UnionFS over NFS over UnionFS

[Wilhelm Meier <meier@informatik.fh-kl.de>]

Hello everybody,

the below problem was allready posted to the unionfs-list, but remains=20
unsolved:
=2D-------------

To clarify things further, this happens only in the follwing scenario (as
described in previous posting, see below):

1) we build a union mounted on server:/tftproot/gentoo_B
2) we export this union via NFS
3) we mount server:/tftproot/gentoo_B onto client:/mnt/test/N
4) we build a union on the client consisting of /mnt/test/N an some tmpfs

If we change step 2) to export some local filesytem (tftproot/gentoo_A in
the below example) and change step 3) to mount server:/tftproot/gentoo_A
onto the client, all works well.

A saw a posting on this list reporting similar problems. Are the any hints?

=2D-
Wilhelm


> Hello,
>
> thank you for the advice, but this does not solve the problem.
>
> On the other hand, I tried to export and nfs-mount all rw, but to declare
> the nfs-mounted branch ro for the union-mount:
>
> gs test # mount
> /dev/hda1 on / type ext3 (rw,noatime)
> proc on /proc type proc (rw)
> sysfs on /sys type sysfs (rw)
> udev on /dev type tmpfs (rw,nosuid)
> devpts on /dev/pts type devpts (rw)
> /dev/hdb1 on /tftproot type ext3 (rw,noatime)
> none on /tftproot/gentoo_B type unionfs
> (rw,dirs=3D/tftproot/gentoo_Bdiff=3Drw:/tftproot/gentoo_A=3Dro)
> shm on /dev/shm type tmpfs (rw,noexec,nosuid,nodev)
> nfsd on /proc/fs/nfs type nfsd (rw)
> rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
> 192.168.39.10:/tftproot/gentoo_B on /mnt/test/N type nfs
> (rw,addr=3D192.168.39.10)
> none on /mnt/test/T type tmpfs (rw)
> none on /mnt/test/A type unionfs (rw,dirs=3D/mnt/test/T=3Drw:/mnt/test/N=
=3Dro)
>
> gs test # touch A/x
> touch: setting times of `A/x': Operation not permitted
>
> gs test # ls A
> bin =A0 dev =A0home =A0mnt =A0proc =A0sbin =A0 =A0 =A0 =A0 =A0sys =A0usr
> boot =A0etc =A0lib =A0 opt =A0root =A0stateless.sh =A0tmp =A0var
>
> gs test # touch N/x
>
> gs test # ls A
> bin =A0 dev =A0home =A0mnt =A0proc =A0sbin =A0 =A0 =A0 =A0 =A0sys =A0usr =
=A0x
> boot =A0etc =A0lib =A0 opt =A0root =A0stateless.sh =A0tmp =A0var
>
> gs test # touch A/x
> touch: setting times of `A/x': Operation not permitted
> gs test #
>
> Any hints?
>
> -
> Wilhelm
>>
>> Hi!!
>>
>>> The same problem arises also a simpler setup (on the a single machine):
>>>
>>> gs ~ # mount
>>> /dev/hda1 on / type ext3 (rw,noatime)
>>> proc on /proc type proc (rw)
>>> sysfs on /sys type sysfs (rw)
>>> udev on /dev type tmpfs (rw,nosuid)
>>> devpts on /dev/pts type devpts (rw)
>>> /dev/hdb1 on /tftproot type ext3 (rw,noatime)
>>> shm on /dev/shm type tmpfs (rw,noexec,nosuid,nodev)
>>> nfsd on /proc/fs/nfs type nfsd (rw)
>>> /dev/hdc on /mnt/cdrom type iso9660 (ro)
>>> none on /tftproot/gentoo_B type unionfs
>>> (rw,dirs=3D/tftproot/gentoo_Bdiff=3Drw:/tftproot/gentoo_A=3Dro)
>>> rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
>>> 192.168.39.10:/tftproot/gentoo_B on /mnt/test/N type nfs
>>> (rw,addr=3D192.168.39.10)
>>
>> If this share is exported RO it should be mounted RO only. Unfortunately
>> I
>> may mount a RO nfs share with RW option on a client (of course it does
>> not
>> renders the share writeable) - but it will confuse unionfs. If you mount
>> your share explicitly RO you shouldn't get a permission denied...
>>
>> We had the same problem with RO nfs root filesystem unioned with RW
>> tempfs
>> on top of it. Hope I got the idea right what you intend to do :-))
>>
>> Ciao,
>> =A0=A0=A0=A0=A0Dirk
>>
>>> none on /mnt/test/T type tmpfs (rw)
>>> none on /mnt/test/A type unionfs
>>> (rw,dirs=3D/mnt/test/T=3Drw:/mnt/test/N=3Dro)
>>> gs ~ #
>>>
>>> As you see 192.168.39.10:/tftproot/gentoo_B is exported and mounted
>>> on /mnt/test/N. This is union-mounted together with tmpfs /mnt/test/T
>>> on /mnt/test/A.
>>>
>>> On /mnt/test/A we get:
>>>
>>> gs A # touch x
>>> touch: setting times of `x': Operation not permitted
>>>
>>>
>>> Am Montag, 5. Dezember 2005 13:48 schrieben Sie:
>>> > >NFS: Buggy server - nlink =3D=3D 0!
>>> > >nfs_fhget: iget failed
>>> > >
>>> > >We are using unionfs-1.0.14
>>> >
>>> > Step 1: Try updating to 1.1.1 or some CVS snapshot.
>>> >
>>> >
>>> >
>>> >
>>> > Jan Engelhardt
>>>
>>> --
>>> --
>>> Wilhelm Meier
>>> email: meier@informatik.fh-kl.de
>>> _______________________________________________
>>> unionfs mailing list
>>> unionfs@mail.fsl.cs.sunysb.edu
>>> http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs
>>>
>>
>
>
>
=2D-=20
=2D-
Wilhelm Meier
email: meier@informatik.fh-kl.de


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