net: Export open_related_ns()

This function will be used to obtain net of tun device.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 36b0772..60702d6 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -184,6 +184,7 @@
 
 	return fd;
 }
+EXPORT_SYMBOL_GPL(open_related_ns);
 
 static long ns_ioctl(struct file *filp, unsigned int ioctl,
 			unsigned long arg)