1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1996 Doug Rabson 4.\" Copyright (c) 2010 Konstantin Belousov <kib@FreeBSD.org> 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.Dd February 24, 2016 31.Dt VRELE 9 32.Os 33.Sh NAME 34.Nm vput , 35.Nm vrele , 36.Nm vunref 37.Nd decrement the use count for a vnode 38.Sh SYNOPSIS 39.In sys/param.h 40.In sys/vnode.h 41.Ft void 42.Fn vput "struct vnode *vp" 43.Ft void 44.Fn vrele "struct vnode *vp" 45.Ft void 46.Fn vunref "struct vnode *vp" 47.Sh DESCRIPTION 48Decrement the 49.Va v_usecount 50field of a vnode. 51.Bl -tag -width 2n 52.It Fa vp 53the vnode to decrement 54.El 55.Pp 56The 57.Fn vrele 58function takes an unlocked vnode and returns with the vnode unlocked. 59.Pp 60The 61.Fn vput 62function should be given a locked vnode as argument, the vnode is unlocked 63after the function returned. 64The 65.Fn vput 66is operationally equivalent to calling 67.Xr VOP_UNLOCK 9 68followed by 69.Fn vrele , 70with less overhead. 71.Pp 72The 73.Fn vunref 74function takes a locked vnode as argument, and returns with the vnode locked. 75.Pp 76Any code in the system which signified its use of a vnode by usecount 77should call one of the listed function to decrement use counter. 78If the 79.Va v_usecount 80field of the non-doomed vnode reaches zero, then it will be inactivated 81and placed on the free list. 82.Pp 83The 84.Fn vrele 85function may lock the vnode. 86All three functions may sleep. 87.Pp 88The hold count for the vnode is always greater or equal to the usecount. 89Non-forced unmount fails when mount point owns a vnode that has non-zero 90usecount, see 91.Xr vflush 9 . 92.Sh SEE ALSO 93.Xr vget 9 , 94.Xr vnode 9 , 95.Xr vref 9 , 96.Xr vrefcnt 9 97.Sh AUTHORS 98This manual page was written by 99.An Doug Rabson 100and 101.An Konstantin Belousov . 102