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    SubjectRe: NFS Problem in Kernel 2.0.27: inode status not updated
    Matthias Urlichs <smurf@work.smurf.noris.de> wrote:
    > srb@cuci.nl (Stephen R. van den Berg) writes:
    >> Tim Wright <timw@sequent.com> wrote:
    >> >You cannot rely on ANY Unix filesystems semantics using NFSv2.

    >> I agree that it's fairly bad. But, if you make sure that you're the
    >> only client operating on a certain file which has never existed before,
    >> the results aren't so bad (if the NFS-client and server are a good quality
    >> implementation).

    >Why should you want that?

    In order to implement a locking scheme, or a maildir type mail delivery
    system, that works across NFS.

    >IMHO, relying on any such thing is evil. People will surely use your code
    >in environments where that assumption doesn't hold; after all, it works (almost)
    >flawlessly regardless, right?

    >The "almost" is the problem.

    It's not really a problem. The assumption is *not* a requirement to make
    the code work correctly. If the assumption does not hold, two things
    can happen:
    - The code will work regardlessly, because it anticipates some kind of
    deviation from the standard.
    - The code will report a problem, and will refuse to continue.

    >Read maildir(5), a manual page from the qmail system. It describes a reliable
    >mail delivery system which works over NFS, even if multiple mail servers
    >write to the same mail spool.

    It makes use of the same assumptions I made to implement the
    NFS-resistent-locking scheme. It wouldn't surprise me if Bernstein
    took a good look at the locking scheme before creating the maildir
    implementation.

    >much yet, unfortunately. However, IMHO it's a much better idea to create a
    >patch for elm which supports maildir than to invent yet another limited-use
    >locking scheme.

    This locking scheme predates the maildir implementation by more than six
    years. So we're not inventing "yet another" locking scheme.
    --
    Sincerely, srb@cuci.nl
    Stephen R. van den Berg (AKA BuGless).
    "I don't like this word bomb. It is not a bomb, it is a device,
    which explodes." French Ambassador about the atomic tests.

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