Correct module count in do_mount()

If do_mount() fails in the wrong place, the filesystem module count is incremented twice, but decremented only once.

This patch agains 2.4.2 fixes the problem.

Jörgen

@@ -1414,6 +1414,8 @@
 fail:
 	if (list_empty(&sb->s_mounts))
 		kill_super(sb, 0);
+	else
+		put_filesystem(fstype);
 	goto unlock_out;
 }