nfsd: fsnotify on rmdir under nfsd/clients/

Userspace should be able to monitor nfsd/clients/ to see when clients
come and go, but we're failing to send fsnotify events.

Cc: stable@kernel.org
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfsctl.c

@@ -1333,6 +1333,7 @@ void nfsd_client_rmdir(struct dentry *dentry)
 	dget(dentry);
 	ret = simple_rmdir(dir, dentry);
 	WARN_ON_ONCE(ret);
+	fsnotify_rmdir(dir, dentry);
 	d_delete(dentry);
 	inode_unlock(dir);
 }