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