cgroup: change rstat function signatures from cgroup-based to css-based

This non-functional change serves as preparation for moving to
subsystem-based rstat trees. To simplify future commits, change the
signatures of existing cgroup-based rstat functions to become css-based and
rename them to reflect that.

Though the signatures have changed, the implementations have not. Within
these functions use the css->cgroup pointer to obtain the associated cgroup
and allow code to function the same just as it did before this patch. At
applicable call sites, pass the subsystem-specific css pointer as an
argument or pass a pointer to cgroup::self if not in subsystem context.

Note that cgroup_rstat_updated_list() and cgroup_rstat_push_children()
are not altered yet since there would be a larger amount of css to
cgroup conversions which may overcomplicate the code at this
intermediate phase.

Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 5905f277057b..0560ea402856 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1144,7 +1144,7 @@ static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu)
 /*
  * We source root cgroup stats from the system-wide stats to avoid
  * tracking the same information twice and incurring overhead when no
- * cgroups are defined. For that reason, cgroup_rstat_flush in
+ * cgroups are defined. For that reason, css_rstat_flush in
  * blkcg_print_stat does not actually fill out the iostat in the root
  * cgroup's blkcg_gq.
  *
@@ -1253,7 +1253,7 @@ static int blkcg_print_stat(struct seq_file *sf, void *v)
 	if (!seq_css(sf)->parent)
 		blkcg_fill_root_iostats();
 	else
-		cgroup_rstat_flush(blkcg->css.cgroup);
+		css_rstat_flush(&blkcg->css);
 
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
@@ -2243,7 +2243,7 @@ void blk_cgroup_bio_start(struct bio *bio)
 	}
 
 	u64_stats_update_end_irqrestore(&bis->sync, flags);
-	cgroup_rstat_updated(blkcg->css.cgroup, cpu);
+	css_rstat_updated(&blkcg->css, cpu);
 	put_cpu();
 }