1.\" $OpenBSD: vref.9,v 1.3 2003/06/06 20:56:32 jmc Exp $ 2.\" -*- nroff -*- 3.\" 4.\" Copyright (c) 1996 Doug Rabson 5.\" 6.\" All rights reserved. 7.\" 8.\" This program is free software. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 20.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 23.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" $FreeBSD: src/share/man/man9/vref.9,v 1.8 2001/10/01 16:09:25 ru Exp $ 31.\" 32.Dd July 24, 1996 33.Os 34.Dt VREF 9 35.Sh NAME 36.Nm vref 37.Nd increment the use count for a vnode 38.Sh SYNOPSIS 39.Fd #include <sys/param.h> 40.Fd #include <sys/vnode.h> 41.Ft void 42.Fn vref "struct vnode *vp" 43.Sh DESCRIPTION 44Increment the 45.Dv v_usecount 46field of a vnode. 47.Bl -tag -width 2n 48.It Ar vp 49the vnode to increment 50.El 51.Pp 52Each vnode maintains a reference count of how many parts of the system 53are using the vnode. 54This allows the system to detect when a vnode is 55no longer being used and can be safely recycled for a different file. 56.Pp 57Any code in the system which is using a vnode (e.g. during the 58operation of some algorithm or to store in a data structure) should 59call 60.Fn vref . 61.Sh SEE ALSO 62.Xr vget 9 , 63.Xr vnode 9 , 64.Xr vput 9 , 65.Xr vrele 9 66.Sh AUTHORS 67This man page was originally written by 68.An Doug Rabson 69for 70.Fx . 71