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-rw-r--r--block/blk-cgroup.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 3622518e1c23..e41cc6f2ccc1 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -537,6 +537,30 @@ struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
}
EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
+static void blkio_reset_stats_cpu(struct blkio_group *blkg)
+{
+ struct blkio_group_stats_cpu *stats_cpu;
+ int i, j, k;
+ /*
+ * Note: On 64 bit arch this should not be an issue. This has the
+ * possibility of returning some inconsistent value on 32bit arch
+ * as 64bit update on 32bit is non atomic. Taking care of this
+ * corner case makes code very complicated, like sending IPIs to
+ * cpus, taking care of stats of offline cpus etc.
+ *
+ * reset stats is anyway more of a debug feature and this sounds a
+ * corner case. So I am not complicating the code yet until and
+ * unless this becomes a real issue.
+ */
+ for_each_possible_cpu(i) {
+ stats_cpu = per_cpu_ptr(blkg->stats_cpu, i);
+ stats_cpu->sectors = 0;
+ for(j = 0; j < BLKIO_STAT_CPU_NR; j++)
+ for (k = 0; k < BLKIO_STAT_TOTAL; k++)
+ stats_cpu->stat_arr_cpu[j][k] = 0;
+ }
+}
+
static int
blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
{
@@ -581,7 +605,11 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
}
#endif
spin_unlock(&blkg->stats_lock);
+
+ /* Reset Per cpu stats which don't take blkg->stats_lock */
+ blkio_reset_stats_cpu(blkg);
}
+
spin_unlock_irq(&blkcg->lock);
return 0;
}