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+.\" -*- nroff -*-
+.\"
+.\" Copyright (c) 1996 Doug Rabson
+.\"
+.\" All rights reserved.
+.\"
+.\" This program is free software.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd July 24, 1996
+.Os
+.Dt VREF 9
+.Sh NAME
+.Nm vref
+.Nd increment the use count for a vnode
+.Sh SYNOPSIS
+.In sys/param.h
+.In sys/vnode.h
+.Ft void
+.Fn vref "struct vnode *vp"
+.Sh DESCRIPTION
+Increment the
+.Va v_usecount
+field of a vnode.
+.Bl -tag -width 2n
+.It Fa vp
+the vnode to increment
+.El
+.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 is using 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 vrefcnt 9 ,
+.Xr vrele 9
+.Sh AUTHORS
+This manual page was written by
+.An Doug Rabson .