[lvm-devel] [PATCH v1 02/17] tests: Support multiple backing devices

[Leo Yan]

In current implementation, the option "LVM_TEST_BACKING_DEVICE" only
supports to specify one backing device; this patch is to extend the
option to support multiple backing devices by using comma as separator,
e.g. below command specifies two backing devices:

  make check_lvmlockd_idm LVM_TEST_BACKING_DEVICE=/dev/sdj3,/dev/sdk3

This can allow the testing works on multiple drives and verify the
locking scheme if can work as expected for multiple drives case.  For
example, for Seagate IDM locking scheme, if a VG uses two PVs, every PV
is resident on a drive, thus the locking operations will be sent to two
drives respectively; so the extension for "LVM_TEST_BACKING_DEVICE" can
help to verify different drive configurations for locking.

Signed-off-by: Leo Yan <leo.yan at linaro.org>
---
 test/lib/aux.sh | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/test/lib/aux.sh b/test/lib/aux.sh
index 97c7ac68b..a592dad81 100644
--- a/test/lib/aux.sh
+++ b/test/lib/aux.sh
@@ -901,11 +901,22 @@ prepare_backing_dev() {
 	local size=${1=32}
 	shift
 
+	if test -n "$LVM_TEST_BACKING_DEVICE"; then
+		IFS=',' read -r -a BACKING_DEVICE_ARRAY <<< "$LVM_TEST_BACKING_DEVICE"
+
+		for d in "${BACKING_DEVICE_ARRAY[@]}"; do
+			if test ! -b "$d"; then
+				echo "Device $d doesn't exist!"
+				return 1
+			fi
+		done
+	fi
+
 	if test -f BACKING_DEV; then
 		BACKING_DEV=$(< BACKING_DEV)
 		return 0
-	elif test -b "$LVM_TEST_BACKING_DEVICE"; then
-		BACKING_DEV=$LVM_TEST_BACKING_DEVICE
+	elif test -n "$LVM_TEST_BACKING_DEVICE"; then
+		BACKING_DEV=${BACKING_DEVICE_ARRAY[0]}
 		echo "$BACKING_DEV" > BACKING_DEV
 		return 0
 	elif test "${LVM_TEST_PREFER_BRD-1}" = "1" && \
@@ -953,7 +964,14 @@ prepare_devs() {
 		local dev="$DM_DEV_DIR/mapper/$name"
 		DEVICES[$count]=$dev
 		count=$((  count + 1 ))
-		echo 0 $size linear "$BACKING_DEV" $(( ( i - 1 ) * size + ( header_shift * 2048 ) )) > "$name.table"
+		# If the backing device number can meet the requirement for PV devices,
+		# then allocate a dedicated backing device for PV; otherwise, rollback
+		# to use single backing device for device-mapper.
+		if [ -n "$LVM_TEST_BACKING_DEVICE" ] && [ $n -le ${#BACKING_DEVICE_ARRAY[@]} ]; then
+			echo 0 $size linear "${BACKING_DEVICE_ARRAY[$(( count - 1 ))]}" $(( header_shift * 2048 )) > "$name.table"
+		else
+			echo 0 $size linear "$BACKING_DEV" $(( ( i - 1 ) * size + ( header_shift * 2048 ) )) > "$name.table"
+		fi
 		dmsetup create -u "TEST-$name" "$name" "$name.table" || touch CREATE_FAILED &
 		test -f CREATE_FAILED && break;
 	done
@@ -971,6 +989,13 @@ prepare_devs() {
 		return $?
 	fi
 
+	for d in "${BACKING_DEVICE_ARRAY[@]}"; do
+		cnt=$((`blockdev --getsize64 $d` / 1024 / 1024))
+		cnt=$(( cnt < 1000 ? cnt : 1000 ))
+		dd if=/dev/zero of="$d" bs=1MB count=$cnt
+		wipefs -a "$d" 2>/dev/null || true
+	done
+
 	# non-ephemeral devices need to be cleared between tests
 	test -f LOOP -o -f RAMDISK || for d in "${DEVICES[@]}"; do
 		# ensure disk header is always zeroed
-- 
2.25.1