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Date:      Mon, 26 Nov 2007 13:36:44 +0100
From:      =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no>
To:        Robert Watson <rwatson@FreeBSD.org>
Cc:        Timo Sirainen <tss@iki.fi>, freebsd-current@FreeBSD.org, Adam McDougall <mcdouga9@egr.msu.edu>, mohans@FreeBSD.org
Subject:   Re: link() not increasing link count on NFS server
Message-ID:  <86ir3p4203.fsf@ds4.des.no>
In-Reply-To: <20071115135734.O82897@fledge.watson.org> (Robert Watson's message of "Thu\, 15 Nov 2007 14\:05\:34 %2B0000 \(GMT\)")
References:  <20071115074247.GQ37473@egr.msu.edu> <20071115123543.H82897@fledge.watson.org> <1195132320.6039.135.camel@hurina> <20071115135734.O82897@fledge.watson.org>

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Robert Watson <rwatson@FreeBSD.org> writes:
> Indeed, and inspection of nfs_vnops.c:nfs_link(): finds:
>
> 1772         /*
> 1773          * Kludge: Map EEXIST =3D> 0 assuming that it is a reply to =
a retry.
> 1774          */
> 1775         if (error =3D=3D EEXIST)
> 1776                 error =3D 0;
> 1777         return (error);
>
> Neither Linux nor Solaris appears to have this logic in the client.  I
> assume this is, as suggested, to work around UDP retransmissions where
> the reply is lost rather than the request.  It appears to exist in
> revision 1.1 of nfs_vnops.c, so came in with 4.4BSD in the initial
> import, but doesn't appear in NetBSD so I'm guessing they've removed
> it.

Wrong, it still exists in NetBSD, but they've separated part of
nfs_link() (including that bit) out into nfs_linkrpc().  They also seem
to have added logic to detect a retransmit:

        /*
         * Kludge: Map EEXIST =3D> 0 assuming that it is a reply to a retry.
         */
        if (rexmit && error =3D=3D EEXIST)
                error =3D 0;

revision 1.197
date: 2004/05/10 10:40:42;  author: yamt;  state: Exp;  lines: +32 -25
don't do kludge for a reply to a retransmitted request
unless we actually retransmitted the request.

DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no



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