samba-tool domain backup with lmdb on btrfs fails

[Andreas Schneider]

On Tuesday, 14 February 2023 16:39:59 CET Andreas Schneider via samba-
technical wrote:
> Hi,
> 
> I've discovered on my Fedora 37 system that all tests related to domain
> backup fail. The strange thing is that I can't reliably reproduce it, I see
> reliably two different errors:
> 
> lib/ldb/ldb_key_value/ldb_kv_search.c:162: Invalid data for index
> DN=@INDEXLIST
> 
> or
> 
> lib/ldb/ldb_mdb/ldb_mdb.c:419: MDB corrupted for key [ DN=@OPTIONS]
> 
> ldb: Improve debug outout
> https://gitlab.com/samba-team/samba/-/merge_requests/2936
> 
> It the tests worked just fine on my other system with openSUSE Tumbleweed.
> So I've tried to track it down. My home directory on openSUSE Tumbleweed is
> ext4 and on Fedora 37 my home is btrfs.
> 
> So I created a btrfs filesystem on Tumbleweed and could reproduce the issue.
> The next thing I did is replace the compression algorithm for the domain
> backup tarball to gzip and it also failed.
> 
> Now the question is if lmdb or btrfs needs a fix and how to create a minimal
> reproducer. As I never worked on this codepath, pointers and ideas would be
> really helpful!

I've did a quick hack and created the backup tarball (offlinebackupdc env) on 
ext4 and restored it on btrfs.

@@ -3426,11 +3426,12 @@ sub setup_offlinebackupdc
                                                    $dnsupdate_options);
 
        # create an offline backup of the 'backupfromdc' target
-       my $backupdir = File::Temp->newdir();
-       my $cmd = "offline --configfile $dcvars->{SERVERCONFFILE}";
-       my $backup_file = $self->create_backup($env, $dcvars,
-                                              $backupdir, $cmd);
+       my $backupdir = '/tmp/samba';
+       #my $cmd = "offline --configfile $dcvars->{SERVERCONFFILE}";
+       # my $backup_file = $self->create_backup($env, $dcvars,
+       #                                      $backupdir, $cmd);
 
+       my $backup_file = '/tmp/samba/samba-
backup-2023-02-14T16-14-17.289039.tar.bz2';
        unless($backup_file) {
                return undef;
        }

Backup file successfully restored to /var/tmp/samba-test/samba/st/
offlinebackupdc

So the corruption could also happen when creating the tarball. I will try to 
checksum the file before backup put it into a file and store it into the 
tarball, then I can unpack it and check the sums.


-- 
Andreas Schneider                      asn at samba.org
Samba Team                             www.samba.org
GPG-ID:     8DFF53E18F2ABC8D8F3C92237EE0FC4DCC014E3D