If you shut down and restart the samba servers, three log files will be
created in /var/log/samba: log.smb, smb.log, and log.nmb.

The first one is created because smbd logs to log.smb before reading the
smb.conf file and realizing that it's actually supposed to be logging to
"%m.log".

The second one is a correctly named log file created because of the "log
file = /var/log/samba/%m.log" entry in smb.conf.

The third one is the default log file name for nmbd, and it is problematic
because the pattern in /etc/logrotate.d/samba won't match it so it will
never be rotated.

I assume that the switch from log.smb to smb.log was made because logrotate
goes haywire because of the "/var/log/samba/log.*" pattern matching, trying
to rotate all of the previously rotated log files.  The correct fix for
that problem is probably to fix logrotate, not to screw up samba's log
files and leave things messed up as they are now.

The minimal fix to this problem is to change /etc/logrotate.d/samba so that
it reads "/var/log/samba/*.log /var/log/samba/log.smb
/var/log/samba/log.nmb" instead of just "/var/log/samba/*.log".

Yuck.