blk-cgroup: Make 64bit per cpu stats safe on 32bit arch

Some of the stats are 64bit and updation will be non atomic on 32bit
architecture. Use sequence counters on 32bit arch to make reading
of stats safe.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index fd730a24b491..262226798093 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -14,6 +14,7 @@
  */
 
 #include <linux/cgroup.h>
+#include <linux/u64_stats_sync.h>
 
 enum blkio_policy_id {
         BLKIO_POLICY_PROP = 0,          /* Proportional Bandwidth division */
@@ -154,6 +155,7 @@ struct blkio_group_stats {
 struct blkio_group_stats_cpu {
         uint64_t sectors;
         uint64_t stat_arr_cpu[BLKIO_STAT_CPU_NR][BLKIO_STAT_TOTAL];
+        struct u64_stats_sync syncp;
 };
 
 struct blkio_group {