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

[Ian Kent]

On Thu, 2009-01-29 at 12:27 +0530, Nitin Bhardwaj wrote:
> 
> 
> 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) ?

That process sounds ok but if it wasn't, such as you didn't add the
patch to the spec file before the build, then you shouldn't have ended
up with a module at all. I'll check the patch applies, maybe build a
kernel and see. Having time to do this is a problem so you'll need to
wait a while.

Ian