nfs-utils/lockd problems

Hello everyone,

I'm encountering unmount issues with lockd on stock 2.4.18 kernels. The problem:

On the raidzone1(ip=192.168.2.224) server host(where knfsd is running on 2.4.18), prior to exporting /home to client 192.168.2.134 with rw,sync,no_root_squash options, I mount /dev/sda1 to /home. Then I export the client.(btw, this is the only client+export point in the kernel tables)

On the nfs client(ip=192.168.2.134) which also has a stock 2.4.18 kernel, I mount the nfs export-point /home from raidzone1 onto /test. I go ahead and issue a posix file lock(range=whole file) for *one* file on the mounted nfs filesystem. The nfs client acquires the lock successfully.

The problem:

Now on the server host I unexport the client via unexportfs -u 192.168.2.134:/home. Checked /proc/fs/nfs/exportfs: cleaned-out,no entries. Remember: client still has /home mounted on his side.

But, when I try to umount /dev/sda1 from /home, I get a "device is busy" error. Same error even if I try to force the umount.

It is important to note, that I only get the umount problems IF the client has issued locks. It doesn't matter if the client has open files on the nfs fs, transferring data, type of lock,etc.

A simple work-around for this problem is to shutdown the nfs subsystem and restart it. Another way would be if the client unlocks the files. In both cases I can proceed to umount /home. To me however, such solutions are unacceptable. I know this much: this problem is with lockd.

More investigation reveals that knfsd is informing lockd to remove locks when a *client* is removed. Call path: handle_sys_nfsservctl-> nfsdelclient->exp_delcient->exp_freeclient->nfsd_lockd_unexport-> nlmsvc_invalidate_client. Funny thing is, exportfs in nfs-utils-1.0.1-pre8 never calls nfsctl() with NFS_DELCLIENT when unexporting a client+export_point; it only calls nfsctl() with NFS_UNEXPORT. On the other hand, exportfs does call nfsctl() with NFS_ADDCLIENT & NFS_EXPORT.

So has anyone come up with a fix where knfsd tells lockd to "remove all locks on this nfs filesystem/export-point"?

Thanks for any help,

Kashif Shaikh

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I was experiencing all sorts of badness with my mail spool on an NFS mounted filesystem. Upgrading the server to 2.4.19-rc1-ac3 seems to have done the trick. All gone!

Steve

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