Copyright (c) 2013 Hudson River Trading 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: stable/10/share/man/man9/VOP_ADVISE.9 283927 2015-06-02 19:20:39Z jhb $
.Dd October 3, 2013 .Dt VOP_ADVISE 9 .Os .Sh NAME .Nm VOP_ADVISE .Nd apply advice about use of file data .Sh SYNOPSIS n sys/param.h n 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.
p Its arguments are: l -tag -width offset t Fa vp The vnode of the file. t Fa start The start of the range of file data. t Fa end The end of the range of file data. t Fa advice The type of operation to apply to the file data. Possible values are: l -tag -width POSIX_FADV_WILLNEED t Dv POSIX_FADV_WILLNEED Initiate an asynchronous read of the file data if it is not already resident. t Dv POSIX_FADV_DONTNEED Decrease the in-memory priority of clean file data or discard clean file data. .El .El
p 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
q 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 l -tag -width Er t Bq Er EINVAL An invalid value was given for .Fa advice . .El .Sh SEE ALSO .Xr vnode 9