89 lines
2.9 KiB
Groff
89 lines
2.9 KiB
Groff
|
.\" -*- nroff -*-
|
||
|
|
.\"
|
||
|
|
.\" Copyright (c) 2013 Advanced Computing Technologies LLC
|
||
|
|
.\" Written by: John H. Baldwin <jhb@FreeBSD.org>
|
||
|
|
.\" All rights reserved.
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" $FreeBSD$
|
||
|
|
.\"
|
||
|
|
.Dd October 3, 2013
|
||
|
|
.Dt VOP_ADVISE 9
|
||
|
|
.Os
|
||
|
|
.Sh NAME
|
||
|
|
.Nm VOP_ADVISE
|
||
|
|
.Nd apply advice about use of file data
|
||
|
|
.Sh SYNOPSIS
|
||
|
|
.In sys/param.h
|
||
|
|
.In sys/vnode.h
|
||
|
|
.Ft int
|
||
|
|
.Fn VOP_ADVISE "struct vnode *vp" "off_t start" "off_t end" "int advice"
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
This call applies advice for a range of a file's data.
|
||
|
|
It is used to implement the
|
||
|
|
.Xr posix_fadvise
|
||
|
|
system call.
|
||
|
|
.Pp
|
||
|
|
Its arguments are:
|
||
|
|
.Bl -tag -width offset
|
||
|
|
.It Fa vp
|
||
|
|
The vnode of the file.
|
||
|
|
.It Fa start
|
||
|
|
The start of the range of file data.
|
||
|
|
.It Fa end
|
||
|
|
The end of the range of file data.
|
||
|
|
.It Fa advice
|
||
|
|
The type of operation to apply to the file data.
|
||
|
|
Possible values are:
|
||
|
|
.Bl -tag -width POSIX_FADV_WILLNEED
|
||
|
|
.It Dv POSIX_FADV_WILLNEED
|
||
|
|
Initiate an asynchronous read of the file data if it is not already resident.
|
||
|
|
.It Dv POSIX_FADV_DONTNEED
|
||
|
|
Decrease the in-memory priority of clean file data or discard clean file data.
|
||
|
|
.El
|
||
|
|
.El
|
||
|
|
.Pp
|
||
|
|
If the
|
||
|
|
.Fa start
|
||
|
|
and
|
||
|
|
.Fa end
|
||
|
|
offsets are both zero,
|
||
|
|
then the operation should be applied to the entire file.
|
||
|
|
Note that this call is advisory only and may perform the requested
|
||
|
|
operation on a subset of the requested range
|
||
|
|
.Pq including not performing it at all
|
||
|
|
and still return success.
|
||
|
|
.Sh LOCKS
|
||
|
|
The file should be unlocked on entry.
|
||
|
|
.Sh RETURN VALUES
|
||
|
|
Zero is returned if the call is successful, otherwise an appropriate
|
||
|
|
error code is returned.
|
||
|
|
.Sh ERRORS
|
||
|
|
.Bl -tag -width Er
|
||
|
|
.It Bq Er EINVAL
|
||
|
|
An invalid value was given for
|
||
|
|
.Fa advice .
|
||
|
|
.El
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Xr vnode 9
|