From de5004c74485a05b75ddf1409a32fb0969ba68d4 Mon Sep 17 00:00:00 2001
From: Axel Burri <axel@tty0.ch>
Date: Fri, 29 Jun 2018 12:49:04 +0200
Subject: [PATCH] btrbk: abort subvolume if it is btrfs root (id=5)

Btrfs root subvolume (id=5) have no UUID and cannot be backed
up. Abort if "subvolume ." is configured on btrfs root, e.g.:

  volume /path/to/btrfs_root
    subvolume .
---
 btrbk | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/btrbk b/btrbk
index 92125de..5bdd36c 100755
--- a/btrbk
+++ b/btrbk
@@ -5309,6 +5309,11 @@ MAIN:
         WARN "Skipping subvolume \"$svol->{PRINT}\": $abrt";
         next;
       }
+      if((not $svol->{node}{uuid}) || ($svol->{node}{uuid} eq '-')) {
+        ABORTED($svol, "subvolume has no UUID");
+        ERROR "Skipping subvolume \"$svol->{PRINT}\": $abrt";
+        next;
+      }
       if($svol->{node}{readonly}) {
         ABORTED($svol, "subvolume is readonly");
         WARN "Skipping subvolume \"$svol->{PRINT}\": $abrt";
@@ -5319,9 +5324,8 @@ MAIN:
         WARN "Skipping subvolume \"$svol->{PRINT}\": $abrt";
         next;
       }
-      if($svol->{node}{uuid} &&
-          (_is_child_of($sroot->{node}, $svol->{node}{uuid}) ||
-           ($svol->{node}{uuid} eq $sroot->{node}{uuid})))
+      if(_is_child_of($sroot->{node}, $svol->{node}{uuid}) ||
+         ($svol->{node}{uuid} eq $sroot->{node}{uuid}))
       {
         DEBUG "Found \"$svol->{PRINT}\" (id=$svol->{node}{id}) in btrfs tree of: $sroot->{PRINT}";
       } else {