Merge branch 'unsafe_delete_on_receive_errors'

ChangeLog

@@ -1,5 +1,8 @@
 btrbk-current
 
+  * Bugfix: send/receive: delete possibly left-behind garbled
+    subvolume on failure. Fail with unrecoverable error if stray
+    target subvolume is in the way (closes: #17).
   * Bugfix: assume unreachable target as clean on snapshot creation if
     snapshot_create_always is set (closes: #19).
 

btrbk

@@ -971,8 +971,19 @@ sub macro_send_receive($@)
 
   INFO "Receiving from snapshot: $snapshot->{PRINT}";
 
+  # check for existing target subvolume
+  if(my $err_vol = vinfo_subvol($target, $snapshot->{NAME})) {
+    $config_target->{ABORTED} = "Target subvolume \"$err_vol->{PRINT}\" already exists";
+    $config_target->{UNRECOVERABLE} = "Please delete stray subvolume: $err_vol->{PRINT}";
+    ERROR $config_target->{ABORTED} . ", aborting send/receive of: $snapshot->{PRINT}";
+    ERROR $config_target->{UNRECOVERABLE};
+    $info{ERROR} = 1;
+    return undef;
+  }
+
   # add info to $config->{SUBVOL_RECEIVED}
-  $info{received_name} = "$target->{PRINT}/$snapshot->{NAME}";
+  my $vol_received = vinfo_child($target, $snapshot->{NAME});
+  $info{received_subvolume} = $vol_received;
   $config_target->{SUBVOL_RECEIVED} //= [];
   push(@{$config_target->{SUBVOL_RECEIVED}}, \%info);
 
@@ -1002,6 +1013,19 @@ sub macro_send_receive($@)
   } else {
     $info{ERROR} = 1;
     $config_target->{ABORTED} = "Failed to send/receive subvolume";
+
+    # NOTE: btrfs-progs v3.19.1 does not delete garbled received subvolume,
+    #       we need to do this by hand.
+    # TODO: remove this as soon as btrfs-progs handle receive errors correctly.
+    DEBUG "send/received failed, deleting (possibly present and garbled) received subvolume: $vol_received->{PRINT}";
+    my $ret = btrfs_subvolume_delete($vol_received, commit => "after");
+    if(defined($ret)) {
+      WARN "Deleted partially received (garbled) subvolume: $vol_received->{PRINT}";
+    }
+    else {
+      WARN "Deletion of partially received (garbled) subvolume failed, assuming clean environment: $vol_received->{PRINT}";
+    }
+
     return undef;
   }
 }
@@ -1783,8 +1807,7 @@ MAIN:
               my @schedule;
               my $found_missing = 0;
 
-              # sort children of svol ascending by generation
+              foreach my $child (sort { $a->{gen} <=> $b->{gen} } get_snapshot_children($sroot, $svol))
-              foreach my $child (get_snapshot_children($sroot, $svol))
               {
                 if(scalar get_receive_targets($droot, $child)) {
                   DEBUG "Found matching receive target, skipping: $child->{PRINT}";
@@ -1792,6 +1815,10 @@ MAIN:
                 else {
                   DEBUG "No matching receive targets found, adding resume candidate: $child->{PRINT}";
 
+                  if(my $err_vol = vinfo_subvol($droot, $child->{NAME})) {
+                    WARN "Target subvolume \"$err_vol->{PRINT}\" exists, but is not a receive target of \"$child->{PRINT}\"";
+                  }
+
                   # check if the target would be preserved
                   my ($date, $date_ext) = get_date_tag($child->{SUBVOL_PATH});
                   next unless($date && ($child->{SUBVOL_PATH} =~ /^\Q$snapdir\/$snapshot_basename\E$snapshot_postfix_match$/));
@@ -1979,6 +2006,7 @@ MAIN:
     unless($quiet)
     {
       my @out;
+      my @unrecoverable;
       my $err_count = 0;
       foreach my $config_vol (@{$config->{VOLUME}})
       {
@@ -2007,7 +2035,7 @@ MAIN:
               $create_mode = ">>>" if($_->{parent});
               # substr($create_mode, 0, 1, '%') if($_->{resume});
               $create_mode = "!!!" if($_->{ERROR});
-              push @out, "$create_mode $_->{received_name}";
+              push @out, "$create_mode $_->{received_subvolume}->{PRINT}";
             }
 
             if($config_target->{SUBVOL_DELETED}) {
@@ -2018,6 +2046,8 @@ MAIN:
               push @out, "!!! Target \"$droot->{PRINT}\" aborted: $config_target->{ABORTED}";
               $err_count++ unless($config_target->{ABORTED_NOERR});
             }
+
+            push(@unrecoverable, $config_target->{UNRECOVERABLE}) if($config_target->{UNRECOVERABLE});
           }
           push @out, "";
         }
@@ -2037,12 +2067,13 @@ MAIN:
 
       print join("\n", @out);
 
+      if($preserve_backups) {
+        print "\nNOTE: Preserved all backups (option -p present)\n";
+      }
       if($err_count) {
         print "\nNOTE: Some errors occurred, which may result in missing backups!\n";
         print "Please check warning and error messages above.\n";
-      }
+        print join("\n", @unrecoverable) . "\n" if(@unrecoverable);
-      if($preserve_backups) {
-        print "\nNOTE: Preserved all backups (option -p present)\n";
       }
       if($dryrun) {
         print "\nNOTE: Dryrun was active, none of the operations above were actually executed!\n";