blk-cgroup: delete cpd_init_fn of blkcg_policy

blkcg_policy cpd_init_fn() is used to just initialize some default
fields of policy data, which is enough to do in cpd_alloc_fn().

This patch delete the only user bfq_cpd_init(), and remove cpd_init_fn
from blkcg_policy.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230406145050.49914-4-zhouchengming@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Chengming Zhou

block/bfq-cgroup.c

@@ -497,14 +497,9 @@ static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
 	bgd = kzalloc(sizeof(*bgd), gfp);
 	if (!bgd)
 		return NULL;
-	return &bgd->pd;
-}
 
-static void bfq_cpd_init(struct blkcg_policy_data *cpd)
-{
-	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
-
-	d->weight = CGROUP_WEIGHT_DFL;
+	bgd->weight = CGROUP_WEIGHT_DFL;
+	return &bgd->pd;
 }
 
 static void bfq_cpd_free(struct blkcg_policy_data *cpd)
@@ -1300,7 +1295,6 @@ struct blkcg_policy blkcg_policy_bfq = {
 	.legacy_cftypes		= bfq_blkcg_legacy_files,
 
 	.cpd_alloc_fn		= bfq_cpd_alloc,
-	.cpd_init_fn		= bfq_cpd_init,
 	.cpd_free_fn		= bfq_cpd_free,
 
 	.pd_alloc_fn		= bfq_pd_alloc,

block/blk-cgroup.c

@@ -1249,8 +1249,6 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
 		blkcg->cpd[i] = cpd;
 		cpd->blkcg = blkcg;
 		cpd->plid = i;
-		if (pol->cpd_init_fn)
-			pol->cpd_init_fn(cpd);
 	}
 
 	spin_lock_init(&blkcg->lock);
@@ -1605,8 +1603,6 @@ int blkcg_policy_register(struct blkcg_policy *pol)
 			blkcg->cpd[pol->plid] = cpd;
 			cpd->blkcg = blkcg;
 			cpd->plid = pol->plid;
-			if (pol->cpd_init_fn)
-				pol->cpd_init_fn(cpd);
 		}
 	}
 

block/blk-cgroup.h

@@ -173,7 +173,6 @@ struct blkcg_policy {
 
 	/* operations */
 	blkcg_pol_alloc_cpd_fn		*cpd_alloc_fn;
-	blkcg_pol_init_cpd_fn		*cpd_init_fn;
 	blkcg_pol_free_cpd_fn		*cpd_free_fn;
 
 	blkcg_pol_alloc_pd_fn		*pd_alloc_fn;