Re: [PATCH] NFS: Sign Extentions with Tru64 FSIDs.

[Peter Staubach <staubach@redhat.com>]

Trond Myklebust wrote:
> On Mon, 2007-03-05 at 15:35 -0500, Steve Dickson wrote:
>   
>> Over the last new months, I've been getting beaten up
>> about the fact the Fedora Core clients (FC5 and FC6)
>> no loner works with Tru64 server. The problem is
>> accessing mounted directories would fail with -ENOTDIR.
>> Similar to:
>>
>> # ls /mnt/alpha/doc
>> /bin/ls: cannot open directory /mnt/alpha/doc: Not a directory
>>
>> After months of floundering around looking at ethereal
>> traces and such, I actually was able to trace down a
>> Tru64 server to test against (thanks you very much HP!).
>>
>> Low and behold... it turns not to be a Linux client
>> bug at all... but only Linux clients failed because
>> they seem to actually care what fsids are being returned.
>>
>> The problem is this: Tru64 server exporting Advfs fileystems
>> return sign extend fsids in most but not all NFS procedures.
>>
>> Meaning most fattrs returned by the server have a fsid of:
>>      fsid: 0xffffffff8419f8d5
>>
>> but in some procs (like READDIRPLUS) the fsid is
>>      fsid: 0x000000008419f8d5
>>
>> Which is _clearly_ wrong and does not happen with UFS
>> exports on the same server.
>>
>> So its my contention that Tru64 has been broken forever
>> since only Linux clients fail, which started due to the
>> following patch that went into 2.6.12:
>>     
>
> Sorry, but I really do not like the idea of fixing server bugs in the
> Linux client, and particularly not in generic code like this.
>
> As far as I understood, this was a direct consequence of using the
> 32bitclients export option to work around the old issues with 64-bit
> cookies on readdir. Is there really a need for this option now that
> we've ensured that readdir cookies are no longer exported to userland?

Just to be clear, you are proposing to remove the "32bitclients"
export option from the export options on the deployed Tru64 server?

A potential issue that I could see would be if there are other NFS
clients, who do need that export option used in order to interoperate
with this server.

It is an ickey idea and the right way is to fix the Tru64 server, but
given that we probably can't get it fixed, this seems relatively low
risk.

It also wouldn't be the first time (or last probably :-) ) that we've
worked around a bug in another implementation that should rightly
have been fixed in that other implementation.  :-)

       ps

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