1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)msync.2 8.1 (Berkeley) 6/9/93 33.\" $Id: msync.2,v 1.6 1994/06/21 04:49:04 cgd Exp $ 34.\" 35.Dd June 9, 1993 36.Dt MSYNC 2 37.Os 38.Sh NAME 39.Nm msync 40.Nd synchronize a mapped region 41.Sh SYNOPSIS 42.Fn msync "caddr_t addr" "int len" 43.Sh DESCRIPTION 44The 45.Fn msync 46system call 47writes any modified pages back to the filesystem and updates 48the file modification time. 49If 50.Fa len 51is 0, all modified pages within the region containing 52.Fa addr 53will be flushed; 54if 55.Fa len 56is non-zero, only the pages containing 57.Fa addr 58and 59.Fa len 60succeeding locations will be examined. 61Any required synchronization of memory caches 62will also take place at this time. 63Filesystem operations on a file that is mapped for shared modifications 64are unpredictable except after an 65.Fn msync . 66.Sh ERRORS 67The following errors may be reported: 68.Bl -tag -width Er 69.It Bq Er EINVAL 70The 71.Fa addr 72parameter was not page aligned. 73.It Bq Er EINVAL 74The 75.Fa addr 76parameter did not specify an address part of a mapped region. 77.It Bq Er EINVAL 78The 79.Fa len 80parameter was negative. 81.It Bq Er EIO 82An I/O error occured while writing to the file system. 83.Sh SEE ALSO 84.Xr madvise 2 , 85.Xr munmap 2 , 86.Xr mprotect 2 , 87.Xr mincore 2 88.Sh HISTORY 89The 90.Fn msync 91function first appeared in 4.4BSD. 92