tests: check we detect lvm.conf read failure

No coredumps with unreadable lvm.conf.

test/shell/lvm-conf-error.sh

@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+
+# Copyright (C) 2020 Red Hat, Inc. All rights reserved.
+#
+# This copyrighted material is made available to anyone wishing to use,
+# modify, copy, or redistribute it subject to the terms and conditions
+# of the GNU General Public License v.2.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+# Check what happens when reading of lvm.conf fails
+
+. lib/inittest
+
+MKFS=mkfs.ext3
+which $MKFS || skip
+which filefrag || skip
+
+aux prepare_vg 1
+
+mkdir mnt
+
+lvcreate -L5M -n $lv1 $vg
+
+$MKFS "$DM_DEV_DIR/$vg/$lv1"
+mount "$DM_DEV_DIR/$vg/$lv1" mnt
+cp etc/lvm.conf mnt
+
+# Figure where the file is placed in filesystem
+filefrag -e mnt/lvm.conf | tee frags
+umount mnt
+
+# 1st. sector for filesystem
+first_extent_sector=$(get first_extent_sector "$dev1")
+
+# find 1st. 1k block of file and trim '..' from printed number
+file_block=$(awk '/0:/ { gsub(/\.\.$/, "", $4); print $4}'  frags)
+
+# figure sector position on DM device
+file_sector=$(( file_block * 2 + first_extent_sector ))
+
+aux error_dev "$dev1" $file_sector:2
+
+mount "$DM_DEV_DIR/$vg/$lv1" mnt
+
+# force lvm to read lvm.conf from mnt path
+LVM_SYSTEM_DIR=mnt lvs 2>&1 | tee out || true
+
+# shell give nice error message
+grep "Failed to load config file mnt/lvm.conf" out
+
+aux enable_dev "$dev1"
+
+umount mnt
+
+vgremove -ff $vg