blk-throttle: clean up blkg_policy_data alloc/init/exit/free methods

With the recent addition of alloc and free methods, things became
messier.  This patch reorganizes them according to the followings.

* ->pd_alloc_fn()

  Responsible for allocation and static initializations - the ones
  which can be done independent of where the pd might be attached.

* ->pd_init_fn()

  Initializations which require the knowledge of where the pd is
  attached.

* ->pd_free_fn()

  The counter part of pd_alloc_fn().  Static de-init and freeing.

This leaves ->pd_exit_fn() without any users.  Removed.

While at it, collapse an one liner function throtl_pd_exit(), which
has only one user, into its user.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 69ce2883099e..4b795c7250ef 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1584,7 +1584,17 @@ static void cfq_cpd_init(const struct blkcg *blkcg)
 
 static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
 {
-	return kzalloc_node(sizeof(struct cfq_group), gfp, node);
+	struct cfq_group *cfqg;
+
+	cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
+	if (!cfqg)
+		return NULL;
+
+	cfq_init_cfqg_base(cfqg);
+	cfqg_stats_init(&cfqg->stats);
+	cfqg_stats_init(&cfqg->dead_stats);
+
+	return &cfqg->pd;
 }
 
 static void cfq_pd_init(struct blkcg_gq *blkg)
@@ -1592,11 +1602,8 @@ static void cfq_pd_init(struct blkcg_gq *blkg)
 	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
 	struct cfq_group_data *cgd = blkcg_to_cfqgd(blkg->blkcg);
 
-	cfq_init_cfqg_base(cfqg);
 	cfqg->weight = cgd->weight;
 	cfqg->leaf_weight = cgd->leaf_weight;
-	cfqg_stats_init(&cfqg->stats);
-	cfqg_stats_init(&cfqg->dead_stats);
 }
 
 static void cfq_pd_offline(struct blkcg_gq *blkg)