vfs: switch ->show_devname() to struct dentry *

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b2e4b6f..a8dff43 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1673,7 +1673,7 @@
 	void (*umount_begin) (struct super_block *);
 
 	int (*show_options)(struct seq_file *, struct vfsmount *);
-	int (*show_devname)(struct seq_file *, struct vfsmount *);
+	int (*show_devname)(struct seq_file *, struct dentry *);
 	int (*show_path)(struct seq_file *, struct vfsmount *);
 	int (*show_stats)(struct seq_file *, struct dentry *);
 #ifdef CONFIG_QUOTA