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

[Greg Banks <gnb@melbourne.sgi.com>]

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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