[PATCH 4.19 063/346] block: factor out requeue handling from dispatch code

Greg Kroah-Hartman
2020-12-28T13:23:10Z

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

[ Upstream commit c92a41031a6d57395889b5c87cea359220a24d2a ]

Factor out the requeue handling from the dispatch code, this will make
subsequent addition of different requeueing schemes easier.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/blk-mq.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index db2db0b70d34f..0df43515ff949 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1118,6 +1118,23 @@ static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)

#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */

+static void blk_mq_handle_dev_resource(struct request *rq,
+ struct list_head *list)
+{
+ struct request *next =
+ list_first_entry_or_null(list, struct request, queuelist);
+
+ /*
+ * If an I/O scheduler has been configured and we got a driver tag for
+ * the next request already, free it.
+ */
+ if (next)
+ blk_mq_put_driver_tag(next);
+
+ list_add(&rq->queuelist, list);
+ __blk_mq_requeue_request(rq);
+}
+
/*
* Returns true if we did some work AND can potentially do more.
*/
@@ -1185,17 +1202,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,

ret = q->mq_ops->queue_rq(hctx, &bd);
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
- /*
- * If an I/O scheduler has been configured and we got a
- * driver tag for the next request already, free it
- * again.
- */
- if (!list_empty(list)) {
- nxt = list_first_entry(list, struct request, queuelist);
- blk_mq_put_driver_tag(nxt);
- }
- list_add(&rq->queuelist, list);
- __blk_mq_requeue_request(rq);
+ blk_mq_handle_dev_resource(rq, list);
break;
}

--
2.27.0