1.\" 2.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 16.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 19.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25.\" DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man9/vhold.9,v 1.4 2005/07/22 00:28:22 rodrigc Exp $ 28.\" $DragonFly: src/share/man/man9/vhold.9,v 1.4 2007/05/11 08:25:24 swildner Exp $ 29.\" 30.Dd May 5, 2007 31.Dt VHOLD 9 32.Os 33.Sh NAME 34.Nm vhold , vdrop 35.Nd "Acquire/release an auxiliary reference on a vnode" 36.Sh SYNOPSIS 37.In sys/param.h 38.In sys/vnode.h 39.Ft void 40.Fn vhold "struct vnode *vp" 41.Ft void 42.Fn vdrop "struct vnode *vp" 43.Sh DESCRIPTION 44The 45.Fn vhold 46function acquires an auxiliary reference on a vnode by incrementing the 47.Fa v_auxrefs 48field. 49Auxiliary references do not reactivate a vnode or move it to the cache 50if it resides on the free list, but they will prevent the vnode from 51being recycled (if not already being recycled), or reused. 52Auxiliary references are used to associate auxiliary structures such as 53namecache records with the vnode for those cases where the intent is to 54not allow the vnode to be immediately recycled. 55Auxiliary references are also used to access a vnode via an auxiliary 56structure without having to hold a deep stack of locks that might 57create deadlock issues for the caller. 58.Pp 59The 60.Fn vdrop 61function decrements the 62.Fa v_auxrefs 63field. If the vnode has been deactivated and resides in the cache, 64it will be moved to the free list when 65.Fa v_auxrefs 66drops to 0. 67.Sh SEE ALSO 68.Xr vget 9 , 69.Xr vnode 9 , 70.Xr vn_lock 9 , 71.Xr vn_unlock 9 , 72.Xr vput 9 , 73.Xr vref 9 , 74.Xr vrele 9 75.Sh AUTHORS 76This manual page was written by 77.An Chad David Aq davidc@acns.ab.ca . 78