[Samba] Problem with Samba re-share of a CIFS mount

[Jeremy Allison]

On Tue, Feb 11, 2014 at 03:12:54PM +0100, Gionatan Danti wrote:
> Premise: I posted the same question to the linux-cifs mailing list.
> I absolutely don't want to cross-posting, but I am not sure if the
> problem is related to the cifs client or to the Samba server. If you
> think that this post is an unnecessary duplicate, feel free to
> delete it.
> 
> Hi all,
> I have a strange problem trying to re-share, via Samba, a CIFS mount.
> 
> Let first explain my network topology:
> 
> Win2008R2 w/SMB share -> low speed link -> Linux Box -> WIN7 clients
> 
> In short, a Win2008 R2 share is being accessed by some W7 clients
> over a slow (~8 Mb/s downstream, ~1 Mb/s upstream) ADSL link. To
> speed up read operation on the branch office, I thought to use a
> Linux Box with cachefilesd and a CONFIG_CIFS_FSCACHE enabled kernel.
> The Linux box will mount the Win2008R2 share and, thanks to
> cachefilesd, it will maintain an "hot cache" of the read data. This
> CIFS mount is then shared, via Samba, to the other client Win7 PCs.
> 
> However, the problem is that when re-sharing the CIFS mount, the
> Win7 clients often see the many directories inside the mount as a
> regular files, and not directories! In other words, if I have a
> directory "test" inside the mount, the client PC will see a _file_
> called "test". When double-clicking on that "file", the Win7 client
> even ask to select the application to open it.
> 
> The strange this is that this problem happen with some Linux kernel
> version, but not with others. These are my results:
> 
> 1) Stock CentOS 6.5 x86-64 system (kernel 2.6.32-431.1.2.0.1,
> cifs-utils 4.8.1-19, samba 3.6.9-167): no problem here, but this
> kernel does not have CONFIG_CIFS_FSCACHE, so I can not use it for
> speeding up read access;
> 
> 2) CentOS 6.5 x86-64 with ElRepo updates (kernel 3.10.28-1): here
> CONFIG_CIFS_FSCACHE is enabled, but I have the problem described
> above;
> 
> 3) Debian 7 amd64 with latest updates (kernel 3.2.54-2, cifs-utils
> 2:5.5-1, samba 3.6.6-6): CONFIG_CIFS_FSCACHE is enabled, problem
> happens;
> 
> 4) Fedora 20 x86-64 (kernel 3.12.8-300, cifs-utils 6.3-1, samba
> 4.1.3-2): CONFIG_CIFS_FSCACHE is enabled and problem does _not_
> happen, however this is a client distro and I am not so comfortable
> to put it into production.
> 
> Anyone has any explanation of what is happening here?
> Regards.

Pretty sure this is to do with CIFSFS showing
a directory link count as 1, which leads
smbd to think it's a file.