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Subject[PATCH 1/6] blk-cgroup: factor out a helper to read rwstat counter
Date
Trying to break up the crazy statements to something readable.
Also switch to an unsigned counter as it can't ever turn negative.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/blk-cgroup.c | 5 ++---
include/linux/blk-cgroup.h | 7 +++++++
2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b97b479e4f64..6f79ace02be4 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -750,7 +750,7 @@ 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);

@@ -767,8 +767,7 @@ 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();
diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h
index 76c61318fda5..06236f56a840 100644
--- a/include/linux/blk-cgroup.h
+++ b/include/linux/blk-cgroup.h
@@ -198,6 +198,13 @@ int blkcg_activate_policy(struct request_queue *q,
void blkcg_deactivate_policy(struct request_queue *q,
const struct blkcg_policy *pol);

+static inline u64 blkg_rwstat_read_counter(struct blkg_rwstat *rwstat,
+ unsigned int idx)
+{
+ return atomic64_read(&rwstat->aux_cnt[idx]) +
+ percpu_counter_sum_positive(&rwstat->cpu_cnt[idx]);
+}
+
const char *blkg_dev_name(struct blkcg_gq *blkg);
void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
u64 (*prfill)(struct seq_file *,
--
2.20.1
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