From 008a6ba96f016fd0a3e8bb35cdce3d27e1c11363 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Mon, 5 Aug 2013 18:33:47 -0400
Subject: [PATCH 9/9] dm stats: move stats mutex locking out of dm_stats_find to caller

also rename functions that are called while mutex is locked or rcu
locked (to have leading double underscores)
---
 drivers/md/dm-stats.c |   63 +++++++++++++++++++++++++++++-------------------
 1 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 2025228..61f5739 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -325,12 +325,10 @@ free_ret:
 	return -ENOMEM;
 }
 
-static struct dm_stat *dm_stats_find(struct dm_stats *st, int id)
+static struct dm_stat *__dm_stats_find(struct dm_stats *st, int id)
 {
 	struct dm_stat *m;
 
-	mutex_lock(&st->mutex);
-
 	list_for_each_entry(m, &st->list, list_entry) {
 		if (m->id > id)
 			break;
@@ -338,8 +336,6 @@ static struct dm_stat *dm_stats_find(struct dm_stats *st, int id)
 			return m;
 	}
 
-	mutex_unlock(&st->mutex);
-
 	return NULL;
 }
 
@@ -348,9 +344,13 @@ static int dm_stats_delete(struct dm_stats *st, int id)
 	struct dm_stat *m;
 	int cpu;
 
-	m = dm_stats_find(st, id);
-	if (!m)
+	mutex_lock(&st->mutex);
+
+	m = __dm_stats_find(st, id);
+	if (!m) {
+		mutex_unlock(&st->mutex);
 		return -ENOENT;
+	}
 
 	list_del_rcu(&m->list_entry);
 	mutex_unlock(&st->mutex);
@@ -457,9 +457,10 @@ static void dm_stat_for_entry(struct dm_stat *m, size_t entry,
 	preempt_enable();
 }
 
-void dm_stat_bio(struct dm_stat *m, unsigned long bi_rw,
-		 sector_t bi_sector, sector_t end_sector,
-		 bool end, unsigned long duration, struct dm_stats_aux *aux)
+static void __dm_stat_bio(struct dm_stat *m, unsigned long bi_rw,
+			  sector_t bi_sector, sector_t end_sector,
+			  bool end, unsigned long duration,
+			  struct dm_stats_aux *aux)
 {
 	sector_t rel_sector, offset;
 	unsigned todo;
@@ -522,13 +523,13 @@ void dm_stats_bio(struct dm_stats *st,
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(m, &st->list, list_entry)
-		dm_stat_bio(m, bi_rw, bi_sector, end_sector, end, duration, aux);
+		__dm_stat_bio(m, bi_rw, bi_sector, end_sector, end, duration, aux);
 
 	rcu_read_unlock();
 }
 
-static void dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *s,
-						 struct dm_stat *m, size_t x)
+static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *s,
+						   struct dm_stat *m, size_t x)
 {
 	int cpu;
 	struct dm_stat_percpu *p;
@@ -556,8 +557,8 @@ static void dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *s,
 	}
 }
 
-static void dm_stat_clear(struct dm_stat *m, size_t idx_start, size_t idx_end,
-			  bool init_tmp_percpu_totals)
+static void __dm_stat_clear(struct dm_stat *m, size_t idx_start, size_t idx_end,
+			    bool init_tmp_percpu_totals)
 {
 	size_t x;
 	struct dm_stat_shared *s;
@@ -566,7 +567,7 @@ static void dm_stat_clear(struct dm_stat *m, size_t idx_start, size_t idx_end,
 	for (x = idx_start; x < idx_end; x++) {
 		s = &m->stat_shared[x];
 		if (init_tmp_percpu_totals)
-			dm_stat_init_temporary_percpu_totals(s, m ,x);
+			__dm_stat_init_temporary_percpu_totals(s, m ,x);
 		local_irq_disable();
 		p = &m->stat_percpu[smp_processor_id()][x];
 		p->sectors[0] -= s->tmp.sectors[0];
@@ -589,11 +590,15 @@ static int dm_stats_clear(struct dm_stats *st, int id)
 {
 	struct dm_stat *m;
 
-	m = dm_stats_find(st, id);
-	if (!m)
+	mutex_lock(&st->mutex);
+
+	m = __dm_stats_find(st, id);
+	if (!m) {
+		mutex_unlock(&st->mutex);
 		return -ENOENT;
+	}
 	
-	dm_stat_clear(m, 0, m->n_entries, true);
+	__dm_stat_clear(m, 0, m->n_entries, true);
 
 	mutex_unlock(&st->mutex);
 
@@ -631,9 +636,13 @@ static int dm_stats_print(struct dm_stats *st, int id,
 	size_t idx_end;
 	struct dm_stat_shared *s;
 
-	m = dm_stats_find(st, id);
-	if (!m)
+	mutex_lock(&st->mutex);
+
+	m = __dm_stats_find(st, id);
+	if (!m) {
+		mutex_unlock(&st->mutex);
 		return -ENOENT;
+	}
 
 	idx_end = idx_start + idx_len;
 	if (idx_end < idx_start ||
@@ -651,7 +660,7 @@ static int dm_stats_print(struct dm_stats *st, int id,
 		if (unlikely(end > m->end))
 			end = m->end;
 
-		dm_stat_init_temporary_percpu_totals(s, m, x);
+		__dm_stat_init_temporary_percpu_totals(s, m, x);
 
 		DMEMIT("%llu-%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu\n",
 			(unsigned long long)start,
@@ -675,7 +684,7 @@ static int dm_stats_print(struct dm_stats *st, int id,
 	}
 
 	if (clear)
-		dm_stat_clear(m, idx_start, idx_end, false);
+		__dm_stat_clear(m, idx_start, idx_end, false);
 
 buffer_overflow:
 	mutex_unlock(&st->mutex);
@@ -687,9 +696,13 @@ static int dm_stats_set_aux(struct dm_stats *st, int id, const char *aux)
 {
 	struct dm_stat *m;
 
-	m = dm_stats_find(st, id);
-	if (!m)
+	mutex_lock(&st->mutex);
+
+	m = __dm_stats_find(st, id);
+	if (!m) {
+		mutex_unlock(&st->mutex);
 		return -ENOENT;
+	}
 
 	aux = kstrdup(aux, GFP_KERNEL);
 	if (!aux) {
-- 
1.7.1