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 1.17 2000/04/21 09:41:53 phantom 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.Fd #include <sys/mman.h> 45.Ft int 46.Fo msync 47.Fa "void *addr" 48.Fa "size_t len" 49.Fa "int flags" 50.Fc 51.Sh DESCRIPTION 52The 53.Fn msync 54system call writes modified whole pages back to the filesystem 55and updates the file modification time. 56Only those pages containing 57.Fa addr 58and 59.Fa len-1 60succeeding locations will be examined. 61.Pp 62The 63.Fa flags 64argument may be specified as follows: 65.Bd -literal 66MS_ASYNC Return immediately 67MS_SYNC Perform synchronous writes 68MS_INVALIDATE Invalidate all cached data 69.Ed 70.Pp 71The 72.Fa MS_ASYNC 73flag is not permitted to be combined with other flags. 74.Sh RETURN VALUES 75If any errors occur, -1 is returned and errno is set to indicate the 76error. 77Otherwise, a 0 value is returned. 78.Sh ERRORS 79.Fn msync 80will fail if: 81.Bl -tag -width Er 82.\" =========== 83.It Bq Er EBUSY 84Some of the specified addresses are locked 85and MS_INVALIDATE is specified. 86.\" =========== 87.It Bq Er EINVAL 88.Fa addr 89is not a multiple of the hardware page size. 90.\" =========== 91.It Bq Er EINVAL 92.Fa len 93is too large, or less than 1. 94.\" =========== 95.It Bq Er EINVAL 96.Fa flags 97is invalid 98(e.g., it combines MS_ASYNC with another flag, 99which is not permitted). 100.\" =========== 101.It Bq Er EIO 102An I/O error occurs while writing to the file system. 103.\" =========== 104.It Bq Er ENOMEM 105The specified address range is outside of the address range 106of the process or includes an unmapped page. 107.El 108.Sh LEGACY SYNOPSIS 109.Fd #include <sys/types.h> 110.Fd #include <sys/mman.h> 111.Pp 112The include file 113.In sys/types.h 114is necessary. 115.Sh SEE ALSO 116.Xr madvise 2 , 117.Xr mincore 2 , 118.Xr mprotect 2 , 119.Xr munmap 2 , 120.Xr compat 5 121.Sh HISTORY 122The 123.Fn msync 124function first appeared in 125.Bx 4.4 . 126