shadow_copy2 requires wide links enabled

[Volker Lendecke]

On Thu, Jan 06, 2011 at 07:27:08PM -0800, Paul B. Henson wrote:
> We currently use Solaris 10's bundled version of samba to serve zfs
> filesystems with Ed Plese's shadow_copy_zfs to allow zfs snapshots as a
> shadow copy source. The current shipping version of Solaris samba is based
> on 3.0.37 8-/, but I'm testing a new version based on samba 3.5.5 that
> should be released soon. Unfortunately, Ed's patches to shadow_copy2 to
> provide zfs compatibility (among other features) seem not to have made it
> into the 3.5 branch, so I pulled a copy of the source for that module from
> the 3.6 branch from right after Ed's patches were merged in and compiled it
> under 3.5.5 to use as a binary module with the 3.5.5 based Solaris samba
> (I've requested they do this themselves and include it in the production
> release, but haven't heard whether they will).
> 
> To get to the point, shadow copies weren't working and I traced it down to
> samba considering the shadow copy a wide link, and wide links are disabled
> by default:
> 
>   check_reduced_name [@GMT-2011.01.07-02.06.23/license/:2eDS_Store] [/export/user/henson]
>   check_reduced_name realpath [@GMT-2011.01.07-02.06.23/license/:2eDS_Store] -> [/export/user/henson/.zfs/snapshot/backup-2011.01.06-18.06.23/license/:2eDS_Store]
>   check_reduced_name: Bad access attempt: @GMT-2011.01.07-02.06.23/license/:2eDS_Store is a symlink outside the share path
> 
> 
> Once I enabled wide links the shadow copy functionality worked fine. It
> looks like there's some magic in the names the shadow copy module uses that
> confuses the link check code.
> 
> I'd prefer not to have to enable wide links for shadow copy functionality.
> Is this perchance fixed already in the development branch? Or a result of
> something stupid I've done rather than an issue with samba?

We have made changes to fix this. The new CONNECTPATH
operation is made to fix it, and it is present in 3.5. The
version a customer of mine is using is definitely regularly
tested for this feature, but that is 3.4 with backported
patches. It is surprising that it does not work for you in
3.5.5, that definitely has those patches. We need more logs.
But be aware, the shadow_copy2 module is really HELL to
debug.

With best regards,

Volker Lendecke

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