[Devel] Re: [PATCH 2/4] NFS: replace per-net client lock by mutex

[Myklebust, Trond]

On Mon, 2012-02-27 at 17:49 +0400, Stanislav Kinsbursky wrote:
> Lockdep is sad otherwise, because inode mutex is taken on PipeFS dentry
> creation, which can be called on mount notification, where this per-net client
> lock is taken on clients list walk.
> 
> Note: I used simple mutex instead of rw semaphore because of
> nfs_put_client->atomic_dec_and_mutex_lock() call. Probably, there is a better
> solution here.
> 
> Signed-off-by: Stanislav Kinsbursky <skinsbursky at parallels.com>
> 

This is overkill... We end up blocking NFSv4 callbacks while the
rpc_pipefs notifier runs through the nfs_clients creating or destroying
idmapper dentries.

Surely the rpc_pipefs_event() can take a reference to the nfs_client and
then drop the spin_lock if it sees that it needs to create or destroy a
dentry?

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust at netapp.com
www.netapp.com