2 files changed, 24 insertions, 5 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 34bfcefdd924..3622518e1c23 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -400,14 +400,25 @@ void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
                                 uint64_t bytes, bool direction, bool sync)
 {
         struct blkio_group_stats_cpu *stats_cpu;
+        unsigned long flags;
+
+        /*
+         * Disabling interrupts to provide mutual exclusion between two
+         * writes on same cpu. It probably is not needed for 64bit. Not
+         * optimizing that case yet.
+         */
+        local_irq_save(flags);
 
         stats_cpu = this_cpu_ptr(blkg->stats_cpu);
 
+        u64_stats_update_begin(&stats_cpu->syncp);
         stats_cpu->sectors += bytes >> 9;
         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICED],
                         1, direction, sync);
         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICE_BYTES],
                         bytes, direction, sync);
+        u64_stats_update_end(&stats_cpu->syncp);
+        local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
 
@@ -622,15 +633,21 @@ static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg,
 {
         int cpu;
         struct blkio_group_stats_cpu *stats_cpu;
-        uint64_t val = 0;
+        u64 val = 0, tval;
 
         for_each_possible_cpu(cpu) {
+                unsigned int start;
                 stats_cpu  = per_cpu_ptr(blkg->stats_cpu, cpu);
 
-                if (type == BLKIO_STAT_CPU_SECTORS)
-                        val += stats_cpu->sectors;
-                else
-                        val += stats_cpu->stat_arr_cpu[type][sub_type];
+                do {
+                        start = u64_stats_fetch_begin(&stats_cpu->syncp);
+                        if (type == BLKIO_STAT_CPU_SECTORS)
+                                tval = stats_cpu->sectors;
+                        else
+                                tval = stats_cpu->stat_arr_cpu[type][sub_type];
+                } while(u64_stats_fetch_retry(&stats_cpu->syncp, start));
+
+                val += tval;
         }
 
         return val;
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 {