1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1996 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.Dd January 18, 2016 30.Dt VREF 9 31.Os 32.Sh NAME 33.Nm vref , vrefl 34.Nd increment the use count for a vnode 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/vnode.h 38.Ft void 39.Fn vref "struct vnode *vp" 40.Ft void 41.Fn vrefl "struct vnode *vp" 42.Sh DESCRIPTION 43Increment the 44.Va v_usecount 45field of a vnode. 46.Bl -tag -width 2n 47.It Fa vp 48the vnode to increment 49.El 50.Pp 51Each vnode maintains a reference count of how many parts of the system 52are using the vnode. 53This allows the system to detect when a vnode is 54no longer being used and can be safely recycled for a different file. 55.Pp 56Any code in the system which is using a vnode (e.g.\& during the 57operation of some algorithm or to store in a data structure) should 58call 59.Fn vref 60or 61.Fn vrefl . 62.Pp 63.Fn vref 64locks the vnode interlock while 65.Fn vrefl 66expects the interlock to already be held. 67.Sh SEE ALSO 68.Xr vget 9 , 69.Xr vnode 9 , 70.Xr vput 9 , 71.Xr vrefcnt 9 , 72.Xr vrele 9 73.Sh AUTHORS 74This manual page was written by 75.An Doug Rabson . 76