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Date:   Thu, 17 Oct 2019 11:22:53 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Rick Macklem <rmacklem@uoguelph.ca>
Cc:     "Kornievskaia, Olga" <Olga.Kornievskaia@netapp.com>,
        "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
        "nfsv4@ietf.org" <nfsv4@ietf.org>
Subject: Re: NFSv4.2 server replies to Copy with length == 0
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On Thu, Oct 17, 2019 at 02:16:36AM +0000, Rick Macklem wrote:
> I have now found two cases where the Linux NFSv4.2 server does not
> conform to RFC-7862. One is as above and the other is a reply to Seek
> of NFS4ERR_NXIO when the sa_offset argument == file_size (instead of
> replying NFS_OK along with sr_eof == true).

Huh.  Looks like that's documented behavior of Linux's seek.  (See the
ERRORS section of the lseek(2) man page.)  Looks like Solaris also
returns -ENXIO in this case:

	https://docs.oracle.com/cd/E26502_01/html/E29032/lseek-2.html

And freebsd too:

	https://www.freebsd.org/cgi/man.cgi?query=lseek&sektion=2

I wonder where that spec language came from?

Our NFS server could translate an -ENXIO return into 0 and sr_eof ==
true easily enough, assuming -ENXIO is really only ever returned in that
case.

I haven't tested, but from a quick check of the Linux client code I
think that would require a matching fix on the client side to translate
sr_eof == 0 *back* to ENXIO.

I don't know if it's worth it.

--b.