[pme@devphil.com: Bug#239158: Strange exportfs problems, fantastically unhelpful error message]

[pme@devphil.com: Bug#239158: Strange exportfs problems, fantastically unhelpful error message]

[Chip Salzenberg]

This Debian bug report includes an exportfs problem which I suspect is
due to one export tree under the other, and an error message complaint
which I think is justified....

----- Forwarded message from Phil Edwards <pme@devphil.com> -----

Subject: Bug#239158: Strange exportfs problems, fantastically unhelpful error message
From: Phil Edwards <pme@devphil.com>
To: Debian Bug Tracking System <submit@bugs.debian.org>
Date: Sun, 21 Mar 2004 00:37:43 -0500

Package: nfs-kernel-server
Version: 1:1.0.6-1
Severity: normal

    [~]# cat /etc/exports
    /usr/local      fenric(ro,async) hreidmar(ro,async)
    /home           fenric(rw,sync) hreidmar(rw,sync)
    [~]# exportfs -v -r
    exporting hreidmar:/usr/local
    exporting fenric:/usr/local
    exporting hreidmar:/home
    exporting fenric:/home
    exporting hreidmar:/usr/local to kernel
    hreidmar:/usr/local: Invalid argument
    exporting fenric:/usr/local to kernel
    fenric:/usr/local: Invalid argument
    reexporting hreidmar:/home to kernel
    reexporting fenric:/home to kernel
    [~]#

I have no idea why the export fails.  If either line is commented, then
the export succeeds; presumably that's strong evidence of /something/,
but I don't know the nfs-kernel-server code at all and so can't say what.

My real complaint is that "Invalid argument" doesn't tell me a damn thing,
so I have no idea what to try next.


-- System Information:
Debian Release: testing/unstable
Architecture: i386
Kernel: Linux fenric 2.4.22-fenric3 #1 SMP Sun Oct 12 00:45:53 EDT 2003 i686
Locale: LANG=C, LC_CTYPE=C

Versions of packages nfs-kernel-server depends on:
ii  debconf                     1.4.7        Debian configuration management sy
ii  libc6                       2.3.2.ds1-11 GNU C Library: Shared libraries an
ii  libwrap0                    7.6-ipv6.1-3 Wietse Venema's TCP wrappers libra
ii  nfs-common                  1:1.0.6-1    NFS support files common to client
ii  sysvinit                    2.85-9       System-V like init.

-- debconf information:
  nfs-kernel-server/sync-default: 
  nfs-kernel-server/tcpwrappers-mountd: 




----- End forwarded message -----

-- 
Chip Salzenberg               - a.k.a. -               <chip@pobox.com>
"I wanted to play hopscotch with the impenetrable mystery of existence,
    but he stepped in a wormhole and had to go in early."  // MST3K


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Re: [pme@devphil.com: Bug#239158: Strange exportfs problems, fantastically unhelpful error message]

[Olaf Kirch]

On Sun, Mar 21, 2004 at 10:35:15AM -0500, Chip Salzenberg wrote:
> This Debian bug report includes an exportfs problem which I suspect is
> due to one export tree under the other, and an error message complaint
> which I think is justified....

Well, what he tries to do is invalid from the kernel point of view.
And unfortunately there's no "EBADNFSEXPORTPLEASEREADTHEMANPAGE" :-)

I agree though this issue is confusing to many people. Wasn't there
some work going on to allow an arbitrary configuration of exports?
For each file handle, we need to establish the dentry chain anyway,
so it should not be too hard to find the proper export entry.

Olaf
-- 
Olaf Kirch     |  Stop wasting entropy - start using predictable
okir@suse.de   |  tempfile names today!
---------------+ 


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Re: [pme@devphil.com: Bug#239158: Strange exportfs problems, fantastically unhelpful error message]

[Greg Banks]

Chip Salzenberg wrote:
> 
> This Debian bug report includes an exportfs problem which I suspect is
> due to one export tree under the other, 

Possibly, if one of /usr/local or /home is a symlink to somewhere
underneath the other.

> and an error message complaint
> which I think is justified....

I second this complaint.  On other OSes that case is checked in
userspace early and a sensible message printed, e.g.

irix# exportfs -av
re-exported /
exportfs: /opt: parent-directory (/) already exported
re-exported /mnt/scratch

> I have no idea why the export fails.  If either line is commented, then
> the export succeeds; presumably that's strong evidence of /something/,
> but I don't know the nfs-kernel-server code at all and so can't say what.

You can get a better idea of what is failing by:

linux# echo 4 > /proc/sys/sunrpc/nfsd_debug

linux# exportfs -av
exporting foo.melbourne.sgi.com:/home/fmeh
exporting bar.melbourne.sgi.com:/home/fmeh
exporting foo.melbourne.sgi.com:/home
exporting bar.melbourne.sgi.com:/home
exporting foo.melbourne.sgi.com:/home/fmeh to kernel
exporting bar.melbourne.sgi.com:/home/fmeh to kernel
exporting foo.melbourne.sgi.com:/home to kernel
foo.melbourne.sgi.com:/home: Invalid argument
exporting bar.melbourne.sgi.com:/home to kernel
bar.melbourne.sgi.com:/home: Invalid argument

linux# tail /var/log/messages
...
Mar 22 09:49:53 4A:quux kernel: exp_export called for foo.melbourne.sgi.com:/home
(403/54526548 fl 24).
Mar 22 09:49:53 4A:quux kernel: exp_export: export not valid (Rule 3).  <------
Mar 22 09:49:53 4A:quux kernel: exp_export called for bar.melbourne.sgi.com:/home
(403/54526548 fl 24).
Mar 22 09:49:53 4A:quux kernel: exp_export: export not valid (Rule 3).  <------

The error message tells you...indirectly...what is going on.  You need
to match it to the source of fs/nfsd/export.c:exp_export() to make any
sense of it.  The "Rule 3" message happens when a child of the given
directory is already exported.

Greg.
-- 
Greg Banks, R&D Software Engineer, SGI Australian Software Group.
I don't speak for SGI.


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