diff --git a/Documentation/ioctl-number.txt b/Documentation/ioctl-number.txt
index 5c7fbf9..c18363b 100644
--- a/Documentation/ioctl-number.txt
+++ b/Documentation/ioctl-number.txt
@@ -138,6 +138,7 @@
 'm'	00-1F	net/irda/irmod.h	conflict!
 'n'	00-7F	linux/ncp_fs.h
 'n'	E0-FF	video/matrox.h          matroxfb
+'o'	00-1F	fs/ocfs2/ocfs2_fs.h	OCFS2
 'p'	00-0F	linux/phantom.h		conflict! (OpenHaptics needs this)
 'p'	00-3F	linux/mc146818rtc.h	conflict!
 'p'	40-7F	linux/nvram.h