Re: Current NFS issues (2.5.59)

[Neil Brown]

On Sunday February 9, [e-mail] wrote:
> Ok.  Here goes.  I have two servers that NFS mount from each other and 
> provide.

Thankyou for using the development kernel and sharing your woes...

> 
> Server 1 exports A, B, and C to server 2.  Server 2 exports D and E back 
> to server 1 and exports F and G to two other clients.  Each of these 
> (A-G) are distinctly different filesystem paths and not part of each other.
> 
> 1. If server 1 is restarted, server 2 will invalidate (make all 'df' 
> values '1') F and G.  This requires an 'exportfs -vra' or similar on 
> server 2 to fix the client 'df' values.  The client doesn't need to do 
> anything.

This has me completely mystified.  If I understand correctly, an event
on server 1 causes a failure to commuinicate between server 2 and some
third party..

I can only imagine that as server 1 boots it does something to server
2.  At the very least it sends a mount request for D and E.  I'm not
sure how a mount request for D or E would affect F or G.
Are you using an automounter at all?

> 
> 2. Repeated nfs system stops and starts (/etc/init.d/nfs restart) will 
> eventually cause a kernel panic on server 2 (haven't tested on server 
> 1).   The number of restarts is variable.

Can you capture the panic and send it to me please?

> 
> 3. Mount point F (/home/david) infrequently loops.  ls -la /home/david 
> will loop forever until all client memory is exhausted and the kernel 
> kills it via OOM.  ls -la /home/david/somefile or /home/david/somedir/ 
> works just fine as well as any sub directory under /home/david.  
> Restarts of both systems refuse to fix things.

I think this might be a reiserfs problem.  Someone else mentioned that
this started happening when they upgrade from an earlier 2.5 kernel.
If you can capture the NFS traffic 
	tcpdump -s 1500 -w /tmp/afile host $server and host $client
we could have a look at the directory cookies and see what is
happening.

> 
> 4. Mounts infrequently get "permission denied" messages on the client 
> with a " rpc.mountd: getfh failed: Operation not permitted" message on 
> the server.  This is fixable by restarting the nfs system on the server.
> 

I've seen this, but it was fixed by the time 2.5.59 came out.
If/when it happens again, could you please check if the IP address of
the client in question is in
    /proc/net/rpc/auth.unix.ip/content
and if the name found there is in
    /proc/fs/nfs/exports
next to the appropriate filesystem.

NeilBrown