blk-cgroup: factor out a helper to read rwstat counter

Trying to break up the crazy statements to something readable.
Also switch to an unsigned counter as it can't ever turn negative.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 2 insertions, 3 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 440797293235..0778e52b1db2 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -745,7 +745,7 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
         struct blkcg_gq *pos_blkg;
         struct cgroup_subsys_state *pos_css;
         struct blkg_rwstat sum = { };
-        int i;
+        unsigned int i;
 
         lockdep_assert_held(&blkg->q->queue_lock);
 
@@ -762,8 +762,7 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
                         rwstat = (void *)pos_blkg + off;
 
                 for (i = 0; i < BLKG_RWSTAT_NR; i++)
-                        atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) +
-                                percpu_counter_sum_positive(&rwstat->cpu_cnt[i]),
+                        atomic64_add(blkg_rwstat_read_counter(rwstat, i),
                                 &sum.aux_cnt[i]);
         }
         rcu_read_unlock();