From 3528927ea6e60d358ea254870efb0eb138c3a74a Mon Sep 17 00:00:00 2001
From: Axel Burri <axel@tty0.ch>
Date: Tue, 2 Oct 2018 17:22:57 +0200
Subject: [PATCH] btrbk: bugfix: do not keep latest common snapshot for
 "incremental no"

There is no reason to keep the latest common source snapshot if
"incremental no" is configured (see #252).
---
 ChangeLog |  2 ++
 btrbk     | 22 ++++++++++++----------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3a21ac8..73fa708 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,6 +11,8 @@ btrbk-0.27.0-dev
   * Bugfix: add "btrfs filesystem usage" backend mapping (close #222).
   * Bugfix: do not fail (exitcode=10) if targets are not accessible on
     "btrfs snapshot --preserve".
+  * Bugfix: if "incremental no" is configured on target, do not keep
+    latest common snapshot.
   * Enhance internal data structures:
     - Allow snapshot_dir to be a mountpoint.
     - Search complete target tree for correlated subvolumes.
diff --git a/btrbk b/btrbk
index 9606dd0..557c9cf 100755
--- a/btrbk
+++ b/btrbk
@@ -5990,17 +5990,19 @@ MAIN:
               next;
             }
 
-            # always preserve latest common snapshot/backup pair
-            foreach my $child (@snapshot_children) {
-              my @receive_targets = get_receive_targets($droot, $child, exact => 1);
-              if(scalar(@receive_targets)) {
-                DEBUG "Force preserve for latest common snapshot: $child->{PRINT}";
-                $child->{node}{FORCE_PRESERVE} = 'preserve forced: latest common snapshot';
-                foreach(@receive_targets) {
-                  DEBUG "Force preserve for latest common target: $_->{PRINT}";
-                  $_->{node}{FORCE_PRESERVE} = 'preserve forced: latest common target';
+            # preserve latest common snapshot/backup (for incremental targets)
+            if(config_key($droot, "incremental")) {
+              foreach my $child (@snapshot_children) {
+                my @receive_targets = get_receive_targets($droot, $child, exact => 1);
+                if(scalar(@receive_targets)) {
+                  DEBUG "Force preserve for latest common snapshot: $child->{PRINT}";
+                  $child->{node}{FORCE_PRESERVE} = 'preserve forced: latest common snapshot';
+                  foreach(@receive_targets) {
+                    DEBUG "Force preserve for latest common target: $_->{PRINT}";
+                    $_->{node}{FORCE_PRESERVE} = 'preserve forced: latest common target';
+                  }
+                  last;
                 }
-                last;
               }
             }