Re: problems with ip_conntrack on Linux 2.6.x (x>5)

Clint Adams [[email protected]] wrote:
> > I've never really used ip_conntrack.  Did something change in that code,
> > or the generic kernel NFS code between 2.6.5 and 2.6.6?  Does your
> > problem happen if the kernel module is loaded just on the client or the
> > server, or does it have to be both?
> 
> Either side.  If it's loaded on the server, there will be localhost NFS
> hangs on the server.  If it's loaded on the client, there will be
> localhost NFS hangs on the client.
> 
> In either case, it's possible to cd around the filesystem and run ls,
> but not to copy files.

Ok.  I did some more testing and I'm seeing your problem now,
particularly when copying files.  I found a thread which discusses this
issue:

  http://lists.netfilter.org/pipermail/netfilter-devel/2004-May/015233.html

The thread basically says that if the the NFS mounts are done with a
r/wsize <= 8192, then things will work.  By default, it seems that NFS
mounts have a r/wsize = 32K (SFS is not setting/changing this value from
what I can tell).

I did a quick test which seems to check this--perhaps someone else can
do the same to confirm:  

# modprobe ip_conntrack
# mount localhost:/some/nfs/export /mnt
# cp /mnt/some-biggish-file /tmp
< hang >

  versus

# modprobe ip_conntrack
# mount -orsize=8192,wsize=8192 localhost:/some/nfs/export /mnt
# cp /mnt/some-biggish-file /tmp
< works! >

This sounds like a kernel issue, but I imagine inserting a work-around
into SFS wouldn't be very difficult.

Michael