[PATCH v2] btrfs-progs: misc-tests: replace deprecated standalone "usebackuproot" option

That option is already marked deprecated a long time ago, and is going to
be completely removed in v7.3.

Update the test case to auto-detect if the running kernel has support
for "rescue=usebackuproot", and if not skip the test case.

Furthermore, since v7.3 all "rescue=" mount options, including
"rescue=usebackuproot" will require full RO mount, also add "ro" mount
option to the test run.

Signed-off-by: Qu Wenruo <[email protected]>
---
Changelog:
v2:
- Add "ro" mount option for v7.3
---
 .../misc-tests/038-backup-root-corruption/test.sh  | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/tests/misc-tests/038-backup-root-corruption/test.sh b/tests/misc-tests/038-backup-root-corruption/test.sh
index d4396a7fe21e..02f5962da450 100755
--- a/tests/misc-tests/038-backup-root-corruption/test.sh
+++ b/tests/misc-tests/038-backup-root-corruption/test.sh
@@ -10,6 +10,18 @@ check_prereq btrfs-corrupt-block
 setup_root_helper
 prepare_test_dev

+supported_opts="/sys/fs/btrfs/features/supported_rescue_options"
+# Make sure the current kernel has "rescue=usebackuproot" support.
+# Since v7.3 the standalone "usebackuproot" mount option is completely
+# removed.
+if [ ! -f "$supported_opts" ]; then
+	_not_run "No sysfs file for supported_rescue_options"
+fi
+
+if ! grep -q usebackuproot "$supported_opts"; then
+	_not_run "No \"rescue=usebackuproot\" support"
+fi
+
 # Create a file and unmount to commit some backup roots
 run_check_mkfs_test_dev
 run_check_mount_test_dev
@@ -55,7 +67,7 @@ run_mustfail "Unexpected successful mount" \
 	$SUDO_HELPER mount "$TEST_DEV" "$TEST_MNT"

 # Cycle mount with the backup to force rewrite of slot 3
-run_check_mount_test_dev -o usebackuproot
+run_check_mount_test_dev -o rescue=usebackuproot,ro
 run_check_umount_test_dev

 main_root_ptr=$(dump_super | awk '/^root\t/{print $2}')
--
2.54.0