[Unionfs] UNIX domain sockets fail in RHEL5 patched unionfs

[Craig Johnston]

Erez,

Thank you for the offer of help.  I'll try to give you whatever you need.

The SRPM for the RHEL5 (5.3) kernel we are using is located here,
ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/os/SRPMS/kernel-2.6.18-128.1.1.el5.src.rpm

This includes the kernel .config file (we are using the SMP i386
kernel).  If this form doesn't work for you, I can create a tarball
for you.

We started with the 2.5.1 patch for 2.6.18.8.  And modeled our changes
on the unionfs-2.4_for_2.6.18-RHEL5.diff.gz that is located on the
UnionFS download server.

We had to muck around with the lookup_one_len() symbol (breaking the
kernel API :( ), and found a couple of areas where RH had patched the
kernel forward.

In vfs_path_lookup(), we needed to change the call to audit_inode() as
the parameters changed.  Also changed the signature of
unionfs_filldir() and readdir_util_callback() to make the ino
parameter a u64.

The LOOKUP_ONE #define had to be changed to (0x1000) to avoid
conflicting with LOOKUP_ATOMIC (128 (or 0x80)).  Note the RHEL5 patch
moved this to 256, but I think that conflicted with LOOKUP_OPEN
(0x0100 or (256)).  I don't know why the confusing change in base for
the #defines in namei.h ;)

I've attached the complete patch we applied to the stock kernel if you
are interested.

Thanks,
Craig


On Tue, Mar 10, 2009 at 9:20 AM, Erez Zadok <ezk at cs.sunysb.edu> wrote:
>
> In message <f4f856dc0903031620y2e9559c8sa5b65f6bc9780d36 at mail.gmail.com>, Craig Johnston writes:
>
> > We have patched a RHEL5 (5.3) kernel with the latest 2.5.1 unionfs patches.
> > We started with the 2.6.18.8 patch set, and modified it until it went into
> > RH's heavily modified kernel.  We didn't have to do do much (most remove
> > stuff that RH already had).
> >
> > In the end, things seem to work Ok except that UNIX domain sockets that are
> > created within a unionfs writeable layer do not work.  They can be created
> > (nc -lU /var/run/mysocket), but we receive an ECONNREFUSED when the client
> > tries to connect (nc -U /var/run/mysocket).
> [...]
>
> Craig, I've not heard from others of having problems with domain sockets.
> Maybe there's something else in the rhel kernel which is preventing them
> from working.  It's also possible that something went wrong during the hand
> application of the unionfs patch to the rhel kernel.
>
> Can you send me a tarball with the unmodified rhel5.3 kernel sources, and
> your kernel .config file?  I'll apply the unionfs patch carefully and test
> it here to ensure that it passes my regression suite, including the tests
> for sockets.
>
> Cheers,
> Erez.
>
> PS. does anyone know if there's a git repo of the rhel kernel, being kept
> somewhere and up-to-date (preferably one that isn't git-rebase'd).  If I had
> access to one, it'd be easier for me to keep up-to-date a set of unionfs
> patches against the latest rhel kernels (it's a popular request).
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