From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [nfs] Oops during call nfs_mountpoint_inode_operations->lookup()
 method
Date: Mon, 17 Jan 2011 22:18:46 +0000
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To: Vitaliy Gusev <gusev.vitaliy@gmail.com>
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On Mon, Jan 17, 2011 at 08:04:02PM +0300, Vitaliy Gusev wrote:

> diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
> index db6aa36..c5f9162 100644
> --- a/fs/nfs/namespace.c
> +++ b/fs/nfs/namespace.c
> @@ -177,10 +177,16 @@ out_follow:
>  const struct inode_operations nfs_mountpoint_inode_operations = {
>  	.follow_link	= nfs_follow_mountpoint,
>  	.getattr	= nfs_getattr,
> +#ifdef CONFIG_NFS_V4
> +	.lookup		= nfs_atomic_lookup,
> +#endif
>  };
> 
>  const struct inode_operations nfs_referral_inode_operations = {
>  	.follow_link	= nfs_follow_mountpoint,
> +#ifdef CONFIG_NFS_V4
> +	.lookup		= nfs_atomic_lookup,
> +#endif
>  };

That looks very wrong.  You are papering over the real problem here - ask
yourself what would that ->lookup() be expected to do?

The thing is, we shouldn't end up trying to call ->lookup() for those.
That's the real issue...