From 25c4b5e058578066db56d757ad3a7adeaff35856 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sat, 13 Nov 2021 13:37:38 -0700 Subject: [PATCH] blk-ioprio: don't set bio priority if not needed We don't need to write to the bio if: 1) No ioprio value has ever been assigned to the blkcg 2) We wouldn't anyway, depending on bio and blkcg IO priority Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/blk-ioprio.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c index 332a07761bf8..2e7f10e1c03f 100644 --- a/block/blk-ioprio.c +++ b/block/blk-ioprio.c @@ -62,6 +62,7 @@ struct ioprio_blkg { struct ioprio_blkcg { struct blkcg_policy_data cpd; enum prio_policy prio_policy; + bool prio_set; }; static inline struct ioprio_blkg *pd_to_ioprio(struct blkg_policy_data *pd) @@ -112,7 +113,7 @@ static ssize_t ioprio_set_prio_policy(struct kernfs_open_file *of, char *buf, if (ret < 0) return ret; blkcg->prio_policy = ret; - + blkcg->prio_set = true; return nbytes; } @@ -190,6 +191,10 @@ static void blkcg_ioprio_track(struct rq_qos *rqos, struct request *rq, struct bio *bio) { struct ioprio_blkcg *blkcg = ioprio_blkcg_from_bio(bio); + u16 prio; + + if (!blkcg->prio_set) + return; /* * Except for IOPRIO_CLASS_NONE, higher I/O priority numbers @@ -199,8 +204,10 @@ static void blkcg_ioprio_track(struct rq_qos *rqos, struct request *rq, * bio I/O priority is not modified. If the bio I/O priority equals * IOPRIO_CLASS_NONE, the cgroup I/O priority is assigned to the bio. */ - bio->bi_ioprio = max_t(u16, bio->bi_ioprio, - IOPRIO_PRIO_VALUE(blkcg->prio_policy, 0)); + prio = max_t(u16, bio->bi_ioprio, + IOPRIO_PRIO_VALUE(blkcg->prio_policy, 0)); + if (prio > bio->bi_ioprio) + bio->bi_ioprio = prio; } static void blkcg_ioprio_exit(struct rq_qos *rqos)