.\"     $OpenBSD: vref.9,v 1.7 2010/10/28 18:27:29 jmc Exp $
.\"
.\" Copyright (c) 1996 Doug Rabson
.\"
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.\" This program is free software.
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.\" $FreeBSD: src/share/man/man9/vref.9,v 1.8 2001/10/01 16:09:25 ru Exp $
.\"
.Dd $Mdocdate: October 28 2010 $
.Dt VREF 9
.Os
.Sh NAME
.Nm vref
.Nd increment the use count for a vnode
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/vnode.h>
.Ft void
.Fn vref "struct vnode *vp"
.Sh DESCRIPTION
Increment the
.Va v_usecount
field of the vnode specified by
.Fa vp .
.Pp
Each vnode maintains a reference count of how many parts of the system
are using the vnode.
This allows the system to detect when a vnode is
no longer being used and can be safely recycled for a different file.
.Pp
Any code in the system which uses a vnode (e.g. during the
operation of some algorithm or to store in a data structure) should
call
.Fn vref .
.Sh SEE ALSO
.Xr vget 9 ,
.Xr vnode 9 ,
.Xr vput 9 ,
.Xr vrele 9
.Sh AUTHORS
This man page was originally written by
.An Doug Rabson
for
.Fx .