From 455ddf1252e691d1eaa701de94e1421959a1aac9 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Mon, 5 Aug 2013 14:04:14 -0400
Subject: [PATCH] dm stats: factor out dm_stat_initialize_temporary_percpu_totals

fixing @stats_clear in the process
---
 drivers/md/dm-stats.c |   57 ++++++++++++++++++++++++++++--------------------
 1 files changed, 33 insertions(+), 24 deletions(-)

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 2aaa18a..2c30f78 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -352,7 +352,32 @@ void dm_stats_bio(struct dm_stats *st,
 	rcu_read_unlock();
 }
 
-static void dm_stat_clear(struct dm_stat *m)
+static void dm_stat_initialize_temporary_percpu_totals(struct dm_stat_shared *s,
+						       struct dm_stat *m, size_t x)
+{
+	int cpu;
+	struct dm_stat_percpu *p;
+
+	local_irq_disable();
+	p = &m->stat_percpu[smp_processor_id()][x];
+	dm_stat_round(s, p);
+	local_irq_enable();
+
+	memset(&s->tmp, 0, sizeof(s->tmp));
+	for_each_possible_cpu(cpu) {
+		p = &m->stat_percpu[cpu][x];
+		s->tmp.sectors[0] += p->sectors[0];
+		s->tmp.sectors[1] += p->sectors[1];
+		s->tmp.ios[0] += p->ios[0];
+		s->tmp.ios[1] += p->ios[1];
+		s->tmp.ticks[0] += p->ticks[0];
+		s->tmp.ticks[1] += p->ticks[1];
+		s->tmp.io_ticks += p->io_ticks;
+		s->tmp.time_in_queue += p->time_in_queue;
+	}
+}
+
+static void dm_stat_clear(struct dm_stat *m, bool init_tmp_percpu_totals)
 {
 	size_t x;
 	struct dm_stat_shared *s;
@@ -360,6 +385,8 @@ static void dm_stat_clear(struct dm_stat *m)
 
 	for (x = 0; x < m->n_entries; x++) {
 		s = &m->stat_shared[x];
+		if (init_tmp_percpu_totals)
+			dm_stat_initialize_temporary_percpu_totals(s, m, x);
 		local_irq_disable();
 		p = &m->stat_percpu[smp_processor_id()][x];
 		p->sectors[0] -= s->tmp.sectors[0];
@@ -382,7 +409,7 @@ static int dm_stats_clear(struct dm_stats *st, int id)
 	if (!m)
 		return -ENOENT;
 
-	dm_stat_clear(m);
+	dm_stat_clear(m, true);
 
 	return 1;
 }
@@ -394,6 +421,7 @@ static int dm_stats_print(struct dm_stats *st, int id, bool clear,
 	struct dm_stat *m;
 	size_t x;
 	sector_t start, end;
+	struct dm_stat_shared *s;
 
 	m = dm_stats_find(st, id);
 	if (!m)
@@ -402,31 +430,12 @@ static int dm_stats_print(struct dm_stats *st, int id, bool clear,
 	start = m->start;
 
 	for (x = 0; x < m->n_entries; x++, start = end) {
-		int cpu;
-		struct dm_stat_shared *s = &m->stat_shared[x];
-		struct dm_stat_percpu *p;
-
+		s = &m->stat_shared[x];
 		end = start + m->step;
 		if (unlikely(end > m->end))
 			end = m->end;
 
-		local_irq_disable();
-		p = &m->stat_percpu[smp_processor_id()][x];
-		dm_stat_round(s, p);
-		local_irq_enable();
-
-		memset(&s->tmp, 0, sizeof(s->tmp));
-		for_each_possible_cpu(cpu) {
-			p = &m->stat_percpu[cpu][x];
-			s->tmp.sectors[0] += p->sectors[0];
-			s->tmp.sectors[1] += p->sectors[1];
-			s->tmp.ios[0] += p->ios[0];
-			s->tmp.ios[1] += p->ios[1];
-			s->tmp.ticks[0] += p->ticks[0];
-			s->tmp.ticks[1] += p->ticks[1];
-			s->tmp.io_ticks += p->io_ticks;
-			s->tmp.time_in_queue += p->time_in_queue;
-		}
+		dm_stat_initialize_temporary_percpu_totals(s, m, x);
 
 		DMEMIT("%llu-%llu %lu %u %lu %lu %lu %u %lu %lu %d %lu %lu\n",
 			(unsigned long long)start,
@@ -448,7 +457,7 @@ static int dm_stats_print(struct dm_stats *st, int id, bool clear,
 	}
 
 	if (clear)
-		dm_stat_clear(m);
+		dm_stat_clear(m, false);
 
 buffer_overflow:
 	mutex_unlock(&st->mutex);
-- 
1.7.1