"panic: len 0" on NFS read

[Peter Jeremy]

On 2014-Dec-25 20:08:20 -0500, Rick Macklem <rmacklem at uoguelph.ca> wrote:
>Peter Jeremy wrote:
>> Whilst trying to debug a RPC issue with a NFS tunneling tool, I
>> mounted a
>> NFS filesystem onto the same host and got a panic when I tried to
>> access it.
>> 
>> I'm running FreeBSD/amd64 10-stable r276177.
>> 
>> I mounted the filesystem with:
>> # mount -o udp,nfsv3 $(hostname):/tank/src92 /dist
>> 
>> (/tank/src92 and / are ZFS)
>> 
>> And then ran:
>> $ grep zzzz /dist/*
>> 
>> And got:
>> panic: len 0
>r275941 in head changed this KASSERT to allow a 0 length mbuf, so I
>don't think the panic is meaningful.
>Maybe r275941 should be MFC'd? (I've cc'd benno, who did the commit.)

Thanks.  I've tried MFCing r275941 and can't reproduce the panic by
following the above (though without knowing the exact reason for having a
0-byte mbuf in the chain originally, I can't be sure that I'm getting a
0-byte mbuf in the chain now).

-- 
Peter Jeremy
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