[Samba] Can Samba lock files until copy is complete?

Whit Blauvelt whit+samba at transpect.com
Sat Aug 21 07:13:41 MDT 2010

Thanks much for the suggestions. This may be a dead end then, but trying to
get just a bit clearer on the implications....

On Fri, Aug 20, 2010 at 04:46:20PM -0700, Jeremy Allison wrote:

> Outside of Samba, there's no way to know when Samba is finished
> with a file. You could write a Windows app to do the copies, which
> does a share mode DENY_ALL over the file, but there's no guarantee
> that local POSIX apps on the Linux side will see it.

So inside Samba there's a way to know? Would it be possible, with the right
hooks into Samba, to query: "I see a file. Are you done with it?"

> One way of testing that Samba is finished with writing a file
> from a POSIX shell script is to write a custom program using
> the libsmbclient library to open the required file, and set
> the share mode using smbc_setOptionOpenShareMode() to be
> DENY_ALL. Such a program will only allow an open to succeed
> if there are no other openers in Samba.

Do I take it that this would only apply if the "open" were made through
Samba? I ask since the file is being placed there through Samba, but taken
for other uses by local *nix methods.

> Otherwise you can write a VFS module in Samba that notifies
> an external program when a file in a particular share is
> closed, with no other openers. That might fit your specific
> case best.

Probably true, aside from the "you can write" part - that's beyond my C
skills. At


there's mention of a "audit" and "extd_audit" modules that can log among
other things "file close." If we can have a log of when files are closed, we
can have our Linux-side scripting only grab those files which are logged as
closed. For that matter, we can have a primary and secondary directory, with
logic like "if file in primary directory, if logged as closed, move to
secondary directory; if file in secondary directory, process."

There'd need to be some comparison of file time and log time, so that if a
file by the same name comes in twice the check to the log doesn't
misidentify it as closed, but on first glance this looks workable. Thanks.


More information about the samba mailing list