xref: /freebsd/share/man/man9/vget.9 (revision 1669d8afc64812c8d2d1d147ae1fd42ff441e1b1)
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.\" $FreeBSD$
30.\"
31.Dd July 24, 1996
32.Os
33.Dt VGET 9
34.Sh NAME
35.Nm vget
36.Nd get a vnode from the free list
37.Sh SYNOPSIS
38.In sys/param.h
39.In sys/vnode.h
40.Ft int
41.Fn vget "struct vnode *vp" "int lockflag" "struct thread *td"
42.Sh DESCRIPTION
43Get a vnode from the free list and increment its reference count.
44.Bl -tag -width lockflag
45.It Fa vp
46The vnode to remove from the free list.
47.It Fa lockflag
48If non-zero, the vnode will also be locked.
49.El
50.Pp
51When not in use, vnodes are kept on a free list.
52The vnodes still
53reference valid files but may be reused to refer to a new file at any
54time.
55Often, these vnodes are also held in caches in the system, such
56as the name cache.
57.Pp
58When a vnode which is on the free list is used again, for instance if
59the vnode was found in the name cache as a result of a call to
60.Xr VOP_LOOKUP 9
61then the new user must call
62.Fn vget
63to increment the reference count and remove it from the free list.
64.Sh SEE ALSO
65.Xr vnode 9 ,
66.Xr vput 9 ,
67.Xr vref 9 ,
68.Xr vrele 9
69.Sh AUTHORS
70This manual page was written by
71.An Doug Rabson .
72