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

From: Trond Myklebust
Date: Fri Dec 30 2011 - 17:54:51 EST

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@xxxxxxxxxxxxx>

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.


Trond Myklebust
Linux NFS client maintainer


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