btrfs-progs: tests, verify that btrfs-image works on a missing device

Create a 2 device raid1 filesystem, fill with some data, delete one
device (the device node must not exist) and try to dump a filesystem
image.

Signed-off-by: David Sterba <dsterba@suse.com>

tests/misc-tests/006-image-on-missing-device/test.sh

@@ -0,0 +1,78 @@
+#!/bin/bash
+# test btrfs-image with a missing device (uses loop devices)
+#
+# - btrfs-image must not loop indefinetelly
+# - btrfs-image will expectedly fail to produce the dump
+
+source $TOP/tests/common
+
+check_prereq btrfs-show-super
+check_prereq btrfs-image
+check_prereq mkfs.btrfs
+check_prereq btrfs
+
+ndevs=2
+declare -a devs
+dev1=
+dev2=
+
+setup_root_helper
+
+
+# TODO: move the helpers to common
+
+prepare_devices()
+{
+	for i in `seq $ndevs`; do
+		touch img$i
+		chmod a+rw img$i
+		truncate -s0 img$i
+		truncate -s2g img$i
+		devs[$i]=`run_check_stdout $SUDO_HELPER losetup --find --show img$i`
+	done
+}
+
+cleanup_devices()
+{
+	for dev in ${devs[@]}; do
+		run_mayfail $SUDO_HELPER losetup -d $dev
+	done
+	for i in `seq $ndevs`; do
+		truncate -s0 img$i
+	done
+	run_check $SUDO_HELPER losetup --list
+}
+
+test_image_dump()
+{
+	run_check $SUDO_HELPER $TOP/btrfs check $dev1
+	# the output file will be deleted
+	run_mayfail $SUDO_HELPER $TOP/btrfs-image $dev1 /tmp/test-img.dump
+}
+
+test_run()
+{
+	run_check $SUDO_HELPER $TOP/mkfs.btrfs -f -d raid1 -m raid1 $dev1 $dev2
+
+	# we need extents to trigger reading from all devices
+	run_check $SUDO_HELPER mount $dev1 $TEST_MNT
+	run_check $SUDO_HELPER dd if=/dev/zero of=$TEST_MNT/a bs=1M count=10
+	run_check $SUDO_HELPER dd if=/dev/zero of=$TEST_MNT/b bs=4k count=1000 conv=sync
+	run_check $SUDO_HELPER umount $TEST_MNT
+
+	test_image_dump
+	run_check btrfs fi show $dev1
+	# create a degraded raid1 filesystem, check must succeed
+	# btrfs-image must not loop
+	run_mayfail wipefs -a $dev2
+	run_check $SUDO_HELPER losetup -d $dev2
+	run_check btrfs fi show $dev1
+
+	test_image_dump
+}
+
+prepare_devices
+dev1=${devs[1]}
+dev2=${devs[2]}
+test_run
+cleanup_devices