From c98868181fa3ee0816d525ef186c1059a46f1d0b Mon Sep 17 00:00:00 2001
From: "Bryn M. Reeves" <bmr@redhat.com>
Date: Thu, 9 Mar 2017 17:33:02 +0000
Subject: [PATCH] libdm: remove unnecessary backtrace in
 _stats_group_id_present()

It's not an error to call dm_stats_group_present() on a handle
that contains no regions.

This causes dmfilemap to log a false backtrace during shutdown
if all regions are removed from the corresponding device:

  exiting _filemap_monitor_get_events() with deleted=0, check=0
  waiting for FILEMAPD_WAIT
  dm message   (253:1) [ opencount flush ]  @stats_list dmstats [32768] (*1)
  <backtrace>
  Filemap group removed: exiting.

Change this to only emit a backtrace if the handle is NULL.
---
 libdm/libdm-stats.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libdm/libdm-stats.c b/libdm/libdm-stats.c
index 3f6730eac..f0a7dbfef 100644
--- a/libdm/libdm-stats.c
+++ b/libdm/libdm-stats.c
@@ -264,9 +264,12 @@ static int _stats_group_id_present(const struct dm_stats *dms, uint64_t id)
 	if (id == DM_STATS_GROUP_NOT_PRESENT)
 		return 0;
 
-	if (!dms || !dms->regions)
+	if (!dms)
 		return_0;
 
+	if (!dms->regions)
+		return 0;
+
 	if (id > dms->max_region)
 		return 0;