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.\" @(#)msync.2 8.2 (Berkeley) 6/21/94 33.\" $FreeBSD: src/lib/libc/sys/msync.2,v 1.16.2.5 2001/12/14 18:34:01 ru Exp $ 34.\" 35.Dd June 21, 1994 36.Dt MSYNC 2 37.Os 38.Sh NAME 39.Nm msync 40.Nd synchronize a mapped region 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In sys/types.h 45.In sys/mman.h 46.Ft int 47.Fn msync "void *addr" "size_t len" "int flags" 48.Sh DESCRIPTION 49The 50.Fn msync 51system call 52writes any modified pages back to the filesystem and updates 53the file modification time. 54If 55.Fa len 56is 0, all modified pages within the region containing 57.Fa addr 58will be flushed; 59if 60.Fa len 61is non-zero, only those pages containing 62.Fa addr 63and 64.Fa len-1 65succeeding locations will be examined. 66The 67.Fa flags 68argument may be specified as follows: 69.Bd -literal 70MS_ASYNC Return immediately 71MS_SYNC Perform synchronous writes 72MS_INVALIDATE Invalidate all cached data 73.Ed 74.Sh RETURN VALUES 75.Rv -std msync 76.Sh ERRORS 77.Fn msync 78will fail if: 79.Bl -tag -width Er 80.It Bq Er EINVAL 81.Fa addr 82is not a multiple of the hardware page size. 83.It Bq Er EINVAL 84.Fa len 85is too large or negative. 86.It Bq Er EINVAL 87.Fa flags 88was both MS_ASYNC and MS_INVALIDATE. 89Only one of these flags is allowed. 90.It Bq Er EIO 91An I/O error occurred while writing to the file system. 92.El 93.Sh SEE ALSO 94.Xr madvise 2 , 95.Xr mincore 2 , 96.Xr mprotect 2 , 97.Xr munmap 2 98.Sh HISTORY 99The 100.Fn msync 101function first appeared in 102.Bx 4.4 . 103