From 2fa7b537498a855953acc5765261914cf834c3ea Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Mon, 5 Aug 2013 12:26:57 -0400
Subject: [PATCH 5/8] dm cache: add @stats_clear message

factored out reuseable code to share between print and clear
---
 drivers/md/dm-stats.c |   72 ++++++++++++++++++++++++++++++++++++------------
 1 files changed, 54 insertions(+), 18 deletions(-)

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 084fee3..3079555 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -343,6 +343,41 @@ void dm_stats_bio(struct dm_stats *st,
 	rcu_read_unlock();
 }
 
+static void dm_stat_clear(struct dm_stat *stat)
+{
+	size_t x;
+	struct dm_stat_shared *s;
+	struct dm_stat_percpu *p;
+
+	for (x = 0; x < stat->n_entries; x++) {
+		s = &stat->stat_shared[x];
+		local_irq_disable();
+		p = &stat->stat_percpu[smp_processor_id()][x];
+		p->sectors[0] -= s->tmp.sectors[0];
+		p->sectors[1] -= s->tmp.sectors[1];
+		p->ios[0] -= s->tmp.ios[0];
+		p->ios[1] -= s->tmp.ios[1];
+		p->ticks[0] -= s->tmp.ticks[0];
+		p->ticks[1] -= s->tmp.ticks[1];
+		p->io_ticks -= s->tmp.io_ticks;
+		p->time_in_queue -= s->tmp.time_in_queue;
+		local_irq_enable();
+	}
+}
+
+static int dm_stats_clear(struct dm_stats *stats, int id)
+{
+	struct dm_stat *stat;
+
+	stat = dm_stats_find(stats, id);
+	if (!stat)
+		return -ENOENT;
+
+	dm_stat_clear(stat);
+
+	return 1;
+}
+
 static int dm_stats_print(struct dm_stats *st, int id, bool clear,
 			  char *result, unsigned maxlen)
 {
@@ -403,23 +438,8 @@ static int dm_stats_print(struct dm_stats *st, int id, bool clear,
 			goto buffer_overflow;
 	}
 
-	if (clear) {
-		for (x = 0; x < m->n_entries; x++) {
-			struct dm_stat_shared *s = &m->stat_shared[x];
-			struct dm_stat_percpu *p;
-			local_irq_disable();
-			p = &m->stat_percpu[smp_processor_id()][x];
-			p->sectors[0] -= s->tmp.sectors[0];
-			p->sectors[1] -= s->tmp.sectors[1];
-			p->ios[0] -= s->tmp.ios[0];
-			p->ios[1] -= s->tmp.ios[1];
-			p->ticks[0] -= s->tmp.ticks[0];
-			p->ticks[1] -= s->tmp.ticks[1];
-			p->io_ticks -= s->tmp.io_ticks;
-			p->time_in_queue -= s->tmp.time_in_queue;
-			local_irq_enable();
-		}
-	}
+	if (clear)
+		dm_stat_clear(m);
 
 buffer_overflow:
 	mutex_unlock(&st->mutex);
@@ -495,6 +515,21 @@ static int message_stats_delete(struct mapped_device *md,
 	return dm_stats_delete(dm_get_stats(md), id);
 }
 
+static int message_stats_clear(struct mapped_device *md,
+			       unsigned argc, char **argv)
+{
+	int id;
+	char dummy;
+
+	if (argc != 2)
+		return -EINVAL;
+
+	if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
+		return -EINVAL;
+
+	return dm_stats_clear(dm_get_stats(md), id);
+}
+
 static int message_stats_print(struct mapped_device *md,
 			       unsigned argc, char **argv, bool clear,
 			       char *result, unsigned maxlen)
@@ -525,9 +560,10 @@ int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
 		r = message_stats_create(md, argc, argv, result, maxlen);
 	else if (!strcasecmp(argv[0], "@stats_delete"))
 		r = message_stats_delete(md, argc, argv);
+	else if (!strcasecmp(argv[0], "@stats_clear"))
+		r = message_stats_clear(md, argc, argv);
 	else if (!strcasecmp(argv[0], "@stats_print"))
 		r = message_stats_print(md, argc, argv, false, result, maxlen);
-	/* FIXME: why not have @stats_print + @stats_clear ? */
 	else if (!strcasecmp(argv[0], "@stats_print_clear"))
 		r = message_stats_print(md, argc, argv, true, result, maxlen);
 	else
-- 
1.7.1