Locking propigation probelm samba to netatalk & netatalk to samba

Kevin M. Myer kevin_myer at iu13.k12.pa.us
Tue Mar 13 20:56:23 GMT 2001

On Tue, 13 Mar 2001, Daniel E. Lautenschleger wrote:

> This is the type of information many of us have been looking for with
> respect to Netatalk and Samba coexisting in a "friendly" matter. Many of
> the replies I received when originally asking whether the two behaved
> together basically stated that the biggest problem was a Windows user and
> a Netatalk user accessing the same file at the same time.
> Some of the other comments regarding Samba and Netatalk being used on the
> same share...

Sorry about all the CC's: on this message.

I posted on this subject awhile back, the subject was something like "The
facts about Samba and netatalk" - search the archives.

To summarize:

the --with-netatalk option in Samba does _NOTHING_, except enable a few
#ifdefs in the samba code, which do....nothing.  There was experimental
wrapper functions for .AppleDouble support written up in 1998 but the
hooks were never placed in the runtime code to actually use these
functions.  There's no code whatsoever written to deal with cooperative
locking and as far as I know, netatalk and samba use incompatible lock
types. Also, as far as I know, the only real degree of integration with
Samba is to specify, in the smb.conf file, to block the viewing of
netatalk metafiles (.AppleDouble, etc.) and to allow deletion of the
netatalk meta files when a directory is being deleted (otherwise the
delete will return a directory not empty errno).

I requested that the samba folks remove the --with-netatalk config option
and the unused libatalk.c code since its only causing confusion and
propagation of misinformation over mailing lists (I myself thought it was
actually doing things as well for awhile, until I ran some tests and
checked the source code).  I haven't checked the code lately to see if
this was actually accomplished.

There was no interest from the samba folks to impliment this, judging from
the zero replies I got regarding updating the netatalk support.  I floated
a question to see if anyone on the netatalk list was interested in it and
got a few responses from others who had posed the same question with
generally the same ideas but nothing ever materialized from their posts or
from mine.

So I think for the time being, unless someone changes the locking
mechanism used with netatalk, its safe to say that using netatalk and
samba together is a calculated risk, i.e. you run the risk that a Mac and
a Windows machine will have open the same file and can then easily corrupt
it at worse or whoever saves last will get their changes saved at best.

Incidentally, I also reported a problem with the --enable-flock-locks
configure option with the 1.5preX series.  Samba aside, just enabling that
broke netatalk's locking mechanism, at least under kernel 2.2.X on Linux.
I never got a confirmation that this was a widespread problem, although it
occured on three machines I tested here.  However, I noticed that its
commented out in the latest 1.5-pre5 RPM .spec file so

> ----
> I wonder if collaboration between Netatalk folks and Samba folks could
> occur?!
> God, it would be sweet to have both coexist, eh!

Yes, it would be.  Have samba be aware of netatalk meta-files and have
netatalk use samba's locking mechanism.  That would equal a fully
cooperative SMB and AppleShare file share volume on a robust operating
system, something that currently can't be said for NT and Services for

If anyone has an update on anything I've listed, I'd really like to hear
about it (i.e. if you are working on implimenting samba/netatalk
interoperability or if you have more info on locking problems).


Kevin M. Myer
Systems Administrator
Lancaster-Lebanon Intermediate Unit 13

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