sec=null on nfsroot

[hsasshofer]

Hi,

I am currently using a server which PXE-boots a XEN-based Dom0 image via nfsroot and Unionfs. This works perfectly (with a custom built kernel allowing DHCP autoconfig and nfsroot) on FC4. Upgrading to FC5 works with the (original) 2.6.17-based kernel, but stops due the the known Unionfs problems with 2.6.18.

But the problem is now that I tried to upgrade to FC6 (substituting aufs for unionfs, which works nicely), the NFS rootfs mount shows a very strange behaviour (even before aufs steps in):

While on my 2.6.17 FC5 exporting
/nfsroot/ 172.16.0.0/255.255.254.0(ro,no_root_squash,no_all_squash,asyn c)
yields the following (expected) entry in /proc/mounts of the client
/dev/root / nfs ro,vers=2,rsize=4096,wsize=4096,hard,nolock,proto= udp,timeo=11,retrans=2,addr=172.16.0.1 0 0
the same line with 2.6.18 FC5 (regardless of minor version) gives
/dev/root / nfs ro,vers=2,rsize=4096,wsize=4096,hard,nolock,proto= udp,timeo=11,retrans=2,sec=null,addr=172.16.0.1 0 0
and inhibits access to non-public files (sec=null!!!) . Exporting via
/nfsroot/ 172.16.0.0/255.255.254.0(ro,root_squash,all_squash,anonuid=0, anongid=0,async)
gives better results, but can't be the solution. Standard NFS mounts work as expected though. Kernel is currently 2.6.18-1.2869.fc6, nfs-utils 1.0.10-5.fc6.

Can anyone offer help or an explanation of what's happening ?

Thank you.

[hsasshofer]

The patch below fixes the problem - and it's not in the current FC6 kernel:
Von: Trond Myklebust <Trond.Mykleb...@netapp.com>
In:
Datum: Thu, 03 Aug 2006 10:33:52 -0400
Lokal: Do 3 Aug. 2006 15:33
Betreff: No Subject
Signed-off-by: Trond Myklebust <Trond.Mykleb...@netapp.com>
---

fs/nfs/super.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 867b5dc..97cfb14 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -471,12 +471,14 @@ static int nfs_validate_mount_data(struc
data->version);
return -EINVAL;
}
- /* Fill in pseudoflavor for mount version < 5 */
- data->pseudoflavor = RPC_AUTH_UNIX;
case 5:
memset(data->context, 0, sizeof(data->context));
}

+ /* Set the pseudoflavor */
+ if (!(data->flags & NFS_MOUNT_SECFLAVOUR))
+ data->pseudoflavor = RPC_AUTH_UNIX;
+
#ifndef CONFIG_NFS_V3
/* If NFSv3 is not compiled in, return -EPROTONOSUPPORT */
if (data->flags & NFS_MOUNT_VER3) {