Taken from FreeBSD.
Index: Makefile
===================================================================
RCS file: /cvs/src/share/man/man9/Makefile,v
retrieving revision 1.171
diff -u -p -r1.171 Makefile
--- Makefile 21 Jun 2012 18:02:21 -0000 1.171
+++ Makefile 14 Sep 2012 18:06:46 -0000
@@ -373,5 +373,6 @@ MLINKS+=VOP_LOOKUP.9 VOP_ABORTOP.9 VOP_L
MLINKS+=workq_add_task.9 workq_create.9 \
workq_add_task.9 workq_queue_task.9 \
workq_add_task.9 workq_destroy.9
+MLINKS+=vhold.9 vdrop.9
.include <bsd.prog.mk>
Index: vhold.9
===================================================================
RCS file: /cvs/src/share/man/man9/vhold.9,v
retrieving revision 1.6
diff -u -p -r1.6 vhold.9
--- vhold.9 15 Dec 2009 07:34:58 -0000 1.6
+++ vhold.9 14 Sep 2012 18:06:46 -0000
@@ -38,6 +38,8 @@
.Fd #include <sys/vnode.h>
.Ft void
.Fn vhold "struct vnode *vp"
+.Ft void
+.Fn vdrop "struct vnode *vp"
.Sh DESCRIPTION
The
.Fn vhold
@@ -50,6 +52,16 @@ and
.Va v_usecount
are both zero, it will be removed from the free list and
added to the vnode hold list.
+.Pp
+The
+.Fn vdrop
+function decrements the
+.Va v_holdcnt
+of the vnode.
+If the holdcount is less than or equal to zero prior to calling
+.Fn vdrop ,
+the system will panic.
+If the vnode is no longer referenced, it will be freed.
.Sh SEE ALSO
.Xr vnode 9
.Sh AUTHORS
--
Michal Mazurek
