[Samba] samba-tool domain backup offline stalls

[Andrew Bartlett]

On Wed, 2020-07-22 at 12:35 -0400, James B. Byrne via samba wrote:
> FreeBSD-12.1p7 jail running Samba-4.10.15 on ZFS.
> 
> When I run 'samba-tool domain backup offline targetdir=/tmp' I see
> this:
> 
> running backup on dirs: /var/db/samba4/private /var/db/samba4
> /usr/local/etc
> Starting transaction on /var/db/samba4/private/secrets
> 
> At which point samba-tool enters a permanent wait state.
> 
> 86064 root          1  52    0   131M    78M
> wait     3   0:01   0.00% python3.7
> 
> Trace shows this:
> 
> . . .
>  --- modulename: subprocess, funcname: __enter__
> subprocess.py(845):         return self
> subprocess.py(340):         try:
> subprocess.py(341):             return p.wait(timeout=timeout)
>  --- modulename: subprocess, funcname: wait
> subprocess.py(1016):         if timeout is not None:
> subprocess.py(1018):         try:
> subprocess.py(1019):             return self._wait(timeout=timeout)
>  --- modulename: subprocess, funcname: _wait
> subprocess.py(1623):             if self.returncode is not None:
> subprocess.py(1626):             if timeout is not None:
> subprocess.py(1649):                 while self.returncode is None:
> subprocess.py(1650):                     with self._waitpid_lock:
> subprocess.py(1651):                         if self.returncode is
> not None:
> subprocess.py(1653):                         (pid, sts) =
> self._try_wait(0)
>  --- modulename: subprocess, funcname: _try_wait
> subprocess.py(1610):             try:
> subprocess.py(1611):                 (pid, sts) =
> os.waitpid(self.pid, wait_flags)
> 
> And that is where it stops.  Is this caused by a configuration
> issue?  Is so
> then what?

Are you using DLZ_BIND9?  There is a bug where it doesn't know the
locking rules for those files.

Otherwise, work out which commend it is waiting on (the child) and what
lock that is waiting on (lslocks on linux is what I used to debug this
stuff).

Andrew Bartlett

-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT - Expert Open Source
Solutions
https://catalyst.net.nz/services/samba