blk-ioprio: remove per-disk structure

ioprio works on the blk-cgroup level, all disks in the same cgroup
are the same, and the struct ioprio_blkg doesn't have anything in it.
Hence register the policy is enough, because cpd_alloc/free_fn will
be handled for each blk-cgroup, and there is no need to activate the
policy for disk. Hence remove blk_ioprio_init/exit and
ioprio_alloc/free_pd.

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/20240719071506.158075-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -1458,7 +1458,6 @@ int blkcg_init_disk(struct gendisk *disk)
 	struct request_queue *q = disk->queue;
 	struct blkcg_gq *new_blkg, *blkg;
 	bool preloaded;
-	int ret;
 
 	new_blkg = blkg_alloc(&blkcg_root, disk, GFP_KERNEL);
 	if (!new_blkg)
@@ -1478,15 +1477,8 @@ int blkcg_init_disk(struct gendisk *disk)
 	if (preloaded)
 		radix_tree_preload_end();
 
-	ret = blk_ioprio_init(disk);
-	if (ret)
-		goto err_destroy_all;
-
 	return 0;
 
-err_destroy_all:
-	blkg_destroy_all(disk);
-	return ret;
 err_unlock:
 	spin_unlock_irq(&q->queue_lock);
 	if (preloaded)

block/blk-ioprio.c

@@ -49,14 +49,6 @@ static const char *policy_name[] = {
 
 static struct blkcg_policy ioprio_policy;
 
-/**
- * struct ioprio_blkg - Per (cgroup, request queue) data.
- * @pd: blkg_policy_data structure.
- */
-struct ioprio_blkg {
-	struct blkg_policy_data pd;
-};
-
 /**
  * struct ioprio_blkcg - Per cgroup data.
  * @cpd: blkcg_policy_data structure.
@@ -67,11 +59,6 @@ struct ioprio_blkcg {
 	enum prio_policy	 prio_policy;
 };
 
-static inline struct ioprio_blkg *pd_to_ioprio(struct blkg_policy_data *pd)
-{
-	return pd ? container_of(pd, struct ioprio_blkg, pd) : NULL;
-}
-
 static struct ioprio_blkcg *blkcg_to_ioprio_blkcg(struct blkcg *blkcg)
 {
 	return container_of(blkcg_to_cpd(blkcg, &ioprio_policy),
@@ -108,25 +95,6 @@ static ssize_t ioprio_set_prio_policy(struct kernfs_open_file *of, char *buf,
 	return nbytes;
 }
 
-static struct blkg_policy_data *
-ioprio_alloc_pd(struct gendisk *disk, struct blkcg *blkcg, gfp_t gfp)
-{
-	struct ioprio_blkg *ioprio_blkg;
-
-	ioprio_blkg = kzalloc(sizeof(*ioprio_blkg), gfp);
-	if (!ioprio_blkg)
-		return NULL;
-
-	return &ioprio_blkg->pd;
-}
-
-static void ioprio_free_pd(struct blkg_policy_data *pd)
-{
-	struct ioprio_blkg *ioprio_blkg = pd_to_ioprio(pd);
-
-	kfree(ioprio_blkg);
-}
-
 static struct blkcg_policy_data *ioprio_alloc_cpd(gfp_t gfp)
 {
 	struct ioprio_blkcg *blkcg;
@@ -169,9 +137,6 @@ static struct blkcg_policy ioprio_policy = {
 
 	.cpd_alloc_fn	= ioprio_alloc_cpd,
 	.cpd_free_fn	= ioprio_free_cpd,
-
-	.pd_alloc_fn	= ioprio_alloc_pd,
-	.pd_free_fn	= ioprio_free_pd,
 };
 
 void blkcg_set_ioprio(struct bio *bio)
@@ -209,16 +174,6 @@ void blkcg_set_ioprio(struct bio *bio)
 		bio->bi_ioprio = prio;
 }
 
-void blk_ioprio_exit(struct gendisk *disk)
-{
-	blkcg_deactivate_policy(disk, &ioprio_policy);
-}
-
-int blk_ioprio_init(struct gendisk *disk)
-{
-	return blkcg_activate_policy(disk, &ioprio_policy);
-}
-
 static int __init ioprio_init(void)
 {
 	return blkcg_policy_register(&ioprio_policy);

block/blk-ioprio.h

@@ -9,17 +9,8 @@ struct request_queue;
 struct bio;
 
 #ifdef CONFIG_BLK_CGROUP_IOPRIO
-int blk_ioprio_init(struct gendisk *disk);
-void blk_ioprio_exit(struct gendisk *disk);
 void blkcg_set_ioprio(struct bio *bio);
 #else
-static inline int blk_ioprio_init(struct gendisk *disk)
-{
-	return 0;
-}
-static inline void blk_ioprio_exit(struct gendisk *disk)
-{
-}
 static inline void blkcg_set_ioprio(struct bio *bio)
 {
 }