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.\" $FreeBSD$ 28.\" 29.Dd April 1, 2007 30.Dt VHOLD 9 31.Os 32.Sh NAME 33.Nm vhold , vdrop , vdropl 34.Nd "acquire/release a hold on a vnode" 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/vnode.h 38.Ft void 39.Fn vhold "struct vnode *vp" 40.Ft void 41.Fn vdrop "struct vnode *vp" 42.Ft void 43.Fn vdropl "struct vnode *vp" 44.Sh DESCRIPTION 45The 46.Fn vhold 47function increments the 48.Va v_holdcnt 49of the given vnode. 50If the vnode has already been added to the free list and is still referenced, 51it will be removed. 52.Pp 53The 54.Fn vdrop 55and 56.Fn vdropl 57functions decrement the 58.Va v_holdcnt 59of the vnode. 60If the holdcount is less than or equal to zero prior to calling 61.Fn vdrop 62or 63.Fn vdropl , 64the system will panic. 65If the vnode is no longer referenced, it will be freed. 66.Pp 67The difference between 68.Fn vdrop 69and 70.Fn vdropl 71is that 72.Fn vdrop 73locks the vnode interlock and then calls 74.Fn vdropl 75while 76.Fn vdropl 77expects the interlock to already be locked. 78.Sh SEE ALSO 79.Xr vbusy 9 , 80.Xr vfree 9 81.Sh AUTHORS 82This manual page was written by 83.An Chad David Aq davidc@acns.ab.ca . 84