data dir: allow sameness of old and new dir

this makes it easy to migrate to a new volume setup

src/scripts/checkvolume.sh

@@ -17,14 +17,24 @@ if [[ "$1" == "--check" ]]; then
     exit 0
 fi
 
-volume_dir="$1"
+target_dir="$1"
+source_dir="$2"
 
-readonly test_file="${volume_dir}/.chown-test"
+source_stat=$(stat --format='%d,%i' "${source_dir}")
+target_stat=$(stat --format='%d,%i' "${target_dir}")
 
-mkdir -p "${volume_dir}"
+# test sameness across bind mounts. if it's same, we can skip the emptiness check
+if [[ "${source_stat}" == "${target_stat}" ]]; then
+    echo "Source dir and target dir are the same"
+    exit 0
+fi
+
+readonly test_file="${target_dir}/.chown-test"
+
+mkdir -p "${target_dir}"
 rm -f "${test_file}" # clean up any from previous run
 
-if [[ -n $(ls -A "${volume_dir}") ]]; then
+if [[ -n $(ls -A "${target_dir}") ]]; then
     echo "volume dir is not empty"
     exit 2
 fi
@@ -35,5 +45,5 @@ if ! chown yellowtent:yellowtent "${test_file}"; then
     exit 3
 fi
 rm -f "${test_file}"
-rm -r "${volume_dir}" # will get recreated by the local storage addon
+rm -r "${target_dir}" # will get recreated by the local storage addon
 

src/scripts/mvvolume.sh

@@ -26,6 +26,15 @@ if [[ "${BOX_ENV}" == "test" ]]; then
     [[ "${target_dir}" != *"/.cloudron_test/"* ]] && exit 1
 fi
 
+source_stat=$(stat --format='%d,%i' "${source_dir}")
+target_stat=$(stat --format='%d,%i' "${target_dir}")
+
+# test sameness across bind mounts
+if [[ "${source_stat}" == "${target_stat}" ]]; then
+    echo "Source dir and target dir are the same"
+    exit 0
+fi
+
 # copy and remove - this way if the copy fails, the original is intact
 # the find logic is so that move to a one level subdir works (and we also move hidden files)
 find "${source_dir}" -maxdepth 1 -mindepth 1 -not -wholename "${target_dir}" -exec cp -ar '{}' "${target_dir}" \;