blk-ioprio: remove ioprio_blkcg_from_bio()

Currently, if config is enabled, then ioprio is always enabled by
default from blkcg_init_disk(), hence there is no point to check if
the policy is enabled from blkg in ioprio_blkcg_from_bio(). Hence remove
it and get blkcg directly from bio.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240719071506.158075-3-yukuai1@huaweicloud.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-ioprio.c

@@ -84,16 +84,6 @@ ioprio_blkcg_from_css(struct cgroup_subsys_state *css)
 	return blkcg_to_ioprio_blkcg(css_to_blkcg(css));
 }
 
-static struct ioprio_blkcg *ioprio_blkcg_from_bio(struct bio *bio)
-{
-	struct blkg_policy_data *pd = blkg_to_pd(bio->bi_blkg, &ioprio_policy);
-
-	if (!pd)
-		return NULL;
-
-	return blkcg_to_ioprio_blkcg(pd->blkg->blkcg);
-}
-
 static int ioprio_show_prio_policy(struct seq_file *sf, void *v)
 {
 	struct ioprio_blkcg *blkcg = ioprio_blkcg_from_css(seq_css(sf));
@@ -186,7 +176,7 @@ static struct blkcg_policy ioprio_policy = {
 
 void blkcg_set_ioprio(struct bio *bio)
 {
-	struct ioprio_blkcg *blkcg = ioprio_blkcg_from_bio(bio);
+	struct ioprio_blkcg *blkcg = blkcg_to_ioprio_blkcg(bio->bi_blkg->blkcg);
 	u16 prio;
 
 	if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE)