block, bfq: remove BFQ_WEIGHT_LEGACY_DFL

BFQ_WEIGHT_LEGACY_DFL is the same as CGROUP_WEIGHT_DFL, which means
we don't need cpd_bind_fn() callback to update default weight when
attached to a hierarchy.

This patch remove BFQ_WEIGHT_LEGACY_DFL and cpd_bind_fn().
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230406145050.49914-2-zhouchengming@bytedance.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/bfq-cgroup.c

@@ -504,8 +504,7 @@ static void bfq_cpd_init(struct blkcg_policy_data *cpd)
 {
 	struct bfq_group_data *d = cpd_to_bfqgd(cpd);
 
-	d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
-		CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
+	d->weight = CGROUP_WEIGHT_DFL;
 }
 
 static void bfq_cpd_free(struct blkcg_policy_data *cpd)
@@ -1302,7 +1301,6 @@ struct blkcg_policy blkcg_policy_bfq = {
 
 	.cpd_alloc_fn		= bfq_cpd_alloc,
 	.cpd_init_fn		= bfq_cpd_init,
-	.cpd_bind_fn	        = bfq_cpd_init,
 	.cpd_free_fn		= bfq_cpd_free,
 
 	.pd_alloc_fn		= bfq_pd_alloc,

block/bfq-iosched.h

@@ -20,7 +20,6 @@
 
 #define BFQ_DEFAULT_QUEUE_IOPRIO	4
 
-#define BFQ_WEIGHT_LEGACY_DFL	100
 #define BFQ_DEFAULT_GRP_IOPRIO	0
 #define BFQ_DEFAULT_GRP_CLASS	IOPRIO_CLASS_BE