cleanups for tar and /data/media support

Change-Id: I4afe3a8d4484f91b1e689d7b3aa4f137acd66e93
diff --git a/roots.c b/roots.c
index fa7a5df..6d76aa8 100644
--- a/roots.c
+++ b/roots.c
@@ -286,6 +286,10 @@
 int format_volume(const char* volume) {
     Volume* v = volume_for_path(volume);
     if (v == NULL) {
+        // no /sdcard? let's assume /data/media
+        if (strstr(path, "/sdcard") == path && is_data_media()) {
+            return format_unknown_device(volume);
+        }
         // silent failure for sd-ext
         if (strcmp(volume, "/sd-ext") == 0)
             return -1;