blk-cgroup: pass blkg_rwstat structures by reference

Returning a structure generates rather bad code, so switch to passing
by reference.  Also don't require the structure to be zeroed and add
to the 0-initialized counters, but actually set the counters to the
calculated value.

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, 9 insertions, 6 deletions

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index b3796a40a61a..66abc82179f3 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -935,9 +935,9 @@ static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
 static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
                                         struct blkg_policy_data *pd, int off)
 {
-        struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
-                                                           &blkcg_policy_bfq,
-                                                           off);
+        struct blkg_rwstat sum;
+
+        blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum);
         return __blkg_prfill_rwstat(sf, pd, &sum);
 }
 
@@ -975,9 +975,12 @@ static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
 static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
                                          struct blkg_policy_data *pd, int off)
 {
-        struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
-                                        offsetof(struct blkcg_gq, stat_bytes));
-        u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
+        struct blkg_rwstat tmp;
+        u64 sum;
+
+        blkg_rwstat_recursive_sum(pd->blkg, NULL,
+                        offsetof(struct blkcg_gq, stat_bytes), &tmp);
+        sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
                 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
 
         return __blkg_prfill_u64(sf, pd, sum >> 9);