OpenBSD-4.6/share/man/man9/vget.9

.\"     $OpenBSD: vget.9,v 1.8 2007/05/31 19:20:01 jmc Exp $
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.\" Copyright (c) 1996 Doug Rabson
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.\" $FreeBSD: src/share/man/man9/vget.9,v 1.7 2001/12/26 23:14:04 davidc Exp $
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.Dd $Mdocdate: May 31 2007 $
.Os
.Dt VGET 9
.Sh NAME
.Nm vget
.Nd get a vnode from the free list
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/vnode.h>
.Ft int
.Fn vget "struct vnode *vp" "int flags" "struct proc *p"
.Sh DESCRIPTION
Get a vnode from the free list and increment its reference count.
.Pp
Its arguments are:
.Bl -tag -width flags
.It Fa vp
The vnode to remove from the free list.
.It Fa flags
If non-zero, the vnode will also be locked.
.It Fa p
The process responsible for this call.
.El
.Pp
When not in use, vnodes are kept on a free list.
The vnodes still
reference valid files but may be reused to refer to a new file at any
time.
Often, these vnodes are also held in caches in the system, such
as the name cache.
.Pp
When a vnode which is on the free list is used again, for instance if
the vnode was found in the name cache as a result of a call to
.Xr VOP_LOOKUP 9 ,
then the new user must call
.Fn vget
to increment the reference count and remove it from the free list.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOENT
The vnode
.Fa vp
is in the process of being cleaned out from the underlying
file system.
.It Bq Er EBUSY
The vnode
.Fa vp
is in the process of being cleaned out from the underlying file system, and
it wasn't possible to sleep on it because the
.Dv LK_NOWAIT
flag was specified.
.El
.Sh SEE ALSO
.Xr vnode 9 ,
.Xr vput 9 ,
.Xr vref 9 ,
.Xr vrele 9
.Sh AUTHORS
This man page was originally written by
.An Doug Rabson
for
.Fx .