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.\" $DragonFly: src/lib/libc/sys/msync.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd June 21, 1994 37.Dt MSYNC 2 38.Os 39.Sh NAME 40.Nm msync 41.Nd synchronize a mapped region 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In sys/types.h 46.In sys/mman.h 47.Ft int 48.Fn msync "void *addr" "size_t len" "int flags" 49.Sh DESCRIPTION 50The 51.Fn msync 52system call 53writes any modified pages back to the filesystem and updates 54the file modification time. 55If 56.Fa len 57is 0, all modified pages within the region containing 58.Fa addr 59will be flushed; 60if 61.Fa len 62is non-zero, only those pages containing 63.Fa addr 64and 65.Fa len-1 66succeeding locations will be examined. 67The 68.Fa flags 69argument may be specified as follows: 70.Bd -literal 71MS_ASYNC Return immediately 72MS_SYNC Perform synchronous writes 73MS_INVALIDATE Invalidate all cached data 74.Ed 75.Sh RETURN VALUES 76.Rv -std msync 77.Sh ERRORS 78.Fn msync 79will fail if: 80.Bl -tag -width Er 81.It Bq Er EINVAL 82.Fa addr 83is not a multiple of the hardware page size. 84.It Bq Er EINVAL 85.Fa len 86is too large or negative. 87.It Bq Er EINVAL 88.Fa flags 89was both MS_ASYNC and MS_INVALIDATE. 90Only one of these flags is allowed. 91.It Bq Er EIO 92An I/O error occurred while writing to the file system. 93.El 94.Sh SEE ALSO 95.Xr madvise 2 , 96.Xr mincore 2 , 97.Xr mprotect 2 , 98.Xr munmap 2 99.Sh HISTORY 100The 101.Fn msync 102function first appeared in 103.Bx 4.4 . 104