[Unionfs] modprobe error on CentOS 5.2 (RHEL 5.2)

[Nitin Bhardwaj]

On Wed, Jan 28, 2009 at 10:32 PM, Erez Zadok <ezk at cs.sunysb.edu> wrote:

> In message <1233134703.3005.47.camel at zeus.themaw.net>, Ian Kent writes:
> > On Tue, 2009-01-27 at 18:34 +0530, Nitin Bhardwaj wrote:
>
> [..]
> > > The dmesg output is as follows:
> > >
> > > unionfs: Unknown symbol vfs_splice_from
> > > unionfs: Unknown symbol krealloc
> > > unionfs: Unknown symbol lookup_one_len_nd
> > > unionfs: Unknown symbol vfs_splice_to
> > > unionfs: Unknown symbol vfs_path_lookup
> >
> > It looks like you haven't built the kernel rpms and updated the kernel
> > on the machine you want to use the module on.
> >
> > I think these are changes to the VFS proper made by the patch. They
> > won't be available if you try and install the module on a system with a
> > stock kernel.
>
> Ian is correct.  The best way to add such a patch to an RPM is to edit the
> rpmspec file and add it there, then rpmbuild the RPM.
>
> Erez.


Erez/Ian,

I'm still getting the errors inspite of rebuilding the new kernel;
Following are the steps I followed:

1. Unpacked the kernel-2.6.18-92.el5.src.rpm ( as non-root user)
2. Applied the patch 'unionfs-2.4_for_2.6.18-RHEL5.diff' to the kernel
successfully.
3. make menuconfig and gave option 'M' for Unionfs under "Layered
FileSystems".
4. Build the new kernel using rpmbuild command, which built two RPMs
successfully:
     kernel-2.6.18-92.el5.unionfs.rpm
     kernel-devel-2.6.18-92.el5.unionfs.rpm
5. (as root) Installed the new rpm
     rpm -ivh kernel-2.6.18-92.el5.unionfs.rpm
    which gave warnings:
WARNING: /lib/modules/2.6.18-92.el5.unionfs/kernel/fs/unionfs/unionfs.ko
needs unknown symbol vfs_splice_from
WARNING: /lib/modules/2.6.18-92.el5.unionfs/kernel/fs/unionfs/unionfs.ko
needs unknown symbol krealloc
WARNING: /lib/modules/2.6.18-92.el5.unionfs/kernel/fs/unionfs/unionfs.ko
needs unknown symbol lookup_one_len_nd
WARNING: /lib/modules/2.6.18-92.el5.unionfs/kernel/fs/unionfs/unionfs.ko
needs unknown symbol vfs_splice_to
WARNING: /lib/modules/2.6.18-92.el5.unionfs/kernel/fs/unionfs/unionfs.ko
needs unknown symbol vfs_path_lookup

6. Rebooted the system into the new kernel

Tried modprobe unionfs, which gave the same errors in dmesg, which I
mentioned in my earlier mail.


Here's what Dave suggested when I inquired about his progress on
RHEL+unionfs:

[...]

>I haven't been working on it since then actually, and haven't had a
>chance to get back to it.  Traditionally, RHEL likes to backport patches
>from newer upstream kernels.  This tends to break the unionfs patches
>because they're typically designed to match up to specific kernels, and
>the RHEL kernels essentially become a hybrid somewhere in between
>different versions.
>
>Usually every time Red Hat releases a new kernel for RHEL, someone has
>to unpack the kernel SRPM and tarball the build directory and ship it
>off to Erez and let him backport to it specifically.  I know for sure
>there's been new RHEL kernels since the last RHEL patch was made, so
>it's probably time to do that again.
>
>--
>Dave Miller                                   http://www.justdave.net/
>System Administrator, Mozilla Corporation      http://www.mozilla.com/
>Project Leader, Bugzilla Bug Tracking System  http://www.bugzilla.org/


Am i doing some step incorrectly or missing something here ? Or ( as Dave
Miller suggested) , we need a new patch release for RHEL 5.2 ( 2.6.18-92.el5
) , as Dave was sure Redhat has released a new kernel after Erez gave that
last patch for RHEL (unionfs-2.4_for_2.6.18-RHEL5.diff) ?



Thanks,
Nitin.
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