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From:   Vasyl Vavrychuk <vvavrychuk@gmail.com>
Date:   Wed, 28 Oct 2020 10:53:20 +0200
Message-ID: <CAGj4m+5j1ZK+=-4w6LpRLsnEPvi=UfpO3r8PruRtcJib9gbYyQ@mail.gmail.com>
Subject: Re: Hard linking symlink does not work
To:     Patrick Goetz <pgoetz@math.utexas.edu>,
        "J. Bruce Fields" <bfields@fieldses.org>
Cc:     linux-nfs@vger.kernel.org
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Thanks for replies about my problem. It is actually a practical one...

I need to compile Yocto BSP which builds only under older
distributions. For convenience I have established a Vagrant virtual
machine which uses NFS to share workspace with the host machine.

Now coming back to hardlinking symlinks.

Yocto build system uses hardlinks to prepare sysroot for packages, and
symlinks are part of that sysroot provided by other packages.

On Tue, Oct 27, 2020 at 10:03 PM Patrick Goetz <pgoetz@math.utexas.edu> wrote:
>
>
>
> On 10/27/20 12:12 PM, J. Bruce Fields wrote:
> > On Fri, Oct 23, 2020 at 01:13:02PM +0300, Vasyl Vavrychuk wrote:
> >> I have found that hard links for regular files works well for me over NFS:
> >>
> >> $ touch bar
> >> $ ln bar tata
> >>
> >> But if I try to make hard link for symlink, then it fails:
> >>
> >> $ ln -s foo bar
> >> $ ln bar tata
> >> ln: failed to create hard link 'tata' => 'bar': Operation not permitted
> >
> > Huh.  I'm not sure I even realized it was possible to hardlink symlinks.
> > Makes sense, I guess.
>
> What's even the use case for hard linking a symlink?  That sounds like
> asking for trouble...
>
>
> >
> > I think my first step debugging this would be to watch wireshark while
> > attempting the "ln", and see what happens.  That should tell us whether
> > it's the client or server that's failing the operation.
> >
> > --b.
> >
> >>
> >> I am using NFSv4 with Vagrant, here is mount entry:
> >>
> >> 172.28.128.1:PATH on /vagrant type nfs4
> >> (rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=IP,local_lock=none,addr=IP)
> >>
> >> I have also verified that rpc-statd is running on host.
> >>
> >> Host machine is Ubuntu 18.04 with NFS packages version 1:1.3.4-2.1ubuntu5.3.
> >>
> >> Will appreciate help on this.
> >>
> >> Thanks,
> >> Vasyl