the queue.
+ */
+ data->rq_flags |= RQF_SCHED_TAGS;
/*
* Flush/passthrough requests are special and go directly to the
- * dispatch list. Don't include reserved tags in the
- * limiting, as it isn't useful.
+ * dispatch list.
*/
if (!op_is_flush(data->cmd_flags) &&
- !blk_op_is_passthrough(data->cmd_flags) &&
- e->type->ops.limit_depth &&
- !(data->flags & BLK_MQ_REQ_RESERVED))
- e->type->ops.limit_depth(data->cmd_flags, data);
+ !blk_op_is_passthrough(data->cmd_flags)) {
+ struct elevator_mq_ops *ops = &q->elevator->type->ops;
+
+ WARN_ON_ONCE(data->flags & BLK_MQ_REQ_RESERVED);
+
+ data->rq_flags |= RQF_USE_SCHED;
+ if (ops->limit_depth)
+ ops->limit_depth(data->cmd_flags, data);
+ }
}
retry:
data->ctx = blk_mq_get_ctx(q);
data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx);
- if (!(data->rq_flags & RQF_ELV))
+ if (!(data->rq_flags & RQF_SCHED_TAGS))
blk_mq_tag_busy(data->hctx);
if (data->flags & BLK_MQ_REQ_RESERVED)
@@ -646,10 +651,10 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
goto out_queue_exit;
data.ctx = __blk_mq_get_ctx(q, cpu);
- if (!q->elevator)
- blk_mq_tag_busy(data.hctx);
+ if (q->elevator)
+ data.rq_flags |= RQF_SCHED_TAGS;
else
- data.rq_flags |= RQF_ELV;
+ blk_mq_tag_busy(data.hctx);
if (flags & BLK_MQ_REQ_RESERVED)
data.rq_flags |= RQF_RESV;
@@ -694,7 +699,7 @@ void blk_mq_free_request(struct request *rq)
struct request_queue *q = rq->q;
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
- if ((rq->rq_flags & RQF_ELV) && !op_is_flush(rq->cmd_flags) &&
+ if ((rq->rq_flags & RQF_USE_SCHED) &&
q->elevator->type->ops.finish_request)
q->elevator->type->ops.finish_request(rq);
@@ -1268,7 +1273,7 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
if (!plug->multiple_queues && last && last->q != rq->q)
plug->multiple_queues = true;
- if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
+ if (!plug->has_elevator && (rq->rq_flags & RQF_USE_SCHED))
plug->has_elevator = true;
rq->rq_next = NULL;
rq_list_add(&plug->mq_list, rq);
@@ -2620,7 +2625,7 @@ static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
return;
}
- if ((rq->rq_flags & RQF_ELV) || !blk_mq_get_budget_and_tag(rq)) {
+ if ((rq->rq_flags & RQF_USE_SCHED) || !blk_mq_get_budget_and_tag(rq)) {
blk_mq_insert_request(rq, 0);
blk_mq_run_hw_queue(hctx, false);
return;
@@ -2983,7 +2988,7 @@ void blk_mq_submit_bio(struct bio *bio)
}
hctx = rq->mq_hctx;
- if ((rq->rq_flags & RQF_ELV) ||
+ if ((rq->rq_flags & RQF_USE_SCHED) ||
(hctx->dispatch_busy && (q->nr_hw_queues == 1 || !is_sync))) {
blk_mq_insert_request(rq, 0);
blk_mq_run_hw_queue(hctx, true);
