netdev - Re: [PATCH 6/6] NFS: idmap PipeFS notifier introduced

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Date:	Fri, 30 Dec 2011 17:54:03 -0500
From:	Trond Myklebust <Trond.Myklebust@...app.com>
To:	Stanislav Kinsbursky <skinsbursky@...allels.com>
Cc:	linux-nfs@...r.kernel.org, xemul@...allels.com, neilb@...e.de,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	jbottomley@...allels.com, bfields@...ldses.org,
	davem@...emloft.net, devel@...nvz.org
Subject: Re: [PATCH 6/6] NFS: idmap PipeFS notifier introduced

On Mon, 2011-11-28 at 17:34 +0300, Stanislav Kinsbursky wrote: 
> This patch subscribes NFS clients to RPC pipefs notifications. Idmap notifier
> is registering on NFS module load. This notifier callback is responsible for
> creation/destruction of PipeFS idmap pipe dentry for NFS4 clients.
> 
> Since ipdmap pipe is created in rpc client pipefs directory, we have make sure,
> that this directory has been created already. IOW RPC client notifier callback
> has been called already. To achive this, PipeFS notifier priorities has been
> introduced (RPC clients notifier priority is greater than NFS idmap one).
> But this approach gives another problem: unlink for RPC client directory will
> be called before NFS idmap pipe unlink on UMOUNT event and will fail, because
> directory is not empty.
> The solution, introduced in this patch, is to try to remove client directory
> once again after idmap pipe was unlinked. This looks like ugly hack, so
> probably it should be replaced in some more elegant way.
> 
> Note that no locking required in notifier callback because PipeFS superblock
> pointer is passed as an argument from it's creation or destruction routine and
> thus we can be sure about it's validity.
> 
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@...allels.com>

This patch gives me:

Kernel: arch/x86/boot/bzImage is ready  (#3)
  Building modules, stage 2.
  MODPOST 921 modules
ERROR: "nfs_idmap_init" [fs/nfs/nfs.ko] undefined!
ERROR: "nfs_idmap_quit" [fs/nfs/nfs.ko] undefined!
make[2]: *** [__modpost] Error 1
make[1]: *** [modules] Error 2
make: *** [sub-make] Error 2

if CONFIG_NFS_V4 is not defined.

Cheers
  Trond

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@...app.com
www.netapp.com

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