xref: /freebsd/share/man/man9/vget.9 (revision cbb3ec25236ba72f91cbdf23f8b78b9d1af0cedf)
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 July 24, 1996
30.Dt VGET 9
31.Os
32.Sh NAME
33.Nm vget
34.Nd get a vnode from the free list
35.Sh SYNOPSIS
36.In sys/param.h
37.In sys/vnode.h
38.Ft int
39.Fn vget "struct vnode *vp" "int lockflag" "struct thread *td"
40.Sh DESCRIPTION
41Get a vnode from the free list and increment its reference count.
42.Bl -tag -width lockflag
43.It Fa vp
44The vnode to remove from the free list.
45.It Fa lockflag
46If non-zero, the vnode will also be locked.
47.El
48.Pp
49When not in use, vnodes are kept on a free list.
50The vnodes still
51reference valid files but may be reused to refer to a new file at any
52time.
53Often, these vnodes are also held in caches in the system, such
54as the name cache.
55.Pp
56When a vnode which is on the free list is used again, for instance if
57the vnode was found in the name cache as a result of a call to
58.Xr VOP_LOOKUP 9
59then the new user must call
60.Fn vget
61to increment the reference count and remove it from the free list.
62.Sh SEE ALSO
63.Xr vnode 9 ,
64.Xr vput 9 ,
65.Xr vref 9 ,
66.Xr vrele 9
67.Sh AUTHORS
68This manual page was written by
69.An Doug Rabson .
70